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Diagnostic Accuracy of Mammography, Clinical Examination, US, and MR Imaging in Preoperative Assessment of Breast Cancer¹

¹ From American College of Radiology Imaging Network, 301 Merrie Hunt Dr, Lutherville, MD 21093 (W.A.B.); Corporacion Nacional del Cancer, Santiago, Chile (L.G.); Departments of Radiology (M.S.N.), Surgery (W.B.C.), and Pathology (O.B.I.), University of Maryland, Baltimore; and American College of Radiology Technology Assessment Studies Assistance Program, Reston, Va (M.B., R.S.L.). From the 2001 RSNA scientific assembly. Received September 15, 2003; revision requested November 28; revision received March 5, 2004; accepted April 12. Supported by a grant from the Society of Breast Imaging. Address correspondence to W.A.B. (e-mail: wendieberg@hotmail.com).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
PURPOSE: To prospectively assess accuracy of mammography, clinical examination, ultrasonography (US), and magnetic resonance (MR) imaging in preoperative assessment of local extent of breast cancer.

MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. Results of bilateral mammography, US, and contrast-enhanced MR imaging were analyzed from 111 consecutive women with known or suspected invasive breast cancer. Results were correlated with histopathologic findings.

RESULTS: Analysis included 177 malignant foci in 121 cancerous breasts, of which 89 (50%) foci were palpable. Median size of 139 invasive foci was 18 mm (range, 2–107 mm). Mammographic sensitivity decreased from 100% in fatty breasts to 45% in extremely dense breasts. Mammographic sensitivity was highest for invasive ductal carcinoma (IDC) in 89 of 110 (81%) cases versus 10 of 29 (34%) cases of invasive lobular carcinoma (ILC) (P < .001) and 21 of 38 (55%) cases of ductal carcinoma in situ (DCIS) (P < .01). US showed higher sensitivity than did mammography for IDC, depicting 104 of 110 (94%) cases, and for ILC, depicting 25 of 29 (86%) cases (P < .01 for each). US showed higher sensitivity for invasive cancer than DCIS (18 of 38 [47%], P < .001). MR showed higher sensitivity than did mammography for all tumor types (P < .01) and higher sensitivity than did US for DCIS (P < .001), depicting 105 of 110 (95%) cases of IDC, 28 of 29 (96%) cases of ILC, and 34 of 38 (89%) cases of DCIS. In anticipation of conservation or no surgery after mammography and clinical examination in 96 breasts, additional tumor (which altered surgical approach) was present in 30. Additional tumor was depicted in 17 of 96 (18%) breasts at US and in 29 of 96 (30%) at MR, though extent was now overestimated in 12 of 96 (12%) at US and 20 of 96 (21%) at MR imaging. After combined mammography, clinical examination, and US, MR depicted additional tumor in another 12 of 96 (12%) breasts and led to overestimation of extent in another six (6%); US showed no detection benefit after MR imaging. Bilateral cancer was present in 10 of 111 (9%) patients; contralateral tumor was depicted mammographically in six and with both US and MR in an additional three. One contralateral cancer was demonstrated only clinically.

CONCLUSION: In nonfatty breasts, US and MR imaging were more sensitive than mammography for invasive cancer, but both MR imaging and US involved risk of overestimation of tumor extent. Combined mammography, clinical examination, and MR imaging were more sensitive than any other individual test or combination of tests.

© RSNA, 2004

Index terms: Breast, abnormalities • Breast, MR, 00.121412, 00.121413, 00.121415, 00.12143 • Breast, US, 00.1298 • Breast neoplasms, radiography, 00.115

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
With increasing use of reliable percutaneous biopsy techniques, a current goal in breast cancer management is accurate pretreatment planning to allow neoadjuvant chemotherapy or asingle definitive surgical procedure with lymph node sampling, as appropriate. Complete excision of malignant foci is the standard, with the goal of achieving clear margins of excision.

The sensitivity of mammography to the index cancer ranges from 63% to 98% (1–3) and has been reported to be as low as 30%–48% in dense breasts (4,5). Several groups have evaluated the preoperative use of supplemental magnetic resonance (MR) imaging (6–8), ultrasonography (US) (9,10), or both (11,12) after mammography and clinical breast examination to assess the extent of disease within the breast(s). Across these series, a change in management in 11%–15% of patients resulted from additional imaging after mammography; 27%–34% of breasts had additional malignant foci not seen mammographically (6–10,12,13). The purpose of our study was to prospectively assess the accuracy of mammography, clinical examination, US, and MR imaging in the preoperative assessment of the local extent of breast cancer. We further sought to determine whether the accuracy of detection methods varied with breast density or tumor type.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Entrance criteria consisted of women older than 18 years with newly diagnosed invasive breast cancer by means of core biopsy and/or high clinical or mammographic suspicion of invasive breast cancer. Women ultimately shown to have ductal carcinoma in situ (DCIS) either had a larger area of calcifications (>2.5 cm) mammographically or a mass (either clinically or at imaging) and were therefore suspected of having an invasive component. Consecutive patients at the University of Maryland were recruited from September 1999 through January 2002. Women had to (a) agree to undergo bilateral mammography, whole-breast US, and contrast material–enhanced MR imaging of the breasts according to an institutional review board–approved protocol and (b) provide informed consent. Women who were unable to provide consent or undergo MR imaging because of a pacemaker, an aneurysm clip, or a metallic foreign body in or near the eye were excluded, as were patients who had undergone open biopsy before mammography, US, and MR imaging could be performed.

Imaging and Clinical Examination Techniques
Bilateral mammography was performed (Lo-Rad MIV unit, Hologic, Danbury, Conn, or DMR Plus, GE Medical Systems, Milwaukee, Wis) and included routine craniocaudal and mediolateral oblique views of the breast(s) and spot- or global-magnification views over the area of the cancer. Findings were recorded prospectively according to the Breast Imaging Reporting and Data System , or BI-RADS, lexicon (14) by one of several interpreting radiologists (including W.A.B.) who were qualified according to the Mammography Quality Standards Act and had 2–10 years of experience in mammography. Findings ipsilateral to the cancer, which were mammographically probably benign, suspicious for cancer, or highly suggestive of malignancy, were sampled for biopsy if the patient was a candidate for conservation and if the identification of a malignancy at that site would change the surgical approach. Contralateral findings suspicious for or highly suggestive of malignancy were sampled for biopsy. Mammography had to be performed within 6 weeks of the other imaging studies.

Clinical breast examination was performed by one of two radiologists (including W.A.B.) with 2–10 years of experience in clinical examination at the time of whole-breast US. Any palpable lumps in the breast(s) or axilla, skin thickening or retraction, and nipple discharge or retraction were noted.

Bilateral whole-breast US was performed with knowledge of clinical and mammographic findings either prior to MR imaging or afterward. US was performed by one of two radiologists (including W.A.B.) with 2–10 years of experience in the performance and interpretation of breast US, who were blinded to MR imaging results (US results were recorded prospectively). By using a linear-array broadband transducer with a center frequency of 10 MHz, US was performed and supplemented with a linear-array transducer with a center frequency of 7.5 MHz as needed to penetrate larger breasts (Acoustic Imaging Performa, Tempe, Ariz, or Elegra, Siemens, Issaquah, Wash). For the inner breast, scanning was performed with the patient in the supine position. For the outer breast, the patient was placed in the contralateral posterior oblique position with the ipsilateral arm raised. Survey scanning was performed in transverse and sagittal planes. Discrete lesions were measured in both radial and antiradial scanning planes. When multiple suspicious lesions were identified, panoramic display was used whenever possible to document the distance between lesions. Spatial compounding was intermittently used in 20 cases.

Images and perpendicular measurements were documented for all discrete findings other than simple cysts. Biopsy was recommended for all palpable solid masses and for incidental solid masses unless they were (a) circumscribed, oval, uniformly hypoechoic with no posterior features, and nonpalpable or (b) nonpalpable complicated cysts. The latter two classes of lesions were classified as probably benign at US and were recommended for short-interval (6-month) follow-up. If such lesions corresponded to suspicious findings at MR imaging, then biopsy was performed, but the US classification remained probably benign for purposes of analysis. Solid lesions that would otherwise have been considered probably benign but were ipsilateral to cancers were aspirated or sampled for biopsy if a malignant result would change the surgical approach.

MR imaging was performed with the patient in the prone position in a dedicated phased-array breast coil. A 1.5-T (n = 30) or 1.0-T (n = 81) imager (Philips/Marconi Medical Systems, Cleveland, Ohio) was used. Transverse T1-weighted MR images (repetition time msec/echo time msec, 718/14; two signals acquired; field of view, 32–40 cm; section thickness, 5 mm) were obtained in both breasts, followed by sagittal T2-weighted fat-suppressed (6700–7072/68–88; two signals acquired; field of view, 18 cm; section thickness, 4 mm) images at 1.5 T or inversion-recovery (7100/90/90 [inversion time]; flip angle, 90°; one signal acquired; field of view, 18 cm; section thickness, 4 mm) images at 1.0 T acquired in each breast separately. A coronal three-dimensional T1-weighted spoiled gradient-echo volume acquisition (10/3.6; flip angle, 30°; field of view, 34–42 cm; section thickness, 2.0–2.9 mm; matrix, 192 x 256) was then obtained both prior to and then three to six times over a period of 5–8 minutes after intravenous injection of 0.1 mmol per kilogram of body weight of gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) over 20 seconds with a power injector.

Zero-filled interpolation was used for a reconstruction matrix of 512 x 512; final resolution was 1.8–2.2 mm in the phase-encoding direction by 1.5–1.9 mm in the frequency-encoding direction with 1.0–1.4-mm section thickness. The dynamic acquisition consisted of three volumes at 1.5 T and six volumes at 1.0 T obtained after administration of contrast material. The dynamic sequence was reviewed with subtraction technique and maximum intensity projection (MIP) technique.

Kinetic analysis was performed for regions of interest that were either drawn around the entire lesion (for lesions 5 mm) or based on 4 pixels within the lesion for lesions larger than 5 mm. Lesion size was measured on selected MIPs (typically those created from the second postinjection subtraction volume) in sagittal and transverse planes, and hard copies were generated for clinical use.

Morphology (15) and kinetics (16) at MR imaging were evaluated for all enhancing lesions. Enhancement in contiguity with the primary tumor was considered suspicious, regardless of size or morphology. Isolated discrete foci of enhancement that showed at least 70% increase in signal intensity over background in the first 90 seconds after injection and were at least 5 mm in size were considered suspicious unless there was (a) a benign correlate at mammography, US, or unenhanced MR imaging (eg, an intramammary lymph node of normal morphology or a fat-containing mass compatible with fat necrosis at T1-weighted MR imaging and/or at mammography) or (b) a probably benign correlate (such as clustered microcysts at inversion-recovery MR imaging and/or at US).

Lesions smaller than 5 mm with at least 70% increase in signal intensity within the first 90 seconds of injection with washout kinetics (16) were also considered suspicious. Regional areas of enhancement with at least 60% increase in signal intensity within the first 90 seconds after contrast material injection were considered suspicious for malignancy and segmental, or linear clumped enhancement was considered suspicious for DCIS, regardless of kinetics. Lesions that did not meet any of these criteria were considered probably benign, with serial 6-month follow-up MR imaging recommended. Findings were recorded prospectively.

One radiologist (W.A.B.) with 2 years of experience (prior to the study) in contrast-enhanced breast MR imaging interpretation interpreted all MR images; US images and mammograms were reviewed at the time of MR imaging interpretation, and clinical findings were known. Second-look US was performed and targeted to areas of concern on MR images when the lesion was not believed to have been identified at prospective US or mammography.

Biopsy Technique
Lesions considered suspicious for or highly suggestive of malignancy with any modality were sampled for biopsy if a malignant result would change the surgical approach. Lesions considered probably benign with any modality were sampled for biopsy if they were ipsilateral to cancer and a malignant result would change the surgical approach. If a lesion was clearly benign with any modality, it was not sampled for biopsy. Core biopsy of more than two separate areas in any given breast was performed if the lesions had a different appearance and malignant results would change the surgical approach.

Preoperative core-needle biopsy was performed with US guidance whenever possible by one of four radiologists (W.A.B.) or fellows who specialized in breast imaging and had 6 months to 10 years of experience. A 14-gauge automated biopsy gun (Monopty; Bard Urological, Covington, Ga) was used to sample lesions with US guidance with a minimum of three passes per lesion. Specimen radiography was performed according to the method of Berg et al (17). A clip (Micromark II; Biopsys division of Ethicon Endo-Surgery, Cincinnati, Ohio) was placed with US guidance for lesions 7 mm or smaller, lesions with poor conspicuity, and those depicted with only US or MR imaging. The clip was placed via an 11-gauge trochar (Bard Urological) according to the method of Kopans (18). When a clip was placed, craniocaudal and true lateral mammographic views were acquired after biopsy. Any malignant or atypical result prompted excision, as did any discordant result. Follow-up was recommended after a benign concordant result.

When a lesion was seen only mammographically and stereotactic biopsy was feasible, the patient was positioned prone on a digital stereotactic table (LoRad DSM; Hologic, Danbury, Conn). An 11-gauge probe (Biopsys division of Ethicon Endo-Surgery) was inserted, positioning was confirmed, and 12 samples were obtained in circumferential fashion with biopsies performed by one of four breast imaging radiologists (W.A.B.) with 2–10 years of experience. Specimen radiography and handling was performed as described earlier. A clip (Micromark II; Biopsys division of Ethicon Endo-Surgery) was placed in the posterior aspect of the biopsy cavity for all stereotactic biopsies.

For lesions first identified at MR imaging, mammograms were reevaluated, and second-look US was performed as needed. MR imaging–guided biopsy was available by using a breast biopsy coil (MRI Devices, Waukesha, Wis, supplied by Philips/Marconi Medical Systems). During the course of this study, no MR imaging–guided biopsies were required, since (a) the lesion could be identified with either US or mammography or (b) wide excision or mastectomy was performed according to patient and physician choice. If the lesion(s) seen only at MR imaging was not identified clearly at initial histopathologic examination, the specimen was resectioned according to the clockface location and distance from the nipple of the MR imaging–depicted abnormality (or abnormalities) after discussion between the radiologist (W.A.B.) and pathologist (O.B.I.).

Histopathologic Examination
The reference standard was detailed serial 5-mm slicing of the surgical specimen (lumpectomy or mastectomy) per the method of Egan (19). The histopathologic specimen was viewed by one of two pathologists (O.B.I.) with 3–20 years of experience in breast pathology. Invasive ductal carcinoma (IDC) was graded according to the Nottingham system (20). DCIS was graded according to the nuclear grade (20). The number of slides containing DCIS in relation to the total number of slides was recorded as a surrogate measure of histopathologic size. An extensive intraductal component (EIC) was defined as tumor with an invasive component, where at least 25% of the tumor was DCIS and there were additional discrete foci of DCIS outside the main tumor mass (21,22).

Analysis
For each imaging modality, a cancer was considered to be depicted successfully (true-positive) if it appeared to be suspicious for or highly suggestive of malignancy (14,23,24) with that modality. Lesions considered probably benign that proved to be malignant at biopsy were classified as false-negative findings for the modality (or modalities) with which they appeared probably benign (such as a cluster of punctate calcifications or a circumscribed mass at mammography, a complicated cyst at US, or a round or oval focus showing <70% enhancement at MR imaging). If a malignancy was seen only in retrospect or at repeat scanning (such as those seen at second-look US as directed by findings at MR imaging), it was classified as a false-negative finding for that modality. A modality was credited with prompting an additional unnecessary biopsy if the biopsy sample was not malignant and that tissue would otherwise not have been sampled histologically. Contralateral probably benign findings were followed at 6, 12, and 24 months. The rates of additional induced follow-up and compliance with these recommendations were recorded.

The extent of disease was classified as follows by using prospectively defined criteria. Multifocal disease was defined as multiple discrete discontinuous tumor foci within 4 cm in one breast. Multicentric disease was defined as two or more malignant foci separated by 4 cm or more in one breast (25). Disease was classified as diffuse if more than two quadrants had multiple discrete and/or contiguous tumor foci. Imaging findings could be altogether negative for cancer in that breast. Disease was considered to be underestimated with an imaging modality if the size of the cancer was underestimated by at least 2 cm or if additional malignant foci were missed that would have required a wider surgical excision. Disease was considered to be overestimated if the size of the primary tumor was overestimated by at least 2 cm or if there were additional suspicious foci that would have prompted wider surgical excision (or mastectomy) unnecessarily.

In an effort to avoid artificially inflating or deflating the performance of any imaging modality, we sought practical definitions of disease extent. All suspicious findings at imaging were evaluated histopathologically. However, since we are unaware of a circumstance whereby a breast with more than four distinct malignant foci separated by more than 5 cm total would be recommended for conservation, we considered only the performance of the imaging modality in the detection of no more than four suspicious foci in each breast, even if there were diffuse foci of tumor. Similarly, we did not specifically seek to perform core biopsy in more than four lesions per breast in any circumstance.

Statistical Methods
The sensitivity and accuracy of extent determination with each modality for each tumor type were compared with the sensitivity and accuracy of extent determination with mammography by using the McNemar test and t tests to determine statistical significance. The McNemar test was performed for comparisons of the same group of cases or matched pairs of patients when comparing how different imaging modalities performed in the same group of cases. t tests were performed in separate groups of cases—for example, when comparing across cancer types within the same imaging modality.

The corresponding rates for each imaging modality combination were compared with the rates for mammography and clinical examination by using t tests. Independent comparisons were evaluated with the ² test. The ² test was also used to evaluate the effect of breast density on the sensitivity of imaging modalities.

Multivariate logistic regressions were performed with SAS version 8.1 software (SAS Institute, Cary, NC). Logistic multiple regression was used to analyze the possible effect of independent variables, such as modality, tumor type, patient age, and breast density, on (a) accurate detection of the presence of cancer and (b) accurate depiction of the extent of cancer (not over- or underestimated). In addition to the use of the McNemar test when comparing matched pairs of cases, we controlled for cluster and/or dependency issues that stemmed from the presence of multiple imaging studies read in the same patient and the presence of multiple lesions by using random-effects logistic regression. We treated the variability across multiple imaging studies read in the same patient as a random effect.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
A total of 120 patients were eligible for this study. Seven did not participate because of surgeon preference (n = 3, all with fatty breasts), patient claustrophobia (n = 3), or scheduling constraints (n = 1). Results from two patients were excluded because contrast material injection failed during MR imaging (not recognized by the technologist or patient). In the 111 analyzable women enrolled in study, the mean age was 48.7 years; median age was 48 years (age range, 26–81 years). The presenting (index) lesion proved malignant in 110 of 111 (99.1%) patients (with one focus of architectural distortion yielding atypical ductal hyperplasia at excision); 80 (73%) of these 110 lesions were palpable.

A total of 258 discrete lesions, including 177 malignancies, were correlated with histopathologic findings in 121 breasts with cancer. There were 110 foci of invasive ductal cancer (including 51 foci with associated intraductal carcinoma, of which 19 had an EIC, and five had mixed IDC and invasive lobular carcinoma [ILC]), 38 foci of DCIS (not including EIC cases), 29 foci of ILC, 12 atypical lesions (all excised after initial diagnosis at core biopsy, with the same or benign results, including five atypical papillomas, three lobular carcinomas in situ, two cases of atypical lobular hyperplasia, and two cases of atypical ductal hyperplasia), and 69 concordant benign diagnoses (19 fibroadenomas, 19 fibrocystic changes, nine cases of sclerosing adenosis, seven cases of fibrosis, six papillomas, four ruptured cysts, two lymph nodes, and one case each of foreign body granuloma, chronic inflammatory changes, and lactational changes). One patient presented for evaluation of a new area of architectural distortion mammographically in one breast, which proved to be only atypical ductal hyperplasia at excision, with a contralateral tubular cancer found only at MR imaging (Fig 1).

View larger version (137K): [in this window] [in a new window] [Download PPT slide]   Figure 1a. Images in 46-year-old woman with nonpalpable 5-mm tubular carcinoma in left breast seen only at MR imaging. (a) Bilateral mediolateral oblique (MLO) and (b) spot-magnification mediolateral mammograms show subtle architectural distortion (arrow) suspicious for carcinoma in right breast, which proved to be atypical ductal hyperplasia at excision. (c) Transverse MIP reconstruction of subtracted three-dimensional spoiled gradient-echo coronal volume MR acquisition obtained 90 seconds after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine (10/3.6; flip angle, 30°; section thickness, 2.2 mm; field of view, 36 cm; 1.0 T) shows solitary intensely enhancing mass (arrowhead) in upper inner left breast and no abnormal enhancement in right breast. (d) Sagittal second-look US image (L12-7.5-MHz transducer) obtained in 10 o’clock position in left breast demonstrates irregular hypoechoic shadowing mass (arrowhead). US-guided needle localization revealed 5-mm (tubular) IDC. Patient underwent lumpectomy with radiation therapy.

View larger version (115K): [in this window] [in a new window] [Download PPT slide]   Figure 1b. Images in 46-year-old woman with nonpalpable 5-mm tubular carcinoma in left breast seen only at MR imaging. (a) Bilateral mediolateral oblique (MLO) and (b) spot-magnification mediolateral mammograms show subtle architectural distortion (arrow) suspicious for carcinoma in right breast, which proved to be atypical ductal hyperplasia at excision. (c) Transverse MIP reconstruction of subtracted three-dimensional spoiled gradient-echo coronal volume MR acquisition obtained 90 seconds after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine (10/3.6; flip angle, 30°; section thickness, 2.2 mm; field of view, 36 cm; 1.0 T) shows solitary intensely enhancing mass (arrowhead) in upper inner left breast and no abnormal enhancement in right breast. (d) Sagittal second-look US image (L12-7.5-MHz transducer) obtained in 10 o’clock position in left breast demonstrates irregular hypoechoic shadowing mass (arrowhead). US-guided needle localization revealed 5-mm (tubular) IDC. Patient underwent lumpectomy with radiation therapy.

View larger version (63K): [in this window] [in a new window] [Download PPT slide]   Figure 1c. Images in 46-year-old woman with nonpalpable 5-mm tubular carcinoma in left breast seen only at MR imaging. (a) Bilateral mediolateral oblique (MLO) and (b) spot-magnification mediolateral mammograms show subtle architectural distortion (arrow) suspicious for carcinoma in right breast, which proved to be atypical ductal hyperplasia at excision. (c) Transverse MIP reconstruction of subtracted three-dimensional spoiled gradient-echo coronal volume MR acquisition obtained 90 seconds after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine (10/3.6; flip angle, 30°; section thickness, 2.2 mm; field of view, 36 cm; 1.0 T) shows solitary intensely enhancing mass (arrowhead) in upper inner left breast and no abnormal enhancement in right breast. (d) Sagittal second-look US image (L12-7.5-MHz transducer) obtained in 10 o’clock position in left breast demonstrates irregular hypoechoic shadowing mass (arrowhead). US-guided needle localization revealed 5-mm (tubular) IDC. Patient underwent lumpectomy with radiation therapy.

View larger version (181K): [in this window] [in a new window] [Download PPT slide]   Figure 1d. Images in 46-year-old woman with nonpalpable 5-mm tubular carcinoma in left breast seen only at MR imaging. (a) Bilateral mediolateral oblique (MLO) and (b) spot-magnification mediolateral mammograms show subtle architectural distortion (arrow) suspicious for carcinoma in right breast, which proved to be atypical ductal hyperplasia at excision. (c) Transverse MIP reconstruction of subtracted three-dimensional spoiled gradient-echo coronal volume MR acquisition obtained 90 seconds after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine (10/3.6; flip angle, 30°; section thickness, 2.2 mm; field of view, 36 cm; 1.0 T) shows solitary intensely enhancing mass (arrowhead) in upper inner left breast and no abnormal enhancement in right breast. (d) Sagittal second-look US image (L12-7.5-MHz transducer) obtained in 10 o’clock position in left breast demonstrates irregular hypoechoic shadowing mass (arrowhead). US-guided needle localization revealed 5-mm (tubular) IDC. Patient underwent lumpectomy with radiation therapy.

Of the 121 breasts with cancer, 75 (62%) had solitary tumors, of which seven were classified as "diffuse" because they were larger than 7 cm. Eleven (9%) breasts had diffuse foci of cancer in multiple quadrants; 29 (24%) had multifocal cancer within 4 cm surrounding the index lesion, and six (5%) had isolated multicentric foci of cancer.

Overall Performance
Table 1 summarizes the overall performance of each of the imaging modalities and combinations of modalities. The combination of mammography, clinical examination, and MR imaging was the most sensitive, depicting 176 of 177 (99.4%) of all malignant foci. This combination was significantly better than the combination of mammography, clinical examination, and US, which depicted 165 of 177 (93.2%) foci (P < .001) (Tables 1–3). Mammography combined with clinical examination was more accurate overall than clinical examination alone (P < .001) or mammography alone (P < .001). With regard to only dense and heterogeneously dense breasts, however, the accuracy of mammography and clinical examination combined was not significantly better than that of clinical examination alone (131 of 168 [78.0%] foci vs 123 of 168 [73.2%] foci). Because of the substantial risk of false-positive findings with both US and MR imaging, the overall accuracy of US or MR imaging alone or in combination with mammography and clinical examination was no higher than the accuracy of mammography alone (Table 1).

Mammographic sensitivity was inversely related to breast density (P < .001), with 18 of 30 (60%) foci of IDC depicted in dense breasts, 31 of 36 (86%) depicted in heterogeneously dense breasts, 34 of 38 (89%) depicted in breasts with minimal scattered fibroglandular density, and six of six (100%) depicted in fatty breasts (Table 2). Of the 18 foci of IDC depicted mammographically in dense breasts, 17 (94%) were palpable. Random-effects logistic regression analysis showed that age did not affect mammographic sensitivity independent of density. Breast density did not affect the sensitivity of US or MR imaging.

Ninety-two breasts were found to have IDC; of these, 43 (47%) had associated DCIS, including 19 (21%) with EIC. Four were mixed IDC and ILC. Of the 92 breasts, six (6.5%) had "incidental" IDC at additional imaging that was not detected at either mammography or clinical examination, with two of those occult to initial US, as well. Of the 92 breasts with IDC, 14 (15%) had diffuse tumor (six according to primary tumor size larger than 7 cm and eight with diffuse foci), four (4.3%) were multicentric, 19 (21%) were multifocal, and 55 (60%) were solitary and smaller than 5 cm.

Twenty-one breasts with IDC were recommended for mastectomy on the basis of mammography and clinical examination findings; indeed, the findings in five (24%) of these 21 were ultimately overestimated not only mammographically but also on the basis of US and MR imaging findings.

Among the 72 breasts with IDC for which conservation or no surgery was planned after mammography and clinical examination, the tumor was missed altogether in six of 72 (8%) breasts, and the extent of tumor was underestimated in another 15 (21%) breasts (Table 4). Of the 15 underestimates, three (20%) were due to EIC alone, two (13%) were due to size, and 10 (67%) were due to discrete additional foci of tumor (three of which also had underestimated EIC). Thus, there were six outright misses and another 10 with missed discrete additional tumor foci, for a total of 16 breasts with missed tumor after mammography and clinical examination. This number represents 17% of the 92 breasts with IDC with additional tumor that potentially would have been missed even if clear margins of excision had been achieved, had management been based on the combination of mammography and clinical examination.

US alone (performed with knowledge of mammographic and clinical findings) was more accurate than mammography in the depiction of disease extent for IDC (P < .05), but the combination of mammography, clinical examination, and US was not significantly more accurate in the depiction of disease extent than mammography and clinical examination alone. MR imaging alone (interpreted with knowledge of mammographic and clinical findings) was more accurate than mammography in the assessment of disease extent (P < .001). The combination of mammography, clinical examination, and MR imaging provided significantly more accurate assessment of disease extent than did mammography and clinical examination alone (P < .01). The combination of mammography, clinical examination, and MR imaging left no underestimates of extent of IDC, but IDC extent was overestimated in 10 of 72 (14%) breasts after this combination of tests (Fig 2, Table 4).

View larger version (99K): [in this window] [in a new window] [Download PPT slide]   Figure 2a. Images in 43-year-old woman with nonpalpable 4-mm colloid carcinoma seen only at mammography and many bilateral fibroadenomas seen at US and MR imaging. (a) Bilateral craniocaudal mammograms and (b) spot-magnification craniocaudal mammogram show cluster of amorphous calcifications (arrowhead) in right breast yielding (colloid) IDC at stereotactic vacuum-assisted biopsy. (c) Radial sonograms (L13-7-MHz transducer) obtained in 11 o’clock position in right breast and (d) in 12 o’clock position in left breast show representative ovoid circumscribed hypoechoic masses (arrows) seen diffusely in both breasts. (e) Transverse three-dimensional MIP of subtracted coronal volume MR images obtained 90 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (5.3/2.2; section thickness, 1.8 mm; field of view, 42 cm; 1.0 T) shows diffuse bilateral intense foci of enhancement with no one dominant suspicious mass. US-guided core biopsy was performed after MR imaging of two masses in right breast and one in left breast in regions shown and yielded fibroadenomas. The known carcinoma could not be depicted clearly at US or MR imaging, though a 4-mm residual (colloid) IDC was found at excision. Patient underwent lumpectomy and radiation therapy, and other multiple bilateral masses have resolved after 36 months.

View larger version (144K): [in this window] [in a new window] [Download PPT slide]   Figure 2b. Images in 43-year-old woman with nonpalpable 4-mm colloid carcinoma seen only at mammography and many bilateral fibroadenomas seen at US and MR imaging. (a) Bilateral craniocaudal mammograms and (b) spot-magnification craniocaudal mammogram show cluster of amorphous calcifications (arrowhead) in right breast yielding (colloid) IDC at stereotactic vacuum-assisted biopsy. (c) Radial sonograms (L13-7-MHz transducer) obtained in 11 o’clock position in right breast and (d) in 12 o’clock position in left breast show representative ovoid circumscribed hypoechoic masses (arrows) seen diffusely in both breasts. (e) Transverse three-dimensional MIP of subtracted coronal volume MR images obtained 90 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (5.3/2.2; section thickness, 1.8 mm; field of view, 42 cm; 1.0 T) shows diffuse bilateral intense foci of enhancement with no one dominant suspicious mass. US-guided core biopsy was performed after MR imaging of two masses in right breast and one in left breast in regions shown and yielded fibroadenomas. The known carcinoma could not be depicted clearly at US or MR imaging, though a 4-mm residual (colloid) IDC was found at excision. Patient underwent lumpectomy and radiation therapy, and other multiple bilateral masses have resolved after 36 months.

View larger version (129K): [in this window] [in a new window] [Download PPT slide]   Figure 2c. Images in 43-year-old woman with nonpalpable 4-mm colloid carcinoma seen only at mammography and many bilateral fibroadenomas seen at US and MR imaging. (a) Bilateral craniocaudal mammograms and (b) spot-magnification craniocaudal mammogram show cluster of amorphous calcifications (arrowhead) in right breast yielding (colloid) IDC at stereotactic vacuum-assisted biopsy. (c) Radial sonograms (L13-7-MHz transducer) obtained in 11 o’clock position in right breast and (d) in 12 o’clock position in left breast show representative ovoid circumscribed hypoechoic masses (arrows) seen diffusely in both breasts. (e) Transverse three-dimensional MIP of subtracted coronal volume MR images obtained 90 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (5.3/2.2; section thickness, 1.8 mm; field of view, 42 cm; 1.0 T) shows diffuse bilateral intense foci of enhancement with no one dominant suspicious mass. US-guided core biopsy was performed after MR imaging of two masses in right breast and one in left breast in regions shown and yielded fibroadenomas. The known carcinoma could not be depicted clearly at US or MR imaging, though a 4-mm residual (colloid) IDC was found at excision. Patient underwent lumpectomy and radiation therapy, and other multiple bilateral masses have resolved after 36 months.

View larger version (131K): [in this window] [in a new window] [Download PPT slide]   Figure 2d. Images in 43-year-old woman with nonpalpable 4-mm colloid carcinoma seen only at mammography and many bilateral fibroadenomas seen at US and MR imaging. (a) Bilateral craniocaudal mammograms and (b) spot-magnification craniocaudal mammogram show cluster of amorphous calcifications (arrowhead) in right breast yielding (colloid) IDC at stereotactic vacuum-assisted biopsy. (c) Radial sonograms (L13-7-MHz transducer) obtained in 11 o’clock position in right breast and (d) in 12 o’clock position in left breast show representative ovoid circumscribed hypoechoic masses (arrows) seen diffusely in both breasts. (e) Transverse three-dimensional MIP of subtracted coronal volume MR images obtained 90 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (5.3/2.2; section thickness, 1.8 mm; field of view, 42 cm; 1.0 T) shows diffuse bilateral intense foci of enhancement with no one dominant suspicious mass. US-guided core biopsy was performed after MR imaging of two masses in right breast and one in left breast in regions shown and yielded fibroadenomas. The known carcinoma could not be depicted clearly at US or MR imaging, though a 4-mm residual (colloid) IDC was found at excision. Patient underwent lumpectomy and radiation therapy, and other multiple bilateral masses have resolved after 36 months.

View larger version (96K): [in this window] [in a new window] [Download PPT slide]   Figure 2e. Images in 43-year-old woman with nonpalpable 4-mm colloid carcinoma seen only at mammography and many bilateral fibroadenomas seen at US and MR imaging. (a) Bilateral craniocaudal mammograms and (b) spot-magnification craniocaudal mammogram show cluster of amorphous calcifications (arrowhead) in right breast yielding (colloid) IDC at stereotactic vacuum-assisted biopsy. (c) Radial sonograms (L13-7-MHz transducer) obtained in 11 o’clock position in right breast and (d) in 12 o’clock position in left breast show representative ovoid circumscribed hypoechoic masses (arrows) seen diffusely in both breasts. (e) Transverse three-dimensional MIP of subtracted coronal volume MR images obtained 90 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (5.3/2.2; section thickness, 1.8 mm; field of view, 42 cm; 1.0 T) shows diffuse bilateral intense foci of enhancement with no one dominant suspicious mass. US-guided core biopsy was performed after MR imaging of two masses in right breast and one in left breast in regions shown and yielded fibroadenomas. The known carcinoma could not be depicted clearly at US or MR imaging, though a 4-mm residual (colloid) IDC was found at excision. Patient underwent lumpectomy and radiation therapy, and other multiple bilateral masses have resolved after 36 months.

Two mastectomies were prompted only by additional imaging findings in breasts with IDC that proved to have a solitary cancer smaller than 5 cm at excision. One of these was prompted by MR imaging findings alone, and one was prompted by US and MR imaging findings. Another 13 patients chose mastectomy, which exceeded the needed surgery: Five of these women had cancer foci that were mammographically occult, and another three had index cancers at additional evaluation with MR imaging alone (n = 2) or both MR imaging and US (n = 1).

EIC.—A subset of 19 breasts with IDC had an EIC, and in 12 of these, conservation was planned on the basis of mammography and clinical examination findings. In the 19 breasts with an EIC, disease was visible mammographically in 18, and the extent of disease was underestimated by more than 2 cm with mammography in seven of those 18 (39%), compared with 15 of 73 (20%) of all other breasts with IDC, though the difference was not significant. Clinical examination was of no value in the identification of EIC. With US, in seven of 19 (37%) cases of EIC, disease extent was underestimated, though careful attention to detail allowed retrospective identification in five cases in which second-look US was performed (Fig 3). In six of 19 (32%) breasts with EIC, only MR imaging depicted the EIC; five of those six EIC cases seen only at MR imaging were in breasts in which conservation was anticipated. Findings in only one (5%) breast with EIC were underestimated at MR imaging, with the EIC seen at both mammography and US in that breast.

View larger version (130K): [in this window] [in a new window] [Download PPT slide]   Figure 3a. Images in 44-year-old woman with palpable mass in right breast due to grade II IDC with associated EIC of micropapillary type, which is best depicted with MR imaging. (a) MLO mammograms show dense parenchyma with focal asymmetry corresponding to palpable mass marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) of palpable mass in 9 o’clock position in right breast shows hypoechoic irregular mass with posterior enhancement, interpreted as solitary cancer with surrounding heterogeneous echotexture. (c) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as Fig 2) shows linear clumped enhancement (arrowheads) extending anterior and posterior to the known invasive cancer, due to extensive DCIS (EIC). A few small scattered foci of enhancement in contralateral breast were followed for 18 months and have resolved. (d) Second-look sonogram in radial orientation demonstrates hypoechoic mass with duct extension (arrowheads) and small adjacent hypoechoic masses (arrows) due to EIC. Patient opted for mastectomy.

View larger version (128K): [in this window] [in a new window] [Download PPT slide]   Figure 3b. Images in 44-year-old woman with palpable mass in right breast due to grade II IDC with associated EIC of micropapillary type, which is best depicted with MR imaging. (a) MLO mammograms show dense parenchyma with focal asymmetry corresponding to palpable mass marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) of palpable mass in 9 o’clock position in right breast shows hypoechoic irregular mass with posterior enhancement, interpreted as solitary cancer with surrounding heterogeneous echotexture. (c) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as Fig 2) shows linear clumped enhancement (arrowheads) extending anterior and posterior to the known invasive cancer, due to extensive DCIS (EIC). A few small scattered foci of enhancement in contralateral breast were followed for 18 months and have resolved. (d) Second-look sonogram in radial orientation demonstrates hypoechoic mass with duct extension (arrowheads) and small adjacent hypoechoic masses (arrows) due to EIC. Patient opted for mastectomy.

View larger version (73K): [in this window] [in a new window] [Download PPT slide]   Figure 3c. Images in 44-year-old woman with palpable mass in right breast due to grade II IDC with associated EIC of micropapillary type, which is best depicted with MR imaging. (a) MLO mammograms show dense parenchyma with focal asymmetry corresponding to palpable mass marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) of palpable mass in 9 o’clock position in right breast shows hypoechoic irregular mass with posterior enhancement, interpreted as solitary cancer with surrounding heterogeneous echotexture. (c) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as Fig 2) shows linear clumped enhancement (arrowheads) extending anterior and posterior to the known invasive cancer, due to extensive DCIS (EIC). A few small scattered foci of enhancement in contralateral breast were followed for 18 months and have resolved. (d) Second-look sonogram in radial orientation demonstrates hypoechoic mass with duct extension (arrowheads) and small adjacent hypoechoic masses (arrows) due to EIC. Patient opted for mastectomy.

View larger version (122K): [in this window] [in a new window] [Download PPT slide]   Figure 3d. Images in 44-year-old woman with palpable mass in right breast due to grade II IDC with associated EIC of micropapillary type, which is best depicted with MR imaging. (a) MLO mammograms show dense parenchyma with focal asymmetry corresponding to palpable mass marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) of palpable mass in 9 o’clock position in right breast shows hypoechoic irregular mass with posterior enhancement, interpreted as solitary cancer with surrounding heterogeneous echotexture. (c) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as Fig 2) shows linear clumped enhancement (arrowheads) extending anterior and posterior to the known invasive cancer, due to extensive DCIS (EIC). A few small scattered foci of enhancement in contralateral breast were followed for 18 months and have resolved. (d) Second-look sonogram in radial orientation demonstrates hypoechoic mass with duct extension (arrowheads) and small adjacent hypoechoic masses (arrows) due to EIC. Patient opted for mastectomy.

As with IDC, mammographic sensitivity to ILC was again inversely related to breast density, with one of nine (11%) cases of ILC depicted in dense breasts, five of 14 (36%) depicted in heterogeneously dense breasts, three of five (60%) depicted in breasts with minimal scattered fibroglandular density, and one of one (100%) depicted in fatty breasts (P < .001) (Table 2). Of the nine foci of ILC in dense breasts, all had palpable index lesions. As with IDC, breast density did not affect US or MR imaging sensitivity.

The management of 15 breasts was based on presence of ILC. Of the 15 breasts with ILC, three (20%) had diffuse tumor (one according to tumor size larger than 7 cm and two according to diffuse foci), one (6.7%) had multicentric tumor, five (33%) had multifocal tumor, and six (40%) had solitary tumor. Mastectomy was planned in three (20%) breasts on the basis of combined mammography and clinical examination findings.

Table 5 summarizes the extent of disease according to imaging modality for the 12 breasts with ILC in which breast conservation was anticipated after mammography and clinical examination. US and MR imaging accurately depicted extent in eight and seven of these breasts, respectively, compared with five at mammography, though the differences were not significant. Detection of mammographically and clinically unsuspected contralateral ILC occurred in two breasts on the basis of additional imaging with US and MR imaging (Fig 4). US and MR imaging were both hampered by false-positive findings due to lobular carcinoma in situ (Fig 5). Two patients had potentially unnecessary mastectomy on the basis of US and MR imaging findings (Fig 5).

View larger version (106K): [in this window] [in a new window] [Download PPT slide]   Figure 4a. Images in 57-year-old woman with bilateral diffuse foci of ILC. Patient presented with palpable node in neck, with fine-needle aspiration biopsy findings consistent with metastatic ILC. (a) Bilateral craniocaudal mammograms showed heterogeneously dense parenchyma with several vague asymmetries (arrows) in left breast developing since acquisition of a prior mammogram, seen only in craniocaudal view. (b) MLO mammograms show extensive bilateral axillary adenopathy (arrows). (c) Radial sonogram (L13-7-MHz transducer) obtained in 9 o’clock position in left breast shows multiple irregular hypoechoic masses (arrows), as were seen diffusely throughout both breasts. (d) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as in Fig 2) shows multiple diffuse intensely enhancing irregular masses in both breasts, as well as intensely enhancing adenopathy. One representative mass in each breast underwent core-needle biopsy with US guidance, confirming ILC. Patient underwent bilateral mastectomy and axillary node dissection, which confirmed diffuse ILC and metastatic adenopathy.

View larger version (117K): [in this window] [in a new window] [Download PPT slide]   Figure 4b. Images in 57-year-old woman with bilateral diffuse foci of ILC. Patient presented with palpable node in neck, with fine-needle aspiration biopsy findings consistent with metastatic ILC. (a) Bilateral craniocaudal mammograms showed heterogeneously dense parenchyma with several vague asymmetries (arrows) in left breast developing since acquisition of a prior mammogram, seen only in craniocaudal view. (b) MLO mammograms show extensive bilateral axillary adenopathy (arrows). (c) Radial sonogram (L13-7-MHz transducer) obtained in 9 o’clock position in left breast shows multiple irregular hypoechoic masses (arrows), as were seen diffusely throughout both breasts. (d) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as in Fig 2) shows multiple diffuse intensely enhancing irregular masses in both breasts, as well as intensely enhancing adenopathy. One representative mass in each breast underwent core-needle biopsy with US guidance, confirming ILC. Patient underwent bilateral mastectomy and axillary node dissection, which confirmed diffuse ILC and metastatic adenopathy.

View larger version (117K): [in this window] [in a new window] [Download PPT slide]   Figure 4c. Images in 57-year-old woman with bilateral diffuse foci of ILC. Patient presented with palpable node in neck, with fine-needle aspiration biopsy findings consistent with metastatic ILC. (a) Bilateral craniocaudal mammograms showed heterogeneously dense parenchyma with several vague asymmetries (arrows) in left breast developing since acquisition of a prior mammogram, seen only in craniocaudal view. (b) MLO mammograms show extensive bilateral axillary adenopathy (arrows). (c) Radial sonogram (L13-7-MHz transducer) obtained in 9 o’clock position in left breast shows multiple irregular hypoechoic masses (arrows), as were seen diffusely throughout both breasts. (d) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as in Fig 2) shows multiple diffuse intensely enhancing irregular masses in both breasts, as well as intensely enhancing adenopathy. One representative mass in each breast underwent core-needle biopsy with US guidance, confirming ILC. Patient underwent bilateral mastectomy and axillary node dissection, which confirmed diffuse ILC and metastatic adenopathy.

View larger version (98K): [in this window] [in a new window] [Download PPT slide]   Figure 4d. Images in 57-year-old woman with bilateral diffuse foci of ILC. Patient presented with palpable node in neck, with fine-needle aspiration biopsy findings consistent with metastatic ILC. (a) Bilateral craniocaudal mammograms showed heterogeneously dense parenchyma with several vague asymmetries (arrows) in left breast developing since acquisition of a prior mammogram, seen only in craniocaudal view. (b) MLO mammograms show extensive bilateral axillary adenopathy (arrows). (c) Radial sonogram (L13-7-MHz transducer) obtained in 9 o’clock position in left breast shows multiple irregular hypoechoic masses (arrows), as were seen diffusely throughout both breasts. (d) Transverse MIP of subtracted MR image obtained 3 minutes after contrast agent injection (same parameters as in Fig 2) shows multiple diffuse intensely enhancing irregular masses in both breasts, as well as intensely enhancing adenopathy. One representative mass in each breast underwent core-needle biopsy with US guidance, confirming ILC. Patient underwent bilateral mastectomy and axillary node dissection, which confirmed diffuse ILC and metastatic adenopathy.

View larger version (111K): [in this window] [in a new window] [Download PPT slide]   Figure 5a. Images in 41-year-old woman with multifocal ILC and multiple foci of lobular carcinoma in situ. (a) Bilateral MLO mammograms show dense parenchyma with no discrete abnormality. Palpable mass in lower left breast is marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) obtained in 6 o’clock position in left breast demonstrates at least five discrete hypoechoic irregular masses suspicious for cancer. US-guided core biopsy was performed for palpable largest mass (right arrowhead) and a second mass 3 cm superior to it (left arrowhead), both proving to be ILC. Similar findings were noted on (c) sagittal MIP of subtracted MR image obtained 90 seconds after contrast agent injection (same parameters as Fig 2), with biopsied masses indicated by arrowheads. Patient opted for mastectomy. Only the two cored masses proved to be ILC. Remainder were lobular carcinoma in situ.

View larger version (101K): [in this window] [in a new window] [Download PPT slide]   Figure 5b. Images in 41-year-old woman with multifocal ILC and multiple foci of lobular carcinoma in situ. (a) Bilateral MLO mammograms show dense parenchyma with no discrete abnormality. Palpable mass in lower left breast is marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) obtained in 6 o’clock position in left breast demonstrates at least five discrete hypoechoic irregular masses suspicious for cancer. US-guided core biopsy was performed for palpable largest mass (right arrowhead) and a second mass 3 cm superior to it (left arrowhead), both proving to be ILC. Similar findings were noted on (c) sagittal MIP of subtracted MR image obtained 90 seconds after contrast agent injection (same parameters as Fig 2), with biopsied masses indicated by arrowheads. Patient opted for mastectomy. Only the two cored masses proved to be ILC. Remainder were lobular carcinoma in situ.

View larger version (87K): [in this window] [in a new window] [Download PPT slide]   Figure 5c. Images in 41-year-old woman with multifocal ILC and multiple foci of lobular carcinoma in situ. (a) Bilateral MLO mammograms show dense parenchyma with no discrete abnormality. Palpable mass in lower left breast is marked with radiopaque marker. (b) Radial sonogram (L13-7-MHz transducer) obtained in 6 o’clock position in left breast demonstrates at least five discrete hypoechoic irregular masses suspicious for cancer. US-guided core biopsy was performed for palpable largest mass (right arrowhead) and a second mass 3 cm superior to it (left arrowhead), both proving to be ILC. Similar findings were noted on (c) sagittal MIP of subtracted MR image obtained 90 seconds after contrast agent injection (same parameters as Fig 2), with biopsied masses indicated by arrowheads. Patient opted for mastectomy. Only the two cored masses proved to be ILC. Remainder were lobular carcinoma in situ.

The foci of DCIS depicted mammographically included two of eight (25%) in dense breasts, nine of 14 (64%) in breasts with heterogeneously dense parenchyma, nine of 15 (60%) in breasts with minimal scattered fibroglandular density, and one of one (100%) in fatty breasts. Another focus of low-grade DCIS was initially considered probably benign at mammography and manifested as a grouping of four punctate calcifications at stereotactic biopsy performed after intense progressive enhancement seen at MR imaging.

The management of 14 breasts was predicated on DCIS (six high-grade, four intermediate-grade, and four low-grade DCIS). Of the 14 breasts, one (7.1%) showed diffuse foci of DCIS, one (7.1%) had multicentric foci, five (36%) had multifocal disease, and seven (50%) had solitary tumor foci. Of the six with multifocal or multicentric disease, three (50%) were micropapillary DCIS.

Table 6 summarizes the extent of disease according to imaging modality for the 12 breasts with DCIS for which breast conservation was anticipated on the basis of clinical examination and mammographic findings. Combined mammography and clinical examination depicted extent of DCIS well, but differences compared with other modalities alone or in combination were not significant, likely as a result of the small number of cases. The extent of disease was overestimated with US in four of 12 (33%) breasts and with MR imaging in six of 12 (50%). One mastectomy was prompted by the finding of multiple scattered suspicious foci at both US and MR imaging, with two additional core biopsy results indicating atypical ductal hyperplasia. This case proved to be a solitary 25-mm mass of intermediate-grade DCIS. Another four of 12 (33%) breasts with DCIS for which conservation was planned were negative at US. Two breasts were appropriately converted from planned lumpectomy to mastectomy on the basis of more extensive disease at US and MR imaging (Fig 6).

View larger version (114K): [in this window] [in a new window] [Download PPT slide]   Figure 6. Images in 59-year-old woman with multicentric intermediate-grade solid and cribriform DCIS that was underestimated mammographically. A, Laterally exaggerated craniocaudal and, B, MLO mammograms demonstrate indistinctly-marginated mass (arrow) in axillary tail of left breast, seen best on B, and minimal scattered fibroglandular density. C, Transverse sonogram (L12-7.5-MHz transducer) obtained in 2 o’clock position in left breast confirms the finding (marked by calipers). US-guided 14-g core biopsy revealed intermediate-grade cribriform DCIS. Lumpectomy was planned. D, MIP of subtracted contrast-enhanced three-dimensional gradient-echo MR image in sagittal plane (same technique as above) showed the known focus of cancer (arrow) and three other similar foci of enhancement (arrowheads). Second-look transverse sonograms obtained in, E, 9 o’clock position and, F, 6 o’clock position after MR imaging showed multiple additional masses (marked by calipers) that corresponded to additional lesions found at MR imaging. Additional core biopsies were performed, confirming additional foci of DCIS. Patient underwent mastectomy.