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Published online before print November 7, 2006, 10.1148/radiol.2421050859
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(Radiology 2007;242:63-69.)
© RSNA, 2006

Breast Imaging

Characterization of Benign and Malignant Solid Breast Masses: Comparison of Conventional US and Tissue Harmonic Imaging1

Joo Hee Cha, MD, Woo Kyung Moon, MD, Nariya Cho, MD, Sun Mi Kim, MD, Seong Ho Park, MD, Boo-Kyung Han, MD, Yeon Hyeon Choe, MD, Jeong Mi Park, MD and Jung-Gi Im, MD

1 From the Department of Radiology, Boramae Municipal Hospital, Seoul, Korea (J.H.C.); Department of Radiology and Clinical Research Institute, Seoul National University Hospital and the Institute of Radiation Medicine, Seoul National University Medical Research Center, 28 Yongon-dong, Chongno-gu, Seoul 100-744, Korea (W.K.M., N.C., S.M.K., J.G.I.); Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea (S.H.P.); Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea (B.K.H., Y.H.C.); and Department of Radiology, College of Medicine, University of Iowa, Iowa City, Iowa (J.M.P.). From the 2005 RSNA Annual Meeting. Received May 23, 2005; revision requested July 18; revision received October 11; accepted November 4; final version accepted April 12, 2006. Supported by KISTEP, Ministry of Science and Technology, Korea. Address correspondence to W.K.M. (e-mail: moonwk{at}radcom.snu.ac.kr).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Purpose: To prospectively compare the diagnostic performance of radiologists by using conventional ultrasonography (US) and tissue harmonic imaging for the differentiation of benign from malignant solid breast masses, with histologic results used as the reference standard.

Materials and Methods: The study was approved by the institutional review board, and informed consent was obtained from all patients. Images were obtained with conventional US and tissue harmonic imaging in 88 patients (age range, 25–67 years; mean age, 45 years) with 91 solid breast masses (30 cancers and 61 benign lesions) before excisional or needle biopsy. Three experienced radiologists, who did not perform the examinations, independently analyzed the US findings and provided a level of suspicion to indicate the probability of malignancy. Results were evaluated by using {kappa} statistics and receiver operating characteristic (ROC) analyses.

Results: Regarding the descriptions of US findings, echogenicity ({kappa} = 0.205) was the most discordant between conventional US and tissue harmonic imaging, followed by margin ({kappa} = 0.495), lesion boundary ({kappa} = 0.495), calcifications ({kappa} = 0.537), posterior acoustic transmission ({kappa} = 0.546), echotexture ({kappa} = 0.586), shape ({kappa} = 0.591), and orientation ({kappa} = 0.594). The area under the ROC curve (Az) for conventional US and tissue harmonic imaging was 0.84 and 0.79, respectively, for reader 1; 0.88 and 0.85, respectively, for reader 2; and 0.91 and 0.89, respectively, for reader 3. The overall Az value for the three readers was 0.88 for conventional US and 0.84 for tissue harmonic imaging (95% confidence interval: –0.0950, 0.1646; P = .595).

Conclusion: The performance of the radiologists with respect to the characterization of solid breast masses as benign or malignant was not significantly improved with tissue harmonic imaging.

© RSNA, 2006


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Tissue harmonic imaging is an ultrasonographic (US) technique that can potentially provide images of higher quality than those obtained with conventional US techniques. Tissue harmonic imaging involves the use of harmonic frequencies that originate within the tissue as a result of nonlinear wave front propagation and are not present in the incident beam (1–4). These harmonic signals are generated differently at anatomic sites with similar impedances and thus lead to a higher contrast resolution. In addition, the use of tissue harmonic imaging helps to reduce many of the artifacts that occur during conventional US, such as side-lobe, clutter, and reverberation artifacts, and improves the signal-to-noise ratio.

The results of recent studies have shown that tissue harmonic imaging substantially improves the image quality of breast lesions compared with conventional US (5–7). Tissue harmonic imaging was found to improve the conspicuity of low-contrast lesions and the differentiation of fluid from solid tissue in complicated cysts and to enhance the delineation of tumor margins. However, although the potential benefits of tissue harmonic imaging for the characterization of solid breast masses have been emphasized, previous studies have not addressed whether these improvements affect the final diagnostic assessment of lesions and allow better selection of patients for biopsy.

Thus, the purpose of our study was to prospectively compare the diagnostic performance of radiologists by using conventional US and tissue harmonic imaging for the differentiation of benign from malignant solid breast masses, with histologic results used as the reference standard.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Patients and Masses
Between December 2002 and January 2003, 98 consecutive women who had been scheduled to undergo excisional or percutaneous needle biopsy on the basis of suspicious mammographic or physical findings were examined with US. A total of 91 solid breast masses were visualized at US in 88 patients (age range, 25–67 years; mean age, 45 years) who were included in the study. Patients with clustered microcalcifications detected at mammography were excluded because the mass that was associated with the microcalcifications was not seen at US (Fig 1). The study was approved by the institutional review board of Seoul National University Hospital, and informed consent was obtained from all patients.


Figure 1
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  		Figure 1: Flowchart shows the selection of patients with suspicious mammographic or physical findings who were included in the analysis.

 
Lesions manifested as a clinically occult mammographic lesion in 51 cases, as a palpable mass in 29 cases, as nipple discharge in eight cases, and as an incidental US lesion in three cases. Mammograms were available in 84 patients with 84 lesions. Lesions were identified at mammography as a mass in 42 cases, as a mass with microcalcifications in 28 cases, as an asymmetric density in three cases, and as an architectural distortion in one case. No mammographic abnormality was found in 10 (12%) of 84 lesions.

The 91 solid breast masses were assessed before biopsy by using the Breast Imaging Reporting and Data System (BI-RADS) of the American College of Radiology (8), with a final assessment of category 3 (probably benign) in eight masses (9%), category 4 (suspicious) in 59 masses (65%), and category 5 (highly suggestive of malignancy) in 24 masses (26%). Biopsy was performed in eight probably benign lesions because of patient or referring clinician preference on clinical grounds.

The nature of all masses seen at US was confirmed by means of histopathologic analysis after surgical excision (n = 30) or by means of US-guided percutaneous core-needle biopsy (n = 61) within 24 hours of the US examination. Of the 91 masses, 30 (33%) were cancerous and 61 (67%) were benign (Fig 1). Malignant masses included infiltrating ductal carcinoma (n = 24), infiltrating lobular carcinoma (n = 2), and ductal carcinoma in situ (DCIS) (n = 4). Benign lesions included fibroadenoma (n = 31), papilloma (n = 2), and fibrocystic changes (n = 28). All benign lesions, except for three fibroadenomas and one fibrocystic change, were followed up for more than 2 years, and lesion stability was confirmed. For the four benign lesions that were followed up for less than 2 years, follow-up time was 0–18 months (mean, 7.5 months). The histologic diameter of the lesions was 6–28 mm (mean, 12.1 mm) for invasive cancer, 6–25 mm (mean, 13.7 mm) for DCIS, and 4–26 mm (mean, 12.3 mm) for benign lesions. Mass size at US was 4–9 mm in 40 lesions, 10–19 mm in 31 lesions, and 20–29 mm in 20 lesions.

US Examinations
Conventional US and tissue harmonic imaging scans were obtained by using a LOGIQ 700 scanner (GE Medical Systems, Milwaukee, Wis) with a 5–13-MHz linear transducer. Imaging was performed by one breast radiologist (W.K.M.) who had 7 years of experience in conventional breast US and 2 years of experience in tissue harmonic imaging; this radiologist also had knowledge of clinical and mammographic findings. During tissue harmonic imaging, the beam was emitted at a center frequency of 6 MHz and was received at a center frequency of 12 MHz. The scanning protocol included both transverse and longitudinal real-time imaging of the solid masses, and a split-screen imaging mode was used to obtain identical images at conventional US and tissue harmonic imaging. The images were obtained in an identical plane without changing depth or focus position. The image gain was adjusted for conventional US and tissue harmonic imaging. The order of the image acquisitions (ie, either tissue harmonic imaging first or conventional US first) was determined randomly.

Representative transverse and longitudinal images of solid masses at conventional US and tissue harmonic imaging were saved in a picture archiving and communications system and were printed on film. The images were then cut apart so that the readers looked at only one image or the other. Image sets were masked and randomized.

Imaging Review
Three breast radiologists (B.K.H., Y.H.C., J.M.P.), who had not performed the US examinations and who were blinded to the image acquisition technique, independently analyzed the hard-copy images of the transverse and longitudinal scans, without knowledge of physical examination findings or mammographic information. A single transverse image and a single longitudinal image were provided for the readers. The readers were from two academic centers other than the institution where the US examinations were performed, and their level of experience in breast US varied (range, 5–12 years; mean, 8.3 years). All readers had at least 3 years of experience in tissue harmonic imaging (range, 3–5 years; mean, 4.3 years) and had read the conventional US and tissue harmonic imaging scans independently.

The 182 sets of US images (91 conventional US scans and 91 tissue harmonic imaging scans) were divided into two groups after randomization. The two groups of 91 images were then reviewed, with a 1-month interval between each review session. For both techniques, the radiologists described the shape (round or oval, lobulated, or irregular), orientation (wider than tall or taller than wide), margin (circumscribed, microlobulated, ill defined, or spiculated), echogenicity (hyperechoic, isoechoic, mildly hypoechoic, or markedly hypoechoic), echotexture (homogeneous or heterogeneous), posterior acoustic transmission (unaffected, enhanced, or shadowing), lesion boundary (absent, thin pseudocapsule, or thick echogenic halo), and presence of calcifications within the mass (present or absent). The radiologists also provided a BI-RADS final assessment category to indicate the probability of malignancy (8).

The three readers were given instructions that the malignancy risk for each category at US was similar to the mammographic BI-RADS risk. A solid mass with circumscribed margins, round or oval shape, and wider-than-tall orientation (most likely a fibroadenoma) should have a less than 2% risk of malignancy and should be placed in category 3 (probably benign lesions) on the basis of our data and that of others (9–11). Each lesion was further categorized as benign (benign or probably benign) or malignant (suspicious or highly suggestive of malignancy). For management, follow-up was recommended for benign or probably benign lesions, and biopsy was recommended for suspicious lesions or for lesions that were highly suggestive of malignancy.

Statistical Analysis
Agreement between the two US techniques and interobserver agreement between the three radiologists for each US technique were calculated by using {kappa} statistics with regard to the description of US findings, such as shape, orientation, margin, echogenicity, echotexture, posterior acoustic transmission, lesion boundary, presence of calcifications within masses, and BI-RADS final assessment category. A {kappa} value of 0.20 or less was considered slight agreement; 0.21–0.40, fair agreement; 0.41–0.60, moderate agreement; 0.61–0.80, substantial agreement; and 0.81–1.00, almost perfect agreement (12).

Receiver operating characteristic (ROC) analysis was performed to assess and compare radiologists' performance in characterizing solid breast masses with conventional US and tissue harmonic imaging by using histologic results as the reference standard. To summarize overall performance, parametric estimates of the area under the ROC curve (Az) were calculated and compared for the two techniques by using LABMRMC (C. E. Metz, University of Chicago, Chicago, Ill) (13). The statistical significance of the results was reported with 95% confidence intervals for the mean differences in Az for reader performance with use of the two techniques. Mean differences were regarded as statistically significant at the 5% level when the corresponding confidence interval did not encompass zero (14).

In addition, test set sensitivities and test set specificities for the two techniques were calculated for each reader and were compared by using the McNemar test; the mean test set sensitivity and the mean test set specificity for the three readers were compared between the two techniques by using a paired t test. In our study, the terms test set sensitivity and test set specificity were used instead of sensitivity and specificity because we treated our case sets as though they were fixed for analysis (15,16). Two-tailed P values of less than .05 were considered to indicate a statistically significant difference. Statistical analyses other than ROC analyses were performed by using SPSS for Windows (version 10; SPSS, Chicago, Ill).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 
Reader Agreement: Findings at Imaging
The three radiologists showed fair to moderate agreement with respect to US findings by using the two techniques (Table 1). Their description of echogenicity was the most discordant ({kappa} = 0.205) for the two techniques, followed by margin ({kappa} = 0.495), lesion boundary ({kappa} = 0.495), calcifications ({kappa} = 0.537), posterior acoustic transmission ({kappa} = 0.546), echotexture ({kappa} = 0.586), shape ({kappa} = 0.591), and orientation ({kappa} = 0.594).


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  		Table 1. Agreement between Conventional US and Tissue Harmonic Imaging for US Findings and Final Assessments in 91 Solid Breast Masses

 
Of the 29 lesions that were described as having isoechoic echogenicity at conventional US, 27 were described differently by at least one reader at tissue harmonic imaging. Twenty-three lesions were described as mildly hypoechoic, three were described as markedly hypoechoic, and one was described as hyperechoic. Two DCIS lesions that manifested as a mass with microcalcifications at mammography were isoechoic at conventional US and hypoechoic at tissue harmonic imaging (Fig 2). Twenty-eight lesions (21 cancers and seven benign lesions) were found to have calcifications at mammography, but readers 1, 2, and 3 reported 16, 15, and 13 lesions, respectively, as having calcifications at conventional US and 15, 12, and 15 lesions, respectively, as having calcifications at tissue harmonic imaging (Fig 3).


Figure 2
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  		Figure 2a: Longitudinal images of DCIS obtained in a 42-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) The 0.9-cm ill-defined isoechoic mass (arrow) is difficult to distinguish from the surrounding glandular or fatty tissue. (b) The mass (arrow) with posterior acoustic shadowing appears hypoechoic and the tumor margin is clearly delineated.

 

Figure 2
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  		Figure 2b: Longitudinal images of DCIS obtained in a 42-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) The 0.9-cm ill-defined isoechoic mass (arrow) is difficult to distinguish from the surrounding glandular or fatty tissue. (b) The mass (arrow) with posterior acoustic shadowing appears hypoechoic and the tumor margin is clearly delineated.

 

Figure 3
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  		Figure 3a: Transverse images of infiltrating ductal carcinoma obtained in a 55-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) A 1.1-cm ill-defined hypoechoic mass with mild posterior acoustic shadowing is seen. (b) The mass is markedly hypoechoic, with pronounced posterior acoustic shadowing (*). Images show punctate echogenic dots (arrow) within the hypoechoic mass corresponding to microcalcifications seen at mammography. The final assessment by all readers was "highly suggestive of malignancy" at both conventional US and tissue harmonic imaging.

 

Figure 3
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  		Figure 3b: Transverse images of infiltrating ductal carcinoma obtained in a 55-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) A 1.1-cm ill-defined hypoechoic mass with mild posterior acoustic shadowing is seen. (b) The mass is markedly hypoechoic, with pronounced posterior acoustic shadowing (*). Images show punctate echogenic dots (arrow) within the hypoechoic mass corresponding to microcalcifications seen at mammography. The final assessment by all readers was "highly suggestive of malignancy" at both conventional US and tissue harmonic imaging.

 
For the final assessment of solid breast masses, moderate to substantial agreement was found between the two techniques; the {kappa} value was 0.520 for reader 1, 0.658 for reader 2, and 0.575 for reader 3 (Fig 4).


Figure 4
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  		Figure 4a: Transverse images of fibroadenoma obtained in a 35-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) A 1.0-cm oval-shaped slightly hypoechoic mass (arrow) is seen. (b) The mass (arrow) appears more hypoechoic and the circumscribed margin is clearly delineated. The final assessment by all readers was "probably benign" at both conventional US and tissue harmonic imaging.

 

Figure 4
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  		Figure 4b: Transverse images of fibroadenoma obtained in a 35-year-old woman during (a) conventional US and (b) tissue harmonic imaging. (a) A 1.0-cm oval-shaped slightly hypoechoic mass (arrow) is seen. (b) The mass (arrow) appears more hypoechoic and the circumscribed margin is clearly delineated. The final assessment by all readers was "probably benign" at both conventional US and tissue harmonic imaging.

 
Interobserver agreement between the three radiologists in terms of conventional US findings was fair for orientation ({kappa} = 0.314) and echogenicity ({kappa} = 0.344); moderate for boundary echo ({kappa} = 0.434), echotexture ({kappa} = 0.463), margin ({kappa} = 0.496), and posterior acoustic transmission ({kappa} = 0.571); and substantial for shape ({kappa} = 0.631) and calcifications ({kappa} = 0.713). On the other hand, interobserver agreement for tissue harmonic imaging was slight for echogenicity ({kappa} = 0.188); fair for boundary echo ({kappa} = 0.316); and moderate for margin ({kappa} = 0.422), echotexture ({kappa} = 0.500), orientation ({kappa} = 0.518), calcifications ({kappa} = 0.524), shape ({kappa} = 0.542), and posterior acoustic transmission ({kappa} = 0.583). Interobserver agreement among the three radiologists on the final assessment of solid breast masses was similar for conventional US ({kappa} = 0.343) and tissue harmonic imaging ({kappa} = 0.451).

ROC Analysis, Test Set Sensitivity, and Test Set Specificity
The Az values for conventional US and tissue harmonic imaging were 0.84 and 0.79, respectively, for reader 1; 0.88 and 0.85, respectively, for reader 2; and 0.91 and 0.89, respectively, for reader 3. The overall Az value for the three readers was 0.88 for conventional US and 0.84 for tissue harmonic imaging (95% confidence interval: –0.0950, 0.1646) (Table 2). This difference was not statistically significant (P = .595).


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  		Table 2. Performance Test Measures of Three Readers for the Assessment of 91 Solid Breast Masses at Conventional US and Tissue Harmonic Imaging

 
The test set sensitivity for conventional US and tissue harmonic imaging was 100% (30 of 30) and 97% (29 of 30), respectively, for reader 1 (P > .99); 93% (28 of 30) and 97% (29 of 30), respectively, for reader 2 (P > .99); and 97% (29 of 30) and 93% (28 of 30), respectively, for reader 3 (P > .99). Test set sensitivity showed no significant difference between the three readers. The mean test set sensitivity for the three readers was not significantly different between conventional US and tissue harmonic imaging (P = .729) (Table 2).

The test set specificity for conventional US and tissue harmonic imaging was 56% (34 of 61) and 59% (36 of 61), respectively, for reader 1 (P = .774); 57% (35 of 61) and 56% (34 of 61), respectively, for reader 2 (P > .99); and 75% (46 of 61) and 72% (44 of 61), respectively, for reader 3 (P = .687). Test set specificity showed no significant difference between the three readers. The mean test set specificity for the three readers was not significantly different between conventional US and tissue harmonic imaging (P = .868) (Table 2).

Management
For the 91 lesions, the management decision (either follow-up or biopsy) was discordant at conventional US and tissue harmonic imaging in 13 lesions (14%) for reader 1, eight lesions (9%) for reader 2, and nine lesions (10%) for reader 3 (Table 3). One of the three readers recommended follow-up rather than biopsy for one malignant lesion at both conventional US and tissue harmonic imaging.


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  		Table 3. Management Decision in 91 Solid Breast Masses at Conventional US and Tissue Harmonic Imaging

 
Two cancers that were categorized as benign at conventional US were correctly categorized as malignant at tissue harmonic imaging by two readers (Table 3). These two cancers were described differently at conventional US and tissue harmonic imaging for at least one of the eight US findings (shape [n = 2], margin [n = 2], echogenicity [n = 1], posterior acoustic transmission [n = 1], and lesion boundary [n = 1]).

Two cancers that were categorized as benign at tissue harmonic imaging were correctly categorized as malignant at conventional US by at least one of the three readers (one cancer by one reader and one cancer by two readers). These two cancers were described differently at conventional US and tissue harmonic imaging for at least one of the eight US findings (shape [n = 1], margin [n = 2], echogenicity [n = 2], echotexture [n = 1], posterior acoustic transmission [n = 1], lesion boundary [n = 1], and calcifications [n = 1]).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
ADVANCES IN KNOWLEDGE
 References
 
Tissue harmonic imaging improves the gray-scale contrast between glandular or fatty tissue and breast lesions (5,6). Tissue harmonic imaging reduces the echogenicity seen within solid masses by suppressing the speckles that contribute to the internal echogenicity of lesions at conventional US. This makes the lesion more hypoechoic relative to the surrounding breast tissue, thereby making the lesions easier to identify and less likely to be missed. Of the 29 lesions that were described as having isoechoic echogenicity at conventional US, 26 were described as hypoechoic at tissue harmonic imaging by at least one reader in our study. Two DCIS lesions that manifested as a mass with microcalcifications at mammography were subtle and barely seen at conventional US. These same lesions were definitely seen at tissue harmonic imaging, which allowed the use of US to guide needle biopsy.

In a study by Jung et al (17) that compared conventional US with tissue harmonic imaging in 350 patients who had dense breasts, 19 of 25 breast lesions detected at US were seen both at conventional US and tissue harmonic imaging, while six lesions were seen at tissue harmonic imaging only. A prospective study is needed to compare conventional US with tissue harmonic imaging in the depiction of solid nodules in fatty breasts and masses associated with calcific clusters in dense breasts (18).

The main limitation of using tissue harmonic imaging is reduced penetration. In a study that comprised 350 US examinations of the breast, tissue harmonic imaging failed to obtain adequate penetration to the chest wall in 6% of cases (19). Such instances usually occurred in women with large breasts that were composed primarily of fibrous tissue. Another limitation is related to extensive refractive shadowing. In the dense breast, shadowing from normal structure is increased, and examination of the retroareolar region is sometimes limited. Regarding posterior acoustic transmission, either enhancement or shadowing becomes more conspicuous at tissue harmonic imaging and is related to the higher receiving frequency and narrower dynamic range used with tissue harmonic imaging. Further improvement in tissue harmonic imaging is needed to increase tissue penetration, frame rate, and spatial resolution.

There are limitations to our study. We used only two static images (ie, transverse and longitudinal scans) of the solid breast masses for evaluation rather than using real-time assessment at conventional US and tissue harmonic imaging. The radiologists were blinded to the mammographic information, and this probably lowered the radiologists' performance. The physician who acquired the conventional US and tissue harmonic imaging scans adjusted the image gain and was aware of the study purpose. This could also be a limitation. There was no assessment of intrareader variability in our study. The small sample size of our study could also be a limitation because a post hoc power analysis showed a power of 0.28 rather than 0.80, which is generally regarded as appropriate. Spatial compound imaging can also be used for breast scanning because it is easy to switch from one technique to the other (7). We did not compare spatial compound imaging with tissue harmonic imaging for the differentiation of benign from malignant solid breast masses. Results of a recent study showed that the performance of the radiologists with respect to the characterization of solid breast masses was not improved significantly at spatial compound imaging compared with conventional US (20).

In summary, three radiologists described specific US findings of solid breast masses and provided a BI-RADS final assessment category at conventional US and tissue harmonic imaging. As a result, we found fair to moderate agreement between the two modalities in terms of the description of US findings and moderate to substantial agreement for the final assessment of the masses. For the three radiologists, however, diagnostic performance (Az value, test set sensitivity, and test set specificity) was not significantly different between conventional US and tissue harmonic imaging.


   ADVANCES IN KNOWLEDGE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
References
 


   FOOTNOTES
 

Abbreviations: Az = area under the ROC curve • BI-RADS = Breast Imaging Reporting and Data System • DCIS = ductal carcinoma in situ • ROC = receiver operating characteristic

Author contributions: Guarantor of integrity of entire study, W.K.M.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, J.H.C., W.K.M., S.H.P.; clinical studies, J.H.C., W.K.M., B.K.H., Y.H.C., J.M.P., J.G.I.; statistical analysis, J.H.C., W.K.M., S.H.P.; and manuscript editing, all authors

Authors stated no financial relationship to disclose.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCES IN KNOWLEDGE
 References
 

  1. Tranquart F, Grenier N, Eder V, Pourcelot L. Clinical use of ultrasound tissue harmonic imaging. Ultrasound Med Biol 1999;25:889–894.[CrossRef][Medline]
  2. Shapiro RS, Wagreich J, Parsons RB, Stancato-Pasik A, Yeh HC, Lao R. Tissue harmonic imaging sonography: evaluation of image quality compared with conventional sonography. AJR Am J Roentgenol 1998;171:1203–1206.[Abstract/Free Full Text]
  3. Strobel K, Zanetti M, Nagy L, Hodler J. Suspected rotator cuff lesions: tissue harmonic imaging versus conventional US of the shoulder. Radiology 2004;230:243–249.[Abstract/Free Full Text]
  4. Yucel C, Ozdemir H, Asik E, Oner Y, Isik S. Benefits of tissue harmonic imaging in the evaluation of abdominal and pelvic lesions. Abdom Imaging 2003;28:103–109.[CrossRef][Medline]
  5. Rosen EL, Soo MS. Tissue harmonic imaging sonography of breast lesions: improved margin analysis, conspicuity, and image quality compared to conventional ultrasound. Clin Imaging 2001;25:379–384.[CrossRef][Medline]
  6. Szopinski KT, Pajk AM, Wysocki M, Amy D, Szopinska M, Jakubowski W. Tissue harmonic imaging: utility in breast sonography. J Ultrasound Med 2003;22:479–487.[Abstract/Free Full Text]
  7. Seo BK, Oh YW, Kim HR, et al. Sonographic evaluation of breast nodules: comparison of conventional, real-time compound, and pulse-inversion harmonic images. Korean J Radiol 2002;3:38–44.[Medline]
  8. American College of Radiology. Breast imaging reporting and data system (BI-RADS). 3rd ed. Reston, Va: American College of Radiology, 1998.
  9. Stavros AT, Thickman D, Rapp CL, Dennis MA, Parker SH, Sisney GA. Solid breast nodules: use of sonography to distinguish between benign and malignant lesions. Radiology 1995;196:123–134.[Abstract/Free Full Text]
  10. Moon WK, Myung JS, Lee YJ, Park IA, Noh DY, Im JG. US of ductal carcinoma in situ. RadioGraphics 2002;22:269–280.[Abstract/Free Full Text]
  11. Moon WK, Noh DY, Im JG. Multifocal, multicentric, and contralateral breast cancers: bilateral whole-breast US in the preoperative evaluation of patients. Radiology 2002;224:569–576.[Abstract/Free Full Text]
  12. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33:159–174.[CrossRef][Medline]
  13. Metz CE. LABMRMC 1.0B software. University of Chicago Department of Radiology Web site. http://www-radiology.uchicago.edu/krl/KRL_ROC/software_index.htm. Accessed March 2, 2005.
  14. Bulpitt CJ. Confidence intervals. Lancet 1987;1:494–497.[CrossRef][Medline]
  15. Hanley JA. Receiver operating characteristic (ROC) methodology: the state of the art. Crit Rev Diagn Imaging 1989;29:307–335.[Medline]
  16. Beam CA, Conant EF, Sickles EA. Correlation of radiologist rank as a measure of skill in screening and diagnostic interpretation of mammograms. Radiology 2006;238:446–453.[Abstract/Free Full Text]
  17. Jung EM, Clevert DA, Lutz R, Kett H, Rupp N. Preoperative wire localisation of breast lesions by tissue harmonic imaging (THI) sonography. Rofo 2002;174:1121–1125.[Medline]
  18. Moon WK, Im JG, Koh YH, Noh DY, Park IA. US of mammographically detected clustered microcalcifications. Radiology 2000;217:849–854.[Abstract/Free Full Text]
  19. Stavros AT. Breast ultrasound equipment requirements. Philadelphia, Pa: Lippincott Williams & Wilkins, 2004; 16–42.
  20. Cha JH, Moon WK, Cho N, et al. Differentiation of benign from malignant solid breast masses: conventional US versus spatial compound imaging. Radiology 2005;237:841–846.[Abstract/Free Full Text]




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