| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Thoracic Imaging |
1 From the Department of Radiology and Center for Imaging Science (Y.J.J., K.S.L., S.S.S., S.Y.J., M.J.C.), Division of Pulmonary and Critical Care Medicine, Department of Medicine (H.K., O.J.K.), and Biostatistics Unit (S.K.), Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-Dong, Kangnam-Ku, Seoul 135-710, Korea. Received September 8, 2004; revision requested November 12; revision received November 19; accepted December 30. Address correspondence to K.S.L. (e-mail: kyungs.lee{at}samsung.com).
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. The study included 107 patients (62 men, 45 women; mean age, 55 years; range, 22–81 years) with a solitary pulmonary nodule. After unenhanced CT (2.5-mm collimation) scans were obtained, dynamic CT was performed by using a helical technique (series of images obtained throughout the nodule, with 2.5-mm collimation, at 30, 60, 90, and 120 seconds and 4, 5, 9, 12, and 15 minutes) after intravenous injection of contrast medium (120 mL). Tissue diagnosis was made in 70 nodules, and follow-up images showed benignancy in the remaining 37 (no change in size, n = 32; decrease in size, n = 5). CT findings were analyzed in terms of wash-in and washout of contrast medium. Sensitivity, specificity, and accuracy for malignant nodules were calculated by considering both the wash-in and washout characteristics at dynamic CT.
RESULTS: There were 49 malignant and 58 benign nodules. When diagnostic criteria for malignancy of both wash-in of 25 HU or greater and washout of 5–31 HU were applied, sensitivity, specificity, and accuracy for malignancy were 94% (46 of 49 nodules), 90% (52 of 58 nodules), and 92% (98 of 107 nodules), respectively. Of 58 benign nodules, 27 showed less than 25 HU wash-in, 14 showed persistent contrast enhancement without washout and with wash-in of 25 HU or greater, and 11 showed washout greater than 31 HU and wash-in of 25 HU or greater.
CONCLUSION: Evaluation of solitary pulmonary nodules by analyzing combined wash-in and washout characteristics at dynamic contrast-enhanced multi–detector row CT showed 92% accuracy for distinguishing benign nodules from malignant nodules.
© RSNA, 2005
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
More recently, several authors have attempted to assess the washout characteristics of adrenal lesions at contrast-enhanced CT (13–17). Washout refers to the reduction in the attenuation values of lesions at CT during a variable period after the intravenous injection of a bolus of contrast material. Many study findings now confirm the usefulness of attenuation measurements at both unenhanced and delayed contrast-enhanced CT for the differentiation of benign from malignant adrenal lesions (13–17).
To the best of our knowledge, no evaluation of the accuracy of pulmonary nodule washout characterization at dynamic contrast-enhanced CT has been reported. The purpose of our study was to prospectively assess the accuracy of combined wash-in and washout characteristics with dynamic contrast-enhanced multi–detector row CT in distinguishing benign from malignant solitary pulmonary nodules.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Before dynamic CT was performed, we obtained targeted thin-section helical CT scans (2.5-mm collimation, 0.8-second gantry rotation time, 120 kVp, 90 mA) through the nodule. Nodules that appeared to be solitary at chest radiography but appeared to have a satellite nodule at thin-section CT (n = 22) were included in this study. For those nodules with a satellite lesion, only the main nodule was evaluated with dynamic contrast-enhanced CT. Nodules were excluded from study if they had benign (diffuse, laminated, popcornlike, or central) patterns of calcification (n = 17) or fat (n = 0) at thin-section CT. Nodules with ground-glass opacity at thin-section CT were also excluded (n = 7). Nodules with stippled (n = 3) or peripheral nodular (n = 12) calcification were included. Dynamic CT was performed in the remaining 131 patients.
Before the intravenous injection of contrast medium, a series of 13 images was obtained throughout the nodule for 30 mm along the z-axis, with 2.5-mm collimation, 120 kVp, 90 mA, 0.8-second gantry rotation time, and a table speed of 3.75 mm/sec over 8 seconds. Thereafter, an additional nine series of images were obtained at 30, 60, 90, and 120 seconds and 4, 5, 9, 12, and 15 minutes after injection of iomeprol (Iomeron 300; Bracco, Milan, Italy), which was administered at a rate of 3 mL/sec for a total of 120 mL by using a power injector (MCT Plus; Medrad, Pittsburgh, Pa), with the same parameters as used for the initial preenhancement series (10 total series of images obtained at 0, 30, 60, 90, and 120 seconds and 4, 5, 9, 12, and 15 minutes). Image data were reconstructed with a thickness of 2.5 mm (13 images in each cluster; total number of dynamic images, 130 [ie, 13 images x 10 series]) by using a standard algorithm. Immediately after dynamic imaging at 120 seconds, helical CT scans (125 mA, 120 kVp, 5-mm collimation, table speed of 15 mm/sec) were obtained from the lung apices to the level of the middle pole of both kidneys for tumor staging. All thin-section, dynamic, and staging CT data were interfaced directly to our picture archiving and communication system (Centricity 1.0; GE Medical Systems Integrated Imaging Solutions, Mt Prospect, Ill), which displayed all image data on monitors (four monitors, 1536 x 2048 image matrices, 8-bit viewable gray scale, 60-foot-lambert luminescence). On the monitors, both mediastinal window (width, 400 HU; level, 20 HU) and lung window (width, 1500 HU; level, –700 HU) images were viewed.
The technical adequacy of dynamic CT fulfilled the following criteria, as presented in previous studies (2,6): (a) absence of contrast medium extravasation at the site of injection, (b) appropriate enhancement of cardiovascular structures imaged during examination, (c) no marked reaction to contrast medium that interfered with image acquisition, and (d) satisfactory patient respiratory registration without artifact on equatorial images. In four patients, inconsistent breath holding was a problem for obtaining dynamic image clusters at the same level. In another 10 patients, the nodules were too small (<5.6 mm in diameter) to measure the attenuation value (partial volume averaging precluded the measurement of attenuation value). With the exception of these 14 patients, the dynamic CT scans were technically adequate in 117 patients, and no serious reactions to contrast medium were reported. No CT examination was interrupted because of reaction to contrast medium.
Of 117 patients, 10 were excluded because neither follow-up CT scans nor cytologic or histologic diagnosis was available for these patients. Therefore, the final study group was 107 patients, which comprised 62 men and 45 women aged 22–81 years (mean, 55 years). The body weight of these 107 patients ranged from 36 to 90 kg (mean, 64 kg; standard deviation, ±10 kg). These patients underwent transthoracic needle biopsy (n = 39) or surgery (n = 31), which included lobectomy (n = 20) or wedge resection (n = 11). Thirty-seven patients in whom CT findings and clinical situations suggested benignancy of a nodule but histopathologic diagnosis was not obtained were regarded to have a benign nodule because the nodules did not change in diameter (n = 32) or decreased in diameter (n = 5). Nodules that did not change in size were followed up with CT at least once or more than once over 9–14 months (mean, 11.7 months; standard deviation, ±1.3 months).
Radiation Exposure
Radiation exposure was determined by means of thermoluminescent dosimetry, as described by Jung et al (18). Total organ doses of thin-section, dynamic, and staging CT studies were calculated. Four lithium fluoride chips were placed in the bilateral upper and lower lung zones of the irradiated lungs of a phantom: one in the right upper lung zone, one in the left upper lung zone, one in the right lower lung zone, and one in the left lower lung zone. Radiation doses were measured twice: once with the presumption that the nodule was located in the upper lung zone and once with the presumption that the nodule was located in the lower lung zone. The radiation doses (at nodule sites and at other lung sites away from the nodule locations) were calculated by measuring the doses absorbed by the lithium fluoride chips placed inside the phantom. The measured organ dose was compared with that at standard thoracic helical CT (beam collimation of 20 mm, beam pitch of 0.75, 0.8-second rotation time, 120 kVp, and 210 mA) at our institution.
Evaluation of Morphologic Features at Targeted Thin-Section CT
One radiologist (K.S.L.) with 14 years of experience in chest CT evaluated the morphologic features. Morphologic features of nodules, including margins, presence or absence of a satellite lesion, and cavity were assessed. Nodule margins were classified as smooth, lobulated, or spiculated. Long-axis diameters of the nodules were also measured on images with lung window settings.
Evaluation of Enhancement Dynamics
After viewing all 130 images as thumbnail images on a picture archiving and communications monitor, we selected one image for analysis from the 13 images obtained at each time point. The selected image was the transverse section with the largest diameter (scanned at the equator of the nodule). We measured attenuation values of the nodules in the same area on the selected image for each cluster at each time point (ie, from the unenhanced image to the image acquired at 15 minutes). A circular region of interest was placed over the nodule. We examined a region of interest that covered about one-half of the diameter of the nodule at the equator. When we were confronted with areas that were calcified (n = 8; average area at the selected image, 5%; range, 2%–20%), cavitary (n = 9; average area, 24%; range, 2%–40%), or necrotic (n = 22; average area, 17%; range, 5%–60%), these areas were avoided so that the region of interest was made as large as possible away from these areas. All Hounsfield unit measurements were performed by using mediastinal window images to ensure that partial volume averaging was minimized.
Two radiologists (Y.J.J. and K.S.L., with 2 and 14 years of experience in chest CT, respectively) measured the attenuation values independently. All measurements were obtained at the time of the CT examination, and the radiologists were blinded to features, including patients' age and clinical history, that might influence their CT measurements. Two measurements were obtained for each nodule at each imaging phase by each observer. Each observer recorded the mean attenuation values and then analyzed and calculated the following dynamic characteristics of tumor enhancement by using wash-in and washout values of the contrast medium: peak enhancement, net enhancement (wash-in), and absolute and relative loss of enhancement (washout). Peak enhancement was defined as the maximum attenuation value of the nodule over the entire duration of the dynamic study. Net enhancement was calculated by subtracting the preenhancement attenuation value from the peak enhancement attenuation value. Absolute loss of enhancement at delayed imaging was calculated by subtracting the attenuation value at 15 minutes (AT15) from the peak enhancement attenuation value (ATpeak). The relative percentage loss of enhancement was calculated as follows: [(ATpeak – AT15)/ATpeak] · 100.
Data and Statistical Analyses
Statistical analyses were performed by using commercially available software (SAS 8.2; SAS Institute, Cary, NC). Agreement in measured attenuation values of nodules between the two observers was analyzed by calculating the intraclass correlation coefficient.
A retrospective calculation was used to evaluate the usefulness of net enhancement as a marker for malignant nodules (vs benign nodules) at early-phase dynamic CT. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated by varying the level of enhancement that signified a positive finding (cutoff value).
Washout was also calculated retrospectively at different cutoff levels to differentiate malignant nodules from benign nodules during the delayed phase of dynamic CT.
Diagnostic characteristics—that is, sensitivity, specificity, accuracy, positive predictive value, and negative predictive value—were calculated by considering both the wash-in (net enhancement) and washout (absolute loss of enhancement) characteristics at dynamic CT.
The 
2 test, Fisher exact test, Student t test, and Mann-Whitney test were used to analyze statistically significant differences between morphologic features and attenuation values for unenhanced imaging, net enhancement, and absolute and relative loss of enhancement in malignant and benign nodules. P < .05 was considered to indicate a significant difference.
Multivariate analysis was performed by using the multiple logistic regression method to see how the morphologic characteristics and dynamic enhancement CT results were useful independently from each other in distinguishing between malignant and benign nodules. In other words, we investigated whether a factor of morphologic characteristics and dynamic CT results was related to the outcome variable (malignancy), adjusting the effect of the other factor in the model.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Unenhanced Targeted Thin-Section CT
Of 107 nodules, 49 (46%) proved to be malignant and 58 (54%) proved to be benign (Table 1). One bronchial carcinoid tumor was classified as malignant. The sizes (in diameter) of the 107 nodules were as follows: In 11 patients, nodules were 5.6 mm or larger but were smaller than 10 mm; in 28 patients, nodules were 10 mm or larger but were smaller than 15 mm; in 32 patients, nodules were 15 mm or larger but were smaller than 20 mm; in 15 patients, nodules were 20 mm or larger but were smaller than 25 mm; and in 21 patients, nodules were 25 mm or larger but were smaller than 30 mm. Malignant nodules were significantly larger (mean diameter, 20.4 mm ± 6.1 [standard deviation]; range, 8.3–30.0 mm) than benign nodules (mean diameter, 16.2 mm ± 6.5; range, 5.6–30.0 mm) (P = .001, Student t test). Lobulated margins (P < .001, 2 test) and spiculated margins (P < .001, 2 test) were more frequently observed than were smooth margins in malignant nodules. Calcification (two of 49 malignant nodules [4%] vs 13 of 58 benign nodules [22%], P = .007) or satellite lesions (three of 49 malignant nodules [6%] vs 18 of 58 benign nodules [31%], P = .001, 2 test) were more frequently seen in benign nodules.
|
The characteristics of the enhancement dynamics of nodules on early-phase contrast-enhanced CT are summarized in Table 2. The mean attenuation value for the 58 benign nodules on unenhanced CT scans was 44 HU ± 11.8 (range, 14–84 HU), whereas that for the 49 malignant nodules was 47 HU ± 7.0 (range, 32–62 HU). The mean attenuation value of benign nodules on unenhanced CT scans was not significantly different from that of malignant nodules (P = .141).
|
Delayed Enhancement CT and Washout of Contrast Material
Malignant nodules showed greater washout of contrast enhancement (15 HU ± 7.3; range of 0–34 HU in absolute loss or 15% ± 6.0 in relative loss) than did benign nodules (14 HU ± 19.9; range of 0–90 HU in absolute loss or 14% ± 14.8 in relative loss) (P < .001 and .035, respectively; Mann-Whitney test). Considering the nodule dynamics of both early and delayed enhancement CT, several diagnostic rates were retrospectively calculated at different cutoff values (Table 3). Considering the nodule dynamics of both early and delayed enhancement CT, four kinds of enhancement pattern were observed (Tables 4, 5; Fig 1). Most malignant nodules (46 of 49, 94%) showed more than 25 HU wash-in and 5–31 HU washout of contrast medium (Fig 2). Of 58 benign nodules, 27 showed less than 25 HU wash-in (Fig 3), 14 showed persistent enhancement without washout and with more than 25 HU wash-in (Fig 4), and 11 showed more than 31 HU washout and more than 25 HU wash-in (Fig 5, Table 4).
|
|
|
|
|
|
|
|
|
|
Each of the diagnostic criteria for malignancy—fulfilling both more than 25 HU wash-in and 5–31 HU washout (P < .001; odds ratio, 25.7), lobulated margin (P = .011; odds ratio, 41.7), spiculated margin (P = .006; odds ratio, 35.3), and absence of satellite nodule (P = .004; odds ratio, 13.8)—was useful for the diagnosis of a malignant nodule from the multivariate analysis controlling the effect of other diagnostic factors.
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
Transport of contrast medium through the lung involves the intravascular and interstitial spaces (20). The vascular supply of most malignant pulmonary nodules is from the bronchial arterial system (20,21). Washout from the intravascular space in malignant nodules takes place via the bronchial veins. A large interstitial space has been found in some human and experimental malignant tumors (22). Most important, in the washout phase from the interstitial space, a near absence or substantial reduction of lymphatic flow is noted in malignant tumors (20). The retarded flow in the intravascular and interstitial spaces would contribute to the retention of contrast medium in malignant nodules. In most inflammatory pulmonary processes, because of diffuse thrombosis at the arterioles of the pulmonary circulation, the vascular supply is actually from the bronchial arteries, which are shown to increase in size and number (23). Outflow of contrast medium (washout) through the intravascular space in an inflammatory situation is taking place through relatively straight vessels with a normal configuration, and washout of contrast medium from the interstitial space is accelerated by active lymphatic flow (24). In the inflammatory nodules, the time-attenuation curve declines after reaching peak height because of normal washout (7). In malignant nodules, the curve changes little after reaching peak height because of the retarded flow in the washout phase.
In our study, one malignant nodule (an adenocarcinoma) and 14 benign nodules showed persistent enhancement without washout. We speculate that persistent enhancement without washout on dynamic contrast-enhanced CT scans may be related to the amount and degree of fibrosis (25–27). Delayed uptake of contrast medium may be attributed to redistribution of it. Namely, in the early phase, the well-vascularized tumor cell zones show contrast enhancement; once contrast medium moves into abundant fibrous tissue with scanty blood supply in the late phase, it remains there, showing the fibrotic portion of the nodule for a long time without washout.
To the best of our knowledge, no evaluation of the accuracy of a protocol based on the combination of these two properties (wash-in and washout characteristics) has been reported. In our study, the threshold value, wash-in enhancement of 25 HU or more, was reached by all malignant nodules. However, by analyzing the wash-in phase only, the false-positive rate was 52% (30 of 58 benign nodules). The use of the washout characteristics of dynamic enhancement allowed us to correctly diagnose 24 of 30 benign nodules and to reduce the false-positive rate.
In our study, in 45 of 49 malignant nodules the peak level of enhancement occurred within 5 minutes of initiating the injection of contrast material. However, in four malignant nodules the peak level of enhancement occurred more than 5 minutes after injection. The mean time to peak enhancement in malignant nodules was 3.2 minutes. In a previous study (5), the peak level of enhancement in most malignant nodules (96%) occurred during the first 2 minutes after initiating the injection. Therefore, the authors of that study pointed out the diagnostic importance of attenuation measurements over the first 2 minutes of dynamic CT. However, in our study, only 57% of the malignant nodules showed peak enhancement during the first 2 minutes after injection was initiated. Yamashita et al (19) observed that some lung carcinomas reached peak enhancement late, at 5 minutes. This finding reflects the fact that some lung carcinomas have a wide extravascular fluid pool. Contrast enhancement values obtained at CT are a summation of the intra- and extravascular concentrations of contrast medium. The distribution of contrast material approaches a balance at 5 minutes after injection, being directly related to the volume of the extracellular space, with more than 80% of the contrast medium remaining outside blood vessels (28).
The real clinical value of dynamic contrast-enhanced CT for the differentiation of malignant and benign nodules may be in the evaluation of radiologically indeterminate small nodules, in which it is difficult to perform biopsy successfully. In our study, 36% of nodules (39 of 107) were less than 15 mm in diameter. In a previous study by Swensen et al (2), 44% of nodules (47 of 107) were less than 15 mm in diameter.
In our study, the measured total organ dose at thin-section, dynamic, and staging CT ranged from 98 to 115 mGy at the nodule sites. This dose at nodule location is about five times larger than that used for single–detector row helical CT (18–19 mGy with 1–10-mm collimation, 120 kVp, 300 mAs) (29) and is about two and half times larger than that used for standard helical multi–detector row CT (39–40 mGy) performed at our institution. However, this organ dose applies only to the thin (3 cm in length along the z-axis) bandlike area of the nodule location. An increased band of organ dose at a nodule location in women may often be in the breast tissue, and, therefore, this technique may not be appropriate for women with a low pretest probability of malignancy or even to young women when a T1N0 lung cancer is suspected. The dose (35–40 mGy) in other areas is similar to or slightly lower than that with our standard helical CT technique. We obtained a total of 10 series of images at various times for 15 minutes. Because images obtained at certain time points may provide little information, truncation of the protocol (not obtaining an image series at, for example, 9 minutes and 12 minutes) might have contributed to the mitigation of radiation dose.
There were several limitations to our study. First, pathologic proof was not obtained for all benign nodules. However, although the follow-up period was somewhat short (average, 11.7 months), follow-up CT scans helped to diagnose benignancy by showing no growth or a decrease in the size of nodules.
Second, we did not attempt to standardize the injection rate or volume of contrast material according to the cardiac output for each patient, and we did not routinely use CT software techniques (SmartPrep; GE Medical Systems) to time the initiation of scanning in consideration of peak enhancement. For a more uniform and standardized delivery of contrast medium while reducing the total amount of contrast medium injected, saline chaser can be administered with a double-barrel injector (30). In addition, we did not standardize the volume of contrast material according to patient weight. However, these techniques are either variably used or not used in clinical practice, and, therefore, we believe that our results are likely to reflect those in the clinical situation.
Third, no pathophysiologic data or proof is presented to explain the washout characteristics of benign and malignant nodules. However, angioarchitectural differences, such as the integrity of cellular membranes or the extracellular space volumes, might be present in benign and malignant nodules (31,32). It should also be pointed out that placing the regions of interest accurately on nodules is important when attempting to measure their attenuation values on CT scans. Inadequate placement of regions of interest on nodules leads to erroneous attenuation values, which can lead to false wash-in and washout enhancement calculations.
Fourth, our study may contain a selection bias. We excluded 10 patients with no histologic diagnosis or follow-up images. However, most of the excluded patients had no follow-up study or study of less than 6 months, and some patients were excluded because they refused to undergo surgery or biopsy. Neither surgical criteria nor dynamic CT results precluded our including patients in this study.
Fifth, we arbitrarily chose a 15-minute delay, which we believe allowed enough time for the washout of contrast material from a pulmonary nodule, given practical time constraints. Although this modality did not provide a perfect test, the application of attenuation threshold values of wash-in and washout resulted in the differentiation of benign and malignant nodules with high sensitivity and specificity.
Sixth, the threshold values (
25 HU of net enhancement and 5–31 HU of washout for malignant nodules) chosen in this study were derived retrospectively from the data and were then applied to get diagnostic characteristics. Consequently, the high sensitivity, specificity, and accuracy values may not be the same in future studies.
Finally, we used fixed-form CT imaging (2.5-mm collimation) and reconstruction (2.5-mm) parameters for covering 3 cm along the z-axis. If we acquired thinner (eg, 1.0-mm-reconstruction) images, evaluation of smaller nodules (<7 mm in diameter) on dynamic images would have been feasible.
In conclusion, malignant nodules can be characterized by means of a net enhancement of 25 HU or more and a washout of 5–31 HU. Benign nodules can be characterized by means of a net enhancement of less than 25 HU, a net enhancement of 25 HU or more in combination with a washout enhancement of 31 HU or more, or a net enhancement of 25 HU or more and persistent enhancement without washout. The evaluation of solitary pulmonary nodules by analyzing combined wash-in and washout characteristics at dynamic multi–detector row CT proved useful for differentiating between benign and malignant nodules. However, our study is still a category of work in progress. Further multi-institutional studies, especially those on radiation dose reduction by means of truncating image acquisition sequences and those on imaging parameters (eg, different machines, section thickness, or pitch) are needed.
|
FOOTNOTES |
|---|
Authors stated no financial relationship to disclose.
Author contributions: Guarantor of integrity of entire study, K.S.L.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, Y.J.J., K.S.L., H.K., O.J.K.; clinical studies, Y.J.J., S.Y.J., M.J.C., S.S.S.; statistical analysis, Y.J.J., K.S.L., S.W.K.; and manuscript editing, Y.J.J., K.S.L., M.J.C., S.S.S., O.J.K.
|
References |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
|---|
This article has been cited by other articles:
|
|
 |
|
  F. Girvin and J. P. Ko Pulmonary Nodules: Detection, Assessment, and CAD Am. J. Roentgenol., October 1, 2008; 191(4): 1057 - 1069. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. J. Chae, J.-W. Song, J. B. Seo, B. Krauss, Y. M. Jang, and K.-S. Song Clinical Utility of Dual-Energy CT in the Evaluation of Solitary Pulmonary Nodules: Initial Experience Radiology, September 16, 2008; (2008) 2492071956. [Abstract] [Full Text]
|
|
|
|
|
|
S. Satoh, Y. Kitazume, S. Ohdama, Y. Kimula, S. Taura, and Y. Endo Can Malignant and Benign Pulmonary Nodules Be Differentiated with Diffusion-Weighted MRI? Am. J. Roentgenol., August 1, 2008; 191(2): 464 - 470. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. J. Chae, J. B. Seo, H. W. Goo, N. Kim, K.-S. Song, S. D. Lee, S.-J. Hong, and B. Krauss Xenon Ventilation CT with a Dual-Energy Technique of Dual-Source CT: Initial Experience Radiology, August 1, 2008; 248(2): 615 - 624. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Cronin, B. A. Dwamena, A. M. Kelly, and R. C. Carlos Solitary Pulmonary Nodules: Meta-analytic Comparison of Cross-sectional Imaging Modalities for Diagnosis of Malignancy Radiology, March 1, 2008; 246(3): 772 - 782. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Honda, T. Johkoh, H. Sumikawa, A. Inoue, N. Tomiyama, N. Mihara, Y. Fujita, M. Tsubamoto, M. Yanagawa, T. Daimon, et al. Pulmonary Nodules: 3D Volumetric Measurement with Multidetector CT Effect of Intravenous Contrast Medium Radiology, December 1, 2007; 245(3): 881 - 887. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. S. Lee, C. A. Yi, S. Y. Jeong, Y. J. Jeong, S. Kim, M. J. Chung, H. Y. Kim, Y. K. Kim, and K. H. Lee Solid or Partly Solid Solitary Pulmonary Nodules: Their Characterization Using Contrast Wash-In and Morphologic Features at Helical CT Chest, May 1, 2007; 131(5): 1516 - 1525. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. J. Jeong, C. A. Yi, and K. S. Lee Solitary Pulmonary Nodules: Detection, Characterization, and Guidance for Further Diagnostic Workup and Treatment Am. J. Roentgenol., January 1, 2007; 188(1): 57 - 68. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. B. Lobrano Partnerships in Oncology and Radiology: The Role of Radiology in the Detection, Staging, and Follow-up of Lung Cancer Oncologist, July 1, 2006; 11(7): 774 - 779. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. A Yi, K. S. Lee, B.-T. Kim, J. Y. Choi, O. J. Kwon, H. Kim, Y. M. Shim, and M. J. Chung Tissue Characterization of Solitary Pulmonary Nodule: Comparative Study Between Helical Dynamic CT and Integrated PET/CT J. Nucl. Med., March 1, 2006; 47(3): 443 - 450. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
