HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jonisch, A. I. Articles by Israel, G. M. Search for Related Content PubMed PubMed Citation Articles by Jonisch, A. I. Articles by Israel, G. M.

Can High-Attenuation Renal Cysts Be Differentiated from Renal Cell Carcinoma at Unenhanced CT?¹

¹ From the Department of Diagnostic Radiology, Yale University School of Medicine, PO Box 208042, 333 Cedar St, New Haven, CT 06520-8042. Received March 29, 2006; revision requested May 30; revision received June 9; accepted July 7; final version accepted September 18. Address correspondence to G.M.I. (e-mail: gary.israel{at}yale.edu).

Purpose: To retrospectively determine if renal cell carcinoma can be differentiated from high-attenuation renal cysts at unenhanced computed tomography (CT) based on Hounsfield unit measurements and heterogeneity.

Materials and Methods: The Human Investigation Committee at our institution approved this study with waiver of informed consent. This study was compliant with the HIPAA. Fifty-four pathologically proved renal cell carcinomas in 54 patients (36 men and 18 women; average age, 53 years; range, 23–90 years) and 56 high-attenuation renal cysts in 51 patients (30 men and 21 women; average age, 63 years; range, 28–86 years) were retrospectively evaluated at unenhanced CT. Two independent readers reviewed randomized unenhanced CT images and obtained Hounsfield unit readings of each mass. A subjective determination of lesion heterogeneity was also performed by using a four-point scale (1: homogeneous, 2: mildly heterogeneous, 3: moderately heterogeneous, 4: markedly heterogeneous). Statistical analysis was performed by using Bland-Altman regression tree, classification and regression tree, and Shapiro-Wilk normality test.

Results: The average attenuation of cysts for reader 1 was 53.4 HU (range, 23–113 HU) and for reader 2 was 53.8 HU (range, 21–108 HU). The average attenuation of neoplasms for reader 1 was 34.7 HU (range, 21–60 HU) and for reader 2 was 38.4 HU (range, 22–60 HU). For cyst heterogeneity, a score of 1 was given in 55 of 56 (98%) cysts for reader 1 and in 53 of 56 (95%) cysts for reader 2. For neoplasm heterogeneity, a score of 1 was given in 35 of 54 (65%) neoplasms for reader 1 and in 36 of 54 (67%) for reader 2. Given the distribution of cyst and tumor attenuation values and lesion heterogeneity, a homogeneous mass measuring 70 HU or greater at unenhanced CT has a greater than 99.9% chance of representing a high-attenuation renal cyst.

Conclusion: The findings from this study may help differentiate high-attenuation renal cysts from renal cell carcinomas at unenhanced CT and may suggest the next appropriate imaging study for definitive characterization.

© RSNA, 2007

This article has been cited by other articles:

				H. Siddiki, J. G. Fletcher, B. McFarland, N. Dajani, N. Orme, B. Koenig, M. Strobel, and S. M. Wolf Incidental Findings in CT Colonography: Literature Review and Survey of Current Research Practice. J. Law Med. Ethics, June 1, 2008; 36(2): 320 - 331. [PDF]