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Qualitative Assessment of Enhancement in a Renal Mass: Contribution of Subtraction CT

Kambadakone, Avinash MD, DNB, FRCR*; Arasu, Vignesh A. BS*; Samir, Anthony E. MD*; Eisner, Brian H. MD; Kulkarni, Naveen M. MD*; Hahn, Peter F. MD, PhD*; Sahani, Dushyant V. MD*

Journal of Computer Assisted Tomography: July/August 2012 - Volume 36 - Issue 4 - p 381–387
doi: 10.1097/RCT.0b013e318256b1ba
Abdominal Imaging

Purpose: To evaluate the impact of subtraction CT on reader confidence and diagnostic accuracy when characterizing renal masses.

Materials and Methods: In this institutional review board–approved retrospective study, 159 patients (85 men and 74 women; mean age, 62.6 years; range, 22–88 years) underwent routine unenhanced and contrast-enhanced multidetector computed tomography (MDCT) for renal lesion characterization. Subtraction images were subsequently generated on scanner console. Two readers independently reviewed the MDCT images to characterize presence of enhancement using a 6-point scale during 3 blinded review sessions of (1) only subtraction, (2) routine, and (3) combined subtraction and routine images. The standard of reference consisted of either histopathology or follow-up imaging and clinical data.

Results: Of the 240 lesions evaluated, 60 lesions (mean, 3.2 cm; range, 1–7.5 cm) were enhancing and 180 lesions (mean, 2.7 cm; range, 0.5–12 cm) were nonenhancing. For determination of lesion enhancement, a combined evaluation of routine MDCT and subtraction images improved reader confidence in 60% to 63% of lesions (P < 0.001). The combined evaluation also provided the highest sensitivity (97%), specificity (99%), and accuracy (98.9%).

Conclusion: When used in combination with routine image interpretation, subtraction CT improves reader confidence and diagnostic accuracy in identifying enhancement in renal lesions.

From the *Division of Abdominal Imaging and Intervention, Department of Imaging, and †Department of Urology, Massachusetts General Hospital, Boston, MA.

Received for publication December 28, 2011; accepted March 21, 2012.

Reprints: Dushyant V. Sahani, MD, Massachusetts General Hospital, 55 Fruit St, White 270, Boston, MA 02114 (e-mail:

The authors report no conflicts of interest.

© 2012 Lippincott Williams & Wilkins, Inc.