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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.

Copyright © 2012 Wolters Kluwer Health, Inc. All rights reserved.