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Renal Masses: Quantitative Assessment of Enhancement with Dynamic MR Imaging¹

¹ From the MR Research Division, Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD 20814-4799 (V.B.H., M.N.H., P.L.C.); and Department of Diagnostic Radiology, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Md (V.B.H., S.F.A., M.N.H., P.L.C.). Received June 14, 2001; revision requested July 6; final revision received February 14, 2002; accepted March 12. Address correspondence to V.B.H. (e-mail: vho@usuhs.mil or vho@nih.gov).

View larger version (142K): [in a new window]   Figure 1. Serial coronal spoiled gradient-echo images (120/4.2; flip angle, 80°) obtained during dynamic imaging of three cysts (*) in a single left kidney, a, at baseline and, b-f, 1-5 minutes after intravenous administration of contrast media. c, At 2 minutes, the lesions demonstrate a 1% change in signal intensity.

View larger version (174K): [in a new window]   Figure 2. Serial coronal spoiled gradient-echo images (120/4.2; flip angle, 80°) of a solid renal tumor (arrow) in the upper pole of the right kidney, a, before administration of contrast material and, b-f, 1-5 minutes after intravenous administration of contrast media demonstrate mild lesion enhancement. c, At 2 minutes, the lesion demonstrates a 28% change in signal intensity. Final diagnosis is papillary renal cancer.

View larger version (136K): [in a new window]   Figure 3. Serial coronal spoiled gradient-echo images (120/4.2; flip angle, 80°) of a solid renal tumor (arrow) in the upper pole of the right kidney, a, before administration of contrast material and, b-f, 1-5 minutes after intravenous administration of contrast media demonstrate moderate lesion enhancement. c, At 2 minutes, the lesion demonstrates an 86% change in signal intensity. Final diagnosis is clear cell renal carcinoma.

View larger version (120K): [in a new window]   Figure 4. Serial coronal spoiled gradient-echo images (100/4.2; flip angle, 60°) of a solid renal tumor (arrow) in the middle pole of the right kidney is noted to have a slowly enhancing center, a, before administration of contrast material and, b-f, 1-5 minutes after intravenous administration of contrast media. c, At 2 minutes, the lesion demonstrates dramatic enhancement with a 167% change in signal intensity. Note gradual filling in of the central portion of the tumor and its isointensity with renal parenchyma. Final diagnosis is clear cell renal carcinoma.

View larger version (25K): [in a new window]   Figure 5. Graph depicts the relative percentage of enhancement for renal cysts () and tumors () versus time. There is a small amount of overlap at the 15% threshold level (arrow) that is best used to distinguish the two groups. Note that there are some inherent variations when obtaining signal intensity measurements with this method whereby higher values may be seen on the precontrast images and yield an apparent negative enhancement. For practical purposes, these instances should be treated as showing no enhancement.