Use of DWI in the Differentiation of Renal Cortical Tumors

Abstract

OBJECTIVE The purpose of this study was to differentiate clear cell renal cell carcinoma (RCC) from other common renal cortical tumors by use of DWI. MATERIALS AND METHODS The study included 117 patients (mean age, 60 years) with 122 histopathologically confirmed renal cortical tumors who underwent 1.5-T MRI that included DWI before they underwent nephrectomy between 2006 and 2013. For each tumor, two radiologists independently evaluated apparent diffusion coefficient (ADC) values on the basis of a single ROI in a nonnecrotic area of the tumor and also by assessment of the whole tumor. The concordance correlation coefficient (CCC) was calculated to assess interreader agreement. The mean ADC values of clear cell RCC and every other tumor subtype were compared using an exact Wilcoxon rank sum test. RESULTS Interreader agreement was excellent and higher in whole-tumor assessment (CCC, 0.982) than in single-ROI analysis (CCC, 0.756). For both readers, ADC values for clear cell RCC found on single-ROI assessment (2.19 and 2.08 × 10−3 mm2/s) and whole-tumor assessment (2.30 and 2.32 × 10−3 mm2/s) were statistically significantly higher than those for chromophobe, papillary, or unclassified RCC (p < 0.05) but were similar to those for oncocytoma found on single-ROI assessment (2.14 and 2.32 × 10−3 mm2/s) and whole-tumor assessment (2.38 and 2.24 × 10−3 mm2/s). ADC values were also higher for clear cell RCC than for angiomyolipoma, but the difference was statistically significant only in whole-tumor assessment (p < 0.03). CONCLUSION ADC values were statistically significantly higher for clear cell RCC than for chromophobe, papillary, or unclassified RCC subtypes; however, differentiating clear cell RCC from oncocytoma by use of DWI remains especially challenging, because similar ADC values have been shown for these two tumor types.

Assessment of apparent diffusion coefficient value as prognostic factor for renal cell carcinoma aggressiveness

“…A few reports recommend that ADC might be related well with morphologic and histologic prognostic parameters in RCC [7]. Thus, the minimum ADC was observed to be an independent factor for recurrence of RCC after nephrectomy [8].…”

Diagnostic Imaging for Solid Renal Tumors: A Pictorial Review

“…From the enhancement pattern, pRCC can be differentiated from ccRCC with 93% sensitivity and 96% specificity [60]. ADC values are described to be higher compared with ccRCC [63]. Based on MR imaging findings, type 1 and 2 pRCCs cannot be differentiated [44].…”

“…The tumors are hypovascular and show less contrast enhancement in all phases compared with the renal cortex [64]. Although conflicting results have been reported, a meta-analysis showed that differentiation of oncocytoma from RCC based on ADC values is feasible [55,63]. However, great heterogeneity exists in the scanning protocols and b-values, making these results hard to reproduce.…”

Nichtinvasive Phänotypisierung von Nierentumoren – aktueller Stand

“…Mittels Chemical-Shift(CSI)-Sequenzen lässt sich mikroskopisches Fett nachweisen [30]. Der "apparent diffusion coefficient" (ADC) des klarzelligen RCC ist gemeinhin höher als in anderen RCC-Subtypen [15]. Ein inverser Zusammenhang zwischen dem ADC und dem FuhrmanGrad wurde berichtet [8].…”

“…Nach Kontrastmittel(KM)-Applikation (e, koronare T1w mit Fettsättigung) zeigt sich der solide Anteil kontrastmittelaffin, während der fettige Anteil signalsupprimiert ist. In der korrespondierenden KM-verstärkten Computertomografie (f arterielle Phase, g venöse Phase) zeigt der solide Anteil eine kräftige initiale Anreicherung mit Wash-out, der fettige Anteil ist annähernd isodens zum umgebenden Fettgewebe hilfreich, beide Entitäten weisen eher hö-here ADC-Werte auf [15,39].…”