Multi-b-value diffusion weighted imaging MRI in evaluation of renal tumors：preliminary results / 中华泌尿外科杂志

ABSTRACT

Objective To determine the significance of the quantitative parameters obtained from intravoxel incoherent motion ( IVIM) diffusion weighted imaging ( DWI) in differentiating renal tumors from normal renal tissues.Methods Twenty-four patients with surgical pathology-proven renal tumors and 13 volunteers with healthy kidneys were included.DWI was performed with 9 b-values (0, 20, 50, 100, 200, 400, 600, 800 and 1 000 s/mm2).The slow component of diffusion (Dslow), fast component of diffusion ( Dfast ) and fraction of fast ADC ( f) of the biexponential DWI were calculated for the clear cell renal cell carcinoma (CCRCC), the normal renal parenchyma and the non CCRCC ( NCCRCC) .The ADC was calculated for all b-values using linear regression yielding standard ADC ( ADCtot ) .The parameters were compared among the groups, and the receiver operating characteristic ( ROC ) analysis was performed. Results CCRCC showed higher ADCtot (1.73 ±0.43) ×10 -3 mm2/s, Dfast (14.75 ±14.73) ×10 -3 mm2/s, Dslow(1.34 ±0.38) ×10 -3 mm2/s than NCCRCC (ADCtot(1.23 ±0.26) ×10 -3 mm2/s, Dfast(9.47 ± 5.27) ×10 -3 mm2/s, Dslow(0.58 ±0.15) ×10 -3 mm2/s), and the differences of ADCtot(P=0.037) and Dslow(P=0.001) were significant.The normal renal parenchyma showed higher ADCtot (2.25 ±0.11) × 10 -3 mm2/s, Dslow ( 1.74 ±0.17 ) ×10 -3 mm2/s, f ( 35.00% ±9.37%) than CCRCC ( f, 31.13% ± 10.75%) and NCCRCC(f, 33.76%±24.02%), and the differences between the normal renal parenchyma and CCRCC of ADCtot ( P =0.000 ) and Dslow ( P =0.001 ) were significant.There were no differences between the normal renal parenchyma and the tumor ipsilateral renal parenchyma of all parameters.Dslow had higher accuracy ( sensitivity 95%, specificity 100%) in distinguishing CCRCC and NCCRCC, with area under the curve of 0.988.Conclusions Multi-b-value DWI derived quantitative parameters including ADCtot and Dslow may differ significantly between the renal tumor and normal renal parenchyma.Dslow is the best parameter in distinguishing CCRCC and NCCRCC.