The role of the ADC value in the characterisation of renal carcinoma by diffusion-weighted MRI

¹ Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine, Showa-machi 3-39-22, Maebashi, Gunma 371-8510, Japan
² Department of Human Pathology, Gunma University Graduate School of Medicine, Showa-machi 3-39-22, Maebashi, Gunma 371-8510, Japan

	Abstract

The purpose of this study is to evaluate the role of diffusion-weighted imaging (DWI) in combination with T₁ and T₂ weighted MRI for the characterisation of renal carcinoma. The institutional review board approved the study protocols and waived informed consent from all of the patients. 47 patients (32 male and 15 female; age range, 21–85 years; median age, 65 years) who had suspected renal lesions on abdominal CT underwent MRI for further evaluation and characterisation of the lesions from April 2005 to August 2007 in our university hospital. A region of interest was drawn around the tumour area on apparent diffusion coefficient (ADC) maps. Final diagnosis was confirmed by histological examination of surgical specimens from all patients. The ADC value was significantly higher in renal cell carcinoma (RCC) than in transitional cell carcinoma (2.71 ± 2.35 x 10^-3 mm²•s^-1 vs 1.61 ± 0.80 x 10^-3 mm²•s^-1; p = 0.022). While analysing the histological subtypes of RCC, a significant difference in ADC values between clear cell carcinoma and non-clear cell carcinoma was found (1.59 ± 0.55 x 10^-3 mm²•s^-1 vs 6.72 ± 1.85 x 10^-3 mm²•s^-1; p = 0.0004). Similarly, ADC values of RCC showed a significant difference between positive and negative metastatic lesions (1.06 ± 0.38 x 10^-3 mm²•s^-1 vs 3.02 ± 2.44 x 10^-3 mm²•s^-1; p = 0.0004), whereas intensity on T₁ and T₂ weighted imaging did not reach statistical significance. In conclusion, DWI has clinical value in the characterisation of renal carcinomas and could be applied in clinical practice for their management.