A Preliminary Study Of Intravoxel Incoherent Motion Diffusion-weighted Imaging Of The Renal Tumors

Objective:To evaluate the reproducibility of intravoxel incoherent motion diffusion-weighted imaging in normal kidney and renal tumors.Methods:Sixteen healthy volunteers (10 male,6 female, average age 30 years) and sixteen patients (12 male,4 female, average age 56 years) were examined twice using respiratory-triggered echo-planar MRI with nine b values (0,20,50,100,150,200,400, 600,800 s/mm2) 24h apart. Pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were calculated using a bi-exponential model. Reproducibility of derived parameters derived by IVIM-DWI were performed using intraclass correlation coefficient and Bland-Altman.Results:There were no significant differences in the IVIM parameters of the two repeated scan (P>0.05).There were significant differences in the parameters D between the normal renal tissue and the renal tumors (P<0.05).The ICC value of D*, D, f in healthy volunteers group were 0.764,0.824,0.556, respectively. The ICC value of D*, D, f in patient’s group were 0.690,0.964,0.538, respectively.Conclusions:D has the best reproducibility of the three parameters, D* has good reproducibility in the healthy group, while shows moderate reproducibility of the renal tumors, f shows moderate reproducibility of the two groups.Objective:To evaluate the application value of monoexponential model parameter (apparent diffusion coefficient, ADC) and biexponential model parameters derived by multiple b-values DWI in differential diagnosis of benign and malignant renal lesions.Methods:Seventy-four patients were enrolled and classified into three groups according to the surgical pathology results. One is the benign group (including 14 angiomyolipoma,1 oncocytoma and 1 solitary fibrous tumor), the second one is the clear cell RCC group (including 43 patients) and the last one is the non-clear cell RCC group (including 6 Papillary RCC and 9 Chromophobe RCC). ALL the patients underwent respiratory-triggered DWI on 3.0T MR system with single b-factor range (b=0,800 s/mm2) and multi b-values of 0,20,50,100,150,200,400,600,800 s/mm2. Apparent diffusion coefficient (ADC) were calculated using a mono-exponential model, while pure molecular-based (D), perfusion-related (D*) and perfusion fraction (f) were calculated using a bi-exponential model. The four derived parameters among three groups were compared.Results:ADC shows significant differences between benign and clear cell RCC group (P<0.05), clear cell RCC group and non-clear cell RCC group (P<0.05), no significant differences occurred between benign and non-clear cell RCC group (P=0.696>0.05). Each two groups of the three have significant differences in D* (P<0.05). For D, there were significant differences between benign and clear cell RCC group (P<0.05), clear cell RCC group and non-clear cell RCC group (P<0.05), no significant differences occurred between benign and non-clear cell RCC group (P=0.587>0.05). There are no significant differences between any two groups of the three in f. The areas under the ROC curve of ADC, D*, D and f were 0.716,0.725,0.751,0.575, respectively. The sensitivity of ADC, D*, D and f were 74.1%,69.0%,81.0%,74.1%, respectively, and the specificity of ADC, D*, D and f were 75.0%,75.0%,75.0%,37.5%, respectively.Conclusion:ADC value in monoexponential model and D as well as D* in biexponential model can be used in the differential diagnosis of benign and malignant renal lesions, among which D value shows the best diagnostic efficacy.