Comparative study of conventional diffusion-weighted imaging and introvoxel incoherent motion in assessment of pathological grade of clear cell renal cell carcinoma

Abstract

Objective: To quantitatively compare the diagnostic values of conventional diffusion-weighted imaging (DWI) and introvoxel incoherent motion (IVIM) analysis of microstructural differences for clear cell renal cell carcinoma (ccRCC). Methods: Multiple b value DWIs and IVIMs were performed in patients with 146 ccRCCs, 42 with Grade Ⅰ, 46 with Grade Ⅱ, 28 with Grade Ⅲ and 30 with Grade Ⅳ. These tumours were divided into low (Ⅰ+Ⅱ, n = 88) and high grades (Ⅲ+Ⅳ, n = 58). The diagnostic efficacy of various diffusion parameters for predicting ccRCC grades was compared. Results: The mean signal-to-noise ratios (SNRs) of IVIM images at b = 0, 800 and 1500 s/mm2 were 31.9, 12.3 and 8.4, respectively. The apparent diffusion coefficient (ADC), D and D* values correlated negatively with ccRCC grading (r = -0.786,–0.913, −0879, p < 0.05). f values correlated positively with ccRCC grading (r = 0.811, p < 0.05). The ADC, D and D* values were higher for Grade Ⅱ ccRCC than that of Grade Ⅲ ccRCC (p < 005), however, f values were higher for Grade Ⅲ ccRCC than that of Grade Ⅱ ccRCC (p < 005). Receiver operating characteristic curve analyses showed that D values had the highest diagnostic efficacy in differentiating low/high and Ⅱ/Ⅲ ccRCC grading. The area under the curve, sensitivity, specificity and accuracy of the D values were 0.963, 0.960; 90.9%, 89.1%; 81.0%,78.6 and 89.0%, 87.8%, respectively. For pairwise comparisons of receiver operating characteristic curves and diagnostic efficacy, ADC was worse than IVIM (all p < 0.05). Conclusion: IVIM parameters have better performance than ADC in differentiating ccRCC grading, given an adequate SNR of IVIM images. Advances in knowledge: 1. D values had the highest diagnostic efficacy in differentiating low/high and Ⅱ/Ⅲ ccRCC grading. 2. IVIM parameters have better performance than ADC in differentiating ccRCC grading, given an adequate SNR of IVIM images. 3. The ADC, D and D* values correlated negatively with ccRCC grading, however, f values correlated positively with ccRCC grading.

Multiparametric MRI of Solid Renal Masses: Principles and Applications of Advanced Quantitative and Functional Methods for Tumor Diagnosis and Characterization

“…32 Multiple studies have suggested the potential added value of certain IVIM-derived parameters compared to ADC due to its increased specificity and sensitivity in assessing tissue diffusion and perfusion. 35,38,40,41 Although ADC values can reliably differentiate benign SRM from RCC due to its ability to assess microcirculation and tissue cellularity, its use in further tumor characterization may be limited. Artifacts and variability in ADC due to combination of different b-values and protocol parameters used in different radiology centers limits its multicenter reliability for diagnosis.…”

“…Similarly, an additional comparative study also demonstrated the accuracy of IVIM parameters relative to ADC in the grading of ccRCCs, assuming adequate signal‐to‐noise ratios (SNR). A positive correlation between f values and ccRCC grading was also demonstrated ( r = 0.811, P < 0.05), likely due to an increased abundance of capillaries within high‐grade ccRCC vs. low‐grade ccRCC 41 . Of note, D values were shown to have the highest diagnostic efficacy in determining low‐grade vs. high‐grade ccRCC (1.42 ± 0.42 × 10 −3 vs. 0.89 ± 0.23 × 10 −3 , P < 0.01) and grade 2 vs. 3 ccRCC (1.31 ± 0.31 × 10 −3 vs. 0.76 ± 0.27 × 10 −3 , P < 0.01) 41 .…”

“…A positive correlation between f values and ccRCC grading was also demonstrated ( r = 0.811, P < 0.05), likely due to an increased abundance of capillaries within high‐grade ccRCC vs. low‐grade ccRCC 41 . Of note, D values were shown to have the highest diagnostic efficacy in determining low‐grade vs. high‐grade ccRCC (1.42 ± 0.42 × 10 −3 vs. 0.89 ± 0.23 × 10 −3 , P < 0.01) and grade 2 vs. 3 ccRCC (1.31 ± 0.31 × 10 −3 vs. 0.76 ± 0.27 × 10 −3 , P < 0.01) 41 . Results of published studies summarizing the role of DWI/ADC and IVIM investigation in renal mass characterization are summarized in Table 2.…”

“…40 Similarly, an additional comparative study also demonstrated the accuracy of IVIM parameters relative to ADC in the grading of ccRCCs, assuming adequate signal-to-noise ratios (SNR). A positive correlation between f values and ccRCC grading was also demonstrated (r = 0.811, P < 0.05), likely due to an increased abundance of capillaries within high-grade ccRCC vs. low-grade 41 Results of published studies summarizing the role of DWI/ADC and IVIM investigation in renal mass characterization are summarized in Table 2.…”

“…ccRCC 41. Of note, D values were shown to have the highest diagnostic efficacy in determining low-grade vs. highgrade ccRCC (1.42 AE 0.42 Â 10 À3 vs. 0.89 AE 0.23 Â 10 À3 , P < 0.01) and grade 2 vs. 3 ccRCC (1.31 AE 0.31 Â 10 À3 vs. 0.76 AE 0.27 Â 10 À3 , P < 0.01).…”