In vivo assessment of Lauren classification for gastric adenocarcinoma using diffusion MRI with a fractional order calculus model

Objectives To evaluate the performance of a fractional order calculus (FROC) diffusion model for imaging-based assessment of Lauren classification in gastric adenocarcinoma. Methods In this study, 43 patients (15 females, 28 males) with gastric adenocarcinoma underwent MRI at 1.5 T. According to pathology-based Lauren classification, 10 patients had diffuse-type, 20 had intestinal-type, and 13 had mixed-type lesions. The diffuse and mixed types were combined as diffuse-and-mixed type to be differentiated from the intestinal type using diffusion MRI. Diffusion-weighted images were acquired by using eleven b-values (0-2000 s/mm(2)). Three FROC model parameters comprising diffusion coefficient D, intravoxel diffusion heterogeneity beta, and a microstructural quantity mu, together with a conventional apparent diffusion coefficient (ADC), were estimated. The mean parameter values in the tumour were computed by using a percentile histogram analysis. Individual or linear combinations of the mean parameters in the tumour were used to differentiate the diffuse-and-mixed type from the intestinal type using descriptive statistics and receiver operating characteristic (ROC) analyses. Results Significant differences were observed between diffuse-and-mixed-type and intestinal-type lesions in D (0.99 +/- 0.20 mu m(2)/ms vs. 1.11 +/- 0.23 mu m(2)/ms; p = 0.036), beta (0.37 +/- 0.08 vs. 0.43 +/- 0.11; p = 0.043), mu (7.92 +/- 2.79 mu m vs. 9.87 +/- 1.52 mu m; p = 0.038), and ADC (0.81 +/- 0.34 mu m(2)/ms vs. 0.96 +/- 0.19 mu m(2)/ms; p = 0.033). Among the individual parameters, mu produced the largest area under the ROC curve (0.739). The combinations of (D, beta, mu) and (beta and mu) produced the best overall performance with a sensitivity of 0.739, specificity of 0.750, accuracy of 0.744, and area under the curve of 0.793 (95% confidence interval: 0.657-0.929). Conclusion Diffusion MRI with the FROC model holds promise for non-invasive assessment of Lauren classification for gastric adenocarcinoma.