Intravoxel incoherent motion MRI for the initial characterization of non-fatty non-vascular soft tissue tumors

To compare the capabilities of intravoxel incoherent motion (IVIM) to those of monoexponential diffusion-weighted imaging for differentiating benign from malignant non-vascular, non-fatty soft tissue tumors (NVSFSTT).

A total of 64 patients with 64 histologically confirmed soft-tissue tumors were retrospectively included. There were 23 men and 41 women with a mean age of 52±17 (SD) (range: 18-92 years). IVIM parameters, including molecular diffusion restriction coefficient (ADC_true), perfusion fraction, and tissue perfusion related coefficient were compared to mean monoexponential ADC (ADC_std) values. Two readers calculated all parameters, which were compared to histopathological findings that were used as standard of reference.

The overall performance of ADC_true and ADC_std was similar for the benign-malignant differentiation of NFNVSTT with accuracies ranging from 73% to 75% for both readers (P=0.3). Interobserver reproducibility was considered excellent for both ADC_std and all IVIM parameters (ICC=0.81-0.96). When myxoid tumors were excluded from morphological analysis, an increase in sensitivity of 16-21% of ADC_true was observed, with no changes in specificity values. The use of perfusion related IVIM parameters in association with ADC_true did not improve tumor characterization.

The use of IVIM parameters does not improve the characterization of NVNFSTT by comparison with conventional monoexponential ADC calculation.