Intravoxel incoherent motion MR imaging: comparison of diffusion and perfusion characteristics between nasopharyngeal carcinoma and post-chemoradiation fibrosis

Objectives To compare the intravoxel incoherent motion (IVIM) diffusion and perfusion characteristics of nasopharyngeal carcinoma (NPC) and post-chemoradiation fibrosis to aid in their differentiation. Methods Fifty-three (64 %) patients with newly diagnosed NPC and 30 (36 %) patients with biopsy-proven post-chemoradiation fibrosis were recruited into tumour and fibrosis groups respectively. Diffusion-weighted magnetic resonance (MR) imaging was performed using 13 b values (0–1,000 s/mm 2 ). Their respective IVIM parameters ( D , pure diffusion; f , perfusion fraction; D *, pseudodiffusion coefficient) were obtained. Results D and f were significantly lower in NPC ( D = 0.752 ± 0.194 × 10 -3 mm 2 /s, P