Reduced Field of View Diffusion MRI for Rectal Cancer Response Assessment after Short Course Radiation and FOLFOXIRI

Motivation: Rectal cancer response assessment utilizes primarily T2 weighted and diffusion MRI. Reduced field of view diffusion has been shown to have higher imaqe quality and resolution than traditional EPI-based diffusion. Goal(s): We compare reduced field of view diffusion to mrTRG and sigmoidoscopy for assessment of clinical response. Approach: 32 patient MRI were evaluated after treatment with short course radiation (30 Gy, 5 fractions), and FOLFOXIRI and assessed with mrTRG system, ADC on reduced field of view DWI, and sigmoidoscopy. Results: Reduced field of view diffusion is highly accurate for assessment of clinical response nearly matching the performance of mrTRG and surpassing sigmoidoscopy. Impact: Reduced field of view diffusion should be considered for use in clinical protocols assessing rectal cancer treatment response along with T2 weighted MRI and clinical assessment.