Radiation Oncology

Pre-treatment (A-C) and post-treatment (D-F) images after eight cycles of systemic FOLFIRINOX and consolidative chemoradiation. Baseline CA 19-9 was 145 U/ml. Pre-treatment whole body axial fused PET/MRI showed FDG avid lesion in body of pancreas (arrow, A) with SUVmax 7.1 and SUVgluc 8.0. Lesion was hypo-enhancing on axial contrast-enhanced T1-weighted (T1W) MR image (arrow, B) from focused abdominal PET/MRI and on CT (arrow, C). Pre-treatment CT tumor volume was 10.3 cm3. Post-treatment whole body axial fused PET/MRI showed complete metabolic response (arrow D) with SUVmax 1.9 and SUVgluc 1.9. Lesion was indistinct on axial contrast-enhanced T1W MRI (arrow, E) and CT (arrow, F), and there was upstream pancreatic parenchymal atrophy. Post-treatment CT tumor volume was 0.46 cm3. There was normalization of CA 19-9. Relative change in SUVmax (ΔSUVgluc) was -73%, and relative change in SUVgluc (ΔSUVgluc) was -76%. Based on change in tumor size, response was categorized as partial response per RECIST. Relative change in tumor volume (ΔTvol) was -96%. Pathology showed major pathologic response (College of American Pathologists score 1.) Images courtesy of American Roentgen Ray Society (ARRS), American Journal of Roentgenology (AJR)