Texture Analysis of Fractional Water Content Images Acquired during PET/MRI: Initial Evidence for an Association with Total Lesion Glycolysis, Survival and Gene Mutation Profile in Primary Colorectal Cancer

SIMPLE SUMMARY: There is a need to demonstrate additional clinical value/utility for PET/MRI in oncology which moves beyond simple diagnosis. We believe that our currently submitted work represents an initial step in realizing the goal of moving PET/MRI beyond simple diagnosis. We report how texture analysis of parametric images depicting tumor fractional water content derived from routine PET/MRI Dixon acquisitions shows good inter-operator agreement, generates biologically relevant information related to total lesion glycolysis and gene mutation count, and provides prognostic information that can potentially unlock new clinical applications for patients with colorectal cancer. This research study resulted from a long-standing multi-disciplinary collaboration between the nuclear medicine physicians at our institute and experts in quantitative imaging, MRI radiology, GI histology, clinical oncology in colorectal cancer, and several gastrointestinal surgeons at various local hospitals. ABSTRACT: To assess the capability of fractional water content (FWC) texture analysis (TA) to generate biologically relevant information from routine PET/MRI acquisitions for colorectal cancer (CRC) patients. Thirty consecutive primary CRC patients (mean age 63.9, range 42–83 years) prospectively underwent FDG-PET/MRI. FWC tumor parametric images generated from Dixon MR sequences underwent TA using commercially available research software (TexRAD). Data analysis comprised (1) identification of functional imaging correlates for texture features (TF) with low inter-observer variability (intraclass correlation coefficient: ICC > 0.75), (2) evaluation of prognostic performance for FWC-TF, and (3) correlation of prognostic imaging signatures with gene mutation (GM) profile. Of 32 FWC-TF with ICC > 0.75, 18 correlated with total lesion glycolysis (TLG, highest: r(s) = −0.547, p = 0.002). Using optimized cut-off values, five MR FWC-TF identified a good prognostic group with zero mortality (lowest: p = 0.017). For the most statistically significant prognostic marker, favorable prognosis was significantly associated with a higher number of GM per patient (medians: 7 vs. 1.5, p = 0.009). FWC-TA derived from routine PET/MRI Dixon acquisitions shows good inter-operator agreement, generates biological relevant information related to TLG, GM count, and provides prognostic information that can unlock new clinical applications for CRC patients.