Association of magnetic resonance imaging–based preoperative tumor volume with postsurgical survival time in dogs with primary intracranial glioma

OBJECTIVE To assess the relationship between preoperative volume of primary intracranial gliomas in dogs as determined via MRI and survival time after surgical debulking and adjunctive immunotherapy. DESIGN Retrospective cohort study. ANIMALS 47 client-owned dogs enrolled in clinical trials regarding glioma treatments. PROCEDURES Medical records of all dogs undergoing craniotomy at the University of Minnesota Veterinary Medicine Center with histologically confirmed glioma between 2008 and 2015 were retrospectively reviewed, and outcome data were collected. Preoperative T2-weighted or post–gadolinium administration T1-weighted MRI scans, performed at several referral institutions with scanners of magnet strengths ranging from 0.5 to 3.0 T, were used to measure tumor volumes as a percentage of total calvarial volume. Data were analyzed to assess the effect of each 2% fraction of tumor volume on median survival time (MST) after surgery and adjuvant treatment. RESULTS Tumor volumes ranged from 0.5% to 12.2% o...