4701. The Impact of Posttreatment MR Perfusion and Spectroscopy on Clinical Decision-Making in Neuro-Oncology: A Prospective Study
Authors * Denotes Presenting Author
  1. Samir-Anthony Dagher *; The University of Texas MD Anderson Cancer Center
  2. Ho-Ling Liu; The University of Texas MD Anderson Cancer Center
  3. Burak Ozkara; The University of Texas MD Anderson Cancer Center
  4. Vinodh Kumar; The University of Texas MD Anderson Cancer Center
  5. Max Wintermark; The University of Texas MD Anderson Cancer Center
  6. Donald Schomer; The University of Texas MD Anderson Cancer Center
  7. Melissa Chen; The University of Texas MD Anderson Cancer Center
The addition of MR perfusion and spectroscopy to routine imaging protocols increases scan time and costs, and calls for the expertise of MRI technologists and neuroradiologists. However, it is unclear whether these sequences significantly impact management decisions in the neuro-oncology practice. The purpose of this study is to determine the clinical usefulness of these sequences in the current clinical practice, for brain tumor patients with posttreatment changes on conventional MRI, by prospectively comparing treatment decisions before and after MR perfusion and spectroscopy.

Materials and Methods:
An IRB-approved, survey-based, prospective cohort study was conducted at our comprehensive cancer center between March 1, 2017, and October 31, 2020. Adult patients with (1) a confirmed histomolecular diagnosis of glioblastoma (IDH-wildtype, or astrocytoma, IDH-mutant, WHO Grade 4), (2) who completed radiotherapy, and (3) underwent MR perfusion and spectroscopy after conventional MRI as part of their routine clinical evaluation were included. Four MR sequences were performed as part our institutional advanced brain tumor imaging (ABTI) protocol: pseudocontinuous arterial spin labeling, dynamic contrast-enhanced, dynamic susceptibility contrast, and proton MR spectroscopy imaging. Hyperlinks to pre- and post-ABTI REDCap surveys were emailed to the neuro-oncologist as soon as the ABTI order was placed, and once the results were reported by the neuroradiologist, respectively. Data related to treatment decision were gathered using multilevel categorical variables in both questionnaires, then analyzed with SPSS version 28.0. The primary endpoint was to measure the change in treatment decision after ABTI and compare it to the one by Geer et. al., using the Wald test for independent samples proportions. An exploratory analysis using the McNemar-Bowker test of symmetry was then performed, followed by a posthoc power analysis, to further evaluate changes in management with ABTI.

A total of 70 patients were recruited in this study, of which 60 (85.7%) had glioblastoma, IDH-wildtype. ABTI revealed progression in 38 cases (54.3%). A change in treatment decision after ABTI occurred in 44.3% (32.6 – 55.9%) of patients and was significantly different from the reported change of 8.5% by Geer et al. in 2012 (<em>p</em> < 0.001). There were no significant differences in specific treatment strategies pre- and post-ABTI (<em>p</em> = 0.706), as the study was underpowered for this exploratory outcome (the required sample size to achieve a power of 80% was 242). However, neuro-oncologists found ABTI results helpful in 92.9% of cases (86.8 – 98.9%), hence increasing their confidence in their treatment plan without necessarily altering it.

The current ABTI protocol impacts clinical decision-making and helps neuro-oncologists manage patients with high-grade gliomas. Adding MR sequences, such as perfusion and spectroscopy, to protocols increases costs to patients and institutions, so ensuring clinical utility is of paramount importance.