Jesse Montagnese DO, Presenter: Nothing to Disclose

Andrew Sher MD, Abstract Co-Author: Research Grant, Koninklijke Philips NV

Salim E. Abboud MD, Abstract Co-Author: Nothing to Disclose

Lisa Rogers MD, Abstract Co-Author: Nothing to Disclose

Norbert Avril MD, Abstract Co-Author: Nothing to Disclose

Leo John Wolansky MD, Abstract Co-Author: Nothing to Disclose

Advanced imaging is often utilized in the post-treatment period of high-grade intra-axial neoplasm to better characterize enhancing lesions. Our study compares the diagnostic accuracy of 18F-FDG PET/CT and 18F-FDG PET/MR in differentiating progressive disease (PD) from radiation change (RC).

We evaluated 12 patients with high-grade intra-axial neoplasm whom had undergone radiation therapy and developed MR evidence of PD per RANO criteria. 13 lesions were evaluated:10 glioma; 2 metastatic patients (3 lesions). All patients underwent 18F-FDG PET/CT, 18F-FDG PET/MR (with MR attenuation correction, PET/MRAC), conventional diagnostic MR (PET/MRD), and perfusion MR in a single exam. Four separate interpretations were performed of the PET/CT, PET/MRAC, PET/MRD, and perfusion PET/MR with consensus readings by two fellowship-trained radiologists (1 neuroradiology; 1 nuclear). A qualitative subjective rating was given to each lesion (1 = definite RC; 2 = probable RC; 3 = equivocal; 4 = probable PD; 5 = definite PD). The fourth interpretation session was considered the reference standard (11 PD, 2 RC). Sensitivity, specificity, and accuracy were determined for the three interpretation sessions (PET/CT, PET/MRAC, PET/MRD) via ROC analysis after binary reclassification, with a rating of 1-3 defined as RC and 4-5 as PD. Wilcoxon-rank test was used for rating comparison between the three interpretations.

PET/CT yielded a sensitivity, specificity, and accuracy of 0.64, 1.00, and 0.82 (p=0.17), respectively. PET/MRAC demonstrated a sensitivity, specificity, and accuracy of 0.91, 1.00, and 0.96 (p<0.05), respectively. PET/MRD had the highest sensitivity, specificity, and accuracy of 1.00, 1.00, and 1.00 (p<0.05), respectively. There was a statistically significant difference in interpretation between PET/MRD and PET/CT (p<0.05), but not PET/MRAC and PET/CT (p=.08).

In this small series, 18F-FDG PET/MR utilizing either diagnostic or attenuation-only MR sequences was more accurate in differentiating radiation change from progressive disease compared to 18F-FDG PET/CT, with a statistically significant difference in interpretation between 18F-FDG PET/MR with diagnostic MR and 18F-FDG PET/CT.

Differentiation of radiation change from progressive disease has significant clinical ramifications requiring divergent treatment. PET/MR is a promising technique in differentiating PD from RC.

Montagnese, J, Sher, A, Abboud, S, Rogers, L, Avril, N, Wolansky, L, Utility of 18F-FDG PET/MR in Differentiation of Recurrent High-grade Intra-axial Neoplasm from Radiation Changes: A Comparison of PET/CT to PET/MR.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012102.html