Improved Detection of Postoperative Residual Meningioma with [⁶⁸Ga]Ga-DOTA-TOC PET Imaging Using a High-resolution Research Tomograph PET Scanner.

Abstract

PET with somatostatin receptor ligand [⁶⁸Ga]Ga-DOTA-D-Phe¹-Tyr³-octreotide ([⁶⁸Ga]Ga-DOTA-TOC) is an established method in radiotherapy planning because of the improved detection and delineation of meningioma tissue. We investigated the diagnostic accuracy of supplementary [⁶⁸Ga]Ga-DOTA-TOC PET in patients with a 3-month postoperative MRI reporting gross-total resection (GTR). Thirty-seven patients with a histologically proven meningioma and GTR on postoperative MRI were prospectively referred to [⁶⁸Ga]Ga-DOTA-TOC PET. Detection and volume measurements of [⁶⁸Ga]Ga-DOTA-TOC-avid lesions in relation to the primary tumor site were recorded. Residual tumor in suspicious lesions suggested by [⁶⁸Ga]Ga-DOTA-TOC PET was verified by (i) tumor recurrence/progression on subsequent MRI scans according to the Response Assessment of Neuro-Oncology criteria, (ii) subsequent histology, and (iii) follow-up [⁶⁸Ga]Ga-DOTA-TOC PET scan. Twenty-three PET scans demonstrated [⁶⁸Ga]Ga-DOTA-TOC-avid lesions suspicious of residual meningioma, where 18 could be verified by (i) tumor progression on subsequent MRI scans (<i>n</i> = 6), (ii) histologic confirmation (<i>n</i> = 3), and (iii) follow-up [⁶⁸Ga]Ga-DOTA-TOC PET scans confirming the initial PET findings (<i>n</i> = 9) after an overall median follow-up time of 17 months (range, 9-35 months). In contrast, disease recurrence was seen in only 2 of 14 patients without [⁶⁸Ga]Ga-DOTA-TOC-avid lesions (<i>P</i> < 0.0001). The sensitivity, specificity, and diagnostic accuracy of [⁶⁸Ga]Ga-DOTA-TOC PET in detecting meningioma residue was 90% [95% confidence interval (CI), 67-99], 92% (95% CI, 62-100), and 90% (95% CI, 74-98; <i>P</i> < 0.0001), respectively. The majority of patients with GTR on 3-month postoperative MRI may have small unrecognized meningioma residues that can be detected using [⁶⁸Ga]Ga-DOTA-TOC PET.