Long-term metabolic evolution of brain metastases with suspected radiation necrosis following stereotactic radiosurgery: longitudinal assessment by F-DOPA PET.

Francesco Cicone, Luciano Carideo, Claudia Scaringi, Andrea Romano, Marcelo Mamede, Annalisa Papa, Anna Tofani, Giuseppe Lucio Cascini, Alessandro Bozzao, Francesco Scopinaro, Giuseppe Minniti

Journal: Neuro-oncology 2021;23(6):1024-1034

PMID: 33095884

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Abstract

BACKGROUND

The evolution of radiation necrosis (RN) varies depending on the combination of radionecrotic tissue and active tumor cells. In this study, we characterized the long-term metabolic evolution of RN by sequential PET/CT imaging with 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine (F-DOPA) in patients with brain metastases following stereotactic radiosurgery (SRS).

METHODS

Thirty consecutive patients with 34 suspected radionecrotic brain metastases following SRS repeated F-DOPA PET/CT every 6 months or yearly in addition to standard MRI monitoring. Diagnoses of local progression (LP) or RN were confirmed histologically or by clinical follow-up. Semi-quantitative parameters of F-DOPA uptake were extracted at different time points, and their diagnostic performances were compared with those of corresponding contrast-enhanced MRI.

RESULTS

Ninety-nine F-DOPA PET scans were acquired over a median period of 18 (range: 12-66) months. Median follow-up from the baseline F-DOPA PET/CT was 48 (range 21-95) months. Overall, 24 (70.6%) and 10 (29.4%) lesions were classified as RN and LP, respectively. LP occurred after a median of 18 (range: 12-30) months from baseline PET. F-DOPA tumor-to-brain ratio (TBR) and relative standardized uptake value (rSUV) increased significantly over time in LP lesions, while remaining stable in RN lesions. The parameter showing the best diagnostic performance was rSUV (accuracy = 94.1% for the optimal threshold of 1.92). In contrast, variations of the longest tumor dimension measured on contrast-enhancing MRI did not distinguish between RN and LP.

CONCLUSION

F-DOPA PET has a high diagnostic accuracy for assessing the long-term evolution of brain metastases following SRS.

Address: Department of Experimental and Clinical Medicine, "Magna Graecia" University of Catanzaro, Catanzaro, Italy.; Nuclear Medicine Unit, Sant'Andrea Hospital, Sapienza University of Rome, Rome, Italy.; Radiation Oncology Unit, UPMC Hillman Cancer Center, San Pietro Hospital FBF, Rome, Italy.; Neuroradiology Unit, Sant'Andrea Hospital, Department of Neuroscience, Mental Health and Sense Organs (NESMOS) Sapienza University of Rome, Rome, Italy.; Department of Anatomy and Imaging, Federal University of Minas Gerais, Belo Horizonte, Brazil.; Nuclear Medicine Unit, University Hospital "Mater Domini," Catanzaro, Italy.; Radiation Oncology Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Policlinico Le Scotte, Siena, Italy.; IRCCS Neuromed, Pozzilli (IS), Italy.

DOI: 10.1093/neuonc/noaa239

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MeSH Terms: Brain Neoplasms, Dihydroxyphenylalanine, Humans, Necrosis, Positron Emission Tomography Computed Tomography, Positron-Emission Tomography, Radiosurgery