PET identifies transitional metabolic change in the spinal cord following a subthreshold dose of irradiation

Abstract

Positron emission tomographic (PET) investigations were performed to obtain in vivo information on symptomless radiation-induced pathological changes in the human spinal cord. PET investigations were carried out prior to radiotherapy and during the regular follow-up in an early hypopharyngeal cancer patient (the spinal cord was irradiated with a biologically effective dose of 80 Gy2), with [18F]fluorodeoxyglucose (FDG), [11C]methionine and [15O]butanol as tracers; radiosensitivity and electroneuronographic (ENG) studies were also performed. A very low background FDG accumulation (mean standardized uptake values, i.e. SUV: 0.84) was observed in the spinal cord before the initiation of radiotherapy. An increased FDG uptake was measured 2 months after the completion of radiotherapy (mean SUV: 1.69), followed by a fall-off, as measured 7 months later (mean SUV: 1.21). By 44 months after completion of irradiation, the FDG accumulation in the irradiated segments of the spinal cord had decreased to a level very close to the initial value (mean SUV: 1.11). The simultaneous [15O]butanol uptake results demonstrated a set of perfusion changes similar to those observed in connection with the FDG accumulation. The patient exhibited an extremely low [11C]methionine uptake within the irradiated and the nonirradiated spinal cord during the clinical course. She has not had any neurological symptoms, and the results of central ENG measurements before radiotherapy and 2 months following its completion proved normal. Radiobiological investigations did not reveal unequivocal signs of an increased radiosensitivity. A transitory increased spinal cord FDG uptake following radiotherapy may be related to the posttherapeutic mild inflammatory and regenerative processes. The normal [11C]methionine accumulation observed is strong evidence against intensive cell proliferation. The high degree of normalization of the temporarily increased FDG uptake of the irradiated spinal cord segments by 44 months is in good agreement with the results of monkey studies, which demonstrated a nearly complete recovery from radiation-induced spinal cord injury.

Neuromyelitis Optica Spectrum Disorder: 2-Deoxy-2-[¹⁸F]Fluoro-D-Glucose Positron Emission Tomography Findings

“…The [ 18 F]FDG PET showed hypermetabolic foci (maximum SUV 5.1) in the sarcoidosis of the spinal cord and [ 18 F]FDG uptake increased in radiation myelopathy. [1][2][3][4][5]18) The present findings revealed that [ 18 F]FDG PET was also useful for detecting the inflammatory sites of the spinal cord in neuromyelitis optica. 22) …”

Prognostic Value of 18F-FDG PET in Monosegmental Stenosis and Myelopathy of the Cervical Spinal Cord

“…After initially increased 18 F-FDG uptake (SUV max # 2.7) within the area of demyelination, a slow normalization of glucose utilization can be observed. The decline of the increased glucose metabolism is accompanied by a good clinical recovery under treatment with glucocorticoids (31)(32)(33)(34). These authors suggest that the regionally increased 18 F-FDG uptake is caused by reparative processes in radiation-induced damage to the spinal cord.…”

Changes in18F-Fluorodeoxyglucose Uptake in the Spinal Cord in a Healthy Population on Serial Positron Emission Tomography/Computed Tomography

“…However, those studies were done in patients with a cancer history and were conducted without follow-up PET/CT. Therapy such as radiation therapy, chemotherapy, or surgery might affect FDG uptake in the spinal cord 8-12. Also, many diseases, including spinal metastasis,13,14 spinal sarcoidosis,15,16 and myelopathy,17-19 can increase FDG uptake in the spinal cord.…”