This month's Editor's Favorite authors Xu et al's article "Imaging Brain Metastasis Patients With 18F-(2S,4R)-4-Fluoroglutamine" presents initial imaging results with 18F-FGln as a new PET radiotracer for brain metastasis. Seven men and 7 women; age, 25–67 years with suspected brain metastasis were imaged with 18F-FGln PET followed by 18F-FDG PET performed in the same week. The characteristics of 18F-FGln PET imaging in patients with brain metastasis were compared with 18F-FDG PET and contrast-enhanced MRI patient-by-patient. Dynamic scans in 3 patients demonstrated that 30 ± 10 minutes after injection is optimal for identifying brain metastasis with a high-contrast ratio. All patients were positive for brain metastasis with 38 total lesions. The per-lesion detection rates for 18F-FGln PET and 18F-FDG PET were 81.6% and 36.8%, respectively. The mean tumor-to-normal brain ratio of 18F-FGln PET was significantly better than 18F-FDG PET in all patients (4.97 ± 2.23 vs 1.22 ± 0.69, P < 0.05). 18F-FGln uptake in brain metastasis was independent of tumor size and peripheral edema. In 14 brain metastatic lesions visualized by both 18F-FDG PET and 18F-FGln PET, a positive correlation of SUVmax was observed (r = 0.780, P < 0.01).
Initial imaging results on the new PET radiotracer 18F-FGln are promising for the detection and characterization of brain metastases.