Solitary brain lesions enhancing at MR imaging: evaluation with fluorine 18 fluorocholine PET

Abstract

Purpose: To prospectively determine whether differences between benign and malignant brain lesions can be depicted with fluorine 18 ((18)F) fluorocholine positron emission tomography (PET).

Materials and methods: Thirty consecutive patients (14 women, 16 men; age range, 26-79 years) with solitary brain lesions that were enhanced at magnetic resonance (MR) imaging underwent whole-brain (18)F-fluorocholine PET after giving informed consent in this institutional review board-approved, HIPAA-compliant study. Histopathologic diagnoses were made in 24 cases (13 high-grade gliomas, eight metastases to the brain, and three benign lesions). In six cases, benign lesions were diagnosed on the basis of longitudinal follow-up MR findings. The maximum standardized uptake value (SUV(max)) for lesion and peritumoral regions was measured on PET images, and a lesion-to-normal tissue uptake ratio (LNR) was calculated. Differences were assessed with one-way analysis of variance, Fisher exact, and Student t tests.

Results: Differences in SUV(max) between high-grade gliomas (1.89 +/- 0.78 [mean +/- standard deviation]), metastases (4.11 +/- 1.68), and benign lesions (0.59 +/- 0.31) were significant (P < .0001). LNRs also differed significantly (5.15 +/- 2.51, 10.91 +/- 2.14, and 1.28 +/- 0.32, respectively; P < .0001). These differences were also significant at pairwise analysis. The peritumoral LNR exceeded 2.0 in seven high-grade gliomas and no metastases (P = .02). In 14 radiation-treated patients, the lesions classified as benign demonstrated significantly less uptake compared with the recurrent tumors (SUV(max): 0.72 +/- 0.38 vs 2.27 +/- 1.24, P < .01; LNR: 1.36 +/- 0.43 vs 5.88 +/- 3.66, P < .01).

Conclusion: High-grade gliomas, metastases, and benign lesions can be distinguished on the basis of measured fluorocholine uptake. Increased peritumoral fluorocholine uptake is a distinguishing characteristic of high-grade gliomas.