Brain metastases assessment by FDG-PET/CT: can it eliminate the necessity for dedicated brain imaging?

• Published in: Egyptian journal of radiology and nuclear medicine 2020-11, Vol.51 (1), p.223-11
• Main Authors: Zidan, Mamdouh A, Hassan, Radwa S, El-Noueam, Khaled I, Zakaria, Yasser M
• Format: Article
• Language: English
• Subjects: Brain; Brain cancer; Brain tumors; Clinical medicine; Computed tomography (CT); CT imaging; Dextrose; Fluoro-2-deoxy-d-glucose (FDG); Glucose; Kidney cancer; Lymphomas; Medical imaging; Medical prognosis; Metastases; Metastasis; Neuroimaging; Patients; PET imaging; Positron emission tomography (PET); Scanners; Software; Tumors
• ISSN: 0378-603X; 2090-4762
• DOI: 10.1186/s43055-020-00342-8

Background Brain metastases (BM) are the most common intracranial tumors in adults outnumbering all other intracranial neoplasms. Positron emission tomography combined with computed tomography (PET/CT) is a widely used imaging modality in oncology with a unique combination of cross-sectional anatomic information provided by CT and the metabolic information provided by PET using the [.sup.18F]-2-fluoro-2-deoxy-d-glucose (FDG) as a tracer. The aim of the study is to assess the role and diagnostic performance of brain-included whole-body PET/CT in detection and evaluation of BM and when further imaging is considered necessary. The study was conducted over a period of 12 months on 420 patients suffering from extra-cranial malignancies utilizing brain-included whole-body PET/CT. Results Thirty patients with 71 brain lesions were detected, 18 patients (60%) had BM of unknown origin while 12 patients (40%) presented with known primary tumors. After brain-included whole-body FDG-PET/CT examination, the unknown primaries turned out to be bronchogenic carcinoma in 10 patients (33.3%), renal cell carcinoma in 2 patients (6.7%), and lymphoma in 2 patients (6.7%), yet the primary tumors remained unknown in 4 patients (13.3%). In 61 lesions (85.9%), the max SUV ranged from 0.2- < 10, while in 10 lesions (14.1%) the max SUV ranged from 10 to 20. Hypometabolic lesions were reported in 41 (57.7%) lesions, hypermetabolic in 3 lesions (4.2%), whereas 27 lesions (38.0%) showed similar FDG uptake to the corresponding contralateral brain matter. PET/CT overall sensitivity, specificity, positive and negative predictive, and accuracy values were 78.1, 92.6, 83.3, 90, and 88% respectively. Conclusion Brain-included whole-body FDG-PET/CT provides valuable complementary information in the evaluation of patients with suspected BM. However, the diagnostic performance of brain PET-CT carries the possibility of false-negative results with consequent false sense of security. The clinicians should learn about the possible pitfalls of PET/CT interpretation to direct patients with persistent neurological symptoms or high suspicion for BM for further dedicated CNS imaging.