Positron emission tomography-computed tomography vs. brain magnetic resonance imaging for the detection of cerebral metastases of melanoma: a 5-year retrospective study.

Background: Patients with melanoma present a high risk of developing extracutaneous metastases. Positron emission tomography--computed tomography (PET-CT) is one of the preferred examinations for the staging of oncological patients. It is not the method of choice to detect brain metastases, but this technique has shown significant improvement and allows the detection of some of them. However, it is unclear how it performs compared with magnetic resonance imaging (MRI), the current gold standard for diagnosing brain metastases.

Objectives: To compare the accuracy of PET-CT and cerebral MRI to detect brain metastases in patients with melanoma.

Methods: We retrospectively included all patients diagnosed with melanoma stage IIC-IV (American Joint Committee on Cancer 8th Edition, 2017) who presented at the skin tumour board of the University Hospital of Bern between January 2018 and December 2022. All radiological reports extracted from the patient management system were analysed to assess discrepancy between the visibility of brain metastases on PET-CT and brain MRI.

Results: In this study including 393 patients, brain MRI demonstrated significantly better performance than PET-CT in detecting brain metastases. In 47 patients, cerebral metastases were detected completely, detected partially, or not detected by PET-CT in 2 (4%), 15 (32%) and 30 (64%), respectively.

Conclusions: Despite the increasing performance of PET-CT, this study highlights the crucial role of brain MRI, which remains the gold standard to detect cerebral metastases. Brain MRI should be performed in patients with high-risk melanoma from stage IIC to exclude brain metastases.