Leptomeningeal metastases: MR evaluation.

Area of Science:

• Neurology
• Radiology
• Oncology

Background:

• Subarachnoid dissemination of neoplasms, or leptomeningeal metastases, is a serious complication of cancer.
• Accurate detection of these metastases is crucial for patient management and treatment planning.
• Magnetic resonance (MR) imaging is a key diagnostic tool, but its sensitivity for leptomeningeal disease is debated.

Purpose of the Study:

• To evaluate the diagnostic performance of unenhanced and gadolinium-enhanced MR imaging in detecting intracranial and intraspinal leptomeningeal metastases.
• To compare the sensitivity of MR imaging with positive cerebrospinal fluid (CSF) cytology findings.

Main Methods:

• Retrospective analysis of 40 patients with confirmed CSF cytology for neoplastic seeding.
• Review of unenhanced and gadolinium-enhanced MR imaging studies of the brain and spine.
• Comparison of MR findings with cytological results, stratified by primary tumor type (CNS vs. non-CNS, lymphoma/leukemia).

Main Results:

• Overall sensitivity for MR imaging was low: 19.3% for unenhanced and 36.1% for enhanced studies.
• Gadolinium enhancement improved detection rates, particularly for spinal leptomeningeal metastases (37.5% vs. 13.8%).
• MR imaging was more sensitive in patients with non-central nervous system (CNS) primary malignancies (31.4%) compared to lymphoma or leukemia (5.6%).
• Enhanced MR images alone rarely demonstrated CSF seeding (10% for brain, 37.5% for spine).

Conclusions:

• Despite improvements with gadolinium enhancement, MR imaging demonstrates limited sensitivity for detecting leptomeningeal metastases in patients with positive CSF cytology.
• Gadolinium contrast is particularly beneficial for visualizing spinal leptomeningeal disease.
• Diagnostic accuracy varies based on the primary tumor type, with lower sensitivity for hematologic malignancies.