The diagnostic accuracy of magnetic resonance imaging and cerebrospinal fluid cytology in leptomeningeal metastasis

Diagnostic decision making in the case of patients suspected of having lept omeningeal metastasis (LM) can be very difficult. The results of cerebrospi nal fluid (CSF) cytology can be repeatedly negative, and the predictive val ue of gadolinium-enhanced magnetic resonance imaging (MRI) is not well:know n. We report the results of CSF cytology and Gd MRI in 61 patients with kno wn cancer, suspected of having LM. We combined our data with those from a s imilar study and calculated the sensitivity and specificity of CSF and Gd M RI, in the absence of a "gold standard diagnosis." CSF cytology was positiv e for LM in 35 patients and MRI in 38. With CSF cytology sensitivity 75% an d specificity 100%, with Gd MRI sensitivity was 76% but specificity only 77 %. We conclude that Gd MRI provides strong support in the diagnosis of LM i n patients with cancer who have negative results on CSF cytology.