Detection of neoplastic meningitis in a patient with gastric cancer by thallium-201 SPECT.

We describe the usefulness of thallium-201 SPECT in a patient with neoplastic meningitis (NM) from gastric carcinoma. Thallium-201 SPECT is of value for the diagnosis of cancer; retention of thallium-201 on delayed images strongly suggests malignancy. NM is a lethal, major neurologic complication of cancer. The standard for the diagnosis of NM is cytologic confirmation of malignant cells in CSF, but cytologic results are often negative (estimated false negative rate, 50%), even when NM is strongly suspected clinically. In patients with equivocal findings, our findings suggest that thallium-201 SPECT is one helpful tool for the detection of NM, particularly when associated with signet-ring cell carcinoma.