This book reviews the current clinical practice of leptomeningeal metastasis (LM) diagnosis and treatment, which is predominately by intrathecal chemotherapy and/or in combination with external beam radiotherapy.  LM is a refractory lethal complication of many human malignancies when neoplastic cells grow in the meninges. The use of penetrating emissions from radionuclides has the advantages of visualizing cerebrospinal fluid (CSF) flow and ablating meninges at shallow depths and has been used to diagnose CSF flow anomalies and to treat LM.  The scientific bases of using radionuclides...