Spinal 111Indium-DTPA CSF flow studies in leptomeningeal metastasis

Sixteen consecutive patients (8 men; 8 women; age range 6-63 years, median 40 years) with leptomeningeal metastasis were found by radionuclide ventriculography to have cerebrospinal fluid (CSF) flow interruption at the following sites: cisterna magna/basal cisterns (6); cervical (5) and thoracic (3) spinal subarachnoid space. Two additional patients had no evidence of interruption of CSF flow. All patients underwent intralumbar injection of 111Indium-DTPA and imaging of spinal ascent of radionuclide, corroborating sites of CSF flow disruption seen by radionuclide ventriculography. Median (range) time to appearance in lumbar, thoracic and cervical spinal subarachnoid compartments were 1 (1), 22.5 (20-25) and 32.5 (30-35) minutes respectively. Appearance of radionuclide in the cisterna magna/basal cisterns, sylvian cisterns, ventricular system and high cerebral convexity was 37.5 (35-40), 65 (60-70), 1440 (1440) and 1440 (1440) minutes respectively. Only 1 of 8 patients with interruption of CSF flow within the spinal subarachnoid space shown by intralumbar radionuclide flow study, was seen by either CT myelography or contrast enhanced spine MR to have CSF flow block. No patient with base of brain block (0/6) shown by radionuclide CSF flow studies demonstrated CSF flow disruption by either cranial contrast enhanced CT or MR. In conclusion, spinal 111In-DTPA CSF flow studies confirmed sites of CSF flow block shown by radionuclide ventriculography and demonstrate the feasibility of assessing CSF compartmentalization by intralumbar radionuclide administration. Furthermore, radionuclide CSF flow studies when compared to conventional neuroradiographic imaging are more sensitive in demonstrating interruption of CSF flow.