Radionuclide cisternography: imaging and study of the cerebrospinal fluid circulation

English: English: Radionuclide cisternography performed in 200 selected patients with neurological disease has proved to be a simple and relatively safe procedure, v,rithminimal disturbing side effects, which can provide useful information about cerebrospinal fluid (eSF) flow and dynamics. Following the subarachnoid or ventricular injection of an appropiate radiopharmaceutical, the tracer flows with the eSF and demonstrates the pathways of circulation under normal and abnormal conditions with virtually no disruption of the existing eSF physiology. The eventual distribution of the tracer is complex. The range of normal varies from rapid ascent with early absorption of the radiopharmaceutical to slower ascent and absorption, frequently with laterilization of flow to one or other side intracranially and occasionally with transient ventricular reflux. In pathological states the cisternographic picture varies ac= cation (or lack of it) of the ventricles with the subarachnoid cording to the underlying disease. It may lack the ability to establish the precise anatomical features available from air encephalography. However ventricular dilatation, the communispace, and the delay or lack of absorption are only satisfactorily demonstrated by radionuclide cisternography. Repeated examinations may be readily performed to show progression of the disease or the results of surgical treatment. The abnormal flow pattern in patients with normal pressure hydrocephalus proved to be the most important criterion in their selection for extracranial neurosurgical eSF shunting. When properly selected, these patients often respond to surgical treatment. The routine use of radionuclide cisternography in the examination of patients with suspected presenile dementia and compensated hydrocephalus results in a low yield of operable patients. When operation is contraindicated conservative management of the patient is then instituted and unnecessary surgical intervention avoided. Radionuclide cisternography gained wide acceptance in the evaluation of shunt patency. The test is fast and safe in the presence of extracranial diversionary eSF shunts. The rapid flow into the cerebral ventricles and the fast disappearance of the radioactive tracer, as well as the relative size of the ventricular system, are valuable indexes for the determination of patency and efficaccy of the shunt. Another important use of radionuclide cisternography is the investigation of eSF leaks and eSF spinal flow obstruction. It may demonstrate the existence and site of eSF leakage or block and offer valuable assistance to the neurosurgeon. Radionuclide cisternographic images are usually interpreted subjectively on the basis of abnormal regional and temporal concentrations of radiopharmaceuticals in the eSF space. The evaluation of images can be improved by the use of quantitative computerized digital scanning, increasing the sensitivity and value of the measurements. The further extension of these studies involving abnormalities of cerebrospinal fluid dynamics would seem worthwhile, and the value of the methods described in this thesis and their limitations, remain a potential and challenging field for further exploration.