Abstract
Quantitative evaluation of radioisotope (RI) cisternography was performed by single photon emission computed tomography (SPECT) in eight patients suspected of chronic hydrocephalus or malfunction of a shunt system, showing symptoms for two to 24 months, and one control patient with cerebrospinal fluid (CSF) leakage ten years after head trauma. Criteria of ventricular dilation by CT scan were satisfied in seven of the eight patients. The patients were given an injection of 1 ml of 1 mCi indium-111 diethylene triamine pentaacetic acid (In-Ill DTPA) via the lumbar route (seven cases) or ventricular catheter (two cases). Regular evaluations were scheduled (4, 7, 10-12, 24, 48 and 72 hours after injection). The region of interest, about 1.3 cm in radius and 0.8 cm in height, was placed in cisterna magna, sylvian cistern, basal cistern, and interhemispheric cistern as well as in the ventricle using a reconstructed image of a horizontal section by SPECT. Clearance curves were calculated with estimated decreasing count of RI each time by the method of exponential regression coefficients. Discrimination of the disease was attempted using the values of constant K of clearance curve and biological half-life time (BHT). Diagnosis of hydrocephalus was satisfactorily made in five patients demonstrating K values lower than 0.04 in all the cisterns expect for the cisterna magna, as well as BHT longer than 18-20 hours. Three of the five patients were treated with ventriculo-peritoneal (VP) shunt (two reconstructions of shunt systems and one VP shunt), and all of the improved. Although the remaining two patients were diagnosed as having hydrocephalus from the study, surgery was not performed, because of complicating psychiatric and malignant gastrointestinal diseases. Each patient diagnosed as Parkinson's disease or Alzheimer's disease showed a higher K value and shorter BHT than those in hydrocephalic patients. This tendency became clearer in the control patient with CSF leakage. Thus quantitative RI cisternography was highly valuable in the discrimination of chronic hydrocephalic from non-hydrocephalic patients with definitive dilation of the ventricles or symptoms similar to normal pressure hydrocephalus. This study may also be useful for estimation of the degree of impairment of CSF circulation.
