Metrizamideによる髄腔および髄液循環動態の検討—特にmetrizamide CT cisternographyにおける水平面形成について

STUDY OF THE PATHWAY AND THE DYNAMICS OF CEREBROSPINAL FLUID BY THE ADMINISTRATION OF METRIZAMIDE : SPECIAL REFERENCE TO METRIZAMIDE CT CISTERNOGRAPHY

I．はじめに

　Metrizamide （Amlpaque^R）は髄腔の形態の検査として脊髄造影，脳室撮影などに利用され，従来の造影剤にない利点が認められている。頸胸髄腔や頭蓋内クモ膜下腔に注入しても比較的安全で，油性造影剤であるMyodilのごとき検査後の残留もなく，gas造影のごとき検査後の頭痛，嘔吐少ない。

　さらに，Greitz　＆　Hindmarsh^8）によつて始められたmetrizamide CT cisternography （metrizamide CTC）はCSF dynamicsを描出することで脚光を浴び，水頭症の診断^2,3,12）などに応用されている。

50 patients (31 adults, 17 children and 2 infants) were submitted to the computerized tomographic study after the intrathecal administration of Metrizamide (Amipaque), those diagnoses were cerebrovascular disease—15, brain tumors—14, head injury—2, hydrocephalus—4, subdural hygroma—5, arachnoid cyst—7 and miscellaneous—3. The main purpose of the study was the examination of cir?\culatory dynamics of the cerebrospinal fluid (Metrizamide CT cisternography). CT assisted ventriculography and CT assisted myelography were also performed in 5 cases.

6 ml of isotonic (170 mgI/m/) Metrizamide were administered through lumber tap for adult cases and 3 ml for children. In 14 cases of adult, 3 ml of Metrizamide was injected through the high cervical (C₁-C₂) lateral tap. After the injection, the patient was kept in supine position with slightly elevated head in order to avoid the artifact from the higher specific gravity (1.184) of the drug. CT scans were done at 15 min., 3 hrs. and 6 hrs. after injection in the cases of cervical tap, and after 1 hr., 3 hrs., 6 hrs. and 24 hrs. in the case of lumbar tap. When the finding of ventricular reflex was noticed, CT was done up to 24 hrs. and 48 hrs. respectively. The CT scanners used were Siemens' Siretom I and Siretom 2000.

In the Metrizamide CT cisternography through lumbar route, the intracranial CSF spaces were clearly enhanced 1 hr. after injection. (In the cases of children, the density of the space was higher than that of adults.) After 6 hrs., the contrast media spreaded diffusely over the convexity, and disappeared after 24 hrs. in the normal circulation. In the method of high cervical route, the large cistern and the basal cistern were enhanced a few minutes after injection. The dynamics of CSF then after revealed the same manner as the lumbar route. The advantages of the high cervical route were the fewer volume of the drug and the shorter period of the examination.

In 22 cases, the findings of ventricular reflux were noted, 6 cases of which showed persistent ventricular filling. In 9 cases of ventricular reflux, the "niveau formation" was seen, which might be caused by the higher gravity of Metrizamide and it should be regarded as one of the important diagnostic evidences of normal pressure hydro-cephalus. The "niveau formation" with upper low density area was seen especially in the anterior horn of lateral ventricles and that was a quite different finding from RI cisternography in which the RI accumulation appeared remarkably in there.

Metrizamide CT cisternography could be applied to the examination of communicability of the CSF in the arachnoid cyst or the subdural hygroma with subarachnoid space. For the diagnosis of the extension of juxtabasal tumors, Metrizamide CT cisternography was useful also. The juxtabasal tumors were clearly contoured out by Metrizamide CT cisternography.

CT assisted ventriculography was also useful for the diagnosis of the shift of IVth ventricle com-pressed by the large cerebellar tumor. CT assisted myelography revealed diagnostic value for the spinal lesions.

The side effects of Metrizamide such as headache, nausea and vomiting were minimal and temporary, and no convulsion was observed.