鞍部及び傍鞍部腫瘍のscintigraphy

THE SCIENTIGRAPHY OF THE SELLAR AND PARASELLAR TUMORS

I．はじめに

　scintigraphyの頭蓋内腫瘍に関する平均的診断率は，腫瘍の種類，使用核種，機器の性能，手技の適否，剖検所見との相関などを考慮して，おおよそ80％前後であるとされている^{2,5,10,11,13）}。しかし，その中には髄膜腫の95％前後の高率からlow grade astrocytomaのように非常に低率のものまでを含んでおり，対象症例次第で報告される診断率にかなりのはばがある。

　又，このような病理学的要因と同時に，腫瘍の占拠部位も診断率を左右する主要な要因である。天幕上の腫瘍は一般的には天幕下の腫瘍比べれば診断率は高いが，同じ天幕上でもトルコ鞍とその周辺の腫瘍の場合は高い診断率を期待できないとされている^14）。例えばRamsey等は^17），93％の高診断率を得たが，それは下垂体腫瘍が含まれていないからであると述べている。

The scintigraphical accuracy of the tumors nearsella turcica has been less increased than that ofother intracranial tumors because of various factorswhich disturb the interpretation of scintigrams.

The scintigrams of 76 cases of seller and para-sellar tumor, which were 15 menigiomas, 25 pitu-itary adenomas, 11 craniopharyngiomas, and 6miscellaneous tumors, were reviewed and evaluatedits diagnossic value. The over-all rate of accuratediagnosis was 81%. In meningiomas we havegained 93% of accurate diagnosis which make nosignificant difference so other reports. However,in pituitary adenoma correct diagnosis was obrainedin 80% of cases and in craniopharyngioma 73% ofcases were given correct diagnosis which makesfairly high diagnossic rate as comparied previousreports.

In order to heighten the rate of diagnosis thefollowings were taken into consideration.

a) Of course, potasium perchlorate should beadministrated much enough before procedure, butsometime readministration of it is neccesary.

b) In cases of small tumor or craniopharyngiomas,intervals of several hours was needed to recorddelayed scintigraphy in addition to conventionalscintigraphy.

c) In the cases of pituitary adenomas, frontalview Scintigram was taken to record semilunaractivity (we call this moon-rise sign) in interorbitalarea which affords an important clue to its diagnosis.