Question 問(wèn)題：

Studies have demonstrated the utility of MRI for detection of subarachnoid hemorrhage after an initial false-negative NCCT. ?Yet，why do guidelines still recommend LP for cases of suspicious SAH, even after negative MRI??

研究顯示在首次假陰性平掃CT后可以做MRI診斷蛛網(wǎng)膜下腔出血（SAH）。但是，為什么即使MRI陰性，指南還是建議對(duì)疑似SAH病例做腰穿？

?Answer 答案：

Because MRI is ineffective at detecting perimesencephalic SAH, a spontaneous bleed of presumed venous etiology at the level of the brainstem, which accounts for 8-10% of all SAH. Overall, PMSAH has an excellent prognosis。

因?yàn)镸RI對(duì)腦干水平可能的靜脈自發(fā)性出血，即占全部SAH5-10%的中腦周?chē)鶶AH（PMSAH）陽(yáng)性率低?？傮w上，PMSAH預(yù)后是相當(dāng)好的。

參考文獻(xiàn)：

Emerg Radiol, epub, 2/13/21