行政院國家科學委員會專題研究計畫結案報告:腦部功能性磁性振造影之機制及臨床應用的研發（3/3）

Abstract

The purpose of this two-year study is to investigate the correlation of magnetic resonance imaging (MRI) and histomorphological changes in a focal brain ischemia model of rat. In the first-year project, focal cerebral ischemia was produced with a predetermined duration. MR imaging is carried out with different pulse sequences of T1WI, T2WI, PDWI and DWI. Histomorphological study included histochemical stains with H/E, and GFAP. In the second year, we emphasized the effect of different post-stroke duration. The “early” changes of the brain images as well as histochemistry were studied. We also performed artificial neural net analsysis on the images obtained in these two years. The purpose was to improve the power of the imaging technique in differentiating severity and stage of stroke. The results showed in the acute stage of stroke, only T2WI and DWI are of great value in the detection of ischemic infarction. In histomorphological study, the H/E represented a more complete or laterstage change of ischemic infarction. GFAP revealed ischemic change of different severity and might indicate incomplete or earlier ischemic change. However, the quantitative study revealed that even the most sensitive DWI was not able to show up all area with partial and complete ischemic change as in the histochmical stain of GFAP. As for the earlier ischemic changes in histomorphology and MR image, the study revealed less satisfactory resutls. Neither H/E nor GFAP can reflect different severity of stroke. This is because neuroanl damage, reactive gliosis or loss of GFAP has not yet completed in such a short duration after an ischemic stroke. The performance of the MR images in such early change of stroke is also poor. Although artificial neural net did help with further analysis of MR images of stroke, it depends on the knowledge of the original images, histomorphology and histochemistry of the ischemic lesions.

本研究利用兩年的時間，分階段研究動物模式的實驗性局部腦缺血的組織型態化學與各種磁振造影技術之間的關聯性。第一年，以定時間動脈結紮與重灌流的實驗來蒐集各種磁振造影脈衛序列( Tlwi , TZwi , PDwi , Dwi ）的訊號強度與動物的缺血性腦中風不同組織型態化學( H / E , 5100 , GFAP ）變化之定量關係。第二年則研究不同長短的中風復時間之腦組織缺血性變化與磁振影像之定量關係。並將兩年的結果以類神經網路的方法進行分析試圖改善影像對於不同中風時間及腦組織缺血嚴重度的鑑別能力。 結果顯示，在急性（24-72 小時）缺血性腦中風的情況下只有TZwi 與擴散造影技術，具偵測之價值。組織化學方面，H/E其所代表的意義是較慢性及完整之缺血變化，其變化面積較小。而GFAP 則可反應出不同嚴重度之缺血反應。其染色喪失，代表了完整嚴重之缺血性變化。染色增加之部分，代表了部分或較輕度之缺血 性變化。其可能代表腦缺血的半影區。對於組織型態化學中的GFAP 的發現，擴散影像技術並無法完全代表其範圍。至於更早期（2 -6 小時內）的缺血性變化及半影區的與組織型態學的變化則不論以H / E 或GFAP 染色觀察皆無法反應出不同嚴重度之缺血反應。因為在數小時內神經細胞死亡及膠質細胞增生之組織型態學以及GFAP 染色喪失或反應性增加之組織化學的變化皆尚未完成。磁振影像對於早期( 2 -6 小時內）缺血性腦中風的偵測功能並不完善，擴散造影（57 . 1 % , n = 14 ）與TZwi ( 2 1 . 4 % , n = 14 ）都只有偏低的早期顯現率。類神經網路的分析雖可將不同嚴重度之缺血區域分出。然而其個別區域所代表之臨床或病理之意義，端賴研究者進一步依據原有磁振影像，組織型態學以及組織化學之基礎知識予以進一步闡釋方具價值。

The purpose of this two-year study is to investigate the correlation of magnetic resonance imaging (MRI) and histomorphological changes in a focal brain ischemia model of rat. In the first-year project, focal cerebral ischemia was produced with a predetermined duration. MR imaging is carried out with different pulse sequences of T1WI, T2WI, PDWI and DWI. Histomorphological study included histochemical stains with H/E, and GFAP. In the second year, we emphasized the effect of different post-stroke duration. The ¡§early¡¨ changes of the brain images as well as histochemistry were studied. We also performed artificial neural net analsysis on the images obtained in these two years. The purpose was to improve the power of the imaging technique in differentiating severity and stage of stroke. The results showed in the acute stage of stroke, only T2WI and DWI are of great value in the detection of ischemic infarction. In histomorphological study, the H/E represented a more complete or later- stage change of ischemic infarction. GFAP revealed ischemic change of different severity and might indicate incomplete or earlier ischemic change. However, the quantitative study revealed that even the most sensitive DWI was not able to show up all area with partial and complete ischemic change as in the histochmical stain of GFAP. As for the earlier ischemic changes in histomorpho logy and MR image, the study revealed less satisfactory resutls. Neither H/E nor GFAP can reflect different severity of stroke. This is because neuroanl damage, reactive gliosis or loss of GFAP has not yet completed in such a short duration after an ischemic stroke. The performance of the MR images in such early change of stroke is also poor. Although artificial neural net did help with further analysis of MR images of stroke, it depends on the knowledge of the original images, histomorphology and histochemistry of the ischemic lesions.