本文選題：腦血流 + 動(dòng)脈自旋標(biāo)記��； 參考：《浙江大學(xué)》2017年碩士論文

【摘要】：定量測(cè)量腦血流(CBF)作為測(cè)量灌注的方式之一,對(duì)血管性或神經(jīng)退行性疾病的病理機(jī)制的理解和診斷具有重要意義。動(dòng)脈自旋標(biāo)記技術(shù)(ASL)是目前唯一一種無創(chuàng)、無外加造影劑的定量檢測(cè)CBF的方法。但ASL存在一些誤差來源和不確定性,包括組織T1效應(yīng)、傳輸時(shí)間效應(yīng)、信噪比(SNR)低、時(shí)空分辨率低等,其魯棒性有待提高。近幾年發(fā)展起來的3DGRASEpCASL序列極大地提高了 ASL的SNR,multi-shot的讀出方式也有利于分辨率的提高,但其參數(shù)和采樣策略仍有待于進(jìn)一步優(yōu)化。顳葉癲癇伴海馬硬化(TLE-HS)與發(fā)作間期海馬區(qū)域的低灌注有重要關(guān)系。以往TLE-HS的CBF偏側(cè)性都是在忽略組織T1效應(yīng)的情況下得出的,但實(shí)際上海馬硬化的同時(shí)T1也升高,將會(huì)影響CBF偏側(cè)性。許多病變與白質(zhì)的異常灌注有關(guān),但白質(zhì)的灌注測(cè)量一直面臨SNR低和傳輸時(shí)間效應(yīng)的問題,使得ASL在白質(zhì)中的應(yīng)用受到限制。針對(duì)以上相關(guān)問題,本論文進(jìn)行了以下兩項(xiàng)主要工作:(1)本文通過仿真,并用multi-shot 3D GRASE pCASL序列采集21個(gè)高分辨的病人數(shù)據(jù),來研究組織T1對(duì)于CBF偏側(cè)化的影響。由于ASL的模型有很多種,本文選擇其中常見的三種模型:Buxton模型,ParkesI模型和ParkesS模型,并進(jìn)行比較。經(jīng)研究,使用T1成像后,偏側(cè)性中值從-2.56最多變?yōu)?6.96,診出率從61.9%最多變?yōu)?1.0%。TLE-HS的CBF偏側(cè)性提高了,使得更容易區(qū)分病人和正常人,從而提高診斷準(zhǔn)確性。與病情嚴(yán)重程度的相關(guān)性提高,使CBF偏側(cè)性可以作為病情嚴(yán)重程度的參考參數(shù)。(2)本文采用多延時(shí)(multi-PLD)采樣策略來測(cè)量白質(zhì)的CBF,以克服低SNR和傳輸時(shí)間效應(yīng)。對(duì)multi-PLD采樣策略進(jìn)行優(yōu)化,尋找有效信噪比最優(yōu)時(shí)的標(biāo)記時(shí)長(zhǎng),從而最大化白質(zhì)CBF估計(jì)的可靠性。并采用目前信噪比最高的multi-shot 3D GRASE pCASL序列采集2個(gè)健康人的數(shù)據(jù)以進(jìn)行驗(yàn)證,發(fā)現(xiàn)白質(zhì)的相關(guān)性和p值顯著的體素百分比均得到了一定的改善,CBF估計(jì)的可靠性得到了提高。
[Abstract]:Quantitative measurement of cerebral blood flow (CBF), as one of the methods of measuring perfusion, is of great significance in understanding and diagnosing the pathological mechanism of vascular or neurodegenerative diseases. Arterial spin labeling (ASL) is the only non-invasive, non-contrast agent quantitative detection method for CBF. However, there are some error sources and uncertainties in ASL, including tissue T1 effect, transmission time effect, low signal-to-noise ratio (SNR), low spatial and temporal resolution, etc. Its robustness needs to be improved. The 3DGRASEpCASL sequences developed in recent years greatly improve the SNR multi-shot readout method of ASL, but its parameters and sampling strategies still need to be further optimized. Temporal lobe epilepsy with hippocampal sclerosis (TLE-HSN) is associated with hypoperfusion in the hippocampal region during interictal period. In the past, the CBF laterality of TLE-HS was obtained by ignoring the tissue T1 effect, but in fact, the hippocampal sclerosis was accompanied by the increase of T1, which would affect the CBF laterality. Many lesions are related to abnormal perfusion of white matter, but the measurement of white matter perfusion has been faced with the problem of low SNR and transmission time effect, which limits the application of ASL in white matter. Aiming at the above problems, the following two main tasks were carried out in this paper: 1) in this paper, 21 high-resolution patient data were collected by multi-shot 3D GRASE pCASL sequence through simulation to study the effect of tissue T1 on CBF lateralization. Because there are many kinds of ASL models, this paper selects and compares three common models: 1: Buxton model (1) Parkes I model and (2) ParkesS model. After the use of T1 imaging, the median value of hemiplegia changed from -2.56 to -6.96, and the diagnostic rate from 61.9% to 81.0%.TLE-HS increased, which made it easier to distinguish patients from normal people and improve the diagnostic accuracy. In order to overcome the low SNR and transmission time effect, we use multi-delay multi-PLD sampling strategy to measure the white matter CBFs. In order to maximize the reliability of white matter CBF estimation, the multi-PLD sampling strategy is optimized to find the best marking time when the effective signal-to-noise ratio (SNR) is optimal. The multi-shot 3D GRASE pCASL sequences with the highest signal-to-noise ratio (SNR) were used to collect data from two healthy subjects for verification. It was found that both the correlativity of white matter and the percentage of voxels with significant p value improved the reliability of CBF estimation to some extent.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R445.9

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本文編號(hào)：1939133