2010-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/693783摘要：臨床在評估腎臟功能時，常使用核醫方式於體內注射有放射性同位素標記的藥物，在腎臟代謝這些藥物時，偵測同位素分布的濃度去做定量。但是基於單光子射出電腦斷層掃描(SPECT)在影像解析度上的不足，因此無法提供有關解剖構造相關的資訊。磁振造影(MRI; Magnetic Resonance Imaging)檢查，可以藉由單次檢查中，同時提供定量腎臟血流灌注量(renal perfusion)以及觀察腎動脈血管造影(renal angiography)等多項資訊。在動物實驗的結果中也發現，利用動態對比劑增強磁振造影技術(DCE-MRI; Dynamic contrast enhanced MRI)，不但可以定量腎臟的血流量，同時也可以透過模型的建立計算出腎絲球過濾率(GFR; glomerular filtration rate)等功能性參數。以目前的技術，我們可以建立出兼具有高時間及空間解析度的影像，可以區分出腎臟各個不同構造的顯影，在根據在時間上的分布去計算出腎臟功能的各種指標。然而，DCE-MRI所施打的gadolinium-based對比劑，卻會有引發腎因性纖維化症(NSF; nephrogenicsystemic fibrosis)的風險。過去的研究中發現，美國兩大醫學中心共83,121位曾經接受過gadolinium-based對比劑檢查的病患，發現大約有15位病患(0.02%)產生腎因性纖維化症，而這些病患大都接受過高劑量(0.3 mmol/kg)的對比劑注射，不過也發現這些病患在接受注射同時，已經伴隨有急性腎衰竭等疾病。目前我們利用DCE-MRI定量腎臟的血流量時，所需要施打的對比劑劑量只有一般劑量的1/12 (0.025 mmol/kg)，這對於腎臟功能正常或稍差的病患，產生NSF併發症的風險也相對較低。動脈標定磁振造影技術(ASL-MRI; arterial spin labeling MRI)是另一種磁振造影檢查，其具有不需施打對比劑與絕對定量血流灌注等優點，因此可以完全排除產生NSF併發症的疑慮，不過、由於其影像訊雜比較低、脈衝程序複雜等因素，因此臨床上的發展與應用目前較不普及。此計畫的目標為：(1) 利用動態對比劑增強磁振造影技術，並利用模型獨立解卷積及成分獨立分析法，定量腎臟皮質血流灌注量(ml/min/g)。(2) 建立動脈標定磁振造影技術，以絕對定量腎臟血流灌注量(ml/min/g)。(3) 在正常受試者中建立出正常腎臟灌流的統計資料，與核醫檢查方式(99m-Tc-DTPA)對照以確定其可用性，作為未來診斷與臨床應用的參考依據。(4) 在臨床的應用上，我們將使用DCEMRI來測量腎臟手術(nephrectomy or renal transplantation)後剩餘腎臟功能的變化，也將研究在早期腎臟病變對血液灌流的影響。<br> Abstract: Glomerular filtration rate (GFR) is the most useful quantitative index of renal function and is used clinically as the gold standard of diagnosing and monitoring kidney disease. 99m-Tc-DTPA is clinically used in assessment of GFR. However, the scintigraphy has the disadvantages, because of its reliance on absolute gamma camera counts. Therefore, the data from this method is relative value, thereby leading to difficulty in individual comparisons.Gadolinium-diethylenetriaminepentaacetate (Gd-DTPA) is the most common MR contrast agent used clinically. Gd-DTPA is analogous to 99m-Tc-DTPA, a true filtration marker which is widely used to measure urinary clearance. Magnetic resonance imaging (MRI) has been used to assess the renal function by using dynamic contrast-enhanced (DCE) techniques. In comparison with radionuclide methods, MRI provides better imaging quality in spatial resolution, and more feasibility for segmentation of renal function.However, exposure to gadolinium-based contrast agent has been considered to associate with subsequent development of nephrogenic systemic fibrosis (NSF), especially in the patients with chronic renal function impairment. In multiple case series, investigators have reported that high doses of gadolinium-based contrast agent contribute to an increased risk of NSF. In our protocol design, the dose of Gd-DTPA is lower as 0.025 mmol/kg, nearly one-twelfth of the standard dose in abdominal MR examination.Arterial spinning labeling (ASL) MRI is the other non-invasive MR technique that allows absolute quantification of renal perfusion without contrast agents exposed. ASL has advantage of no risk of NSF, however, lower signal-to-noise ratio and complicated post-processing may yield inaccurate perfusion values and diminished clinical feasibility.The present study is designed to determine the renal perfusion by using 3T MRI. Our primary aims are:1. To assess the feasibility of renal perfusion quantification on DCE-MRI, using Gd-DTPA in comparison with conventional radionuclide renography using Tc-99m-DTPA.2. To develop a pulsed ASL technique for quantitative measurement of renal perfusion.3. To test the clinical feasibility of DCE-MRI and ASL-MRI for renal function measurement and establish the normative value of renal perfusion in our center for clinical applications.4. To evaluate the sequential change of reserve renal function in the patients who underwent partial or total nephrectomy