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研究生:王碩盟
研究生(外文):Wang, Shuo-Meng
論文名稱:超音波新的應用方式:血管指數與協頻分析對於移植腎臟的評估
論文名稱(外文):A New Application of Ultrasonography: Applying Vascularity Index and Harmonic Analysis to Evaluate Transplant Kidney
指導教授:陳 淳邵耀華
指導教授(外文):J. ChenYio-Wha Shau
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:臨床醫學研究所
學門:醫藥衛生學門
學類:醫學學類
論文種類:學術論文
論文出版年:2003
畢業學年度:91
語文別:英文
論文頁數:56
中文關鍵詞:血管係數頻譜分析腎臟移植
外文關鍵詞:Vascularity indexHarmonic analysisKidney Transplantation
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一、論文中文摘要
1.背景
超音波一直是評估腎臟的重要工具,希望由不具輻射及侵入性的方法便可以對腎臟進行評估。基本的工具包括使用灰階影像來評估腎臟大小,如超音波反射值的變化、腎竇的變化。但對腎臟來說,大小改變對腎臟功能是一個晚期的指標,對腎臟的變化偵測的敏感性不佳。而阻力係數(resistance index, RI)或脈搏係數(pulsatile index,PI)雖然使用普遍,但是其所代表的生理功能仍有待研究,對RI所代表的意義大家的共識是其代表血管內的阻抗(resistance)。隨著彩色都卜勒超音波(color Doppler)1985年及強力都卜勒超音波(power Doppler)於1993年的引進,對腎臟實質部分的血管灌流新增加了一項相當實用的工具,其比美血管攝影品質的灌流探測能力,對局部灌流的研究提供了一理想的非侵入性方法。有人試著由其在腎皮質內血流灌流的程度來分類,希望能反映腎臟內的變化,或與腎功能達到相關性,但兩者皆無令人滿意的預測能力(Hilborn, 1997; Karl Turetschek, 1996; Peter FH, 1999)。雖然超音波的發展日新月異,超音波對血流偵測技術上的突飛猛進,但對其生理意義的瞭解則遠遠落後於其臨床使用上的普遍及臨床醫師的期待。在移植腎臟的臨床使用上使用已久,其使用上也以能對異常情況及早偵測為目標。使用上對於RI的測量經驗較多,而腎臟型態改變的測量、腎動脈狹窄或腎靜脈拴塞的診斷,及切片後的腎動靜脈廔管皆是超音波使用上較成熟的部分。但是以都卜勒的偵測灌流能力對移植腎進行的研究則沒有任何突破。Hilborn醫師在1997年對此下了一個結論:強力超音波主觀性的影像分析對移植腎的評估並無法增加評估上的好處(Hilborn, 1997)。
強力超音波對腎實質血液灌流優異的能力,提供了對於血液動力學進一步研究的機會,尤其腎實質豐富的血流及移植腎較表淺的位置,對周邊血液循環的研究提供了一個可行的生物模式。腎臟的皮質及髓質交接處也是動脈(artery)變成小動脈(arteriole)的地方,而此處也是生理上血壓變化最大的地方,即血管阻抗(impedance)貢獻最多的地方。壓力波的研究在大血管相對的直接及方便,可以直接測量管壁的脈動,或由侵入性的血管導管(catheter)來取的一段壓力波。對周邊血管的研究則相對貧瘠。超音波對組織內的血流偵測是一個方便而有效率的工具,如RI已應用於血管阻力的研究,而強力超音波是研究腎實質灌流理想的工具,而強力超音波的優勢,如偵測血流沒有角度限制,不受假訊號(aliasing)的影響,能提供連續的訊號等。對此連續的灌流訊號的分析卻並未見突破,對其所代表的生理意義亦不清楚,除了3-D影像加上極強的軟體處理對血液灌流影像有突破性的發展外,2-D影像使用相對較普遍卻沒有對的應用。Hilborn等人將此連續訊號定性成3或6個等級的程度外,更遑論將此連續訊號加以分析。
將腎實質的一個區域的灌流轉換成正弦曲線(sinusoid)的波型加以分析是本設計的目標,將此波型經富力葉分析轉換成多階的常數加以研究其可能的生理含意並以現有的生理學及血液動力學來加以解釋,希望能將強力超音波偵測的腎皮質灌流所代表的生理意義或及其應用方式加以研究,並進一步開發適當的軟體來增加超音波的附加價值。
血液灌流受許多因素的影響,有血液動力方面的因素,如血管阻抗(vascular impedance)、血流的黏滯性,血管的僵硬程度(stiffness),腎實質的適應性(compliance),血壓、及與身體其他器官的交互作用。在超音波的偵測方面,血比容(HCT)也會影響超音波訊號的強度。
每一個器官皆有其阻抗,在腎實質的血流由動脈進入小動脈(arteriole)時,其交接處是主要組抗產生的地方,產生的反射波代表此一血管床的反射波,也會由影響波的形狀來加以偵測。腎臟由捐腎者移植到受腎者的骨盆腔內,在三個月內RI值才會達到一個穩定的值,雖然腎臟功能常在10天左右便達到穩定,表示移植腎與受腎者的全身循環需一些適應時間,與全身阻抗需達成新的平衡。由於移植腎本身便是一個波的反射源,即有其特殊的阻抗,身上的器官也有其特殊阻抗,串連如同電阻般由同一個心臟及大血管來構成整個循環系統。當新的器官加入循環,阻抗間的共振便需重新達成,使新的器官與原來的循環達到新的平衡。如此受腎者的血型動力對移植腎便會有影響。其中影響受腎者血行動力的因素便是年紀。隨著年紀的增加,大動脈逐漸硬化,其壓力波的反射點逐漸改變,新的反射點逐漸由四肢末稍往腎動脈的進端改變,在較末稍的腎皮質波型也會跟著改變,所以當受腎者年紀增長時,在移植腎末稍循環的波型也會改變。
在1955年以前,只有少數的報告關於脈搏與頻率的關係,如Hamilton, Remington等對脈搏的研究只限於波型外觀的改變,但都沒有牽涉協頻分析這觀念。在1955年由McDonald及Womersley的研究,發現動脈系統是一個穩定狀況的共振,大部分的循環符合線性原則,只有小部分屬於非線性,尤其是高頻部分。阻抗可由血流與血壓的比值得知,經由富力葉分析(Fournier analysis)得知不同波頻時阻抗是不同的,也就是說各個血管叢在不同頻率時其阻抗是不同的。而與McDonald同一實驗室的Taylor發現此一阻抗的特性可以用來解釋各血管叢的特質,且由此血管叢下游的記錄位置所得波形可分析壓力波經過此一血管叢所造成的反射對波型的改變。由於動脈內波型的研究有了新的進展,對於造成波型改變的反射處,其形成的原因及其所代表的意義,尤其是位於末稍血管上的反射處是值得研究的。
血管內阻抗產生的位置及方式並不相同,動脈波的變形提供了一個適當的切入點,血管內的反射造成波型的改變是主要原因(Li JK, 1981)。反射的成因由早期所認為的血管分支處,漸漸的知道是大動脈分支處之後的周邊血管,而不同血管叢的特性對波型的改變方式亦不同,1992年Young提出血管叢隨著其特性而有不同的波頻過濾方式,如腎及脾臟有堅硬的外膜及不長的動脈,與大動脈有著較佳的共振效果,而如胃及腸繫膜則有著較長的動脈,其作用則較近似單純的反射處。對於腎臟的研究(Yu GL, 1994)發現腎臟的共振主要在第二及第三頻譜,阻抗在第二頻譜最低,但在第三頻譜接近最高,而得到一個腎臟有一主要的協頻在第二頻譜的結論。
由於以上的研究皆為使用動脈內導管來得到壓力波的紀錄,而又已知主要的阻抗位置在小動脈處,使用強力超音波對腎臟皮質的小動脈來得到波型並不難,如要探查此處血管的波型使用超音波是一可行的方法,並以此來進行移植腎的評估並與正常腎臟的比較。
2.研究材料及方法
研究的對象以腎移植病人及門診或住院的非移植病人,進行超音波對腎的研究。從2000年3月至2003年5月,由同一醫生執行檢查。
其中腎移植病人共108位,非移植病人117位。腎移植組的資料數共273組,非移植病人組共164組。移植病人來源為本院移植門診病人及剛移植完住院病人,及排斥需住院時的追蹤及診斷。非移植病人則包括門診病人及住院病人,腎衰竭、腫瘤、腎水腫為排除因素(exclusion factor)。兩邊腎臟的資料皆盡量收集,雖然有時兩邊的腎臟無法收集完全,如病人無法配合閉氣等。
這是一個使用強力超音波(power Doppler)優異的灌流偵測能力,將腎臟皮髓質灌流的變化轉換成數字,來驗證其生理上的意義,以擴展新的適應性。
所有檢查使用同一台機器及同一位研究者,超音波使用”ATL”的HDI 5000型,探頭規格為2-5 MHz頻率,弧線排列(curved array),換算成波長為0.77至0.31 mm。機器設定條件為內建的”內臟”下的”腎臟”,條件為pulse repetition frequencies(PRFs) 設定在 1000Hz ,gain則設在對腎臟檢查時有效率的 (CPA 79%, MAP1, WF med, 及 Flow opt V). 隨腎臟深度不同,每秒約17-27個 畫面(frames)回傳,但在移植腎的情況下常會到達每秒25到31個畫面。每個病人約需70張左右的畫面,這些畫面會傳回電腦儲存起來,再進行運算。使用強力超音波來進行灌流的研究尚有一些優勢,如Jonathan在1995年的報告,對強力超音波進行灌流的偵測的準確性認為與事實相當接近,且能連續性的偵測(Rubin JM, 1995),對深度所造成的影響也較有限。
病人不需特別準備,姿勢以平躺為主,先做2-D影像,測量腎臟大小、異常部分,如結石、腫瘤、水腫等。接著使用都卜勒測量頻譜(spetrum)並測量阻力係數、脈搏係數(PI)。RI則接取三個部分,一是髓質與弧形動脈(segmental artery)交界處的血管,代表整個皮、髓質的灌流動脈(feeding artery),另外測其下游較周邊的血管,如葉間動脈(interlobar artery)及小葉間動脈( interlobular artery),代表皮質處的周邊血管,因此處血管較接近小動脈(arteriole),而小動脈則為絕大部分血管的阻力產生之處,對強力超音波而言,偵測此處的血管並無困難。每一測量的RI值需由一段穩定的流速圖形來取得,最少保持五個穩定的心搏週期。由於RI或PI的值會有些起伏,同一個位置常會測得多組RI值,再取其平均值,稱為平均RI(mean RI)。使用平均RI是盡量減少操作誤差(detecting error)的最好辦法。
腎實質的灌流的取樣一般為找一處位於腎臟較近中央處,選擇一個血管叢(vascular tree),以較易在計算VI時可以完整的一同計算一個血管叢的VI值。一個血管叢包含了arcuatal artery及其下游的interlobar artery及 interlobular artery。計算單一的血管叢可以減少受旁枝血管叢的影響,使得到的圖形較單純。
圖形以BMP檔存檔,每組圖形檔可以計算出其VI值,所謂VI值的定義為在一個選出的範圍內,有顏色的部分佔選取的面積的百分比,隨著心臟收縮及舒張循環的變化,在圖形上的VI值將隨著時間而改變,以VI值為Y軸,而畫面的次序(frame number)為X軸,將可以得到一個規律的波動圖形,此圖形為腎實質灌流的變化,因靜脈及動脈無法由強力超音波分辨出來,但是靜脈在心搏的過程中其訊號改變不大,所以變化的部分是由動脈系統所貢獻。此一圖形所代表是在腎實質一個血管叢在脈搏週期的灌流時動脈部分的變化,以此來探討動脈的擴張性是一個可以考慮的生物模型。雖然動脈的擴張性受血管內壓力、血液黏稠杜、血管外間質的壓力、血管的適應性、僵硬程度的影響,是一個多因素共同作用的結果。
軟體使用”超音波vascular index(VI)影像軟體”,由台灣大學應力所邵耀華老師所提供,將一個檔案”BmpList”的MD DOS檔放入所要計算的圖形檔內,便可以在此影像軟體叫出此一同名檔,選取所要計算的範圍及threshold便會跑出一個sinusoid的圖形。同時會有一個DAT檔及M檔,此為計算富力葉轉換所需的檔案。
以圖形的形狀來討論並不是很好的定量工具,將圖形數字化較能使用於研究的目的,富力葉轉換是一個很好的選擇,此一轉換軟體由邵耀華老師所提供的軟體”matlab” (the MathWork inc. copyright 1998)
3.結果
在腎移植組:取腎功能穩定的、追蹤超過4個月者、圖形品質好的,以及每一個病人只挑選一組資料來加以比較,以避免某些人測量多次所造成的誤差。共有62組資料可供比較,並挑選與血管擴張性及強力超音波的功能有關的因素來驗證相關性(correction),以hct, cre, bw, age, 以及DM作為independent variable,h21為dependent variable來測試其相關性,結果age對於h21有弱的相關性(p=0.056),而BW與Cre在統計上有意義的相關性(p=0.005)。其中的age指的是受腎者的年紀。至於使用ANOVA來進一步驗證因子間與h21的關係。由統計結果可知最少有兩個因子對h21有不同的影響。(F=3.165,p=0.018)。接著進行回歸分析,探討各個因子間與h21的關係係數,其中年紀(b=-.005, p=0.001)及體重(b=-.0008, p=0.001)有統計上的意義,但是因體重無法找到生理上的相關意義,如將其當成confounding factor,去掉後的年紀(b=-0.54,p=0.001)。其他因子對h21的影響並不明顯,皆未達統計上有意義的水準。
如果年紀對h21的影響是有意義的,則同一病人如有兩次以上的測量,將有時間先後次序的h21相減。來測試其是否有時間次序性,結果有29組資料,其中14組前面的h21較大,而15組則較後的h21較大,以此方法並無法證實此一趨勢。
1. 由統計資料可知,對於波型的影響較明顯的因素為受腎者的年紀。
2. 但對於有前後測的組,並無法得到h21的變化與受腎者的年紀的變化有相關。這可以用一些因素來解釋:
a. 因前後測的組數太少,相對於全部的118組不同病人而言,29組無法代表全部。
b. 另外可能有一個甚至多個混淆(confounding)因素存在,且並沒在本實驗列入的因子內。
在非移植組:選出108組腎臟,不為同一人,計算相關性,變數為sex、age、cre、bw、RI1、RI2等與血管阻力可能有關係的項目。在p=0.05統計有意義的前提下,RI1與RI2的p值為0.019與0.02,皆達到統計上有意義的相關。其中RI1與RI2分別表示arcuatal artery及interlobarartery的RI值。
4.討論及展望:
超音波使用在移植腎的追蹤治療已有一定的角色。彩色都卜勒超音波的引進(1985)使的超音波的功能除了能看灰階影像之外,對於血流的變化有了一個實用的工具。頻譜的加入使的血流速能被偵測,並可測量RI及PI。彩色超音波使用已久,但有其缺點不易克服,如易受假像(aliasing)影響,在血流量高的地方因各個方向的血流都有,常為不同方向向量的抵銷,反而測出來的總和變小,而看到的血流量便不準了。強力超音波因使用內建的程式算出所有能量的整合,而此能量成正比於能量頻譜的區域(area under the Doppler power spectrum)。由於一些移植腎臟的病變與微血管或小血管有關,對此區域的血液動態的變化如能早期偵測,對移植腎的術後追蹤治療是非常重要的。雖然強力超音波有優異的皮質灌流偵測能力,但是如試著使用皮質灌流程度來預測腎臟內的變化,對臨床上的實際效果幫助不大((Hilborn, 1997; Karl Turetschek, 1996; Peter FH, 1999))。
如何來將此功能充分利用,一個新的設計及對腎皮質的血行動力的進一步認識是需要的。本研究的設計方向便是利用強力超音波收集一段腎實質處的血液灌流,將其細分成多段後(每秒用多少個影像儲存與超音波探頭的特質及腎臟的深度有關),存進電腦後經計算每個影像的VI值再合成波型(協波,harmonic wave),此時此波已被轉換成數字訊號,再經矩陣運算便可得到此波的特徵,以協頻常數(harmonic number)來表示。
經此運算後,得到的是一個區域的腎實質處的血液灌流的變動,與血流的變動應是較類似的,其變動受到阻抗頻譜(impedance spectrum)及壓力波的影響。但以其血液動力來說,受到腎實質處動脈的擴張性、腎實質的適應性、血壓、 血液黏稠性有關,而如末稍小血管的阻力改變,增加的反射應也會改變此處的壓力波及灌流。
在腎移植病人得的資料經分析歸納出一個趨勢,即年紀、體重與h21(h2比上h1的比值)有相關,甚至在回歸分析時此兩者對h21的關係皆達到統計上有意義的程度。至於HCT、Cre、DM對h21並無統計上有意義的影響。由於h2與h1為腎臟主要的協頻,而越高階的協頻常數又為非線性的部分,h21越低表示有較多的血流符合線性的流體力學,雖然大部分的血流本都以符合線性的流體力學來流動。一般年紀越大時,因血管硬化,使的血管的擴張性變差,除了血流變快使RI值變高之外,彈性變差使的較高階的成分減少,h21變小可能是因h2的下降比h1大,這需進一步驗證。
體重對移植腎的預後其實是有的,由傳統上的經驗知由小孩來源的腎臟(Alexander JW, 1991)或女生的腎臟捐給男生(Odland MD, 1993),其預後較差。體重較重的換腎者,其體重對腎的影響是負面的(Gill IS, 1993)當捐腎與受腎者的體型相差明顯,而受腎者的體重較大時,其預後較差(Filippo quarto di Palo, 1997)。當比較由體重較輕捐給體重較重者,或較重捐給較輕者,在前者,當換腎時間較久時,腎血流減少(p=0.03),而隨著換腎者年紀增加,腎阻力增加(p=0.01)(Filippo quarto di Palo, 1997)。
在腎移植者的體重與h21的關係我們的結果(回歸係數為-0.0008,p=0.001), 達到統計上的意義。但體重的增加與年紀可能有關,畢竟體重對周邊血流的影響所知尚不足。
在瞭解年紀及體重的影響之後,對移植腎的照顧上會增加一些新的觀念,如對體重的控制應該更積極,而在不違反醫學倫理的情況之下,盡量不要讓捐腎受腎者的體重比例相差太大的移植發生。

For the benefit of free from invasiveness and irradiation exposure, many efforts tried to evaluate kidney with ultrasound. With built integral functions as 2-D gray scale image, we can measure renal size, that is not sensitive to renal function; furthermore the change in renal size is a late indicator of poor renal function. Using duplex Doppler to check resistance index (RI) and pulsatile index (PI) is another available built function of Doppler ultrasound. In evaluation of renal transplant, the RI value is mandatory. From a physical aspect, however, RI is not well-understood despites it is so popular applied. The usefulness of the ultrasonographic measurement of resistive index is not yet fully recognized. The current consensus of RI is its stand for vascular resistance. Moreover, the range of RI value varied widely, without definite cutoff point. So, mean RI is a more convincing data to be analyzed.
With introduction of color duplex sonography that has been available in 1986 and power Doppler image later in 1993, we have more realistic tools to evaluate renal cortex perfusion. Color duplex sonography, also referred to as color flow mapping, or technically not quite correct color Doppler, has become an essential modality in medical diagnosis imaging. Most color Doppler technique as based on the estimation of the mean Doppler frequency shift. Some efforts tried to improve perfusion detection by color duplex Doppler and detect renal perfusion by contrast-enhanced harmonics ultrasound images. Although color Doppler ultrasound with harmonics function seems to have a good correlation with renal cortex perfusion, the preparation and injection of contrast medium diminishes the characteristics of ultrasound--non-invasive and easily available.
The power Doppler technique, also called color Doppler energy image, bases on estimating the integrated Doppler power spectrum. The power Doppler image, however, is superior to color Doppler index in the demonstration of the normal intrarenal vasculature. We can even see the cortical brush resulting from visualization of small vessels at their branches distal to the arcuate arteries. Studies graded the perfusion of the renal cortex by power Doppler, no matter 6 or 3 grades, among adult or children, there were no correlation with renal function. No matter the superiority of renal cortex perfusion detection ability, Hilborn made a conclusion that objective analysis of the power Doppler sonographic appearance of renal transplants does not appear to aid in their evaluations(Michel C, 1999) .
The studies about vascular impedance aid another way to evaluate the kidney. Impedance is calculated by the ratio between pressure and flow at difference frequencies. Prior to 1955 there were only sporadic attempts to analyze the arterial pulse in the frequency domain. The conventional study, conducted by Hamilton, Remington, and their colleagues, was to analyze fluctuation in wave contour in time domain, not to involve in frequencies. In 1955, the physiologist McDonald and the mathematician Womersley first published the relationship between pulsatile pressure and flow in a vascular segment. This was based completely on the concepts that the arterial system being in a steady state of oscillation and pressure-flow relationship were obtained through Fourier analysis of recorded pulses. The non-linearitics in pressure-flow relationship were insufficiently small to be neglected at a first approximation. Taylor, working with McDonald in the same laboratory, showed that impedance patterns could be used to characterize the properties of the vascular bed downstream from a recording site, especially with regard to pulse-wave reflection.
At the difference properties and position of vascular trees, the impedance works quite different from others. Analysis of vascular contour fluctuation was feasible because the reflection of vascular bed was the most important contribution to fluctuation in wave contour. Early study considered the reflection arose from branching area of arteries. Later we knew that the main reflection sites were arterial-arteriolar junction. The different properties of vascular bed that work different as filter was studied by Young in 1992. Each arterial bed selects specific frequency on which to propagate and reflect. The beds are attached to the aorta at different sections and with different length of arteries. These effects result in organic arterial beds having different frequency properties, as the frequency selectivity is heavily dependent on the positions and the physical properties of organs. The kidney and spleen are more rigidly encapsulated organs, and communicate with the aorta through shorter arteries. Such organic beds may couple strongly with the aorta and amplify the high-frequency components of pressure waves. The arteries of stomach and the intestine are much longer and more divergent. Such arterial beds simply work as reflective sites.
The importance of resonance in hemodynamics had been revealed by Wang in 1991 and the characteristics of different vascular beds were also studied in 1994. The impedance of a kidney system in rat revealed that second and third harmonics were resonant frequencies. At the second harmomic, the pressure wave and fluid flow run in a round trip through the branch of the kidney. Whereas it is difficult for the third harmonics flow to enter the kidney. The kidney vascular system exhibits a resonant frequency at the second harmonics of the heartbeat.
From above studies the data were obtained from artery line in rat’s tail artery or radial artery line in human. Since renal cortex area is the main site of arterial-arteriolar junction that can be detected non-invasively with power Doppler. We have a good position to detect renal cortex vascular beds waveform non-invasively with ultrasound and try to clarify its physiological property.
For all examination, ATL ultrasound machine (HDI 5000) and a model 2-5 MH probe are used to evaluate kidney. Pulse repetition frequencies (PRFs) set at 1000Hz with gain optimized (CPA 79%, MAP1, WF med, and Flow opt V). Images were recorded 17-27 frames per second according to depth of kidney and recorded by a digital image processing unit. These frames were transferred to computer one by one and in order. We pick up images including at least three heart circles and usually more than 50 frames at each set of data available.
Examination procedure: Patients did not need any special preparation and took a rest more than 15 minutes. All patients were instructed to take easy to prevent change his or her heart rate by emotion.
For native kidney evaluation, volunteers or patients would be put on supine or flank position according to most appropriate position for data collection. Patients with short of breath that disturb image collection would be quitted. Valsava Maneuver was avoided since this procedure would interfere with data collection. Each patient was asked to hold respiration in seconds to facilitate completing data collection.
The kidney was first examined in B-mode and judged for echogenicity, structural differentiation or abnormality, renal size and cortex thickness. Patients with situation like hydronephrosis, tumor or calculi were excluded.
With the use of color and/or power Doppler, an area of cortex and medulla was evaluated and focused a region containing a complete vascular tree infused by an interlobar artery. The superficial cortex would be better for detection of perfusion since the deep renal cortex often showed less flow than the superficial cortex, presumably due to attenuation. This vascular tree includes an interlobar artery, interlobular artery and arcuatal artery. Brush in peripheral area of cortex in image of power Doppler was en bloc recorded.
Among these cases, some were recorded more than one cortex area to check the homogeneity. Usually three areas were selected including upper, middle and lower pole. In some cases a same area were recorded twice, one with color Doppler and then with power Doppler, because we intended to know whether there was difference between color and power Doppler in modulus calculated with Fournier analysis.
With pulse wave Doppler, maximal and minimum velocity were measured in the interlobular artery, downstream. Interlobular and arcuatal artery each wave selected had to fit the criteria that at least 5 stable continuous pulse with same waveform available. The RI for all the arteries was calculated using the formula: RI= (maximal systolic flow velocity subtracted end diastolic flow velocity, then divided by maximal systolic flow velocity). PI= (maximal systolic flow velocity subtracted end diastolic flow velocity, then divided by mean systolic flow velocity).
Mean RI was the mean of three independent RI values calculated from spectral Doppler waveform among a same artery. This effort tried to decrease the detecting error.
Fournier analysis: The collected 2-D Doppler images needed to transform to waveform for Fournier analysis, we had to transform those further. Firstly, we transformed this image into VI (vascularity index) (%) values. VI was identified as the percentage of colored pixel in a selected area that we preferred. Usually this area included a complete vascular tree in cortex and medulla, from medulla and collecting system junction to peripheral cortex. Renal capsule must be included because we do not want to neglect brush not seen by naked eyes. The ratio in each frame was recorded as VI (%) that plotted against frame number. This procedure was completed by computer and software was kindly supported by Professor 邵耀華。
This VI to frame pictures show a sinusoid picture. The waveform could be transformed digitally with Fourier transformation to moduli, named H1, H2, to Hn, for further analyses.
There were 117 cases in non-transplant group and 108 in transplant group. The male to female ratio was 56% and 77%. There were 164 and 273 effective data available in each group. In non-transplant group, the collected parameters included age, patient physical condition, kidney size, RI value (including arcuate, interlobar, interlobular RI), parenchyma perfusion with power Doppler, body weight, hemocrit, and serum creatinine. In transplant group, we collected the following parameters: age(donor and recipient), after transplantation follow-up time(coding in months), graft situation(coding in smooth, acute rejection, chronic allograft nephropathy, elevated Cre, and just after transplantation), proteinuria, prescribed medication(CNI, sirolimus, antihypertensive agents uses to treat hyperlipidemia and hyperuricemia), kidney size, RI value(including arcuate, interlobar, interlobular RI), parenchyma perfusion with power Doppler, body weight, hemocrit, and serum creatinine.
There were two significant results:
1. The transplant group: The age of recipient is a good predictive factor of H21(the ratio of H2 to H1). With current knowledge, the kidney has a resonance harmonics among H2 and H1. The ratio of H2 to H1 reveals the relative component of these two harmonics. Aging caused vascular stiffness increased, then influence vessel distensibility of aorta, large arteries and small peripheral vessels. The flow in a vessel propagates decreased under high frequency harmonic component, since high frequency harmonic reflected the elastic component of a vessel. H2 and H1 impedance might increase in aging process since there were drastic changes in the vasculature, then increase cardiac afterload. Both nonpulsatile and pulsatile component of arterial load increased chronologically too. The flow propagates into each organ also decreased. (Kelly R, 1989). However, no interpretation about separate component of impedance was found. From our study, the ratio H21 decreased with age means the high harmonic component, which stands for elastic part of a vessel, decreased more prominent than H1, which stands for rigid tube part.
Since a kidney transplant was implanted into a new hemodynamic situation (the recipient), this kidney had to couple with the new system. From series RI and renal systolic pressure evaluation, (Isiklar I, 2000) the transplant took several months to couple into this system. The transplant kidney would adapt the recipients’ systematic circulation and the physical age of this recipient.
2. The mean interlobar RI value has good correlation with patient’ age: With our best knowledge, the mean RI has good correlation with age (Mary TK, 1996). The mean RI is a mean of RIs measured from different part of this kidney or different parenchyma vessel. However, the intrarenal vessel RI value decreases in order from renal artery, interlobar artery to cortical artery(Filippo Quarto di P, 1996). The different RI valued measured from parenchyma vessel also decreases among peripheral vessel. The aim of study was to test whether different RI value correlated with age existed or not. However, the mean interlobar artery RI value had high statistical correlation with age (p=0.007). And arcuate RI value also has significant correlation with age (p=0.05).
With aging, characteristic changes were noted in all sites, including pulse amplitude increased with advancing age, diastolic decay steeped, and diastolic waves less prominent. The aging process hence causes the elevated systolic velocity and decreased velocity. According to the definition of RI value, RI value elevated is doomed. We just tried to clarify which parenchyma vessel can correlated well with age.
RI of interlobar artery has once been reported correlated well with perfusion pressure during acute urinary retention.(Michel C, 1999) With my best knowledge, interlobar artery probably has good correlation with change of vessel distensibility whereas interstitial fibrosis and vessel stiffness contribute a lot to vessel distensibility. Aging would cause change, such as vessel stiffness.(Michael EM, 2000)

目錄
3
一、 中文摘要 4-10
二、 緒論 11-21
三、 研究方法與材料 22-25
四、 結果 26-31
五、 討論 32-39
六、 展望 40-42
七、 論文英文簡述 43-48
八、 參考文獻 49-54
九、 圖表 55

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