| Background and Objective: Renal transplantation is the most effective treatmentfor end-stage renal disease. Living donor renal transplantation has been developing rapidly and playing more and more important role in current field of renal transplantation, because conventional donor kidneys from corpses can no longer meet the growing demand of clinic. With the development of living renal transplantation, comprehensive imaging evaluation of kidney donor become crucial in selecting candidates for living kidney transplantation and for determining the surgical technique to procure the renal graft. Digital subtraction angiography (DSA) and intravenous pyelography (IVP) was ever considered as the golden standard in the preoperative evaluation of the living renal donor (LRD). With the continuous development of imaging technique, multi-slice spiral computed tomography (MSCT) has drawn people's attention in the field of renal transplantation for its characteristics of high time, high spatial and high density resolution. The original image and postprocessing image complement each other and they can display the vessels, parenchyma and collecting system of kidney. The domestic literatures about this subject are few.The purpose of this research was to study the applied value of MSCT in preoperative evaluation of living donor kidneys and provide a convenient examination means for clinic to choose appropriate dornor kidneys and make rational operative plan.Materials and methods: Between May 2008 and February 2009, a total of 48 living renal donors(31men and 17women; range of age, 22-67 years; mean age,44.83 years) were performed enhanced scan with GE 64-slice spiral CT and evaluated preoperatively as potential living donors for renal transplantation. All the living donors and recipients are families except for 1 LRD who were performed self-transplantation. Besides accepting the CT examination, All the LRDs were required to undergo the examination of color Doppler and nuclide scan in order to preclude the contraindication of operation. Among 48 LRDs, 47 cases were performed open operation to extirpate the donor kidneys (22 left kidneys, 25 right kidneys), and 1 case gave up donation because his renal blood vesseles fell short of the demand of transplantation.GE Lightspeed 64-VCT scanner was used to performed the examination for living renal donors. Scan range: from the top of T11 to anterior iliac spine in the phase of blood vessel, and from adrenal gland to pubic symphysis in the phase of excretion. Scan parameter: 120 KV, automatic tube current, screw-pitch 0.984:1, scan time 0.35s/r, and collimation 64×0.625mm. Scan means: All the LRDs were first performed plain scan, then were performed enhanced scan after being injected contrast medium (100ml, 350mgI/ml) with high pressure syringe. 48 LRDs were devided into 3 groups (I group 21, II group 15,IIIgroup 12) which were performed enhanced scan according to different scan means in the blood vessel phase. The scan of excretion phase were all completed during 300～600s after injecting contrast medium.The different scan principle which were kept to by the 3 group as follows: I group adopted manual touching off in the early artery phase. GE Smart Prep system were utilized to trace the contrast medium in the vein. II group adopted the scan method of settled time in the artery phase and vein phase. III group adopted the measure of scan with dual velocity of flow, which were completed in one phase.All the original data from scan were reconstructed with slice thickness of 0.625mm and then were transmited to ADW 4.3 workstation where the three-dimensional images of renal blood vessels, parenchyma and collection system were reconstructed with the technique of VR, MIP, CPR or MPR. Three diagnostic doctors appraised the quality of reconstruction images and evaluated the complexion of renal blood vessels, parenchyma and collection system. Renal blood vessels can be evaluated by analyzing VR,MIP,CPR and MPR reconstruction images, which included observing the amount, position, length, and shape of renal blood vessels, estimating whether there are plaque, calcification, stenosis, embolism, abnormal dilation or other diseases in renal blood vessels. Renal parenchyma can be evaluated by analyzing VR, MPR reconstruction images and original axis-orientation images, which including observing the size, shape, position relation between kidney and surrounding organize, the enhancement degree of renal parenchyma, and estimating indirectly the function of kidney. Renal pelvis, renal calices and ureter can be evaluated by analyzing VR, MIP reconstruction images in order to judge wether there are variation, hydrocele, stenosis, and so on. The images of renal vein were graded into three ranks in terms of the quality of images, and the case amount of every grade in three groups were counted separately.The results of preoperative evaluation by MSCT were contrasted with the record of postoperation, the results of ultrasound and nuclide scan which were performed before operation in order to appraise the accuracy of preoperative evaluation of Living Donor Kindneys by 64-VCTStatistical analysis was executed by SPSS 13.0 software packages. Computation data was analysed with analysis of variance (ANOVA), and the data of grade sample was analysed with nonparametric test. Significant level was set as a=0.05.Results: 1. Appraisement on the quality of images: (1) Analysis of variance showedthat the difference was statistically significant in CT density of renal artery and vein among three groups (F volume were 3.921,12.139; P <0.05) . CT volume average contrast of renal artery among three Groups: I group> II group>IIIgroup; CT volume average contrast of renal vein among three Groups: I group >IIIgroup> II group. Statistical Ananysis showed that the difference was statistically significant in CT volume of renal artery between I group and III group, no statistically significant difference was found between I group and II group, II group and III group. For CT volume of renal vein, the statistically significant difference was found between I group and II group, II group and IIIgroup.(2) Image quality contrast on renal vein: The images of renal vein were graded into three ranks in terms of the quality of images as above. The renal vein images which were considered as 1 and 2 grade cound meet the demand of diagnosis, but 3 grade cound not. The proportion of case amount whose renal vein image cound be used to diagnosis in three groups is 90.5% (19/21), 53.3%(8/15), 91.6%(11/12).Rank sum test showed that the difference in proportion of each grade among three groups was statistically significant(P <0.05), which means that the quality of renal vein images had distinction. Proportion of each grade contrast between erery two groups: the difference between I group and II group, II group and IIIgroup was statistically significant(P <0.05), no statistically significant difference was found betweenI group and IIIgroup. (3) The difference of CT volume between renal artery and vein in III group: The quality of images in IIIgroup was graded as nicer (CT volume difference >80HU), generic (40HU<CT volume difference<80HU),bad (CT volume difference<40HU).The case amount of each grade is 6,4,2.2. Evaluation of renal blood vessels:(1) renal artery: among 48 living donors, 28 cases were found bilateral single renal artery (frequence 58.3%; 20 cases were found unilat multiple renals (frequence 41.7%); 19 cases were found early branches of renal artery (frequence 39.6%), and among them, 3 cases were bilateral, 16 cases were Unilat (frequence 33.3%, left 10 cases, right 6 cases). 22 cases were found accessory renal artery (ARA)(frequence 45.8%,16 men and 6 wemen),among them, 6 cases were bilateral(frequence 12.5%), 16 cases were unilat(frequence 33.3%,left 9 cases and right 7 cases); The ARA amount of 22 cases added up to 32, of which 8 cases originated from abdominal aorta and 24 cases originated from trunk of renal artery; 29ARAs supplied blood to upper pole of kidney and 3 ARAs to inferior pole of kidney. 5 cases were found aortic suprarenal arterys which originated from right renal arterys. 11 cases were found diaphragmatic artery which originated from renal artery(frequence 22.9%), and among them,9 cases were unilat (left 1 case and right 8 cases). Among 48 living donors,5 cases was found disease in renal artery, of which 1 case was found tough plaque in the front branch of right renal artery, 2 case was found calcify in the initation point of left renal artery, 1 case was found stenosis in the initation point of bilateral renal artery, 1 case was found a small aneurysm in the right renal artery.(2) renal vein: Among 96 kidneys of 48 donors, 83 kidneys were found single vein (left 46 cases, right 37 cases); 35 donors were found unilat single renal vein (frequence 72.9%),13 donors were found bilateral multiple renal veins(frequence 27.1%, left 2 case and right 11 case).Among all the living donors,18 cases were found variation or abnormal branches in renal vein, of which 1 case was found left double renal veins which surrounded abdominal aorta, and 15 cases were found abnormal branches which including gonad veins, lunbar veins, hemiazygos veins and adrenal veins. 2 cases was found abnormality in left renal veins whose signs corresponded to nutcracker syndrome, but they had no symptom. (3) The display capability for ARA and renal vein is not identical among different reconstruction method. MIP images cound display more blood vessels than VR, and axial images was most accurate because they are the basic accordance of elaluation. In addition, MIP images were superior to VR images in displaying renal artery branches.3. Evaluation of renal parenchyma: Among 48 living donors,3 cases was found small renal cysts. The one whose hibateral renal arterys showed stenosis was found that right renal parenchyma represented delayed enhancement which indicated that renal function got impaired. 4 cases have congenital lobulated kidney. Other living donors were not found abnormal in their kidneys. With respect to the relationship between kidneys and ribs, VR images diaplayed clearly that 11 superior parts of the kidneys, 47 central regions and 38 inferior parts were covered by ribs among 96 kidneys.4. Evaluation of collecting system: Among all the donors, 3 cases were found abnormal in renal collection system. 1 case was found the malformation of double renal pelvis and ureters on the left.l case was found low-grade hydronephrosis with dilatation of ureter on the left.l case was found a small calculus in right kidney by plain scan images.5. Contrast with surgery: 4 cases were found difference between operational findings and preoperative evaluation. 1 case was found right double renal arterys one of which was ARA, but preoperative evaluation omitted the ARA. 3 cases was judged there was single renal vein on the right by MSCT examination but operational record showed that their right renal vein were both double. All the Other cases coincided.Conclusions: 1. Multi-slice spiral CT examination can reach the effect of manykinds of detection including DSA, ultrasound, IVP, so it is able to make a full range of comphensive preoperative evaluation for living donor kidneys and provide a noninvasive, convenient and effective method of examination for clinical. Therefore, MSCT have good practical value and application prospect.2. 64-slice spiral CT is a more convenient, efficient and accurate detection technique. In the applications of preoperative evaluation of living donor kidneys, 64-slice spiral CT which combines fast volume scan and powerful image post-processing function can display renal blood vessels, parenchyma, collecting system and surrounding tissue clearly, so as to provide important reference basis for clinic to select suitable donor kidneys and formulate reasonable and feasible surgery program.3. Dual-flow rate scanning method can achieve that one-phase scan complete examination of renal artery and vein, which greatly reduces X-ray volume received by living donors by shortening the time of examination, and can obtain ideal images, so it is worthy of promotion and application. |
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