| [Objective]1 To investigate the CT anatomical features of adult living kidneys and to provide morphological basis for clinic and teaching by measuring normal renal location and its diameters and blood vesseles.2 To evaluate the value of multislice spiral CT in preoperative living renal donors by analyzing the CT findings of living renal donors.3 To investigate the value of MSCT angiography in living kidney donors at five different reconstructive slice thickness and reconstruction increment by comparing the image quality and visibility of branch order of renal artery and accessory renal artery.[Materials and Methods]1. Subjects157 patients (314 kidneys) without renal disease from November,2007 to December,2009 were underwent abdominal CT examination,including 55 cases living kidney donors, Among them,101 cases were males and 56 females, aging from 22 to 77 years old with average age 44.18±15.00 years old, renal function of all patients were normal.2. Equipment and scanning methodThe MSCT examinations were performed on a 16-channel multi-detector row CT unit (Emotion; Siemens) with the following parameters:120 kVp,90mAs,0.6mm slice width,0.5-sec rotation speed, detector collimation of 16×0.6 mm. All image data were reconstructed using the body soft-tissue algorithm. Unenhanced andⅣcontrast-enhanced multiphasic scans (arterial, nephrographic, and excretory phases) were acquired. After unenhanced CT scans, nonionicⅣiohexol (300 mg iodine/mL) was injected into an antecubital vein through an 18-gauge peripheralⅣline using a power injector(Mallinckrodt)at a rate of 3.0-4.5 mL/sec, the dose amounts were 1.5ml/kg. For non-donor kidney transplant patients, the arterial phase scans was initiated approximately 23 seconds after bolus injection. For the nephrographic phase, scanning began 80 seconds after bolus injection with the same scanning parameters. For donor kidney transplant patients, the arterial phase scans were initiated using an automatic Smart Prep program. A region of interest was placed in the abdominal aorta just above the kidneys. Scanning was triggered 3 sec after a threshold of 120 Hu in the region of interest was reached. Nephrographic phase images were then acquired 55 sec after the arterial phase covering the same area described with similar parameters. Excretory phase images were acquired 5 min after the nephrographic phase and extended from above the kidneys to the bladder.3. Data processing and analysisFor the arterial phase, the images were reconstructed at 0.75-mm thickness with a 0.4mm interval using a standard body filter without edge enhancement. For the nephrographic phase, the images were reconstructed at 1.5 mm thickness with a 1.0 mm interval, and the images of the excretory phase were reconstructed at 2.0mm thickness with a 1.2mm interval. The cases involued in difference analysis of the quality of the renal artery and accessory renal artery images in different reconstruction slice thickness and increment were reconstructed at 5 kinds of different ways, including at 0.75mm slice thickness with a 0.4mm interval(0.75×0.4mm group),1.0mm slice thickness with a 0.6mm interval(1.0×0.6mm group),1.5mm slice thickness with a 1.0mm interval(1.5×1.0mm group),2.0mm slice thickness with a 1.2mm interva(2.0×1.2mm group),3.0mm slice thickness with a 2.0mm interva(3.0×2.0mm group). For each CT examination, the reviewers used axial images, supplemented by 2D and 3D postprocessing techniques including multiplanar reformations(MPR), maximum intensity projections(MIP), curved plannar reformation(CPR), CT virtual endoscopy(CTVE), and volume rendering(VR) according to individual preferences.The conture, position of normal kidney and renal artery were investigated, The long diameter, wide diameter, thickness and inside diameter of bilateral renal artery were measured. For donor kidney transplant patients, the malformation of renal artery, renal vein and urinary system was interviewed. For the study of MSCT angiography at different reconstructive slice thickness and reconstruction increment, the numbers and imaging quality of renal artery and accessory renal artery were compared. The quality of the reconstruction images was recorded using a 5-point scale (0=no display,1= unacceptable,2= suboptimal,3= diagnostically acceptable,4= good, and 5= excellent quality).4,Statistics analysisSPSS 13.0 software package was applied to statistical analysis. All data were recorded as(mean±standard deviation). The statistically significant difference was set at P<0.05.Paired-Samples T Test was applied to compare the dates such as bilateral kidney long diameter, wide diameter, thickness and bilateral renal artery inside diameter, et al. Independent-Samples T Test was applied to compare the gender differences, if equal variances not assumed, then Mann-Whitney U Test was applied. R×C chi-square Test and K-W Test were applied to compare differences of various reconstruction methods.[Results]1. The application of multislice spiral CT in adult living kidneys(1) The size of the kidney:The long diameter, wide diameter and thickness of left kidney is 102.51±10.05mm,54.13±5.87mm, and 49.16±5.12mm respectively; the long diameter, wide diameter and thickness of right kidney is 99.95±12.80mm, 50.50±4.68mm, and 46.51±5.24mm respectively. The long diameter, wide diameter, and thickness of left kidney are lager than those of right kidney, with statistical significant differences (P<0.05). Female patients were found to have smaller bilateral long diameter, wide diameter, and thickness than males, with significant differences(P<0.01).(2) Position of the kidney:Among the 157 cases, the position of left kidney is higher than right kidney in 135 cases(85.9%), with average 14.01±10.42mm higher than right. Only 22 cases (14.1%) those position of right kidney is higher than left kidney. There is no statistical significant differences between male and female patients. The upper pole of right kidney is located between upper 1/3 of T12 and lower 1/3 of L1 in 90.4% cases. The upper pole of left kidney is located between lower 1/3 of T11 and upper1/3 of L1 in 84.7% cases. The lower pole of right kidney is located between lower 1/3 of L2 and upper 1/3 of L4 in 84.7% cases. The lower pole of left kidney is located between lower 1/3 of L2 and upper1/3 of L4 in 86.6% cases.(3) The diameter, location and originated level of ranal artery:the left renal artery inside diameter is lager than that of right renal artery(mean left renal inside diameter 5.39 mm, mean right renal diameter 5.24mm)(P=0.001). Female patients were found to have smaller bilateral renal artery inside diameter (P<0.01). The majority (84.4%of right and 85.1% of left) of renal arteries originated between the middle 1/3 of L1 and middle 1/3 of L2.,In 119 cases(80.4%), the originated position of the right renal artery is.6.21±6.27mm higher than the that of left renal artery, only in 29 cases the originated position of the left renal artery is higher than that of right renal artery2 The value of multislice spiral CT in preoperative living renal donorsMultiple renal arteries were seen in 33 (60%) cases, most of which were accessory renal arteries. A total of 45 accessory renal arteries were seen in 55 cases. Among them,22 accessory renal arteries were seen on the left and 23 on the right, single accessory renal artery was seen in 24 cases and bilateral accessory renal arteries were seen in 9 cases. Early branching of the main renal arterys was seen in 7 (12.7%) cases, with bilateral at both sides. multiple renal veins were seen in 7 cases. Circumaortic veins were seen in 2 cases, and retroaortic vein was seen in 1 case. The right inferior phrenic artery originating from right renal artery were seen in 2 cases. Late venous confluence were seen in 3 cases. Dilatation of left ovarian vein were showed in 2 cases. A small accessory renal artery was missed by two reviewers before operation, and it was identified by the surgeons. The other cases were the same as the surgical findings.3 The value of MSCT angiography in living kidney donors at five different reconstructive slice thickness and reconstruction incrementAll five groups could display all the renal artery trunk and the first renal artery branch order without statistical significant. There were not statistical significant in fivegroups (χ2=5.020, P=0.403) in displaying the second renal artery branch order. In displaying the third renal artery branch order, there were not statistical significant in the former three groups, but there were statistical significant difference among the 2.0 X 1.2mm group and the former three groups. All the five kinds of reconstructive methods in displaying the fourth renal artery branch order were poor. There were not statistical significant in five groups in displaying the accessory renal artery.The mean scores for the quality of the renal artery trunk among the five groups were 5,5,5,5,4. There were not statistical significant in former four groups, There were difference among the 3.0×2.0mm group and the former four groups. The mean scores for the quality of the first renal artery branch order among the five groups were 4.98,4.98,4.93,4.73,3.53. There were not statistical significant in former three groups, but there were difference among the 2.0 X 1.2mm group, the 3.0X2.0 mm group and the former three groups. The mean scores for the quality of the second renal artery branch among the five groups were 4.54,4.54,4.15,3.46,2.24. There were not statistical significant in former three groups.There were difference among the 2.0×1.2mm group, the 3.0×2.0mm group and zhe former three groups. The mean scores for the quality of the third renal artery branch among the five groups were 2.80,2.80,2.22,1.24,0.41. There were not statistical significant in former two groups, there were difference among the 1.5×1.0mm group, the 2.0×1.2.mm group, the 3.0 ×2.0 mm group and the former two groups. The mean scores for the quality of the fourth renal artery branch among the five groups were 0.27,0.22,0.07,0.00,0.00. The score of five groups were lower in displaying the fourth renal artery branch order. The mean scores for the quality of the accessory renal artery were 4.52,4.52,4.14,3.19,1.48. There were not statistical significant in former three groups, but there were difference among the 2.0×1.2.mm group, the 3.0×2.0 mm group and the former three groups.Conclusion1. MSCT can provide a "one-stop" evaluation of bilateral renal vascular, parenchymal and urothelial anomalies of living potential kidney donors. It is the first choise imaging method before the living kidney donor transplantation.2 The long diameter, wide diameter, and thickness of left kidney are lager than that of right kidney. Female patients were found to have smaller bilateral kidney long diameter, wide diameter, thickness and renal artery inside diameter than males.3 In 85.9% cases, the position of the left kidney is higher than the right kidney. The majority of upper pole of right kidney is located at the T12 and L1 levels, and the lower pole is at L3 and L4 level. The majority of upper pole of left kidney is locatd at T11 and L1 level, and the lower pole is located at L2 and L4 level.4 The inner diameter of left renal artery is larger than that of right renal artery, with statistical significant difference. Female patients were found to have smaller inner diameter of renal artery than males, with statistical significant difference. The majority of renal arteries originated at the L1 and L2 levels, position of the right renal artery is higher than the left renal artery.5 To displaying renal artery branch and accessory renal artery, our results showed that images performed with a slice thickness 1.0mm and 0.6mm interval produced similar image quality to those with a slice thickness 0.75mm, interval 0.4mm. It can be used as the conventional reconstruction method to displaying renal artery branch and accessory renal artery, Submillimeter slices were not recommended, as they did not add additional information to the visualization.
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