| Abstract|| |
Objectives - Review of the angiographic data of 118 live kidney donors was done to assess the renal vessel anatomy, compare the findings with the per operative findings, to determine the sensitivity of Multislice CT angiography in the work up of live potential donors and finally to discuss and compare the results of the present study with the reported results using single slice CT, MR and conventional angiography.
Material and Methods : Retrospective analysis of the angiographic data of 118 of prospective live kidney donors was done. All donors underwent renal angiography on Multistice CT scan using 50 cc IV Contrast with 1.25 mm slice thickness followed by MIP and VRT post processing algorithms. The number of vessels, vessel bifurcation, vessel morphology and venous anatomy was analysed and the findings compared with the surgical findings.
Results - MSCTA showed clear delineation of the main renal arteries in all the donors with detailed vessel morphology. The study revealed 100% sensitivity in detection of accessory renal vessels which had a overall incidence of 26.67% with commonest distribution in the parahilar region.
Discussion- The present study showed 100% sensitivity in the visualization and detection of main and accessory renal vessels. These results were comparable with conventional angiography which has so far been considered the gold standard and were found superior to the use of SSCT, MR in the angiographic work up of liver renal donors. Due to improved detection of accessory vessels less than 2 mm in diameter a higher incidence of aberrant vessels was seen on the right side as has been suggested so far.
Keywords: Multislice CT - MRI, Renal Angiography
|How to cite this article:|
Kapoor A, Kapoor A, Mahajan G, Singh A. Multispiral CT angiography of renal arteries of live potential renal donors : A review of 118 cases. Indian J Radiol Imaging 2004;14:199-203
|How to cite this URL:|
Kapoor A, Kapoor A, Mahajan G, Singh A. Multispiral CT angiography of renal arteries of live potential renal donors : A review of 118 cases. Indian J Radiol Imaging [serial online] 2004 [cited 2020 Feb 28];14:199-203. Available from: http://www.ijri.org/text.asp?2004/14/2/199/28589
| Introduction|| |
Renal transplantation has grown rapidly over the years and so has been the evaluation of potential kidney donors. Graft retrieval from live donor requires accurate assessment of renal anatomy and its blood supply . Imaging forms an essential step in the prospective evaluation of a potential kidney donor. Conventional renal angiography (CA) has traditionally been used as an investigative tool in the final preoperative planning of the kidney donor . With the advances in imaging technology, safe and non-invasive methods of evaluation are now available using single slice spiral CT. Angiography (SSCTA), MR Angiography (MRA) and now multi-spiral CT Angiography (MSCTA). Many studies have been done over the last few years comparing CTA, MRA and CA with surgical findings and have shown good but varying results depending upon the techniques and the equipment used ,,. The aim of this study was to assess the sensitivity of MSCTA in the evaluation of prospective renal donors and to compare the findings with the intraoperative findings and also to discuss its role as compared to other available imaging modalities in the pre operative work up renal donors.
| Material and Methods|| |
Review of 118 prospective donor renal angiogram was done; which were performed on Multi-spiral CT (Somatom Volume Zoom, Forchheim Germany AG). Plain topogram of the abdomen was first taken, followed by the selection of the region of interest from the upper margin of D12 vertebra to the lower margin of L.3 vertebrae. The circulation time was determined using bolus tracking software (Siemens, Forchheim. Germany AG) with a scan delay of 15-20 cc depending upon the circulation time determined. This was followed by a IV injection of 50ml iopromide 300 mg/ml (Ultravist 300, Schering Germany AG) along with 20 ml saline with the use of a power injector (Medrad, USA) 1.25mm slices were acquired in a single breath hold using 3mm collimation, 120KV, 130 mAS, with table feed of 6mm and reconstruction interval of 0.6mm with a total scan length of 320 mm.
Post processing was done using various techniques like multiplanar reconstructions, freehand MIP, Virtual Rendering techniques (VRT) on a Siemens Virtuoso 3D workstation.
Retrospective analysis of the renal arteries of all the renal donors was done in double blinded way by Ak, Ap. Gm, Am. The following parameters were assessed. A) The visualization of the main renal arteries, their length (from the origin of the vessel to the renal hilum) and diameter along with the bifureation pattern for which each main renal artery was divided into three equal segments i.e. Proximal, mid and distal parts). B) The location of the accessory renal arteries on each side and their morphologic details. C), Renal vein assessment was also done for its number, size and location. Each of the observations made were looked for in the axial MIP, MPR and the VR mode to compare the findings. All the findings seen on imaging were then finally compared with the operative findings.
| Results|| |
The study retrospectively analysed the findings in 118 live renal donor of which 111 were males and 7 females in the age group of 20-50 years. MSCTA showed excellent visualization of the main renal arteries of all the potential donors with an average length of the main renal arteries of 6.82 and 7.34 cms on the right and left side respectively [Figure - 1]. The average diameter of the main renal artery was 1.09 and 1.10 cm on the right and left side respectively. The total incidence of accessory vessels was 26.67% of which single accessory renal arteries were seen in 28 (11.86%) on the left side and 34 (14.47%) donors on the right side [Figure - 2]a & b. Double accessory renal arteries were see in 2 (0.84%) and 6(2.1%) donors on the right and left side respectively [Figure - 3] while only 1 donor had triple accessory renal arteries on the left side [Chart 1]. The distribution of the accessory vessels was most commonly seen in the parahilar region followed by equal incidence in both the polar regions [Chart 2]. The main renal arteries were also assessed for vessel bifurcation. Early bifurcation was seen in 11 donors on the left side and 3 on the right side Figure 4]. The commonest pattern of the main renal artery bifurcation was late/distal seen in 93 and 76 donors on the right and left side respectively with mid vessel bifurcation seen in 25 and 33 patients on the right and left side respectively [Chart 3] Observations were also made on the perihilar branching pattern for surgical anatomic view point. Upto 3 perihilar branches were seen as the most common pattern in 61 and 69 donors on the right and left side with the second common pattern of 3-6 branches in 42 and 44 patients. No donor showed more than 6 perihilar branches of the main renal artery. The renal vein was visualized in all the patients with proximal renal vein bifurcation in 13 donors, retroaortic left renal vein in 5 and renal vein duplication in 1 potential renal donor [Figure - 5]. Comparison was also made for visualization of the above findings on axial as well as on VRT images which revealed good correlation in visualization of main renal arteries and there branches. However only 22 of the 71 accessory vessels especially those in the polar region were visualized on the axial images prospectively [Figure - 6]a,b,c.
| Discussion|| |
As CTA and MSCTA are done as an out patient procedure, they show a better donor compliance compared to CA, with excellent depiction of main renal arteries . The incidence of aberrant renal arteries in this study was 26.7% which is comparable to earlier reported incidence (25-30%) ,. However interestingly this study showed single accessory renal arteries to be more common on the right side 14.4% as compared to 11.8% on the left side which is contrary to the earlier reported studies showing higher incidence of accessory vessels on the left side . This variation could be explained due to better detection rate of small accessory vessels on MSCTA. On CTA and MRA accessory vessels less than 2mm diameter were difficult to recognize while in this study MSCTA showed 13 accessory vessels with diameters of 1-2mm; this could account for the variation in the result of the percentage of accessory vessels of the right and left side in the present study. This however requires confirmation with more studies using this modality. Many different techniques have been used earlier to study donor kidney vessels namely- Single slice CT angiography, Conventional catheter angiography and MR angiography. Determination of the detailed anatomy of the accessory renal vessels forms a important factor in the selection of the donor kidney. The sensitivity of accessory vessel detection rate in this study is 100% which strongly suggests the use of MSCTA as useful tool to evaluate the renal vessels in kidney donors. It is therefore worthwhile here to compare the results of MSCTA with the other available diagnostic modalities in use for doing a vascular workup of a potential renal donors.
Comparison of the results of this study with various studies reported in literature was done; the use of single slice CTA show a variable number of false negatives with 8-23% of the accessory renal arteries being not visualized by the single slice CTA , and these commonly involved arteries with diameter less than 2mm . CA so far considered to be the gold standard also shows a varying sensitivity for accessory vessel detection between 91-100% ,,. MRA using IV Gadolinium on 1.5 Tesla also gives promising results for aberrant vessel detection with studies reporting a sensitivity of 80 - 100% ,. Another important finding in the evaluation of donor renal vessels is the detection of early bifurcation of main renal artery and plays an important part in the preoperative evaluation of the donor renal vessels and its visualization can change the surgical technique for reimplantation in the recipient kidney. This study showed 100% accuracy in the detection of early vessel bifurcations with the use of Volume rendered post processing.
The results for detection of early vessel bifurcation were also superior with the use of MSCTA as is seen in this study than the reported result with the use of CTA and CA which have a accuracy of 93% and 91% respectively . The mid and distal vessel bifurcation was also accurately determined on MSCTA, however the observation was regarded as surgically irrelevant. Accurate perihilar branching pattern was also seen in all the patients in this study and matches the results of CA  however on CTA and MRA the reported sensitivity of detection of the number of perihilar branches is 70-90% and 50-80% respectively . With the use of MSCTA renal venous duplication anomalies and retroaortic renal veins can also be accurately detected which is a major advantage over DSA and MRA .
Another significant advantage seen in the present study by the use of MSCT was the reduced dose of intravenous contrast which was less than half of what is used in single slice CT. Protocols are also being recommended which shall obviate the need of intravenous pyelography by combining plain skiagrams of the abdomen and MSCTA thus avoiding reinjection and reducing the cost.
To conclude MSCTA is a highly accurate investigation not only for detection of supernumerary vessels but also gives accurate morphological details of the main and the aberrant vessels. The use of multiplanar reconstructions and the free MIP and VR protocols improves the detection of supernumerary vessels than being studied in the axial plane only. Review of the literature showing the results of MSCTA in the present study show the latter to be definitely superior to the above modalities in the renal vessel evaluation of the prospective donors and can replace CA as the gold standard .
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9]