|Year : 2004 | Volume
| Issue : 2 | Page : 134-137
Evaluation of renal donors with helical CT angiography - our experience
N Upendra Kumar1, PVLN Murty1, Nand Kumar1, Ram Reddy1, Ramamurthy2, Jyotsna2, KV Dakshina Murthy3
1 Department of Urology and Renal Transplantation, Nizam's Institute of Medical Sciences, Hyderabad, India
2 Department of Radiodiagnosis, Nizam's Institute of Medical Sciences, Hyderabad, India
3 Department of Nephrology, Nizam's Institute of Medical Sciences, Hyderabad, India
Department of Urology, Nizam's Institute of Medical Sciences, Punjagutta, Hyderabad - 500 082
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objectives: To compare the findings of helical computed tomography (CT) angiography and the intraoperative findings in voluntary kidney donors.
Methods: This was a prospective study evaluating 28 voluntary kidney donors from January 2001 to December 2002 who underwent a preoperative CT angiography with a 20 minute intravenous urogram film and was compared with intraoperative findings during nephrectomy to determine the accuracy of CT angiography. Donors constituted 21 females and 7 males and all were related donors with mean age of 35.5 years (19 to 55 years).
Results: Intraoperative findings correlated in 25 out of 28 patients (88.75%). Among those 3 patients, one patient had an upper polar accessory artery, another had a lower polar artery and the third patient had an early branching respectively.
Conclusions: Helical CT and 3-D reformatting allowed improved vascular imaging and has the potential for future single imaging method for donor evaluation. It has been cost effective also. It needs a dedicated radiologist for interpretation. About 10% of renal arteries are not seen on helical CT renal arteriograms when compared with findings at surgery.
Keywords: Helical CT angio, kidney donors, renal transplantation.
|How to cite this article:|
Upendra Kumar N, Murty P, Kumar N, Reddy R, Ramamurthy, Jyotsna, Dakshina Murthy K V. Evaluation of renal donors with helical CT angiography - our experience. Indian J Urol 2004;20:134-7
|How to cite this URL:|
Upendra Kumar N, Murty P, Kumar N, Reddy R, Ramamurthy, Jyotsna, Dakshina Murthy K V. Evaluation of renal donors with helical CT angiography - our experience. Indian J Urol [serial online] 2004 [cited 2020 May 28];20:134-7. Available from: http://www.indianjurol.com/text.asp?2004/20/2/134/21529
| Introduction|| |
Helical CT angiography is rapidly replacing conventional angiography and intravenous urography (IVU) as the imaging modality of choice for evaluating renal donors.  Helical CT, combined with low-osmolar intravenous contrast materials, has enabled safe, rapid and relatively noninvasive evaluation of potential donors. Sensitivity and specificity for identifying specific vessels has been reported to be 99% for main renal, 89% for polar arteries and 98% for main renal veins respectively.  It also provides comprehensive details of the location, size and length of the renal, adrenal, gonadal and lumbar veins that are useful for laparoscopic nephrectomy.  Accurate radiologic interpretation depends on the radiologist's experience level, attention to detail, and commitment to careful image evaluation. Live kidney donor evaluation mandates anatomical and functional assessment of the donor kidney. Helical CT with advanced 3-D techniques provides detailed description of the vascular, parenchymal and collecting system. 
The agreement between results of CT arteriography and findings at surgery is about 90% and that of conventional arteriography is about 87%. 
We present our experience at our institution with helical CT angiography in prospective renal donors and the intraoperative correlation as it is (1) minimally invasive, less morbid and highly informative when compared to conventional angiography, (2) provides not only anatomical but functional aspects so that IVU can be replaced, (3) cost-effective and (4) also detects minimal parenchymal lesions that are missed on IVU.
| Patients and Methods|| |
This was a prospective study evaluating 28 voluntary kidney donors between January 2001 to December 2002. A thorough history, clinical examination and laboratory assessment was performed to exclude candidates with renal dysfunction. Donors had documented histocompatibility with the recipients. Potential donors received an intravenous bolus of 90 ml (2 ml/kg) of non-ionic contrast at the rate of 2 ml per second through peripheral vein. During the arterial phase, 14 to 20 seconds after the start of the injection, helical scanning was begun above the kidney and continued to 3 cm below the aortic bifurcation using 2 mm collimation and a pitch of 1.5 to 1.8 depending on the required length of coverage. Continuous anatomic information was obtained from data acquired by Somatom Plus 4 sub-second helical CT scanner (Siemens AG, Erlanger, Germany), which couples a rotating tube and table feed. Images were obtained during a single breath hold (usually 30 seconds) using standard CTA protocol, thus eliminating respiratory artifacts.
Approximate patient examination time was 10 min and image reconstruction to generate MIP's and data analysis using Somatom console were completed in 20 min. A plain X-ray of the abdomen (KUB) was taken 20 min after injection of contrast to acquire an IVU like image. These findings were compared with intraoperative findings during nephrectomy to determine the accuracy of CT angiography. Donors constituted 21 females and 7 males and all were related donors. Their mean age was 35.5 years (range 19 to 55 years). Initial 10 patients underwent simultaneous conventional angiography also. Preoperative CT findings were compared to intraoperative findings and the accuracy of CT was determined.
| Results|| |
Twenty-eight renal donors were evaluated with preoperative CT angiography. Ten donors had bilateral single renal arteries [Figure - 1], 16 had unilateral double renal arteries (left 10, right 6) with 10 upper polar and 6 lower polar accessory renal arteries and 2 had triple vessels in the left side respectively. Ninety-eight per cent of the donors had a single renal vein. All the patients underwent nephrectomy on the side with preferably single or double renal arteries. Intraoperative findings correlated in 25 patients with an accuracy of 88.75%. Among those 3 patients, one patient had an upper polar accessory artery, another had a lower polar artery [Figure - 2] and the third patient had an early branching (<3 mm) respectively. The cost of CT angiography and 20-minute plain film - KUB was Rs.6000/- versus conventional angiogram with IVU of Rs. 10,000/- (40% reduction in the cost) at our center.
| Discussion|| |
Live kidney donor evaluation mandates anatomical and functional assessment of the donor kidney. Helical CT with advanced 3-D techniques provides detailed description of the vascular, parenchymal and collecting system. In our study, CT angiography missed 3 vessels which were small (<3 mm) but were detected during nephrectomy; 2 accessories and I early branching missed due to interpretation by the radiologist. A comparison of our results with other similar studies is presented in the Table. Kaynan et all divided the donors undergoing CT angiogram into early and late groups because there was a learning curve with spiral CT. In the early group 2 accessory arteries were missed by spiral CT. No arteries found at surgery were missed in the late group (negative predictive value 100%). Hence, there is a profound learning curve for performance and interpretation. Lionel et al  assessed the number of renal arteries, presence or absence of renal artery stenoses and associated parenchymal abnormalities by spiral CT. A total of 39 renal arteries were detected. Conventional transverse scans viewed in a cine loop format detected all vessels, while the maximum intensity projection and shaded surface display demonstrated only 37.
Patil et al  in their study concluded that identification of vascular anomalies was best on direct viewing of the axial images using interactive scrolling through the images and cine-loop paging. They compared the accuracy of CT angiography with intraoperative findings in the evaluation of 102 live kidney donors. In 204 kidneys evaluated, CT angiography missed a small renal vein, an accessory artery that was visualized in retrospect, and a very early branch that was read as accessory artery.
Kaynan et al  evaluated 47 living renal donor candidates with spiral CT, all but 2 underwent donor nephrectomy. Two accessory arteries were missed in the early group donors. Overall accuracy to predict early renal artery division relative to surgical findings was 93% for spiral CT. Rankin et al  evaluated 80 donors, of which 50 patients underwent CT angiography and 30 underwent MR angiography before donor nephrectomy. Imaging findings were compared with the surgical results in 54 patients. CT angiography and MR angiography were 100% sensitive in identifying the main renal arteries and renal veins. Hence, both methods may miss small accessory renal arteries. Pozniak et al performed CT angiography in 205 potential renal donors. Correlation with surgical findings in 136 donor nephrectomies helped confirm a high level of accuracy for CT angiography in the assessment of the renal vasculature. Sensitivity and specificity for identifying specific vessels were 99.6% and 99.6% for main renal arteries, 76.9% and 89.9% for polar arteries, and 98.7% and 95.5% for main renal veins, respectively. Cochran et al in their prospective study intended to determine if helical CT arteriography plus conventional radiography is sufficiently accurate to replace and less costly than excretory urography and conventional renal arteriography. Of 57 patients who underwent CT arteriography, 46 also underwent conventional arteriography and 40 underwent surgery. For those 46 patients, agreement between results of CT arteriography and conventional arteriography correlated in 89% of kidneys. Slakey et al  evaluated 19 donors solely by CT angiography preoperatively. Five donors (26%) had supernumerary renal arteries. Fourteen donors had single, 4 donors had 2 and 1 donor had 3 renal arteries. Helical CT demonstrated small polar vessels in several donors. Two donors (10%) had supernumerary renal veins. Accuracy of vascular anatomy defined on CT was 90% when confirmed at operation which missed a 0.8 cm lesion near the renal hilum. Patient acceptance was excellent.
CT angiography is comparable to conventional angiography and MRI in detecting multiple renal arteries, early branching, venous anomalies and incidental parenchymal disorders. 
| Conclusions|| |
3-D reformatting and cine loop formatting allows improved vascular imaging. However, it needs a dedicated and experienced radiologist for proper interpretation to plan preoperatively and avoiding potential risks of damaging accessory vessels. It is possible to image kidneys and its vessels in a single breath hold. It is noninvasive and less expensive with less discomfort, morbidity and radiation exposure than conventional angiogram and IVU but is less accurate in identifying pre-hilar branching and accessory renal arteries.
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[Figure - 1], [Figure - 2]
[Table - 1]