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RESEARCH ARTICLE
Year : 2004  |  Volume : 20  |  Issue : 2  |  Page : 134-137
 

Evaluation of renal donors with helical CT angiography - our experience


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

Correspondence Address:
PVLN Murty
Department of Urology, Nizam's Institute of Medical Sciences, Punjagutta, Hyderabad - 500 082
India
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Source of Support: None, Conflict of Interest: None


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   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 2019 Aug 22];20:134-7. Available from: http://www.indianjurol.com/text.asp?2004/20/2/134/21529



   Introduction Top


Helical CT angiography is rapidly replacing conven­tional angiography and intravenous urography (IVU) as the imaging modality of choice for evaluating renal do­nors. [1] 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. [2] 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. [3] 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. [4]

The agreement between results of CT arteriography and findings at surgery is about 90% and that of conventional arteriography is about 87%. [5]

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 Top


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 Top


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 Top


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 [7] 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 [4] 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 [6] 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 [8] 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 [9] 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. [10]


   Conclusions Top


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.

 
   References Top

1.Pozniak MA, Lee FT Jr. Computed tomographic angiography in the preoperative evaluation of potential renal transplants donors. Curr Opin Urol 1999; 9(2): 165-70.  Back to cited text no. 1    
2.Pozniak MA. Balison DJ, Lee FT Jr, Tambeaux RH, Uehling DT, Moon TD. CT angiography of potential renal transplant donors. Radiographics 1998; 18(3): 565-87.  Back to cited text no. 2    
3.Smith PA, Ratner LE, Lynch FC, Corl FM, Fishman EK. Role of CT angiography in the preoperative evaluation for laparoscopic nephrectomy. Radiographics 1998; 18(3): 589-601.  Back to cited text no. 3    
4.Patil UD, Ragavan A, Nadaraj, Murthy K, Shankar R, Bastani B et al. Helical CT angiography in evaluation of live kidney donors. Nephrol Dial Transplant 2001; 16(9): 1900-4.  Back to cited text no. 4    
5.Cochran ST, Krasny RM, Danovitch GM, Rajfer J, Barbaric ZM, Wilkinson A et al. Helical CT angiography for examination of liv­ing renal donors. Am J Roentgenol 1997; 168: 1569-73.  Back to cited text no. 5    
6.Kanyan AM. Rozenblit AM, Figueroa KI, Hoffman SD. Cynamon J, Karwa GL et al. Use of spiral computerized tomography in leu of angiography for preoperative assessment of living renal donors. J Urol 1999; 161(6): 1769-75.  Back to cited text no. 6    
7.Lionel G, Sebben RA, Costello P, Rao MM. The use of spiral com­puted tomographic angiography for the assessment of living kid­ney donors. Aust NZ J Surg 1999; 69(3): 217-9.  Back to cited text no. 7    
8.Rankin SC, Jan W, Koffman CG. Noninvasive imaging of living related kidney donors: evaluation with CT angiography and gado­linium-enhanced MR angiography. Am J Roentgenol 2001; 1777(2): 349-55.  Back to cited text no. 8    
9.Slakey DP, Florman S, Lovretich J, Zarifian AA, Cheng SS. Utility of CT angiography for evaluation of living kidney donors. Clin Transplant 1999; 13(1 Pt 2): 104-7.  Back to cited text no. 9    
10.Halpern EJ, Nazarian LN, Wechsler RJ, Mitchell DG, Outwater EK, Levin DC et al. US, CT and MR evaluation of accessory renal arteries and proximal renal arterial branches. Acad Radiol 1999: 6(5): 299-304.  Back to cited text no. 10    


    Figures

  [Figure - 1], [Figure - 2]
 
 
    Tables

  [Table - 1]



 

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    Abstract
    Introduction
    Patients and Methods
    Results
    Discussion
    Conclusions
    References
    Article Figures
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