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ORIGINAL ARTICLE
Year : 2002  |  Volume : 19  |  Issue : 1  |  Page : 50-53
 

Comparison of spiral CT angiography vs digital subtraction angiography in the evaluation of living kidney donors


Department of Urology and Radiodiagnosis, Christian Medical College and Hospital, Vellore, India

Correspondence Address:
Lionel Gnanaraj
Department of Urology, Christian Medical College and Hospital, Vellore - 632 004
India
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Source of Support: None, Conflict of Interest: None


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   Abstract 

Recent reports suggest that spiral computed tomographic (CT) angiography could replace conventional angiogra­phy and intravenous urography (IVU) for the assessment of potential live kidney donors. The purpose of this study was to assess the accuracy of spiral CT in kidney donor workup. 10 consecutive renal donors had IVU, percutane­ous transfemoral selective renal angiography and spiral CT angiography between January and March 2001. The spiral CT and renal angiograms were assessed independ­ently by two radiologists. The number of renal arteries, pres­ence or absence of renal artery stenoses and associated parenchymal abnormalities were assessed. A total of 27 renal arteries were detected. Transverse scans viewed in a tine loop format with maximum intensity projection and shaded surface display detected all 27 vessels. All 27 ves­sels were detected by conventional catheter angiography. A simple renal cyst was noted in both spiral CT and con­ventional angiogram. Venous anatomy including a retroaortic renal vein was visualized in spiral CT angiogram but not visualized by conventional angiography. Spiral CT angiography performed as an outpatient procedure is less invasive, less expensive, and provides good images of the arterial and venous anatomy in addition to the visualiza­tion of the other abdominal viscera. A plain X-ray of the abdomen was taken 15 rains after injection of contrast to acquire an IVU like image. Spiral CT angiography has the potential to replace conventional catheter angiography and IVU in the assessment of renal donors.


Keywords: Spiral Computed Tomographic Angiogram; Live Kidney Donor; Digital Subtraction Angiogram


How to cite this article:
Kumar S, Tharakan M, Chacko N, Gnanaraj L. Comparison of spiral CT angiography vs digital subtraction angiography in the evaluation of living kidney donors. Indian J Urol 2002;19:50-3

How to cite this URL:
Kumar S, Tharakan M, Chacko N, Gnanaraj L. Comparison of spiral CT angiography vs digital subtraction angiography in the evaluation of living kidney donors. Indian J Urol [serial online] 2002 [cited 2018 Nov 18];19:50-3. Available from: http://www.indianjurol.com/text.asp?2002/19/1/50/20291



   Introduction Top


Live kidney donors undergo extensive preoperative evaluation, which includes medical history, laboratory test­ing and radiological imaging. Assessment of a potential live kidney donor requires intravenous urography (IVU) in order to determine the renal size, function of both the kidneys, evaluation of the calyces, pelvis and ureteric anatomy, as well as to detect renal or ureteral calculi. [1] Po­tential donors with normal IVU undergo renal angiogra­phy for anatomic definition of the renal arteries and the detection of accessory renal arteries. Recently, spiral com­puted tomographic (CT) angiography has been used to delineate the renal vascular and collecting systems. [2] Spi­ral CT angiography has the potential to achieve the diag­nostic accuracy of conventional angiography without the risks of catheter angiography.[3] The purpose of this study was to assess the accuracy of spiral CT compared with catheter angiography for the assessment of potential renal donors.


   Material and Methods Top


A total of 10 kidney donors were evaluated between January to March 2001. A thorough history, clinical ex­amination and laboratory assessment was performed to exclude from donation candidates with renal dysfunction. Donors had documented histocompatibility with recipi­ents. Potential donors received an intravenous bolus of 100 ml (2 ml/kg) of contrast at the rate of 3 ml per second through a peripheral vein. During the arterial phase, 14 to 20 seconds after the start of injection, helical scanning was begun above the kidney and continued to 3 cm below the aortic bifurcation using 2 mm collimation and a pitch varying from 1.5 to 1.8 depending on the required length of coverage. Continuous anatomic information was ob­tained from the data acquired by the spiral CT, which cou­ples a continuously rotating tube and table feed. Images are obtained during a single breath hold (usually 30 sec­onds), thus eliminating respiratory artifacts. Approximate patient examination time is 5-10 mins and image recon­struction and data analysis are complete in 20 mins. Image analysis includes not only visualization of the axial images in a cine mode, but also interactive multiplanar reformatting with thin maximum intensity projection (thin MIP) and shaded surface display (SSD). Thin MIP and SSD displays provide angiographic-like images and can discriminate calcification from the contrast material. A plain X-ray of the abdomen was taken 15 mins after injec­tion of contrast to acquire an IVU like image.

Radiological investigations included IVU followed by conventional angiography and spiral CT angiography. All spiral CT angiograms were done and interpreted before digital subtraction angiography by a radiologist who had no knowledge of the conventional angiography results. Digital subtraction angiograms were done as day care pro­cedure with hospital admission whereas spiral CT angio­grams were done as an out patient procedure. All the potential donors underwent open donor nephrectomy.


   Results Top


All the patients were accepted for donor nephrectomy. 27 arteries were reported by spiral CT as well as by the conventional angiography (100% accuracy). Review of the axial images, thin MIP and SSD showed all the 27 arteries. Maximum intensity projection and SSD images should be always viewed in conjunction with axial im­ages to avoid missing small arteries. Multiple arteries were reported on spiral CT angiography and digital subtraction angiography in 5 donors (two patients had bilateral dou­ble vessels). Early prehilar branching of renal artery was seen in two renal units of the same patient by both spiral CT angiography and DSA. The arteries were assessed for the presence of calcification and stenosis. The details of the venous anatomy were clear in spiral CT angiograms. Details of the adrenal, gonadal and the lumbar vein join­ing the left renal vein is seen clearly by viewing reformatted images of the spiral CT at the workstation which is very useful to the surgeon planning a laparoscopic donor ne­phrectomy. Vascular images of the donor kidneys seen on both the conventional and spiral CT angiography were con­firmed for the side that underwent donor nephrectomy.

A simple renal cyst was noted on both spiral CT and conventional angiogram in one donor. There were no com­plications encountered with the conventional as well as the spiral CT angiograms in this series.


   Discussion Top


Anatomic imaging of potential living renal donors has been performed with IVU followed by conventional arte­riography. Preoperative conventional arteriography has four recognized objectives: (a) renal artery number, (b) renal artery length, (c) renal arterial aneurysmal and oc­clusive disease, and (d) unsuspected renal parenchymal abnormalities. [4] The purpose of this study was to assess the accuracy of spiral CT angiography compared with catheter angiography for the assessment of potential. renal donors.

5 of the potential donors had multiple arteries (50%) diagnosed both by the conventional and the spiral CT angiograms. 1 patient had bilateral early (prehilar) branch­ing of renal artery. The generation of three-dimensional renderings of the arterial tree has been an important factor in the acceptance of CT for the evaluation of potential living donors by transplant surgeons. [2] There were 7 ac­cessory polar arteries identified in the 20 renal units stud­ied. Attention has been given to detection of these small (less than 2 mm) accessory vessels to help surgeons avoid additional blood loss and possibly a focal renal infarct. However, some of these small vessels especially at the upper pole are sacrificed at surgery, as they are too small to transplant and do not affect patient outcome, since re­nal volume loss is negligible. [5]

Spiral CT angiogram delineates venous normal and anomalous anatomy in greater detail. Venous anomalies can be identified preoperatively, and unexpected injury can be prevented during its removal. This additional in­formation is very useful to the laparoscopic removal of the kidney. [6] 1 case of retroaortic renal vein was seen in our study that was confirmed at surgery. Circumaortic and retroaortic left renal veins are important anomalies that occur in 17% and 3% of healthy subjects, respectively. [7]

1 donor was found to have a solitary renal cyst on spiral CT and conventional angiography. The spiral CT charac­terizes parenchymal lesions in greater detail. This could lead to the diagnosis of incidental tumefactions. In the long run whether this will decrease the donor pool or not is an issue that is still not addressed. An additional advantage of pre-transplant screening with CT is the evaluation of other abdominal organs for unsuspected abnormality.

Spiral CT angiography is performed as an outpatient procedure and is less invasive compared with the conven­tional angiography. The morbidity from arterial puncture may be devastating and occurs in 1.73% of cases, includ­ing thromboembolism in 0.14%, pseudoaneurysm in 0.05%, bleeding in 0.26%, arteriovenous fistula forma­tion in 0.01 %. [8] Intravenous administration of the contrast eliminates the thromboembolic complication that may re­sult from the arterial catheter.

The other advantage of using spiral CT is its cost (Rs.5,500 vs Rs. 11,700). It provides excellent details of the venous anatomy as well as replacing 2 procedures (con­ventional angiogram and IVU) with 1. Spiral CT angiogram is safe, reliable, cost effective, accurate and acceptable. The use of conventional angiogram can be reserved in the workup of potential kidney donors when there is doubt re­garding vascular anatomy.


   Conclusions Top


Helical CT arteriography is accurate and highly spe­cific for arterial and venous anatomy. It provides vital in­formation needed for the surgical team before open or laparoscopic live donor nephrectomy. At our institution this imaging modality has replaced conventional angi­ogram and IVU in evaluation for live donor nephrectomy. Helical CT arteriography can become the primary imaging modality for preoperative assessment of potential renal donors. Conventional renal angiography is still the gold standard for identification of arterial multiplicity and fi­bromuscular dysplasia, and should be used adjunctively if there is an ambiguity. Live donation should be made less painful and more comfortable, and spiral CT angiog­raphy meets this objective.

 
   References Top

1.Riehle RA Jr, Steckler R, Naslund EB, Riggio R, Cheigh J. Stubenbord W. Selection criteria for the evaluation of living re­lated renal donors. J Urol 1990; 144: 845-8.  Back to cited text no. 1    
2.Rubin GD, Alfrey EJ, Dake MD et al. Assessment of living renal donors with spiral CT. Radiology 1995; 195: 457-62.  Back to cited text no. 2    
3.Dillon EH, van Leeuwen MS, Fernandez A, Mali WETM. Spiral CT angiography. AJR 1993; 160: 1273-8.  Back to cited text no. 3    
4.Derauf B, Goldberg ME. Angiographic assessment of potential renal transplant donors. Radiol Clin North Am 1987; 25: 261-5.  Back to cited text no. 4  [PUBMED]  
5.Joseph J, Del Pizzo, Geoffrey N, Sklar, Jade Won- You-Cheong Brian Evin, Thorsten Krebs, Stephen C. Jacobs. Helical computer­ized tomography arteriography for evaluation of live renal donors undergoing laparoscopic nephrectomy. J Urol 1999; 162: 31-34.  Back to cited text no. 5    
6.Smith PA, Rafter LE, Lynch FC, Corl FM, Fishman EK. Role of angiography in the preoperative evaluation for laparoscopic ne­phrectomy. Radiographics 1998; 18(3): 589-601.  Back to cited text no. 6    
7.Pick JW, Anson BJ. The renal vascular pedicle : An anatomical study of 430 body-halves. J Urol 1940; 44: 411-34.  Back to cited text no. 7    
8.Adams DF, Abrams HL. Complications of angiography. Radiology; 138: 419-26.  Back to cited text no. 8    


    Figures

  [Figure - 1], [Figure - 2], [Figure - 3]



 

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    Abstract
    Introduction
    Material and Methods
    Results
    Discussion
    Conclusions
    References
    Article Figures

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