Preoperative planning of renal transplantation: a comparison of non-contrast-enhanced ultrasonography, computed tomography, and magnetic resonance angiography with observations from surgery.

BACKGROUND: Many candidates for kidney transplantation need to undergo vessel examination before the transplantation procedure. PURPOSE: To identify the optimal preoperative modality for the examination of vessel status without the use of contrast agents in kidney transplant candidates. MATERIAL AND METHODS: Fifty-three consecutive patients were examined and 31 patients were transplanted. Ultrasonography (US), non-contrast-enhanced computed tomography (NCCT), and non-contrast-enhanced magnetic resonance angiography (NCMRA) were compared using inspection during kidney transplantation (TX) as a reference standard. The sensitivity and specificity to severe arteriosclerotic changes and the accuracy were calculated. Kappa statistics were used to assess the agreement between TX and the different examination modalities, and McNemar's test was used to test for significant differences. RESULTS: US had higher sensitivity (1.0) and better agreement with observations from surgery (k = 0.89) than both NCCT (sensitivity = 0.60; k = 0.72) and NCMRA (sensitivity = 0.20; k = 0.30). No significant difference was found between TX and US (P = 0.3173) or TX and NCCT (P = 0.1573), but there was a significant difference between TX and NCMRA (P = 0.0455). US was inconclusive in 20% of cases, and the internal iliac artery could not be visualized in 69% of cases. CONCLUSION: Either US or NCCT can be used as the preferred preoperative imaging modality to examine vessel status before kidney transplantation, but a combination of the two is preferable. NCMRA should not be used as the sole imaging modality for preoperative imaging before kidney transplantation because of its low sensitivity in detecting severe arteriosclerotic disease without the presence of stenosis.

Noncontrast-Enhanced Magnetic Resonance Versus Computed Tomography Angiography in Preoperative Evaluation of Potential Living Renal Donors.

RATIONALE AND OBJECTIVES: Living renal donors undergo an extensive examination program. These examinations should be as safe, gentle, and patient friendly as possible. To compare computed tomography angiography (CTA) and an extensive magnetic resonance imaging (MRI) protocol without contrast agents to observations from nephrectomy in living renal donors and to evaluate whether noncontrast-enhanced MRI can replace CTA for vessel assessment in living renal donors. MATERIAL AND METHODS: CTA and MRI results were compared to observations from nephrectomy, which served as the reference standard. Fifty-one potential kidney donors underwent imaging, and 31 donated a kidney. Comparisons in sensitivity, specificity, and accuracy were made with respect to the number of arteries, early branching, and the number of veins. Agreement was assessed using Cohen's kappa. The exact McNemar's test was used to test for statistically significant differences. RESULTS: In the assessment of more than one renal artery, the sensitivity and specificity of MRI and CTA were high and in perfect agreement compared to observations from surgery. The results for both MRI and CTA were as follows: (sensitivity 100%/specificity100%/accuracy 100%/Kappa = 1/P = 1). When comparing the ability to test for early branching we found, MRI: (sensitivity 33%/specificity 100%/accuracy 87%/Kappa = 0.45/P = 1) and CTA: (sensitivity 50%/specificity 100%/accuracy 90%/Kappa = 0.62/P = 1). When used to depict supernumerary veins, we found MRI: (sensitivity60%/specifivity100%/accuracy 93%/Kappa = 0.72/P = 1), whereas CTA showed: (sensitivity 40%/specificity 96%/accuracy 87% Kappa = 0.43/P = 1). CONCLUSIONS: In conclusion, an optimized MRI protocol that includes noncontrast-enhanced magnetic resonance angiography can be substituted for CTA for preoperative assessment of the renal vessels before living donor nephrectomy.