3.0Tesla magnetic resonance angiography (MRA) for comprehensive renal evaluation of living renal donors: pilot study with computerized tomography angiography (CTA) comparison

One-stop preoperative assessment of renal vessels for living donors with 3.0 T non-contrast-enhanced magnetic resonance angiography: compared with computerized tomography angiography and surgical results

OBJECTIVE

The study was to investigate the feasibility and accuracy of assessment for living renal donors before transplantation by using 3.0 T non-contrast-enhanced magnetic resonance angiography (NCE-MRA).

METHODS

30 renal donors were investigated and underwent computed tomography angiography (CTA) and 3.0 T NCE-MRA before nephrectomy. Two radiologists independently assessed arterial and venous anatomy and potential kidney lesions. The image quality score, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diameters and lengths of renal arteries and veins were compared between CTA and NCE-MRA. Imaging findings were compared with the surgical results served as reference standard. Agreement was assessed using κ test. The Wilcoxon test and paired sample t test were used for statistically significant differences.

RESULTS

The results of image quality score for renal arteries and veins were highly consistent between the two radiologists in NCE-MRA (p < 0.001). There was no significant difference in the scores of renal arterial and venous branches between NCE-MRA and CTA (p > 0.05). The SNR and CNR of renal vessels were higher than CTA (p < 0.001). There were no statistically significant differences in the length of renal vessels measured by the two methods (p > 0.05), and the diameter was smaller than that of CTA (p < 0.05). The detection of normal renal arteries and early branches by both examination techniques was consistent with intraoperative findings. Both methods showed good consistency between the anatomical variation of renal vein and the intraoperative diagnosis (p < 0.001).

CONCLUSION

3.0 T NCE-MRA can be used for evaluation of main renal arteries and veins with high accuracy for anatomy and variation classification, and can be used for pre-operative vascular evaluation of living donor kidney transplantation.

ADVANCES IN KNOWLEDGE

3.0 T NCE-MRA can be used for evaluation of main renal arteries and veins with high accuracy for anatomy and variation classification, and can be used for pre-operative vascular evaluation of living donor kidney transplantation.

Unenhanced magnetic resonance angiography as an accurate alternative in the preoperative assessment of potential living kidney donors with contraindications to computed tomography angiography and to contrast-enhanced magnetic resonance angiography

Objective

To evaluate the accuracy of steady-state free precession (SSFP) unenhanced magnetic resonance angiography (MRA) at 1.5 T for the identification of multiple renal arteries, using computed tomography angiography (CTA) as the reference standard.

Materials and Methods

This was a prospective study involving 39 patients (26 males; mean age, 62.6 years) who underwent CTA and unenhanced MRA to evaluate the proximal and middle segments of the renal arteries. The analysis was performed in two phases: the quality of unenhanced MRA images was classified as diagnostic or nondiagnostic for the presence of multiple renal arteries by two independent readers; two other independent readers then evaluated the images previously classified as being of diagnostic quality. The sensitivity, specificity, and overall accuracy of unenhanced MRA were calculated, CTA being used as the reference standard. The kappa statistic was used in order to calculate interobserver agreement.

Results

The image quality of unenhanced MRA was considered diagnostic in 70-90% of the extrarenal arterial segments. The CTA examination revealed 19 multiple renal arteries (8 on the right and 11 on the left). The accuracy of unenhanced MRA for the identification of multiple renal arteries was greater than 90%, with a sensitivity of 72.7-100% and a specificity of 96.3-100%.

Conclusion

Unenhanced MRA provides high quality imaging of the extrarenal segments of renal arteries. This method may be used as an alternative for the evaluation of the renal arteries, given that it has an accuracy comparable to that of CTA.

Vascular imaging in renal donors

Imaging plays a crucial role in pre-transplant evaluation to enhance the probability of a successful outcome. Its aim is to define kidney and vascular anatomy and to assess potential pathologies. Each modality has advantages and disadvantages. Computed tomography angiography (CTA) is the most commonly used imaging modality, however, magnetic resonance angiography (MRA) can be used in selected cases. The purpose of this review article is to provide an overview of available imaging modalities, their benefits, risks, advantages, and disadvantages. Imaging findings that indicate particular anomalies and pathologies that may affect living renal donor selection will be discussed.

Impact of Incidental Findings During the Evaluation of Live Kidney Donors on Post-Transplant Outcomes: A Single Center Analysis

BACKGROUND

A careful assessment of a living donor is mandatory to minimize the short- and long-term risk related to kidney donation. In this study, we evaluated the incidence of incidental findings (IFs) in a large population of potential living kidney donors. Moreover, this study evaluated if the presence of IFs could influence the chance of living kidney donation and post-transplant outcomes.

METHODS

One hundred and sixty consecutive potential prospective living kidney transplant donors, who underwent a multidetector computed tomography angiography (MDCTA), were included in the study. An IF was defined as an incidentally discovered mass or lesion, detected by computed tomography angiography during the imaging evaluation of potential living donors. Clinical outcomes of living donors with IF were compared with those without IF.

RESULTS

In 10 patients (6.2%) an incidental finding was detected at MDCTA assessment. Among the 10 patients presenting with an IF, 7 patients (4.3%) were excluded from the living donation: 2 patients with an adrenal lesion, 3 patients with cancer, and 2 patients with a large (>8 cm) renal cyst. Graft and patient survival of kidney transplant recipients of donors with IFs were not significantly different to those receiving a kidney from living donors without IFs.

CONCLUSIONS

Incidental findings are frequently discovered during living kidney donor evaluation. Whereas most are asymptomatic or not clinically relevant, predonation screening could identify potentially life-threatening diseases at an earlier stage, allowing for a more radical treatment.

Evaluation of Vascular Structures of Living Donor Kidneys by Multislice Computed Tomography Angiography before Transplant Surgery: Is Arterial Phase Sufficient for Determination of Both Arteries and Veins?

Objectives

The aim of our study was to determine the efficacy of preoperative early arterial Computed tomography angiography (CTA) in donor nephrectomy, to assess the renal arterial and venous structures of donor kidneys.

Materials and Methods

Seventy living donor candidates were included to this study, who had CTA for the assessment of their renal vessels in our hospital between January 2011 and January 2015. Only early arterial phase images were obtained to avoid exposing the patients from high dose of radiation. Scans were reported by two radiologists independently. The number of renal arteries, veins and their tributaries were documented. The donor kidneys were removed by two consultant surgeons, and after back-table perfusion the same details were recorded and taken as the reference findings for the operation side.

Results

A total of 70 potential live kidney donors underwent renal CTA, among them fifty five patients had donor nephrectomy. A total of 140 kidneys were evaluated by CTA and the vessels of 55 harvested kidneys were compared with CTA findings. There were 40 kidneys that had at least one accessory or polar artery. There were 5 early branching renal arteries, two retroaortic and two circumaortic renal veins. Three kidneys had multiple renal veins. Operation findings were totally consistent with CTA findings in patients who underwent donor nephrectomy.

Conclusion

Arterial phase CTA is sufficient for evaluation of both arterial and venous vessels of kidneys, and precontrast, venous or late phase imaging should be preserved only for chosen circumstances to avoid high radiation exposure.