Multidetector computed tomography with triple-bolus contrast medium administration protocol for preoperative anatomical and functional assessment of potential living renal donors

Determination of split renal function in voluntary renal donors by multidetector computed tomography and nuclear renography: How well do they correlate?

Background

The use of computed tomography (CT) for estimation of split renal function (SRF) has been reported previously. However, most of these studies have small samples, and many do not account for the renal attenuation at CT.

Objective

The aim of this study was to compare multidetector computed tomography (MDCT) volumetry-attenuation-based SRF with that obtained via Tc99m-diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy in voluntary renal donors.

Methods

Between January 2017 and January 2020, 526 voluntary renal donors were enrolled prospectively. All donors underwent contrast CT and DTPA scan before surgery. The semiautomatic region of interest (ROI) tool was applied slice by slice on axial CT images acquired in the arterial phase. The renal contour was drawn semiautomatically with mouse clicks around the renal parenchyma, and the renal volume was ascertained. Using renal volume and attenuation, SRF was determined and compared with results obtained at DTPA imaging.

Results

The mean age was 44.91 ± 10.97 years (mean ± s.d.). There was no significant difference in SRF based on DTPA and MDCT volumetry for the left kidney (49.18% ± 3.40% vs. 49.15% ± 3.38%, p = 0.540) and for the right kidney (50.82% ± 3.40% vs. 50.86% ± 3.39%, p = 0.358). A very good correlation was observed between the two methods for the left kidney (r = 0.953, p = 0.000) and the right kidney (r = 0.955, p = 0.000). On simple linear regression analysis, 90.8% of DTPA SRF values for the left kidney and 91.3% of DTPA SRF values for the right kidney could be predicted correctly using the corresponding MDCT SRF values.

Conclusion

MDCT volumetry-attenuation-derived estimation of SRF for living renal donors could be an alternative to renal scintigraphy-based SRF estimation.

Can Split Renal Volume Assessment by Computed Tomography Replace Nuclear Split Renal Function in Living Kidney Donor Evaluations? A Systematic Review and Meta-Analysis

Background:

As part of their living kidney donor assessment, all living donor candidates complete a computed tomography (CT) angiogram, but some also receive a nuclear renogram for split renal function (SRF%).

Objective:

We considered whether split renal volume (SRV%) assessed by CT can predict SRF%.

Design:

Systematic review and meta-analysis.

Setting:

Living donor candidates undergoing evaluation as potential living kidney donors.

Patients:

Living donor candidates who received both a nuclear renogram for split function and CT for SRV as part of their living donor work-up.

Measurements:

Split renal volume from CT scans and SRF from nuclear renography.

Methods:

We performed a systematic review and meta-analysis of the literature, abstracting data and digitizing plots where possible. We searched Medline, EMBASE, and the Cochrane Library. We added data from donor candidates assessed in London, Ontario from 2013 to 2016. We used fixed and random-effects models to pool Fisher’s z-transformed Pearson’s correlation coefficient (r). We conducted random-effects meta-regression on digitized and aggregate data. Studies were restricted to living kidney donors or living donor candidates.

Results:

After pooling 19 studies (n = 1479), we obtained a pooled correlation of r = 0.74 (95% confidence interval [CI] = 0.61-0.82). By linear regression using individual-level data, we observed a 0.76% (95% CI = 0.71-0.81) increase in SRF% for every 1% increase in SRV%. Split renal volume had a specificity of 88% for discriminating SRF at a threshold that could influence the decision of which kidney is to be removed (between-kidney difference ≥10%). Predonation SRV and SRF both moderately predicted kidney function 6 to 12 months after donation: r = 0.75 for SRV and r = 0.73 for SRF; Δr = 0.05 (–0.02, 0.13).

Limitations:

Most studies were retrospective and measured SRV and SRF only on selected living donor candidates. Efficiency gains in removing the SRF from the evaluation will depend on the transplant program.

Conclusion:

Split renal volume has the potential to replace SRF for some candidates. However, it is uncertain whether it can do so reliably and routinely across different transplant centers. The impact on clinical decision-making needs to be assessed in well-designed prospective studies.

Trial registration:

The digitized data are registered with Mendeley Data (doi10.17632/dyn2bfgxxj.2).

Comparison of 270 Versus 320 mg I/mL of Iodixanol in 1 Image Assessment of Both Renal Arteries and Veins With Dual-Energy Spectral CT Imaging in Late Arterial Phase and Their Influence on Renal Function

OBJECTIVE

The objective of this study was to compare the image quality of renal arteries and veins with dual-energy spectral computed tomography (CT) imaging in late arterial phase using 270 and 320 mg I/mL of iodixanol and their influence on renal function.

METHODS

A total of 1062 patients underwent renal CT angiography with 270 or 320 mg I/mL of iodixanol with dual-energy spectral CT imaging in late arterial phase. Image quality and their influence on renal function were compared.

RESULTS

There were no significant differences of CT value, signal-to-noise ratio, contrast-to-noise ratio, and subjective score of renal vessels between 2 groups (all P > 0.05). The incidence of contrast-induced nephropathy in patients with abnormal renal function using 320 mg I/mL of iodixanol was significantly higher than using 270 mg I/mL of iodixanol (P = 0.043).

CONCLUSIONS

The renal arteries and veins can be fully assessed in late arterial phase with 270 mg I/mL of iodixanol using dual-energy spectral CT scan with better preserved renal function.

Experiences with the use of iteratively reconstructed dose-modified MDCT angiography examinations of living renal donors

PURPOSE

To evaluate the performance of iteratively reconstructed (IR) dose-modified (DM) multidetector computed tomography (MDCT) angiography (CTA) examinations of renal donors in comparison to standard dose filtered back projection (FBP) images.

MATERIALS AND METHODS

Eighty-five potential donors who underwent dual-phase CTA on 16-/64-MDCT scanners were retrospectively reviewed. Images from a 16-MDCT scanner were reconstructed with filtered back projection (group A, 47) and examinations from 64-MDCT with IR (group B, 38). Scan parameters were constant for both groups except for higher noise index (× 1.3) in group B. Images were interpreted for the relevant anatomy and IQ by 2 readers. Surgical report served as reference standard for operated kidneys, whereas for nonoperated kidneys, interobserver agreement was evaluated.

RESULTS

Radiation dose was 36% lower in group B compared to group A. All CTA examinations were rated for diagnostic quality with comparable IQ scores. In 48 operated kidneys, 10 surgically confirmed vascular anomalies were correctly identified by both readers. In the remaining 122 nonoperated kidneys, there was an excellent interobserver agreement.

CONCLUSIONS

Iteratively reconstructed technique preserves high image quality and diagnostic performance at significantly lower radiation doses in DM kidney donor CTA examinations.

CT urography for hematuria

Hematuria can signify serious disease such as bladder cancer, upper urinary tract urothelial cell carcinoma (UUT-UCC), renal cell cancer or urinary tract stones. CT urography is a rapidly evolving technique made possible by recent advances in CT technology. CT urography is defined as CT examination of the kidneys, ureters and bladder with at least one series of images acquired during the excretory phase after intravenous contrast administration. The reasoning for using CT urography to investigate hematuria is based on its high diagnostic accuracy for urothelial cell carcinoma (UCC) and favorable comparison with other imaging techniques. The optimum diagnostic imaging strategy for patients with hematuria at high-risk for UCC involves the use of CT urography as a replacement for other imaging tests (ultrasonography, intravenous urography, or retrograde ureteropyelography) and as a triage test for cystoscopy, resulting in earlier diagnosis and improved prognosis of bladder cancer, UUT-UCC, renal cell cancer and stones. Current problems with CT urography for investigating hematuria might be solved with a formative educational program simulating clinical reporting to reduce reader error, and a new technique for image-guided biopsy of UUT-UCC detected by CT urography for histopathological confirmation of diagnosis and elimination of false-positive results. CT urography is recommended as the initial imaging test for hematuria in patients at high-risk for UCC.