Estimation of Split Renal Function With 99mTc-DMSA SPECT: Comparison Between 3D Volumetric Assessment and 2D Coronal Projection Imaging

Dose-Effect Relationship of Kidney Function After SABR for Primary Renal Cell Carcinoma: TROG 15.03 FASTRACK II

PURPOSE

Stereotactic ablative body radiotherapy (SABR) is a novel option to treat primary renal cell carcinoma. However, a high radiation dose may be received by the treated kidney, which may affect its function posttreatment. This study investigates the dose-effect relationship of kidney SABR with posttreatment renal function.

METHODS AND MATERIALS

This was a prespecified secondary endpoint of the multicenter FASTRACK II (Focal Ablative STereotactic RAdiotherapy for Cancers of the Kidney phase II) clinical trial (National Clinical Trial 02613819). Patients received either 26 Gy in a single fraction (SF) for tumors with a maximal diameter of 4 cm or less or 42 Gy in 3 fractions (multifraction [MF]) for larger tumors. To determine renal function change, 99mTc-dimercaptosuccinic acid (DMSA) single-photon emission computed tomography/computed tomography (SPECT/CT) scans were acquired, and the glomerular filtration rate was estimated at baseline, 12, and 24 months posttreatment. Imaging data sets were rigidly registered to the planning CT where kidneys were segmented to calculate dose-response curves.

RESULTS

From 71 enrolled patients, 36 (51%) and 26 (37%) patients were included in this study based on availability of posttreatment data at 12 and 24 months, respectively. The ipsilateral kidney glomerular filtration rate decreased from baseline by 42% and 39% in the SF cohort and by 45% and 62% in the MF cohort, at 12 and 24 months, respectively (P < .03). The loss in renal function was 3.6%/Gy ± 0.8%/Gy and 4.5%/Gy ± 1.0%/Gy in the SF cohort and 1.7%/Gy ± 0.1%/Gy and 1.7%/Gy ± 0.2%/Gy in the MF cohort at 12 and 24 months, respectively. The major loss in renal function occurred in high-dose regions, where dose-response curves converged to a plateau.

CONCLUSIONS

For the first time in a multicenter study, the dose-effect relationship at 12 and 24 months post-SABR treatment for primary renal cell carcinoma was quantified. Kidney function reduces linearly with dose up to 100 Gy BED3.

Comparison of absolute renal uptake by using Tc-99m MAG-3 and Tc-99m DMSA

PURPOSE

The purpose of this study is to compare the value of absolute renal uptake (ARU %) in patients by using Tc-99m MAG-3 and Tc-99m DMSA scan.

MATERIAL AND METHODS

Absolute renal uptake is calculated using Tc-99m MAG-3 and Tc-99m DMSA in renal scintigraphy, Itoh and Tauex kidney depth methods used, respectively. n = 40 adult patients of both genders were included. All patients underwent Tc-99m MAG-3 and Tc-99m DMSA, respectively.

RESULTS

The values of ARU (%) were calculated separately in selected patients n = 40, (left = 17, right = 23 normal functioning kidneys) by MAG-3 and DMSA. Absolute renal uptake (%) of Tc-99m MAG-3 in left kidneys was found to be 15.2 ± 3.4, with spilt renal function 79.2 ± 14.7 and ARU (%) in right kidneys 16.2 ± 3.4 with spilt renal function 77.5 ± 19. Absolute renal uptake of Tc-99m DMSA in left kidneys was 17.5 ± 3.2 and in right kidneys 17.9 ± 4.5 with spilt renal function 81.8 ± 10.7 and 79.3 ± 13.8 for left and right kidney, respectively. Statistical analysis showed strong Pearson correlation.

CONCLUSION

Absolute renal uptake % was found to be more reliable in cases of bilateral compromised kidneys. ARU (%) calculated by Tc-99m MAG-3 solely can be used as predictor of renal function. The use of Tc-99m MAG-3 has more advantages than Tc-99m DMSA alone in renal scintigraphy as dynamic scintigraphy gives less radiation burden to patient, more information regarding renal function, and shorter stay time at hospital in comparison to static renal imaging. SRF % is less reliable than ARU (%).

Can We Predict Renal Function Recovery After Pyeloplasty in Pediatrics with Ureteropelvic Junction Obstruction? A Systematic Review

Chronic unilateral renal obstruction, primarily caused by ureteropelvic junction obstruction (UPJO), poses challenges in determining the optimal timing for corrective surgery. The goal is to preserve renal function and alleviate symptoms, but there is no definitive diagnostic test to reliably predict the outcomes of surgery. This systematic review aimed to identify predictors for renal function recovery after pyeloplasty in order to guide effective treatment options. We conducted a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. A literature search was performed on PubMed, Embase, and Scopus using keywords related to renal function, pyeloplasty, and predictors. The search was conducted on March 10, 2022. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Out of 344 potentially relevant articles, 11 met the eligibility criteria for this study. These included 6 retrospective and 5 prospective studies, with a total of 925 participants. Most studies evaluated renal function using differential renal function (DRF). The overall quality of the included studies was considered average. The findings indicated that age at the time of surgery and gender did not significantly influence functional recovery after pyeloplasty. However, preoperative DRF consistently emerged as a critical predictor. Preoperative DRF can serve as the most common predictors used for renal function recovery following pyeloplasty. These findings contribute to understanding effective treatment options for chronic unilateral renal obstruction. However, further research for each predictor is needed to validate these predictors and their clinical utility. Cite this article as: Siregar S, Mustafa A, Steven S. Can we predict renal function recovery after pyeloplasty in pediatrics with ureteropelvic junction obstruction? A systematic review. Urol Res Pract. Published online March 31, 2024. DOI:10.5152/tud.2024.23220.

Tc-99m DMSA SPECT for Follow-Up of Non-Operative Treatments in Renal Injuries: A Prospective Single-Center Study

OBJECTIVE

The assessment of cortical integrity following renal injuries with planar Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy depends on measuring relatively decreased cortical uptake (i.e., split renal function [SRF]). We analyzed the additive values of the volumetric and quantitative analyses of the residual cortical integrity using single-photon emission computed tomography (SPECT) compared to the planar scintigraphy.

MATERIALS AND METHODS

This prospective study included 47 patients (male:female, 32:15; age, 47 ± 22 years) who had non-operatively managed renal injuries and underwent DMSA planar and SPECT imaging 3-6 months after the index injury. In addition to planar SRF, SPECT SRF, cortical volume, and absolute cortical uptake were measured for the injured kidney and both kidneys together. The correlations of planar SRF with SPECT SRF and those of SRF with volumetric/quantitative parameters obtained with SPECT were analyzed. The association of SPECT parameters with renal function, grades of renal injuries, and the risk of renal failure was also analyzed.

RESULTS

SPECT SRF was significantly lower than planar SRF, with particularly higher biases in severe renal injuries. Planar and SPECT SRF (dichotomized with a cutoff of 45%) showed 19%-36% of discrepancies with volumetric and quantitative DMSA indices (when dichotomized as either high or low). Absolute cortical uptake of the injured kidney best correlated with glomerular filtration rate (GFR) at follow-up (ρ = 0.687, P < 0.001) with significant stepwise decreases by GFR strata (90 and 60 mL/min/1.73 m²). Total renal cortical uptake was significantly lower in patients with moderate-to-high risk of renal failure than those with low risk. However, SRF did not reflect GFR decrease below 60 mL/min/1.73 m² or the risk of renal failure, regardless of planar or SPECT (count- or volume-based SRF) imaging.

CONCLUSION

Quantitative measurements of renal cortical integrity assessed with DMSA SPECT can provide more clinically relevant and comprehensive information than planar imaging or SRF alone.

Ultrafast cadmium-zinc-telluride-based renal single-photon emission computed tomography: clinical validation

BACKGROUND

One of the main limitations of 99mtechnetium-dimercaptosuccinic acid (DMSA) scan is the long acquisition time.

OBJECTIVE

To evaluate the feasibility of short DMSA scan acquisition times using a cadmium-zinc-telluride-based single-photon emission computed tomography (SPECT) system in children.

MATERIALS AND METHODS

The data of 27 children (median age: 4 years; 16 girls) who underwent DMSA SPECT were retrospectively analyzed. Both planar and SPECT DMSA were performed. SPECT images were analyzed using coronal-simulated planar two-dimensional images. A reduction in SPECT acquisition time was simulated to provide 4 series (SPECT-15 min, SPECT-10 min, SPECT-5 min and SPECT-2.5 min). A direct comparison of the planar and SPECT series was performed, including semi-quantification reproducibility, image quality (mean quality score on a scale of 0 to 2) and inter- and intra-observer reproducibility of the scintigraphic patterns.

RESULTS

The overall image quality score (± standard deviation) was 1.3 (± 0.6) for the planar data set, 1.6 (± 0.5) for the SPECT-15 min data set, 1.4 (± 0.5) for the SPECT-10 min data set, 1.0 (± 0.5) for the SPECT-5 min data set and 0.6 (± 0.6) for the SPECT-2.5 min data set. Median Kappa coefficients for inter-observer agreement between planar and SPECT images were greater than 0.83 for all series and all readers except one reader for the SPECT-2.5 min series (median Kappa coefficient = 0.77).

CONCLUSION

Shortening SPECT acquisitions to 5 min is feasible with minimal impact on images in terms of quality and reproducibility.

Development and autoregulation of kidney function in children: a retrospective study using 99mTc-MAG3 renography

BACKGROUND

Both the development of kidney function in healthy children and autoregulation ability of kidney function in patients with asymmetric kidneys are important in clinical diagnosis and treatment of kidney-related diseases, but there are however only limited studies. This study aimed to investigate development of kidney function in normal children with healthy symmetric kidneys and autoregulation of the healthy kidney compensating the functional loss of a diseased one in children with asymmetric kidneys.

METHODS

Two hundred thirty-seven children (156 male, 81 female) from 0 to 20y (average 4.6y ± 5.1) undergoing ^99mTc-MAG3 renography were included, comprising 134 with healthy symmetrically functioning kidneys and 103 with asymmetric kidneys. Clearance was calculated from kidney uptakes at 1-2 min. A developmental model between MAG3 clearance (CL) and patient age in normal group was identified (CL = 84.39Age^0.395 ml/min, r = 0.957, p < 0.001). The clearance autoregulation rate in abnormal group with asymmetric kidneys was defined as the ratio of the measured MAG3 clearance and the normal value predicted from the renal developmental model of normal group.

RESULTS

No significant difference of MAG3 clearance (p = 0.723) was found between independent abnormal group and normal group. The autoregulation rate of kidney clearance in abnormal group was 94.2% on average, and no significant differences were found between two age groups (p = 0.49), male and female (p = 0.39), and left kidney and right kidney (p = 0.92) but two different grades of asymmetric kidneys (p = 0.02).

CONCLUSIONS

The healthy kidney of two asymmetric kidneys can automatically regulate total kidney function up to 94% of two symmetric kidneys in normal children.

Comparison of tomographic kidney volumes measured by semi-automatic segmentation method with scintigraphic split renal function in predicting posttransplant kidney functions

INTRODUCTION

In this study, it was aimed to compare scintigraphic split renal function (SRF) and computed tomographic (CT) kidney volumes by semi-automatic segmentation method in predicting graft functions after kidney transplantation.

METHODS

112 patients (77 males, 35 females) who had a living donor kidney transplant between 2015 and 2017 in our center were included in the study. While SRF was calculated with technetium-99m-diethylenetriaminepentaacetic acid (^99m Tc-DTPA) scintigraphy, CT angiography was used for volumetric calculations.

RESULTS

CT-volumetric measurements, especially renal cortical volume (RCV:103.8 ± 20 mL) and ratio to body mass index (RCV/BMI:4.45±1.3) were found to be more significant than ^99m Tc-DTPA-SRF in predicting graft functions. The correlations between SRF and RCV with 6th month eGFR (rSRF:0.052, rRCV:0.317, p=0.041) and 1st year eGFR (rSRF:0.104, rRCV:0.374, p=0.033) were found to be more significant in favor of RCV. The correlation between SRF/BMI and RCV/BMI with 1st, 6th and 12th month eGFR (respectively, p=0.02/0.048/0.024) were found to be more significant in favor of RCV/BMI. Although univariate analysis showed a significant relationship between most volumetric measurements and 1st year graft functions, in multivariate analysis only RCV (OR: 1.04(1.01-1.07), p=0.023) and RCV/BMI (OR: 2.5(1.27-5.39), p=0.013) showed a significant relationship between graft functions.

CONCLUSION

In our study, it was shown that CT-based renal volumetric measurements, especially RCV and RCV/BMI, predicted graft functions more strongly than scintigraphic ^99m Tc-DTPA-SRF. This article is protected by copyright. All rights reserved.

Planar scan vs. SPECT/low-dose CT for estimating split renal function by 99mTc-DMSA scintigraphy in children

In the present study, we compared estimates of split renal function (SRF) in paediatric patients of various diagnostic subgroups by ^99mTc-dimercaptosuccinic acid (DMSA) scintigraphy using either geometric mean (GM) based on planar scans or a volume of interest (VOI)-based analysis on single photon emission tomography combined with low-dose CT (SPECT/ldCT). Two experienced physicians blinded to patient diagnosis retrospectively analysed all paediatric ^99mTc-DMSA scintigraphies that were conducted in our department between 2011 and 2016 and which included both a planar scan and SPECT/ldCT. All scintigraphies were performed on either a Phillips Precedence 16 slice CT or a Siemens Symbia 16 slice CT. SRF was estimated from planar scintigraphy using the geometric mean (GM), while the VOI-based analysis (VBA) was used for kidney segmentation on SPECT/ldCT. RESULTS: A total of 68 scintigraphies were included. A Bland-Altman plot-based analysis showed a bias for SRF of 2.1% with limits of agreement from - 7.5 to + 11.7% for the whole data set but showed larger differences between the two methods outside the normal range of 45-55%. In the GM-based SRF analyses, 29 cases were found to be outside the normal range, and in seven of these, VBA showed normal SRF. In the remaining 39 cases, VBA showed an abnormal SRF in only one case. CONCLUSION: Approximately a quarter of planar DMSA scintigraphies that show an abnormal SRF in paediatric patients may be normal when assessed by SPECT/ldCT, which likely reflects underestimation of the kidney with the poorest function when assessed by GM due to the lack of attenuation correction. Planar scans that show an abnormal SRF in paediatric patients should thus preferably be supplemented by SPECT/ldCT.

Nuclear Medicine in Pediatric Nephro-Urology: An Overview

In the context of ante-natally diagnosed hydronephrosis, the vast majority of children with a dilated renal pelvis do not need any surgical treatment, as the dilatation resolves spontaneously with time. Slow drainage demonstrated at Tc-99m-mercaptoacetyltriglycine (MAG3) renography does not necessarily mean obstruction. Obstruction is defined as resistance to urinary outflow with urinary stasis at the level of the pelvic-ureteric junction (PUJ) which, if left untreated, will damage the kidney. Unfortunately this definition is retrospective and not clinically helpful. Therefore, the identification of the kidney at risk of losing function in an asymptomatic patient is a major research goal. In the context of renovascular hypertension a DMSA scan can be useful before and after revascularisation procedures (angioplasty or surgery) to assess for gain in kidney function. Renal calculi are increasingly frequent in children. Whilst the vast majority of patients with renal stones do not need functional imaging, DMSA scans with SPECT and a low dose limited CT can be very helpful in the case of complex renal calculi. Congenital renal anomalies such as duplex kidneys, horseshoe kidneys, crossed-fused kidneys and multi-cystic dysplastic kidneys greatly benefit from functional imaging to identify regional parenchymal function, thus directing further management. Positron emission tomography (PET) is being actively tested in genito-urinary malignancies. Encouraging initial reports suggest that F-18-fluorodeoxyglucose (FDG) PET is more sensitive than CT in the assessment of lymph nodal metastases in patients with genito-urinary sarcomas; an increased sensitivity in comparison to isotope bone scans for skeletal metastatic disease has also been reported. Further evaluation is necessary, especially with the promising advent of PET/MRI scanners. Nuclear Medicine in paediatric nephro-urology has stood the test of time and is opening up to new exciting developments.