99mTc-diethylenetriaminepentaacetic Acid Research Articles

99mTc-DMSA and 99mTc-DTPA identified renal dysfunction due to microplastic polyethylene in murine model

In the previous study (Im et al., 2022), we revealed microplastic (MP) was accumulated and cleared through the kidneys via PET imaging. Here, we aimed to identify the renal dysfunction due to polyethylene (PE) MP in the kidney tissue. Mice were exposed to 100 ppm (∼equivalent to 0.1 mg/mL)/100 μL of PE for 12 weeks (n = 10). PE uptake in the kidney tissues was confirmed using confocal microscopy. QuantSeq analysis was performed to determine gene expression. Renal function assessment was performed using 99mTc-Diethylene triamine penta acetic acid or 99mTc-Dimercaptosuccinic acid. Measurement of creatinine, BUN, and albumin levels in serum and urine samples was also estimated. [18F]-FDG was also acquired. PE increased expression of Myc, CD44, Programmed Death-Ligand 1 (PD-L1), and Hypoxia-Inducible Factor (HIF)-1α, which indicates a potential link to an increased risk of early-onset cancer. An increase in glucose metabolism of [18F]-FDG were observed. We assessed renal failure using 99mTc-Diethylene triamine penta acetic acid and 99mTc-Dimercaptosuccinic acid scintigraphy to determine the renal function. Renal failure was confirmed using serum and urine creatinine, serum blood urea nitrogen levels, serum albumin levels, and urine albumin levels in PE exposed mice, relative to the control. In sum, PE exposure induced renal dysfunction in a murine model.

Deep learning-based measurement of split glomerular filtration rate with 99mTc-diethylenetriamine pentaacetic acid renal scan

PurposeTo develop a deep learning (DL) model for generating automated regions of interest (ROIs) on 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal scans for glomerular filtration rate (GFR) measurement.MethodsManually-drawn ROIs retrieved from a Picture Archiving and Communications System were used as ground-truth (GT) labels. A two-dimensional U-Net convolutional neural network architecture with multichannel input was trained to generate DL ROIs. The agreement between GFR values from GT and DL ROIs was evaluated using Lin’s concordance correlation coefficient (CCC) and slope coefficients for linear regression analyses. Bias and 95% limits of agreement (LOA) were assessed using Bland-Altman plots.ResultsA total of 24,364 scans (12,822 patients) were included. Excellent concordance between GT and DL GFR was found for left (CCC 0.982, 95% confidence interval [CI] 0.981–0.982; slope 1.004, 95% CI 1.003–1.004), right (CCC 0.969, 95% CI 0.968–0.969; slope 0.954, 95% CI 0.953–0.955) and both kidneys (CCC 0.978, 95% CI 0.978–0.979; slope 0.979, 95% CI 0.978–0.979). Bland-Altman analysis revealed minimal bias between GT and DL GFR, with mean differences of − 0.2 (95% LOA − 4.4–4.0), 1.4 (95% LOA − 3.5–6.3) and 1.2 (95% LOA − 6.5–8.8) mL/min/1.73 m² for left, right and both kidneys, respectively. Notably, 19,960 scans (81.9%) showed an absolute difference in GFR of less than 5 mL/min/1.73 m².ConclusionOur DL model exhibited excellent performance in the generation of ROIs on 99mTc-DTPA renal scans. This automated approach could potentially reduce manual effort and enhance the precision of GFR measurement in clinical practice.

Evaluation of Ectopic Kidney Located at the Deep Subcutaneous Region of the Abdominal Wall: Role of Diuretic Renography with 99mTc-DTPA.

An ectopic kidney is often found inadvertently during CT, ultrasonography, MRI, or urologic physical examination. Ectopic kidneys usually occur in the pelvis. A pelvic ectopic kidney may be misinterpreted for a pelvic tumor by less experienced physicians and surgeons. We present an extremely rare case of ectopic kidney in the deep subcutaneous region of the abdominal wall and associated with the additional abnormality of spina bifida. MRI found an ectopic kidney but failed to identify ureteropelvic drainage. Diuretic renography with 99mTc-diethylenetriaminepentaacetic acid showed normal functioning and identified nonobstructive ureteropelvic drainage of the ectopic subcutaneous kidney.

Abstract 6381: Long-term kidney function after treatment for unilateral, non-metastatic, non-syndromic Wilms tumor. A report from the St. Jude Lifetime Cohort Study

Abstract Background: We previously reported that the estimated glomerular filtration rate (eGFR) was decreased among survivors of unilateral, non-metastatic, non-syndromic Wilms tumor (WT) treated with whole abdomen radiation therapy (WART) compared to controls, but not compared to unirradiated WT survivors (Pediatr Blood Cancer 2020;67:e28271). The impact of sex on estimates of kidney function among adult survivors of WT has not been well-documented. Methods: We clinically evaluated male and female WT survivors with creatinine and cystatin C, calculated eGFR using the Chronic Kidney Disease - Epidemiology (CKD-EPI) equations with and without cystatin C and measured 99mTc diethylenetriamine pentaacetic acid (DTPA) plasma clearance. WT survivors consisted of 20 treated with unilateral nephrectomy (UN), non-nephrotoxic chemotherapy (NNC) and whole abdomen radiation therapy (WART) (mean - 20.2 Gray (Gy); standard deviation (SD) - 9.12 Gy), and 20 treated with UN, no radiation therapy, and NNC. Correlations between 99mTc DTPA clearance and eGFR were calculated. Results: Among female WT survivors, none of the eGFR calculations was statistically significantly correlated with 99mTc DTPA clearance. Among male WT survivors, 99mTc DTPA clearance correlated well with eGFR calculations that included creatinine. Results are shown in the Table. Conclusions: Among female survivors of unilateral, non-metastatic, non-syndromic WT who have undergone UN, eGFR is poorly correlated with 99mTc DTPA clearance. Evaluation of treatment-related changes in body composition may provide insight into these results. Correlation between eGFR and 99mTc DTPA clearance Females eGFR(CKD-EPI) 99mTc DTPA clearance No radiation therapy (n=13) Whole abdomen radiation therapy(n=12) Pearson correlation coefficient p-value Pearson correlation coefficient p-value Creatinine only 0.109 0.723 -0.295 0.352 Cystatin C only 0.311 0.301 0.094 0.782 Creatinine and cystatin C 0.348 0.244 -0.028 0.935 Males No radiation therapy (n=6) Whole abdomen radiation therapy(n=6) Pearson correlation coefficient p-value Pearson correlation coefficient p-value Creatinine only 0.827 0.043 0.859 0.028 Cystatin C only 0.811 0.050 0.592 0.216 Creatinine and cystatin C 0.878 0.021 0.866 0.026 Citation Format: Daniel M. Green, Mingjuan Wang, Matthew J. Krasin, Andrew M. Davidoff, DeoKumar Srivastava, Dennis W. Jay, Kirsten K. Ness, Barry L. Shulkin, Jennifer Q. Lanctot, Kyla C. Shelton, Rachel C. Brennan, Matthew J. Ehrhardt, Stephanie Dixon, Beth A. Kurt, Leslie L. Robison, Melissa M. Hudson, Sheri L. Spunt. Long-term kidney function after treatment for unilateral, non-metastatic, non-syndromic Wilms tumor. A report from the St. Jude Lifetime Cohort Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6381.

Quantitative analysis of abdominal aortic blood flow by 99mTc-DTPA renal scintigraphy in patients with heart failure.

This study aimed to explore the characteristics of abdominal aortic blood flow in patients with heart failure (HF) using 99mTc-diethylenetriaminepentaacetic acid (DTPA) renal scintigraphy. We investigated the ability of renal scintigraphy to measure the cardiopulmonary transit time and assessed whether the time-to-peak of the abdominal aorta (TTPa) can distinguish between individuals with and without HF. We conducted a retrospective study that included 304 and 37 patients with and without HF (controls), respectively. All participants underwent 99mTc-DTPA renal scintigraphy. The time to peak from the abdominal aorta's first-pass time-activity curve was noted and compared between the groups. The diagnostic significance of TTPa for HF was ascertained through receiver operating characteristic (ROC) analysis and logistic regression. Factors influencing the TTPa were assessed using ordered logistic regression. The HF group displayed a significantly prolonged TTPa than controls (18.5 [14, 27] s vs. 11 [11, 13] s). Among the HF categories, HF with reduced ejection fraction (HFrEF) exhibited the longest TTPa compared with HF with mildly reduced (HFmrEF) and preserved EF (HFpEF) (25 [17, 36.5] s vs. 17 [15, 23] s vs. 15 [11, 17] s) (P < 0.001). The ROC analysis had an area under the curve of 0.831, which underscored TTPa's independent diagnostic relevance for HF. The diagnostic precision was enhanced as left ventricular ejection fraction (LVEF) declined and HF worsened. Independent factors for TTPa included the left atrium diameter, LVEF, right atrium diameter, velocity of tricuspid regurgitation, and moderate to severe aortic regurgitation. Based on 99mTc-DTPA renal scintigraphy, TTPa may be used as a straightforward and non-invasive tool that can effectively distinguish patients with and without HF.

Comparison of Renal Functions Evaluated by Measured Glomerular Filtration Rate in Patients Treated With Cisplatin, Carboplatin, and Oxaliplatin.

In cancer chemotherapy platinum drugs do cause damage to the normal cells and as a result, many physiological functions are derailed. Renal function as measured by measured glomerular filtration rate(mGFR) plays a large role in drug dosing on the basis of the maximum tolerated dose, which is the highest dose that may be administered without unacceptable toxicity, to maximize anticancer efficacy. The objective of the study was to compare the toxic effect of platinum drugs on renal function as measured by mGFR in patients with malignancy and to study the difference in the magnitude of nephrotoxicity by these drugs. The study was conducted in the Department of Physiology in close collaboration with the Department of Radiotherapy at a tertiary care centre in Western Rajasthan, India. 150 patients suffering from different malignances undergoing treatment with cisplatin, carboplatin, and oxaliplatin were examined for their renal functionas measured by mGFR using 99mTc-diethylene triamine pentaacetic acid (99mTc-DTPA) and were compared with 50 subjects of control group. In the cisplatin group there was a gradual fall of GFR from 85.49 ml/min/1.73sqm to 58.09ml/min/1.73sqm at cycle II. In the carboplatin group it was 84.86ml/min/1.73sqm at baseline whereas cycle II was 75.5 ml/min/1.73sqm with SD ± 16.49. mGFR fell significantly (p<0.0001) in cisplatin and carboplatin groups but not in the cohort of patients who received oxaliplatin. The GFR reduction continued from the baseline to cycle I and then cycle II in cisplatin and carboplatin groups. Nephrotoxicity is a major side effectof platin drugs and further studies should be done to establish their optimal dose in relation to renal function and minimize toxicity by trying various cytoprotective agents.

Impact of the New Glomerular Filtration Rate Formulas on Kidney Function Assessment in Living Kidney Donors and Candidates.

To address this, we conducted a single-center retrospective cohort study of 150 kidney donors and donor candidates. We calculated pre- and postdonation eGFR using the old and new equations and compared them with measured GFR by 2.8 mCi Tc-99m diethylene triamine penta-acetic acid clearance (mGFRDTPA) and 24-h creatinine clearance (mGFRCrCl). We evaluated the impact of the new equations on donation eligibility and postdonation eGFR. We found that using the new eGFR equations resulted in higher predonation eGFR compared with the old equations but remained significantly lower than mGFRDTPA and mGFRCrCl. We also found that using the new eGFR equations would not exclude any potential donors based on our center's GFR criteria for donation. At 6 mo postdonation, the new equations resulted in higher eGFR values compared with the old equations. The new eGFR equations continue to underestimate GFR in healthy donor candidates but would not exclude any potential donors from donation and resulted in higher eGFR predonation and postdonation in a predominantly White population. eGFR equations designed specifically for potential kidney donors are still needed for better kidney function assessment.

Reproducibility of Computed Tomography Volumetry for Predicting Post-Donation Remnant Renal Function: A Retrospective Analysis

Recent studies indicate that split renal function calculated by computed tomography (CT) volumetry is equally or more useful than that calculated by nuclear renography for donated kidney side selection. However, it remains unclear if CT volumetry accurately reflects split renal function as measured by nuclear renography. Therefore, this study aimed to evaluate the reproducibility of CT volumetry. Data from 141 donors who underwent living donor nephrectomy at Nara Medical University from March 2007 to June 2021 were reviewed. The correlation and agreement between the predicted postdonation estimated glomerular filtration rate (eGFR) by 99mTc-diethylenetriamine penta-acetic acid (DTPA) scintigraphy and by CT volumetry were evaluated by the Pearson's correlation coefficient and Bland-Altman analysis, respectively. Moreover, a comparison in split renal function categorization between 99mTc-DTPA scan and CT volumetry was performed. A total of 133 donors were included in the analysis. There was high correlation between the predicted postdonation eGFR by 99mTc-DTPA scintigraphy and by CT. Moreover, there was agreement in the predicted postdonation eGFR between 99mTc-DTPA scintigraphy and CT volumetry (Bland-Altman analysis [bias, 95% limits of agreement]; 0.83%, -5.6% to 7.3%). However, in one of 17 donors with absolute split renal function greater than 10% by 99mTc-DTPA scintigraphy, this clinically significant difference was missed by CT volumetry. There are donors for whom a clinically significant split renal function is not accurately reflected in CT volumetry. Future studies need to amend this discrepancy.

Effect of decreased renal function on poor oncological outcome after radical cystectomy.

To evaluate the impact of preoperative renal impairment on the oncological outcomes of patients with urothelial carcinoma who underwent radical cystectomy. We retrospectively reviewed the medical records of patients with urothelial carcinoma who underwent radical cystectomy from 2004 to 2017. All patients who underwent preoperative 99mTc-diethylenetriaminepentaacetic acid renal scintigraphy (DTPA) were identified. We divided the patients into two groups according to their glomerular filtration rates (GFRs): GFR group 1, GFR≥90 mL/min/1.73 m²; GFR group 2, 60≤GFR<90 mL/min/1.73 m². We included 89 patients in GFR group 1 and 246 patients in GFR group 2 and compared the clinicopathological characteristics and oncological outcomes between the two groups. The mean time required for recurrence was 125.5±8.0 months in GFR group 1 and 85.7±7.4 months in GFR group 2 (p=0.030). The mean cancer-specific survival was 131.7±7.8 months in GFR group 1 and 95.5±6.9 months in GFR group 2 (p=0.051). The mean overall survival was 123.3±8.1 months in GFR group 1 and 79.5±6.6 months in GFR group 2 (p=0.004). Preoperative GFR values in the range of 60≤GFR<90 mL/min/1.73 m² are independent prognostic factors for poor recurrence-free survival, cancer-specific survival, and overall survival in patients after radical cystectomy compared with GFR values of ≥90 mL/min/1.73 m².

Performance and Feasibility of Therapeutic Vibrating Mesh Nebulizer for Ventilation Lung Scan

PurposeThis study aimed to evaluate the performance of a therapeutic vibrating mesh-type nebulizer for the pulmonary delivery of radioaerosols for lung scintigraphy in healthy subjects.MethodsSix healthy subjects (mean age of 28.7 ± 6.2 years) inhaled 2 mL Tc-99m diethylenetriaminepentaacetic acid and normal saline solution (20 mCi) via a therapeutic vibrating mesh-type nebulizer (DK010, DELBio, Taipei, Taiwan). The nebulizer’s mass median aerodynamic diameter was between 2.3 and 5.0 µm (3.47 ± 0.37 µm), and the nebulization rate was greater than 0.2 mL/min. Scintigraphy was performed to count radioaerosols in the regions of interest to determine the total and regional lung deposition and extrathoracic airway deposition of aerosols, penetration of aerosols, and radioactivity count balance (RCB).ResultsThe total lung depositions of aerosols were 21.2% ± 5.2% (% ex-valve dose), 27.4% ± 8.0% (% ex-device dose), and 13.8% ± 4.1% (% initial dose) in the nebulizer. The extrathoracic airway deposition was 4.8% ± 1.1%. The RCB was 5.4% ± 3.0%. The ratio of outer over inner lung deposition (O/I ratio, or penetration index) was 1.89 ± 0.55.ConclusionThe delivery efficiency and penetration of aerosols to the peripheral lung, which were achieved by the DELBio DK010 vibrating mesh-type nebulizer, were similar to the commercialized jet-type nebulizers dedicated for radioaerosol lung scintigraphy nebulizer. The therapeutic vibrating mesh-type nebulizer (DELBio DK010) is feasible for radionuclide lung ventilation scintigraphy.

SPECT/CT imaging reveals CNS-wide modulation of glymphatic cerebrospinal fluid flow by systemic hypertonic saline

SummaryIntrathecal administration enables central nervous system delivery of drugs that do not bypass the blood-brain barrier. Systemic administration of hypertonic saline (HTS) enhances delivery of intrathecal therapeutics into the neuropil, but its effect on solute clearance from the brain remains unknown. Here, we developed a dynamic in vivo single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging platform to study the effects of HTS on whole-body distribution of the radiolabeled tracer 99mTc-diethylenetriaminepentaacetic acid (DTPA) administered through intracisternal, intrastriatal, or intravenous route in anesthetized rats. Co-administration of systemic HTS increased intracranial exposure to intracisternal 99mTc-DTPA by ∼80% during imaging. In contrast, HTS had minimal effects on brain clearance of intrastriatal 99mTc-DTPA. In sum, SPECT/CT imaging presents a valuable approach to study glymphatic drug delivery. Using this methodology, we show that systemic HTS increases intracranial availability of cerebrospinal fluid-administered tracer, but has marginal effects on brain clearance, thus substantiating a simple, yet effective strategy for enhancing intrathecal drug delivery to the brain.

The Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating glomerular filtration rate in Chinese patients with chronic kidney disease.

To evaluate the clinical practicability of the Xiangya equation in estimating glomerular filtration rate (GFR) and compare with the Asian modified Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation, assessing whether the Xiangya equation could replace the Asian modified CKD-EPI equation as the preferred method for predicting GFR in the Chinese CKD patients in an external validation study. The GFR was determined simultaneously by two methods: (a) the Asian modified CKD-EPI equation (GFRCKD-EPI); (b) the Xiangya equation (GFRXiangya); diagnostic performance of the two models was compared by the regression analysis, the Bland-Altman plot, bias, precision and P30 under the background of 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) dual plasma sample clearance method as reference method for GFR measurement (mGFR). A total of 158 Chinese CKD patients were included in our external study. The GFRXiangya was highly related with mGFR, with the correlation coefficient of 0.92. The regression equation was GFRXiangya = 0.55*mGFR + 28.25, where the regression coefficient was far away from one and the intercept was wide. Compared with the Asian modified CKD-EPI equation, the performance of the Xiangya equation demonstrated a poorer bias (9.5 vs -3.3ml/min/1.73 m2, P < 0.001), an inferior precision (23.9 vs 13.0ml/min/1.73 m2, P < 0.001), a lower P30 (51.3% vs 73.4%, P < 0.001) and a wider 95% limit of agreement in Bland-Altman analysis (65.0 vs 44.9ml/min/1.73 m2). Due to relatively inferior performance, the Xiangya equation could not replace the Asian modified CKD-EPI equation in estimating GFR in Chinese patients with chronic kidney disease in our external cohort.

Use of CT-based renal volumetry for the measurement of split renal function: a split glomerular filtration rate prediction model based on unilateral renal volume parameters

To develop a split glomerular filtration rate (sGFR) prediction model based on unilateral renal volume parameters using three-dimensional (3D) computed tomography (CT) volumetry. Clinical data (age, sex, height, weight, serum creatinine level [sCr], and sGFR measured by 99mTc-diethylene triamine pentaacetic acid nuclear renal scintigraphy with the double plasma sample method) of 67 healthy renal donors and 111 patients with hydronephrosis admitted from April 2016 to September 2021 were analysed. The split renal parenchymal volume (sRPV) and split renal calyces and pelvis volume (sRCPV) of 67 unilateral donor left kidneys and 111 hydronephrotic kidneys were measured. Statistical analysis of these parameters was performed to develop and validate the sGFR prediction model. sRPV (p<0.001), sRCPV (p=0.012), age (p=0.015), serum creatinine level (p=0.004), and weight (p=0.006) were significantly associated with the measured sGFR and were included in the sGFR prediction formula, which was constructed as: 68.710+0.093×sRPV-0.041×sRCPV-0.228×W-0.219×A-14.432×sCr (r2=0.416; where A is age, W is weight). The paired difference of internal validation between the measured sGFR (42.34±13.71 ml/min/1.73 m2) and the sGFR estimated by the prediction model (41.46±8.99 ml/min/1.73 m2) was 0.879±11.475 ml/min/1.73 m2 (p=0.492) with a 95% confidence interval of the mean difference of ±2.54 ml/min/1.73 m2. The proposed model based on sRPV and sRCPV parameters could be used for estimating split renal function of healthy renal donors and patients with hydronephrosis to some extent. Further studies are required to evaluate and rectify the model.

Agreement between serum estimates of glomerular filtration rate (GFR) and a reference standard of radioisotopic GFR in children with cancer.

Accurate assessment of renal function is important in the care of children with cancer because renal function has implications for anti-tumor medication dosing and eligibility for clinical trials. To characterize agreement between serum estimates of glomerular filtration rate (GFR) and a reference standard of radioisotopic GFR in a large pediatric oncology cohort. We conducted a retrospective cross-sectional study of children who had both radioisotopic GFR (99mTc-diethylenetriaminepentaacetic acid, or 99mTc-DTPA) and serum labs (creatinine, cystatin C) obtained <7days apart between January 2017 and August 2019. We calculated estimated GFR from serum labsusing published equations and calculated agreement using intraclass correlation coefficient (ICC) and Bland-Altman analysis with univariate regression to define predictors of agreement. We included 272 pairs of data. Mean patient age was (mean ± standard deviation) 7.8±5.7years. Mean radioisotopic GFR was 112±33mL/min/1.73m2. Absolute agreement between radioisotopic GFR and serum estimates was only fair (ICC=0.46-0.58) with a mean difference of -26.6 to +0.12mL/min/1.73m2. For radioisotopic GFR measurements <60mL/min/1.73m2, mean differences were greater, with serum estimates overestimating GFR by a mean of 21.5-39.6mL/min/1.73m2. In multivariable modeling, significant predictors of agreement included age, height, acute kidney injury and tumor type. Sensitivity of serum estimates was 14-29% for a GFR <60mL/min/1.73m2. Agreement between radioisotopic GFR and serum estimates of GFR is only fair and serum estimates of GFR have poor sensitivity for clinically relevant GFR <60mL/min/1.73m2. Radioisotopic measurement of GFR likely remains necessary to assess renal function in pediatric oncology patients with decreased renal function.

Measurement of glomerular filtration rate and its current status in African countries GFR measurement and its status in Africa

Glomerular filtration rate (GFR) is usually estimated rather than measured as this only requires measurement of an endogenous filtration marker. In certain clinical settings a more accurate measure of GFR is essential. The most commonly used endogenous filtration marker is creatinine. Exogenous filtration markers include nonradiopharmaceuticals such as inulin, iohexol and unlabelled iothalamate, or radiopharmaceuticals such as 51Crethylenediaminetetraacetic acid (51Cr-EDTA) and 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA). Inulin is considered an ideal filtration marker but the clearance of iothalamate, 99mTc-DTPA, 51Cr-EDTA and iohexol have all been shown to have sufficient accuracy for measuring GFR. For radiopharmaceuticals, a well counter is required to measure the amount of activity in patient samples. Iohexol or unlabelled iothalamate require samples to be measured using high performance liquid chromatography with ultraviolet detection (HPLC-UV), liquid chromatography-tandem mass spectrometry (LC-MS/MS) or x-ray fluorescence (XRF). Due to the practical challenges of measuring urinary clearance, measurement of GFR in clinical settings is almost exclusively based on plasma clearance of a filtration marker. This can follow a long-established approach based on the ratio of the tracer administered to the area under the plasma concentration curve. Alternatively, a single plasma sample giving an apparent volume of distribution at a given time point can be used to accurately measure GFR. While techniques exist for the measurement of GFR in a number of African countries, preliminary evidence suggests that facilities are very limited. There is a need for support for both equipment and training to establish GFR measurement facilities in several centres on the continent. Keywords: measured glomerular filtration rate;, mGFR;, Africa

Comparison of double plasma sampling method and gates method for estimation of glomerular filtration rateComparison of double plasma sampling method and gates method for estimation of glomerular filtration rateComparison of double plasma sampling method a

Glomerular filtration rate (GFR) is an important indicator of renal function. Several methods have been applied to calculate GFR in clinical exams. In this study, we evaluated and compared between radionuclide plasma sampling methods (double blood samples, in vitro methods) and in vivo Gate’s method using 99mTc-diethylene triamine penta-acetic acid (99mTc-DTPA) renography. Subejct and method: 42 patients were participated in this study, including 12 patients with obstructive uropathy (group 1) and 30 renal donors (group 2). The administered doses were in a range of 5 – 7mCi. Then, scintigraphy was performed simultaneously after injection, and GFR was calculated by Gate’s method. Blood samples were collected at 60 mins and 120 mins post-injection, which were counted by a thyroid uptake system, and GFR results were determined using a double plasma sample (DPSM) method. Result: The mean GFRs calculated by renography in groups 1 and 2 were 85.8 ± 16.2 (ml/min) and 118.9 ± 13.9 (ml/min), respectively. Meanwhile, using the in vitro DPSM, the mean GFRs in group 1 and 2 were 73.8 ± 15.4 (ml/min) and 117.0 ± 13.0 (ml/min) respectively. They showed a high correlation between the two methods in the two groups (r = 0.86 and 0.71, respectively). Conclusion: Renography is a simple technique but considered inaccurate for determination of GFR. However, in vitro DPSM is rarely used in Vietnam. In this study, Gate’s method corresponded well with plasma sampling method and tended to overestimate the glomerular filtration rate.

CT-measured Cortical Volume Ratio Is an Accurate Alternative to Nuclear Medicine Split Scan Ratio Among Living Kidney Donors.

The 125I-iothalamate clearance and 99mTc diethylenetriamine-pentaacetic acid (99mTc-DTPA) split scan nuclear medicine studies are used among living kidney donor candidates to determine measured glomerular filtration rate (mGFR) and split scan ratio (SSR). The computerized tomography-derived cortical volume ratio (CVR) is a novel measurement of split kidney function and can be combined with predonation estimated GFR (eGFR) or mGFR to predict postdonation kidney function. Whether predonation SSR predicts postdonation kidney function better than predonation CVR and whether predonation mGFR provides additional information beyond predonation eGFR are unknown. We performed a single-center retrospective analysis of 204 patients who underwent kidney donation between June 2015 and March 2019. The primary outcome was 1-y postdonation eGFR. Model bases were created from a measure of predonation kidney function (mGFR or eGFR) multiplied by the proportion that each nondonated kidney contributed to predonation kidney function (SSR or CVR). Multivariable elastic net regression with 1000 repetitions was used to determine the mean and 95% confidence interval of R2, root mean square error (RMSE), and proportion overprediction ≥15 mL/min/1.73 m2 between models. In validation cohorts, eGFR-CVR models performed best (R2, 0.547; RMSE, 9.2 mL/min/1.73 m2, proportion overprediction 3.1%), whereas mGFR-SSR models performed worst (R2, 0.360; RMSE, 10.9 mL/min/1.73 m2, proportion overprediction 7.2%) (P < 0.001 for all comparisons). These findings suggest that predonation CVR may serve as an acceptable alternative to SSR during donor evaluation and furthermore, that a model based on CVR and predonation eGFR may be superior to other methods.

The ensemble learning model is not better than the Asian modified CKD-EPI equation for glomerular filtration rate estimation in Chinese CKD patients in the external validation study

ObjectiveTo assess the clinical practicability of the ensemble learning model established by Liu et al. in estimating glomerular filtration rate (GFR) and validate whether it is a better model than the Asian modified Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in a cohort of Chinese chronic kidney disease (CKD) patients in an external validation study.MethodsAccording to the ensemble learning model and the Asian modified CKD-EPI equation, we calculated estimated GFRensemble and GFRCKD-EPI, separately. Diagnostic performance of the two models was assessed and compared by correlation coefficient, regression equation, Bland–Altman analysis, bias, precision and P30 under the premise of 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) dual plasma sample clearance method as reference method for GFR measurement (mGFR).ResultsA total of 158 Chinese CKD patients were included in our external validation study. The GFRensemble was highly related with mGFR, with the correlation coefficient of 0.94. However, regression equation of GFRensemble = 0.66*mGFR + 23.05, the regression coefficient was far away from one, and the intercept was wide. Compared with the Asian modified CKD-EPI equation, the diagnostic performance of the ensemble learning model also demonstrated a wider 95% limit of agreement in Bland-Altman analysis (52.6 vs 42.4 ml/min/1.73 m2), a poorer bias (8.0 vs 1.0 ml/min/1.73 m2, P = 0.02), an inferior precision (18.4 vs 12.7 ml/min/1.73 m2, P < 0.001) and a lower P30 (58.9% vs 74.1%, P < 0.001).ConclusionsOur study showed that the ensemble learning model cannot replace the Asian modified CKD-EPI equation for the first choice for GFR estimation in overall Chinese CKD patients.

Effect of a Surfactant Additive on Drug Transport and Distribution Uniformity After Aerosol Delivery to Ex Vivo Lungs.

Background: Inhaled drug delivery can be limited by heterogeneous dose distribution. An additive that would disperse drug over the internal surfaces of the lung after aerosol deposition could improve dosing uniformity and increase the treated area. Our previous studies demonstrated that surfactant additives can produce surface tension-driven (Marangoni) flows that effectively dispersed aerosol-delivered drugs over mucus surfaces. Here we sought to determine whether the addition of a surfactant would increase transport of an aerosol between lung regions and also improve dosing uniformity in human lungs. Methods: We compared the deposition and postdeposition dispersion of surfactant (10 mg/mL dipalmitoylphosphatidylcholine; DPPC) and saline-based liquid aerosols, admixed with Technetium 99m (Tc99m) diethylenetriaminepentaacetic acid, using gamma scintigraphy. Deposition images were obtained ex vivo in eight pairs of ventilated human lungs. The trachea was intubated and the mainstem bronchi were alternately clamped so that saline was delivered to one lung and then DPPC to the other (sides alternated). The lungs were continually imaged for 15 minutes during delivery. We assessed transport of the deposited aerosol by quantifying the percentage of Tc99m in each of four lung quadrants over time. We quantified dose uniformity within each lung quadrant by measuring the coefficient of variation (CV = standard deviation of the pixel associated radioactive counts/mean of the counts within each quadrant). Results: There was no change in the percentage of Tc99m in each quadrant over time, indicating no improvement in transport with the addition of the surfactant. The addition of surfactant was associated with a statistically significant decrease in CV in the lower inner lung quadrant at each of the three time points, indicating an improvement in dosing uniformity. Conclusion: These preliminary results indicate the possible utility of adding surfactant to aerosols to improve drug distribution uniformity to lower inner lung regions.

Gastric emptying of preoperative drinks is slower in adults with chronic energy deficiency: A 2 hour cross-over study among Chinese.

To investigate the effects of oral preoperative regimens on gastric emptying time in relation to BMI in Chinese adults. The enrolled 56 adults were divided into three groups (normal-weight, underweight, and overweight) and completed a regimen of two drinks after a 2-week interval. After drinking a carbohydrate regimen (CD, 50 g carbohydrates) or a carbohydrate glutamine regimen (CGD, 44 g carbohydrates and 6 g glutamine) labelled with 99mTc-DTPA (99mTc-diethylenetriaminepentaacetic acid), gastric emptying times T50 and T90 were measured using a curve derived from scintigraphic images. T50 and T90 had no significant difference between the CD and CGD regimens. T50 was significantly delayed in the underweight participants (BMI <18.5 kg/m2, as Chronic Energy Deficiency, CED) compared with the normal-weight participants after drinking CD (p=0.003) or CGD (p=0.002), as well as T90 after CD (p=0.019). There was no difference in glucose concentrations between the three groups. There are negative correlations between body weight and gastric emptying time T50 (r=-0.461, p=0.016) or T90 (r=-0.553, p=0. 003) after drinking CD, as well as T50 (r=-0.553, p=0.003) after drinking CGD. Underweight adults should be careful to take oral preoperative regimens 2 hours before surgery and consider reducing the volume because of a slower gastric emptying rate.