Quantitation of renal function with static imaging agents

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.

Assessing the correlation between 68Ga-PSMA-11 renal PET parameters and renal function tests

Aim: ⁶⁸Ga -PSMA ligands are used for prostate cancer but also show high renal cortical uptake. In this study, we aimed to assess if there is any correlation between renal PSMA PET parameters and renal function tests using the images of prostate cancer patients. Methods: ⁶⁸Ga-PSMA-11 PET/CT images of the patients with prostate cancer were retrospectively evaluated. The following PET parameters were obtained: SUV_max, SUVmean, SULmax, SULmean, volume, TLGSUL and counts of both kidneys as well as SUVmean of liver, blood pool and spleen. Total TLGSUL, total volume, kidney to liver and kidney to blood pool ratios were calculated. Patient's creatinine values were obtained and GFR was calculated using the MDRD formula. Statistical analysis was performed to understand if there is a correlation between above parameters and renal function tests. Results: Twenty five patients were included in this study. GFR was significantly/positively correlated and creatinine was significantly/negatively correlated with renal SUV/liver SUV and renal SUV/blood pool SUV ratios. GFR was marginally positively correlated with renal SULmean and creatinine was marginally negatively correlated with total TLGSUL. Total renal parenchymal volume was significantly and directly (positively) associated with GFR and significantly and inversely (negatively) associated with creatinine. Conclusion: Renal ⁶⁸Ga-PSMA uptake appears to be correlated with renal function tests. Our method of measuring approximate renal parenchymal volume on PET image appears to be reliable.

Renal Cortical Scarring: 68Ga-PSMA-11 PET versus 99mTc-DMSA Scan in a Case with Pyelonephritis

We previously reported ⁶⁸Ga-prostate‑specific membrane antigen (PSMA)-11 and ^99mTcdimercaptosuccinic acid (DMSA) images of the 1st case of our prospective research comparing renal PSMA PET to DMSA scan in adult patients with pyelonephritis. Here, we present renal cortical PSMA PET and DMSA images of our 2nd patient with chronic recurring pyelonephritis which demonstrated renal parenchymal defects secondary to scarring in the kidney.

Current and future perspectives on functional molecular imaging in nephro-urology: theranostics on the horizon

In recent years, a paradigm shift from single-photon-emitting radionuclide radiotracers toward positron-emission tomography (PET) radiotracers has occurred in nuclear oncology. Although PET-based molecular imaging of the kidneys is still in its infancy, such a trend has emerged in the field of functional renal radionuclide imaging. Potentially allowing for precise and thorough evaluation of renal radiotracer urodynamics, PET radionuclide imaging has numerous advantages including precise anatomical co-registration with CT images and dynamic three-dimensional imaging capability. In addition, relative to scintigraphic approaches, PET can allow for significantly reduced scan time enabling high-throughput in a busy PET practice and further reduces radiation exposure, which may have a clinical impact in pediatric populations. In recent years, multiple renal PET radiotracers labeled with 11C, 68Ga, and 18F have been utilized in clinical studies. Beyond providing a precise non-invasive read-out of renal function, such radiotracers may also be used to assess renal inflammation. This manuscript will provide an overview of renal molecular PET imaging and will highlight the transformation of conventional scintigraphy of the kidneys toward novel, high-resolution PET imaging for assessing renal function. In addition, future applications will be introduced, e.g. by transferring the concept of molecular image-guided diagnostics and therapy (theranostics) to the field of nephrology.

The Use of Tissue Adhesive for Tumor Bed Closure during Partial Nephrectomy is Associated with Reduced Devascularized Functional Volume Loss

Objectives

To quantitatively compare the functional renal volume loss, following nephron sparing surgery (NSS) between patients in whom tumor bed closure was done by biological tissue adhesive and those who were managed by standard suture technique.

Methods

From our institutional NSS database we retrospectively collected patients who had two sequential quantitative single-photon emission computed tomography of ^99mTc-dimercaptosuccinic acid uptake studies, the first study immediately before surgery and the second one 3-6 months following surgery. The study group included 69 patients: 26 (37.7%) patients in the sealant group (BioGlue®) and 43 (62.3%) patients in the standard suture group.

Results

No statistically significant differences were noted in the baseline clinical and pathological characteristics of the studied groups. However, there were several statistically significant differences in operative variables: patients in the suture group had larger amount of blood loss (3-fold), longer ischemia time (26.6 vs. 21 minutes,) and slightly longer operation time. Patients in whom tumor bed was closed by sutures had nearly 3-fold higher parenchymal loss compared to patients managed by sealant (26.28 vs. 8.92 ml, p = 0.048).

Conclusions

The use of tissue sealant during tumor bed reconstruction is associated with reduced devascularized parenchymal mass loss and should be considered among modifiable surgical factors during NSS.

Compton imaging with 99mTc for human imaging

We have been developing a medical imaging system using a Compton camera and demonstrated the imaging ability of Compton camera for ^99mTc-DMSA accumulated in rat kidneys. In this study, we performed imaging experiments using a human body phantom to confirm its applicability to human imaging. Preliminary simulations were conducted using a digital phantom with varying activity ratios between the kidney and body trunk regions. Gamma rays (141 keV) were generated and detected by a Compton camera based on a silicon and cadmium telluride (Si/CdTe) detector. Compton images were reconstructed with the list mode median root prior expectation maximization method. The appropriate number of iterations of the condition was confirmed through simulations. The reconstructed Compton images revealed two bright points in the kidney regions. Furthermore, the numerical value calculated by integrating pixel values inside the region of interest correlated well with the activity of the kidney regions. Finally, experimental studies were conducted to ascertain whether the results of the simulation studies could be reproduced. The kidneys could be successfully visualised. In conclusion, considering that the conditions in this study agree with those of typical human bodies and imaginable experimental setup, the Si/CdTe Compton camera has a high probability of success in human imaging. In addition, our results indicate the capability of (semi-) quantitative analysis using Compton images.

Percutaneous Nephrolithotomy: Current Clinical Opinions and Anesthesiologists Perspective

Percutaneous nephrolithotomy (PCNL), a minimally invasive method for removal of renal calculi, was initially started in the 1950s but gained popularity about two decades later and has now become standard practice for management. There has been an immense improvement in technique and various guidelines have been established for treatment of renal stones. However, it has its own share of complications which can be attributed to surgical technique as well as anesthesia related complications. PubMed and Google search yielded more than 30 articles describing the different complications seen in this procedure, out of which 15 major articles were selected for writing this review. The aim of this review article is to describe the implications of the complications associated with PCNL related to the anesthesiologist. The anesthesiologist is as much responsible for the management of the patient perioperatively as the surgeon. Therefore, it is mandatory to be familiar with the various complications, some of which may be life threatening and he should be able to manage them efficiently. The paper also analyses the advantages and drawbacks of the available options in anesthesia, that is, general and regional, both of which are employed for PCNL.

In vivo quantification of renal function in mice using clinical gamma cameras

INTRODUCTION

In preclinical research, the growing number of transgenic models has led to the need for renal-function studies in mice. Many efforts have been made to develop dedicated SPECT systems for rodents, but their availability is limited due to high capital costs. The aim of this work is to demonstrate the feasibility of mouse renal imaging by using an inexpensive alternative based on clinical gamma-cameras.

METHODS

A healthy mouse was scanned 3 h after injection of 6 mCi of Dimercaptosuccinic acid (DMSA) labeled with 99mTc by using a single-head gamma-camera in conjunction with a dedicated pinhole collimator. List-mode data were binned to emulate multiple injections of 1 mCi, 0.1 mCi and 0.01 mCi of 99mTc-DMSA and 6-min ventral and dorsal planar images were acquired and SPECT imaging (60 projection images acquired over 60 min) was performed. An optimization of the protocols in terms of injected activity, time scan, renal cortex uniformity and cortex-to-pelvis contrast was carried out.

RESULTS

The appropriate protocols were an injected activity of 0.6 mCi, combined with duration of scanning of 1 min for planar and 60 min for SPECT imaging. Our results were validated through the relative quantification of renal function, which showed that both kidneys contributed equally to the total function. They showed that functional structures of the mouse kidneys can be visually distinguished as easily as in human studies.

CONCLUSIONS

Our findings showed the feasibility of conducting quantitative DMSA SPECT studies of anesthetized mice on clinical gamma cameras.

Does percutaneous nephrolithotomy and its outcomes have an impact on renal function? Quantitative analysis using SPECT-CT DMSA

To assess the functional effects of percutaneous nephrolithotomy (PCNL) and its outcomes in the operated kidney, we prospectively studied 30 consecutive cases undergoing PCNL. Kidney function was evaluated preoperatively and 3 months after surgery with serum creatinine, glomerular filtration rate (GFR), and with (99m)Tc-DMSA SPECT-CT scans to determine the differential renal function (DRF). PCNL effects in the operated kidney DRF were considered globally (DRFPLANAR, DRFSPECT) and in the region of percutaneous access (DRFACCESS). PCNL functional impact was also assessed depending on its outcomes, namely success (stone-free status) and the development of perioperative complications. PCNL has rendered 73 % of the cases completely stone free with a 33 % complication rate. After PCNL, serum creatinine and GFR did not change significantly, whereas DRFPLANAR and DRFSPECT dropped 1.2 % (p = 0.014) and 1.0 % (p = 0.041), respectively. The highest decrease was observed in DRFACCESS (1.8 %, p = 0.012). Stone-free status after PCNL did not show any impact on kidney function. Conversely, cases that suffered from a complication showed impairment in serum creatinine (0.1 mg/dL, p = 0.028), in GFR (11.1 mL/min, p = 0.036) as well as in DRFPLANAR (2.7 %, p = 0.018), DRFSPECT (2.2 %, p = 0.023) and DRFACCESS (2.7 %, p = 0.049). We conclude that PCNL has a minimal impact on global kidney function, which is mainly located in the region of percutaneous access. The advent of perioperative complications increased PCNL functional damage, whereas the stone-free status did not show any meaningful effect.

Current and potential renal applications of contrast-enhanced ultrasound

The combination of microbubble technology and complementary ultrasound techniques has resulted in the development of contrast-enhanced ultrasound (CEUS) and, although initial clinical applications largely focussed on the liver, these are now becoming more diverse. With regard to the kidney, it is a safe, well-tolerated, and reproducible technique, and in selected cases, can obviate the need for computed tomography or magnetic resonance imaging. A clear advantage is the absence of nephrotoxicity. With respect to the current and potential renal applications, it is a useful technique in the evaluation of pseudotumours, acute pyelonephritis, renal tumours, cystic lesions, vascular insults, and renal transplantation. It may also be of value for monitoring the kidney following anti-angiogenic treatment or nephron-sparing interventional techniques for renal tumours. Assessment of microvascular perfusion using time-intensity curves is also likely to have further far-reaching applications in the kidney as well as other organs.

Degree and Predictors of Functional Loss of the Operated Kidney following Nephron-Sparing Surgery: Assessment by Quantitative SPECT of 99m Tc-Dimercaptosuccinic Acid Scintigraphy

Purpose. To determine the degree and predictors of renal function loss of the operated kidney following nephron-sparing surgery (NSS). Material and methods. The study group included 113 patients with renal mass who underwent NSS at our institution. QDMSA before and 3–6 months after surgery was used for evaluation differences in renal function of each kidney. Mean change of percent uptake by the kidney was correlated with various clinical and pathological variables. Results. The overall average decrease of renal function of the operated kidney as measured by QDMSA was 10.5% ± 2.6 SER. Among the studied variables, the most important predictors of postoperative ipsilateral residual kidney function were estimated blood loss (EBL), P = 0.0003, duration of warm ischemia, P = 0.008, patient's age at surgery, P = 0.024, method used for tumor bed closure, P = 0.06, and location of the lesion, P = 0.08. Conclusions. Carful hemostasis, minimal duration of arterial clamping, and use of tissue adhesives to seal tumor bed are associated with maximal preservation of postoperative residual renal function after NSS. These variables should be considered by the operative team when planning the surgical procedure .

Evaluation of kidney repair capacity using 99mTc-DMSA in ischemia/reperfusion injury models

Quantitative (99m)Tc-DMSA renal uptake was studied in different renal ischemia/reperfusion (I/R) mice models for the assessment of renal repair capacity. Mice models of nephrectomy, uni- and bi-lateral I/R together with sham-operated mice were established. At 1h, 1d, 4d, 1, 2 and 3 wk after I/R, (99m)Tc-DMSA (27.7 ± 1.3 MBq) was injected via tail vein and after 3h post-injection, the mice were scanned for 30 min with pinhole equipped gamma camera. Higher uptake of (99m)Tc-DMSA was measured in normal kidneys of uni-lateral I/R model and nephrectomized kidney I/R model at 3 wk post-surgery. Comparing the restoration capacities of the affected kidneys of nephrectomy, uni- and bi-lateral I/R models, higher repair capacity was observed in the nephrectomized model followed by bi-lateral then uni-lateral models. The normal kidney may retard the restoration of damaged kidney in uni-lateral I/R model. Moreover, 3 wk after Uni-I/R, the size of injured kidney was significantly smaller than non-ischemic contralateral and sham operated kidneys, while nephrectomy I/R kidneys were significantly enlarged compared to all others at 3 wk post-surgery. Very strong correlation between (99m)Tc-DMSA uptake and weight of dissected kidneys in I/R models was observed. Consistent with (99m)Tc-DMSA uptake results, all histological results indicate that kidney recovery after injury is correlated with the amount of intact tubules and kidney sizes. In summary, our study showed good potentials of (99m)Tc-DMSA scan as a promising non-invasive method for evaluation of kidney restoration after I/R injuries. Interestingly, mice with Bi-I/R injury showed faster repair capacity than those with uni-I/R.

A prospective, randomized trial of management for asymptomatic lower pole calculi

PURPOSE

We determined the natural course and compared the deleterious effects in kidneys of shock wave lithotripsy, percutaneous nephrolithotomy and observation for asymptomatic lower caliceal stones.

MATERIALS AND METHODS

Between April 2007 and August 2008 patients with asymptomatic lower caliceal calculi were enrolled in the study. To assess stone status noncontrast abdominal helical computerized tomography was done 3 and 12 months after intervention. All patients were evaluated by dimercapto-succinic acid renal scintigraphy 6 weeks and 12 months after intervention.

RESULTS

A total of 94 patients were prospectively randomized to percutaneous nephrolithotomy (31), shock wave lithotripsy (31) and observation (32). Mean +/- SD followup was 19.3 +/- 5 months (range 12 to 29). In the percutaneous nephrolithotomy group all patients were stone-free at month 12. Scintigraphy revealed a scar in 1 patient (3.2%) on month 3 followup imaging. In the shock wave lithotripsy group the stone-free rate was 54.8%. Scintigraphy revealed scarring in 5 patients (16.1%). In the observation group 7 patients (18.7%) required intervention during followup. Median time to intervention was 22.5 +/- 3.7 months (range 18 to 26). One patient (3.1%) had spontaneous stone passage. Scintigraphy did not reveal scarring in any patient.

CONCLUSIONS

Stone related events were noted in more than 20% of patients with asymptomatic lower caliceal stones observed expectantly. To manage lower caliceal stones percutaneous nephrolithotomy has a significantly higher stone-free rate with less renal scarring than shock wave lithotripsy. Thus, patients with asymptomatic lower caliceal stones must be informed in detail about all management options, especially focusing on percutaneous nephrolithotomy with its outstanding outcome.

Compensatory changes in the function of the remaining kidney immediately after unilateral nephrectomy in sheep

Live kidney donation is an established form of organ donation but carries the risk of an unnecessary surgery in a normal individual for the benefit of the recipient. Despite a number of recent studies on the renal function of long-term kidney donors, little attention has been paid to the damaging effects of compensatory hyper-filtration on renal tubular cells immediately after donor nephrectomy. The present study therefore aimed to examine the immediate changes in renal function of the remaining kidney using a sheep model of unilateral nephrectomy. We used the gamma camera-based method to measure the glomerular filtration rate and the tubular excretion values after simultaneous injection of (99m)Tc-diethylene triamine pentaacetic acid and (131)I-ortho-iodohippurate tracers. Compared were the differences in the functions between the remaining left kidney immediately after clamping the right renal pedicle and the baseline values that were measured one week before unilateral nephrectomy. After radionuclide data acquisition was completed, the right kidney was removed. The mean glomerular filtration rate (GFR) increased by 52.3% from the baseline values (29.5 +/- 2.7 to 45.0 +/- 6.7 ml/min; n = 40, p < 0.001), while the mean effective renal plasma flow (ERPF) increased by 40% (225.5 +/- 27.8 to 357.8 +/- 38.94 ml/min; p < 0.001), respectively. Mean filtration fraction was increased from 0.117 to 0.127 immediately after nephrectomy (p < 0.001). We conclude that after unilateral nephrectomy the remaining kidney immediately compensates for the loss of a donated kidney by increasing glomerular filtration rate and effective renal plasma flow.

Estimation of absolute renal uptake with technetium-99m dimercaptosuccinic acid: direct comparison with the radioactivity of nephrectomy specimens

CONTEXT AND OBJECTIVE

Studies using radionuclides are the most appropriate method for estimating renal function. Dimercaptosuccinic acid chelate labeled with technetium-99m (99mTc-DMSA) is the radiopharmaceutical of choice for high-resolution imaging of the renal cortex and estimation of the functional renal mass. The aim of this study was to evaluate a simplified method for determining the absolute renal uptake (ARU) of 99mTc-DMSA prior to nephrectomy, using the radioactivity counts of nephrectomy specimens as the gold standard.

DESIGN AND SETTING

Prospective study at the Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas.

METHODS

Seventeen patients (12 females; range 22-82 years old; mean age 50.8 years old) underwent nephrectomy for various reasons. Renal scintigraphy was performed three to four hours after intravenous administration of a mean dose of 188.7 MBq (5.1 mCi) of 99mTc-DMSA, which was done six to 24 hours before surgery. The in vivo renal uptake of 99mTc-DMSA was determined using the radioactivity of the syringe before the injection (measured using a dose calibrator) and the images of the syringe and kidneys, obtained from a scintillation camera. After surgery, the reference value for renal uptake of 99mTc-DMSA was determined by measuring the radioactivity of the nephrectomy specimen using the same dose calibrator.

RESULTS

The ARU measurements were very similar to those obtained using the reference method, as determined by linear regression (r-squared = 0.96).

CONCLUSION

ARU estimation using the proposed method before nephrectomy seems to be accurate and feasible for routine use.

Functional Significance of Using Tissue Adhesive Substance in Nephron-Sparing Surgery: Assessment by Quantitative SPECT of 99m Tc-Dimercaptosuccinic Acid Scintigraphy

OBJECTIVES

To compare changes in renal function following nephron-sparing surgery (NSS) using tissue adhesive only versus NSS using standard suturing technique, as measured by quantitative SPECT of 99m Tc-dimercaptosuccinic acid uptake by the kidney (QDMSA).

MATERIALS AND METHODS

QDMSA was done before and 3-6 mo after the operation in 32 patients who underwent standard suturing technique and in 24 patients in whom tissue adhesive sealant (19 with albumin glutaraldehyde tissue adhesive [BioGlue]; 5 with CoSeal) was used to close the parenchymal defect. Individual kidney uptake was measured and retrospectively compared between the two groups.

RESULTS

Average tumor diameter was 3.4cm (range: 2.2-6) in the suture group and 3.56 (range: 1.7-6) in the tissue sealant group. In the tissue sealant group following surgery, we observed an average individual renal function loss of 11.49% compared with the suture group in whom an average individual renal function loss of 20.36% (p = 0.02) was measured by 99m Tc-DMSA.

CONCLUSIONS

The use of tissue sealant to close the parenchymal defect during NSS demonstrated a statistically significant advantage in reducing functioning renal loss as measured by the absolute uptake of QDMSA. Further clinical studies are required to establish the role of tissue sealants in NSS.

Effect of percutaneous nephrolithotripsy on renal function: assessment with quantitative SPECT of (99m)Tc-DMSA renal scintigraphy

PURPOSE

To measure the effect of PCNL on global and regional renal function using quantitative single-photon emission CT (SPECT) measurement of Tc-dimercaptosuccinic acid (DMSA) uptake by the kidneys (QDMSA).

PATIENTS AND METHODS

A series of 47 male and 41 female patients with a mean age of 47 +/- 16 years were studied by sequential QDMSA examinations before and 1.5 to 24 months after PCNL. Among the 67 patients (76%) in whom PCNL was performed using upper- or lower-pole access, the function of the affected and nonaffected poles of the treated kidney was calculated separately.

RESULTS

There was no statistically significant difference in the uptake by the treated kidneys before versus after PCNL (11.9% +/- 5% v 11.6% +/- 5%; t = 0.9; P = 0.368). The total functional volume of the treated kidney was slightly decreased, from 235 cc +/- 62 cc to 224 cc +/- 59 cc (t = 2.7; P = 0.011). The percent of the injected isotope dose per cubic centimeter of tissue of the treated kidney was not affected (0.051 +/- 0.02 v 0.053 +/- 0.02; t = 0.86; P = 0.296). Regional assessment revealed a statistically significant decrease in the functional volume at the PCNL port of entry (91 cc +/- 30 cc v 82 cc +/- 27 cc; t = 2.64; P = 0.013). Regarding the percent of the injected dose per cubic centimeter of renal tissue, no statistically significant difference was found between the area of the kidney that underwent PCNL and the untreated area of the same kidney (0.049 +/- 0.02 v 0.05 +/- 0.02; t = 0.693; P = 0.494). The function of the contralateral kidneys remained unchanged (13.4% +/- 5.2% v 13.6% +/- 4.8%; t = 0.68; P = 0.5).

CONCLUSIONS

Despite the statistically significant decrease in the functional volume of the surgically treated region, neither total percent uptake nor percent of injected dose were reduced significantly. Further studies with long-term follow-up of treated kidneys are required.

WDP, Okamoto MRY, Garcez AT, Watanabe T, Costa PLA, Buchpiguel CA. Padronização do método para cálculo da captação renal absoluta do99mTc-DMSA em cria

OBJETIVO: O trabalho teve por objetivo padronizar o método e estabelecer valores normais da captação renal absoluta do99mTc-DMSA em crianças. MATERIAIS E MÉTODOS: Vinte e duas crianças (idade de 7 meses a 10 anos; média de 4,5 anos) sem doença renal prévia foram submetidas a cintilografia renal estática com 99mTc-DMSA. Dezoito apresentavam ultra-sonografia, uretrocistografia miccional, "clearance" de creatinina e padrão visual da cintilografia renal estática normais. Quatro crianças foram excluídas por não terem completado ou por apresentarem redução do "clearance" de creatinina. A captação absoluta de DMSA (DMSA-Abs) foi calculada como a porcentagem da atividade administrada retida em cada rim após seis horas da administração do radiofármaco. RESULTADOS: Os valores de DMSA-Abs foram de 21,8% ± 3,2% para o rim direito e de 23,1% ± 3,3% para o rim esquerdo. Os valores da captação absoluta não mostraram correlação com a idade dos pacientes estudados, apesar da tendência de aumento do "clearance" de creatinina com a idade. CONCLUSÃO: A definição de valores normais da DMSA-Abs permite o emprego deste parâmetro na avaliação inicial e acompanhamento de doenças renais, principalmente em pacientes com acometimento bilateral ou com rim único (nos quais a função diferencial direita X esquerda tem valor limitado).

Megaureter visualization on Tc-99m DMSA scintigraphy

We present a patient with left-sided obstructed megaureter secondary to neuropathic bladder. He was referred for technetium-99m dimercaptosuccinic acid ((99m)Tc-DMSA) renal cortical scintigraphy to evaluate renal cortical function. Images obtained 4 hr after injection showed significant activity in the dilated left ureter. When the ureter is visualized on DMSA scan, obstructive megaureter should be considered in the differential diagnosis.

Laparoscopic partial nephrectomy with temporary arterial occlusion: description of technique and renal functional outcomes

OBJECTIVES

To report our laparoscopic partial nephrectomy experience and the impact of temporary arterial occlusion during laparoscopic partial nephrectomy on postoperative renal function. Laparoscopic partial nephrectomy is increasingly popular but remains technically challenging.

METHODS

Laparoscopic partial nephrectomy was performed in 27 patients, with arterial occlusion in 15 cases. Postoperative renal function was evaluated with serum creatinine in all patients and postoperative technetium-99m mercaptoacetyl triglycine renal scans in a subset of patients after arterial occlusion.

RESULTS

The group with arterial occlusion (n = 15) did not differ from those without arterial occlusion (n = 12) with respect to age, body mass index, American Society of Anesthesiologists score, lesion size, operative time, blood loss, or complications. In patients undergoing arterial occlusion, the mean warm ischemia time was 43 +/- 10 minutes (range 25 to 65). The preoperative and postoperative serum creatinine levels were unchanged in patients with (1.07 +/- 0.4 to 1.15 +/- 0.4 ng/dL; P = 0.24) and without (0.96 +/- 0.22 to 1.07 +/- 0.27 ng/dL; P = 0.14) arterial occlusion. The tumor size on imaging correlated with postoperative serum creatinine (r2 = 0.450, P = 0.04). Nuclear renography was performed in 9 patients (60%) after renal artery occlusion. The mean differential renal function of the operated kidney (49%) was similar to that of the contralateral kidney (51%) and was not associated with warm ischemic time or tumor size.

CONCLUSIONS

Temporary arterial occlusion during laparoscopic partial nephrectomy does not appear to affect short-term renal function adversely. We believe that this technique can be safely performed when significant bleeding or entry into the collecting system is anticipated. Additional study is warranted to identify the maximal time of warm ischemia and ways to reduce potential renal injury.

The value of quantitative 99M technetium dimercaptosuccinic acid renal scintigraphy for predicting postoperative renal insufficiency in patients undergoing nephrectomy

PURPOSE

Radical nephrectomy is a routine urological practice. However, little is known about the use of dimercapto-succinic acid (DMSA) scan to evaluate compensatory changes after surgery and its ability to identify patient at risk for postoperative chronic renal failure or insufficiency. We predicted remaining kidney function using DMSA scan and serum creatinine.

MATERIALS AND METHODS

A total of 42 patients were enrolled in the study. All underwent DMSA scan before surgery and in 38 DMSA scan was done after unilateral nephrectomy. Serum creatinine was determined before and 1 year after surgery. The Student t test was used to determine statistical significance. Spearman rank core analysis was used to evaluate the association of calculated creatinine clearance time after surgery and renal absolute uptake before surgery. We performed 1-way ANOVA comparison of the means to determine the influence of age distribution on kidney hypertrophy and the increase in kidney uptake.

RESULTS

Average patient age was 61.5 years. Baseline mean creatinine clearance time was 71.5 ml. per minute, which decreased to 58.6 ml. per minute after nephrectomy (p <0.0001). Before surgery DMSA scan of the remaining kidney demonstrated an absolute uptake of 4.2% higher than that in the resected kidney (13.5% versus 9.35%, p = 0.0008). After nephrectomy the remaining kidney had an average increase of 3.9% of mean absolute uptake (17.7% versus 13.8%, p = 0.0001). Spearman rank core analysis demonstrated an association of higher preoperative absolute uptake in the remaining kidney with postoperatively high creatinine clearance time (r = 0.458, p = 0.003). Furthermore, 75% of patients with postoperative creatinine clearance time less than 40 ml. per minute presented with a preoperative absolute uptake of lower than 11% in the remaining kidney. In contrast, 75% of those with a postoperative creatinine clearance time of higher than 40 ml. per minute had a preoperative absolute uptake of higher than 11%.

CONCLUSIONS

A preoperative absolute uptake of lower than 11% in the remaining kidney was a significant risk factor for postoperative chronic renal insufficiency.

Impact of arterial occlusion during partial nephrectomy on residual renal function: an evaluation with (99m)technetium-dimercaptosuccinic acid scintigraphy

BACKGROUND

Partial nephrectomy (PNx) has been performed with temporary renal arterial occlusion and in situ renal hypothermia (conventional PNx). However, the impact of temporary renal arterial occlusion on residual renal function has not been well assessed. To address this question, we performed renal scintigraphy with (99m)technetium-dimercaptosuccinic acid (DMSA) for the quantitative measurement of postoperative residual renal function after conventional PNx and partial nephrectomy without arterial occlusion (non-clamping PNx).

METHODS

Thirty-four patients underwent postoperative DMSA scintigraphy after PNx for renal cell carcinoma. No obvious difference in preoperative renal function between the diseased kidney and the contralateral kidney was found in any of the patients. Of these patients, 24 underwent conventional PNx, and 10 underwent non-clamping PNx. Residual renal function was evaluated using the relative DMSA uptake of the operated kidney.

RESULTS

The relative DMSA uptake of the operated kidney was 39.9 +/- 7.3% (25.1-58.8) after conventional PNx compared to 34.8 +/- 8.9% (13.5-45.5) after non-clamping PNx. This difference was not statistically significant (P = 0.15). Total ischemic time during conventional PNx had no adverse influence on the residual renal function. In the analysis of the other determinant factors influencing residual renal function, tumor size was the only significant factor that inversely correlated with the relative DMSA uptake.

CONCLUSION

Our results showed that arterial clamping during PNx has no negative impact on the functional residual capacity as long as insitu renal hypothermia is adequately performed.

The utility of (99m)Tc-DMSA and Tc(99m)-EC scintigraphy for early diagnosis of ifosfamide induced nephrotoxicity

A serious undesired effect of certain cytostatics is their nephrotoxicity. In this study, we investigated the toxic effects of ifosfamide and cisplatin by clinical and biochemical parameters in relation to (99m)Tc-dimercaptosuccinic acid ((99m)Tc-DMSA) and Tc(99m)N, N-ethylenedicysteine (EC) renal scintigraphy. The indicators were urinary beta2-microglobulin levels, tubular resorption of phosphate, urinary protein and glucose excretion, glomerular filtration rate, urinary pH and osmolarity. Thirteen paediatric patients (seven boys and six girls), aged 2-16 years, were investigated. Five patients received only cisplatin, six patients were treated with ifosfamide and cisplatin and two with ifosfamide and carboplatin for various malignancies. All except three patients had normal DMSA uptake (median, 19; range, 16-29%) prior to chemotherapy. The reduction in DMSA uptake was unilateral due to tumour invasion in those three patients. Following chemotherapy, DMSA uptake showed reduction in five patients with or without clinical nephrotoxicity. The observed pattern was decreased renal uptake and elevated bladder activity. Three patients with decreased DMSA uptake had normal tubular maximum phosphate reabsorption, which suggested subclinical injury. Decrease in DMSA uptake and tubular phosphate reabsorption (TPR) was detected simultaneously in two patients. No abnormalities were seen on Tc(99m)-EC scintigraphy to suggest nephrotoxicity in our investigation. However, Tc(99m)-EC clearly demonstrated a reduction in split renal function in children with tumour invasion. In summary, we found that ifosfamide induced tubular injury can be detected with (99m)Tc-DMSA scintigraphy before chemotherapy associated nephrotoxicity is observed by laboratory measurements. Our results also imply that, although a tubular agent, renal scintigraphy performed with Tc(99m)-EC is not able to detect subclinical injury or predict the outcome during treatment.

Inter-observer reproducibility of relative 99Tcm-DMSA uptake

99Tcm-DMSA planar images of 49 randomly selected patients (10 adults, 39 children) were sent to 15 physicians at various centres in Belgium. They were asked to calculate, using their own routine program, the relative uptake (expressed as a percentage) of each kidney. The data were sent on disks formatted so that they could be read by all participants, using their own computer systems. For each scan, the inter-observer variability was expressed using the maximum difference and the standard deviation of left renal uptake. Left renal uptake measured by the 15 observers in the 49 patients was 29.0-72.0% (mean +/- s = 49.8 +/- 6.4%). The maximum differences in left renal uptake ranged between 1.7% and 12.0% (4.5 +/- 2.6%); however, the maximum difference did not exceed 8% in about 90% of the patients. The standard deviations of the individual left renal uptake were between 0.6 and 3.9 (1.3 +/- 0.8). The standard deviations were significantly higher in adults (mean standard deviation = 2.05) than in children (mean standard deviation = 1.12) (P < 0.001); this was probably related to the high background observed in three adults with severe renal impairment. Indeed there was a significant correlation (P < 0.001) between the standard deviation and both the signal-to-noise ratio and the degree of asymmetry between the right and left kidneys. The differences between right and left kidney uptake were systematically lower for some observers, suggesting an influence of the calculation programs.

Prenatal diagnosis of hydronephrosis: impact on renal function and its recovery after pyeloplasty

PURPOSE

We reviewed our experience with corrective surgery for congenital ureteropelvic junction obstruction to assess the impact of mode of presentation on renal function at diagnosis and on postoperative recovery of function.

MATERIALS AND METHODS

We reviewed the records of consecutive children who underwent pyeloplasty or nephrectomy for ureteropelvic junction obstruction during a 5-year period at our hospitals. Patients were divided into those with and without a prenatal diagnosis of hydronephrosis. In each group we compared preoperative and postoperative differential renal function, as measured by nuclear renography.

RESULTS

We identified 89 patients, of whom 51 (57%) and 38 (43%) presented with prenatal and postnatal hydronephrosis, respectively. Kidneys in which hydronephrosis was diagnosed prenatally had better average differential renal function than those in which the condition was detected postnatally (45 versus 37%). This difference was even more significant in kidneys with less than 40% initial function (31 versus 21%). Presentation with a palpable mass was associated with worst renal function (mean 23%). Postoperatively renal function did not recover significantly in either group. There was a minimal increase in postoperative differential renal function in the subgroup of patients in whom initial differential renal function was less than 40%, although there was no significant difference in the 2 groups (6.5 versus 4.8%).

CONCLUSIONS

The early diagnosis of hydronephrosis provided by prenatal ultrasonography is associated with less obstructive nephropathy. Prolonged followup is necessary for studies of the natural history of hydronephrosis because relevant obstruction manifests clinically years later. Despite successful pyeloplasty function recovery is minimal in kidneys with poor function and hydronephrosis diagnosed prenatally. Our findings do not support previous observations that poor function markedly improves after obstruction is relieved.

Comparison of whole-body thallium imaging with transcutaneous PO2 in studying regional blood supply in patients with peripheral arterial occlusive disease

Quantitatively estimating functional reserve of blood supply to the legs in patients with peripheral arterial occlusive disease (PAOD) remains a clinical issue. This study was designed to investigate the regional blood supply to the legs in PAOD patients during exercise by use of thallium 201 (201Tl) whole-body imaging in comparison with transcutaneous PO2 (tcPO2) measurement. Thirty-three patients with PAOD and 10 subjects without PAOD (control) performed an incremental cycle ergometry (CE), while tcPO2 was continuously registered on the involved calf. In the last minute of exercise, 2 mCi of 201Tl was injected intravenously and the 201Tl whole-body images were taken immediately (stress) and four hours (redistribution) following stress with a dual-head camera system. Regional blood supply (RBS) (%) was calculated from the geometric mean counts of the region of interest divided by the total counts of the whole body. The performance of PAOD patients was reduced in doing CE, and tcPO2 fell distinctly in PAOD patients (from 51 to 19 mmHg) whereas it increased in controls (from 57 to 67 mmHg). The RBS in PAOD patients was obviously reduced in comparison with that of controls. While in controls the RBS of the calf (3.1%) at stress did not differ from that at redistribution (3.4%), in PAOD patients the redistribution RBS (2.8%) increased as compared with that of stress (1.5%). There was a hyperbolic relationship between stress RBS of the calf and the velocity of tcPO2 fall in PAOD patients during exercise test (velocity of tcPO2 fall = -0.032 + 0.39/RBS, r2 = 0.54, P < 0.05). In conclusion, the RBS determined by 201Tl whole-body imaging is comparable to the tcPO2 measurement in differentiating patients with PAOD from subjects without PAOD during exercise. Regional 201Tl uptake reflects regional blood supply in PAOD patients. There is a hyperbolic relationship between the RBS derived from 201Tl whole-body imaging and tcPO2 in PAOD patients during exercise, implying that in a critical ischemia the lower the RBS is, the more steeply the tcPO2 decreases.

Potential 99mTc radiopharmaceuticals for renal imaging: tris(N-substituted-3-hydroxy-2-methyl-4-pyridinonato)technetium(IV) cations

A series of monocationic complexes of N-substituted-3-hydroxy-2-methyl-4-pyridinones labeled with technetium(IV)-99m have been evaluated in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the ring nitrogen atom: ethyl, i-propyl, i-butyl, benzyl, phenyl, p-methoxyphenyl, 3-butoxypropyl and cyclohexyl. Biodistribution studies of the 99mTc complexes have been carried out in rabbits and mice. High kidney uptake and retention of the radionuclide has been shown in rabbits and mice with the cationic complexes of 3-hydroxy-1-(p-methoxyphenyl)-2-methyl-4-pyridinone and 1-(cyclohexyl)-3-hydroxy-2-methyl-4-pyridinone. These 99mTcL3+ compounds appear to be morphologic renal agents.

Cysteine, a chelating moiety for synthesis of technetium-99m radiopharmaceuticals--Part IV. Benzyl cysteine and derivatives

To explore the possibility of utilizing cysteine derivatives for technetium-99m radiopharmaceutical preparation with clinical potential, we synthesized two benzyl substituted cysteine compounds, namely, S-benzyl cysteine 1 and cysteine benzyl ester 3. It was expected, from our previous studies on benzoyl cysteines, that the above two ligands after chelation with 99mTc would be excreted by the hepatobiliary pathway. Although for 99mTc-3 the above expectation was realized, 99mTc-1 behaved in a most unexpected way by affixing itself with kidney and selecting the renal tubular secretory pathway for its excretion. It is anticipated that the affinity of 99mTc-1 for kidney is due to its interaction with the kidney sulphhydryl group and it also formed an adduct with other sulphydryl containing compounds like thiophenol. In terms of the kidney-to-background ratio, 99mTc-1 showed some superiority over other kidney structure agents, like 99mTc-dimercaptosuccinic acid and 99mTc-glucoheptanoic acid and, therefore, the chelate (99mTc-1) may have the potential to replace the above two radiopharmaceuticals in clinical use.

Compensatory renal response after unilateral partial and whole volume high-dose irradiation of the human kidney

Renal function was prospectively analysed in 26 patients treated with radiotherapy for various types of malignancies. In patients with gastric non-Hodgkin's lymphoma stage I-II (gNHL, n = 5), the 99mTc-diethylene-triamine-penta-acetic acid (99mTc-DTPA) renal uptake and the relative 99mTc-dimercapto-succinyl acid (99mTc-DMSA) accumulation decreased gradually and concomitantly in the high-dose, whole-volume irradiated left kidney (40 Gy/5, 5 weeks), down to 25 +/- 10% (mean +/- 1 S.E.M.) and 31 +/- 11%, respectively, after 6-9 years. The absolute 99mTc-DMSA uptake in the left kidney declined down to 33 +/- 12% whereas in the low-dose, whole-volume irradiated right kidney (12-13 Gy/3 weeks) it increased up to 187 +/- 11%. When considering renal volume changes with single photon emission computed tomography, the left kidney in the gNHL patients was reduced to 30 +/- 13%, with, surprisingly, a contralateral enlargement up to only 119 +/- 7% (P < 0.05). The overall renal function in this group of patients, as assessed by creatinine clearance and by [125I]iothalamate/[131I]hippuran clearance was reduced to 48-68%. In the Hodgkin's disease patients (HD, n = 7) given 40 Gy in 4 weeks to 30-50% of the left kidney, the 99mTc-DTPA filtration and the relative 99mTc-DMSA uptake in the left kidney was reduced to 75 +/- 4% and 81 +/- 3%, respectively. The absolute 99mTc-DMSA changes were 78 +/- 10% and 135 +/- 13%, respectively. No significant renal functional alterations were observed in patients with either ovarian carcinoma (n = 7) or seminoma (n = 7). These data suggest a significant, compensatory response of the non-irradiated or low-dose irradiated kidney which, however, appears to be incomplete after contralateral, whole-volume, high-dose irradiation. Such compensatory response might be overestimated when considering only relative or absolute changes in radioactivity uptake.

Effect of extracorporeal piezoelectric lithotripsy shock waves on renal function measured by Tc-99m-DMSA using SPECT

Extracorporeal shock-wave lithotripsy has altered the therapeutic approach to urinary stone disease. Recently, a method was developed in which shock-wave generation is obtained piezoelectrically. To evaluate the effect of extracorporeal piezoelectric lithotripsy (EPL) on renal function, 20 patients were studied prior to and after EPL of renal calculi. Renal cortical function was evaluated by using a previously described and validated quantitative single photon emission computerized tomography (SPECT) method to measure individual absolute uptake of technetium-99m dimercaptosuccinic acid (Tc-99m-DMSA). Twenty kidneys were treated, and the 19 contralateral kidneys were without stone disease (1 patient had a single kidney). The absolute kidney uptake of Tc-DMSA in the normal kidneys was 21.4% +/- 6.2% before and 22.2% +/- 6.4% after EPL. For the treated kidneys the absolute update was 16.8% +/- 5.3% and 16.8% +/- 4.7% before and after, respectively. There was no statistical significant difference between pre- and post-treatment values. The absolute kidney uptake was significantly lower (p less than 0.01) in the treated than in the normal kidneys. This study indicates that the EPL procedure did not cause any damage to cortical function detectable by the DMSA uptake.

Single photon emission computed tomography with Tc-99m-dimercaptosuccinic acid in patients with upper urinary tract infection and/or vesicoureteral reflux

By means of Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy, an established method for assessing renal cortical damage, we evaluated the pick-up rate for renal defects (scars) by single photon computed tomography (SPECT) and planar images of 10 normal volunteers, and 58 patients (70 scintigrams) with upper urinary tract infections, most of whom had a history of vesicoureteral reflux (VUR). The positive study rate for renal defects depended on the severity of VUR. The overall positive rates for renal cortical defects obtained by DMSA SPECT imaging and DMSA planar imaging were 60% and 43%, respectively, and the difference between these was significant (p less than 0.005). The mean absolute individual renal uptake (/injected dose) at 2 hours post-injection was decreased in kidneys with defects detected by SPECT alone. The positive study rate for intravenous urography (IVU) depended on the grade of VUR and was 15% overall. DMSA SPECT imaging detects renal cortical defects at greater frequency than previously achieved.

Late tissue reactions after single-fraction sequential half-body irradiation (HBI) in patients with non-Hodgkin's lymphomas

Lung and hepatic toxicities constituted the main radiation-related damage after half-body irradiation (HBI) used as the treatment for patients with non-Hodgkin's lymphomas (NHL). Liver damage was mostly transient after a single dose of 8 Gy and could be well monitored by serum enzyme levels. A dose-response relationship could be shown for lung damage in the single dose range of 6.25-9.25 Gy, but the relationship did not reach statistical significance. A significant dose-rate effect could be shown. Mediastinal involvement by lymphoma seemed to increase the risk of pneumonitis. In a radical setting half-body irradiation is recommended to be used at a low dose-rate or as a multifraction irradiation in order to reduce the risk of liver and lung toxicities.

High resolution single photon emission computerized tomography (SPECT) 99mtechnetium-dimercapto-succinic acid renal imaging: a state of the art technique

The 99mtechnetium-dimercapto-succinic acid renal scan has become the gold standard for evaluating renal parenchymal pathology. The traditional pinhole technique provides 2-dimensional imaging. Recent application of high resolution single photon emission computerized tomography (SPECT) has provided the means to obtain even greater cortical detail. With 360-degree imaging and computer reconstruction, SPECT provides coronal, sagittal and transaxial imaging. We prospectively compared the SPECT and pinhole techniques in 33 patients (65 renal units) ranging in age from 2.5 months to 18 years. Both scans were obtained in all patients. All scans were reviewed by an independent interpreter. Using SPECT imaging, diagnostic information was enhanced in 46 of the 65 kidneys (71%). Of the 24 kidneys that appeared "normal" by pinhole imaging 15 (63%) had defects on SPECT imaging. High resolution SPECT imaging improves the ability to identify cortical defects and visualize asymmetry of cortical thickness compared to standard pinhole imaging.

A kinetic model for 99mTc-DMSA in the rat

A pharmacokinetic model was developed for the renal imaging agent 99mTc-DMSA in anesthetized rats, which incorporated data from serial measurements of blood and urine simultaneously with dynamic images obtained over an 8-h period. Animals which received a 10 mg/kg dose of unlabeled DMSA immediately before 99mTc-DMSA injection had a significantly reduced kidney accumulation and greater urinary elimination of 99mTc than animals which received the radiopharmaceutical alone. The kidney clearance was also significantly lower in rats receiving unlabeled DMSA, but no significant difference was determined between the urine clearance estimates of the two animal groups. Because the increase in the amount eliminated in the urine was not coupled with a significant change in urine clearance, it would appear that unlabeled DMSA saturated the kidney uptake mechanism(s) of 99mTc-DMSA without modifying the urinary clearance process. This interpretation is consistent with the hypothesis that renal handling of 99mTc-DMSA is governed by both glomerular filtration and peritubular capillary uptake. The simultaneous acquisition of blood, urine and non invasive image data allows for a comprehensive and informative model of the physiological disposition of 99mTc-DMSA.

Renal parenchymal damage on DMSA-scintigraphy in pelviureteric obstruction

During a 1.5 year period 21 children were investigated with 99-m-technetium dimercaptosuccinic acid (DMSA) before operation for hydronephrosis due to pelviureteric obstruction. The age at investigation was 0.2-11.5 years. Fourty-two kidneys were examined. Hydronephrosis existed on the right side in 8 cases, left side in 9 and bilateral in 4 cases. Seventeen kidneys had no obstruction. The scintigraphy was interpreted as normal in 19 kidneys. Decreased isotope uptake was found in 23 kidneys and localized to the upper pole area in 19 kidneys, middle-lateral part in 7, lower pole area in 15 and the middle-medial part in 12 kidneys. There were no predominance for any part of the kidney to be affected by parenchymal damage. In 8 children investigated before the age of 1 year, 4 of 10 hydronephrotic kidneys revealed normal DMSA scintigram. DMSA scintigraphy delineates functioning renal parenchyma. DMSA scintigraphy delineates functioning renal parenchyma. It can be recommended as a routine method for evaluation of the renal parenchyma before surgery and for follow up studies in all ages of childhood.

Reflux uropathy

Although much remains to be learned, most pediatric nephrologists and urologists are now in comfortable agreement with the following assumptions: (1) Most reflux (primary reflux) is due to a congenital anatomic abnormality of the bladder trigone. (2) In many instances this anomaly improves with growth and development of the child so that the reflux may cease spontaneously. In low-grade (I-II) reflux with undilated ureters, approximately 75 to 85 per cent will stop refluxing. In higher grades (III-V) with dilated ureters, the cessation rate is in the range of only 25-30 per cent. (3) Although radiologic grading is helpful in predicting the likelihood of spontaneous cessation, it is possible to improve that predictability by cystoscopic evaluation of the size, configuration, and position of the ureteral orifice plus the length of the submucosal tunnel. (4) Reflux in combination with bacteriuria can and does lead to renal scarring. (5) Renal scarring probably does not occur in patients with primary reflux and normal voiding pressures in the absence of bacteriuria. (6) Renal growth may proceed normally despite sterile reflux. (7) A few refluxing patients, perhaps 10 per cent, will have bacteriuria despite continuous antimicrobials, and these "breakthrough" infections may cause renal scars. (8) Other patients prove either unwilling or unable to comply with continuous medications and are also vulnerable to scars. (9) A successful antireflux operation may not change the recurrence rate of urinary tract infections per se, but it almost eliminates the likelihood of pyelonephritic episodes and the necessity for further continuous antibiotics. Unfortunately, in patients with intermediate grades of reflux, it is not presently known whether an early surgical correction might be more effective in allowing normal renal growth, in avoiding renal scars, and in preventing eventual hypertension, which is present as a late complication in almost 20 per cent of the patients. The data to answer this important question should ultimately be forthcoming from the current International Collaborative Reflux Study.

Measurement of relative renal function. A comparison of methods and assessment of reproducibility

A good correlation was found between relative uptake of 99Tcm dimercaptosuccinic acid (DMSA) and relative 131I orthoiodohippuric acid clearance in a group of 100 consecutive patients without evidence of renal failure. In the majority, attenuation correction was found to make no significant difference to relative function measurement. Those in whom it did could be readily identified by inspection of the posterior DMSA images at the time of examination. Two hundred patients were reviewed in whom serial studies had been performed over the previous 5 years. Differences in relative function greater than 5% indicated a high probability that a real change in renal function had occurred. We conclude that whilst renography and DMSA scintigraphy yield complementary information, relative function (L/L + R) can be measured equally well by either method, and the results are sufficiently reproducible to be clinically useful.

Evaluation of renal parenchyma in children by DMSA scintigraphy, X-ray computed tomography and intravenous urography

The demonstration of diminished or scarred renal parenchyma in children is often the decisive factor in determining the future management of children with urinary tract malformations. Renal scintigraphy using technetium 99m-labelled dimercaptosuccinic acid (DMSA), computed tomography (CT) and intravenous urography (IU) were used to evaluate the renal parenchyma prior to ureter re-implantation in a series of 13 children. Their ages ranged from 5 months to 3 years 8 months. The indication for operation was ureteric reflux in 8 children and distal ureteric stenosis in 5. CT was performed on a Toshiba TCT-80 scanner. Renal scintigraphy was performed 3 hours after intravenous injection of DMSA. Compared with IU, DMSA imaging gave more information about the renal parenchyma in 6 children, gave equal information in 6 and less in 1. Compared with CT, DMSA imaging gave more information in 2 children, was equally informative in 8 and less so in 3. Accordingly, DMSA imaging was judged to be more sensitive than IU and as sensitive as CT. DMSA imaging can be used both for the initial evaluation and for follow-up assessment of renal parenchymal damage.

Imaging techniques in the evaluation of pediatric hypertension

Moderate or severe hypertension occurs in a small percentage of hypertensive children, but it is within this group that the surgically correctable causes of hypertension are found. Since cure rates up to 90% have been reported, it is important to diagnose a secondary cause of hypertension. Excretory urography is recommended to screen for renovascular hypertension and renal parenchymal disease. Renal scintigraphy can be substituted for the urogram, but the anatomical resolution is poorer. If renovascular hypertension is suggested by abnormal results of screening examination, arteriography should be part of the evaluation. Ultrasonography is reserved primarily for evaluating neonatal hypertension which most frequently is related to thrombosis. If this diagnosis is documented, renal function should be assessed with radionuclide techniques. If a hormonally active tumor is suspected, evaluation of the adrenals and retroperitoneum is accomplished best by CT.

99mTc-DTPA and 99mTc-DMSA renal gamma imaging in the surveillance of patients with conduit urinary diversion

We studied renal anatomy and function using 99mTc-2-3 dimercaptosuccinic acid (DMSA) and 99mTc-diethylenetriaminepentaacetic acid (DTPA) in 27 patients with conduit urinary diversion. In this condition, free ureteral reflux is often associated with bacteriuria, and these factors are thought to precipitate progressive renal deterioration. Gamma-camera images provided valuable information concerning the structure of the renal parenchyma, the function of individual kidneys and possible ureteral obstruction, thus helping us to decide whether or not to instigate further treatment. The information gained using renal gamma imaging with 99mTc-DTPA and 99mTc-DMSA was complementary and partly overlapping. We preferred the use of 99mTc-DTPA because of its ability to visualise the ureters and the region of ureteroconduit anastomosis. Using diuretic medication, we were able to differentiate true ureteral obstruction from atony in 9 patients using 99mTc-DTPA.

Renal accumulation of 99mTc-DMSA in the artificially perfused isolated rat kidney

In order to investigate aspects of the renal handling of 99mTc-DMSA, 68 isolated rat kidneys were artificially perfused. The experimental groups were: Group 1 (no. = 32)-oxygenated filtering kidneys; Group 2 (no. = 29)-oxygenated non-filtering kidneys; Group 3 (no. = 7)-anaerobic non-filtering kidneys. We conclude that the 99mTc-DMSA complex is strongly bound to albumin, is not filtered and is removed from perfusion fluid through the renal peritubular capillary route and that this occurs by an active process which depends upon aerobic metabolism. This process has a high capacity and is not inhibited by probenecid.