Renal nuclear medicine

Evaluation of Split Renal Function for Children with Kidney Diseases by Renal and Vascular Color Ultrasonography

Renal dynamic imaging and radionuclide renography use radioactivity to evaluate split renal function. We aimed to investigate the use of renal vascular color Doppler ultrasonography for evaluation of split renal function in children. Thirty-five children with unilateral kidney diseases were enrolled. For patients with unilateral renal tumor, peak systolic velocity (V_max = 113.04 ± 13.59 cm/s) and resistance index (RI = 0.73 ± 0.02) were higher on abnormal compared with normal sides (V_max = 86.03 ± 6.49 cm/s, RI = 0.62 ± 0.01), and blood perfusion was good, indicating compensatory enhancement in split renal function. For unilateral renal cyst, V_max (58.20 ± 7.38 cm/s) was lower on the abnormal compared with the normal (87.71 ± 14.83 cm/s) size, and perfusion was poor. For unilateral hydronephrosis and renal atrophy, the parameters were similar to those of renal cyst, suggesting a weakening of renal function. For unilateral renal agenesis, V_max (106.07 ± 13.07 cm/s) and RI (0.71 ± 0.05) were higher, and perfusion was good. Renal vascular color Doppler ultrasonography was superior in the evaluation of split renal function in children, without being invasive or radioactive.

Clinical reappraisal and state of the art of nephropexy

The diffusion of minimally invasive techniques for renal surgery has prompted a renewed interest in nephropexy which is indicated to prevent nephroptosis in symptomatic patients and to mobilize the upper ureter downward in order to bridge a ureteral defect. Recent publications have been reviewed to present the state of the art of the diagnosis and management of these two challenging conditions and to try to foresee the next steps. The evaluation of patients with mobile kidney can be made relying on diagnostic criteria such as ultrasound with color Doppler and measurement of resistive index, conventional upright X-ray frames after a supine uro-computerized tomography scan and both static and dynamic nuclear medicine scans, always with evaluation in the sitting or erect position. Laparoscopic nephropexy emerges as the current treatment option combining both objectively controlled repositioning of the kidney and resolution of symptoms with minimal invasiveness, low morbidity, and short hospital stay. The use of robotics is presently limited by its higher cost, but may increase in the future. Downward renal mobilization and nephropexy is a safe and versatile technique which has been adopted as a unique strategy or more often in combination with other surgical maneuvers in order to cope with complex ureteral reconstruction.

Kidney transplantation: structural and functional evaluation using MR Nephro-Urography

End-stage-renal disease (ESRD) is a major health issue in the United States, and the Medicare costs of ESRD totaled nearly USD 21 billion in 2005. Renal transplantation has emerged as the treatment of choice in this patient population, providing improved quality of life and lower healthcare costs compared with other treatment options. Imaging evaluation of a graft kidney plays a critical role in the postoperative care of the renal transplant patient. In the past, diagnostic evaluation of the transplant kidney has depended upon a combination of ultrasonography, computed tomography, MRI, and biopsy, used in conjunction with the patient's clinical presentation. However, new and developing advances in MR technology has lead to the development of MR Nephro-Urography (MRNU), which provides both anatomic and functional evaluation of the kidney in a single examination. It is expected that the increasing use of MRNU will have a significant impact on the management of renal transplant patients. This review describes MRNU methodology, examines known posttransplant complications, and highlights the utility of MRNU as a comprehensive imaging examination to diagnose both surgical and medical complications of the transplant kidney.

[Common errors in diagnosis and management of urinary tract infections--microbiological aspects]

INTRODUCTION

Urinary tract infections (UTI) are among the most common infectious diseases affecting all age groups, from infants to the elderly. The majority of these infections occur in otherwise healthy individuals who present with symptoms of acute uncomplicated bacterial cystitis or pyelonephritis. Certain patient populations with complicated conditions are at increased risk for acquiring infection or failing therapy. Forty to 50% of adult women have a history of at least one urinary tract infection.

DIAGNOSIS AND CLASSIFICATION OF UTI

Although there are general guidelines concerning diagnosis and classification of urinary tract infections, there are wide variations in clinical practice. There are both errors which are frequently committed and mysteries that are still unsolved. Active management is important because under some circumstances urinary tract infections may cause permanent renal scarring. Imaging procedures are a cornerstone for critical evaluation of urinary tract infections, but avoidance of investigative routines will allow a marked saving in terms of costs and in terms of unnecessary radation and psychological stress to the patient.

Evaluation of the use of technetium Tc 99m diethylenetriamine pentaacetic acid and technetium Tc 99m dimercaptosuccinic acid for scintigraphic imaging of the kidneys in green iguanas (Iguana iguana)

OBJECTIVE

To evaluate the use of scintigraphy involving technetium Tc 99m diethylenetriamine pentaacetic acid ((99m)Tc-DTPA) or technetium Tc 99m dimercaptosuccinic acid ((99m)Tc-DMSA) for the determination of kidney morphology and function in green iguanas (Iguana iguana).

ANIMALS

10 healthy iguanas weighing >1.6 kg.

PROCEDURE

Renal scintigraphy was performed by use of (99m)Tc-DTPA in 6 of the iguanas and by use of (99m)Tc-DMSA in all 10 iguanas. After the injection of (99m)Tc-DMSA, scans were performed for each iguana at intervals during a 20-hour period. Renal biopsies were performed in all 10 iguanas after the final scintigraphic evaluation.

RESULTS

In iguanas, the use of (99m)Tc-DTPA for renal scintigraphy was nondiagnostic because of serum protein binding and poor renal uptake of the isotope; mean +/- SD (99m)Tc-DTPA bound to serum proteins was 48.9 +/- 9.9%. Renal uptake of (99m)Tc-DMSA produced distinct visualization of both kidneys. Renal uptake and soft tissue clearance of (99m)Tc-DMSA increased over the 20-hour imaging period; mean +/- SD renal uptake of (99m)Tc-DMSA was 11.31 +/- 3.06% at 20 hours. In each of the 10 iguanas, ultrasonographic and histologic examinations of biopsy specimens from both kidneys revealed no abnormalities.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that the kidneys of iguanas can be evaluated scintigraphically by use of (99m)Tc-DMSA; this technique may be potentially useful for the diagnosis of renal failure in iguanas.

Renal imaging with ultrasound contrast: current status

The application of UCAs to the kidney is still in its infancy; however, there are several areas of great promise. UCAs may replace CT in complex renal cyst evaluation and follow-up, eliminating the need for costly CT scans with their attendant potential contrast nephrotoxicity. This approach may decrease patient and physician uncertainty and improve diagnostic confidence. The use of UCAs is likely to be clinically useful in the evaluation of the indeterminate small renal mass on CT or MR imaging. Another probable useful application will be in renal artery stenosis. Routine application of UCAs may increase the percentage of diagnostic examinations, increase diagnostic confidence, and decrease examination times. It also will likely become the first line of evaluation in pyelonephritis, and be useful in immediate assessment of residual tumor after radiofrequency ablation. Of course, substantial additional work needs to be performed in large groups of patients to prove this currently optimistic outlook.

Quality of dynamic radionuclide renal imaging: multicentre evaluation using a functional renal phantom

The aim of this study was to evaluate the quality of dynamic radionuclide renal imaging in Finland. Nineteen nuclear medicine departments participated. A functional renal phantom was imaged and interpreted as a patient-like study. Reconstruction and printouts were performed according to the clinical routine of each laboratory. Three nuclear medicine specialists anonymously evaluated the quality of the image sets. The visual scores of the experts were ranked from one to five. In addition, several numerical time-activity parameters were calculated and compared between the laboratories. The average visual scores of the experts for the image sets were 3.2+/-0.5 (range 2.4-4.2). Only two laboratories received a score value of 4 or higher. The average error for the time to reach maximum activity (T(max)) ranged from -29 to +18% and for the washout time to reach half activity from maximum activity (T(1/2)) ranged from -43 to +66%. These results suggest that the difference in calculated parameters between laboratories is most probably due to variations in study protocols and analysis programmes. The need for external quality assurance and quality improvement in nuclear renal imaging is evident and is recommended for regular use.

Retroperitoneal laparoscopic nephropexy

Laparoscopic nephropexy is a suitable and clinically established procedure for the treatment of symptomatic nephroptosis. The availability of a minimally invasive therapy can facilitate decisions regarding the indication after careful selection of patients.

Evaluation of effective renal plasma flow with I-127 ortho-iodohippurate and I-123 ortho-iodohippurate in rabbits

RATIONALE AND OBJECTIVES

Radiolabeled ortho-iodohippurate is commonly employed for evaluating effective renal plasma flow (ERPF) by means of either in vivo scintigraphy and/or plasma clearance curves. A new method has recently been developed for measuring levels of stable iodine (iodine-127) in biologic samples, based on the detection of x-ray fluorescence photons. In this study, the authors assessed the potential of the new system to evaluate ERPF by using an iodinated contrast medium with adequate glomerular filtration and tubular secretion properties.

MATERIALS AND METHODS

A commercial system was used to evaluate ERPF after intravenous injection of stable I-127 ortho-iodohippurate. The results were compared with the clearance values of I-123 ortho-iodohippurate, considered the reference standard. Seven rabbits under general anesthesia were given intravenous injections of I-123 ortho-iodohippurate and I-127 ortho-iodohippurate. The corresponding plasma curves were evaluated from 4 to 60 minutes to calculate ERPF as the dose/integral of plasma curve.

RESULTS

The initial distribution volumes of I-123 ortho-iodohippurate (149.4 mL/kg +/- 12.1) and I-127 ortho-iodohippurate (148.8 mL/kg +/- 11.8) were virtually superimposable, thus confirming the chemical identity of the two compounds. The plasma clearance values for I-127 ortho-iodohippurate (11.15 mL/min kg(-1) +/- 1.44) were slightly (not significantly) higher than those for I-123 ortho-iodohippurate (10.49 mL/min kg(-1) +/- 1.41), perhaps because of a relative "mass" load effect of the iodinated medium.

CONCLUSION

The results obtained in this study demonstrate the feasibility of the new system for evaluating ERPF, provided that a compound with adequate glomerular filtration and tubular secretion properties is employed.

The true clinical significance of renography in nephro-urology

Isotopic renography is a non-invasive technique used routinely by the clinician to provide information about kidney structure and function. Whilst there is no doubt of its value in the accurate measurement of glomerular filtration rate and in the detection of parenchymal abnormalities, its role in the diagnosis of renovascular disease (especially in patients with renal insufficiency), the exclusion of obstruction and the evaluation of the patient with either acute renal failure or renal transplant dysfunction remains unproven. In part, this reflects a failure to standardise protocols and rigorously evaluate diagnostic techniques. Recent developments in ultrasound, computerised X-ray tomography and nuclear magnetic resonance now present the clinician with rival techniques and emphasise the need for the clinical development of isotopic renography.