The 14th International Symposium on Radionuclides in Nephrourology

Diuresis renography in equivocal urinary tract obstruction. A historical perspective

Obstructive nephropathy may be suspected for the incidental detection of dilated renal collecting system at ultrasonography, CT or MRI. A dilated renal collecting dilation (calyco-pelvis or ureteres) might be related 1) to an anatomical variant of the excretory tract without obstruction and, therefore, without consequence on renal function, or 2) to an obstruction/stenosis of the urinary tract that may cause a damage of kidney function. In the present review we annotated the various methods proposed for Diuresis Renography (DR) used with the purpose to make early diagnosis of obstructive nephropathy. First, the F + 20 method (i.e. furosemide 40 mg injected IV 20 min after radiotracer injection) in seated position (sp) (F + 20(sp)) was reported to distinguish between an anatomical dilation from an anatomical obstruction of the urinary tract. It was also suggested to perform DR with the patient in supine or prone position in order to minimize possible furosemide-induced hypotension and patient's movements during exam. Other DR methods were proposed administering furosemide EV to the patient in supine position at different times: F-15 (furosemide injected IV 15 min prior to radiotracer), F0 (furosemide injected contemporary to radiotracer), F + 20 (furosemide injected 20 min after the radiotracer), F-20 and Well Tempered (other than F + 20 this modality requires saline infusion for all duration of the test plus bladder catheterization). Unfortunately, in all the above described DR methods with patientin supine position, despite the furosemide administration, a sensitive slowing down of urinary outflow could be related to the supine position itself of the patient during the examination. Lastly, there are reports of a new DR method based on furosemide IV injection 10 min after radiotracer with the patient in seated position, F+10(sp). This method allows a better timing between hydration (400 mL of water) at 5 min, and the injection of relatively low dose of furosemide (20 mg), thus avoiding side effects as diuretic-induced hypotension and favouring bladder filling, therefore ameliorating patient compliance and reducing equivocal responses.

Reproducibility of differential renal function measurement using technetium-99m-ethylenedicysteine dynamic renal scintigraphy: a French prospective multicentre study

OBJECTIVE

Dynamic renal scintigraphy remains the gold standard for assessing differential renal function (DRF). Recently, technetium-99m-ethylenedicysteine (Tc-EC) was shown to be valuable and had similar quality images as technetium-99m-mercaptoacetyltriglycine (Tc-MAG3). However, its reproducibility has never been confirmed. The aim of this study was to perform the first evaluation of Tc-EC reproducibility for assessing DRF in children who were referred for hydronephrosis or urinary tract dilatation.

PATIENTS AND METHODS

A total of 109 patients from three French nuclear medicine departments prospectively underwent dynamic renal scintigraphy with Tc-EC. DRF reproducibility was assessed by different pairs of raters using a multilevel design that integrated local and centralized predefined procedures.

RESULTS

Both local and centralized procedures yielded near-excellent inter-rater agreements, with all of the intraclass correlation coefficient values over 0.998. Bland-Altman plots showed a systematic bias of less than 1%, with the corresponding limits of agreements not exceeding the 5% threshold cut-off value that corresponds to the clinical definition of acceptable limits for this purpose. Intrarater agreements were also good to excellent.

CONCLUSION

This prospective multicentre study showed that Tc-EC is highly reproducible for assessing DRF in a standard paediatric population, thus validating its use as an alternative to Tc-MAG3 in this setting.

(99m)Tc-MAG3 diuretic renography in diagnosis of obstructive nephropathy in adults: a comparison between F-15 and a new procedure F+10(sp) in seated position

OBJECTIVE

The objective of this study was to compare 2 diuretic renography procedures: F-15 versus F+10(sp) for diagnosis of obstructive uropathy in adults.

METHODS

Thirty-six patients with unilateral or bilateral hydronephrosis had 2 consecutive Tc-MAG3 diuretic renograms within 7 days, using the widely used procedure F-15 in supine position, and a new seated-position procedure whereby the patient drinks 400 to 500 mL of water at 5 minutes and receives an injection of 20 mg of furosemide at 10 minutes [F+10 (sp)].

RESULTS

F-15 showed nonobstructive results in 63.9% of kidneys, obstruction in 26.4%, and equivocal findings in 6.9% and was not applicable in 2.8%. F+10(sp) showed nonobstructive results in 70.9%, obstruction in 27.8%, and equivocal result in 1.4% of kidneys. Nephroptosis was observed by F+10(sp) in 22.2% of kidneys. Adverse effects reported for the F-15 were hypotension in 2 patients, renal colic in 3 patients, and interruption due to voiding in 5 patients. No adverse effects were reported for F+10(sp).

CONCLUSIONS

This study shows that the F+10(sp) procedure reduces the equivocal findings of F-15 procedure in 36 patients. It can improve the accuracy and compliance, avoiding adverse effects and reducing bladder filling-related problems.

The reproducibility of measurements of differential renal function in paediatric 99mTc-MAG3 renography

OBJECTIVES

The aims of this study were to establish the reproducibility of estimates of differential renal function (DRF) obtained using the software supplied by different vendors, assess the effects of age, glomerular filtration rate (GFR) and degree of asymmetry of renal function on reproducibility and ascertain whether the software gives the same estimates of DRF.

METHODS

A stratified sample of 172 renograms covering a wide range of DRF estimates, age and renal function was drawn from an electronic archive containing raw data from 1416 renograms. The renograms were processed by one operator using seven different methods, five times for each method. For each renogram and each method the DRF for the left kidney and difference between the maximum and minimum of the five estimates of DRF were calculated.

RESULTS

There were differences in reproducibility among the seven methods [Friedman analysis of variance, χ(2)(N=172, d.f.=6)=367.0, P=0.0001]. Reproducibility was good with all methods in most children. The appreciable minority in whom reproducibility was not as good tended to be less than 6 months old or had GFRs below 90 ml/min/1.73 m(2) or both. The median of the DRF estimates of the left kidney obtained using the seven methods differed [Friedman analysis of variance, χ(2)(N=172, d.f.=6)=284.7, P<0.0001]. The largest difference between any two methods was 5%.

CONCLUSION

Although reproducibility was good in the majority of children, an appreciable minority showed poor reproducibility, which could impact clinical decision making. It is essential that these studies be identified. This can be done by processing each renogram several times, ideally using different methods. Those with poorer reproducibility tended to be less than 6 months old or to have a low GFR.

99mTc-MAG3 scintigraphy for the longitudinal follow-up of kidney function in a mouse model of renal ischemia-reperfusion injury

Background

Experimental models are essential tools in the development and evaluation of novel treatment options, but the preclinical model of renal ischemia-reperfusion injury is limited to the retrieval of (very) early functional data, leaving the pivotal long-term outcome unknown. The present study applies technetium-99m-mercapto-acetyl-tri-glycine [^99mTc-MAG3] scintigraphy for the longitudinal follow-up examination of long-term kidney function after renal ischemia-reperfusion injury.

Methods

Unilateral warm ischemia was induced in scid beige mice by vascular clamping of the kidney hilum for 40 min. ^99mTc-MAG3 scintigraphy was performed prior to injury, 8 and 14 days post ischemia. The fractional uptake rate [FUR] was calculated from scintigraphy data as a measure of renal clearance.

Results

FUR demonstrated a significant functional impairment of the ischemic kidney 8 and 14 days after injury (P < 0.05 vs. baseline), while contralateral non-ischemic kidneys showed no significant changes. In histological analysis, ischemic kidneys exhibited tubular dilatation and cytoplasmic degeneration as signs of hypoxia without any evidence for necrosis.

Conclusions

FUR enables the detection of renal dysfunction and longitudinal long-term follow-up examination in the same individual. Our model may facilitate preclinical therapy evaluation for the identification of effective renoprotective therapies.