The choice of timing for diuresis renography: the F + 0 method

Timing of diuretics in diuresis renography

Purpose

The aim of this systematic literature review was to obtain an overview of when to administer the diuretics in relation to the radiopharmaceutical during a diuresis renography.

Methods

A systematic literature search was performed in three different databases (Embase, PubMed/Medline and Cochrane Library) together with an information specialist. The review question was: when should diuretics be administered in relation to the radiopharmaceutical in a diuresis renography? Studies of adults were included together with guidelines published in collaboration with an organization.

Results

Seventeen articles and four guidelines were retrieved in the literature search. The F − 15 method (diuretics administered 15 min before the radiopharmaceutical) was the one that was studied and described most and was compared with other time points for diuretic administration. The retrieved articles and guidelines report of advantages with different time points for diuretics. Both F − 15 and F + 0 are reported to clarify washout in equivocal cases compared to F + 20.

Conclusion

No consensus could be found for a preferred time point of diuretics administration during a diuresis renography.

Diuretic Renal Scintigraphy: The State of Practice and a Potential Opportunity for Standardization

OBJECTIVE

The aim of this study was to assess variation in diuretic renal scintigraphy (DRS) practice patterns and quantify compliance with the national guidance in a large cohort of laboratories from different institutions and practice settings across the United States.

METHODS

By means of an institutional review board-approved protocol, we extracted 107 facility-specific, adult DRS protocols and associated 174 reports from the Intersocietal Accreditation Commission database, representing all laboratories applying for genitourinary scintigraphy certification during the 2016 to 2018 accreditation cycle. From these, we assessed 40 variables regarding facilities and staffing, patient preparation, examination technique and acquisition, image processing, and reporting.

RESULTS

Review of protocols and reports demonstrates a very high degree of variability in DRS practice across the United States and suboptimal compliance with societal guidelines and practice parameters. Some of the more variable or underreported parameters include the use of patient hydration, type and dosage of radiopharmaceutical, dosage and timing of diuretic administration, quantitative parameters assessed, and report content.

CONCLUSION

There is high variability in the performance and reporting of DRS among laboratories applying for accreditation, similar to that seen in studies of other nuclear medicine examinations. The wide degree of practice variance may have a significant impact on diagnostic accuracy and patient management, with inaccurate or incomplete results. This survey impresses the need for standardization and improved quality of this important nuclear medicine examination.

Advantages of gravity-assisted diuretic renogram: F + 10 (seated position) method

INTRODUCTION

In 1978, O'Reilly introduced the diuretic renogram using the F + 20 method. Initially, the patient was examined in the seated position. A dose of 40 mg furosemide was injected intravenously 20 min following tracer injection and dynamic acquisition was prolonged for 15-20 min. In 1992, the guidelines suggested to study patients in the supine position to avoid risk of diuretic-induced hypotension and reduce patient movement. Unfortunately, equivocal findings were reported in 15-30% of cases. Side effects such as bladder fullness and disruption because of voiding were reported. Several methods had been proposed in the supine position, such as the well-tempered diuretic renogram F + 20, F - 15, F0 and F + 2, with different time in minute of diuretic administration in relation to tracer injection. However, as confirmed by many studies, there was no clear evidence suggesting superiority among these methods. We suggest using the diuretic renogram with the F ± 10(sp) method for the diagnosis of obstruction in adult patients with hydronephrosis and for the follow-up in patients who underwent a surgical treatment of the urinary tract.

METHODS

We searched all international guidelines and articles of most influential authors published from 1978 to October 2020 on diuretic renogram.

RESULTS

We selected 60 articles.

DISCUSSION

F + 10(sp) method improves patient compliance avoiding bladder fullness-related problems, without need of catheterization. It allows for a more reliable quantification of the renal output, thanks to outflow indices that are favored by gravity effects.

Nuclear Medicine in Pediatric Nephro-Urology: An Overview

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

Delayed renal tissue tracer transit in Tc-99m-DTPA renography correlates with postoperative renal function improvement in UPJO patients

OBJECTIVE

The aim of the study was to explore the potential parameters for evaluating the improvement in relative renal function (RRF) in patients with unilateral ureteropelvic junction obstruction (UPJO) who underwent surgery. In this regard we observed the RRF expressed as the obstructed kidney's percentage contribution to overall renal function in technetium-99m diethylenetriaminepentaacetic acid (Tc-99m-DTPA) diuretic renography.

MATERIALS AND METHODS

Data on 47 patients, who underwent Anderson-Hynes pyeloplasty for diagnosed unilateral UPJO during the period of February 2003 to October 2014, were retrospectively collected. Tc-99m-DTPA diuretic renography was performed on all patients before and after surgery, and no morphological or functional abnormalities were detected on the contralateral kidney. Several parameters, especially renal tissue tracer transit (TTT), the response to furosemide stimulation, and RRF, were evaluated. All data were analyzed with the statistical software SPSS, 17.0, and a value of P less than 0.05 was considered statistically significant.

RESULTS

Data on 42 patients were eventually retained for further analysis; five patients were excluded because of indeterminate TTT. All patients showed obstructive response to furosemide stimulation with a preoperative RRF of 41±12%. Postoperative RRF of the obstructed kidneys was 47±11%, significantly higher than the preoperative RRF (P<0.05). Postoperative RRF improvement (absolute increment≥5%) was seen in 18/42 (43%) patients, and 24/42 (57%) of them manifested with postoperative drainage improvement. After surgery, both the RRF increment and the percentage of patients with postoperative RRF improvement in the preoperative delayed TTT group were significantly higher than those in the normal TTT group (12±7 vs. 2±4%, and 81 vs. 19%, respectively; P<0.05), but no significant difference in postoperative drainage improvement was detected between the two groups (56 vs. 54%, P>0.05). None of the other factors, including the preoperative RRF, obstructed kidney location, surgical method, sex, and age, had a significant influence on postoperative RRF improvement (P>0.05).

CONCLUSION

Preoperatively delayed TTT of Tc-99m-DTPA diuretic renography was an independent factor that correlated with RRF improvement of unilaterally hydronephrotic kidneys, and might provide valuable information for surgical decisions pertaining to UPJO patients.

Validation of IAEA software package for the analysis of scintigraphic renal dynamic studies: parameters of renal transit in children with renal pelvic dilatation

PURPOSE

The objectives of the study were to use the International Atomic Energy Agency (IAEA) software package for the analysis of scintigraphic renal dynamic studies to obtain values of curve parameters and excretory parameters in children with hydronephrosis and to validate the reliability of these numerical outputs by comparing with values established by consensus reports.

PATIENTS AND METHODS

Fifty children with hydronephrosis (median age, 16 months; 30 boys, 20 girls; 99 kidneys) underwent Tc-MAG3 diuresis renography. Studies were analyzed by 2 observers, and according to the assessment of images, renograms, and differential function, kidneys were classified as normal (42, kidneys contralateral to hydronephrotic kidney), hypotonic unobstructed (49), and obstructed (8). The IAEA software was applied to each renogram. The parameters analyzed were as follows: normalized residual activity at 20 minutes (NORA 20) and on postmicturition (PM) acquisition, output efficiency at 20 minute (OE 20), PM to maximum renal count ratio (PM/max), and mean transit time (MTT).

RESULTS

Mean values for normal, hypotonic unobstructed, and obstructed kidneys were as follows: NORA 20: 0.25, 0.57, and 2.16; OE 20 (%): 94.5, 87, and 57; normalized residual activity on PM acquisition: 0.02, 0.03, and 0.27; PM/max: 0.01, 0.02, and 0.13; and MTT (minutes): 1.9, 3.5, and 8.9, respectively. Difference between obstruction/dilatation and normal/dilatation was significant (P < 0.0001), as well as the correlation between NORA 20/OE 20 (R = -0.982). Cutoff values to predict obstruction were as follows: NORA 20, 1.6; OE 20, 73%; NORA PM, 0.11; PM/max, 0.06; and MTT, 8.23 minutes.

CONCLUSIONS

The IAEA software package gives reliable values of numerical parameters of renal excretion. The use of the software improves diagnostic accuracy of diuresis renography in children.

Radionuclides in nephrourology, Part 2: pitfalls and diagnostic applications

Radionuclide renal scintigraphy provides important functional data to assist in the diagnosis and management of patients with a variety of suspected genitourinary tract problems, but the procedures are underutilized. Maximizing the utility of the available studies (as well as the perception of utility by referring physicians) requires a clear understanding of the clinical question, attention to quality control, acquisition of the essential elements necessary to produce an informed interpretation, and production of a report that presents a coherent impression based on data contained in the report and that specifically addresses the clinical question. To help achieve these goals, part 1 of this review addressed the available radiopharmaceuticals, quality control, and quantitative indices, including the measurement of absolute and relative renal function. Part 2 assumes familiarity with part 1 and focuses on the common clinical indications of suspected obstruction and renovascular hypertension; part 2 also summarizes the status of radionuclide renal imaging in the evaluation of the transplanted kidney and the detection of infection, discusses potential pitfalls, and concludes with suggestions for future research. The series of SAM questions accompanying parts 1 and 2 has been designed to reinforce and extend points made in the review. Although the primary focus is the adult patient, aspects of the review also apply to the pediatric population.

Influence of early (F+0) intravenous furosemide injection on the split renal function using 99mTc-DTPA renography

In busy nuclear medicine departments, the F+0 protocol for diuretic renography is routinely used to shorten the acquisition time. The aim of this study was to evaluate the influence of the F+0 protocol on the split renal function (SRF) during a dynamic renal scan using technetium-99m diethylene triamine pentaacetic acid (Tc-DTPA) compared with that using the standard technetium-99m dimercaptosuccinic acid (Tc-DMSA). A total of 102 patients referred for a dynamic renal scan for varied etiologies were divided into two groups: the F+0 group, comprising 53 patients who were injected with furosemide just before Tc-DTPA injection, and the F+10 group, comprising 49 patients who were injected with the diuretic at the 10th minute after radiotracer injection. All patients were also subjected to a static cortical Tc-DMSA scan with geometric quantification of SRF. A highly significant statistical difference (P<0.001) was obtained on comparing the mean value of the difference in SRF calculated using DTPA and DMSA between the F+0 and F+10 groups, being 5.0±2.6 and 1.5±0.6%, respectively. All 49 patients in the F+10 group had a difference in split function of 5% or less, whereas 17/53 patients representing 32.1% of the F+0 group had a difference in SRF of greater than 5%. Early (F+0) furosemide injection before administration of Tc-DTPA has a significant influence on the estimation of SRF of the diseased kidney (either obstructed or functionally impaired) when compared with furosemide injection after standard Tc-DMSA administration. Care should be taken during interpretation of the scan findings when accurate split function is required.

Guidance document for structured reporting of diuresis renography

This Guidance Document for structured reporting of diuresis renography in adults was developed by the International Scientific Committee of Radionuclides in Nephro-urology (ISCORN; http://www.iscorn.org). ISCORN chose diuresis renography for its first structured report Guidance Document because suspected obstruction is the most common reason for referral, most radionuclide renal studies are conducted at institutions that perform fewer than 3 studies per week, and a large percentage of studies are interpreted by physicians with limited training in nuclear medicine. Ten panelists were asked to categorize specific reporting elements as essential, recommended, optional (without sufficient data to support a higher ranking), and unnecessary (does not contribute to scan interpretation or quality assurance). The final document was developed through an iterative series of comments and questionnaires with a majority vote required to place an element in a specific category. The Guidance Document recommends a reporting structure organized into indications, clinical history, study procedure, findings and impression and specifies the elements considered essential or recommended in each category. The Guidance Document is not intended to be restrictive but, rather, to provide a basic structure and rationale so that the diuresis renography report will: (1) communicate the results to the referring physician in a clear and concise manner designed to optimize patient care; (2) contain the essential elements required to evaluate and interpret the study; (3) clearly document the technical components of the study necessary for accountability, quality assurance and reimbursement; and (4) encourage clinical research by facilitating better comparison and extrapolation of results between institutions.

MR urography in children. Part 1: how we do the F0 technique

MR urography (MRU) has been widely accepted as a substitute to intravenous urography for investigating children with a dilated urinary tract after preliminary assessment by US and voiding cystourethrography. Hydronephrosis is by far the main indication for MRU because upper tract dilatation is a frequent condition in infants and children. Recent advances in technology have allowed MR to go beyond morphology and to assess renal function parameters such as split renal function and drainage. In this article we report our routine practice of the F0 MRU technique. The main advantages of our protocol are no requirement for general anaesthesia, no bladder catheterization, use of low-dose gadolinium-based contrast agent (0.05-0.1 mmol/kg) and total acquisition time of 30 min or less.

[Functional MR urography in children]

MR Urography (MRU) provides both morphologic and functional information without radiation exposure. It enables the assessment of split renal function, excretion, and quantification of obstruction. MRU is thus complementary to ultrasonography in the assessment of pre- and post-natal obstructive uropathies in children. If available, MRU should be definitely preferred to intravenous urography.

International Scientific Committee of Radionuclides in Nephrourology (ISCORN) consensus on renal transit time measurements

This report is the conclusion of the international consensus committee on renal transit time (subcommittee of the International Scientific Committee of Radionuclides in Nephrourology) and provides recommendations on measurement, normal values, and analysis of clinical utility. Transit time is the time that a tracer remains within the kidney or within a part of the kidney (eg, parenchymal transit time). It can be obtained from a dynamic renogram and a vascular input acquired in standardized conditions by a deconvolution process. Alternatively to transit time measurement, simpler indices were proposed, such as time of maximum, normalized residual activity or renal output efficiency. Transit time has been mainly used in urinary obstruction, renal artery stenosis, or renovascular hypertension and renal transplant. Despite a large amount of published data on obstruction, only the value of normal transit is established. The value of delayed transit remains controversial, probably due to lack of a gold standard for obstruction. Transit time measurements are useful to diagnose renovascular hypertension, as are some of the simpler indices. The committee recommends further collaborative trials.

Inter-observer reproducibility in reporting on renal drainage in children with hydronephrosis: a large collaborative study

PURPOSE

The goal of this study was to evaluate the inter-observer reproducibility in reporting on renal drainage obtained during (99m)Tc MAG3 renography in children, when already processed data are offered to the observers.

METHODS

Because web site facilities were used for communication, 57 observers from five continents participated in the study. Twenty-three renograms, including furosemide stimulation and posterect postmicturition views, covering various patterns of drainage, were submitted to the observers. Images, curves and quantitative parameters were provided. Good or almost good drainage, partial drainage and poor or no drainage were the three possible responses for each kidney.

RESULTS

An important bias was observed among the observers, some of them more systematically reporting the drainage as being good, while others had a general tendency to consider the drainage as poor. This resulted in rather poor inter-observer reproducibility, as for more than half of the kidneys, less than 80% of the observers agreed on one of the three responses. Analysis of the individual cases identified some obvious causes of discrepancy: the absence of a clear limit between partial and good or almost good drainage, the fact of including or neglecting the effect of micturition and change of patient's position, the underestimation of drainage in the case of a flat renographic curve, and the difficulties of interpretation in the case of a small, not well functioning kidney.

CONCLUSION

There is an urgent need for better standardisation in estimating the quality of drainage.

DIURETIC RENAL SCINTIGRAPHY IN NORMAL DOGS

Diuretic renal scintigraphy is commonly used in human medicine to differentiate obstructive from nonobstructive pyelectasia. In order to determine normal parameters, 99mTc-DTPA renal scintigraphy was performed twice in 20 healthy adult Mongrel dogs. Each dog was injected with either 3.0 mg/kg furosemide or an equivalent volume of saline 4.5 min following injection of the radiopharmaceutical. The following parameters were evaluated: (1) global and individual glomerular filtration rate (GFR); (2) time of peak (TOP) of the time-activity curve (TAC); (3) shape of the TAC; (4) individual kidney excretion half-time (T1/2); (5) proportion of maximum activity measured at end of study (8 min); (6) time of onset; and (7) duration of the effect of the diuretic. Most TAC in the diuretic renography group showed a steep drop in the curve following administration of the diuretic compared with a gradual slope in the saline control group. There was a statistically significant difference in T1/2 between the control renograms (median 10.25 min, range 4.41-18.07 min) and the diuretic renograms (median 4.16 min, range 3.62-5.90 min). There was a statistically significant difference in percentage maximum activity between the control renograms (median 65.25%, range 48.27-93.68%) and the diuretic renograms (median 48.54%, range 35.64-58.76%). Median time of onset of the diuretic effect was 1.10 min (0.20-2.40 min), and median duration was 0.83 min (0.30-2.35 min).

Evaluation of dilated upper renal tracts by technetium-99m ethylenedicysteine f+0 diuresis renography in infants and children

AIM

To evaluate the feasibility of modifying diuresis renography by the simultaneous administration of Tc-99m ethylenedicysteine and furosemide in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. Parameters assessed were the diuretic response in normal kidneys and the ability of the F+0 study to differentiate between renal obstruction and nonobstruction.

METHODS

One hundred and thirty-three children (93 males, 40 females; mean age 35.2 months) with sonographic diagnoses of hydronephrosis or hydroureteronephrosis underwent F+0 diuresis renography. Tc-99m ethylenedicysteine (3.7 MBq/kg body weight) and furosemide at an appropriate dose were administered intravenously at the start of the study. Posterior imaging of the kidneys and bladder was performed for 20 min followed by imaging after voiding. All patients were followed-up for 12 months, and the results of the initial F+0 diuresis renography were compared with the final diagnoses. Final diagnosis was based on the pediatric urologist's decision of either surgery or conservative management.

RESULTS

A renal unit was defined as a kidney and its ureter. There were 262 renal units with 4 patients having a solitary kidney. 90 normal and 172 abnormal renal units on sonography were assessed by F+0 diuresis renography. The furosemide clearance half time for the 90 normal renal units was 5.8 +/- 1.4 min. Of the 172 abnormal renal units, 100 were classified as nonobstructed and 72 as obstructed on diuresis renography. All 100 nonobstructed renal units were correctly classified with no false-negative studies; of the 72 renal units classified as obstructed, there were 43 true-positive studies and 29 false-positive studies. The sensitivity was 100%, specificity was 78% and accuracy was 83%.

CONCLUSION

Tc-99m ethylenedicysteine F+0 diuresis renography is a valid method for the investigation of hydronephrosis and hydroureteronephrosis in infants and children.

Comparison of Three Different Diuretic Renal Scintigraphy Protocols in Patients With Dilated Upper Urinary Tracts

PURPOSE

To compare 3 different diuretic renal scintigraphy protocols in patients with dilated upper urinary tract.

MATERIALS AND METHODS

Three diuresis renography protocols were performed in 22 adult patients (28 kidneys) with upper urinary tract dilatation. The diuretic was given 20 minutes after (F+20), at the same time as (F+0), and 15 minutes before (F-15) radionuclide administration. The mean age was 29.8 years (range, 18-43 years). The 3 protocols were identical, except for the time of injection of furosemide. The F+0 protocol could not be performed in 1 and F-15 in 2 of the patients. Each of the 3 protocols was performed for the rest of the patients. The results were classified as nonobstructive, equivocal, and obstructive according to the renogram images and curves.

RESULTS

None of the patients showed equivocal results in both F+0 and F-15 protocols. In the F+20 studies, 7 of the 28 kidneys were evaluated as equivocal. Of these, 5 kidneys showed nonobstructive and 2 kidneys revealed obstructive renogram patterns with the other 2 protocols (F+0 and F-15). Moreover, one kidney, which was evaluated as nonobstructive in the F+20 protocol, showed an obstructive pattern in both F+0 and F-15 protocols. All of the kidneys showing obstructive patterns in the F+20 study also revealed obstruction in the F+0 and F-15 investigations. We could not find any difference between the renogram patterns of F+0 and F-15 investigations.

CONCLUSIONS

F+0 and F-15 protocols allow clarification in cases of equivocal F+20 studies. Because the F+0 study is more practical and shorter, we suggest the F+0 method when equivocal results are obtained by an F+20 study or as a single test when there is only one opportunity to confirm or exclude the presence of obstruction.

Standardization of the renogram technique for investigating the dilated upper urinary tract and assessing the results of surgery

OBJECTIVE

To recommend a standard technique for the renographic evaluation of the dilated upper urinary tract, and for evaluating the results of surgery.

METHODS

This review is an update of the previously recommended consensus report of the 9th International Symposium of Radionuclides in Nephrourology.

RESULTS

State-of-the-art recommendations are detailed for standardizing common radionuclide investigations.

CONCLUSIONS

Where open, laparoscopic or endourological techniques for treating pelvi-ureteric junction obstruction are under study, results can only be compared by standardizing the investigational techniques. The guidelines produced here are recommended for this purpose.