Alain Prigent

Consensus report on quality control of quantitative measurements of renal function obtained from the renogram: International consensus committee from the scientific committee of radionuclides in nephrourology

Among all the physiological indices that can be quantified using renography, measurement of renal function is the most basic. These measurements are used to make critical clinical management decisions and, as such, their reliability needs to be quality assured. This article seeks to address each aspect of the renography procedure, with particular emphasis on the effect on measurement of relative renal function. Estimation of individual kidney function is mentioned, but only briefly. A consensus approach was adopted, overseen, and directed by a chairman appointed by the Scientific Committee of the International Radionuclides in Nephro-Urology Group. The chairman selected the panel of experts from eight different countries based on their practical experience in the field. Where evidence exists to support the various recommendations it is given. Otherwise, the stated guidance represents the considered opinion of a body of experts, based on long experience and unpublished data. Some necessary compromises were made to account for the fact that renography is seldom performed solely with the purpose of measuring relative renal function. The technicalities of renography have always been a source of debate in nuclear medicine, which is reflected by the fact that a consensus could simply not be reached on a small number of issues. The structure of the report ensures that these are clearly indicated. This should serve to highlight gaps in our current knowledge, thus helping to direct future research. It is envisaged that the recommendations will be revised on a 2-year cycle to ensure that they remain up to date. An open process will be used to encourage participation and ownership. It is hoped that promotion of these guidelines, suitably complemented by audit processes, will raise standards in the practice of gamma camera renography.

The diagnosis of renovascular hypertension: the role of captopril renal scintigraphy and related issues

This article reviews the screening and diagnostic tests used in the detection of significant renal artery stenosis and renovascular hypertension. After addressing the pathophysiological considerations necessary for correct diagnostic test interpretation, this review critically surveys the recent advances in, and the limitations of, relevant investigational procedures and in particular focusses on the efficacy and issues of Angotensin-converting enzyme inhibitor renal scintigraphy.

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.

Syllabus for Postgraduate Specialization in Nuclear Medicine – 2011/2012 Update

Nuclear medicine (NM) is a branch of medicine that uses unsealed radioactive substances for diagnosis and therapy. NM became an independent medical specialty under the European Directives in 1988. The minimum duration of the postgraduate specialized training in the European Union is 4 years, but may be extended beyond this period according to the requirements for training in other clinical disciplines. Candidates for specialized training should have a good general background in internal medicine. More detailed knowledge about those conditions which may need to be investigated or treated by NM techniques has to be acquired. Some complementary imaging and biological methods as far as they relate to NM procedures must be mastered. Training in basic sciences, such as pharmacokinetics, radiochemistry, instrumentation, image processing, dosimetry and quality control is required. The quality of training has to be objectively assessed, using a final examination on a national basis covering basic sciences and clinical skills, after satisfactory completion of a minimum number of courses and/or workshops and a formally organized and controlled practical training. Each training programme should contain a standard against which the progress of the trainee can be assessed for each element of the syllabus. The assessment may take the form of an interview, a written paper, an essay, a set of multiple-choice questions or an oral examination of displayed images of various NM techniques in clinical practice. Continuous assessment is an alternative. Each end of year or training programme assessment should carry a score that indicates how the candidate has progressed against the set target. Successful trainees are awarded with a final certificate, degree or diploma that is recognized by the government, local health authority and hospital as an assurance of specialist competence in NM. The clinical training of physicians specializing in NM should include: (1) a minimal theoretical foundation of the general principles of NM with active participation in clinical presentations, seminars and meetings and (2) in vivo diagnostic procedures performance. Personal responsibility (including indication, justification, performance and interpretation) must be taken for at least 3,000 in vivo NM diagnostic procedures, with a broad spectrum of the most currently used procedures. The list of the procedures published in the syllabus will be subject to revision. It is recommended that a period of training be spent away from the main department in at least one other On behalf of the Educational and Syllabus Committee andthe Executive Committee, Union Européenne des Médecins Spécialistes/ European Union of Medical Specialists, Section of Nuclear Medicine/ European Board of Nuclear Medicine (UEMS/EBNM). Other committee members actively participating in the planning, discussion and writing of the present syllabus update are for the UEMS/EBNM Educational and Syllabus Committee A.K.A. Ahonen (Finland), F. Brunotte (France), R. Hustinx (Belgium), H. Sayman (Turkey) and J. Pou Ucha (Spain) as young EANM member representative and for the UEMS/EBNM Executive Committee M. Bajc and L.S. Maffioli.

Synthesis and application of lactosylated, 99mTc chelating albumin for measurement of liver function.

Neogalactosylated and neolactosylated albumins are currently used as radiopharmaceutical agents for imaging the liver asialoglycoprotein receptors, which allows the quantification of hepatic liver function in various diseases and also in healthy liver transplant donors. We developed an original process for synthesizing a chelating neolactosylated human albumin using maleimidopropyl-lactose and maleimidopropyl-diethylene triamine pentaacetic acid (DTPA) derivatives. The lactosylated protein (LACTAL) conjugate showed excellent liver uptake compared to nonlactosylated protein and a very high signal-to-noise ratio, based on functional assessment of biodistribution in mice using (99m)Tc-scintigraphy.

Chronic Urinary Obstruction: Evaluation of Dynamic Contrast-enhanced MR Urography for Measurement of Split Renal Function

PURPOSEnTo evaluate if measurement of split renal function ( SRF split renal function ) with dynamic contrast material-enhanced ( DCE dynamic contrast enhanced ) magnetic resonance (MR) urography is equivalent to that with renal scintigraphy ( RS renal scintigraphy ) in patients suspected of having chronic urinary obstruction.nnnMATERIALS AND METHODSnThe study protocol was approved by the institutional ethics committee of the coordinating center on behalf of all participating centers. Informed consent was obtained from all adult patients or both parents of children. This prospective, comparative study included 369 pediatric and adult patients from 14 university hospitals who were suspected of having chronic or intermittent urinary obstruction, and data from 295 patients with complete data were used for analysis. SRF split renal function was measured by using the area under the curve and the Patlak-Rutland methods, including successive review by a senior and an expert reviewer and measurement of intra- and interobserver agreement for each technique. An equivalence test for mean SRF split renal function was conducted with an α of 5%.nnnRESULTSnReproducibility was substantial to almost perfect for both methods. Equivalence of DCE dynamic contrast enhanced MR urography and RS renal scintigraphy for measurement of SRF split renal function was shown in patients with moderately dilated kidneys (P < .001 with the Patlak-Rutland method). However, in severely dilated kidneys, the mean SRF split renal function measurement was underestimated by 4% when DCE dynamic contrast enhanced MR urography was used compared with that when RS renal scintigraphy was used. Age and type of MR imaging device had no significant effect.nnnCONCLUSIONnFor moderately dilated kidneys, equivalence of DCE dynamic contrast enhanced MR urography to RS renal scintigraphy was shown, with a standard deviation of approximately 12% between the techniques, making substitution of DCE dynamic contrast enhanced MR urography for RS renal scintigraphy acceptable. For severely dilated kidneys, a mean underestimation of SRF split renal function of 4% should be expected with DCE dynamic contrast enhanced MR urography, making substitution questionable.

Clinical Problems in Renovascular Disease and the Role of Nuclear Medicine

Although renovascular disease remains defined as a stenosis of the main renal artery or its proximal branches (renal artery stenosis [RAS]), its clinical overview has changed dramatically over the last 15-20 years and its management is more controversial than ever before. The clinical problems, not only diagnosis and treatment but also the relative contribution of different pathophysiological mechanisms involved in the progression of kidney disease, have shifted dramatically. This presentation aims to emphasize the paradigm change revisiting the (recent) past focused on renovascular hypertension (RVH) to the current context of preservation or recovery of threatened renal function in patients with progressive atherosclerotic renovascular disease until its last stage of irreversible ischemic nephropathy. In the past, the foreground was occupied by RVH, a very rare disease, where the activation of the renin-angiotensin-aldosterone system (RAAS) was supposed to play the major, if not only, role in RVH issues. The retrospective RVH diagnosis was established either on the improvement or, more rarely, on the cure of hypertension after revascularization by, most often, a percutaneous transluminal renal angioplasty with or without a stent placement. At this time, captoptril radionuclide renography was an efficient diagnostic tool, because it was a functional (angiotensin-converting enzyme inhibition), noninvasive test aiming to evidence both the RAAS activation and the lateralization (or asymmetry) of renin secretion by the kidney affected by a hemodynamically significant RAS. At present, even if captoptril radionuclide renography could be looked upon as the most efficient (and cost effective in selected high-risk patients) noninvasive, functional test to predict the improvement of hypertension after RAS correction, its clinical usefulness is questioned as the randomized, prospective trials failed to demonstrate any significant benefits (either on blood pressure control or on renal function protection) of the revascularization over current antihypertensive therapy. Today many patients with RVH remain undetected for years because they are treated successfully and at low expense with these new blockers of RAAS. In addition to its well-known role in hemodynamics, angiotensin II promotes activations of profibrogenic and inflammatory factors and cells and stimulates reactive oxygen species generation. The atherosclerotic milieu itself plays a role in the loss of renal microvessels and defective angiogenesis. After an adaptative phase, ischemia eventually develops and induces hypoxia, the substratum of ischemic nephropathy. Because blood oxygen level-dependent MRI may provide an index of oxygen content in vivo, it may be useful to predict renal function outcome after percutaneous transluminal renal angioplasty. New PET tracers, dedicated to assess RAAS receptors, inflammatory cell infiltrates, angiogenesis, and apoptose, would be tested in this context of atherosclerotic renovascular disease.

Can dimercaptosuccinic acid renal scintigraphy be used to assess global renal function

Abstract.Use of dimercaptosuccinic acid (DMSA) has been proposed for the assessment of both relative and absolute renal function. Our aim was to test whether the renal absolute DMSA uptake (ADU) can reflect the absolute renal function from a theoretical point of view. A simple model was used to compute the ADU in the case of injury to one kidney. It was found that the assumption that ADU correctly reflects the absolute renal function may lead to a more than 50% overestimation of the function of both the normal and the impaired kidney. The later the measurement is made and the more impaired is the kidney, the more important is the error. Although DMSA can reliably quantify the relative renal function, it should not be used to assess absolute renal function lest major overestimation should occur.

Intrapancreatic accessory spleen diagnosed on radionuclide imaging.

Intrapancreatic accessory spleen (IPAS) is ectopic splenic tissue distinct from the main spleen. A 46-year-old man with chronic hepatitis C, presented in 2006 with low right chest pain which led to a diagnosis of tuberculosis pleurisy. CT scan and MRI showed a round, homogenous, well limited mass of 3cm in the pancreas tail. Tc-99m heat-damaged red blood cell scintigraphy with SPECT-CT was performed to confirm the diagnosis of IPAS. Most cases of IPAS described in the literature were diagnosed by pathologists after distal pancreatectomy and splenectomy performed for a suspicion of pancreatic tumor. However, heat-damaged red blood cell scintigraphy remains the most commonly used diagnostic procedure for IPAS, even if superparamagnetic iron oxide MRI contrast agent may be used in the future.

Quantitation in planar renal scintigraphy: which µ value should be used?

Abstract. The attenuation coefficient value µ used by different authors for quantitation in planar renal scintigraphy varies greatly, from the theoretical value of 0.153 cm–1 (appropriate for scatter-free data) down to 0.099 cm–1 (empirical value assumed to compensate for both scatter and attenuation). For a 6-cm-deep kidney, such variations introduce up to 30% differences in absolute measurement of kidney activity. Using technetium-99m phantom studies, we determined the µ values that would yield accurate kidney activity quantitation for different energy windows corresponding to different amounts of scatter, and when using different image analysis approaches similar to those used in renal quantitation. With the 20% energy window, it was found that the µ value was strongly dependent on the size of the region of interest (ROI) and on whether background subtraction was performed: the µ value thus varied from 0.119 cm–1 (loose ROI, no background subtraction) to 0.150 cm–1 (kidney ROI and background subtraction). When using data from an energy window that could be considered scatter-free, the µ value became almost independent of the image analysis scheme. It is concluded that: (1) when performing background subtraction, which implicitly reduces the effect of scatter, the µ value to be used for accurate quantitation is close to the theoretical µ value; (2) if the acquired data were initially corrected for scatter, the appropriate µ value would then be the theoretical µ value, whatever the image analysis scheme.