French National Authority for Health assessment of metabolic surgery for type 2 diabetes remission-A meta-analysis in patients with class I to III obesity

OBJECTIVE

Randomized controlled trials (RCTs) have demonstrated the superiority of metabolic surgery (MS) over medical therapy (MT) in patients with obesity and type 2 diabetes, leading, to a joint statement in 2016 proposing MS to patients with class I obesity and uncontrolled glycemia. Yet, these RCTs included few patients with class I obesity (body mass index 30-35 kg/m2) and even fewer patients with overweight. Our aim was to provide an updated systematic review (SR) with meta-analysis (MA) of RCTs reporting diabetes remission (DR) after MS in these patients.

RESEARCH DESIGN AND METHODS

We included in the SR with MA only RCTs with at least 24-month follow-up found in Medline, Cochrane Library, Embase, and LiSSA between January 2008 and September 2022 comparing DR post-MT versus post-MS. We calculated relative risk (RR) and 95 % confidence intervals (CIs) using the Mantel-Haenszel random-effects approach to examine differences in DR between patients allocated to MS versus MT.

RESULTS

DR was significantly higher in MS versus MT after 36 months' follow-up in patients with obesity (RR = 6.65 [95 %CI 2.24;19.79]; I² = 27 %; 5 trials, 404 patients), but also specifically in patients with class I obesity (RR = 5.27 [1.31;21.23]; I² = 0 %; 4 trials, 80 patients). Furthermore, and in line with previous results, all additional MAs performed in patients with obesity in this work favor MS (specifically Roux-en-Y gastric bypass) over MT at 24, 36 (only) and 60 months of follow-up.

CONCLUSIONS

Although the data available in patients with class I obesity and type 2 diabetes remains limited, MA shows higher rates of DR after MS compared with MT after 36 months' follow-up in these patients. Consequently, the French National Authority for Health French (HAS) recommends MS for these patients.

Head-to-head comparison of the diagnostic performances of Rubidium-PET and SPECT with CZT camera for the detection of myocardial ischemia in a population of women and overweight individuals

BACKGROUND

The aim of this study was to compare the diagnostic performances for the detection of myocardial ischemia of 82-Rb-PET-MPS and 99m-Tc-SPECT-MPS in overweight individuals and women.

METHODS AND RESULTS

Men with BMI ≥ 25 and women referred for MPS were considered for inclusion. All individuals underwent 99m-Tc-SPECT-MPS with CZT cameras and 82-Rb-PET-MPS in 3D-mode. Individuals with at least one positive MPS were referred for coronary angiography (CA) with FFR measurements. A criterion for positivity was a composite endpoint including significant stenosis on CA or, in the absence of CA, the occurrence of acute coronary event during the following year. 313 patients (46% women) with mean BMI of 31.8 ± 6.5 were included. Sensitivity for the detection of myocardial ischemia was higher with 82-Rb-PET-MPS compared with 99m-Tc-SPECT-MPS (85% vs. 57%, P < .05); specificity was equally high with both imaging techniques (93% vs. 94%, P > .05). 82-Rb-PET allowed for a more accurate detection of patients with a high-risk coronary artery disease (HR-CAD) than 99m-Tc-SPECT-MPS (AUC = 0.86 vs. 0.75, respectively; P = .04).

CONCLUSIONS

In women and overweight individuals, 82-Rb-PET-MPS provides higher sensitivity for the detection of myocardial ischemia than 99m-Tc-SPECT-MPS thanks to a better image quality and an improved detection of HR-CAD.

Current Status of Myocardial Perfusion Imaging With New SPECT/CT Cameras

Myocardial perfusion imaging (MPI) with Single-Photon Emission Computed Tomography (SPECT) has a major role in the management of coronary artery disease. Recent technological advances regarding SPECT detectors with the use of solid-state detectors has allowed for improved imaging quality since a decade with dramatic dose and/or time reduction of imaging protocols due to improved sensitivity and spatial resolution, and is now performed as a routine exam. Interestingly, this new technology has modified our everyday practice, from acquisition protocols (low dose and ultra-fast protocols) to image semiology. Numerous studies have shown how these technical advances have allowed for improved patient management, with similar or improved diagnostic and prognostic information derived from MPI. These improvements have also led to the straightforward implementation of myocardial blood flow measurement. This article reviews the current status of MPI using new SPECT and SPECT/CT cameras.

Nanostructured lipid carriers accumulate in atherosclerotic plaques of ApoE-/- mice

Nanostructured lipid carriers (NLC) might represent an interesting approach for the identification and targeting of rupture-prone atherosclerotic plaques. In this study, we evaluated the biodistribution, targeting ability and safety of ⁶⁴Cu-fonctionalized NLC in atherosclerotic mice. ⁶⁴Cu-chelating-NLC (51.8±3.1 nm diameter) with low dispersity index (0.066±0.016) were produced by high pressure homogenization at tens-of-grams scale. 24 h after injection of ⁶⁴Cu-chelated particles in ApoE^-/- mice, focal regions of the aorta showed accumulation of particles on autoradiography that colocalized with Oil Red O lipid mapping. Signal intensity was significantly greater in aortas isolated from ApoE^-/- mice compared to wild type (WT) control (8.95 [7.58, 10.16]×10⁸ vs 4.59 [3.11, 5.03]×10⁸ QL/mm², P < 0.05). Moreover, NLC seemed safe in relevant biocompatibility studies. NLC could constitute an interesting platform with high clinical translation potential for targeted delivery and imaging purposes in atherosclerosis.

Diagnostic Impact of 18 F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography and White Blood Cell SPECT/Computed Tomography in Patients With Suspected Cardiac Implantable Electronic Device Chronic Infection

Background:

Cardiac implantable electronic devices (CIEDs) chronic infection diagnosis is challenging because the clinical presentation is frequently misleading and echocardiography may be inconclusive. The aim of this study was to evaluate the diagnostic value of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (CT) and radiolabeled white blood cells single photon emission CT/CT in a cohort of patients who underwent both scans for suspicion of CIED infection and inconclusive routine investigations.

Methods:

Forty-eight consecutive patients with suspicion of CIED infection who underwent both 18 F-fluorodeoxyglucose positron emission tomography/CT and white blood cell single photon emission CT/CT in a time span ≤30 days were retrospectively included. The final diagnosis of CIED infection by the endocarditis expert team was based on the modified Duke-Li classification at the end of follow-up. 18 F-Fluorodeoxyglucose positron emission tomography/CT and white blood cell single photon emission CT/CT scans were independently analyzed blinded to the patients’ medical record.

Results:

In the overall study population, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were respectively 80%, 91%, 80%, and 91% for 18 F-fluorodeoxyglucose positron emission tomography/CT and 60%, 100%, 100%, and 85% for white blood cell single photon emission CT/CT. Addition of a positive nuclear imaging scan as a major criterion markedly improved the Duke-Li classification at admission. Semiquantitative parameters did not allow to discriminate between definite and rejected CIED infection. Prolonged antibiotic therapy before imaging tended to decrease the sensitivity for both techniques.

Conclusions:

Nuclear imaging can improve the diagnostic performances of the Duke-Li score at admission in a selected population of patients with suspected CIED infection, particularly when the infection was initially graded as possible. Whenever possible, imaging should be performed before or early after antibiotic initiation.

Cause of death analysis and temporal trends in survival after liver transplantation for transthyretin familial amyloid polyneuropathy

BACKGROUND

Hereditary transthyretin amyloidosis (ATTR) is a multisystemic disease involving mainly the peripheral nervous system and the heart. Liver transplantation (LT) is the reference treatment for ATTR neuropathy and preoperative detection of high risk patients is crucial. We aimed to document the causes of death of ATTR patients after LT, their temporal trends, and to evaluate whether the available preoperative tools that predict the risk of death after LT for hereditary ATTR amyloidosis matched with these trends.

METHODS

A retrospective longitudinal cohort study was performed on 215 consecutive ATTR patients who underwent LT between January 1993 and January 2011. Each patient's death cause and timing were classified.

RESULTS

Over a median follow up of 5.9 years, 84 patients died. The rate of death was higher in the first year following LT than thereafter (13.0 vs. 4.3 ± 1.8%/year; p = .004). Cardiac events ranked as the leading cause of death (C: 38%), followed by infections (I: 24%), graft complications (G: 17%), end stage amyloidosis, stroke and others (ASO: 7% each). Deaths due to graft complications and infections (GI) occurred earlier than those due to end stage amyloidosis and stroke. Death prediction was less accurate for GI-related mortality than for other causes, which blunted the accuracy of the early-term risk prediction scores. Conclusions In ATTR amyloidosis, cardiac events were the leading cause of death after liver transplantation. Close preoperative evaluation allowed for accurate mid-term prediction of mortality, but the high rate of graft complications and infections blunted the early-term risk prediction.

Can Nuclear Imaging Techniques Predict Patient Outcome and Guide Medical Management in Hereditary Transthyretin Cardiac Amyloidosis?

PURPOSE OF REVIEW

Nuclear imaging recently gained a key role in the diagnosis and prognostic assessment of transthyretin (TTR)-related cardiac amyloidosis. This review aims at summarizing the state-of-the art regarding the implementation of nuclear imaging in the management of hereditary mutated TTR-cardiac amyloidosis (mTTR-CA).

RECENT FINDINGS

Although cardiac uptake of bone tracers is acknowledged as a specific marker of TTR amyloid cardiac burden, recent studies validated the implementation of bone scan in the flow chart for non-invasive diagnosis and follow-up of CA in multicenter trials. Simultaneously, cardiac denervation evidenced by MIBG scintigraphy proved to be a strong and independent prognostic marker of poor outcome in mTTR-CA. By its unique ability to assess both amyloid burden and cardiac denervation, nuclear imaging may prove useful as part of multimodality imaging tools to trigger treatment initiation and monitoring in patients with mTTR-CA.

Cardiac denervation evidenced by MIBG occurs earlier than amyloid deposits detection by diphosphonate scintigraphy in TTR mutation carriers

PURPOSE

Cardiac involvement in familial transthyretin (TTR) amyloidosis is of major prognostic value, and the development of early-diagnostic tools that could trigger the use of new disease-modifying treatments is crucial. The aim of our study was to compare the respective contributions of ^99mTc-diphosphonate scintigraphy (DPD, detecting amyloid deposits) and ¹²³I-MIBG (MIBG, assessing cardiac sympathetic denervation) in patients with genetically proven TTR mutation referred for the assessment of cardiac involvement.

METHODS

We prospectively studied 75 consecutive patients (classified as symptomatic or asymptomatic carriers), using clinical evaluation, biomarkers (troponin and BNP), echocardiography, and nuclear imaging. Patients were classified as having normal heart-to-mediastinum (HMR) MIBG uptake ratio 4 h after injection (defined by HM4 ≥ 1.85) or abnormal HM4 < 1.85, and positive DPD uptake (grade ≥ 1 of Perugini classification) or negative DPD uptake.

RESULTS

Among 75 patients, 49 (65%) presented with scintigraphic sympathetic cardiac denervation and 29 (39%) with myocardial diphosphonate uptake. When MIBG was normal, DPD was negative except for two patients. Age was an independent predictor of abnormal scintigraphic result of both MIBG and DPD (HR 1.08 and 1.15 respectively), whereas echocardiographic-derived indicators of increased left ventricular filling pressure (E/e' ratio) was an independent predictor of abnormal MIBG (HR 1.33) and global longitudinal strain of positive DPD (HR 1.45). In asymptomatic patients (n = 31), MIBG was abnormal in 48% (n = 15) among whom 50% had a normal DPD; all those with a normal MIBG (n = 16) had a normal DPD.

CONCLUSIONS

In TTR mutation carriers, cardiac sympathetic denervation evidenced by decreased MIBG uptake is detected earlier than amyloid burden evidenced by DPD. These results raise the possibility of a diagnostic role for MIBG scintigraphy at an early stage of cardiac involvement in TTR-mutated carriers, in addition to its well-established prognostic value.

Relationship between cardiac microvascular dysfunction measured with 82Rubidium-PET and albuminuria in patients with diabetes mellitus

Background

Albuminuria is of one the strongest predictors of cardiovascular disease (CVD) in diabetes. Diabetes is associated with cardiac microvascular dysfunction (CMD), a powerful, independent prognostic factor for cardiac mortality. The aim of this study was to evaluate the relationship between CMD and microvascular complications in patients without known CVD.

Methods

In this monocentric study, myocardial flow reserve (MFR) was measured with cardiac ⁸²Rubidium positron emission tomography (Rb-PET) in 311 patients referred to nuclear medicine department of Bichat University Hospital for screening of coronary artery disease from 2012 to 2014. Patients with hemodynamically relevant stenosis on coronary angiography or myocardial ischemia on Rb-PET were excluded. Among patients with diabetes, MFR values were compared according to the presence of retinopathy and albuminuria.

Results

Overall, 175 patients (118 with type 2 diabetes) were included. MFR was significantly lower in patients with diabetes compared with those without diabetes (2.6 ± 1.1 vs. 3.3 ± 1.7; p < 0.005). In patients with diabetes, MFR decreased progressively in relation to albumin urinary excretion (normoalbuminuria: 2.9 ± 1.1, microalbuminuria: 2.3 ± 1.0, macroalbuminuria: 1.8 ± 0.7; p < 0.0001). MFR was not significantly different in patients with vs. without retinopathy (2.4 ± 1.0 vs. 2.7 ± 1.1, p = 0.07). Microalbuminuria and macroalbuminuria remained strongly associated with impaired MFR after multiple adjustments [odds ratio 2.6 (95% CI 1.1–8.4) and 5.3 (95% CI 1.2–44.7), respectively]. This association was confirmed when analyses were restricted to patients with low levels of coronary calcifications on computed tomography.

Conclusions

Impaired MFR was more frequent in patients with diabetes and was strongly associated with the degree of albuminuria suggesting that CMD and albuminuria might share common mechanisms.

Electronic supplementary material

The online version of this article (10.1186/s12933-017-0652-1) contains supplementary material, which is available to authorized users.

Targeting mannose receptor expression on macrophages in atherosclerotic plaques of apolipoprotein E-knockout mice using 111In-tilmanocept

Background

Atherosclerotic plaque phenotypes are classified based on the extent of macrophage infiltration into the lesions, and the presence of certain macrophage subsets might be a sign for plaque vulnerability. The mannose receptor (MR) is over-expressed in activated macrophages. Tilmanocept is a tracer that targets MR and is approved in Europe and the USA for the detection of sentinel lymph nodes. In this study, our aim was to evaluate the potential of ¹¹¹In-labelled tilmanocept for the detection of MR-positive macrophages in atherosclerotic plaques of apolipoprotein E-knockout (ApoE-KO) mouse model.

Methods

Tilmanocept was labelled with ¹¹¹In. The labelling stability and biodistribution of the tracer was first evaluated in control mice (n = 10) 1 h post injection (p.i.). For in vivo imaging studies, ¹¹¹In-tilmanocept was injected into ApoE-KO (n = 8) and control (n = 8) mice intravenously (i.v.). The mice were scanned 90 min p.i. using a dedicated animal SPECT/CT. For testing the specificity of ¹¹¹In-tilmanocept uptake in plaques, a group of ApoE-KO mice was co-injected with excess amount of non-labelled tilmanocept. For ex vivo imaging studies, the whole aortas (n = 9 from ApoE-KO and n = 4 from control mice) were harvested free from adventitial tissue for Sudan IV staining and autoradiography. Cryosections were prepared for immunohistochemistry (IHC).

Results

¹¹¹In radiolabelling of tilmanocept provided a yield of greater than 99%. After i.v. injection, ¹¹¹In-tilmanocept accumulated in vivo in MR-expressing organs (i.e. liver and spleen) and showed only low residual blood signal 1 h p.i. MR-binding specificity in receptor-positive organs was demonstrated by a 1.5- to 3-fold reduced uptake of ¹¹¹In-tilmanocept after co-injection of a blocking dose of non-labelled tilmanocept. Focal signal was detected in atherosclerotic plaques of ApoE-KO mice, whereas no signal was detected in the aortas of control mice. ¹¹¹In-tilmanocept uptake was detected in atherosclerotic plaques on autoradiography correlating well with Sudan IV-positive areas and associating with subendothelial accumulations of MR-positive macrophages as demonstrated by IHC.

Conclusions

After i.v. injection, ¹¹¹In-tilmanocept accumulated in MR-expressing organs and was associated with only low residual blood signal. In addition, ¹¹¹In-tilmanocept uptake was detected in atherosclerotic plaques of mice containing MR-expressing macrophages suggesting that tilmanocept represents a promising tracer for the non-invasive detection of macrophages in atherosclerotic plaques.

Nuclear imaging for patients with a suspicion of infective endocarditis: Be part of the team!

The diagnosis of infective endocarditis (IE) is challenging and requires the association of morphological features suggestive of valvular infection such as the presence of vegetations or abscesses identified usually with echocardiography and positive blood culture or serologies suggestive of systemic bacterial infection. In the past 5 years, several groups confirmed the incremental value of FDG-PET imaging and radiolabeled leukocyte scintigraphy over echocardiography for the diagnosis of IE. Based on the latter studies, the presence of abnormal activity in the perivalvular region on either FDG-PET imaging or radiolabeled leukocyte scintigraphy has been added as a major criterion for the diagnosis of IE in the guidelines recently published. Nuclear physicians should therefore learn not only the imaging criteria in favor of active IE but also the pitfalls of these nuclear imaging techniques in order to give a useful answer to the referring physician for the management of these patients. In fact, the diagnosis of IE is often complex and requires the integration of multiple clinical, biological, and imaging parameters. Multi-disciplinary teams including cardiologists, infectious disease physicians, cardiac surgeons, and radiologists have been therefore set up in several institutions to discuss the diagnosis and management of patients with a suspicion of IE. It is now time for nuclear cardiologists to join the team.

Cardiac Dysautonomia Predicts Long-Term Survival in Hereditary Transthyretin Amyloidosis After Liver Transplantation

OBJECTIVES

This study sought to compare techniques evaluating cardiac dysautonomia and predicting the risk of death of patients with hereditary transthyretin amyloidosis (mATTR) after liver transplantation (LT).

BACKGROUND

mATTR is a multisystemic disease involving mainly the heart and the peripheral nervous system. LT is the reference treatment, and pre-operative detection of high-risk patients is critical. Cardiovascular dysautonomia is commonly encountered in ATTR and may affect patient outcome, although it is not known yet which technique should be used in the field to evaluate it.

METHODS

In a series of 215 consecutive mATTR patients who underwent LT, cardiac dysautonomia was assessed by a dedicated clinical score, time-domain heart rate variability, ¹²³-meta-iodobenzylguanidine heart/mediastinum (¹²³-MIBG H/M) ratio on scintigraphy, and heart rate response to atropine (HRRA).

RESULTS

Patient median age was 43 years, 62% were male and 69% carried the Val30Met mutation. Cardiac dysautonomia was documented by at least 1 technique for all patients but 6 (97%). In univariate analysis, clinical score, ¹²³-MIBG H/M ratio and HRRA were associated with mortality but not heart rate variability. The ¹²³-MIBG H/M ratio and HRRA had greater area under the curve (AUC) of receiver-operating characteristic curves than clinical score and heart rate variability (AUC: 0.787, 0.748, 0.656, and 0.523, respectively). Multivariate score models were then built using the following variables: New York Heart Association functional class, interventricular septum thickness, and either ^123-MIBG H/M ratio (S_MIBG) or HRRA (S_atropine). AUC of S_MIBG and S_atropine were greater than AUC of univariate models, although nonsignificantly (AUC: 0.798 and 0.799, respectively). Predictive powers of S_MIBG, S_atropine, and a reference clinical model (AUC: 0.785) were similar.

CONCLUSIONS

Evaluation of cardiac dysautonomia is a valuable addition for predicting survival of mATTR patients following LT. Among the different techniques that evaluate cardiac dysautonomia, ¹²³-MIBG scintigraphy and heart rate response to atropine had better prognostic accuracy. Multivariate models did not improve significantly prediction of outcome.

Multicentre multi-device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population

AIMS

Hybrid imaging provides a non-invasive assessment of coronary anatomy and myocardial perfusion. We sought to evaluate the added clinical value of hybrid imaging in a multi-centre multi-vendor setting.

METHODS AND RESULTS

Fourteen centres enrolled 252 patients with stable angina and intermediate (20-90%) pre-test likelihood of coronary artery disease (CAD) who underwent myocardial perfusion scintigraphy (MPS), CT coronary angiography (CTCA), and quantitative coronary angiography (QCA) with fractional flow reserve (FFR). Hybrid MPS/CTCA images were obtained by 3D image fusion. Blinded core-lab analyses were performed for CTCA, MPS, QCA and hybrid datasets. Hemodynamically significant CAD was ruled-in non-invasively in the presence of a matched finding (myocardial perfusion defect co-localized with stenosed coronary artery) and ruled-out with normal findings (both CTCA and MPS normal). Overall prevalence of significant CAD on QCA (>70% stenosis or 30-70% with FFR≤0.80) was 37%. Of 1004 pathological myocardial segments on MPS, 246 (25%) were reclassified from their standard coronary distribution to another territory by hybrid imaging. In this respect, in 45/252 (18%) patients, hybrid imaging reassigned an entire perfusion defect to another coronary territory, changing the final diagnosis in 42% of the cases. Hybrid imaging allowed non-invasive CAD rule-out in 41%, and rule-in in 24% of patients, with a negative and positive predictive value of 88% and 87%, respectively.

CONCLUSION

In patients at intermediate risk of CAD, hybrid imaging allows non-invasive co-localization of myocardial perfusion defects and subtending coronary arteries, impacting clinical decision-making in almost one every five subjects.

Value of mechanical dyssynchrony as assessed by radionuclide ventriculography to predict the cardiac resynchronization therapy response

AIMS

To assess the value of mechanical dyssynchrony measured by equilibrium radionuclide angiography (ERNA) in predicting long-term outcome in cardiac resynchronization therapy (CRT) patients.

METHODS AND RESULTS

We reviewed 146 ERNA studies performed in heart failure patients between 2001 and 2011 at our institution. Long-term follow-up focused on death from any cause or heart transplantation. Phase images were computed using the first harmonic Fourier transform. Intra-ventricular dyssynchrony was calculated as the delay between the earliest and most delayed 20% of the left ventricular (LV) (IntraV-20/80) and inter-ventricular dyssynchrony as the difference between LV- and right ventricular (RV)-mode phase angles (InterV). Eighty-three patients (57%) were implanted with a CRT device after ERNA. Median follow-up was 35 [21-50] months. Twenty-four events were observed during the first 41 months. Median baseline ERNA dyssynchrony values were 28 [3 to 46] degrees for intraV-20/80 and 9 [-6 to 24] degrees for interV. Comparing survival between CRT and non-CRT patients according to dyssynchrony status, log-rank tests showed no difference in survival in patients with no ERNA dyssynchrony (P = 0.34) while a significant difference was observed in ERNA patients with high level of mechanical dyssynchrony (P = 0.004).

CONCLUSION

ERNA mechanical dyssynchrony could be of value in CRT patient selection.

Story of Rubidium-82 and Advantages for Myocardial Perfusion PET Imaging

Rubidium-82 has a long story, starting in 1954. After preclinical studies in dogs showing that myocardial uptake of this radionuclide was directly proportional to myocardial blood flow (MBF), clinical studies were performed in the 80s leading to an approval in the USA in 1989. From that time, thousands of patients have been tested and their results have been reported in three meta-analyses. Pooled patient-based sensitivity and specificity were, respectively, 0.91 and 0.90. By comparison with ^99mTc-SPECT, ⁸²Rb PET had a much better diagnostic accuracy, especially in obese patients with body mass index ≥30 kg/m² (85 versus 67% with SPECT) and in women with large breasts. A great advantage of ⁸²Rb PET is its capacity to accurately quantify MBF. Quite importantly, it has been recently shown that coronary flow reserve is associated with adverse cardiovascular events independently of luminal angiographic severity. Moreover, coronary flow reserve is a functional parameter particularly useful in the estimate of microvascular dysfunction, such as in diabetes mellitus. Due to the very short half-life of rubidium-82, the effective dose calculated for a rest/stress test is roughly equivalent to the annual natural exposure and even less when stress-only is performed with a low activity compatible with a good image quality with the last generation 3D PET scanners. There is still some debate on the relative advantages of ⁸²Rb PET with regard to ^99mTc-SPECT. For the last 10 years, great technological advances substantially improved performances of SPECT with its accuracy getting closer to this of ⁸²Rb/PET. Currently, the main advantages of PET are its capacity to accurately quantify MBF and to deliver a low radiation exposure.

Impact of morbid obesity on the kidney function of patients with type 2 diabetes

AIMS

Type 2 diabetes and obesity impair kidney function. We examined their respective contributions to urinary albumin excretion (UAE) and glomerular filtration rate (GFR) in patients with type 2 diabetes and morbid obesity.

METHODS

Cross-sectional, monocentric study of kidney function in patients with type 2 diabetes classified into four body mass index (BMI) stages: non-obese (<25 kg/m(2), n=157); overweight (25 to <30, n=311); obesity (30 to <40, n=310); and morbid obesity (≥40, n=77), with 84 similarly staged controls without diabetes. UAE classes were defined as normal (<30 μg/mg creatinine), microalbuminuria (30-299), or macroalbuminuria (≥300) from 3 consecutive urine samples. GFR was measured by (51)Cr EDTA plasma disappearance (adjusted and unadjusted to 1.73 m(2) body surface area, as obesity increases body surface).

RESULTS

Participants with type 2 diabetes had same age, diabetes duration, and HbA1c across BMI stages. UAE was higher in participants with type 2 diabetes (p<0.0001), and increased with obesity stages (p<0.0001). After adjustment for age, sex, systolic blood pressure and type 2 diabetes status, morbid obesity was associated with a risk of microalbuminuria (OR 1.99, 95%CI 1.35-2.98, p=0.0007) and macroalbuminuria (OR 2.33, 95%CI 1.25-4.22, p=0.006). The body surface adjusted GFR was lower in patients with type 2 diabetes than in controls (p<0.0001), and declined with obesity stages, contrary to controls. An interaction of diabetes and obesity was seen with unadjusted GFR values (p=0.002).

CONCLUSIONS

Morbid obesity interacts with type 2 diabetes to aggravate UAE and GFR. Treatment strategies should focus on both conditions to protect kidney function in these patients.

Variability and uncertainty of 18F-FDG PET imaging protocols for assessing inflammation in atherosclerosis: suggestions for improvement

PET with (18)F-FDG shows promise for the evaluation of metabolic activities in atherosclerotic plaques. Although recommendations regarding the acquisition and measurement protocols to be used for (18)F-FDG PET imaging of atherosclerosis inflammation have been published, there is no consensus regarding the most appropriate protocols, and the image reconstruction approach has been especially overlooked. Given the small size of the targeted lesions, the reconstruction and measurement methods might strongly affect the results. We determined the differences in results due to the protocol variability and identified means of increasing the measurement reliability.

METHODS

An extensive literature search was performed to characterize the variability in atherosclerosis imaging and quantification protocols. Highly realistic simulations of atherosclerotic carotid lesions based on real patient data were designed to determine how the acquisition and processing protocol parameters affected the measured values.

RESULTS

In 49 articles, we identified 53 different acquisition protocols, 51 reconstruction protocols, and 46 quantification methods to characterize atherosclerotic lesions from (18)F-FDG PET images. The most important parameters affecting the measurement accuracy were the number of iterations used for reconstruction and the postfiltering applied to the reconstructed images, which could together make the measured standardized uptake values (SUVs) vary by a factor greater than 3. Image sampling, acquisition duration, and metrics used for the measurements also affected the results to a lesser extent (SUV varying by a factor of 1.3 at most). For an acceptable SUV variability, the lowest bias in SUV was observed using an 8-min acquisition per bed position; ordered-subset expectation maximization reconstruction with at least 120 maximum likelihood expectation maximization equivalent iterations, including a point spread function model using a 1 mm(3) voxel size; and no postfiltering. Because of the partial-volume effect, measurement bias remained greater than 60%. The use and limitations of the target-to-blood activity ratio metrics are also presented and discussed.

CONCLUSION

(18)F-FDG PET protocol harmonization is needed in atherosclerosis imaging. Optimized protocols can significantly reduce the measurement errors in wall activity estimates, but PET systems with higher spatial resolution and advanced partial-volume corrections will be required to accurately assess plaque inflammation from (18)F-FDG PET.

A New Integrated Clinical-Biohumoral Model to Predict Functionally Significant Coronary Artery Disease in Patients With Chronic Chest Pain

BACKGROUND

In patients with chronic angina-like chest pain, the probability of coronary artery disease (CAD) is estimated by symptoms, age, and sex according to the Genders clinical model. We investigated the incremental value of circulating biomarkers over the Genders model to predict functionally significant CAD in patients with chronic chest pain.

METHODS

In 527 patients (60.4 years, standard deviation, 8.9 years; 61.3% male participants) enrolled in the European Evaluation of Integrated Cardiac Imaging (EVINCI) study, clinical and biohumoral data were collected.

RESULTS

Functionally significant CAD-ie, obstructive coronary disease seen at invasive angiography causing myocardial ischemia at stress imaging or associated with reduced fractional flow reserve (FFR < 0.8), or both-was present in 15.2% of patients. High-density lipoprotein (HDL) cholesterol, aspartate aminotransferase (AST) levels, and high-sensitivity C-reactive protein (hs-CRP) were the only independent predictors of disease among 31 biomarkers analyzed. The model integrating these biohumoral markers with clinical variables outperformed the Genders model by receiver operating characteristic curve (ROC) (area under the curve [AUC], 0.70 [standard error (SE), 0.03] vs 0.58 [SE, 0.03], respectively, P < 0.001) and reclassification analysis (net reclassification improvement, 0.15 [SE, 0.07]; P = 0.04). Cross-validation of the ROC analysis confirmed the discrimination ability of the new model (AUC, 0.66). As many as 56% of patients who were assigned to a higher pretest probability by the Genders model were correctly reassigned to a low probability class (< 15%) by the new integrated model.

CONCLUSIONS

The Genders model has a low accuracy for predicting functionally significant CAD. A new model integrating HDL cholesterol, AST, and hs-CRP levels with common clinical variables has a higher predictive accuracy for functionally significant CAD and allows the reclassification of patients from an intermediate/high to a low pretest likelihood of CAD.

Diagnostic value of ⁹⁹mTc-HMPAO-labeled leukocytes scintigraphy in suspicion of post-sternotomy mediastinitis relapse

BACKGROUND

The diagnostic value of radiolabeled white blood cells (WBCs) scintigraphy in mediastinitis is well established, but data in the specific context of relapse are lacking. The present study aimed at evaluation of the diagnostic value of WBCs scintigraphy in suspicion of mediastinitis relapse after prior surgical revision.

METHODS AND RESULTS

Multiple planar incidences of the chest were acquired 4 and 20 hours after injection of labeled WBC in 43 patients. In case of non-conclusive scintigraphy, a second scan was performed 2-3 weeks after the first one. The diagnosis of infection was based on positive bacteriological results; otherwise patients were followed up for at least 1 year. Out of 39 analyzable patients, 17 (44%) were diagnosed with mediastinitis relapse. After the first scan, 32 of 39 were correctly classified, 2 were false positive, and 5 were not conclusive. After completion of an additional scan in the latter 5 patients, 36 of 39 were correctly classified and 3 were false positive (100% sensitivity, 86% specificity, 85% positive predictive value, and 100% negative predictive value).

CONCLUSIONS

In the specific context of suspicion of mediastinitis relapse, the optimal diagnostic value was achieved by repeating the scan when the first one was not conclusive. In this context, a negative WBC scintigraphy was able to rule out infection, with potential major impact on therapeutic management in patients with poor clinical status.

Detection of Apoptotic Cells in a Rabbit Model with Atherosclerosis-Like Lesions Using the Positron Emission Tomography Radiotracer [18F]ML-10

[18F]ML-10 (2-(5-fluoro-pentyl)-2-methylmalonic acid) is a positron emission tomography (PET) radiotracer that accumulates in cells presenting apoptosis-specific membrane alterations. The aim of this study was to test whether [18F]ML-10 allows for the detection of apoptotic cells located in atherosclerotic plaques in rabbits. Atherosclerotic plaques were induced in the aortas of five rabbits, and five additional rabbits were used as controls. Activity in the aortas was quantified in vivo and ex vivo. The localization of [18F]ML-10 to the aortic wall was identified by autoradiography. Average target to background ratios measured in vivo by PET were higher in the aortas of atherosclerotic rabbits compared with those of control rabbits (2.00 ± 0.52 vs 1.22 ± 0.30; p < .05). Differences in [18F]ML-10 uptake between atherosclerotic and control aortas were confirmed ex vivo by PET and gamma counting (23.9 ± 11.2 vs 1.1 ± 2.4 counts/pixel; p <.05; 3.6 ± 2.0 vs 0.05 ± 0.05 % of injected activity/g; p < .05, respectively). Strong correlation was observed between the accumulation of [18F]ML-10 in aortic segments as detected by autoradiography and the number of apoptotic cells on corresponding histologic sections (r2 = .75; p < .05). In this study, we found that atherosclerotic plaques rich in apoptotic cells can be detected with [18F]ML-10 and PET.

Respective performance of 18F-FDG PET and radiolabeled leukocyte scintigraphy for the diagnosis of prosthetic valve endocarditis

Echocardiography plays a key role in the diagnosis of infective endocarditis (IE) but can be inconclusive in patients in whom prosthetic valve endocarditis (PVE) is suspected. The incremental diagnostic value of (18)F-FDG PET and radiolabeled leukocyte scintigraphy in IE patients has already been reported. The aim of this study was to compare the respective performance of (18)F-FDG PET and leukocyte scintigraphy for the diagnosis of PVE in 39 patients.

METHODS

(18)F-FDG PET and leukocyte scintigraphy were performed on 39 consecutive patients admitted because of clinically suspected PVE and inconclusive echocardiography results. The results of (18)F-FDG PET and leukocyte scintigraphy were analyzed separately and retrospectively by experienced physicians masked to the results of the other imaging technique and to patient outcome. The final Duke-Li IE classification was made after a 3-mo follow-up.

RESULTS

Of the 39 patients, 14 were classified as having definite IE, 4 as having possible IE, and 21 as not having IE. The average interval between (18)F-FDG PET and leukocyte scintigraphy was 7 ± 7 d. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 93%, 71%, 68%, 94%, and 80%, respectively, for (18)F-FDG PET and 64%, 100%, 100%, 81%, and 86%, respectively, for leukocyte scintigraphy. Discrepancies between the results of (18)F-FDG PET and leukocyte scintigraphy occurred in 12 patients (31%). In patients with definite IE, 5 had true-positive (18)F-FDG PET results but false-negative leukocyte scintigraphy results. Of these 5 patients, 3 had nonpyogenic microorganism IE (Coxiella or Candida). Of patients for whom endocarditis had been excluded, 6 had true-negative leukocyte scintigraphy results but false-positive (18)F-FDG PET results. These 6 patients had been imaged in the first 2 mo after the last cardiac surgery. The last patient with a discrepancy between (18)F-FDG PET and leukocyte scintigraphy was classified as having possible endocarditis and had positive (18)F-FDG PET results and negative leukocyte scintigraphy results.

CONCLUSION

(18)F-FDG PET offers high sensitivity for the detection of active infection in patients with suspected PVE and inconclusive echocardiography results. Leukocyte scintigraphy offers a higher specificity, however, than (18)F-FDG PET for diagnosis of IE and should be considered in cases of inconclusive (18)F-FDG PET findings or in the first 2 mo after cardiac surgery.

Purification of a low molecular weight fucoidan for SPECT molecular imaging of myocardial infarction

Fucoidans constitute a large family of sulfated polysaccharides with several biochemical properties. A commercial fucoidan from brown algae, containing low molecular weight polysaccharidic species constituted of l-fucose, uronic acids and sulfate groups, was simply treated here with calcium acetate solution. This treatment led to a purified fraction with a yield of 45%. The physicochemical characterizations of the purified fucoidan using colorimetric assay, MALLS, dRI, FT-IR, NMR, exhibited molecular weight distributions and chemical profiles similar for both fucoidans whereas the sulfate and l-fucose contents increased by 16% and 71%, respectively. The biodistribution study in rat of both compounds labeled with ^99mTc evidenced a predominant renal elimination of the purified fucoidan, but the crude fucoidan was mainly retained in liver and spleen. In rat myocardial ischemia-reperfusion, we then demonstrated the better efficiency of the purified fucoidan. This purified sulfated polysaccharide appears promising for the development of molecular imaging in acute coronary syndrome.

Factors affecting the myocardial activity acquired during exercise SPECT with a high-sensitivity cardiac CZT camera as compared with conventional Anger camera

PURPOSE

Injected doses are difficult to optimize for exercise SPECT since they depend on the myocardial fraction of injected activity (MFI) that is detected by the camera. The aim of this study was to analyse the factors affecting MFI determined using a cardiac CZT camera as compared with those determined using conventional Anger cameras.

METHODS

Factors affecting MFI were determined and compared in patients who had consecutive exercise SPECT acquisitions with (201)Tl (84 patients) or (99m)Tc-sestamibi (87 patients) with an Anger or a CZT camera. A predictive model was validated in a group of patients routinely referred for (201)Tl (78 patients) or (99m)Tc-sestamibi (80 patients) exercise CZT SPECT.

RESULTS

The predictive model involved: (1) camera type, adjusted mean MFI being ninefold higher for CZT than for Anger SPECT, (2) tracer type, adjusted mean MFI being twofold higher for (201)Tl than for (99m)Tc-sestamibi, and (3) logarithm of body weight. The CZT SPECT model led to a +1 ± 26% error in the prediction of the actual MFI from the validation group. The mean MFI values estimated for CZT SPECT were more than twofold higher in patients with a body weight of 60 kg than in patients with a body weight of 120 kg (15.9 and 6.8 ppm for (99m)Tc-sestamibi and 30.5 and 13.1ppm for (201)Tl, respectively), and for a 14-min acquisition of up to one million myocardial counts, the corresponding injected activities were only 80 and 186 MBq for (99m)Tc-sestamibi and 39 and 91 MBq for (201)Tl, respectively.

CONCLUSION

Myocardial activities acquired during exercise CZT SPECT are strongly influenced by body weight and tracer type, and are dramatically higher than those obtained using an Anger camera, allowing very low-dose protocols to be planned, especially for (99m)Tc-sestamibi and in non-obese subjects.

Pulp cell tracking by radionuclide imaging for dental tissue engineering

Pulp engineering with dental mesenchymal stem cells is a promising therapy for injured teeth. An important point is to determine the fate of implanted cells in the pulp over time and particularly during the early phase following implantation. Indeed, the potential engraftment of the implanted cells in other organs has to be assessed, in particular, to evaluate the risk of inducing ectopic mineralization. In this study, our aim was to follow by nuclear imaging the radiolabeled pulp cells after implantation in the rat emptied pulp chamber. For that purpose, indium-111-oxine (¹¹¹In-oxine)-labeled rat pulp cells were added to polymerizing type I collagen hydrogel to obtain a pulp equivalent. This scaffold was implanted in the emptied pulp chamber space in the upper first rat molar. Labeled cells were then tracked during 3 weeks by helical single-photon emission computed tomography (SPECT)/computed tomography performed on a dual modality dedicated small animal camera. Negative controls were performed using lysed radiolabeled cells obtained in a hypotonic solution. In vitro data indicated that ¹¹¹In-oxine labeling did not affect cell viability and proliferation. In vivo experiments allowed a noninvasive longitudinal follow-up of implanted living cells for at least 3 weeks and indicated that SPECT signal intensity was related to implanted cell integrity. Notably, there was no detectable systemic release of implanted cells from the tooth. In addition, histological analysis of the samples showed mitotically active fibroblastic cells as well as neoangiogenesis and nervous fibers in pulp equivalents seeded with entire cells, whereas pulp equivalents prepared from lysed cells were devoid of cell colonization. In conclusion, our study demonstrates that efficient labeling of pulp cells can be achieved and, for the first time, that these cells can be followed up after implantation in the tooth by nuclear imaging. Furthermore, it appears that grafted cells retained the label and are viable to follow the repair process. This technique is expected to be of major interest for monitoring implanted cells in innovative therapies for injured teeth.

Role of radiolabelled leucocyte scintigraphy in patients with a suspicion of prosthetic valve endocarditis and inconclusive echocardiography

AIMS

In patients with a suspicion of prosthetic valve endocarditis (PVE), detection of perivalvular infection can be difficult based only on echocardiography. The aim of this retrospective study was to test the interest of radiolabelled leucocyte scintigraphy (LS) for the detection of perivalvular infection in patients with a suspicion of PVE and inconclusive transoesophageal echocardiography (TEE).

METHODS AND RESULTS

LS was performed in 42 patients. The results of LS were classified as positive in the cardiac area (intense or mild), or negative. Macroscopical aspects and bacteriology were obtained from patients who underwent cardiac surgery (n = 10). Clinical outcome was collected in patients treated medically (n = 32). Among patients with intense signal with LS who underwent surgery (n = 6), five had an abscess confirmed during intervention and one, post-operatively. Patients with intense accumulation of radiolabelled leucocytes with scintigraphy and treated medically (n = 3) had a poor outcome: death (n = 1); prosthetic valve dehiscence (n = 1); and recurrent endocarditis (n = 1). Among patients with mild activity with LS (n = 5), one patient developed a large prosthetic valve dehiscence during the follow-up. The remaining four patients were treated medically and did not present any recurrent endocarditis after a median follow-up of 14 months. No abscess was detected in patients with negative LS who underwent surgery (n = 4). Among the patients with negative LS treated medically (n = 24), none presented recurrent endocarditis after a mean follow-up of 15 ± 16 months. Patient management was influenced by the results of LS in 12 out of 42 patients (29%).

CONCLUSION

This study suggests that LS is useful for the identification of perivalvular infection in patients with a suspicion of PVE and inconclusive TEE.

Study of the impact of tissue density heterogeneities on 3-dimensional abdominal dosimetry: comparison between dose kernel convolution and direct Monte Carlo methods

Dose kernel convolution (DK) methods have been proposed to speed up absorbed dose calculations in molecular radionuclide therapy. Our aim was to evaluate the impact of tissue density heterogeneities (TDH) on dosimetry when using a DK method and to propose a simple density-correction method.

METHODS

This study has been conducted on 3 clinical cases: case 1, non-Hodgkin lymphoma treated with (131)I-tositumomab; case 2, a neuroendocrine tumor treatment simulated with (177)Lu-peptides; and case 3, hepatocellular carcinoma treated with (90)Y-microspheres. Absorbed dose calculations were performed using a direct Monte Carlo approach accounting for TDH (3D-RD), and a DK approach (VoxelDose, or VD). For each individual voxel, the VD absorbed dose, D(VD), calculated assuming uniform density, was corrected for density, giving D(VDd). The average 3D-RD absorbed dose values, D(3DRD), were compared with D(VD) and D(VDd), using the relative difference Δ(VD/3DRD). At the voxel level, density-binned Δ(VD/3DRD) and Δ(VDd/3DRD) were plotted against ρ and fitted with a linear regression.

RESULTS

The D(VD) calculations showed a good agreement with D(3DRD). Δ(VD/3DRD) was less than 3.5%, except for the tumor of case 1 (5.9%) and the renal cortex of case 2 (5.6%). At the voxel level, the Δ(VD/3DRD) range was 0%-14% for cases 1 and 2, and -3% to 7% for case 3. All 3 cases showed a linear relationship between voxel bin-averaged Δ(VD/3DRD) and density, ρ: case 1 (Δ = -0.56ρ + 0.62, R(2) = 0.93), case 2 (Δ = -0.91ρ + 0.96, R(2) = 0.99), and case 3 (Δ = -0.69ρ + 0.72, R(2) = 0.91). The density correction improved the agreement of the DK method with the Monte Carlo approach (Δ(VDd/3DRD) < 1.1%), but with a lesser extent for the tumor of case 1 (3.1%). At the voxel level, the Δ(VDd/3DRD) range decreased for the 3 clinical cases (case 1, -1% to 4%; case 2, -0.5% to 1.5%, and -1.5% to 2%). No more linear regression existed for cases 2 and 3, contrary to case 1 (Δ = 0.41ρ - 0.38, R(2) = 0.88) although the slope in case 1 was less pronounced.

CONCLUSION

This study shows a small influence of TDH in the abdominal region for 3 representative clinical cases. A simple density-correction method was proposed and improved the comparison in the absorbed dose calculations when using our voxel S value implementation.