Hatem Boulahdour

The Role of Delayed 18F-FDG PET Imaging in the Follow-up of Patients with Alveolar Echinococcosis

18F-FDG PET has already proved its usefulness in the follow-up of patients with alveolar echinococcosis (AE) and has been proposed as a surrogate marker for therapeutic decisions on structured treatment interruption by benzimidazoles. However, standard PET acquisition (1 h after 18F-FDG injection) lacks sensitivity, and the parasite may stay viable even if 18F-FDG perilesional uptake has disappeared. The aim of our study was to evaluate the usefulness of delayed 18F-FDG PET in the management of AE patients. Methods: During a 6-y period, 120 PET scans using 18F-FDG were obtained for 70 AE patients treated by benzimidazoles, without selection. All patients underwent whole-body imaging on a PET/CT device 1 h after 18F-FDG injection (4 MBq/kg), as well as an acquisition focused on the liver 3 h after the injection. We also analyzed the results of serologic tests. Results: Of the 57 scans considered negative at the standard acquisition, 13 (22.8%) became clearly positive at the delayed acquisition, and 6 (10.5%) became indeterminate at the delayed acquisition. Furthermore, 20 of 22 scans interpreted as indeterminate at the standard acquisition were considered positive because of clear perilesional 18F-FDG uptake at the delayed acquisition. Thus, delayed acquisition changed the interpretation in 32.5% of cases. Moreover, of 44 patients treated by benzimidazoles and followed for more than 2 y by regular 18F-FDG PET scans and specific AE serology, 11 (25%) presented pathologic 18F-FDG uptake at the delayed acquisition but not at the standard one. In these patients, the treatment was continued despite negative results on standard 18F-FDG PET and negative serologic findings. On the other hand, in 7 patients with negative delayed 18F-FDG PET and negative serology, the treatment was safely interrupted with no evidence of disease recurrence during 8–37 mo (mean, 23 mo). Conclusion: Our study clearly demonstrated that delayed 18F-FDG PET greatly facilitated the differentiation between active and inactive liver lesions in AE patients. Also, our results strongly suggested that the combination of delayed 18F-FDG PET and specific serology would prevent most of the recurrences observed after premature interruption of the treatment based only on standard 18F-FDG PET.

The value of combined radionuclide and magnetic resonance imaging in the diagnosis and conservative management of minimal or localized osteomyelitis of the foot in diabetic patients.

Early diagnosis of osteomyelitis is helpful for a successful conservative treatment. The value of bone scanning combined with granulocytes labeled with hexamethylpropylene amine oxime (HMPAO) granulocyte-Tc99m (GN) radionuclide imaging (combined [RI]) with magnetic resonance imaging (MRI) for the diagnosis of osteomyelitis was assessed in 24 diabetic patients with foot ulcers. Evidence of osteomyelitis was based on the presence of at least one of the following criteria: (1) clinical bone involvement, (2) radiological bone involvement, (3) both positive combined RI and MRI, and (4) evidence of clinical bone involvement during the follow-up period. Thirteen patients had osteomyelitis. Seven patients had clinical bone involvement (sensitivity, 54%), five had radiological bone involvement (sensitivity, 38%), and 10 had positive combined RI for osteomyelitis (sensitivity, 77%). MRI demonstrated a higher sensitivity (100%). The specificity for combined RI and MRI was 82%. These results lead to a new diagnostic strategy for the early detection of minimal or localized osteomyelitis to avoid amputations. MRI is most appropriate following a negative x-ray in determining whether to treat osteomyelitis, since a negative MRI result rules out osteomyelitis. Antibiotic therapy should be used in the case of a positive MRI result, but Charcot joint disease can lead to false-positive MRI results. In this case, combined RI should be performed.

Utility of 18F-fluoro-dexoxyglucose positron emission tomography for the diagnosis of polymyalgia rheumatica: a controlled study

OBJECTIVES To compare (18)F-fluoro-dexoxyglucose PET/CT (FDG-PET/CT) findings in patients with polymyalgia rheumatica (PMR) and controls without rheumatologic disease. METHODS We retrospectively included 50 patients with a diagnosis of PMR as well as 53 patients with a neoplasm as a control group. All patients underwent FDG-PET/CT. Seventeen hotspots were analysed. We performed a semi-quantitative analysis of FDG uptake (4-point score from 0 to 3). The cut-offs for the number of sites with high activity and for FDG uptake score were assessed using receiver operating characteristics curves and odds ratios (ORs). RESULTS The two groups were comparable for the median patient age (69.3 years for PMR vs 68.1 for controls). Significant differences between the two groups were found for FDG uptake score (1.12 vs 0.34, P < 0.00001) and for the number of sites with significant uptake (score ⩾ 2): 6.36 sites vs 1.49 sites (P < 0.00001). The presence of three or more sites with significant uptake was correlated with the diagnosis of PMR with 74% sensitivity and 79% specificity (OR = 10.8). For the FDG uptake score, the cut-off was 0.53 (sensitivity 80%, specificity 77%, OR = 13.6). We found significant differences in all sites for FDG uptake score and the number of sites with significant uptake, particularly marked for shoulders, ischial tuberosities and interspinous bursitis (P < 0.00001 for FDG uptake score). CONCLUSION Our results suggest that the number of sites with significant FDG uptake and the uptake score could be relevant criteria for the diagnosis of PMR.

Positron emission tomography: The ideal tool in polymyalgia rheumatica?

Joint Bone Spine - In Press.Proof corrected by the author Available online since dimanche 22 juin 2014

18F-fluoride PET/CT aspect of an unusual case of Erdheim-Chester disease with histologic features of Langerhans cell histiocytosis.

We report the case of a 63-year-old woman with Erdheim-Chester disease (ECD) and histologic features of Langerhans cell histiocytosis, both extremely rare histiocytic proliferations responsible of skeletal and extraskeletal involvement. 18F-Fluoride PET/CT revealed multiple intense focal uptake scattered throughout the skeleton. We also performed an 18F-FDG PET/CT which point out visceral and vascular involvement. This case illustrates the interest of PET/CT in ECD, a rare polymorphus and systemic disease, and in our knowledge, this is the first reported illustration of 18F-fluoride PET/CT findings in this pathology.

Feasibility of data-driven cardiac respiratory motion correction of myocardial perfusion CZT SPECT: A pilot study

BackgroundWe developed a data-driven respiratory motion (RM) correction method (REGAT program) for multiple-pinhole detector CZT SPECT. We verified its clinical feasibility with myocardial perfusion imaging (MPI) and studied its impact on image characteristics.MethodsThis retrospective study included 18 patients having stress/rest 99mTc-Tetrofosmin MPI SPECT. List mode was acquired on CZT SPECT and processed with REGAT. REGAT generates reconstructed RM-gated volumes that are summed either without realignment (NR-SPECT) or after realignment (R-SPECT). For both stress and rest, we calculated the maximal RM in the 3 axis, and image characteristics of both R-SPECT and NR-SPECT: minimum left ventricular (LV) cavity counts (LV-Min), maximum LV myocardial counts (LV-Max), LV contrast, and FWHM of both anterior (FWHM-ant) and inferior (FWHM-inf) LV myocardial walls.ResultsAt both stress and rest, cranio-caudal motion was the dominant axial movement and REGAT had a positive impact on image characteristics as reflected by variations between R-SPECT and NR-SPECT in LV-Min, LV-Max, FWHM-ant, FWHM-inf, and contrast. These latter were well correlated to the amplitude of cranio-caudal motion at both stress and rest.ConclusionsData-driven RM correction of MPI acquired with CZT SPECT is clinically feasible and easily applicable. It presents interesting impact on image characteristics.

Encapsulation capacity and natural payload delivery of an anticancer drug from boron nitride nanotube

The behavior of confined anticancer carboplatin (CPT) molecules in a single (10, 10) boron nitride nanotube (BNNT) was studied by means of molecular dynamics simulations. Our study revealed a very large storage capacity of BNNT. Analysis of the energy profiles depending on the number of confined molecules, and on their spatial organization allowed us to quantify the ability of BNNT to vectorize CPT. Indeed, BNNT despite its small radius presented a large inner volume that favored stable encapsulation of multiple active anticancer molecules. Moreover, in our molecular dynamics simulations, the empty BNNT and the BNNT filled with CPT diffused spontaneously to the cell membrane and were able to passively enter inside lipid bilayers by a lipid-assisted mechanism. This property has been used to deliver naturally anticancer drugs to cellular targets. Using this enhanced drug delivery system, we have provided a definitive solution to the problem of drug release and have thus opened up a new way of targeting cancer cells. Indeed, regardless of the mode of action of the platinum complex towards the cell, the delivery of the drug on site should limit the side effects of the drug.

Applicability of data-driven respiratory motion correction to CZT SPECT myocardial perfusion imaging in the clinical setting: The birth of an old wish

An asymptomatic 81-year-old man was addressed for a one-day stress/rest Tc Myoview MPI SPECT before resuming physical exercise. Invasive coronary angiography performed 10 years before showed 1-vessel CAD with a severe stenosis of the right coronary artery that was treated by percutaneous transluminal coronary angioplasty. He had no previously known myocardial infarction (MI). Rest ECG was normal. Exercise stress test (180 watts, 96% THR) was clinically and electrographically (ECG) negative. Noteworthy stress and rest CZT SPECT were performed without any modification of the routinely used acquisition protocol (3 MBq/kg at stress and 9 MBq/kg at rest, 5-min acquisition duration, and prone position). LV regional motion and thickness were normal at both poststress and rest. The study (non-corrected for RM) showed a mild inferior myocardial perfusion defect (MPD) at stress that was not reversible at rest (Figure 1 and 2). The inferior LV non-reversible MPD was considered probably normal and rather related to photon attenuation. The stress and rest list mode acquisitions were processed offline with REGAT, a data-driven cardiac RM correction program (videos 1 and 2 in

Theoretical study of the interaction between carbon nanotubes and carboplatin anticancer molecules

Full DFT calculations were carried out to study the interactions between single-wall functionalized carbon-based metallic nanotubes (CNTs) and carboplatin anticancer drugs. The geometry of the CNT–carboplatin was optimized considering different molecular configurations on inner and outer surfaces of the nanotubes. Simulation results show that the most stable physisorption state for molecules is to be located inside the nanotubes in a parallel configuration. Furthermore, we demonstrated that the molecular physisorption was reinforced as soon as the number of encapsulated carboplatin molecules increased, leading to a favored state where the nanovector is filled by the drug. Moreover, all theoretical results show that the therapeutic agent is not affected when it is attached onto CNTs.

Development of a specific tracer for metabolic imaging of alveolar echinococcosis: A preclinical study

Positron emission tomography (PET)-computed tomography (CT) using [18F]-fluorodeoxyglucose (FDG) (FDG-PET/CT) is a valuable method for initial staging and follow up of patients with alveolar echinococcosis (AE). However, the cells responsible for FDG uptake have not been clearly identified. The main goal of our study was to evaluate the uptake of PET tracers by the cells involved in the host-parasite reaction around AE lesions as the first step to develop a specific PET tracer that would allow direct assessment of parasite viability in AE. Candidate molecules ([18F]-fluorotyrosine (FET), [18F]-fluorothymidine (FLT), and [18F]-fluorometylcholine (FMC), were compared to FDG by in vitro studies on human leukocytes and parasite vesicles. Our results confirmed that FDG was mainly consumed by immune cells and showed that FLT was the best candidate tracer for parasite metabolism. Indeed, parasite cells exhibited high uptake of FLT. We also performed PET/CT scans in mice infected intraperitoneally with E. multilocularis metacestodes. PET images showed no FDG or FLT uptake in parasitic lesions. This preliminary study assessed the metabolic activity of human leukocytes and AE cells using radiolabeling. Future studies could develop a specific PET tracer for AE lesions to improve lesion detection and echinococcosis treatment in patients. Our results demonstrated that a new animal model is needed for preclinical PET imaging to better mimic human hepatic and/or periparasitic metabolism.