Francis Bouchet

Lipid nanocapsules loaded with rhenium-188 reduce tumor progression in a rat hepatocellular carcinoma model.

Background Due to their nanometric scale (50 nm) along with their biomimetic properties, lipid nanocapsules loaded with Rhenium-188 (LNC188Re-SSS) constitute a promising radiopharmaceutical carrier for hepatocellular carcinoma treatment as its size may improve tumor penetration in comparison with microspheres devices. This study was conducted to confirm the feasibility and to assess the efficacy of internal radiation with LNC188Re-SSS in a chemically induced hepatocellular carcinoma rat model. Methodology/Principal Findings Animals were treated with an injection of LNC188Re-SSS (80 MBq or 120 MBq). The treated animals (80 MBq, n = 12; 120 MBq, n = 11) were compared with sham (n = 12), blank LNC (n = 7) and 188Re-perrhenate (n = 4) animals. The evaluation criteria included rat survival, tumor volume assessment, and vascular endothelial growth factor quantification. Following treatment with LNC188Re-SSS (80 MBq) therapeutic efficiency was demonstrated by an increase in the median survival from 54 to 107% compared with control groups with up to 7 long-term survivors in the LNC188Re-SSS group. Decreased vascular endothelial growth factor expression in the treated rats could indicate alterations in the angiogenesis process. Conclusions/Significance Overall, these results demonstrate that internal radiation with LNC188Re-SSS is a promising new strategy for hepatocellular carcinoma treatment.

Calibration Test of PET Scanners in a Multi-Centre Clinical Trial on Breast Cancer Therapy Monitoring Using 18F-FLT

A multi-centre trial using PET requires the analysis of images acquired on different systems We designed a multi-centre trial to estimate the value of 18F-FLT-PET to predict response to neoadjuvant chemotherapy in patients with newly diagnosed breast cancer. A calibration check of each PET-CT and of its peripheral devices was performed to evaluate the reliability of the results. Material and Methods 11 centres were investigated. Dose calibrators were assessed by repeated measurements of a 68Ge certified source. The differences between the clocks associated with the dose calibrators and inherent to the PET systems were registered. The calibration of PET-CT was assessed with an homogeneous cylindrical phantom by comparing the activities per unit of volume calculated from the dose calibrator measurements with that measured on 15 Regions of Interest (ROIs) drawn on 15 consecutive slices of reconstructed filtered back-projection (FBP) images. Both repeatability of activity concentration based upon the 15 ROIs (ANOVA-test) and its accuracy were evaluated. Results There was no significant difference for dose calibrator measurements (median of difference −0.04%; min = −4.65%; max = +5.63%). Mismatches between the clocks were less than 2 min in all sites and thus did not require any correction, regarding the half life of 18F. For all the PET systems, ANOVA revealed no significant difference between the activity concentrations estimated from the 15 ROIs (median of difference −0.69%; min = −9.97%; max = +9.60%). Conclusion No major difference between the 11 centres with respect to calibration and cross-calibration was observed. The reliability of our 18F-FLT multi-centre clinical trial was therefore confirmed from the physical point of view. This type of procedure may be useful for any clinical trial involving different PET systems.

Delayed ( 18 F)FDG PET imaging of central nervous system lymphoma: is PET better than MRI?

The use of [F]FDG PET in primary central nervous system lymphoma was the subject of a recent article in this journal [1]. The authors concluded that MRI plays a crucial role in CNS lymphoma, but that [F]FDG PET could yield additional information. It is well known that the use of [F]FDG to study brain tumour is hindered by the high glucose affinity for the grey matter. Recently, Spence [2] proved that delayed imaging of brain tumours could enhance the tumour to background contrast. In our institution we currently perform early (1 h post injection) and late (6 h) images for every patient with suspected malignant brain disease. This 73-year-old woman was referred for the evaluation of relapse of a diffuse large B-cell lymphoma initially localised in the abdomen and bone (T3–T11). She was treated with apparent success with six courses of RMBACOD [rituximab (Mabthera, Rituxan)–methotrexate, bleomycin, adriamycin, cyclophosphamide, oncovin, dexamethasone]. Ten months later, the patient experienced numbness of her right arm and a cerebellar syndrome. MRI revealed a tumour in the cerebellum, and a possible second lesion in the right part of the tentorium cerebelli. A PET scan was performed 14 days thereafter, using 350 MBq [F]FDG. For early acquisition, scanning was performed in seven bed positions, at 4 min per bed position, in 2D mode using a GE Discovery ST. The late acquisition consisted of a 45 min bed position in 3D mode. Figure a shows the maximum intensity projection (MIP) image of the brain in the early phase. Thoracic and abdominal examination did not reveal any abnormality. Figure b shows the late MIP image. The tomogram (c) confirmed the three lesions suspected on MIP imaging, in the left cerebellum, left temporal pole and right tentorium cerebelli. A small lesion at the anterior edge of the right cerebellum could also be suspected. The use of [F]FDG PET in CNS Lymphoma has already been advocated, but most of these articles used only early imaging [1, 3–6].

American consensus recommendations for gastric scintigraphy: curve fitting with only a few points remains an easy and accurate method to obtain reliable and reproducible gastric emptying estimates.

BackgroundIn 2008, American consensus recommendations for performing gastric emptying (GE) scintigraphy were published. It was recommended that data are acquired only at 0, 1, 2, and 4 h and that the results are expressed as percentages of meal retention. Until now, it was established that the GE time–activity curves should have many points (every 10, 15, or 20 min) to reflect the GE process accurately and to be optimally adjusted by a mathematical model. In this study, we have evaluated the curve fitting using only a few points as proposed by the consensus protocol. Materials and methodsGE scintigraphy tests of 224 patients were retrospectively analyzed. Two curve fittings were done for each patient, either using data acquired every 20 min or using data acquired every hour. A comparison of these two methods was made based on the values of the computed GE parameters. ResultsWe observed strong correlations between the two methods (r=0.81–0.99, P<0.05). Using the Bland–Altman analysis, more than 95% of the differences were included in the mean difference 95% confidence interval. The mean differences were weak with a relatively small SD and Cohens k coefficients ranging from 0.84 to 0.93, indicating an excellent agreement between the two methods. ConclusionOur results showed the feasibility and accuracy of curve fitting using only a few points. The curve fitting is easy to perform and allows the computation of reliable and reproducible parameters that reflect the whole GE process.

Minimum deconvolution and 0 - 90° subset, new algorithms for emission tomography with large hole collimator

Radionuclide imaging is right now one of the poorest medical imaging modalities (MIM). With a sensitivity of 10-4 and a 1-1.5 cm spatial resolution it presents the worst performance. Its usefulness must be great to survive beside the others MIM. Emission tomography with large hole collimator was proposed to improve these figures. Interesting results has already been obtained but a robust algorithm is needed to give a practical proof of the superiority of the approach. This paper unveils new ways to deconvolute and reconstruct these tomographic data, both in noise free and in low photon counts conditions. Comparison with thin parallel hole collimator is also depicts.