Reconstructive surgery for sequellae of Mycobacterium ulcerans infection (Buruli ulcer) of the upper limb.

INTRODUCTION: Infection by Mycobacterium ulcerans constitutes a neglected tropical disease whose prevalence seems to have overrun those of cutaneous tuberculosis and leprosy. Its aggressivity depends on a mycolactone toxin. Lesions may involve skin, tendon and bone with a large spectrum of manifestations: non-ulcerative (papules, nodules, plaques), ulcerative and oedematous presentations as well as osteomyelitis with muscular contraction and ankylosis. Upper limbs account for more than two thirds of the infection sites. Surgical treatment may involve tendon transpositions, partial and total skin grafts. Amputation is relegated to extreme cases. MATERIAL AND METHODS: Selected iconography from patients during the last 15 years is presented. At least 1500 cases had partial skin grafts (anterior thigh). Total skin grafts (inguinal region) were used in about 200 cases. Complex lesions involved 9 ilioinguinal flaps (5 boys, 4 girls, mean age 11.2 years, range 2-16 years), 5 tendon transfers (4 boys, one girl, mean age 15.4 years, range 12-19 years) and 3 resections of the first carpal row (2 girls, 1 boy, mean age 8 years, range 4-15 years). RESULTS AND DISCUSSION: Out of 9 ilioinguinal flaps mild, marginal necrosis was the only complication in 2 patients without flap loss. Mean hospital stay was 26.44 days (range, 18-41 days), with return to full weight-bearing after a mean of 12 weeks (range 9-25 weeks) after discharge. Functional thumb opposition to allow pencil prehension was achieved in all three cases of resection of first carpal row resection without postoperative complications.

Validation of the Monte Carlo simulator GATE for indium-111 imaging.

Monte Carlo simulations are useful for optimizing and assessing single photon emission computed tomography (SPECT) protocols, especially when aiming at measuring quantitative parameters from SPECT images. Before Monte Carlo simulated data can be trusted, the simulation model must be validated. The purpose of this work was to validate the use of GATE, a new Monte Carlo simulation platform based on GEANT4, for modelling indium-111 SPECT data, the quantification of which is of foremost importance for dosimetric studies. To that end, acquisitions of (111)In line sources in air and in water and of a cylindrical phantom were performed, together with the corresponding simulations. The simulation model included Monte Carlo modelling of the camera collimator and of a back-compartment accounting for photomultiplier tubes and associated electronics. Energy spectra, spatial resolution, sensitivity values, images and count profiles obtained for experimental and simulated data were compared. An excellent agreement was found between experimental and simulated energy spectra. For source-to-collimator distances varying from 0 to 20 cm, simulated and experimental spatial resolution differed by less than 2% in air, while the simulated sensitivity values were within 4% of the experimental values. The simulation of the cylindrical phantom closely reproduced the experimental data. These results suggest that GATE enables accurate simulation of (111)In SPECT acquisitions.

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.