An overview of recent developments in FLUKA PET tools.

The new developments of the FLUKA Positron-Emission-Tomography (PET) tools are detailed. FLUKA is a fully integrated Monte Carlo (MC) particle transport code, used for an extended range of applications, including Medical Physics. Recently, it provided the medical community with dedicated simulation tools for clinical applications, including the PET simulation package. PET is a well-established imaging technique in nuclear medicine, and a promising method for clinical in vivo treatment verification in hadrontherapy. The application of clinically established PET scanners to new irradiation environments such as hadrontherapy requires further experimental and theoretical research to which MC simulations could be applied. The FLUKA PET tools, besides featuring PET scanner models in its library, allow the configuration of new PET prototypes via the FLUKA Graphical User Interface (GUI) Flair. Both the beam time structure and scan time can be specified by the user, reproducing PET acquisitions in time, in a particle therapy scenario. Furthermore, different scoring routines allow the analysis of single and coincident events, and identification of parent isotopes generating annihilation events. Two reconstruction codes are currently supported: the Filtered Back-Projection (FBP) and Maximum-Likelihood Expectation Maximization (MLEM), the latter embedded in the tools. Compatibility with other reconstruction frameworks is also possible. The FLUKA PET tools package has been successfully tested for different detectors and scenarios, including conventional functional PET applications and in beam PET, either using radioactive sources, or simulating hadron beam irradiations. The results obtained so far confirm the FLUKA PET tools suitability to perform PET simulations in R&D environment.

Peripheral neuropathy is a common manifestation of mitochondrial diseases: a single-centre experience.

BACKGROUND AND PURPOSE: Peripheral neuropathy in mitochondrial diseases (MDs) may vary from a subclinical finding in a multisystem syndrome to a severe, even isolated, manifestation in some patients. METHODS: To investigate the involvement of the peripheral nervous system in MDs extensive electrophysiological studies were performed in 109 patients with morphological, biochemical and genetic diagnosis of MD [12 A3243G progressive external ophthalmoplegia (PEO)/mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), 16 myoclonic epilepsy with ragged-red fibres (MERRF), four mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), 67 PEO with single or multiple deletions of mitochondrial DNA, 10 others]. RESULTS: A neuropathy was found in 49 patients (45%). The incidence was very high in MNGIE (100%), MELAS (92%) and MERRF (69%), whilst 28% of PEO patients had evidence of peripheral involvement. The most frequent abnormality was a sensory axonal neuropathy found in 32/49 patients (65%). A sensory-motor axonal neuropathy was instead detected in 16% of the patients and sensory-motor axonal demyelinating neuropathy in 16%. Finally one Leigh patient had a motor axonal neuropathy. It is interesting to note that the great majority had preserved tendon reflexes and no sensory disturbances. CONCLUSIONS: In conclusion, peripheral involvement in MD is frequent even if often mild or asymptomatic. The correct identification and characterization of peripheral neuropathy through electrophysiological studies represents another tile in the challenge of MD diagnosis.