Multidrug-resistant Gram-negative osteomyelitis: a 10-year study.

AIM: Few series of osteomyelitis due to multi-drug (MDR) or extensively-drug resistant (XDR) gram-negative bacteria exist. A retrospective study of MDR and XDR gram-negative osteomyelitis cases was performed, aiming to investigate causative organisms, proper surgical and medical management, as well as outcome. PATIENTS AND METHODS: All patients, treated at the University hospital of Crete between 2007 and 2016 for acute osteomyelitis, due to MDR or XDR gram-negative pathogens were evaluated. RESULTS: A total of 14 patients (8 males) were identified with a mean age of 50.6 years. Five Acinetobacter baumanii cases, 3 XDR and 2 MDR, were found. Furthermore, 3 MDR Klebsiella pneumoniae and 3 MDR Enterobacter cloacae isolates were identified. Additionally, 2 MDR Escherichia coli, as well as 2 Pseudomonas aeruginosa, 1 XDR and 1 MDR, were isolated. One case of Roseomonas gilardii was also identified. In 5 cases the same pathogen was also isolated from blood. Five out of the 14 patients were smokers, 6 were suffering severe injury, 4 had diabetes-mellitus, 2 chronic renal disease and 2 were obese. Most causative organisms had hospital origin. All patients received first line empirical combination antimicrobial treatment, proven effective in 4. Thirteen patients were also subjected to surgical treatment. The study included mainly young individuals, most likely due to the high incidence of traffic accidents involving young adults in Crete. CONCLUSIONS: Antimicrobial regimens are important supplements to surgical treatment of acute osteomyelitis. However, due to emergence of resistant microorganisms, compliance with strict rules of antimicrobial strategy is of utmost importance.

Automatic deformable registration of histological slides to µCT volume data.

Localizing a histological section in the three-dimensional dataset of a different imaging modality is a challenging 2D-3D registration problem. In the literature, several approaches have been proposed to solve this problem; however, they cannot be considered as fully automatic. Recently, we developed an automatic algorithm that could successfully find the position of a histological section in a micro computed tomography (µCT) volume. For the majority of the datasets, the result of localization corresponded to the manual results. However, for some datasets, the matching µCT slice was off the ground-truth position. Furthermore, elastic distortions, due to histological preparation, could not be accounted for in this framework. In the current study, we introduce two optimization frameworks based on normalized mutual information, which enabled us to accurately register histology slides to volume data. The rigid approach allocated 81 % of histological sections with a median position error of 8.4 µm in jaw bone datasets, and the deformable approach improved registration by 33 µm with respect to the median distance error for four histological slides in the cerebellum dataset.

An anthropomorphic breathing phantom of the thorax for testing new motion mitigation techniques for pencil beam scanning proton therapy.

Motion-induced range changes and incorrectly placed dose spots strongly affect the quality of pencil-beam-scanned (PBS) proton therapy, especially in thoracic tumour sites, where density changes are large. Thus motion-mitigation techniques are necessary, which must be validated in a realistic patient-like geometry. We report on the development and characterisation of a dynamic, anthropomorphic, thorax phantom that can realistically mimic thoracic motions and anatomical features for verifications of proton and photon 4D treatments. The presented phantom is of an average thorax size, and consists of inflatable, deformable lungs surrounded by a skeleton and skin. A mobile 'tumour' is embedded in the lungs in which dosimetry devices (such as radiochromic films) can be inserted. Motion of the tumour and deformation of the thorax is controlled via a custom made pump system driving air into and out of the lungs. Comprehensive commissioning tests have been performed to evaluate the mechanical performance of the phantom, its visibility on CT and MR imaging and its feasibility for dosimetric validation of 4D proton treatments. The phantom performed well on both regular and irregular pre-programmed breathing curves, reaching peak-to-peak amplitudes in the tumour of <20 mm. Some hysteresis in the inflation versus deflation phases was seen. All materials were clearly visualised in CT scans, and all, except the bone and lung components, were MRI visible. Radiochromic film measurements in the phantom showed that imaging for repositioning was required (as for a patient treatment). Dosimetry was feasible with Gamma Index agreements (4%/4 mm) between film dose and planned dose >90% in the central planes of the target. The results of this study demonstrate that this anthropomorphic thorax phantom is suitable for imaging and dosimetric studies in a thoracic geometry closely-matched to lung cancer patients under realistic motion conditions.