Brain MR findings in patients treated with particle therapy for skull base tumors.

Nowadays, hadrontherapy is increasingly used for the treatment of various tumors, in particular of those resistant to conventional radiotherapy. Proton and carbon ions are characterized by physical and biological features that allow a high radiation dose to tumors, minimizing irradiation to adjacent normal tissues. For this reason, radioresistant tumors and tumors located near highly radiosensitive critical organs, such as skull base tumors, represent the best target for this kind of therapy. However, also hadrontherapy can be associated with radiation adverse effects, generally referred as acute, early-delayed and late-delayed. Among late-delayed effects, the most severe form of injury is radiation necrosis. There are various underlying mechanisms involved in the development of radiation necrosis, as well as different clinical presentations requiring specific treatments. In most cases, radiation necrosis presents as a single focal lesion, but it can be multifocal and involve a single or multiple lobes simulating brain metastasis, or it can also involve both cerebral hemispheres. In every case, radiation necrosis results always related to the extension of radiation delivery field. Multiple MRI techniques, including diffusion, perfusion imaging, and spectroscopy, are important tools for the radiologist to formulate the correct diagnosis. The aim of this paper is to illustrate the possible different radiologic patterns of radiation necrosis that can be observed in different MRI techniques in patients treated with hadrontherapy for tumors involving the skull base. The images of exemplary cases of radiation necrosis are also presented.

Lemierre Syndrome: Clinical Update and Protocol for a Systematic Review and Individual Patient Data Meta-analysis.

Lemierre syndrome usually affects otherwise healthy adolescents or young adults and occurs at an overall rate of 1 to 10 cases per million person-years with an estimated fatality rate of 4 to 9%. Diagnostic criteria remain debated and include acute neck/head bacterial infection (often tonsillitis caused by anaerobes at high potential for sepsis and vascular invasion, notably Fusobacterium necrophorum) complicated by local vein thrombosis, usually involving the internal jugular vein, and systemic septic embolism. Medical treatment is based on antibiotic therapy with anaerobic coverage, anticoagulant drugs and supportive care in case of sepsis. Surgical procedures can be required, including drainage of the abscesses, tissue debridement and jugular vein ligation. Evidence for clinical management is extremely poor in the absence of any adequately sized study with clinical outcomes. In this article, we illustrate two cases of Lemierre syndrome not caused by Fusobacterium necrophorum and provide a clinically oriented discussion on the main issues on epidemiology, pathophysiology and management strategies of this disorder. Finally, we summarize the study protocol of a proposed systematic review and individual patient data meta-analysis of the literature. Our ongoing work aims to investigate the risk of new thromboembolic events, major bleeding or death in patients diagnosed with Lemierre syndrome, and to better elucidate the role of anticoagulant therapy in this setting. This effort represents the starting point for an evidence-based treatment of Lemierre syndrome built on multinational interdisciplinary collaborative studies.

Brain Imaging Findings and Neurologic Complications after Allogenic Hematopoietic Stem Cell Transplantation in Children.

Hematopoietic stem cell transplantation (HSCT) is the only therapy for a subset of patients with malignant and nonmalignant diseases. Central nervous system (CNS) complications continue to be an important cause of morbidity and significantly contribute to mortality after HSCT. These complications include infections, cerebrovascular lesions, therapy-induced diseases, metabolic disturbances, and post-HSCT carcinogenesis. Following HSCT, three phases can be identified on the basis of the patient's immune status: the pre-engraftment period (<30 days after HSCT), the early postengraftment period (30-100 days after HSCT), and the late postengraftment period (>100 days after HSCT). There is a distinct relationship between the patient's degree of immunodeficiency after HSCT and the incidence of various complications that may occur. Early diagnosis of CNS complications is crucial for successful management and a good prognosis, and computed tomography and magnetic resonance imaging play an important role in achieving these goals. The global increase in the use of HSCT requires radiologists to be familiar with CNS complications, their relationship to the patient's immune status, and their imaging appearances. This article describes the clinical background of HSCT; reviews the incidence, causes, and timeline of brain complications in children who underwent allogenic HSCT; and identifies the characteristic imaging findings of these disorders. ©RSNA, 2018.

Median nerve evaluation by shear wave elastosonography: impact of "bone-proximity" hardening artifacts and inter-observer agreement.

PURPOSE: Peripheral nerves frequently travel close to the bone surface and are, therefore, prone to elastosonographic "bone-proximity" hardening artifacts. The impact of these artifacts on quantitative measurements of median nerve stiffness performed by shear wave elastosonography has not been explored. Our aim was to assess normal median nerve stiffness values at various locations. MATERIALS AND METHODS: Thirty-six healthy volunteers (24 women and 12 men) aged between 25 and 40 years were evaluated. Two operators performed the evaluation: one expert (6 years of ultrasound experience) and one inexperienced operator (6 months' experience). The nerve was sampled in cross-section at three different locations: mid-forearm, immediately before the carpal tunnel and within the tunnel. The ultrasound scanner was equipped with a 14-MHz linear probe. The Shear Wave module was activated in one-shot mode. Measurements were performed using a ROI corresponding to the diameter of the nerve. RESULTS: The mean values of stiffness of the medial nerve were 32.26 kPa ± 18.60 within the carpal tunnel, 22.20 kPa ± 9.84 at the carpal tunnel inlet and 7.62 kPa ± 7.38 in the forearm. Inter-observer agreement assessed using the intraclass correlation coefficient (ICC) was "moderate" within the carpal tunnel (ICC = 0.44), "moderate" at the carpal tunnel inlet (ICC = 0.41) and "fair" in the forearm (ICC = 0.38). CONCLUSIONS: The stiffness of the median nerve progressively increases in its distal portions, where the nerve approaches the bone surface. Inter-observer agreement was generally good (from fair to moderate).

High-frame rate vector flow imaging of the carotid bifurcation.

Carotid artery atherosclerotic disease is still a significant cause of cerebrovascular morbidity and mortality. A new angle-independent technique, measuring and visualizing blood flow velocities in all directions, called vector flow imaging (VFI) is becoming available from several vendors. VFI can provide more intuitive and quantitative imaging of vortex formation, which is not clearly distinguishable in the color Doppler image. VFI, as quantitative method assessing disturbed flow patterns of the carotid bifurcation, has the potential to allow better understanding of the diagnostic value of complex flow and to enhance risk stratification. This pictorial review article will show which new information VFI adds for the knowledge of hemodynamics in comparison to the conventional ultrasound techniques. TEACHING POINTS: • VFI is an angle-independent technique measuring flow velocities in all directions. • This kind of VFI is based on a plane wave multidirectional excitation technique. • VFI allows quantitative assessment of carotid streamlines progression and visualizes vorticity. • VFI does not allow a precise comprehension of streamlines' 3D shape. • VFI allows a better understanding of carotid artery complex flows.

Haemorrhagic presentation of a craniopharyngioma in a pregnant woman.

Objective. Craniopharyngioma is a rare tumour, and, consequently, acute clinical presentation and diagnosis, during pregnancy, of this pathology are quite difficult to find. Only few cases are reported in the literature, and no one describes these two conditions in association. Methods. We report a particular case of craniopharyngioma presenting both of the above conditions. Results. The patient was successfully operated with endoscopic technique. Conclusions. Rare and difficult cases, created by the superposition of different clinical conditions, need multidisciplinary management, with collaboration, integration, and cooperation between different medical specialists.