Clinical applications of dynamic susceptibility contrast perfusion-weighted MR imaging in brain tumours.

Magnetic resonance imaging (MRI) with a dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI) sequence to study brain tumours provides information on the haemodynamic characteristics of the neoplastic tissue. Brain perfusion maps and calculation of perfusion parameters, such as relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV) and mean transit time (MTT) allow assessment of vascularity and angiogenesis within tumours of the central nervous system (CNS), thus providing additional information to conventional MRI sequences. Although DSC-PWI has long been used, its clinical use in the study of brain tumours in daily clinical practice is still to be defined. The aim of this review was to analyse the application of perfusion MRI in the study of brain tumours by summarising our personal experience and the main results reported in the literature.

Age-related macular degeneration and the complement system.

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. It is a complex multifactorial disease, and despite new advances in treatment, many patients still succumb to visual impairment. The complement pathway has been implicated in the pathogenesis of many diseases, and recently variants in several genes encoding complement pathway proteins have been associated with AMD. Complement proteins have been found in histological specimens of eyes with AMD. Altered levels of both intrinsic complement proteins and activated products have been found in the circulation of patients with AMD. Complement activation may be triggered by oxidative stress, resulting from retinal exposure to incoming light; indeed an inter-play between these two pathological processes seems to exist. Finally, complement inhibitors are currently being evaluated in clinical trials. This article reviews the role of the complement system in AMD, and the potential of complement inhibition in preventing the devastating blindness resulting from this disease.

Role of magnetic resonance tractography in the preoperative planning and intraoperative assessment of patients with intra-axial brain tumours.

PURPOSE: This study was conducted to assess the possibility of identifying precise white matter tracts situated in proximity to intracranial tumours, to define the anatomical and topographical relations between the same white matter tracts and the tumour, to verify the possibility of integrating tractographic images in the context of a package of three-dimensional anatomical images to send to the neuronavigation system, to assess the impact of this information on surgical planning, and to analyse, both pre-and postoperatively, the patient's clinical conditions as an index of the functional integrity of the fibres themselves. MATERIALS AND METHODS: Twenty-five patients underwent diffusion tensor study prior to neurosurgery. With the use of dedicated software, relative colour maps were obtained and the trajectories of the white matter tracts adjacent to the tumour were reconstructed in three dimensions. These were then processed for preoperative planning. Planning, which was performed with the neuronavigator, was based on analysis of the location of the course of the main white matter tracts adjacent to the lesion (pyramidal tract, optic radiation and arcuate fasciculus). Two neurosurgeons were asked whether the tractography images had modified the access and/or intraoperative approach to the tumour. All patients were clinically assessed both pre-and postoperatively 1 month after the procedure to define the presence of symptoms related to the involvement of the white matter tracts studied and therefore to assess the integrity of the fibres after the operation. RESULTS: In one patient, the tumour was situated away from all the tracts studied and did not compress them in any way. Overall, 40/75 tracts studied had no anatomical relation with the tumour, were not displaced by the tumour or could not be visualised in their entire course. Analysis of the remaining 35 white matter tracts led to an a priori change in the surgical approach for corticotomy in four patients (16%), with no disagreement between the two neurosurgeons and an impact on the extent of resection during surgery in 17 (68%), thus an overall impact on the surgical procedure in 80% of cases. Eight patients showed no symptoms related to the involvement of the white matter tracts studied. In the remaining 17 patients, the symptoms were related to involvement of the pyramidal tract, arcuate fasciculus or optic radiation. At 1-month follow-up, one previously asymptomatic patient reported a speech disorder (transcortical sensory dysphasia); in the remaining 24, symptoms remained unchanged, with a tendency to improvement in 14/17 with symptoms related to involvement of white matter tracts studied. CONCLUSIONS: Magnetic resonance (MR) tractography offers the neurosurgeon an anatomical panoramic view that can improve surgical planning for the resection of intracranial tumours. Despite the high incidence of cases in which the lesion is responsible for changes that hinder the reconstruction of white matter tracts, the technique can change the surgical approach for corticotomy, defines the extent of resection and leads to some change in the procedure in 80% of cases. The improvement of pre-existing symptoms and the absence of new symptoms in the postoperative phase, in our opinion, confirms the value of the technique.

Cost of an outbreak of hepatitis A in Puglia, Italy.

In total, 5889 cases of hepatitis A virus infection were reported during an outbreak in Puglia, a region of Southern Italy, in 1996. The primary cause of the outbreak was consumption of contaminated food (raw shellfish, vegetables, etc.), with a contributory risk factor of person-to-person transmission. A detailed questionnaire was completed by 250 randomly selected patients to obtain information sufficient to calculate the direct and indirect costs of the outbreak for the individual patient, the National Health Service (NHS) and society as a whole. A conversion rate of $US1 = 1530 Italian lire (L) has been used throughout the study since this was the average exchange rate in 1996. For the individual patient with hepatitis A virus infection, the mean cost was L1.013 million ($US662), which was equivalent to 6.6% of the mean annual income of the employed patients. The total cost of the outbreak to the NHS was L23.98 billion ($US15.67 million), which was equivalent to 0.4% of the total public health expenditure in the region in 1996. The total cost of the outbreak to society (individual patient, NHS and third parties combined) was L37.406 billion ($US24.45 million), corresponding to 0.04% of the gross domestic product of the entire region in 1996, with a mean cost per patient of L6.35 million ($US4150) from a societal perspective. The majority of patients (86.3%) were 11 to 30 years of age, reflecting the increasing susceptibility of younger patients to hepatitis A virus infection in recent decades. These economic and demographic data provide important information for the evaluation of preventive strategies including public education, sanitation and immunisation, so as to optimise the use of local health resources.