[en] Short communication

No abstract available

[en] Artefacts in MR can take the form of variation in signal intensities or mispositioning of signal that can be misleading because they alter the appearance of the image. This paper covers the most common artefacts, that must be recognized andly understood in order to accurately interpret MR findings. Each type of artefact will be illustrated, briefly explained and followed by practical suggestions for avoiding or reducing it. At the end of the paper a table will resume the essential notions to be remembered. (authors). 27 refs., 35 figs

[en] Many efforts and much research have been dedicated to the field of non-invasive angiographic techniques in the past few years. Thanks first to magnetic resonance angiography (MRA) and subsequently to computed tomographic angiography (CTA), very interesting results have been obtained in the diagnosis of cerebrovascular diseases. Neck vessels are most successfully evaluated by both MRA and CTA, and the need for digital subtraction angiography (DSA) examinations in patients at risk for vascular occlusions has significantly decreased. The role and the diagnostic accuracy of these non-invasive modalities in intracranial vascular pathology is still under investigation, and several studies have been and are being performed. Both techniques have a better spatial resolution and sensitivity in detecting cerebrovascular malformations than DSA. In the diagnosis of cerebral aneurysms, both MRA and CTA - due to their high sensitivity - have become screening techniques in the population at risk for subarachnoid hemorrhage, these techniques may become basic diagnostic modalities in treatment planning. The results are less satisfying in the evaluation of brain arteriovenous malformations and in the different steps of pre- and post-therapeutic evaluation. (orig.)

No abstract available

[en] Based on clinical observations, we hypothesized that in infiltrative high-grade brainstem neoplasms, such as diffuse intrinsic pontine glioma (DIPG), longitudinal metabolic evaluation of the tumor by magnetic resonance spectroscopy (MRS) may be more accurate than volumetric data for monitoring the tumor's biological evolution during standard treatment. We evaluated longitudinal MRS data and corresponding tumor volumes of 31 children with DIPG. We statistically analyzed correlations between tumor volume and ratios of Cho/NAA, Cho/Cr, and NAA/Cr at key time points during the course of the disease through the end of the progression-free survival period. By the end of RT, tumor volume had significantly decreased from the baseline (P <.0001) and remained decreased through the last available follow-up magnetic resonance imaging study (P =.007632). However, the metabolic profile of the tumor tissue (Cho/Cr, NAA/Cr, and Cho/NAA ratios) did not change significantly over time. Our data show that longitudinal tumor volume and metabolic profile changes are dissociated in patients with DIPG during progression-free survival. Volume changes, therefore, may not accurately reflect treatment-related changes in tumor burden. This study adds to the existing body of evidence that the value of conventional MRI metrics, including volumetric data, needs to be reevaluated critically and, in infiltrative tumors in particular, may not be useful as study end-points in clinical trials. We submit that advanced quantitative MRI data, including robust, MRS-based metabolic ratios and diffusion and perfusion metrics, may be better surrogate markers of key end-points in clinical trials. (orig.)