Hyperintense Acute Reperfusion Marker on FLAIR in Posterior Circulation Infarction.

In the present study, we aimed to investigate the frequency of blood brain barrier injury in posterior circulation infarction as demonstrated by the hyperintense acute reperfusion marker (HARM) on fluid attenuated inversion recovery images (FLAIR).From a MRI report database we identified patients with posterior circulation infarction who underwent MRI, including perfusion-weighted images (PWI), within 12 hours after onset and follow-up MRI within 24 hours and analyzed diffusion-weighted images (DWI), PWI, FLAIR, and MR angiography (MRA). On FLAIR images, the presence of HARM was noted by using pre-specified criteria (focal enhancement in the subarachnoid space and/or the ventricles).Overall 16 patients (median age of patients 68.5 (IQR 55.5-82.75) years) with posterior circulation infarction were included. Of these, 13 (81.3%) demonstrated PCA occlusion, and 3 (18.7%) patients BA occlusion on MRA. Initial DWI demonstrated ischemic lesions in the thalamus (68.8%), splenium (18.8%), hippocampus (75%), occipital lobe (81.3%), mesencephalon (18.8%), pons (18.8%), and cerebellum (50%). On follow-up MRA recanalization was noted in 10 (62.5%) patients. On follow-up FLAIR images, HARM was observed in 8 (50%) patients. In all of these, HARM was detected remote from the acute ischemic lesion. HARM was more frequently observed in patients with vessel recanalization (p = 0.04), minor infarction growth (p = 0.01), and smaller ischemic lesions on follow-up DWI (p = 0.05).HARM is a frequent finding in posterior circulation infarction and associated with vessel recanalization, minor infarction growth as well as smaller infarction volumes in the course. Neuroradiologists should be cognizant of the fact that HARM may be present on short interval follow-up FLAIR images in patients with acute ischemic infarction who initially underwent MRI and received intravenous gadolinium-based contrast agents

Laser-guided cervical selective nerve root block with the Dyna-CT: initial experience of three-dimensional puncture planning with an ex-vivo model.

BACKGROUND: Cervical selective nerve root block (CSNRB) is a well-established, minimally invasive procedure to treat radicular cervical pain. However, the procedure is technically challenging and might lead to major complications. The objective of this study was to evaluate the feasibility of a three-dimensional puncture planning and two-dimensional laser-guidance system for CSNRB in an ex-vivo model. METHODS: Dyna-CT of the cervical spine of an ex-vivo lamb model was performed with the Artis Zee® Ceiling (Siemens Medical Solutions, Erlangen, Germany) to acquire multiplanar reconstruction images. 15 cervical nerve root punctures were planned and conducted with the syngo iGuide® laser-guidance system. Needle tip location and contrast dye distribution were analyzed by two independent investigators. Procedural, planning, and fluoroscopic time, tract length, and dose area product (DAP) were acquired for each puncture. RESULTS: All 15 punctures were rated as successful with 12 punctures on the first attempt. Total procedural time was approximately 5 minutes. Mean planning time for the puncture was 2.03 (±0.39) min. Mean puncture time was 2.16 (±0.32) min, while mean fluoroscopy time was 0.17 (±0.06) min. Mean tract length was 2.68 (±0.23) cm. Mean total DAP was 397.45 (±15.63) µGy m(2). CONCLUSION: CSNRB performed with Dyna-CT and the tested laser guidance system is feasible. 3D pre-puncture planning is easy and fast and the laser-guiding system ensures very accurate and intuitive puncture control

Value of dynamic susceptibility contrast perfusion MRI in the acute phase of transient global amnesia.

Transient global amnesia (TGA) is a transitory, short-lasting neurological disorder characterized by a sudden onset of antero- and retrograde amnesia. Perfusion abnormalities in TGA have been evaluated mainly by use of positron emission tomography (PET) or single-photon emission computed tomography (SPECT). In the present study we explore the value of dynamic susceptibility contrast perfusion-weighted MRI (PWI) in TGA in the acute phase.From a MRI report database we identified TGA patients who underwent MRI including PWI in the acute phase and compared these to control subjects. Quantitative perfusion maps (cerebral blood flow (CBF) and volume (CBV)) were generated and analyzed by use of Signal Processing In NMR-Software (SPIN). CBF and CBV values in subcortical brain regions were assessed by use of VOI created in FIRST, a model-based segmentation tool in the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FSL).Five TGA patients were included (2 men, 3 women). On PWI, no relevant perfusion alterations were found by visual inspection in TGA patients. Group comparisons for possible differences between TGA patients and control subjects showed significant lower rCBF values bilaterally in the hippocampus, in the left thalamus and globus pallidus as well as bilaterally in the putamen and the left caudate nucleus. Correspondingly, significant lower rCBV values were observed bilaterally in the hippocampus and the putamen as well as in the left caudate nucleus. Group comparisons for possible side differences in rCBF and rCBV values in TGA patients revealed a significant lower rCBV value in the left caudate nucleus.Mere visual inspection of PWI is not sufficient for the assessment of perfusion changes in TGA in the acute phase. Group comparisons with healthy control subjects might be useful to detect subtle perfusion changes on PWI in TGA patients. However, this should be confirmed in larger data sets and serial PWI examinations

Demographic characteristics, ischemic lesion size on initial and follow-up DWI, as well as perfusion deficit size on initial PWI in patients with and without HARM.

<p>Demographic characteristics, ischemic lesion size on initial and follow-up DWI, as well as perfusion deficit size on initial PWI in patients with and without HARM.</p

Needle tip localization in post-puncture control Dyna-CT images.

<p>Lateral (<b>A</b>), coronal (<b>B</b>), and axial views (<b>C</b>) of the multiplanar reconstructions, as well as (<b>D</b>) three-dimensional rendering of the Dyna-CT of the <i>ex-vivo</i> lamb cervical spine-model demonstrating the location of the needle tip and the trajectory used to access the neural foramen. The needle tip is located in the posterior part of the neural foramen, anatomically well away from the vertebral vessels but directly adjacent to the path of the nerve root.</p

Detailed data for cervical selective nerve root block using Dyna-CT with syngo iGuide® laser-guidance.

1<p>DAP: dose area product.</p

Pre-interventional interventional table positioning and laser-guided puncture.

<p>Correct pre-interventional positioning of the free-floating interventional table shown as three lines properly positioned in the indicated triangle (<b>B</b>). Correct laser-guided puncture along the planned trajectory indicated by the needle in-line with the 2D laser cross (<b>B</b>).</p

Schematic illustration of perfusion MRI postprocessing and analysis.

<p>A. CBF map. B. CBF map with superimposed parenchyma mask (red). C. Processed CBF map after application of the parenchyma mask. D. Processed CBF map with superimposed vessel mask (turquoise). E. Processed CBF map after application of the vessel mask. F. Processed CBF map with superimposed hippocampus VOI (blue) and amygdala VOI (violet).</p

Fluoroscopic control images for correct needle positioning.

<p>Bulls’eye view (<b>A</b>) and angulated lateral (<b>B</b>) and oblique (<b>C</b>) views confirming the correct trajectory in-line with the indicated road-map. The positioning of the needle tip centered in the bulls’ eye (<b>A</b>, <b>B</b>, and <b>C</b>) confirming the needle tip in the target area.</p

Three-dimensional puncture planning using syngo iGuide®.

<p>Three-dimensional puncture planning using syngo iGuide® with indication of the planned needle trajectory in two angulated lateral (<b>A</b> and <b>B</b>) views and the axial (<b>C</b>) orientation on the multiplanar Dyna-CT reconstructions of the <i>ex-vivo</i> lamb spine-model. Additionally three-dimensional rendering of the Dyna-CT (<b>D</b>) visualizing the trajectory path. The distance between skin entry and target area is indicated (<b>A</b>, <b>C</b>, and <b>D</b>).</p