Mansour Al-Zghloul

Visualization of the internal globus pallidus: sequence and orientation for deep brain stimulation using a standard installation protocol at 3.0 Tesla

BackgroundDeep-brain stimulation (DBS) of the internal globus pallidus (GPi) has shown remarkable therapeutic benefits for treatment-resistant neurological disorders including dystonia and Parkinson’s disease (PD). The success of the DBS is critically dependent on the reliable visualization of the GPi.The aim of the study was to evaluate promising 3.0 Tesla magnetic resonance imaging (MRI) methods for pre-stereotactic visualization of the GPi using a standard installation protocol.MethodsMRI at 3.0 T of nine healthy individuals and of one patient with PD was acquired (FLAIR, T1-MPRAGE, T2-SPACE, T2*-FLASH2D, susceptibility-weighted imaging mapping (SWI)). Image quality and visualization of the GPi for each sequence were assessed by two neuroradiologists independently using a 6-point scale. Axial, coronal, and sagittal planes of the T2*-FLASH2D images were compared. Inter-rater reliability, contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) for the GPi were determined. For illustration, axial T2*-FLASH2D images were fused with a section schema of the Schaltenbrand-Wahren stereotactic atlas.ResultsThe GPi was best and reliably visualized in axial and to a lesser degree on coronal T2*-FLASH2D images. No major artifacts in the GPi were observed in any of the sequences. SWI offered a significantly higher CNR for the GPi compared to standard T2-weighted imaging using the standard parameters. The fusion of the axial T2*-FLASH2D images and the atlas projected the GPi clearly in the boundaries of the section schema.ConclusionsUsing a standard installation protocol at 3.0 T T2*-FLASH2D imaging (particularly axial view) provides optimal and reliable delineation of the GPi.

The subthalamic nucleus at 3.0 Tesla: choice of optimal sequence and orientation for deep brain stimulation using a standard installation protocol: Clinical article

OBJECT Reliable visualization of the subthalamic nucleus (STN) is indispensable for accurate placement of electrodes in deep brain stimulation (DBS) surgery for patients with Parkinson disease (PD). The aim of the study was to evaluate different promising new MRI methods at 3.0 T for preoperative visualization of the STN using a standard installation protocol. METHODS Magnetic resonance imaging studies (T2-FLAIR, T1-MPRAGE, T2*-FLASH2D, T2-SPACE, and susceptibility-weighted imaging sequences) obtained in 9 healthy volunteers and in 1 patient with PD were acquired. Two neuroradiologists independently analyzed image quality and visualization of the STN using a 6-point scale. Interrater reliability, contrast-to-noise ratios, and signal-to-noise ratios for the STN were calculated. For illustration of the anatomical accuracy, coronal T2*-FLASH2D images were fused with the corresponding coronal section schema of the Schaltenbrand and Wahren stereotactic atlas. RESULTS The STN was best and reliably visualized on T2*-FLASH2D imaging (in particular, the coronal view). No major artifacts in the STN were observed in any of the sequences. Susceptibility-weighted, T2-SPACE, and T2*-FLASH2D imaging provided significantly higher contrast-to-noise ratio values for the STN than standard T2-weighted imaging. Fusion of the coronal T2*-FLASH2D and the digitized coronal atlas view projected the STN clearly within the boundaries of the STN found in anatomical sections. CONCLUSIONS For 3.0-T MRI, T2*-FLASH2D (particularly the coronal view) provides optimal delineation of the STN using a standard installation protocol.

Imaging for deep brain stimulation: The zona incerta at 7 Tesla

AIM To evaluate different promising magnetic resonance imaging (MRI) methods at 7.0 Tesla (T) for the pre-stereotactic visualization of the zona incerta (ZI). METHODS Two neuroradiologists qualitatively and quantitatively examined T2-turbo spin-echo (T2-TSE), T1-weighted gradient-echo, as well as FLASH2D-T2Star and susceptibility-weighted imaging (SWI) for the visualization of the ZI at 7.0 T MRI. Delineation and image quality for the ZI were independently examined using a 6-scale grading system. Inter-rater reliability using Cohens kappa coefficient (κ) were assessed. Contrast-to-noise ratios (CNR), and signal-to-noise ratios (SNR) for the ZI were calculated for all sequences. Differences in delineation, SNR, and CNR between the sequences were statistically assessed using a paired t-test. For the anatomic validation the coronal FLASH2D-T2Star images were co-registered with a stereotactic atlas (Schaltenbrand-Wahren). RESULTS The rostral part of the ZI (rZI) could easily be identified and was best and reliably visualized in the coronal FLASH2D-T2Star images. The caudal part was not definable in any of the sequences. No major artifacts in the rZI were observed in any of the scans. FLASH2D-T2Star and SWI imaging offered significant higher CNR values for the rZI compared to T2-TSE images (P > 0.05). The co-registration of the coronal FLASH2D-T2Star images with the stereotactic atlas schema (Schaltenbrand-Wahren) confirmed the correct localization of the ZI in all cases. CONCLUSION FLASH2D-T2Star imaging (particularly coronal view) provides the reliable and currently optimal visualization of the rZI at 7.0 T. These results can facilitate a better and more precise targeting of the caudal part of the ZI than ever before.

Anatomical variations in the posterior part of the circle of willis and vascular pathology in bilateral thalamic infarction.

Bilateral paramedian thalamic infarction is a rare subtype of stroke the etiology of which still remains undetermined in many patients.

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 m2. 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.

Perfusion-weighted imaging and dynamic 4D angiograms for the estimation of collateral blood flow in lacunar infarction.

Although lacunar infarction accounts for approximately 25% of ischemic strokes, collateral blood flow through anastomoses is not well evaluated in lacunar infarction. In 111 lacunar infarction patients, we analyzed diffusion-weighted images, perfusion-weighted images, and blood flow on dynamic four-dimensional angiograms generated by use of Signal Processing In NMR-Software. Blood flow was classified as absent (type 1), from periphery to center (type 2), from center to periphery (type 3), and combination of type 2 and 3 (type 4). On diffusion-weighted images, lacunar infarction was found in the basal ganglia (11.7%), internal capsule (24.3%), corona radiata (30.6%), thalamus (24.3%), and brainstem (9.0%). In 58 (52.2%) patients, perfusion-weighted image showed a circumscribed hypoperfusion, in one (0.9%) a circumscribed hyperperfusion, whereas the remainder was normal. In 36 (62.1%) patients, a larger perfusion deficit (>7 mm) was observed. In these, blood flow was classified type 1 in four (11.1%), 2 in 17 (47.2%), 3 in 9 (25.0%), and 4 in six (16.7%) patients. Patients with lacunar infarction in the posterior circulation more often demonstrated blood flow type 2 and less often type 3 (p = 0.01). Detailed examination and graduation of blood flow in lacunar infarction by use of dynamic four-dimensional angiograms is feasible and may serve for a better characterization of this stroke subtype.

Incidence, Locations, and Longitudinal Course of Cerebral Microbleeds in European Moyamoya

Background and Purpose— Cerebral microbleeds (cMBs) have previously been linked with especially high incidence in Asian patients with moyamoya together with high tendency to bleed. This, presumably, is characteristic of patients with moyamoya. Herein, we, therefore, investigate retrospectively the frequency, location, and longitudinal course of cMBs in a large German cohort. Methods— We included all patients with moyamoya who underwent standard magnetic resonance imaging, including T2*-weighted images, in our department between 1998 and 2015. Two independent readers evaluated magnetic resonance imaging scans to determine the occurrence of cMBs according to the Brain Observer Microbleed Scale. Demographics, initial symptoms leading to hospitalization, and associated diseases were obtained by chart review. Results— Overall, there was a total of 242 T2* studies of 101 included moyamoya patients available with a strong female predominance (69.3%). Eight patients (7.9%) were ⩽18 years of age. We detected 25 cMBs within 13 patients (12.9%). One patient <18 of age was presented with a cMB; 2 of 3 patients with an intracranial hemorrhage as initial event demonstrated cMB(s). In 72 of 101 cases, there were 1719 person months of follow-up, with 3 adult patients showing 3 de novo cMBs in the course. The majority of cMBs (64.0%) were located at the cortex/gray–white junction. Conclusions— Although the frequency of cMBs herein is much higher than the expected age-specific incidence, it is still much lower compared with previous reports on cMBs in moyamoya patients of Asian descent. These results might reflect another ethnic-specific difference in patients diagnosed with moyamoya.

Isolated punctuate hippocampal infarction and transient global amnesia are indistinguishable by means of MRI.

Background Small punctuate lesions in the hippocampus on diffusion-weighted images are a typical finding in transient global amnesia. Consequently, it has been suggested that diffusion-weighted images findings might corroborate the diagnosis of transient global amnesia. However, isolated punctuate hippocampal infarction might be a differential diagnosis of transient global amnesia. Aim Evaluation of isolated punctuate hippocampal infarction frequency and comparison of its clinical presentation and MRI findings to transient global amnesia. Methods From an MRI database, we identified 10 patients with isolated punctuate hippocampal infarction and compared these to 12 patients with transient global amnesia with diffusion-weighted images lesion with regard to clinical symptoms and MRI findings. Results Disorientation and memory deficits were more common in transient global amnesia patients, whereas dysphasia/aphasia and vertigo were more common in hippocampal infarction patients. MRI findings in isolated punctuate hippocampal infarction and transient global amnesia did not differ significantly, neither regarding the affected hemisphere, lesion distribution, size, nor relative ADC values. Conclusions Differentiation of isolated punctuate hippocampal infarction and transient global amnesia based on neuroimaging findings is not possible. Thus, in the case of isolated punctuate hippocampal diffusion-weighted images lesions the final diagnosis of hippocampal infarction or transient global amnesia should be based on the clinical presentation.

Value of Dynamic Susceptibility Contrast Perfusion MRI in the Acute Phase of Transient Global Amnesia

Purpose 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. Methods 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). Results 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. Conclusions 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.

Sparing of the hippocampus indicates better collateral blood flow in acute posterior cerebral artery occlusion.

Background In acute posterior cerebral artery, occlusion involvement of the hippocampus is a common finding. Nevertheless, until today, infarction and ischemic lesion evolution in the hippocampus has not been studied systematically. Aim Evaluation of hippocampal infarction patterns in posterior cerebral artery occlusion in the very early phase (≤six-hours) and ischemic lesion evolution on follow-up magnetic resonance imaging in relation to collateral blood flow assessed by a magnetic resonance imaging-based approach was conducted. Methods In 28 patients [mean age 69·4 ± 13·8 years, 19 (67·9%) males, 10 (32·1%) females] with proximal posterior cerebral artery occlusion, magnetic resonance imaging findings were analyzed, with emphasis on hippocampal infarction patterns on diffusion-weighted images and collateralization on dynamic 4D angiograms derived from perfusion-weighted raw images. Results On initial diffusion-weighted images, we identified all known hippocampal infarction patterns: type 1 (complete) in 6/18 (33·3%) patients, type 2 (lateral) in 10/18 (55·6%) patients, and type 3 (dorsal) and type 4 (circumscribed) in 1/18 (5·6%) patient respectively. On dynamic 4D angiograms, the grade of collateralization was classified as 1 in 9 (32·1%), 2 in 1 (3·6%), 3 in 10 (35·7%), and 4 in 8 (28·6%) patients. On follow-up diffusion-weighted images, we found new ischemic lesions in three and infarction growth in the hippocampus in five patients. Patients with better collateralization (grades 3 and 4) less often had hippocampal infarctions on initial (P = 0·003)/follow-up diffusion-weighted images (P = 0·046) as well as type 1 on initial (P = 0·007)/follow-up diffusion-weighted images (P = 0·005). Conclusions Involvement of the hippocampus in proximal posterior cerebral artery occlusion is frequently but not obligatorily observed and highly dependent on the extent of collateralization. The same holds true for hippocampal infarction patterns.