Ali Al-Radaideh

A Comparison of 3T and 7T in the Detection of Small Parenchymal Veins Within MS Lesions

Objective:Histologic examination of multiple sclerosis (MS) brain lesions reveals heterogeneity including the presence or absence of a central blood vessel. Recent work has shown that T2* weighted magnetic resonance imaging at 7T allows the identification of small parenchymal veins within MS lesions. The aims of this study were (1) to compare whether a comparable sequence at 3T was also capable of demonstrating parenchymal veins within MS brain lesions, and (2) to investigate the potential of 7T T2* weighted imaging to differentiate between MS white matter lesions and age-related vascular lesions seen in controls. Materials and Methods:Seven patients with demyelinating brain disease and 7 healthy volunteers were scanned at 3T and 7T. Fluid attenuated inversion recovery (FLAIR) images acquired at 3T were used to identify each brain lesion in each patient. A comparison of images from both field strengths was then made to determine whether white matter lesions seen in 3T FLAIR images could be identified in T2*-weighted images, and whether a central vein could be detected. Results:A total of 358 brain lesions were identified in the brains of the 7 patients using 3T FLAIR images. The 3T T2* sequence detected 89% of FLAIR lesions compared with 94% using the 7T T2* sequence (P = 0.0002). A central vessel could be identified in 45% of visible lesions using 3T T2* and 87% of visible lesions using 7T T2* (P < 0.0001). Using 7T T2* imaging, a central vein was evident in only 8% of the discrete white matter lesions found in the brains of healthy volunteers. Discussion:This study suggests that ultra high field imaging is advantageous in demonstrating detailed structural anatomy of MS lesions. 7T T2* imaging can be used in the future to investigate the pathogenesis of MS lesions. The potential for ultra high field imaging to discriminate between MS white matter lesions and microangiopathic lesions warrants further investigation as this would represent a clinically useful application.

3 Tesla and 7 Tesla MRI of multiple sclerosis cortical lesions

Cortical lesions are prevalent in multiple sclerosis but are poorly detected using MRI. The double inversion recovery (DIR) sequence is increasingly used to explore the clinical relevance of cortical demyelination. Here we evaluate the agreement between imaging sequences at 3 Tesla (T) and 7T for the presence and appearance of individual multiple sclerosis cortical lesions. Eleven patients with demyelinating disease and eight healthy volunteers underwent MR imaging at 3T (fluid attenuated inversion recovery [FLAIR], DIR, and T1‐weighted magnetization prepared rapid acquisition gradient echo [MP‐RAGE] sequences) and 7T (T1‐weighted MP‐RAGE). There was good agreement between images for the presence of mixed cortical lesions (involving both gray and white matter). However, agreement between imaging sequences was less good for purely intracortical lesions. Even after retrospective analysis, 25% of cortical lesions could only be visualized on a single MRI sequence. Several DIR hyperintensities thought to represent cortical lesions were found to correspond to signal arising from extracortical blood vessels. High‐resolution 7T imaging appeared useful for confidently classifying the location of lesions in relation to the cortical/subcortical boundary. We conclude that DIR, FLAIR, and MP‐RAGE imaging sequences appear to provide complementary information during the detection of multiple sclerosis cortical lesions. High resolution 7T imaging may facilitate anatomical localization of lesions in relation to the cortical boundary. J. Magn. Reson. Imaging 2010;32:971–977.

Tailored RF Pulse for Magnetization Inversion at Ultrahigh Field

The radiofrequency (RF) transmit field is severely inhomogeneous at ultrahigh field due to both RF penetration and RF coil design issues. This particularly impairs image quality for sequences that use inversion pulses such as magnetization prepared rapid acquisition gradient echo and limits the use of quantitative arterial spin labeling sequences such as flow‐attenuated inversion recovery. Here we have used a search algorithm to produce inversion pulses tailored to take into account the heterogeneity of the RF transmit field at 7 T. This created a slice selective inversion pulse that worked well (good slice profile and uniform inversion) over the range of RF amplitudes typically obtained in the head at 7 T while still maintaining an experimentally achievable pulse length and pulse amplitude in the brain at 7 T. The pulses used were based on the frequency offset correction inversion technique, as well as time dilation of functions, but the RF amplitude, frequency sweep, and gradient functions were all generated using a genetic algorithm with an evaluation function that took into account both the desired inversion profile and the transmit field inhomogeneity. Magn Reson Med, 2009.

Increased iron accumulation occurs in the earliest stages of demyelinating disease: an ultra-high field susceptibility mapping study in Clinically Isolated Syndrome

Objective: To determine, using ultra-high field magnetic resonance imaging (MRI), whether changes in iron content occur in the earliest phases of demyelinating disease, by quantifying the magnetic susceptibility of deep grey matter structures in patients with Clinically Isolated Syndrome (CIS) that is suggestive of multiple sclerosis (MS), as compared with age-matched healthy subjects. Methods: We compared 19 CIS patients to 20 age-matched, healthy controls. Scanning of the study subjects was performed on a 7T Philips Achieva system, using a 3-dimensional, T2*-weighted gradient echo acquisition. Phase data were first high-pass filtered, using a dipole fitting method, and then inverted to produce magnetic susceptibility maps. Region of interest (ROI) analysis was used to estimate magnetic susceptibility values for deep grey matter structures (caudate nucleus, putamen, globus pallidus, the thalamus and its pulvinar). Results: Significantly increased relative susceptibilities were found in the CIS group, compared with controls, for the caudate nucleus (p = < 0.01), putamen (p < 0.01), globus pallidus (p < 0.01) and pulvinar (p < 0.05). We found no significant nor consistent trends in the relationship between susceptibility and age for either the study controls or CIS patients, in any ROI (r 2 < 0.5; p > 0.05). In CIS patients, the time elapsed since the clinical event and the Expanded Disability Status Scale (EDSS) scores were not correlated with iron levels in any ROI (r 2 < 0.5; p > 0.05); however, a moderate correlation (r 2 = 0.3; p < 0.01) was found between the T1 lesion load and the mean susceptibility of the caudate nucleus. Conclusion: CIS patients showed an increased iron accumulation, as measured using susceptibility mapping of the deep grey matter, suggesting that iron changes did occur at the earlier stages of CIS disease.

Combined white matter imaging suggests myelination defects in visual processing regions in schizophrenia.

Diverse pathological changes occur in the white matter (WM) of patients with schizophrenia. Various microstructural alterations including a reduction in axonal number or diameter, reduced myelination, or poor coherence of fibers could account for these changes. Abnormal integrity of macromolecules such as myelin (‘dysmyelination’) can be studied by applying multiple modalities of WM imaging such as diffusion tensor imaging (DTI) and magnetization transfer imaging (MTI) in parallel. Using ultra-high field (7 Tesla) MTI in 17 clinically stable patients with schizophrenia and 20 controls, we evaluated the voxelwise distribution of macromolecular WM abnormalities. Patients had a significant reduction in magnetization transfer ratio (MTR) in WM adjacent to visual processing regions and inferior temporal cortex (Cohen’s d=1.54). Among the regions showing MTR reduction, a concurrent reduction in fractional anisotropy (FA) occurs proximal to the lingual gyrus. Multiple regression analysis revealed that the degree of FA reduction in the putatively ‘dysmyelinated’ regions in patients predicted impaired processing speed (PS; β=0.74; P=0.003), a core cognitive dysfunction in schizophrenia. In controls, MTR/FA in the occipito-temporal regions were not associated with PS. Our findings suggest that dysmyelination in visual processing regions is present in patients with schizophrenia with greatest cognitive and functional impairment. Combined DTI/MTI deficits in the occipito-temporal region may be an important variable when considering potential treatment targets for improving cognitive function in schizophrenia.

Increase in the iron content of the substantia nigra and red nucleus in multiple sclerosis and clinically isolated syndrome: A 7 Tesla MRI study

To study iron deposition in the substantia nigra (SN) and red nuclei (RN), in patients with clinically isolated syndrome (CIS) and relapsing remitting MS (RRMS) and healthy controls (HC).

The role of magnetic resonance imaging in the diagnosis of Parkinson's disease: a review

Parkinsons disease (PD) is the second most common neurodegenerative disease after Alzheimers in elderly people. Different structural and functional neuroimaging methods play a great role in the early diagnosis of neurodegenerative diseases. This review discusses the role of magnetic resonance imaging (MRI) in the diagnosis of PD. MRI provides clinicians with structural and functional information of human brain noninvasively. Advanced quantitative MRI techniques have shown promise for detecting pathological changes related to different stages of PD. Collectively, advanced MRI techniques at high and ultrahigh magnetic fields aid in better understanding of the nature and progression of PD.

Assessment of Abdominal Fat Using High-field Magnetic Resonance Imaging and Anthropometric and Biochemical Parameters

Background: To measure the abdominal subcutaneous fat (SF) and visceral fat (VF) volumes using high‐field magnetic resonance imaging (MRI) and to investigate their association with selected anthropometric and biochemical parameters among obese and nonobese apparently healthy participants. Methods: A cross‐sectional study was conducted by recruiting 167 healthy participants. Abdominal scans were acquired at 3T MRI, and the SF and VF were segmented and their volumes were calculated. Selected anthropometric and biochemical measurements were also determined. Results: A significant difference (P < 0.05) was observed between normal body weight and overweight and obese participants for SF and VF, total abdominal fat volumes, leptin, resistin, adiponectin and waist circumference. Waist circumferences were measured by tape and MRI. Findings revealed that MRI‐measured fat volumes were different between males and females and had a significant (P < 0.01) strong positive correlation with body mass index, leptin, resistin and WC and had a negative correlation with adiponectin level. MRI‐measured fat volumes were found to correlate moderately with interleukin‐6 and weakly with cholesterol, serum triglyceride and low‐density lipoprotein. Except for cholesterol, all measured biochemical variables and abdominal fat volumes in the current study were significantly associated with body mass index. Conclusions: All anthropometric and biochemical parameters showed weak‐to‐strong associations with the MRI‐measured fat volumes. Abdominal fat distribution was different between males and females and their correlations with some lipid profiles were found to be sex dependent. These findings revealed that MRI can be used as an alternative tool for obesity assessment.

Mesenchymal stem cells and conditioned media in the treatment of multiple sclerosis patients: Clinical, ophthalmological and radiological assessments of safety and efficacy

This open‐label prospective phase I/IIa clinical study used autologous bone marrow‐derived mesenchymal stromal cells (BM‐MSCs) followed by mesenchymal stromal cells conditioned media (MSC‐CM) for the first time to treat multiple sclerosis (MS) patients. The primary goal was to assess the safety and feasibility and the secondary was efficacy. The correlation between the MSC‐CM content and treatment outcome was investigated.

Seven‐Tesla Magnetization Transfer Imaging to Detect Multiple Sclerosis White Matter Lesions

Fluid‐attenuated inversion recovery (FLAIR) imaging at 3 Tesla (T) field strength is the most sensitive modality for detecting white matter lesions in multiple sclerosis. While 7T FLAIR is effective in detecting cortical lesions, it has not been fully optimized for visualization of white matter lesions and thus has not been used for delineating lesions in quantitative magnetic resonance imaging (MRI) studies of the normal appearing white matter in multiple sclerosis. Therefore, we aimed to evaluate the sensitivity of 7T magnetization‐transfer‐weighted (MTw) images in the detection of white matter lesions compared with 3T‐FLAIR.