Microvascular and large vein abnormalities in young patients after mild head trauma and associated fatigue: A brain SPECT evaluation and posture dependence modeling.

Objective: MRI and CT scans are usually normal in mild traumatic brain injury (mTBI) although 15-20% of such patients suffer for months from fatigue, headache, anxiety, sleep and other disorders. mTBI is suspected to be a cerebrovascular injury, similar to moderate and severe TBI. Brain SPECT is more sensitive and shows perfusion abnormalities immediately after mTBI.

A subjective and objective comparison of tissue contrast and imaging artifacts present in routine spin echoes and in iterative decomposition of asymmetric spin echoes for soft tissue neck MRI.

Objective: FSE sequences play key roles in neck MRI despite the susceptibility issues in neck region. Iterative decomposition of asymmetric echoes (IDEAL, GE) is a promising method that separates fat and water images resulting in high SNR and improved fat suppression. We tested how neck tissue contrasts, image artifacts and fat separation as opposed to fat suppression in terms of image quality compare between routine and IDEAL FSE.

Quantifying cerebellum grey matter and white matter perfusion using pulsed arterial spin labeling.

To facilitate quantification of cerebellum cerebral blood flow (CBF), studies were performed to systematically optimize arterial spin labeling (ASL) parameters for measuring cerebellum perfusion, segment cerebellum to obtain separate CBF values for grey matter (GM) and white matter (WM), and compare FAIR ASST to PICORE. Cerebellum GM and WM CBF were measured with optimized ASL parameters using FAIR ASST and PICORE in five subjects. Influence of volume averaging in voxels on cerebellar grey and white matter boundaries was minimized by high-probability threshold masks.

Utilizing fast spin echo MRI to reduce image artifacts and improve implant/tissue interface detection in refractory Parkinson's patients with deep brain stimulators.

Introduction. In medically refractory Parkinson's disease (PD) deep-brain stimulation (DBS) is an effective therapeutic tool. Postimplantation MRI is important in assessing tissue damage and DBS lead placement accuracy.

Subthalamic nuclear tissue contrast in inversion recovery MRI decreases with age in medically refractory Parkinson's disease.

Background And Purpose: MRI appearance of subthalamic nucleus (STN) boundaries in Parkinson's patients is often unreliable and not well understood. An objective comparison between FSE T2 and inversion recovery (FSTIR) sequences for stereotactic placement of deep brain stimulators is presented to advance current understanding of STN tissue contrast for refractory Parkinson's disease (PD).

Methods: We imaged 12 PD (age 53-82) and 12 control patients (age 48-77) using T2 and FSTIR sequences at 1.

Three-dimensional brain MRI for DBS patients within ultra-low radiofrequency power limits.

Background: For patients with deep brain stimulators (DBS), local absorbed radiofrequency (RF) power is unknown and is much higher than what the system estimates. We developed a comprehensive, high-quality brain magnetic resonance imaging (MRI) protocol for DBS patients utilizing three-dimensional (3D) magnetic resonance sequences at very low RF power.

Methods: Six patients with DBS were imaged (10 sessions) using a transmit/receive head coil at 1.

Effect of low refocusing angle in T1-weighted spin echo and fast spin echo MRI on low-contrast detectability: a comparative phantom study at 1.5 and 3 Tesla.

MRI tissue contrast is not well preserved at high field. In this work, we used a phantom with known, intrinsic contrast (3.6%) for model tissue pairs to test the effects of low angle refocusing pulses and magnetization transfer from adjacent slices on intrinsic contrast at 1.

Anteroposterior perfusion heterogeneity in human hippocampus measured by arterial spin labeling MRI.

Measurements of blood flow in the human hippocampus are complicated by its relatively small size, unusual anatomy and patterns of blood supply. Only a handful of arterial spin labeling (ASL) MRI articles have reported regional cerebral blood flow (rCBF) values for the human hippocampus. Numerous reports have found heterogeneity in a number of other physiological and biochemical parameters along the longitudinal hippocampal axis.

Improved quantification of brain perfusion using FAIR with active suppression of superior tagging (FAIR ASST).

Purpose: To address two problems for perfusion studies in the middle or inferior brain regions: (1) to reduce venous artifacts due to the intrinsic superior labeling of FAIR; (2) to alleviate the discrepancy of the existence of both superior and inferior boluses, but with only the inferior bolus having a temporally defined bolus width with Q2TIPs or QUIPSS.

Materials And Methods: Superior tagging suppression methods for FAIR with different combinations of pre- and postinversion superior saturation pulses were evaluated and compared with FAIR with Q2TIPS for producing perfusion maps of superior, middle, and inferior brain regions.

Results: One preinversion plus two postinversion superior saturation radio frequency pulses effectively suppressed the superior tagging of FAIR and sufficiently eliminated venous artifacts without negative effects, avoiding the overestimations of cerebral blood flow that can occur in FAIR.

Optimized double inversion recovery for reduction of T₁ weighting in fluid-attenuated inversion recovery.

Fluid-attenuated inversion recovery (FLAIR) is a routinely used technique in clinical practice to detect long T(2) lesions by suppressing the cerebrospinal fluid. Concerns remain, however, that the inversion pulse in FLAIR imparts T(1) weighting that can decrease the detectability and mischaracterize some lesions. Hence, FLAIR is usually acquired in conjunction with a standard T(2) to guard against these concerns.

Brain MR imaging at ultra-low radiofrequency power.

Purpose: To explore the lower limits for radiofrequency (RF) power-induced specific absorption rate (SAR) achievable at 1.5 T for brain magnetic resonance (MR) imaging without loss of tissue signal or contrast present in high-SAR clinical imaging in order to create a potentially viable MR method at ultra-low RF power to image tissues containing implanted devices.

Materials And Methods: An institutional review board-approved HIPAA-compliant prospective MR study design was used, with written informed consent from all subjects prior to MR sessions.