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Hackney, David

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Hackney

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David

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Hackney, David
Author's Publications: search.filters.isAuthorOfPublication.4ba52033-7610-43a2-94a0-7a347161eb94

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    3 T MRI relaxometry detects T2 prolongation in the cerebral normal-appearing white matter in multiple sclerosis
    (Elsevier BV, 2009-07-01) Neema, Mohit; Goldberg-Zimring, Daniel; Guss, Zachary D.; Healy, Brian; Guttmann, Charles; Houtchens, Maria; Weiner, Howard; Horsfield, Mark A.; Hackney, David; Alsop, David; Bakshi, Rohit
    MRI at 3 T has increased sensitivity in detecting overt multiple sclerosis (MS) brain lesions; a growing body of data suggests clinically relevant damage occurs in the normal-appearing white matter (NAWM). We tested a novel pulse sequence to determine whether 3 T MRI spin–spin relaxometry detected damage in NAWM of MS patients (n = 13) vs. age-matched normal controls [(NL) (n = 11)]. Baseline characteristics of the MS group were: age (mean ± SD) 42.5 ± 5.4 (range 33–51 years), disease duration 9.0 ± 6.4 (range 1–22 years), Expanded Disability Status Scale score 2.5 ± 1.7 (range 1–6.5). Brain MRI measures, obtained at 3 T, included global and regional NAWM transverse relaxation rate [R2 (= 1/T2)], derived from 3D fast spin-echo T2 prepared images, and global white matter volume fraction derived from SPGR images. The regional NAWM areas investigated were the frontal lobe, parietal lobe, and the genu and splenium of the corpus callosum. Mean NAWM R2 was lower (indicating T2 prolongation) in MS than NL in the whole brain (p = 0.00047), frontal NAWM (p = 0.00015), parietal NAWM (p = 0.0069) and callosal genu (p = 0.0019). Similarly, R2 histogram peak position was lower in NAWM in MS than NL in the whole brain (p = 0.019). However, the normalized WM volume fractions were similar in both MS and NL (p > 0.1). This pilot study suggests that a novel 3D fast spin-echo pulse sequence at 3 T, used to derive R2 relaxation maps, can detect tissue damage in the global and regional cerebral NAWM of MS patients that is missed by conventional lesion and atrophy measures. Such findings may represent demyelination, inflammation, glial proliferation and axonal loss.
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    A 3T MR Imaging Investigation of the Topography of Whole Spinal Cord Atrophy in Multiple Sclerosis
    (American Society of Neuroradiology (ASNR), 2011) Klein, Joshua; Arora, A.; Neema, M; Healy, Brian; Tauhid, Shahamat; Goldberg-Zimring, D.; Chavarro-Nieto, C.; Stankiewicz, James; Cohen, Adam; Buckle, G. J.; Houtchens, Maria; Ceccarelli, A.; Dell, E.; Guttmann, Charles; Alsop, David; Hackney, David; Bakshi, Rohit
    Background and Purpose: Spinal cord atrophy is a common feature of MS. However, it is unknown which cord levels are most susceptible to atrophy. We performed whole cord imaging to identify the levels most susceptible to atrophy in patients with MS versus controls and also tested for differences among MS clinical phenotypes. Materials and Methods: Thirty-five patients with MS (2 with CIS, 27 with RRMS, 2 with SPMS, and 4 with PPMS phenotypes) and 27 healthy controls underwent whole cord 3T MR imaging. The spinal cord contour was segmented and assigned to bins representing each C1 to T12 vertebral level. Volumes were normalized, and group comparisons were age-adjusted. Results: There was a trend toward decreased spinal cord volume at the upper cervical levels in PPMS/SPMS versus controls. A trend toward increased spinal cord volume throughout the cervical and thoracic cord in RRMS/CIS versus controls reached statistical significance at the T10 vertebral level. A statistically significant decrease was found in spinal cord volume at the upper cervical levels in PPMS/SPMS versus RRMS/CIS. Conclusions: Opposing pathologic factors impact spinal cord volume measures in MS. Patients with PPMS demonstrated a trend toward upper cervical cord atrophy. However patients with RRMS showed a trend toward increased volume at the cervical and thoracic levels, which most likely reflects inflammation or edema-related cord expansion. With the disease causing both expansion and contraction of the cord, the specificity of spinal cord volume measures for neuroprotective therapeutic effect may be limited.
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    Spinal Cord Lesions and Clinical Status in Multiple Sclerosis: A 1.5 T and 3 T MRI Study
    (Elsevier BV, 2009-04-15) Stankiewicz, James; Neema, Mohit; Alsop, David; Healy, Brian; Arora, Ashish; Buckle, Guy J.; Chitnis, Tanuja; Guttmann, Charles; Hackney, David; Bakshi, Rohit
    Objective Assess the relationship between spinal cord T2 hyperintense lesions and clinical status in multiple sclerosis (MS) with 1.5 and 3T MRI. Methods Whole cord T2-weighted fast spin-echo MRI was performed in 32 MS patients [Expanded Disability Status Scale (EDSS) score (mean±SD: 2±1.9), range 0–6.5]. Protocols at 1.5T and 3T were optimized and matched on voxel size. Results Moderate correlations were found between whole cord lesion volume and EDSS score at 1.5T (rs =.36, p=0.04), but not at 3T (rs =0.13, p=0.46). Pyramidal Functional System Score (FSS) correlated with thoracic T2 lesion number (rs=.46, p=0.01) and total spinal cord lesion number (rs=0.37, p=0.04) and volume (rs=0.37, p=0.04) at 1.5T. Bowel/bladder FSS correlated with T2 lesion volume and number in the cervical, thoracic, and total spine at 1.5T (rs 0.400.57, all p<0.05). These MRI-FSS correlations were non-significant at 3T. However, these correlation coefficients did not differ significantly between platforms (Choi’s test p>0.05). Correlations between whole cord lesion volume and timed 25-foot walk were non-significant at 1.5T and 3T (p>0.05). Lesion number and volume did not differ between MRI platforms in the MS group (p>0.05). Conclusions Despite the use of higher field MRI strength, the link between spinal lesions and MS disability remains weak. The 1.5T and 3T protocols yielded similar results for many comparisons.
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    Using Anatomic Magnetic Resonance Image Information to Enhance Visualization and Interpretation of Functional Images: A Comparison of Methods Applied to Clinical Arterial Spin Labeling Images
    (Institute of Electrical and Electronics Engineers (IEEE), 2017-02) Zhao, Li; Dai, Weiying; Soman, Salil; Hackney, David; Wong, Eric; Robson, Philip M.; Alsop, David
    Functional imaging provides hemodynamic and metabolic information and is increasingly being incorporated into clinical diagnostic and research studies. Typically functional images have reduced signal-to-noise ratio and spatial resolution compared to other non-functional cross sectional images obtained as part of a routine clinical protocol. We hypothesized that enhancing visualization and interpretation of functional images with anatomic information could provide preferable quality and superior diagnostic value. In this work, we implemented five methods (frequency addition, frequency multiplication, wavelet transform, non-subsampled contourlet transform and intensity-hue-saturation) and a newly proposed ShArpening by Local Similarity with Anatomic images (SALSA) method to enhance the visualization of functional images, while preserving the original functional contrast and quantitative signal intensity characteristics over larger spatial scales. Arterial spin labeling blood flow MR images of the brain were visualization enhanced using anatomic images with multiple contrasts. The algorithms were validated on a numerical phantom and their performance on images of brain tumor patients were assessed by quantitative metrics and neuroradiologist subjective ratings. The frequency multiplication method had the lowest residual error for preserving the original functional image contrast at larger spatial scales (55%–98% of the other methods with simulated data and 64%–86% with experimental data). It was also significantly more highly graded by the radiologists (p<0.005 for clear brain anatomy around the tumor). Compared to other methods, the SALSA provided 11%–133% higher similarity with ground truth images in the simulation and showed just slightly lower neuroradiologist grading score. Most of these monochrome methods do not require any prior knowledge about the functional and anatomic image characteristics, except the acquired resolution. Hence, automatic implementation on clinical images should be readily feasible.
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    Brain MR Imaging at Ultra-Low Radiofrequency Power
    (Radiological Society of North America (RSNA), 2011-05) Sarkar, Subhendra N.; Alsop, David; Madhuranthakam, Ananth J.; Busse, Reed F.; Robson, Philip M.; Rofsky, Neil M.; Hackney, David
    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. Seven healthy subjects were imaged prospectively at 1.5 T with ultra-low-SAR optimized three-dimensional (3D) fast spin-echo (FSE) and fluid-attenuated inversion-recovery (FLAIR) T2-weighted sequences and an ultra-low-SAR 3D spoiled gradient-recalled acquisition in the steady state T1-weighted sequence. Corresponding high-SAR two-dimensional (2D) clinical sequences were also performed. In addition to qualitative comparisons, absolute signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) for multicoil, parallel imaging acquisitions were generated by using a Monte Carlo method for quantitative comparison between ultra-low-SAR and high-SAR results. Results: There were minor to moderate differences in the absolute tissue SNR and CNR values and in qualitative appearance of brain images obtained by using ultra-low-SAR and high-SAR techniques. High-SAR 2D T2-weighted imaging produced slightly higher SNR, while ultra-low-SAR 3D technique not only produced higher SNR for T1-weighted and FLAIR images but also higher CNRs for all three sequences for most of the brain tissues. Conclusion: The 3D techniques adopted here led to a decrease in the absorbed RF power by two orders of magnitude at 1.5 T, and still the image quality was preserved within clinically acceptable imaging times.
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    Hyperintense Cortical Signal on Magnetic Resonance Imaging Reflects Focal Leukocortical Encephalitis and Seizure Risk in Progressive Multifocal Leukoencephalopathy
    (Wiley, 2014-05) Khoury, Michael N.; Alsop, David; Agnihotri, Shruti P.; Pfannl, Rolf; Wuthrich, Christian; Ho, Mai-Lan; Hackney, David; Ngo, Long; Anderson, Matthew; Koralnik, Igor
    Objective To determine the frequency of hyperintense cortical signal (HCS) on T1-weighted pre-contrast MRI in progressive multifocal leukoencephalopathy (PML) patients, its association with seizure risk and immune reconstitution inflammatory syndrome (IRIS), and its pathologic correlate. Methods We reviewed clinical data including seizure history, presence of IRIS, and MRI scans from PML patients evaluated at our institution between 2003 and 2012. Cases that were diagnosed either by CSF JC Virus (JCV) PCR, brain biopsy or autopsy, and who had MRI images available were included in the analysis (n=49). We characterized pathologic findings in areas of the brain displaying HCS in two patients and compared them with isointense cortex in the same individuals. Results Of 49 patients, 17 (34.7%) had seizures and 30 (61.2%) had HCS adjacent to subcortical PML lesions on MRI. Of the 17 PML patients with seizures, 15 (88.2%) had HCS compared to 15/32 (46.9%) patients without seizures (p= 0.006). HCS was associated with seizure development with a relative risk (RR) of 4.75 (95% confidence interval of 1.2 to 18.5; p=0.006). Of the 20 patients with IRIS, 16 (80.0%) had HCS compared to 14/29 (49.3%) of those without IRIS (p=0.04). On histological examination, HCS areas were associated with striking JCV-associated demyelination of cortical and sub-cortical U-fibers, significant macrophage infiltration and a pronounced reactive gliosis in the deep cortical layers. Interpretation Seizures are a frequent complication in PML. HCS is associated with seizures as well as IRIS, and correlates histologically with JCV focal leukocortical encephalitis (JCV FLE).