Faculty Bibliography

BACKGROUND AND PURPOSE: Magnetization transfer ratio histogram peak height (MTR-HPH) has been shown to correlate with macroscopic and microscopic brain disease in patients with multiple sclerosis (MS). We studied the changes in MTR-HPH and in Kurtzke's Expanded Disability Status Scale (EDSS) scores over time in a group of patients with relapsing-remitting MS. METHODS: Twenty adult patients with relapsing-remitting MS (four men and 16 women) were followed up for a period of 334 to 1313 days. In all, 86 MR imaging studies of the brain were obtained, and MTR-HPH was calculated for each MR examination by using a semiautomated technique. Changes in MTR-HPH were compared between patients over the study's duration. A neurologist specialized in the care of MS patients assessed the EDSS score for each patient as a measure of clinical disability. RESULTS: Serial MR data showed a subtle but significant decline in MTR-HPH with time. No significant changes in EDSS scores were noted over the same period. CONCLUSION: Patients with relapsing-remitting MS have a significant progressive decline in normalized MTR-HPH, which is independent of EDSS score. MTR-HPH measurements can be used to monitor subclinical disease in patients with relapsing-remitting MS over a short time frame of 1 to 4 years. This parameter might be applied in future therapeutic trials to assess its usefulness

PURPOSE: To determine the relationship between T2 lesion volume and either disability measurements or change in T2 lesion volume over time in multiple sclerosis (MS). MATERIALS AND METHODS: Eighteen patients (age range, 26-53 years) with clinically proved relapsing-remitting MS were examined every 6 months for over 2 years. Three-millimeter-thick contiguous images of the whole brain were obtained. T2 lesion volume was calculated with a highly reproducible volumetric computer method. RESULTS: A substantial annual increase in T2 lesion volume, with a median annual increase of approximately 8%, was demonstrated. However, there was no significant correlation between absolute T2 lesion volume and either the absolute expanded disability status scale (EDSS) grade (P = .32) or the absolute ambulation index (AI) (P = .20). In addition, no significant correlation between change in T2 lesion volume and change in EDSS grade (P = .42) or AI (P = .37) was found. There was no significant correlation between T2 lesion volume and duration of disease (P = .08). CONCLUSION: There is no significant correlation between T2 lesion volume and standardized disability measurements despite a substantial increase in T2 lesion volume over time. Patients have an increase in total T2 lesion volume in the brain regardless of their clinical status or disability measurements. T2 lesion volumes as outcomes in therapeutic clinical trials on MS should be viewed as secondary outcomes rather than as surrogate markers of clinical responses

Magnetic resonance (MR) imaging is the pre-eminent modality for the detection and characterization of central nervous system pathology. However, in a variety of disease processes, histopathologic studies have often shown more extensive abnormalities in the brain and spinal cord than could be detected on conventional MR images. Magnetization transfer contrast (MTC) can be used qualitatively to augment differences between tissues and to accentuate gadolinium enhancement. Additionally, MTC may be used quantitatively to characterize tissues and potentially to detect otherwise microscopic disease

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) accounts for a significant portion of primary intra-axial lesions in cases of traumatic brain injury. The goal of this study was to use diffusion-weighted MR imaging to characterize DAI in the setting of acute and subacute traumatic brain injury. METHODS: Nine patients ranging in age from 26 to 78 years were examined with conventional MR imaging (including fast spin-echo T2-weighted, fluid-attenuated inversion-recovery, and gradient-echo sequences) as well as echo-planar diffusion-weighted MR imaging 1 to 18 days after traumatic injury. Lesions were characterized as DAI on the basis of their location and their appearance on conventional MR images. Trace apparent diffusion coefficient (ADC) maps were computed off-line with the diffusion-weighted and base-line images. Areas of increased signal were identified on the diffusion-weighted images, and regions of interests were used to obtain trace ADC values. RESULTS: In the nine patients studied, isotropic diffusion-weighted images showed areas of increased signal with correspondingly decreased ADC. In one case, decreased ADC was seen 18 days after the initial event. CONCLUSION: Decreased ADC can be demonstrated in patients with DAI in the acute setting and may persist into the subacute period, beyond that described for cytotoxic edema in ischemia

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is the most common inflammatory disease of the central nervous system and manifests both physical and neurocognitive disabilities. Although predominantly a disease of the white matter, MS is also characterized by lesions in the gray matter. Previous pathologic studies have found that cortical and deep gray matter lesions comprised 5% and 4%, respectively, of total lesions. Using software for lesion detection and quantitation, our study was designed to determine MS involvement in the cortical and deep gray matter and to correlate gray matter lesion load with neurocognitive function and the Kurtzke Expanded Disability Status Scale. METHODS: Using a semiautomated segmentation algorithm that detected and delineated all possible brain MS lesions on MR images, we investigated gray matter lesion volume in 18 patients with untreated relapsing-remitting MS. Cortical and deep gray matter lesions then were correlated with the neurocognitive and physical disability measurements. RESULTS: We found that cortical gray matter lesions comprised approximately 5.7% of the total lesion volume, whereas deep gray matter lesions comprised another 4.6% in this patient cohort. No strong correlations were found between gray matter lesions and disability status or neurocognitive function. CONCLUSION: These results are similar to those found in previous pathologic studies. The cortical lesion load in cases of relapsing-remitting MS, as measured by MR imaging, represents less than 6% of the total lesion volume and does not correlate with disability measures or neurocognitive tests

PURPOSE: The purpose of this study was twofold: first, to compare two different measures of lesion burden in patients with multiple sclerosis (MS), the magnetization transfer ratio (MTR) histogram and T2 lesion volume; and, second, to investigate the relationship between lesion burden and atrophy in patients with MS. METHODS: Thirty patients with MS were examined with MR imaging, including fast spin-echo T2- and proton density-weighted sequences as well as magnetization transfer sequences. The lesion burden in each subject was quantitated by MTR histographic analysis and by a computer-based method for calculating the total volume of lesions on T2-weighted images. Additionally, the CSF volume, the brain parenchymal volume, and the percentage of brain parenchymal volume were determined in all patients by using this method and were compared with measurements in eight control subjects. RESULTS: Significant loss of parenchymal volume was seen in patients with MS as determined by increased CSF volume and decreased percentage of brain parenchymal volume relative to that in age-matched control subjects. An inverse correlation was observed between the peak height of the MTR histogram and T2 lesion volume. T2 lesion volume corresponded positively with CSF volume and inversely with percentage of brain parenchymal volume. The peak height of the MTR histogram corresponded positively with percentage of brain parenchymal volume and inversely with CSF volume. CONCLUSION: MS patients sustain a significant loss of parenchymal volume (atrophy), which corresponds strongly with increasing lesion burden. T2 lesion volume and peak height of the MTR histogram show good correlation, and the peak height of the MTR histogram shows a superior correlation with measures of brain atrophy as compared with measurements of T2 lesion volume, suggesting that the MTR histogram may be a better indicator of global disease burden than is T2 lesion volume

PURPOSE: The purpose of this study was to compare contrast-enhanced GRE and conventional SE (CSE) fat-suppressed T1-weighted techniques in the evaluation of head and neck lesions. A hybrid, opposed phase, frequency-selective, fat-suppressed fast multiplanar spoiled GRE (FMPSPGR) sequence was compared with a fat-suppressed CSE sequence. METHOD: Thirty-two patients with head and neck pathology were evaluated with both fat-suppressed CSE and FMPSPGR sequences. Regions of interest obtained by two viewers in consensus were used to establish contrast-to-noise (CNR) and signal-to-noise ratios for both sequences. Three neuroradiologists also independently reviewed the images for quality of fat suppression, lesion conspicuity, and potential pitfalls. RESULTS: The CNR of the FMPSPGR sequence was superior to that of the fat-suppressed CSE sequence. Subjectively, all three reviewers rated the FMPSPGR sequence as having fat suppression equal to or better than that in the CSE sequence in 94% of cases. Imaging times for the FMPSPGR sequence were 60-75% faster than those for the CSE sequence. CONCLUSION: Enhanced imaging of the head and neck region using an opposed phase, fat-suppressed GRE sequence results in improved fat suppression compared with the CSE technique, with substantial savings in imaging time