Biomedical subjects

R I Grossman

Publications and source records attributed to R I Grossman.

At least 37 records · Page 2Linked to original sources

PubMed2000

The contribution of MRI in the differential diagnosis of posterior fossa damage.

In multiple sclerosis patients, magnetic resonance imaging (MRI) frequently detects lesions in the brain stem and cerebellum. However various pathologies that have a predelection to occur in posterior fossa parenchyma may share similar features with inflammatory-demyelinating lesions. In this paper, we review the contribution of MRI to the differential diagnosis of posterior fossa pathology. Vascular lesions due to chronic hypoperfusion and arteriolosclerosis or occlusion of the main supplying arteries of the posterior circulation leading to acute infarction frequently produce characteristic pontine or cerebellar lesions. Neoplastic disease, in particular pontine gliomas in younger patients may have similar MRI features and may be difficult to distinguish from inflammatory-demyelinating lesions. Central pontine myelinolysis usually occurs in severely ill patients but the pontine MRI changes have an overlapping profile with inflammatory demyelination. Diffuse axonal injury of the midbrain and brainstem after head trauma and atrophy of posterior fossa structures in degenerative diseases may appear similar on MRI to tissue changes also seen frequently in MS. Analysis of the MRI appearance and clinical information is most often useful to narrow the fairly long list of differential diagnoses of posterior fossa pathology.

Brain Diseases↗

PubMed2000

Assessment of posterior fossa damage in MS using MRI.

In multiple sclerosis (MS), brain stem and cerebellum are frequent sites of damage in clinically isolated syndromes at presentation and it is likely that lesions located in such structures can have an important impact on the development of disability in the definite forms of the disease. In patients presented with isolated brain stem syndromes, the symptomatic lesion was often not detected by magnetic resonance (MR) imaging. But patients with asymptomatic infratentorial lesions progressed to clinically definite MS in 65% of cases. Infratentorial lesions are included in various MR criteria designed to assist in the differential diagnosis of MS lesions from incidental lesions, to differentiate MS from subcortical encephalopathic arteriopathy. The preferred MR sequence to visualize infratentorial lesions is the fast spin echo sequence. It is preferred to conventional spin echo and fast fluid attenuated inversion recovery sequences because of its relatively short acquisition time and good sensitivity. The correlation between disability and infratentorial lesion load on T2 weighted sequences is controversial. However, it was recently shown that the correlations between clinical measures and T1 lesion load, histogram magnetization transfer ratio and peak positions, and infratentorial volume measurements are strong. These findings suggest that one of the major factors in the development of disability in patients with MS is the pathological damage in clinically eloquent sites such as the brain stem and cerebellum.

Brain Diseases↗

PubMed2000

The contribution of magnetic resonance imaging in the differential diagnosis of the damage of the cerebral hemispheres.

There are presently many magnetic resonance (MR) measures that can aid the assessment of damage to the brain. The conventional measures include T2 lesion volume, T1 enhanced lesion volume, and brain atrophy. Newer methodologies include magnetization transfer measures and proton spectroscopy. These methods have the potential for improving the specificity of MR with respect to the underlying pathology. MR spectroscopy offers the ability to quantitate the component of axonal loss in multiple sclerosis. MR techniques can be implemented to assess the effectiveness of treatment algorithms.

Blood-Brain Barrier↗

PubMed2000

Total brain N-acetylaspartate: a new measure of disease load in MS.

OBJECTIVE: To quantitate the extent of neuronal cell loss in MS via the whole brain's N-acetylaspartate (NAA) concentration (WBNAA). METHODS: Because NAA is assumed to be present only in neuronal cell bodies and their axons, we measured WBNAA as a marker for viable neurons in 12 patients (9 women and 3 men, 26 to 53 years of age) suffering from relapsing-remitting (RR) MS for at least 5 years and compared them with 13 age- and sex-matched normal controls. Total brain NAA was determined with proton MR spectroscopy, and WBNAA was obtained by dividing it by the total brain volume, calculated from high resolution MRI. RESULTS: The WBNAA of the RR MS patients was lower than their matched controls (p<0.005). This difference was greater among older than younger subjects. The linear prediction equations of WBNAA with age indicate a faster, x10, decline in the patients, approximately 0.8% per year of age (p = 0.022). CONCLUSION: The age-dependent decrease of whole brain N-acetylaspartate (WBNAA) in the patients suggests that progressive neuronal cell loss is a cardinal feature of this disease. WBNAA offers a quick, highly reproducible measure of disease progression and may be an important marker of treatment efficacy in MS as well as other neurodegenerative diseases.

Adolescent↗

PubMed2000

Reduced dorsal and orbital prefrontal gray matter volumes in schizophrenia.

BACKGROUND: Converging neuroanatomic, neurophysiological, and neurobehavioral evidence implicate prefrontal subregions in schizophrenia. Neuroanatomic studies with magnetic resonance (MR) imaging enable regional volume parcellation. Inconsistent reports may relate to variable methods and small samples. We attempted to resolve volume differences within sectors of the prefrontal lobe in a large sample, relating volumes to clinical and neurocognitive features. METHODS: Magnetic resonance imaging was performed in 70 patients with schizophrenia (40 men and 30 women; 29 neuroleptic naive and 41 previously treated) and 81 healthy controls (34 men and 47 women). Gray and white matter volumes of the dorsolateral, dorsomedial, orbitolateral, and orbitomedial prefrontal cortex were quantified. Symptoms, functioning, and neurocognition were assessed concurrently. RESULTS: Reduced prefrontal gray matter volume was observed in patients. The reduction was evident for the dorsolateral area in men (9%) and women (11%), for the dorsomedial area only in men (9%), and for orbital regions only in women (23% and 10% for lateral and medial, respectively). The reduction of orbital volume in women was associated with poorer premorbid functioning, more severe negative symptoms, and depression. Volume of dorsal cortex was positively associated with better performance on abstraction and attention tasks across all groups. CONCLUSIONS: Schizophrenia is associated with reduced gray matter volume in prefrontal cortex, which affects men and women in the dorsolateral sector. The effects are moderated by sex for dorsomedial and orbital regions and are related to symptom severity and cognitive function. This is not a by-product of treatment, since the differences are evident in neuroleptic-naive patients.

Adult↗

PubMed2000

Temporolimbic volume reductions in schizophrenia.

BACKGROUND: Neuroanatomic studies of schizophrenia have reported temporolimbic abnormalities. Most magnetic resonance imaging studies have evaluated small samples of primarily men with chronic schizophrenia. Our goal was to evaluate sex differences in segmented temporal lobe subregions with reliable parcellation methods, relating volume with clinical and neurocognitive parameters. METHODS: Magnetic resonance imaging was performed in 100 patients with schizophrenia (58 men, 42 women; 39 neuroleptic naive, 61 previously treated) and 110 healthy controls (51 men, 59 women). Gray and white matter volumes of temporolimbic (hippocampus and amygdala) and neocortical regions (superior temporal gyrus and temporal pole) were examined. Symptoms, functioning, and neurocognition were assessed concurrently. RESULTS: Hippocampal gray matter volume was reduced in men (7%) and women (8.5%) with schizophrenia. In the amygdala, however, decreased volume was evident for men (8%) whereas women (10.5%) had increased volume. Magnetic resonance imaging of the temporal pole showed decreased gray matter in men (10%) and women (8.5%). For the superior temporal gyrus, the decrease exceeded that of whole-brain only in men (11.5%). Volumes were largely uncorrelated with clinical measures, but higher hippocampal volumes were associated with better memory performance for all groups. Cortical volumes were associated with better memory performance in healthy women. CONCLUSIONS: Schizophrenia is associated with reduced gray matter volume in temporolimbic structures. In men, reduction was manifested in all regions, whereas women showed decreased hippocampal volumes but increased amygdala volumes. The abnormalities are evident in patients with first-episode schizophrenia and correlate more strongly with cognitive performance than with symptom severity.

Adult↗

PubMed2000

Magnetization transfer imaging of traumatic brain injury.

Magnetization transfer imaging (MTI) has been shown to be sensitive for the detection of white matter abnormalities in entities such as multiple sclerosis, progressive multifocal leukoencephalopathy, and wallerian degeneration. Our hypothesis was that MTI would detect traumatic white matter abnormalities (TWMA) and provide information additional to that obtainable with routine spin- and gradient-echo imaging. We hypothesized that the presence of TWMA defined by MTI would correlate with outcome following TBI. Twenty-eight victims of head trauma and 15 normal controls underwent magnetic resonance imaging including MTI. Magnetization transfer ratios (MTR) were calculated for areas of shearing injury and for normal-appearing white matter (NAWM) in locations frequently subject to diffuse axonal injury. Abnormal MTRs were detected in NAWM in eight patients. All eight had persistent neurologic deficits, including cognitive deficits, aphasia, and extremity weakness. Seven of the 28 patients had no abnormal findings on neurologic exam at discharge, transfer, or follow-up. None of these patients had an abnormal MTR in NAWM. In the remaining 13 patients, who had persistent neurologic deficits, no regions of abnormal MTR were detected in NAWM. MTI is a sensitive method for the detection of TWMA. Detection of abnormal MTR in NAWM that is prone to axonal injury may predict a poor patient outcome. The presence of normal MTR in NAWM in these areas does not necessarily confer a good outcome, however.

Adult↗

PubMed2000

Numerical tissue characterization in MS via standardization of the MR image intensity scale.

Image intensity standardization is a recently developed postprocessing method that is capable of correcting the signal intensity variations in MR images. We evaluated signal intensity of healthy and diseased tissues in 10 multiple sclerosis (MS) patients based on standardized dual fast spin-echo MR images using a numerical postprocessing technique. The main idea of this technique is to deform the volume image histogram of each study to match a standard histogram and to utilize the resulting transformation to map the image intensities into standard scale. Upon standardization, the coefficients of variation of signal intensities for each segmented tissue (gray matter, white matter, lesion plaques, and diffuse abnormal white matter) in all patients were significantly smaller (2.3-9.2 times) than in the original images, and the same tissues from different patients looked alike, with similar intensity characteristics. Numerical tissue characterizability of different tissues in MS achieved by standardization offers a fixed tissue-specific meaning for the numerical values and can significantly facilitate image segmentation and analysis.

Adult↗

PubMed2000

The accuracy of whole brain N-acetylaspartate quantification.

A non-localizing pulse sequence to quantify the total amount of N-acetylaspartate (NAA) in the whole brain (WBNAA) was introduced recently [Magn. Reson. Med. 40, 684-689 (1998)]. However, it is known that regional magnetic field inhomogeneities, deltaB0s, arising from susceptibility differences at tissue interfaces, shift and broaden local resonances to outside the integration window, leading to an underestimation of the true amount of NAA in the entire brain. To quantify the upper limit of this loss, the whole-head proton MR spectrum (1H-MRS) of the water was integrated over the same frequency width as the NAA. The ratio of this area/total-water-line was 75 +/- 5% in 5 volunteers. The procedure was repeated with the brain-only water peak, obtained by summing signals only from voxels within that organ from a three-dimensional chemical-shift-imaging (3D CSI) set. It indicated that <10% of the water signal loss occurred in the brain. Therefore, by analogy, WBNAA accounts for >90% of that metabolite.

Adult↗

PubMed2000

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA).

RATIONALE AND OBJECTIVES: The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system. METHODS: Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques. RESULTS: No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation. CONCLUSIONS: Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.

Adult↗

PubMed2000

The representation of the horizontal meridian in the primary visual cortex.

The authors report the findings of two patients that confirm the location of the horizontal meridian in the human visual cortex. The first patient had an inferior quadrant defect with a band of horizontal meridian sparing. Magnetic resonance imaging showed a lesion concentrated along the medial striate cortex. The second patient had a homonymous horizontal defect that resulted from removal of an arteriovenous malformation located in the lateral striate cortex. The findings of these two patients demonstrate that the horizontal meridian is represented at the calcarine fissure base in the primary visual cortex.

Adult↗

PubMed2000

Brain atrophy in relapsing-remitting multiple sclerosis and secondary progressive multiple sclerosis: longitudinal quantitative analysis.

PURPOSE: To determine annual rates of volumetric changes in the whole-brain parenchyma of patients with relapsing-remitting and secondary progressive multiple sclerosis (MS) and test the hypothesis that these changes correlate with clinical disability. MATERIALS AND METHODS: A computer-assisted segmentation technique with thin-section magnetic resonance (MR) imaging was used in 36 patients with MS (27 relapsing-remitting, nine secondary progressive) and in 20 control subjects to quantify brain and cerebrospinal fluid volumes. To determine the degree of brain atrophy, the percentage brain parenchyma volume (PBV) relative to that of intracranial contents was calculated. RESULTS: At the beginning of the study, the PBV was smaller in the MS group than in the control group (P = .007); brain parenchyma volumes were similar. The median rate of brain volume loss was 17.3 mL per year in patients with relapsing-remitting MS and 23.6 mL per year in those with secondary progressive MS. There was a negative correlation between brain atrophy and Expanded Disability Status Scale (EDSS) score in patients with secondary progressive MS (r = -0.69, P = .004) and no correlation in patients with relapsing-remitting MS. T2 lesion volume did not correlate with brain atrophy in either group. CONCLUSION: The correlation between brain atrophy and EDSS score was better in patients with secondary progressive MS than in those with relapsing-remitting MS.

Adult↗

PubMed2000

Multiple sclerosis: magnetization transfer histogram analysis of segmented normal-appearing white matter.

PURPOSE: To investigate and characterize the global distribution of magnetization transfer (MT) ratio values of normal-appearing white matter (NAWM) in patients with relapsing-remitting multiple sclerosis (MS) and test the hypothesis that the MT histogram for NAWM reflects disease progression. MATERIALS AND METHODS: Conventional and MT magnetic resonance (MR) images were obtained in 23 patients and 25 healthy volunteers. Clinical tests for comparison with the MT histogram parameters included the Extended Disability Status Scale and the ambulation index. Lesion load calculated with T2-weighted MR images and whole-brain and white matter volumes were measured. RESULTS: The location of the MT histogram peak and the mean MT ratio for NAWM were significantly lower in patients with MS than in control subjects. In longitudinal studies, the histogram peak location and mean MT ratio shifted in the direction of normal values as the duration of disease increased. A mean of 26.5% of the volume of new lesions identified on the later studies were demonstrated to have originated in NAWM corresponding to "lost" pixels on the histogram. CONCLUSION: MT histogram analysis of NAWM, including longitudinal analysis, may provide new prognostic information regarding lesion formation and increase understanding of the course of the disease.

Adult↗

PubMed2000

Brain imaging.

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Brain Diseases↗

PubMed2000

Peripheral spinal cord hypointensity on T2-weighted MR images: a reliable imaging sign of venous hypertensive myelopathy.

BACKGROUND AND PURPOSE: MR findings reported in conjunction with spinal dural arteriovenous fistula (SDAVF) include cord swelling, increased T2 signal within the spinal cord, and parenchymal enhancement, each of which is nonspecific. Enlarged vessels on the cord surface, the most specific MR finding, is noted in only half of SDAVF patients. Nevertheless, we have frequently observed MR peripheral hypointensity of the spinal cord in SDAVF on T2-weighted images, which is not characteristic of nonvascular or nonhemorrhagic causes of myelopathy and which has not been described in association with SDAVF. We hypothesized that peripheral cord hypointensity might reliably suggest the diagnosis of SDAVF or other causes of venous hypertensive myelopathy. METHODS: We reviewed the MR findings in 11 consecutive cases of angiographically confirmed symptomatic SDAVF and in four cases of intracranial dural arteriovenous fistula with spinal drainage, a lesion that also causes spinal cord deficits mediated by venous hypertensive myelopathy. RESULTS: In each case, T2 hypointensity involving the cord periphery was present. This sign has not been previously described in association with either SDAVF or other causes of venous hypertensive myelopathy. It appears, however, to be a relatively constant imaging feature of SDAVF. CONCLUSION: In the absence of spinal hemorrhage, T2 hypointensity involving the periphery of the spinal cord suggests venous hypertensive myelopathy as a cause of spinal cord dysfunction.

Arteriovenous Fistula↗

PubMed2000

Multiple sclerosis: comparison of trace apparent diffusion coefficients with MR enhancement pattern of lesions.

BACKGROUND AND PURPOSE: Diffusion-weighted MR imaging and the trace apparent diffusion coefficient (ADC) provide important structural information about tissues. The purpose of this study was to investigate the relationship between trace ADC values and the enhancement pattern of multiple sclerosis (MS) lesions. METHODS: Ninety-six lesions, identified in 24 patients with MS, were characterized by their enhancement pattern on contrast-enhanced T1-weighted MR images. There were 57 nonenhancing lesions (NELs), 28 homogeneously enhancing lesions (HELs), and 11 ring-enhancing lesions (RELs). The trace ADC means for each type of lesion and for normal-appearing white matter (NAWM) were calculated and compared using Student's t-test. RESULTS: The mean trace ADC values for HELs (mean, 7.7 x 1(-10) m2s(-1); SD, 1.4 x 10(-10) m2s(-1)) were less than those for RELs (mean, 1.2 x 10(-9) m2s(-1); SD, 3.5 x 10(-10)m2s(-1)) and NELs (mean, 1.3 x 10(-9) m2(s-1); SD, 2.6 x 10(-10) m2(s-1)). There was a significant difference between the mean trace ADC values of HELs and RELs as well as between those for HELs and NELs. There was also a significant difference in the mean trace ADC values between all lesion types and NAWM (mean, 6.9 x 10(-10) m2s(-1); SD, 5.0 x 10(-11) m2s(-1)). CONCLUSION: We found a predictable relationship between mean trace ADC and the pattern of enhancement in MS lesions, corresponding to reported histopathologic differences in myelination between lesion types and magnetization transfer ratios.

Adult↗

PubMed2000

Magnetization transfer imaging in the detection of injury associated with mild head trauma.

BACKGROUND AND PURPOSE: Most traumatic brain injuries are classified as mild, yet in many instances cognitive deficits result. The purpose of this study was to investigate possible relationships between quantitative magnetization transfer imaging (MTI) and neurocognitive findings in a cohort of patients with mild head trauma but negative findings on conventional MR images. METHODS: We examined 13 patients and 10 healthy volunteers with a standard MR protocol including fast spin-echo and gradient-echo imaging, to which was added quantitative MTI. MTI was performed with a modified gradient-echo sequence incorporating pulsed, off-resonance saturation. Both region-of-interest analysis and contour plots were obtained from the MTI data. A subgroup of nine patients was examined with a battery of neuropsychological tests, comprising 25 measures of neurocognitive ability. RESULTS: The magnetization transfer ratio (MTR) in the splenium of the corpus callosum was lower in the patient group as compared with the control group, but no significant reduction in MTR was found in the pons. Individual regional MTR values were significantly reduced in two cases, and contour plot analysis revealed focal areas of abnormality in the splenium of four patients. All the patients showed impairment on at least three measures of the neuropsychological test battery, and in two cases a significant correlation was found between regional MTR values and neuropsychological performance. CONCLUSION: Our results suggest that MTI and contour plot analysis may add sensitivity to the MR imaging examination of patients with traumatic brain injury.

Adult↗

PubMed1999

Evidence for preganglionic pupillary involvement in superficial siderosis.

A 36-year-old man presented with spinal myoclonus, ataxia, hearing loss, and unilateral pupillary dilation. MRI demonstrated hemosiderin deposition along the superficial surfaces of the brain, brainstem, cerebellum, and spine. The pupillary changes were localized to the preganglionic oculomotor nerve. In contrast to vasculopathic oculomotor nerve palsies, superficial siderosis may cause selective involvement of the superficially located pupillary fibers.

Adult↗