Faculty Bibliography

PURPOSE: To evaluate the MR findings in the central nervous systems of patients with deletions of the long arm of chromosome 18 (18q- syndrome). METHODS: Sixteen patients with 18q- syndrome ranging in age from 3 to 46 years (mean, 17 years) were studied with high-field-strength MR imaging. Images were analyzed for abnormal T2 hyperintensity in the white matter, abnormal T2 hypointensity in the deep gray matter, and atrophy. RESULTS: Ten of 16 patients had abnormal white matter. Diffuse, bilaterally symmetric deep white matter T2 hyperintensity, most pronounced in the periventricular regions, was most common, noted in eight cases. Focal deep white matter lesions and/or abnormalities involving the subcortical white matter were also noted in four cases. The cerebellum, brain stem, and corpus callosum were spared. Ventriculomegally associated with volume loss, and abnormal T2 hypointensity in the basal ganglia and/or thalami were each present in 11 patients. CONCLUSIONS: The 18q- syndrome is associated with white matter disease and abnormal T2 hypointensity in the deep gray matter. The basis for the white matter abnormalities is unknown, but may be related to one of the two genes for myelin basic protein included in the deleted segment of chromosome 18

PURPOSE: To compare proton MR spectroscopic alterations with the degree of contrast enhancement in multiple sclerosis (MS) lesions. METHODS: Thirty-five patients with clinically diagnosed MS were studied with MR spectroscopy. A total of 47 lesions were examined. Solvent-suppressed proton spectra were acquired with an echo time of 16 milliseconds using the point-resolved spectroscopic localization method from 1.5 cm3 voxels. Marker peaks/creatine (Cr) ratios obtained from these spectra were plotted against the relative enhancement of the lesion seen after administration of contrast material. The relative enhancement was defined as S(contrast) -S0/S0, where S0 is the signal intensity of a T1-weighted image and S(contrast) is the signal intensity after administration of gadopentetate dimeglumine. RESULTS: We found a positive linear relationship between the marker peaks/Cr ratio and the degree of enhancement of the lesion. That is, the marker peaks/Cr ratio was higher in the lesions that showed the greatest enhancement. CONCLUSION: The MR/Cr ratio obtained with the use of short-echo-time proton MR spectroscopy correlates with the degree of contrast enhancement. This ratio may therefore serve as a means for evaluating and quantifying the level of inflammatory activity within the plaques of patients with MS

Magnetization transfer imaging (MTI) has been shown to be sensitive to both macroscopic and microscopic disease in multiple sclerosis (MS). In this study three-dimensional MTI was used to estimate the global burden of disease in large volumes of brain tissue. MTI was performed in 15 MS patients and 11 normal controls. In seven MS patients MTI was performed on two different occasions. MTI data were displayed as magnetization transfer ratio (MTR) histograms and analyzed. The peak height of the histograms, presumably reflecting the residual amount of normal brain tissue, was lower in MS patients as compared with normal controls (P < 0.001), and was found to correlate with the duration of disease (P < 0.05). A decrease of the MTR histogram peak height was observed in the course of the disease (P < 0.01). These findings suggest that in MS, volumetric MTI provides quantitative information reflecting the global burden of disease

PURPOSE: To characterize plaques of multiple sclerosis (MS) using both proton MR spectroscopy and magnetization transfer (MT) imaging. METHODS: The magnetization transfer ratio (MTR) was calculated from two series of three-dimensional gradient-recalled acquisition in the steady state (GRASS) images obtained with and without an MT saturation pulse. Proton spectra were acquired using the point-resolved spectroscopy (PRESS) sequence with a voxel size of 1.5 x 1.5 x 1.5 cm3. A total of 28 spectra were obtained in 13 patients who had clinically definitive MS. The spectra were analyzed together with the MTR. RESULTS: A positive relationship was found between the N-acetylaspartate (NAA)/creatine (Cr) ratio and the MTR in MS plaques, whereas no significant correlation was found between the metabolite ratios and the signal intensity on fast spin-echo T2-weighted MR images. CONCLUSION: Small changes in the MTR of MS plaques relative to the MTR of normal white matter may reflect inflammatory changes and edema, whereas larger changes in MTR correlate with decreased NAA/Cr ratio and therefore suggest demyelination and irreversible damage from chronic MS plaques

RATIONALE AND OBJECTIVES: Nonionic iodinated contrast media have proved effective for computed tomography (CT) of the head and have demonstrated greater tolerability than their ionic counterparts. Iodixanol is a new nonionic agent with the added attribute of being isosmolar to blood and having less than half the osmolality of iohexol. Phase I safety, tolerance, and pharmacokinetic studies have indicated that iodixanol may be associated with fewer adverse effects than iohexol while providing equivalent diagnostic information. METHODS: We compared the safety and efficacy of iodixanol at 270 mg I/ ml (IOD-270) and at 320 mg I/ml (IOD-320) with iohexol 300 mg I/ml (IOH-300). RESULTS: No statistically significant differences in the quality of images or in the occurrence of adverse events were found among the three treatment groups. Pairwise comparisons of injection-associated discomfort revealed that significantly more patients in the IOH-300 group experienced discomfort than in either the IOD-270 or IOD-320 groups. CONCLUSION: Iodixanol at 270 or 320 mg I/ml was found to be safe and effective when administered intravenously at a volume of 100 ml for intracranial CT scans in adult patients

PURPOSE: To evaluate the effect of MR imaging of the brain on four domains of patient care: diagnosis, diagnostic workup, therapy, and prognosis. METHODS: Pre- and post-MR written questionnaires and oral interviews were administered to the referring clinicians of 103 medical and neurologic inpatients at a tertiary care institution. Additional information was obtained from radiologic reports and records. RESULTS: The study population had a diverse array of signs and symptoms and of presumptive clinical diagnoses, reflecting the breadth of disease seen at our institution. The vast majority of physicians (89%) reported that MR imaging added significant diagnostic information, playing an important role in guiding diagnostic workup (24%), planning treatment (34%), and estimating prognosis (47%). MR imaging was significantly more likely to decrease than to increase confidence in the presumptive clinical diagnosis. Thus, MR imaging may be most useful in the setting of diagnostic uncertainty. CONCLUSION: Our results show that MR imaging of the brain has important effects on each of the four domains of care for medical inpatients

PURPOSE: Our goal was to evaluate the use of the magnetization transfer ratio (MTR) in the detection of diffuse axonal injury (DAI) resulting from traumatic brain injury in a swine model. METHOD: DAI was created by applying a nonimpact, coronal plane, rotational acceleration to the heads of miniature swine (n = 4). GE imaging was performed with and without off-resonance MT saturation. Histologic correlation of axonal injury with MRI was performed 7 days postinjury. Thirty-one subcortical white matter regions and 10 deep white matter regions were selected for the direct comparison of histologic data and MTR measurements. RESULTS: Nineteen of 41 examined locations exhibited histologic evidence of axonal injury. The mean MTR in regions with axonal damage was significantly less than in regions without axonal damage. These changes were observed both in regions demonstrating high signal intensity on T2-weighted images (T2WI) (p <0.0001, n = 6) and in regions with no signal intensity change on T2WI (p < 0.05, n = 13). CONCLUSION: These results suggest that the measurement of MTR may have the potential for evaluation axonal damage in DAI following traumatic brain injury even when conventional T2WI does not demonstrate the lesion

PURPOSE: To investigate the relationship between the enhancement pattern of a multiple sclerosis lesion and its magnetization transfer effect. METHODS: Fifty-four lesions were chosen from 29 patients with multiple sclerosis on the basis of enhancement pattern on contrast-enhanced T1-weighted MR images. They included 14 homogeneously enhancing lesions, 26 nonenhancing lesions, and 14 ring-enhancing lesions. Magnetization transfer ratios of the homogeneously enhancing lesions, nonenhancing lesions, and central portion of the ring-enhancing lesions were measured. Means were calculated and compared. RESULTS: The magnetization transfer ratios for homogeneously enhancing lesions were higher (mean, 32.2%; SD, 3.4%) than those for nonenhancing lesions (mean 29.4%; SD, 4.3%) and for the central portion of ring-enhancing lesions (mean, 24.5%; SD, 4.0%). Significant differences were found between the ring-enhancing lesions and the homogeneously enhancing lesions and between the ring-enhancing lesions and the nonenhancing lesions. CONCLUSION: We found a relationship between decreased magnetization transfer ratios and those enhancement patterns in which myelin is known to be decreased histopathologically. Thus, use of the magnetization transfer technique may increase the specificity of MR imaging in assessing the extent of residual myelination in multiple sclerosis lesions

BACKGROUND: Quantitative magnetic resonance imaging (MRI) studies demonstrate reduced brain volumes in schizophrenics, but specific structural abnormalities have not been clearly delineated. The structural abnormalities of this disorder are likely to be heterogeneous, consistent with its diverse clinical presentation. To investigate the relationship between structural abnormality and clinical symptoms, we examined regional brain and cerebral spinal fluid (CSF) volumes in a large sample of schizophrenic patients and controls, with patients aggregated into clinical subtypes. METHODS: Right and left hemisphere frontal and temporal lobe brain and CSF volumes were quantified from 5-mm axial spin-echo MRIs for 71 schizophrenic patients and 77 age- and sex-matched controls. The following four standardized rating scales were used to assess symptom severity: Negative Symptoms, Disorganization, Schneiderian Delusions and Hallucinations, and Suspicion-Hostility. Patients were also subtyped as either deficit or nondeficit on the basis of enduring negative symptoms. RESULTS: Schizophrenic patients overall exhibited abnormal brain asymmetry, with selective decrease in brain volume in the left temporal and right frontal regions. Left temporal lobe parenchymal volume reduction and CSF volume increase were correlated with the severity of negative symptoms. Consistent with this, the subtype analysis revealed abnormal temporal lobe asymmetry for the deficit subgroup only. Right frontal lobe volume reduction correlated with the duration of illness, independent of symptom severity or schizophrenic subtype. CONCLUSIONS: Abnormal lateral asymmetry suggests selective structural deficits in schizophrenia, rather than diffusely undifferentiated CNS abnormalities. The pattern of regional abnormalities is related to clinical symptoms, with negative symptoms being associated with left temporal lobe rather than frontal lobe abnormality. This is consistent with suggestions of a temporolimbic prefrontal network abnormality in schizophrenia. Further longitudinal studies are warranted, using higher-resolution MRI technology and gray matter-white matter segmentation to confirm and extend these findings

We report the occurrence of clinically definite multiple sclerosis in an offspring of a couple with conjugal multiple sclerosis. Extensive investigation of all members of this family, which includes two additional asymptomatic children, eliminated the possibility of alternative neurological diagnoses. All family members were studied with magnetic resonance imaging (MRI), evoked potentials, and human leukocyte antigen (HLA) typing. An asymptomatic child had subtle white matter abnormalities on MRI, suggesting subclinical neurological involvement. This study documents the third case of multiple sclerosis in the child of conjugal multiple sclerosis patients and provides the first report of MRI lesions in an asymptomatic offspring of the same parents. Neurodiagnostic and immunogenetic investigations of such rare family clusters may contribute to the elucidation of the pathogenesis of multiple sclerosis