MR imaging of multiple sclerosis: comparison with clinical and CT examinations in 74 patients

Morphometrics of the entire human spinal cord and spinal canal measured from in vivo high-resolution anatomical magnetic resonance imaging

STUDY DESIGN

Measurements of cervical and thoracolumbar human spinal cord (SC) geometry based on in vivo magnetic resonance imaging and investigation of morphological "invariants."

OBJECTIVE

The current work aims at providing morphological features of the complete in vivo human normal SC and at investigating possible "invariant" parameters that may serve as normative data for individualized study of SC injuries.

SUMMARY OF BACKGROUND DATA

Few in vivo magnetic resonance image-based studies have described human SC morphology at the cervical level, and similar description of the entire SC only relies on postmortem studies, which may be prone to atrophy biases. Moreover, large interindividual variations currently limit the use of morphological metrics as reference for clinical applications or as modeling inputs.

METHODS

Absolute metrics of SC (transverse and anteroposterior diameters, width of anterior and posterior horns, cross-sectional SC area, and white matter percentage) were measured using semiautomatic segmentation of high resolution in vivo T2*-weighted transverse images acquired at 3 T, at each SC level, on healthy young (N = 15) and older (N = 8) volunteers. Robustness of measurements, effects of subject, age, or sex, as well as comparison with previously published postmortem data were investigated using statistical analyses (separate analysis of variance, Tukey-HSD, Bland-Altman). Normalized-to-C3 parameters were evaluated as invariants using a leave-one-out analysis. Spinal canal parameters were measured and occupation ratio border values were determined.

RESULTS

Metrics of SC morphology showed large intra- and interindividual variations, up to 30% and 13%, respectively, on average. Sex had no influence except on posterior horn width (P < 0.01). Age-related differences were observed for anteroposterior diameter and white matter percentage (P < 0.05) and all postmortem metrics were significantly lower than in vivo values (P < 0.001). In vivo normalized SC area and diameters seemed to be invariants (R > 0.74, root-mean-square deviation < 10%). Finally, minimal and maximal occupation ratio were 0.2 and 0.6, respectively.

CONCLUSION

This study presented morphological characteristics of the complete in vivo human SC. Significant differences linked to age and postmortem state have been identified. Morphological "invariants" that could be used to calculate the normally expected morphology accurately, were also identified. These observations should benefit to biomechanical and SC pathology studies.

LEVEL OF EVIDENCE

N/A.

An image-based approach to understanding the physics of MR artifacts

As clinical magnetic resonance (MR) imaging becomes more versatile and more complex, it is increasingly difficult to develop and maintain a thorough understanding of the physical principles that govern the changing technology. This is particularly true for practicing radiologists, whose primary obligation is to interpret clinical images and not necessarily to understand complex equations describing the underlying physics. Nevertheless, the physics of MR imaging plays an important role in clinical practice because it determines image quality, and suboptimal image quality may hinder accurate diagnosis. This article provides an image-based explanation of the physics underlying common MR imaging artifacts, offering simple solutions for remedying each type of artifact. Solutions that have emerged from recent technologic advances with which radiologists may not yet be familiar are described in detail. Types of artifacts discussed include those resulting from voluntary and involuntary patient motion, magnetic susceptibility, magnetic field inhomogeneities, gradient nonlinearity, standing waves, aliasing, chemical shift, and signal truncation. With an improved awareness and understanding of these artifacts, radiologists will be better able to modify MR imaging protocols so as to optimize clinical image quality, allowing greater confidence in diagnosis.

Magnetic resonance imaging findings in acute canine distemper virus infection

Demyelination is the prominent histopathological hallmark in the acute stage of canine distemper virus infection. Magnetic resonance imaging is an important diagnostic tool in human beings to determine demyelination in the brain, for example in multiple sclerosis. Five young dogs with clinically suspected canine distemper virus infection were subjected to magnetic resonance imaging of the brain and histopathological and immunohistochemical examinations. Hyperintense lesions and loss of contrast between grey and white matter were detected in T2-weighted images in the cerebellum and/or in the brainstem of three dogs, which correlated with demyelination demonstrated in histopathological examination. Furthermore, increased signal intensities in T2-weighted images were seen in the temporal lobe of four dogs with no evidence of demyelination. Magnetic resonance imaging seems to be a sensitive tool for the visualisation of in vivo myelination defects in dogs with acute canine distemper virus infection. Postictal oedema and accumulation of antigen positive cells have to be considered an important differential diagnosis.

Multiprotocol MR image segmentation in multiple sclerosis: experience with over 1,000 studies

RATIONALE AND OBJECTIVES

Multiple sclerosis (MS) is an acquired disease of the central nervous system. Several clinical measures are commonly used to express the severity of the disease, including the Expanded Disability Status Scale and the ambulation index. These measures are subjective and may be difficult to reproduce. The aim of this research is to investigate the possibility of developing more objective measures derived from MR imaging.

MATERIALS AND METHODS

Various magnetic resonance (MR) imaging protocols are being investigated for the study of MS. Seeking to replace the Expanded Disability Status Scale and ambulation index with an objective means to assess the natural course of the disease and its response to therapy, the authors have developed multiprotocol MR image segmentation methods based on fuzzy connectedness to quantify both macrosopic features of the disease (lesions, gray matter, white matter, cerebrospinal fluid, and brain parenchyma) and the microscopic appearance of diseased white matter. Over 1,000 studies have been processed to date.

RESULTS

By far the strongest correlations with the clinical measures were demonstrated by the magnetization transfer ratio histogram parameters obtained for the various segmented tissue regions. These findings emphasize the importance of considering the microscopic and diffuse nature of the disease in the individual tissue regions. Brain parenchymal volume also demonstrated a strong correlation with clinical measures, which suggests that brain atrophy is an important disease indicator.

CONCLUSION

Fuzzy connectedness is a viable, highly reproducible segmentation method for studying MS.

ADEM: literature review and case report of acute psychosis presentation

Acute disseminated encephalomyelitis is a monophasic, immune-mediated disorder that produces multifocal demyelinating lesions within the central nervous system. It is characterized clinically by the acute onset of neurologic abnormalities, including varying degrees of mental state changes ranging from drowsiness to coma. It is unusual for the illness to present as an isolated acute psychosis. The case of a 14-year-old female with biopsy-confirmed acute disseminated encephalomyelitis, who was initially diagnosed with an acute psychiatric disorder, is presented, and published reports on this unusual manifestation are reviewed. A Medline database search was performed from 1965 to 1999, using the terms acute disseminated encephalomyelitis, postvaccinal encephalomyelitis, postinfectious encephalomyelitis, and measles encephalomyelitis, combined with the terms psychosis, psychiatric disorder, and behavioral disorder. Selected cross-referenced reports were also reviewed. Nine patients were identified who presented with acute psychosis. We conclude that, although rare, acute disseminated encephalomyelitis can present as an acute psychosis. This immune-mediated condition should be included in the differential diagnosis of neurologic disorders presenting as a psychiatric illness.

Multiple sclerosis lesion quantification using fuzzy-connectedness principles

Multiple sclerosis (MS) is a disease of the white matter. Magnetic resonance imaging (MRI) is proven to be a sensitive method of monitoring the progression of this disease and of its changes due to treatment protocols. Quantification of the severity of the disease through estimation of MS lesion volume via MR imaging is vital for understanding and monitoring the disease and its treatment. This paper presents a novel methodology and a system that can be routinely used for segmenting and estimating the volume of MS lesions via dual-echo fast spin-echo MR imagery. A recently developed concept of fuzzy objects forms the basis of this methodology. An operator indicates a few points in the images by pointing to the white matter, the grey matter, and the cerebro-spinal fluid (CSF). Each of these objects is then detected as a fuzzy connected set. The holes in the union of these objects correspond to potential lesion sites which are utilized to detect each potential lesion as a three-dimensional (3-D) fuzzy connected object. These objects are presented to the operator who indicates acceptance/rejection through the click of a mouse button. The number and volume of accepted lesions is then computed and output. Based on several evaluation studies, we conclude that the methodology is highly reliable and consistent, with a coefficient of variation (due to subjective operator actions) of 0.9% (based on 20 patient studies, three operators, and two trials) for volume and a mean false-negative volume fraction of 1.3%, with a 95% confidence interval of 0%-2.8% (based on ten patient studies).

Prognostic value of magnetic resonance imaging in monosymptomatic optic neuritis

PURPOSE

Magnetic resonance imaging is able to depict lesions in the optic nerve in the acute stage of monosymptomatic optic neuritis. Most patients have lesions located intraorbitally, intracanalicularly, and/or intracranially. The goal of this study is to determine whether these lesions resolve after visual recovery, change in length or localization, or could be correlated to the visual function.

METHODS

Between 1987 and 1992, the authors examined 22 patients with acute optic neuritis using magnetic resonance imaging short-time inversion recovery sequences. Additionally, the authors determined visual acuity, visual field, color vision, contrast sensitivity, and visual-evoked responses. All patients were re-examined between 1993 and 1994 in the same manner. Visual recovery in the re-examination was divided into three groups: group 1 with complete visual recovery (visual acuity better than 20/25); group 2 with incomplete recovery (visual acuity better than 20/25 but defect in at least one of the other tests: visual field, color vision, and contrast sensitivity); and group 3 with partial recovery (visual acuity remained less than 20/25, defect in all the other tests).

RESULTS

All group 1 patients initially had lesions less than 17.5 mm, group 2 patients had lesions greater than 17.5 mm (44%) and/or lesions located intracanalicularly (66%), and most of group 3 patients initially had lesions greater than 17.5 mm (79%).

CONCLUSION

Eyes with lesions less than 17.5 mm in the optic nerve in acute optic neuritis have a good prognosis for visual recovery. Lesions greater than 17.5 mm or lesions involving the intracanalicular portion of the optic nerve lead to incomplete or partial visual recovery.

MR imaging of multiple sclerosis simulating brain tumor

Multiple sclerosis may sometimes present as a mass lesion that is indistinguishable from brain tumor both clinically and radiologically. We describe two cases of multiple sclerosis simulating brain tumor on computed tomography (CT) scans and magnetic resonance (MR) images, one of which was proved and another was suggestive to be demyelinating disease by biopsy. Steroid therapy produced regression of the lesions of MR images and CT scans. Our cases and others in the literature suggest strategies for detecting multiple sclerosis presenting as a mass lesion.

Multiple sclerosis of the spinal cord: magnetic resonance appearance

OBJECTIVE

To determine the MR appearance of spinal cord multiple sclerosis (MS) plaques in patients presenting with myelopathy by using a high-field (1.5 T) imager.

MATERIALS AND METHODS

We studied 119 patients who underwent high-field (1.5 T) MR studies of the spinal cord for evaluation of myelopathy. All 119 patients were thought to have possible findings of spinal cord MS at the time of the MRI interpretation.

RESULTS

Sixty-four plaques were studied in 47 patients with clinically definite MS and adequate quality MRI. Of these patients 68% had a single spinal cord plaque, 19% had two plaques, and 13% had three or more plaques. Sixty-two percent of the plaques occurred in the cervical spinal cord and most frequently involved the posterior (41%) and lateral (25%) aspects of the spinal cord. None of the 64 lesions involved the entire thickness of the spinal cord. The lesion length varied from 2 to 60 mm, with 84% of the lesions < 15 mm in length. The spinal cord diameter was unchanged in 84% of plaques, enlarged at the level of the lesion in 14%, and atrophic in 2%. Just over half (55%) of the plaques enhanced with intravenously administered gadolinium. Of the patients who received synchronous head and spinal cord examinations on the same day, 24% had normal findings on the MR study of the head. Follow-up spinal cord studies were available in nine patients. New lesions developed in two patients, while previously described lesions resolved. In three patients only new lesions developed. In four patients no change occurred in the existing number of cord plaques.

CONCLUSION

Spinal cord demyelinating plaques present as well-circumscribed foci of increased T2 signal that asymmetrically involve the spinal cord parenchyma. Knowledge of their usual appearance may prevent unnecessary biopsy. An MR examination of the head may confirm the imaging suggestion of spinal cord demyelinating disease, because up to 76% of patients have abnormal intracranial findings. In the remaining 24% of cases in which the clinical diagnosis is not certain and MR findings in the head are negative, a follow-up spinal cord study is recommended, because these lesions evolve and change over time.

Magnetisation transfer ratios and transverse magnetisation decay curves in optic neuritis: correlation with clinical findings and electrophysiology

Conventional MRI sequences do not permit the distinction between the different pathological characteristics (oedema, demyelination, gliosis, axonal loss) of the multiple sclerosis plaque. Magnetisation transfer imaging and transverse magnetisation decay curve (tMDC) analysis may be more specific. These techniques have been applied to the optic nerves in 20 patients with optic neuritis and the results correlated with clinical and visual evoked potential (VEP) findings. tMDC analysis failed to identify separate intracellular and extracellular water compartments within the optic nerve but gave a measure of transverse relaxation time (T2) without the confounding effects of CSF in the nerve sheath. Both T2 and magnetisation transfer ratio (MTR) were abnormal after an episode of optic neuritis. T2 did not correlate with visual function or with VEP latency or amplitude. There was a significant correlation between MTR reduction and prolongation of VEP latency: this increased latency may reflect an effect of myelin loss on MTR. Longer lesions were associated with worse visual outcome, implying that the overall extent of pathological involvement is likely to influence the degree of functional deficit.

An unusual cerebral mass lesion

Images

Optic neuritis: findings on MRI, CSF examination and HLA class II typing in 60 patients and results of a short-term follow-up

Optic neuritis (ON) is a common first manifestation of multiple sclerosis (MS), and examination of patients with ON provides opportunities to study the early clinical stages of MS. This prospective study compares results of brain magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) examinations and HLA-Dw2 phenotyping in 60 consecutive patients with ON. At a median of 17 days after the onset of ON, 69% had oligoclonal IgG bands, and at a median on 79 days after onset, 53% had multiple (> or = 3) white matter lesions on MRI. Subgroup analyses revealed that MRI abnormalities and oligoclonal IgG bands were equally common in patients examined early or late after the onset of ON. Strong correlations were found between the presence of MRI abnormalities and oligoclonal IgG bands. The HLA-Dw2 phenotype was significantly increased in ON patients compared with controls, but also significantly different from a group of MS patients from the same geographical area. A significant relation was found between Dw2 phenotype and oligoclonal IgG bands. During a mean follow-up time of about 2 years, the diagnosis in 17 of the patients changed to clinically definite MS. Initially, 16 of them had oligoclonal IgG bands and 12 had three or more MRI lesions. Both MRI and CSF studies are important diagnostic tools in the workup of ON patients.

Using gadolinium-enhanced magnetic resonance imaging lesions to monitor disease activity in multiple sclerosis

The highly variable clinical course and the lack of a direct measurement of disease activity have made evaluation of experimental therapies in multiple sclerosis (MS) difficult. Recent studies indicate that clinically silent lesions can be demonstrated by magnetic resonance imaging (MRI) in patients with mild relapsing-remitting MS. Thus, MRI may provide a means for monitoring therapeutic trials in the early phase of MS. We studied 12 patients longitudinally for 12 to 21 months with monthly gadolinium (Gd)-enhanced MRIs. The data have been used to identify the most effective design of a clinical trial using Gd-enhanced lesions as the outcome measure. Frequent ( > 1/mo) Gd-enhancing lesions were observed in 9 of the 12 patients, indicating that the disease is active even during the early phase of the illness. The frequency of the lesions was not constant; there was marked fluctuation in lesion number from month to month. However, the magnitude of the peak number of lesions and the frequency of the peaks varied among patients. Because of this variability, the most effective use of Gd-enhancing lesions as an outcome measure in a clinical trial was a crossover design with study arms of sufficient duration to allow accurate estimation of lesion frequency. Monitoring Gd-enhancing lesions may be an effective tool to assist in the assessment of experimental therapies in early MS.

The utility of MRI in acute stage of carbon monoxide poisoning

Intracranial abnormalities by magnetic resonance imaging (MRI) in acute carbon monoxide (CO) poisoning have been described in two cases. Edematous bilateral lesions have been demonstrated in the globus pallidus. Findings correspond with the pathological changes described in literature. In our experience MIR is a more sensitive examination compared to serial computed tomography (CT) in acute CO poisoning.

MRI of anterior spinal artery syndrome of the cervical spinal cord

Cervical spinal cord lesions in the anterior spinal artery syndrome were delineated on magnetic resonance images (MRI) in four patients. The lesion was always seen anteriorly in the cervical cord. On T2-weighted images, the lesions appeared hyperintense relative to the normal spinal cord, while on T1-weighted images, two chronic lesions appeared hypointense, with local atrophy of the cord. In one case, repeated T1-weighted images showed no signal abnormality 4 days after the ictus, but the lesion became hypointense 18 days later, when contrast enhancement was also recognized after injection of Gd-DTPA; this sequence of intensity changes was similar to that of cerebral infarction. The extent of the lesion seen MRI correlated closely with neurological findings in all cases. Although the findings may not be specific, MRI is now the modality of choice for confirming the diagnosis in patients suspected of having an anterior spinal artery syndrome.

Memory and learning disturbances in multiple sclerosis. MRI lesions and neuropsychological correlation

Thirty-five patients with definite multiple sclerosis (MS) were studied. They underwent neuropsychological testing and magnetic resonance imaging (MRI). The MRI findings at different brain areas levels were compared with the neuropsychological findings. A quantitative system was used to measure MRI-MS lesions. In this series, a positive correlation was established between memory and learning disturbances measured by Battery 144, and the lesions measured by MRI (total, hemispheric and, particularly, periventricular lesions). MRI can detect MS lesions, and this study shows that a correlation between MRI and neuropsychological findings is possible if quantitative methods are used to distinguish different MS involvement areas in relation to neuropsychological tasks. These findings suggest that hemispheric lesions in MS produce cognitive disturbances and MRI could be a useful tool in predicting memory and learning impairment.

Improved sensitivity of MRI in multiple sclerosis by use of extensive standardized procedures

The relative value of two different MRI procedures for the assessment of infratentorial extension in multiple sclerosis (MS) was studied. Multislice spin-echo techniques were used overall. Procedure A consisted of parasagittal T1-weighted images (500/30) and axial T2-weighted images (2500/30, 2500/120). Procedure B consisted of parasagittal T2-weighted images (1600/35, 1600/90). In the parasagittal T2-weighted images clear visualization of MS lesions is achieved because signal intensities of CSF and normal nervous tissue are nearly identical. All images were performed with a 0.5 Tesla MR system. Data were obtained in 98 patients with definite (N = 30) or probable MS (N = 68). Areas with abnormal signal intensity in the infratentorial regions (brainstem, cerebellum, and/or cervical spinal cord) were identified in 44% of the patients with procedure A and in 64% with procedure B. The standard application of the combination of both procedures improves the sensitivity of the MR examination for the diagnosis of MS, the delineation of infratentorial lesions and the correlation between clinical and MR data without excessively increasing imaging time.

One-year MR imaging follow-up of patients with multiple sclerosis under cortisone therapy

Twenty patients with relapsing/remitting course of MS were studied four times with MR imaging over the course of one year. First MR was undertaken during the acute relapse, afterwards patients were given cortisone therapy for four to six weeks. The second MR study followed 4-6 weeks after the first, the patients at this time being in remission. The third MR study was carried out 4 months after the first, the last scan one year after the first. The total number of lesions varied, though not greatly, over the whole follow-up, but there was an influence of the clinical course of MS on the pattern of lesions in MR imaging, mostly in respect to the number of confluences and the size of the lesions. Follow-up over one year showed that the inflammatory process produced an increase in the number of plaques, independent of the fact that most patients stayed in remission. A delayed effect of the cortisone therapy on the size, number, and confluence of plaques is suggested whilst clinical signs improved in most cases immediately after the beginning of drug therapy. Independent of the clinical course of the disease in some cases plaques previously seen vanished and others appeared in one and the same examination.

Serial magnetic resonance scanning in multiple sclerosis: a second prospective study in relapsing patients

A prospective study of serial magnetic resonance (MR) scans of the brain was carried out every 2 weeks for 4 to 6 months in 9 patients with mild, clinically definite, relapsing/remitting multiple sclerosis (MS). Six of the 9 patients developed a total of 12 asymptomatic new lesions in various parts of the brain. In none of the patients were the changes on MR scan accompanied by relevant new neurological symptoms or signs. New MR lesions had a characteristic temporal profile, reaching a maximum size in approximately 4 weeks before gradually shrinking, usually leaving a small residual abnormality indistinguishable from chronic MS lesions. The frequent occurrence of new asymptomatic lesions indicates that MS may be a more active process even in mildly affected asymptomatic patients than has been previously realized. The results emphasize the potential importance of using MR scanning to measure disease activity in laboratory studies of MS and in the assessment of treatment, particularly in asymptomatic patients in the early stages. We suggest that the expanding and contracting new lesions are the basic or primary lesion in MS, that the characteristic demyelinated plaque is represented by the small residual area that these lesions shrink down to, and that the typical collection of scattered white matter lesions in chronic MS may represent the accumulated residua of dozens or more of these active lesions occurring over many years.

Multiple sclerosis: diagnostic value of computerized tomography with delayed scanning after a double-dose of contrast medium in comparison with other diagnostic tests

In 63 cases of clinical definite or suspected MS we compared the results of CSF analysis, VEP, BAEP, CT scanning without and after double dose contrast, in 17 cases also those of MRT. We found that CSF analysis had the highest rate of abnormal findings, followed by MRT. VEP and CT with double dose contrast showed similar sensitivity, while BAEP and CT without contrast had disappointing results. We think that CT with delayed scanning after double dose contrast can be a very useful investigation in early and doubtful cases of MS, until MRT will become a more widespread and less expensive investigation.

Topological characteristics of brainstem lesions in clinically definite and clinically probable cases of multiple sclerosis: an MRI-study

Disseminated lesions in the white matter of the cerebral hemispheres and confluent lesions at the borders of the lateral ventricles as seen on MRI are both considered acceptable paraclinical evidence for the diagnosis of multiple sclerosis. Similar changes are, however, also found in vascular diseases of the brain. We therefore aimed at identifying those additional traits in the infratentorial region, which in our experience are not frequently found in cerebrovascular pathology. We evaluated MR brain scans of 68 patients and found pontine lesions in 71% of cases with a clinically definite diagnosis (17 out of 24) and in 33% of cases with a probable diagnosis (14 out of 43). Lesions in the medulla oblongata were present in 50% and 16%, respectively, and in the midbrain in 25% and 7%, respectively. With rare exceptions all brainstem lesions were contiguous with the cisternal or ventricular cerebrospinal fluid spaces. In keeping with post-mortem reports the morphological spectrum ranged from large confluent patches to solitary, well delineated paramedian lesions or discrete linings of the cerebrospinal fluid border zones and were most clearly depicted form horizontal and sagittal T2 weighted SE-sequences. If there is a predilection for the outer or inner surfaces of the brainstem, such lesions can be considered an additional typical feature of multiple sclerosis and can be more reliably weighted as paraclinical evidence for a definite diagnosis.

Magnetic resonance imaging in infections of the brain: findings in tuberculosis, listeriosis, toxoplasmosis, subacute sclerosing panencephalitis, and multiple sclerosis

A total of 6 patients with various inflammatory brain diseases were investigated by MRI. Typical diagnostic criteria like signal intensity, location, and morphology of the lesions are presented. MRI proves to be a highly sensitive method to detect encephalitic foci, which, however, suffers from a low specificity. Therefore additional informations like case history, clinical findings, and serological data have to be considered to find the correct diagnosis.

Progressive multifocal leucoencephalopathy with magnetic resonance imaging verification and therapeutic trials with interferon

Progressive multifocal leucoencephalopathy was diagnosed by magnetic resonance imaging (MRI) and brain biopsy in a 44-year-old woman, for whom therapeutic trials with various antiviral agents were made. Despite early diagnosis and treatment, her neurological deterioration and extension of MRI-detectable lesions were not halted for a period of about 8 months. After the introduction of intrathecal beta-interferon therapy, her neurological status and MRI findings became stable and showed minimal improvement. Early diagnosis of this fatal disorder is important and intrathecal interferon therapy should be considered.

MRI of Listeria rhombencephalitis

A case of Listeria rhombencephalitis in a patient, who was evaluated by MRI, is reported. MRI showed areas of high signal intensity on T2-weighted images in the rhombencephalon and confirmed the clinical diagnosis of a brainstem affection by Listeria monocytogenes.

Balance of T1-weighted images before and after application of a paramagnetic substance (Gd-DTPA)

Ten patients with encephalitis disseminata and 10 patients with cerebral ischemia underwent computed tomography and magnetic resonance imaging examinations. The results before and after the application of contrast media were compared. It is shown that T1-weighted MRI images, even after application of gadolinium-DTPA, are of little value for differential diagnosis of these diseases. In contrast, T2-weighted images did support the diagnosis of an acute stage of encephalitis disseminata versus acute ischemia. This was also true for lesions that had not been adequately depicted by computed tomography.

Magnetic resonance imaging and clinical relationships in multiple sclerosis

Magnetic resonance imaging (MRI) was done in 109 patients with suspected demyelinating disease (56 with clinical multiple sclerosis [MS] and 53 without). Of those with clinical MS, 43 (77%) had multifocal lesions of the white matter detected on MRI; 12 of the 43 also had confluent periventricular signaling. Nine patients (17%) without clinical MS had similar findings. Of the 56 patients with MS, 35 underwent both computed tomography (CT) and MRI. In this group, 80% of MRI scans showed multiple demyelinating lesions compatible with MS, as compared with 29% of the CT scans. A CT scan was "positive" more often if obtained within 1 month after an attack of MS than later. In contrast, the sensitivity of MRI or the number of lesions detected by MRI did not increase in patients with recent exacerbations. MRI was "positive" in patients with clinical MS more often than was any single evoked response study. In statistical analyses, both the sensitivity of MRI and the number of lesions were associated with the duration of MS. A pattern of confluent periventricular signaling around the lateral ventricle was associated with greater duration of MS and patient disability.