Magnetic resonance spectroscopy of cerebral cortex is normal in hereditary hyperekplexia due to mutations in the GLRA1 gene

Excessive startling and stiffness in hereditary hyperekplexia has been attributed to lack of inhibition at either the cortical or brainstem level. Six patients with hereditary hyperekplexia (HH) and a confirmed mutation in the gene encoding the alpha(1) subunit of the glycine receptor (GLRA1) underwent single voxel (1)H magnetic resonance spectroscopy (MRS) of the brainstem and an area of frontal cortex and white matter using a method that allows absolute quantification of metabolites. The results of MRS were within normal limits, although there was a tendency for the neuronal marker N-acetyl aspartate to be reduced in the brainstem of patients compared with that in controls. Thus, we found no evidence to support a deficit in the cerebral cortex in patients with hereditary hyperekplexia due to mutations in the GLRA1 gene.

Clinical-MRI correlations in a European trial of interferon beta-1b in secondary progressive MS

BACKGROUND

The recently completed placebo-controlled multicenter randomized trial of interferon beta-1b (Betaferon) in 718 patients with secondary progressive MS shows significant delay of disease progression and reduction of relapse rate. This study provides an opportunity to assess the level of relationship between clinical and MRI outcomes in this cohort of patients with secondary progressive MS.

METHODS

Brain T2-weighted lesion volume was measured annually in all available patients, with visual analysis to identify any new or enlarging (active) T2 lesions at each annual time point. A subgroup of 125 patients had monthly gadolinium-enhanced, T1-weighted imaging at months 0 to 6 and 18 to 24. Relapses were documented and expanded disability status scale (EDSS) was measured every 3 months.

RESULTS

For the annual MRI outcomes, a significant but modest correlation was identified between the change in T2 lesion volume from baseline to the final scan and the corresponding change from baseline in EDSS (r = 0.17, p < 0.0001). There were significant correlations between the cumulative number of active T2 lesions and 1) change in EDSS (r = 0.18, p < 0.0001) and 2) relapse rate (r = 0.24, p < 0.0001). In the subgroup of 125 patients undergoing monthly imaging, MRI lesion activity was correlated with relapse rate over months 0 to 24 (r = 0.24, p = 0.006) but not with change in EDSS.

CONCLUSIONS

These results confirm that the clinical-MRI relationships previously identified in relapsing-remitting MS still are apparent in the secondary progressive phase of the disease and support the use of MRI as a relevant outcome measure. In view of the relatively modest nature of the correlations, it seems unwise to rely on such MRI measures alone as primary efficacy variables in secondary progressive MS trials.

Quantitative MRI in patients with secondary progressive MS treated with monoclonal antibody Campath 1H

BACKGROUND

To assess the long-term effect of the lymphocyte-depleting humanized monoclonal antibody Campath 1H on MR markers of disease activity and progression in secondary progressive MS patients.

METHODS

Twenty-five patients participated in a crossover treatment trial with monthly run-in MR scans for 3 months, followed (after a single pulse of Campath 1H) by monthly MR scans from months 1 to 6 and again from months 12 to 18. MR analysis was performed to provide measurements of the number and volume of gadolinium (Gd)-enhancing lesions as well as the hypointense lesion volume on a T1-weighted sequence. In addition, serial measurements of T2 brain lesion volume, brain volume, and spinal cord cross-sectional area were made over the duration of the study. The relationship between clinical and MR measures of disease evolution was also assessed.

RESULTS

Treatment was associated with a reduction in the number and volume of Gd-enhancing lesions (p < 0.01). Despite this, a decrease in brain volume was seen in 13 patients during the 18 months post-treatment. The mean pretreatment Gd-enhancing lesion volume was predictive of subsequent reduction in brain volume (r = 0.77, p = 0.002). Reduction in brain volume also correlated with the change in T1 hypointense lesion volume after treatment (r = 0.53, p < 0.01). A reduction in spinal cord area was also seen throughout the study duration, and this correlated with an increase in disability (r = 0.65, p = 0.01).

CONCLUSION

Campath 1H treatment was associated with a sustained and marked reduction in the volume of Gd enhancement, indicating suppression of active inflammation. Nevertheless, many patients developed increasing brain and spinal cord atrophy, T1 hypointensity, and disability. This study highlights the potential role for novel MR techniques in monitoring the effect of treatment on the pathologic process in MS.

Improved imaging of the spinal cord in multiple sclerosis using three-dimensional fast spin echo

We report assessment of a new three-dimensional fast spin echo (3D FSE) sequence in ten patients with clinically definite multiple sclerosis, comparing it with standard 2D FSE, and in ten normal controls. We saw 29 focal lesions on the 2D images and 53 on the 3D FSE images (P = 0.05); none were seen in controls. Lesion length was significantly smaller on the 3D FSE than on to the 2D FSE images (3D: 1.36; 2D 2.0; P = 0.03). This may relate in part to separation into several lesions on the 3D images of confluent abnormal signal seen on 2D and in part to detection of small lesions missed by the thicker 2D FSE slices (3 mm compared to 1.5 mm). The 3D FSE sequence looks promising in improving spinal cord imaging.

Phase I study of paclitaxel and etoposide for metastatic or recurrent malignancies

The authors define the dose-limiting toxicities and the recommended phase II doses of paclitaxel combined with etoposide, without and with filgrastim support. Patients with advanced solid tumors were eligible if they had a performance status of 0 to 2 and normal renal, hepatic, and bone marrow function. Patients with cardiac arrhythmias or congestive heart failure requiring medical therapy were excluded. Prior radiation was allowed only if it involved less than 30% of the marrow-containing skeleton. The dose of etoposide was fixed at 100 mg/m2/d for 3 days beginning on day 1. Paclitaxel was administered over 3 hours on day 4. The dose of paclitaxel was escalated until the maximum tolerated dose (MTD), without and with filgrastim 5 microg/kg (or 300 microg total dose) subcutaneously beginning on day 5, was reached. Treatment cycles were repeated every 21 days. Of 39 patients entered, 37 were evaluable for toxicity and 30 for response. The principal toxicity was neutropenia. Without filgrastim, the MTD of paclitaxel was 150 mg/m2. With filgrastim, the dose of paclitaxel was escalated to 250 mg/m2 in combination with etoposide 100 mg/m2. One episode of pulmonary toxicity was observed. Five patients responded: two with previously treated non-small-cell lung cancer (NSCLC), two with refractory small-cell lung cancer (SCLC), and one with refractory germ-cell tumor (GCT). We conclude that paclitaxel and etoposide can be given in combination at clinically relevant doses with filgrastim support. In this phase I trial, a dose of paclitaxel of 200 mg/m2 on day 4 and etoposide at 100 mg/m2/d on days 1-3, with filgrastim 5 microg/kg beginning on day 5, was found to be well tolerated, and can be recommended for future studies. Without filgrastim, a paclitaxel dose of 150 mg/m2 with the same dose of etoposide can also be recommended.

MRI of the optic nerve in benign intracranial hypertension

We investigated the MRI appearance of the optic nerve and its cerebrospinal-fluid-containing sheath in 17 patients with benign intracranial hypertension (BIH) and 15 normal controls. Using phased-array local coils, 3-mm coronal T2-weighted fat-suppressed fast spin-echo images were obtained with an in-plane resolution of < 0.39 mm. The optic nerve and its sheath were clearly differentiated. An enlarged, elongated subarachnoid space around the optic nerve was demonstrated in patients with BIH. High-resolution MRI of the optic nerve offers additional information which may be of value for diagnosis and in planning and monitoring treatment.

Lesion discrimination in optic neuritis using high-resolution fat-suppressed fast spin-echo MRI

Fast spin-echo (FSE) is a new sequence with acquisition times currently down to one-sixteenth of those obtained with conventional spin-echo sequences, which allows high-resolution (512 x 512 matrix) images to be acquired in an acceptable time. We compared the higher resolution of FSE with the medium resolution of a short inversion-time inversion-recovery (STIR) sequence in depicting the optic nerves of healthy controls and patients with optic neuritis. Optic nerve MRI examinations were performed in 18 patients with optic neuritis and 10 normal controls. Two sequences were obtained coronally: fat-suppressed FSE (FSE TR 3250 ms/TEef 68 ms, echo-train length 16, 4 excitations, 24 cm rectangular field of view, 3 mm interleaved contiguous slices, in-plane resolution 0.5 x 0.5 mm) and STIR (TR 2000 ms/TE 50 ms/TI 175 ms, in-plane resolution 0.8 x 0.8 mm, slice thickness 5 mm). FSE demonstrated much more anatomical detail than STIR, e.g. distinction of optic nerve and sheath. Lesions were seen in 20 of 21 symptomatic nerves using FSE and in 18 of 21 using STIR. Nerve swelling or partial cross-sectional lesions of the optic nerve were each seen only on FSE in 3 cases. Fat-suppressed FSE imaging of the optic nerve improves anatomical definition and increases lesion detection in optic neuritis.

A preliminary study into the sensitivity of disease activity detection by serial weekly magnetic resonance imaging in multiple sclerosis

Long TR and gadolinium enhanced spin echo brain MRI was performed weekly for three months in three patients with relapsing-remitting or secondary progressive multiple sclerosis. During the study, 38 new enhancing lesions were seen; 11 showed enhancement for less than four weeks, and two enhanced on only one scan. All 16 new lesions seen on long TR scans showed initial enhancement. When only every fourth (monthly) scan was analysed, a total of 33 new enhancing lesions were seen. Subject to confirmation in a larger cohort, the results suggest: (a) that blood brain barrier leakage is an invariable event in new lesion development in relapsing-remitting and secondary progressive multiple sclerosis; (b) the small increase in sensitivity of weekly scanning does not justify its use in preference to monthly scanning when monitoring treatments.

MR magnetization transfer measurements in temporal lobe epilepsy: a preliminary study

MR magnetization transfer ratio was measured in both hippocampi of three patients with temporal lobe epilepsy, and in two control subjects. The magnetization transfer ratio in each section was significantly lower on the affected side than on the contralateral side and in control subjects. Magnetization transfer ratio measurements are relatively fast and precise, this preliminary study shows that they may provide useful presurgical information.

High resolution magnetic resonance imaging of the anterior visual pathway in patients with optic neuropathies using fast spin echo and phased array local coils

High resolution MRI of the anterior visual pathways was evaluated using frequency selective fat suppressed fast spin echo (FSE) sequences in conjunction with phased array local coils in patients with optic neuropathies. Fifteen normal controls and 57 patients were examined. Coronal T2 weighted fat suppressed FSE images were obtained in 11 minutes with an in plane resolution of 0.39 x 0.39 mm. The optic nerve and its sheath containing CSF were clearly differentiated. Central retinal vessels were often visible. In demyelinating optic neuritis and in anterior ischaemic optic neuropathy high signal within the nerve was readily delineated. Meningiomas and gliomas involving the optic nerve were precisely visualised both in the orbit and intracranially. Extrinsic compression of the optic nerves was readily visualised in carotid artery ectasia and dysthyroid eye disease. Enlarged subarachnoid spaces around the optic nerves were demonstrated in benign intracranial hypertension. High resolution MRI of the anterior visual pathway represents an advance in the diagnosis and management of patients presenting with optic neuropathy.

Correlation of magnetization transfer ratio with clinical disability in multiple sclerosis

We performed spin echo magnetic resonance imaging with and without application of an off-resonance saturation pulse in 43 patients with multiple sclerosis (MS), 10 age-matched controls, and 4 elderly asymptomatic patients with the radiological diagnosis of small-vessel disease. Magnetization transfer (MT) ratio images were obtained from these. All MS subgroups (primary progressive, secondary progressive, benign, early relapsing-remitting) showed significantly lower average lesion MT ratios than small-vessel disease patients. Secondary progressive MS patients showed significantly lower lesion MT ratios than those with benign disease, and there was an inverse correlation of disability with average lesion MT ratio. The degree of reduction of MT ratios is an indicator of the extent of tissue destruction. Thus, reduced MT ratios in MS may provide an indication of the degree of demyelination and axonal loss, both of which are likely to cause functional deficits in MS. We conclude that MT measurement is (1) a robust quantitative method that may increase the pathological specificity of magnetic resonance imaging, (2) has the potential to differentiate demyelination in MS from less destructive pathological changes, and (3) may be useful in monitoring modifications in tissue structure brought about by treatment.

Magnetic resonance imaging in degenerative ataxic disorders

MRI of the brain was performed in 53 patients with a variety of degenerative ataxias and related disorders and 96 control subjects. Atrophy of intracranial structures was not seen in patients with the pure type of hereditary spastic paraplegia, or in early cases of Friedreich's ataxia. In advanced Friedreich's ataxia there was atrophy of the vermis and medulla. The MRI features of early onset cerebellar ataxia with retained reflexes were variable, and suggest heterogeneity. In autosomal dominant cerebellar ataxias, most patients had cerebellar and brainstem atrophy, probably reflecting the pathological process of olivopontocerebellar atrophy; there was no clearly defined group with both clinical and imaging features of isolated cerebellar involvement. The MRI abnormalities in idiopathic late onset cerebellar ataxia were predominantly those of cerebellar and brainstem atrophy or pure cerebellar atrophy. The clinical and imaging features of brainstem abnormalities were discordant in several patients. Pure cerebellar atrophy was associated with slower progression of disability. Cerebral atrophy was common in the late onset ataxias. Cerebral white matter lesions, although usually few in number, were observed in significantly more patients than controls, particularly those aged over 50 years.

Serial gadolinium-enhanced MRI in relapsing/remitting multiple sclerosis of varying disease duration

In the planning of MRI protocols to monitor disease activity in multiple sclerosis (MS), the clinical subtype needs to be considered. In this serial gadolinium-enhanced MRI study, we demonstrated differences between patients with early relapsing/remitting MS and benign MS in both the production of new lesions and the occurrence of enhancement.

Histopathology of multiple sclerosis lesions detected by magnetic resonance imaging in unfixed postmortem central nervous system tissue

Postmortem unfixed whole brains from 17 multiple sclerosis and 6 control cases were examined by magnetic resonance imaging (MRI) using a T2-weighted spin echo sequence and histology to determine the relationship between areas of abnormal MRI signal and underlying pathological change. In group 1, small MRI lesions and correspondingly small plaques, most of which were chronic, were detected histologically in 5 brains. In 4 brains there were more extensive areas of both abnormal signal and histological plaques which were more often active (group 2). However, in a further 5 brains extensive MRI abnormalities were observed when only small periventricular plaques were present histologically (group 3). Lesions in the hindbrain and cerebral grey matter were infrequently observed by MRI. The extensive MRI abnormalities seen in areas in which only small histological plaques were found may be the result of vascular permeability changes in the normal-appearing white matter surrounding plaques.

Precise relaxation time measurements of normal-appearing white matter in inflammatory central nervous system disease

Precise relaxation time (RT) measurements have been made, with a standard deviation of 3% for T1 and T2 in white matter in normal volunteers. This sets an upper limit to the instrumental random errors (imprecision). Achieving this precision requires careful adjustment and use of the imager. The wide variation in RTs seen by other workers may be in part due to larger instrumental errors. We have measured RTs (both T1 and T2) in normal-appearing white matter in 16 normal controls and patients with multiple sclerosis (MS, 18), systemic lupus erythematosis (SLE, 16) and cerebral sarcoidosis (8). Both RTs were significantly higher in MS than in other patient groups and controls (P less than .05), possibly caused by microscopic lesions. T2 was elevated in SLE patients relative to controls and sarcoidosis patients (P less than .05), possibly because of microhemorrhages. Lesion RTs were abnormal but more variable and no significant differences between diseases were found.

STIR sequences in NMR imaging of the optic nerve

Orbital fat surrounding the optic nerve causes considerable difficulties in NMR imaging due to its high image intensity and the chemical shift artefact. We have investigated the ability of inversion recovery sequences with short inversion times (STIR sequences) to suppress fat signals in imaging the optic nerve. We have also compared the contrast attainable with STIR sequences with that obtainable from other sequences. Measurements were made on 4 normal controls and 5 patients with multiple sclerosis (MS) to obtain typical values of relaxation times and proton densities for orbital fat, cerebral white matter and MS lesions. The fat T1 measurements were used to predict an appropriate inversion time for the STIR sequence and estimate how much residual fat signal might be expected as a result of natural variations in fat T1. STIR sequences can be used to suppress the signal from orbital fat with little residual signal. Measurements from white matter and MS lesions were used to predict the contrast between normal and pathological tissues that is attainable with STIR sequences. STIR contrast compares favourably with that obtainable from other sequences.

Accuracy and precision in the measurement of relaxation times from nuclear magnetic resonance images

The accuracy (proximity to the true value) and precision (reproducibility) of relaxation times derived from nuclear magnetic resonance images were investigated. Two methods of deriving relaxation times were considered. A patient scanning protocol in which the minimum number of scans necessary for the calculation (three) were performed. Calculated T1 and T2 images were then formed. An animal (cat) protocol in which many more scans were performed. The data were read from the display and fitted by computer to the theoretical curves. The accuracy of the measurements was determined by an empirical method. A series of bottles with different concentrations of MnCl2 and CuSO4 in water were prepared and their relaxation times determined using the imager as a simple pulsed spectrometer. These values were compared with those derived from images. Over the normal range of tissue values (T1 less than 700 ms, T2 less than 200 ms) the animal protocol gave values of T1 up to 1% shorter than the true values. The T2 values were up to 5% shorter. Patient protocol values were up to 7% shorter for T1 and up to 20% shorter for T2. There was some difference between results for MnCl2 and for CuSO4 (particularly for patient T2s), suggesting that the results depend to a small extent on the T1/T2 ratio. The precision of the values was investigated by considering the standard deviations (SDs) of brain tissue measurements over populations of cats (animal protocols) and normal control subjects and multiple sclerosis patients (patient protocols). These were compared with the SDs of measurements of calibration bottles scanned with the patients. Standard deviations of 3% for T1 and 6% for T2 were found over 19 cats using the animal protocols; SDs of 7% for T1 and 14% for T2 were found over 15 normal control subjects using the patient protocols. Standard deviations of bottle measurements were similar to these figures. There are also variations between different subjects and different regions of the brain. There was no significant change between readings on the same patient in follow-up studies. Other sources of variation in the measurements made with the patient protocols were investigated by scanning phantoms. Noise in T1 and T2 images is about 2%. Spatial non-uniformity within slices is about 1% for T1 and 10% for T2. Non-uniformity between slices in multislice sets is 4% for T1 and 14% for T2. There is no long-term variation in measured values over 9 months; short-term variation is approximately 1%.

The role of nuclear magnetic resonance imaging in the diagnosis of Arnold-Chiari malformation

The diagnosis and demonstration of an Arnold-Chiari malformation (ACM), in particular the Type I ACM, presents a challenge to the clinician and diagnostic imaging specialist. Various imaging techniques have been used to demonstrate this condition in the past; as with other pathologies, the value of nuclear magnetic resonance imaging (NMRI) will naturally be compared with current techniques in the diagnosis of this abnormality. In this paper the authors give a brief history of the condition, an indication of current imaging techniques, and suggest an important role for NMRI in the demonstration of Arnold-Chiari malformations.