Relapsing-Remitting Multiple Sclerosis: Metabolic Abnormality in Nonenhancing Lesions and Normal-appearing White Matter at MR Imaging: Initial Experience

PURPOSE

To quantify, with three-dimensional proton magnetic resonance (MR) spectroscopy, metabolic characteristics of normal-appearing white matter and nonenhancing lesions in patients with relapsing-remitting multiple sclerosis (MS).

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. Nine patients with relapsing-remitting MS (six women, three men) and nine age-matched control subjects (seven women, two men) were studied with T1- and T2-weighted MR imaging and three-dimensional proton MR spectroscopy at spatial resolution less than a cubic centimeter. Absolute N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) levels were obtained from 171 voxels: 66 from lesions on T2-weighted MR images (43 hypointense and 23 isointense on T1-weighted MR images), 31 from normal-appearing white matter, and 74 from analogous normal white matter regions on images in control subjects.

RESULTS

Mean NAA level in hypointense lesions (5.30 mmol/L +/- 2.27 [standard deviation]) was significantly lower (P < or = .05) than that in isointense lesions (7.82 mmol/L +/- 2.28), normal-appearing white matter (7.37 mmol/L +/- 1.71), and normal white matter in control subjects (8.89 mmol/L +/- 1.54). Cho (1.79 mmol/L +/- 0.65) and Cr (5.64 mmol/L +/- 1.50) levels in isointense lesions were indistinguishable from those in normal-appearing white matter (1.74 mmol/L +/- 0.46 and 4.99 mmol/L +/- 0.97, respectively) but were significantly higher (Cho, 20%; Cr, 24%) than those in normal white matter in control subjects (1.44 mmol/L +/- 0.40 and 4.30 mmol/L +/- 1.32, respectively). NAA, Cho, and Cr levels in normal-appearing white matter were significantly different than those in normal white matter in control subjects (NAA, 20% lower; Cho, 14% higher; and Cr, 17% higher).

CONCLUSION

Abnormal metabolic activity persists in all MS tissue types. Increased Cr and Cho levels suggest (a) ongoing gliosis and attempted remyelination in isointense lesions on T1-weighted MR images and (b) membrane turnover (de- and remyelination), in addition to increased cellularity (gliosis, inflammation) in normal-appearing white matter.

Three-dimensional proton spectroscopy of deep gray matter nuclei in relapsing-remitting MS

The metabolic changes in the deep gray matter (GM) nuclei, thalamus, and basal ganglia of patients with relapsing-remitting multiple sclerosis were investigated with quantitative, multivoxel, three-dimensional proton MR spectroscopy. This technique facilitated the study of several bilateral structures in a single session at sub-cubic centimeter spatial resolution. Compared with 9 matched control subjects, the deep GM nuclei of 11 patients showed 7% lower N-acetylaspartate and 14% higher choline levels (p = 0.02 for both).

Quantitative MRI: hidden age-related changes in brain tissue

The advent of MRI has made a remarkable progress in the understanding of age-related brain changes providing a noninvasive tool to study in vivo the normally aging individuals at multiple time points. However, conventional MRI techniques are unable to detect and quantify age-related microstructural changes that have been documented at the post-mortem examination of brain tissues. More sophisticated, quantitative MR techniques such as magnetization transfer imaging, diffusion tensor imaging, and proton MR spectroscopy have been shown to be sensitive to microstructural and metabolic changes that occur in gray and white matter over the course of life span. This review highlights some of these innovative, quantitative MR techniques that are particularly relevant for the study of occult age-related brain tissue changes. Characterization of the in vivo patterns of molecular and cellular changes that occur in the normal aging brain is of crucial importance to understand the pathophysiology of normal cognitive decline and to interpret observed changes in neurodegenerative diseases.

Interferon beta-1a for brain tissue loss in patients at presentation with syndromes suggestive of multiple sclerosis: a randomised, double-blind, placebo-controlled trial

BACKGROUND

In patients who present with clinically isolated syndromes suggestive of multiple sclerosis, interferon beta-1a is effective in delaying evolution to clinically definite disease and in reducing MRI-measured disease activity. We aimed to assess whether this drug can also reduce the rate of brain volume decrease in such patients enrolled in the ETOMS (early treatment of multiple sclerosis) trial.

METHODS

MRI data for brain volume measurements at baseline, month 12, and month 24 were available from 131, 111, and 112 patients assigned treatment (22 microg interferon beta-1a), and 132, 98, and 99 patients assigned placebo respectively. Normalised brain parenchymal volume (NBV) at baseline and percentage brain volume changes (PBVC) were measured with a fully-automated segmentation technique. The primary endpoint was conversion to clinically definite multiple sclerosis due to clinical relapse. Analysis was by intention to treat.

FINDINGS

41 (31%) of 131 patients on interferon beta-1a and 62 (47%) of 132 on placebo converted to clinically definite multiple sclerosis (odds ratio 0.52 [95% CI 0.31-0.86], p=0.0115). Mean PBVC for patients on placebo was -0.83% during the first year, -0.67% during the second year, and -1.68% during the entire study period. Respective values for treated patients were -0.62%, -0.61%, and -1.18%. The changes in brain volume were significant in both groups at all timepoints. A significant treatment effect was detected for month 24 versus baseline values (p=0.0031). The number of new T2 lesions formed during the first year correlated weakly with PBVC during the second year.

INTERPRETATION

Early treatment with interferon beta-1a is effective in reducing conversion to clinically definite multiple sclerosis and in slowing progressive loss of brain tissue in patients with clinically isolated syndromes. The modest correlation between new lesion formation and brain volume decrease suggests that inflammatory and neurodegenerative processes are, at least partly, dissociated from the earliest clinical stage of multiple sclerosis onwards.

Brain tissue loss occurs after suppression of enhancement in patients with multiple sclerosis treated with autologous haematopoietic stem cell transplantation

To assess whether brain tissue loss occurs after profound and sustained suppression of magnetic resonance imaging (MRI) enhancement, we measured brain volume changes from 10 patients with rapidly evolving secondary progressive multiple sclerosis (MS) treated with autologous haematopoietic stem cell transplantation and followed up for 24 months. An average yearly decrease of brain volume of about 1.9% was observed despite only five enhancing lesions seen on triple dose follow up scans of two patients. This indicates that, in MS, progressive loss of tissue can occur independently of concomitant MRI-visible inflammation.

Indirect evidence for early widespread gray matter involvement in relapsing–remitting multiple sclerosis

Multiple sclerosis (MS) has traditionally been viewed as an inflammatory demyelinating white matter (WM) disease of the central nervous system. However, recent pathology and MRI studies have shown lesions in the gray matter (GM) as well. To ascertain the extent of GM involvement, we obtained with nonlocalizing proton MR spectroscopy the concentration of N-acetylaspartate (NAA), a metabolite found almost exclusively in neuronal cells, T2-lesion loads, and GM and WM fractions in the entire brain of 71 relapsing-remitting (RR) MS patients (51 women, 20 men, 25-55 years old) and 41 healthy controls (27 women, 14 men, 23-55 years old). The average whole-brain NAA (WBNAA) difference between the patients and the controls was -2.9 mM (-22%, P < 0.0001); range: +1.2 to -7.8 mM (+8% to -63%). The patients' median T2 lesion volume was 5.5 (range: 0.140-28) cm(3). GM and WM comprised 50.4 +/- 3.8% and 30.4 +/- 5.0% (mean +/- standard deviation), respectively, of the total brain volume in the patients; 53.8 +/- 3.7% and 35.4 +/- 4.7% in the controls. Because WM and GM constitute approximately 40% and 60% of the brain parenchyma, respectively, and the NAA concentration in the former is 2/3 of the latter, WBNAA loss greater than 40% x 2/3 = 27% cannot be explained in terms of WM (axonal) pathology alone and must include widespread GM (neuronal) deficits. Therefore, the concept of MS, even at its earlier stages, as a WM disease might need to be reexamined.

Conventional and magnetization transfer MRI predictors of clinical multiple sclerosis evolution: a medium-term follow-up study

The correlation between conventional MRI lesion load accumulation and multiple sclerosis clinical evolution is only modest. The assessment of brain parenchymal volume and of its changes over time may provide adjunctive MRI markers reflecting the more disabling aspects of multiple sclerosis pathology. Magnetization transfer (MT) MRI is sensitive to 'occult' multiple sclerosis-related brain damage and might also contribute to overcome the clinical/MRI paradox. In this study, we assessed the value of conventional and MT MRI-derived metrics in predicting the medium-term clinical evolution of patients with different multiple sclerosis phenotypes. We studied 73 patients, with relapsing-remitting multiple sclerosis (n = 34), secondary progressive multiple sclerosis (n = 19) and clinically isolated syndromes suggestive of multiple sclerosis (n = 20), and 16 healthy subjects. Brain dual-echo, T1-weighted (only in patients) and MT MRI scans were obtained at baseline and after 12 months. T2-hyperintense and T1-hypointense lesion volumes, normalized brain volume and average lesion MT ratio (MTR) were measured. MTR histograms from the whole brain tissue were also obtained. Clinical multiple sclerosis evolution and neurological disability were re-assessed in all patients after a median follow-up of 4.5 years. A multivariate analysis was performed to establish which clinical and MRI-derived variables were significant predictors of neurological deterioration at the end of the study period. At the end of follow-up, 34 patients showed significant neurological deterioration. The final multivariable model included average brain MTR percentage change after one year [P = 0.02, odds ratio (OR) = 0.86] and baseline T2-hyperintense lesion volume (P = 0.04, OR=1.04) as independent predictors of medium-term disability accumulation (r2 = 0.23). In this cohort of patients, abnormal values of average brain MTR changes showed a relatively high specificity (76.9%) and positive predictive value (59.1%) for Expanded Disability Status Scale score deterioration in individual cases. In patients with multiple sclerosis, a comprehensive estimation of the short-term changes of both conventional and MT MRI-detectable lesion burden might provide useful prognostic information for the medium-term clinical disease evolution.

Whole-brain N-acetylaspartate level and cognitive performance in HIV infection

BACKGROUND AND PURPOSE

In the brain of HIV-infected patients, proton MR spectroscopic studies are typically used to examine small volumes of tissue with single-voxel methods. Since brain disease is diffuse in patients with HIV, such studies preclude assessment of the true extent of the metabolic burden. To assess this extent, the relationship between global neuronal integrity, reflected by the whole-brain N-acetylaspartate (WBNAA) concentration, was correlated with neuropsychological function and the AIDS dementia complex (ADC) stage score.

METHODS

WBNAA levels were compared between 15 HIV-infected patients (seven symptomatic, eight asymptomatic) and 13 age- and sex-matched healthy subjects. The patients' WBNAA level was correlated with cognitive performance, as measured with a battery of eight tests (NPZ-8), including the ADC stage score and four total-memory, mood, motor, and processing speed subtests.

RESULTS

WBNAA levels were significantly different between patients and healthy subjects (mean +/- sigma, 11.82 +/- 1.40 and 12.91 +/- 1.03 mmol/L, respectively; P =.032) after we adjusted for age and sex effects. Intermediate negative correlations were found between the WBNAA level, the processing speed subtest score (r = -0.50, P =.03), and the ADC stage score (r = -0.44, P =.05).

CONCLUSION

The WBNAA concentration complements brain atrophy data with information about the quality of the remaining neuronal and axonal tissue in patients with HIV infection. In HIV-infected patients, its correlation with processing speed and the ADC score indicates that the latter reflects pathologic deficits, which are extensive throughout the brain.

Diffusely elevated cerebral choline and creatine in relapsing-remitting multiple sclerosis

It is well known that multiple sclerosis (MS) pathogenesis continues even during periods of clinical silence. To quantify the metabolic characteristics of this activity we compared the absolute levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the normal-appearing white matter (NAWM) between relapsing-remitting (RR) MS patients and controls. Metabolite concentrations were obtained with 3D proton MR spectroscopy at 1.5 T in a 480 cm(3) volume-of-interest (VOI), centered on the corpus callosum of 11 MS patients and 9 matched controls. Gray/white-matter/cerebral-spinal-fluid (CSF) volumes were obtained from MRI segmentation. Patients' average VOI tissue volume (V(T)), 410.8 +/- 24.0 cm(3), and metabolite levels, NAA = 6.33 +/- 0.70, Cr = 4.67 +/- 0.52, Cho = 1.40 +/- 0.17 mM, were different from the controls by -8%, -9%, +22% and +32%. The Cho level was the only single metric differentiating patients from controls at 100% specificity and >90% sensitivity. Diffusely elevated Cho and Cr probably reflect widespread microscopic inflammation, gliosis, or de- and remyelination in the NAWM. Both metabolites are potential prognostic indicators of current disease activity, preceding NAA decline and atrophy.

A diffusion tensor magnetic resonance imaging study of brain tissue from patients with migraine

OBJECTIVE

To measure in vivo, using diffusion tensor magnetic resonance imaging (DT-MRI) the extent of pathological damage of normal appearing brain tissue (NABT) from patients with migraine.

METHODS

Dual echo and DT-MRI scans of the brain were acquired from 34 patients with migraine and 17 sex and age matched healthy volunteers. Mean diffusivity (MD) and fractional anisotropy (FA) histograms of the NABT were obtained from all subjects and the histograms' peak heights and average NABT MD and FA measured. When present, average MD and FA values of T2 visible lesions were also measured.

RESULTS

In comparison with healthy volunteers, patients with migraine had lower MD histogram peak height (p=0.02) of the NABT. No differences were found in FA histogram derived metrics between migraine patients and healthy subjects. No difference was found for any MD and FA histogram derived metrics between migraine patients with and without brain MRI lesions, and between patients with and without aura.

CONCLUSIONS

This study shows that, although brain damage may extend beyond T2 weighted abnormalities in patients with migraine, the severity of these "occult" changes is mild compared with that found in other diseases associated with white matter abnormality.

The effect of interferon beta-1b on quantities derived from MT MRI in secondary progressive MS

BACKGROUND

Magnetization transfer (MT) MRI can provide in vivo markers reflecting the severity of irreversible, MS-related brain damage occurring within and outside T2-visible lesions.

OBJECTIVE

To assess the effect of interferon (IFN) beta-1b treatment on the accumulation of brain damage in patients with secondary progressive (SP) MS, measured using MT MRI.

METHODS

Eighty-two patients with SPMS from five centers participating in a European, multicenter, double-blind, placebo-controlled trial of IFNbeta-1b in SPMS underwent brain T2-weighted and MT MRI at baseline. Evaluable follow-up data were available for 75 patients at 12 months, 54 at 24 months, and 47 at 36 months. MT MRI scans were postprocessed and analyzed to obtain histograms of MT ratio (MTR) values from the whole brain. A region of interest-based analysis of MTR values from the normal-appearing white matter (NAWM) was also performed.

RESULTS

In both the treatment arms, there was a decrease of average brain MTR values from baseline to month 24 (mean change -4.9%) and month 36 (mean change -4.3%). These changes were significant for the placebo group at both timepoints and for the IFNbeta-1b group at month 24 only, with no significant treatment effect. A decrease of NAWM MTR was also observed, with no significant difference between the two treatment arms.

CONCLUSION

In this cohort of patients with secondary progressive MS, interferon beta-1b did not show an overall effect on the worsening of magnetization transfer MRI measures, when compared with placebo. The data show that change in magnetization transfer ratio is a promising tool for monitoring disease evolution in secondary progressive MS and that the information obtained from magnetization transfer MRI complements that obtained from MRI measures of lesion load and inflammation.

Quantification of brain damage in cerebrotendinous xanthomatosis with magnetization transfer MR imaging

BACKGROUND AND PURPOSE

Conventional MR imaging for quantification of brain damage in monitoring the evolution of cerebrotendinous xanthomatosis (CTX) has limitations. Magnetization transfer (MT) MR imaging is overcoming these limitations. Using MT MR imaging, we sought to quantify, in vivo, the extent of brain and cerebellar damage in patients with CTX, with the ulimate goal to investigate the magnitude of the correlation between MT MR imaging findings and clinical disability.

METHODS

Conventional and MT MR images of the brain were obtained in nine patients with CTX and in 10 sex- and age-matched healthy volunteers. MT ratio histograms were derived of the whole brain, brain normal-appearing white matter (NAWM), brain normal-appearing gray matter (NAGM), cerebellar NAWM, and cerebellar NAGM. Clinical disability was measured by using the Expanded Disability Status Scale (EDSS).

RESULTS

Average MT ratio and peak heights of the whole brain, brain NAWM, and brain NAGM histograms in patients with CTX were significantly lower than the corresponding quantities in the control subjects. All cerebellar NAGM MT ratio histogram-derived metrics and average MT ratio of the cerebellar NAWM histogram in patients with CTX were also significantly lower than the corresponding quantities in the control subjects. Strong correlations were found between the EDSS score and a composite whole-brain MT ratio histogram score (r = 0.77, P <.01) and a composite brain white matter MT ratio histogram score (r = 0.71, P <.03). A strong correlation was also found between the cerebellar functional system score and a composite cerebellar NAWM score (r = 0.72, P <.02).

CONCLUSION

The quantitative assessment of brain damage in patients with CTX with use of MT MR imaging can provide powerful measures of disease outcome.

A diffusion tensor MRI study of basal ganglia from patients with ADEM

Using diffusion tensor (DT) MRI and histogram analysis, we measured mean diffusivity ((-)D) of basal ganglia grey matter (GM) from eight patients with acute disseminated encephalomyelitis (ADEM), 10 patients with multiple sclerosis (MS), and 10 healthy controls. Patients with ADEM had higher average (-)D (p=0.02) and lower (-)D histogram peak height (p=0.008) of the basal ganglia GM than patients with MS. Microscopic tissue damage occurs in the basal ganglia of ADEM patients, but not in MS patients with a similar burden of MRI-visible brain lesions.

Growing Region Segmentation Software (GRES) for quantitative magnetic resonance imaging of multiple sclerosis: intra- and inter-observer agreement variability: a comparison with manual contouring method

Lesion area measurement in multiple sclerosis (MS) is one of the key points in evaluating the natural history and in monitoring the efficacy of treatments. This study was performed to check the intra- and inter-observer agreement variability of a locally developed Growing Region Segmentation Software (GRES), comparing them to those obtained using manual contouring (MC). From routine 1.5-T MRI study of clinically definite multiple sclerosis patients, 36 lesions seen on proton-density-weighted images (PDWI) and 36 enhancing lesion on Gd-DTPA-BMA-enhanced T1-weighted images (Gd-T1WI) were randomly chosen and were evaluated by three observers. The mean range of lesion size was 9.9-536.0 mm(2) on PDWI and 3.6-57.2 mm(2) on Gd-T1WI. The median intra- and inter-observer agreement were, respectively, 97.1 and 90.0% using GRES on PDWI, 81.0 and 70.0% using MC on PDWI, 88.8 and 80.0% using GRES on Gd-T1WI, and 85.8 and 70.0% using MC on Gd-T1WI. The intra- and inter-observer agreements were significantly greater for GRES compared with MC ( P<0.0001 and P=0.0023, respectively) for PDWI, while no difference was found between GRES an MC for Gd-T1WI. The intra-observer variability for GRES was significantly lower on both PDWI ( P=0.0001) and Gd-T1WI ( P=0.0067), whereas for MC the same result was found only for PDWI ( P=0.0147). These data indicate that GRES reduces both the intra- and the inter-observer variability in assessing the area of MS lesions on PDWI and may prove useful in multicentre studies.

Irreversible disability and tissue loss in multiple sclerosis: a conventional and magnetization transfer magnetic resonance imaging study of the optic nerves

OBJECTIVES

To assess, by magnetic resonance imaging, the volumes and magnetization transfer ratio (MTR) values of optic nerves (ONs) from patients with multiple sclerosis (MS) who had incomplete or no visual recovery after optic neuritis; and to compare these quantities with those derived from ONs from patients with MS who showed a marked clinical recovery after optic neuritis, ONs from healthy volunteers, and ONs from patients with Leber hereditary optic neuropathy (LHON).

METHODS

Conventional and magnetization transfer magnetic resonance images of the ONs were obtained from 30 patients with MS, 18 healthy volunteers, and 10 patients with LHON. The ON from patients with MS were classified as clinically unaffected (n = 18); clinically affected with recovery (n = 20; visual acuity > or =20/25 at least 6 months after optic neuritis); and clinically affected with incomplete or no recovery (n = 22; visual acuity <20/25 at least 6 months after optic neuritis). The ON volumes and MTR values were measured.

RESULTS

Volumes (P =.002) and MTR values (P<.001) of the ONs from patients with MS and incomplete or no recovery were both lower than those of the ONs from patients with MS and recovery, but not different from those of the ONs from patients with LHON. Volumes and MTR values of the affected ONs from patients with MS and recovery did not differ from those of clinically unaffected ONs, which were similar to those of healthy volunteers.

CONCLUSION

These findings suggest that, in patients with MS, neurodegeneration is associated with persistent functional deficits secondary to incomplete recovery from relapses.

Magnetization transfer and diffusion tensor MR imaging of acute disseminated encephalomyelitis

BACKGROUND AND PURPOSE

Patients with acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) have a similar pattern of abnormalities on conventional MR images. We used magnetization transfer and diffusion tensor MR imaging to quantify normal-appearing brain tissue and cervical cord disease in patients with ADEM and to compare findings with those in healthy volunteers and patients with MS.

METHODS

Brain dual-echo, T1-weighted magnetization transfer, and diffusion tensor images were obtained in eight patients with ADEM, in 10 patients with MS, and in 10 healthy volunteers. Fast short-tau inversion recovery, T1-weighted, and magnetization transfer cervical cord images were also obtained. We identified lesions on the images and quantified their volumes. We performed histogram analysis of the magnetization transfer ratio (MTR) and average mean histogram analysis of the diffusivity (D) in normal-appearing brain tissue and MTR in the cervical cord.

RESULTS

Histogram analysis of normal-appearing brain tissue in patients with MS showed significantly lower MTRs and peak positions and significantly higher D averages compared with those in patients with ADEM. Patients with MS had significantly lower MTRs and D peak heights and significantly higher average D compared with those in healthy volunteers. Between patients with ADEM and control subjects, normal-appearing brain tissue MTR and D histogram metrics did not differ significantly. Cervical cord MTRs did not differ between control subjects and patients with ADEM, whereas the average MTR and histogram peak position was significantly lower in patients with MS than in the other groups.

CONCLUSION

Outside the acute phase of disease and as opposed to what happens in MS, the normal-appearing brain tissue and cervical cord in patients with ADEM are spared in the pathologic process.

Segmenting brain white matter, gray matter and cerebro-spinal fluid using diffusion tensor-MRI derived indices

Based on its ability to provide quantitative information about tissue microstructure, diffusion tensor magnetic resonance imaging (DT-MRI) might be a valuable approach to improve the reliability of segmentation of the various brain tissues. In this study, a fully automated and easy-to-implement technique based on 2D histogram analysis of DT-MRI derived images was used to segment white and gray matter of the brain from 10 healthy subjects (aged = 27-56 years). The results obtained with this novel segmentation strategy were compared to those achieved by two experienced observers using an operator-dependent segmentation on the dual-echo scans. Visual inspection of the segmented tissues from a third senior observer disclosed that the automated technique worked properly on all images from all subjects and was more accurate than the human raters in defining thalamus white and gray matter portions as well as in tissue classification at the external brain edge. In addition, this segmentation technique resulted in an average gray/white matter ratio similar to that reported by post-mortem assessment. The application of the operator-dependent segmentation strategy was extremely time-consuming and the two observers achieved poorly reproducible results. Segmenting brain white and gray matter using information from DT-MRI proved to be an accurate approach with the potential for improving the understanding of the pathophysiology of many neurologic conditions.

Defective gp130-mediated signal transducer and activator of transcription (STAT) signaling results in degenerative joint disease, gastrointestinal ulceration, and failure of uterine implantation

The receptor subunit gp130 transduces multiple cell type-specific activities of the leukemia inhibitory factor (LIF)/interleukin (IL)-6 family of cytokines through the signal transducer and activator of transcription (STAT) and src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2/ras/Erk pathways. To define STAT-dependent physiological responses, we generated mice with a COOH-terminal gp130(DeltaSTAT) "knock-in" mutation which deleted all STAT-binding sites. gp130(DeltaSTAT) mice phenocopyed mice deficient for IL-6 (impaired humoral and mucosal immune and hepatic acute phase responses) and LIF (failure of blastocyst implantation). However, unlike mice with null mutations in any of the components in the gp130 signaling pathway, gp130(DeltaSTAT) mice also displayed gastrointestinal ulceration and a severe joint disease with features of chronic synovitis, cartilaginous metaplasia, and degradation of the articular cartilage. Mitogenic hyperresponsiveness of synovial cells to the LIF/IL-6 family of cyto-kines was caused by sustained gp130-mediated SHP-2/ras/Erk activation due to impaired STAT-mediated induction of suppressor of cytokine signaling (SOCS) proteins which normally limits gp130 signaling. Therefore, the joint pathology in gp130(DeltaSTAT) mice is likely to arise from the disturbance of the otherwise balanced activation of the SHP-2/ras/Erk and STAT signaling cascades emanating from gp130.

Magnetization transfer and diffusion tensor MR imaging of the optic radiations and calcarine cortex from patients with Leber's hereditary optic neuropathy

Optic nerve abnormalities are easily detectable in patients with Leber's hereditary optic neuropathy (LHON), using magnetic resonance imaging (MRI). However, the presence of structural changes in the optic radiations and calcarine cortex of these patients is still an unresolved issue. In this study, we obtained magnetization transfer (MT) and diffusion tensor (DT) MRI to investigate the integrity of these structures in patients with LHON. Dual echo, MT- and DT-MRI scans of the brain were obtained from 10 men with LHON and 10 healthy sex- and age-matched controls. After image co-registration, we obtained MT ratio (MTR), average diffusivity (D) and fractional anisotropy (FA) maps. MTR, D and FA values for the white matter of the optic radiations and MTR and D values for the calcarine cortex were obtained using a region of interest (ROI) analysis. No macroscopic abnormalities were detected in any of the scans from LHON patients and controls. No statistically significant differences of MTR, D or FA values were found for any of the regions studied in LHON patients and healthy controls. Our results suggest that, in patients with LHON, the optic radiations and the calcarine cortex are spared from structural damage, both at a macroscopic and a microscopic level.

Autologous hematopoietic stem cell transplantation suppresses Gd-enhanced MRI activity in MS

BACKGROUND

Autologous hematopoietic stem cell transplantation (ASCT) has been recently utilized with encouraging results in patients with poorly controlled MS.

OBJECTIVE

To determine in severe cases of MS the effect of ASCT on gadolinium (Gd)-enhanced MRI and to obtain information on clinical course and safety.

METHODS

In a cooperative study, 10 patients with rapidly evolving secondary progressive MS were transplanted, after BEAM conditioning regimen (carmustine, etoposide, cytosine-arabinoside, and melphalan), with unmanipulated autologous peripheral blood SC mobilized with high-dose cyclophosphamide (CY; 4 g/m2) and granulocyte-colony-stimulating factor. Triple-dose Gd-enhanced scans were performed monthly for a pretreatment period of 3 months and compared with serial monthly Gd-enhanced MRI for the following 6 months and then once every 3 months.

RESULTS

The median follow-up is now 15 months (range 4 to 30 months). The number of Gd-enhancing lesions decreased immediately after mobilization with CY and finally dropped to zero in all cases after the conditioning regimen. The number of new T2-weighted positive lesions paralleled data obtained for Gd-enhanced MRI. Clinically, patients improved slightly or remained stable.

CONCLUSION

These results demonstrate that the therapeutic sequence CY-BEAM-ASCT has the capacity to completely suppress MR-enhancing activity, an effect that is sustained with time. The final impact of this procedure on disease course remains to be established.

Overview of diffusion-weighted magnetic resonance studies in multiple sclerosis

Diffusion-weighted magnetic resonance imaging (DW-MRI) provides a unique form of MR contrast that enables the diffusional motion of water molecules to be quantitatively measured. As a consequence, DW-MRI provides information about the size, shape, integrity, and orientation of brain structures. Pathological processes able to alter tissue integrity by removing or modifying some of the structural barriers that normally restrict water molecular motion in biological tissues cause changes in water diffusion characteristics, which can be measured in-vivo using DW-MRI. Although DW-MRI has been shown to be of great clinical utility in the assessment of patients with cerebral ischemia, it is also increasingly being used to quantify in-vivo the extent and severity of multiple sclerosis (MS) pathology. The pathological elements of MS have the potential to alter the permeability or geometry of structural barriers to water molecular motion in the brain, optic nerve and spinal cord. The present review outlines the major contributions given by DW-MRI for the quantification of MS-related damage and for the understanding of MS pathophysiology.

Mean diffusivity and fractional anisotropy histograms of patients with multiple sclerosis

BACKGROUND AND PURPOSE

Compared with conventional T2-weighted MR imaging, diffusion tensor MR imaging provides quantitative indices with increased specificity to the most destructive aspects of multiple sclerosis. In this study, we obtained brain mean diffusivity (_D) and fractional anisotropy histograms of patients with multiple sclerosis to compare them with those of healthy volunteers and to investigate the correlation between diffusion tensor MR imaging histogram-derived measures and the level of disability and quantities derived from conventional MR imaging.

METHODS

Dual-echo and diffusion tensor MR images were obtained from 78 patients with relapsing-remitting, secondary progressive, or primary progressive multiple sclerosis and from 20 healthy control volunteers. After obtaining mean diffusivity (_D) and fractional anisotropy images and image coregistration, _D and fractional anisotropy histograms were created. From each histogram, the following measures were derived: the average _D and fractional anisotropy, the histogram peak heights, and the histogram peak locations.

RESULTS

All the _D and fractional anisotropy histogram-derived measures were different between patients and controls at a significance level of P <.001. No differences were found in any of the considered quantities among the three multiple sclerosis phenotypes. In patients with relapsing-remitting multiple sclerosis, disability was correlated with histogram average_D (r = 0.4, P =.01) and peak height (r = -0.4, P =.01). In patients with secondary progressive multiple sclerosis, disability was correlated with fractional anisotropy histogram peak position (r = -0.6, P =.01). Significant correlations were also found between T2 lesion load and various diffusion tensor MR quantities.

CONCLUSION

This study shows that brain _D and fractional anisotropy histograms are different for patients with multiple sclerosis compared with control volunteers. This study also shows that quantities derived from diffusion tensor MR imaging are correlated with disability in patients with relapsing-remitting multiple sclerosis and secondary progressive multiple sclerosis, suggesting that they might serve as additional measures of outcome when monitoring multiple sclerosis evolution in these patients.

Magnetic resonance imaging, magnetisation transfer imaging, and diffusion weighted imaging correlates of optic nerve, brain, and cervical cord damage in Leber's hereditary optic neuropathy

OBJECTIVES

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disease leading to bilateral loss of central vision and severe optic nerve atrophy. A subtype of LHON presents additional clinical and MRI aspects indistinguishable from those of multiple sclerosis (MS) (LHON-MS). In patients with LHON or LHON-MS, an assessment was made of (a) the severity of optic nerve damage, using MRI and magnetisation transfer imaging (MTI), and (b) the presence and extent of macroscopic and microscopic pathology in the brain and cervical cord, using MRI and MT ratio (MTR) and mean diffusivity (D) histogram analysis.

METHODS

Ten patients with LHON, four with LHON-MS, and 20 age and sex matched healthy controls were studied. For the optic nerve and the brain, dual-echo turbo spin echo (TSE), T1 weighted spin echo, and MT images were obtained. For the brain, fast fluid attenuated inversion recovery (fast FLAIR) and diffusion weighted images were also obtained. For the cervical cord, fast short tau inversion recovery (STIR) and MT images were obtained. The volume and the average MTR value of both the optic nerves were measured. MTR and histograms of the normal appearing brain tissue (NABT) and MTR histograms of the whole cervical cord tissue were created.

RESULTS

The mean values of optic nerve volumes and MTR were significantly lower in patients with LHON than in healthy controls. Mean NABT-MTR histogram peak height was significantly lower in patients with LHON than in controls, whereas no significant difference was found for any of the cervical cord MTR histogram derived measures. Average diffusivity (D) was higher in patients with LHON than in controls. Optic nerve volume and MTR value and mean NABT-MTR were lower in patients with LHON-MS than in those with LHON.

CONCLUSIONS

The severity of optic nerve pathology in LHON is measurable in vivo using MRI and MTI. MTR and histogram analysis suggests that microscopic brain damage occurs in LHON and that it is more severe in the MS-like form of the disease.

Scan-rescan variation of measures derived from brain magnetization transfer ratio histograms obtained in healthy volunteers by use of a semi-interleaved magnetization transfer sequence

SUMMARY

A novel semiinterleaved gradient-echo (GE) sequence for quantitative measurement of magnetization transfer ratio (MTR) is described. With this sequence, several lines of k-space are collected for the non-MT image then several lines are collected for the MT image, thus building up the entire k-space in distinct acquisition blocks, with a good trade-off between motion-induced misregistration and degree of MT effect. The scan-rescan coefficients of variation for several MTR histogram-derived measures from 10 healthy volunteers scanned serially with this semiinterleaved sequence proved to be lower than those achieved using a conventional GE sequence. This sequence may be useful in a clinical environment to measure MTR changes over time more reliably than when acquiring the non-MT and MT images sequentially, which inevitably are affected by patient motion.

Diffusion tensor magnetic resonance imaging in multiple sclerosis

OBJECTIVES

To quantify, using diffusion tensor imaging (DTI), the tissue damage in lesions and normal-appearing white matter (NAWM) from a large cohort of patients with MS and to investigate the magnitude of the correlation between DTI-derived metrics and clinical disability.

METHODS

Dual-echo and DTI scans were obtained from 78 patients with relapsing-remitting, secondary progressive, or primary progressive MS and from 20 normal control participants. Post-contrast T1-weighted images were also obtained from the patients. After creating mean diffusivity (D) and fractional anisotropy (FA) images and image coregistration, D and FA values were measured for 4846 lesions (3207 nonenhancing T1-isointense, 1511 nonenhancing T1-hypointense, and 128 enhancing), 497 NAWM areas from patients, and 160 white matter areas from the controls.

RESULTS

The average lesion D was higher and the average lesion FA was lower than the corresponding quantities of the NAWM (p < 0.001). The values of enhancing and nonenhancing lesions were not different, whereas enhancing lesions had lower FA (p < 0.001). T1-hypointense lesions had higher D and lower FA than T1-isointense lesions (p < 0.001). NAWM of patients had higher and lower FA than white matter of controls (p = 0.01). Significant correlations were found between T1 and T2 lesion volume and and FA of lesions and NAWM. In the overall patient sample, a moderate correlation was also found between lesion D and the Expanded Disability Status Scale score (r = 0.28, p = 0.01). However, the r value of this correlation was 0.48 in patients with secondary progressive MS, whose disability was also correlated with average lesion FA (r = -0.50).

CONCLUSIONS

The results of this study show that DTI is able to identify MS lesions with severe tissue damage and to detect changes in the NAWM. They also indicate that DTI-derived measures are correlated with clinical disability, especially in patients with secondary progressive MS, thus suggesting a role for DTI in monitoring advanced phases of the disease.