Evidence-based guidelines: MAGNIMS consensus guidelines on the use of MRI in multiple sclerosis--establishing disease prognosis and monitoring patients

The role of MRI in the assessment of multiple sclerosis (MS) goes far beyond the diagnostic process. MRI techniques can be used as regular monitoring to help stage patients with MS and measure disease progression. MRI can also be used to measure lesion burden, thus providing useful information for the prediction of long-term disability. With the introduction of a new generation of immunomodulatory and/or immunosuppressive drugs for the treatment of MS, MRI also makes an important contribution to the monitoring of treatment, and can be used to determine baseline tissue damage and detect subsequent repair. This use of MRI can help predict treatment response and assess the efficacy and safety of new therapies. In the second part of the MAGNIMS (Magnetic Resonance Imaging in MS) network's guidelines on the use of MRI in MS, we focus on the implementation of this technique in prognostic and monitoring tasks. We present recommendations on how and when to use MRI for disease monitoring, and discuss some promising MRI approaches that may be introduced into clinical practice in the near future.

Evidence-based guidelines: MAGNIMS consensus guidelines on the use of MRI in multiple sclerosis-clinical implementation in the diagnostic process

The clinical use of MRI in patients with multiple sclerosis (MS) has advanced markedly over the past few years. Technical improvements and continuously emerging data from clinical trials and observational studies have contributed to the enhanced performance of this tool for achieving a prompt diagnosis in patients with MS. The aim of this article is to provide guidelines for the implementation of MRI of the brain and spinal cord in the diagnosis of patients who are suspected of having MS. These guidelines are based on an extensive review of the recent literature, as well as on the personal experience of the members of the MAGNIMS (Magnetic Resonance Imaging in MS) network. We address the indications, timing, coverage, reporting and interpretation of MRI studies in patients with suspected MS. Our recommendations are intended to help radiologists and neurologists standardize and optimize the use of MRI in clinical practice for the diagnosis of MS.

Characteristics of lesional and extra-lesional cortical grey matter in relapsing–remitting and secondary progressive multiple sclerosis: A magnetisation transfer and diffusion tensor imaging study

Background:

In multiple sclerosis (MS), diffusion tensor and magnetisation transfer imaging are both abnormal in lesional and extra-lesional cortical grey matter, but differences between clinical subtypes and associations with clinical outcomes have only been partly assessed.

Objective:

To compare mean diffusivity, fractional anisotropy and magnetisation transfer ratio (MTR) in cortical grey matter lesions (detected using phase-sensitive inversion recovery (PSIR) imaging) and extra-lesional cortical grey matter, and assess associations with disability in relapse-onset MS.

Methods:

Seventy-two people with MS (46 relapsing–remitting (RR), 26 secondary progressive (SP)) and 36 healthy controls were included in this study. MTR, mean diffusivity and fractional anisotropy were measured in lesional and extra-lesional cortical grey matter.

Results:

Mean fractional anisotropy was higher and MTR lower in lesional compared with extra-lesional cortical grey matter. In extra-lesional cortical grey matter mean fractional anisotropy and MTR were lower, and mean diffusivity was higher in the MS group compared with controls. Mean MTR was lower and mean diffusivity was higher in lesional and extra-lesional cortical grey matter in SPMS when compared with RRMS. These differences were independent of disease duration. In multivariate analyses, MTR in extra-lesional more so than lesional cortical grey matter was associated with disability.

Conclusion:

Magnetic resonance abnormalities in lesional and extra-lesional cortical grey matter are greater in SPMS than RRMS. Changes in extra-lesional compared with lesional cortical grey matter are more consistently associated with disability.

Extra-ocular muscle MRI in genetically-defined mitochondrial disease

Objectives

Conventional and quantitative MRI was performed in patients with chronic progressive external ophthalmoplegia (CPEO), a common manifestation of mitochondrial disease, to characterise MRI findings in the extra-ocular muscles (EOMs) and investigate whether quantitative MRI provides clinically relevant measures of disease.

Methods

Patients with CPEO due to single mitochondrial DNA deletions were compared with controls. Range of eye movement (ROEM) measurements, peri-orbital 3 T MRI T1-weighted (T1w) and short-tau-inversion-recovery (STIR) images, and T2 relaxation time maps were obtained. Blinded observers graded muscle atrophy and T1w/STIR hyperintensity. Cross-sectional areas and EOM mean T2s were recorded and correlated with clinical parameters.

Results

Nine patients and nine healthy controls were examined. Patients had reduced ROEM (patients 13.3°, controls 49.3°, p < 0.001), greater mean atrophy score and increased T1w hyperintensities. EOM mean cross-sectional area was 43 % of controls and mean T2s were prolonged (patients 75.6 ± 7.0 ms, controls 55.2 ± 4.1 ms, p < 0.001). ROEM correlated negatively with EOM T2 (rho = −0.89, p < 0.01), whilst cross-sectional area failed to correlate with any clinical measures.

Conclusions

MRI demonstrates EOM atrophy, characteristic signal changes and prolonged T2 in CPEO. Correlation between elevated EOM T2 and ROEM impairment represents a potential measure of disease severity that warrants further evaluation.

Key Points

• Chronic progressive external ophthalmoplegia is a common clinical manifestation of mitochondrial disease.

• Existing extra-ocular muscle MRI data in CPEO reports variable radiological findings.

• MRI confirmed EOM atrophy and characteristic signal changes in CPEO.

• EOM T2 was significantly elevated in CPEO and correlated negatively with ocular movements.

• EOM T2 represents a potential quantitative measure of disease severity in CPEO.

Effects of delayed-release dimethyl fumarate on MRI measures in the phase 3 CONFIRM study

OBJECTIVE

To evaluate the effects of oral delayed-release dimethyl fumarate (DMF; also known as gastro-resistant DMF) on MRI lesion activity and load, atrophy, and magnetization transfer ratio (MTR) measures from the Comparator and an Oral Fumarate in Relapsing-Remitting Multiple Sclerosis (CONFIRM) study.

METHODS

CONFIRM was a 2-year, placebo-controlled study of the efficacy and safety of DMF 240 mg twice (BID) or 3 times daily (TID) in 1,417 patients with relapsing-remitting multiple sclerosis (RRMS); subcutaneous glatiramer acetate 20 mg once daily was included as an active reference comparator. The number and volume of T2-hyperintense, T1-hypointense, and gadolinium-enhancing (Gd+) lesions, as well as whole brain volume and MTR, were assessed in 681 patients (MRI cohort).

RESULTS

DMF BID and TID produced significant and consistent reductions vs placebo in the number of new or enlarging T2-hyperintense lesions and new nonenhancing T1-hypointense lesions after 1 and 2 years of treatment and in the number of Gd+ lesions at week 24, year 1, and year 2. Lesion volumes were also significantly reduced. Reductions in brain atrophy and MTR changes with DMF relative to placebo did not reach statistical significance.

CONCLUSIONS

The robust effects on MRI active lesion counts and total lesion volume in patients with RRMS demonstrate the ability of DMF to exert beneficial effects on inflammatory lesion activity in multiple sclerosis, and support DMF therapy as a valuable new treatment option in RRMS.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence of reduction in brain lesion number and volume, as assessed by MRI, over 2 years of delayed-release DMF treatment.

Preventing visual field deficits from neurosurgery

OBJECTIVE

We assessed whether display of optic radiation tractography during anterior temporal lobe resection (ATLR) for refractory temporal lobe epilepsy (TLE) can reduce the severity of postoperative visual field deficits (VFD) and increase the proportion of patients who can drive and whether correction for brain shift using intraoperative MRI (iMRI) is beneficial.

METHODS

A cohort of 21 patients underwent ATLR in an iMRI suite. Preoperative tractography of the optic radiation was displayed on the navigation and operating microscope displays either without (9 patients) or with (12 patients) correction for brain shift. VFD were quantified using Goldmann perimetry and eligibility to drive was assessed by binocular Esterman perimetry 3 months after surgery. Secondary outcomes included seizure freedom and extent of hippocampal resection. The comparator was a cohort of 44 patients who underwent ATLR without iMRI.

RESULTS

The VFD in the contralateral superior quadrant were significantly less (p = 0.043) with iMRI guidance (0%-49.2%, median 14.5%) than without (0%-90.9%, median 24.0%). No patient in the iMRI cohort developed a VFD that precluded driving whereas 13% of the non-iMRI cohort failed to meet UK driving criteria. Outcome did not differ between iMRI guidance with and without brain shift correction. Seizure outcome and degree of hippocampal resection were unchanged.

CONCLUSIONS

Display of the optic radiation with image guidance reduces the severity of VFD and did not affect seizure outcome or hippocampal resection. Correction for brain shift is possible but did not further improve outcome. Future work to incorporate tractography into conventional neuronavigation systems will make the work more widely applicable.

Reproducibility, and age, body-weight and gender dependency of candidate skeletal muscle MRI outcome measures in healthy volunteers

Objectives

Quantitative magnetic resonance imaging (MRI) can potentially meet the pressing need for objective, sensitive, reproducible outcome measures in neuromuscular disease trials. We tested, in healthy volunteers, the consistency, reliability and sensitivity to normal inter-subject variation of MRI methods targeted to lower limb muscle pathology to inform the design of practical but comprehensive MRI outcome measure protocols for use in imminent patient studies.

Methods

Forty-seven healthy volunteers, age 21-81 years, were subject at 3T to three-point Dixon fat-fraction measurement, T₁-relaxometry, T₂-relaxometry and magnetisation transfer ratio (MTR) imaging at mid-thigh and mid-calf level bilaterally. Fifteen subjects underwent repeat imaging at 2 weeks.

Results

Mean between-muscle fat fraction and T₂ differences were small, but significant (p < 0.001). Fat fraction and T₂ correlated positively, and MTR negatively with subject age in both the thigh and calf, with similar significant correlations with weight at thigh level only (p < 0.001 to p < 0.05). Scan-rescan and inter-observer intra-class correlation coefficients ranged between 0.62-0.84 and 0.79-0.99 respectively.

Conclusions

Quantitative lower-limb muscle MRI using readily implementable methods was sensitive enough to demonstrate inter-muscle differences (small in health), and correlations with subject age and weight. In combination with high reliability, this strongly supports the suitability of these methods to provide longitudinal outcome measures in neuromuscular disease treatment trials.

Key points

• Quantitative lower limb muscle MRI provides potential outcome measures in neuromuscular diseases

• Bilateral thigh/calf coverage using sequences sensitive to acute and chronic pathology

• Measurements have excellent scan-rescan and interobserver reliability

• Measurements show small but significant inter-subject age and weight dependency

• Readily implementable sequences suitable for further assessment in patient studies

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-014-3145-6) contains supplementary material, which is available to authorized users.

Automated identification of brain tumors from single MR images based on segmentation with refined patient-specific priors

Brain tumors can have different shapes or locations, making their identification very challenging. In functional MRI, it is not unusual that patients have only one anatomical image due to time and financial constraints. Here, we provide a modified automatic lesion identification (ALI) procedure which enables brain tumor identification from single MR images. Our method rests on (A) a modified segmentation-normalization procedure with an explicit “extra prior” for the tumor and (B) an outlier detection procedure for abnormal voxel (i.e., tumor) classification. To minimize tissue misclassification, the segmentation-normalization procedure requires prior information of the tumor location and extent. We therefore propose that ALI is run iteratively so that the output of Step B is used as a patient-specific prior in Step A. We test this procedure on real T1-weighted images from 18 patients, and the results were validated in comparison to two independent observers' manual tracings. The automated procedure identified the tumors successfully with an excellent agreement with the manual segmentation (area under the ROC curve = 0.97 ± 0.03). The proposed procedure increases the flexibility and robustness of the ALI tool and will be particularly useful for lesion-behavior mapping studies, or when lesion identification and/or spatial normalization are problematic.

Multiparameter MR imaging in the 6-OPRI variant of inherited prion disease

BACKGROUND AND PURPOSE

Inherited prion diseases represent over 15% of human prion cases and are a frequent cause of early onset dementia. The purpose of this study was to define the distribution of changes in cerebral volumetric and microstructural parenchymal tissues in a specific inherited human prion disease mutation combining VBM with VBA of cerebral MTR and MD.

MATERIALS AND METHODS

VBM and VBA of cerebral MTR and MD were performed in 16 healthy control participants and 9 patients with the 6-OPRI mutation. An analysis of covariance consisting of diagnostic grouping with age and total intracranial volume as covariates was performed.

RESULTS

On VBM, there was a significant reduction in gray matter volume in patients compared with control participants in the basal ganglia, perisylvian cortex, lingual gyrus, and precuneus. Significant MTR reduction and MD increases were more anatomically extensive than volume differences on VBM in the same cortical areas, but MTR and MD changes were not seen in the basal ganglia.

CONCLUSIONS

Gray matter and WM changes were seen in brain areas associated with motor and cognitive functions known to be impaired in patients with the 6-OPRI mutation. There were some differences in the anatomic distribution of MTR-VBA and MD-VBA changes compared with VBM, likely to reflect regional variations in the type and degree of the respective pathophysiologic substrates. Combined analysis of complementary multiparameter MR imaging data furthers our understanding of prion disease pathophysiology.

Muscle MRI reveals distinct abnormalities in genetically proven non-dystrophic myotonias

We assessed the presence, frequency and pattern of MRI abnormalities in non-dystrophic myotonia patients. We reviewed T1-weighted and STIR (short-tau-inversion-recovery) 3T MRI sequences of lower limb muscles at thigh and calf level in 21 patients with genetically confirmed non-dystrophic myotonia: 11 with CLCN1 mutations and 10 with SCN4A mutations, and 19 healthy volunteers. The MRI examinations of all patients showed hyperintensity within muscles on either T1-weighted or STIR images. Mild extensive or marked T1-weighted changes were noted in 10/21 patients and no volunteers. Muscles in the thigh were equally likely to be affected but in the calf there was sparing of tibialis posterior. Oedema was common in calf musculature especially in the medial gastrocnemius with STIR hyperintensity observed in 18/21 patients. In 10/11 CLCN1 patients this included a previously unreported “central stripe”, also present in 3/10 SCN4A patients but no volunteers. Degree of fatty infiltration correlated with age (rho = 0.46, p < 0.05). Muscle MRI is frequently abnormal in non-dystrophic myotonia providing evidence of fatty infiltration and/or oedema. The pattern is distinct from other myotonic disorders; in particular the “central stripe” has not been reported in other conditions. Correlations with clinical parameters suggest a potential role for MRI as a biomarker.

Strictly lobar microbleeds are associated with executive impairment in patients with ischemic stroke or transient ischemic attack

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) are a marker of small vessel diseases, including hypertensive arteriopathy and cerebral amyloid angiopathy, and may be associated with cognitive impairment. The relationship between CMBs and cognitive function in ischemic cerebrovascular disease remains uncertain. We, therefore, investigated the cognitive impact of CMBs in a cohort of patients with ischemic stroke or transient ischemic attack.

METHODS

All patients underwent detailed and comprehensive neuropsychological testing and standardized MRI, including fluid attenuation inversion recovery, T1, T2, and gradient-recalled echo T2*-weighted sequences. CMBs, white matter changes, lacunes, and territorial cortical infarcts (defined by standardized criteria) were identified, and associations with cognition assessed.

RESULTS

Three hundred twenty patients with a diagnosis of ischemic stroke or transient ischemic attack were included. Of these, 72 (22.5%) had at least 1 CMB. Of all the cognitive domains tested, only executive impairment was more prevalent in patients with CMBs than without (38% versus 25%; P=0.039). In univariate analysis, the presence of strictly lobar (but not deep) CMBs was associated with executive impairment (odds ratio, 2.49; 95% confidence interval, 1.16-5.36; P=0.019). In adjusted multivariate analyses, the presence (OR, 2.34; 95% confidence interval, 1.08-5.09; P=0.031) and number (OR, 1.33; 95% confidence interval, 1.04-1.69; P=0.022) of strictly lobar CMBs were significantly associated with executive impairment. CMBs were not associated with impairment in other cognitive domains.

CONCLUSIONS

Strictly lobar CMBs are independently associated with executive dysfunction in patients with ischemic stroke or transient ischemic attack. Our findings suggest that a microangiopathy related to strictly lobar CMBs (eg, cerebral amyloid angiopathy) contributes to cognitive impairment in this population.

Magnetic resonance imaging pattern in natalizumab-associated progressive multifocal leukoencephalopathy

OBJECTIVE

Natalizumab is an effective treatment for patients with multiple sclerosis (MS) that is associated with a risk of progressive multifocal leukoencephalopathy (PML). Recommendations were published in 2006 to improve early diagnosis of PML using magnetic resonance imaging (MRI). However, due to the small number of MS patients initially diagnosed with PML, the imaging criteria could only be derived from PML lesions in patients with human immunodeficiency virus. Therefore, there is an urgent need to assess the MRI characteristics of PML in MS patients to update the existing recommendations.

METHODS

In this retrospective review, the first 40 natalizumab-treated MS patients diagnosed with PML in the postmarketing setting were identified, of whom 22 (10 with clinically diagnosed immune reconstitution inflammatory syndrome) fulfilled the inclusion criteria for this study. Magnetic resonance images were analyzed according to predefined criteria by 5 independent readers.

RESULTS

The most frequent lesion pattern in early scans from PML patients was that of large (>3 cm, 15 of 18), subcortical (18 of 18), T2 or fluid-attenuated inversion recovery hyperintense (18 of 18), T1-hypointense (17 of 18), and diffusion-hyperintense (15 of 15) lesions, with a sharp border toward the gray matter and an ill-defined border toward the white matter (18 of 18) on T2-weighted images. We could detect contrast enhancement in 41% (7 of 17) of the cases on the first scan at clinical presentation.

INTERPRETATION

Attention to characteristic MRI patterns, especially the presence of contrast enhancement, and the subcortical location may have utility in screening and early diagnosis of PML in natalizumab-treated MS patients.

Improved detection of cortical MS lesions with phase-sensitive inversion recovery MRI

OBJECTIVE

Cortical grey matter lesions are common in multiple sclerosis (MS), but usually not seen on MRI. The authors compared the performance of double inversion recovery (DIR, currently considered the best available imaging sequence for detecting cortical lesions) with phase-sensitive inversion recovery (PSIR, a sequence allowing much higher resolution scans to be obtained in a clinically feasible time).

METHODS

Sixty MS patients and 30 healthy controls underwent MRI scanning on a 3 Tesla scanner. The authors compared intracortical (IC) and leucocortical (LC) lesion counts obtained with a standard DIR sequence (1×1×3 mm resolution, obtained in 4 min) and a PSIR sequence (0.5×0.5×2 mm, 11 min). Lesions were marked separately on DIR and PSIR scans.

RESULTS

In the whole MS cohort, more cortical lesions were seen on the higher-resolution PSIR than the DIR scans (IC mean±SD: 18.1±9.8 vs 5.9±4.5, p<0.001; LC mean±SD: 13.4±12.9 vs 7.3±8.0, p<0.001). On PSIR, ≥1 IC lesion was seen in 60/60 MS patients and 1/30 controls, and ≥1 LC lesion in 60/60 patients and 6/30 controls. On DIR, ≥1 IC lesion was seen in 50/60 patients and 0/30 controls, and ≥1 LC lesion(s) in 60/60 patients and 5/30 controls.

CONCLUSIONS

Compared with DIR, using PSIR the authors are able to detect a significantly greater number of cortical grey matter lesions. The presence of at least one IC lesion in every MS patient, but very few healthy controls, suggests that it may be a useful adjunct to conventional MRI when a diagnosis of MS is suspected but not confirmed.

Correcting radiofrequency inhomogeneity effects in skeletal muscle magnetisation transfer maps

The potential of MRI to provide quantitative measures of neuromuscular pathology for use in therapeutic trials is being increasingly recognised. Magnetisation transfer (MT) imaging shows particular promise in this context, being sensitive to pathological changes, particularly in skeletal muscle, where measurements correlate with clinically measured muscle strength. Radiofrequency (RF) transmit field (B(1)) inhomogeneities can be particularly problematic in measurements of the MT ratio (MTR) and may obscure genuine muscle MTR changes caused by disease. In this work, we evaluate, for muscle imaging applications, a scheme previously proposed for the correction of RF inhomogeneity artefacts in cerebral MTR maps using B(1) information acquired in the same session. We demonstrate the theoretical applicability of this scheme to skeletal muscle using a two-pool model of pulsed quantitative MT. The correction scheme is evaluated practically in MTR imaging of the lower limbs of 28 healthy individuals and in two groups of patients with representative neuromuscular diseases: Charcot-Marie-Tooth disease type 1A and inclusion body myositis. The correction scheme was observed to reduce both the within-subject and between-subject variability in the calf and thigh muscles of healthy subjects and patient groups in histogram- and region-of-interest-based approaches. This method of correcting for RF inhomogeneity effects in MTR maps using B(1) data may markedly improve the sensitivity of MTR mapping indices as measures of pathology in skeletal muscle.

Skeletal muscle MRI magnetisation transfer ratio reflects clinical severity in peripheral neuropathies

MRI may provide treatment outcome measures in neuromuscular conditions. The authors assessed MRI magnetisation transfer ratios (MTRs) in lower-limb musculature as markers of pathology in peripheral neuropathies and compared the findings with associated clinical data. Ten patients with Charcot-Marie-Tooth disease type 1A (CMT1A) and nine patients with chronic inflammatory demyelinating polyneuropathy (CIDP) were compared with 10 healthy subjects. The MTR in the calf muscles was significantly lower than controls in the two patient groups (both p<0.001). The median MTRs (IQR) were 50.5(1.6) percentage units (p.u.) (control), 41.5(10.6) p.u. (CMT1A) and 39.3(8.7) p.u. (CIDP). Moreover, anterior lower leg MTR correlated strongly with strength of ankle dorsiflexion, measured with the Medical Research Council scale, in CIDP (ρ=0.88, p<0.001) and also in CMT1A (ρ=0.50, p<0.05), where MTR also showed an association with disease duration (ρ=-0.86, p<0.001). Short tau inversion recovery MRI of the same muscles showed abnormalities associated with regions of reduced MTR (p<0.001), and MTR was also reduced in other muscles otherwise deemed normal appearing (p<0.001), indicating that MTR may be more sensitive to muscle damaged by denervation than conventional MRI. The significant reductions in muscle MTR in peripheral neuropathies and the associated correlations with clinical measures indicate that MTR has potential as an imaging outcome measure in future therapeutic trials.

MRI shows increased sciatic nerve cross sectional area in inherited and inflammatory neuropathies

Measurements of the cross sectional area of the sciatic nerve are described in a group of 10 patients with genetically confirmed Charcot-Marie-Tooth disease type 1A (CMT1A), nine patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and 10 healthy controls using MRI. One mid-thigh of each individual was imaged using a short tau inversion recovery sequence and the nerve appearance evaluated radiologically with respect to the signal intensity and visibility of the internal neural structure. The cross sectional area of the sciatic nerve of each individual was measured by defining irregular enclosing regions of interest on the MRI images. The sciatic nerve area was enlarged in both CMT1A (p<0.001) and CIDP (p=0.008) compared with controls and in CMT1A compared with CIDP (p<0.001). Median (interquartile range) areas were 67.6 (16.2) mm(2) for the CIDP group, 135.9 (46.5) mm(2) for the CMT1A group and 43.3 (19.9) mm(2) for the control group. The critical upper value for discriminating pathologically enlarged nerves from normal controls with p<0.05 was 64.4 mm(2). Quantification of sciatic nerve hypertrophy on MRI may be of assistance in cases where the diagnosis is still in doubt, providing an objective pathological marker complimenting other clinical investigations.

High resolution MR anatomy of the subthalamic nucleus: imaging at 9.4 T with histological validation

Using conventional MRI the subthalamic nucleus (STN) is not clearly defined. Our objective was to define the anatomy of the STN using 9.4 T MRI of post mortem tissue with histological validation. Spin-echo (SE) and 3D gradient-echo (GE) images were obtained at 9.4 T in 8 post mortem tissue blocks and compared directly with corresponding histological slides prepared with Luxol Fast Blue/Cresyl Violet (LFB/CV) in 4 cases and Perl stain in 3. The variability of the STN anatomy was studied using internal reference points. The anatomy of the STN and surrounding structures was demonstrated in all three anatomical planes using 9.4 T MR images in concordance with LFB/CV stained histological sections. Signal hypointensity was seen in 6/8 cases in the anterior and medial STN that corresponded with regions of more intense Perl staining. There was significant variability in the volume, shape and location of the borders of the STN. Using 9.4 T MRI, the internal signal characteristics and borders of the STN are clearly defined and significant anatomical variability is apparent. Direct visualisation of the STN is possible using high field MRI and this is particularly relevant, given its anatomical variability, for planning deep brain stimulation.

Diffusion tensor imaging tractography of the optic radiation for epilepsy surgical planning: a comparison of two methods

The optic radiation is a key white matter structure at risk during epilepsy surgery involving the temporal, parietal or occipital lobes. It shows considerable anatomical variability, cannot be delineated on clinical MRI sequences and damage may cause a disabling visual field deficit. Diffusion tensor imaging tractography allows non-invasive mapping of this pathway. Numerous methods have been published but direct comparison is difficult as patient, acquisition and analysis parameters differ.

Two methods for delineating the optic radiation were applied to 6 healthy controls and 4 patients with epileptogenic lesions near the optic radiation. By comparing methods with the same datasets, many of the parameters could be controlled. The first method was previously developed to accurately identify Meyer's loop for planning anterior temporal lobe resection. The second aimed to address limitations of this method by using a more automated technique to reduce operator time and to depict the entire optic radiation.

Whilst the core of the tract was common to both methods, there was significant variability between the methods. Method 1 gave a more consistent depiction of Meyer's loop with fewer spurious tracts. Method 2 gave a better depiction of the entire optic radiation, particularly in more posterior portions, but did not identify Meyer's loop in one patient.

These results show that whilst tractography is a promising technique, there is significant variability depending on the method chosen even when the majority of parameters are fixed. Different methods may need to be chosen for surgical planning depending on the individual clinical situation.

Effect of BG-12 on contrast-enhanced lesions in patients with relapsing--remitting multiple sclerosis: subgroup analyses from the phase 2b study

BACKGROUND

In a phase 2b study in patients with relapsing-remitting MS (RRMS), BG-12 240 mg three times daily significantly reduced the number of new gadolinium-enhanced (Gd+) lesions from weeks 12 to 24 (primary end point) by 69% compared with placebo.

OBJECTIVE

In this analysis, the effect of BG-12 240 mg three times daily on the number of Gd+ lesions from weeks 12 to 24 was evaluated in subgroups based on baseline disease characteristics and demographics.

METHODS

Two hundred and fifty-seven patients were randomized equally to receive BG-12 (120 mg once daily or three times daily or 240 mg three times daily) or placebo.

RESULTS

BG-12 240 mg three times daily significantly reduced the number of new Gd+ lesions compared with placebo in the following subgroups: Expanded Disability Status Scale (EDSS) score ≤ 2.5 (74%), EDSS score > 2.5 (63%), no Gd+ lesions (80%), ≥ 1 Gd+ lesion (55%), age < 40 years (49%), age ≥ 40 years (89%), female patients (81%), disease duration ≤ 6 years (81%) and disease duration > 6 years (54%) (all comparisons p < 0.05).

CONCLUSION

BG-12 demonstrated efficacy in patients with RRMS by decreasing new Gd+ lesion development across a range of subgroups defined by baseline disease characteristics or demographics.

Functional magnetic resonance imaging exploration of combined hand and speech movements in Parkinson's disease

Among the repertoire of motor functions, although hand movement and speech production tasks have been investigated widely by functional neuroimaging, paradigms combining both movements have been studied less so. Such paradigms are of particular interest in Parkinson's disease, in which patients have specific difficulties performing two movements simultaneously. In 9 unmedicated patients with Parkinson's disease and 15 healthy control subjects, externally cued tasks (i.e., hand movement, speech production, and combined hand movement and speech production) were performed twice in a random order and functional magnetic resonance imaging detected cerebral activations, compared to the rest. F-statistics tested within-group (significant activations at P values < 0.05, familywise error corrected), between-group, and between-task comparisons (regional activations significant at P values < 0.001, uncorrected, with cluster size > 10 voxels). For control subjects, the combined task activations comprised the sum of those obtained during hand movement and speech production performed separately, reflecting the neural correlates of performing movements sharing similar programming modalities. In patients with Parkinson's disease, only activations underlying hand movement were observed during the combined task. We interpreted this phenomenon as patients' potential inability to recruit facilitatory activations while performing two movements simultaneously. This lost capacity could be related to a functional prioritization of one movement (i.e., hand movement), in comparison with the other (i.e., speech production). Our observation could also reflect the inability of patients with Parkinson's disease to intrinsically engage the motor coordination necessary to perform a combined task.