Conventional MR Imaging

Diagnostic value of 3D-FLAIR magnetic resonance sequence in detection of white matter brain lesions in multiple sclerosis

Background

MS is common demyelinating disease in which standard T2 and 2D-FLAIR MRI sequences play important role in its diagnosis. Recently, 3D-FLAIR sequence is used and has a role that is evaluated compared to standard sequences.

Results

This study was performed on 20 selected MS patients. Brain MRI was performed using routinely used T2 and 2D FLAIR sequences, and 3D-FLAIR sequence was added. 3D-FLAIR images were reformatted, and all images were blindly analyzed. Lesions were counted in each sequence and classified according to their location into supratentorial lesions including periventricular, deep white matter, and juxta-cortical, and infratentorial lesions and relative comparison of lesion number on 3D-FLAIR versus 2D-FLAIR and T2 imaging, respectively, were expressed as percentage gain or a loss.

3D-FLAIR sequence showed significantly more lesions compared to 2D FLAIR and T2 sequences in all locations with relative ratio of 29% and 41%, respectively, in periventricular region; 22% and 30%, respectively, in deep WM; 180% and 147%, respectively, in juxta-cortical region; and 80% and 13%, respectively, in infratentorial region.

Conclusion

3D-FLAIR sequence is of greater sensitivity than standard 2D-FLAIR and T2 sequences in MS brain lesions depiction, and it is recommended to be included in MR protocol of MS.

Three-dimensional MRI sequences in MS diagnosis and research

The most recent guidelines for magnetic resonance imaging (MRI) in multiple sclerosis (MS) recommend three-dimensional (3D) MRI sequences over their two-dimensional (2D) counterparts. This development has been made possible by advances in MRI scanner hardware and software. In this article, we review the 3D versions of conventional sequences, including T1-weighted, T2-weighted and fluid-attenuated inversion recovery (FLAIR), as well as more advanced scans, including double inversion recovery (DIR), FLAIR2, FLAIR*, phase-sensitive inversion recovery, and susceptibility weighted imaging (SWI).

FLAIR2: A Combination of FLAIR and T2 for Improved MS Lesion Detection

BACKGROUND AND PURPOSE

FLAIR and double inversion recovery are important MR imaging scans for MS. The suppression of signal from CSF in FLAIR and the additional suppression of WM signal in double inversion recovery improve contrast between lesions, WM and GM, albeit at a reduced SNR. However, whether the acquisition of double inversion recovery is necessary is still debated. Here, we present an approach that allows obtaining CSF-suppressed images with improved contrast between lesions, WM and GM without strongly penalizing SNR.

MATERIALS AND METHODS

3D T2-weighted and 3D-FLAIR data acquired from September 2014 to April 2015 in healthy volunteers (23.4 ± 2.4 years of age; female/male ratio, 3:2) and patients (44.1 ± 14.0 years of age; female/male ratio, 4:5) with MS were coregistered and multiplied (FLAIR(2)). SNR and contrast-to-noise measurements were performed for focal lesions and GM and WM. Furthermore, data from 24 subjects with relapsing-remitting and progressive MS were analyzed retrospectively (52.7 ± 8.1 years of age; female/male ratio, 14:10).

RESULTS

The GM-WM contrast-to-noise ratio was by 133% higher in FLAIR(2) than in FLAIR and improved between lesions and WM by 31%, 93%, and 158% compared with T2, DIR, and FLAIR, respectively. Cortical and juxtacortical lesions were more conspicuous in FLAIR(2). Furthermore, the 3D nature of FLAIR(2) allowed reliable visualization of callosal and infratentorial lesions.

CONCLUSIONS

We present a simple approach for obtaining CSF suppression with an improved contrast-to-noise ratio compared with conventional FLAIR and double inversion recovery without the acquisition of additional data. FLAIR(2) can be computed retrospectively if T2 and FLAIR scans are available.

Revised Recommendations of the Consortium of MS Centers Task Force for a Standardized MRI Protocol and Clinical Guidelines for the Diagnosis and Follow-Up of Multiple Sclerosis

An international group of neurologists and radiologists developed revised guidelines for standardized brain and spinal cord MR imaging for the diagnosis and follow-up of MS. A brain MR imaging with gadolinium is recommended for the diagnosis of MS. A spinal cord MR imaging is recommended if the brain MR imaging is nondiagnostic or if the presenting symptoms are at the level of the spinal cord. A follow-up brain MR imaging with gadolinium is recommended to demonstrate dissemination in time and ongoing clinically silent disease activity while on treatment, to evaluate unexpected clinical worsening, to re-assess the original diagnosis, and as a new baseline before starting or modifying therapy. A routine brain MR imaging should be considered every 6 months to 2 years for all patients with relapsing MS. The brain MR imaging protocol includes 3D T1-weighted, 3D T2-FLAIR, 3D T2-weighted, post-single-dose gadolinium-enhanced T1-weighted sequences, and a DWI sequence. The progressive multifocal leukoencephalopathy surveillance protocol includes FLAIR and DWI sequences only. The spinal cord MR imaging protocol includes sagittal T1-weighted and proton attenuation, STIR or phase-sensitive inversion recovery, axial T2- or T2*-weighted imaging through suspicious lesions, and, in some cases, postcontrast gadolinium-enhanced T1-weighted imaging. The clinical question being addressed should be provided in the requisition for the MR imaging. The radiology report should be descriptive, with results referenced to previous studies. MR imaging studies should be permanently retained and available. The current revision incorporates new clinical information and imaging techniques that have become more available.

Canadian Expert Panel Recommendations for MRI Use in MS Diagnosis and Monitoring

BACKGROUND

A definitive diagnosis of multiple sclerosis (MS), as distinct from a clinically isolated syndrome, requires one of two conditions: a second clinical attack or particular magnetic resonance imaging (MRI) findings as defined by the McDonald criteria. MRI is also important after a diagnosis is made as a means of monitoring subclinical disease activity. While a standardized protocol for diagnostic and follow-up MRI has been developed by the Consortium of Multiple Sclerosis Centres, acceptance and implementation in Canada have been suboptimal.

METHODS

To improve diagnosis, monitoring, and management of a clinically isolated syndrome and MS, a Canadian expert panel created consensus recommendations about the appropriate application of the 2010 McDonald criteria in routine practice, strategies to improve adherence to the standardized Consortium of Multiple Sclerosis Centres MRI protocol, and methods for ensuring effective communication among health care practitioners, in particular referring physicians, neurologists, and radiologists.

RESULTS

This article presents eight consensus statements developed by the expert panel, along with the rationale underlying the recommendations and commentaries on how to prioritize resource use within the Canadian healthcare system.

CONCLUSIONS

The expert panel calls on neurologists and radiologists in Canada to incorporate the McDonald criteria, the Consortium of Multiple Sclerosis Centres MRI protocol, and other guidance given in this consensus presentation into their practices. By improving communication and general awareness of best practices for MRI use in MS diagnosis and monitoring, we can improve patient care across Canada by providing timely diagnosis, informed management decisions, and better continuity of care.

Automated identification of brain new lesions in multiple sclerosis using subtraction images

PURPOSE

To propose and evaluate a new automated method for the identification of new/enlarging multiple sclerosis (MS) lesions on subtracted images (SI). The subtraction of serially acquired images has shown great potential in assessing new/enlarging brain magnetic resonance imaging (MRI) lesions in MS patients. However, this approach relies on the manual definition of lesions, which is labor-intensive and subject to operator-dependent variability.

MATERIALS AND METHODS

An overestimated mask of candidate SI lesions was created and then these hyperintense voxel clusters were filtered using specific constraints for extent, shape, and intensity. The method was tested on normal and pathological MRI datasets.

RESULTS

The automated method did not detect hyperintense voxels on SI of healthy controls. SI lesions were identified manually and automatically in a multicenter MS dataset of 19 patients with paired MRI over 36 weeks. Sensitivity of the method was high (0.91) and in agreement with the results of manually defined SI lesions (Cohen's k=0.82,95% confidence interval [CI]: 0.77–0.87). On a second multicenter MS dataset of 103 patients with paired MRI over 76 weeks, the number of SI lesions detected automatically correlated with the number of gadolinium-enhancing lesions(r=0.74).

CONCLUSION

The proposed method is robust, accurate,and sensitive and may be used with confidence in Phase II MS trials.

A pattern approach to focal white matter hyperintensities on magnetic resonance imaging

Evaluation of focal white matter hyperintensities on magnetic resonance imaging in any age group is always challenging because the cause of these hyperintensities varies extensively. Understanding the clinical presentation, pathophysiology, and associated imaging findings can allow the radiologist to limit the differential diagnosis. A specific imaging approach including age, pattern of distribution, signal characteristics on various sequences, enhancement pattern, and other ancillary findings helps to identify a correct cause for these hyperintensities. This article provides a pattern approach to differentiate various common and a few uncommon diseases presenting as focal white matter hyperintensities.

Diffusion tensor imaging detects treatment effects of FTY720 in experimental autoimmune encephalomyelitis mice

Fingolimod (FTY720) is an orally available sphingosine-1-phosphate (S1P) receptor modulator reducing relapse frequency in patients with relapsing-remitting multiple sclerosis (RRMS). In addition to immunosuppression, neuronal protection by FTY720 has also been suggested, but remains controversial. Axial and radial diffusivities derived from in vivo diffusion tensor imaging (DTI) were employed as noninvasive biomarkers of axonal injury and demyelination to assess axonal protection by FTY720 in experimental autoimmune encephalomyelitis (EAE) mice. EAE was induced through active immunization of C57BL/6 mice using myelin oligodendrocyte glycoprotein peptide 35-55 (MOG(35-55)). We evaluated both the prophylactic and therapeutic treatment effect of FTY720 at doses of 3 and 10 mg/kg on EAE mice by daily clinical scoring and end-point in vivo DTI. Prophylactic administration of FTY720 suppressed the disease onset and prevented axon and myelin damage when compared with EAE mice without treatment. Therapeutic treatment by FTY720 did not prevent EAE onset, but reduced disease severity, improving axial and radial diffusivity towards the control values without statistical significance. Consistent with previous findings, in vivo DTI-derived axial and radial diffusivity correlated with clinical scores in EAE mice. The results support the use of in vivo DTI as an effective outcome measure for preclinical drug development.

Standardized magnetic resonance imaging acquisition and reporting in pediatric multiple sclerosis

Magnetic resonance (MR) imaging is one of the most important paraclinical tools for the diagnosis of multiple sclerosis (MS), and monitoring of disease progression and treatment response. This article provides clinicians and neuroradiologists caring for children with demyelinating disorders with a suggested standard MR imaging acquisition and reporting protocol, and defines a standard lexicon for lesion features typical of MS in children. As there is considerable overlap between the MR imaging features of pediatric- and adult-onset MS, the recommendations provided herein may be of relevance to radiologists and clinicians caring for adults with multiple sclerosis.

Relevance of hypointense brain MRI lesions for long-term worsening of clinical disability in relapsing multiple sclerosis

BACKGROUND

The accrual of brain focal pathology is considered a good substrate of disability in relapsing-remitting multiple sclerosis (RRMS). However, knowledge on long-term lesion evolution and its relationship with disability progression is poor.

OBJECTIVE

The objective of this paper is to evaluate in RRMS the long-term clinical relevance of brain lesion evolution.

METHODS

In 58 RRMS patients we acquired, using the same scanner and protocol, brain magnetic resonance imaging (MRI) at baseline and 10±0.5 years later. MRI data were correlated with disability changes as measured by the Expanded Disability Status Scale (EDSS).

RESULTS

The annualized 10-year lesion volume (LV) growth was +0.25±0.5 cm(3) (+6.7±8.7%) for T2-weighted (T2-W) lesions and +0.20±0.31 cm(3) (+11.5±12.3%) for T1-weighted (T1-W) lesions. The univariate analysis showed moderate correlations between baseline MRI measures and EDSS at 10 years (p < 0.001). Also, 10-year EDSS worsening correlated with LV growth and the number of new/enlarging lesions measured over the same period (p < 0.005). In the stepwise multiple regression analysis, EDSS worsening over 10 years was best correlated with the combination of baseline T1-W lesion count and increasing T1-W LV (R = 0.61, p < 0.001).

CONCLUSION

In RRMS patients, long-term brain lesion accrual is associated with worsening in clinical disability. This is particularly true for hypointense, destructive lesions.

Tumefactive multiple sclerosis: an uncommon diagnostic challenge

OBJECTIVE

This case report describes a rare presentation of multiple sclerosis (MS) that was initially diagnosed as a peripheral nerve lesion in the emergency department.

CLINICAL FEATURES

A 30-year-old woman presented to a chiropractic teaching clinic with a complaint of a sudden right foot drop. Magnetic resonance imaging of the brain revealed a large mass in the left parietal lobe with additional white matter lesions. The mass and smaller lesions were consistent with a rare presentation of demyelinating disease, tumefactive MS.

INTERVENTION AND OUTCOME

The patient was referred to a neurologist for further evaluation and treatment. Her short-term clinical course was punctuated by recurrent myospasms and neurologic deficits.

CONCLUSION

Tumefactive MS may mimic the clinical and magnetic resonance imaging characteristics of glioma or a cerebral abscess. The clinical presentation, pathophysiology, differential diagnosis, role of diagnostic imaging, and treatment options of MS are described. This case report illustrates that the timely diagnosis and optimal treatment of MS require recognition of its varied, sometimes atypical, and often nonspecific clinical and imaging manifestations.

In vivo quantitative evaluation of brain tissue damage in multiple sclerosis using gradient echo plural contrast imaging technique

Conventional MRI based on weighted spin-echo (SE) images aids in the diagnosis of multiple sclerosis (MS); however, MRI markers derived from SE sequences provide limited information about lesion severity and correlate poorly with patient disability assessed with clinical tests. In this study, we introduced a novel method [based on quantitative R2* (1/T2*) histograms] for estimating the severity of brain tissue damage in MS lesions. We applied at 1.5T an advanced, multi-gradient echo MRI technique [gradient echo plural contrast imaging (GEPCI)] to obtain images of the brains of healthy control subjects and subjects with MS. GEPCI is a simple yet robust technique allowing simultaneous acquisition of inherently co-registered quantitative T2* and FLAIR-like maps, along with T1-weighted images within a clinically acceptable time frame. Images obtained with GEPCI appear highly similar to standard scans; hence, they can be used in a reliable and conventional way for a clinical evaluation of the disease. Yet, the main advantage of GEPCI approach is its quantitative nature. Analysis of R2* histograms of white matter revealed a difference in the distribution between healthy subjects and subjects with MS. Based on this difference, we developed a new method for grading the severity of tissue damage [tissue damage score (TDS)] in MS lesions. This method also provides a tissue damage load (TDL) assessing both lesion load and lesion severity, and a mean tissue damage score (MTDS) estimating the average MS lesion damage. We found promising correlations between the results derived from this method and the standard measure of clinical disability.

Pathophysiology of the lymphatic drainage of the central nervous system: Implications for pathogenesis and therapy of multiple sclerosis

In most organs of the body, immunological reactions involve the drainage of antigens and antigen presenting cells (APCs) along defined lymphatic channels to regional lymph nodes. The CNS is considered to be an immunologically privileged organ with no conventional lymphatics. However, immunological reactions do occur in the CNS in response to infections and in immune-mediated disorders such as multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). Here, we review evidence that cervical lymph nodes play a role in B and T cell mediated immune reactions in the CNS. Then we define the separate pathways by which interstitial fluid (ISF) and CSF drain to cervical lymph nodes. ISF and solutes drain from the brain along the 100-150nm-wide basement membranes in the walls of capillaries and arteries. In humans, this perivascular pathway is outlined by the deposition of insoluble amyloid (Abeta) in capillary and artery walls in cerebral amyloid angiopathy in Alzheimer's disease. The failure of APCs to migrate to lymph nodes along perivascular lymphatic drainage pathways may be a major factor in immunological privilege of the brain. Lymphatic drainage of CSF is predominantly through the cribriform plate into nasal lymphatics. Lymphatic drainage of ISF and CSF and the specialised cervical lymph nodes to which they drain play significant roles in the induction of immunological tolerance and of adaptive immunological responses in the CNS. Understanding the afferent and efferent arms of the CNS lymphatic system will be valuable for the development of therapeutic strategies for diseases such as MS.

Multiple sclerosis: clinical features, pathophysiology, neuroimaging and future therapies

Multiple sclerosis (MS) is a common immune-mediated progressive neurodegenerative disease of the CNS that typically manifests with periods of disease activity followed by intervals of remission. The etiology of MS remains unknown; however, existing evidence indicates that MS is a ‘whole-brain disease’ that is driven by a potent immune response against CNS antigen(s), particularly myelin peptide antigens. The immunopathogenesis of MS includes both the cell- and humorally-mediated arms of the immune system. Genetic and environmental factors play important roles in the development of MS. Application of various neuroimaging techniques to the world of MS have expanded our knowledge concerning its pathogenesis and assist us in the more accurate diagnosis of MS versus its imitators. Current treatments target acute attacks and aim to reduce future clinical relapses. A summary of the potential future therapies for MS is presented.