Quantitative diffusion weighted imaging measures in patients with multiple sclerosis

MRI features and disability in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

In this systematic review and meta-analysis, we aimed to investigate the correlation between disability in patients with Multiple sclerosis (MS) measured by the Expanded Disability Status Scale (EDSS) and brain Magnetic Resonance Imaging (MRI) features to provide reliable results on which characteristics in the MRI can predict disability and prognosis of the disease.

METHODS

A systematic literature search was performed using three databases including PubMed, Scopus, and Web of Science. The selected peer-reviewed studies must report a correlation between EDSS scores and MRI features. The correlation coefficients of included studies were converted to the Fisher's z scale, and the results were pooled.

RESULTS

Overall, 105 studies A total of 16,613 patients with MS entered our study. We found no significant correlation between total brain volume and EDSS assessment (95 % CI: -0.37 to 0.08; z-score: -0.15). We examined the potential correlation between the volume of T1 and T2 lesions and the level of disability. A positive significant correlation was found (95 % CI: 0.19 to 0.43; z-score: 0.31), (95 % CI: 0.17 to 0.33; z-score: 0.25). We observed a significant correlation between white matter volume and EDSS score in patients with MS (95 % CI: -0.37 to -0.03; z-score: -0.21). Moreover, there was a significant negative correlation between gray matter volume and disability (95 % CI: -0.025 to -0.07; z-score: -0.16).

CONCLUSION

In conclusion, this systematic review and meta-analysis revealed that disability in patients with MS is linked to extensive changes in different brain regions, encompassing gray and white matter, as well as T1 and T2 weighted MRI lesions.

Correlation between the clinical disability and T1 hypointense lesions' volume in cerebral magnetic resonance imaging of multiple sclerosis patients: A systematic review and meta-analysis

BACKGROUND

To evaluate the correlation between T1 hypointense lesions' mean volume on cerebral MRI with disability level of patients with multiple sclerosis.

METHODS

We included studies testing the desired outcome in adult patients diagnosed with RRMS or SPMS. In Feb 2021, we searched PubMed, Embase, CENTRAL, and Web of Science to find relevant studies. All included studies were assessed for the risk of bias using a tailored version of the Quality in Prognosis Studies (QUIPS) tool. Extracted correlation coefficients were converted to the Fisher's z scale, and a meta-analysis using a random-effects model was performed on the results.

RESULTS

We included 27 studies (1919 participants). Meta-analysis revealed a correlation coefficient of 0.32 (95% CI 0.26-0.37) between T1 hypointense lesions' mean volume and EDSS score.

DISCUSSION

The correlation between T1 hypointense lesions' mean volume and EDSS was interpreted as low to slightly moderate. The certainty of the evidence was judged to be high.

Multiple sclerosis and subclinical neuropathology in healthy individuals with familial risk: A scoping review of MRI studies

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MRI evidence of MS pathology in healthy individuals reflects a subclinical period.

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First-degree relatives of MS patients are ideal to study MS subclinical neuropathology.

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MRI found WM focal inflammation in a substantial proportion of these healthy relatives.

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Diffuse tissue damage is also found by MRI in healthy relatives of MS patients.

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MS prodromal phase can be characterized by studying healthy subjects at high risk.

Multiple genetic and non-heritable factors have been linked to the risk of multiple sclerosis (MS). These factors seem to contribute to disease pathogenesis before the onset of clinical symptoms, as suggested by incidental MRI evidence of subclinical MS neuropathology in individuals without clinical symptoms. Individuals with high familial risk for MS, such as first-degree relatives of patients with MS, can be studied by MRI to characterize the neuropathology during a subclinical period of MS. 16 studies published in English, which performed brain MRI on healthy individuals with high familial risk of MS were included in this scoping review. Studies suggest either no conclusive (5), or inconclusive yet considerable (4), or conclusive evidence (7) for the incidence of subclinical neuropathology, including focal and diffuse tissue damage. Across all studies, white matter lesions fulfilling MS criteria were observed in 86 of 613 individuals (14%). Future research is needed to evaluate the longitudinal dynamics and clinical relevance of preclinical imaging abnormalities in MS.

Complexity Analysis of Resting-State fMRI in Adult Patients with Attention Deficit Hyperactivity Disorder: Brain Entropy

Objective

Complexity analysis of functional brain structure data represents a new multidisciplinary approach to examining complex, living structures. I aimed to construct a connectivity map of visual brain activities using resting-state functional magnetic resonance imaging (fMRI) data and to characterize the level of complexity of functional brain activity using these connectivity data.

Methods

A total of 25 healthy controls and 20 patients with attention deficit hyperactivity disorder (ADHD) participated. fMRI preprocessing analysis was performed that included head motion correction, temporal filtering, and spatial smoothing process. Brain entropy (BEN) was calculated using the Shannon entropy equation.

Results

My findings demonstrated that patients exhibited reduced brain complexity in visual brain areas compared to controls. The mean entropy value of the ADHD group was 0.56 ± 0.14, compared to 0.64 ± 0.11 in the control group.

Conclusion

My study adds an important novel result to the growing literature pertaining to abnormal visual processing in ADHD that my ADHD patients had lower BEN values, indicating more-regular functional brain structure and abnormal visual information processing.

Brain Parenchymal Fraction in Healthy Adults-A Systematic Review of the Literature

Brain atrophy is an important feature of many neurodegenerative disorders. It can be described in terms of change in the brain parenchymal fraction (BPF). In order to interpret the BPF in disease, knowledge on the BPF in healthy individuals is required. The aim of this study was to establish a normal range of values for the BPF of healthy individuals via a systematic review of the literature. The databases PubMed and Scopus were searched and 95 articles, including a total of 9269 individuals, were identified including the required data. We present values of BPF from healthy individuals stratified by age and post-processing method. The mean BPF correlated with mean age and there were significant differences in age-adjusted mean BPF between methods. This study contributes to increased knowledge about BPF in healthy individuals, which may assist in the interpretation of BPF in the setting of disease. We highlight the differences between post-processing methods and the need for a consensus gold standard.

Whole-lesion apparent diffusion coefficient (ADC) metrics as a marker of breast tumour characterization-comparison between ADC value and ADC entropy

OBJECTIVE

To prospectively assess the role of whole-lesion apparent diffusion coefficient (ADC) metrics in the characterization of breast tumours by comparing ADC value with ADC entropy.

METHODS

49 patients with 53 breast lesions underwent phased-array breast coil 1.5-T MRI. Two radiologists experienced in breast MRI, blinded to the final diagnosis, reviewed the ADC maps and placed a volume of interest on all slices including each lesion on the ADC map to obtain whole-lesion mean ADC value and ADC entropy. The mean ADC value and ADC entropy in benign and malignant lesions were compared by the Mann-Whitney U-test. Receiver-operating characteristic analysis was performed to assess the sensitivity and specificity of the two variables in the characterization of the breast lesions.

RESULTS

The benign (n = 19) and malignant lesions (n = 34) had mean diameters of 20.8 mm (10.1-31.5 mm) and 26.4 mm (10.5-42.3 mm), respectively. The mean ADC value of the malignant lesions was significantly lower than that of the benign ones (0.87 × 10^-3 vs 1.49 × 10^-3 mm² s^-1; p < 0.0001). Malignant ADC entropy was higher than benign entropy, without reaching levels of statistical significance (5.4 vs 5.0; p = 0.064). At a mean ADC cut-off value of 1.16 × 10^-3 mm² s^-1, the sensitivity and specificity for diagnosing malignancy became optimal (97.1% and 93.7, respectively) with an area under the curve (AUC) of 0.975. With regard to ADC entropy, the sensitivity and specificity at a cut-off of 5.18 were 67.6 and 68.7%, respectively, with an AUC of 0.664.

CONCLUSION

Whole-lesion mean ADC could be a helpful index in the characterization of suspicious breast lesions, with higher sensitivity and specificity than ADC entropy. Advances in knowledge: Two separate parameters of the whole-lesion histogram were compared for their diagnostic accuracy in characterizing breast lesions. Mean ADC was found to be able to characterize breast lesions, whereas entropy proved to be unable to differentiate benign from malignant breast lesions. It is, however, likely that entropy may distinguish these two groups if a larger cohort were used, or the fact that this may be influenced by the molecular subtypes of breast cancers included.

Intrinsic Functional Plasticity of the Thalamocortical System in Minimally Disabled Patients with Relapsing-Remitting Multiple Sclerosis

The thalamus plays a crucial role in sensorimotor, cognitive, and attentional circuit functions. Disruptions in thalamic connectivity are believed to underlie the symptoms of multiple sclerosis (MS). Therefore, assessing thalamocortical structural connectivity (SC) and functional connectivity (FC) may provide new insights into the mechanism of intrinsic functional plasticity in a large-scale neural network. We used resting-state FC measurement and diffusion tensor imaging probabilistic tractography to study the functional and structural integrity of the thalamocortical system in patients with relapsing-remitting MS (RRMS) and matched healthy controls. In the thalamocortical connections of RRMS patients, we found lesion load-related regional FC in the right temporal pole, which reflected compensatory hyperconnectivity related to lesion-related demyelination. We also found significant correlations between increased diffusivity and slowed cognitive processing (PASAT) or the impact of fatigue (MFIS-5), as well as between connective fiber loss and disease duration. Taken together, the evidence from SC and FC analysis of the thalamocortical system suggests that minimally disabled RRMS patients exhibit a dissociated SC-FC pattern and limited regional functional plasticity to compensate for the chronic demyelination-related loss of long-distance SC. These results also provide further evidence supporting the notion that MS is a disorder of anatomical disconnection.

A semi-automated measuring system of brain diffusion and perfusion magnetic resonance imaging abnormalities in patients with multiple sclerosis based on the integration of coregistration and tissue segmentation procedures

Background

Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) abnormalities in patients with multiple sclerosis (MS) are currently measured by a complex combination of separate procedures. Therefore, the purpose of this study was to provide a reliable method for reducing analysis complexity and obtaining reproducible results.

Methods

We implemented a semi-automated measuring system in which different well-known software components for magnetic resonance imaging (MRI) analysis are integrated to obtain reliable measurements of DWI and PWI disturbances in MS.

Results

We generated the Diffusion/Perfusion Project (DPP) Suite, in which a series of external software programs are managed and harmonically and hierarchically incorporated by in-house developed Matlab software to perform the following processes: 1) image pre-processing, including imaging data anonymization and conversion from DICOM to Nifti format; 2) co-registration of 2D and 3D non-enhanced and Gd-enhanced T1-weighted images in fluid-attenuated inversion recovery (FLAIR) space; 3) lesion segmentation and classification, in which FLAIR lesions are at first segmented and then categorized according to their presumed evolution; 4) co-registration of segmented FLAIR lesion in T1 space to obtain the FLAIR lesion mask in the T1 space; 5) normal appearing tissue segmentation, in which T1 lesion mask is used to segment basal ganglia/thalami, normal appearing grey matter (NAGM) and normal appearing white matter (NAWM); 6) DWI and PWI map generation; 7) co-registration of basal ganglia/thalami, NAGM, NAWM, DWI and PWI maps in previously segmented FLAIR space; 8) data analysis. All these steps are automatic, except for lesion segmentation and classification.

Conclusion

We developed a promising method to limit misclassifications and user errors, providing clinical researchers with a practical and reproducible tool to measure DWI and PWI changes in MS.

The prognostic utility of MRI in clinically isolated syndrome: a literature review

For patients presenting with clinically isolated syndrome, the treating clinician needs to advise the patient on the probability of conversion to clinically definite multiple sclerosis. MR imaging may give useful prognostic information, and there is large body of literature pertaining to the use of MR imaging in assessing patients presenting with clinically isolated syndrome. This literature review evaluates the accuracy of MR imaging in predicting which patients with clinically isolated syndrome will go on to develop long-term disease and/or disability. New and emerging MR imaging technologies and their applicability to patients with clinically isolated syndrome are also considered.

Entropy of T2-weighted imaging combined with apparent diffusion coefficient in prediction of uterine leiomyoma volume response after uterine artery embolization

RATIONALE AND OBJECTIVES

To determine the potential value of entropy of T2-weighted imaging combined with apparent diffusion coefficient (ADC) before uterine artery embolization (UAE) for prediction of uterine leiomyoma volume reduction (VR) after UAE.

MATERIALS AND METHODS

In this prospective study, 11 patients with uterine leiomyomas who underwent pelvic magnetic resonance imaging including diffusion-weighted imaging before and 6 months after UAE were included. A total number of 16 leiomyomas larger than 2 cm in diameter were evaluated. The volume of each leiomyoma before and after UAE was determined, and the percentage change in volume was calculated. Entropy of T2-weighted imaging and ADC before UAE were assessed. Pearson correction coefficients were calculated between leiomyoma VR after UAE and age, leiomyoma volume, ADC, and entropy, respectively. Multiple regression analysis was performed to investigate the parameters that determine the VR after UAE. Receiver operating characteristic curve analysis was used to determine the sensitivity and specificity of ADC, entropy and the combination of ADC and entropy for predicting volume response.

RESULTS

The mean leiomyoma VR was 58.9% (range 25.8%-95.0%) in the 6-month follow-up. The mean ADC of leiomyomas was 1.37 × 10(-3) mm(2)/s (range 1.05 × 10(-3)-2.32 × 10(-3) mm(2)/s) and the mean entropy of T2-weighted imaging was 5.36 (range 4.62-5.91) before UAE. ADC and entropy were significantly correlated with leiomyoma VR, respectively (r = 0.61, P = .012; r = 0.73, P = .001). On multiple regression analysis, a combination of ADC and entropy constituted the best model for determining leiomyoma VR using Akaike information criterion. For predicting ≥50% VR, the optimal cutoff value of ADC was 1.39 × 10(-3) mm(2)/s (sensitivity 45.5%, specificity 80.0%) and the optimal cutoff value of entropy was 5.15 (sensitivity 90.9%, specificity 60.0%). The combination of ADC and entropy (area under the curve [AUC] 0.86) provided better classification accuracy than ADC or entropy alone (AUC 0.69 and 0.82, respectively).

CONCLUSIONS

Pre-UAE entropy of T2-weighted imaging and ADC of leiomyomas were significantly correlated with the leiomyoma VR 6 months after embolization. Higher entropy and higher ADC may be related to greater leiomyoma VR after UAE. A combination of entropy and ADC may have predictive value for leiomyoma VR after UAE.

Whole-lesion apparent diffusion coefficient metrics as a marker of percentage Gleason 4 component within Gleason 7 prostate cancer at radical prostatectomy

PURPOSE

To retrospectively assess the utility of whole-lesion apparent diffusion coefficient (ADC) metrics in characterizing the Gleason 4 component of Gleason 7 prostate cancer (PCa) at radical prostatectomy.

MATERIALS AND METHODS

Seventy patients underwent phased-array coil 3T-magnetic resonance imaging (MRI) before prostatectomy. A uropathologist mapped locations and Gleason 4 percentage (G4%) of Gleason 7 tumors. Two radiologists independently reviewed ADC maps, aware of tumor locations but not G4%, and placed a volume-of-interest (VOI) on all slices including each lesion on the ADC map to obtain whole-lesion mean ADC and ADC entropy. Entropy reflects textural variation and increases with greater macroscopic heterogeneity. Performance for characterizing Gleason 7 tumors was assessed with mixed-model analysis of variance (ANOVA) and logistic regression.

RESULTS

Among 84 Gleason 7 tumors (G4% 5%-85%, median 30%; 59 Gleason 3+4, 25 Gleason 4+3), ADC entropy was significantly higher in Gleason 4+3 than Gleason 3+4 tumors (R1: 5.27 ± 0.61 vs. 4.62 ± 0.78, P = 0.001; R2: 5.91 ± 0.32 vs. 5.57 ± 0.56, P = 0.004); mean ADC was not significantly different between these groups (R1: 0.90 ± 0.15*10(-3) cm(2) /s vs. 0.98 ± 0.21*10(-3) cm(2) /s, P = 0.075; R2: 1.06 ± 0.19*10(-3) cm(2) /s vs. 1.14 ± 0.16*10(-3) cm(2) /s, P = 0.083). The area under the receiver operating characteristic (ROC) curve (AUC) for differentiating groups was significantly higher with ADC entropy than mean ADC for one observer (R1: 0.74 vs. 0.57, P = 0.027; R2: 0.69 vs. 0.61, P = 0.329). For R1, correlation with G4% was moderate for ADC entropy (r = 0.45) and weak for mean ADC (r = -0.25). For R2, correlation with G4% was moderate for ADC entropy (r = 0.41) and mean ADC (r = -0.32). For both readers, ADC entropy (P = 0.028-0.003), but not mean ADC (P = 0.384-0.854), was a significant independent predictor of G4%.

CONCLUSION

Whole-lesion ADC entropy outperformed mean ADC in characterizing Gleason 7 tumors and may help refine prognosis for this heterogeneous PCa subset.

Diffusion-weighted imaging of the liver: an update

Diffusion-weighted magnetic resonance imaging (DW-MRI) is now widely used as a standard imaging sequence for evaluation of the liver. The technique is easy to implement across different MRI platforms, and results in enhanced disease detection and characterization. With careful implementation, the quantitative apparent diffusion coefficient derived shows good measurement reproducibility, which can be applied for tissue characterization, the assessment of tumour response and disease prognostication. There is now a body of evidence that highlights the relative strengths and limitations of the technique for the assessment of liver diseases. The potential for more sophisticated analysis of DW-MRI data is currently being widely investigated.

MRI characteristics of familial and sporadic multiple sclerosis patients

PURPOSE

To investigate the MRI characteristics in a large cohort of multiple sclerosis (MS) patients with and without a family history of MS.

METHODS

Enrolled in this prospective study were 758 consecutive MS patients (mean age 46.2 ± 10.1 years, disease duration 13.6 ± 9.2 years and EDSS 3.4 ± 2.1), of whom 477 had relapsing-remitting, 222 secondary-progressive, and 30 primary-progressive disease courses and 29 had clinically isolated syndrome. One hundred and ninety-six patients (25.9%) had a positive family history of MS. Patients were assessed using measurements of lesions, brain atrophy, magnetization transfer ratio (MTR) and diffusion-weighted imaging.

RESULTS

The familial MS group had greater T1-lesion volume (p=0.009) and a trend for lower MTR of T1-lesion volume (p=0.047) than the sporadic MS group. No clinical differences were found between familial versus sporadic group, or by a degree of affected relative subgroups.

CONCLUSIONS

While familial MS was associated with more severe T1-lesion volume and its MTR characteristics, there were no clinical status differences between familial and sporadic MS patients. Therefore, a better understanding of the genetic and/or epigenetic influences causing these differences can advance the understanding and management of MS.

Brain volume and diffusion markers as predictors of disability and short-term disease evolution in multiple sclerosis

BACKGROUND AND PURPOSE

MRI markers of neuroaxonal damage in MS have emerged as critical long-term predictors of MS-related disability. Here we investigated the potential of whole-brain diffusivity and brain volume for the prediction of cross-sectional disability and short- to medium-term clinical evolution.

MATERIALS AND METHODS

In this multimodal prospective longitudinal MRI study of 54 patients with MS (87% under immunomodulatory therapy, baseline and follow-up at a median of 12 months), ADC histogram analysis, WM lesion load, BPF, whole-brain atrophy rate, MSFC score, and EDSS score were obtained. A total of 44 patients with no relapse at both time points were included.

RESULTS

At both time points, ADC histogram analysis provided robust predictors of the MSFC scores (maximal R(2) = 0.576, P < .001), incorporated cognition and fine-motor skill subscores, and EDSS scores. Significant changes beyond physiologic age-related changes at follow-up were noted for ADC histogram markers and BPF. Stronger diffusivity alterations and brain volume at baseline predicted MSFC decline, as demonstrated by multiple linear regression analysis (mean ADC, R(2) = 0.203; P = .003) and lower baseline BPF in patients with declined compared with stable MSFC scores (P = .001). Results were independent of intercurrent relapses.

CONCLUSIONS

Diffusion histogram analysis provided stable surrogates of disability in MS and proved sensitive for monitoring disease progression during a median of 12 months. Advanced neuroaxonal pathology at baseline was indicative of an increased risk for sustained progression during a median of 12 months, independent of intercurrent relapses.

Composite MRI scores improve correlation with EDSS in multiple sclerosis

BACKGROUND

Quantitative measures derived from magnetic resonance imaging (MRI) have been widely investigated as non-invasive biomarkers in multiple sclerosis (MS). However, the correlation of single measures with Expanded Disability Status Scale (EDSS) is poor, especially for studies with large population samples.

OBJECTIVE

To explore the correlation of MRI-derived measures with EDSS through composite MRI scores.

METHODS

Magnetic resonance images of 126 patients with relapsing-remitting MS were segmented into white and gray matter, cerebrospinal fluid, T2-hyperintense lesions, gadolinium contrast-enhancing lesions, T1-hypointense lesions ('black holes': BH). The volumes and average T2 values for each of these tissues and lesions were calculated and converted to a z-score (in units of standard deviation from the mean). These z-scores were combined to construct composite z-scores, and evaluated against individual z-scores for correlation with EDSS.

RESULTS

Composite scores including relaxation times of different tissues and/or volumetric measures generally correlated more strongly with EDSS than individual measures. The maximum observed correlation of a composite with EDSS was r = 0.344 (p < 0.0001), which is an improvement over the highest-performing single MRI measure (BH; r = 0.298, p < 0.001).

CONCLUSION

Z-transformation permits construction of composite scores including volumetric and T2-relaxation measures. Inclusion of multiple MRI measures in the composite can provide a broader characterization of the disease process, resulting in more robust correlations with EDSS.

Multiple sclerosis with initial stroke-like clinicoradiologic features: case report and literature review

A 17-year-old male presented with sudden onset of persistent focal neurological symptoms. Magnetic resonance imaging (MRI) demonstrated a nonenhancing white matter lesion that appeared hyperintense on fluid-attenuated inversion recovery sequence and diffusion-weighted imaging, while hypointense on apparent diffusion coefficient mapping corresponding to the patient's clinical features. A smaller subclinical lesion was also present. The patient's history, radiographic findings, and initial hospital course including response to treatment appeared supportive of a stroke diagnosis. However, a rapid recovery from his severe neurological deficits and results of subsequent serologic testing strongly indicated a demyelinating condition. The onset of adolescent multiple sclerosis can present diagnostic and therapeutic challenges, especially when the initial demyelinating event resembles an acute stroke in clinical and radiographic presentation. Every effort should be made to distinguish these diagnoses as early as possible to ensure timely and appropriate management.

MRI characteristics of patients with antiphospholipid syndrome and multiple sclerosis

MRI findings of primary anti-phospholipid antibody syndrome (PAPLS) are difficult to distinguish from those of multiple sclerosis (MS). Only a few previous studies have compared conventional and non-conventional MRI findings in MS and PAPLS patients. In addition, MRI differences between anti-phospholipid antibody (APLA) positive (+) and APLA negative (-) MS patients have not been reported. Therefore, the aim of this study was to investigate the differences in MRI measures among patients with PAPLS, MS and normal control (NC) subjects. We also explored non-conventional MRI measures in APLA+ and APLA- MS patients. Forty-nine (49) consecutive MS patients among whom 39 had relapsing-remitting (RR) and 10 secondary-progressive (SP) disease course, 30 patients with PAPLS and 49 NC were enrolled. Twenty-eight (28) MS patients were APLA+. MRI measures of T1- and T2-lesion volumes (LV) and brain atrophy, including fractions of whole brain (BPF), gray matter (GMF) and white matter (WMF), were evaluated. The magnetization transfer ratio (MTR) of T2- and T1-LVs and different normal-appearing brain tissue (NABT) compartments as well as diffusion-weighted imaging of whole brain mean parenchyma diffusivity (MPD) were obtained. MS patients differed significantly from NC in all MRI measures. PAPLS patients differed from NC in their T2-LV, in MTR measures and in MPD. When MS patients were compared to PAPLS patients, they showed significantly higher T2- and T1-LVs and T2-LV MTR, lower BPF and GMF and higher MPD. APLA+ RR and SPMS (all APLA+) patients showed significantly higher T2-LV, lower GMF, lower normal-appearing gray matter MTR and higher MPD when compared to APLA- patients. The results indicate that brain abnormalities can be detected in PAPLS patients with non-conventional MRI. MRI reveals more profound injury in patients with MS versus PAPLS. APLA mediates heterogeneous cerebral pathology that remains to be further investigated.

Relationship of optic nerve and brain conventional and non-conventional MRI measures and retinal nerve fiber layer thickness, as assessed by OCT and GDx: a pilot study

BACKGROUND

Measurement of retinal nerve fiber layer (RNFL) thickness in multiple sclerosis (MS) is gaining increasing attention.

OBJECTIVES

To explore the relationship between RNFL thickness as measured by optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDx), and conventional and non-conventional optic nerve and brain MRI measures.

METHODS

Twelve relapsing-remitting (RR) MS patients (12 affected and 12 unaffected eyes) and 4 age- and sex-matched normal controls (NC) (8 unaffected eyes) were enrolled. Four MS patients had a history of bilateral optic neuritis (ON), four had a history of unilateral ON, and 4 had no history of ON. Optic nerve MRI measurements included the length of T2 lesions, measurement of optic nerve atrophy, magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) measures. Optic nerve atrophy was measured by a novel method with high reproducibility. Brain MRI measurements included T1 and T2 lesion volumes (LVs) and their relative MTRs, and tissue class specific atrophy, MTR and DTI measures. Measures of RNFL were evaluated with OCT and GDx. We also evaluated both high and low contrast letter acuities (LCLA) in order to determine the relationship between vision, MRI metrics, and retinal structural architecture.

RESULTS

LCLA, RNFL-OCT and optic nerve radius measures showed more robust differences between NC and MS patients, and between MS patients with affected and unaffected eyes. T2-LV and T1-LV, as well as gray matter atrophy, DTI and MTR measures were related to LCLA and RNFL thickness. Unique additive variance regression models showed that both brain and optic nerve MRI measures independently accounted for about 50% of the variance in LCLA and RNFL thickness. In reverse models, about 20% of the additional independent variance was explained by optic nerve or brain MRI metrics.

CONCLUSIONS

Measurement of RNFL thickness and radius of the optic nerve should be preferred to the other optic nerve MRI measures in clinical studies. Whole brain lesion and GM measures are predictive of impaired visual function with corresponding structural concomitants.

T2 detection of tumor invasion within segmented components of glioblastoma multiforme

PURPOSE

To use T2-weighted images to detect tumor invasion when comparing normal individuals to groups of gliomablastoma multiforme (GBM) patients with varying levels of CXCR4, a chemokine receptor that promotes tumor migration.

MATERIALS AND METHODS

T2-weighted images were acquired preoperatively in 22 treatment-naïve GBM patients. Two groups were formed based on the expression levels of CXCR4. A third group of normal volunteers was used for comparison. Each image was segmented to obtain four different clusters for tissue types identified as white matter, basal ganglia, gray matter/edema and cerebrospinal fluid (CSF)/tumor. Signal intensity histograms were formed for each cluster and compared between groups.

RESULTS

In every cluster the GBM groups displayed significantly higher standard deviations of intensity distributions when compared to normal subjects. Significant differences in skewness were found between normal subjects and GBM patients in the white matter, basal ganglia, and CSF/tumor. Further, when the two groups of GBM patients were compared the CXCR4-high group was found to have a significant shift in the median intensity values in the cluster containing gray matter and peritumoral edema.

CONCLUSION

T2 signal intensity histograms in normal subjects differ significantly from those obtained from GBM groups, suggesting widespread dissemination of disease.

Gender-related differences in MS: a study of conventional and nonconventional MRI measures

Background

Studies showed gender-associated differences in multiple sclerosis (MS) disease evolution and in the evolution of conventional magnetic resonance imaging (MRI) findings.

Objective

The aim of this study was to investigate gender differences according to a number of conventional and nonconventional MRI measures in patients with MS.

Methods

We examined 763 consecutive patients with MS [499 (19.2% men) relapsing-remitting (RR), 230 (24.8% men) secondary-progressive, and 34 (44.1% men) primary-progressive], 32 (21.9% men) patients with clinically isolated syndrome (CIS), and 101 (30.7% men) normal controls (NC). Patients were assessed using conventional and nonconventional MRI measures. Gender-related MRI differences were investigated using general linear model analysis, corrected for MS disease type.

Results

In the total MS group, male patients showed lower normalized peripheral gray matter (GM) ( P < 0.001) and normalized GM ( P = 0.011) volumes than female patients. Female patients presented lower normalized white matter (WM) volumes ( P = 0.011). These gender effects were not observed in NC. Male patients also showed more advanced central atrophy ( P = 0.022). In RRMS male patients, there was also a higher lateral ventricle volume ( P = 0.001). The GM-WM normalized ratio was lower for male patients with MS compared with male NC (0.97 vs. 1.09, P < 0.001) but not in patients with CIS compared with NC.

Conclusions

There were no significant gender-related differences regarding nonconventional MRI measures. GM and central atrophy are more advanced in male patients, whereas WM atrophy is more advanced in female patients. These gender-related MRI differences may be explained by the effect of sex hormones on brain damage and repair mechanisms.

Preserved decision making ability in early multiple sclerosis

BACKGROUND

The purpose of this study was to assess decision making in patients with multiple sclerosis (MS) at the earliest clinically detectable time point of the disease.

METHODS

Patients with definite MS (n = 109) or with clinically isolated syndrome (CIS, n = 56), a disease duration of 3 months to 5 years, and no or only minor neurological impairment (Expanded Disability Status Scale [EDSS] score 0-2.5) were compared to 50 healthy controls using the Iowa Gambling Task (IGT).

RESULTS

The performance of definite MS, CIS patients, and controls was comparable for the two main outcomes of the IGT (learning index: p = 0.7; total score: p = 0.6). The IGT learning index was influenced by the educational level and the co-occurrence of minor depression. CIS and MS patients developing a relapse during an observation period of 15 months dated from IGT testing demonstrated a lower learning index in the IGT than patients who had no exacerbation (p = 0.02). When controlling for age, gender and education, the difference between relapsing and non-relapsing patients was at the limit of significance (p = 0.06).

CONCLUSION

Decision making in a task mimicking real life decisions is generally preserved in early MS patients as compared to controls. A possible consequence of MS relapsing activity in the impairment of decision making ability is also suspected in the early phase of MS.

Application of hidden Markov random field approach for quantification of perfusion/diffusion mismatch in acute ischemic stroke

The perfusion/diffusion 'mismatch model' in acute ischemic stroke provides the potential to more accurately understand the consequences of thrombolytic therapy on an individual patient basis. Few methods exist to quantify mismatch extent (ischemic penumbra) and none have shown a robust ability to predict infarcted tissue outcome. Hidden Markov random field (HMRF) approaches have been used successfully in many other applications. The aim of the study was to develop a method for rapid and reliable identification and quantification of perfusion/diffusion mismatch using an HMRF approach. An HMRF model was used in combination with automated contralateral identification to segment normal tissue from non-infarcted tissue with perfusion abnormality. The infarct was used as a seed point to initialize segmentation, along with the contralateral mirror tissue. The two seeds were then allowed to compete for ownership of all unclassified tissue. In addition, a novel method was presented for quantifying tissue salvageability by weighting the volume with the degree of hypoperfusion, allowing the penumbra voxels to contribute unequal potential damage estimates. Simulated and in vivo datasets were processed and compared with results from a conventional thresholding approach. Both simulated and in vivo experiments demonstrated a dramatic improvement in accuracy with the proposed technique. For the simulated dataset, the mean absolute error decreased from 171.9% with conventional thresholding to 2.9% for the delay-weighted HMRF approach. For the in vivo dataset, the mean absolute error decreased from 564.6% for thresholding to 34.2% for the delay-weighted HMRF approach. The described method represents a significant improvement over thresholding techniques.

Cognitive dysfunction in MS: bridging the gap between neurocognitive deficits, neuropsychological batteries and MRI

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the CNS. Its sequelae include both physical and cognitive disability. Advances in neuropsychological testing and screening have led to increased recognition of cognitive impairment in MS; more than half of MS patients have been found to have some degree of cognitive impairment. Strong correlations have been found between neuropsychological testing, brain atrophy and other brain imaging techniques. These tools can aid in the comprehensive evaluation of MS patients. Genetic markers, such as ApoE and brain-derived neurotrophic factor polymorphisms, may also correlate with cognitive impairment in MS. This review details advances in recognizing and predicting cognitive dysfunction in MS. Increased understanding and better evaluation and monitoring of cognitive status in MS may improve the sensitivity of studies designed to test new disease-modifying therapies and interventions for cognitive impairment.

Retinal nerve fiber layer thickness is associated with brain MRI outcomes in multiple sclerosis

Multiple sclerosis is characterized by the dual pathological processes of inflammation and neurodegeneration. Conventional MRI techniques are considered the best tools for assessing and monitoring lesion burden and inflammation but are limited in their ability to assess axonal loss. Optical coherence tomography (OCT) is a simple high-resolution technique that uses near infrared light to quantify the thickness of the retinal nerve fiber layer (RNFL), which contains only non-myelinated axons. RNFL thickness (RNFLT) was measured using OCT on thirty consecutive MS patients (60 eyes). Eighteen patients underwent quantitative MRI analysis including T1- and T2-lesion volumes (LV), normalized brain volume (NBV), normalized cortical, white and gray matter volumes (NCV, NWMV, and NGMV), and mean whole brain diffusivity (MD). There was a strong association between NBV and average RNFL thickness (p<0.001, partial rp=0.77). The T2-LV and NWMV were significantly associated with average RNFL thickness (p=0.002, partial rp= -0.76 and p=0.005, partial rp=0.68, respectively) and there were trends toward association with T1-LV (p=0.041) and NGMV (p=0.067). There was negative correlation between average RNFL thickness (average of both eyes) and disability as assessed by EDSS (p=0.02). The results support potential usefulness of OCT for MS patient monitoring and research applications.

Comparison of three different methods for measurement of cervical cord atrophy in multiple sclerosis

BACKGROUND AND PURPOSE

Evidence is mounting that spinal cord atrophy significantly correlates with disability in patients with multiple sclerosis (MS). The purpose of this work was to validate 3 different measures for the measurement of cervical cord atrophy on high-resolution MR imaging in patients with MS and in normal control subjects (NCs). We also wanted to evaluate the relationship between cervical cord atrophy and clinical disability in the presence of other conventional and nonconventional brain MR imaging metrics by using a unique additive variance regression model.

MATERIALS AND METHODS

We studied 66 MS patients (age, 41.2 +/- 12.4 years; disease duration, 11.8 +/- 10.7 years; Expanded Disability Status Scale, 3.1 +/- 2.1) and 19 NCs (age, 30.4 +/- 12.0 years). Disease course was relapsing-remitting (34), secondary-progressive (14), primary-progressive (7), and clinically isolated syndrome (11). The cervical cord absolute volume (CCAV) in cubic millimeters and 2 normalized cervical cord measures were calculated as follows: cervical cord fraction (CCF) = CCAV/thecal sac absolute volume, and cervical cord to intracranial volume (ICV) fraction (CCAV/ICV). Cervical and brain lesion volume measures, brain parenchyma fraction (BPF), and mean diffusivity were also calculated.

RESULTS

CCAV (P < .0001) and CCF (P = .007) showed the largest differences between NCs and MS patients and between different disease subtypes. In regression analysis predicting disability, CCAV was retained first (R(2) = 0.498; P < .0001) followed by BPF (R(2) = 0.08; P = .08). Only 8% of the variance in disability was explained by brain MR imaging measures when coadjusted for the amount of cervical cord atrophy.

CONCLUSIONS

3D CCAV measurement showed the largest differences between NCs and MS patients and between different disease subtypes. Cervical cord atrophy measurement provides valuable additional information related to disability that is not obtainable from brain MR imaging metrics.

MRI in multiple sclerosis: what's inside the toolbox?

Magnetic resonance imaging (MRI) has played a central role in the diagnosis and management of multiple sclerosis (MS). In addition, MRI metrics have become key supportive outcome measures to explore drug efficacy in clinical trials. Conventional MRI measures have contributed to the understanding of MS pathophysiology at the macroscopic level yet have failed to provide a complete picture of underlying MS pathology. They also show relatively weak relationships to clinical status such as predictive strength for clinical progression. Advanced quantitative MRI measures such as magnetization transfer, spectroscopy, diffusion imaging, and relaxometry techniques are somewhat more specific and sensitive for underlying pathology. These measures are particularly useful in revealing diffuse damage in cerebral white and gray matter and therefore may help resolve the dissociation between clinical and conventional MRI findings. In this article, we provide an overview of the array of tools available with brain and spinal cord MRI technology as it is applied to MS. We review the most recent data regarding the role of conventional and advanced MRI techniques in the assessment of MS. We focus on the most relevant pathologic and clinical correlation studies relevant to these measures.

Preservation of gray matter volume in multiple sclerosis patients with the Met allele of the rs6265 (Val66Met) SNP of brain-derived neurotrophic factor

To investigate the association of the rs6265 (Val66Met) single nucleotide polymorphism (SNP) of brain-derived neurotrophic factor (BDNF) with brain morphometry and functional status as measured by quantitative magnetic resonance imaging (MRI) and neurocognitive testing in multiple sclerosis (MS) patients. BDNF is released by neurons and by immune cells in MS brain. The rs6265 SNP variation of BDNF causes substitution of valine (Val) for methionine (Met) and interferes with activity-dependent BDNF secretion. A total of 209 treated MS patients (161 females; 48 males) underwent clinical brain MRI and were genotyped for the BDNF rs6265 Val66Met SNP. A subset of 108 patients had neurocognitive testing for processing speed, memory and executive function. The MRI measurements included T2 and T1-lesion volume (LV); normalized brain volume measures of whole brain (WB) volume, white and gray matter volume (NWMV and NGMV) and the diffusion-weighted imaging measure of WB mean parenchyma diffusivity (MPD). The Met66 allele status was positively associated with NGMV (P = 0.015, standardized beta = 0.15) and negatively associated with T2-LV (P = 0.041, standardized beta = -0.14). There were no significant associations between Met66 allele status and T1-LV, NWMV or MPD. On the Paced Serial Addition Test (PASAT), a trend (P = 0.057) favoring the Met66 allele group was observed. There were no significant associations between Met66 allele status and other neurocognitive measures. The BDNF Met66 allele is associated with lower damage as evidenced by measurement of NGMV and T2-LV in MS patients.

Immune cell BDNF secretion is associated with white matter volume in multiple sclerosis

PURPOSE

To investigate the relationship between immune cell secretion of brain-derived neurotrophic factor (BDNF) with clinical and MRI variables in multiple sclerosis (MS) patients.

BACKGROUND

BDNF exerts beneficial effects on neuronal growth and repair and is secreted by both neurons and immune cells. Consequently, it may mediate the crosstalk between the immune system and CNS in autoimmune diseases such as MS.

METHODS

Fifty-two relapsing MS patients (41 females, age: 48.8+/-6.6 years, disease duration: 12.7+/-8.4 years) were enrolled. Clinical and MRI measurements (including, T1-, T2- and contrast-enhancing (CE) lesion volumes (LVs); normalized measures of whole brain, white matter (WM) and gray matter (GM) volumes; diffusion weighted imaging measure of mean whole brain (WB) parenchyma diffusivity and magnetization transfer ratio (MTR) measures were obtained.

RESULTS

Immune cell BDNF secretion after anti-CD3 plus anti-CD28 stimulation was positively associated with increased CE-LV (p=0.026). The MTR of CE-LV and normal-appearing (NA) WM (NAWM) were negatively associated with immune cell BDNF secretion after anti-CD3 plus anti-CD28 stimulation. Immune cell BDNF secretion after anti-CD3 plus anti-CD28 was positively associated with higher WM volume (p=0.027). Immune cell BDNF secretion after anti-CD3 plus anti-CD28 stimulation was decreased with increasing disease duration (p=0.031). The BDNF secretion was independent of the BDNF Val66Met (dBSNP ID: rs6265) SNP genotype.

CONCLUSIONS

Immune cell BDNF secretion is associated with the sites of higher inflammatory activity as evidenced by CE lesions and may represent an important factor associated with the WM volume of patients with MS.