DTI of chronic spinal cord injury in children without MRI abnormalities (SCIWOMR) and with pathology on MRI and comparison to severity of motor impairment

STUDY DESIGN

This investigation was a cohort study that included: 36 typically developing (TD) children and 19 children with spinal cord lesions who underwent spinal cord MRI.

OBJECTIVES

To investigate diffusion tensor imaging (DTI) cervical and thoracic spinal cord changes in pediatric patients that have clinically traumatic and non-traumatic spinal cord injury (SCI) without MR (SCIWOMR) abnormalities.

SETTING

Thomas Jefferson University, Temple University, Shriners Hospitals for Children all in Philadelphia, USA.

METHODS

36 TD children and 19 children with spinal cord lesions that represent either a chronic traumatic acquired SCI or chronic non-traumatic SCI (≥6 months post injury), age range, 6-16 years who underwent cervical and thoracic spinal cord MRI in 2014-2017. Additionally DTI was correlated to clinical American Spinal Injury Association Impairment Scale (AIS).

RESULTS

Both SCIWOMR and MRI positive (+) groups showed abnormal FA and RD DTI values in the adjacent MRI-normal appearing segments of cephalad and caudal spinal cord compared to TD. The FA values demonstrated perilesional abnormal DTI findings in the middle and proximal segments of the cephalad and caudal cord in the SCIWOMR AIS A/B group compared to SCIWOMR AIS C/D group.

CONCLUSIONS

We found DTI changes in children with SCIWOMR with different causes of spinal lesions. We also investigated the relationship between DTI and clinical AIS scores. This study further examined the potential diagnostic value of DTI and should be translatable to adults with spinal cord lesions.

Clinical Utility of Diffusion Tensor Imaging as a Biomarker to Identify Microstructural Changes in Pediatric Spinal Cord Injury

Background

Lack of clarity about the neurological consequence of spinal cord injury (SCI) in children causes speculation about diagnoses, recovery potential, and treatment effectiveness. Diffusion tensor imaging (DTI) has shown promising results as a biomarker to evaluate spinal cord integrity at a microstructural level.

Objectives

To look at the difference between pediatric participants with and without SCI to determine which DTI metrics best categorize spinal cord tissue damage and to correlate DTI metrics with two clinical measures: Capabilities of the Upper Extremity Test (CUE-T) and Spinal Cord Independence Measure version III (SCIM-III).

Methods

This single-site, prospective study included pediatric participants with SCI (n = 26) and typically developed (TD) control subjects (n = 36). All participants underwent two magnetic resonance imaging (MRI) scans on a 3T MR scanner. Participants with SCI also completed the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), CUE-T, and SCIM-III outcomes measures.

Results

This study found significant strength of association between fractional anisotropy (FA) and upper extremity muscle strength (UEMS) in participants with SCI. Most DTI parameters showed a significant difference between participants with SCI and TD participants and a moderate correlation with the CUE-T total score. Regional effects on group differences were found to be significant.

Conclusion

This study demonstrates the strength of association between DTI parameters and clinical measures in the pedantic SCI population. It illustrates DTI as a potential biomarker of SCI location and severity in the pediatric SCI population.

Antiarrhythmic medication for atrial fibrillation (AIM-AF) study: a physician survey of antiarrhythmic drug (AAD) treatment practices and guideline adherence in Europe

Background

The 2020 European Society of Cardiology (ESC) guidelines provide detailed recommendations for the management of patients with atrial fibrillation (AF). In symptomatic patients, AADs are advised for rhythm control.

Purpose

This study was designed to investigate AAD treatment practices and adherence to guidelines in four European countries.

Methods

An online survey (n=321) of cardiologists or cardiac electrophysiologists (CDs) and interventional electrophysiologists (EPs) was conducted in Germany (DE; n=83), Italy (IT; n=95), Sweden (SE; n=60) and the UK (n=83). Respondents were actively treating ≥10 patients with AF.

Results

(1) The majority of physicians considered guidelines to be the most important non-patient factor influencing their AF management practices (pooled: 65%; range: 55–72%), with 96%

(range: 89–100%) following ESC guidelines. Although amiodarone use was most frequent in heart failure with reduced left ventricular (LV) ejection fraction (pooled: 91%; range: 88–93%) where it is a recommended first-line option, non-adherent AAD selection was common. Amiodarone was frequently selected as a typical treatment choice for minimal/no structural heart disease (SHD) where it is not recommended for initial therapy; this was particularly common in the UK versus SE (Figure 1). Other deviations included use of class 1C drugs in those with coronary artery disease (CAD) (with the exception of SE; Figure 1) and other SHD, as well as use of sotalol in LV hypertrophy (pooled: 30%) and renal impairment (Figure 1). Furthermore, absence of inpatient initiation of sotalol was generally high, with the exception of SE (Figure 1).

(2) Sotalol and dronedarone use in CAD varied between country (pooled: 28% [range: 16–41%] and pooled: 19% [range: 10–54%], respectively).

(3) CDs and EPs used rhythm control as initial therapy in most patients with paroxysmal AF (PAF); however, other than SE, this was not the case for persistent AF (Figure 2).

(4) AADs were preferred over ablation as initial therapy for individuals with infrequent, mildly symptomatic PAF (pooled: 61%), with the exception of SE (48%). Ablation was favoured for most patients with frequent, symptomatic PAF; however, in SE, AADs were preferred for infrequent, highly symptomatic PAF (53%) and frequent, symptomatic PAF (53%).

(5) Rhythm control therapies were selected for asymptomatic or subclinical AF; AADs were used more often (average: 41% [range: 22–60%]; ablation was used less frequently (average: 11% [range: 2–18%]).

Conclusion

Despite assertion that guidelines are the primary determinant for rhythm control treatment decisions, non-adherence was notable in European practice. While deviation may be reasonable in select individual patients, in general, non-adherence could compromise patient safety. As such, establishing the drivers of non-adherent practices is key, and education directed at clinicians to improve optimal and safe use of AADs is warranted in Europe.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Sanofi

Factors predicting adverse cardiovascular outcomes in patients with atrial fibrillation and heart failure with preserved ejection fraction

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Electrophysiology Research Foundation

Introduction

Atrial fibrillation (AF) is known to impact cardiovascular(CV) mortality in heart failure (HF) patients (pts) with preserved ejection fraction (pEF) but its exact causes are unknown.

Methods

 We analyzed demographic, clinical, ECG and AF presentation as predictors of CV mortality, sudden death( SCD) and pump failure death(PFD) in HFpEF pts in the TOPCAT AMERICAS trial. We analyzed two AF presentations 1. Pts in sinus rhythm (SR, n = 1319) compared to AF  on ECG (n = 446) at entry or 2. Pts with no AF event by history or ECG ( n = 1007 ) to those with any AF event (n = 760 ).

Results (Table): 5 year (yr) CV mortality was higher in pts with AF on ECG (30%) than SR (18%, p = 0.014) but 5 yr SCD was (10% in AF on ECG & 7% in any AF) & comparable to SR (7% & 9% respectively, p = ns). 5 yr PFD was higher in AF on ECG  (13%) than SR (5%, p = 0.007) 

Conclusions

: 1. CV death risk in HFpEF pts increased with AF on ECG.. 2. SCD was not more frequent with both AF presentations 3. PFD in HFpEF increased with age, ECG recorded AF & elevated heart rate. 4. The recording of AF on ECG was more strongly associated with CV death & PFD, possibly due to greater AF burden . Predictors of adverse outcomes in HFpEF AF on ECG* Any AF* Endpoint Covariate HR (95% CI) p-value HR (95% CI) p-value Time to cardiovascular death Atrial Fibrillation* 1.44 (1.08, 1.92) 0.014 1.15 (0.87, 1.51) 0.338 Age (years) 1.03 (1.02, 1.05) <.001 1.03 (1.02, 1.05) <.001 Black/AA (vs. White) 0.97 (0.65, 1.46) 0.002 0.96 (0.64, 1.44) 0.004 Other race (vs. White) 2.41 (1.46, 3.99) 2.32 (1.41, 3.83) Smoking 2.62 (1.63, 4.20) <.001 2.60 (1.62, 4.17) <.001 Diabetes 1.47 (1.12, 1.94) 0.006 1.45 (1.10, 1.91) 0.009 Systolic BP (mmHg) 0.99 (0.98, 1.00) 0.022 0.99 (0.98, 1.00) 0.014 Heart rate (bpm) 1.02 (1.00, 1.03) 0.012 1.02 (1.01, 1.03) 0.006 Time to Any sudden cardiac death Atrial Fibrillation* 1.17 (0.69, 1.96) 0.563 0.85 (0.53, 1.35) 0.484 Female (vs. Male) 0.46 (0.28, 0.75) 0.002 0.46 (0.28, 0.74) 0.002 Black/AA (vs. White) 1.57 (0.87, 2.82) 0.194 1.49 (0.83, 2.69) <.001 Other race (vs. White) 1.76 (0.70, 4.41) 1.70 (0.68, 4.25) Diabetes 1.70 (1.07, 2.70) 0.024 1.65 (1.04, 2.62) 0.033 Time to pump failure death Atrial Fibrillation* 2.04 (1.22, 3.42) 0.007 1.62 (0.96, 2.75) 0.074 Age (years) 1.06 (1.03, 1.10) <.001 1.06 (1.03, 1.10) <.001 Heart rate (bpm) 1.03 (1.00, 1.05) 0.034 1.03 (1.01, 1.05) 0.015 Cox model of covariates associated with outcomes adjusted for baseline imbalances

Antiarrhythmic Medication for Atrial Fibrillation (AIM-AF) study: A physician survey of antiarrhythmic drug (AAD) treatment practices and guideline adherence in the EU and USA

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Sanofi

Introduction

The 2020 European Society of Cardiology and the 2019 USA (AHA/ACC/HRS) guidelines recommend the use of AADs for rhythm control in patients with symptomatic AF. This study sought to understand AAD treatment practices and adherence to guidelines across the EU and the USA.

Method

An online physician survey of cardiologists, cardiac electrophysiologists and interventional electrophysiologists (N = 569) was conducted in the USA, Germany, Italy and the UK. All respondents were actively treating ≥10 AF patients who received drug therapy and/or who had received or were referred for ablation. This extensively detailed survey explored questions on physician demographics, AF types, and drug treatment and ablation practices.

Results: Of the responses obtained

(1) Amiodarone was used frequently across co-morbidity categories (highest use in those with heart failure with reduced left ventricular ejection fraction [LVEF] [80%]), including in those in which it is not indicated for initial therapy (minimal or no structural heart disease: 26%). Other deviations from guideline recommendations, include: class 1C drugs were used with structural heart disease, including coronary artery disease (CAD) (average class 1C use in CAD-related comorbidities: 6%); sotalol was used with renal dysfunction (22%); and drugs such as sotalol and dofetilide were initiated out of hospital (56% and 17% of respondents, respectively). (2) Nonetheless, a majority of respondents (53%) considered guidelines as the most important non-patient factor in influencing their choice of AF management. (3) Rhythm control was selected more frequently as primary therapy for paroxysmal AF (PAF) (59% of patients) while rate control was used more often for persistent AF (53%). (4) For PAF, AADs were preferred as 1st line more often than ablation, especially if PAF was infrequent and mildly symptomatic (59% of respondents) while ablation was preferred more if frequent symptomatic PAF and for recurrent persistent AF. (5) Rhythm control (AAD or ablation) was chosen in notable numbers for asymptomatic AF and subclinical AF (AADs: 36% and 37%, respectively; ablation: 9% and 14%, respectively). (6) AAD use for those with a first or recurrent episodes of symptomatic AF was 60% or 47%, respectively. (7) Efficacy and safety were chosen as the most important considerations for choice of specific rhythm control therapy (49% and 33%, respectively), and reduction of mortality and cardiovascular hospitalisation (23%) were as important as maintaining sinus rhythm (26%) for rhythm therapy goals.

Conclusions

Although surveyed clinicians consider guidelines important, deviations in patient types and treatments chosen that compromise safety or were not indicated were common. Findings suggest a lack of understanding of the pharmacology and safe use of AADs, highlighting an important need for further education. Abstract Figure.

NCEPOD and alcohol-related liver disease, what are the views of those who deliver the service? A survey of consultants and trainees in North Eastern England

BACKGROUND

National Confidential Enquiry into Patient Outcome and Death (NCEPOD) 'Measuring the Units' (June 2013) identified significant organisational and attitudinal deficits in hospital care of patients with alcohol-related liver disease (ARLD), care being recognised as good in less than 50% of patients.

METHOD

We surveyed over 700 consultants and trainees in acute medical and intensive therapy specialties to examine their perceptions of the NCEPOD findings.

RESULTS

A total of 178 responded. In keeping with the NCEPOD findings, their perception was of lack of 24-hour access to specialty advice for patients with liver disease and inequity of access to high-dependency units. Their explanations include lack of resources, therapeutic nihilism and prejudicial judgements that would not be made of other patient groups.

CONCLUSION

There is an urgent need for robust mechanisms to ensure equity of access to specialist liver advice and intensive therapy unit resources, and to counter negative and prejudicial attitudes to these patients.

Diffusion Tensor Imaging Assessment of Regional White Matter Changes in the Cervical and Thoracic Spinal Cord in Pediatric Subjects

There are no studies to date,describing changes in the diffusion tensor imaging (DTI) metrics of the white matter (WM) regions of the entire cervical and thoracic spinal cord (SC) remote from the lesion in pediatric spinal cord injury (SCI) subjects. The purpose of this study was to determine whether DTI at sites cephalad and caudal to a lesion provides measures of cord abnormalities in children with chronic SCI. A retrospective study included 10 typically developing subjects (TD) and 10 subjects with chronic SCI who underwent SC imaging in 2014-2017. Axial diffusion tensor images using an inner field of view DTI sequence were acquired to cover the entire cervical and thoracic SC. Regions of interest were drawn on the SC WM: right and left lateral (motor), ventral (motor), and dorsal (sensory) tracts. To detect differences in DTI metrics between TD and SCI of the cord, a one way analysis of variance with pooled t test was performed. A stepwise regression analysis was performed to assess the correlation between DTI metrics and clinical scores. In motor and sensory tracts, fractional anisotropy (FA) and axial diffusivity (AD) were significantly decreased in the proximal segments of the caudal cord. In motor tracts cephalad to the lesion, FA was significantly decreased whereas AD was significantly increased in the proximal segment; however, AD was decreased in the distal and middle segments. International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) total score was significantly correlated with FA and AD of the motor and sensory tracts cephalad to the lesion. This study demonstrates that FA and AD have the potential to be sensitive biomarkers of the full extent of cord injury and might be useful in detecting remote injuries to the SC and in guiding new treatments.

Age related diffusion and tractography changes in typically developing pediatric cervical and thoracic spinal cord

Background and objective

Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are two techniques that can measure white matter integrity of the spinal cord. Recently, DTI indices have been shown to change with age. The purpose of this study is (a) to evaluate the maturational states of the entire pediatric spinal cord using DTI and DTT indices including fractional anisotropy (FA), mean diffusivity (MD), mean length of white matter fiber tracts and tract density and (b) to analyze the DTI and DTT parameters along the entire spinal cord as a function of spinal cord levels and age.

Method

A total of 23 typically developing (TD) pediatric subjects ranging in age from 6 to 16 years old (11.94 ± 3.26 (mean ± standard deviation), 13 females and 10 males) were recruited, and scanned using 3.0 T MR scanner. Reduced FOV diffusion tensor images were acquired axially in the same anatomical location prescribed for the T2-weighted images to cover the entire spinal cord (C1-mid L1 levels). To mitigate motion induced artifacts, diffusion directional images were aligned with the reference image (b0) using a rigid body registration algorithm performed by in-house software developed in Matlab (MathWorks, Natick, Massachusetts). Diffusion tensor maps (FA and MD) and streamline deterministic tractography were then generated from the motion corrected DTI dataset. DTI and DTT parameters were calculated by using ROIs drawn to encapsulate the whole cord along the entire spinal cord by an independent board certified neuroradiologist. These indices then were compared between two age groups (age group A = 6-11 years (n = 11) and age group B = 12-16 years (n = 12)) based on similar standards and age definitions used for reporting spinal cord injury in the pediatric population. Standard least squared linear regression based on a restricted maximum likelihood (REML) method was used to evaluate the relationship between age and DTI and DTT parameters.

Results

An increase in FA (group A = 0.42 ± 0.097, group B = 0.49 ± 0.116), white matter tract density (group A = 368.01 ± 236.88, group B = 440.13 ± 245.24) and mean length of fiber tracts (group A = 48.16 ± 20.48 mm, group B = 60.28 ± 23.87 mm) and a decrease in MD (group A = 1.06 ± 0.23 × 10-3 mm2/s, group B = 0.82 ± 0.24 × 10-3 mm2/s) were observed with age along the entire spinal cord. Statistically significant increases have been shown in FA (p = 0.004, R2 = 0.57), tract density (p = 0.0004, R2 = 0.58), mean length of fiber tracts (p < 0.001, R2 = 0.5) and a significant decrease has been shown in MD (p = 0.002, R2 = 0.59) between group A and group B. Also, it has been shown DTI and DTT parameters vary along the spinal cord as a function of intervertebral disk and mid-vertebral body level.

Conclusion

This study provides an initial understanding of age related changes of DTI values as well as DTT metrics of the spinal cord. The results show significant differences in DTI and DTT parameters which may result from decreasing water content, myelination of fiber tracts, and the thickening diameter of fiber tracts during the maturation process. Consequently, when quantitative DTI and DTT of the spinal cord is undertaken in the pediatric population an age and level matched normative dataset should be used to accurately interpret the quantitative results.

Reduced Field of View Diffusion Tensor Imaging and Fiber Tractography of the Pediatric Cervical and Thoracic Spinal Cord Injury

The aim of this study is to assess the utility and effectiveness of diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) of the entire pediatric cervical and thoracic spinal cord toward discrimination of typically developing (TD) controls and subjects with spinal cord injury (SCI). A total of 43 pediatric subjects, including 23 TD subjects ranging in age from 6 to 16 years old and 20 subjects with SCI ranging in age from 7 to 16 years, were recruited and scanned using a 3.0 Tesla magnetic resonance scanner. Reduced field of view diffusion tensor images were acquired axially to cover the entire spinal cord across two slabs. For DTI analysis, motion correction was performed by coregistration of the diffusion-weighted images to the reference image (b0). Streamline deterministic tractography results were generated from the preprocessed data. DTI and DTT parameters of the whole cord, including fractional anisotropy (FA), mean diffusivity (MD), tract length, and tract density, were calculated, averaged across the whole spinal cord, and compared between the TD and SCI groups. Statistically significant decreases have been shown in FA (TD = 0.46 ± 0.11; SCI = 0.37 ± 0.09; p < 0.0001) and tract density (TD = 405.93 ± 243.84; SCI = 268.90 ± 270.34; p < 0.0001). However, the mean length of tracts and MD did not show significant differences. When investigating differences in DTI and DTT parameters above and below the injury site, it was shown that the FA and tract density in patients with cervical SCI decreased significantly in the thoracic region. An identical trend was observed in the cervical region for patients with thoracic SCI as well. When comparing TD and SCI subjects, FA and tract density were the most sensitive parameters in detecting functional changes of the spinal cord in chronic pediatric SCI. The results show that both DTI and DTT have the potential to be imaging biomarkers in the diagnosis of SCI.

Identification of ghost artifact using texture analysis in pediatric spinal cord diffusion tensor images

PURPOSE

Ghost artifacts are a major contributor to degradation of spinal cord diffusion tensor images. A multi-stage post-processing pipeline was designed, implemented and validated to automatically remove ghost artifacts arising from reduced field of view diffusion tensor imaging (DTI) of the pediatric spinal cord.

METHOD

A total of 12 pediatric subjects including 7 healthy subjects (mean age=11.34years) with no evidence of spinal cord injury or pathology and 5 patients (mean age=10.96years) with cervical spinal cord injury were studied. Ghost/true cords, labeled as region of interests (ROIs), in non-diffusion weighted b0 images were segmented automatically using mathematical morphological processing. Initially, 21 texture features were extracted from each segmented ROI including 5 first-order features based on the histogram of the image (mean, variance, skewness, kurtosis and entropy) and 16s-order feature vector elements, incorporating four statistical measures (contrast, correlation, homogeneity and energy) calculated from co-occurrence matrices in directions of 0°, 45°, 90° and 135°. Next, ten features with a high value of mutual information (MI) relative to the pre-defined target class and within the features were selected as final features which were input to a trained classifier (adaptive neuro-fuzzy interface system) to separate the true cord from the ghost cord.

RESULTS

The implemented pipeline was successfully able to separate the ghost artifacts from true cord structures. The results obtained from the classifier showed a sensitivity of 91%, specificity of 79%, and accuracy of 84% in separating the true cord from ghost artifacts.

CONCLUSION

The results show that the proposed method is promising for the automatic detection of ghost cords present in DTI images of the spinal cord. This step is crucial towards development of accurate, automatic DTI spinal cord post processing pipelines.

Diffusion Tensor Imaging of the Normal Cervical and Thoracic Pediatric Spinal Cord

BACKGROUND AND PURPOSE

DTI data of the normal healthy spinal cord in children are limited compared with adults and are typically focused on the cervical spinal cord. The purpose of this study was the following: to investigate the feasibility of obtaining repeatable DTI parameters along the entire cervical and thoracic spinal cord as a function of age in typically developing pediatric subjects; to analyze the DTI parameters among different transverse levels of the cervical and thoracic spinal cord; and to examine the sex differences in DTI parameters along the cervical and thoracic spinal cord.

MATERIALS AND METHODS

Twenty-two subjects underwent 2 identical scans by using a 3T MR imaging scanner. Axial diffusion tensor images were acquired by using 2 overlapping slabs to cover the cervical and thoracic spinal cord. After postprocessing, DTI parameters were calculated by using ROIs drawn on the whole cord along the entire spinal cord for both scans.

RESULTS

An increase in fractional anisotropy and a decrease in mean diffusivity, axial diffusivity, and radial diffusivity were observed with age along the entire spinal cord. Significantly lower fractional anisotropy and higher mean diffusivity values were observed in the lower cervical cord compared with the upper cervical cord. Axial diffusivity values in the cervical cord were higher compared with the thoracic cord. No statistically significant sex differences were observed for all DTI parameters. There was a moderate-to-strong repeatability for all DTI parameters.

CONCLUSIONS

This study provides an initial understanding of DTI values of the spinal cord relevant to age and sex and shows that obtaining repeatable DTI values of the entire cord in children is feasible.

Magnetic resonance spectroscopy for detection of choline kinase inhibition in the treatment of brain tumors

Abnormal choline metabolism is a hallmark of cancer and is associated with oncogenesis and tumor progression. Increased choline is consistently observed in both preclinical tumor models and in human brain tumors by proton magnetic resonance spectroscopy (MRS). Thus, inhibition of choline metabolism using specific choline kinase inhibitors such as MN58b may be a promising new strategy for treatment of brain tumors. We demonstrate the efficacy of MN58b in suppressing phosphocholine production in three brain tumor cell lines. In vivo MRS studies of rats with intracranial F98-derived brain tumors showed a significant decrease in tumor total choline concentration after treatment with MN58b. High-resolution MRS of tissue extracts confirmed that this decrease was due to a significant reduction in phosphocholine. Concomitantly, a significant increase in poly-unsaturated lipid resonances was also observed in treated tumors, indicating apoptotic cell death. MRI-based volume measurements demonstrated a significant growth arrest in the MN58b-treated tumors in comparison with saline-treated controls. Histologically, MN58b-treated tumors showed decreased cell density, as well as increased apoptotic cells. These results suggest that inhibition of choline kinase can be used as an adjuvant to chemotherapy in the treatment of brain tumors and that decreases in total choline observed by MRS can be used as an effective pharmacodynamic biomarker of treatment response.

The Corpus Callosum Wallerian Degeneration in the Unilateral Brain Tumors: Evaluation with Diffusion Tensor Imaging (DTI)

PURPOSE

The purpose of this study was to evaluate whether DTI could demonstrate the water diffusivity changes in the corpus callosum (CC), which were not visible on the morphologic imaging in patients with glioblastoma multiforme (GBM) and brain metastases with no midline CC infiltration.

MATERIALS AND METHODS

Twenty-seven patients with treatment naïve unilateral GBM and eleven patients with a solitary brain metastasis with no midline CC infiltration underwent DTI. Ten controls with normal brain MRI were also included. Based on the tensors, the principal diffusion directions, the anisotropy values, and the prior information about the diffusivity pattern in CC, a similarity measure was proposed. Subsequently, the CC was automatically divided into the Witelson subdivisions.

RESULTS

We observed significantly decreased fractional anisotropy values in all the regions of CC in the patients with GBM and metastases as compared to those in the controls. The mean diffusivity values showed a significant increase in all the regions of CC, except the splenium in patients with GBM and the isthmus in the patients with metastases, as compared to that in the controls respectively.

CONCLUSION

In conclusion, DTI is more sensitive than the morphologic MR imaging in the evaluation of changes within the CC, in brain tumours which do not infiltrate the CC. However, these changes of the DTI metrics in the CC are due to a Wallerian degeneration rather than a tumour infiltration, as was shown by our results, as similar changes were seen in the GBM as well as the non-infiltrating metastases patients.

Segmentation of corpus callosum using diffusion tensor imaging: validation in patients with glioblastoma

BACKGROUND

This paper presents a three-dimensional (3D) method for segmenting corpus callosum in normal subjects and brain cancer patients with glioblastoma.

METHODS

Nineteen patients with histologically confirmed treatment naïve glioblastoma and eleven normal control subjects underwent DTI on a 3T scanner. Based on the information inherent in diffusion tensors, a similarity measure was proposed and used in the proposed algorithm. In this algorithm, diffusion pattern of corpus callosum was used as prior information. Subsequently, corpus callosum was automatically divided into Witelson subdivisions. We simulated the potential rotation of corpus callosum under tumor pressure and studied the reproducibility of the proposed segmentation method in such cases.

RESULTS

Dice coefficients, estimated to compare automatic and manual segmentation results for Witelson subdivisions, ranged from 94% to 98% for control subjects and from 81% to 95% for tumor patients, illustrating closeness of automatic and manual segmentations. Studying the effect of corpus callosum rotation by different Euler angles showed that although segmentation results were more sensitive to azimuth and elevation than skew, rotations caused by brain tumors do not have major effects on the segmentation results.

CONCLUSIONS

The proposed method and similarity measure segment corpus callosum by propagating a hyper-surface inside the structure (resulting in high sensitivity), without penetrating into neighboring fiber bundles (resulting in high specificity).

Magnetic resonance imaging in central nervous system tuberculosis

Tuberculosis (TB) in any form is a devastating disease, which in its most severe form involves the central nervous system (CNS), with a high mortality and morbidity. Early diagnosis of CNS TB is necessary for appropriate treatment to reduce this morbidity and mortality. Routine diagnostic techniques involve culture and immunological tests of the tissue and biofluids, which are time-consuming and may delay definitive management. Noninvasive imaging modalities such as computed tomography (CT) scan and magnetic resonance imaging (MRI) are routinely used in the diagnosis of neurotuberculosis, with MRI offering greater inherent sensitivity and specificity than CT scan. In addition to conventional MRI imaging, magnetization transfer imaging, diffusion imaging, and proton magnetic resonance spectroscopy techniques are also being evaluated for better tissue characterization in CNS TB. The current article reviews the role of various MRI techniques in the diagnosis and management of CNS TB.

Permeability estimates in histopathology-proved treatment-induced necrosis using perfusion CT: can these add to other perfusion parameters in differentiating from recurrent/progressive tumors?

BACKGROUND AND PURPOSE

Differentiating treatment effects from RPT is a common yet challenging task in a busy neuro-oncologic practice. PS probably represents a different aspect of angiogenesis and vasculature and can provide additional physiologic information about recurrent/progressive enhancing lesions. The purpose of the study was to use PS measured by using PCT to differentiate TIN from RPT in patients with previously irradiated brain tumor who presented with a recurrent/progressive enhancing lesion.

MATERIALS AND METHODS

Seventy-two patients underwent PCT for assessment of a recurrent/progressive enhancing lesion from January 2006 to November 2009. Thirty-eight patients who underwent surgery and histopathologic diagnosis were included in this analysis. Perfusion parameters such as PS, CBV, CBF, and MTT were obtained from the enhancing lesion as well as from the NAWM.

RESULTS

Of 38 patients, 11 were diagnosed with pure TIN and 27 had RPT. Patients with TIN showed significantly lower mean PS values than those with RPT (1.8 ± 0.8 versus 3.6 ± 1.6 mL/100 g/min; P value=.001). The TIN group also showed lower rCBV (1.2 ± 0.3 versus 2.1 ± 0.7; P value<.001), lower rCBF (1.2 ± 0.5 versus 2.6 ± 1.7; P value=.004), and higher rMTT (1.4 ± 0.4 versus 1.0 ± 0.4; P value=.018) compared with the RPT group.

CONCLUSIONS

PCT and particularly PS can be used in patients with previously treated brain tumors to differentiate TIN from RPT. PS estimates can help increase the accuracy of PCT in differentiating these 2 entities.

Predicting survival in glioblastomas using diffusion tensor imaging metrics

PURPOSE

To retrospectively correlate various diffusion tensor imaging (DTI) metrics in patients with glioblastoma multiforme (GBM) with patient survival analysis and also degree of tumor proliferation index determined histologically.

MATERIALS AND METHODS

Thirty-four patients with histologically confirmed treatment naive GBMs underwent DTI on a 3.0 Tesla (T) scanner. Region-of-interest was placed on the whole lesion including the enhancing as well as nonenhancing component of the lesion to determine the various DTI metrics. Kaplan-Meier estimates and Cox proportional hazards regression methods were used to assess the relationship of DTI metrics (minimum and mean values) and Ki-67 with progression free survival (PFS). To study the relationship between DTI metrics and Ki-67, Pearson's correlation coefficient was computed.

RESULTS

Univariate analysis showed that patients with fractional anisotropy (FA)(mean) ≤ 0.2, apparent diffusion coefficient (ADC)(min) ≤ 0.6, planar anisotropy (CP)(min) ≤ 0.002, spherical anisotropy (CS)(mean) > 0.68 and Ki-67 > 0.3 had lower PFS rate. The multivariate analysis demonstrated that only CP(min) was the best predictor of survival in these patients, after adjusting for age, Karnofsky performance scale and extent of resection. No significant correlation between DTI metrics and Ki-67 were observed.

CONCLUSION

DTI metrics can be used as a sensitive and early indicator for PFS in patients with glioblastomas. This could be useful for treatment planning as high-grade gliomas with lower ADC(min), FA(mean), CP(min), and higher CS(mean) values may be treated more aggressively.

Quantification of age- and gender-related changes in diffusion tensor imaging indices in deep grey matter of the normal human brain

This study aimed to demonstrate age-related and gender-related changes in diffusion tensor imaging (DTI) indices of deep grey matter (GM) nuclei of the normal human brain. DTI was performed on 142 subjects (age: 10-52 years). Regions of interest were placed on the caudate nucleus (CN), putamen, globus pallidus, frontal white matter (WM), occipital WM, anterior and posterior limb of internal capsule, genu of the corpus callosum and splenium in all participants. The quadratic regression model was used to describe age-related and gender-related changes in DTI indices for GM and WM. We observed increased fractional anisotropy (FA) values with age up to adulthood in GM, and a rise up to the third decade of life followed by a decrease in FA for WM. We observed higher FA values in males compared to females in CN and all WM regions. Decreased mean diffusivity with age was observed in GM and WM irrespective of gender. This normative data may be valuable in the diagnosis of neurodegenerative diseases.

Comparative evaluation of corpus callosum DTI metrics in acute mild and moderate traumatic brain injury: its correlation with neuropsychometric tests

PRIMARY OBJECTIVE

To look for differences in vulnerability of corpus callosum (CC) in patients of mild and moderate traumatic brain injury (TBI) in the acute stage using quantitative diffusion tensor imaging (DTI) and to correlate these with neuropsychometric tests (NPT) done at 6 months post-injury. RESEARCH DESIGN, METHODS AND PROCEDURES: Conventional MRI, DTI and NPT were performed on 83 patients (moderate TBI, n = 57; mild TBI, n = 26) within 5-14 days after TBI. Thirty-three age- and sex-matched healthy controls were also included for comparison.

RESULTS

Significantly decreased fractional anisotropy (FA) in genu and splenium; significantly increased radial diffusivity (RD) values in genu, midbody and splenium with significant increase in mean diffusivity (MD) and a decrease in axial diffusivity (AD) only in genu, respectively, in patients with moderate TBI compared to healthy controls were observed. However, in moderate TBI, significantly decreased FA was found only in genu compared to mild TBI. Moderate TBI showed poor NPT scores compared to mild TBI, but this did not reach statistical significance.

CONCLUSIONS

It is concluded that DTI abnormalities in the regions of CC were more in patients with moderate TBI compared to mild TBI and this was associated with relatively poor neuropsychological outcome 6 months post-injury.

A diffusion tensor imaging study of deep gray and white matter brain maturation differences between patients with spina bifida cystica and healthy controls

The aim of this study was to use diffusion tensor imaging (DTI) to identify differences in the maturation of deep gray matter (GM) and white matter (WM) between patients with spina bifida cystica (SBC) (n=29) with normal-appearing brains on conventional MRI, and age-matched and sex-matched healthy control participants (n=33). Changes in DTI metrics were calculated using a log-linear regression model. We observed increasing fractional anisotropy (FA) with age in the occipital, fornix, cingulum and middle cerebellar peduncles and decreasing FA with age in the genu and splenium of the corpus callosum (CC) and caudate nuclei in patients compared to controls. Increasing FA values in some of the WM structures probably represent faulty WM maturation, whereas decreasing FA values in the CC represents changes secondary to the affected WM fibers contributing to the CC. DTI changes in deep GM and WM in the absence of any abnormality on conventional MRI might provide the basis for cognitive decline in these patients.

Correlation of DTI metrics in the wall and cavity of brain abscess with histology and immunohistochemistry

Diffusion tensor imaging (DTI) was performed in eight patients with brain abscess (BA). The aim of this study was to see the difference in the relationship between intercellular cell adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) expression and DTI metrics measured in vivo in the wall and cavity of BA and its possible explanation vis-à-vis histology and immunohistochemistry. Neuroinflammatory molecules (NMs) were quantified from BA cavity aspirate of the patients and quantitative immunohistochemical analysis was performed for ICAM-1 and LFA-1 in the BA wall, showing maximal positive staining and correlated with DTI metrics. The fractional anisotropy (FA) significantly increased while mean diffusivity and spherical anisotropy significantly decreased in the BA wall compared to the BA cavity. In the BA wall, FA and linear anisotropy (CL) showed a significant positive correlation with ICAM-1 and LFA-1 expression whereas FA and planar anisotropy positively correlated with NMs quantified from aspirated pus respectively. Higher FA values in the BA wall compared to BA cavity, even when ICAM-1 and LFA-1 were expressed only in the macrophages and not in the collagen fibers, suggests that a combination of both concentric layers of collagen fibers as well as neutrophils and macrophages provide structural orientation and are responsible for increased FA. In the BA wall, increased CL was found compared to the cavity, indicating the presence of concentrically laid collagen fibers responsible for the diffusion of water molecules in the direction parallel to the collagen fibers. We conclude that in the BA, different mechanisms are operative for the changes in the DTI metrics in the wall and cavity; these conclusions are validated by histology and immunohistochemistry.

Serial changes in diffusion tensor imaging metrics of corpus callosum in moderate traumatic brain injury patients and their correlation with neuropsychometric tests: a 2-year follow-up study

OBJECTIVE

To assess longitudinally the severity of diffuse axonal injury in the corpus callosum in patients with moderate traumatic brain injury (TBI) through quantitative diffusion tensor imaging and to correlate these changes with neuropsychometric tests (NPT) at 6 and 24 months after injury.

DESIGN

Prospective longitudinal study.

PARTICIPANTS

Sixteen patients with TBI and 17 age/sex-matched healthy controls.

METHODS

Patients underwent magnetic resonance imaging at 3 time points: within 2 weeks (range = 5-14 days), 6 months, and 24 months after injury. NPT could be performed only at 6 and 24 months.

RESULTS

In patients with TBI, a significant increase in fractional anisotropy (FA) values in genu as well as an insignificant decrease in radial diffusivity (RD) and mean diffusivity values in genu and splenium were observed over time, respectively. FA, RD, and mean diffusivity values continued to be abnormal in patients compared with controls at the end of 2 years. Although some NPT scores improved over time in these patients, these were still significantly impaired compared with controls.

CONCLUSIONS

FA and RD indices appear to be surrogate markers of microstructural alterations in patients over time and correlate significantly with some of the NPT scores. The recovery in these indices associated with recovery in neurocognitive deficits suggests that these indices may be used as an objective marker for residual injury in these patients.

Brain MR imaging and 1H-MR spectroscopy changes in patients with extrahepatic portal vein obstruction from early childhood to adulthood

BACKGROUND AND PURPOSE

MR imaging and (1)H-MR spectroscopy changes are well reported in cirrhotic patients, whereas they are inadequately reported in EHPVO. The aim of this study was to investigate age-related changes in brain MR imaging and metabolite profile in EHPVO with and without MHE and to explore any correlation of imaging and (1)H-MR spectroscopy parameters with blood ammonia.

MATERIALS AND METHODS

Sixty-three patients with EHPVO (children, 7-12 years [n = 22], adolescents, 13-18 years [n = 15] and adults, 19-41 years [n = 26]) and 47 healthy age/sex-matched volunteers were studied. Neuropsychological tests, MR imaging, (1)H-MR spectroscopy, and blood ammonia estimation were performed in all subjects.

RESULTS

Of 63 EHPVO patients, 25 (40%) who had MHE showed significantly increased MD, Glx, and blood ammonia in all 3 age groups; however, myo-inositol was significantly lower only in adults when compared with controls. MD positively correlated with blood ammonia and Glx in all age groups. Brain choline levels were normal in all patients with different age groups.

CONCLUSIONS

Increases in brain MD, Glx, and blood ammonia were associated with MHE in all age groups. Normal brain choline in EHPVO signifies healthy liver and may serve as a diagnostic marker for its differentiation from cirrhosis-induced encephalopathy. Significant decrease of myo-inositol in adults is probably due to cellular osmoregulation secondary to long-standing hyperammonemia.

High performance tangential flow filtration

Conventional tangential flow filtration (TFF) has traditionally been limited to separation of solutes that differ by about ten-fold in size. Wide pore-size distributions, membrane fouling, and concentration polarization phenomena have commonly been cited as reasons for this limitation. The use of TFF in the biotechnology industry has therefore been restricted to cell-protein, virus-protein, and protein-buffer separations. A multi-disciplinary team with industrial and academic members was formed to overcome these limitations and enable protein-protein separations using High Performance TFF (HPTFF) systems. Pore-size distributions have been improved with the development of new membrane formulation and casting techniques. Membrane fouling has been controlled by operating in the transmembrane pressure-dependent regime of the filtrate flux curve and by carefully controlling fluid dynamic start-up conditions. Concentration polarization was exploited to enhance, rather than limit, the resolution of solutes. Concentration polarization has also been controlled by operating a co-current filtrate stream that maintains transmembrane pressure constant along the length of the TFF module. High yields and purification factors were obtained even with small differences in protein sieving. IgG-BSA and BSA monomer-oligomer mixtures have successfully been separated with these systems. HPTFF technology provides a competitive purification tool to complement chromatographic processing of proteins.

Protein fractionation using electrostatic interactions in membranel filtration

One of the critical factors limiting the development of membrane systems for protein fractionation has been the poor selectivity that has generally been obtained with these membrane devices. We have demonstrated that it is possible to dramatically improve the selectivity of available membrane systems by exploiting the different electrostatic interactions between the two proteins and the membrane. The separation factor for the albumin-hemoglobin system could be increased to more than 70 simply by reducing the salt concentration and adjusting the pH to around 7 (near the isoelectric point of hemoglobin). This very high selectivity was a direct result of the strong electrostatic exclusion of the charged albumin from the membrane pores under these conditions. This high selectivity makes it possible to very effectively separate these albumin-hemoglobin mixtures using membrane filtration, and this was demonstrated experimentally using both a simple batch filtration process and a continuous diafiltration system. The hemoglobin recovery in the diafiltration experiment was greater than 70% after a 3-diavolume filtration, with the Hb purification factor being around 100 under these conditions. These results clearly demonstrate the potential of membrane systems for the fractionation of proteins even with very similar molecular weights.

Understanding development and lateralization of major cerebral fiber bundles in pediatric population through quantitative diffusion tensor tractography

Region of interest based morphometric diffusion tensor imaging analysis, has been used extensively for the assessment of age-related changes in human brain, is limited to two dimensions and does not reflect the whole fiber bundle; however, diffusion tensor tractography (DTT) offers an overall view of individual fiber bundle in three-dimensional spaces. Quantitative DTT was performed on 51 healthy subjects of pediatric age range and young adults to compare age-related fractional anisotropy (FA) changes in corpus callosum, sensory and motor pathways, limbic tracts [cingulum (CNG) and fornix (Fx)], and superior and inferior longitudinal fascicules. In corpus callosum, inferior longitudinal fascicules, limbic tracts (CNG and Fx), sensory pathways, and motor pathways, an initial sharp increase in FA was observed up to the age of 2 y followed by a gradual increase up to 21 y. In superior longitudinal fascicules, sharp increase in FA was observed up to 3 y followed by a gradual increase. The FA value of the left CNG (p = 0.01, sign test) was observed to be significantly greater than that of the right CNG. We conclude that white matter fiber tracts mature with age and can be assessed by using DTT that may greatly improve our understanding of the human brain development.

Correlation of diffusion tensor imaging with histology in the developing human frontal cerebrum

Transient early cerebral laminar organization resulting from normal developmental events has been revealed in human beings through histology and imaging studies. DTI studies have postulated that the fractional anisotropy (FA)-based differentiation of different laminar structures reflects both differing cellular density over the glial fibers and fiber alignment in respective regions. The aim of this study was to correlate FA values in these transient zones with histology. Brain DTI was performed on 50 freshly aborted human fetuses with gestational ages (GA) ranging from 12 to 42 weeks. Regions of interest were placed on the cortical plate, subplate, intermediate and germinal matrix (GMx) zones of the frontal lobe to quantify FA values. Glial fibrillary acidic protein (GFAP), neurofilament (NF) and neuron-specific enolase (NSE) immunohistochemical analyses were performed for the cortical plate, intermediate zone and GMx. In the cortical plate, a significant positive correlation was observed between FA values and percentage area of GFAP expression in fetuses <or=28 weeks of GA (r = 0.56, p = 0.01). FA values showed a significant positive correlation with the percentage area of NF expression in the intermediate zone (r = 0.54, p = 0.05). A significant positive correlation was also observed between FA and the number of NSE-positive cells per mm(2) in the GMx (r = 0.76, p < 0.01) and subplate (r = 0.59, p = 0.03) zones. The results of our study suggest that the FA can be used as noninvasive marker of neurodevelopmental events in the frontal lobe of human fetal brain.

Comparative evaluation of the cerebral and cerebellar white matter development in pediatric age group using quantitative diffusion tensor imaging

Age-dependent changes in the normal cerebral white matter have been reported; however, there is no study on normal cerebellar white matter maturation in developing brain using diffusion tensor imaging (DTI). We performed DTI in 21 children who had normal neurological assessment along with no evidence of any abnormality on imaging. The aim of this study was to compare the age-related changes in fractional anisotropy (FA) and mean diffusivity (MD) quantified from cerebral white matter (splenium and genu of the corpus callosum and posterior limb of the internal capsule) and cerebellar white matter (middle cerebellar peduncles, superior cerebellar peduncles, and inferior cerebellar peduncles) regions in healthy children ranging in age from birth to 132 months. Log-linear regression model showed best fit to describe the age-related changes in FA and MD both for cerebral and cerebellar white matter. In cerebral white matter, an initial sharp increase in FA was observed up to the age of 24 months followed by a gradual increase up to 132 months. In cerebellar white matter, sharp increase in FA was observed up to 36 months, which then followed a gradual increase. However, MD showed a sharp decrease in cerebral white matter up to 24 months followed by a more gradual decrease thereafter, while in cerebellar white matter after an initial decrease (6 months), it followed a stable pattern. This study provides normative database of brain white matter development from neonates to childhood. This quantitative information may be useful for assessing brain maturation in patients with developmental delay of the cerebral and cerebellar white matter.

Region-specific maturation of cerebral cortex in human fetal brain: diffusion tensor imaging and histology

INTRODUCTION

In this study, diffusion tensor imaging (DTI) and glial fibrillary acidic protein (GFAP) immunohistochemical analysis in different cortical regions in fetal brains at different gestational age (GA) were performed.

METHODS

DTI was performed on 50 freshly aborted fetal brains with GA ranging from 12 to 42 weeks to compare age-related fractional anisotropy (FA) changes in different cerebral cortical regions that include frontal, parietal, occipital, and temporal lobes at the level of thalami. GFAP immunostaining was performed and the percentage of GFAP-positive areas was quantified.

RESULTS

The cortical FA values in the frontal lobe peaked at around 26 weeks of GA, occipital and temporal lobes at around 20 weeks, and parietal lobe at around 23 weeks. A significant, but modest, positive correlation (r = 0.31, p = 0.02) was observed between cortical FA values and percentage area of GFAP expression in cortical region around the time period during which the migrational events are at its peak, i.e., GA < or = 28 weeks for frontal cortical region and GA < or = 22 weeks for rest of the lobes.

CONCLUSIONS

The DTI-derived FA quantification with its GFAP immunohistologic correlation in cortical regions of the various lobes of the cerebral hemispheres supports region-specific migrational and maturational events in human fetal brain.

Retrograde Wallerian degeneration of cranial corticospinal tracts in cervical spinal cord injury patients using diffusion tensor imaging

Diffusion tensor imaging (DTI) has the potential to reveal disruption of white matter microstructure in chronically injured spinal cords. We quantified fractional anisotropy (FA) and mean diffusivity (MD) to demonstrate retrograde Wallerian degeneration (WD) of cranial corticospinal tract (CST) in cervical spinal cord injury (SCI). Twenty-two patients with complete cervical SCI in the chronic stage were studied with DTI along with 13 healthy controls. Mean FA and MD values were computed for midbrain, pons, medulla, posterior limb of internal capsule, and corona radiata. Significant reduction in the mean FA and increase in MD was observed in the cranial CST in patients with SCI compared with controls, suggesting retrograde WD. Statistically significant inverse FA and MD changes were noted in corona radiata, indicating some restoration of spared white matter tracts. Temporal changes in the DTI metrics suggest progressing degeneration in different regions of CST. These spatiotemporal changes in DTI metrics suggest continued WD in injured fibers along with simultaneous reorganization of spared white matter fibers, which may contribute to changing neurological status in chronic SCI patients.

DTI derived indices correlate with immunohistochemistry obtained matrix metalloproteinase (MMP-9) expression in cellular fraction of brain tuberculoma

We performed in vivo diffusion tensor imaging (DTI) in a total of 33 patients with brain tuberculomas (BT). Thirteen of them had surgical excision of the lesion as it was clinically indicated, and in these samples matrix metalloproteinase-9 (MMP-9) expression was quantified. We correlated the results of DTI indices like fractional anisotropy (FA), mean diffusivity (MD), linear anisotropy (CL), planar anisotropy (CP) and spherical anisotropy (CS) with MMP-9 expression. In addition, the remaining 20 patients had serial DTI studies while on specific anti-tuberculous drug therapy and DTI indices in these patients were quantified. The FA, CL and CP significantly decreased while MD and CS significantly increased in BT compared to normal white matter. The FA, CL and CP showed negative correlation with MMP-9 while CS correlated positively. In serial follow-up studies in 20 patients FA, CL and CP showed significant increase while CS decreased significantly over time. We conclude that DTI indices show strong correlation with MMP-9 and these may be used as a surrogate marker of MMP-9 expression in BT. In addition, these indices may be of value in assessing the therapeutic response in patients with BT who are treated only with specific anti-tuberculous drugs.

Diffusion tensor imaging in the developing human cerebellum with histologic correlation

Diffusion tensor imaging was performed on 24 freshly aborted human fetuses with gestational age ranging from 20 to 37 weeks to observe age-related fractional anisotropy changes in cerebellar cortex and cerebellar white matter. Quantitative immunohistochemical analysis was performed for glial fibrillary acidic protein in each fetus molecular layer of cerebellar cortex and myelin basic protein expression was quantified in myelinated areas of the middle cerebellar peduncles. The cerebellar cortical fractional anisotropy reached its peak value at 28 weeks, and then decreased gradually until 37 weeks. The time course of glial fibrillary acidic protein expression paralleled that of fractional anisotropy in the cerebellar cortex from 20 weeks of gestation upto the gestational age at which the fractional anisotropy reached its peak value (28 weeks). In the middle cerebellar peduncles, the fractional anisotropy increased continuously upto 37 weeks of gestational age and showed a significant positive correlation with myelin basic protein immunostained fibers. The fractional anisotropy quantification can be used to assess the migrational and maturation changes during the development of the human fetal cerebellum supported by the immunohistochemical analysis.

Evaluation of mannitol effect in patients with acute hepatic failure and acute-on-chronic liver failure using conventional MRI, diffusion tensor imaging and in-vivo proton MR spectroscopy

AIM: To evaluate the effect of an intravenous bolus of mannitol in altering brain metabolites, brain water content, brain parenchyma volume, cerebrospinal fluid (CSF) volume and clinical signs in controls and in patients with acute liver failure (ALF) and acute-on-chronic liver failure (ACLF), by comparing changes in conventional magnetic resonance imaging (MRI), in vivo proton magnetic resonance spectroscopy (PMRS) and diffusion tensor imaging (DTI) before and after its infusion.

METHODS: Five patients each with ALF and ACLF in grade 3 or 4 hepatic encephalopathy and with clinical signs of raised intracranial pressure were studied along with five healthy volunteers. After baseline MRI, an intravenous bolus of 20% mannitol solution was given over 10 min in controls as well as in patients with ALF and ACLF. Repeat MRI for the same position was acquired 30 min after completing the mannitol injection.

RESULTS: No statistically significant difference was observed between controls and patients with ALF and ACLF in metabolite ratios, DTI metrics and brain volume or CSF volume following 45 min of mannitol infusion. There was no change in clinical status at the end of post-mannitol imaging.

CONCLUSION: The osmotic effect of mannitol did not result in significant reduction of brain water content, alteration in metabolite ratios or any change in the clinical status of these patients during or within 45 min of mannitol infusion.

Cerebral diffusion tensor imaging and in vivo proton magnetic resonance spectroscopy in patients with fulminant hepatic failure

BACKGROUND AND AIM

Cerebral edema is a major complication in patients with fulminant hepatic failure (FHF). The aim of this study was to evaluate the metabolite alterations and cerebral edema in patients with FHF using in vivo proton magnetic resonance spectroscopy (MRS) and diffusion tensor imaging, and to look for its reversibility in survivors.

METHODS

Ten FHF patients along with 10 controls were studied. Five of the 10 patients who recovered had a repeat imaging after three weeks. N-acetylaspartate, choline (Cho), glutamine (Gln), glutamine/glutamate (Glx), and myoinositol ratios were calculated with respect to creatine (Cr). Mean diffusivity (MD) and fractional anisotropy (FA) were calculated in different brain regions.

RESULTS

Patients exhibited significantly increased Gln/Cr and Glx/Cr, and reduced Cho/Cr ratios, compared to controls. In the follow-up study, all metabolite ratios were normalized except Glx/Cr. Significantly decreased Cho/Cr were observed in deceased patients compared to controls. In patients, significantly decreased MD and FA values were observed in most topographical locations of the brain compared to controls. MD and FA values showed insignificant increase in the follow-up study compared to their first study.

CONCLUSIONS

We conclude that the Cho/Cr ratio appears to be an in vivo marker of prognosis in FHF. Decreased MD values suggest predominant cytotoxic edema may be present. Persistence of imaging and MRS abnormalities at three weeks' clinical recovery suggests that metabolic recovery may take longer than clinical recovery in FHF patients.

Assessment of therapeutic response in brain tuberculomas using serial dynamic contrast-enhanced MRI

AIM

To assess the most useful dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) index in the evaluation of the therapeutic response in brain tuberculoma (BT) patients.

SUBJECTS AND METHODS

Twenty-three patients with 25 BT lesions were serially evaluated using DCE MRI. All lesions were classified into two groups: group I (n=15) included patients who showed clinical, as well as imaging, improvement; and group II (n=10) included patients with either clinical or radiological deterioration. The group I and group II lesions were examined for up to 12 months at 4 monthly intervals. However, the lesions in five patients of group II were excised following clinical deterioration after 4 months of therapy. The perfusion indices, i.e., relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), permeability (k(trans)), and leakage (v(e)), were quantified at each time point. The cellular, necrotic, and total volumes of lesion, together with the oedema volume, were also calculated.

RESULTS

All patients in group I and three in group II showed a significant decrease in all perfusion indices, together with the oedema volume, after 1 year. In these three patients in group II, increase in rCBV was associated with increased cellular volume fraction whereas the k(trans), v(e), and oedema volume decreased significantly after 4 months. In five patients in group II who underwent excision of the lesion after 4 months of therapy due to clinical deterioration, the decrease in rCBV was associated with significant increase in k(trans) and oedema volume without any significant change in lesion volume. The rCBV correlated significantly with the cellular volume, whereas k(trans) showed a significant correlation with the v(e) and oedema volume at each time point.

CONCLUSION

In BT, changes in k(trans) and oedema volume are associated with a therapeutic response at 4 months, even when there is a paradoxical increase in the lesion volume.

MR demonstration of complete cerebellar and corpus callosum agenesis

Complete cerebellar agenesis is a very rare entity, which occurs during the early period of embryogenesis and is usually associated with severe motor dysfunction. We report a case of complete cerebellar agenesis with complete corpus callosum agenesis diagnosed on magnetic resonance imaging (MRI). These anomalies were also associated with rudimentary pons.

Focal Wallerian degeneration of the corpus callosum in large middle cerebral artery stroke: Serial diffusion tensor imaging

PURPOSE

To detect lesion-related focal Wallerian degeneration (WD) changes in different segments of the corpus callosum (CC) in patients with large middle cerebral arterial (MCA) territory stroke using diffusion tensor imaging (DTI).

MATERIALS AND METHODS

Eight patients underwent DTI scans at three different time points: six to eight weeks, 10-12 weeks, and beyond six months of stroke onset. Eight healthy age-matched controls were also scanned using the same protocol at three different time points. Region-of-interest (ROI) analysis was performed on seven segments of the CC to determine the fractional anisotropy (FA), mean diffusivity (MD), and corresponding callosal cross-sectional areas.

RESULTS

On repeated-measures analysis of variance (ANOVA), a significant reduction in the FA values was observed from the first to the third study compared to controls, reflecting temporal degeneration in the rostrum, genu, rostral body, anterior midbody, and splenium of the CC. However, a significant temporal elevation in MD values was observed in only the rostral body and anterior midbody of the CC. This was associated with a significant region-specific reduction in the cross-sectional areas at time points beyond six months, and appears to be consistent with the loss of callosal structural components due to interruption of the cortico-callosal fibers secondary to WD.

CONCLUSION

These results indicate that cortico-callosal topographical changes exhibit a significant temporal decline in observed FA values that is suggestive of cortico-callosal WD in patients with large MCA territory stroke.

Diffusion tensor imaging in late posttraumatic epilepsy

PURPOSE

The main objective of this study was to use diffusion tensor imaging (DTI) to search and quantify the extent of abnormality beyond the obvious lesions seen on the T2 and fluid-attenuation inversion recovery (FLAIR) magnetic resonance images in patients with chronic traumatic brain injury (TBI) with and without epilepsy.

METHODS

DTI was performed on 23 chronic TBI patients (with late posttraumatic epilepsy, n=14; without epilepsy, n=9) and 11 age-matched controls. The ratios of fractional anisotropy (FA) and mean diffusivity (MD) between the regions of interest beyond the T2/FLAIR-visualized abnormality and the corresponding contralateral normal-appearing region were calculated. FA and MD ratios were compared for relative changes in these parameters among the TBI subjects with and without epilepsy and controls. Tissue volumes exhibiting abnormalities on DTI also were measured in these patients.

RESULTS

The mean regional FA ratio was significantly lower, whereas the mean regional MD value was higher in patients with TBI compared with controls. The mean regional FA ratio was significantly lower in TBI patients with epilepsy (0.57+/-0.059) than in those without epilepsy (0.68+/-0.039). Although the regional MD ratio was higher in TBI patients with epilepsy (1.15+/-0.140) relative to those without epilepsy (1.09+/-0.141), the difference did not reach statistical significance. The tissue volume with low FA value also was found to be higher in TBI patients with epilepsy than without.

CONCLUSIONS

Severity of injury as predicted by the DTI-derived increased volume of microstructure damage is associated with delayed posttraumatic epilepsy in TBI patients. These findings could be valuable in predicting epileptogenesis in patients with chronic TBI.

Immune response towards lipid peroxidation products as a predictor of progression of non-alcoholic fatty liver disease to advanced fibrosis

AIMS

Factors responsible for the progression of non-alcoholic fatty liver disease (NAFLD) to more severe liver injury are poorly understood. In the present study, we investigated the association between immune reactions triggered by oxidative stress and stage of NAFLD.

METHODS

Titres of IgG against human serum albumin adducted with malondialdehyde (MDA-HSA) or arachidonic acid hydroperoxide (AAHP) and against oxidised cardiolipin (Ox-CL) were measured in 167 NAFLD patients with steatosis only (n = 79), steatohepatitis (n = 74), or steatosis plus cirrhosis (n = 14), and in 59 age and sex matched controls.

RESULTS

Circulating IgG against lipid peroxidation products was significantly higher (p<0.001) in NAFLD patients than in controls. Oxidative stress dependent immune responses were not associated with obesity, type 2 diabetes, or with serum cholesterol, ferritin, or aminotransferase levels. Titres of lipid peroxidation related antibodies were also independent of the extent of steatosis and were similarly distributed in patients with and without necroinflammation. In contrast, the same antibodies were significantly increased in patients with advanced fibrosis or cirrhosis. Logistic regression analysis confirmed that anti-MDA antibodies were independently associated with progression of NALFD and that NAFLD patients with titres of anti-MDA-HSA antibodies above the control threshold value had a threefold (relative risk 2.82 (95% confidence interval 1.35-5.90); p = 0.007) higher risk of having advanced fibrosis/cirrhosis than patients whose antibody titres were within the control range.

CONCLUSIONS

These results indicate that the presence of immune reactions triggered by oxidative stress can be an independent predictor of progression of NAFLD to advanced fibrosis.

Biological correlates of diffusivity in brain abscess

Restricted diffusion in brain abscess is assumed to be due to a combination of inflammatory cells, necrotic debris, viscosity, and macromolecules present in the pus. We performed diffusion-weighted imaging (DWI) on 41 patients with proven brain abscesses (36 pyogenic and five tuberculous), and correlated the apparent diffusion coefficient (ADC) from the abscess cavity with viable cell density, viscosity, and extracellular-protein content quantified from the pus. On the basis of the correlation between cell density and ADC in animal tumor models and human tumors in the literature, we assumed that the restricted ADC represents the cellular portion in the abscess cavity. We calculated restricted and unrestricted lesion volumes, and modeled cell density over the restricted area with viable cell density per mm(3) obtained from the pus. The mean restricted ADC in the cavity (0.65 +/- 0.01 x 10(-3) mm(2)/s) correlated inversely with restricted cell density in both the pyogenic (r = -0.90, P = <0.05) and tuberculous (0.60 +/- 0.04 x 10(-3) mm(2)/s, r = -0.94, P = <0.05) abscesses. We conclude that viable cell density is the main biological parameter responsible for restricted diffusion in brain abscess, and it is not influenced by the etiological agents responsible for its causation.

Regulation of butyrate uptake in Caco-2 cells by phorbol 12-myristate 13-acetate

Butyrate and the other short-chain fatty acids (SCFAs) are the most abundant anions in the colonic lumen. Also, butyrate is the preferred energy source for colonocytes and has been shown to regulate colonic electrolyte and fluid absorption. Previous studies from our group have demonstrated that the HCO(3)(-)/SCFA(-) anion exchange process is one of the major mechanisms of butyrate transport across the purified human colonic apical membrane vesicles and the apical membrane of human colonic adenocarcinoma cell line Caco-2 and have suggested that it is mainly mediated via monocarboxylate transporter-1 (MCT-1) isoform. However, little is known regarding the regulation of SCFA transport by various hormones and signal transduction pathways. Therefore, the present studies were undertaken to examine whether hydrocortisone and phorbol 12-myristate 13-acetate (PMA) are involved in a possible regulation of the butyrate/anion exchange process in Caco-2 cells. The butyrate/anion exchange process was assessed by measuring a pH-driven [(14)C]butyrate uptake in Caco-2 cells. Our results demonstrated that 24-h incubation with PMA (1 microM) significantly increased [(14)C]butyrate uptake compared with incubation with 4alphaPMA (inactive form). In contrast, incubation with hydrocortisone had no significant effect on butyrate uptake in Caco-2 cells compared with vehicle (ethanol) alone. Induction of butyrate uptake by PMA appeared to be via an increase in the maximum velocity (V(max)) of the transport process with no significant changes in the K(m) of the transporter for butyrate. Parallel to the increase in the V(max) of [(14)C]butyrate uptake, the MCT-1 protein level was also increased in response to PMA incubation. Our studies demonstrated that the butyrate/anion exchange was increased in response to PMA treatment along with the induction in the level of MCT-1 expression in Caco-2 cells.