Diffusion Tensor Imaging Protocol Research Articles

MO‐G‐18C‐09: Thermal Characterization and Initial Imaging Results From the Diffusive Quantitative Imaging Phantom (DQIP)

Purpose:The goals of this project were a) to characterize thermal relaxation of the phantom and b) to demonstrate correlations between temperature, signal‐to‐noise ratio (SNR) and diffusion tensor imaging (DTI) metrics. A site‐based clinical DTI protocol was used in this study. The hypothesis is that thermal stability of the phantom will be adequate such that temperature monitoring during a scan may be neglected.Methods:The Diffusive Quantitative Imaging Phantom (DQIP) is a prototype phantom consisting of fifteen cylindrical compartments containing capillary arrays, encased in a larger compartment. Thermal stability of the phantom was established using a cork container and a Peltier incubator. After the phantom was cooled or heated, thermal relaxation was measured as the phantom was allowed to return to room temperature, with and without cork. A clinical‐grade DTI protocol was used to collect scan and temperaturedependent data from the phantom over ten days. SNR and thermal dependences of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were characterized by scanning a heated or cooled phantom over several hours.Results:The phantom temperature was stable within ±0.08°C/hour per degree difference from the scan room using the cork enclosure, compared to ±0.3°C/hour per degree difference without the cork enclosure. During scanning, temperature variation was ∼ 0.1°C/hour. The dependences of (FA, ADC) on (SNR, temperature) were characterized for the heating and cooling experiments. However, for the range of temperature (1.2°C) and SNR (max: ±77%) variations in a particular compartment over all daily measurements, no significant improvement in total variation was achieved after regressing out temperature and SNR, although one compartment showed significant decline after regression.Conclusion:Thermal stability of the DQIP phantom and incubator system is sufficient for neglecting temperature variations during scanning. For a standard clinical protocol, SNR dependence of FA and ADC are not sufficient to warrant correction.Schott Glass North America and The Phantom Laboratory have donated materials and personnel time to this project.

In vivo diffusion spectrum imaging of non-human primate brain: initial experience in transcallosal fiber examination.

In comparison with conventional diffusion tensor imaging (DTI) technique, diffusion spectrum imaging (DSI) allows for delineating crossing and touching fibers in the brain and has been explored in clinical and preclinical studies. Non-human primates (NHPs) resemble most aspects of human and are widely employed in various neuroscience researches and pharmaceutical development. In the present study, a parallel imaging-based DSI protocol was implemented for in vivo fiber tracking of macaque monkey brains on a 3.0 T clinical scanner. Transcallosal fiber tracts of adult macaque brains were examined with DSI and compared with those from a a conventional DTI protocol. The results demonstrate that DSI can reveal the transcallosal fiber bundles much more extensively than the conventional DTI. The preliminary results suggest that DSI may provide a feasible and robust approach for characterizing the fiber pathways in various disease models of NHPs.

Diffusion tensor imaging of the sural nerve in normal controls

ObjectiveTo develop a diffusion tensor imaging (DTI) protocol for assessing the sural nerve in healthy subjects. MethodsSural nerves in 25 controls were imaged using DTI at 3T with 6, 15, and 32 gradient directions. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were computed from nerve regions of interest co-registered with T2-weighted images. ResultsCoronal images with 0.5(RL)×2.0(FH)×0.5(AP)mm3 resolution successfully localized the sural nerve. FA maps showed less variability with 32 directions (0.559±0.071) compared to 15(0.590±0.080) and 6(0.659±0.109). ConclusionsOur DTI protocol was effective in imaging sural nerves in controls to establish normative FA/ADC, with potential to be used non-invasively in diseased nerves of patients.

Distinguishing and quantification of the human visual pathways using high-spatial-resolution diffusion tensor tractography

Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high-spatial-resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways. Five healthy males, age range 24–37years, were studied after approval of the institutional review board (IRB) at The University of Texas Health Science Center at Houston. We acquired diffusion tensor imaging (DTI) data with 1-mm slice thickness on a 3.0-Tesla clinical MRI scanner and analyzed the data using DTT with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high-spatial-resolution DTI protocol with FACT algorithm, we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm, optic tract, optic radiations free of contamination from neighboring white matter tracts.

Microanisotropy imaging: quantification of microscopic diffusion anisotropy and orientational order parameter by diffusion MRI with magic-angle spinning of the q-vector

Diffusion tensor imaging (DTI) is the method of choice for non-invasive investigations of the structure of human brain white matter. The results are conventionally reported as maps of the fractional anisotropy (FA), which is a parameter related to microstructural features such as axon density, diameter, and myelination. The interpretation of FA in terms of microstructure becomes ambiguous when there is a distribution of axon orientations within the image voxel. In this paper, we propose a procedure for resolving this ambiguity by determining a new parameter, the microscopic fractional anisotropy (µFA), which corresponds to the FA without the confounding influence of orientation dispersion. In addition, we suggest a method for measuring the orientational order parameter (OP) for the anisotropic objects. The experimental protocol is capitalizing on a recently developed diffusion NMR pulse sequence based on magic-angle spinning of the q-vector. Proof-of-principle experiments are carried out on microimaging and clinical MRI equipment using lyotropic liquid crystals and plant tissues as model materials with high µFA and low FA on account of orientation dispersion. We expect the presented method to be especially fruitful in combination with DTI and high angular resolution acquisition protocols for neuroimaging studies of grey and white matter.

Osteoporosis detection by 3T diffusion tensor imaging and MRI spectroscopy in women older than 60 years

Aim of this study was to evaluate the cancellous bone quality of postmenopausal women (age >60 years) by diffusion tensor imaging (DTI) using mean diffusivity (MD) and fractional anisotropy (FA) in combination with proton magnetic resonance spectroscopy (1H-MRS). 20 postmenopausal women older than 60 years were introduced to dual-energy X-ray absorptiometry (DXA) examination in femoral neck and to an MRI spectroscopy and DTI evaluation at 3T. We observed that fat fraction (FF) can discriminate healthy and osteoporotic patients. Water mean diffusivity (MD) and FA can discriminate the healthy group from osteopenic and osteoporotic group. MD/FF vs FA/FF graph extracted from the femoral neck identifies all healthy individuals, according to DXA results. DTI and spectroscopy protocol performed in the femoral neck could be highly sensitive and specific in identifying healthy subjects.

Hippocampal multimodal structural changes and subclinical depression in healthy individuals

BackgroundSeveral neuroimaging studies report reduced hippocampal volume in depressed patients. However, it is still unclear if hippocampal changes in healthy individuals can be considered a risk factor for progression to clinical depression. Here, we investigated subclinical depression and its hippocampal correlates in a non-clinical sample of healthy individuals, with particular regard to gender differences. MethodsOne-hundred-two participants underwent a comprehensive clinical assessment, a high-resolution T1-weighted magnetic resonance imaging and diffusion tensor imaging protocol using a 3T MRI scanner. Data of macro-(volume) and micro-(mean diffusivity, MD) structural changes of the hippocampus were analyzed with reference to the Beck Depression Inventory score. ResultsResults of multivariate regression analyses revealed reduced bilateral volume, along with increased bilateral MD in hippocampal formation predicting subclinical depressive phenomenology only in healthy males. Conversely, subclinical depressive phenomenology in healthy female was accounted for by only lower educational level, in the absence of any hippocampal structure variations. LimitationsTo date, this is the only evidence reporting a relationship between subclinical depressive phenomenology and changes in hippocampal formation in healthy individuals. ConclusionsOur findings demonstrated that reduced volume, along with increased MD in hippocampal formation, is significantly associated with subclinical depressive phenomenology in healthy males. This encourages to study the hypothesis that early macro- and microstructural changes in hippocampi associated with subclinical depression may constitute a risk factor of developing depressive disorders in males.

Diffusion tensor imaging of Parkinson's disease, atypical parkinsonism, and essential tremor

Diffusion tensor imaging could be useful in characterizing movement disorders because it noninvasively examines multiple brain regions simultaneously. We report a multitarget imaging approach focused on the basal ganglia and cerebellum in Parkinson's disease, parkinsonian variant of multiple system atrophy, progressive supranuclear palsy, and essential tremor and in healthy controls. Seventy-two subjects were studied with a diffusion tensor imaging protocol at 3 Tesla. Receiver operating characteristic analysis was performed to directly compare groups. Sensitivity and specificity values were quantified for control versus movement disorder (92% sensitivity, 88% specificity), control versus parkinsonism (93% sensitivity, 91% specificity), Parkinson's disease versus atypical parkinsonism (90% sensitivity, 100% specificity), Parkinson's disease versus multiple system atrophy (94% sensitivity, 100% specificity), Parkinson's disease versus progressive supranuclear palsy (87% sensitivity, 100% specificity), multiple system atrophy versus progressive supranuclear palsy (90% sensitivity, 100% specificity), and Parkinson's disease versus essential tremor (92% sensitivity, 87% specificity). The brain targets varied for each comparison, but the substantia nigra, putamen, caudate, and middle cerebellar peduncle were the most frequently selected brain regions across classifications. These results indicate that using diffusion tensor imaging of the basal ganglia and cerebellum accurately classifies subjects diagnosed with Parkinson's disease, atypical parkinsonism, and essential tremor and clearly distinguishes them from control subjects.

Effect of B-value in revealing postinfarct myocardial microstructural remodeling using MR diffusion tensor imaging

Nonmonoexponential diffusion behavior has been previously reported to exist in some biological tissues, making quantification of diffusion tensor imaging (DTI) indices dependent on diffusion sensitivity of b-value. This study aims to investigate the effect of b-value in revealing postinfarct myocardial microstructural remodeling in ex vivo hearts. DTI scans were performed on heart samples 1, 3, 5, and 7 days after infarction induction as well as intact controls with b-values of 500 to 2500s/mm2. DTI indices, including fractional anisotropy (FA), and mean and directional diffusivities, were measured in infarct, adjacent and remote regions with zero and each non-zero b-values respectively using conventional DTI analysis. Experimental results showed that these DTI indices decreased gradually with b-values in all regions and groups. Optimal b-values were found to vary with targeted DTI indices, and could strengthen DTI ability in revealing myocardium degradation with using conventional DTI approach. Specifically, FA showed the most sensitive detection of fiber integrity degradation at moderate b-values (≈1500 to 2000s/mm2), and the greatest ability of mean and directional diffusivities in monitoring diffusivity alteration occurred at relatively small b-values (≤1500s/mm2) during the necrotic and fibrotic phases. These findings may provide useful information for DTI protocol parameter optimization in assessing heart microstructures at other pathological or in vivo states in the future.

Thoracic and lumbar spinal cord diffusion tensor imaging in dogs

To analyze four clinically applicable diffusion tensor imaging (DTI) protocols (two each in the transverse and sagittal planes) in the normal dog. Seven healthy Dachshund dogs were scanned with four DTI protocols. Within each plane, identical spatial resolution was used while the number of diffusion-encoding directions and averages varied. Agreement of measured fractional anisotropy (FA) and apparent diffusion coefficient (ADC) was analyzed with Bland-Altman methods, subjective image quality within each plane was compared, and FA and ADC were explored as a function of anatomic location. There was good agreement in FA and ADC values within each plane. FA had the smallest bias and most precision. No difference was detected in subjective image quality within each plane. FA and ADC were slightly higher cranial to the lumbar intumescence compared to within it. DTI is a promising tool in the assessment of spinal cord injury (SCI) in the study of dogs with intervertebral disk herniation as a preclinical model of human SCI.

Reproducibility of quantitative fiber tracking measurements in diffusion tensor imaging of frontal lobe tracts: A protocol based on the fiber dissection technique

Background:Diffusion tensor imaging (DTI)-based tractography is a noninvasive in vivo method for tracing white matter bundles. This raises possibilities for qualitative and quantitative assessment of the structural organization of tracts. Nevertheless, questions remain about neuroanatomical accuracy, reproducibility for clinical purposes, and accessibility of the best method for broader application. The aim of this study was to combine the fiber dissection technique and tractography to provide more pertinent insight into brain anatomy and, as a result, to test a protocol for reconstruction of six major frontal lobe tracts.Methods:A combination of fiber dissection of formalin-fixed brain tissue after freezing (Klingler's technique) and virtual dissection (tractography) was used to develop a protocol to reconstruct major frontal tracts. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), number of voxels (NVO), volume (VOL), number (NTR), and length (LEN) of tracts were evaluated to assess intra- and interobserver reproducibility. Statistical reliability was evaluated using intraclass correlation coefficients (ICCs) and the Pearson association coefficient (r).Results:The virtual dissection obtained by tractography seemed to reproduce the anatomic knowledge of the white matter tracts obtained through the classic method. In reliability study, most ICC and r values corresponded at least to large correlation. The magnitude of correlation was very high (ICC 0.7-0.9) or almost perfect (ICC 0.9-1.0) for the FA and ADC measures of every tract studied.Conclusion:The DTI protocol proposed herein provided a reliable method for analysis of reconstructed frontal lobe tracts, especially for the FA and ADC variables.

Development of a high-resolution fat and CSFsuppressed optic nerve DTI protocol at 3T: application in multiple sclerosis

Clinical trials of neuroprotective interventions in multiple sclerosis require outcome measures that reflect the disease pathology. Measures of neuroaxonal integrity in the anterior visual pathways are of particular interest in this context, however imaging of the optic nerve is technically challenging. We therefore developed a 3T optic nerve diffusion tensor imaging protocol incorporating fat and cerebrospinal fluid suppression and without parallel imaging. The sequence used a scheme with six diffusion-weighted directions, b = 600 smm(-2) plus one b ≈ 0 (b(0)) and 40 repetitions, averaged offline, giving an overall scan time of 30 minutes. A coronal oblique orientation was used with voxel size 1.17 mm x 1.17 mm x 4 mm, We validated the sequence in 10 MS patients with a history of optic neuritis and 11 healthy controls: mean fractional anisotropy was reduced in the patients: 0.346(±0.159) versus 0.528(±0.123), p<0.001; radial diffusivity was increased: 0.940(±0.370)x10(-6) mm(2) s(-1) compared to 0.670(± 0.221)x10(-6) mm(2) s(-1) (p<0.01). No significant differences were seen for mean diffusivity or mean axial diffusivity.

Degeneration of the Injured Cervical Cord Is Associated with Remote Changes in Corticospinal Tract Integrity and Upper Limb Impairment

BackgroundTraumatic spinal cord injury (SCI) leads to disruption of axons and macroscopic tissue loss. Using diffusion tensor imaging (DTI), we assessed degeneration of the corticospinal tract (CST) in the cervical cord above a traumatic lesion and explored its relationship with cervical atrophy, remote axonal changes within the cranial CST and upper limb function.MethodsNine cervical injured volunteers with bilateral motor and sensory impairment and ten controls were studied. DTI of the cervical cord and brain provided measurements of fractional anisotropy (FA), while anatomical MRI assessed cross-sectional spinal cord area (i.e. cord atrophy). Spinal and central regions of interest (ROI) included the bilateral CST in the cervical cord and brain. Regression analysis identified correlations between spinal FA and cranial FA in the CST and disability.ResultsIn individuals with SCI, FA was significantly lower in both CSTs throughout the cervical cord and brain when compared with controls (p≤0.05). Reduced FA of the cervical cord in patients with SCI was associated with smaller cord area (p = 0.002) and a lower FA of the cranial CST at the internal capsule level (p = 0.001). Lower FA in the cervical CST also correlated with impaired upper limb function, independent of cord area (p = 0.03).ConclusionAxonal degeneration of the CST in the atrophic cervical cord, proximal to the site of injury, parallels cranial CST degeneration and is associated with disability. This DTI protocol can be used in longitudinal assessment of microstructural changes immediately following injury and may be utilised to predict progression and monitor interventions aimed at promoting spinal cord repair.

Improved in vivo diffusion tensor imaging of human cervical spinal cord

We describe a cardiac gated high in-plane resolution axial human cervical spinal cord diffusion tensor imaging (DTI) protocol. Multiple steps were taken to optimize both image acquisition and image processing. The former includes slice-by-slice cardiac triggering and individually tiltable slices. The latter includes (i) iterative 2D retrospective motion correction, (ii) image intensity outlier detection to minimize the influence of physiological noise, (iii) a non-linear DTI estimation procedure incorporating non-negative eigenvalue priors, and (iv) tract-specific region-of-interest (ROI) identification based on an objective geometry reference. Using these strategies in combination, radial diffusivity (λ(⊥)) was reproducibly measured in white matter (WM) tracts (adjusted mean [95% confidence interval]=0.25 [0.22, 0.29] μm(2)/ms), lower than previously reported λ(⊥) values in the in vivo human spinal cord DTI literature. Radial diffusivity and fractional anisotropy (FA) measured in WM varied from rostral to caudal as did mean translational motion, likely reflecting respiratory motion effect. Given the considerable sensitivity of DTI measurements to motion artifact, we believe outlier detection is indispensable in spinal cord diffusion imaging. We also recommend using a mixed-effects model to account for systematic measurement bias depending on cord segment.

Fronto-thalamic volumetry markers of somatic delusions and hallucinations in schizophrenia

Although the psychotic phenomena of schizophrenia have been extensively investigated, somatic delusions and hallucinations have seldom been reported and their mechanisms are substantially unexplored. Here, we aimed to identify the brain structural correlates of somatic psychotic phenomena using combined volumetry and diffusivity structural neuroimaging techniques. Seventy-five individuals with a DSM-IV-TR diagnosis of schizophrenia and 75 healthy controls (HC) underwent a comprehensive clinical assessment, a high-resolution T1-weighted magnetic resonance imaging and a diffusion tensor imaging protocol using a 3T MRI scanner. Voxel-based volumetry and mean diffusivity (MD) of gray matter (GM) and fractional anisotropy (FA) of white matter (WM) of the whole brain were calculated for each subject. Reduced left fronto-insular GM volume was found in patients with somatic delusions compared with patients without somatic delusions and HC. Increased GM volume was found in the bilateral thalami, primarily in the right ventral-anterior thalamic nucleus projecting to the prefrontal-temporal cortices and the bilateral pars triangularis of the inferior frontal lobe, of patients with somatic hallucinations and HC compared with patients without somatic hallucinations. No differences emerged in GM MD and in WM FA between patients with and without psychotic somatic phenomena (i.e. delusions or hallucinations). These findings provide the first evidence that a frontal-thalamic structural perturbation mediates somatic psychotic phenomena in schizophrenia.

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)(1, 2) protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

Understanding white matter integrity stability for bilinguals on language status and reading performance

Recent studies using diffusion tensor imaging (DTI) have described overall white matter integrity in bilinguals but have not related structural neural pathways to language functions. The current study examined white matter integrity and its relationship to reading skill in monolingual English and bilingual Chinese-English speakers. Eleven monolingual speakers (mean age 28.5 years) and 13 bilingual speakers (mean age 24.2 years; English as a second language was acquired post 5 years of age) participated. Behavioural response times and accuracy rates to name regular and exception words were recorded. Participants were then scanned using a standardized DTI protocol. Fractional anisotropy (FA) and mean diffusivity values were derived from a voxelwise statistical analysis for comparisons between participant groups. Tests for relationships between response time and FA were also conducted. Our results show minimal regions of higher FA for monolinguals when compared to bilinguals and no regions of higher FA for bilinguals when compared to monolinguals, which indicates that white matter integrity may not stabilize in bilinguals until late adulthood. We do show several regions where an increase in FA is associated with faster response times. Interestingly, the FA-response time relationship varies between groups and between word types, which may reflect an increased processing demand for retrieval of difficult words (e.g., exception words). These results provide some support for the interference control and reduced frequency hypotheses outlined by Jones et al. (Cerebr Cortex 22:892-902, 2012). The current findings advance our understanding of the underlying cortical networks associated with language status and reading skill in monolingual and bilingual adults.

Diffuse Abnormality of Low to Moderately Organized White Matter in Schizophrenia

Increasing evidence suggests that abnormal white matter is central to the pathophysiology and, potentially, the pathogenesis of schizophrenia (SCZ). The spatial distribution of observed abnormalities and the type of white matter involved remain to be elucidated. Seventeen chronically ill individuals with SCZ and 17 age- and gender-matched controls were studied using a 3T magnetic resonance imaging diffusion tensor imaging protocol designed to examine the abnormalities of white matter by region and by level of architectural infrastructure as assessed by fractional anisotropy (FA) in native space. After assessing whole-brain FA, FA was divided into quartiles, capturing all brain regions with FA values from 0 to 0.25, 0.25 to 0.5, 0.5 to 0.75, and 0.75 to 1.0. Mean whole-brain FA was 4.6% smaller in the SCZ group than in healthy controls. This difference was largely accounted for by FA values from the second quartile (between 0.25 and 0.5). Second quartile FA was decreased in all 130 brain regions of the template in the SCZ group, with the difference reaching statistical significance in 41 regions. Correspondingly, the amount of brain tissue with an FA of ∼0.4 was significantly reduced in the SCZ group, while the amount of brain tissue falling in the lowest quartile of FA was increased. These findings strongly imply a diffuse loss of white matter integrity in SCZ. Our finding that the loss of integrity disproportionately involves white matter of low to moderate organization suggests an approach to the specificity of white matter abnormalities in SCZ based on microstructure rather than spatial distribution.

Continuing the search for MR imaging biomarkers for MGMT promoter methylation status: conventional and perfusion MRI revisited

Continuing the search for MR imaging biomarkers for MGMT promoter methylation status: conventional and perfusion MRI revisited