Visualization of Diffusion Tensor Imaging (DTI) for Schizophrenia Diagnosis

Diffusion tensor (DT) imaging is an emerging magnetic resonance (MR) imaging technique for evaluating the microstructure of well-organized biologic tissues such as muscles and nerves. DT imaging provides information about tissue microstructure by producing three-dimensional maps of water molecule movements. The two main parameters of measurement at DT imaging, fractional anisotropy and the apparent diffusion coefficient, allow quantitation of architectural changes occurring in tissue. These parameters are modified in the presence of cervical spondylotic myelopathy, cervical spine trauma, carpal tunnel syndrome, lumbar nerve compression, peripheral nerve tumors, and muscle ischemia. Their alteration may be observed at DT imaging even when no abnormality is seen at conventional MR imaging, a fact that suggests that DT imaging allows the detection of abnormalities at an earlier stage of injury. Experimental studies in animals have shown that DT imaging consistently allows identification of pathophysiologic alterations in tissue that correlate with histologic findings. Tractographic images accurately depict both normal and abnormal diffusion in anatomic structures such as the thigh and pelvic muscles, cervical spine, and lumbar nerves. Patients with chronic diseases also may benefit from follow-up evaluation with DT imaging, although DT imaging sequences must be further adapted to improve the evaluation of specific anatomic regions by reducing artifacts, optimizing spatial resolution, and minimizing acquisition time. Given its proven potential for use in identifying abnormalities that are otherwise identifiable only with electrophysiologic and histopathologic studies, and with future technical improvements, DT imaging could soon become a standard method for early diagnosis, management, and follow-up of disease in the spine, muscles, and peripheral nerves.

712 Correlating Current Pathways With Myocardial Fiber Orientation Through Fusion of Data From Current Density and Diffusion Tensor Imaging

To investigate the features of white matter myelin development in preterm infants using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). A total of 31 preterm infants with a gestational age of ≤32 weeks and a birth weight of <1 500 g were enrolled. According to head MRI findings, these infants were divided into preterm group with brain injury (12 infants) and preterm group without brain injury (19 infants). A total of 24 full-term infants were enrolled as control group. Head MRI and DTI were performed at a gestational age or corrected gestational age of 37-40 weeks. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured for the same regions of interest in the three groups. The preterm group with brain injury showed a significantly lower FA value of the posterior limb of the internal capsule than the preterm group without brain injury and full-term control group (P<0.05). The preterm groups with and without brain injury showed significantly lower FA values of frontal white matter and lenticular nucleus than the full-term control group (P<0.05). The FA value of occipital white matter showed no significant differences among the three groups (P>0.05). Compared with the full-term control group, the preterm groups with and without brain injury showed significantly higher ADC values of the posterior limb of the internal capsule, lenticular nucleus, occipital white matter, and frontal white matter (P<0.05). After brain injury, preterm infants tend to develop disorder or delay of white matter myelination in the posterior limb of the internal capsule. At a corrected full-term gestational age, the preterm infants with and without brain injury have a lower grade of maturity in periventricular white matter and grey matter than full-term infants.

Introduction We present the first study in literature that documents the changes in diffusion tensor imaging (DTI) indices and tractography after surgical decompression in patients with cervical myelopathy. DTI, an established tool for tracking nerve fibers in brain, is now widely evaluated for its usefulness in spine pathologies. Although there are many studies directly comparing DTI indices of control and cervical myelopathic patients, there are no studies that have evaluated the prognostic applicability of DTI indices. The present study analyzes the pre- and postdecompression DTI indices and tractography in cervical myelopathic patients and its prognostic value. Materials and Methods Total 56 subjects including 16 cervical myelopathy patients who required surgical decompression (mean age: 53.5 ± 12.3 years, males: 15, females: (1) and forty normal controls (mean age: 38.18 ± 13.74 years, males: 20, females: 20) were included in the study. DTI of cervical spine was obtained using an axial single shot echo-planar parallel diffusion-weighted imaging sequence in a 1.5 tesla magnetic resonance imaging (MRI). Apparent diffusion coefficient (ADC), fractional anisotropy (FA), and Eigen values (E1, E2, and E3) were obtained at each region of interest (cervical disk level) from C1-C2 to C7-T1. The DTI indices of myelopathic patients were compared with normal volunteers after matching was done based on sex, cord level, and cord size. Postoperatively, the patients were followed up after 6 months and DTI scan was performed again. The clinical improvement and the DTI indices observed at the follow-up were compared with the preoperative values. Results Analysis showed significant differences between the controls and patients in all the indices (p&lt;0.05) at the site of compression. At the compressed levels, FA decreased while all the other indices increased as compared to the controls. The mean DTI indices of myelopathic patients before surgery at the sites of spinal cord compression were as follows: FA (0.49 ± 0.092), ADC (1.8 ± 0.32 µm2/ms), E1 (2.80 ± 0.44 µm2/ms), E2 (1.63 ± 0.45 µm2/ms), E3 (0.95 ± 0.23 µm2/ms). The average DTI indices of matched controls were as follows: FA (0.55 ± 0.033), ADC (1.47 ± 0.066 µm2/ms), E1 (2.49 ± 0.150 µm2/ms), E2 (1.16 ± 0.050 µm2/ms), E3 (0.77 ± 0.058 µm2/ms. The Nurick grading distribution in patients before surgery was as follows: Grade 2 = 2, Gr 3 = 8, Gr 4 = 2, Gr 5 = 4. Postoperatively, all the patients had improvement of neurology by at least one Nurick grade except for one patient who had no improvement. The Nurick grading distribution in patients during 6 months follow-up after surgery was as follows: Grade 0 = 3, Gr 1 = 6, Gr 2 = 2, Gr 3 = 3, Gr 4 = 2. Mean postoperative values of ADC, E1, and E2 showed improvement towards normal values especially in patients with preoperative Nurick grade 2 and 3 (Table 1). Patients with Nurick grade 4 and 5 did not show any significant change. The mean FA and E3 values worsened when compared to preoperative DTI indices. The postoperative DTI indices for the patients who had neurological improvement are as follows: FA (0.45 ± 0.087), ADC (1.73 ± 0.31 µm2/ms), E1 (2.59 ± 0.28 µm2/ms), E2 (1.56 ± 0.38 µm2/ms), E3 (1.07 ± 0.31 µm2/ms. Tractography also showed interruption of nerve fibre tract continuity at the level of severe compression in patients with myelopathy. At levels of moderate compression over the spinal cord, the changes in direction of nerve fibres due to bulging disc-osteophytes were evident as changes in color coding of the tracts. After surgical decompression, the restitution of fibre tract pathways was clearly demonstrated in DT tractography. Conclusion For the first time, the prognostic applicability of DTI by comparing pre- and postoperative indices of cervical myelopathy patients has been described. All preoperative DTI indices at compressed levels showed significant differences from controls indicating abnormality in neuronal integrity. All but one of the patients showed clinical improvement at 6 months. The postoperative DTI values (ADC, E1 and E2) of patients with Nurick grading 2 and 3 were observed to approach normal values indicating restoration of linear diffusion in neuronal tracts. DTI indices in patients with Nurick grade 4 and 5 remained same or worsened more. This could probably indicate persistent axonal damage. At 6 months postsurgery, DTI indices show evidence of improvement towards normal values, even though the values did not match the true extent of clinical improvement. Further DTI evaluation at 12 months and 2 years is required to analyze the extent of usefulness of DTI indices in evaluating cervical myelopathy. The results suggest that DTI indices, especially ADC and Eigen vectors can be promising indicators in the evaluation and prognostic assessment of myelopathy patients. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared

Brain injury in term neonatal hypoxic-ischemic encephalopathy (HIE) emerges on magnetic resonance imaging (MRI) by day 3. This study aimed to address the relationship of MRI, diffusion tensor imaging (DTI), and MR spectroscopic imaging (MRSI) findings on days 1 and 3 in a prospective cohort of term newborns with HIE. A total of 24 term newborns with HIE were prospectively studied with MRI on days 1 and 3; 19 were imaged with DTI and MRSI on days 1 and 3. MRI was assessed using validated scores. The relationship between MRI, DTI, and MRSI values on days 1 and 3 was determined using linear regression for repeated measures. Conventional MRI showed a complex variation of findings from day 1 to 3. In gray matter, mean diffusivity (Dav) and metabolite ratios measured on day 1 were predictive of values on day 3 (all P ≤ 0.04). In white matter, Dav, fractional anisotropy (FA), and N-acetylaspartate (NAA)/choline on days 1 and 3 were strongly related (all P ≤ 0.003). Hypothermia appeared to attenuate the severity and progression of brain injury in the six treated newborns. In term newborns with HIE, quantitative MR values on days 1 and 3 are strongly associated, providing an objective measure of injury before qualitative images.

Diffusion Tensor Imaging (DTI) is a magnetic resonance imaging (MRI) modality which can significantly improve our understanding of the brain structures and neural connectivity. DTI measures are thought to be representative of brain tissue microstructure and are particularly useful for examining organized brain regions, such as white matter tract areas. DTI measures the water diffusion tensor using diffusion weighted pulse sequences which are sensitive to microscopic random water motion. The resulting diffusion weighted images (DWI) display and allow quantification of how water diffuses along axes or diffusion encoding directions. This can help to measure and quantify the tissue’s orientation and structure, making it an ideal tool for examining cerebral white matter and neural fiber tracts. In this chapter the authors discuss the theoretical aspects of DTI, the information that can be extracted from DTI data, and the use of the extracted information for the reconstruction of fiber tracts and the diagnosis of a disease. In addition, a review of known fiber tracking algorithms is presented.

This thesis aimed to investigate the feasibility of two diffusion imaging techniques, Diffusion Tensor Imaging (DTI) and Diffusion Kurtosis Imaging (DKI), on detecting subtle physiological or pathological microstructural changes in normal-appearing neural tissues of human central nervous system. &#13;\n At first, ten patients with neuromyelitis optica (NMO) and twelve age- and gender-matched healthy subjects were recruited. DTI-derived indices including fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivities were quantified in the lateral and dorsal columns of cervical spinal cord. Based on the regions of interest (ROIs) measurement, NMO patients showed reduced FA, increased MD and radial diffusivity compared to control subjects, while axial diffusivity did not show any significant difference. The three former DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO. Our results show that DTI-derived indices can quantitatively assess the white matter (WM) abnormalities with seemingly normal appearance in conventional MRI, and are associated with the level of clinical disability, suggesting that DTI may have great potential as a useful diagnostic tool in the clinical setting.&#13;\n DKI is an extension of conventional DTI to probe the non-Gaussian diffusion property in biological tissues. Besides the four conventional DTI-derived metrics, DKI also provide three additional kurtosis metrics (mean kurtosis (MK), axial and radial kurtosis). In the second study, ROI-based analysis was used to characterize age-related microstructural changes in WM, cortical and subcortical gray matter (GM) of 27 healthy adults (21~59 yrs). Though the volumes of GM and WM were still preserved, DTI-derived metrics can detect the subtle changes in WM and GM. Meanwhile, MK and radial kurtosis significantly increased in both caudate nucleus and putamen while Thalamus showed little aging effect in the diffusivity and kurtosis metrics but significantly decreased only in FA. Our results demonstrated that DKI is sensitive to detect the age-related alterations in neural microstructures at the stage of early aging.&#13;\n In addition, DKI has been applied to detect the pathological changes in the normal-appearing neural tissues of 18 patients with multiple sclerosis (MS), compared to 22 healthy controls. Diffuse WM abnormalities have been observed extensively in the brain, revealed by DKI-derived metrics. Though the volumetric and voxel-wise analysis revealed no significant changes in the volume of cortical GM, decreased FA and kurtoses with increased diffusivities in MS group were sensitive to disclose the subtle alterations in global and regional cortical GM tissues. Significant correlations have been found between FA in the global, frontal and temporal cortical GM in relapsing-remitting MS patients and their disability scores, suggesting FA as an important biomarker to monitor the disease progress in cortical GM. Moreover, elevated kurtosis indices in MS patients did not correlate with diffusivities in caudate nucleus, putamen and thalamus, suggesting these metrics may be vulnerable to different pathologic aspects of the disease.&#13;\n In conclusion, DKI is sensitive to neural alterations during normal aging and in MS pathologies, and can provide complementary information to conventional MRI and DTI.

Diffusion Tensor Magnetic Resonance Imaging and Fiber Tractography of the Sacral Plexus in Children with Spina Bifida

Malformations of cortical development (MCD) include a broad range of disorders that result from disruption of the major steps of cortical development: cell proliferation in germinal zones, neuronal migration and cortical organization. With the improvement and increased utilization of modern imaging techniques, MCD have been increasingly recognized as a major cause of seizure disorders. The advent of Magnetic Resonance Imaging (MRI), in particular, has revolutionized the investigation and the treatment of patients with epilepsy. High-resolution MRI may elucidate the type, the extension and the localization of MCD; therefore, in a group of patients suffering from drug-resistant partial epilepsy (DRPE), MRI greatly contributes to the identification of subjects who are suitable for surgical treatment. In the recent past, many efforts were addressed to establish the MRI diagnostic criteria for a peculiar group of MCD, namely focal cortical dysplasias (FCD), histopathologically distinguished as types I and II. Some subtle FCD, which were previously cryptic to imaging investigation, can now be recognized by MRI, however their detection and specification remains challenging. This review will re-visit the neuroimaging findings, including structural MRI, PET, co-registered PET/MRI, MEG and diffusion tensor imaging (DTI) of FCD types I and II. Three major issues will be discussed: 1) the morphological MRI features of the FCDs, 2) the utility of PET and MEG and the use of co-registration methods and 3) diffusion tensor imaging (DTI) as a future modality of investigation, which may add additional informations regarding the microstructure of the grey matter (GM) and white matter (WM) in cortical dysplasia.

Introduction: The conventional magnetic resonance imaging (MRI) method is widely considered ‘with limited success’ in differentiating the meningioma types but may fail to localize the tumor occupation of white-matter fiber bundles accurately. Diffusion tensor imaging (DTI) is considered as an imaging modality that may elucidate the microstructure of brain tumors. We provide characteristics of meningioma using DTI-based-three-dimensional tracing of white matter to portray meningioma in a noninvasive approach and its structural contact to contiguous tumors and elucidate the influence of occupying lesions on white-matter fiber bundles. Case Presentation: A 28-year-old female presented with visuospatial disturbances and persistent headaches for 2 years. Conventional and advanced MRI studies were performed. Diffusion-weighted Images (DWI) and Apparent Diffusion Coefficient (ADC) values were measured in the lesion using routine MRI sequences. Advanced MRI using DTI was also performed. Conventional MRI outcomes showed tumor parenchyma, peritumoral edema, and compression on the circumnavigated brain tissue. There was hyperintense on DW trace image and isointense on ADC map. On T2-weighted image (T2WI) and Fluid-Attenuated Inversion Recovery (FLAIR) images, there was an increased signal intensity that demonstrated an extra-axial lesion, while T1-weighted imaging signals showed hypointensity. DTI fractional anisotropy (FA) marker is an unclear optic radiation in the concerned area, indicating the shift or destruction of the optic radiation. The mean FA values of solid-enhancing areas of meningioma were 0.28 ± 0.17. Mean ADC values (103 mm2/s) were 0.764 ± 0.172. Conclusions: Classic meningioma in this case has low intratumoral FA and high ADC. DTI displayed that intratumoral microscopic water motion is disorganized.

Texture analysis in brain T2 and diffusion MRI differentiates histology-verified grey and white matter pathology types in multiple sclerosis

The growing number of neuroimaging studies of cynomolgus macaques require extending existing templates to facilitate species-specific application of voxel-wise neuroimaging methodologies. This study aimed to create population-averaged structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) templates for the cynomolgus macaques and apply the templates in fully automated voxel-wise analyses. We presented the development of symmetric and asymmetric MRI and DTI templates from a sample of 63 young male cynomolgus monkeys with the use of optimized template creation approaches. We also generated the associated average tissue probability maps and Diffeomorphic Anatomical Registration using Exponentiated Lie Algebra templates for use with the Statistical Parametric Mapping (SPM), as well as the average fractional anisotropy/skeleton targets for incorporation into tract-based spatial statistics (TBSS) framework. Both asymmetric and symmetric templates in a standardized coordinate space demonstrated low bias and high contrast. Fully automated processing using SPM was accomplished for all native MRI datasets and demonstrated outstanding performance regarding skull-stripping, segmentation, and normalization when using the MRI templates. Automated normalization to the DTI template was excellently achieved for all native DTI images using the TBSS pipeline. The cynomolgus MRI and DTI templates are anticipated to provide a common platform for precise single-subject data analysis and facilitate comparison of neuroimaging findings in cynomolgus monkeys across studies and sites. It is also hoped that the procedures of template creation and fully-automated voxel-wise frameworks will provide a straightforward avenue for investigating brain function, development, and neuro-psychopathological disorders in non-human primate models.

Objective To analyze the characteristics of magnetic resonance diffusion tensor imaging(DTI)and diffusion tensor tractography (DTIT) in patients with cerebral infarction, and explore the diagnosis values and prognosis of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) in patients with cerebral infarction in different stages. Methods 58 patients with cerebral infarction in different stages and 25 healthy volunteers were examined by magnetic resonance imaging (MRI), including conventional T1 and T2 weighted imaging, DWI and DTI. Fractional anisotropy (FA) images were reconstructed. The values of FA and apparent diffusion coefficient (ADC) were measured in the infarcted regions, corresponding contralateral normal regions and corresponding normal regions in normal control group. Results ①DWI and DTI showed size of infarction focus was more accurate and clearer than that of conventional MRI; ②The FA and ADC values of the infarcted regions during superacute stage, acute stage, subacute stage and chronic stage were (0.24±0.02, 0.31 ±0.11), (0.20±0.02, 0.32±0.12), (0.18±0.02, 0.34±0.11) and (0.16±0.02, 0.37±0.13), respectively, lower than those in the contralateral corresponding regions which were (0.40±0.03, 0.70±0.21), (0.37±0.03, 0.71±0.21), (0.39±0.03, 0.72±0.22) and (0.40:±0.03, 0.72±0.23), respectively. The differences were statistically significant (P＜0.05). The FA and ADC values had no significant differences between the uninjured sides in patients with cerebral infarction and the corresponding regions in the normal control group (P＞0.05); ③The FA and ADC values in brain tissues changed regularly with the time of infarction after cerebral infarction. The FA values in the affected sides had no consistent changes as compared with the contralateral sides in the superacute stage. They increased or decreased slightly, then (during acute stage, subacute stage and chronic stage) decreased irreversibly. The ADC values in the affected sides changed with time regularly, they decreased significantly, gradually returned to normal, and then increased again. Conclusion DTI and DTT examination contribute to the diagnosis of cerebral infarction. The combination of the FA and ADC values may more accurately conduct clinical staging and evaluate the time of the occurrence of cerebral infarction. Key words: Magnetic resonance; Cerebral infarction; Diffusion tensor imaging; Diffusion tensor tractography

OP0169 Assessment of Lupus Nephritis Disease Activity Using Non-Contrast MRI: A Pilot Study

Fiber tractography is a technique capable of depicting the three-dimensional structure and connectivity of nerve fibers using serial magnetic resonance diffusion tensor imaging (DTI). To establish fiber tractography and DTI methods in veterinary clinical medicine, we evaluated fiber tractography and DTI parameters: apparent diffusion coefficient (ADC) values and fractional anisotropy (FA) values, in various spinal cord diseases. Spinal cord DTI was examined in 28 dogs with spinal cord diseases. The ADC and FA values were measured at lesion sites and cranial normal sites on spinal cords, and both values of lesion sites were compared with normal sites. In thoracolumbar intervertebral disk herniation (IVDH) cases, depending on their neurologic grades, fiber tractography indicated rupture of fiber trajectories, loss of neuronal bundles and disorder of fiber directions. In these cases, the average ADC values at lesion sites significantly decreased compared with normal sites (P=0.016). In the progressive myelomalacia case, the average ADC and FA values of hyperintense swollen regions in T2WI decreased compared to both values in other disease cases. Finally, in the meningioma case, the continuity of fiber trajectories improved after the administration of an anticancer agent. This study suggests that fiber tractography and DTI are useful in the diagnosis and prognosis of veterinary spinal cord diseases.