Diffusion Tensor Tractography Parameters Research Articles

Correlation between spasticity and corticospinal/corticoreticular tract status in stroke patients after early stage.

We investigated the correlation between spasticity and the states of the corticospinal tract (CST) and corticoreticular tract (CRT) in stroke patients after early stage. Thirty-eight stroke patients and 26 healthy control subjects were recruited. The modified Ashworth scale (MAS) scale after the early stage (more than 1 month after onset) was used to determine the spasticity state of the stroke patients. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), fiber number (FN), and ipsilesional/contra-lesional ratios for diffusion tensor tractography (DTT) parameters of the CST and CRT after the early stage were measured in both ipsi- and contra-lesional hemispheres. This study was conducted retrospectively. The FA and FN CST-ratios in the patient group were significantly lower than those of the control group (P < .05), except for the ADC CST-ratio (P > .05). Regarding the DTT parameters of the CRT-ratio, the patient group FN value was significantly lower than that of the control group (P < .05), whereas the FA and ADC CRT-ratios did not show significant differences between the patient and control groups (P > .05). MAS scores showed a strong positive correlation with the ADC CRT-ratio (P < .05) and a moderate negative correlation with the FN CRT-ratio (P < .05). We observed that the injury severities of the CST and CRT were related to spasticity severity in chronic stroke patients; moreover, compared to the CST, CRT status was more closely related to spasticity severity.

Prediction of the gait function using the nigrostriatal and corticoreticulospinal tracts of the affected hemisphere in a cerebral infarct: A diffusion tensor imaging study.

Prognosis predictability of the nigrostriatal tract (NST) and corticoreticulospinal tract (CRT) of affected hemisphere at early stage for gait function at chronic stage were investigated using diffusion tensor tractography (DTT) in patients with a cerebral infarction.Thirty consecutive patients with middle cerebral artery (MCA) territory infarction were recruited. Functional ambulation category (FAC) was used to evaluate the gait function at chronic stage. Fractional anisotropy (FA) and tract volume (TV) of ipsilesional NST and ipsilesional CRT were determined to be DTT parameters at early stage.FAC score at chronic stage showed strong positive correlations with TVs of ipsilesional NST and ipsilesional CRT at early stage (ipsilesional NST R = 0.786; ipsilesional CRT R = 0.821; P < .05). According to regression model, FAC score at chronic stage was positively related to TVs of ipsilesional NST and ipsilesional CRT at early stage (Adjusted R2 = 0.700, F = 34.905, P < .05). FAC score at chronic stage was associated more positively with TV of ipsilesional CRT (β = 0.532) than that of ipsilesional NST (β = 0.362).Ipsilesional NST and ipsilesional CRT at early stage had prognosis predictability for gait function at chronic stage in patients with an MCA infarction. Moreover, ipsilesional CRT had stronger predictability than ipsilesional NST.

Diagnostic sensitivity of traumatic axonal injury of the spinothalamic tract in patients with mild traumatic brain injury.

Diffusion tensor tractography (DTT) can detect traumatic axonal injury (TAI) in patients whose conventional brain magnetic resonance imaging results are negative. This study investigated the diagnostic sensitivity of TAI of the spinothalamic tract (STT) in patients with a mild traumatic brain injury (TBI) suffering from central pain symptoms, using DTT.Thirty-five patients with central pain following mild TBI and 30 healthy control subjects were recruited for this study. After DTT-based reconstruction of the STT, we analyzed the STT in terms of configuration (narrowing and/or tearing) and the DTT parameters (fractional anisotropy and tract volume).Thirty-three (94.3%) patients had at least 1 DTT parameter value at 1 standard deviation below the control group value, and 20 (57.1%) patients had values at 2 standard deviations, below the control group value. All 35 patients showed STT abnormalities (tearing, narrowing, or both) on DTT.A high diagnostic sensitivity of TAI of the STT in patients with mild TBI was achieved. However, the small number of subjects who visited the university hospital and the limitations of DTT should be considered when generalizing the results of this study.

Relationships among language ability, the arcuate fasciculus and lesion volume in patients with putaminal hemorrhage: a diffusion tensor imaging study.

Relationships among language ability, arcuate fasciculus and lesion volume were investigated by use of diffusion tensor tractography in patients with putaminal hemorrhage. Thirty-three right-handed patients within six weeks of hemorrhage onset were recruited. Correlation of the aphasia quotient with subset (fluency, comprehension, repetition, naming) scores, diffusion tensor tractography parameters and lesion volume of patients, aphasia quotient (r = 0.446) with subset (naming: r = 0.489) score had moderate positive correlations with fractional anisotropy of the left arcuate fasciculus. The aphasia quotient subset (repetition) score had a strong positive correlation with fractional anisotropy of the left arcuate fasciculus (r = 0.520), whereas, aphasia quotient subset (fluency and comprehension) scores had no significant correlations with fractional anisotropy of the left arcuate fasciculus after Benjamini-Hochberg correction. Aphasia quotient (r = 0.668) with subset (fluency: r = 0.736, comprehension: r = 0.739, repetition: r = 0.649, naming: r = 0.766) scores had strong positive correlations with the tract volume of the left arcuate fasciculus and strong negative correlations with lesion volume (r = -0.521, fluency: r = -0.520, comprehension: r = -0.513, repetition: r = -0.518, naming: r = -0.562). Fractional anisotropy of the left arcuate fasciculus had a moderate negative correlation with lesion volume (r = -0.462), whereas the tract volume of the left arcuate fasciculus had a strong negative correlation with lesion volume (r = -0.700). According to the result of mediation analysis, tract volume of the left arcuate fasciculus fully mediated the effect of lesion volume on the aphasia quotient. Regarding the receiver operating characteristic curve, the lesion volume cut-off value was 29.17 cm3 and the area under the curve (0.74), sensitivity (0.77) and specificity (0.80) were higher than those of fractional anisotropy, tract volume and aphasia quotient cut-off values. It was found that level of language disability was related to lesion volume as well as to injury severity of arcuate fasciculus in the dominant hemisphere of patients with putaminal hemorrhage. In particular, the tract volume of the arcuate fasciculus in the dominant hemisphere fully mediated the effect of lesion volume on language ability. Additionally, a lesion volume of approximately 30 cm3 was helpful in discriminating arcuate fasciculus discontinuation in the dominant hemisphere.

Relationship between depression and dorsolateral prefronto-thalamic tract injury in patients with mild traumatic brain injury

The prefrontal lobe has been considered to be closely related to depression. This study examined the relationship between depression and three prefronto-thalamic tract (PF-TT) regions (the dorsolateral prefronto-thalamic tract [DLPF-TT], ventrolateral prefronto-thalamic tract [VLPF-TT], and the orbitofronto-thalamic tract [OF-TT]) in patients with mild traumatic brain injury (TBI), using diffusion tensor tractography (DTT). Thirty-seven patients with depression following mild TBI were recruited based on Beck Depression Inventory-II (BDI-II) scores. Thirty-one normal control subjects were also recruited. The three regions of the PF-TTs were reconstructed using probabilistic tractography and DTT parameters for each of the three PF-TT regions were determined. The tract volume of the DLPF-TT and OF-TT in the patient group showed a significant decrease compared to that of the control group (p < 0.05). The BDI-II score of the patient group showed a moderate negative correlation with the tract volume value of the right (r = − 0.33) and left (r = − 0.41) DLPF-TT (p < 0.05). On the other hand, no significant correlations were detected between the BDI-II score of the patient group and the values of the other DTT parameters values for the three PF-TT regions (p > 0.05). Using DTT, depression was found to be closely related to a DLPF-TT injury in patients with mild TBI. We believe that evaluation of the DLPF-TT using DTT would be helpful when assessing patients with depression following mild TBI. These results can provide useful information regarding the proper application of neuromodulation in the management of depression.

Injury of the optic radiation in patients with mild TBI: A DTT study.

ObjectivesWe investigated injuries of the optic radiations (ORs) in patients with mild traumatic brain injury (TBI) by using diffusion tensor tractography (DTT).MethodsFifty-two consecutive patients who complained of visual problems showed abnormal visual evoked potential (VEP) latency but no abnormality on conventional brain MRI after mild TBI, and fifty normal control subjects were recruited for this study. Subjects’ ORs were reconstructed using DTT, and three DTT parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], and tract volume) were measured for each OR.ResultsMean FA value and tract volume of the OR were significantly lower in the patient group than in the control group (p < 0.05). However, there was no significant difference in the ADC values of the OR between the patient and control groups (p > 0.05). A weak negative correlation was detected between VEP latency and OR fiber number (r = 0.204, p < 0.05).ConclusionsDTT revealed that OR injuries were not detected on the conventional brain MRI scans of patients who complained of visual problems and had abnormal VEP latency after mild TBI. Our results suggest that DTT would be a useful technique for detecting OR injury in patients with mild TBI.

Title: Injury characteristics of the Papez circuit in patients with diffuse axonal injury: a diffusion tensor tractography study.

We investigate the characteristics of injury of four portions of the Papez circuit in patients with diffuse axonal injury (DAI), using diffusion tensor tractography (DTT). Thirty-four consecutive patients with DAI and 30 normal control subjects were recruited. Four portions of the Papez circuit were reconstructed: the fornix, cingulum, thalamocingulate tract, and mammillothalamic tract. Analysis of DTT parameters [fractional anisotropy (FA) and tract volume (TV)] and configuration (narrowing, discontinuation, or non-reconstruction) was performed for each portion of the Papez circuit. The Memory Assessment Scale (MAS) was used for the estimation of cognitive function. In the group analysis, decreased fractional anisotropy and tract volume of the entire Papez circuit were observed in the patient group compared with the control group (p < 0.05). In the individual analysis, all four portions of the Papez circuit were injured in terms of DTT parameters or configuration. Positive correlation was observed between TV of the fornix and short-term memory on MAS r = 0.618, p < 0.05), and between FA of the fornix and total memory on MAS (r = 0.613, p < 0.05). We found that all four portions of the Papez circuit in the patient group were vulnerable to DAI, and among four portions of the Papez circuit, the fornix was the most vulnerable portion in terms of injury incidence and severity.

Abstract TP154: Arcuate Fasciculus Integrity and Outcome of Post-stroke Aphasia: A 6-month Follow-up DTI Study

Objectives: We evaluated the changes of arcuate fasciculus (AF), an important connecting pathway for language function, using DTI at 1-month and 6-month after stroke and investigated the relationship between structural changes of AF and improvement of post-stroke aphasia. Methods: We collected data from the STroke Outcome Prediction (STOP) database that is prospective data collecting system for functional recovery prediction after stroke based on neuroimaging study. Twenty-six patients with aphasia (PWA) who had first-ever stroke, presence of aphasia evaluated by Western Aphasia Battery (WAB) and no previous neurological or psychiatric diagnosis. The WAB and DTI data within 1 month (initial) and 6 months after (follow-up) stroke onset were used for analysis. And fractional anisotropy (FA), mean diffusivity (MD), fiber number (FN) and differences (Δ) at two time points of these parameters were obtained in bilateral AF in diffusion tensor tractography (DTT). Three types (I: not reconstructed, II: disrupted, discontinued or shallow, III: preserved) of classification according to integrity of AF was also included. Results: DTT parameters of bilateral AF showed statistically significant decrease in FA and increase in MD. Types of AF were changed in 6 patients (23%): 3 patients from type III to type II, 2 patients from type II to type I, and 1 patient from type II to type III. In Pearson’s correlation analysis, significant correlation was observed between 6-mon aphasia quotient (AQ) and parameters of left AF; positive correlation with FA (r=0.707, p&lt;0.001), and negative correlation with MD (r=-.540, p&lt;0.001). However, there was no correlation between 6-mon AQ score and FN of left AF, and all parameters of right AF. In addition, ΔDTT parameters were not correlated with either 6-mon AQ or ΔAQ. Conclusions: The AF changes over time not only in dominant but also in nondominant hemispheres in patients with aphasia after stroke. But amount of changes (Δ) in AF parameters were not associated with language recovery. Acknowledgement: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (No. 2019R1A2C2003020).

Injury of the dentatorubrothalamic tract in patients with post-traumatic tremor following mild traumatic brain injury: a case-control study.

Post-traumatic movement disorder is one of the sequelae of traumatic brain injury. The dentatorubrothalamic tract (DRTT) is reported to be involved in the control of movement. Therefore, injury of the DRTT can be accompanied by abnormal movements, including ataxia, tremor, or dystonia. We investigated DRTT injuries in 27 patients who showed post-traumatic tremor in at least one of four extremities following mild traumatic brain injury. We classified DRTT injuries based on diffusion tensor tractography parameters and configuration: type A: the DRTT showed narrowing, type B: the DRTT showed partial tearing, and type C: the DRTT showed discontinuation. Fractional anisotropy and fiber number of the DRTT were significantly decreased in patients compared with the healthy controls. Based on our DRTT injury classification, among the 54 hemispheres of the 27 patients, type A injury occurred in 22 hemispheres (40.7%) of 17 patients, type B injury was present in 15 hemispheres (27.7%) of 10 patients, and type C injury was observed in 8 hemispheres (14.8%) of 6 patients. Our results suggest that diffusion tensor tractography-based evaluation of the DRTT would be useful when determining cause of post-traumatic tremor in patients with mild traumatic brain injury. The study protocol was approved by the Institutional Review Board of Yeungnam University Hospital (YUMC-2018-09-007) on September 5, 2018.

Difference in Injury of the Corticospinal Tract and Spinothalamic Tract in Patients with Putaminal Hemorrhage

Purpose: We investigated the difference in injury of the corticospinal tract (CST) and the spinothalamic tract (STT) in patients with pu ­taminal hemorrhage, using diffusion tensor tractography (DTT). Methods: Thirty one consecutive patients with PH and 34 control subjects were recruited for this study. DTT scanning was performed at early stage of PH (7-63 days), and the CST and STT were reconstructed using the Functional Magnetic Resonance Imaging of Brain (FM ­RIB) Software Library program. Injury of the CST and STT was defined in terms of the configuration or abnormal DTT parameters was more than 2 standard deviations lower than that of normal control subjects. Results: Among 31 patients, all 31 patients (100%) had injury of the CTS, whereas 25 patients (80.6%) had injury of the STT: the inci­ dence of CST injury was significantly higher than that of STT (p<0.05). In detail, 20 (64.5%) of 31 patients showed a discontinuation of the CST in the affected hemisphere; in contrast, 14 patients (45.2%) of 31 patients showed a discontinuation of the STT in the affected hemisphere. Regarding the FA value, 6 (19.4%) of 31 patients and 2 (6.4%) of 31 patients were found to have injury in the CST and STT, respectively. In terms of the fiber number, the same injury incidence was observed in 11 patients (35.5%) in both the CST and STT. Conclusion: The greater vulnerability of the CST appears to be ascribed to the anatomical characteristics; the CST is located anteriorly to the center of the putamen compared with the STT.

Difference between injuries of the corticospinal tract and corticoreticulospinal tract in patients with diffuse axonal injury: a diffusion tensor tractography study

Objectives: No studies have investigated differences in injury of the corticospinal tract (CST) and corticoreticulospinal tract (CRT) following diffuse axonal injury (DAI) to date. Therefore, we investigated differences in injury of the CST and CRT in patients with DAI using diffusion tensor tractography (DTT).Methods: Twenty consecutive patients with DAI and 20 control subjects were recruited. CST and CRT were reconstructed. Each part of the CST and CRT was analyzed in terms of DTT parameters and configuration.Results: Upon group analysis, decreased FA and TV values were observed in both the CST and CRT in the patient group compared with the control group (%) (p < .05). In the individual analysis in terms of the TV, significantly higher injury incidence was observed for the CRT (47.5%) than the CST (25.0%) (p < .05). Evaluation of the DTT configuration revealed significantly higher injury incidence for the CRT (50.0%) than the CST (17.5%) (p < .05). Specifically, the incidence of discontinuation was significantly higher for the CRT (40.0%) than the CST (10.0%) (p < .05).Conclusions: Injury of the CST and CRT was detected in patients with DAI using DTT. In terms of the incidence and severity of neural injury, the CRT appeared to be more vulnerable to DAI than the CST.

Relationship Between Impaired Consciousness and Injury of Ascending Reticular Activating System in Patients With Intracerebral Hemorrhage.

Background and Purpose- We investigated the relationship between impaired consciousness and ascending reticular activating system (ARAS) characteristics on diffusion tensor tractography during the early stage of spontaneous intracerebral hemorrhage confined to a unilateral supratentorial area. Methods- A total of 29 consecutive patients with impaired consciousness (the patient group A), 31 age- and sex-matched patients without impaired consciousness (the patient group B), and 20 age- and sex-matched healthy control subjects were recruited. The Glasgow Coma Scale was used to evaluate patients' conscious state in the early stage of intracerebral hemorrhage (within 30 days after onset). Three parts of the ARAS (lower dorsal, lower ventral, and upper) were reconstructed, and fractional anisotropy and tract volume values were determined. Results- The tract volume value of the lower dorsal ARAS in the patient group A was significantly lower than those of the patient group B and control group in the affected hemisphere (P<0.05). Among the diffusion tensor tractography parameters, only the tract volume of the lower dorsal ARAS in the affected hemispheres of the patient group A had a moderate positive correlation with Glasgow Coma Scale score (r=0.456; P<0.05). Conclusions- Impaired consciousness during the early stage of intracerebral hemorrhage was closely related to injury of the lower dorsal ARAS in the affected hemisphere. Clinical Trial Registration- URL: http://www.e-irb.com/index.jsp. Unique identifier: 2015-07-064.

Deterioration of Brain Neural Tracts in Elderly Women with Sarcopenia

Sarcopenia is known to be associated with increased stiffness in brain arteries, which causes deterioration in brain structure and function. In this study, the authors evaluated the deterioration of neural tracts using diffusion tensor tractography (DTT) in elderly women with sarcopenia and investigated whether deterioration of neural tracts is consistent with clinical findings. Twenty elderly women with sarcopenia were recruited. Muscle mass was measured by dual energy x-ray absorptiometry. Hand-grip power and gait speed were also assessed. Memory function was evaluated using the Seoul Neuropsychological Screening Battery. Additionally, using DTT-Studio software, the authors evaluated eight neural tracts: the corticospinal tract (CST), corticoreticular pathway, fornix, cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and optic radiation. The authors measured the DTT parameters (fractional anisotropy [FA] and fiber volume [FV]) for each neural tract. The FA and FV values were decreased in all the evaluated neural tracts, compared with those of the 20 normal comparison subjects. The FVs of the CST were significantly correlated with the hand-grip power of elderly women with sarcopenia. The FVs of the fornix and cingulum in elderly women with sarcopenia were significantly correlated with their memory function. The authors found that the neural tracts in elderly women with sarcopenia were extensively deteriorated, and their hand-grip power and memory function were associated with related neural tracts. The DTT seems to be a useful tool for evaluating structural changes in the brains of people with sarcopenia.

Traumatic axonal injury of the cingulum in patients with mild traumatic brain injury: a diffusion tensor tractography study.

The cingulum, connecting the orbitofrontal cortex to the medial temporal lobe, involves in diverse cognition functions including attention, memory, and motivation. To investigate the relationship between the cingulum injury and cognitive impairment in patients with chronic mild traumatic brain injury, we evaluated the integrity between the anterior cingulum and the basal forebrain using diffusion tensor tractography in 73 patients with chronic mild traumatic brain injury (39 males, 34 females, age 43.29 ± 11.42 years) and 40 healthy controls (22 males, 18 females, age 40.11 ± 16.81 years). The patients were divided into three subgroups based on the integrity between the anterior cingulum and the basal forebrain on diffusion tensor tractography: subgroup A (n = 19 patients) – both sides of the anterior cingulum were intact; subgroup B (n = 36 patients) – either side of the anterior cingulum was intact; and subgroup C (18 patients) – both sides of the anterior cingulum were discontinued. There were significant differences in total Memory Assessment Scale score between subgroups A and B and between subgroups A and C. There were no significant differences in diffusion tensor tractography parameters (fractional anisotropy, apparent diffusion coefficient, and fiber volume) between patients and controls. These findings suggest that the integrity between the anterior cingulum and the basal forebrain, but not diffusion tensor tractography parameter, can be used to predict the cognitive function of patients with chronic mild traumatic brain injury. This study was approved by Yeungnam University Hospital Institutional Review Board (approval No. YUMC-2014-01-425-010) on August 16, 2017.

Relation Between Memory Impairment and the Fornix Injury in Patients With Mild Traumatic Brain Injury: A Diffusion Tensor Tractography Study.

We investigated the relation between memory impairment and the fornix injury in patients with mild traumatic brain injury, using diffusion tensor tractography. Eighty-six chronic patients with mild traumatic brain injury and 50 normal control subjects were recruited. Fractional anisotropy and fiber volume were measured for each reconstructed fornix. The patients were classified according to the following three types: type A (47 patients), intact integrity of both fornical crura; type B (27 patients), showed a discontinuation in either fornical crus; and type C (12 patients), discontinuations in both fornical crura. The Memory Assessment Scale was used for evaluation of memory function. Fractional anisotropy and fiber volume showed weak positive correlations with global memory of Memory Assessment Scale, respectively (r = 0.303, P = 0.006; r = 0.271, P = 0.014). Significant difference in the global memory of Memory Assessment Scale was observed between type A and B and between type A and C without difference between type B and C (P < 0.05). It seems that the diffusion tensor tractography parameters of the fornix and the integrity of fornical crus can be used as a biomarker for axonal injury of the fornix in patients with mild traumatic brain injury.

Diffusion-Tensor Tractography of the Auditory Neural Pathway : Clinical Usefulness in Patients with Unilateral Sensorineural Hearing Loss.

The purpose of this study was to evaluate the structural integrity of the auditory neural pathway in patients with unilateral sensorineural hearing loss using quantitative diffusion-tensor tractography. Diffusion-tensor tractography imaging was performed using a3T magnetic resonance imaging system to evaluate structural alterations in the auditory neural pathway of patients with unilateral sensorineural hearing loss. The two diffusion-tensor tractography parameters, fractional anisotropy and the apparent diffusion coefficient were compared between the ipsilateral side and the contralateral side in patients and controls. Additionally, correlations between the parameter values and the hearing loss level in patients were evaluated. A total of 24 sensorineural hearing loss patients (14males; age range, 17-65years; average age, 45.3 years) and 24age and sex-matched control subjects were enrolled. Fractional anisotropy values on the ipsilateral and contralateral sides were significantly lower in patients than in the control group (p = 0.004 and 0.001, respectively). The differences in the apparent diffusion coefficient values for the ipsilateral and contralateral sides between the two groups were not significant (p = 0.279 and 0.248, respectively). There was an inverse relationship between fractional anisotropy and the severity of hearing impairment on the ipsilateral and contralateral sides (r = -0.519, p = 0.005 and r = -0.454, p = 0.015, respectively). No significant correlation was found between the apparent diffusion coefficient and hearing loss level on the ipsilateral and contralateral sides (r = 0.172, p = 0.380 and r = 0.131, p = 0.508, respectively). Quantitative diffusion-tensor tractography can be used to detect microstructural alterations in the auditory neural pathway in sensorineural hearing loss patients with normal results in standard imaging studies.

The Ipsilateral Vestibulothalamic Tract in the Human Brain.

Although there are a few studies of portions of the vestibular system such as the vestibulocerebellar tract and the neural connectivity of the vestibular nuclei (VN), no study of the ipsilateral vestibulothalamic tract (VTT) (originating from the VN and mainly connecting to the lateral thalami nuclei) has been reported. In the current study, using diffusion tensor tractography (DTT), we investigate the reconstruction method and characteristics of the ipsilateral VTT in normal subjects. Thirty-three subjects were recruited for this study. For the ipsilateral VTT, the seed region of interest (ROI) was placed on the VN, which was isolated on the FA map using adjacent structures as follows: the reticular formation (anterior boundary), posterior margin of medulla and pons (posterior boundary), medial lemniscus (medial boundary) and restiform body (lateral boundary). The target ROI was placed at the lateral thalamic nuclei using known anatomical locations. The DTT parameters of the ipsilateral VTT were measured. The ipsilateral VTTs that originated from the vestibular nuclei ascended postero-laterally to the upper pons and antero-medially to the upper midbrain via the medial longitudinal fasciculus, and terminated the lateral thalamic nuclei. No significant differences were observed in DTT parameters of the ipsilateral VTT between the right and left hemispheres (p > 0.05). Using DTT, we reconstructed the ipsilateral VTT and observed the anatomical characteristics of the ipsilateral VTT in normal subjects. We believe that the methodology and results in this study could be helpful to researchers and clinicians in this field.

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

Background and objectiveDiffusion 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.MethodA 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.ResultsAn 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.ConclusionThis 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.

Diffusion Tensor Tractography for Detection of Concomitant Traumatic Brain Injury in Patients With Traumatic Spinal Cord Injury.

We investigated concomitant traumatic brain injury in patients with traumatic spinal cord injury (TSCI) who had head trauma history, using diffusion tensor tractography (DTT). Retrospective survey. We recruited 14 consecutive patients with TSCI and coexisting head trauma history at the time of TSCI and 30 control subjects. The corticospinal tract (CST), corticoreticulospinal tract (CRT), cingulum, and fornix were reconstructed using DTT, and DTT parameters (fractional anisotropy and fiber volume) and configuration were estimated. The values of fractional anisotropy and fiber volume in the CST, CRT, cingulum, and fornix of the patient group were significantly lower than those of the control group (P < .05). On configurational analysis of DTT for each tract, the neural tracts for motor function (the CST and CRT) had more injury than the neural tracts for cognitive function (the cingulum and fornix). No association between the severity of TSCI and traumatic brain injury was observed in terms of DTT parameters. Using DTT, we found injury of the neural tracts in patients with head trauma history at the time of TSCI. Our results suggest that brain evaluation using DTT can be recommended for the patients with head trauma history at the time of TSCI irrespective of the results of conventional brain MRI.