Diffusion imaging concepts for clinicians

Visual Pathway Recovery Post Pituitary Adenoma Surgery: Insights from Retinal Structure, Vascular Density, and Neural Conduction Analysis

INTRODUCTION

This study investigates how surgery for pituitary adenoma (PA) affects the visual pathway, examining changes in the retina, blood vessel density, and nerve function. Since PAs often impair vision as a result of their location near visual structures, this research is key to understanding and improving vision recovery after surgery.

METHODS

Our study is based on a retrospective analysis of the historical data of 28 patients diagnosed with pituitary adenomas. We conducted assessments by reviewing preoperative and postoperative imaging records. These included optical coherence tomography (OCT) for retinal structure analysis, diffusion tensor imaging (DTI) for neural transmission evaluation, and optical coherence tomography angiography for assessing blood vessel density. These tools allowed for a detailed understanding of the structural and functional changes within the visual pathway following PA surgery.

RESULTS

OCT findings show postoperative changes in the eye: thinning in average and nasal circumpapillary retinal nerve fiber layer, thickening in macular central 1 mm inner plexus layer, ganglion cell complex, and nasal retinal nerve fiber layer. DTI reveals increased fractional anisotropy (FA) in the left optic chiasm and posterior optic nerve, decreased mid-segment optic nerve FA, and increased apparent diffusion coefficient (ADC) in the right optic chiasm and nerve segments. Early postoperative reduction in radial peripapillary capillaries plexus density is noted. Preoperative ganglion cell layer (GCL) thickness correlates with postoperative visual radiation FA and ADC values, especially in the inferior quadrant. A negative correlation exists between preoperative GCL thickness and postoperative visual field mean defect values, particularly on the temporal side and superior inner ring. All changes are statistically significant (P < 0.05).

CONCLUSIONS

The study finds that surgery for PA has varied effects on vision. Early post surgery, there are changes in the retina and nerve signals. Macular GCL thickness before surgery might predict early visual recovery, influencing future research and treatment for vision issues related to PA.

Biogenic Imaging Contrast Agents

Imaging contrast agents are widely investigated in preclinical and clinical studies, among which biogenic imaging contrast agents (BICAs) are developing rapidly and playing an increasingly important role in biomedical research ranging from subcellular level to individual level. The unique properties of BICAs, including expression by cells as reporters and specific genetic modification, facilitate various in vitro and in vivo studies, such as quantification of gene expression, observation of protein interactions, visualization of cellular proliferation, monitoring of metabolism, and detection of dysfunctions. Furthermore, in human body, BICAs are remarkably helpful for disease diagnosis when the dysregulation of these agents occurs and can be detected through imaging techniques. There are various BICAs matched with a set of imaging techniques, including fluorescent proteins for fluorescence imaging, gas vesicles for ultrasound imaging, and ferritin for magnetic resonance imaging. In addition, bimodal and multimodal imaging can be realized through combining the functions of different BICAs, which helps overcome the limitations of monomodal imaging. In this review, the focus is on the properties, mechanisms, applications, and future directions of BICAs.

Neural Injury of the Dopaminergic Pathways in Patients with Middle Cerebral Artery Territory Infarct: A Diffusion Tensor Imaging Study

The mesocortical tract (MCT) and mesolimbic tract (MLT), dopaminergic pathways originating from the ventral tegmental area in the midbrain to the ventral striatum (nucleus accumbens) and prefrontal cortex, play a crucial role in regulating incentive salience. This study aimed to investigate the potential changes in the MCT and MLT pathways following ischemic stroke, such as middle cerebral artery (MCA) infarction. We enrolled thirty-six patients with MCA infarction and forty healthy individuals with no history of psychiatric or neurological disorders. Using diffusion tensor tractography, we examined the injury to the affected and unaffected MCT and MLT pathways in patients with MCA infarction, comparing them to the control group. Our findings revealed a significant difference in the mean values of fractional anisotropy (FA) and tract volume (TV) of the MCT and MLT pathways between the patient and control groups (p < 0.05). Specifically, the mean FA of the MCT and MLT showed a decrease of 7.94% and 6.33%, respectively, in the affected side compared to the control group (p < 0.05). Similarly, the mean TV of the MCT and MLT showed a decrease of 73.22% and 78.79%, respectively, in the affected side compared to the control group (p < 0.05). These changes were significantly different from those of the unaffected MCT, MLT, and control groups (p < 0.05). Our study suggests that MCA infarction can cause significant damage to the affected MCT and MLT pathways, potentially contributing to our understanding of the pathophysiology of post-stroke depression.

Diffusion tensor tractography of the corticobulbar tract in a dysphagic patient with progressive supranuclear palsy: A case report

RATIONALE

This paper reports the changes over time in the corticobulbar tract (CBT) analyzed using diffusion tensor tractography (DTT) in a dysphagic patient with progressive supranuclear palsy (PSP).

PATIENT CONCERNS

A 53-year-old man initially presented with dysarthria, gait disturbance, and bradykinesia, and approximately 1-year later, downward gaze paralysis appeared. Initially, there was no dysphagia; however, approximately 2 years after visiting the hospital, symptoms of dysphagia, including difficulty swallowing pills, aspiration, and oral movement impairments appeared. The symptoms gradually progressed, and finally, mouth opening was severely damaged to the extent that it was difficult to orally feed.

INTERVENTIONS

We performed diffusion tensor imaging 3 times; at 3-month, 20-month, and 41-month from onset.

OUTCOMES

On 3-month DTT, the left CBT was well reconstructed, whereas the right CBT showed partial tearing. In the 20-month DTT, both CBTs became thinner compared to the 3-month DTT. On 41-month DTT, both CBTs became much thinner than after 3-month and 20-month DTT.

LESSONS

We observed the degree of CBT injury over time in a dysphagic patient with PSP. These results suggest that the analysis of CBT using DTT is helpful in predicting the degree of dysphagia and prognosis in patients with PSP.

Diffusion Tensor Tractography Studies on Recovery Mechanisms of Aphasia in Stroke Patients: A Narrative Mini-Review

Aphasia is a common and serious clinical feature of stroke. Various neural tracts are known to be involved in language processing. Diffusion tensor tractography (DTT) appears to be an appropriate imaging technique for the elucidation of the recovery mechanisms of aphasia in the language-related neural tracts in stroke patients. In this article, twelve previous DTT-based studies on the recovery mechanisms of aphasia in stroke were reviewed. We classified the twelve studies into the following three categories according to the recovery mechanisms: recovery via the neural tracts in the dominant hemisphere (eight studies), via transcallosal fibers (two studies), and via the neural tracts in the non-dominant hemisphere (two studies). Although there are various neural tracts for language processing, eight of the ten studies focused only on the role of the arcuate fasciculus (AF) in the recovery process. Consequently, it appears from the studies that only one recovery mechanism of aphasia via the restoration of the integrity of the injured AF in the dominant hemisphere was clearly demonstrated. However, because various neural tracts are involved in language processing, there could be other mechanisms that have not yet been elucidated. Therefore, further original studies involving a larger number of patients with aphasia in stroke should be encouraged forthwith. Further studies involving various lesion locations and severity levels of injuries to the language-related neural tracts are also necessary because the recovery mechanisms of aphasia in stroke could be dependent on these factors.

Relationship between hyperhidrosis and hypothalamic injury in patients with mild traumatic brain injury

Hyperhidrosis is clinical symptom of various diseases and is an important clinical feature of paroxysmal sympathetic hyperactivity (PSH). Traumatic brain injury (TBI) is known to be most common condition associated with PSH, and PSH has been mainly reported in moderate and severe TBI. However, very little has been reported on PSH or hyperhidrosis in mild TBI patients. In this study, we used diffusion tensor imaging (DTI) to investigate the relationship between hyperhidrosis and hypothalamic injury in patients with mild TBI. Seven patients with hyperhidrosis after mild TBI and 21 healthy control subjects were recruited for this study. The Hyperhidrosis Disease Severity Scale was used for evaluation of sweating at the time of DTI scanning. The fractional anisotropy and apparent diffusion coefficient DTI parameters were measured in the hypothalamus. In the patient group, the fractional anisotropy values for both sides of the hypothalamus were significantly lower than those of the control group (P < .05). By contrast, the apparent diffusion coefficient values for both sides of the hypothalamus were significantly higher in the patient group than in the control group (P < .05). In conclusion, we detected hypothalamic injuries in patients who showed hyperhidrosis after mild TBI. Based on the results, it appears that hyperhidrosis in patients with mild TBI is related to hypothalamic injury.

Limb Length Discrepancy and Corticospinal Tract Disruption in Hemiplegic Cerebral Palsy

This study aimed to investigate the relationship between the corticospinal tract (CST) and limb length discrepancy (LLD) in patients with hemiplegic cerebral palsy (CP). Using diffusion tensor tractography, a retrospective study on 92 pediatric patients with hemiplegic CP who visited our hospital from May 2017 to the end of 2020 was conducted. Limb length was measured by anthropometry to calculate LLD. The functional level of hemiplegia scale (FxL), modified Ashworth scale, and manual muscle test (MMT) were evaluated for clinical function. Patients were classified into two groups according to the presence or absence of disruption of the affected CST: disruption (A) and preservation (B) groups. Fractional anisotropy (FA) and mean diffusivity (MD) of the affected CSTs were measured and correlated with LLD. The results of the independent t-test and chi-square test did not show significant differences between the two groups, except in the FxL and finger extensor of MMT (p < 0.05). For the LLD, there were no significant differences in total upper, total lower, and foot limb lengths. A significant difference was observed only in hand LLD (p < 0.05) from ANCOVA. Hand LLD was significantly correlated with FA (r = −0.578), MD (r = 0.512), and degree of CST disruption (r = −0.946) from the Pearson correlation test. The results of this study suggested that patients with hemiplegic CP would likely have LLD especially in the hand, and that CST evaluation using diffusion tensor tractography might be helpful in assessing and predicting LLD in hemiplegic CP.

Neuroimaging of structural and functional connectivity in preterm infants with intraventricular hemorrhage

Preterm infants with intraventricular hemorrhage (IVH) are known to have some of the worst neurodevelopmental outcomes in all of neonatal medicine, with a growing body of evidence relating these outcomes to underlying disruptions in brain structure and function. This review begins by summarizing state-of-the-art neuroimaging techniques delineating structural and functional connectivity (diffusion and resting state functional MRI) and their application in infants with IVH, including unique technical challenges and emerging methods. We then review studies of altered structural and functional connectivity, highlighting the role of IVH severity and location. We subsequently detail investigations linking structural and functional findings in infancy to later outcomes in early childhood. We conclude with future directions including methodologic considerations for prospective and potentially interventional studies designed to mitigate disruptions to underlying structural and functional connections and improve neurodevelopmental outcomes in this high-risk population.

Role of the Contra-Lesional Corticoreticular Tract in Motor Recovery of the Paretic Leg in Stroke: A Mini-Narrative Review

This review discusses the role of the contra-lesional corticoreticular tract (CRT) in motor recovery of the paretic leg in stroke patients by reviewing related diffusion tensor tractography studies. These studies suggest that the contra-lesional CRT can contribute to the motor recovery of the paretic leg in stroke patients, particularly in patients with complete injuries of the ipsilesional corticospinal tract and CRT. Furthermore, a review study reported that the motor recovery of the paretic ankle dorsiflexor, which is mandatory for achieving a good gait pattern without braces in hemiparetic stroke patients, was closely related to the contra-lesional CRT. These results could be clinically important in neuro-rehabilitation. For example, the contra-lesional CRT could be a target for neuromodulation therapies in patients with complete injuries of the ipsilesional corticospinal tract and CRT. On the other hand, only three studies were reviewed in this review and one was a case report. Although the CRT has been suggested to be one of the ipsilateral motor pathways from the contra-lesional cerebral cortex to the paretic limbs in stroke, the role of the CRT has not been elucidated clearly. Therefore, further prospective follow-up studies combining functional neuroimaging and transcranial magnetic stimulation for the paretic leg with diffusion tensor tractography will be useful for elucidating the role of the contra-lesional CRT in stroke patients.

Deterioration of the Corticobulbar Tract in Older Dysphagic Patients Without Neurologic Diseases

OBJECTIVES

Less is known how dysphagia affects older patients without neurologic diseases and whether the symptoms of dysphagia have any association with impaired central control of swallowing. This study investigated the state of the corticobulbar tract, the surrogate marker for the central control of swallowing, in older dysphagic patients without any neurologic diseases, using diffusion tensor tractography.

DESIGN

This retrospective observational study was conducted at a tertiary university hospital including 10 patients 60 yrs or older with oropharyngeal dysphagia without neurological disease and 11 age- and sex-matched control participants. The corticobulbar tract was reconstructed, and the fractional anisotropy and tract volume were measured using diffusion tensor tractography.

RESULTS

The corticobulbar tracts of the dysphagia group were narrowed and not reconstructed by their configurations and had lower fractional anisotropy and tract volume values when compared with those of control group. Significant asymmetry between the left and the right corticobulbar tract hemispheres was found in the dysphagia group, whereas no asymmetry was found in the control group.

CONCLUSIONS

A deteriorated corticobulbar tract could be associated with the development of dysphagia in older adults without neurological diseases. Our findings might help establish more appropriate treatment strategies, such as targeted neuromodulation therapies in the future.

Structural connectivity associated with familial risk for mental illness: A meta‐analysis of diffusion tensor imaging studies in relatives of patients with severe mental disorders

Schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD) are heritable conditions with overlapping genetic liability. Transdiagnostic and disorder‐specific brain changes associated with familial risk for developing these disorders remain poorly understood. We carried out a meta‐analysis of diffusion tensor imaging (DTI) studies to investigate white matter microstructure abnormalities in relatives that might correspond to shared and discrete biomarkers of familial risk for psychotic or mood disorders. A systematic search of PubMed and Embase was performed to identify DTI studies in relatives of SCZ, BD, and MDD patients. Seed‐based d Mapping software was used to investigate global differences in fractional anisotropy (FA) between overall and disorder‐specific relatives and healthy controls (HC). Our search identified 25 studies that met full inclusion criteria. A total of 1,144 relatives and 1,238 HC were included in the meta‐analysis. The overall relatives exhibited decreased FA in the genu and splenium of corpus callosum (CC) compared with HC. This finding was found highly replicable in jack‐knife analysis and subgroup analyses. In disorder‐specific analysis, compared to HC, relatives of SCZ patients exhibited the same changes while those of BD showed reduced FA in the left inferior longitudinal fasciculus (ILF). The present study showed decreased FA in the genu and splenium of CC in relatives of SCZ, BD, and MDD patients, which might represent a shared familial vulnerability marker of severe mental illness. The white matter abnormalities in the left ILF might represent a specific familial risk for bipolar disorder.

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.

Ataxia due to injury of the cortico-ponto-cerebellar tract in patients with mild traumatic brain injury

INTRODUCTION

The cortico-ponto-cerebellar tract (CPCT) is involved in coordination of movement; injury of the CPCT can therefore be accompanied by ataxia. In this study, using diffusion tensor tractography (DTT), we investigated injury of the CPCT in patients with mild traumatic brain injury (TBI).

METHODS

We recruited 45 consecutive patients with ataxia following mild TBI and 20 normal control subjects. The score of assessment and rating of ataxia (SARA) was used to evaluate of ataxia. The patients were classified into 2 groups based on the SARA; patient group A had with post-traumatic ataxia and patient group B had without post-traumatic ataxia. The fractional anisotropy (FA) value and fiber number (FN) of the CPCT was measured.

RESULTS

Significant differences were observed in the FA and FN values of the CPCT between patient group A and the control group and between patient groups A and B (P < .05). In addition, a significant difference was observed in the FA value only of the CPCT between patient group B and the control group (P < .05). However, no significant difference was observed in the FN value of the CPCT between patient group B and the control group (P > .05).

CONCLUSION

By using DTT, injury of the CPCT was demonstrated in patients who showed ataxia following mild TBI. These results suggest that DTT would be useful for evaluation of the CPCT in patients with ataxia after mTBI because mTBI usually does not show any abnormalities on conventional brain MRI.

Associations Between Injury of the Parieto-Insular Vestibular Cortex and Changes in Motor Function According to the Recovery Process: Use of Diffusion Tensor Imaging

Background and Purpose: Parieto-insular vestibular cortex (PIVC) injury can cause symptoms such as abnormal gait and affects the integration and processing of sensory inputs contributing to self-motion perception. Therefore, this study investigated the association of the vestibular pathway in the gait and motor function recovery process in patients with PIVC injury using diffusion tensor imaging (DTI).

Methods: We recruited 28 patients with stroke with only PIVC injury and reconstructed the PIVC using a 1.5-T scanner for DTI. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. The functional ambulatory category (FAC) test was conducted, and motricity index (MI) score was determined. These were conducted and determined at the start (phase 1), end of rehabilitation (phase 2), and during the follow-up 6 months after onset.

Results: Although the tract volume of PIVC showed a decrease in subgroup A, all of DTI parameters were not different between two subgroups in affected side (p > 0.05). The results of MI and FAC were significantly different according to the recovery process (p < 0.05). In addition, FA of the PIVC showed a positive correlation with FAC in phase 2 of the recovery process on the affected side. On the unaffected side, FA of the PIVC showed a significant negative correlation with MI in all processes (p < 0.05).

Conclusion: The degree of projection pathways to PIVC injury at onset time seems to be related to early restoration of gait function. Moreover, we believe that early detection of the projection pathway for PIVC injury using DTI would be helpful in the clinical evaluation and prediction of the prognosis of patients with PIVC injury.

Structural and functional connectivity in premature neonates

Advances in neuroimaging have increasingly enabled researchers to investigate whether alterations in brain development commonly identified in preterm infants underlie their high risk of long-term neurodevelopmental impairment, including sensory, motor, cognitive, and psychiatric deficits. This review begins by examining the growing body of literature utilizing advanced magnetic resonance imaging (MRI) techniques to probe structural (via diffusion MRI) and functional (via resting state-functional MRI) connectivity development in the preterm brain during the neonatal period, both in the presence and absence of brain injury. It then details the recent work linking neonatal brain connectivity measures to neurodevelopmental and psychiatric outcomes in prematurely-born cohorts. Finally, building upon the recent substantive growth in the utilization of these neuroimaging modalities, it concludes by highlighting areas in which continued optimization of age-specific acquisition and analysis techniques for these data remains necessary, efforts fundamental to advancing the field toward establishing individual-level predictive capabilities in this high-risk population.

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.

Delayed development of aphasia related to degeneration of the arcuate fasciculus in the dominant hemisphere nine years after the onset in a patient with intracerebral hemorrhage: a case report

Background

We report on a patient with an intracerebral hemorrhage (ICH), who showed delayed development of aphasia, which was demonstrated via follow up diffusion tensor tractography (DTT) to be related to neural degeneration of the arcuate fasciculus (AF).

Case presentation

A 51-year-old, right-handed male presented with right hemiparesis, which occurred at the onset of a spontaneous ICH in the left corona radiata and basal ganglia. Brain magnetic resonance images showed a hematoma in the left subcortical area at one month after onset and hemosiderin deposits in the left subcortical area at nine years after onset. At four weeks after onset, he exhibited severe aphasia, and Western Aphasia Battery (WAB) testing revealed an aphasia quotient in the 39.6 percentile (%ile). However, his aphasia improved to nearly a normal state, and at three months after onset, his aphasia quotient was in the 90.5 %ile. At approximately eight years after onset, he began to show aphasia, and his aphasia increased slowly with time resulting in a WAB aphasia quotient in the 12.5 %ile at nine years after onset. The integrity of the left AF over the hematoma was preserved on 1-month post-onset DTT. However, the middle portion of the left AF in the middle of the hemosiderin deposits showed discontinuation on 9-year post-onset DTT. The fractional anisotropy value of the left AF was higher on the 9-year post-onset DTT (0.48) than that on the 1-month post-onset DTT (0.35), whereas the mean diffusivity value was lower on the 9-year post-onset DTT (0.10) than that on the 1-month post-onset DTT (0.32). The fiber number of the left AF was decreased to 175 on the 9-year post-onset DTT from 239 on the 1-month post-onset DTT.

Conclusions

We report on a patient with ICH who showed delayed development of aphasia, which appeared to be related to degeneration of the AF in the dominant hemisphere. Our results suggest that DTT would be useful in ruling out neural degeneration of the AF.

Peri-hematoma corticospinal tract integrity in intracerebral hemorrhage patients: A diffusion-tensor imaging study

BACKGROUND

The impact of perihematoma edema in Intracerebral Hemorrhage (ICH) on white matter integrity is uncertain. Fractional Anisotropy (FA), as measured with Diffusion Tensor Imaging (DTI), can be used to assess white matter microstructure. We tested the hypotheses that sections of the Corticospinal Tract (CST) passing through perihematoma edema would 1) have low FA relative to the contralateral CST and 2) would predict NIHSS motor score in ICH patients.

METHODS

Patients were prospectively imaged with DTI at 48 h and 7 days after onset. Edema volume/extent was measured on CT at baseline and 24 h. FA, mean, axial and radial diffusivity were measured in the perihematoma edema, contralateral CST and sections of CST passing through the edema ('edematous CST').

RESULTS

Patients (n = 27, mean age 67 ± 13) were scanned with DTI at a median (IQR) of 42.3 (24.5) hours and 7.7 (1.8) days from onset. Median acute ICH volume was 8.8 (22) ml. FA in edematous CST at 72 h was decreased (0.37 ± 0.03) relative to contralateral CST (0.52 ± 0.06; p < 0.0001). Day 7 FA in edematous CST (0.35 ± 0.08) was also decreased compared to contralateral CST (0.54 ± 0.06; p < 0.0001). FA remained stable between 72 h (0.37 ± 0.03) and day 7 (0.35 ± 0.07; p = 0.350). FA at 72 h (ρ = -0.22, p = 0.420) and day 7 (ρ = -0.14, p = 0.624) was unrelated to 90-day motor score.

CONCLUSIONS

FA is decreased in the CST where it passes through the edema. Decreased FA in the edematous CST remained stable over time, was unrelated to motor score, and may represent water infiltration into the tracts rather than axonal injury.

Chronic pontine strokes: Diffusion tensor imaging of corticospinal tract indicates the prognosis in terms of motor outcome

OBJECTIVE

To investigate relationship between the diffusion indexes of corticospinal tract (CST) and the neurological motor outcomes in chronic pontine stroke patients.

METHODS

Diffusion tensor imaging (DTI) is performed in 27 patients with chronic pontine stroke. Fractional anisotropy (FA) values along the CST area, the track number, and the CST length are measured. Neurological and motor outcomes are evaluated based on Fugl-meyer (FM), National Institutes of Health Stroke Scale (NIHSS), Barthel index (BI), and modified Rankin scale (mRS) scores. The relationships between FA ratios (rFAs) in the CST of stroke subjects and their clinical motor scores are analyzed through Spearman's correlation analysis. Then, diffusion tensor tractography (DTT) is performed to show the injury degree of CST.

RESULTS

First, FA values are decreased in the infarct area, cerebral peduncle, posterior limb of the internal capsule, and precentral gyrus compared with those in the contralateral side. The number of CST is decreased in the ipsilateral side of the infarct. Second, rFAs in the cerebral peduncle, posterior limb of the internal capsule, and CST rnum correlate positively with FM scores (r = 0.824, 0.672, 0.651, p < 0.001) and negatively with mRS scores (r = -0.835, -0.604, -0.645, p≤0.001). Third, the injury degree of CST correlates negatively with FM scores (r = -0.627, p < 0.001).

CONCLUSIONS

The study demonstrates that rFAs in the cerebral peduncle, posterior limb of the internal capsule, and CST rnum associate with motor outcome, suggesting that DTI may be applicable for outcome evaluation.

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

Objectives

We investigated injuries of the optic radiations (ORs) in patients with mild traumatic brain injury (TBI) by using diffusion tensor tractography (DTT).

Methods

Fifty-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.

Results

Mean 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).

Conclusions

DTT 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.

Prefronto-thalamic tract injury and cognitive outcome according to external ventricular drainage location in stroke patients

OBJECTIVES

We investigated the characteristics of prefronto-thalamic tract (PF-TT) injuries in stroke patients using diffusion tensor tractography (DTT) and assessing cognitive outcome according to location of the external ventricular drainage (EVD).

METHODS

Forty-five consecutive stroke patients who underwent EVD and 24 control subjects were recruited. The patients were classified into three groups: group A (EVD on the lesion or one side, 17 patients), group B (EVD on the hemisphere opposite to the lesion, 12 patients), and group C (EVD on both sides, 16 patients). Mini-Mental State Examination (MMSE) results were performed at the beginning (average 2.27 months from onset) and end (average 4.19 months from onset) of rehabilitation. Three parts of the PF-TT (dorsolateral PF-TT[DLPF-TT], ventrolateral PF-TT[VLPF-TT], orbitofronto-thalamic tract[OF-TT]) were reconstructed and the fractional anisotropy (FA) and tract volume (TV) measurements were obtained.

RESULTS

With the EVD on the stroke-affected side, the values of FA and TV of all three parts of the PF-TTs in three patient groups were lower than those of the control group (p < 0.05). With the EVD on the unaffected side, the FA values of the DLPF-TT in groups B and C and the OF-TT in group C were lower than those of the control group (p < 0.05). There was no difference in initial MMSE score among three patient groups; however, group A had a higher mean follow-up MMSE score than that of groups B and C (p < 0.05).

CONCLUSIONS

Patients who underwent EVD of the affected hemisphere showed better results in terms of the PF-TT injury and cognitive outcome than patients who underwent EVD through the unaffected hemisphere or through both hemispheres.

Clinical and neuroimaging factors associated with aphasia severity in stroke patients: diffusion tensor imaging study

This study investigated factors associated with aphasia severity at both 2 weeks and 3 months after stroke using demographic and clinical variables, brain diffusion tensor imaging (DTI) parameters, and lesion volume measurements. Patients with left hemisphere stroke were assessed at 2 weeks (n = 68) and at 3 months (n = 20) after stroke. Demographic, clinical, and neuroimaging data were collected; language functions were assessed using the Western Aphasia Battery. For neuroimaging, DTI parameters, including the laterality index (LI) of fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity, mean diffusivity and fibre density (FD) of the arcuate fasciculus (AF), and lesion volume, were measured. Lesion volume, cortical involvement, and the National Institutes of Health Stroke Scale score significantly predicted aphasia severity at 2 weeks after stroke, whereas the aphasia quotient and presence of depression during the early subacute stage were significant predictors at 3 months after stroke. According to Pearson correlation, LI-AD and LI-FD were significantly correlated with the aphasia quotient 2 weeks after ischaemic stroke, and the LI-FA was significantly correlated with the aphasia quotient 2 weeks after haemorrhagic stroke, suggesting that the extent and mechanism of AF injuries differ between ischaemic and haemorrhagic strokes. These differences may contribute to aphasia severity.

Evaluation of diffusion-weighted magnetic resonance imaging at 3.0 Tesla for differentiation between intracranial neoplastic and noninfectious inflammatory lesions in dogs

OBJECTIVE

To evaluate the utility of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values obtained by diffusion-weighted MRI (DWI) at 3.0 T for differentiating intracranial neoplastic lesions from noninfectious inflammatory lesions (NIILs) in dogs.

ANIMALS

54 dogs that met inclusion criteria (ie, had a histologically confirmed intracranial lesion and DWI of the brain performed) with 5 lesion types: meningioma [n = 18], glioma [14], metastatic hemangiosarcoma [3], other metastatic neoplasms [5], and NIIL [14]).

PROCEDURES

Two observers, who were blinded to the histologic diagnoses, independently determined the mean ADC and FA values for each evaluated intracranial lesion on the basis of 3 circular regions of interest on DWI images. Findings were compared among the 5 lesion types, between all neoplasms combined and NIILs, and between the 5 legion types and previously determined values for corresponding locations for neurologically normal dogs.

RESULTS

The mean ADC and FA values did not differ significantly among the 5 lesion types or between all neoplasms combined and NIILs. However, 35% (14/40) of the neoplastic lesions had an ADC value ≥ 1.443 × 10^-3 mm²/s, whereas all NIILs had ADC values < 1.443 × 10^-3 mm²/s. Meningiomas and NIILs had FA values that were significantly lower than those for neurologically normal dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

In this population of dogs, the FA values for meningiomas and NIILs differed significantly from those previously reported for neurologically normal dogs. In addition, an ADC cutoff value of 1.443 × 10^-3 mm²/s appeared to be highly specific for diagnosing neoplastic lesions (vs NIILs), although the sensitivity and accuracy were low.

Based on Histogram Analysis: ADCaqp Derived from Ultra-high b-Value DWI could be a Non-invasive Specific Biomarker for Rectal Cancer Prognosis

Aquaporins (AQP) are not only water channel protein, but also potential prognostic indicator and therapeutic target for rectal cancer. Some previous studies have demonstrated the AQP expression could be estimated by ADC_aqp value derived from ultra-high b-value diffusion-weighted imaging (DWI). We aim to determine whether ADC_aqp could be a new and specific biomarker for indicating the AQP expression and prognostic factors of rectal cancer. 76 untreated patients with rectal cancer confirmed by colonoscopy biopsy were enrolled. ADC_aqp value was generated from ultra-high b-value DWI with five b-values (1700–3500 s/mm²). AQP (AQP1, 3 and 5)staining intensity was estimated by both of software (QuPath) and manual manner. The relationships between histogram features of ADC_aqp and AQP staining intensity were analyzed. The correlations between histogram features of ADC_aqp and differentiation degrees (good, moderate, poor), T stage (T1–2 vs T3–4), and lymph node status (N+ vs N−) were also evaluated respectively. The mean, 75^th percentile and 97.5^th percentile of ADC_aqp were correlated with AQP1 staining intensity (r = 0.237, 0.323 and 0.362, respectively, all P < 0.05) . No correlation was found between the histogram features of ADC_aqp and AQP3 or AQP5 staining intensity. The mean, 50^th percentile, 75^th percentile and 97.5^th percentile of ADC_aqp value exhibited significant differences between differentiation status (all P < 0.05). Histogram features of ADC_aqp value showed no significant differences in two subgroups of T stage and lymph node status (all P > 0.05). Histogram analysis showed that the ADC_aqp value derived from ultra-high b-value DWI of rectal cancer could reflect AQP1’s expression and rectal cancer’s malignancy degree. ADC_aqp might be a new imaging biomarker for evaluating rectal cancer.

Diffusion Tensor Imaging Studies on Recovery of Injured Optic Radiation: A Minireview

The optic radiation (OR) is a visual neural fiber pathway for the transfer of visual information from the lateral geniculate body of the thalamus to the primary visual cortex. To demonstrate the recovery of an OR injury, quantification and visualization of changes to the injured OR are necessary. Diffusion tensor imaging (DTI) allows determination of the state of an OR by assessing the obtained DTI parameters. In particular, diffusion tensor tractography (DTT), which is derived from DTI data, allows three-dimensional visualization of the OR. Thus, recovery of an injured OR can be demonstrated by examining changes in DTI parameters and/or configuration on follow-up DTI scans or via DTT of the injured OR. Herein, we review nine DTI-based studies that demonstrated recovery of OR injuries. The results reported in these studies suggest that an OR injury has a potential for recovery. Moreover, the results of these studies can form a basis for elucidating the recovery mechanisms of injured OR. These studies have suggested two recovery mechanisms for OR injury: recovery via the original OR pathway or via the transcallosal fibers of the corpus callosum. However, only nine studies on this topic have been conducted to date and six of those nine studies were case reports. Therefore, further studies involving larger numbers of subjects and reporting precise evaluations of changes in OR injury during recovery are warranted.

Motor recovery by the aberrant pyramidal pathway in a patient with cerebral infarct

INTRODUCTION

The aberrant pyramidal tract (APT) refers to the collateral pathway of the pyramidal tract (PT) descending through the medial lemniscus in the midbrain and pons. We report on a patient who showed changes of the APT from the early stage to the chronic stage concurrent with motor recovery following an infarct in the cerebral peduncle.

PATIENT CONCERNS

An 84-year-old female patient presented with moderate motor weakness of her upper and lower extremities (2/2) due to cerebral infarct on the right cerebral peduncle of midbrain. One week after her stroke, her motor weakness was similar to that at the onset (2/2). During 5 weeks' rehabilitation, her motor weakness recovered to the point that she was able to move upper and lower extremities against gravity with some resistance (4/4).

DIAGNOSIS

Cerebral infarct on the right cerebral peduncle of midbrain INTERVENTIONS:: She participated in a comprehensive rehabilitative management program, including movement therapy, neurotrophic drugs, and neuromuscular electrical stimulation therapy of the left finger extensor and ankle dorsiflexor muscles.

OUTCOMES

On 1-week and 6-week diffusion tensor tractographys (DTTs), the right PT was not reconstructed, but the right APT, which descended through the medial lemniscus pathway at the midbrain and pons and the pyramid at the medulla, was observed. The right APT became thicker on six-week DTT compared with 1-week DTT. On 1-week transcranial magnetic stimulation study, an motor evoked potential with delayed latency and decreased amplitude was evoked from the affected (right) hemisphere (latency: 24.4 msec and amplitude: 0.2uV). In contrast, its latency was decreased and amplitude was increased on six-week transcranial magnetic stimulation study (latency: 21.8 msec, amplitude: 0.8 uV) CONCLUSIONS:: We demonstrated changes in the APT from the early stage to the chronic stage concurrent with motor recovery in a patient with an infarct in the cerebral peduncle. Our findings have important implications that a spared APT could contribute to the motor recovery in patients with cerebral infarct when the PTis completely injured at the onset of cerebral infarct,.

Recent Progress for the Techniques of MRI-Guided Breast Interventions and their applications on Surgical Strategy

With a high sensitivity of breast lesions, MRI can detect suspicious lesions which are occult in traditional breast examination equipment. However, the lower and variable specificity of MRI makes the MRI-guided intervention, including biopsies and localizations, necessary before surgery, especially for patients who need the treatment of breast-conserving surgery (BCS). MRI techniques and patient preparation should be first carefully considered before the intervention to avoid lengthening the procedure time and compromising targeting accuracy. Doctors and radiologists need to reconfirm the target of the lesion and be very familiar with the process approach and equipment techniques involving the computer-aided diagnosis (CAD) tools and the biopsy system and follow a correct way. The basic steps of MRI-guided biopsy and localization are nearly the same regardless of the vendor or platform, and this article systematically introduces detailed methods and techniques of MRI-guided intervention. The two interventions both face different challenging situations during procedures with solutions given in the article. Post-operative statistics show that the complications of MRI-guided intervention are infrequent and mild, and MRI-guided biopsy provides the pathological information for the subsequent surgical decisions and MRI-guided localization fully prepared for follow-up surgical biopsy. New techniques for MRI-guided intervention are also elaborated in the article, which leads to future development. In a word, MRI-guided intervention is a safe, accurate, and effective technique with a low complication rate and successful MRI-guided intervention is truly teamwork with efforts from patients to surgeons, radiologists, MRI technologists, and nurses.

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.

Effects of injuries to descending motor pathways on restoration of gait in patients with pontine hemorrhage

BACKGROUND AND PURPOSE

Gait disturbance due to injuries of the descending motor pathway, including corticospinal tract (CST), corticoreticular pathway (CRP), and medial and lateral vestibulospinal tracts (VSTs), are commonly encountered disabling sequelae of pontine hemorrhage. We investigated relations between changes in the CST, CRP, and medial and lateral VST and corresponding changes in gait function in patients with pontine hemorrhage.

METHOD

Nine consecutive stroke patients with pontine hemorrhage, and 6 age-matched normal subjects were recruited. Four patients were allocated to group A (can't walk independently) and 5 to group B (can walk independently). Diffusion tensor imaging (DTI) data were acquired twice at acute to subacute stage and chronic stage after stroke onset. Diffusion tensor tractography (DTT) was used to reconstruct CST, CRP, medial and lateral VST.

RESULT

The CRP shows a significantly different between groups A and B in both initial and follow up DTT (p > 0.05). In contrast, CST, medial VST and lateral VST did not show a significant difference (p > 0.05). Regarding DTI parameters of CRPs in group A, percentages of patients with fractional anisotropy (FA) and mean diffusivity (MD) values more than two standard deviation from normal were higher by follow up DTI than by initial DTI, however, the CRPs in group B only showed increased abnormal range of MD.

CONCLUSIONS

The CST does not play an essential role in recovery of independent walking and vestibulospinal tracts may not crucially affect recovery of independent walking in patients with pontine hemorrhage. In contrast, and intact CRP or changes of the CRP integrity appear to be related to the recovery of gait function.

Injury of Corticospinal Tract in a Patient with Subarachnoid Hemorrhage as Determined by Diffusion Tensor Tractography: A Case Report

We report diffusion tensor tractography (DTT) of the corticospinal tract (CST) in a patient with paresis of all four limbs following subarachnoid hemorrhage (SAH) with intraventricular hemorrhage (IVH) after the rupture of an anterior communicating artery (ACoA) aneurysm rupture. The 73-year-old female was admitted to our emergency room in a semi-comatose mental state. After coil embolization-an acute SAH treatment-she was transferred to our rehabilitation department with motor weakness development, two weeks after SAH. Upon admission, she was alert but she complained of motor weakness (upper limbs: MRC 3/5, and lower limbs: MRC 1/5). Four weeks after onset, DTT showed that the bilateral CSTs failed to reach the cerebral cortex. The left CST demonstrated a wide spread of fibers within the corona radiata as well as significantly lower tract volume (TV) and higher fractional anisotropy (FA) as well as mean diffusivity (MD) compared to the controls. On the other hand, the right CST shifted to the posterior region at the corona radiata, and MD values of the right CST were significantly higher when compared to the controls. Changes in both CSTs were attributed to vasogenic edema and compression caused by untreated hydrocephalus. We demonstrate in this case, two different pathophysiological entitles, contributing to this patient's motor weakness after SAH.

Diffusion-Tensor-Tractography-Based Diagnosis for Injury of Corticospinal Tract in a Patient with Hemiplegia Following Traumatic Brain Injury

This paper reports a mechanism for corticospinal tract injury in a patient with hemiplegia following traumatic brain injury (TBI) based on diffusion tensor tractography (DTT) finding. A 73-year-old male with TBI resulting from a fall, without medical history, was diagnosed as having left convexity epidural hematoma (EDH). He underwent craniotomy and suffered motor weakness on the right side of the body. Two weeks after onset, he was transferred to a rehabilitation department with an alerted level of consciousness. Four weeks after onset, his motor functions were grade 1 by the Medical Research Council’s (MRC) standards in the right-side limbs and grade 4 in the left-side limbs. The result of DTT using the different regions of interest (ROIs) showed that most of the right corticospinal tract (CST) did not reach the cerebral cortex around where the EDH was located, and when the ROI was placed on upper pons, a disconnection of the CST was shown and a connection of the CST in ROI with the middle pons appeared. However, the right CST was connected to the cerebral cortex below the pons regardless of ROI. This study is the first report to use DTT to detect that the discontinuation of the left CST in the cerebral cortex and injury lesions below the lower pons and between the upper and lower pons are responsible for motor weakness in a patient.

Relationship between ataxia and inferior cerebellar peduncle injury in patients with cerebral infarct

INTRODUCTION

The inferior cerebellar peduncle (ICP) is a major neural tract in the cerebellum and is involved in coordination of movement and proprioceptive; therefore, ICP injury can be accompanied by poor coordination of movement, including ataxia. In this study, using diffusion tensor tractography (DTT), we investigated the relationship between ataxia and ICP injury in patients with cerebral infarct.

METHODS

We recruited 14 stroke patients with ataxia after the onset of stroke and 12 normal subjects. The Score of Assessment and Rating of Ataxia (SARA) was used to evaluate ataxia. The values of fractional anisotropy (FA), apparent diffusion coefficient, and fiber number (FN) of the ICP were measured for the diffusion tensor imaging parameters.

RESULTS

Significant differences were observed in the FA and FN values of the ICP in the affected hemisphere between the patient and control groups (P < .05). In addition, the FN value of the ICP in the affected hemisphere showed a negative correlation with SARA (r = -0.538, P < .05). However, parameters of the ICP in the unaffected hemisphere or the FN value in the unaffected hemisphere showed no correlation with SARA (P > .05).

CONCLUSION

We found that the ataxia severity was closely related to the severity of ICP injury in patients with cerebral infarct. Our results suggest that evaluation of the ICP using DTT would be useful for patients with ataxia after cerebral infarct.

Characteristics of the Uncinate Fasciculus and Cingulum in Patients with Mild Cognitive Impairment: Diffusion Tensor Tractography Study

Many studies have examined the relationship between cognition, and the cingulum and uncinate fasciculus (UF). In this study, diffusion tensor tractography (DTT) was used to investigate the correlation between fractional-anisotropy (FA) values and the number of fibers in the cingulum and UF in patients with and without cognitive impairment. The correlation between cognitive function, and the cingulum and UF was also investigated. Thirty patients (14 males, age = 70.68 ± 7.99 years) were divided into a control group (n = 14) and mild-cognitive-impairment (MCI) group (n = 16). The Seoul Neuropsychological Screening Battery (SNSB) and DTT were performed to assess cognition and bilateral tracts of the cingulum and UF. The relationship between SNSB values and the cingulum and UF was analyzed. The number of fibers in the right cingulum and right UF were significantly different between the two groups. The MCI group showed thinner tracts in both the cingulum and UF compared to the control group. A significant relationship was found between the number of fibers in the right UF and delayed memory recall. In conclusion, memory loss in MCI was associated with a decreased number of fibers in the right UF, while language and visuospatial function were related to the number of fibers in the right cingulum.

Corticoreticular Tract in the Human Brain: A Mini Review

Previous studies have suggested that the corticoreticular tract (CRT) has an important role in motor function almost next to the corticospinal tract (CST) in the human brain. Herein, the CRT is reviewed with regard to its anatomy, function, and recovery mechanisms after injury, with particular focus on previous diffusion tensor tractography-based studies. The CRT originates from several cortical areas but mainly from the premotor cortex. It descends through the subcortical white matter anteromedially to the CST with a 6- to 12-mm separation in the anteroposterior direction, then passing through the mesencephalic tegmentum and the pontine and pontomedullary reticular formations. Regarding its motor functions, the CRT appears to be mainly involved in the motor function of proximal joint muscles accounting for ~30–40% of the motor function of these joint muscles. In addition, the CRT is involved in gait function and postural stability. However, further studies that clearly rule out the effects of other motor function-related neural tracts are necessary to clarify the precise portion of the total motor function for which the CRT is responsible. With regard to recovery mechanisms for an injured CRT, three recovery mechanisms were suggested in five previous studies: recovery through the original pathway, recovery through perilesional reorganization, and recovery through the transcallosal pathway. However, each of those studies was single-case reports; therefore, further original studies including a larger number of patients are warranted.

Increased white matter diffusivity associated with phantom limb pain

Background

We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network.

Methods

Ten patients with phantom limb pain due to unilateral arm amputation and sixteen healthy age-matched controls were enrolled. The intensity of phantom limb pain was measured by the visual analogue scale (VAS) and depressive mood was assessed by the Hamilton depression rating scale. Diffusion tensor-derived parameters, including fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD), were computed from the DTI.

Results

Compared with controls, the cases had alterations in the cerebral white matter as a consequence of phantom limb pain, manifesting a higher AD of white matter in both hemispheres symmetrically after adjusting for individual depressive moods. In addition, there were associations between the RD of white matter and VAS scores primarily in the hemispheres related to the missing hand and in the corpus callosum.

Conclusions

The phantom limb pain after unilateral arm amputation induced plasticity in the white matter. We conclude that loss of white matter integrity, particularly in the hemisphere connected with the missing hand, is significantly correlated with phantom limb pain.

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.

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

OBJECTIVE

We investigated the relation between memory impairment and the fornix injury in patients with mild traumatic brain injury, using diffusion tensor tractography.

DESIGN

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.

RESULTS

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).

CONCLUSION

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.

Deterioration of Brain Neural Tracts in Elderly Women with Sarcopenia

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Difference in the Ascending Reticular Activating System Injury Between Mild Traumatic Brain Injury and Cerebral Concussion

Introduction

We investigated differences in the ascending reticular activating system (ARAS) injuries between patients with mild traumatic brain injury (mTBI) and cerebral concussion by using diffusion tensor tractography (DTT).

Methods

Thirty-one patients with mTBI, 29 patients with concussion, and 30 control subjects were recruited. We used DTT to reconstruct the lower ventral and dorsal ARAS, and the upper ARAS. The fractional anisotropy (FA) value and the fiber number (FN) of the lower ventral and dorsal ARAS, and the upper ARAS were determined.

Results

Significant differences were observed in the FA values of the lower ventral and dorsal ARAS on both sides between the mTBI and control groups and between the concussion and control groups (p < 0.05). The FN value was significantly different in the lower ventral ARAS on both sides between the concussion and control groups and between the mTBI and concussion groups (p < 0.05).

Conclusion

Both the mTBI and concussion patients suffered injuries in the lower ventral and dorsal ARAS, with the concussion patients exhibiting more severe injury in the ventral ARAS than that in the mTBI patients. These results suggest that the terms mTBI and concussion should be used differentially, even though they have used interchangeably for a long time.

Neonatal brain injury and aberrant connectivity

Brain injury sustained during the neonatal period may disrupt development of critical structural and functional connectivity networks leading to subsequent neurodevelopmental impairment in affected children. These networks can be characterized using structural (via diffusion MRI) and functional (via resting state-functional MRI) neuroimaging techniques. Advances in neuroimaging have led to expanded application of these approaches to study term- and prematurely-born infants, providing improved understanding of cerebral development and the deleterious effects of early brain injury. Across both modalities, neuroimaging data are conducive to analyses ranging from characterization of individual white matter tracts and/or resting state networks through advanced 'connectome-style' approaches capable of identifying highly connected network hubs and investigating metrics of network topology such as modularity and small-worldness. We begin this review by summarizing the literature detailing structural and functional connectivity findings in healthy term and preterm infants without brain injury during the postnatal period, including discussion of early connectome development. We then detail common forms of brain injury in term- and prematurely-born infants. In this context, we next review the emerging body of literature detailing studies employing diffusion MRI, resting state-functional MRI and other complementary neuroimaging modalities to characterize structural and functional connectivity development in infants with brain injury. We conclude by reviewing technical challenges associated with neonatal neuroimaging, highlighting those most relevant to studying infants with brain injury and emphasizing the need for further targeted study in this high-risk population.

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.

Early treadmill exercise increases macrophage migration inhibitory factor expression after cerebral ischemia/reperfusion

The neuroprotective function of macrophage migration inhibitory factor (MIF) in ischemic stroke was rarely evaluated. This study aimed to investigate the effects of early treadmill exercise on recovery from ischemic stroke and to determine whether these effects are associated with the expression levels of MIF and brain-derived neurotrophic factor (BDNF) in the ischemic area. A total of 40 male Sprague-Dawley rats were randomly assigned to the ischemia and exercise group [middle cerebral artery occlusion (MCAO)-Ex, n = 10), ischemia and sedentary group (MCAO-St, n = 10), sham-surgery and exercise group (Sham-Ex, n = 10), or sham-surgery and sedentary group (Sham-St, n = 10). The MCAO-Ex and MCAO-St groups were subjected to MCAO for 60 minutes, whereas the Sham-Ex and Sham-St groups were subjected to an identical operation without MCAO. Rats in the MCAO-Ex and Sham-Ex groups then ran on a treadmill for 30 minutes once a day for 5 consecutive days. After reperfusion, the hanging time tested by the wire hang test was longer and the relative fractional anisotropy determined by MRI was higher in the peri-infarct region of the MCAO-Ex group compared with the MCAO-St group. The expression levels of MIF and BDNF in the peri-infarct region were upregulated in the MCAO-Ex group. Increased MIF and BDNF levels were positively correlated with relative fractional anisotropy changes in the peri-infarct region. There was no significant difference in the levels of MIF and BDNF in the peri-infarct region between the Sham-Ex and Sham-St groups. Our study demonstrated that early exercise (initiated 48 hours after the MCAO) could improve motor and neuronal recovery after ischemic stroke. Furthermore, the increased levels of MIF and BDNF in the peri-infarct region (penumbra) may be one of the mechanisms of enhanced neurological function recovery. All experiments were approved by the Institutional Animal Care and Use Committee in Asan Medical Center in South Korea (2016-12-126).

Effect of Neuromuscular Electrical Stimulation Training on the Finger Extensor Muscles for the Contralateral Corticospinal Tract in Normal Subjects: A Diffusion Tensor Tractography Study

Objectives: Neuromuscular electrical stimulation (NMES) is a popular rehabilitative modality to improve motor function of the extremities and trunk. In this study, we investigated changes of hand function and the contralateral corticospinal tract (CST) with treatment by NMES on the finger extensor muscles for 2 weeks, using serial diffusion tensor tractography (DTT).

Methods: Thirteen right handed normal subjects were recruited. Treatment was applied to the left hand (the NMES side), and the right hand was the control side. NMES was applied for 30 min/day, 7 days per week, for 2 weeks. Hand motor function was evaluated twice at pre-NMES and post-NMES training using grip strength (GS), Purdue pegboard test (PPT) and tip pinch. The fractional anisotropy (FA), mean diffusivity (MD) and tract volume (TV) of the CST in both hemispheres were measured using DTT.

Results: On the control side, the clinical scores did not differ significantly between pre- and post-NMES training (p > 0.05). However, on the NMES side, PPT and tip pinch improved significantly (p < 0.05), although GS did not. TV of the right CST increased significantly at post-NMES training (p < 0.05) whereas FA and MD did not differ significantly (p > 0.05). By contrast, FA, MD and TV on the left CST did not change significantly (p > 0.05).

Conclusion: We demonstrated facilitation of the contralateral CST with improvement of fine motor activity by 2 weeks of NMES training of peripheral muscles in normal subjects. We think our results can be applied to the normal subjects and patients with brain injury to improve the fine motor function of the hand and facilitate the normal CST or healing of the injured CST.

Recent advances in the use of MRI to assess early human cortical development

Over the past decade, a number of advanced magnetic resonance-based methods have been brought to bear on questions related to early development of the human cerebral cortex. Herein, we describe studies employing analysis of cortical surface folding (cortical cartography), cortical microstructure (diffusion anisotropy), and cortically-based functional networks (resting state-functional connectivity MRI). The fundamentals of each MR method are described, followed by a discussion of application of the method to developing cortex and potential clinical uses. We use premature birth as an exemplar of how these modalities can be used to investigate the effects of medical and environmental variables on early cortical development.

Changes in Diffusion Metrics of the Red Nucleus in Chronic Stroke Patients With Severe Corticospinal Tract Injury: A Preliminary Study

Objective

To explore plastic changes in the red nucleus (RN) of stroke patients with severe corticospinal tract (CST) injury as a compensatory mechanism for recovery of hand function.

Methods

The moderate group (MG) comprised 5 patients with synergistic hand grasp movement combined with limited extension, and the severe group (SG) included 5 patients with synergistic hand grasp movement alone. The control group (CG) included 5 healthy subjects. Motor assessment was measured by Motricity Index (MI). Diffusion tensor imaging was analyzed using fractional anisotropy (FA) and radial diffusivity (RD) in the individual regions of interest (ROIs)—bilateral internal capsule and anterior pons for CST injury and bilateral RN for rubrospinal tract (RST) injury.

Results

The SG showed a significantly lower MI score than the MG mainly due to differences in hand subscores. Significantly reduced FA was observed in both MG and SG compared with CG, while SG showed increased MD and RD in the affected ROIs of CST, and increased FA on the unaffected side compared with CG. However, in the RN ROI, a significantly increased FA and decreased RD on the unaffected side similar to the affected side were found only in the SG. The relative index of FA was lower and RD in SG was higher than in CG in RST.

Conclusion

The diffusion metrics of RST showed changes in patients with severe CST injury, suggesting that RST may play a role in the recovery of hand function in patients with severe CST injury.

Impact of Advancing Technology on Diagnosis and Treatment of Breast Cancer

New emerging breast imaging techniques have shown great promise in breast cancer screening, evaluation of extent of disease, and response to neoadjuvant therapy. Tomosynthesis, allows 3-dimensional imaging of the breast, and increases breast cancer detection. Fast abbreviated MRI has reduced time and costs associated with traditional breast MRI while maintaining cancer detection. Diffusion-weighted imaging is a functional MRI technique that does not require contrast and has shown potential in screening, lesion characterization and also evaluation of treatment response. New image-guided preoperative localizations are available that have increased patient satisfaction and decreased operating room delays.

Comparison of Multi-Tensor Diffusion Models' Performance for White Matter Integrity Estimation in Chronic Stroke

Better insight into white matter (WM) alterations after stroke onset could help to understand the underlying recovery mechanisms and improve future interventions. MR diffusion imaging enables to assess such changes. Our goal was to investigate the relation of WM diffusion characteristics derived from diffusion models of increasing complexity with the motor function of the upper limb. Moreover, we aimed to evaluate the variation of such characteristics across different WM structures of chronic stroke patients in comparison to healthy subjects. Subjects were scanned with a two b-value diffusion-weighted MRI protocol to exploit multiple diffusion models: single tensor, single tensor with isotropic compartment, bi-tensor model, bi-tensor with isotropic compartment. From each model we derived the mean tract fractional anisotropy (FA), mean (MD), radial (RD) and axial (AD) diffusivities outside the lesion site based on a WM tracts atlas. Asymmetry of these measures was correlated with the Fugl-Meyer upper extremity assessment (FMA) score and compared between patient and control groups. Eighteen chronic stroke patients and eight age-matched healthy individuals participated in the study. Significant correlation of the outcome measures with the clinical scores of stroke recovery was found. The lowest correlation of the corticospinal tract FAasymmetry and FMA was with the single tensor model (r = -0.3, p = 0.2) whereas the other models reported results in the range of r = -0.79 ÷ -0.81 and p = 4E-5 ÷ 8E-5. The corticospinal tract and superior longitudinal fasciculus showed most alterations in our patient group relative to controls. Multiple compartment models yielded superior correlation of the diffusion measures and FMA compared to the single tensor model.

Optic radiation injury in patients with aneurismal subarachnoid hemorrhage: A preliminary diffusion tensor imaging report

Visual field defect is one of the various clinical manifestations in patients with subarachnoid hemorrhage (SAH). Little is known about the pathogenic mechanism of visual field defect in SAH. In the current study, we investigated the diffusion tensor imaging (DTI) finding of the optic radiation in patients with SAH following rupture of a cerebral artery aneurysm. We recruited 21 patients with aneurismal SAH (12 males, 9 females, mean age, 52.67 years; range, 41–68 years) who showed no definite lesion along the visual pathway. Twenty-one age-and sex-matched normal control subjects were also recruited. DTI data were acquired at an average of 5.9 weeks (range: 3–12 weeks) after onset and reconstruction of the optic radiation was performed using DTI-Studio software. The fractional anisotropy value, apparent diffusion coefficient value, and fiber number of the optic radiation were measured. The fractional anisotropy value of the optic radiation was significantly decreased, and the apparent diffusion coefficient value was significantly increased, in patients with aneurismal SAH than in normal control subjects. However, there was no significant difference in the fiber number of the optic radiation between patients with aneurismal SAH and normal control subjects. The decrement of fractional anisotropy value and increment of apparent diffusion coefficient value of the optic radiation in patients with aneurismal SAH suggest optic radiation injury. Therefore, we recommend a thorough evaluation for optic radiation injury in patient with aneurismal SAH.

Openness to Changing Religious Views Is Related to Radial Diffusivity in the Genu of the Corpus Callosum in an Initial Study of Healthy Young Adults

A quest orientation to religion is characterized by a search for answers to complex existential questions, a perception of religious doubt as positive, and an openness to change one's religious views as one grows and changes. This orientation is inversely related to fundamentalism, authoritarianism, and prejudice and directly related to cognitive complexity, openness to experience, and prosociality. To date, the neural correlates of religious quest have not been investigated. This study assessed the relationships between measures linked to white-matter integrity and quest religious orientation among 24 healthy participants using diffusion tensor imaging (DTI) and the quest scale. A tract-based spatial statistical analysis whole-brain-corrected initially employing an accepted threshold (pTFCE < 0.05) and then applying a Bonferroni correction (pTFCE < 0.0042) identified a region of the genu of the corpus callosum as showing radial diffusivity measures being related to openness to change religious beliefs. When not employing a Bonferroni correction (pTFCE < 0.05), the openness-to-change subscale of the quest scale negatively correlated with radial diffusivity and mean diffusivity measures in extensive white-matter regions in both hemispheres that include the corpus callosum body, genu, and splenium, superior longitudinal fasciculus, forceps minor, external capsule, and inferior fronto-occipital fasciculus. No relationships were found with the other subscales. These findings suggest that a greater openness to change one's religious views is associated with better white-matter integrity specifically in the genu of the corpus callosum and likely in a more extensive set of white-matter structures interconnecting widespread cortical and subcortical regions in the brain across hemispheres. They, furthermore, suggest structural similarities that may link this tendency to associated positive psychological traits, including creative cognition and post-traumatic growth.