Correlation of diffusion tensor imaging parameters and Gleason scores of prostate cancer

The aim of the present study was to explore the association between the parameters of diffusion tensor imaging (DTI), including fractional anisotropy (FA) values, apparent diffusion coefficient (ADC) values and the diffusion tensor tractography (DTT) map, with the Gleason score of prostate cancer (PCa). A retrospective study of 50 cases of PCa confirmed by biopsy or surgical pathology was performed. Conventional magnetic resonance imaging and DTI scans were conducted in these cases. The 50 cases of PCa were divided into three groups, including low, intermediate and high grade, according to the Gleason score. Post-DTI processing was performed using Neuro 3D software, in order to measure the FA and ADC values, and map the prostate fibers. Differences in FA and ADC values among the various PCa groups were examined using analysis of variance, while the correlation of FA and ADC values with the Gleason score was studied using Pearson correlation analysis. The obtained DTT map clearly demonstrated the spatial structure of the prostate fibers. The fibers of the cancer area were dense without interruption in the low-grade group, sparse and disordered in the intermediate-grade group, and were disordered, sparse or even absent in the high-grade group. The FA values were 0.284±0.313, 0.293±0.347 and 0.369±0.347, respectively, with statistically significant differences observed among the three groups (F=234.533; P<0.05) and between each group (P<0.05). In addition, the FA value of PCa was positively correlated with the Gleason score (r=0.884; P<0.05). The ADC values of the low-, intermediate- and high-grade groups were 1.070±0.072×10^-3, 0.961±0.081×10^-3 and 0.821±0.048×10^-3, respectively, which demonstrated statistically significant differences among the three groups (F=49.987; P<0.05) and between each group (P<0.05). Furthermore, the ADC values of PCa were negatively correlated with Gleason score (r=-0.810; P<0.05). In conclusion, there was an association between DTI parameters and Gleason score, which may be used to evaluate the grading and prognosis of PCa.

Diffusion-tensor Imaging and Tractography Application in Pre-operative Planning of Intra-axial Brain Lesions

Gliomas are the most common brain tumors that diffusely infiltrate the surrounding white matter (WM) tracts. Conventional MRI is commonly used for tumor localization and characterization. However, this does not give precise information about the WM infiltration surrounding the tumor. Diffusion-tensor imaging (DTI) is a non-invasive magnetic resonance (MR) technique that measures WM tissue integrity and tractography (fiber tracking) used to investigate the preferential directionality of diffusion. DTI allows visualization of WM tracts in the immediate vicinity of brain tumors that permit maximum tumor resection while also preserving the eloquent brain areas. The relation of tumors with the white matter tracts (deviation, infiltration, and disruption) has been one the most important initial applications of DTI. The fibers can be infiltrated in normal-appearing areas, and abnormal-appearing areas of the brain can show anatomically intact fibers. In the surgical planning of brain tumors, surgery is aided by knowing the proximity and relative position of the tumor to the adjacent WM tracts. The aim of the present study is to assess the role of DT tractography (DTT) in preoperative mapping of major WM tracts in relation to brain tumors.

Delayed recovery of the affected finger extensors at chronic stage in a stroke patient: A case report

RATIONALE

A 33-year-old male presented with complete weakness of the right extremities due to corona radiata infarct.

PATIENT CONCERNS

The main concerns of the patient is recovery of hand function especially related to finger extension.

DIAGNOSES

Right corona radiata infarct.

INTERVENTIONS

He underwent physical therapy and occupational therapy at the outpatient clinic of the rehabilitation department of the same university hospital until 2 years after onset. In addition, he underwent neuromuscular electrical stimulation for the right finger extensors continuously until 4 years after onset.

OUTCOMES

At 6 months after onset, the weakness of his right side recovered to subnormal state except for the right finger extensors which were completely weak. At 1.5 years after onset, the right finger extensors began to show slow and continuous recovery. At 4 years after onset, the patient showed motor recovery in the right finger extensors to the extent that he was able to move against gravity. Discontinuation of the left corticospinal tract was observed on 2-month diffusion tensor tractography (DTT); however, the integrity of this discontinuation had recovered to the primary motor cortex on 4-year DTT. On 2-month transcranial magnetic stimulation (TMS), no motor-evoked potential was evoked; in contrast, motor-evoked potentials were obtained at the right-hand muscle on 4-year TMS study.

LESSONS

We demonstrated unusual delayed and long-term recovery of the affected finger extensors in a patient with corona radiata infarct using DTT and TMS.

Recovery of an injured prefronto-caudate tract in a patient with traumatic brain injury: A diffusion tensor tractography study

OBJECTIVES

We report on a patient with improvement of akinetic mutism (AM), who showed recovery of an injured prefronto-caudate tract following traumatic brain injury (TBI), which was demonstrated by follow-up diffusion tensor tractographies (DTTs).

CASE PRESENTATION

A 72-year-old female had suffered from head trauma resulting from falling down the stairs. She was diagnosed as subdural hematoma on the right frontal lobe and subarachnoid haemorrhage. At 5 weeks after head trauma, when starting rehabilitation, she showed no spontaneous movement or speech. She participated in a comprehensive rehabilitative management programme, including movement therapy and dopaminergic drugs, for improvement of AM. During 5 week's intensive rehabilitation, she showed gradual improvement of AM: she became able to perform some daily activities by herself including eating, dressing and walking.

RESULTS

On 5-week DTT, the neural connectivity of the caudate nucleus (CN) to the medial prefrontal cortex (PFC; Broadmann area [BA]: 10 and 12) and the orbitofrontal cortex (BA: 11 and 13) was decreased in both hemispheres; in contrast, the neural connectivity of the CN to the medial PFC was increased on the left side on 10-week and 6-month DTT.

CONCLUSIONS

Recovery of an injured prefronto-caudate tract concurrent with the improvement of AM was demonstrated in a patient with TBI, using follow-up DTTs.

Traumatic axonal injury despite clinical phenotype of mild traumatic brain injury: a case report

OBJECTIVES

We report on a patient who suffered traumatic axonal injury (TAI) of various neural tracts despite airbag deployment following mild traumatic brain injury (TBI), which was demonstrated by diffusion tensor tractography (DTT).

CASE DESCRIPTION

A 58-year-old female patient suffered from head trauma resulting from an in-car traffic accident. At the time of head trauma, her head and face hit the deployed airbag after flexion-hyperextension-rotation injury. The patient's Glasgow Coma Scale score was 15. Since the day of head trauma, she began to feel headache and upper back pain at the mid-thoracic area. At 7 days after onset, she began to feel pain on the left hand, which spread to the right hand and leg: throbbing and cold pain without allodynia or hyperalgesia (visual analogue scale score: 5). She also felt mild weakness of all four extremities and mild memory impairment. On 4-week DTT, the corticospinal tract showed partial tearing at the subcortical white matter level in both hemispheres . The right fornical crus and right anterior cingulum were discontinued, and narrowing and partial tearing were observed in both spinothalamic tracts.

CONCLUSIONS

TAI of four kinds of neural tracts was demonstrated in a patient with mild TBI despite airbag deployment, using DTT.

Recovery of an injured corticobulbar tract in a patient with stroke: A case report

RATIONALE

The corticobulbar tract (CBT) is known to be involved in the motor function of the non-oculomotor cranial nuclei and controls the muscles of the face, head, and neck. Several studies have reported injury of the CBT in patients with brain injury, however, little is known about recovery of the injured CBT.

PATIENT CONCERNS

A 59-year-old right-handed male underwent decompressive craniectomy for management of brain swelling and intracerebral hemorrhage following an infarction in the left middle cerebral artery territory. Initially, the patient had showed severe dysphagia and had to be fed using a Levin tube. Five weeks after the onset of stroke, the patient was transferred to the rehabilitation department and underwent comprehensive rehabilitative therapy. Cranioplasty was performed eight weeks after the onset. The patient was completely recovered from dysphagia and the Levine tube was removed nine weeks after the onset.

INTERVENTIONS

Diffusion tensor imaging was performed twice; at five weeks and nine weeks from the onset.

OUTCOME

On five-week diffusion tensor tractography (DTT), the right CBT was discontinued at the subcortical white matter and showed severe narrowing and the left CBT was not reconstructed. By contrast, on nine-week DTT, the right CBT was extended to the cerebral cortex and thickened while the left CBT remained not reconstructed in DTT.

LESSONS

This case demonstrates the association of the recovery of injured CBT with the recovery of dysphagia using DTT.

Aberrant Pyramidal Tract in Comparison with Pyramidal Tract on Diffusion Tensor Tractography: A Mini-Review

The pyramidal tract (PT) is a major neural tract that controls voluntary movements in the human brain. The PT has several collateral pathways, including the aberrant pyramidal tract (APT), which passes through the medial lemniscus location at the midbrain and pons. Diffusion tensor tractography (DTT) allows visualization and estimation of the APT in three dimensions. In this mini-review, eight DTT studies on the APT were reviewed. Two studies for normal subjects reported the prevalence (17–18% of hemispheres) and the different characteristics (different cortical origin, less directionality, and fewer neural fibers) of the APT compared with the PT. Six studies reported on the APT in patients with cerebral infarct, traumatic brain injury, and cerebral palsy and suggested that the APT could contribute to motor recovery following brain injury. The research on the APT in patients with brain injury has important implications for neuro-rehabilitation because understanding of the motor recovery mechanism can provide the basis for scientific rehabilitation strategies. Therefore, studies involving various brain pathologies with large numbers of patients on this topic should be encouraged. In addition, further studies are needed on the exact role of the APT in normal subjects.

Frontal aslant tract projections to the inferior frontal gyrus

BACKGROUND

Frontal aslant tract (FAT) is a white matter bundle connecting the pre-supplementary motor area (pre-SMA) and the supplementary motor area (SMA) with the inferior frontal gyrus (IFG). The purpose of the present study was to evaluate the anatomical variability of FAT.

MATERIALS AND METHODS

Total number of fibres and the lateralisation index (LI) were calculated. We attempted to find factors contributing to the diversity of FAT regarding IFG terminations to the pars opercularis (IFG-Op) and to the pars triangularis (IFG-Tr). Magnetic resonance imaging of adult patients with diffusion tensor imaging (DTI) with total number of 98 hemispheres composed a cohort. V-shaped operculum was the most common (60.5%).

RESULTS

Total number of FAT fibres had widespread and unimodal distribution (6 to 1765; median: 160). Left lateralisation was noted in 64.3% of cases and was positively correlated with total number of FAT fibres and the bundle projecting to IFG-Op (p < 0.01). LI correlated with total number of FAT fibres (r = 0.43, p < 0.01). FAT projected predominantly to IFG-Op (88.9%; 88 of 99). Only in 3 (3.1%) cases more fibres terminated in IFG-Tr than in IFG-Op. Total number of FAT fibres and number of fibres terminating at IFG-Op did not correlate with the ratio of fibre numbers: FAT/IFG-Op, FAT/IFG-Tr and IFG-Op/IFG-Tr (p > 0.05). The greater total number of fibres to IFG-Tr was, the higher were the ratios of IFG-Tr/ /FAT (r = 0.57, p < 0.01) and IFG-Tr/IFG-Op (r = 0.32, p = 0.04).

CONCLUSIONS

Among the IFG, the major termination of FAT is IFG-Op. Whereas the IFG-Tr projection seems to be related to the expansion of the entire FAT bundle regardless of side, domination and handedness. Nevertheless, FAT features a significant anatomical variability which cannot be explained in terms of DTI findings.

Combination of kinematic analyses and diffusion tensor tractrography to evaluate the residual motor functions in spinal cord-hemisected monkeys

BACKGROUND

Spinal cord injury (SCI) causes loss of locomotor functions. Nowadays, the relationship between the residual locomotion after SCI and the diffusion tensor tractography (DTT) results still remains unclear.

METHODS

Four rhesus monkeys were suffered thoracic cord hemisection. Kinematic evaluation and DTT were performed prior- and post-SCI (6 and 12 weeks). The longitudinal changes of gait parameters and the DTT parameters were analyzed for the injury-contralateral hindlimb. The correlations between gaits and DTT parameters were also investigated.

RESULTS

Almost gait parameters significantly changed after SCI, meanwhile, the caudal-rostral connection rate of DTT showed negative correlation with all gait parameters, demonstrating that the locomotor changes of the injury-contralateral hindlimb were associated with the ratio of residual fibers.

CONCLUSIONS

The combinatory use of gait analysis and DTT has been demonstrated to be sensitive to locomotion changes after SCI, and may therefore have potential applications in the pre-clinical studies of SCI.

Degeneration of corticofugal fibers in a patient with primary progressive freezing gait: A case report

RATIONALE

To report a patient with primary progressive freezing gait (PPFG) whose degeneration of corticofugal tract (CFT) from the supplementary motor area (SMA) was demonstrated using diffusion tensor tractography (DTT).

PATIENT CONCERNS

A 66-year-old woman presented with a solitary symptom of a sudden transient break on walking (i.e., freezing gait), which slowly progressed for 4 years.

DIAGNOSES

Imaging evidence using magnetic resonance imaging and F-florinated-N-3-fluoropropyl-2-β-carboxymethoxy-3-β-(4-lodophenyl) nortropane positron emission tomography scanning was unremarkable, and our patient's symptom was not affected by dopamine agonist medication. Based on the clinical symptoms and imaging findings, we diagnosed our patient as having PPFG.

INTERVENTIONS

From the patient and 20 age- and sex- matched normal controls, diffusion tensor imaging data were acquired using a 1.5 T magnetic resonance scanner.

OUTCOMES

In DTT findings, the CFT from the left SMA was partially torn and thinned. Moreover, the fractional anisotropy value and tract volume of CFT from the left SMA were more than two standard deviations lower than those of normal controls.

LESSONS

In our opinion, the lesion in the CFT from the left SMA in our patient was attributed to the occurrence of PPFG. We believe that the results of this study suggest one of the pathological mechanisms for the occurrence of gait difficulty in PPFG.

Restoration of the ascending reticular activating system compressed by hematoma in a stroke patient

RATIONALE

We report on restoration of the ascending reticular activating system (ARAS), compressed by an intracerebral hematoma and perihematomal edema following a stroke. The restoration of the ARAS was demonstrated by diffusion tensor tractography (DTT).

PATIENT CONCERNS

In a 60-year-old male, a brain MRI taken at 2 weeks after the surgery showed a hematoma and perihematomal edema in the left posterolateral pons and cerebellum, which were markedly resolved on a brain MRI after 5 weeks.

DIAGNOSES

Intraventricular hemorrhage.

INTERVENTIONS

Navigation-guided stereotactic drainage of a hematoma in the left cerebellum, comprehensive rehabilitative therapy, including hypersomnia medication (modafinil), physical therapy, and occupational therapy.

OUTCOMES

His hypersomnia improved significantly with rehabilitation, with no daytime hypersomnia beginning 3 weeks after the surgery. On 2-week DTT, neither the neural tract of the left lower dorsal or ventral ARAS were reconstructed, but these neural tracts were wellreconstructed on 5-week DTT.

LESSONS

In conclusion, restoration of nonreconstructed neural tracts of the lower ARAS with the resolution of the hematoma and perihematomal edema was demonstrated in a stroke patient, using DTT.

Aggravation of excessive daytime sleepiness concurrent with aggravation of an injured ascending reticular activating system in a patient with mild traumatic brain injury: A case report

BACKGROUND

We report on a patient who developed aggravation of excessive daytime sleepiness (EDS) concurrent with aggravation of an injured ascending reticular activating system (ARAS) following mild traumatic brain injury (TBI), demonstrated by follow-up diffusion tensor tractographies (DTTs).

METHODS

A 42-year-old male patient experienced head trauma resulting from flexion-hyperextension injury after collision with another vehicle from behind while stopped at an intersection. The patient lost consciousness for approximately 10 seconds and experienced no post-traumatic amnesia following the accident. The patient's Glasgow Coma Scale score was 15. No specific lesion was observed on the conventional brain MRI performed at 10 weeks after onset. The patient complained of EDS after the head trauma and aggravation of EDS with passage of time. The Epworth Sleepiness Scale indicated abnormality with a score of 12 at 10 weeks after onset (cut-off: 10 points full mark: 24 score) and it was aggravated with a score of 18 at 16 months.

RESULTS

On 10-week DTT, decreased neural connectivity of the intralaminar thalamic nucleus to the prefrontal cortex and basal forebrain was observed in both hemispheres. However, no significant abnormality was observed in the dorsal and ventral lower ARAS. On 16-month DTT, the upper portion of the left dorsal lower ARAS showed partial tearing and the ventral lower ARAS showed thinning (both sides) and partial tearing (right side).

CONCLUSIONS

Aggravation of EDS concurrent with aggravation of an injured ARAS was demonstrated in a patient with mild TBI using DTT.

Magnetic resonance diffusion tensor imaging for occult lesion detection in multiple sclerosis

It remains challenging to locate occult lesions in patients with multiple sclerosis (MS). Diffusion tensor imaging (DTI) has been demonstrated to have the potential to identify occult changes in MS lesions. The present study used 3.0T magnetic resonance DTI to investigate the characteristics of different stages of MS lesions. DTI parameters, fractional anisotropy (FA), mean diffusivity (MD), λ// and λ┴ values of lesions were compared at the different stages of 10 patients with MS with 10 normal controls. The results demonstrated that FA and λ// values of MS silent and subacute lesions are decreased and MD and λ┴ values are increased, as compared with those of normal appearing white matter (NAWM) and normal controls. NAWM FA values were lower, and MD, λ//, and λ┴ values were higher than those of normal controls. It was also indicated that MS lesions had reduced color signals compared with the controls, and the lesion area appeared larger using DTI as compared with diffusion-weighted imaging. Furthermore, fiber abnormalities were detected in MS lesions using DTT, with fewer fibers connected to the lesion side, as compared with the contralateral side. FA, MD, λ// and λ┴ values in the thalamus were increased, as compared with those of normal controls (P<0.05); whereas MD, λ// and λ┴ values were significantly increased and FA values significantly decreased in the caudate nucleus and deep brain gray matter (DBGM) of patients with MS, as compared with the controls (P<0.05). λ// and λ┴ values were also significantly increased in the DBGM of patients with MS as compared with normal controls (P<0.05). The present findings demonstrate that DTI may be useful in the characterization of MS lesions.

Change of ascending reticular activating system with recovery from vegetative state to minimally conscious state in a stroke patient

RATIONALE

We report on a stroke patient who showed change of the ascending reticular activating system (ARAS) concurrent with recovery from a vegetative state (VS) to a minimally conscious state (MCS), which was demonstrated on diffusion tensor tractography (DTT).

PATIENT CONCERNS

A 59-year-old male patient underwent CT-guided stereotactic drainage 3 times for management of intracerebral hemorrhage and intraventricular hemorrhage.

DIAGNOSIS

After 4 months from onset, when starting rehabilitation, the patient showed impaired consciousness, with a Glasgow Coma Scale (GCS) score of 6 and a Coma Recovery Scale-Revised score of 2. At 10 months after onset, his GCS score had recovered to 11 with a GRS-R score of 20, and he was able to perform rock-scissors-paper using his right hand according to verbal command.

INTERVENTIONS

On 10-month DTT, marked increased neural connectivity of the thalamic intralaminar nucleus (ILN) to the cerebral cortex was observed in both prefrontal cortexes and the right thalamus compared with 4-month DTT. However, no significant change was observed in the lower dorsal ARAS between the pontine reticular formation (PRF) and the thalamic ILN. In addition, the reconstructed lower ventral ARAS between the PRF and hypothalamus had disappeared in both hemispheres on 10-month DTT.

OUTCOMES

Change of the ARAS was demonstrated in a stroke patient who showed recovery from a VS to an MCS.

LESSONS

It appeared that the prefrontal cortex and thalamus, which showed increased neural connectivity, contributed to recovery from a VS to an MCS in this patient.

Delayed gait recovery with recovery of an injured corticoreticulospinal tract in a chronic hemiparetic patient: A case report

OBJECTIVES

We report on a chronic hemiparetic patient whose gait recovery was delayed until healing of an injured corticoreticulospinal tract (CRT), which was demonstrated on diffusion tensor tractography (DTT).

CASE PRESENTATION

A 71-year-old female presented with complete paralysis of the right extremities resulting from a spontaneous intracerebral hemorrhage. At 5 months after onset, when she was admitted for rehabilitation after undergoing rehabilitation at the previous university hospital, she presented with severe weakness of the right leg (manual muscle test: 0 ∼ 2- score) and could not even stand. She received comprehensive rehabilitative therapy for 32 months after the onset. Motor weakness of her right leg improved to the point that she was able to extend her knee on gravity-eliminated position at 11 months and against some resistance at 30 months after onset. She was able to walk independently at 30 months after onset.

RESULTS

The left CRT was discontinuous at the basal ganglia level on 5-month DTT. This discontinuation elongated to the cerebral cortex on 32-month DTT, whereas on 32-month DTT, the right CRT had become thicker compared with that on 5-month DTT.

CONCLUSIONS

An injured CRT healed in a patient who was able to walk independently after approximately 2 years of rehabilitation starting 5 months after the onset of intracerebral hemorrhage.

Recovery of an injured cingulum via an aberrant neural tract in a patient with traumatic brain injury: A case report

BACKGROUND

We report on a patient who appeared to show recovery of an injured anterior cingulum via an aberrant neural tract between an injured cingulum and the basalis nucleus of Meynert following traumatic brain injury (TBI), which was demonstrated on diffusion tensor tractography (DTT).

METHODS

A 47-year-old male who had suffered a pedestrian traffic accident underwent conservative management for diffuse traumatic axonal injury. When starting rehabilitation at 6 weeks after onset, evaluation using the Mini-Mental State Examination (MMSE) could not be performed due to the severity of his cognitive dysfunction. The patient showed improvement of cognitive dysfunction on MMSE with 10 at 2 months, 13 at 6 months, and 26 at 10 months after onset.

RESULTS

On 6-week DTT, discontinuation superior to the genu of the corpus callosum was observed in both cingulums. However, on 6-month DTT, the discontinued anterior part of the right cingulum was elongated anteriorly, not through the cingulum, but through the anterolateral subcortical white matter of the cingulum, while on 10-month DTT, this elongated neural tract of the right cingulum was connected to the right basalis nucleus of Meynert in the basal forebrain.

CONCLUSION

Recovery of an injured anterior cingulum via an aberrant neural tract between an injured cingulum and Ch 4 was demonstrated in a patient with TBI. Our result appears to suggest a mechanism for recovery of an injured cingulum following brain injury.

Injury of the dorsolateral prefronto-thalamic tract in a patient with depression following mild traumatic brain injury: A case report

BACKGROUND

Depression, a prevalent psychiatric disorder, is associated with abnormality in the prefrontal cortex, particularly the left dorsolateral prefrontal cortex. In this study, we report on a patient with severe depression who showed injury of the dorsolateral prefronto-thalamic tract following mild traumatic brain injury, which was demonstrated by diffusion tensor tractography (DTT).

METHODS AND RESULTS

A 63-year-old female patient suffered an in-car accident. The patient lost consciousness for approximately 10 minutes and experienced posttraumatic amnesia approximately 30 minutes from the time of the accident. Her Glasgow Coma Scale score was 15. No specific lesion was observed on the conventional brain magnetic resonance imaging. Since the onset of head trauma, she had shown continuous depression and on 32 month evaluation, she exhibited severe depression (Beck Depression Inventory-II: 42 [full score: 63 score] and Patient Health Questionnaire-9: 24 [full score: 27 score]).

RESULTS

On 32-month DTT, partical tearing of the dorsolateral prefronto-thalamic tract was observed in the right hemisphere and thinning in the left hemisphere.

CONCLUSION

Injury of the dorsolateral prefronto-thalamic tract was demonstrated in a patient with depression following mild traumatic brain injury, using DTT. We believe that injury of the dorsolateral prefronto-thalamic tract might be a pathogenetic mechanism of depression in patients with brain injury.

Diffusion tensor imaging of occult injury of optic radiation following optic neuritis in multiple sclerosis

Multiple sclerosis (MS) is easily detected by routine magnetic resonance imaging (MRI). However, it is not possible to detect early or occult lesions in MS by routine MRI, and this may explain the inconsistency between the severity of the lesions found by MRI and the degree of clinical disability of patients with MS. The present study included 10 patients with relapsing-remitting MS and 10 healthy volunteers. Each patient underwent routine 3.0 T MRI, diffusion tensor imaging (DTI), and diffusion tensor tractography (DTT). Optic nerve and optic radiation were analyzed by DTI and DTT. The fractional anisotropy (FA), mean diffusivity (MD), λ_//, and λ_┴ values were measured. In the 10 patients with MS, 7 optic nerves were affected, and 13 optic nerves were not affected. Cranial MRI showed that optic nerve thickening and hyperintensity occurred in 2 patients with MS. In the directionally encoded color maps, a hypointensive green signal in the optic nerve was observed in 3 patients with MS. The FA values were significantly lower and the MD, λ_//, and λ_┴ values were significantly higher in the affected and unaffected optic nerves and optic radiations in patients with MS in comparison with controls (P<0.05). There were no significant differences in these values between the affected and unaffected optic nerves and optic radiation in patients with MS (P>0.05). Diffusion tensor imaging is sensitive in the detection of occult injury of the optic nerve and optic radiation following optic neuritis. Diffusion tensor imaging may be a useful tool for the early diagnosis, treatment and management of MS.

Prediction of motor outcome by shoulder subluxation at early stage of stroke

We attempted to determine whether shoulder subluxation at the early stage of stroke can predict motor outcome in relation to the corticospinal tract (CST) state on diffusion tensor tractography.Fifty-nine stroke patients with severe hemiparesis were recruited. The patients were classified according to the distance of shoulder subluxation (group A: ≥2 cm, group B: <2 cm) and the affected CST on diffusion tensor tractography at the first evaluation (CST type A-the CST was discontinued at the stroke lesion; CST type B-the integrity of the CST was preserved). Motor function of the patients was evaluated twice (first: beginning of rehabilitation-24.1 ± 16.6 days; second: discharge after first rehabilitation-58.5 ± 24.1 days) using the Medical Research Council score, Motricity Index, and Modified Brunnstrom Classification.Regarding the improvement of the Medical Research Council for the finger extensor and upper Motricity Index, the order in terms of better recovery was as follows: group B-type B, group A-type B, group B-type A, and group A-type A (P < 0.05). The distance of shoulder subluxation showed significant correlation with improvement of the finger extensor (moderate negative correlation, r = -0.37) and improvement of the Modified Brunnstrom Classification (weak negative correlation, r = -0.29) (P < 0.05).The presence of shoulder subluxation at the early stage of stroke can be a predictor of motor outcome of the affected upper extremity and the degree of shoulder subluxation can be a predictor of the motor function of the affected hand. Therefore, our results suggest that shoulder subluxation in relation to the affected CST state at the early stage of stroke can be a prognostic factor for motor outcome.

Clinical and MRI findings of cerebellar agenesis in two living adult patients

Cerebellar agenesis (CA) is an extremely rare entity. We present two adult patients with CA. The 61-year-old man had ataxia, dysarthria, abnormalities in cerebellar tests, severe cognitive impairment, and moderate mental retardation. The 26-year-old woman had dysmetria, dysdiadochokinesia, and dysarthria as well as mild cognitive impairment and mild mental retardation. Magnetic resonance imaging (MRI) showed complete absence of the cerebellum with small residual vermis. Brainstem was hypoplastic and structures above tentorium were normal. Supratentorial white matter bundles were unaffected in diffusion tensor tractography. Only few adult patients with CA have so far been published. These cases show that patients with CA present with a variety of developmental, clinical, and mental abnormalities; and emphasize the role of the cerebellum in normal motor, language, and mental development.

Injury of the inferior cerebellar peduncle in patients with mild traumatic brain injury: A diffusion tensor tractography study

OBJECTIVES

No study on injury of the inferior cerebellar peduncle (ICP) in patients with mild traumatic brain injury (mTBI) has been reported. This study, using diffusion tensor tractography (DTT), attempted to demonstrate injury of the ICP in patients with mTBI.

METHODS

Three patients with mTBI resulting from a car accident and 18 normal healthy control subjects were enrolled in this study. Diffusion tensor imaging data were acquired at 2 months (patient 1) and 3 months (patients 2 and 3) after onset and the ICP was reconstructed. The Balance Error Scoring System was used for evaluation of balance at the same time diffusion tensor imaging scanning was performed.

RESULTS

The ICPs were discontinued at the upper portion of the vertical cerebellar branch and the transverse cerebellar branch (patient 1) and the proximal portion of the transverse cerebellar branch (patients 2 and 3) compared to the normal control subjects. Regarding DTT parameters, in the three patients, the fibre number of the ICPs was decreased by more than 2 SD compared with those of subjects in the control group.

CONCLUSION

Evaluation of the ICP using DTT would be useful in patients with a balance problem after mTBI.

Recovery of consciousness and an injured ascending reticular activating system in a patient who survived cardiac arrest: A case report

We report on a patient who survived cardiac arrest and showed recovery of consciousness and an injured ARAS at the early stage of hypoxic-ischemic brain injury (HI- BI) for 3 weeks, which was demonstrated by diffusion tensor tractography (DTT).A 52-year-old male patient who had suffered cardiac arrest caused by acute coronary syndrome was resuscitated immediately by a layman and paramedics for ∼25 minutes. He was then transferred immediately to the emergency room of a local medical center. When starting rehabilitation at 2 weeks after onset, his consciousness was impaired, with a Glasgow Coma Scale (GCS) score of 8 and Coma Recovery Scale-Revised (GRS-R) score of 8. He underwent comprehensive rehabilitative therapy, including drugs for recovery of consciousness. He recovered well and rapidly so that his consciousness had recovered to full scores in terms of GCS:15 and GRS-R:23 at 5 weeks after onset.The left lower dorsal and right lower ventral ARAS had become thicker on 5-week DTT compared with 2-week DTT (Fig. 1B). Regarding the change of neural connectivity of the thalamic ILN, increased neural connectivity to the basal forebrain and prefrontal cortex was observed in both hemispheres on 5-week DTT compared with 2-week DTT.Recovery of an injured ARAS was demonstrated in a patient who survived cardiac arrest and his consciousness showed rapid and good recovery for 3 weeks at the early stage of HI-BI.

4.7-T diffusion tensor imaging of acute traumatic peripheral nerve injury

Diagnosis and management of peripheral nerve injury is complicated by the inability to assess microstructural features of injured nerve fibers via clinical examination and electrophysiology. Diffusion tensor imaging (DTI) has been shown to accurately detect nerve injury and regeneration in crush models of peripheral nerve injury, but no prior studies have been conducted on nerve transection, a surgical emergency that can lead to permanent weakness or paralysis. Acute sciatic nerve injuries were performed microsurgically to produce multiple grades of nerve transection in rats that were harvested 1 hour after surgery. High-resolution diffusion tensor images from ex vivo sciatic nerves were obtained using diffusion-weighted spin-echo acquisitions at 4.7 T. Fractional anisotropy was significantly reduced at the injury sites of transected rats compared with sham rats. Additionally, minor eigenvalues and radial diffusivity were profoundly elevated at all injury sites and were negatively correlated to the degree of injury. Diffusion tensor tractography showed discontinuities at all injury sites and significantly reduced continuous tract counts. These findings demonstrate that high-resolution DTI is a promising tool for acute diagnosis and grading of traumatic peripheral nerve injuries.

Degeneration of an injured spinothalamic tract in a patient with mild traumatic brain injury

OBJECTIVES

This study reports on a patient who developed degeneration of an injured spinothalamic tract (STT) detected on diffusion tensor tractography (DTT) following mild traumatic brain injury (TBI).

CASE DESCRIPTION

A 56-year-old female had suffered from head trauma resulting from a pedestrian car accident. The patient did not experience loss of consciousness or post-traumatic amnesia and the patient's Glasgow Coma Scale score was 15. She had begun to feel pain in her left hand and foot at ~ 7 days after onset. The characteristics and severity of pain were as follows: constant tingling and pricking sensation without allodynia or hyperalgesia (Visual Analogue Scale score: 3~4). No specific focal lesion was observed on brain and spine MRI and an electromyography study showed no evidence of peripheral nerve injury or radiculopathy. At 6 months after onset, the central pain in the left hand and foot became aggravated, with a Visual Analogue Scale score of 6.

RESULTS

On 1-month DTT, partial tearing was observed in both STTs. In contrast, both partially torn STTs had become atrophy on 9-month DTT.

CONCLUSIONS

This study recommends further studies conducted on the prognosis (regeneration or degeneration) of injured STTs and on the effect of change of an injured STT on central pain.

Brodmann's Area Template Based Region of Interest Setting and Probabilistic Pathway Map Generation in Diffusion Tensor Tractography: Application to the Arcuate Fasciculus Fiber Tract in the Human Brain

The purpose of this study is to acquire accurate diffusion tensor tractography (DTT) results for arcuate fasciculus (AF) fiber tract using Brodmann's area (BA) template for region of interest (ROI) setting. Thirteen healthy subjects were participated in this study. Fractional anisotropy (FA) map of each subject was calculated using diffusion tensor data, and T1w template was co-registered to FA map. The BA template was also co-registered using the transformation matrix. The ROIs were drawn in the co-registered BA template, and AF fiber tract was extracted. To generate the probabilistic pathway map, a binary mask image was generated based on the fiber tract image and co-registered to T1w template image. We also measured relative location of the AF fiber tract. The location of the probabilistic pathway map of each subject's AF fiber tract was well defined in the brain. By using this probabilistic map, the mediolateral position ratio of AF was measured 18%, and the anteroposterior position ratio of AF was measured 35%, respectively. This study demonstrated that the AF fiber tract can be extracted using BA template for ROI setting and probabilistic pathway of fiber tract. Our results and analytical approaches can helpful for accurate fiber tracking and application of perspective clinical researches.

Traumatic brain injury and the post-concussion syndrome: A diffusion tensor tractography study

Aim:

The aim of the present study is to evaluate diffusion tensor tractography (DTT) as a tool for detecting diffuse axonal injury in patients of acute, mild, and moderate traumatic brain injury (TBI), using two diffusion variables: Fractional anisotropy (FA) and mean diffusivity (MD). The correlation of these indices with the severity of post-concussive symptoms was also assessed.

Materials and Methods:

Nineteen patients with acute, mild, or moderate TBI and twelve age- and sex-matched healthy controls were recruited. Following Magnetic Resonance Imaging (MRI) on a 3.0-T scanner, DTT was performed using the ‘fiber assignment by continuous tracking’ (FACT) algorithm for fiber reconstruction. Appropriate statistical tools were used to see the difference in FA and MD values between the control and patient groups. In the latter group, the severity of post-concussive symptoms was assessed six months following trauma, using the Rivermead Postconcussion Symptoms Questionnaire (RPSQ).

Results:

The patients displayed significant reduction in FA compared to the controls (P < 0.05) in several tracts, notably the corpus callosum, fornix, bilateral uncinate fasciculus, and bilateral superior thalamic radiations. Changes in MD were statistically significant in the left uncinate, inferior longitudinal fasciculus, and left posterior thalamic radiation. A strong correlation between these indices and the RPSQ scores was observed in several white matter tracts.

Conclusion:

Diffusion tensor imaging (DTI)-based quantitative analysis in acute, mild, and moderate TBI can identify axonal injury neuropathology, over and above that visualized on conventional MRI scans. Furthermore, the significant correlation observed between FA and MD indices and the severity of post-concussive symptoms could make it a useful predictor of the long-term outcome.

Age-Related Differences and Heritability of the Perisylvian Language Networks

Acquisition of language skills depends on the progressive maturation of specialized brain networks that are usually lateralized in adult population. However, how genetic and environmental factors relate to the age-related differences in lateralization of these language pathways is still not known. We recruited 101 healthy right-handed subjects aged 9-40 years to investigate age-related differences in the anatomy of perisylvian language pathways and 86 adult twins (52 monozygotic and 34 dizygotic) to understand how heritability factors influence language anatomy. Diffusion tractography was used to dissect and extract indirect volume measures from the three segments of the arcuate fasciculus connecting Wernicke's to Broca's region (i.e., long segment), Broca's to Geschwind's region (i.e., anterior segment), and Wernicke's to Geschwind's region (i.e., posterior segment). We found that the long and anterior arcuate segments are lateralized before adolescence and their lateralization remains stable throughout adolescence and early adulthood. Conversely, the posterior segment shows right lateralization in childhood but becomes progressively bilateral during adolescence, driven by a reduction in volume in the right hemisphere. Analysis of the twin sample showed that genetic and shared environmental factors influence the anatomy of those segments that lateralize earlier, whereas specific environmental effects drive the variability in the volume of the posterior segment that continues to change in adolescence and adulthood. Our results suggest that the age-related differences in the lateralization of the language perisylvian pathways are related to the relative contribution of genetic and environmental effects specific to each segment.

SIGNIFICANCE STATEMENT

Our study shows that, by early childhood, frontotemporal (long segment) and frontoparietal (anterior segment) connections of the arcuate fasciculus are left and right lateralized, respectively, and remain lateralized throughout adolescence and early adulthood. In contrast, temporoparietal (posterior segment) connections are right lateralized in childhood, but become progressively bilateral during adolescence. Preliminary twin analysis suggested that lateralization of the arcuate fasciculus is a heterogeneous process that depends on the interplay between genetic and environment factors specific to each segment. Tracts that exhibit higher age effects later in life (i.e., posterior segment) appear to be influenced more by specific environmental factors.

Basic Principle and Image Analysis in the Diffusion Tensor Image

The magnetic resonance imaging (MRI) is established as the imaging technique that is essential to the imaging of the central nervous system disease. Above all, the diffusion weighted image (DWI) is known as the tool which can diagnose acute ischemic stroke with high accuracy in a short time. DTI, an applied form of DWI, was devised as a technique to image the structure of the brain white matter. In clinical sites, this technique is used for pathologic elucidation such as the intracerebral tissue injury or mental disorder. Additionally, diffusion tensor tractography (DTT), which is a technique to build three-dimensional structure of the neural fiber tracts, is used for grasping the relations between a brain tumor and the fibers tract. Therefore, these techniques may be useful imaging tools in the central nerve region.

Diffusion tensor imaging of the nigrostriatal fibers in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is histopathologically characterized by the loss of dopamine neurons in the substantia nigra pars compacta. The depletion of these neurons is thought to reduce the dopaminergic function of the nigrostriatal pathway, as well as the neural fibers that link the substantia nigra to the striatum (putamen and caudate), causing a dysregulation in striatal activity that ultimately leads to lack of movement control. Based on diffusion tensor imaging, visualizing this pathway and measuring alterations of the fiber integrity remain challenging. The objectives were to 1) develop a diffusion tensor tractography protocol for reliably tracking the nigrostriatal fibers on multicenter data; 2) test whether the integrities measured by diffusion tensor imaging of the nigrostriatal fibers are abnormal in PD; and 3) test whether abnormal integrities of the nigrostriatal fibers in PD patients are associated with the severity of motor disability and putaminal dopamine binding ratios.

METHODS

Diffusion tensor tractography was performed on 50 drug-naïve PD patients and 27 healthy control subjects from the international multicenter Parkinson's Progression Marker Initiative.

RESULTS

Tractography consistently detected the nigrostriatal fibers, yielding reliable diffusion measures. Fractional anisotropy, along with radial and axial diffusivity of the nigrostriatal tract, showed systematic abnormalities in patients. In addition, variations in fractional anisotropy and radial diffusivity of the nigrostriatal tract were associated with the degree of motor deficits in PD patients.

CONCLUSION

Taken together, the findings imply that the diffusion tensor imaging characteristic of the nigrostriatal tract is potentially an index for detecting and staging of early PD.

Combined use of diffusion tensor tractography and multifused contrast-enhanced FIESTA for predicting facial and cochlear nerve positions in relation to vestibular schwannoma

OBJECT

The authors assessed whether the combined use of diffusion tensor tractography (DTT) and contrast-enhanced (CE) fast imaging employing steady-state acquisition (FIESTA) could improve the accuracy of predicting the courses of the facial and cochlear nerves before surgery.

METHODS

The population was composed of 22 patients with vestibular schwannoma in whom both the facial and cochlear nerves could be identified during surgery. According to DTT, depicted fibers running from the internal auditory canal to the brainstem were judged to represent the facial or vestibulocochlear nerve. With regard to imaging, the authors investigated multifused CE-FIESTA scans, in which all 3D vessel models were shown simultaneously, from various angles. The low-intensity areas running along the tumor from brainstem to the internal auditory canal were judged to represent the facial or vestibulocochlear nerve.

RESULTS

For all 22 patients, the rate of fibers depicted by DTT coinciding with the facial nerve was 13.6% (3/22), and that of fibers depicted by DTT coinciding with the cochlear nerve was 63.6% (14/22). The rate of candidates for nerves predicted by multifused CE-FIESTA coinciding with the facial nerve was 59.1% (13/22), and that of candidates for nerves predicted by multifused CE-FIESTA coinciding with the cochlear nerve was 4.5% (1/22). The rate of candidates for nerves predicted by combined DTT and multifused CE-FIESTA coinciding with the facial nerve was 63.6% (14/22), and that of candidates for nerves predicted by combined DTT and multifused CE-FIESTA coinciding with the cochlear nerve was 63.6% (14/22). The rate of candidates predicted by DTT coinciding with both facial and cochlear nerves was 0.0% (0/22), that of candidates predicted by multifused CE-FIESTA coinciding with both facial and cochlear nerves was 4.5% (1/22), and that of candidates predicted by combined DTT and multifused CE-FIESTA coinciding with both the facial and cochlear nerves was 45.5% (10/22).

CONCLUSIONS

By using a combination of DTT and multifused CE-FIESTA, the authors were able to increase the number of vestibular schwannoma patients for whom predicted results corresponded with the courses of both the facial and cochlear nerves, a result that has been considered difficult to achieve by use of a single modality only. Although the 3D image including these prediction results helped with comprehension of the 3D operative anatomy, the reliability of prediction remains to be established.

Diffusion tensor imaging of the human cerebellar pathways and their interplay with cerebral macrostructure

Cerebellar white matter (WM) connections to the central nervous system are classified functionally into the Spinocerebellar (SC), vestibulocerebellar (VC), and cerebrocerebellar subdivisions. The SC pathways project from spinal cord to cerebellum, whereas the VC pathways project from vestibular organs of the inner ear. Cerebrocerebellar connections are composed of feed forward and feedback connections between cerebrum and cerebellum including the cortico-ponto-cerebellar (CPC) pathways being of cortical origin and the dentate-rubro-thalamo-cortical (DRTC) pathway being of cerebellar origin. In this study we systematically quantified the whole cerebellar system connections using diffusion tensor magnetic resonance imaging (DT-MRI). Ten right-handed healthy subjects (7 males and 3 females, age range 20–51 years) were studied. DT-MRI data were acquired with a voxel size = 2 mm × 2 mm × 2 mm at a 3.0 Tesla clinical MRI scanner. The DT-MRI data were prepared and analyzed using anatomically-guided deterministic tractography methods to reconstruct the SC, DRTC, fronto-ponto-cerebellar (FPC), parieto-ponto-cerebellar (PPC), temporo-ponto-cerebellar (TPC) and occipito-ponto-cerebellar (OPC). The DTI-attributes or the cerebellar tracts along with their cortical representation (Brodmann areas) were presented in standard Montréal Neurological Institute space. All cerebellar tract volumes were quantified and correlated with volumes of cerebral cortical, subcortical gray matter (GM), cerebral WM and cerebellar GM, and cerebellar WM. On our healthy cohort, the ratio of total cerebellar GM-to-WM was ~3.29 ± 0.24, whereas the ratio of cerebral GM-to-WM was approximately 1.10 ± 0.11. The sum of all cerebellar tract volumes is ~25.8 ± 7.3 mL, or a percentage of 1.6 ± 0.45 of the total intracranial volume (ICV).

Magnetic resonance diffusion tensor imaging-based evaluation of optic-radiation shape and position in meningioma

Employing magnetic resonance diffusion tensor imaging, three-dimensional white-matter imaging and conventional magnetic resonance imaging can demonstrate the tumor parenchyma, peritumoral edema and compression on surrounding brain tissue. A color-coded tensor map and three-dimensional tracer diagram were applied to clearly display the optic-radiation location, course and damage. Results showed that the altered anisotropy values of meningioma patients corresponded with optic-radiation shape, size and position on both sides. Experimental findings indicate that the magnetic resonance diffusion tensor imaging technique is a means of tracing and clearly visualizing the optic radiation.

Recovery of Visual Field Defect via Corpus Callosum in a Patient with Cerebral Infarct

Recovery mechanism of visual field defect in stroke patients has not been clearly elucidated. In this study, we report on a patient with a cerebral infarct who showed recovery of visual field defect via the corpus callosum, using diffusion tensor tractography (DTT) for optic radiation (OR). A 57-year-old male patient underwent conservative management for a cerebral infarct in the subcortical white matter of the right temporal lobe. Left homonymous hemianopsia was detected on the 2-week Humphrey visual field test. However, the patient showed improvement of hemianopsia with time; consequently, a left lower peripheral visual defect with the resolution of the upper and medial portions of the initial left hemianopia was observed on the 11-month Humphrey visual field test. Both 2-week and 11-month DTTs for the right OR showed a discontinuation between the right lateral geniculate nucleus (LGN) and the right OR. On 2-week DTT, the left OR was connected to the transcallosal fibres, and on 11-month DTT, these transcallosal fibres were elongated to the right primary visual cortex via the right posterior OR. The visual field defect in this patient appears to have recovered by the neural pathway originating from the left OR and terminating in the primary visual cortex via the transcallosal fibres and right distal OR. We believe that the results of this study may suggest one of the mechanisms for recovery of visual field defect following injury of OR in stroke patients.

The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations

OBJECT

Resection of brainstem cavernous malformations (BSCMs) may reduce the risk of stepwise neurological deterioration secondary to hemorrhage, but the morbidity of surgery remains high. Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are neuroimaging techniques that may assist in the complex surgical planning necessary for these lesions. The authors evaluate the utility of preoperative DTI and DTT in the surgical management of BSCMs and their correlation with functional outcome.

METHODS

A retrospective review was conducted to identify patients who underwent resection of a BSCM between 2007 and 2012. All patients had preoperative DTI/DTT studies and a minimum of 6 months of clinical and radiographic follow-up. Five major fiber tracts were evaluated preoperatively using the DTI/DTT protocol: 1) corticospinal tract, 2) medial lemniscus and medial longitudinal fasciculus, 3) inferior cerebellar peduncle, 4) middle cerebellar peduncle, and 5) superior cerebellar peduncle. Scores were applied according to the degree of distortion seen, and the sum of scores was used for analysis. Functional outcomes were measured at hospital admission, discharge, and last clinic visit using modified Rankin Scale (mRS) scores.

RESULTS

Eleven patients who underwent resection of a BSCM and preoperative DTI were identified. The mean age at presentation was 49 years, with a male-to-female ratio of 1.75:1. Cranial nerve deficit was the most common presenting symptom (81.8%), followed by cerebellar signs or gait/balance difficulties (54.5%) and hemibody anesthesia (27.2%). The majority of the lesions were located within the pons (54.5%). The mean diameter and estimated volume of lesions were 1.21 cm and 1.93 cm(3), respectively. Using DTI and DTT, 9 patients (82%) were found to have involvement of 2 or more major fiber tracts; the corticospinal tract and medial lemniscus/medial longitudinal fasciculus were the most commonly affected. In 2 patients with BSCMs without pial presentation, DTI/DTT findings were important in the selection of the surgical approach. In 2 other patients, the results from preoperative DTI/DTT were important for selection of brainstem entry zones. All 11 patients underwent gross-total resection of their BSCMs. After a mean postoperative follow-up duration of 32.04 months, all 11 patients had excellent or good outcome (mRS Score 0-3) at the time of last outpatient clinic evaluation. DTI score did not correlate with long-term outcome.

CONCLUSIONS

Preoperative DTI and DTT should be considered in the resection of symptomatic BSCMs. These imaging studies may influence the selection of surgical approach or brainstem entry zones, especially in deep-seated lesions without pial or ependymal presentation. DTI/DTT findings may allow for more aggressive management of lesions previously considered surgically inaccessible. Preoperative DTI/DTT changes do not appear to correlate with functional postoperative outcome in long-term follow-up.

A case of hypertrophic olivary degeneration after resection of cavernomas of the brain stem and review of the literature

Hypertrophic olivary degeneration is a transsynaptic form of degeneration, which is also a result of primary or secondary lesion and can damage the dento-rubro-olivary pathway. The dento-rubro-olivary pathway was first described by Guillain and Mollaret and is referred to as "the triangle of Guillain and Mollaret". Multiple factors can destroy the dento-rubro-olivary pathway, such as surgical operation, hemorrhage, tumor, trauma, inflammation, demyelination, degeneration, and radiation damage. All of the above factors can result in delayed hypertrophic olivary degeneration. Articles related to this disease cover etiology, clinical presentation, pathology changes, etc. However, to our knowledge, there has been no literature reporting the use of diffusion tensor imaging and diffusion tensor tractography to improve the diagnosis of hypertrophic olivary degeneration following resection of cavernomas in the brain stem. Herein, we report a case who was diagnosed with hypertrophic olivary degeneration following resection of cavernomas of the brain stem, verify the significance of diffusion tensor imaging and diffusion tensor tractography, and review previous literature. The development of imageology promotes and improves hypertrophic olivary degeneration diagnosis and differential diagnosis.

Diffusion tensor tractography in hypothyroidism and its correlation with memory function

Diffusion tensor tractography (DTT) was performed to determine the microstructural changes in the white matter fibre tracts of hypothyroid patients compared to controls and to correlate these changes with memory dysfunction scores. DTT and Postgraduate Institute Memory Scale test were performed in eight hypothyroid patients and eight healthy controls. Diffusion tensor imaging (DTI) measures [fractional anisotropy (FA) and mean diffusivity (MD)] from all of the major cerebral tracts were calculated and a comparison was made between the patient group and controls. Pearson's correlation was performed between Memory Dysfunction score and DTI measures. Significant changes in DTI measures were observed in various white matter fibre tracts in hypothyroid patients compared to controls. In hypothyroid patients, an inverse correlation of Memory Dysfunction score with FA was observed in the right and left inferior fronto-occipital fasciculus, whereas a positive correlation with MD was observed in the right anterior thalamic radiation among all white matter tracts. These findings suggest that microstructural changes in white matter fibres may contribute to the underlying dysfunction in memory in hypothyroid patients.

Associations between Proprioceptive Neural Pathway Structural Connectivity and Balance in People with Multiple Sclerosis

Mobility and balance impairments are a hallmark of multiple sclerosis (MS), affecting nearly half of patients at presentation and resulting in decreased activity and participation, falls, injuries, and reduced quality of life. A growing body of work suggests that balance impairments in people with mild MS are primarily the result of deficits in proprioception, the ability to determine body position in space in the absence of vision. A better understanding of the pathophysiology of balance disturbances in MS is needed to develop evidence-based rehabilitation approaches. The purpose of the current study was to (1) map the cortical proprioceptive pathway in vivo using diffusion-weighted imaging and (2) assess associations between proprioceptive pathway white matter microstructural integrity and performance on clinical and behavioral balance tasks. We hypothesized that people with MS (PwMS) would have reduced integrity of cerebral proprioceptive pathways, and that reduced white matter microstructure within these tracts would be strongly related to proprioceptive-based balance deficits. We found poorer balance control on proprioceptive-based tasks and reduced white matter microstructural integrity of the cortical proprioceptive tracts in PwMS compared with age-matched healthy controls (HC). Microstructural integrity of this pathway in the right hemisphere was also strongly associated with proprioceptive-based balance control in PwMS and controls. Conversely, while white matter integrity of the right hemisphere’s proprioceptive pathway was significantly correlated with overall balance performance in HC, there was no such relationship in PwMS. These results augment existing literature suggesting that balance control in PwMS may become more dependent upon (1) cerebellar-regulated proprioceptive control, (2) the vestibular system, and/or (3) the visual system.

Corticospinal tract recovery in a patient with traumatic transtentorial herniation

Transtentorial herniation is one of the causes of motor weakness in traumatic brain injury. In this study, we report on a patient who underwent decompressive craniectomy due to traumatic intracerebral hemorrhage. Brain CT images taken after surgery showed intracerebral hemorrhage in the left fronto-temporal lobe and left transtentorial herniation. The patient presented with severe paralysis of the right extremities at the time of intracerebral hemorrhage onset, but the limb motor function recovered partially at 6 months after onset and to nearly normal level at 27 months. Through diffusion tensor tractography, the left corticospinal tract was disrupted below the cerebral peduncle at 1 month after onset and the disrupted left corticospinal tract was reconstructed at 27 months. These findings suggest that recovery of limb motor function in a patient with traumatic transtentorial herniation can come to be true by recovery of corticospinal tract.

Injury of the cingulum in patients with putaminal hemorrhage: a diffusion tensor tractography study

Objectives: Little is known about the pathophysiological mechanisms of cognitive impairment in patients with putaminal hemorrhage (PH). Using diffusion tensor tractography, we investigated injury of the cingulum in patients with PH.

Methods: We recruited 63 patients with PH, who were classified according to three groups, based on integrity of the cingulum to the lower portion of the genu of the corpus callosum: group A; preserved integrity, group B; discontinuation of integrity in the affected hemisphere, and group C; discontinuation of integrity in both hemispheres.

Results: Thirty four patients (54.0%) belonged to group A, 16 patients (25.4%) to group B, and the remaining 13 patients (20.6%) to group C. Regarding the Mini-Mental State Examination, significant differences were observed between group A and group C, and between group B and group C without significant difference between group A and group B (p < 0.05). In terms of the volume of hematoma, significant differences were observed among the three groups (p < 0.05). Regarding the most anterior point of the hematoma, significant differences were observed between group A and groups B and C (p < 0.05); in contrast, regarding the most point of hematoma, significant differences were observed between group C and groups A and B, respectively (p < 0.05).

Conclusion: We found that the anterior cingulum is vulnerable to PH. Therefore, our results suggest the necessity for evaluation of the cingulum in patients with PH particularly if the hematoma is large or close to the anterior margin or midline of the brain.

Injury of the mammillothalamic tract in patients with thalamic hemorrhage

Objective: Injury of the mammillothalamic tract (MTT) has been suggested as one of the plausible pathogenic mechanisms of memory impairment in patients with thalamic hemorrhage; however, it has not been clearly demonstrated so far. We attempted to investigate whether injury of the MTT documented by diffusion tensor tractography following thalamic hemorrhage correlates with cognitive impairment.

Methods: We recruited 22 patients with a thalamic hemorrhage and 20 control subjects. MTTs were reconstructed using the probabilistic tractography method. Patients were classified into two subgroups: reconstructed group, patients whose MTT was reconstructed in the affected hemisphere, and non-reconstructed group, patients whose MTT was not reconstructed.

Results: Mammillothalamic tract was reconstructed in 5 (22.7%, reconstructed group) patients in the affected hemisphere and was not reconstructed in the remaining 17 patients (77.3%, non-reconstructed group). In addition, the MTT was not reconstructed even in the unaffected hemisphere in four patients (23.5%) in non-reconstructed group. Fractional anisotropy and mean diffusivity values of the affected hemisphere in reconstructed group also did not show significant differences from those in the unaffected hemisphere of reconstructed group and the control group (p > 0.05). However, the tract volume of the affected hemisphere in reconstructed group was significantly lower than that of the unaffected hemisphere in reconstructed group and the control group (p < 0.05).

Conclusion: A large portion of patients with thalamic hemorrhage appeared to suffer severe injury of the ipsilesional MTT (77.3%) and 18.2% of them appeared to suffer severe injury even in the contralesional MTT. In addition, the remaining 22.7% of patients who had preserved integrity of the ipsilesional MTT appeared to suffer partial injury of the ipsilesional MTT.

Diffusion tensor tractography in the presurgical assessment of cerebral gliomas

Glioma is the most common intra-axial brain tumor characterized by invasion into the surrounding white matter (WM) tracts. These tumors are usually diagnosed by conventional MRI, but this method is unable to describe the relationship between tumor and neighboring WM tracts. Diffusion tensor tractography (DTT) is a new imaging modality which can solve this problem. The current study evaluated the application of DTT imaging in the presurgical assessment of gliomas, and introduces this new modality and its importance to physicians and imaging centers in Iran. Ten patients with intra-axial brain tumor and suspicion of glioma underwent conventional brain MRI pulse sequences and DTT imaging between December 2011 and February 2013 with a 1.5 Tesla system using 64 independent diffusion encoding directions. Acquired images were assessed by the neuroradiologist and neurosurgeon. The treatment strategies were recognized and compared using data before and after the tractography. On the basis of DTT data, the treatment strategy changed from radiotherapy to the craniotomy in seven patients, and in one patient, the neurosurgeon preferred to avoid surgery. In one patient, the treatment technique did not change, and in the last one radiosurgery was replaced by craniotomy. As we can infer from this study, based on the tractography results, the treatment strategy may be changed, and the treatment technique could be devised more accurately and may lead to fewer postoperative neurological deficits and better outcomes.

Quantitative volumetric analysis of the optic radiation in the normal human brain using diffusion tensor magnetic resonance imaging-based tractography

To attain the volumetric information of the optic radiation in normal human brains, we performed diffusion tensor imaging examination in 13 healthy volunteers. Simultaneously, we used a brain normalization method to reduce individual brain variation and increase the accuracy of volumetric information analysis. In addition, tractography-based group mapping method was also used to investigate the probability and distribution of the optic radiation pathways. Our results showed that the measured optic radiation fiber tract volume was a range of about 0.16% and that the fractional anisotropy value was about 0.53. Moreover, the optic radiation probability fiber pathway that was determined with diffusion tensor tractography-based group mapping was able to detect the location relatively accurately. We believe that our methods and results are helpful in the study of optic radiation fiber tract information.

Relative anterior safe area for invasive procedures in the human brain: diffusion tensor tractography

OBJECTIVE

Many interventions, including surgery, procedures of shunt operation, or radiotherapy could result in neural injury of the brain. However, research to prevent or minimize injury of neural tracts has been overlooked.

MATERIAL AND METHODS

We recruited 41 healthy subjects. Diffusion tensor images were acquired and five neural tracts were reconstructed (corticospinal tract, corticoreticular pathway, arcuate fasciculus, cingulum, and superior longitudinal fasciculus). We defined the safe area, which is an area free from any trajectory of five neural tracts: the medial boundary - the most lateral point free from any trajectory of five neural tracts, the posterior boundary - the most anterior point free from any trajectory of five neural tracts.

RESULTS

Medial boundaries of the safe area in the cortex, centrum semiovale, corona radiata, and internal capsule were located at an average of 0 mm, 12.28 mm, 12.43 mm, and 10.34 mm laterally from the midline, respectively, and the posterior boundaries were located at an average of 1.30 mm, 4.26 mm, 7.05 mm, and 5.74 mm from the ACL, respectively. In addition, we found that the common safe areas for all four axial levels were located at 13.44 mm (medial boundary) and 9.35 mm (posterior boundary).

CONCLUSION

We identified a relatively safe area for the performance of invasive procedures in the anterior portion of the human brain.

Dissociated repetition deficits in aphasia can reflect flexible interactions between left dorsal and ventral streams and gender-dimorphic architecture of the right dorsal stream

Assessment of brain-damaged subjects presenting with dissociated repetition deficits after selective injury to either the left dorsal or ventral auditory pathways can provide further insight on their respective roles in verbal repetition. We evaluated repetition performance and its neural correlates using multimodal imaging (anatomical MRI, DTI, fMRI, and¹⁸FDG-PET) in a female patient with transcortical motor aphasia (TCMA) and in a male patient with conduction aphasia (CA) who had small contiguous but non-overlapping left perisylvian infarctions. Repetition in the TCMA patient was fully preserved except for a mild impairment in nonwords and digits, whereas the CA patient had impaired repetition of nonwords, digits and word triplet lists. Sentence repetition was impaired, but he repeated novel sentences significantly better than clichés. The TCMA patient had tissue damage and reduced metabolism in the left sensorimotor cortex and insula. DTI showed damage to the left temporo-frontal and parieto-frontal segments of the arcuate fasciculus (AF) and part of the left ventral stream together with well-developed right dorsal and ventral streams, as has been reported in more than one-third of females. The CA patient had tissue damage and reduced metabolic activity in the left temporoparietal cortex with additional metabolic decrements in the left frontal lobe. DTI showed damage to the left temporo-parietal and temporo-frontal segments of the AF, but the ventral stream was spared. The direct segment of the AF in the right hemisphere was also absent with only vestigial remains of the other dorsal subcomponents present, as is often found in males. fMRI during word and nonword repetition revealed bilateral perisylvian activation in the TCMA patient suggesting recruitment of spared segments of the left dorsal stream and right dorsal stream with propagation of signals to temporal lobe structures suggesting a compensatory reallocation of resources via the ventral streams. The CA patient showed a greater activation of these cortical areas than the TCMA patient, but these changes did not result in normal performance. Repetition of word triplet lists activated bilateral perisylvian cortices in both patients, but activation in the CA patient with very poor performance was restricted to small frontal and posterior temporal foci bilaterally. These findings suggest that dissociated repetition deficits in our cases are probably reliant on flexible interactions between left dorsal stream (spared segments, short tracts remains) and left ventral stream and on gender-dimorphic architecture of the right dorsal stream.

Motor recovery by improvement of limb-kinetic apraxia in a chronic stroke patient

OBJECTIVES

We report on a chronic stroke patient who showed motor recovery by improvement of limb-kinetic apraxia (LKA) after undergoing intensive rehabilitation for a period of one month, which was demonstrated by diffusion tensor tractography (DTT) and transcranial magnetic stimulation (TMS).

METHODS

A 50-year-old male patient presented with severe paralysis of the left extremities at the onset of thalamic hemorrhage. At thirty months after onset, the patient exhibited moderate weakness of his left upper and lower extremities. In addition, he exhibited a slow, clumsy, and mutilated movement pattern during grasp-release movements of his left hand. During a one-month period of intensive rehabilitation, which was started at thrity months after onset, the patient showed 22% motor recovery of the left extremities. The slow, clumsy, and mutilated movement pattern of the left hand almost disappeared.

RESULTS

DTTs of the corticospinal tract (CST) in both hemispheres originated from the cerebral cortex, including the primary motor cortex, and passed along the known CST pathway. The DTT of the right CST was located anterior to the old hemorrhagic lesion. TMS study performed at thirty and thirty-one months after onset showed normal and similar findings for motor evoked potential in terms of latency and amplitude of the left hand muscle.

CONCLUSIONS

We think that the motor weakness of the left extremities in this patient was mainly ascribed to LKA and that most of the motor recovery during a one-month period of rehabilitation was attributed to improvement of LKA.

Human middle longitudinal fascicle: variations in patterns of anatomical connections

Based on high-resolution diffusion tensor magnetic resonance imaging (DTI) tractographic analyses in 39 healthy adult subjects, we derived patterns of connections and measures of volume and biophysical parameters, such as fractional anisotropy (FA) for the human middle longitudinal fascicle (MdLF). Compared to previous studies, we found that the cortical connections of the MdLF in humans appear to go beyond the superior temporal (STG) and angular (AG) gyri, extending to the temporal pole (TP), superior parietal lobule (SPL), supramarginal gyrus, precuneus and the occipital lobe (including the cuneus and lateral occipital areas). Importantly, the MdLF showed a striking lateralized pattern with predominant connections between the TP, STG and AG on the left and TP, STG and SPL on the right hemisphere. In light of the results of the present study, and of the known functional role of the cortical areas interconnected by the MdLF, we suggested that this fiber pathway might be related to language, high order auditory association, visuospatial and attention functions.

Usefulness of visual evaluation of the anterior thalamic radiation by diffusion tensor tractography for differentiating between Alzheimer's disease and elderly major depressive disorder patients

Background and objective

Many surveys of neural integrity of the cerebral white matter with psychiatric diseases on diffusion tensor imaging have recently been performed, but these mainly utilize fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) values, and the results were inconsistent and not fully applied clinically. In this study, we investigated the possibility of differentiating between Alzheimer’s disease (AD) and elderly major depressive disorder (MDD) patients in whom early-stage symptoms are difficult to diagnose, by visually evaluating cerebral nerve fascicles utilizing diffusion tensor tractography. We also measured and evaluated FA and ADC values at the same time.

Subjects and methods

The subjects included 13 AD patients (age: 69.5 ± 5.1 years), 19 MDD patients (65.8 ± 5.7 years), and 22 healthy control (HC) subjects (67.4 ± 4.8 years). Images were acquired using a 1.5T magnetic resonance imaging device and analyzed by diffusion tensor tractography analysis software.

Results

Depiction of the anterior thalamic radiation (ATR) tended to be poor in AD patients unlike in MDD patients and HC subjects. The FA values in the left superior longitudinal fasciculus and fornix (FX) in AD patients were significantly different from those in MDD patients and HC subjects. The ADC values in the bilateral ATR and left superior and inferior longitudinal fasciculi, left inferior fronto-occipital fasciculus, and FX in AD patients were significantly different from those in MDD patients and HC subjects.

Conclusion

Visual evaluation of the ATR in combination with the FA values of the left superior longitudinal fasciculus and FX and ADC values of the bilateral ATR, left superior and inferior longitudinal fasciculi, left inferior fronto-occipital fasciculus, and FX is useful for differentiating between AD and MDD patients, which further suggests that it may become a useful auxiliary diagnostic tool.

Changes in a cerebellar peduncle lesion in a patient with Dandy-Walker malformation: A diffusion tensor imaging study

We report a patient with severe ataxia due to Dandy-Walker malformation, who showed functional recovery over 10 months corresponding to a change in a cerebellar peduncle lesion. A 20-month-old female patient who was diagnosed with Dandy-Walker syndrome and six age- and sex-matched healthy control subjects were enrolled. The superior cerebellar peduncle, the middle cerebellar peduncle, and the inferior cerebellar peduncle were evaluated using fractional anisotropy and the apparent diffusion coefficient. The patients’ functional ambulation category was 0 at the initial visit, but improved to 2 at the follow-up evaluation, and Berg's balance scale score also improved from 0 to 7. Initial diffusion tensor tractography revealed that the inferior cerebellar peduncle was not detected, that the fractional anisotropy of the superior cerebellar peduncle and middle cerebellar peduncle decreased by two standard deviations below, and that the apparent diffusion coefficient increased by two standard deviations over normal control values. However, on follow-up diffusion tensor tractography, both inferior cerebellar peduncles could be detected, and the fractional anisotropy of superior cerebellar peduncle increased to within two standard deviations of normal controls. The functional improvement in this patient appeared to correspond to changes in these cerebellar peduncles. We believe that evaluating cerebellar peduncles using diffusion tensor imaging is useful in cases when a cerebellar peduncle lesion is suspected.

Curvature range measurements of the arcuate fasciculus using diffusion tensor tractography

Because Broca's area and Wernicke's area in the brain are connected by the arcuate fasciculus, understanding the anatomical location and morphometry of the arcuate fasciculus can help in the treatment of patients with aphasia. We measured the horizontal and vertical curvature ranges of the arcuate fasciculus in both hemispheres in 12 healthy subjects using diffusion tensor tractography. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus horizontal part were 121.13 ± 5.89 and 25.99 ± 3.01 degrees, respectively, and in the left hemisphere, the values were 121.83 ± 5.33 and 27.40 ± 2.96 degrees, respectively. In the right hemisphere, the direct curvature range and indirect curvature range values of the arcuate fasciculus vertical part were 43.97 ± 7.98 and 30.15 ± 3.82 degrees, respectively, and in the left hemisphere, the values were 39.39 ± 4.42 and 24.08 ± 4.34 degrees, respectively. We believe that the measured curvature ranges are important data for localization and quantitative assessment of specific neuronal pathways in patients presenting with arcuate fasciculus abnormalities.

Motor recovery via aberrant pyramidal tract in a patient with traumatic brain injury: A diffusion tensor tractography study

The aberrant pyramidal tract is the collateral pathway of the pyramidal tract through the medial lemniscus in the brainstem. A 21-year-old man presented with right hemiparesis due to a traumatic intracerebral hemorrhage in the left corona radiata. His motor function recovered almost to the normal state at 10 months after onset. Through diffusion tensor tractography, the pyramidal tract in the affected (left) hemisphere showed discontinuation at the pontine level at 13 months after onset. An aberrant pyramidal tract was observed, which originated from the primary motor cortex and the supplementary motor area and descended through the corona radiata, then through the posterior limb of the internal capsule and the medial lemniscus pathway from the midbrain to the pons, finally entered into the pyramidal tract area at the pontomedullary junction. It suggests that the motor functions of the right extremities in this patient had recovered by this aberrant pyramidal tract.