The Usefulness of Diffusion Tensor MRI for the Prediction of Clinical Outcome in Patients with Acute Subcortical Infarction

BACKGROUND: Diffusion tensor MRI (DTI) is a new imaging technique and enables us to analyze the structural damage of fiber pathways and to monitor the time course of Wallerian degeneration of the pyramidal tract in stroke patients. We used DTI to investigate structural changes of the infarct area and the associated descending corticospinal tract in patients with subcortical infarct. METHODS: We examined 24 consecutive patients who presented with acute single cerebral infarct in the subcortical area and who also had undergone an MRI study within 7 days after symptom onset. Clinical outcome was assessed using the National Institutes of Health Stroke Scale (NIHSS) at admission, 7 days, 14 days and 30 days and modified Rankin Scale (mRS) at admission and 30 days. Each of the indices was achieved by post processing the acquired DTI data and correlated with the NIHSS. RESULTS: In infarct region, fractional anisotropy (FA) was significantly decreased compared with matched-contralateral regions (0.39 vs. 0.53, p<0.001). In the distal to the infarct, FA was significantly decreased at internal capsule (0.62 vs. 0.64, p=0.019), not at pons (0.51 vs. 0.53, p=0.103). The decrease of anisotropy at infarct region correlated positively with the NIHSS at 7, 14 and 30 days and mRS at 30 days after stroke, but the decrease of anisotropy at internal capsule did not correlate with the NIHSS. CONCLUSIONS: This study shows the potential of DTI to detect and monitor the structural degeneration of fiber pathways and to establish the prognosis in patients with acute subcortical cerebral infarct.

Terson's Syndrome : A case report

Terson's syndrome is one of the cerebro-ocular syndrome which entails the findings due to intraocular hemorrhage in association with increased intracranial pressure following subarachnoid hemorrhage. We reported a patient suffering from total blindness after basal ganglia hemorrhage, who was diagnosed as Terson's syndrome and vitrectomy was done. Our patient recovered normal visual acuity after vitrectomy, which fascilitated rehabilitative process. We also performed diffusion tensor tractography to investigate abnormalities of brain related to the visual dysfunction, which revealed decreased orientation and integrity of the right optic radiation. It is important to diagnose Terson's syndrome early because it is one of the cerebro-ocular syndrome which needs early intervention with consideration of the integrity of optic pathway.

The Diagnosis of Motor Tract Disruption in Thalamic and Putaminal Hemorrhage using Diffusion Tensor MRI and Its Relation with Motor Recovery

OBJECTIVE: The purpose of this study is to prove and quantify motor tract disruption and to correlate with motor weakness and its recovery in thalamic and putaminal hemorrhage using diffusion tensor magnetic resonance(MR) image. METHODS: We studied 24 patients with thalamic and putaminal hemorrhage with motor weakness who did not underwent surgery(hematoma volume 75.0%)and compared means of motor power at each time. RESULTS: The means of FA ratio were 42.5% in group A, 63.0% in group B and 88.2% in group C. The means of motor power were 1.1, 2.3 and 3.7 at initial. After 6 months the means of motor power were 3.0, 4.0 and 4.5. The group of lower FA ratio had more severe motor weakness and showed worse motor recovery clinically than the group of higher FA ratio(P < 0.01). Though patients had severe motor weakness initially, the patients with high FA ratio showed good recovery. CONCLUSION: In thalamic and putaminal hemorrhage, diffusion tensor MR image can prove the degree of motor tract damage and predict the degree of motor recovery.

Diffusion Tensor MRI on Evaluation of Microstructural Abnormality Compatible with the Motor Weakness in Children with Brain Injury

We present four pediatric cases examined by diffusion tensor MRI (DTI) to investigate microstructural abnormalities of brain related to their neurologic disability and motor weakness, following absence of any remarkable lesion on the motor pathway in conventional MRI. DTI is a relatively novel MR technique that enables investigation of the orientation and integrity of white matter fiber tracts of the brain in vivo. Case 1, 2 and 3 had suffered from cerebral palsy and case 4 had developed left hemiparesis after a traumatic brain injury. Conventional brain MRI presented no specific abnormality in case 1 and 2, a focal encephalomalacia in the left anterior thalamus in case 3, and contusional hemorrhages in the left temporal and parietal lobes in case 4. But DTI disclosed microstructural abnormalities on descending motor pathway including the posterior limb of the internal capsule or the cerebral peduncle of the midbrain in all cases.

Evidence of Microstructural Abnormality on Descending Motor Pathway in Cerebral Plasied Children with Periventricular Leukomalacia: Diffusion Tensor MRI Study

OBJECTIVE: Using diffusion tensor MRI (DTI), to investigate the microstructural abnormality of corticospinal tract in the cerebral palsied children with periventricular leukomalacia on conventional MRI and to recognize the clinical usefulness of DTI. METHOD: Seven patients were studied. DTI was peformed using 1.5T MR scanner (Vision Plus, Siemens, Erlangen, Germany) and fractional anisotropies of corona radiata, posterior limbs of internal capsules, and cerebral peduncles of midbrain in both hemisphere were calculated. RESULTS: The fractional anisotropy was significantly decreased in all corona radiata, posterior limbs of internal capsules, cerebral peduncles of midbrain in six patients except one hemiplegic patient, compared with that of control group. In in the hemiplegic patient, the fractional anisotropy was reduced only in affected hemisphere. In addition, the fractional anisotropy tended to be also increased as gross motor function measure (GMFM) score was increased. CONCLUSION: We believe that DTI may be efficient in evaluating microstructural abnormality on the motor pathway of brain and helpful in providing prognosis of clinical findings in cerebral palsied children with periventricular leukomalacia.