Quantitative diffusion tensor imaging of corticospinal tract: Initial experience.

Objective: Diffusion Tensor Imaging (DTI) and fiber tractography are a relatively new magnetic resonance imaging technique that can provide white matter architectures. In this pilot study, we use these techniques to quantify and evaluate the integrity of white matter tract in a group of subjects with and without lesions involving the corticospinal tract. Methods: Ten subjects (7 patients and 3 controls) who underwent conventional MRI and DTI were retrospectively recruited. DTI data was analyzed with a multiple ROI approach on a workstation to isolate corticospinal tract and obtain fractional anisotropy (FA) and directional average mean diffusivity (Dav). Comparison of these values between affected and unaffected corticospinal tract was done using a Mann-Whitney U test. Results: FA values of the affected side were significantly lower than the unaffected side (comparing affected side of patient versus control and affected side of patient versus unaffected side of patient). Whereas, Dav value was significantly higher only when compared with the affected side of the patient to the control group. Comparison of the unaffected side of the patient versus control and the left side of control versus right side of control showed no statistical differences. Four out of five patients with residual neurological deficit had a higher mean difference of FA. Conclusion: Pathological change of corticospinal tract from various diseases can be quantitatively measured by DTI and fiber tractography. This technique might be useful for early disease detection, to predict disease prognosis or quantitative follow-up of disease progression.

Striatal hyperdensity in hemichorea patient: Case reports and review literatures.

Objective: To report three cases of a unique clinicoradiological manifestration of chorea associated with non-ketotic hyperglycemia. Methods: A retrospective review of clinical, radiological and laboratory findings in three patients with chorea associated with non-ketotic hyperglycemia and a review of relevant literature were done. Results: Three patients presented with acute hemichorea, two patients with a history of long standing diabetes mellitus and one without. The initial cranial CT scans revealed hyperattenuation at the basal ganglia contra-lateral to the side of chorea in two cases and bilateral involvement in one case. The laboratory findings showed a non-ketotic hyperglycemic state in all patients and, hence, hyperglycemia-induced chorea was diagnosed. Chorea in all patients responded well to treatment for hyperglycemia. Conclusion: Acute chorea associated with diabetic non-ketotic hyperglycemia may present with acute neurologic symptoms mimicking stroke. Recognition of this unique clinicoradiological appearance is important because correction of the underlying hyperglycemia will lead to rapid improvement of chorea.

Benign versus malignant compression fracture: a diagnostic accuracy of magnetic resonance imaging.

OBJECTIVE: To evaluate the accuracy, sensitivity, and specificity of various Magnetic Resonance Imaging (MRI) features in differentiating malignant from benign compression fracture of the spine. MATERIAL AND METHOD: Retrospective review of MRI spine of patients with vertebral compression fracture identified from the hospital database between June 2004 and February 2006 by two radiologists blinded to the clinical data. Various MRI features were evaluated for sensitivity, specificity, positive predictive value, and negative predictive value. An additional combination of two, three, four, and five MRI features that had statistically significant (P value less than 0.005) were also calculated for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS: Fifty-eight spinal MRI were included from 35 patients with metastatic vertebral compression fractures and 23 patients with benign vertebral compression fractures. MR imaging features suggestive of malignant vertebral compression fracture were convex posterior border of the vertebral body, involvement of the pedicle or posterior element, epidural mass, paraspinal mass, and destruction of bony cortex. Among these, involvement of pedicle or posterior element was the most reliable finding (sensitivity 91.4% and specificity 82.6%) for diagnosis of malignant vertebral compression fracture. A combination of two or more MRI features gave very high specificity and PPV. CONCLUSION: Certain MR imaging characteristics can reliably distinguish malignant from benign compression fracture of the spine. Combination of several MRI features strongly affirmed the diagnosis of malignant compression fracture, especially in a patient where tissue biopsy is not justified.

Computed tomographic findings in non-traumatic hemorrhagic stroke.

OBJECTIVE: To analyze CT findings in hemorrhagic stroke patients correlation with clinical outcome and assess the interobserver agreement of hemorrhagic stroke identification on CT imaging. MATERIAL AND METHOD: CT imaging features of 131 cases and clinical data were verified and collected at Siriraj Hospital from Jan 2004 to Dec 2005 and retrospectively analyzed for type, location, mass effect, size of hemorrhage, intraventricular extension, initial level of consciousness (GCS), hospital length of stay and patient outcome. The percentages, predictive values, kappa were calculated. RESULTS: From all types of hemorrhagic stroke, intracerebral hemorrhage remains a common and devastating clinical problem. The most common site was the thalamus and basal ganglia. In the present study, the authors found that fifty-three cases (53/131 cases, 40.5%) with thalamic-ganglionic hemorrhage, nineteen cases (19/131 cases, 14.5%) in lobar hemorrhage, five cases (5/131 cases, 3.8%) in cerebellum, five cases (5/131 7 cases, 3.8%) in brainstem and eight cases (8/131 cases, 6.1%) occurred in multiple locations. There were twenty-five cases (25/131 cases, 19.1%) of subarachnoid hemorrhage, thirteen cases (13/131 cases, 9.9%) of subdural hemorrhage and three cases (3/131 cases, 2.3%) of intraventricular hemorrhage. Two variables on CT imaging, identified as significant as early mortality predictors, were hematoma volume more than 60 cm3, and presence of intraventricular hemorrhage extension (p < 0.05). The mass effect defined as midline and/or enlargement of contralateral ventricle was not significant (p = 0.067). The present study found concordance between CT brain interpretation by two neuroradiologists for the type of hemorrhagic stroke was very good, Kappa = 0.861 as well as for location was 0.866. CONCLUSION: CT imaging is an imaging instrument for early identification of hemorrhagic stroke patients and providing imaging evidence of high mortality risk.

Diagnostic accuracy of MR imaging in tuberculous spondylitis.

OBJECTIVE: To systemically evaluate MR imaging features of tuberculous spondylitis and to find features that may help differentiating tuberculosis from other spinal diseases. MATERIAL AND METHOD: Retrospective review of 65 MR imaging of two groups of patients between January 2002 and December 2005. Thirty-one patients were diagnosed as tuberculosis spondylitis and the rest were a randomly selected group of 34 patients with other spinal diseases. All images were reviewed by two neuroradiologists blinded to clinical data. Sensitivity and specificity of each MR imaging features were calculated. RESULTS: Three most useful MR imaging features with high sensitivity and specificity (> 80%) were endplate disruption (100%, 81.4%), paravertebral soft tissue (96.8%, 85.3%), and high signal intensity of intervertebral disc on T2W (80.6%, 82.4%). High sensitivity but low specificity signs in MRI included bone marrow edema (90.3%, 76.5%), bone marrow enhancement (100%, 42.5%), posterior element involvement (93.5%, 76.5%), canal stenosis (87.1%, 26.5%), and spinal cord or nerve root compression (80.6%, 38.2%). Low sensitivity but high specificity features in MRI were intervertebral disc enhancement (63.3%, 84.2%), vertebral collapse (58.1%, 85.3%), and kyphosis deformity (67.7%, 82.4%). Overall, the sensitivity and specificity of MRI for spinal tuberculosis were 100% and 88.2% respectively. CONCLUSION: The authors presented three good to excellent sensitivity and specificity MR imaging features for spinal tuberculosis, end plate disruption, paravertebral soft tissue formation, and high signal of intervertebral disc on T2W. In contrast to a previous study, most of the presented cases still presented with classic radiological pictures of "two vertebral disease with the destruction of the intervertebral disc". Only a small portion of the patients revealed sparing intervening disc or isolated single vertebral body involvement, which possibly reflected the early stages of the disease process.