PubMed Health⌕ Search

Biomedical subjects

Hemant Parmar

Publications and source records attributed to Hemant Parmar.

14 recordsLinked to original sources
PubMed2006

Acute symptomatic seizures and hippocampus damage: DWI and MRS findings.

The authors describe diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) changes in the hippocampus within 48 hours of acute symptomatic seizures or status epilepticus in 12 patients. DWI showed increased signal and a decreased apparent diffusion coefficient (ADC) in all patients, with corresponding lactate detected on MRS in six patients and EEG seizure activity in nine patients. On follow-up, the atrophic hippocampus had an increased ADC in six patients. DWI and MRS may predict development of hippocampal sclerosis.

Adolescent↗
PubMed2006

Contrast-enhanced flair imaging in the evaluation of infectious leptomeningeal diseases.

PURPOSE: The purpose of our study was to compare contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images with contrast-enhanced T1 weighted images for infectious leptomeningitis. MATERIALS AND METHODS: We studied twenty-four patients with a clinical suspicion of infectious meningitis with unenhanced FLAIR, contrast-enhanced T1 weighted and contrast-enhanced FLAIR MR sequences. Twelve patients had cytologic and biochemical diagnosis of meningitis on cerebrospinal fluid (CSF) examination obtained 48 h before or after the MR study. Sequences were considered positive if abnormal signal was seen in the subarachnoid space (cistern or sulci) or along pial surface. RESULTS: Twenty-seven examinations in 24 patients were performed. Of the 12 patients (thirteen studies) in whom cytology was positive, unenhanced FLAIR images were positive in six cases (sensitivity 46%), contrast-enhanced FLAIR images were positive in 11 (sensitivity 85%), and contrast-enhanced T1 weighted MR images were positive in 11 patients (sensitivity 85%). Of the 12 patients (14 studies) in whom cerebrospinal fluid study was negative, unenhanced FLAIR images were negative in 13, contrast-enhanced FLAIR images were negative in 11, and contrast-enhanced T1 weighted MR images were negative in eight. Thus, the specificity of unenhanced FLAIR, contrast-enhanced FLAIR and contrast-enhanced T1 weighted images was 93, 79 and 57%, respectively. CONCLUSION: Our results suggest that post-contrast FLAIR images have similar sensitivity but a higher specificity compared to contrast-enhanced T1 weighted images for detection of leptomeningeal enhancement. It can be a useful adjunct to post-contrast T1 weighted images in evaluation of infectious leptomeningitis.

Adolescent↗
PubMed2006

Cervical schwannoma presenting as an expansile vertebral body lesion: report of two cases with a technical note on the surgical management.

BACKGROUND: Schwannoma causing invasion and osteolytic expansion of the vertebral body has been uncommonly noted in lumbar and thoracic regions, but has not been yet reported in the cervical spine. Our purpose is to discuss the surgically relevant anatomical features of cervical schwannomas associated with vertebral invasion, to review their imaging findings and briefly discuss the surgical strategies in managing these challenging lesions. CASE DESCRIPTION: Clinical and radiological follow-up in two patients is presented. Both tumors were successfully resected using an anterior approach with lateral extension. Pathology was diagnostic for a benign schwannoma, and at 1-year follow-up, both patients were asymptomatic with no recurrence. CONCLUSION: In conclusion, schwannoma should be included in the differential diagnosis of large, extradural mass causing expansion and destruction of the spine, especially with characteristic imaging findings such as neural foraminal widening and vertebral body scalloping. Aggressive surgical management with skeletonization of the vertebral artery may provide good technical and clinical outcome.

Adult↗
PubMed2005

Imaging findings in primary intracranial atypical teratoid/rhabdoid tumors.

BACKGROUND: Intracranial atypical teratoid/rhabdoid tumors (AT/RT) are rare and extremely aggressive neoplasms seen primarily in childhood. Imaging features are often considered non-specific. However, correct diagnosis of AT/RT is important because these tumors have a markedly different clinical prognosis and require more aggressive therapy. OBJECTIVE: To determine the imaging features of AT/RT. MATERIALS AND METHODS: We retrospectively analyzed imaging findings in 11 patients with primary intracranial AT/RT presenting over a period of 5 years. CT (n=11), MR (n=7), clinical (n=11) and pathological (n=11) features were evaluated. FISH analysis showing monosomy of chromosome 22 (absence of bcr 22q11 locus) was available for three patients. Immunohistochemical staining for INI-1 (BAF47) was performed on all tumors. RESULTS: There were 11 patients, 6 boys and 5 girls. The age of presentation varied from 1 month to 15 years (average age 3 years 8 months). Six tumors were located in the posterior fossa and five in the supratentorial compartment. The tumors showed a hyperdense solid component (64%) that showed moderate to marked enhancement with contrast medium. On MR imaging, the predominant signal pattern was isointensity on T1-weighted images (57%) and T2 shortening with heterogeneity on T2-weighted images (86%). All tumors were large in size (average 4.2 x 3.7 cm), and there was a tendency for calcification (36%), hemorrhage (46%), necrosis (46%) and perifocal edema (100%). There was also a high tendency for subarachnoid dissemination, with five patients (46%) demonstrating brain and/or spinal metastasis. At follow-up (n=7), six patients showed local recurrence. At the time of recurrence, all these patients showed extensive leptomeningeal spread of the disease in both intracranial and intraspinal compartments. CONCLUSION: There are no specific imaging features for intracranial AT/RT. But a high tendency toward large size, a hyperdense solid component on CT scan with calcification, hemorrhage, necrosis and subarachnoid spread suggest that this tumor should be considered in the differential diagnosis of large pediatric intracranial tumors.

Adolescent↗
PubMed2005

Petrified ears in a patient with Keutel syndrome: temporal bone CT findings.

We present unusual imaging findings of petrified ears in a 9-year-old girl with Keutel syndrome. The patient presented for a temporal bone study for hearing loss. CT scan showed middle and inner ear abnormalities along with extensive and unsuspected calcification of the external ears and ossicular ligaments. On further investigation, the patient was found to have diffuse cartilage calcification in the larynx and tracheobronchial tree, brachytelephalangism and peripheral pulmonary stenosis suggestive of Keutel syndrome. Confirmation was obtained by mutation analysis.

Abnormalities, Multiple↗
PubMed2005

Multi-voxel MR spectroscopic imaging of the brain: utility in clinical setting-initial results.

BACKGROUND AND PURPOSE: Compared to single voxel methods, MR spectroscopic imaging (MRSI) of the brain provides metabolic information with improved anatomical coverage and spectral resolution, but may be difficult to perform in the clinical setting. We evaluate the factors influencing spectral quality in MRSI using a semi-automated method, focussing on lipid contamination, and phase correction errors related to magnetic field inhomogeneity. METHODS: We retrospectively analysed MRSI studies planned by radiologists and radiographers. Two-dimensional MRSI studies using point-resolved spectroscopy (PRESS) localisation, at long echo time (135 or 144 ms) were acquired on a 1.5 T scanner. Studies that contained lipid contamination and abnormally inverted spectra were reviewed and the latter correlated with anatomic location at the base of skull, and with the area of the region of interest (ROI) studied. RESULTS: Of 128 consecutive MRSI studies, six showed abnormal inverted spectra, of which four were acquired at the base of skull. Multivariate logistic regression analysis showed that study location at the base of skull, but not larger ROI, was a significant predictor for the risk of being affected by inverted spectra (RR for base of skull: 11.76, 95% CI: 1.86-74.18, P=0.009. RR for area of ROI: 3.68, 95% CI: 0.57-23.67, P=0.170). Seven studies showed lipid contamination; all were in close proximity to the overlying scalp. CONCLUSION: Using a semi-automated acquisition and post-processing method, MRSI can be successfully applied in the clinical setting. However, care should be taken to avoid regions of high magnetic field inhomogeneity at the base of skull, and lipid contamination in voxels prescribed near the scalp.

Brain Chemistry↗
PubMed2004

Tuberculous arthritis of the appendicular skeleton: MR imaging appearances.

Tuberculosis [TB] of the appendicular skeleton is an uncommon infection caused by the tuberculous bacilli and constitutes only 1-3% of all tuberculosis infections. MR imaging features of tuberculous arthritis include bone marrow oedema, cortical erosions, synovitis, joint effusion, tenosynovitis, soft tissue collections, and myositis. These imaging features are at times non-specific, but in the correct clinical context help in diagnosis of tuberculosis. We present the various pathological manifestations of TB arthritis involving the different joints of appendicular skeleton and discuss their MR imaging appearances.

Adolescent↗
PubMed2004

Spinal schwannoma with acute subarachnoid hemorrhage: a diagnostic challenge.

We report a case of spinal intradural schwannoma presenting with intracranial subarachnoid hemorrhage. Cerebral angiography studies were negative, but MR imaging of the spine revealed a large hemorrhagic tumor in the thoraco-lumbar junction. The tumor was misdiagnosed as ependymoma of the conus medullaris. This case illustrates the importance of a high index of suspicion for spinal disease in angiographically-negative subarachnoid hemorrhage and pitfalls in MR diagnosis of thoraco-lumbar tumors.

Acute Disease↗
PubMed2003

Hemimegalencephaly with tuberous sclerosis: a longitudinal imaging study.

Hemimegalencephaly is a rare cerebral malformation characterized by asymmetry of the hemispheres and cortical dysplasias. We report clinical and imaging findings in a child with hemimegalencephaly involving the right cerebral hemisphere with associated manifestations of tuberous sclerosis complex. Gross abnormal myelination pattern and gyral abnormalities were seen in the enlarged hemisphere. Subsequent scans showed atrophy of the frontoparietal region in the enlarged hemisphere and normal growth of the opposite hemisphere exceeding the size of the abnormal hemisphere in the frontoparietal region. A few white-matter lesions that were seen in the normal hemisphere on neonatal scan were difficult to appreciate on subsequent MR studies. The white-matter lesions were better seen in the neonatal period, whereas cortical tubers were better detected at a later age.

Cerebral Cortex↗
PubMed2002

Acute tuberculous abscess of the thyroid gland.

Isolated tuberculous thyroid abscess is an extremely rare form of infection of the thyroid gland. We present a case of a female patient who presented with an acute abscess of thyroid gland associated with pain and fever and without cervical lymphadenopathy. We describe the pathology of the disease and the imaging findings with their differential diagnosis.

Abscess↗
PubMedDate not supplied

Diastematomyelia with terminal lipomyelocystocele arising from one hemicord: case report.

Diastematomyelia is an uncommon spinal dysraphism with midline dorsoventral clefting of the spinal cord. Formation of syrinx cavity within the hemicord, vertebral anomalies and lipomas is known to be associated with diastematomyelia. We present an unusual case of a 4-month-old girl, who presented with diastematomyelia and terminal myelocystocele, and dilatation of the terminal portion of the spinal canal with formation of a cystic structure. Findings were confirmed by subsequent surgery and histopathology. Ectopic right kidney, Chiari I malformation and changes of partial sacral agenesis were other findings noted in this case. No case report of formation of terminal myelocystocele arising from one hemicord was described in the literature we reviewed.

Abnormalities, Multiple↗
PubMedDate not supplied

Maple syrup urine disease: diffusion-weighted and diffusion-tensor magnetic resonance imaging findings.

We present conventional magnetic resonance (MR) imaging with diffusion-weighted and diffusion-tensor imaging findings in a 10-day-old neonate with maple syrup urine disease (MSUD). On conventional MR imaging, signal abnormalities were noted in the affected white matter of cerebellum, dorsal brainstem, thalami, posterior limbs of internal capsules, and the corona radiata. These regions showed marked hyperintensity on diffusion-weighted images with decreased apparent diffusion coefficient values (average 68% reduction). Diffusion-tensor imaging showed decreased anisotropy (average 57% reduction) in the corresponding areas. Both diffusion-weighted and diffusion-tensor imaging are valuable in the diagnosis and understanding of the pathogenesis of MSUD, with findings that suggest cytotoxic edema and damaged oligodendro-axonal units within the affected white matter.

Brain↗
PubMedDate not supplied

Combined magnetic resonance tractography and functional magnetic resonance imaging in evaluation of brain tumors involving the motor system.

The goal of neuro-oncologic surgery is to maximize tumor resection while preserving vital brain functions. Identification of the relation between the tumor and adjacent functional cortical areas as well as efferent subcortical white matter tracts is important for preservation of function. Combined diffusion tensor imaging with magnetic resonance (MR) tractography and functional blood oxygen level-dependent MR imaging were applied successfully for preoperative planning and guidance in 2 patients with tumors near the motor cortex. The combination of these novel functional imaging techniques can provide new information for presurgical planning.

Adult↗