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Biomedical subjects

O B Boyko

Publications and source records attributed to O B Boyko.

83 records · Page 5Linked to original sources
PubMedDate not supplied

Gd-DTPA-enhanced MR imaging of leptomeningeal spread of primary intracranial CNS tumor in children.

Three children with known primary brain neoplasms and leptomeningeal disease were evaluated with MR imaging. Two of the patients had medulloblastoma and one had pineoblastoma. The presence of leptomeningeal tumor spread was established by positive CSF cytopathology in conjunction with compatible contrast-enhanced CT findings. Contrast-enhanced CT, nonenhanced MR, and Gd-DTPA-enhanced MR studies were then compared. In two cases, leptomeningeal lesions were seen better with Gd-DTPA-enhanced MR than with contrast-enhanced CT. In all three cases, Gd-DTPA MR imaging revealed lesions that were not identified on noncontrast MR. Gd-DTPA-enhanced MR imaging is useful when searching for intracranial leptomeningeal tumor deposits in pediatric patients at risk for this condition.

Brain Neoplasms↗
PubMedDate not supplied

MR imaging of hindbrain deformity in Chiari II patients with and without symptoms of brainstem compression.

We examined the MR appearance of the hindbrain deformity, including the upper cervical spinal canal and craniovertebral junction, in 33 patients with Chiari II malformation. In this disorder, there is impaction at birth of the medulla and cerebellar vermis into the upper cervical spine, resulting in obliteration of the subarachnoid space and scalloping of the dens. Spinal canal enlargement during the child's growth, combined with dorsal displacement of neural tissue, eventually causes marked widening of the precervical subarachnoid space. This enlargement may simulate an intradural mass. Our series documents the changes seen at birth and the progression of the widened precervical space through the first and second decades. Twelve (36%) of the 33 patients studied were symptomatic, with brainstem or longtract symptomatology, and 11 of these required surgery. This group was compared with the remaining 21 asymptomatic Chiari II patients to identify MR features associated with clinical deterioration. The level of descent of the hindbrain hernia was critical; eight of 12 symptomatic patients had a cervicomedullary kink at C4 or lower, while no asymptomatic patients had a fourth ventricle, medulla, or kink below C3-C4. The precervical cord subarachnoid space was slightly wider in asymptomatic patients, although there was great overlap. In five patients with follow-up scans, this space was seen to increase in width after laminectomy. A CSF flow void was present in the precervical space in about 25% of patients in both groups. In nine of 12 symptomatic patients, C1 arch indentation of the dura (causing significant compression) was confirmed surgically. However, seven (33%) of the 21 asymptomatic patients also had this appearance. Absolute measurement of the anteroposterior diameter of the canal at C1 ranged from 11 to 25 mm in both groups. Retrocollis, which persisted despite sedation for MR, was seen in two patients, both symptomatic. Recognition of the vermis, medullary kink, cervical cord, C1 arch, fourth ventricle, and precervical space in Chiari II patients is fundamental to the analysis of symptoms in

Adolescent↗
PubMedDate not supplied

Carotid body tumor: flow sensitive pulse sequences and MR angiography.

The magnetic resonance (MR) appearance of carotid body tumors has been previously described. Classically, these lesions are well circumscribed and highly vascular and cause a characteristic separation of the external and internal carotid arteries. Hypointense foci within these tumors are seen on T1-weighted images. The T2-weighted images snow a "salt and pepper" pattern. We report a carotid bifurcation glomus tumor that exhibited the above features on conventional MR. Multiplanar gadolinium enhanced MR as well as flow-sensitive MR techniques including small flip angle gradient refocused images and MR angiography were performed. Magnetic resonance angiography demonstrated the abnormal morphology of the carotid bifurcation. Axial gradient refocused images revealed evidence of flow within the lesion. The findings were then correlated with postcontrast CT, arterial digital subtraction angiography, and histopathology.

Carotid Body Tumor↗
PubMedDate not supplied

MR imaging of compact white matter pathways.

A prominent decreased signal intensity can be seen in many of the heavily myelinated, compact fiber pathways of the brain on T2-weighted spin-echo MR images (TR = 2500 msec, TE = 80 msec). These areas include the anterior commissure, internal capsule, optic tract and radiations, fornix, mammillothalamic tract, superior frontooccipital fasciculus, cingulum, corpus callosum, uncinate fasciculus, and superior longitudinal fasciculus. All these pathways could be identified in normal subjects 3 years old and older when 1.5-T axial and coronal images of 50 adults and 17 children were reviewed. Correlation of the in vivo and postmortem MR appearance of two human brains with Perls and Luxol fast blue stains indicates that the short T2 reflects heavy myelination and fiber density, not iron deposition. This is in contrast to the short T2 signal seen in the subcortical U fibers and deep nuclei of the brain that result from iron deposition. These pathways also differ from areas of brain iron accumulation in that (1) they may appear as areas of short T1 on partial-saturation or inversion-recovery pulse sequences and (2) they can be seen with regularity in all patients over 3 years of age. It is important to distinguish between the effect of the myelin sheath and the effect of brain iron on the T2 relaxation values seen in the normal brain since both result in shortened T2 relaxation. The importance of the role of these fiber tracts in disease processes and in modifying the spread of vasogenic edema and tumor needs further investigation.

Adolescent↗
PubMedDate not supplied

MR detection of brain iron.

PURPOSE: To provide further quantitative studies concerning the relationship with age between regional brain iron and T2 shortening. METHODS: a) Quantitative T2 calculations of eight anatomic regions (red nucleus, substantia nigra, dentate nucleus, corpus callosum, caudate, putamen, temporal lobe white matter, and frontal lobe white matter) from T2-weighted spin-echo images were performed in 60 patients aged newborn to 35 years. b) Quantitative brain iron concentrations were obtained in six of the eight anatomic regions (red nucleus, substantia nigra, dentate nucleus, corpus callosum, cauda, and putamen) using 13 autopsied brains (newborn to 78 years). Brain tissue from these six regions was digested with 0.6 N HCl-2.5% wt/vol KMnO4 for 2 hours at 60 degrees C. After centrifugation, 0.1 mL of an iron-chelating reagent (2 mol/L ascorbic acid, 5 mol/L ammonium acetate, 6.5 nmol/L ferrozine, 13.1 mmol/L neocuprine) was added and the absorbance was measured at 562 nm/L and compared with a standard curve with ferric chloride. c) The in vivo iron concentrations in tissue that were obtained were reproduced in four test tube phantom studies with ferric ammonium sulfate or ferrous ammonium sulfate dissolved in either deionized water or 5% agarose. T2 calculations of the phantoms were made with a single-section multiple repetition time, multiple echo time acquisition. RESULTS: a) Clinical T2 calculations--all eight anatomic regions showed a decrease with age in T2 value, beginning shortly after birth. During the first three decades, the T2 shortening was most significant in the region of substantia nigra. b) Quantitative brain iron--five anatomic regions but not the corpus callosum demonstrated an age-related increase in brain iron (1449.6 nmol/g for the red nucleus versus 261.8 nmol/g for the corpus callosum). c) T2 effect of iron in vitro--both the ferric and ferrous iron phantoms showed a decreased T2 value in the in vivo concentration range of iron obtained from the postmortem studies. The T2 shortening was most marked for the ferric phantoms. CONCLUSION: There is an age-related accumulation of iron in five regions of the brain, correlating with an associated decrease in T2 value that can be demonstrated in iron phantoms. Brain iron appears to contribute to the progressive decrease of T2 signal that occurs with aging.

Adolescent↗
PubMedDate not supplied

Interuncal distance measurements in healthy volunteers and in patients with Alzheimer disease.

PURPOSE: To evaluate further the clinical utility of the interuncal distance (IUD) measured from axial MR scans as a reflection of hippocampal atrophy. METHODS: The IUD measured from the axial MR scans of 17 healthy control subjects was correlated with the volume of the amygdala hippocampal complex obtained from coronal MR images. The IUD was also measured on axial MR scans in 12 patients with possible or probable Alzheimer disease. RESULTS: The correlation between the total amygdala hippocampal volume and the IUD was insignificant for control subjects (r = -0.38, P = .13). When analysis of covariance was performed with the IUD as the dependent variable and age and diagnosis as the independent variables, overall R2 was 0.25. Age (F = 5.02, df = 1, P = .034), but not diagnosis (F = 0.02, df = 2, P = .88), had a significant effect. CONCLUSIONS: The IUD has no significant correlation with the amygdala hippocampal volume. The IUD appears to be a better measure of overall brain volume, which changes with age. In our patient population diagnosed with mild to moderate Alzheimer disease, the IUD measurement was not found to be useful in distinguishing their scans from those of the volunteers.

Adult↗
PubMedDate not supplied

Interuncal distance as a measure of hippocampal atrophy: normative data on axial MR imaging.

PURPOSE: To assess the effects of age and gender on the interuncal distance measured from MR images. METHODS: High-field strength MR images (axial) of 75 volunteers, 21-82 years old and free of neurologic disorders, were used to measure the interuncal distance. RESULTS: The interuncal distance increased with age (r = 0.66, P < .0001). The mean (SD) interuncal distance for all subjects was 21.4 (4) mm with a range of 12 to 29 mm. CONCLUSIONS: The interuncal distance in healthy subjects is unlikely to exceed 30 mm. Our data may be of clinical significance in view of a previous report stating that the interuncal distance may be enlarged in pathologic hippocampal degeneration, such as in patients with Alzheimer disease.

Adult↗
PubMedDate not supplied

[18F]2-fluoro-2-deoxyglucose-positron emission tomography correlation of gadolinium-enhanced MR imaging of central nervous system neoplasia.

PURPOSE: To correlate the findings of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced MR imaging with positron emission tomography (PET) in the evaluation of central nervous system neoplasia. MATERIALS AND METHODS: Thirty-six lesions identified on noncontrast MR in 35 patients with biopsy-proved intracranial tumors were imaged with both T1-weighted Gd-DTPA MR at 1.5 T and [18F]2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET). Eighteen women and 17 men with a mean age of 47.1 years (range 22-72) were studied. The degrees of Gd-DTPA enhancement and FDG uptake were rated separately, and then all scans were reviewed together. FDG uptake was graded 1-5. RESULTS: Of the 35 lesions rated, 30 had Gd-DTPA enhancement and 28 of these were hypermetabolic (FDG accumulation greater than white matter) on PET (93% concordance). Twenty-six of 32 neoplastic lesions had Gd-DTPA enhancement. Twenty-four of these enhancing tumors were hypermetabolic. Only one lesion was completely missed on PET but identified on routine spin echo MR. CONCLUSION: Gd-DTPA MR and FDG-PET are complementary and there is a high concordance of Gd-DTPA-enhancing tumours displaying FDG hypermetabolism. Although FDG hypermetabolism and Gd-DTPA enhancement are usually suggestive of high-grade malignancy, anaplastic astrocytomas may not enhance with Gd-DTPA and can be hypometabolic. In addition, benign intracranial tumors (two cases of meningioma) and radiation necrosis can be associated with both FDG uptake and Gd-DTPA enhancement.

Adult↗