Biomedical subjects

Charles A J Romanowski

Publications and source records attributed to Charles A J Romanowski.

5 recordsLinked to original sources

PubMed2006

Dexamethasone and enhancing solitary cerebral mass lesions: alterations in perfusion and blood-tumor barrier kinetics shown by magnetic resonance imaging.

OBJECTIVE: Glucocorticoid analogues are often administered to patients with intracranial space-occupying lesions. Clinical response can be dramatic, but the neurophysiological response is not well documented. This study sought to investigate the blood-lesion barrier, blood-brain barrier, and cerebral perfusion characteristics of patients who have undergone such therapy using magnetic resonance imaging. METHODS: Seventeen patients with intracranial mass-enhancing lesions underwent magnetic resonance imaging before and after 3 days of high-dose dexamethasone therapy. Assessments of blood-lesion barrier and blood-brain barrier integrity were based on a dynamic T1-weighted exogenous contrast technique that yielded the normalized maximal change in contrast uptake (T1-uptake). Perfusion was assessed using a dynamic T2*-weighted exogenous contrast technique to yield relative regional cerebral blood volume and first-moment mean transit time. Comparisons were made in T1-uptake, regional cerebral blood volume, and first-moment mean transit time of both enhancing lesion and contralateral normal-appearing white matter (CNAWM) obtained before and after dexamethasone. RESULTS: Significant reduction in T1-uptake was observed (19% decrease, P < 0.005) within enhancing pathological tissue, whereas no significant alteration was detected in CNAWM. Regional cerebral blood volume was significantly reduced in both enhancing tissue (28% decrease, P < 0.005) and in CNAWM (20% decrease, P < 0.001). Bolus first-moment mean transit time significantly increased (2.0 s prolongation, P < 0.05) in CNAWM, whereas there was no significant change (1.4 s prolongation, P > 0.05) within enhancing tissue. CONCLUSION: Glucocorticoid-analogue therapy not only affects the permeability of the blood-lesion barrier and lesion blood volume but also affects blood flow within normal-appearing contralateral parenchyma. There is a need for controls in steroid therapy in magnetic resonance imaging studies, which involve assessments of cerebrovascular function.

Adult↗

PubMed2005

Agrammatic but numerate.

A central question in cognitive neuroscience concerns the extent to which language enables other higher cognitive functions. In the case of mathematics, the resources of the language faculty, both lexical and syntactic, have been claimed to be important for exact calculation, and some functional brain imaging studies have shown that calculation is associated with activation of a network of left-hemisphere language regions, such as the angular gyrus and the banks of the intraparietal sulcus. We investigate the integrity of mathematical calculations in three men with large left-hemisphere perisylvian lesions. Despite severe grammatical impairment and some difficulty in processing phonological and orthographic number words, all basic computational procedures were intact across patients. All three patients solved mathematical problems involving recursiveness and structure-dependent operations (for example, in generating solutions to bracket equations). To our knowledge, these results demonstrate for the first time the remarkable independence of mathematical calculations from language grammar in the mature cognitive system.

Aphasia↗

PubMed2003

Contrast-enhanced fluid-attenuated inversion recovery imaging for leptomeningeal disease in children.

BACKGROUND AND PURPOSE: To develop an MR imaging method that improves detection of leptomeningeal disease when compared with the current reference standard, contrast-enhanced T1-weighted imaging. METHODS: We investigated the cases of 10 children who were at high risk of intracranial leptomeningeal disease (Sturge-Weber syndrome and medulloblastoma). The cases of Sturge-Weber syndrome were investigated by using one MR imaging examination, and the cases of medulloblastoma were investigated by using four MR imaging examinations performed over 18 months. In all cases, contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images were acquired in addition to the routine sequences. The parameters of the FLAIR sequence were chosen to maximize the T1 component of the signal intensity, to maximize detection of leptomeningeal enhancement. We made subjective and objective assessments of the presence and extent of leptomeningeal disease as shown on contrast-enhanced T1-weighted images and contrast-enhanced FLAIR images. RESULTS: In three of the four cases of Sturge-Weber syndrome, the T1 and FLAIR sequences showed comparable extent of leptomeningeal enhancement. For one child, FLAIR images showed unexpected bilateral disease and more extensive leptomeningeal enhancement on the clinically suspected side. In four of six cases of medulloblastoma, no leptomeningeal enhancement was shown on any examinations during the 18-month period. In two cases, FLAIR images showed more extensive leptomeningeal enhancement when compared with T1-weighted images. CONCLUSION: Contrast-enhanced FLAIR imaging seems to improve detection of leptomeningeal disease when compared with routine contrast-enhanced T1-weighted imaging. This seems to be partly because of suppression of signal intensity from normal vascular structures on the surface of the brain by FLAIR, which allows easier visualization of abnormal leptomeninges. We think that these findings can be extrapolated to the investigation of leptomeningeal disease of all causes and at all ages.

Cerebellar Neoplasms↗

PubMed2002

Dural arteriovenous fistulae: noninvasive diagnosis with dynamic MR digital subtraction angiography.

MR digital subtraction angiography (DSA) is a new diagnostic tool capable of producing dynamic images of the cerebral circulation with the injection of gadopentetate dimeglumine into a peripheral vein. Previous reports have concentrated on its potential as a noninvasive technique for the study of pial arteriovenous malformations. In this report, we present our early findings with MR DSA in the evaluation of intracranial dural arteriovenous fistulae.

Aged↗

PubMedDate not supplied

Wernicke encephalopathy: unusual findings in nonalcoholic patients.

We report the unique findings on magnetic resonance imaging (MRI) in two cases of diet-related Wernicke encephalopathy (WE). There was no relation to alcohol in either case. The first patient presented with seizures and showed changes of WE on diffusion-weighted MRI with involvement of the motor strip. The second case illustrates extensive changes in the thalamus caused by WE, resulting in obstructive hydrocephalus requiring shunting.

Adult↗