Biomedical subjects

R K Fulbright

Publications and source records attributed to R K Fulbright.

43 records · Page 3Linked to original sources

PubMed1995

Limbic lobe embryology and anatomy: dissection and MR of the medial surface of the fetal cerebral hemisphere.

PURPOSE: To facilitate understanding of limbic lobe anatomy by showing embryologic transformations of the medial surface of the cerebral hemisphere. METHODS: Brains from fetal specimens ranging from 13 to 24 weeks of gestational age were dissected. Photographs were made of the medial surface of the cerebral hemisphere. MR images of different fetal specimens of similar age were made for comparison of MR anatomy with dissected material. RESULTS: At 13 weeks, the entire inner limbic arch of the hippocampal formation is visible on the medial surface of the cerebral hemisphere. The hippocampal sulcus extends from frontal lobe to temporal lobe. At 16 weeks, the outer neocortical limbic arch of the subcallosal area, cingulate gyrus, and parahippocampus gyrus is present. Growth of the corpus callosum is associated with reduction in size of the hippocampal formation in the frontal lobe. The sulcus of the corpus callosum is the remnant of the anterior part of the hippocampal sulcus. At 18 weeks, growth of the parahippocampal gyrus begins to conceal the hippocampal formation. The supracallosal gyrus (indusium griseum), hidden from view by the corpus callosum, and the paraterminal gyrus are remnants of the previously larger hippocampal formation. CONCLUSIONS: Analysis of fetal specimens in different developmental stages with dissection and MR provides insight into embryologic transformations responsible for the complex anatomy of the limbic lobe.

Fetus↗

PubMed1993

Cytologic analysis in fine-needle aspiration biopsy: smears vs cell blocks.

OBJECTIVE: Imaging-directed fine-needle aspiration biopsy can be performed with or without immediate cytologic assessment (smears). We compared the results obtained immediately from cytologic smears with the results of cell-block analysis. We wished to determine the frequency of false-negative findings on cytologic smears in patients subsequently found to have malignant tumors by cell-block analysis. MATERIALS AND METHODS: We retrospectively reviewed the records for 100 consecutive biopsies performed between January 1986 and August 1987. In each case, specimens were obtained from both a 22-gauge and a 20-gauge notched needle placed in tandem. The study group consisted of 84 patients who had results of analyses of both cytologic smears and cell blocks available for review and who had clinical or surgical correlation. RESULTS: Sixty-four (76%) of the 84 biopsies yielded malignant tumor cells, 11 yielded evidence of a benign process, and nine were not diagnostic. Malignant tumor cells were seen on the cytologic smears in 55 (86%) of the 64 patients who had malignant tumors; in the other nine patients, the malignant tumors were indicated by the cell-block analysis only. Within the group of benign disorders, in only one case (9%) was the cell block diagnostic when the cytologic smear was not. CONCLUSION: Operators performing fine-needle aspiration biopsy should be aware of the limitations of immediate cytologic evaluation. Cell-block analysis of the aspirate remaining after the smears are made can be expected to increase the diagnostic accuracy in up to 14% of patients.

Aged↗

PubMed1985

Pyoderma gangrenosum at surgery sites.

Pyoderma gangrenosum is a necrotizing and ulcerative skin disorder often associated with underlying systemic diseases. The etiology remains obscure, with recent investigations emphasizing an altered immune system. A case report is presented of pyoderma gangrenosum occurring at surgical sites in the absence of predisposing factors. Pyoderma gangrenosum in this setting can mimic infectious causes of wound necrosis. Early recognition of the characteristic lesion morphology may prevent unnecessary treatment directed toward infectious agents and facilitate effective control with systemic corticosteroid therapy.

Coronary Artery Bypass↗

PubMedDate not supplied

The cerebellum's role in reading: a functional MR imaging study.

BACKGROUND AND PURPOSE: Long considered to have a role limited largely to motor-related functions, the cerebellum has recently been implicated as being involved in both perceptual and cognitive processes. Our purpose was to determine whether cerebellar activation occurs during cognitive tasks that differentially engage the component processes of word identification in reading. METHODS: Forty-two neurologically normal adults underwent functional MR imaging of the cerebellum with a gradient-echo echo-planar technique while performing tasks designed to study the cognitive processing used in reading. A standard levels-of-processing paradigm was used. Participants were asked to determine whether pairs of words were written in the same case (orthographic processing), whether pairs of words and non-words rhymed with each other, respectively (phonologic assembly), and whether pairs of words belonged to the same category (semantic processing). Composite maps were generated from a general linear model based on a randomization of statistical parametric maps. RESULTS: During phonologic assembly, cerebellar activation was observed in the middle and posterior aspects of the posterior superior fissure and adjacent simple lobule and semilunar lobule bilaterally and in posterior aspects of the simple lobule, superior semilunar lobule, and inferior semilunar lobule bilaterally. Semantic processing, however, resulted in activation in the deep nuclear region on the right and in the inferior vermis, in addition to posterior areas active in phonologic assembly, including the simple, superior semilunar, and inferior semilunar lobules. CONCLUSION: The cerebellum is engaged during reading and differentially activates in response to phonologic and semantic tasks. These results indicate that the cerebellum contributes to the cognitive processes integral to reading.

Adult↗

PubMedDate not supplied

Cerebral activation during multiplication: a functional MR imaging study of number processing.

BACKGROUND AND PURPOSE: Current models of brain function propose that number processing involves the interaction of different neuronal networks. Our purpose was to use functional MR (fMR) imaging to elucidate the brain regions engaged by multiplication. METHODS: Eighteen adults underwent fMR imaging while performing matching, multiplication, and control tasks. For each task, three or four single-digit or low-value double-digit numbers were presented serially followed by a 12-second delay. A target stimulus then appeared and subjects made a judgement by pressing a button box that recorded responses. During the matching task, subjects judged whether the target stimulus matched one of the previous numbers. During the multiplication task, subjects judged whether the target stimulus was the product of the previous numbers. For the control task, the numbers were always zeros, and the subjects responded to a target stimulus that was always four zeros. Composite statistical parametric maps of the time course of activation comparing the control task with the matching and multiplication tasks, respectively, were generated and the significance of signal changes was estimated by randomization of statistical parametric maps. RESULTS: The matching and multiplication tasks resulted in activation (P < .005) in the medial superior frontal gyrus; the anterior cingulate gyrus; the intraparietal sulci, bilaterally; the right superior frontal sulcus bilaterally; the middle, inferior and precentral frontal gyri (left greater than right); the left basal ganglia; and the right lateral and inferior occipital gyri. There was a larger area of early activation in the right middle frontal gyrus during the matching task compared with the multiplication task, and there was a longer interval of activation in the left middle frontal gyrus during the multiplication task (10 seconds) than in the matching task (6 seconds). CONCLUSION: Multiplication and memory of numbers share an integrated network of brain regions. The left frontal lobe, an area also involved in memory and language processes, appears to play an important role in multiplication.

Adult↗

PubMedDate not supplied

Regional distribution of MR findings in hippocampal sclerosis.

PURPOSE: To investigate the distribution of MR findings in the hippocampus and amygdala in patients with hippocampal sclerosis. METHODS: We blindly evaluated MR scans for atrophy and signal changes occurring in the amygdala, hippocampal head, hippocampal body, and hippocampal tail in 57 consecutive patients with hippocampal sclerosis proved by pathologic analysis. RESULTS: Regional atrophy or signal change was present in limbic structures. Atrophy was detected in 52 patients, occurring in the amygdala in 7 (12%), hippocampal head in 29 (51%), hippocampal body in 50 (88%), and hippocampal tail in 35 (61%). Hyperintense signal on long-repetition-time images was observed in 49 patients and involved the amygdala in 2 (4%), hippocampal head in 22 (39%), hippocampal body in 46 (81%), and hippocampal tail in 28 (49%). Thirty patients (53%) had abnormal MR findings distributed through the entire ipsilateral hippocampus, 25 (44%) had regional rather than widespread involvement of limbic structures, and 2 (3%) had no MR abnormalities. CONCLUSION: Signal and volume changes associated with hippocampal sclerosis affect the entire hippocampus in most patients. However, a substantial number of patients have MR abnormalities that are regional, involving only portions of the hippocampus and amygdala. The most frequently affected region was the hippocampal body. These findings can have important implications for surgery and quantitative image analysis, if the seizure generator is related to MR changes.

Adult↗

PubMedDate not supplied

Focal cortical dysplasia of Taylor, balloon cell subtype: MR differentiation from low-grade tumors.

PURPOSE: To test the hypothesis that focal cortical dysplasia of Taylor (FCDT) can be distinguished from low-grade tumors by means of clinical and MR findings. METHODS: We examined 10 clinical and 19 MR imaging variables in patients who underwent surgery for intractable epilepsy over an 8-year period. The 54 patients with low-grade glial neoplasms were compared with the eight patients who had balloon cell FCDT. RESULTS: Statistically significant differences were seen with respect to eight of the MR variables and none of the clinical variables. MR findings suggesting dysplasia rather than tumor included the presence of gray matter thickening associated with a homogeneous hyperintense signal in the subcortical white matter that tapers as it extends to the lateral ventricle. A frontal lobe location favors dysplasia, while a temporal lobe (especially medial temporal lobe) location is more suggestive of a neoplasm. CONCLUSION: Several MR features help distinguish balloon cell FCDT from neoplasms, especially cortical thickening and a tapered signal to the ventricle. This distinction is important for surgical planning, as the decision to operate and the extent of surgical resection often depend on the presence or absence of neoplastic tissue.

Adolescent↗