Biomedical subjects

R J Geckle

Publications and source records attributed to R J Geckle.

5 recordsLinked to original sources

PubMed1997

Reproducibility and reliability of volumetric measurements of olfactory eloquent structures.

RATIONALE AND OBJECTIVES: The authors assessed the reliability and reproducibility of volumetric measurements of olfactory bulbs and tracts (OBTs) and temporal lobes (TLs) with magnetic resonance (MR) imaging. METHODS: Repetitive MR imaging of two phantoms and OBTs and TLs of patients was performed. Regions of interest were manually drawn around the relevant structures, and their volumes were measured at workstations. Intra- and interobserver variability for the two readers were measured. Intraclass and Pearson correlation coefficients and mean percentage differences were calculated. RESULTS: The measured phantom volumes were within 1.9%-12% of the true volumes with a variability of < or = 5%. Intraclass and Pearson correlation coefficients were > or = 0.919 for measurements by a single reader and > or = 0.924 for measurements by different readers. The inter- and intraobserver variabilities were < or = 4.2% for TL and 11.3%-14.6% for OBTs. CONCLUSION: Volumetric measurements of the olfactory apparatus can be reliably and accurately reproduced from MR images.

Humans↗

PubMed1997

Functional MR imaging during odor stimulation: preliminary data.

PURPOSE: To determine the locations and extent of activation in areas of the brain at functional magnetic resonance (MR) imaging with olfactory stimulation and to determine whether accommodation or amplification of brain activation occurs with sequential olfactory stimulation. MATERIALS AND METHODS: Five adult men with normal senses of smell underwent multisection, gradient-echo, echo-planar imaging according to a blood-oxygen-level-dependent experimental paradigm. Odorants that nearly exclusively stimulate the olfactory system and odorants that stimulate the olfactory and trigeminal nerves were compared by using repetitive imaging procedures. RESULTS: Activation with olfactory nerve-mediated odorants was demonstrated in the orbitofrontal cortex (Brodmann area 11) with a right-sided predominance. Mild cerebellar stimulation was also observed. With repeated testing, overall activation with olfactory nerve-mediated odorants declined. Odorants that also stimulated the trigeminal nerve produced additional cingulate, temporal, cerebellar, and occipital activation. Activation with combined trigeminal and olfactory system odors increased more than sixfold with repeated testing. CONCLUSION: Olfactory nerve-mediated and combined olfactory and trigeminal nerve-mediated odorants activate different regions of the brain. Orbitofrontal stimulation spreads to all parts of the brain when a trigeminal component is added. Habituation (deactivation) occurs with repeated testing of olfactory nerve-mediated odorants, while, paradoxically, activation increases with repeated exposure to odors that also stimulate the trigeminal nerve.

Adult↗

PubMed1997

Adenoidal width and HIV factors.

PURPOSE: To determine the factors that correspond to adenoidal hypertrophy, often prominent in human immunodeficiency virus (HIV)-positive patients. METHODS: The sagittal T1-weighted MR images of 21 HIV-positive patients (age range, 25 to 50 years; mean, 37 years) and 21 healthy control subjects (age range, 24 to 55 years; mean, 35 years) were reviewed blindly and independently by two radiologists who measured the maximal dimension of the nasopharyngeal lymphoid tissue. Twenty-six additional HIV-positive patients were combined with the original 21 HIV-positive patients, and the hematologic studies of these 47 patients were compared with the adenoidal measurements to assess whether a relationship existed between nasopharyngeal prominence and hematocrit, white blood cell count, and CD4 count. RESULTS: Mean adenoidal width was 6.76 mm (SD, 5.82) in the HIV-positive population, but was only 3.36 mm (SD, 2.48) in the age-matched control group. Age and HIV status correlated with nasopharyngeal width measurements. No relationship between adenoidal width and hematocrit, CD4 count, or white blood cell count was evident. CONCLUSION: After correcting for age, we found that adenoidal lymphoid tissue is more abundant in HIV-positive persons than in control subjects. The hematologic ramifications of this finding remain uncertain.

Adenoids↗

PubMed1996

MR evaluation of patients with congenital hyposmia or anosmia.

OBJECTIVE: The purpose of this study was to evaluate patients with reduced or no sense of smell since birth for sites of abnormality by MR imaging. MATERIALS AND METHODS: Twenty-five patients who reported no olfactory function since birth were evaluated by olfactory testing, sinonasal endoscopy, and MR imaging. Surface coil and head coil images of the olfactory bulbs, olfactory tracts, subfrontal cortex, and temporal lobes in contiguous 3-mm sections were obtained. Two reviewers determined unilateral olfactory bulb and tract volumes and temporal lobe volumes in two separate sessions. Qualitative grading for olfactory bulb, olfactory tract, olfactory sulcus, subfrontal region, hippocampus, and temporal lobe damage also was performed. RESULTS: The absence of olfactory bulbs and tracts (68-84%) or the presence of hypoplasia (16-32%) was noted in all cases. Eight individuals had Kallmann's syndrome (hypogonadotropic hypogonadism with anosmia). Temporal and/or frontal lobe volume loss was noted in five individuals and was mild in all but one individual. CONCLUSION: Congenital anosmia or hyposmia appears to be an olfactory bulb-olfactory tract phenomenon rather than a cerebral process.

Adult↗

PubMedDate not supplied

Posttraumatic olfactory dysfunction: MR and clinical evaluation.

PURPOSE: To evaluate the sites of injury in patients with posttraumatic olfactory deficits and to compare damage with findings on clinical olfactory tests. METHODS: Twenty-five patients with posttraumatic olfactory dysfunction were examined by means of olfactory testing, endoscopy, and MR imaging. MR surface-coil scans through the olfactory bulbs and tracts and head-coil scans of the temporal lobes were evaluated. Quantitative and qualitative gradings of damage to the olfactory bulbs, tracts, subfrontal region, hippocampus, and temporal lobes were compared with results on tests of odor identification, detection, memory, and discrimination. RESULTS: Twelve patients were anosmic, eight had severe impairment, and five were mildly impaired. Injuries to the olfactory bulbs and tracts (88% of patients), subfrontal region (60%), and temporal lobes (32%) were found, but these did not correlate well with individual olfactory test scores. Volumetric analysis showed that patients without smell function had greater volume loss in olfactory bulbs and tracts than did those posttraumatic patients who retained some sense of smell. Qualitative and quantitative assessments of damage showed few significant correlations with olfactory tests, probably because of multifocal injuries, primary olfactory nerve damage, and the constraints of a small sample size on the detection of clinically significant differences. CONCLUSION: MR imaging shows abnormalities in patients with posttraumatic olfactory dysfunction at a very high rate (88%), predominantly in the olfactory bulbs and tracts and the inferior frontal lobes.

Adolescent↗