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Biomedical subjects

C P Wood

Publications and source records attributed to C P Wood.

11 recordsLinked to original sources
PubMed2001

Recurrence of Susac syndrome (retinocochleocerebral vasculopathy) after remission of 18 years.

Susac syndrome (retinocochleocerebral vasculopathy) is a syndrome of unknown pathogenesis. The triad of multifocal encephalopathy, visual loss, and hearing loss is caused by microangiopathy of the brain, retina, and cochlea. The illness tends to be monophasic, and to our knowledge, recurrence after years of remission has not been reported. We describe a 51-year-old woman with symptoms, signs, and brain magnetic resonance imaging findings consistent with recurrence of Susac syndrome 18 years after remission. Clinicians should be aware of the possibility of late recurrence of Susac syndrome when evaluating patients with a distant history of the syndrome who present with complaints referable to the brain, retina, and cochlea.

Blindness↗
PubMed2000

An evaluation of JPEG and JPEG 2000 irreversible compression algorithms applied to neurologic computed tomography and magnetic resonance images. Joint Photographic Experts Group.

We performed visual comparison of 200 head magnetic resonance (MR) and 200 head computed tomography (CT) images compressed at two levels using standard Joint Photographic Experts Group (JPEG) irreversible compression and a preliminary version of the JPEG 2000 irreversible algorithm. Blinded evaluations by neuroradiologists compared original versus either JPEG or JPEG 2000. We found that this version of JPEG 2000 did not perform as well as the current JPEG for head CTs, but for MR images, JPEG 2000 performed as well or better. Around 7:1 compression ratio seemed to be a conservative point where there was no perceptible difference.

Algorithms↗
PubMed1998

The results of radiotherapy for brainstem tumors.

OBJECTIVE: This analysis was performed to examine the outcome of adult and pediatric patients with brainstem tumors. METHODS AND MATERIALS: Forty patients with brainstem glioma were evaluated retrospectively. Included were 24 females and 16 males ranging in age from 3 to 81 years (median, 29.5 years). These patients were treated with various combinations of surgery, chemotherapy, and radiotherapy (RT). The length of follow-up in survivors ranged from 0.6 to 20 years (median: 3.2 years, mean: 6 years). Survival rates were calculated with the Kaplan Meier method and differences between survival curves were calculated using the log-rank test. RESULTS: The overall 2 and 5-year survival rates were 44% and 34%, respectively. The median survival time was 19 months. The 5-year survival rate was 54% for patients with tumors outside the pons compared to 21% for those with tumors involving the pons (p = 0.04). The 5-year survival rate was 59% for patients with exophytic tumors as compared to 23% for those with intrinsic tumors (p = 0.05). Patients undergoing subtotal resection had a 5-year survival rate of 53% compared to 28% for those having only a biopsy or no surgical intervention (p = 0.04). None of the other potential prognostic or treatment related factors evaluated [patient age, tumor grade, tumor histology, radiotherapy parameters (including BID fractionation, 3-D treatment planning, or the use of doses > 55 Gy), or the administration of adjuvant chemotherapy] evaluated were associated with patient survival. CONCLUSIONS: Brainstem gliomas generally occur in younger individuals. The survival rates were better for patients with exophytic tumors, those involving sites other than the pons, and tumors amenable to subtotal resection. Improvements in the outcome of patients with brainstem gliomas will require new therapeutic approaches.

Adolescent↗
PubMed1998

Effects of a stereotactic headframe assembly on proton magnetic resonance spectroscopy.

The effects of a magnetic resonance-compatible stereotactic headframe assembly on single voxel proton magnetic resonance spectroscopy (MRS) were investigated. Multiple stimulated echo acquisition mode (STEAM) spectra were obtained within a commercially available brain metabolite phantom placed within the headframe assembly (Leksell, Model G). All acquisition parameters were kept constant, except voxel location. Maximal distortion occurred for voxels acquired in the immediate vicinity of a headframe fixation pin, manifested by spectral broadening, changes in peak area and height and distortion of the baseline, rendering these acquisitions nondiagnostic. The range of this interaction was short, and a voxel acquired with nearest edge located 2.0 cm or greater from the fixation pin tip produced NAA/Cr, Cho/Cr and mI/Cr ratios differing by less than 7.5% from a spectrum obtained at the phantom center. The feasibility of performing single voxel MRS with a stereotactic headframe in place is demonstrated.

Brain Mapping↗
PubMed1996

Systemic gadolinium toxicity in patients with renal insufficiency and renal failure: retrospective analysis of an initial experience.

OBJECTIVE: To study the possible deleterious systemic effects of gadolinium in patients with impaired renal function. DESIGN: We retrospectively analyzed the routine laboratory data and clinical course of patients who had undergone a gadolinium-enhanced magnetic resonance imaging (MRI) examination of the brain and spine and had evidence of impaired glomerular filtration. MATERIAL AND METHODS: Between October 1988 and October 1992, 15,830 patients underwent gadolinium-enhanced MRI at our institution, 151 of whom had a serum creatinine value of more than 2 mg/dL. The clinical records of these 151 patients were thoroughly examined for the period from 3 days before to 30 days after the gadolinium-enhanced MRI examination. All data were analyzed in an attempt to detect any adverse events that could be related to free gadolinium as a result of dissociation from the chelating agent due to prolonged elimination times (that is, increased serum creatinine concentrations). In addition, we calculated the 90-day mortality rate for both the study group and a matched control population of 80 patients who had undergone MRI of the brain and spine before gadolinium was available. RESULTS: The overall incidence of adverse events in the study group was 3.6%. No event was severe or life threatening--nausea and rash occurred in two patients each, and seizure and headache occurred in one patient each. These findings were not significantly different from those in previous studies performed in populations with normal elimination times. Moreover, no significant difference was noted in the 90-day mortality rate (14.6% of the study group) in comparison with that in the control group (13.8%). CONCLUSION: On the basis of this initial retrospective analysis, we were unable to detect any clinical deleterious effects of administration of gadolinium for MRI examination in patients with impaired renal function. Further investigation with prospective studies is needed to confirm these initial retrospective findings.

Adult↗
PubMed1995

Genetic mosaic analysis of the equatorial-less mutation in Drosophila melanogaster.

eql (equatorial-less) is a recessive lethal mutation on the second chromosome of Drosophila melanogaster. J. Campos-Ortega found that eql clones in somatic mosaic flies have reduced numbers of photoreceptor cells, and he suggested that only the R1, R6, and R7 photoreceptor cells were missing in this mutant. These photoreceptor cells help to define the inverted orientation of ommatidial facets along the equatorial midline of the fly eye, hence the mutation was named "equatorial-less." We have conducted a detailed analysis of the eql mutation, by serial section reconstruction of eql clones marked with bw- or w- in somatic mosaic flies. We found that all photoreceptor cell types (R1-R8) could be deleted by the eql mutation, and in rare cases the number of photoreceptor cells was increased. The apparent lack of photoreceptor cell type specificity was confirmed by our analysis of genetically mosaic facets, which indicated that no single photoreceptor cell, or subset of photoreceptor cells, was uniquely required to express eql+. Rather, eql appears to function in all photoreceptor cells, and possibly in all eye precursor cells. The distribution of photoreceptor cell numbers in w eql facets was consistent with the hypothesis that each photoreceptor cell was deleted independently of the others. The eql gene is located on the right arm of chromosome 2 at map location 2-104.5 +/- 0.7 and lies between the polytene chromosome bands 59D8 and 60A7.

Animals↗