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Biomedical subjects

C P Derdeyn

Publications and source records attributed to C P Derdeyn.

46 records · Page 3Linked to original sources
PubMed1996

Cost-effectiveness of screening for asymptomatic carotid atherosclerotic disease.

BACKGROUND AND PURPOSE: The value of screening for asymptomatic carotid stenosis has become an important issue with the recently reported beneficial effect of endarterectomy. The purpose of this study is to evaluate the cost-effectiveness of using Doppler ultrasound as a screening tool to select subjects for arteriography and subsequent surgery. METHODS: A computer model was developed to simulate the cost-effectiveness of screening a cohort of 1000 men during a 20-year period. The primary outcome measure was incremental present-value dollar expenditures for screening and treatment per incremental present-value quality-adjusted life-year (QALY) saved. Estimates of disease prevalence and arteriographic and surgical complication rates were obtained from the literature. Probabilities of stroke and death with surgical and medical treatment were obtained from published clinical trials. Doppler ultrasound sensitivity and specificity were obtained through review of local experience. Estimates of costs were obtained from local Medicare reimbursement data. RESULTS: A one-time screening program of a population with a high prevalence (20%) of > or = 60% stenosis cost $35130 per incremental QALY gained. Decreased surgical benefit or increased annual discount rate was detrimental, resulting in lost QALYs. Annual screening cost $457773 per incremental QALY gained. In a low-prevalence (4%) population, one-time screening cost $52588 per QALY gained, while annual screening was detrimental. CONCLUSIONS: The cost-effectiveness of a one-time screening program for an asymptomatic population with a high prevalence of carotid stenosis may be cost-effective. Annual screening is detrimental. The most sensitive variables in this simulation model were long-term stroke risk reduction after surgery and annual discount rate for accumulated costs and QALYs.

Angiography↗
PubMed1996

Carotid artery thrombus associated with severe iron-deficiency anemia and thrombocytosis.

BACKGROUND: Thrombus within the carotid artery usually occurs in vessels with severe atherosclerotic disease and may embolize to cause transient ischemic attacks and cerebral infarctions. The risk factors for carotid artery thrombus formation in the absence of atherosclerosis are not well characterized. A case series is presented that suggests an association of carotid artery thrombus with severe iron-deficiency anemia and thrombocytosis. CASE DESCRIPTIONS: We describe three women with severe iron-deficiency anemia and thrombocytosis secondary to menorrhagia who developed carotid artery thrombi. Thrombi were detected radiographically. The patients were treated with anticoagulation and antiplatelet therapy. In two patients, follow-up neuroimaging 10 to 14 days later demonstrated resolution of the thrombus and no identifiable vascular disease. CONCLUSIONS: Severe iron-deficiency anemia with thrombocytosis may be a risk factor for carotid artery thrombus formation. Medical management with anticoagulation and antiplatelet therapy is a reasonable approach for these patients while the thrombus resolves.

Adult↗
PubMed1995

Role of Doppler US in screening for carotid atherosclerotic disease.

PURPOSE: To evaluate Doppler ultrasound (US) as a screening modality before arteriography for extracranial carotid artery disease. MATERIALS AND METHODS: The net benefit in stroke reduction from screening with Doppler US was calculated on the basis of literature estimates of disease prevalence, risk reduction data, and locally validated sensitivities and specificities for detection of carotid artery stenosis and occlusion in 215 patients. RESULTS: Screening a symptomatic population demonstrated a net stroke reduction. Screening asymptomatic populations with a 20% prevalence of > or = 60% stenosis also yielded a net stroke reduction. Screening low-prevalence (5%) asymptomatic populations produced a small benefit, which was lost if arteriographic or surgical complications increased slightly. Arteriographic confirmation of the US diagnosis of occlusion produced a small benefit only in the symptomatic population. CONCLUSION: Screening symptomatic and high-prevalence asymptomatic populations with US reduces stroke. Increased arteriographic or surgical complication rates reduce the benefit of screening in any population.

Arteriosclerosis↗
PubMed1995

Intraoperative digital subtraction angiography: a review of 112 consecutive examinations.

PURPOSE: To examine the effect of intraoperative angiography on neurosurgery and angiographic technical success, safety, and accuracy. METHODS: Angiographic studies, surgical reports, and hospital records were reviewed retrospectively for 112 consecutive procedures in which intraoperative angiography was performed during neurosurgery. The results of conventional postoperative angiograms in 28 of the 112 procedures were also reviewed. A portable digital subtraction angiography unit was used for all patients. Decisions in the operating room were based on review of stored videotaped images. RESULTS: Eighteen studies were obtained in 14 patients after arteriovenous malformation resection. Unsuspected residual nidus was identified and resected in 3 patients. The intraoperative angiogram also altered therapy for 2 patients undergoing staged resections of arteriovenous malformations. Sixty-six studies were performed after aneurysm clipping, with clinically significant changes in surgical therapy made in 5 patients. Of 28 examinations after carotid endarterectomy, 3 led to revision. Two complications of angiography occurred. One led to a permanent neurologic deficit, yielding a complication rate of 1.5% for stroke. Two examinations could not be completed because of technical factors. Two false-negative examinations were identified on postoperative studies. One patient with a normal intraoperative study after carotid endarterectomy thrombosed the repaired internal carotid artery after surgery. CONCLUSIONS: Intraoperative angiography altered surgery in 13 of 112 procedures on 104 patients. This study supports the use of intraoperative angiography in arteriovenous malformation resection and in complex aneurysm surgery, but not for routine carotid endarterectomy.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion.

CONTEXT: The relative importance of hemodynamic factors in the pathogenesis and treatment of stroke in patients with carotid artery occlusion remains controversial. OBJECTIVE: To test the hypothesis that stage II cerebral hemodynamic failure (increased oxygen extraction measured by positron emission tomography [PET]) distal to symptomatic carotid artery occlusion is an independent risk factor for subsequent stroke in medically treated patients. DESIGN AND SETTING: Prospective, blinded, longitudinal cohort study of patients referred from a group of regional hospitals between 1992 and 1996. PATIENTS: From 419 subjects referred, 81 with previous stroke or transient ischemic attack in the territory of an occluded carotid artery were enrolled. All were followed up to completion of the study, with average follow-up of 31.5 months. MAIN OUTCOME MEASURES: Telephone contact every 6 months recorded the subsequent occurrence of all stroke, ipsilateral ischemic stroke, and death. RESULTS: Stroke occurred in 12 of 39 patients with stage II hemodynamic failure and in 3 of 42 patients without (P = .005); stroke was ipsilateral in 11 of 39 patients with stage II hemodynamic failure and in 2 of 42 patients without (P = .004). Six deaths occurred in each group (P = .94). The age-adjusted relative risk conferred by stage II hemodynamic failure was 6.0 (95% confidence interval [CI], 1.7-21.6) for all stroke and 7.3 (95% CI, 1.6-33.4) for ipsilateral stroke. CONCLUSIONS: Stage II hemodynamic failure defines a subgroup of patients with symptomatic carotid occlusion who are at high risk for subsequent stroke when treated medically. A randomized trial evaluating surgical revascularization in this high-risk subgroup is warranted.

Aged↗
PubMedDate not supplied

MRI of esthesioneuroblastoma.

OBJECTIVE: Esthesioneuroblastomas are uncommon tumors originating in the olfactory epithelium of the superior nasal cavity. Accurate staging appropriately guides therapy and predicts survival. The MR appearance and pattern of contrast enhancement in these tumors have not been well described. The goals of this article were to analyze the MRI characteristics of esthesioneuroblastoma, including extent of tumor, differentiation from obstructive sinus disease, MR signal, and pattern of contrast enhancement. MATERIALS AND METHODS: The MR examinations of six patients with proven advanced esthesioneuroblastoma were reviewed. Standard SE T1- and T2-weighted axial images were obtained [550-600/15-25 and 2,000-2,760/80-90 (TR/TE), respectively], followed by postcontrast axial and coronal T1-weighted sequences in all patients. RESULTS: Five of the six tumors were centered in the superior nasal cavity and one was centered in the lateral ethmoid air cells. Five tumors extended intracranially. Postobstructive sinus disease was always encountered. As compared to gray matter, the signal on T1-weighted images was either hypo- or isointense. On T2-weighted images, the signal varied from iso- to hyperintensity. Contrast enhancement was intense and of variable uniformity. CONCLUSION: Magnetic resonance signal characteristics helped to distinguish obstructive sinus disease from tumor. The MR signal characteristics and pattern of contrast enhancement were nonspecific for esthesioneuroblastoma. Enhanced images, particularly in the coronal plane, were very helpful in identifying intracranial extension.

Adult↗
PubMedDate not supplied

Polyvinyl alcohol particle size and suspension characteristics.

PURPOSE: To evaluate the size and shape of commercially available polyvinyl alcohol (PVA) particles and to determine whether they change in size when suspended in nonionic contrast and in a solution of nonionic contrast and absolute alcohol. METHODS: The two-dimensional area and the long and short axis of PVA particles from several different vendors were measured using a light microscope attached to a video system and an image-processing software program. Particles were measured as packaged (dry or suspended in saline), suspended in ioversol, and suspended in ioversol containing 30% alcohol. RESULTS: All brands of dry particles had similar microscopic appearances. The saline-suspended particles had fewer and finer perforations. After suspension in contrast, all sizes and brands of dry particles significantly increased in size. The particles packaged in saline did not expand. The addition of alcohol to the contrast did not consistently change particle size. Particle aggregation was similar in both contrast suspensions for all groups of particles. Particles less than 50 microns in size were rarely observed in any PVA preparation after suspension. CONCLUSIONS: The three dry PVA preparations seem to be similar. All increase significantly in size when suspended in nonionic contrast or contrast-alcohol solutions. The saline-packaged PVA particles were different from the dry variety and did not enlarge in contrast or contrast-alcohol solutions. Alcohol did not change the size or suspension characteristics of PVA particles. Particles less than 50 microns in size were rarely identified.

Contrast Media↗