Applications of decision analysis.
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Cost-Benefit Analysis↗
Biomedical subjects
D F Kallmes
Publications and source records attributed to D F Kallmes.
In vitro proliferation and adhesion of basic fibroblast growth factor-producing fibroblasts on platinum coils.
PURPOSE: To evaluate the growth and adhesion characteristics in vitro of genetically modified, basic fibroblast growth factor-producing fibroblasts on platinum detachable coils. MATERIALS AND METHODS: Coils of two sizes were coated with laminin, poly-L-lysine, fibronectin, and type I and type IV collagen and were cultured with basic fibroblast growth factor-secreting fibroblasts. Type I collagen strands were inserted in the lumen of some coils. Cellular proliferation and adherence during passage of coils through microcatheters were studied with both light and scanning electron microscopy. Growth factor concentration in the culture medium was measured. RESULTS: Rapid cellular proliferation was noted on all coated coils except those coated with type IV collagen. Proliferation on uncoated coils was slightly slower than on most coated coils, although confluent cell layers were present on uncoated larger-diameter coils within 48 hours. Cells had a marked propensity to grow between the primary coil windings into the coil lumen, except in coils that contained collagen filaments. Passage through microcatheters caused widespread stripping of cells from the outer surface of coils, especially the uncoated samples. Viable cells remained in the coil lumen. Supernatant contained high concentrations of growth factor. CONCLUSION: Platinum embolic coils are a promising mechanism of cell delivery for stimulation of scar formation or other desirable biologic effects.
3T3 Cells↗
Platinum coil-mediated implantation of growth factor-secreting endovascular tissue grafts: an in vivo study.
PURPOSE: To demonstrate in vivo that platinum embolic coils can be used to deliver genetically modified, growth factor-secreting fibroblast grafts into the endovascular space with the long-term goal of improving fibrosis within coil-embolized cerebral aneurysms. MATERIALS AND METHODS: Murine fibroblasts that contained multiple inserts of the DNA for human basic fibroblast growth factor were grown in culture onto 10-mm-long segments of Guglielmi detachable coils. Control (n = 4) and fibroblast-bearing (n = 4) coils were implanted into the common carotid artery in nude rats. The arterial segments that contained the coil were harvested after 14 or 35 days. Cellular content and collagen formation in the treated vessels were assessed histologically. RESULTS: At both 14 and 35 days, samples with control coils showed primarily involuting blood elements with minimal fibroblast proliferation or collagen formation. At 14 days, samples with fibroblast-bearing coils showed extensive fibroblast proliferation. At 35 days, samples with fibroblast-bearing coils showed marked interval fibroblast proliferation and collagen formation. CONCLUSION: Platinum coils can be used as a cell delivery device. Direct intravascular implantation of growth factor-secreting fibroblast grafts leads to improved intravascular scar formation, therefore theoretically reducing the potential for aneurysm regrowth or coil compaction.
Animals↗
Prevalence of cerebral aneurysms in patients with fibromuscular dysplasia: a reassessment.
OBJECT: The aim of this study was to determine the prevalence of cerebral saccular aneurysms in patients with carotid artery and/or vertebral artery (VA) fibromuscular dysplasia (FMD). METHODS: A metaanalysis was performed using data from 17 previously reported series of patients with internal carotid artery (ICA) and/or VA FMD that included information on the prevalence of cerebral aneurysms. In addition, the authors retrospectively evaluated their own series of 117 patients with ICA and/or VA FMD to determine the prevalence of cerebral aneurysms. The metaanalysis of the 17 earlier series, which included 498 patients, showed a 7.6 +/- 2.5% prevalence of incidental, asymptomatic aneurysms in patients with ICA and/or VA FMD. In the authors' series of patients with FMD, 6.3 +/- 4.9% of patients harbored an incidental, asymptomatic aneurysm. When the authors' series was combined with those included in the metaanalysis, the prevalence was found to be 7.3 +/- 2.2%. The prevalence of aneurysms in the general population would have to be greater than 5.6% for there to be no statistically significant difference (chi-square test, p < 0.05) when compared with this 7.3% prevalence in patients with FMD. CONCLUSIONS: The prevalence of intracranial aneurysms in patients with cervical ICA and/or VA FMD is approximately 7%, which is not nearly as high as the 21 to 51% prevalence that has been previously reported.
Adult↗
Guglielmi detachable coil embolization for unruptured aneurysms in nonsurgical candidates: a cost-effectiveness exploration.
PURPOSE: We calculated the incremental cost-utility ratio for Guglielmi detachable coil (GDC) embolization versus no therapy for unruptured intracranial aneurysms considered inappropriate for surgical clipping procedures. METHODS: Decision tree and Markov analyses that employ cohort simulation were applied to determine the incremental cost-utility ratio of GDC embolization versus no therapy for unruptured cerebral aneurysms. Clinical values required as input data were estimated from the literature for the following variables: relative frequencies of complete aneurysmal occlusion, partial aneurysmal occlusion, and attempted coiling (no coils detached); morbidity and mortality of GDC embolization; frequency, morbidity, and mortality of spontaneous aneurysmal rupture in untreated and GDC-embolized aneurysms; annual rate of recanalization of GDC-embolized aneurysms; quality of life when knowingly living with untreated or GDG-embolized aneurysms and of living with fixed neurologic deficit; costs of GDC embolization, spontaneous aneurysmal rupture, stroke, and rehabilitation; and discount rate. Cost-utility ratios below $50000 per quality-adjusted life year saved were considered acceptable. Sensitivity analyses were performed for all relevant input variables. RESULTS: Baseline input values resulted in acceptable cost-utility ratios for GDC embolization of unruptured intracranial aneurysms. These ratios remained within acceptable limits across wide ranges of various input parameters. Cost-effectiveness was markedly affected by the natural course of unruptured, untreated aneurysms; rates of spontaneous rupture greater than 2% per year resulted in favorable cost-utility ratios that were relatively unaffected by variation in GDC efficacy, while rates of rupture less than 1% per year resulted in unfavorable ratios that were highly dependent on GDC efficacy. Many of the GDC efficacy indexes, such as rate of failed coiling, early recanalization, and progressive aneurysmal thrombosis, have mild effects on the cost-utility ratios. GDC complication rate as well as life expectancy had moderate effects on the analysis. The influence of late aneurysmal recanalization was mild unless high rates of rupture for partially coiled aneurysms were applied. Suboptimal clip placement resulting from the presence of GDC coils within a ruptured aneurysm had no demonstrable consequence on cost-utility ratios. CONCLUSIONS: The single most influential variable determining the cost-effectiveness of GDC embolization in our analysis was the natural course of untreated aneurysms. Other important variables included GDC-related morbidity and life expectancy at the time of GDC embolization.
Cost-Benefit Analysis↗
The current status of endovascular stroke therapy.
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Adult↗
Frequency and significance of a small distal ICA in carotid artery stenosis.
PURPOSE: Accurate calculation of the percentage of stenosis is crucial for identifying candidates for endarterectomy. Our goal was to quantify the reduction in diameter of the distal internal carotid artery (ICA) as a function of proximal ICA stenosis and to discuss the implications of distal ICA narrowing on the calculation of percentage of stenosis using the criteria of the North American Symptomatic Carotid Endarterectomy Trial (NASCET). METHODS: We retrospectively reviewed the carotid angiograms of 81 patients referred for evaluation of carotid stenosis. The caliber of the ICA stenosis and the diameters of the normal distal ICA, the common carotid artery, and the internal maxillary artery were remeasured with precision calipers. The percentage of stenosis derived from the NASCET criteria were compared with vessel diameter and with the difference in size of the ipsilateral and contralateral distal ICAs. We then recalculated the percentage of stenosis by substituting the presumed normal contralateral distal ICA diameter for the ipsilateral distal ICA diameter. RESULTS: In carotid arteries without significant stenosis (<70%), the distal ICA diameter measured 5.94+/-1.10 mm, but in vessels with severe stenosis (>70%), the distal ICA diameter measured 4.69+/-1.23 mm. After recalculation, four of 26 vessels were upgraded in classification from moderate (40% to 69%) to severe (>70%) stenosis. CONCLUSION: The diameter of the distal ICA begins to decrease when the proximal stenosis is 60% or greater. If the ICA distal to a stenosis is smaller than the contralateral ICA, recalculating the percentage of stenosis by substituting measurements of the contralateral distal ICA diameter may be warranted.
Angiography, Digital Subtraction↗
Hemorrhagic complications in embolization of a meningioma: case report and review of the literature.
We report a case of hemorrhage in a parasellar meningioma shortly after embolization of the dural cavernous carotid artery branches supplying the tumor. This represents the first report of hemorrhage within a meningioma resulting from embolization with small (50 to 150-microns) polyvinyl alcohol particles, as well as the first reported case of hemorrhage complicating meningioma embolization from internal rather than external carotid artery branch embolization. We also review previously reported cases of postembolization hemorrhage from meningiomas.
Angiography, Digital Subtraction↗
Intracranial dissecting aneurysm causing subarachnoid hemorrhage: the role of computerized tomographic angiography and magnetic resonance angiography.
BACKGROUND: With increasing frequency, dissecting aneurysms of the intracranial arteries are recognized as a possible cause of subarachnoid hemorrhage (SAH). In the presence of a dissecting aneurysm, angiographic changes may be subtle at presentation and correct diagnosis often requires serial angiograms. We report a patient with a dissecting aneurysm of the anterior cerebral artery (ACA) causing SAH, in whom less invasive diagnostic tools, such as high-resolution computerized tomographic angiography (CTA) and magnetic resonance angiography (MRA), were helpful in confirming the diagnosis and in following the evolution of the dissection. CASE PRESENTATION: We present this 51-year old woman who experienced the sudden onset of severe headache without associated neurological deficits. Head CT showed SAH with blood in the interhemispheric fissure, suggesting a ruptured ACA aneurysm. Serial cerebral angiograms failed to demonstrate an aneurysmal sac, but showed evolving irregularities of the ACA consistent with a dissecting aneurysm. These findings were confirmed by CTA and MRA. The patient was treated conservatively and made an excellent recovery. A MRA obtained 2 months later showed slight improvement of the previously visualized ACA dilatation. CONCLUSION: Serial angiograms are often required to confirm the diagnosis and to follow the evolution of an intracranial dissection. With recent advances in neuroradiological techniques, however, critical information can be obtained by less invasive imaging studies, such as CTA and MRA.
Aortic Dissection↗
Partial pediculectomy in the treatment of lumbar spinal stenosis: technical note.
OBJECTIVE: We note an additional pathological condition associated with lumbar spinal stenosis that may be responsible for significant postoperative pain. Recognizing that nerve roots are stretched around hypertrophic pedicles in some cases of spinal stenosis, we have altered our surgical management of these cases to address what may be a previously unrecognized but significant anatomic pathological finding. SURGICAL TECHNIQUE: After ipsilateral posterior bony decompression of the spinal canal, the nerve root is examined as it courses around the pedicle. If the root appears stretched, the medial part of the pedicle is removed using first a diamond bit and then a curet. The nerve root is retracted and protected during this procedure. RESULTS: Inspection of the root after partial pediculectomy frequently reveals lateral movement of the root into space previously occupied by the pedicle. Anatomically, the nerve is better decompressed and free of obstruction. This technique adds little time to the overall duration of the operation. CONCLUSION: Anatomic evidence obtained through intraoperative examination and preoperative imaging techniques indicates that partial pediculectomy may play a role in the treatment of some cases of lumbar stenosis.
Decompression, Surgical↗
Routine angiography after surgery for ruptured intracranial aneurysms: a cost versus benefit analysis.
PURPOSE: To assess the cost versus the benefit of routine cerebral angiography after surgery for ruptured aneurysms. METHODS: Decision tree and Markov analyses that used cohort simulation were conducted to determine the incremental cost:benefit ratio of routine postsurgical angiography. Input data for unexpected partially clipped and unclipped cerebral aneurysms were estimated from the literature for the following variables: frequency; annual rate of subsequent hemorrhage; morbidity and mortality rates of subsequent hemorrhage; efficacy and morbidity and mortality rates of subsequent surgery; and costs of subsequent surgery, angiography, subsequent hemorrhage of aneurysm, and rehabilitation. RESULTS; Baseline input variables resulted in an acceptable cost:benefit ratio for routine postsurgical angiography. However, essentially all of the benefit was derived from intervening in cases of unexpected unclipped aneurysms rather than partially clipped aneurysms. Isolated instances of angiography and subsequent surgery for unexpected partially clipped aneurysms yielded unacceptable cost:benefit ratios. Surgical costs had minimal effect on the analysis. CONCLUSIONS: When routine postsurgical angiography was performed primarily to diagnose and to subsequently operate on unexpected partially clipped aneurysms, the cost:benefit ratio was unacceptable. However, even low frequencies of unexpected unclipped aneurysms resulted in favorable cost:benefit ratios.
Algorithms↗
Percutaneous transvenous coil embolization of a type 4 sagittal sinus dural arteriovenous fistula: case report.
OBJECTIVE AND IMPORTANCE: To present an alternative endovascular therapy for a Type 4 sagittal sinus dural arteriovenous fistula (DAVF). CLINICAL PRESENTATION: A 74-year-old man presented with right facial paresthesias. Magnetic resonance imaging revealed an enlarged left parasagittal cortical vein adjacent to the superior sagittal sinus. Angiography demonstrated a Type 4 sagittal sinus DAVF. INTERVENTION: The DAVF was cured using percutaneous transvenous coil embolization. CONCLUSION: This case represents the first report in which a sagittal sinus DAVF was cured using a percutaneous transvenous endovascular approach.
Aged↗
A second look at the second-look angiogram in cases of subarachnoid hemorrhage.
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Cerebral Angiography↗
The normal anterior commissure of the glottis.
OBJECTIVE: We characterized the normal width of the anterior commissure of the glottis by measuring its dimensions on CT scans obtained in patients who had no laryngeal disorders. SUBJECTS AND METHODS: CT scans of patients referred for cervical CT myelography were prospectively reviewed by a single board-certified radiologist. Axial images through the anterior commissure (localized by vocal process of the arytenoid cartilage, the vocal muscle, or both) were magnified on the viewing console of the CT scanner. Window and level were chosen to simulate our routine settings for CT scans of the neck. Anteroposterior width of the anterior commissure was measured using an electronic ruler with 1-mm marks. RESULTS: Sixty-five patients were prospectively evaluated. Nine patients were excluded because of substantial motion artifact, and another 18 were excluded because CT images did not include the entire larynx. Thus, the final study group included 38 patients. The average width of the anterior commissure was 1.02 +/- 0.56 mm. The width was less than or equal to 1.1 mm in 22 (58%) of 38 patients. The width was less than or equal to 1.7 mm in 35 (92%) of 38 patients. Forty-two percent (16 of 38 patients) had anterior commissures wider than 1.0 mm. The maximum width of 2.2 mm was seen in only one patient. CONCLUSION: The mean width of the anterior commissure was approximately 1.0 mm. However, 42% of patients had anterior commissures wider than 1.0 mm. In our series, using an upper limit of 1.6 mm as a normal measurement for the anterior commissure would have included 92% of patients, and an upper limit of 2.1 mm would have encompassed the mean plus two SDs.
Female↗
Typical and atypical MR imaging features of intracranial epidermoid tumors.
OBJECTIVE: We categorized the MR imaging characteristics of intracranial epidermoid tumors. MATERIALS AND METHODS: MR images from 23 cases of intracranial epidermoid tumors were reviewed retrospectively. Signal intensities of tumor relative to surrounding structures were noted, as were the internal architecture of the tumors and the presence and degree of hydrocephalus. RESULTS: Seventeen (74%) of 23 cases of intracranial epidermoid tumors were revealed as slightly hyperintense relative to CSF on T1-weighted MR images. Nineteen (95%) of 20 cases were hyperintense relative to CSF on proton density-weighted MR images. Fifteen (65%) of 23 cases were isointense to CSF on T2-weighted MR images, whereas the remaining eight cases (35%) were hyperintense to CSF on T2-weighted MR images. One (4%) of 23 cases showed signal intensity that was isointense to CSF on all pulse sequences. Fifteen (65%) of 23 cases showed heterogeneous signal characteristics on either T1-weighted or proton density-weighted MR images, or both. Eight (35%) of 23 cases showed a rim of hyperintensity on proton density-weighted MR images. Five (33%) of the 15 cases that received gadolinium showed rim enhancement. Five (22%) of 23 cases were multilocular, with different regions of tumors showing highly variable imaging characteristics. Two (9%) of 23 cases showed high signal intensity on T2-weighted MR images in the adjacent brain parenchyma. Two (9%) of 23 cases showed mild hydrocephalus. Six (43%) of 14 tumors that either originated in or secondarily involved the cerebellopontine angle also extended into the ipsilateral Meckel's cave. CONCLUSION: On T1-, proton density-, and T2-weighted MR images intracranial epidermoid tumors usually showed heterogeneous signal intensity that was hyperintense to CSF. On all spin-echo pulse sequences epidermoid tumors with signal characteristics isointense to CSF were unusual. Hydrocephalus, even in the setting of marked displacement and compression of the brainstem, was not usually seen on MR imaging. Meckel's cave was often involved secondarily with epidermoid tumors that involved the cerebellopontine angle.
Adult↗
Patterns of hemorrhage with ruptured posterior inferior cerebellar artery aneurysms: CT findings in 44 cases.
OBJECTIVE: We intended to characterize the CT patterns of hemorrhage associated with ruptured posterior inferior cerebellar artery (PICA) aneurysms. MATERIALS AND METHODS: CT scans of 44 cases of angiographically confirmed ruptured saccular PICA aneurysms (4) aneurysms at the junction of the vertebral artery and the PICA and three distal PICA aneurysms) were retrospectively reviewed. All scans had been obtained within 2 days of the subarachnoid hemorrhage (SAH) (day 0 [less than 24 hr], 35 patients; day 1, eight patients; day 2, one patient). Presence or absence of hemorrhage in specific subarachnoid, intraventricular, and intraparenchymal locations was noted, as were the presence and degree of hydrocephalus. RESULTS: Posterior fossa SAH was present in 95% of cases. Isolated posterior fossa SAH was present in 30% of cases, but in no case was isolated supratentorial SAH present. Supratentorial SAH was present in 70% of cases. SAH involving the sylvian fissure or the interhemispheric region was present in 25% and 23% of cases, respectively. SAH along the convexity was present in 2% of cases. Intraventricular hemorrhage (IVH) with or without associated SAH was seen in 95% of cases, whereas isolated IVH was seen in 5% of cases. Hydrocephalus was present in 95% of cases and was moderate to marked in 70%. Both IVH and hydrocephalus were present in 93% of cases. CONCLUSION: Ruptured PICA aneurysms almost always coexist with hydrocephalus and IVH, as seen in 93% of cases, and almost never coexist with SAH along the convexity. The most common pattern of hemorrhage associated with such aneurysms includes IVH and posterior fossa hemorrhage. Extensive supratentorial SAH, in conjunction with posterior fossa SAH, is a common finding in patients with ruptured PICA aneurysms. SAH isolated to the posterior fossa is present in a sizeable minority of cases.
Aneurysm, Ruptured↗
Utilization of type I collagen gel, demineralized bone matrix, and bone morphogenetic protein-2 to enhance autologous bone lumbar spinal fusion.
Autologous bone grafts are currently considered "gold standard" material for achieving long-term spinal arthrodesis. The present study was performed to determine whether demineralized bone matrix (DBM), type I collagen gels, or bone morphogenetic protein-2 (BMP-2) can improve autologous bone spinal fusions. Using a unilateral decompression-contralateral fusion technique in dogs, each of these materials was added to an autologous bone graft. Volumetric analysis, histological analysis, and biomechanical testing were performed to assess the effectiveness of each material. The DBM had an inhibitory effect on solid bone fusion of the spine, whereas the type I collagen gels improved the bony interface between the graft and the host spine. The BMP-2 strongly enhanced the amount of bone deposition at the fusion site and increased the number of intervertebral levels that were solidly fused. This study strongly supports the use of BMP-2 as an additive to autologous bone grafts in spine stabilization.
Animals↗
Accuracy and precision of CT angiography in a model of carotid artery bifurcation stenosis.
PURPOSE: To determine optimal acquisition parameters and measurement techniques for CT angiography of the carotid bifurcation. METHODS: Anatomic phantoms were created in which the diameter of the carotid artery stenoses ranged from 15% to 95%. Initially, we compared the accuracy of stenosis determination obtained by using various values of section collimation and table pitch. Subsequently, applying the combination of collimation and pitch that yielded the greatest longitudinal coverage without degradation in accuracy, we compared the accuracy of measurements performed with various display algorithms, including axial, magnified axial, maximum intensity projection (MIP), and shaded surface display (SSD) images. Last, we determined the effect on accuracy of varying both window and level settings. The standard of reference for all measurements was considered to be caliper measurements made of the models at the time of their construction. RESULTS: CT angiography was highly accurate for determining the percentage of stenosis; the average difference between CT angiographic measurements and the standard of reference was less than 1% for all parameter combinations and measurement techniques. Precision varied among the measurement techniques. Magnified axial images provided more precise measurements than either the MIP or SSD images. Although there was a trend toward improved precision with the use of magnified versus unmagnified axial images and MIP versus SSD images, neither of these comparisons reached statistical significance. Systematic error was produced by changing the level setting from that halfway between the luminal density and vessel wall density. Random error was introduced by using window settings greater than zero. CONCLUSION: CT angiography was highly accurate and precise for determining percentage of stenosis. The highest precision was attained by using magnified axial images with the level halfway between luminal density and vessel wall density and with the window set to zero.
Carotid Arteries↗