Cellular mechanisms of aneurysm occlusion after treatment with a flow diverter.

PURPOSE: To characterize the progression of healing across aneurysm necks following treatment with a flow diverter in a rabbit aneurysm model. MATERIALS AND METHODS: With institutional animal care and use committee approval, saccular aneurysms were created in 20 rabbits and treated with flow diverters. On days 1, 3, and 7 and weeks 4 and 8 after implantation, the aneurysm and the device-implanted vessel were harvested. En face staining of the gross specimen was performed for endothelial cells, endothelial progenitor cells, smooth muscle cells, and inflammatory cells. RESULTS: The parent artery segments covered by the flow diverters were completely devoid of endothelial cells at 1 and 3 days but had completely reendothelialized by 7 days. At all time points, the struts along the patent portions of the aneurysm necks harbored scattered tissue islands composed exclusively of inflammatory cells. At 4 and 8 weeks, all samples contiguous with the tissue along the parent arteries had translucent tissue present along the occluded segments of the aneurysm neck. The vast majority of endothelial cells were contiguous with the parent artery and had smooth muscle cells underlying them. Endothelial progenitor cells were not observed along the neck of any aneurysm. Aneurysm closure was noted only when complete or nearly complete endothelialization over the device struts was present. CONCLUSION: The initial event following flow diversion treatment is adherence of clusters of inflammatory cells across the aneurysm neck. Endothelialization is relatively delayed and derived exclusively from cells in the adjacent parent artery.

Mesenteric Amyloidosis: Radiologic Imaging with Pathologic Correlation.

Amyloidosis is a rare disease that is characterized by abnormal deposition of amyloid proteins in tissues, resulting in local, or systemic disease. When localized, it can present as an amyloidoma. We report a case of mesenteric amyloidosis in an 80-year-old male who was found to have an incidental mesenteric mass that was biopsy-proven to represent non-light chain amyloid tissue.

Treatment of superior vena cava syndrome with kissing brachiocephalic stents and exchange of pacemaker leads.

Superior vena cava syndrome is an uncommon but challenging complication of patients undergoing hemodialysis through upper extremity access as well as of patients with indwelling pacemakers. This case report and Video demonstrate the multidisciplinary management of a complex patient with hemodialysis access and indwelling pacemaker for whom multiple attempts at balloon angioplasty for superior vena cava syndrome failed. A joint procedure between vascular surgery and cardiac electrophysiology teams was performed to exchange the pacemaker leads and to place bilateral kissing stents in the brachiocephalic veins. The patient tolerated the procedure well and had no recurrence of symptoms.

Characterizing patterns of endothelialization following coil embolization: a whole-mount, dual immunostaining approach.

BACKGROUND: The extent, rate, and source of endothelialization following coil embolization of saccular aneurysms remains poorly understood. We performed a whole tissue mount, dual immunohistochemical analysis of experimental aneurysms to characterize the state of endothelialization over time after platinum coil embolization. METHOD AND MATERIAL: Elastase-induced rabbit aneurysms were created and treated with bare platinum coils. Samples were harvested at 4 and 8 weeks (n=6 for each). En face whole tissue mount staining with antibodies to CD31 and α-smooth muscle actin was used to identify endothelial cells and smooth muscle cells, respectively. Sytox green stain was used to demonstrate nuclear morphology for identification of inflammatory cells. The extent of endothelialization was measured in relation to the aneurysm neck-parent artery interface. RESULTS: At 4 weeks after coil embolization, very localized membranous tissue and neoendothelial cells were detected on the coil loops immediately adjacent to the parent artery-neck interface, but the remainder of the coil loops remained devoid of endothelial cells. At 8 weeks neoendothelial cells were more confluent over the coils than at 4 weeks, and extended up to 900 µm from the parent artery-neck interface. However, the surfaces of the coils farther away than this region harbored no endothelial cells. Scattered inflammatory cells, including neutrophils and monocytes, were seen on the coil surface at the neck central area, where the coil surface was bare at the 4 and 8 weeks' follow-up. CONCLUSIONS: Platinum coil embolization supports gradual but limited endothelialization, where endothelial cells migrate directly from the adjacent parent artery.

Elastase-induced intracranial dolichoectasia model in mice.

BACKGROUND: Intracranial dolichoectasia is associated with high morbidity, and its pathophysiology remains poorly understood. OBJECTIVE: To develop a technique for the creation of a murine model of dolichoectasia. METHODS: C57/BL6 mice were injected with 0 milliunit (mu) (control, n = 5), 15 mu (n = 7), 25 mu (n = 10), 35 mu (n = 10), and 55 mu (n = 6) of elastase in the cisterna magna. Fourteen days after injection, the vasculature of the brain was perfused with MicroFil polymerizing compound. Tortuosity index and the percentage increase in arterial diameter were calculated for the basilar artery, posterior communicating arteries, and the A1 segment of the anterior cerebral arteries. Tortuosity index >10 combined with 25% increase in diameter were used to indicate success in achieving dolichoectasia. RESULTS: The mortality rate was 28%, 30%, 80%, and 83% in the 15, 25, 35, and 55 mu groups, respectively. As the 35 and 55 mu groups experienced unacceptable mortality rates, they were excluded from further analysis. The tortuosity index and percent increase arterial diameter of the 15 and 25 mu groups for the left anterior cerebral arteries, right anterior cerebral arteries, left posterior communicating arteries, right posterior communicating arteries, and basilar artery were significantly higher (TI >10 and arterial diameter >25%) than in the control. There was no significant difference in tortuosity index or artery diameter between the 15 and 25 mu groups for any of the 5 artery segments. CONCLUSION: Elastase injection through the cisterna magna can induce intracranial dolichoectasia in mice. Fifteen to 25 mu of elastase is an appropriate dose to use with acceptable mortality.

Healing of saccular aneurysms following platinum coil embolization: lack of improved efficacy with vitamin C supplementation.

BACKGROUND AND PURPOSE: To test the hypothesis that systemic administration of vitamin C, through its action of stimulating collagen synthesis and crosslinking, would decrease the recurrence and improve the occlusion of experimental aneurysms treated with platinum coils. METHODS: Experimental aneurysms were created in female rabbits and were embolized with platinum coils (>30% packing density). The animals were divided into three groups: group 1 (n=6) rabbits served as controls, group 2 (n=5) rabbits were fed with a vitamin C supplemented feed and group 3 (n=8) rabbits were medicated with vitamin C pills. Digital subtraction angiography was used to evaluate stability after embolization. Subjects were euthanized at 12 weeks after coil implantation, and serum vitamin C levels were then measured. Histological samples were examined with a grading system (range 0-12) based on the neck and dome features. Masson Trichrome staining was used to evaluate collagen deposition. Parametric data were analyzed with one way analysis of variance and non-parametric data were examined using a Kruskal-Wallis test. RESULTS: There were no significant differences between groups in mean aneurysm size. Mean serum vitamin C concentration was significantly higher in group 3 and group 2 compared with group 1, while vitamin C levels between group 2 and group 3 were statistically comparable. Coil compaction was noted in one of six subjects in group 1 and in three of eight subjects in group 3. All of the remaining aneurysms in the test and control groups showed stable occlusion. There were no significant differences in histological scores or collagen deposition among groups. CONCLUSIONS: Vitamin C supplementation following platinum coil embolization does not demonstrate improvement of long term occlusion rates of aneurysms.

'Initial Clinical Experience' articles are poorly cited and negatively affect the impact factor of the publishing journal: a review.

OBJECTIVES: The phrase 'Initial Clinical Experience' in a manuscript's title implies that the described technique offers promise of future clinical relevance. We assessed, using rates of subsequent citations, the actual academic relevance of such articles in comparison to articles not containing the phrase. DESIGN: We searched ISI database for articles that included the studied phrase in their titles between 1975 and 2009 and grouped the results by the related medical specialty. We excluded articles from journals with no available impact factor. For each identified article, we extracted number of included patients, citations/year, the average impact factor of the publishing journal over the last five years and the proportion of articles published in the same journal that garnered zero subsequent citations. SETTING: Retrospective review of a scientific database. PARTICIPANTS: None. MAIN OUTCOME MEASURES: Citation rate. RESULTS: Among a total of 982,127 articles published in 186 journals representing eight major publishing medical specialties, 531 (0.05%) were Initial Clinical Experience articles. Thirty percent of Initial Clinical Experience articles were never cited compared with 7% of the overall article volume (p < 0.0001). Citations/year for Initial Clinical Experience articles were significantly lower than the median impact factor (p < 0.0001). There was no correlation between citations and number of patients described in the Initial Clinical Experience articles (p = 0.61). CONCLUSIONS: Initial Clinical Experience articles are cited less frequently than the average, especially in Cardiovascular, Radiology and Ophthalmology journals.

Pre-residency publication rate strongly predicts future academic radiology potential.

RATIONALE AND OBJECTIVES: Radiology resident selection committees often favor candidates with strong academic potential. The aim of this study was to determine if preresidency academic productivity of current radiologists was predictive of subsequent of future academic performance. MATERIALS AND METHODS: The academic productivity of all radiology residents trained between 1975 and 2005 at the authors' institution was assessed through identification of their publication histories, National Institutes of Health funding statuses, and Hirsch indexes (h-indexes). These metrics were correlated with numbers of publications generated prior to beginning radiology residency and grouped accordingly (group 0, none prior to residency; group 1, one publication; and group 2, more than one publication). Academic productivity metrics of the different groups were compared using one-way analysis of variance and χ(2) analysis. Spearman's ρ coefficient was used to evaluate correlations between the number of preresidency publications and subsequent productivity. RESULTS: A cohort of 269 residents was included in this study. Group 0 comprised 182 of the 269 residents (68%), while groups 1 and 2 comprised 27 (10%) and 60 (22%) residents, respectively. Rates of subsequent publication, mean h-index, and National Institutes of Health funding statuses were significantly higher in group 2 compared to both groups 0 and 1 (P < .0001 for each metric). Preresidency publication volume was significantly correlated with future publication performance (ρ = 0.3977, P < .0001), mean h-index (ρ = 0.3086, P < .0001), and National Institutes of Health funding status (ρ = 0.4916, P < .0001). CONCLUSIONS: Radiology residency candidates with multiple publications are more likely to achieve future academic success compared to candidates with one or zero publications.

Is the h-index predictive of greater NIH funding success among academic radiologists?

RATIONALE AND OBJECTIVES: Despite rapid adoption of the Hirsch index (h-index) as a measure of academic success, the correlations between the h-index and other metrics of productivity remain poorly understood. The aims of this study were to determine whether h-indices were associated with greater National Institutes of Health (NIH) funding success among academic radiologists. MATERIALS AND METHODS: Using the Scopus database, h-indices were calculated for a random sample of academic radiologists with the rank of professor. Using the NIH tool Research Portfolio Online Reporting Tools Expenditures and Reports, we determined the number, classification, and total years of NIH grant funding as principal investigator for each radiologist. Differences in h-index, sorted by funding status, were determined using Wilcoxon's tests. Associations between h-index and funding status were determined using logistic regression. Significant correlations between h-index and grant metrics were determined using Spearman's ρ. RESULTS: Among 210 professors of radiology, 48 (23%) secured at least one NIH grant. The mean h-index was significantly higher among individuals who secured at least one NIH grant (19.1) compared to those who did not (10.4) (P < .0001). Professors with h-indices < 10 compared to those with h-indices > 10 were significantly less likely to receive NIH funding (odds ratio, 0.07; P = .0321). However, h-indices > 10 were not significantly predictive of greater funding. No significant relationships were observed between h-index and the number of grant awards, years of prior funding, the amounts of grant awards, or grant classification. CONCLUSION: Having obtained at least one NIH grant was associated with a higher h-index, yet multiple or large grants, such as those for program projects, were not predictive of higher h-indices.