Wall Apposition Is a Key Factor for Aneurysm Occlusion after Flow Diversion: A Histologic Evaluation in 41 Rabbits.

BACKGROUND AND PURPOSE: Robust wall apposition for flow-diverter stents may be important for endothelialization. Using a large series of experimental aneurysms treated with the Pipeline Embolization Device, the objectives of this study were to 1) assess interobserver agreement for the evaluation of wall apposition on posttreatment DSA and evaluate its association with aneurysm occlusion, and 2) measure the relationship between wall apposition assessed with histology and aneurysm occlusion rate after treatment. MATERIALS AND METHODS: Saccular aneurysms were created in 41 rabbits and treated with the Pipeline Embolization Device. DSA was performed just after the deployment of the device and at follow-up. Three investigators independently graded wall apposition on posttreatment DSA as good or poor. A histopathologist blinded to the angiographic results graded the wall apposition on histologic samples. We examined the correlation between angiographic occlusion and wall apposition with histology and angiography. RESULTS: Wall apposition evaluated on histology was strongly associated with saccular aneurysm occlusion. Sensitivity and specificity of wall apposition to predict complete occlusion at follow-up were 76.9% and 84.0%, respectively, with an overall accuracy of 81.6%. In this experimental study, DSA was suboptimal to assess flow-diverter apposition, with moderate interobserver agreement and low accuracy. CONCLUSIONS: Good wall apposition is strongly associated with complete occlusion after flow-diverter therapy. In this study, DSA was suboptimal for assessing wall apposition of flow-diverter stents. These findings suggest that improved tools for assessing flow diverter-stent wall apposition are highly relevant.

Validity of the Meyer Scale for Assessment of Coiled Aneurysms and Aneurysm Recurrence.

BACKGROUND AND PURPOSE: Both the Meyer and Raymond scales are commonly used to report angiographic outcomes following coil embolization of intracranial aneurysms. The objectives of this study were the following: 1) to assess the interobserver agreement of the Meyer and Raymond scales, and 2) to evaluate and compare their performance in predicting major recurrence at follow-up. MATERIALS AND METHODS: A retrospective series of 120 coiled aneurysms was included. Four investigators independently graded DSA images immediately posttreatment and at follow-up according to the Meyer and Raymond scales. On follow-up DSA, readers also evaluated recurrence outcome. Interobserver agreement was assessed via the intraclass correlation coefficient. The ability of posttreatment Meyer and Raymond scales to predict major recurrence was modeled by using logistic regression and assessed by using receiver operating characteristic analysis. RESULTS: For the Meyer scale, interobserver intraclass correlation coefficients were 0.58 (95% CI, 0.46-0.68) on posttreatment and 0.78 (95% CI, 0.72-0.83) on follow-up evaluations. For the Raymond scale, interobserver intraclass correlation coefficients were 0.50 (95% CI, 0.39-0.61) and 0.69 (95% CI, 0.62-0.76), respectively, for posttreatment and follow-up. The areas under the curve for the receiver operating characteristic analyses regarding the performance to predict major recurrence at follow-up were 0.69 (95% CI, 0.60-0.79) for the Meyer and 0.70 (95% CI, 0.61-0.78) for the Raymond scale. CONCLUSIONS: The Meyer scale appears consistent and reliable with observer agreement as high or higher than that of the Raymond scale. Performance of both scales in predicting the risk of major recurrence at follow-up is adequate, with no statistical difference between the scales.

Protein phosphorylation in normal and neoplastic development. Cyclic AMP-dependent protein kinase activity in urethane-induced pulmonary tumours.

The cyclic AMP-dependent protein kinase specific activities of cytosol fractions from urethane-induced lung tumours and from normal mouse lung were determined. Both basal and cyclic AMP-stimulated activities in tumours were twofold higher than those of normal lung. Since neonatal and adult lung cytosols have identical kinase activities, the high activity in tumours appears to be a tumour-specific property.

Efficiency and loading characteristics of EPA's high-temperature quartz fiber filter media.

It was experimentally demonstrated that Gelman Type A and "Microquartz" filters are efficient collectors of nonvolatile particles at high temperatures. Submicron particles penetrated more than large particles, and most at the highest filtration velocity tested of 51 cm/sec. In all tests, however, aerosol penetration was never more than about 0.10%. Nonvolatile particles penetrated less with increasing temperature filter loading. Particles with vaporization points below the sampling temperature, including H2SO4, can vaporize, pass through the glass fiber filters, and then recondense when cooled below their dew points. Therefore, the definition of "particulate matter" must be based upon a prescribed temperature. Hot stack gases, sampled at different filter temperatures, should not necessarily be comparable. Particulate emission standards must involve a suitable reference temperature to allow proper enforcement. Filtration efficiencies calculated by theoretical equations change dramatically with small changes in assumed average filter fiber diameter and/or particle size (or size distribution) used in the calculations. Pinholes not visible to the naked eye do not appear to effect penetration of glass fiber filters enough to significantly alter stack sampling results. Effect of temperature on filtration of non-volatile particles simply resulted in an increasing collection of submicron particles with increasing temperature. The main problems encountered at elevated temperatures were vaporization of volatile particles and mechanical leakage of the filter holder.