Dynamic cine-CT angiography for the evaluation of the thoracic aorta; insight in dynamic changes with implications for thoracic endograft treatment.

OBJECTIVE: Thoracic aneurysm preoperative imaging is performed using static techniques without consideration of normal aortic dynamics. Improved understanding of the native aortic environment into which thoracic endografts are placed may aid in device selection. It is unclear what comprises normal thoracic aortic pulsatility. We studied these phenomena dynamically using ECG-gated 64-slice CTA. METHODS: Maximum diameter and area change per cardiac cycle was measured at surgically relevant anatomic thoracic landmarks in ten patients; 1.0 cm proximal and distal to the subclavian artery, 3.0 cm distal to the subclavian artery, and 3.0 cm proximal to the celiac trunk. Data was acquired using a novel ECG-gated dynamic 64-slice CT scanner during a single breath hold with a standard radiation dose and contrast load. Eight gated data sets, covering the cardiac cycle were reconstructed, perpendicular to the central lumen. RESULTS: There is impressive change in both maximum diameter and area in the thoracic aorta during the cardiac cycle. Mean maximum diameter changes of greater than 10% are observed in the typical sealing zones of commercially available endografts corresponding to diameter increases of up to 5mm. Aortic area increases by over 5% per cardiac cycle. CONCLUSIONS: ECG-gated dynamic CTA with standard radiation dose is feasible on a 64-slice scanner and provides insight into (patho) physiology of thoracic aortic conformational changes. Clinicians typically oversize thoracic endografts by 10%. With aortic pulsatility resulting in diameter changes of up to 17.8%, the potential exists for endograft undersizing, graft migration, intermittent type I endoleak, and poor patient outcome. Furthermore, aortic pulsatility is not evenly distributed, and non-circular stentgraft designs should be considered in the future since aortic distension in the aneurysm neck is not evenly distributed.

Validation of a Group Embedded Figures Test for young children.

This paper describes the development and concurrent validation of a group-administered measure of field-dependence/independence for early elementary children. Following the procedure used to validate the Children's Group Embedded Figures Test (Level 2, 9 to 11 yr.), a validation study of a group test for younger children was undertaken with a second-grade sample (N = 77). The test was reliable (alpha = .84) and significantly related to both the individually administered Children's Embedded Figures Test (r = .56) and Portable Rod-and-frame Test (r = .57). This measure, designated the Children's Group Embedded Figures Test--Level 1, provides a promising research instrument for assessing cognitive style of young children.

Eosinophilopoietin. A circulating low molecular weight peptide-like substance which stimulates the production of eosinophils in mice.

In earlier studies, methods were developed to raise specific antibodies in rabbits against purified suspensions of mouse or human eosinophils. On administration of antieosinophil serum (AES) to mice, the mature eosinophils in tissues, peripheral blood, and bone marrow were depleted, while the immature eosinophil pool in the bone marrow was observed to proliferate. The current investigations explore the generation of eosinophilopoietic factors during AES-induced eosinophilopenia. Mice received three injections of AES, one every other day. As the peripheral eosinophil counts started to recover after the last AES injection, the serum was collected and transferred to normal animals. Within 2 days the recipients showed an increase in peripheral blood as well as in bone marrow eosinophils. The rise in bone marrow eosinophils was due to newly formed cells as evidenced by increased uptake of [(3)H]thymidine. The generation of eosinophilopoietic activity was specifically related to depletion of eosinophils but not neutrophils. The eosinophilopoietic activity was: (a) dependent on the volume of serum transferred, (b) lost on dialysis, and (c) largely heat labile. The activity eluted as a low molecular weight substance on G-25 Sephadex and was digested by pronase but not by trypsin. Active fractions collected from G-25 columns were not chemotactic for the eosinophils in vitro. Thus, specific depletion of mature eosinophils generates a low molecular weight peptide which stimulates eosinophilopoiesis in vivo. It is suggested that this substance be named eosinophilopoietin.