The donut sign: a new angiographic sign for partially thrombosed aneurysms with flow-induced intraluminal thrombus.

Three patients are described with unruptured large partially thrombosed aneurysms with a peculiar donut-shaped remaining lumen. Observations suggest that the flow geometry of the aneurysm and parent vessels induces a preferential circular laminar flow inside the aneurysm followed by partial intraluminal thrombosis leaving a donut-shaped lumen to accommodate the circular flow. This flow mechanism of thrombus formation inside aneurysms is different from the more common repeated intramural dissections and hemorrhages that cause growth in most large and giant partially thrombosed aneurysms.

The quantification of glenoid bone loss in anterior shoulder instability; MR-arthro compared to 3D-CT.

OBJECTIVE: The purpose of this study is to investigate if magnetic resonance imaging with intra-articular contrast (MR-arthro) is as reliable as three-dimensionally reconstructed computed tomography imaging (3D-CT) in quantifying the glenoid bone loss in patients with anterior shoulder instability. MATERIALS AND METHODS: Thirty-five patients were included. Sagittal MR-arthro and 3D-CT images of the glenoid surface were obtained pre-operatively. Two observers measured these images twice with OsiriX software in a randomized and blinded way. The intraclass correlations (ICC) of the intra- and inter-observer reliability within one method and an additional Bland-Altman plot for calculating agreement between the two methods were obtained. RESULTS: The joint estimates of the intra-observer reliability, taking into account the data from both observer A and B, for 3D-CT and MR-arthro were good to excellent. The intra-observer reliability was 0.938 (95% CI: 0.879, 0.968) for 3D-CT and 0.799 (95% CI: 0.639, 0.837) for MR-arthro. The inter-observer reliability between the two observers within one method (3D-CT or MR-arthro) was moderate to good. 3D-CT: 0.724 (95% CI: 0.236, 0.886) and MR-arthro: 0.534 (95% CI: 0.128, 0.762). Comparing both the 3D-CT and MR-arthro method, a Bland-Altman plot showed satisfying differences with the majority of outcomes (89%) within 1 SD. CONCLUSIONS: Good to excellent intra- and moderate to good inter-observer correlations and a satisfying Bland-Altman plot when compared to 3D-CT show tendencies that MR-arthro is reliable and valid for measuring bony defects of the glenoid.