Quantifying irregular pulsation of intracranial aneurysms using 4D-CTA

Recent studies have suggested that irregular pulsation of intracranial aneurysm during the cardiac cycle may be potentially associated with aneurysm rupture risk. However, there is a lack of quantification method for irregular pulsations. This study aims to quantify irregular pulsations by the displacement and strain distribution of the intracranial aneurysm surface during the cardiac cycle using four-dimensional CT angiographic image data. Four-dimensional CT angiography was performed in 8 patients. The image data of a cardiac cycle was divided into approximately 20 phases, and irregular pulsations were detected in four intracranial aneurysms by visual observation, and then the displacement and strain of the intracranial aneurysm was quantified using coherent point drift and finite element method. The displacement and strain were compared between aneurysms with irregular and normal pulsations in two different ways (total and stepwise). The stepwise first principal strain was significantly higher in aneurysms with irregular than normal pulsations (0.20 ± 0.01 vs 0.16 ± 0.02, p = 0.033). It was found that the irregular pulsations in intracranial aneurysms usually occur during the consecutive ascending or descending phase of volume changes during the cardiac cycle. In addition, no statistically significant difference was found in the aneurysm volume changes over the cardiac cycle between the two groups. Our method can successfully quantify the displacement and strain changes in the intracranial aneurysm during the cardiac cycle, which may be proven to be a useful tool to quantify intracranial aneurysm deformability and aid in aneurysm rupture risk assessment

Development of a semi-automated technique for reconstructing vertebral anatomy using clinical MRI

Three dimensional (3D) reconstructions of the spinal vertebrae have been utilised to create computational models for assessing spinal biomechanics and to permit clinicians to interrogate a virtual representation of the spinal anatomy for patients with complicated or unusual bone pathologies/deformities. These reconstructions have primarily been developed using computed tomography (CT) scanning. However, the radiation exposure associated with the use of CT scans to assess anatomical features, particularly in young patients, precludes the routine use of this imaging modality in research. An accurate, semi-automatic technique was developed to segment and reconstruct lumbar vertebral anatomy using MRI data. This technique resulted in reconstructed vertebral anatomy with clearly defined vertebral bodies as well as posterior elements, something hereto not achieved in prior studies

Reconstructing vertebral anatomy using clinical MRI Scans

Three dimensional (3D) reconstructions of the spinal vertebrae have been utilised to create computational models for assessing spinal biomechanics. Direct segmentation of bony anatomy from magnetic resonance imaging (MRI) is not straightforward. In light of the non-irradiating advantages offered by this imaging modality for routine scanning of patients, the current project sought to develop an efficient, accurate and semi-automatic method for reconstructing spinal vertebra anatomy from clinical MRI. An accurate, semi-automated technique was developed to segment and reconstruct lumbar vertebral anatomy using MRI data. This technique resulted in reconstructed vertebral anatomy with clearly defined vertebral bodies as well as posterior elements, something hereto not achieved in prior studies. The technique is sensitive to the quality of bone imaged and geometric accuracy may be reduced for aged bone

Vulnerability of inter-tropical littoral areas

The Terminos Lagoon is a 2000-km(2) wide coastal lagoon linked to the largest river catchment in Mesoamerica. Economic development, together with its ecological importance, led the Mexican government to pronounce the Terminos Lagoon and its surrounding wetlands as a Federal protected area for flora and fauna in 1994. It is characterized by small temperature fluctuations, but with two distinct seasons (wet and dry) that control the biological, geochemical, and physical processes and components. This paper presents a review of the available information about the Terminos Lagoon. The review shows that the diversity of benthic communities is structured by the balance between marine and riverine inputs and that this structuration strongly influences the benthic metabolism and its coupling with the biogeochemistry of the water column. The paper also presents many specific drivers and recommendations for a long-term environmental survey strategy in the context of the expected Global Change in the Central American region