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Functional measurements of the left atrium (LA) in atrial fibrillation (AF) patients is limited to a single CINE slice midway through the LA. Nonetheless, a full 3D characterization of atrial functional measurements would provide more insights into LA function. But this improved modeling capacity comes at a price of requiring LA segmentation of each 3D time point,a time-consuming and expensive task that requires anatomy-specific expertise.We propose an efficient pipeline which requires ground truth segmentation of a single (or limited) CINE time point to accurately propagate it throughout the sequence. This method significantly saves human effort and enable better characterization of LA anatomy. From a gated cardiac CINE MRI sequence we select a single CINE time point with ground truth segmentation, and assuming cyclic motion, we register other images corresponding to all time points using diffeomorphic registration in ANTs. The diffeomorphic registration fields allow us to map a given anatomical shape (segmentation) to each CINE time point, facilitating the construction of a 4D shape model.

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Objective This study compares the utility of palpation-based and ultrasound-guided teaching techniques for subclavian central venous access using formalin-embalmed cadavers. Methods The subclavian veins of 20 formalin-embalmed cadavers were imaged with ultrasound to evaluate vein patency and sonographic clarity prior to venous access. Twenty-three first-year medical students were trained to access the subclavian vein using palpation-based techniques. Training involved ten minutes of didactic orientation and ten minutes of hands-on practical instruction using cadavers. Participant confidence was measured using a 10-point Likert scale on pre- and post-training questionnaires. Objective skills testing for each participant included quantifying the number of skin punctures and recording the time elapsed from skin puncture to fluid flashback into the syringe. Results Participant confidence significantly increased following training in both ultrasound and palpation training groups across all questionnaire items (p < 0.0001). The ultrasound group had less skin punctures (p < 0.001) and less failures (1) than the palpation group (6). Participants in the ultrasound group were more confident than those in the palpation group in their ability to locate the vein and select the optimal site for needle access (p < 0.001). Conclusions Formalin-embalmed cadavers provide a safe and stress-free environment in which to learn subclavian vein access. This method is effective for instructing students to use both palpation and ultrasound-based techniques. Utilizing ultrasound equipment and formalin-embalmed cadavers which are readily available in most medical institutions significantly increases trainee confidence, an essential factor in physician performance that may lead to fewer complications. However, participants also became confident in the palpation-based venous access technique, which would prove useful in cases when ultrasound is unavailable or too time-consuming. Introducing this type of hands-on practice to students early in their medical education may provide them the opportunity to administer their first live-patient clinical procedure with increased confidence in their procedural skillsets.