Strengths and Weaknesses of Non-enhanced and Contrast-enhanced Cadaver Computed Tomography Scans in the Teaching of Gross Anatomy in an Integrated Curriculum

Perspective or Spectacle? Teaching thoracic aortic anatomy in a mixed reality assisted educational approach- a two-armed randomized pilot study

PURPOSE

Anatomical understanding is an important basis for medical teaching, especially in a surgical context. The interpretation of complex vascular structures via two-dimensional visualization can yet be difficult, particularly for students. The objective of this study was to investigate the feasibility of an MxR-assisted educational approach in vascular surgery undergraduate education, comparing an MxR-based teaching-intervention with CT-based material for learning and understanding the vascular morphology of the thoracic aorta.

METHODS

In a prospective randomized controlled trial learning success and diagnostic skills following an MxR- vs. a CT-based intervention was investigated in 120 thoracic aortic visualizations. Secondary outcomes were motivation, system-usability as well as workload/satisfaction. Motivational factors and training-experience were also assessed. Twelve students (7 females; mean age: 23 years) were randomized into two groups undergoing educational intervention with MxR or CT.

RESULTS

Evaluation of learning success showed a mean improvement of 1.17 points (max.score: 10; 95%CI: 0.36-1.97). The MxR-group has improved by a mean of 1.33 [95% CI: 0.16-2.51], against 1.0 points [95% CI: -0.71- 2.71] in the CT-group. Regarding diagnostic skills, both groups performed equally (CT-group: 58.25 ± 7.86 vs. MxR-group:58.5 ± 6.60; max. score 92.0). 11/12 participants were convinced that MxR facilitated learning of vascular morphologies. The usability of the MxR-system was rated positively, and the perceived workload was low.

CONCLUSION

MxR-systems can be a valuable addition to vascular surgery education. Further evaluation of the technology in larger teaching situations are required. Especially regarding the acquisition of practical skills, the use of MxR-systems offers interesting application possibilities in surgical education.

Efficacy of postmortem CT and tissue sampling in establishing the cause of death in clinical practice: a prospective observational study

AIMS

The aim of this study is to evaluate whether agreement with autopsy-determined cause of death (COD) increases by use of postmortem CT (PMCT) or PMCT in combination with postmortem sampling (PMS), when compared with clinical assessment only.

METHODS

This prospective observational study included deceased patients from the intensive care unit and internal medicine wards between October 2013 and August 2017. The primary outcome was percentage agreement on COD between the reference standard (autopsy) and the alternative postmortem examinations (clinical assessment vs PMCT or PMCT+PMS). In addition, the COD of patient groups with and without conventional autopsy were compared with respect to involved organ systems and pathologies.

RESULTS

Of 730 eligible cases, 144 could be included for analysis: 63 underwent PCMT without autopsy and 81 underwent both PMCT and autopsy. Agreement with autopsy-determined COD was significantly higher for both PMCT with PMS (42/57, 74%), and PMCT alone (53/81, 65%) than for clinical assessment (40/81, 51%; p=0.007 and p=0.03, respectively). The difference in agreement between PMCT with PMS and PMCT alone was not significant (p=0.13). The group with autopsy had a significantly higher prevalence of circulatory system involvement and perfusion disorders, and a lower prevalence of pulmonary system involvement.

CONCLUSION

PMCT and PMS confer additional diagnostic value in establishing the COD. Shortcomings in detecting vascular occlusions and perfusion disorders and susceptibility to pulmonary postmortem changes could in future be improved by additional techniques. Both PMCT and PMS are feasible in clinical practice and an alternative when autopsy cannot be performed.

The role of anatomical context in soft-tissue multi-organ segmentation of cadaveric non-contrast-enhanced whole body CT

BACKGROUND

Cadaveric computed tomography (CT) image segmentation is a difficult task to solve, especially when applied to whole-body image volumes. Traditional algorithms require preprocessing using registration, or highly conserved organ morphologies. These requirements cannot be fulfilled by cadaveric specimens, so deep learning must be used to overcome this limitation. Further, the widespread use of 2D algorithms for volumetric data ignores the role of anatomical context. The use of 3D spatial context for volumetric segmentation of CT scans as well as the anatomical context required to optimize the segmentation has not been adequately explored.

PURPOSE

To determine whether 2D slice-by-slice UNet algorithms or 3D volumetric UNet (VNet) algorithms provide a more effective method for segmenting 3D volumes, and to what extent anatomical context plays in the segmentation of soft-tissue organs in cadaveric, noncontrast-enhanced (NCE) CT.

METHODS

We tested five CT segmentation algorithms: 2D UNets with and without 3D data augmentation (3D rotations) as well as VNets with three levels of anatomical context (implemented via image downsampling at 1X, 2X, and 3X) for their performance via 3D Dice coefficients, and Hausdorff distance calculations. The classifiers were trained to segment the kidneys and liver and the performance was evaluated using Dice coefficient and Hausdorff distance on the segmentation versus the ground truth annotation.

RESULTS

Our results demonstrate that VNet algorithms perform significantly better (p < 0.05 $p<0.05$ ) than 2D models. Among the VNet classifiers, those that use some level of image downsampling outperform (as calculated through Dice coefficients) the VNet without downsampling. Additionally, the optimal amount of downsampling depends on the target organ.

CONCLUSIONS

Anatomical context is an important component of soft-tissue, multi-organ segmentation in cadaveric, NCE CT imaging of the whole body. Different amounts of anatomical contexts are optimal depending on the size, position, and surrounding tissue of the organ.

Integrated anatomical practice combining cadaver dissection and matched cadaver CT data processing and analysis

PURPOSE

With the increasing significance of diagnostic imaging in clinical practice, long-term anatomical education and training is required to ensure that students can reliably distinguish anatomical structures and interpret images. To improve students' motivation and prospects for learning imaging anatomy, we developed an integrated anatomical practice program combining cadaveric dissection with cadaver CT data processing and analysis during undergraduate students' dissection courses.

METHODS

Workstations imported with post-mortem CT data of dissected cadavers and various forms of clinical CT/MRI data were set in the dissection room. Medical students had free access to the imaging data during cadaver dissection, and they were challenged to process and analyze the data for submission of voluntary imaging reports on their topics of interest. Finally, we surveyed the integrated anatomical education of 481 medical students.

RESULTS

The positive response rate to the integrated anatomical practice was 74.9%, and 79.4% of the students answered that this form of practice offered a suitable introduction to anatomical imaging. The usefulness of this approach in understanding the 2- to 3D arrangement of the human body and enhancing interest in anatomy was also confirmed. The submission rate of voluntary imaging reports also increased annually and is currently 97.4%.

CONCLUSION

Our integrated anatomical practice only allowed students to actively browse CT images and facilitated imaging processing and analysis of their region of interest. This practice may improve students' long-term ability to analyze images and deepen their understanding. A competitive imaging contest may help improve students' motivation when they begin learning imaging anatomy.