Development of personalised 3D printed abdominal aortic aneurysm models with use of different materials for clinical education and training in interventional radiology

Background 3D printing is increasingly used in medical applications with studies proving its clinical value in surgical planning and simulation of complex surgical procedures. Use of patientspecific or personalised 3D printed models could serve as a useful tool in clinical education and training by practicing interventional procedures on the realistic physical models. Aims This study aimed to develop 3D printed personalised abdominal aortic aneurysm (AAA) models using different materials for the purpose of simulating interventional radiology procedure when performing endovascular aneurysm repair. Methods Anonymized Computed Tomography (CT) images of a sample case with an intrarenal AAA were selected to generate 3D volume data comprising AAA and arterial branches covering from celiac axis to common iliac arteries. The 3D segmented AAA model was printed with six different materials including resin, high impact polystyrene (HIPS), polyethylene terephthalate glycol (PETG), polylactic acid (PLA), polymethacrylate (PMMA), and thermoplastic polyurethane (TPU). The 3D printed models were scanned on a 192-slice CT scanner with and without use of contrast medium. Model accuracy in terms of AAA length and maximal transverse diameter was measured on original CT images and compared with that from these 3D printed models. Results The AAA models were successfully printed with these six different materials. 3D printed AAA models accurately replicated aortic aneurysm dimensions with mean differences less than 0.5 mm between measurements from original CT images and 3D printed models. Conclusion This study shows the feasibility of printing personalised AAA models with different materials with high accuracy of replicating aortic aneurysm. The 3D printed personalised models will be used to train interventional radiology trainees to develop their practical skills on performing endovascular aneurysm repair procedures

Clinical application of three-dimensional printed models in preoperative planning of pancoast tumour resection

BackgroundThe resection of pancoast tumours is a highly challenging procedure for cardiothoracic surgeons.  A patient-specific 3D printed model of the tumour may be useful as an adjunct to standard preoperative planning procedures.AimsThis study aims to assess the clinical value of a 3D printed pancoast tumour model as a preoperative planning tool.MethodsTwo anonymised cases of pancoast tumours were obtained and one was chosen to be 3D printed. The model was presented to two cardiothoracic surgeons with more than 10 years of experience. Interview and questionnaire sessions were conducted to sought expert opinions about the clinical value of the model as a preoperative planning tool. ResultsThe participants agreed that the 3D printed model provides an accurate representation of the exact location of the tumour in relation to surrounding structures. The hand-held model also offers a tactile approach to preoperative planning, facilitating the planning of ports placement. The model is also potentially useful in team communication and patient education, leading to improved surgical outcomes. ConclusionThis study has demonstrated the clinical value of a patient-specific 3D printed model of pancoast tumour in preoperative planning. Apart from enhancing the surgeons’ understanding of the anatomical location of the tumour, the model is also easily manipulated.  Future research could investigate the impact of 3D printed model on short to mid-term clinical outcomes

Development of a Tissue Equivalent Gelatine Phantom for Accuracy Verification of Tissue Elasticity Measurement Using Shear Wave Elastography Ultrasound

Background Shearwave elastography ultrasound (SWE) has been increasing used in the recent decade to quantify tissue stiffness and viscoelastic properties correlate to a disease condition. Aims This study aimed to develop a low cost and reproducible gelatine phantom to verify the accuracy of tissue elasticity measurement using shear wave elastography (SWE). The effect of lesion’s size, stiffness and depth from the surface on the tissue elasticity measurement were also investigated. Methods A breast tissue-equivalent phantom embedded with spherical inclusions of different sizes, stiffness and depth from surface was constructed using gelatine. The elasticity of the spherical inclusions was determined using a commercial SWE system and compared to the elasticity determined using a high precision electromechanical microtester (gold standard for elasticity measurements). Results Statistically significant difference (p < 0.05) was found between the elasticity measured using SWE and electromechanical microtester, whereby the SWE overestimated the tissue elasticity by a mean value of 22.8 ± 15.0 kPa. The size and depth of the spherical inclusions have not imposed any effect on the elasticity measured by SWE, but the depth of shear wave detection was found limited to 8 cm from the surface. Conclusion The gelatine phantom constructed in this study could be used to verify the accuracy of the elasticity measured using SWE. The tissue elasticity measured by the SWE appeared to be overestimated compared to the gold standard. Further research would need to be carried out to determine the offset from the SWE measurement and to account for these differences

Computer aided diagnosis of coronary artery disease, myocardial infarction and carotid atherosclerosis using ultrasound images: a review

The diagnosis of Coronary Artery Disease (CAD), Myocardial Infarction (MI) and carotid atherosclerosis is of paramount importance, as these cardiovascular diseases may cause medical complications and large number of death. Ultrasound (US) is a widely used imaging modality, as it captures moving images and image features correlate well with results obtained from other imaging methods. Furthermore, US does not use ionizing radiation and it is economical when compared to other imaging modalities. However, reading US images takes time and the relationship between image and tissue composition is complex. Therefore, the diagnostic accuracy depends on both time taken to read the images and experience of the screening practitioner. Computer support tools can reduce the inter-operator variability with lower subject specific expertise, when appropriate processing methods are used. In the current review, we analysed automatic detection methods for the diagnosis of CAD, MI and carotid atherosclerosis based on thoracic and Intravascular Ultrasound (IVUS). We found that IVUS is more often used than thoracic US for CAD. But for MI and carotid atherosclerosis IVUS is still in the experimental stage. Furthermore, thoracic US is more often used than IVUS for computer aided diagnosis systems

The trans-ancestral genomic architecture of glycemic traits

Glycemic traits are used to diagnose and monitor type 2 diabetes and cardiometabolic health. To date, most genetic studies of glycemic traits have focused on individuals of European ancestry. Here we aggregated genome-wide association studies comprising up to 281,416 individuals without diabetes (30% non-European ancestry) for whom fasting glucose, 2-h glucose after an oral glucose challenge, glycated hemoglobin and fasting insulin data were available. Trans-ancestry and single-ancestry meta-analyses identified 242 loci (99 novel; P < 5 x 10(-8)), 80% of which had no significant evidence of between-ancestry heterogeneity. Analyses restricted to individuals of European ancestry with equivalent sample size would have led to 24 fewer new loci. Compared with single-ancestry analyses, equivalent-sized trans-ancestry fine-mapping reduced the number of estimated variants in 99% credible sets by a median of 37.5%. Genomic-feature, gene-expression and gene-set analyses revealed distinct biological signatures for each trait, highlighting different underlying biological pathways. Our results increase our understanding of diabetes pathophysiology by using trans-ancestry studies for improved power and resolution. A trans-ancestry meta-analysis of GWAS of glycemic traits in up to 281,416 individuals identifies 99 novel loci, of which one quarter was found due to the multi-ancestry approach, which also improves fine-mapping of credible variant sets.Peer reviewe

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Patient-Specific 3D-Printed Low-Cost Models in Medical Education and Clinical Practice

3D printing has been increasingly used for medical applications with studies reporting its value, ranging from medical education to pre-surgical planning and simulation, assisting doctor–patient communication or communication with clinicians, and the development of optimal computed tomography (CT) imaging protocols. This article presents our experience of utilising a 3D-printing facility to print a range of patient-specific low-cost models for medical applications. These models include personalized models in cardiovascular disease (from congenital heart disease to aortic aneurysm, aortic dissection and coronary artery disease) and tumours (lung cancer, pancreatic cancer and biliary disease) based on CT data. Furthermore, we designed and developed novel 3D-printed models, including a 3D-printed breast model for the simulation of breast cancer magnetic resonance imaging (MRI), and calcified coronary plaques for the simulation of extensive calcifications in the coronary arteries. Most of these 3D-printed models were scanned with CT (except for the breast model which was scanned using MRI) for investigation of their educational and clinical value, with promising results achieved. The models were confirmed to be highly accurate in replicating both anatomy and pathology in different body regions with affordable costs. Our experience of producing low-cost and affordable 3D-printed models highlights the feasibility of utilizing 3D-printing technology in medical education and clinical practice

Problems and solutions in medical physics: nuclear medicine physics

xxiii, 139 p. ; 23 cm

Problems and solutions in medical physics : volume 2 : nuclear medicine physics

xxiii, 139 p. ; 23 cm