Variety Of Anatomical Structures Research Articles

Repeatability of MRI for radiotherapy planning for pelvic, brain, and head and neck malignancies

Objectives: The objective of this study was to assess the repeatability of MRI for the purpose of radiotherapy treatment planning by considering the difference in registering MRI to MRI compared to registering CT and MRI.Methods: Fifty patients undergoing radiotherapy planning for gynaecological, prostate, rectal, head and neck and CNS malignancies had a planning CT followed by two T2-weighted MRIs. Anatomical landmarks were contoured on each dataset and the images were rigidly registered. Centre of Mass (COM), Dice Similarity Coefficient (DSC), and Mean Distance to Agreement (MDA) were calculated to assess structure volume and position comparing CT-MRI and MRI-MRI.Results: DSC and MDA demonstrated more consistency in delineated volumes for MRI-MRI than for the CT-MRI comparison. The median DSC values were ≥0.8 for 15 of 46 contoured structures for the CT-MRI comparison and 21 of 23 structures for the MRI-MRI comparison. MDA values were ≤1 mm for 11 of 46 structures for the CT-MRI comparison and 18 of 23 structures for the MRI-MRI comparisons. COM were also more consistent between MRI-MRI than between CT-MRI.Conclusion: There was less variability of anatomical structures between repeated MRIs than registered CT and MRI datasets, demonstrating consistency of MRI for volume delineation in radiotherapy planning.

MobileUNet-FPN: A Semantic Segmentation Model for Fetal Ultrasound Four-Chamber Segmentation in Edge Computing Environments.

The apical four-chamber (A4C) view in fetal echocardiography is a prenatal examination widely used for the early diagnosis of congenital heart disease (CHD). Accurate segmentation of A4C key anatomical structures is the basis for automatic measurement of growth parameters and necessary disease diagnosis. However, due to the ultrasound imaging arising from artefacts and scattered noise, the variability of anatomical structures in different gestational weeks, and the discontinuity of anatomical structure boundaries, accurately segmenting the fetal heart organ in the A4C view is a very challenging task. To this end, we propose to combine an explicit Feature Pyramid Network (FPN), MobileNet and UNet, i.e., MobileUNet-FPN, for the segmentation of 13 key heart structures. To our knowledge, this is the first AI-based method that can segment so many anatomical structures in fetal A4C view. We split the MobileNet backbone network into four stages and use the features of these four phases as the encoder and the upsampling operation as the decoder. We build an explicit FPN network to enhance multi-scale semantic information and ultimately generate segmentation masks of key anatomical structures. In addition, we design a multi-level edge computing system and deploy the distributed edge nodes in different hospitals and city servers, respectively. Then, we train the MobileUNet-FPN model in parallel at each edge node to effectively reduce the network communication overhead. Extensive experiments are conducted and the results show the superior performance of the proposed model on the fetal A4C and femoral-length images.

Is interventional bronchoscopy the first-line solution for mediastinal compression syndrome?

Abstract The mediastinum is known as the anatomical structure connecting the two pleural sacs. A variety of anatomical structures, from organs to veins and arteries, make mediastinal pathology extremely adventurous. We submit the case of a 67-year-old female patient, a former smoker, who presented to our clinic with dyspnoea on slight exertion, anterior chest pain and ineffective cough. The alarming aspect of the case is the stridor present at regular intervals and the patient’s dependence on oxygen. The CT scan reveals a compression syndrome caused by a tumour located in the upper and middle mediastinum that encompasses mediastinal venous and arterial structures and exerts an extrinsic stress effect on the oesophagus and tracheal. An emergency fibrobronchoscopy is performed and it is placed on a Y-shaped tracheal stent; additionally, two biopsies are also taken from different places. The point of debate of the case was related to the coexistence of two simultaneous histopathological types. The medical team’s swift intervention has given this patient a fighting chance to continue oncological and radiotherapy treatment.

A case report on a sporadic retroperitoneal malignant peripheral nerve sheath tumour mimicking a pelvic abscess

Soft tissue sarcomas (STS) are a diverse group of neoplasms with about 60 subtypes arising from a variety of anatomical structures across all age groups. The diagnosis of STS can prove to be challenging as it mimics a variety of non malignant conditions. Here we present one such case of a sporadic MPNST which was operated on with the main differential diagnosis of a Pelvic Abscess. Hence though STS is rare in general population it should always be kept in mind in cases of doubtful and confusing presentations.

Evolutionary Medicine: Microevolution of human morphology and its medico‐social impact

Human morphology is undergoing evolutionary changes. Hitherto, the socio‐economic and clinical impact of such alterations of human anatomy is mostly underestimated. We present not only current research data on such microevolutionary traits but also address particularly their medico‐social impact. Based on skeletal samples from ancient to modern times as well as based on modern Swiss Armed forces conscription data (N>100,000) we are able to show significant increases in body dimensions (such as stature or weight, BMI), decrease in skeletal robustness as well as an increase in morphological variability. A further particular focus is laid by us on the alterations of the axial skeleton as seen eg. by increased frequencies of spina bifida occulta. Embedded in the research framework of Evolutionary Medicine we will address specific consequences for public health measures (target group for weight reduction programs), medical teaching (variability of anatomical structures) or clinical research (low back pain etiology).

Helical tensegrity as a structural mechanism in human anatomy

Tensegrity is a structural system popularly recognised for its distinct compression elements that appear to float within a tensioned network. It is an attractive proposition in living organisms because such structures maintain their energy-efficient configuration even during changes in shape. Previous research has detailed the cellular cytoskeleton in terms of tensegrity, being a semi-autonomous system amenable to such analysis because of its size. It has also been described at higher levels in the extra-cellular/fascial matrix and musculo-skeletal system, but there are fewer syntheses of this. At a fundamental level, the helix and tensegrity share common origins in the geometries of the platonic solids, with inherent hierarchical potential that is typical of biological structures. The helix provides an energy-efficient solution to close-packing in molecular biology, a common motif in protein construction, and a readily observable pattern at many size levels throughout the body. The helix and tensegrity are described in a variety of anatomical structures, suggesting their importance to structural biology and manual therapy.

Anatomical Variations of the Coronary Sinus Ostium Area of the Human Heart

Classic anatomical dissection of 150 heart specimens from adults aged 18 - 80 years was performed. The Thebesian valve was absent in 20% of cases and, in these, 4% had a large ostial valve of the middle cardiac vein in front of the coronary sinus ostium. Fibres of Chiari were found in 10% of cases. Ostia of the middle cardiac vein, posterior veins of the left ventricle, small cardiac vein and deep cardiac veins were present in the distal 10 mm of the coronary sinus. Some samples had ostial and/or parietal valves or antivalves that sometimes contained muscular fibres. Distal accessory parietal valves (2%) and antivalves (1%) of the coronary sinus wall were found at a distance of 4 - 7 mm from its ostium. The frequency and variability of anatomical structures in the area of the coronary sinus ostium probably influence the haemodynamics of this area. Knowledge of and being able to identify these anatomical variations may help in identifying and overcoming potential difficulties in treating arrythmias and in cardiosurgery.

A Dirichlet process mixture model for brain MRI tissue classification

Accurate classification of magnetic resonance images according to tissue type or region of interest has become a critical requirement in diagnosis, treatment planning, and cognitive neuroscience. Several authors have shown that finite mixture models give excellent results in the automated segmentation of MR images of the human normal brain. However, performance and robustness of finite mixture models deteriorate when the models have to deal with a variety of anatomical structures. In this paper, we propose a nonparametric Bayesian model for tissue classification of MR images of the brain. The model, known as Dirichlet process mixture model, uses Dirichlet process priors to overcome the limitations of current parametric finite mixture models. To validate the accuracy and robustness of our method we present the results of experiments carried out on simulated MR brain scans, as well as on real MR image data. The results are compared with similar results from other well-known MRI segmentation methods.

Computed tomography simulation with superquadrics

Accurate and efficient simulation of an x-ray transform for representative structures plays an important role in research and development of x-ray CT, for the evaluation and improvement of CT image reconstruction algorithms, in particular. Superquadrics are a family of three-dimensional objects, which can be used to model a variety of anatomical structures. In this paper, we propose an algorithm for the computation of x-ray transforms for superellipsoids and tori with a monochromatic x-ray. Their usefulness is demonstrated by projection and reconstruction of a superquadric-based thorax phantom. Our work indicates that superquadric modeling provides a more realistic visualization than quadratic modeling, and a faster computation than spline methods.

Photogrammetric Techniques Using High Speed Cineradiography

A high speed 16 mm cineradiographic system originally developed at the University of Michigan Transportation Research Institute (UMTRI) for use in biomechanics research has been undergoing continuous upgrading in capability. In addition to changes in the structural aspect of the cineradiography, improvements have been made in the procedures used to obtain better image quality, as well as in the methods for interpretation of the digitized results. The current improvements in the system include (1) filtering of the x-ray source before penetration of the subject to increase image contrast and to protect the image tube; (2) hypersensitization of the film to increase its effective speed; (3) development of a neutral density radio-contrast medium for outlining anatomic structure without using the vascular system; and (4) development of procedures for obtaining analytic information about motion of nonrigid anatomic structures from digitized film. This system now consists of cameras that view a 50 mm (2 in.) diameter output of a P-11 phosphor of a high gain, four-stage magnetically focused image intensifier tube, gated on and off synchronously with the motion picture camera shutter. A lens optically couples the input photocathode of the image tube to an x-ray fluorescent (rare earth) screen image produced by a smoothed dc x-ray generator of a conventional type. The system is capable of looking at a large variety of anatomic structures under a wide range of dynamic loading conditions.

Pitfalls in CT recognition of mediastinal lymphadenopathy.

Computed tomography (CT) has become the most accurate radiologic technique for the evaluation of mediastinal lymph nodes. Since the introduction of thoracic CT, a variety of anatomic structures, both normal and aberrant, have been described that can be confused with enlarged mediastinal lymph nodes; these represent potential diagnostic pitfalls. This essay illustrates many of these structures and distinguish them from abnormal lymph nodes.

The versatility of the basic microscope system in otolaryngology.

The operating microscope is now an essential tool for a large number of surgical procedures in a wide range of disciplines. At many medical centers, the optical equipment is often shared by surgeons from several disciplines. The expansion of microsurgical interest will continue to be interdisciplinary in the future, and this will call for microscope systems that are sufficiently versatile, both optically and mechanically, to meet the needs of surgery on a wide variety of anatomic structures. The development of the current range of microsurgical procedures in otolaryngology is presented to illustrate the concept of versatility by demonstrating the expansion of microsurgical technique to many regions of the head and neck. The key to this versatility has been the interchangeable objective lens system (200-400 mm), which allows a working distance appropriate to the depth of the various surgical approaches and which also allows the free transfer of microsurgical skills and instrumentation to new procedures.