Application of Super Resolution Convolutional Neural Networks (SRCNNs) to enhance medical images resolution

The importance of resolution is crucial when working with medical images. The possibility to visualize details lead to a more accurate diagnosis and makes segmentation easier. However, obtention of high-resolution medical images requires of long acquisition times. In clinical environments, lack of time leads to the acquisition of low-resolution images. Super Resolution (SR) consist in post-processing images in order to enhance its resolution. During the last years, a branch of SR is getting promising results. This branch focuses in the application of Convolutional Neural Networks (CNNs) to the images. This project is intended to create a network able to enhance resolution of knee MR stored in DICOM format. Different networks are proposed, and evaluation is made by computing Peak Signal-to-Noise Ratio (PSNR) and normalized Cross-Correlation. One of the networks proposed, SR-DCNN, presented better results than the conventional method, bicubic interpolation. Finally, visual comparison of the SR-DCNN and bicubic interpolation also showed that the network proposed outperforms the conventional methods.Ingeniería Biomédic

Screening Tests for Assessing Athletes at Risk of ACL Injury or Reinjury-A Scoping Review

Various tests are available to assess athletes for factors associated with their susceptibility and risk of anterior cruciate ligament (ACL) injury or reinjury; however, it is unclear which tests are clinically meaningful and what should be considered when using them. Therefore, the aim of this scoping review was to screen and summarize testing and to derive evidence-based recommendations for clinicians, practitioners and future research. Five databases were searched to identify studies addressing musculoskeletal morphology or functional-performance-related screening tests with a clear conceptual link or an evidence-based relationship to ACL (re)injury. A quality rating was carried out using the National Institutes of Health (NIH) Study-Quality Assessment Tool. Six different categories of common screening tests were identified: balance and postural control, gait- and running-related tests, joint laxity, joint morphology and anthropometrics, jump tests and strength tests. Predicting future injury in a complex, dynamic system based on a single screening test is methodologically challenging, which is also reflected in the highly controversial findings in the literature regarding potential associations between specific screening tests and the occurrence of ACL injuries and reinjuries. Nonetheless, various screening tests can provide clinically relevant information on ACL-(re)injury-related factors and help to provide tailored preventive measures. A selection of corresponding evidence-based recommendations is derived and presented in this scoping review

Novel Insights into Anterior Cruciate Ligament Injury

Anterior cruciate ligament (ACL) injury is one of the most common sports injuries of the knee. ACL reconstruction has become, standard orthopaedic practice worldwide with an estimated 175,000 reconstructions per year in the United States.6 The ACL remains the most frequently studied ligament in orthopaedic research. Hundreds of papers are published each year related to the ACL. However, the treatment options and techniques are still developing and increasing, indicating the difficulties in the treatment of this central knee ligament

Patient-specific modelling in orthopedics: from image to surgery

In orthopedic surgery, to decide upon intervention and how it can be optimized, surgeons usually rely on subjective analysis of medical images of the patient, obtained from computed tomography, magnetic resonance imaging, ultrasound or other techniques. Recent advancements in computational performance, image analysis and in silico modeling techniques have started to revolutionize clinical practice through the development of quantitative tools, including patient#specific models aiming at improving clinical diagnosis and surgical treatment. Anatomical and surgical landmarks as well as features extraction can be automated allowing for the creation of general or patient-specific models based on statistical shape models. Preoperative virtual planning and rapid prototyping tools allow the implementation of customized surgical solutions in real clinical environments. In the present chapter we discuss the applications of some of these techniques in orthopedics and present new computer-aided tools that can take us from image analysis to customized surgical treatment

The soft-tissue restraints of the knee and its balancing capacity in total knee arthroplasty procedures

Total knee arthroplasty is a successful surgical treatment for patients with severe knee joint arthrosis. However, restoring soft-tissue function is a major challenge. Depending on the positioning of the prosthesis, the implantation procedure and the pathology of the patient, it is necessary to adjust the soft-tissue structures of the joint in order to restore the function of the knee. The assessment and adaptation of the soft-tissue envelope is a subjective process that is strongly dependent on the surgeon. This dissertation addresses these challenges and seeks quantitative guidelines for softtissue management based on a meta-analysis of the laxity of the natural knee joint. A further aim of the present study was to clarify in the scope of in-vitro investigations to what extent the loosening and removal of individual structures alters joint laxity and how far the joint can be balanced by targeted resection of soft-tissue structures. In addition, in-silico investigations within the scope of this thesis form the basis for a numerical tool to better understand the function of the ligaments and to better plan soft-tissue balancing preoperatively in the future. The investigations of the natural laxity of the knee jointin different flexion angles and loading directions by utilizing a meta-analysis show a strong dependency of the joint laxity on the flexion angle. Furthermore, the results show a distinct asymmetry of joint laxity when comparing translations in opposite directions within a certain degree of freedom. The data collected provide the surgeon with quantitative target parameters for natural soft-tissue balancing in knee arthroplasty procedures. The in-vitro investigations on 19 human knee specimens show that the restoration of soft-tissue function of the knee after arthroplasty cannot be achieved by kinematic alignment alone. The use of a bicruciate-retaining knee arthroplasty is the only way to keep the anterior and posterior stability of the joint in balance. To correct varus deformities, balancing of the medial collateral ligament appears to be a safe method. Correction of valgus laxity can be achieved by partially or completely resecting the lateral collateral ligament, however this increases the risk of instability in joint flexion. Within the scope of this work, subject-specific multi-body simulation models could be developed with which the laxity of the knee joint can be predicted, especially for low flexion angles. The presented procedure for the approximation of the ligament attachment sites represents a time-saving alternative to the segmentation of the attachments in MRI images.Deutsche Forschungsgemeinschaft/Sachbeihilfe/HU 873/7-1/E

Dynamics, Electromyography and Vibroarthrography as Non-Invasive Diagnostic Tools: Investigation of the Patellofemoral Joint

The knee joint plays an essential role in the human musculoskeletal system. It has evolved to withstand extreme loading conditions, while providing almost frictionless joint movement. However, its performance may be disrupted by disease, anatomical deformities, soft tissue imbalance or injury. Knee disorders are often puzzling, and accurate diagnosis may be challenging. Current evaluation approach is usually limited to a detailed interview with the patient, careful physical examination and radiographic imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissue conditions. More advanced imaging tools such as MRI or CT are available, but expensive, time consuming and can be used only under static conditions. Moreover, due to limited resolution the radiographic techniques cannot reveal early stage arthritis. The arthroscopy is often the only reliable option, however due to its semi-invasive nature, it cannot be considered as a practical diagnostic tool. Therefore, the motivation for this work was to combine three scientific methods to provide a comprehensive, non-invasive evaluation tool bringing insight into the in vivo, dynamic conditions of the knee joint and articular cartilage degeneration. Electromyography and inverse dynamics were employed to independently determine the forces present in several muscles spanning the knee joint. Though both methods have certain limitations, the current work demonstrates how the use of these two methods concurrently enhances the biomechanical analysis of the knee joint conditions, especially the performance of the extensor mechanism. The kinetic analysis was performed for 12 TKA, 4 healthy individuals in advanced age and 4 young subjects. Several differences in the knee biomechanics were found between the three groups, identifying age-related and post-operative decrease in the extensor mechanism efficiency, explaining the increased effort of performing everyday activities experienced by the elderly and TKA subjects. The concept of using accelerometers to assess the cartilage degeneration has been proven based on a group of 23 subjects with non-symptomatic knees and 52 patients suffering from knee arthritis. Very high success (96.2%) of pattern classification obtained in this work clearly demonstrates that vibroarthrography is a promising, non-invasive and low-cost technique offering screening capabilities

Developing a cationic contrast agent for computed tomographic imaging of articular cartilage and synthetic biolubricants for early diagnosis and treatment of osteoarthritis

Osteoarthritis (OA) causes debilitating pain for millions of people, yet OA is typically diagnosed late in the disease process after severe damage to the articular cartilage has occurred and few treatment options exist. Furthermore, destructive techniques are required to measure cartilage biochemical and mechanical properties for studying cartilage function and changes during OA. Hence, research and clinical needs exist for non-destructive measures of cartilage properties. Various arthroscopic (e.g., ultrasound probes) and imaging (e.g., MRI or CT) techniques are available for assessing cartilage less destructively. However, arthroscopic methods are limited by patient anesthesia/infection risks and cost, and MRI is hindered by high cost, long image acquisition times and low resolution. Contrast-enhanced CT (CECT) is a promising diagnostic tool for early-stage OA, yet most of its development work utilizes simplified and ideal cartilage models, and rarely intact, pre-clinical animal or human models. To advance CECT imaging for articular cartilage, this dissertation describes further development of a new cationic contrast agent (CA4+) for minimally-invasive assessment of cartilage biochemical and mechanical properties, including glycosaminoglycan content, compressive modulus, and coefficient of friction. Specifically, CA4+ enhanced CT is compared to these three cartilage properties initially using an ideal bovine osteochondral plug model, then the technique is expanded to examine human finger joints and both euthanized and live mouse knees. Furthermore, CECT attenuations with CA4+ map bovine meniscal GAG content and distribution, signifying CECT can evaluate multiple tissues involved in OA. CECT's sensitivity to critical cartilage and meniscal properties demonstrates its applicability as both a non-destructive research tool as well as a method for diagnosing and monitoring early-stage OA. Additionally, CECT enables evaluation of efficacy for a new biolubricant (2M TEG) for early-stage OA treatment. In particular, CECT can detect the reduced wear on cartilage surfaces for samples tested in 2M TEG compared to samples tested in saline (negative control). With its sensitivity to cartilage GAG content, surface roughness, and mechanical properties, CA4+ enhanced CT will serve as a valuable tool for subsequent in vivo animal and clinical use