Paolo Gargiulo

Restoration of Muscle Volume and Shape Induced by Electrical Stimulation of Denervated Degenerated Muscles: Qualitative and Quantitative Measurement of Changes in Rectus Femoris Using Computer Tomography and Image Segmentation

This study demonstrates in a novel way how volume and shape are restored to denervated degenerated muscles due to a special pattern of electrical stimulation. To this purpose, Spiral Computer Tomography (CT) and special image processing tools were used to develop a method to isolate the rectus femoris from other muscle bellies in the thigh and monitor growth and morphology changes very accurately. During 4 years of electrical stimulation, three-dimensional (3D) reconstructions of the rectus femoris muscles from patients with long-term flaccid paraplegia were made at different points in time. The growth of the muscle and its changes through the time period are seen in the 3D representation and are measured quantitatively. Furthermore, changes in shape are compared with respect to healthy muscles in order to estimate the degree of restoration. The results clearly show a slow but continuing muscle growth induced by electrical stimulation; the increase of volume is accompanied by the return of a quasi-normal muscle shape. This technique allows a unique way of monitoring which provides qualitative and quantitative information on the denervated degenerated muscle behavior otherwise hidden.

Monitoring of Muscle and Bone Recovery in Spinal Cord Injury Patients Treated With Electrical Stimulation Using Three-Dimensional Imaging and Segmentation Techniques: Methodological Assessment

Muscle tissue composition accounting for the relative content of muscle fibers and intramuscular adipose and loose fibrous tissues can be efficiently analyzed and quantified using images from spiral computed tomography (S-CT) technology and the associated distribution of Hounsfield unit (HU) values. Muscle density distribution, especially when including the whole muscle volume, provides remarkable information on the muscle condition. Different physiological and pathological scenarios can be depicted using the muscle characterization technique based on the HU values and the definition of appropriate intervals and the association of such intervals to different colors. Using this method atrophy, degeneration, and restoration in denervated muscle undergoing electrical stimulation treatments can be clearly displayed and monitored. Moreover, finite element methods are employed to calculate Youngs modulus on the patella bone and to analyze correlation between muscle contraction and bone strength changes. The reliability of this tool though depends on S-CT assessment and calibration. To assess imaging quality and the use of HU values to display muscle composition, different S-CT devices are compared using a Quasar body scanner. Density distributions and volumes of various calibration elements such as lung, polyethylene, water equivalent, and trabecular and dense bone are measured with different scanning protocols and at different points of time. The results show that every scanned element undergoes HU variations, which are greater for materials at the extremes of the HU scale, such as dense bone and lung inhale. Moreover, S-CT scanning with low tube voltages (80 KV) produces inaccurate HU values especially in bones. In conclusion, 3-D modeling techniques based on S-CT scanning is a powerful follow-up tool that may provide structural information at the millimeter scale, and thus may drive choice and timing to validate rehabilitation protocols.

Muscle, tendons, and bone: structural changes during denervation and FES treatment

Abstract Objectives: This paper describes a novel approach to determine structural changes in bone, muscle, and tendons using medical imaging, finite element models, and processing techniques to evaluate and quantify: (1) progression of atrophy in permanently lower motor neuron (LMN) denervated human muscles, and tendons; (2) their recovery as induced by functional electrical stimulation (FES); and (3) changes in bone mineral density and bone strength as effect of FES treatment. Methods: Briefly, we used three-dimensional reconstruction of muscle belly, tendons, and bone images to study the structural changes occurring in these tissues in paralysed subjects after complete lumbar-ischiadic spinal cord injury (SCI). These subjects were recruited through the European project RISE, an endeavour designed to establish a novel clinical rehabilitation method for patients who have permanent and non-recoverable muscle LMN denervation in the lower extremities. This paper describes the use of segmentation techniques to study muscles, tendons, and bone in several states: healthy, LMN denervated-degenerated but not stimulated, and LMN denervated-stimulated. Here, we have used medical images to develop three-dimensional models and advanced imaging, including computational tools to display tissue density. Different tissues are visualized associating proper Hounsfield intervals defined experimentally to fat, connective tissue, and muscle. Finite element techniques are used to calculate Young’s modulus on the patella bone and to analyse correlation between muscle contraction and bone strength changes. Results: These analyses show restoration of muscular structures, tendons, and bone after FES as well as decline of the same tissues when treatment is not performed. This study suggests also a correlation between muscle growth due to FES treatment and increase in density and strength in patella bone. Conclusion: Segmentation techniques and finite element analysis allow the study of the structural changes of human skeletal muscle, tendons, and bone in SCI patient with LMN injury and to monitor effects and changes in tissue composition due to FES treatment. This work demonstrates improved bone strength in the patella through the FES treatment applied on the quadriceps femur.

Quantitative color three-dimensional computer tomography imaging of human long-term denervated muscle

Abstract Objectives: A new non-invasive method was developed to analyse macroscopic and microscopic structural changes of human skeletal muscle based on processing techniques of medical images, here exemplified by monitoring progression and recovery of long-term denervation by home based functional electrical stimulation. Methods: Spiral computer tomography images and special computational tools were used to isolate the quadriceps muscles and to make three-dimensional reconstructions of denervated muscles. Shape, volume and density changes were quantitatively measured on each part of the quadriceps muscle. Changes in tissue composition within the muscle were visualized associating Hounsfield unit values of normal or atrophic muscle, fat and connective tissue to different colors. The minimal volumetric element (voxel) is approximately ten times smaller than the volume analysed by needle muscle biopsy. The results of this microstructural analysis are presented as the percentage of different tissues (muscle, loose and fibrous connective tissue, and fat) in the total volume of the rectus muscle and displaying the first cortical layer of voxels that describe the muscle epimysium directly on the muscle three-dimensional reconstruction. Results: In normal and paraplegic patients, this new monitoring approach provides information on macroscopic shape, volume, and the increased adipose and fibrous tissue content within the denervated muscle. In particular, the change displayed at epimysium level is structurally important and possibly functionally relevant. Here we show that muscle restoration induced by homebased functional electrical stimulation is documented by the increase in normal muscle tissue from 45 to 60% of the whole volume, while connective tissue and fat are reduced of 30 and 50% with respect to the pre-treatment values. These changes are in agreement with the muscle biopsy findings, and self-evident when epimysium thickness is depicted. Conclusion: Color three-dimensional imaging of human skeletal muscle is an improved computational approach of non-invasive medical imaging able to detect not only macroscopic changes of human muscle volume and shape, but also their tissue composition at microscopic level.

Assessment of Total Hip Arthroplasty by Means of Computed Tomography 3D Models and Fracture Risk Evaluation

Total hip arthroplasty (THA) can be achieved by using a cemented or noncemented prosthesis. Besides patients age, weight, and other clinical signs, the evaluation of the quality of the bones is a crucial parameter on which orthopedic surgeons base the choice between cemented and noncemented THA. Although bone density generally decreases with age and a cemented THA is preferred for older subjects, the bone quality of a particular patient should be quantitatively evaluated. This study proposes a new method to quantitatively measure bone density and fracture risk by using 3D models extracted by a preoperative computed tomography (CT) scan of the patient. Also, the anatomical structure and compactness of the quadriceps muscle is computed to provide a more complete view. A spatial reconstruction of the tissues is obtained by means of CT image processing, then a detailed 3D model of bone mineral density of the femur is provided by including quantitative CT density information (CT must be precalibrated). A finite element analysis will provide a map of the strains around the proximal femur socket when solicited by typical stresses caused by an implant. The risk for structural failure due to press-fitting and compressive stress during noncemented THA surgery was estimated by calculating a bone fracture risk index (ratio between actual compressive stress and estimated failure stress of the bone). A clinical trial was carried out including 36 volunteer patients (ages 22-77) who underwent unilateral THA surgery for the first time: 18 received a cemented implant and 18 received a noncemented implant. CT scans were acquired before surgery, immediately after, and after 12 months. Bone and quadriceps density results were higher in the healthy leg in about 80% of the cases. Bone and quadriceps density generally decrease with age but mineral density may vary significantly between patients. Preliminary results indicate the highest fracture risk at the calcar and the lowest at the intertrocanteric line, with some difference between patients. An analysis of the results suggest that this methodology can be a valid noninvasive decision support tool for THA planning; however, further analyses are needed to tune the technique and to allow clinical applications. Combination with gait analysis data is planned.

Persistent muscle fiber regeneration in long term denervation. Past, present, future

Despite the ravages of long term denervation there is structural and ultrastructural evidence for survival of muscle fibers in mammals, with some fibers surviving at least ten months in rodents and 3-6 years in humans. Further, in rodents there is evidence that muscle fibers may regenerate even after repeated damage in the absence of the nerve, and that this potential is maintained for several months after denervation. While in animal models permanently denervated muscle sooner or later loses the ability to contract, the muscles may maintain their size and ability to function if electrically stimulated soon after denervation. Whether in mammals, humans included, this is a result of persistent de novo formation of muscle fibers is an open issue we would like to explore in this review. During the past decade, we have studied muscle biopsies from the quadriceps muscle of Spinal Cord Injury (SCI) patients suffering with Conus and Cauda Equina syndrome, a condition that fully and irreversibly disconnects skeletal muscle fibers from their damaged innervating motor neurons. We have demonstrated that human denervated muscle fibers survive years of denervation and can be rescued from severe atrophy by home-based Functional Electrical Stimulation (h-bFES). Using immunohistochemistry with both non-stimulated and the h-bFES stimulated human muscle biopsies, we have observed the persistent presence of muscle fibers which are positive to labeling by an antibody which specifically recognizes the embryonic myosin heavy chain (MHCemb). Relative to the total number of fibers present, only a small percentage of these MHCemb positive fibers are detected, suggesting that they are regenerating muscle fibers and not pre-existing myofibers re-expressing embryonic isoforms. Although embryonic isoforms of acetylcholine receptors are known to be re-expressed and to spread from the end-plate to the sarcolemma of muscle fibers in early phases of muscle denervation, we suggest that the MHCemb positive muscle fibers we observe result from the activation, proliferation and fusion of satellite cells, the myogenic precursors present under the basal lamina of the muscle fibers. Using morphological features and molecular biomarkers, we show that severely atrophic muscle fibers, with a peculiar cluster reorganization of myonuclei, are present in rodent muscle seven-months after neurectomy and in human muscles 30-months after complete Conus-Cauda Equina Syndrome and that these are structurally distinct from early myotubes. Beyond reviewing evidence from rodent and human studies, we add some ultrastructural evidence of muscle fiber regeneration in long-term denervated human muscles and discuss the options to substantially increase the regenerative potential of severely denervated human muscles not having been treated with h-bFES. Some of the mandatory procedures, are ready to be translated from animal experiments to clinical studies to meet the needs of persons with long-term irreversible muscle denervation. An European Project, the trial Rise4EU (Rise for You, a personalized treatment for recovery of function of denervated muscle in long-term stable SCI) will hopefully follow

Quantitative Computed Tomography and image analysis for advanced muscle assessment

Medical imaging is of particular interest in the field of translational myology, as extant literature describes the utilization of a wide variety of techniques to non-invasively recapitulate and quantity various internal and external tissue morphologies. In the clinical context, medical imaging remains a vital tool for diagnostics and investigative assessment. This review outlines the results from several investigations on the use of computed tomography (CT) and image analysis techniques to assess muscle conditions and degenerative process due to aging or pathological conditions. Herein, we detail the acquisition of spiral CT images and the use of advanced image analysis tools to characterize muscles in 2D and 3D. Results from these studies recapitulate changes in tissue composition within muscles, as visualized by the association of tissue types to specified Hounsfield Unit (HU) values for fat, loose connective tissue or atrophic muscle, and normal muscle, including fascia and tendon. We show how results from these analyses can be presented as both average HU values and compositions with respect to total muscle volumes, demonstrating the reliability of these tools to monitor, assess and characterize muscle degeneration.

Imaging approaches in functional assessment of implantable myogenic biomaterials and engineered muscle tissue

The fields of tissue engineering and regenerative medicine utilize implantable biomaterials and engineered tissues to regenerate damaged cells or replace lost tissues. There are distinct challenges in all facets of this research, but functional assessments and monitoring of such complex environments as muscle tissues present the current strategic priority. Many extant methods for addressing these questions result in the destruction or alteration of tissues or cell populations under investigation. Modern advances in non-invasive imaging modalities present opportunities to rethink some of the anachronistic methods, however, their standard employment may not be optimal when considering advancements in myology. New image analysis protocols and/or combinations of established modalities need to be addressed. This review focuses on efficacies and limitations of available imaging modalities to the functional assessment of implantable myogenic biomaterials and engineered muscle tissues.

Bone Mineral Density and Fracture Risk Assessment to Optimize Prosthesis Selection in Total Hip Replacement

The variability in patient outcome and propensity for surgical complications in total hip replacement (THR) necessitates the development of a comprehensive, quantitative methodology for prescribing the optimal type of prosthetic stem: cemented or cementless. The objective of the research presented herein was to describe a novel approach to this problem as a first step towards creating a patient-specific, presurgical application for determining the optimal prosthesis procedure. Finite element analysis (FEA) and bone mineral density (BMD) calculations were performed with ten voluntary primary THR patients to estimate the status of their operative femurs before surgery. A compilation model of the press-fitting procedure was generated to define a fracture risk index (FRI) from incurred forces on the periprosthetic femoral head. Comparing these values to patient age, sex, and gender elicited a high degree of variability between patients grouped by implant procedure, reinforcing the notion that age and gender alone are poor indicators for prescribing prosthesis type. Additionally, correlating FRI and BMD measurements indicated that at least two of the ten patients may have received nonideal implants. This investigation highlights the utility of our model as a foundation for presurgical software applications to assist orthopedic surgeons with selecting THR prostheses.

Anthropometry of Human Muscle Using Segmentation Techniques and 3D Modelling: Applications to Lower Motor Neuron Denervated Muscle in Spinal Cord Injury

This chapter describes a novel approach to determining muscle anthropometry using medical imaging and processing techniques to evaluate and quantify: (1) progression of atrophy in permanent muscle lower motor neuron (LMN) denervation in humans and (2) muscle recovery as induced by functional electrical stimulation (FES). Briefly, we used three-dimensional reconstruction of muscle belly and bone images to study the structural changes occurring in these tissues in paralyzed subjects after complete lumbar-ischiatic spinal cord injury (SCI). These subjects were recruited through the European project RISE, an endeavour designed to establish a novel clinical rehabilitation method for patients who have permanent and non-recoverable muscle LMN denervation in the lower extremities. This chapter describes the use of anthropometric techniques to study muscles in several states: healthy, LMN denervated-degenerated not stimulated, and LMN denervated-stimulated. Here, we have used medical images to develop three-dimensional models, including computational models of activation patterns induced by FES. Shape, volume and density changes were measured on each part of the muscles studied. Changes in tissue composition within both normal and atrophic muscle were visualized by associating the Hounsfield unit values of fat and connective tissue with different colours. The minimal volumetric element (voxel) is approximately ten times smaller than the volume analyzed by needle muscle biopsy. The results of this microstructural analysis are presented as the percentage of different tissues (muscle, loose and fibrous connective tissue, fat) in the total volume of the rectus femoris muscle; the results display the first cortical layer of voxels that describe the muscle epimisium directly on the three-dimensional reconstruction of the muscle. These analyses show restoration of the muscular structure after FES. The three-dimensional approach used in this work also allows measurement of geometric changes in LMN denervated muscle. The computational methods developed allow us to calculate curvature indices along the muscle’s central line in order to quantify changes in muscle shape during the treatment. The results show a correlation between degeneration status and changes in shape; the differences in curvature between control and LMN denervated muscle diminish with the growth of the latter. Bone mineral density of the femur is also measured in order to study the structural changes induced by muscle contraction and current flow. Importantly, we show how segmented data can be used to build numerical models of the stimulated LMN denervated muscle. These models are used to study the distribution of the electrical field during stimulation and the activation patterns.