CT and MRI assessment and characterization using segmentation and 3D modeling techniques: applications to muscle, bone and brain

Abstract

This paper reviews the novel use of CT and MRI data and image processing tools to segment and reconstruct tissue images in 3D to determine characteristics of muscle, bone and brain.This to study and simulate the structural changes occurring in healthy and pathological conditions as well as in response to clinical treatments. Here we report the application of this methodology to evaluate and quantify: 1. progression of atrophy in human muscle subsequent to permanent lower motor neuron (LMN) denervation, 2. muscle recovery as induced by functional electrical stimulation (FES), 3. bone quality in patients undergoing total hip replacement and 4. to model the electrical activity of the brain. Study 1: CT data and segmentation techniques were used to quantify changes in muscle density and composition by associating the Hounsfield unit values of muscle, adipose and fibrous connective tissue with different colors. This method was employed to monitor patients who have permanent muscle LMN denervation in the lower extremities under two different conditions: permanent LMN denervated not electrically stimulated and stimulated. Study 2: CT data and segmentation techniques were employed, however, in this work we assessed bone and muscle conditions in the pre-operative CT scans of patients scheduled to undergo total hip replacement. In this work, the overall anatomical structure, the bone mineral density (BMD) and compactness of quadriceps muscles and proximal femoral was computed to provide a more complete view for surgeons when deciding which implant technology to use. Further, a Finite element analysis provided a map of the strains around the proximal femur socket when solicited by typical stresses caused by an implant press fitting. Study 3 describes a method to model the electrical behavior of human brain using segmented MR images. The aim of the work is to use these models to predict the electrical activity of the human brain under normal and pathological conditions by developing detailed 3D representations of major tissue surfaces within the head, with over 12 different tissues segmented. In addition, computational tools in Matlab were developed for calculating normal vectors on the brain surface and for associating this information with the equivalent electrical dipole sources as an input into the model.

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

“…Micro X-ray Computer Tomography (μCT) is another promising imaging modality for the functional assessment of engineered tissue, as it allows for the non-destructive quantification of many aspects of engineered scaffolds, such as porosity, pore size, and interconnectivity. [115][116][117][118][119][120][121][122] Inferring cellular integration and interaction with its engineered scaffold is made possible in μCT, as images can be acquired sequentially over time with minimal negative affects to cells from X-ray dose. 123,124 However, in order to achieve suffiecient X-ray absorption (contrast), soft tissues and biomaterials oftentimes need to be freezedried or kept under dry conditions instead of standard culture conditionsa notion which can significantly affect certain cell or tissue types.…”

Home-based Functional Electrical Stimulation for long-term denervated human muscle: History, basics, results and perspectives of the Vienna Rehabilitation Strategy

“…Further, he suggested to Paolo Gargiulo and Helmut Kern to add false color to “Monitoring of muscle and bone recovery in spinal cord injury using three-dimensional imaging and segmentation techniques”, to allow doctors and their patients to read much easy-to-interpret Computer Tomography analyses of their deteriorating or recovering muscles. 38 , 39 , 46 …”

Low-amplitude craniofacial EMG power spectral density and 3D muscle reconstruction from MRI

“…The use of segmented magnetic resonance imaging (MRI) has previously been developed to model the electrical behavior of the human brain under normal and pathological conditions. 22 This imaging modality can be utilized to accurately characterize extant coupled non-linear physical mechanisms and how they impact the propagation of EMG and EEG signals through the inhomogeneous media of the head. 23 In the generation of a 3D model from segmented MRI images, most major tissue surfaces can readily be identified in each slice.…”

“… 23 In the generation of a 3D model from segmented MRI images, most major tissue surfaces can readily be identified in each slice. 22 , 24 , 25 …”