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

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.

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.