title: Quantitative color three-dimensional computer tomography imaging of human long-term denervated muscle.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Research and Development, HTS, Landspitali University Hospital, Reykjavik, Iceland. paologar@landspitali.is
authors.forename: Paolo
authors.initials: P
authors.lastname: Gargiulo
authors.forename: Helmut
authors.initials: H
authors.lastname: Kern
authors.forename: Ugo
authors.initials: U
authors.lastname: Carraro
authors.forename: Páll
authors.initials: P
authors.lastname: Ingvarsson
authors.forename: Sigrún
authors.initials: S
authors.lastname: Knútsdóttir
authors.forename: Vilborg
authors.initials: V
authors.lastname: Gudmundsdóttir
authors.forename: Stefán
authors.initials: S
authors.lastname: Yngvason
authors.forename: Brynjar
authors.initials: B
authors.lastname: Vatnsdal
authors.forename: Thordur
authors.initials: T
authors.lastname: Helgason
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D003116:Color; D003238:Connective Tissue / Q000000981:diagnostic imaging / Q000473:pathology; D018450:Disease Progression; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000294:innervation / Q000473:pathology; D009929:Organ Size; D010264:Paraplegia / Q000000981:diagnostic imaging* / Q000473:pathology; D020127:Recovery of Function; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D013577:Syndrome; D036542:Tomography, Spiral Computed / Q000379:methods*