title: Fractal dimension of bone texture in radiographs correlates to ultrasound broadband attenuation T-score.
abstract: OBJECTIVE
  We aimed to measure the fractal dimension on x-ray images and ultrasonographic parameters of the os calcis of bone from 4 districts in osteoporotic patients and in control subjects, in order to test the hypothesis that ultrasonographic parameters correlate to the fractal dimension obtained on x-ray images.
  
  
  METHODS
  Fractal analysis on radiological images from 4 bone districts (proximal femur, calcaneus, metacarpus and 3rd phalanx) was performed in a study comparing ultrasonographic evaluation of the os calcis in severe osteoporotic patients and in control cases. We studied 86 x-ray-views from patients with severe reduction of ultrasound Stiffness Index and in healthy women. Ultrasound measurements of left os calcis were performed using the Lunar Achilles-Plus instrument. Fractal analysis was performed using the box-counting method.
  
  
  RESULTS
  In healthy subjects, fractal dimension, D, measure of structural complexity, resulted close to the topological dimension (no fractal structure), TD, in femur (1.99±0.03)and phalanx (1.96±0.03), D differed significantly from TD in calcaneus (D=1.90±0.02; p<0.001) and metacarpus (D=1.89±0.03, p<0.001). In osteoporotic subjects, in calcaneus and metacarpus, D was higher (1.94±0.03, 1.93±0.03, respectively) than in healthy subjects (1.90±0.02, 1.89±0.02, respectively, p<0.01). In all the subjects, fractal dimension and ultrasound broadband attenuation T-score correlated significantly in calcaneus and metacarpus (p<0.03 and p<0.02, respectively).
  
  
  CONCLUSIONS
  Parameters based on a combination of ultrasonic examination and fractal analysis on radiographic images may add useful structural information regarding the patients' skeleton using non invasive procedures.
authors: Department of Medical Biotechnologies, University of Siena, Siena, Italy. gbianciardi@unisi.it.
authors: Giorgio
authors: G
authors: Bianciardi
authors: Stefania
authors: S
authors: Bisogno
authors: Ilaria
authors: I
authors: Bertoldi
authors: Lorella
authors: L
authors: Laurini
authors: Giuseppe
authors: G
authors: Coviello
authors: Bruno
authors: B
authors: Frediani
mesh_terms: D000368:Aged; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002111:Calcaneus / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D050278:Finger Phalanges / Q000000981:diagnostic imaging; D017709:Fractals; D006801:Humans; D007091:Image Processing, Computer-Assisted; D050279:Metacarpal Bones / Q000000981:diagnostic imaging; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D011859:Radiography; D014463:Ultrasonography