title: An elastography method based on the scanning contact resonance of a piezoelectric cantilever.
abstract: OBJECTIVE
  Most tissues may become significantly stiffer than their normal states when there are lesions inside. The tissue's modulus can then act as an identification parameter for clinic diagnosis of tumors or fibrosis, which leads to elastography. This study introduces a novel elastography method that can be used for modulus imaging of superficial organs.
  
  
  METHODS
  This method is based on the scanning contact-resonance of a unimorph piezoelectric cantilever. The cantilever vibrates in its bending mode with the tip pressed tightly on the sample. The contact resonance frequency of the cantilever-sample system is tracked at each scanning point, from which the sample's modulus can be derived based on a beam dynamic model and a contact mechanics model. Scanning is performed by a three-dimensional motorized stage and the whole system is controlled by a homemade software program based on LabVIEW.
  
  
  RESULTS
  Testing on in vitro beef tissues indicates that the fat and the muscle can be easily distinguished using this system, and the accuracy of the modulus measurement can be comparable with that of nanoindentation. Imaging on homemade gelatin phantoms shows that the depth information of the abnormalities can be qualitatively obtained by varying the pressing force. The detection limit of this elastography method is specially examined both experimentally and numerically. Results show that it can detect the typical lesions in superficial organs with the depth of several centimeters. The lateral resolution of this elastography method∕system is better than 0.5 mm, and could be further enhanced by using more scanning points.
  
  
  CONCLUSIONS
  The proposed elastography system can be regarded as a sensitive palpation robot, which may be very promising in early diagnosis of tumors in superficial organs such as breast and thyroid.
authors: State Key Lab for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871, China and HEDPS, Center for Applied Physics and Technologies, Peking University, Beijing 100871, China.
authors: Ji
authors: J
authors: Fu
authors: Faxin
authors: F
authors: Li
mesh_terms: D000818:Animals; D002417:Cattle; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D004560:Electricity; D057230:Limit of Detection; D009369:Neoplasms / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging