A novel shape-similarity-based elastography technique for prostate cancer assessment.
OBJECTIVE
Association between tissue stiffness alteration and pathology is well known. This has formed the basis for prostate elastography imaging techniques where images of prostate tissue mechanical properties are reconstructed. In this paper, the authors present a novel prostate elastography technique which, unlike other techniques, relies on magnitude image data only.


METHODS
This proposed technique works in conjunction with ultrasound or magnetic resonance imaging (MRI) imaging modalities and it requires the prostate's pre- and postdeformation images as input. It uses a constrained reconstruction method where the elastic moduli of the prostate's normal and pathological tissues are determined based on an essential subset of the tissue deformation provided by the images data. The elasticity reconstruction technique uses optimization where similarity between calculated and observed shape features of the postcompression prostate image is maximized. The method was validated with an in silico phantom study followed by studies using ultrasound and MR with tissue-mimicking phantoms.


RESULTS
Using the proposed methods, it was observed that the maximum uncertainties of the reconstructed Young's modulus ratios of tumor to normal tissue were 15.6% and 9.7%, which were obtained from the transrectal ultrasound (TRUS) and MR tissue-mimicking phantom studies, respectively.


CONCLUSIONS
This novel prostate elastography technique relies on prostate TRUS or MRI images that can be routinely acquired without additional imaging hardware. The phantom studies provided evidence that the proposed technique has a good potential to reconstruct prostate stiffness maps noninvasively particularly when applied in conjunction with MRI. Further studies are necessary to evaluate the technique's merits for clinical use.
Department of Electrical and Computer Engineering, Western University, London, Ontario N6A 5C1, Canada.
Seyed Reza
SR
Mousavi
Department of Electrical and Computer Engineering, Western University, London, Ontario N6A 5C1, Canada.
Haisu
H
Wang
Department of Medical Biophysics, Western University, London, Ontario N6A 5C1, Canada.
Seyyed Mohammad
SM
Hesabgar
Department of Medical Biophysics, Western University, London, Ontario N6A 5C1, Canada and Imaging Research Laboratories, Robarts Research Institute (RRI), Western University, London, Ontario N6A 5C1, Canada.
Timothy J
TJ
Scholl
Department of Electrical and Computer Engineering, Western University, London, Ontario N6A 5C1, Canada; Department of Medical Biophysics, Western University, London, Ontario N6A 5C1, Canada; and Imaging Research Laboratories, Robarts Research Institute (RRI), Western University, London, Ontario N6A 5C1, Canada.
Abbas
A
Samani
D000465:Algorithms; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology