Our aim is to develop a clinically viable, fast-acquisition, prostate MR elastography (MRE) system with transperineal excitation. We developed a new actively shielded electromagnetic transducer, designed to enable quick deployment and positioning within the scanner. The shielding of the transducer was optimized using simulations. We also employed a new rapid pulse sequence that encodes the three-dimensional displacement field in the prostate gland using a fractionally encoded steady-state gradient echo sequence, thereby shortening the acquisition time to a clinically acceptable 8-10 min. The methods were tested in two phantoms and seven human subjects (six volunteers and one patient with prostate cancer). The MRE acquisition time for 24 slices, with an isotropic resolution of 2 mm and eight phase offsets, was 8 min, and the total scan, including positioning and set-up, was performed in 15-20 min. The phantom study demonstrated that the transducer does not interfere with the acquisition process and that it generates displacement amplitudes that exceed 100 µm even at frequencies as high as 300 Hz. In the in vivo human study, average wave amplitudes of 30 µm (46 µm at the apex) were routinely achieved within the prostate gland at 70 Hz. No pain or discomfort was reported. Results in a single patient suggest that MRE can identify cancer tumors, although this result is preliminary. The proposed methods allow the integration of prostate MRE with other multiparametric MRI methods. The results of this study clearly motivate the clinical evaluation of transperineal MRE in patients.
Vibroelastography is a technique to measure tissue elasticity using a multi-frequency shear wave approach. The method uses ultrasound to image dynamic deformation of soft tissue while an actuator applies surface vibrations. In this paper we evaluate vibroelastography for the first time in differentiating between malignant and benign breast lesions.A dataset of 20 lesions, including fibroadenoma and invasive ductal carcinoma (IDC) lesions was analysed. Ultrasound radiofrequency data were captured while the breast tissue was vibrated with a snap-on actuator at multiple frequencies at an amplitude of less than 100 microns. After the VE exam, the subjects underwent core-needle biopsy. The pathology report was used as the ground truth to validate the VE result. The VE results indicate that both benign fibroadenoma and IDC result in hardening of the tissue; however, IDC lesions exhibits higher values of elasticity compared to benign masses which can be captured using absolute and relative elasticity maps provided by VE.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.