title: Subharmonic aided pressure estimation for monitoring interstitial fluid pressure in tumours--in vitro and in vivo proof of concept.
abstract: The feasibility of using subharmonic aided pressure estimation (SHAPE) to noninvasively estimate interstitial fluid pressure (IFP) was studied. In vitro, radiofrequency signals, from 0.2 ml/l of Definity (Lantheus Medical Imaging, N Billerica, MA) were acquired within a water-tank with a Sonix RP ultrasound scanner (Analogic Ultrasound, Richmond, BC, Canada; fT/R=6.7/3.35 MHz and fT/R=10/5 MHz) and the subharmonic amplitudes of the signals were compared over 0-50 mmHg. In vivo, five swine with naturally occurring melanomas were studied. Subharmonic signals were acquired from tumours and surrounding tissue during infusion of Definity and compared to needle-based pressure measurements. Both in vitro and in vivo, an inverse linear relationship between hydrostatic pressure and subharmonic amplitude was observed with r(2)=0.63-0.95; p<0.05, maximum amplitude drop 11.36 dB at 10 MHz and -8 dB, and r(2) as high as 0.97; p<0.02 (10 MHz and -4/-8 dB most promising), respectively, indicating that SHAPE may be useful in monitoring IFP.
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA; School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA.
authors.forename: V G
authors.initials: VG
authors.lastname: Halldorsdottir
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA; School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Dave
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Eisenbrey
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Machado
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA; Department of Ultrasound, The Second People's Hospital of Fujian, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China.
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Liu
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Merton
authors.affiliation: Department of Radiology, Thomas Jefferson University, Philadelphia, PA, USA. Electronic address: flemming.forsberg@jefferson.edu.
authors.forename: F
authors.initials: F
authors.lastname: Forsberg
mesh_terms: D000162:Acoustics; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D004867:Equipment Design; D045604:Extracellular Fluid / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D005466:Fluorocarbons / Q000008:administration & dosage; D006874:Hydrostatic Pressure; D008545:Melanoma / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D013552:Swine; D014159:Transducers; D014463:Ultrasonography / Q000379:methods
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren
keywords: Breast cancer; Contrast agents; Pressure estimation; Subharmonic signals; Ultrasound imaging