Spatial and temporal-controlled tissue heating on a modified clinical ultrasound scanner for generating mild hyperthermia in tumors.
A new system is presented for generating controlled tissue heating with a clinical ultrasound scanner, and initial in vitro and in vivo results are presented that demonstrate both transient and sustained heating in the mild-hyperthermia range of 37 ( degrees )C-42 ( degrees )C. The system consists of a Siemens Antares ultrasound scanner, a custom dual-frequency three-row transducer array and an external temperature feedback control system. The transducer has two outer rows that operate at 1.5 MHz for tissue heating and a center row that operates at 5 MHz for B-mode imaging to guide the therapy. We compare the field maps obtained using a hydrophone against calculations of the ultrasound beam based on monochromatic and linear assumptions. Using the finite-difference time-domain (FDTD) method, we compare predicted time-dependent thermal profiles to measured profiles for soy tofu as a tissue-mimicking phantom. In vitro results show differential heating of 6 ( degrees )C for chicken breast and tofu. In vivo tests of the system were performed on three mice bearing Met-1 tumors, which is a model of aggressive, metastatic, and highly vascular breast cancer. In superficially implanted tumors, we demonstrate controlled heating to 42 ( degrees )C. We show that the system is able to maintain the temperature to within 0.1 ( degrees )C of the desired temperature both in vitro and in vivo.
Kruse
Dustin E
DE
Department of Biomedical Engineering, University of California, Davis, CA 95616, USA. dekruse@ucdavis.edu
Lai
Chun-Yen
CY
Stephens
Douglas N
DN
Sutcliffe
Patrick
P
Paoli
Eric E
EE
Barnes
Stephen H
SH
Ferrara
Katherine W
KW
D000818:Animals; D002645:Chickens; D006979:Hyperthermia, Induced / Q000295:instrumentation / Q000379:methods*; D008460:Meat; D051379:Mice; D009374:Neoplasms, Experimental / Q000000981:diagnostic imaging*; D045730:Soy Foods; D014464:Ultrasonic Therapy / Q000295:instrumentation / Q000379:methods*; D014463:Ultrasonography