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Thermoacoustic contrast of prostate cancer due to heating by very high frequency irradiation. Phys Med Biol 2015 Jan 21;60(2):689-708 PMID: 25554968 PMCID: PMC4292912

Pubmed ID

25554968

DOI

10.1088/0031-9155/60/2/689

Abstract

Applying the thermoacoustic (TA) effect to diagnostic imaging was first proposed in the 1980s. The object under test is irradiated by high-power pulses of electromagnetic energy, which heat tissue and cause thermal expansion. Outgoing TA pressure pulses are detected by ultrasound transducers and reconstructed to provide images of the object. The TA contrast mechanism is strongly dependent upon the frequency of the irradiating electromagnetic pulse. When very high frequency (VHF) electromagnetic irradiation is utilized, TA signal production is driven by ionic content. Prostatic fluids contain high levels of ionic metabolites, including citrate, zinc, calcium, and magnesium. Healthy prostate glands produce more ionic metabolites than diseased glands. VHF pulses are therefore expected to generate stronger TA signal in healthy prostate glands than in diseased glands. A benchtop system for performing ex vivo TA computed tomography with VHF energy is described and images are presented. The system utilizes irradiation pulses of 700 ns duration exceeding 20 kW power. Reconstructions frequently visualize anatomic landmarks such as the urethra and verumontanum. TA reconstructions from three freshly excised human prostate glands with little, moderate, and severe cancerous involvement are compared with histology. TA signal strength is negatively correlated with percent cancerous involvement in this small sample size. For the 45 regions of interest analyzed, a reconstruction value of 0.4 mV provides 100% sensitivity but only 29% specificity. This sample size is far too small to draw sweeping conclusions, but the results warrant a larger volume study including comparison of TA images to the gold standard, histology.

Author List

Patch SK, Hull D, Thomas M, Griep SK, Jacobsohn K, See WA

Authors

Kenneth Jacobsohn MD Associate Professor in the Urologic Surgery department at Medical College of Wisconsin
Sarah K. Patch PhD Associate Professor in the Physics department at University of Wisconsin - Milwaukee
William A. See MD Chair, Professor in the Urologic Surgery department at Medical College of Wisconsin




Scopus

2-s2.0-84920836388   6 Citations

MESH terms used to index this publication - Major topics in bold

Acoustics
Body Temperature
Computer Simulation
Contrast Media
Electromagnetic Radiation
Hot Temperature
Humans
Image Enhancement
Image Processing, Computer-Assisted
Male
Prostatic Neoplasms
Signal-To-Noise Ratio
jenkins-FCD Prod-310 bff9d975ec7f2d302586822146c2801dd4449aad