Premium
MO‐D‐220‐02: Assessing Intra‐Tumor Hemodynamics and Oxygen Concentration Using Photoacoustic Computed Tomography
Author(s) -
Stantz K,
Cao N,
Shaffer M
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612984
Subject(s) - perfusion , biomedical engineering , oxygenation , blood volume , nuclear medicine , hemodynamics , tumor hypoxia , photoacoustic imaging in biomedicine , scanner , materials science , medicine , radiology , radiation therapy , computer science , physics , artificial intelligence , optics
Purpose:The goal is to develop a method to non‐invasively assess intra‐ tumor pO2 using photoacoustic imaging. It is well established that the oxygen status of a tumor plays a critical role in the therapeutic response and resistance, resulting in treatment failure and poor disease‐free and overall survival. Clinical techniques, such as polarographic electrode, photoluminescence‐quenching, or pimonidazole, are invasive and lack the patho‐physiological etiology leading to hypoxia. A biophysical model is proposed to determine local pO2 based on fusing hemodynamic measurements acquired from dynamic contrast‐enhanced and spectroscopic photoacoustic imaging (DCE‐PCT and PCT‐S). Methods: MCF7 and MCF7/VEGF xenograft breast tumors were first scanned within a prototype PCT scanner to obtain parametric maps of oxygen saturation and hemoglobin concentration and within a clinical CT scanner to obtain dynamic contrast‐enhanced data (DCE‐CT) to obtain parametric maps of perfusion, fractional‐plasma‐volume, and fractional‐interstitial‐volume. These maps were fused based on a mathematical model of tissue oxygen delivery, and compared to measurements taken with an OxyLite probe. To replace DCE‐CT, a new generation of PCT scanner was developed to acquire DCE‐PCT data and realize physiological maps. Mice with MDA‐ MB‐231 xenograft breast tumors were i.v. injected with ICG, and scanned prior to and every 12‐seconds for up to 4‐minutes and at 15‐minutes post‐ injection. These contrast‐enhance curves were fit compartmental models to obtain maps of tumor perfusion and fractional plasma volumes. Results: Preliminary results comparing pO2 measurements implementing biophysical models and PCT‐S and DCE‐CT and OxyLite probe measured a linear correlation of R2=0.82, and a slope of 0.975(±0.10) and an intercept of − 0.093(±2.2)mmHg. The first parametric maps of tumor perfusion and fractional plasma volume using DCE‐PCT will be presented and compared to DCE‐CT, and ICG kinematics identifying regions of high extravasation. Conclusions: A biophysical model of pO2 based on hemodynamic data and physiological maps in breast tumors obtained from photoacoustic imaging has been demonstrated. NIH/SBIR Funding from OptoSonics, Inc, OptoSonics, Inc., 108 Straight Road, Oriental, NC 28571; Consulting for Endra, Inc, 35 Research Drive, Suite 100, Ann Arbor, MI 48103.