Photoacoustic Computed Tomography of Breast Cancer in Response to Neoadjuvant Chemotherapy

Abstract

Neoadjuvant chemotherapy (NAC) has contributed to improving breast cancer outcomes, and it would ideally reduce the need for definitive breast surgery in patients who have no residual cancer after NAC treatment. However, there is no reliable noninvasive imaging modality accepted as the routine method to assess response to NAC. Because of the inability to detect complete response, post‐NAC surgery remains the standard of care. To overcome this limitation, a single‐breath‐hold photoacoustic computed tomography (SBH‐PACT) system is developed to provide contrast similar to that of contrast‐enhanced magnetic resonance imaging, but with much higher spatial and temporal resolution and without injection of contrast chemicals. SBH‐PACT images breast cancer patients at three time points: before, during, and after NAC. The analysis of tumor size, blood vascular density, and irregularity in the distribution and morphology of the blood vessels on SBH‐PACT accurately identifies response to NAC as confirmed by the histopathological diagnosis. SBH‐PACT shows its near‐term potential as a diagnostic tool for assessing breast cancer response to systemic treatment by noninvasively measuring the changes in cancer‐associated angiogenesis. Further development of SBH‐PACT may also enable serial imaging, rather than the use of current invasive biopsies, to diagnose and follow indeterminate breast lesions.

3D Ultrasound-Guided Photoacoustic Imaging to Monitor the Effects of Suboptimal Tyrosine Kinase Inhibitor Therapy in Pancreatic Tumors

“…The potential of PAI in assessing cancer response to neoadjuvant chemotherapy was also demonstrated by Lin et al. ( 40 ), where images of the breast were taken at three time points (once before, during, and after receiving chemotherapy), while the unaffected breast acted as a control. They observed noticeable decreases in the relative vascular density, entropy, and anisotropy of tumors treated with neoadjuvant therapy ( 40 ).…”

“…Using parameters gathered from the photoacoustic spectral gradient, relative StO 2 levels, and the skew angle of StO 2 distributions, Kim et al (39) were able to diagnose papillary thyroid cancer with a specificity of 93% and a sensitivity of 83%. The potential of PAI in assessing cancer response to neoadjuvant chemotherapy was also demonstrated by Lin et al (40), where images of the breast were taken at three time points (once before, during, and after receiving chemotherapy), while the unaffected breast acted as a control. They observed noticeable decreases in the relative vascular density, entropy, and anisotropy of tumors treated with neoadjuvant therapy (40).…”

“…( 40 ), where images of the breast were taken at three time points (once before, during, and after receiving chemotherapy), while the unaffected breast acted as a control. They observed noticeable decreases in the relative vascular density, entropy, and anisotropy of tumors treated with neoadjuvant therapy ( 40 ). While these studies demonstrate the clinical value of PAI, we further display the potential of PAI in oncology by using multiple hemodynamic parameters gathered during the chemotherapeutic regimen to detect non-responsiveness in suboptimal therapeutic regimens and especially predict tumor growth rates.…”

High-Frequency 3D Photoacoustic Computed Tomography Using an Optical Microring Resonator

“…Photoacoustic computed tomography (PACT), also referred to as optoacoustic tomography (OAT), is a hybrid biomedical imaging modality that combines optical excitation and ultrasound detection [1][2][3][4][5]. In PACT, threedimensional (3D) images can be reconstructed using a matrix array of ultrasound sensors without mechanical scanning [4][5][6]. These ultrasound sensors have been used in preclinical applications with high-frame rate and high resolution.…”

Non-Invasive Monitoring of Human Health by Photoacoustic Spectroscopy

“…These methods can be divided into optical methods and non-optical methods. Optical methods include Raman spectroscopy [ 16 , 17 , 18 ], photoacoustic (optoacoustic) spectroscopy (PAS) [ 19 , 20 , 21 ], near-infrared absorption spectroscopy [ 22 , 23 ], and photoacoustic imaging [ 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Non-optical methods are ultrasound [ 31 , 32 , 33 ] and microwave sensing [ 4 ].…”