We describe the ongoing development and performance of a high-pulse-energy wavelength-cycling laser system for three-dimensional optoacoustic tomography of the breast. Joule-level energies are desired for achieving the required penetration depths while maintaining safe fluence levels. Wavelength cycling provides a pulse sequence which repeatedly alternates between two wavelengths (approximately 756 and 797 nm) that provide differential imaging. This improves co-registration of captured differential images and quantification of blood oxygen saturation. New design features have been developed for and incorporated into a clinical prototype laser system, to improve efficacy and ease of use in the clinic. We describe the benefits of these features for operation with a clinical pilot optoacoustic / ultrasound dual-modality three-dimensional imaging system.
X-ray-induced acoustic computed tomography (XACT) has emerged as a promising imaging modality with broad applications in both biomedicine and nondestructive testing. The previous XACT imaging systems require thousands of averages to achieve reasonable images. Here, we report the experimental demonstration of single-shot XACT imaging of a metal object using a single-shot 50 ns x-ray pulse. A two-stage dedicated amplification and a 128-channel parallel data acquisition configuration were introduced for XACT imaging to enable sufficient acoustic signal amplification and maintain an overall low noise level for single-shot XACT imaging. Details of the system design are presented; the improved signal-to-noise ratio (>23 dB) and image reconstruction have been demonstrated with a ring ultrasound transducer array imaging system. The study paves the way for realizing real-time XACT imaging and its potential applications in image-guided intervention.
.
Significance
To effectively study preclinical animal models, medical imaging technology must be developed with a high enough resolution and sensitivity to perform anatomical, functional, and molecular assessments. Photoacoustic (PA) tomography provides high resolution and specificity, and fluorescence (FL) molecular tomography provides high sensitivity; the combination of these imaging modes will enable a wide range of research applications to be studied in small animals.
Aim
We introduce and characterize a dual-modality PA and FL imaging platform using
in vivo
and phantom experiments.
Approach
The imaging platform’s detection limits were characterized through phantom studies that determined the PA spatial resolution, PA sensitivity, optical spatial resolution, and FL sensitivity.
Results
The system characterization yielded a PA spatial resolution of
in the transverse plane and
in the longitudinal axis, a PA sensitivity detection limit not less than that of a sample with absorption coefficient
, an optical spatial resolution of
in the vertical axis and
in the horizontal axis, and a FL sensitivity detection limit not
concentration of IR-800. The scanned animals displayed in three-dimensional renders showed high-resolution anatomical detail of organs.
Conclusions
The combined PA and FL imaging system has been characterized and has demonstrated its ability to image mice
in vivo
, proving its suitability for biomedical imaging research applications.
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