Objective: To develop dual-modality Photoacoustic(PA)/Ultrasound(US) system based on clinical US machine and performed imaging study of in vivo human superficial lesions.
Methods: A dual-modality PA/US system was developed based on a high-end clinical US machine with a handheld probe for US/PA dual modality imaging, equipped with multi-wavelength laser source. Twenty-three patients were enrolled consecutively from the outpatients and inpatients of Peking Union Medical College Hospital (PUMCH) from Dec. 15th 2016 to Apr.15th 2017. All the patients underwent ultrasound examinations including both gray scale and color Doppler flow imaging ultrasound (CDFI) to evaluate the morphological and vascular information of the lesions. PA/US imaging was performed right after CDFI, the CDFI and the PA/US dual imaging information of each case were compared.
Results: The laser source for PAI generates multi-wavelength laser pulses at 10Hz. Therefore, deoxyhemoglobin and hematoglobulin in tumor vasculature, which serve as different optical absorbers at specific wavelengths, can be evaluated and compared through PAI. PA/US dual modality imaging was performed in 23 cases, including 10 thyroid lesions, 10 breast lesions, and 3 soft tissue endometriosis lesions. All of the lesions performed surgery with pathology confirmed diagnosis. Our PA/US dual modality imaging system showed high quality gray scale ultrasonic and dual-modality fusion images. According to the results, significant differences exist between PAI and CDFI. PAI could reveal some blood vessels that were not sensitive for Doppler ultrasound. PAI proved the ability of imaging both the peripheral and intra-nodular vessels of human superficial lesions, as well as detecting the difference of oxygen saturation between benign and malignant tumor.
Conclusion: Our study demonstrated that photoacoustic imaging could provide important complementary information for traditional ultrasound in superficial lesion examination, which has a great potential for clinical diagnosis.