用于深层组织分子成像的小型化光声/超声内窥成像探头

Miniaturized photoacoustic/ultrasound endoscopic imaging probe for molecular imaging of deep tissues

结直肠癌是全球癌症死亡的主要原因之一,常用的光学或超声消化道内镜仍然存在穿透深度低、对比度差、功能/分子成像能力不足等问题.本文介绍了一种小型化的手持式光声/超声双模态内窥探头,旨在克服现有技术在穿透深度和分子成像能力方面的限制.实验结果表明,该探头在组织12 mm深度下分别达到了345μm的光声横向分辨率和185μm的超声横向分辨率,并具有良好的对复杂结构目标成像的能力.本文还利用泵浦探测技术排除了血液背景的干扰,实现了肿瘤深层组织内亚甲基蓝分子的高特异性成像.这种小型化手持式光声/超声双模态内窥探头兼具大成像深度、高空间分辨和高特异性分子成像的特点,有望成为结直肠癌等消化道肿瘤诊断的重要工具,为早期诊断和治疗监测提供强有力的支持.

Colorectal cancer is one of the leading causes of cancer-related deaths worldwide.Traditional gastrointestinal endoscopes for colorectal cancer mainly rely on optical endoscope and ultrasound endoscope.Owing to significant light scattering in tissues the optical endoscope is limited to superficial tissue imaging,while the ultrasound endoscope,despite deeper penetration,provides limited molecular imaging capabilities.In this work,we build a miniaturized handheld photoacoustic/ultrasound dual-modality endoscopic probe to address these problems.It has a small size of 8 mm,and presents the dual advantages of high penetration depth and superior molecular imaging capability,marking a significant advancement over traditional methods.Results show that this probe achieves a high lateral resolution of 345μm for photoacoustic imaging and 185μm for ultrasound imaging at a depth of 12 mm within tissues.It also exhibits the ability to effectively image complex structural targets,as demonstrated by the imaging of a phantom with an embedded metal mesh.Furthermore,the probe adopts an innovative pump-probe method,which effectively mitigates interference from blood and other background tissues,thereby achieving high-specificity photoacoustic molecular imaging.This ability is first confirmed by imaging the distribution of methylene blue(MB)in a phantom,and then by observing the distribution of MB in the depth of tumor in mice.This handheld photoacoustic/ultrasound endoscopic probe has the advantages of small size,high penetration depth,high spatial resolution,and superior molecular imaging ability,and is expected to become an important diagnostic tool for colorectal cancer and other gastrointestinal cancer.This study can provide strong support for early diagnosis and treatment monitoring,potentially revolutionizing the detection and management of these diseases.