Feasibility of interstitial Doppler optical coherence tomography for in vivo detection of microvascular changes during photodynamic therapy
Feasibility of interstitial Doppler optical coherence tomography for in vivo detection of microvascular changes during photodynamic therapy
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DOI：
10.1002/lsm.20387
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发表时间：
2006-09-01
影响因子：
2.4
通讯作者：
Yang, Victor X. D.
中科院分区：
文献类型：
--
作者：
Li, Heng;Standish, Beau A.;Yang, Victor X. D.
前言：多谱勒光学相干断层成像(DOCT)是一种新兴的成像手段，它提供了接近组织学分辨率和亚毫米/秒速度灵敏度的亚表面微结构和微血管组织图像。对于某些应用，OCT的一个关键缺点是其穿透深度较浅(1-3 mm)。这从根本上限制了DOCT成像只能在透明、近表面、血管内或腔内解剖部位进行。因此，间质多普勒OCT(IS-DOCT)被开发用于微创体内成像，在更深的地方进行微血管和微结构成像，提供进入深层实体器官的通道。利用大鼠前列腺癌移植瘤模型，评价IS-DOCT监测光动力疗法(PDT)引起的肿瘤深层微血管变化的可行性。材料和方法：DOCT间质探头是用22G(直径类似于0.7 mm)针构建的，表面有回声，用于增强超声成像。探头的透镜由一个梯度折射率光纤组成，融合在一个角度抛光的无芯尖端，以允许侧视扫描。然后将透镜融合拼接到单模光纤上，该光纤通过导管连接到线性扫描器上，并沿着针的纵轴驱动，以产生2D亚表面DOCT图像。所产生的IS-Doct系统被用来监测肿瘤块深处微血管的变化，以响应PDT在大鼠Dunning前列腺癌异种移植模型中的反应。光敏剂剂量为12.5 mg/kg，波长为635 nm，功率为40 mW，总光剂量为76J/cm(2)。结果：IS-Doct能够检测体内微血管形成并记录PDT引起的变化。治疗过程中检测到的血管横截面积减少，治疗后部分恢复。结论：IS-DOCT是一种潜在的实时可视化和监测PDT治疗进展的有效工具。这一能力可能在阐明PDT在肿瘤中的机制、治疗前计划、治疗优化的反馈控制、确定治疗终点和治疗后评估方面发挥重要作用。
Introduction: Doppler optical coherence tomography (DOCT) is an emerging imaging modality that provides subsurface microstructural and microvascular tissue images with near histological resolution and sub-mm/ second velocity sensitivity. A key drawback of OCT for some applications is its shallow (1-3 mm) penetration depth. This fundamentally limits DOCT imaging to transparent, near-surface, intravascular, or intracavitary anatomical sites. Consequently, interstitial Doppler OCT (IS-DOCT) was developed for minimally-invasive in vivo imaging of microvasculature and microstructure at greater depths, providing access to deep-seated solid organs. Using Dunning prostate cancer in a rat xenograft model, this study evaluated the feasibility of IS-DOCT monitoring of microvascular changes deep within a tumor caused by photodynamic therapy (PDT).Materials and Methods: The DOCT interstitial probe was constructed using a 22 G (diameter similar to 0.7 mm) needle, with an echogenic surface finish for enhanced ultrasound visualization. The lens of the probe consisted of a gradient-index fiber, fusion spliced to an angle-polished coreless tip to allow side-view scanning. The lens was then fusion spliced to a single-mode optical fiber that was attached to the linear scanner via catheters and driven along the longitudinal axis of the needle to produce a 2D subsurface DOCT image. The resultant IS-DOCT system was used to monitor microvascular changes deep within the tumor mass in response to PDT in the rat xenograft model of Dunning prostate cancer. Surface PDT was delivered at 635 nm with 40 mW of power, for a total light 2 dose of 76 J/cm(2), using 12.5 mg/kg of Photofrin as the photosensitizer dose.Results: IS-DOCT demonstrated its ability to detect microvasculature in vivo and record PDT-induced changes. A reduction of detected vascular cross sectional area during treatment and partial recovery post-treatment were observed.Conclusions: IS-DOCT is a potentially effective tool for real-time visualization and monitoring of the progress of PDT treatments. This capability may play an important role in elucidating the mechanisms of PDT in tumors, pre-treatment planning, feedback control for treatment optimization, determining treatment endpoints and posttreatment assessments.