Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA.
Translational Imaging Innovations, Hickory, NC, USA.
Transl Vis Sci Technol. 2021 Jul 1;10(8):5. doi: 10.1167/tvst.10.8.5.
To assess the performance of two spectral-domain optical coherence tomography-angiography systems in a natural model of hypoperfusion: the hibernating thirteen-lined ground squirrel (13-LGS).
Using a high-speed (130 kHz) OCT-A system (HS-OCT-A) and a commercial OCT (36 kHz; Bioptigen Envisu; BE-OCT-A), we imaged the 13-LGS retina throughout its hibernation cycle. Custom software was used to extract the superior, middle, and deep capillary plexus (SCP, MCP, and DCP, respectively). The retinal vasculature was also imaged with adaptive optics scanning light ophthalmoscopy (AOSLO) during torpor to visualize individual blood cells. Finally, correlative histology with immunolabeled or DiI-stained vasculature was performed.
During euthermia, vessel density was similar between devices for the SCP and MCP (P = 0.88, 0.72, respectively), with a small difference in the DCP (-1.63 ± 1.54%, P = 0.036). Apparent capillary dropout was observed during torpor, but recovered after forced arousal, and this effect was exaggerated in high-speed OCT-A imaging. Based on cell flux measurements with AOSLO, increasing OCT-A scan duration by ∼1000× would avoid the apparent capillary dropout artifact. High correspondence between OCT-A (during euthermia) and histology enabled lateral scale calibration.
While the HS-OCT-A system provides a more efficient workflow, the shorter interscan interval may render it more susceptible to the apparent capillary dropout artifact. Disambiguation between capillary dropout and transient ischemia can have important implications in the management of retinal disease and warrants additional diagnostics.
The 13-LGS provides a natural model of hypoperfusion that may prove valuable in modeling the utility of OCT-A in human pathologies associated with altered blood flow.
评估两种频域光相干断层扫描血管造影系统在低灌注天然模型中的性能：冬眠十三线地松鼠（13-LGS）。
使用高速（130 kHz）OCT-A 系统（HS-OCT-A）和商用 OCT（36 kHz；Bioptigen Envisu；BE-OCT-A），我们在 13-LGS 整个冬眠周期中对其视网膜进行成像。使用定制软件提取优势、中间和深层毛细血管丛（SCP、MCP 和 DCP）。在休眠期间还使用自适应光学扫描激光检眼镜（AOSLO）对视网膜血管成像，以可视化单个血细胞。最后，进行与免疫标记或 DiI 染色血管相关的组织学相关性。
在体温正常时，SCP 和 MCP 的设备之间血管密度相似（P = 0.88，0.72），DCP 略有差异（-1.63 ± 1.54%，P = 0.036）。在休眠期间观察到明显的毛细血管消失，但在强制唤醒后恢复，在高速 OCT-A 成像中这种效应更为明显。基于 AOSLO 的细胞通量测量，将 OCT-A 扫描持续时间增加约 1000 倍可以避免明显的毛细血管消失伪影。OCT-A（在体温正常时）和组织学之间的高度一致性使横向比例校准成为可能。
虽然 HS-OCT-A 系统提供了更有效的工作流程，但较短的扫描间隔可能使其更容易受到明显的毛细血管消失伪影的影响。区分毛细血管消失和短暂性缺血可能对视网膜疾病的管理具有重要意义，并需要额外的诊断。
杨逸轩
