Funovics Martin A, Alencar Herlen, Montet Xavier, Weissleder Ralph, Mahmood Umar
Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
Gastrointest Endosc. 2006 Oct;64(4):589-97. doi: 10.1016/j.gie.2006.02.048.
Molecularly targeted fluorescent probes are currently being developed to improve the endoscopic detection of intestinal pathologic conditions.
We report on the development and testing of a novel multichannel microendoscope capable of quantitatively reporting such probes simultaneously at different wavelengths in real time. We assessed the feasibility of detecting and quantifying beacons that can be activated by protease and correlating imaging with disease state.
The microendoscope consisted of a 20-gauge fiberoptic catheter and dichroic beam splitters that simultaneously display visible light, 700 nm and 800 nm near infrared (NIR) fluorescent light. NIR interchannel separation was tested on in vitro phantoms. Two mouse models were used (Apcmin(+/-) mice for colonic adenomas and CT26 murine colon cancer). A perfusion probe and one activated by protease at a separate wavelength were injected before endoscopic evaluation.
The microendoscope fluorochrome detection limit was approximately 10 fmol; ratio imaging in the NIR was accurate (+/-8% of true probe concentration between 0.3 to 100 microg/ml of a protease sensor). Both colonic adenomas and adenocarcinomas were clearly visible in the NIR channel on protease probe administration in live mice. Ratio imaging of protease activity/perfusion increased from healthy colon to adenomas to adenocarcinomas.
Evaluation across additional spontaneous tumor models may provide more data on the translation of these findings.
Our data show the feasibility of multichannel microendoscopic imaging of molecular targets in vivo and that ratio imaging may provide a novel means for characterizing colonic lesions. When scaled up clinically, this could aid in increasing lesion detection and quantitative assessment of distinct molecular markers.
目前正在开发分子靶向荧光探针，以改善肠道病理状况的内镜检测。
我们报告一种新型多通道微型内窥镜的开发和测试，该内窥镜能够实时在不同波长下同时定量报告此类探针。我们评估了检测和定量可被蛋白酶激活的信标以及将成像与疾病状态相关联的可行性。
微型内窥镜由一根20号光纤导管和二向色分束器组成，可同时显示可见光、700纳米和800纳米近红外（NIR）荧光。在体外模型上测试了近红外通道间的分离。使用了两种小鼠模型（用于结肠腺瘤的Apcmin(+/-)小鼠和CT26小鼠结肠癌）。在内镜评估前注射一种灌注探针和一种在单独波长下被蛋白酶激活的探针。
微型内窥镜荧光染料检测限约为10飞摩尔；近红外比率成像准确（在蛋白酶传感器浓度为0.3至100微克/毫升时，与真实探针浓度的偏差为±8%）。在给活小鼠注射蛋白酶探针后，结肠腺瘤和腺癌在近红外通道中均清晰可见。从健康结肠到腺瘤再到腺癌，蛋白酶活性/灌注的比率成像增加。
对更多自发肿瘤模型进行评估可能会提供关于这些发现转化的更多数据。
我们的数据表明体内分子靶点多通道微型内窥镜成像的可行性，并且比率成像可能为表征结肠病变提供一种新方法。在临床上扩大规模时，这有助于增加病变检测和对不同分子标记物的定量评估。
