Department of Thoracic Surgery, Perelman School of Medicine at University of Pennsylvania, 3400 Spruce Street, 6 White Building, Philadelphia, PA, 19104, USA.
Department of Pathology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.
Eur J Nucl Med Mol Imaging. 2022 Nov;49(13):4406-4418. doi: 10.1007/s00259-022-05912-8. Epub 2022 Jul 25.
Intraoperative molecular imaging (IMI) with folate-targeted NIR tracers has been shown to improve lesion localization in more than 80% of lung adenocarcinomas. However, mucinous adenocarcinomas (MAs) and invasive mucinous adenocarcinomas (IMAs) of the lung, which are variants of adenocarcinoma, appear to have decreased fluorescence despite appropriate folate receptor expression on the tumor surface. We hypothesized that the etiology may be related to light excitation and emission through non-Newtonian fluid (mucin) produced by goblet and columnar cancer cells.
Intraoperative data for 311 subjects were retrospectively reviewed from a prospectively collected 6-year database. For standardization, all patients underwent infusion of the same targeted molecular optical contrast agent (pafolacianine, folate receptor-targeted NIR fluorochrome) for lung cancer resections. Then, the ratio of the mean fluorescence intensity of the tumors and background tissues (TBR) was calculated. Tumors were examined for mucin, FRa, FRb, and immunofluorescent tracer uptake by a board-certified pathologist. The optical properties of mucin analyzed by imaging software were used to create in vitro gel models to explore the effects on NIR tracer fluorescence intensity.
A large proportion (192, 62%) of the patients were female, with an average of 62.8 years and a 34-year mean pack smoking history. There were no severe (Clavien-Dindo > III) complications related to pafolacianine infusion. A total of 195 lesions in the study were adenocarcinomas, of which 19 (6.1%) were of the mucinous subtype. A total of 14/19 of the patients had a smoking history, and more than 74% of the IMA lesions were in the lower lobes. IMA lesions had a lower in situ TBR than nonmucinous adenocarcinomas (2.64 SD 0.23) vs (3.45 SD 0.11), respectively (p < 0.05). Only 9/19 (47%) were localized in situ. Tumor bisection and removal of mucin from IMAs significantly increased pafolacianine fluorescence, with resultant TBR not being significantly different from the control group (4.67 vs 4.89) (p = 0.19). Of the 16 lesions that underwent FR expression analysis, 15/16 had FR presence on cancer cells or tumor-associated macrophages in the tumor microenvironment. There was no statistically significant difference in fluorescence intensity during immunofluorescence analysis (4.99 vs 5.08) (p = 0.16). Physical removal of mucin from IMAs improved the TBR from 3.11 to 4.67 (p < 0.05). In vitro analysis of the impact of synthetic non-Newtonian fluid (agarose 0.5%) on NIR tracer fluorescence showed a decrease in MFI by a factor of 0.25 regardless of the concentration for each 5 mm thickness of mucin.
The mucinous subtype of lung adenocarcinomas presents a unique challenge in pafolacianine-targeted IMI-guided resections. The presence of non-Newtonian fluids presents a physical barrier that dampens the excitation of the tracer and fluorescence emission detected by the camera. Knowledge of this phenomenon can allow the surgeon to critically analyze lesion fluorescence parameters during IMI-guided lung cancer resections.
用叶酸靶向近红外示踪剂进行术中分子成像（IMI）已被证明可提高 80%以上肺腺癌患者的病变定位。然而，肺黏液性腺癌（MAs）和侵袭性黏液性腺癌（IMAs）作为腺癌的一种变体，尽管肿瘤表面有适当的叶酸受体表达，但荧光似乎减少了。我们假设病因可能与杯状和柱状癌细胞产生的非牛顿流体（黏液）的光激发和发射有关。
从一个前瞻性收集的 6 年数据库中回顾性分析了 311 名受试者的术中数据。为了标准化，所有患者均接受了相同的靶向分子光学对比剂（pafolacianine，叶酸受体靶向近红外荧光染料）用于肺癌切除术的输注。然后计算肿瘤和背景组织的平均荧光强度比（TBR）。由经过认证的病理学家检查肿瘤中的黏液、FRa、FRb 和免疫荧光示踪剂摄取情况。使用成像软件分析黏液的光学特性，以创建体外凝胶模型，以探索其对近红外示踪剂荧光强度的影响。
很大一部分（192 例，62%）患者为女性，平均年龄为 62.8 岁，平均吸烟史为 34 年。与 pafolacianine 输注相关的没有严重（Clavien-Dindo > III）并发症。在研究中共有 195 个病变为腺癌，其中 19 个（6.1%）为黏液型。共有 14/19 的患者有吸烟史，超过 74%的 IMA 病变位于下叶。IMA 病变的原位 TBR 低于非黏液性腺癌（2.64 SD 0.23）分别为（3.45 SD 0.11）（p < 0.05）。只有 9/19（47%）在原位定位。肿瘤切开和黏液从 IMA 中去除显著增加了 pafolacianine 的荧光，导致 TBR 与对照组无显著差异（4.67 vs 4.89）（p = 0.19）。在 16 个进行 FR 表达分析的病变中，15/16 在肿瘤微环境中的癌细胞或肿瘤相关巨噬细胞中存在 FR。在免疫荧光分析中，荧光强度没有统计学差异（4.99 vs 5.08）（p = 0.16）。从 IMA 中物理去除黏液可将 TBR 从 3.11 提高到 4.67（p < 0.05）。对合成非牛顿流体（琼脂糖 0.5%）对近红外示踪剂荧光影响的体外分析表明，无论每个 5 毫米厚度的黏液的浓度如何，MFI 都会减少 0.25 倍。
肺腺癌的黏液型在 pafolacianine 靶向 IMI 引导切除中提出了一个独特的挑战。非牛顿流体的存在构成了一个物理障碍，削弱了示踪剂的激发和相机检测到的荧光发射。了解这一现象可以使外科医生在 IMI 引导的肺癌切除术中对病变荧光参数进行批判性分析。
