Department of Nuclear Medicine, University Hospital Heidelberg, INF 400, 69120, Heidelberg, Germany.
Translational Lung Research Center Heidelberg, Member of the German Center for Lung Research DZL, Heidelberg, Germany.
Mol Imaging Biol. 2018 Dec;20(6):1044-1052. doi: 10.1007/s11307-018-1196-9.
Tumor delineation within an atelectasis in lung cancer patients is not always accurate. When T staging is done by integrated 2-deoxy-2-[F]fluoro-D-glucose ([F]FDG)-positron emission tomography (PET)/X-ray computer tomography (CT), tumors of neuroendocrine differentiation and slowly growing tumors can present with reduced FDG uptake, thus aggravating an exact T staging. In order to further exhaust information derived from [F]FDG-PET/CT, we evaluated the impact of CT density and maximum standardized uptake value (SUVmax) for the classification of different tumor subtypes within a surrounding atelectasis, as well as possible cutoff values for the differentiation between the primary tumor and atelectatic lung tissue.
Seventy-two patients with histologically proven lung cancer and adjacent atelectasis were investigated. Non-contrast-enhanced [F]FDG-PET/CT was performed within 2 weeks before surgery/biopsy. Boundaries of the primary within the atelectasis were determined visually on the basis of [F]FDG uptake; CT density was quantified manually within each primary and each atelectasis.
CT density of the primary (36.4 Hounsfield units (HU) ± 6.2) was significantly higher compared to that of atelectatic lung (24.3 HU ± 8.3; p < 0.01), irrespective of the histological subtype. The discrimination between different malignant tumors using density analysis failed. SUVmax was increased in squamous cell carcinomas compared to adenocarcinomas. Irrespective of the malignant subtype, a possible cutoff value of 24 HU may help to exclude the presence of a primary in lesions below 24 HU, whereas a density above a threshold of 40 HU can help to exclude atelectatic lung.
Density measurements in patients with lung cancer and surrounding atelectasis may help to delineate the primary tumor, irrespective of the specific lung cancer subtype. This could improve T staging and radiation treatment planning (RTP) without additional application of a contrast agent in CT, or an additional magnetic resonance imaging (MRI), even in cases of lung tumors of neuroendocrine differentiation or in slowly growing tumors with less avidity to [F]FDG.
在肺癌患者的肺不张中进行肿瘤勾画并不总是准确的。当通过整合的 2-脱氧-2-[F]氟-D-葡萄糖([F]FDG)-正电子发射断层扫描(PET)/X 射线计算机断层扫描(CT)进行 T 分期时，神经内分泌分化的肿瘤和生长缓慢的肿瘤可能表现为 FDG 摄取减少，从而加重准确的 T 分期。为了进一步利用[F]FDG-PET/CT 获得的信息，我们评估了 CT 密度和最大标准化摄取值(SUVmax)对周围肺不张中不同肿瘤亚型分类的影响，以及区分原发性肿瘤和肺不张组织的可能截断值。
对 72 例经组织学证实的肺癌合并相邻肺不张患者进行研究。在手术/活检前 2 周内进行非增强[F]FDG-PET/CT。在[F]FDG 摄取的基础上，通过视觉确定原发性肿瘤在肺不张中的边界；手动在每个原发性肿瘤和每个肺不张中量化 CT 密度。
原发性肿瘤的 CT 密度(36.4 亨氏单位(HU)±6.2)明显高于肺不张(24.3 HU±8.3；p<0.01)，与组织学亚型无关。使用密度分析区分不同恶性肿瘤的方法失败。与腺癌相比，鳞状细胞癌的 SUVmax 增加。无论恶性肿瘤亚型如何，24 HU 的可能截断值可能有助于排除 24 HU 以下病变存在原发性肿瘤，而密度高于 40 HU 的阈值可有助于排除肺不张。
在肺癌合并周围肺不张的患者中，密度测量可能有助于描绘原发性肿瘤，而与特定的肺癌亚型无关。这可以改善 T 分期和放射治疗计划(RTP)，而无需在 CT 中额外应用造影剂，或在存在神经内分泌分化的肺癌肿瘤或 FDG 摄取较少的生长缓慢的肿瘤的情况下，无需额外进行磁共振成像(MRI)。
