Role of FDG-PET CT in differentiating adenocarcinomas from squamous cell carcinomas of the lung

Abstract

Lung cancer is the leading cause of cancer related deaths worldwide. The combination of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) has a great impact on the diagnosis, staging, and hence on the treatment plan and follow up of lung cancer patients. Maximum standardized uptake value (SUVmax) is a semi-quantitative index which is easily performed and the most widely used quantitative parameter for the analysis of 18F-FDG PET images and for the estimation of metabolic activity.to investigate the role of PET/ CT to differentiate between adenocarcinomas (AC) and squamous cell carcinomas (SCC) as the most common lung cancer by comparing their FDG uptake measured in the form of SUVmax.A retrospective observational study, conducted at Ain Shams University Hospitals- Radiology Department patients diagnosed with non-small cell lung cancer (NSCLC) and histopathologically proved to be adenocarcinoma or squamous cell carcinoma. All were investigated using PET/CT scans in the period between June 2017 to September 2019. SUVmax of the lesion were measured and statistically analyzed compared with the histopathological type.A total of 30 patients were evaluated with the age ranging from 31 to 81 years old, the mean was 56.9 years (SD ± 11.53). Among them 25 patients (83.3%) were males and 5 patients (16.7%) were females. Out of the 30 NSCLC patients included in the study, 18 patients (60%) were histopathologically diagnosed as AC and 12 patients (40%) were histopathologically diagnosed as SCC. The mean SUVmax of the 30 NSCLC lesions was 15.02±8.4 (range: 2-32.8).The mean SUVmax of AC lesions was 12.4±7.55 (range: 2-32.8), while the mean SUVmax of SCC lesions was 18.95±8.3 (range: 3.7-30.77). The mean SUVmax of lesions in patients with SCC was significantly higher than that of patients with AC using Wilcoxon-Mann-Whitney test (P = 0.04).SCC of the lung has higher SUVmax than AC of the lung and it can be used to differentiate between them using PET/CT.