Background Lymph node staging is a critical component in managing lung cancer, as it determines prognosis and guides treatment decisions. Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has emerged as a highly sensitive and specific imaging modality for evaluating nodal involvement, surpassing conventional imaging techniques. Therefore, this study evaluated the diagnostic accuracy of PET-CT in lymph nodal staging of lung cancer, using histopathology as the gold standard. Methodology This cross-sectional study was conducted at the Radiology and PET Scan Department, Jinnah Postgraduate Medical Centre (JPMC), Karachi, over six months, from January 28, 2021, to July 28, 2021, using a non-probability consecutive sampling. It included 127 biopsy-proven lung cancer patients aged 21-80 years. FDG PET-CT scans were evaluated by an experienced radiologist, with findings compared against histopathology results after surgery and biopsy. Using IBM SPSS Statistics for Windows, Version 22 (Released 2013
IBM Corp., Armonk, New York, United States), data analysis included calculating the sensitivity, specificity, and predictive values of FDG PET-CT for nodal metastasis, with histopathology as the gold standard. Results The study findings showed that out of 127 lung cancer patients, with a mean age of 54.14 ± 10.41 years, 99 (78.0%) were male, and 111 (87.4%) were aged >
40 years. Symptoms persisted for a mean of 12.04 ± 6.82 weeks, and 88 (69.30%) had standardized uptake value (SUV)>
3.0. Nodal staging showed N1 nodes in 64 (50.40%), N2 in 37 (29.10%), and N3 in 26 (20.50%). PET-CT detected nodal metastasis in 89 (70.18%) of cases, with histopathology confirming metastasis in 95 (74.88%). PET-CT achieved a sensitivity of 91.50%, specificity of 93.75%, positive predictive value (PPV) of 97.75%, and negative predictive value (NPV) of 78.95%. The overall accuracy of PET-CT was 92.13%, with a strong correlation to histopathology, emphasizing its reliability in staging nodal metastasis. Conclusion This study concluded the high diagnostic accuracy of PET-CT in detecting nodal metastasis in lung cancer, with an overall accuracy of 92.13%. PET-CT demonstrated excellent sensitivity (91.50%) and specificity (93.75%). These results confirm PET-CT as a reliable imaging modality for lymph nodal staging.