435 N on-small cell lung cancer (NSCLC) accounts for approximately 75% to 85% of all newly diagnosed lung cancers (1). The optimal treatment of NSCLC relies on accurate disease staging, which is based on tumor size, regional nodal involvement, and the presence of metastasis. Correct evaluation of the presence or absence of metastases in mediastinal and hilar lymph nodes is a critical factor that may determine operability and long-term survival in patients with NSCLC. Surgical treatment can be

more »

... pected in 70% of patients with N0 stage and up to 24% of patients with N2 stage; however, surgery is generally not indicated in patients with N3 stage cancer (2). Although computed tomography (CT) is the most commonly used noninvasive imaging modality for the pre-operative evaluation of tumor size and the extent of invasion into adjacent structures, a number of reviews and meta-analyses have shown the limited reliability of CT in lymph node staging (3). The CT criteria for lymph node tumor involvement rely on the size or shape of the lymph nodes. Usually, 1 cm is used as the size criterion predicting tumor involvement in lymph nodes. However, normal sized lymph nodes may show metastases upon histological examination, and nodal enlargement may be due to reactive hyperplasia or other benign conditions (2). Rapid advances in multi-detector CT scanners allow a more detailed analysis of the lung parenchyma and mediastinal structures. As a consequence, nodal staging may be enhanced with CT. Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) has been reported to improve identification of nodal metastasis. FDG PET images may be more sensitive than CT because alterations in tissue metabolism generally precede anatomical changes (4). Integrated PET-CT provides information about anatomy and metabolism by combining morphological CT data and functional PET data (5). However, falsepositive PET-CT results in nodal staging have been shown in patients with co-existing inflammatory or infectious diseases, and PET-CT scanning may be unable to identify metastatic deposits in normal-sized lymph nodes because of its suboptimal spatial resolution (6, 7). Several retrospective and prospective studies have investigated the effectiveness of CT and PET-CT in pre-operative nodal staging of NSCLC (8-13). However, conflicting conclusions have been reported in these studies. Thus, the aim of our study was to retrospectively evaluate the effectiveness of integrated PET-CT in pre-operative staging of NSCLC in comparison with contrast enhanced CT (CE-CT) by using surgical and pathological findings as the reference standard. consecutive patients (50 males and 7 females; mean age, 59 years) underwent surgery for pathologically CHEST IMAGING RESULTS Forty-eight of the 57 patients (84%) had no lymph node involvement (N0), five (9%) were found to have N1 disease, and four (7%) had N2 disease. There was a significant difference between CE-CT and PET-CT for nodal staging of N0 disease (P < 0.05). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of hilar and mediastinal lymph node staging were 56%, 73%, 28%, 90%, and 70%, with CE-CT, respectively; and 78%, 92%, 64%, 96%, and 89% with PET-CT, respectively. CONCLUSION Integrated PET-CT is more accurate than CE-CT for lymph node staging in NSCLC. Key words: • positron emission tomography and computed tomography • lung cancer • lymph node Diagn Interv Radiol 2012; 18:435-440 Contrast enhanced CT versus integrated PET-CT in pre-operative nodal staging of NSCLC • 437 Volume 18 • Issue 5