TY - JOUR T1 - Quantitative Volumetric CT-Histogram Analysis in N-Staging of <sup>18</sup>F-FDG–Equivocal Patients with Lung Cancer JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 559 LP - 564 DO - 10.2967/jnumed.113.128504 VL - 55 IS - 4 AU - Paul Flechsig AU - Clemens Kratochwil AU - Lawrence H. Schwartz AU - Daniel Rath AU - Jan Moltz AU - Gerald Antoch AU - Claus-Peter Heussel AU - Michael Rieser AU - Arne Warth AU - Heike Zabeck AU - Hans-Ulrich Kauczor AU - Uwe Haberkorn AU - Frederik L. Giesel Y1 - 2014/04/01 UR - http://jnm.snmjournals.org/content/55/4/559.abstract N2 - Lung cancer often coexists with acute and chronic lung diseases such as chronic obstructive pulmonary disease. Therefore, mediastinal lymph nodes may be false-positive on 18F-FDG PET because of the inflammatory disease alone. Nevertheless, 18F-FDG PET/CT is the primary imaging modality used for staging patients with lung cancer, including nodal status. The purpose of this study was to evaluate whether volumetric CT histogram analysis can improve the characterization of lymph nodes on PET/CT staging of patients with lung cancer. Methods: Sixty histologically proven lymph nodes of 45 patients aged 43–76 y diagnosed with lung cancer were investigated. 18F-FDG PET/CT, contrast-enhanced CT, and nonenhanced CT were performed before surgery or biopsy as part of the clinical staging procedure. Lymph nodes were analyzed on the basis of the 18F-FDG standardized uptake value and volumetric CT histogram analysis. These findings were correlated to the gold standard of histopathology. Results: Histologic examination revealed 36 positive and 24 negative lymph nodes, which were also successfully analyzed by volumetric CT histogram. Median CT density was significantly higher for histologically positive lymph nodes (33.2 Hounsfield units [HU]; range, −29.8 to 59.1) than for histologically negative lymph nodes (10.1 HU; range, −21.0 to 87.4; P = 0.002). The incidence of malignancy was 88% above a cutoff value of 20 HU in the ten 18F-FDG–equivocal lymph nodes; the incidence of benign findings was 100% in the interval between −20 and +20 HU. Visual- and density-based analysis on contrast-enhanced CT failed to differentiate affected from nonaffected lymph nodes. Conclusion: Three-dimensional histogram analysis is a promising and potentially valuable imaging surrogate for N-stage stratification in patients with lung cancer with unclear glucose uptake during 18F-FDG PET imaging. In cases of equivocal 18F-FDG PET status, this technique might potentially bridge the diagnostic gap between noninvasive techniques and invasive lymph node sampling and could help improve the yield of core biopsies. ER -