title: Ratio of Lymph Node to Primary Tumor SUV on PET/CT Accurately Predicts Nodal Malignancy in Non-Small-Cell Lung Cancer.
abstract: Thoracic lymph nodes with marginally elevated maximum standardized uptake value (SUVmax) on PET/CT a diagnostic challenge in staging non-small-cell lung cancer. We evaluated the ratio of lymph node to primary tumor SUVmax (SUVN/T) in predicting nodal malignancy among 132 sampled nodes from 85 patients both a primary tumor SUVmax > 2.5 and LN SUVmax 2.0 to 6.0. SUVN/T was more accurate than SUVmax for this subset of patients.
  
  
  BACKGROUND
  Among non-small-cell lung cancers with appreciable functional activity, positron emission tomography/computed tomography (PET/CT) is the most accurate imaging modality for clinical staging. However, lymph nodes (LN) with marginally elevated standardized uptake value (SUV) present a diagnostic challenge. In this retrospective study, we hypothesized that normalizing the LN SUV by using the ratio of the LN to primary tumor SUVmax (SUVN/T) may be a better predictor of nodal malignancy than using SUVmax alone for nodes with low to intermediate SUV.
  
  
  METHODS
  We identified 172 patients with newly diagnosed non-small-cell lung cancer who underwent pathologic LN staging and PET/CT within 31 days before biopsy. Receiver operating characteristic curves with area under the curve (AUC) calculations were used to evaluate SUVmax and SUVN/T for their ability to predict nodal malignancy for both the entire cohort of 504 LNs and a subset of 132 LNs from 85 patients who had both primary tumor SUVmax > 2.5 and LN SUVmax 2.0 to 6.0.
  
  
  RESULTS
  In patients with primary tumor SUVmax > 2.5 and LN SUVmax 2.0 to 6.0, SUVN/T was significantly more accurate in predicting nodal malignancy (AUC, 0.846; 95% confidence interval, 0.775-0.917) than SUVmax (AUC, 0.653; 95% confidence interval, 0.548-0.759). The optimal cutoff value of SUVN/T to predict nodal malignancy was 0.28 (90% sensitivity, 68% specificity). Sensitivity was > 95% for SUVN/T < 0.21, whereas specificity was > 95% for SUVN/T > 0.50.
  
  
  CONCLUSIONS
  The ratio of LN SUV to primary tumor SUV on PET/CT is more accurate than SUVmax when assessing nodes of low to intermediate SUV.
authors.affiliation: Department of Radiation Oncology, West Virginia University, Morgantown, WV. Electronic address: malcolm.mattes@gmail.com.
authors.forename: Malcolm D
authors.initials: MD
authors.lastname: Mattes
authors.affiliation: Department of Radiation Oncology, New York Methodist Hospital, Brooklyn, NY.
authors.forename: Ariella B
authors.initials: AB
authors.lastname: Moshchinsky
authors.affiliation: Department of Radiation Oncology, New York Methodist Hospital, Brooklyn, NY.
authors.forename: Salma
authors.initials: S
authors.lastname: Ahsanuddin
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Nabil P
authors.initials: NP
authors.lastname: Rizk
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Amanda
authors.initials: A
authors.lastname: Foster
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Wu
authors.affiliation: Department of Radiation Oncology, New York Methodist Hospital, Brooklyn, NY.
authors.forename: Hani
authors.initials: H
authors.lastname: Ashamalla
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Weber
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Andreas
authors.initials: A
authors.lastname: Rimner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis*; D008198:Lymph Nodes / Q000378:metabolism; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: Lymph node; NSCLC; PET; Ratio; Staging