title: Can Parameters Other than Minimal Axial Diameter in MRI and PET/CT Further Improve Diagnostic Accuracy for Equivocal Retropharyngeal Lymph Nodes in Nasopharyngeal Carcinoma?
abstract: OBJECTIVE
  Minimal axial diameter (MIAD) in magnetic resonance imaging (MRI) was recognized as the most useful parameter in diagnosing lateral retropharyngeal lymph (LRPL) nodes in nasopharyngeal carcinoma (NPC). This study aims to explore the additional nodal parameters in MRI and positron emission tomography-computed tomography for increasing the prediction accuracy.
  
  
  METHODS
  A total of 663 LRPL nodes were retrospectively collected from 335 patients with NPC. The LRPL nodes ascertained on follow-up MRI were considered positive for metastases. First, the optimal cutoff value of each parameter was derived for each parameter. In addition, neural network (NN) nodal evaluation was tested for all combinations of three parameters, namely MIAD, maximal axial diameter (MAAD), and maximal coronal diameter (MACD). The optimal approach was determined through brute force attack, and the results of two methods were compared using a bootstrap sampling method. Second, the mean standard uptake value (NSUVmean) was added as the fourth parameter and tested in the same manner for 410 nodes in 219 patients.
  
  
  RESULTS
  In first and second analysis, the accuracy rate (percentage) for the MIAD was 89.0% (590/663) and 89.0% (365/410), with the optimal cutoff values being 6.1 mm and 6.0 mm, respectively. With the combination of all three and four parameters, the accuracy rate of the NN was 89% (288/332) and 88.8% (182/205), respectively. In prediction, the optimal combinations of the three and four parameters resulted in correct identification of three (accuracy: 593/663, 89.4%) and six additional nodes (371/410, 90.5%), representing 4% (3/73) and 13.3% (6/45) decreases in incorrect prediction, respectively.
  
  
  CONCLUSIONS
  NPC LRPL nodes with an MIAD ≥ 6.1 mm are positive. Among nodes with an MIAD < 6.1 mm, if the NSUVmean ≥ 2.6 or MACD ≥ 25 mm and MAAD ≥ 8 mm, the nodes are positive; otherwise, they are negative.
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan, Taiwan.|Department of Nursing, Min-Hwei Junior College of Health Care Management, Tainan, Taiwan.
authors.forename: Yu-Wen
authors.identifier: http://orcid.org/0000-0002-4588-2591
authors.initials: YW
authors.lastname: Wang
authors.affiliation: Division of Nuclear Medicine, Department of Medical Imaging, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Chin-Shun
authors.initials: CS
authors.lastname: Wu
authors.affiliation: Cancer Center, Foshan Hospital, Sun Yat-sen University, Foshan, People's Republic of China.
authors.forename: Guo-Yi
authors.initials: GY
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Kuo-Sheng
authors.initials: KS
authors.lastname: Cheng
authors.affiliation: Department of Nuclear Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Wei-Jen
authors.initials: WJ
authors.lastname: Yao
authors.affiliation: Department of Medical Imaging, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
authors.forename: Yu-Kang
authors.initials: YK
authors.lastname: Chang
authors.affiliation: Department of Medical research, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Tsair-Wei
authors.initials: TW
authors.lastname: Chien
authors.affiliation: Department of Radiation Oncology, Chi-Mei Foundation Medical Center, Tainan, Taiwan.|Department of Optometry, Chung Hwa University of Medical Technology, Tainan, Taiwan.
authors.forename: Li-Ching
authors.initials: LC
authors.lastname: Lin
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.|Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Keng-Ren
authors.initials: KR
authors.lastname: Lin
mesh_terms: D002277:Carcinoma; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging*; D009305:Nasopharynx / Q000000981:diagnostic imaging*; D009367:Neoplasm Staging / Q000379:methods; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D012189:Retrospective Studies