title: Improved Diagnostic Accuracy Using Arterial Phase CT for Lateral Cervical Lymph Node Metastasis from Papillary Thyroid Cancer.
abstract: Contrast-enhanced CT protocols for papillary thyroid cancer are yet to be optimized. Our aim was to compare the diagnostic accuracy of arterial phase CT and delayed-phase CT protocols for lateral cervical lymph node metastasis from papillary thyroid carcinoma by using the lymph node tissue attenuation.
  
  
  
  This retrospective study included 327 lateral cervical lymph nodes (177 metastatic and 150 benign) from 131 patients with papillary thyroid carcinoma (107 initially diagnosed and 24 recurrences). Patients underwent CT by using 1 of 3 protocols: a 70-second (A) or a 35-second (B) delay with 100 mL of iodinated IV contrast or a 25-second delay with 75 mL of IV contrast (C). Two readers independently measured and compared lymph node tissue attenuation between metastatic and benign lymph nodes. An area under the receiver operating characteristic curve analysis was performed to differentiate metastatic and benign lymph nodes after multiple comparison correction for clustered data and was compared across the protocols.
  
  
  
  The difference in mean lymph node tissue attenuation between metastatic and benign lymph nodes was maximum in protocol C (P< .001 for both readers). Protocol C showed the highest diagnostic performance (area under the receiver operating characteristic curve, 0.88-0.92) compared with protocol A (area under the receiver operating characteristic curve, 0.73-0.74,P< .001 for both readers) and B (area under the receiver operating characteristic curve, .63-0.65,P< .01 for both readers). The sensitivity, specificity, positive predictive value, and negative predictive value of lymph node tissue attenuation by using a 99-HU cutoff value were 83%-87%, 93.7%-97.9%, 95.1%-97.3%, and 81.2%-87%.
  
  
  
  A combination of 25-second delay CT and 75 mL of iodinated IV contrast can improve the diagnostic accuracy for lateral lymph node metastasis from papillary thyroid carcinoma compared with a combination of a 35- or 70-second delay with 100-mL of iodinated IV contrast.
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: J E
authors.identifier: 0000-0002-4419-4682
authors.initials: JE
authors.lastname: Park
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. jeonghlee@amc.seoul.kr.
authors.forename: J H
authors.identifier: 0000-0002-0021-4477
authors.initials: JH
authors.lastname: Lee
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: K H
authors.identifier: 0000-0003-1599-8881
authors.initials: KH
authors.lastname: Ryu
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: H S
authors.identifier: 0000-0003-0707-1875
authors.initials: HS
authors.lastname: Park
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: M S
authors.identifier: 0000-0003-1141-9555
authors.initials: MS
authors.lastname: Chung
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: H W
authors.identifier: 0000-0002-3403-1599
authors.initials: HW
authors.lastname: Kim
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Y J
authors.identifier: 0000-0001-7098-5042
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: J H
authors.identifier: 0000-0003-0480-4754
authors.initials: JH
authors.lastname: Baek
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy / Q000379:methods; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology*; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011237:Predictive Value of Tests; D012372:ROC Curve; D011874:Radiometry; D015203:Reproducibility of Results; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D018084:Ultrasonography, Interventional