title: Overestimation ratio of hepatic lesion size on spiral CT arterial portography: an indicator of malignancy.
abstract: OBJECTIVE
  To assess the reliability of the size-overestimation ratio obtained from spiral CT arterial portography (CTAP) and spiral equilibrium-phase CT (EPCT) in distinguishing malignant focal hepatic lesions from benign ones.
  
  
  METHODS
  The CTAP images and EPCT images obtained five minutes after CTAP in 39 patients with focal hepatic lesions were retrospectively analyzed. Fifty-eight lesions (hepatocellular carcinoma [HCC], 33; metastasis, 10; liver cyst, 10; cavernous hemangioma, 2; adenomatous hyperplasia [AH], 2; focal nodular hyperplasia [FNH], 1) had their sizes measured on CTAP and EPCT images using the calipers on the CT console.
  
  
  RESULTS
  The size-overestimation ratios (CTAP/EPCT) were 1.24+/-0.15 in HCC, 1.28+/-0.26 in metastasis, 1.02+/-0.23 in liver cyst, 0.98+/-0.34 in cavernous hemangioma, 0.94+/-0.39 in AH, and 1.00 in FNH. Mean size-overestimation ratios for benign- and malignant-lesion groups were 1.00+/-0.37 and 1.25+/-0.18, respectively (p < 0.0001). When a cutoff level was set at 1.05, sensitivity and specificity for malignancy were 91% and 93%, respectively.
  
  
  CONCLUSIONS
  In comparison with EPCT, CTAP significantly overestimates the size of malignant hepatic tumors. This phenomenon may be an indicator of hepatic malignancy.
authors.affiliation: Department of Radiology, Gifu University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kanematsu
authors.forename: H
authors.initials: H
authors.lastname: Hoshi
authors.forename: T
authors.initials: T
authors.lastname: Imaeda
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.forename: Y
authors.initials: Y
authors.lastname: Nishigaki
authors.forename: Y
authors.initials: Y
authors.lastname: Nandate
authors.forename: R
authors.initials: R
authors.lastname: Yokoyama
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001706:Biopsy; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005500:Follow-Up Studies; D006801:Humans; D008107:Liver Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011172:Portography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed