title: Hypointense hepatocellular carcinomas on apparent diffusion coefficient mapping: Pathological features and metastatic recurrence after hepatectomy.
abstract: OBJECTIVE
  The present study aimed to evaluate pathological features of hepatocellular carcinomas (HCC) appearing hypointense on the apparent diffusion coefficient (ADC) map, and to elucidate the association between the signal intensity on the ADC map and metastatic recurrences after hepatectomy.
  
  
  METHODS
  In total, 52 consecutive patients with initial hypervascular HCC (solitary lesion ≤5 cm in diameter) without vascular invasion on imaging were examined by diffusion-weighted magnetic resonance imaging before hepatectomy. The signal intensities of HCC on the ADC map were visually compared with the surrounding liver and categorized as hypointense or non-hypointense. Intrahepatic metastatic recurrence was defined as more than three intrahepatic recurrences.
  
  
  RESULTS
  The 52 HCC were evaluated as 26 hypointense and 26 non-hypointense tumors. No significant differences between the hypointense and non-hypointense groups were seen for age, sex, etiology, tumor size and tumor marker levels. However, in resected specimens, significant differences between the two groups were noted for histological grade and microscopic portal invasion. The percentages of poorly differentiated HCC and microscopic portal invasion in the hypointense group were significantly higher than those in the non-hypointense group. The cumulative 3-year metastatic recurrence rates of the hypointense and non-hypointense groups on the ADC map were 56% and 13% (P = 0.001), respectively. Multivariate analyses indicated that hypointensity on the ADC map was the only independent factor related to metastatic recurrence.
  
  
  CONCLUSIONS
  Hypointense HCC on ADC mapping are characterized by poor histological differentiation and more frequent microscopic portal invasion, and are significantly associated with metastatic recurrences after hepatectomy.
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tamai
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Shingaki
authors.affiliation: Second Department of Surgery, Wakayama Medical University, Wakayama, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayami
authors.affiliation: Second Department of Surgery, Wakayama Medical University, Wakayama, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ueno
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Maeda
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Kosaku
authors.initials: K
authors.lastname: Moribata
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Hisanobu
authors.initials: H
authors.lastname: Deguchi
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Niwa
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Inoue
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Maekita
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Mikitaka
authors.initials: M
authors.lastname: Iguchi
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kato
authors.affiliation: Wakayama Minami Radiology Clinic, Wakayama, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Terada
authors.affiliation: Second Department of Surgery, Wakayama Medical University, Wakayama, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamaue
authors.affiliation: Second Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Ichinose
keywords: apparent diffusion coefficient map; diffusion-weighted imaging; hepatectomy; hepatocellular carcinoma; histological differentiation; magnetic resonance imaging