title: Contrast-enhanced ultrasound in planning thermal ablation of liver metastases: Should the hypervascular halo be included in the ablation volume?().
abstract: BACKGROUND
  Liver metastases often exhibit a hypervascular halo during the arterial phase of contrast-enhanced ultrasonography (CEUS). This finding has no correlates on baseline gray-scale imaging, and it has never been characterized. The aim of this study was to identify the features of this halo and determine whether it should be included in the ablation volume during thermal ablation procedures.
  
  
  METHODS
  We prospectively enrolled 25 patients referred to our department for thermal ablation of liver metastases. Before treatment all patients underwent CEUS, and the maximum diameter of the metastatic lesion was measured before administration of the ultrasound contrast agent and during the arterial and portal venous phases of the contrast contrast-enhanced study. Maximum diameters in the different vascular phases were compared with the Turkey-Kramer test. Two biopsies were obtained from each lesion with a 21-gauge needle: 1) one from the center of the metastasis to confirm the diagnosis and 2) one from the hypervascular peripheral halo identified in the arterial phase at CEUS.
  
  
  RESULTS
  The mean (±standard deviation) maximum lesion diameter was 2.67 ± 1.2 cm before contrast agent injection, 3.50 ± 1.4 cm during the arterial phase, and 2.71 ± 1.2 cm during the venous phase. The difference between maximum diameters measured before contrast enhancement and in the arterial phase was highly significant (mean: 0.84 ± 0.45 cm, p < 0.0001). Histological examination of halo specimens revealed inflammatory infiltrates with no evidence of tumor infiltration in 24/25 (96%) cases and normal hepatic parenchymal tissue in the 25th specimen.
  
  
  CONCLUSIONS
  The hypervascular halo surrounding liver metastases during the arterial phase of CEUS represents a chronic inflammatory infiltrate, not tumor infiltration. However, since chronic inflammation appears to promote neovascularization and the production of tumoral growth factors, it seems wise to include the hypervascular halo in the intended-to-treat volume when planning the ablation procedure.
authors: Radiodiagnostics Department, Bicocca University of Milan, Italy ; Department of Radiology, San Gerardo Hospital, Monza, Italy.
authors: A
authors: A
authors: Andreano
authors: E
authors: E
authors: Meneghel
authors: G
authors: G
authors: Bovo
authors: D
authors: D
authors: Ippolito
authors: A
authors: A
authors: Salvioni
authors: C
authors: C
authors: Filice
authors: S
authors: S
authors: Sironi
authors: M F
authors: MF
authors: Meloni
keywords: Contrast-enhanced ultrasound; Hypervascular halo; Liver metastasis; Thermal ablation
references: J Comput Assist Tomogr. 1997 Sep-Oct;21(5):713-9
references: 9294557
references: Ultrasound Q. 2006 Mar;22(1):19-29
references: 16641790
references: Radiology. 2009 Dec;253(3):861-9
references: 19709994
references: Nature. 2002 Dec 19-26;420(6917):860-7
references: 12490959
references: Ann Surg. 2007 Aug;246(2):295-300
references: 17667509
references: Surgeon. 2008 Aug;6(4):232-9
references: 18697366
references: Acta Radiol. 1997 May;38(3):416-21
references: 9191433
references: Eur Radiol. 2009 May;19(5):1206-13
references: 19137310
references: J Magn Reson Imaging. 2003 Jul;18(1):40-8
references: 12815638
references: J Surg Oncol. 1998 Oct;69(2):88-93
references: 9808511
references: Histochem Cell Biol. 2008 Dec;130(6):1079-90
references: 18953558
references: World J Surg. 2008 Sep;32(9):2047-56
references: 18521661
references: Radiology. 2000 Apr;215(1):89-94
references: 10751472
references: Cancer Res. 2006 Jan 15;66(2):605-12
references: 16423985
references: J Comput Assist Tomogr. 2002 Nov-Dec;26(6):975-80
references: 12488746
references: Eur Radiol. 2006 Jul;16(7):1599-609
references: 16552507
references: Ultrasound Q. 2006 Mar;22(1):41-7
references: 16641792
references: J Vasc Interv Radiol. 2009 Jul;20(7 Suppl):S377-90
references: 19560026
references: AJR Am J Roentgenol. 2006 Apr;186(4):1051-8
references: 16554578
references: Nature. 2008 Jul 24;454(7203):436-44
references: 18650914
references: Cytokine Growth Factor Rev. 2010 Feb;21(1):11-9
references: 20018552
references: Cell. 2010 Mar 19;140(6):883-99
references: 20303878