Differentiation of Benign Periablational Enhancement from Residual Tumor Following Radio-Frequency Ablation Using Contrast-Enhanced Ultrasonography in a Rat Subcutaneous Colon Cancer Model

Hanping Wu, Ravi B. Patel, Yuanyi Zheng, Luis Solorio, Tianyi M. Krupka, Nicholas P. Ziats, John R. Haaga, Agata A. Exner

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Benign periablational enhancement (BPE) response to thermal injury is a barrier to early detection of residual tumor in contrast enhanced imaging after radio-frequency (RF) ablation. The objective of this study was to evaluate the role of quantitative of contrast-enhanced ultrasound (CEUS) in early differentiation of BPE from residual tumor in a BD-IX rat subcutaneous colon cancer model. A phantom study was first performed to test the validity of the perfusion parameters in predicting blood flow of two US contrast imaging modes-contrast harmonic imaging (CHI) and microflow imaging (MFI). To create a simple model of BPE, a peripheral portion of the tumor was ablated along with surrounding normal tissue, leaving part of the tumor untreated. First-pass dynamic enhancement (FPDE) and MFI scans of CEUS were performed before ablation and immediately, 1, 4 and 7 days after ablation. Time-intensity-curves in regions of BPE and residual tumor were fitted to the function y=A(1-exp[-β{t-t 0}])+C, in which A, β, t 0 and C represent blood volume, flow speed, time to start and baseline intensity, respectively. In the phantom study, positive linear correlations were noted between A, β, Aβ and contrast concentration, speed and flow rate, respectively, in both CHI and MFI. On CEUS images of the invivo study, the unenhanced ablated zone was surrounded by BPE and irregular peripheral enhancement consistent with residual tumor. On days 0, 4 and 7, blood volume (A) in BPE was significantly higher than that in residual tumor in both FPDE imaging and MFI. Significantly greater blood flow (Aβ) was seen in BPE compared with residual tumor tissue in FPDE on day 7 and in MFI on day 4. The results of this study demonstrate that qualitative CEUS can be potentially used for early detection of viable tumor in post-ablation assessment.

Original languageEnglish (US)
Pages (from-to)443-453
Number of pages11
JournalUltrasound in Medicine and Biology
Volume38
Issue number3
DOIs
StatePublished - Mar 2012
Externally publishedYes

Keywords

  • Contrast-enhanced ultrasound
  • First-pass dynamic enhancement
  • Microflow imaging
  • Post-ablation assessment
  • Radio-frequency ablation

ASJC Scopus subject areas

  • Biophysics
  • Radiological and Ultrasound Technology
  • Acoustics and Ultrasonics

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