Construction of a Preclinical Multimodality Phantom Using Tissue-mimicking Materials for Quality Assurance in Tumor Size Measurement

Yongsook C. Lee; Gary D. Fullerton; Beth A. Goins

doi:10.3791/50403

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Method Article

Construction of a Preclinical Multimodality Phantom Using Tissue-mimicking Materials for Quality Assurance in Tumor Size Measurement

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DOI:

10.3791/50403

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July 29th, 2013

Yongsook C. Lee¹^,² , Gary D. Fullerton² , Beth A. Goins²

¹Department of Radiation Oncology, University of Kansas School of Medicine, ²Department of Radiology, University of Texas Health Science Center at San Antonio

Summary

This paper describes in-house procedures of constructing a preclinical multimodality phantom made of tissue-mimicking (TM) materials for quality assurance (QA) of tumor size measurement in animal imaging modalities such as ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI).

Abstract

World Health Organization (WHO) and the Response Evaluation Criteria in Solid Tumors (RECIST) working groups advocated standardized criteria for radiologic assessment of solid tumors in response to anti-tumor drug therapy in the 1980s and 1990s, respectively. WHO criteria measure solid tumors in two-dimensions, whereas RECIST measurements use only one-dimension which is considered to be more reproducible ^{1, 2, 3,4,5}. These criteria have been widely used as the only imaging biomarker approved by the United States Food and Drug Administration (FDA) ⁶. In order to measure tumor response to anti-tumor drugs on images with accuracy, therefore, a robust quality assurance (QA) procedures and corresponding QA phantom are needed.

To address this need, the authors constructed a preclinical multimodality (for ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI)) phantom using tissue-mimicking (TM) materials based on the limited number of target lesions required by RECIST by revising a Gammex US commercial phantom ⁷. The Appendix in Lee et al. demonstrates the procedures of phantom fabrication ⁷. In this article, all protocols are introduced in a step-by-step fashion beginning with procedures for preparing the silicone molds for casting tumor-simulating test objects in the phantom, followed by preparation of TM materials for multimodality imaging, and finally construction of the preclinical multimodality QA phantom. The primary purpose of this paper is to provide the protocols to allow anyone interested in independently constructing a phantom for their own projects. QA procedures for tumor size measurement, and RECIST, WHO and volume measurement results of test objects made at multiple institutions using this QA phantom are shown in detail in Lee et al. ⁸.

Introduction

Assessment of the change in tumor size is an important endpoint for evaluating the activity of anti-tumor drugs in both tumor shrinkage and disease progression ^{9, 10}. World Health Organization (WHO) and Response Evaluation Criteria in Solid Tumors (RECIST) are the codified methods for the anatomic assessment of tumor lesions in imaging modalities such as ultrasound (US), computed tomography (CT) or magnetic resonance imaging (MRI). For WHO criteria, the product of tumor maximum diameter and its largest perpendicular diameter in the transverse plane for target regions is calculated ⁴. In contrast, for RECIST, the sum of longest diameters ....