Extracranial Soft-Tissue Tumors: Repeatability of Apparent Diffusion Coefficient Estimates from Diffusion-weighted MR Imaging.

Jessica M Winfield,Christina Messiou,Nandita M Desouza,Nina Tunariu,Martin O Leach,Keiko Miyazaki,Neil P Jerome,Dow-Mu Koh,Timothy A Yap,Matthew R Orton,Matthew D Blackledge,Michael Germuska,Johann S De Bono,Mihaela Rata,Simon J Doran,David J Collins

doi:10.1148/radiol.2017161965

Abstract

Purpose To assess the repeatability of apparent diffusion coefficient (ADC) estimates in extracranial soft-tissue diffusion-weighted magnetic resonance imaging across a wide range of imaging protocols and patient populations. Materials and Methods Nine prospective patient studies and one prospective volunteer study, performed between 2006 and 2016 with research ethics committee approval and written informed consent from each subject, were included in this single-institution study. A total of 141 tumors and healthy organs were imaged twice (interval between repeated examinations, 45 minutes to 10 days, depending the on study) to assess the repeatability of median and mean ADC estimates. The Levene test was used to determine whether ADC repeatability differed between studies. The Pearson linear correlation coefficient was used to assess correlation between coefficient of variation (CoV) and the year the study started, study size, and volumes of tumors and healthy organs. The repeatability of ADC estimates from small, medium, and large tumors and healthy organs was assessed irrespective of study, and the Levene test was used to determine whether ADC repeatability differed between these groups. Results CoV aggregated across all studies was 4.1% (range for each study, 1.7%-6.5%). No correlation was observed between CoV and the year the study started or study size. CoV was weakly correlated with volume (r = -0.5, P = .1). Repeatability was significantly different between small, medium, and large tumors (P < .05), with the lowest CoV (2.6%) for large tumors. There was a significant difference in repeatability between studies-a difference that did not persist after the study with the largest tumors was excluded. Conclusion ADC is a robust imaging metric with excellent repeatability in extracranial soft tissues across a wide range of tumor sites, sizes, patient populations, and imaging protocol variations. Online supplemental material is available for this article.

Highlights

To assess the repeatability of apparent diffusion coefficient (ADC) estimates in extracranial soft-tissue diffusionweighted magnetic resonance imaging across a wide range of imaging protocols and patient populations
The most simple quantitative metric derived from DW magnetic resonance (MR) imaging is the apparent diffusion coefficient (ADC), which is estimated by fitting a monoexponential curve to the measured signal at two or more diffusion weightings (b values)
Baseline ADC estimates or posttreatment changes in ADC have been shown to be indicative of response to chemotherapy and/or chemotherapy and radiation therapy in many tumor types, including rectal adenocarcinoma [2], hepatic metastases of colorectal [3] and gastric [4] cancers, cervical cancer [5], breast cancer [6], head-and-neck squamous cell carcinoma [7], ovarian cancer [8], and non–small cell lung cancer [9]

Summary

Objectives

The aim of this study was to assess ADC repeatability using the framework proposed by the QIBA in extracranial soft-tissue DW MR imaging studies to investigate whether ADC repeatability differs between studies performed by using different imaging protocols and patient populations over a period of 10 years at a single institution

Methods

Results

Discussion

Conclusion