Abstract
The aim of this study was to establish the repeatability measures of quantitative Gaussian and non-Gaussian diffusion metrics using diffusion-weighted imaging (DWI) data from phantoms and patients with head-and-neck and papillary thyroid cancers. The Quantitative Imaging Biomarker Alliance (QIBA) DWI phantom and a novel isotropic diffusion kurtosis imaging phantom were scanned at 3 different sites, on 1.5T and 3T magnetic resonance imaging systems, using standardized multiple b-value DWI acquisition protocol. In the clinical component of this study, a total of 60 multiple b-value DWI data sets were analyzed for test–retest, obtained from 14 patients (9 head-and-neck squamous cell carcinoma and 5 papillary thyroid cancers). Repeatability of quantitative DWI measurements was assessed by within-subject coefficient of variation (wCV%) and Bland–Altman analysis. In isotropic diffusion kurtosis imaging phantom vial with 2% ceteryl alcohol and behentrimonium chloride solution, the mean apparent diffusion (Dapp × 10−3 mm2/s) and kurtosis (Kapp, unitless) coefficient values were 1.02 and 1.68 respectively, capturing in vivo tumor cellularity and tissue microstructure. For the same vial, Dapp and Kapp mean wCVs (%) were ≤1.41% and ≤0.43% for 1.5T and 3T across 3 sites. For pretreatment head-and-neck squamous cell carcinoma, apparent diffusion coefficient, D, D*, K, and f mean wCVs (%) were 2.38%, 3.55%, 3.88%, 8.0%, and 9.92%, respectively; wCVs exhibited a higher trend for papillary thyroid cancers. Knowledge of technical precision and bias of quantitative imaging metrics enables investigators to properly design and power clinical trials and better discern between measurement variability versus biological change.
Highlights
Malignant tumors of the head and neck (HN) region include a diverse group of cancers in the oral cavity, nasopharynx, oropharynx, hypopharynx, larynx, and paranasal sinuses; salivary and thyroid carcinomas are located within the HN region, they are typically thought of as separate tumors [1]
We will focus on the measurements obtained from 2 vials, that is, [1] water-only and [2] PVP-20%, as they relate to data from the novel isotropic diffusion kurtosis imaging phantom
Quantitative diffusion-weighted imaging (DWI) Phantom Mean Apparent diffusion coefficient (ADC) values obtained from the National Institute of Standards and Technology (NIST)/Quantitative Imaging Biomarker Alliance (QIBA) DWI phantom at all 3 different sites on 1.5T and 3T magnetic resonance imaging (MRI) scanners are displayed in a box-and-whisker plot (Figure 1)
Summary
Malignant tumors of the head and neck (HN) region include a diverse group of cancers in the oral cavity, nasopharynx, oropharynx, hypopharynx, larynx, and paranasal sinuses; salivary and thyroid carcinomas are located within the HN region, they are typically thought of as separate tumors [1]. HN tumors are heterogeneous with complex anatomy ranging between oral cavity to hypopharynx [2, 3]. Accurate detection and delineation of tumor extent is critical to optimize treatment planning; patients routinely undergo noninvasive imaging for careful assessment of this complex anatomy by an experienced neuroradiologist [4]. The quantitative MRI (qMRI) technique, diffusion-weighted imaging (DWI), assesses the Brownian motion of water mole-. Repeatability Measures of DWI Metrics in Head and Neck and Thyroid Cancers cules at a cellular level [9]. Apparent diffusion coefficient (ADC), derived by fitting DWI data to a monoexponential model using Ն2 b-values (ie, diffusion-weighting factor), reflects tumor cellularity [10, 11]. The use of ADC is helpful in differentiation between malignant and benign solitary thyroid nodules and assessing tumor aggressiveness in papillary thyroid cancer (PTC) [21, 22]
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