Variability and bias assessment in breast ADC measurement across multiple systems

Abstract

Purpose To assess the ability of a recent, anatomically-designed breast phantom incorporating T1 and diffusion elements to serve as a quality control device for quantitative comparison of apparent diffusion coefficient (ADC) measurements calculated from diffusion-weighted MRI (DWI) within and across MRI systems. Materials and Methods A bilateral breast phantom incorporating multiple T1 and diffusion tissue mimics and a geometric distortion array was imaged with DWI on 1.5 T and 3.0 T scanners from two different manufacturers, using three different breast coils (three configurations total). Multiple measurements were acquired to assess the bias and variability of different diffusion weighted single-shot echo-planar imaging (SS-EPI) sequences on the scanner-coil systems. Results The repeatability of ADC measurements was mixed: the standard deviation relative to baseline across scanner-coil-sequences ranged from low variability (0.47, 95% Confidence Interval (CI): 0.22–1.00) to high variability (1.69, 95% CI: 0.17–17.26), depending on material, with the lowest and highest variability from the same scanner-coil-sequence. Assessment of image distortion showed that Right/Left measurements of the geometric distortion array were 1 to 16 % larger on the left coil side compared to the right coil side independent of scanner-coil systems, diffusion weighting, and phase-encoding direction. Conclusions This breast phantom can be used to measure scanner-coil-sequence bias and variability for DWI. When establishing a multi-system study, this breast phantom may be used to minimize protocol differences (e.g. due to available sequences or shimming technique), to correct for bias that cannot be minimized, and to weigh results from each system depending on respective variability.

Additive value of diffusion‐weighted MRI in the I‐SPY 2 TRIAL

“…Third, this was a multicenter clinical trial, so MRI scanners with different magnet strengths (1.5T, 3T) from different vendors were used to acquire data. The phantom study by Keenan et al reported that ADC values vary among vendors and magnet strengths . Newitt et al recently investigated multisite concordance of ADC measurements across the National Cancer Institute's quantitative imaging network and found discrepancies between different platforms .…”

“…The phantom study by Keenan et al reported that ADC values vary among vendors and magnet strengths. 32 Newitt et al recently investigated multisite concordance of ADC measurements across the National Cancer Institute's quantitative imaging network and found discrepancies between different platforms. 24 Fourth, the patient cohort of this study was taken from the experimental arms of four different completed drugs in I-SPY 2.…”

Recommendations towards standards for quantitative MRI (qMRI) and outstanding needs

“…An initial study with the phantom revealed geometric distortions in the right‐left orientation of the axial plane with echo planar diffusion‐weighted images (Fig. ) across systems (fields and platforms) dependent on which side of the coil the object was located . The distortions remained in the right/left orientation regardless of the phase‐encoding direction, did not change with b ‐value, and thus are most likely due to B 0 inhomogeneity .…”

“…NIST created three reference objects that have been commercialized and are being actively used by the MRI community: the ISMRM/NIST system phantom, 7,21 the QIBA/NIH/ NIST isotropic diffusion phantom, 3,22,23 and the University of California San Francisco (UCSF)/NIST breast phantom. 4,5 The NIST reference objects have been used to identify measurement errors and then improve the stability of acquisitions in technique/pulse sequence development and protocol development for multisite studies. These reference objects were necessary to aid standardization, but they are insufficient given the wide range of qMRI applications-that is, there is still a need for additional reference objects.…”

Histogram analysis of diffusion kurtosis imaging based on whole‐volume images of breast lesions

“…Magnetic resonance imaging (MRI) has been adopted as an important tool for the screening and diagnosis of breast cancer . Diffusion‐weighted imaging (DWI), a common functional MRI technology, is widely used to describe the diffusion of water in living tissue by the apparent diffusion coefficient (ADC) . The ADC quantifies the monoexponential decay of signal intensity (SI), which reflects information related to the tumor microenvironment, such as cellularity, extracellular space, and the integrity of the cell membranes in a noninvasive manner .…”