Abstract
Simple SummaryThe role of magnetic resonance imaging (MRI) in breast cancer has expanded in the last decade, and studies have demonstrated good sensitivity and specificity of diffusion-weighted imaging (DWI), a functional imaging technique reflecting water diffusion properties in tissues. However, clear results about the reproducibility of DWI are still missing. To utilize DWI as a reliable stand-alone technique for breast cancer detection, the inter-reader agreement of the measurement must be assessed. Accordingly, in this study, we assess the inter-reader reproducibility to retrospectively evaluate the agreement of breast cancer detection using DWI as a stand-alone technique. As our results show a good agreement only in expert readers, the assumption that a breast MRI based only on qualitative analysis of DWI, with fewer variables, may be easier for a non-expert reader to learn seems disproved, and future prospective studies should assess the right time for appropriate training for radiologists to investigate the potential role of DWI as a stand-alone method for un-enhanced breast MRI.Purpose: In order to evaluate the use of un-enhanced magnetic resonance imaging (MRI) for detecting breast cancer, we evaluated the accuracy and the agreement of diffusion-weighted imaging (DWI) through the inter-reader reproducibility between expert and non-expert readers. Material and Methods: Consecutive breast MRI performed in a single centre were retrospectively evaluated by four radiologists with different levels of experience. The per-breast standard of reference was the histological diagnosis from needle biopsy or surgical excision, or at least one-year negative follow-up on imaging. The agreement across readers (by inter-reader reproducibility) was examined for each breast examined using Cohen’s and Fleiss’ kappa (κ) statistics. The Wald test was used to test the difference in inter-reader agreement between expert and non-expert readers. Results: Of 1131 examinations, according to our inclusion and exclusion criteria, 382 women were included (49.5 ± 12 years old), 40 of them with unilateral mastectomy, totaling 724 breasts. Overall inter-reader reproducibility was substantial (κ = 0.74) for expert readers and poor (κ = 0.37) for non- expert readers. Pairwise agreement between expert readers and non-expert readers was moderate (κ = 0.60) and showed a statistically superior agreement of the expert readers over the non-expert readers (p = 0.003). Conclusions: DWI showed substantial inter-reader reproducibility among expert-level readers. Pairwise comparison showed superior agreement of the expert readers over the non-expert readers, with the expert readers having higher inter-reader reproducibility than the non-expert readers. These findings open new perspectives for prospective studies investigating the actual role of DWI as a stand-alone method for un-enhanced breast MRI.
Highlights
The role of magnetic resonance imaging (MRI) in breast cancer has expanded in the last decade, and currently includes tumor detection and characterization, screening in high-risk patients, image guidance for biopsy, and treatment response scenarios [1,2,3,4,5,6,7,8,9]
The steadily increasing demand for breast MRI has led to concerns regarding the lack of access to MRI itself, which is expensive and time-consuming, as well as concerns regarding the potential side-effects of gadolinium-based contrast agents (GBCA) and its tissue retention [5,7,9,11,12,13,27,28]
We reported a wide range of agreement across all readers, and nonexpert readers showed an overall poor reproducibility, suggesting that readers should have at least 3 years of experience to evaluate diffusion-weighted imaging (DWI) as a stand-alone sequence of breast MRI
Summary
The role of magnetic resonance imaging (MRI) in breast cancer has expanded in the last decade, and currently includes tumor detection and characterization, screening in high-risk patients, image guidance for biopsy, and treatment response scenarios [1,2,3,4,5,6,7,8,9].The backbone of MRI techniques for assessing breast cancer is the dynamic contrastenhanced (DCE) acquisition, which characterizes tissue vascularity, and was demonstrated to be the most reliable tool for assessing the loco-regional extent of breast cancer [10]. The role of magnetic resonance imaging (MRI) in breast cancer has expanded in the last decade, and currently includes tumor detection and characterization, screening in high-risk patients, image guidance for biopsy, and treatment response scenarios [1,2,3,4,5,6,7,8,9]. Growing evidence supports diffusion-weighted imaging (DWI), a functional imaging technique reflecting water diffusion properties in tissue, as a supplemental, or even alternative, technique to DCE. Such an innovation, if it were used instead of DCE, could minimize costs, reduce the time spent, and improve patients’ and physicians’ compliance with MRI. The lack of intravenous injections of gadolinium-based contrast agents (GBCA) could avoid the gadolinium retention in the brain and other tissues, especially in patients with high risk of breast cancer who undergo repeated breast MRI [5,7,11,12,13].
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