Impact of Alternate <i>b</i>-Value Combinations and Metrics on the Predictive Performance and Repeatability of Diffusion-Weighted MRI in Breast Cancer Treatment: Results from the ECOG-ACRIN A6698 Trial
In diffusion-weighted MRI (DW-MRI), choice of <i>b</i>-value influences apparent diffusion coefficient (ADC) values by probing different aspects of the tissue microenvironment. As a secondary analysis of the multicenter ECOG-ACRIN A6698 trial, the purpose of this study was to investigate...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-03-01
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| Series: | Tomography |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2379-139X/8/2/58 |
| Summary: | In diffusion-weighted MRI (DW-MRI), choice of <i>b</i>-value influences apparent diffusion coefficient (ADC) values by probing different aspects of the tissue microenvironment. As a secondary analysis of the multicenter ECOG-ACRIN A6698 trial, the purpose of this study was to investigate the impact of alternate <i>b</i>-value combinations on the performance and repeatability of tumor ADC as a predictive marker of breast cancer treatment response. The final analysis included 210 women who underwent standardized 4-<i>b</i>-value DW-MRI (<i>b</i> = 0/100/600/800 s/mm<sup>2</sup>) at multiple timepoints during neoadjuvant chemotherapy treatment and a subset (n = 71) who underwent test–retest scans. Centralized tumor ADC and perfusion fraction (<i>f<sub>p</sub></i>) measures were performed using variable <i>b</i>-value combinations. Prediction of pathologic complete response (pCR) based on the mid-treatment/12-week percent change in each metric was estimated by area under the receiver operating characteristic curve (AUC). Repeatability was estimated by within-subject coefficient of variation (wCV). Results show that two-<i>b</i>-value ADC calculations provided non-inferior predictive value to four-<i>b</i>-value ADC calculations overall (AUCs = 0.60–0.61 versus AUC = 0.60) and for HR+/HER2− cancers where ADC was most predictive (AUCs = 0.75–0.78 versus AUC = 0.76), <i>p</i> < 0.05. Using two <i>b</i>-values (0/600 or 0/800 s/mm<sup>2</sup>) did not reduce ADC repeatability over the four-<i>b</i>-value calculation (wCVs = 4.9–5.2% versus 5.4%). The alternate metrics ADC<sub>fast</sub> (<i>b</i> ≤ 100 s/mm<sup>2</sup>), ADC<sub>slow</sub> (<i>b</i> ≥ 100 s/mm<sup>2</sup>), and <i>f<sub>p</sub></i> did not improve predictive performance (AUCs = 0.54–0.60, <i>p</i> = 0.08–0.81), and ADC<sub>fast</sub> and <i>f<sub>p</sub></i> demonstrated the lowest repeatability (wCVs = 6.71% and 12.4%, respectively). In conclusion, breast tumor ADC calculated using a simple two-<i>b</i>-value approach can provide comparable predictive value and repeatability to full four-<i>b</i>-value measurements as a marker of treatment response. |
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| ISSN: | 2379-1381 2379-139X |