Distinguishing pure ductal carcinoma in situ grade using quantitative DWI biomarkers at 3 Tesla
Jing Yuan1, Gladys Lo2, Oilei Wong1, Helen H.L. Chan2, Ting Ting Wong3, and Polly S.Y. Cheung3

1Medical Physics and Research Department, Hong Kong Sanatorium&Hospital, Hong Kong, Hong Kong, 2Department of Diagnostic & Interventional Radiology, Hong Kong Sanatorium&Hospital, Hong Kong, Hong Kong, 3Breast Care Center, Hong Kong Sanatorium&Hospital, Hong Kong, Hong Kong

Synopsis

This study aims to explore the use of quantitative breast DWI at 3T to distinguish DCIS pathological grades. In a cohort of 30 pathology confirmed pure DCIS, the mean ADC was 1.26±0.19, 1.51±0.29 and 1.13±0.26 x10-3 mm2/s for low (n=5), intermediate (n=9) and high-grade (n=16) DCIS respectively. The high-grade DCIS could be distinguished by the significantly lower mean ADC from non-high grade DCIS (low and intermediate grades, 1.42±0.28 x10-3 mm2/s, p=0.0057). Quantitative DWI has potentials to aid DCIS risk stratification and management.

Introduction

Ductal carcinoma in situ (DCIS) is a precursor of breast cancer, and accounts for around 20% of the newly diagnosed breast cancers in United States. Recent studies have revealed that not all DCIS will eventually evolve into invasive breast cancer, so there is a critical need to stratify risk in patients with DCIS to avoid possible over-treatment of DCIS. DCE-MRI has better performance in DCIS detection and extent determination (1). DWI is a non-invasive contrast-free MR technique and shows potentials to complete DCE-MRI for DCIS risk stratification. The main purpose of this study is to explore whether quantitative apparent diffusion coefficient (ADC) of pure DCIS at 3 Tesla is able to distinguish DCIS pathological grades so as to aid DCIS risk stratification.

Methods

3T DWI data of 30 surgical pathology confirmed pure DCIS in 29 consecutive female patients (age: 51±11 years) were included. 3T axial breast DWI was conducted (Trio, Siemens, Erlangen, Germany) prior to DCE-MRI using a fat-suppressed single-shot EPI sequence (TE/TR=102/5800ms, voxel=1.8x1.8x6mm3, b=0, 1000 s/mm2, averages=4) with a 4-channel breast coil. ROIs of DCIS lesions were carefully drawn on either b1000 image or ADC map based on better lesion visualization by using DCE-MRI image as reference, and mean ROI ADC was recorded. The mean ADC values of DCIS lesions associated with different (1: low; 2: intermediate; 3: high) grades (Van Nuys prognostic index scoring index) were compared using Kruskal-Wallis test and Mann-Whitney U test with a significance level of 0.05.

Results

The patient and lesion characteristics are given in Table 1. The mean ADC of DCIS lesions was 1.26±0.19 x10-3 mm2/s, 1.51±0.29 x10-3 mm2/s and 1.13±0.26 x10-3 mm2/s for low (n=5), intermediate (n=9) and high grade (n=16) respectively. Kruskal-Wallis test and the box plot (Fig. 1) show that DCIS lesions with different grades had significantly different mean ADC values (p=0.0105). Mann-Whitney U test show that the mean ADC of high-grade DCIS was only significantly lower than that of intermediate-grade (p=0.0042) but not low-grade (p=0.2006). In addition, the mean ADC of high-grade DCIS was also significantly lower (p=0.0057, Fig. 2) than the non-high grade DCIS (1.42±0.28 x10-3 mm2/s, combined low and intermediate grades, n=14). In contrast, the mean ADC of low-grade DCIS was not significantly lower than the non-low grade DCIS (1.27±0.33 x10-3 mm2/s, combined low and intermediate grades, n=25).

Discussion

There are still sparse studies to investigate the correlation between DWI biomarker and pathology of DCIS (2, 3). Iima et al (2) reported that the mean ADCs of non-low (high and intermediate) grade DCIS were significantly lower than those of low grade DCIS in 22 patients. Rahbar et al (3) reported that high nuclear grade DCIS could be distinguished from non-high nuclear grade ones by mean maximum lesion size on DCE-MRI and lower mean contrast-to-noise ratio (CNR) at b600 DWI image in 55 pure DCIS. Both studies were acquired at 1.5T. 3T DWI supposes to better characterize DCIS due to its high SNR compared to 1.5T. Consistent with those two previous studies, our results indicate the potential roles of DWI for DCIS grade differentiation and risk stratification. However, on the other hand, our results are different in some aspects. Compared to Iima’s results, we found that the mean ADC was able to distinguish non-high grade DCIS from high grade ones, while low and intermediate grade DCIS could not be distinguished from each other. In contrast to Rahbar’s study, our DWI was acquired prior to DCE-MRI and different b-values were used (1000 v.s. 600 s/mm2). We correlated DCIS ADC to comprehensive pathological grade rather than simply the nuclear grade of DCIS. The mean ADC of low-grade DCIS was smaller than that of intermediate-grade DCIS in our study, which might attribute to the small number of low-grade DCIS. This study is limited in the relatively small sample size of DCIS. The pathological features that account for the ADC difference between different grades should be further delineated in future studies.

Acknowledgements

No acknowledgement found.

References

1. Kuhl CK et al. MRI for diagnosis of pure ductal carcinoma in situ: a prospective observational study. Lancet 2007;370(9586):485–492.

2. Iima M, Le Bihan D, Okumura R, et al. Apparent diffusion coefficient as an MR imaging biomarker of low-risk ductal carci- noma in situ: a pilot study. Radiology 2011; 260(2):364–372.

3. Rahbar H, et al. "In vivo assessment of ductal carcinoma in situ grade: a model incorporating dynamic contrast-enhanced and diffusion-weighted breast MR imaging parameters." Radiology 2012; 263(2):374-382.

Figures

Table 1: Patient information and DCIS lesion characteristics

Fig.1 Box-plot of mean ADC of DCIS with different grades. Kruskal-Wallis test shows a significantly different mean ADC between DCIS grades with p=0.0105.

Fig. 2 Box-plot of mean ADC of non-high and high-grade DCIS. High-grade DCIS has significantly lower (p=0.0057) mean ADC than the non-high grade DCIS.



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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