Region of interest standardisation for diffusion-weighted imaging of breast malignancies

This poster is published under an open license. Please read the disclaimer for further details.

Congress:

ECR 2017

Poster Number:

C-2765

Type:

Scientific Exhibit

Keywords:

Breast, MR-Diffusion/Perfusion, MR, Comparative studies, Cancer

Authors:

M. Wielema, M. D. Dorrius, H. Dijkstra, E. Langius, M. Oudkerk, P. E. Sijens; Groningen/NL

DOI:

10.1594/ecr2017/C-2765

DOI-Link:

https://dx.doi.org/10.1594/ecr2017/C-2765

Fig. 3: Size of ROI1 (cm2) for all observers.

Fig. 4: ROC curve for all ROIs.

Table 1: Intraclass correlation coefficient (Confidence Interval, CI), absolute...

Table 2: Mean ADC values (sd) (x10-3 mm2/s) of malignant and benign lesions of all 3...

Table 3: Area under the curve for all ROIs and confidence interval.

Results

Breast lesions:

Forty-four (88%) out of the 50 breast lesions were malignant. Malignant breast lesions were invasive ductal carcinoma (41) or invasive lobular carcinoma (3). The size of ROI1 for malignant lesions varied between 0.8 cm² and 8.4 cm². For the 6 benign lesions (12%) the size varied between 0.8 cm² and 6.3 cm². The benign lesions consisted of five fibroadenomas (1 histologically proven, 4 with follow-up MRI) and one chronic mastitis.

Size of ROI1:

ROI 1 is a manually positioned oval of freehand size, to encompass most of the lesion, while staying within its borders on subtracted DCE-T1 series, and copied to the DW images using b-values of 0 and 1000 s/mm². Figure 3 shows high agreement in the size of ROI1 (the only ROI with an unfixed size) amongst the three observers.

Inter- and intra-observer variability:

Listed in Table 1 are the inter- and intra-observer correlations for the mean ADC values obtained in the 50 breast lesions using the 4 ROI methods. A strong agreement (>0.7) was found for all ROIs between the readers and good intra-observer correlation (>0.8). Overall, ADC reproducibility in ROIs 2 to 4 was similar to that in the entire lesion (ROI1).

ADC values for each ROI:

Table 2 shows the mean (±sd) ADC values of benign and malignant lesions for each ROI method of all 3 observers. Significant differences in ADC values of benign and malignant breast lesions were not observed in the entire lesion (ROI1) or in its center (ROI2) but did apply to the minimum ADC subregions of fixed size and shape: ROI3 (p=0.008) and ROI4 (p=0.044).

ROC analysis:

In Table 3 and Figure 4 the ROC analyses for the mean ADC values of the 3 observers are shown. ROC analysis showed the highest AUC for ROI3, 0.706 (95%CI: 0.549-0.864), consistent with the above mentioned best differentiation between benign and malignant lesions obtained with the small ROI minimum ADC fixed circle method (P=0.008).