Korean J Radiol.  2014 Aug;15(4):403-410. 10.3348/kjr.2014.15.4.403.

Readout-Segmented Echo-Planar Imaging in Diffusion-Weighted MR Imaging in Breast Cancer: Comparison with Single-Shot Echo-Planar Imaging in Image Quality

• Kim YJ
• Kim SH
• Kang BJ
• Park CS
• Kim HS
• Son YH
• Porter DA
• Song BJ

• KMID: 1731042
• DOI: http://doi.org/10.3348/kjr.2014.15.4.403

Abstract

OBJECTIVE
The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer.
MATERIALS AND METHODS
Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated.
RESULTS
The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR.
CONCLUSION
Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast.

Keyword

Breast neoplasm; Magnetic resonance imaging; Diffusion-weighted MRI

MeSH Terms

Adult
Aged
Aged, 80 and over
Artifacts
Breast/pathology
Breast Neoplasms/pathology
Contrast Media/diagnostic use
Diffusion Magnetic Resonance Imaging/methods/*standards
Echo-Planar Imaging/methods/*standards
Female
Humans
Image Enhancement/methods/*standards
Middle Aged
Observer Variation
Retrospective Studies
Sensitivity and Specificity
Signal-To-Noise Ratio
Contrast Media

Figure

• 

  Fig. 1 MR images in 39-year-old woman with invasive ductal carcinoma in her right breast. Contrast-enhanced T1-weighted MR image (A), readout-segmented echo-planar image (B), and ADC map (C). Lesion ROI was drawn in center of mass with high signal intensity in DW image then it was copied to ADC map. Normal tissue ROI was drawn in homogeneous breast parenchyma in contralateral breast. Another ROI was drawn at periphery of DW image to measure background noise. SNR, contrast, CNR, and lesion ADC were 304.5, 2.6, 3.4, and 1.06 × 10-3 mm2/sec, respectively. ADC = apparent diffusion coefficient, CNR = contrast-to-noise ratio, DW = diffusion-weighted, ROI = regions-of-interest, SNR = signal-to-noise ratio

• 

  Fig. 2 MR images in 45-year-old woman with two malignant masses in her right breast (invasive ductal carcinoma). Contrast-enhanced T1-weighted MR image (A), single-shot echo-planar image (ss-EPI) (B), and readout-segmented echo-planar image (rs-EPI) (C). While posteriorly located rim-enhancing mass is relatively well identifiable on both sequences, other larger mass is poorly defined on ss-EPI. Average scores given by three readers for overall image quality were 2.3 (poor) for ss-EPI and 5.3 (above average) for rs-EPI. Other variables are scored as follows (ss-EPI vs. rs-EPI); anatomical structure, 2.0 vs. 4.0; delineation of lesion, 2.7 vs. 5.7; ghosting artifacts, 2.7 vs. 3.0; fat suppression, 3.0 vs. 3.0; SNR, 78.0 vs. 232.0; contrast, 1.0 vs. 2.2; CNR, 0.1 vs. 3.8; ADC, 1.35 × 10-3 mm2/sec vs. 1.33 × 10-3 mm2/sec. ADC = apparent diffusion coefficient, CNR = contrast-to-noise ratio, SNR = signal-to-noise ratio

• 

  Fig. 3 Comparison of average lesion lengths in contrast-enhanced (CE)-MR and diffusion-weighted (DW) images. Both average anterior-posterior (AP) length (A) and left-right (LR) width (B) of lesions were measured smaller in both sets of DW images. Whereas there were no significant differences in AP length and LR width between CE-MR and readout-segmented echo-planar image (rs-EPI), they were significantly smaller in single-shot echo-planar image (ss-EPI).

• 

  Fig. 4 MR images in 88-year-old woman with invasive ductal carcinoma in her left breast. Contrast-enhanced T1-weighted MR image (A), single-shot echo-planar image (ss-EPI) (B), and readout-segmented echo-planar image (rs-EPI) (C). rs-EPI provides superior anatomical detail and lesion delineation. Spatial distortion is more prominent on ss-EPI. Average scores given by three readers for overall image quality were 3 (acceptable) for ss-EPI and 5 (above average) for rs-EPI. Other variables are scored as follows (ss-EPI vs. rs-EPI); anatomical structure, 0 vs. 4.0; delineation of lesion, 4.3 vs. 6.0; ghosting artifacts, 2.7 vs. 4.0; fat suppression, 1.3 vs. 2.0; SNR, 126.5 vs. 556.9; contrast, 3.6 vs. 8.8; CNR, 6.3 vs. 15.4; ADC, 0.62 × 10-3 mm2/sec vs. 0.63 × 10-3 mm2/sec. ADC = apparent diffusion coefficient, CNR = contrast-to-noise ratio, SNR = signal-to-noise ratio

• 

  Fig. 5 Correlation for lesion length between contrast-enhanced (CE) T1-weighted MRI and diffusion-weighted images (DWI). Pearson correlation coefficients of anterior-posterior (AP) length (A) and left-right (LR) width (B) are slightly higher in readout-segmented echo-planar image (r = 0.995, r = 0.994) than in single-shot echo-planar image (r = 0.973, r = 0.975). rs-EPI = readout-segmented echo-planar imaging, ss-EPI = single-shot echo-planar imaging

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