De-Speckling Breast Cancer Ultrasound Images Using a Rotationally Invariant Block Matching Based Non-Local Means (RIBM-NLM) Method

Gelan Ayana; Kokeb Dese; Hakkins Raj; Janarthanan Krishnamoorthy; Timothy Kwa

doi:10.3390/diagnostics12040862

De-Speckling Breast Cancer Ultrasound Images Using a Rotationally Invariant Block Matching Based Non-Local Means (RIBM-NLM) Method

Diagnostics (Basel). 2022 Mar 30;12(4):862. doi: 10.3390/diagnostics12040862.

Authors

Gelan Ayana^{1

2}, Kokeb Dese², Hakkins Raj², Janarthanan Krishnamoorthy^{2

3}, Timothy Kwa^{2

4

5}

Affiliations

¹ Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39253, Korea.
² School of Biomedical Engineering, Jimma University, Jimma 378, Ethiopia.
³ Singapore Bioimaging Consortium, Astar Research Institutes, Singapore 138667, Singapore.
⁴ Department of Biomedical Engineering, University of California, 451 Health Sciences, Davis, CA 95616, USA.
⁵ Medtronic MiniMed, 18000 Devonshire St., Northridge, Los Angeles, CA 91325, USA.

Abstract

The ultrasonic technique is an indispensable imaging modality for diagnosis of breast cancer in young women due to its ability in efficiently capturing the tissue properties, and decreasing nega-tive recognition rate thereby avoiding non-essential biopsies. Despite the advantages, ultrasound images are affected by speckle noise, generating fine-false structures that decrease the contrast of the images and diminish the actual boundaries of tissues on ultrasound image. Moreover, speckle noise negatively impacts the subsequent stages in image processing pipeline, such as edge detec-tion, segmentation, feature extraction, and classification. Previous studies have formulated vari-ous speckle reduction methods in ultrasound images; however, these methods suffer from being unable to retain finer edge details and require more processing time. In this study, we propose a breast ultrasound de-speckling method based on rotational invariant block matching non-local means (RIBM-NLM) filtering. The effectiveness of our method has been demonstrated by com-paring our results with three established de-speckling techniques, the switching bilateral filter (SBF), the non-local means filter (NLMF), and the optimized non-local means filter (ONLMF) on 250 images from public dataset and 6 images from private dataset. Evaluation metrics, including Self-Similarity Index Measure (SSIM), Peak Signal to Noise Ratio (PSNR), and Mean Square Error (MSE) were utilized to measure performance. With the proposed method, we were able to record average SSIM of 0.8915, PSNR of 65.97, MSE of 0.014, RMSE of 0.119, and computational speed of 82 seconds at noise variance of 20dB using the public dataset, all with p-value of less than 0.001 compared against NLMF, ONLMF, and SBF. Similarly, the proposed method achieved av-erage SSIM of 0.83, PSNR of 66.26, MSE of 0.015, RMSE of 0.124, and computational speed of 83 seconds at noise variance of 20dB using the private dataset, all with p-value of less than 0.001 compared against NLMF, ONLMF, and SBF.

Keywords: block matching; clustering; filtering; non-local means; speckle; ultrasound.