Compression of ^99mTc Methylene Diphosphonate Bone Scan Images using Discrete Cosine Transformation

Area of Science:

• Medical Imaging
• Digital Signal Processing
• Nuclear Medicine

Background:

• Bone scan imaging, particularly with 99mTc-MDP, is crucial for diagnosing various bone pathologies.
• Efficient storage and transmission of medical images are essential in modern healthcare systems.
• Discrete Cosine Transformation (DCT) is a widely used technique for image compression.

Purpose of the Study:

• To determine the optimal threshold value for compressing 99mTc-MDP bone scan images using DCT.
• To evaluate the effectiveness of DCT-based compression in maintaining diagnostic quality.
• To quantify the compression ratio achievable with the proposed method.

Main Methods:

• DCT was applied to 51 99mTc-MDP bone scan images.
• The logarithmic values of DCT coefficients were analyzed to identify an appropriate threshold.
• Inverse DCT was used to reconstruct compressed images after applying a threshold of 10.
• Compression factor was calculated based on the ratio of non-zero DCT coefficients before and after thresholding.
• Nuclear medicine physicians assessed the diagnostic acceptability of compressed images based on specific criteria.

Main Results:

• A threshold value of 10 was determined to be optimal for compression.
• Forty-four out of 51 compressed images (86.3%) were deemed acceptable by nuclear medicine physicians.
• The average compression factor achieved was 13.03, representing a significant reduction in data size.
• Compressed images exhibited reduced noise compared to the original images.

Conclusions:

• The optimal threshold for compressing 99mTc-MDP bone scan images using DCT is 10.
• DCT-based compression with a threshold of 10 provides an average compression factor of 13.03 (92.30%) while maintaining diagnostic acceptability.
• This technique offers a viable method for reducing the storage and transmission burden of bone scan images.