Investigating the Role of Global Histogram Equalization Technique for Technetium-Methylene diphosphonate Bone Scan Image Enhancement.

PURPOSE OF THE STUDY

Technetium-methylene diphosphonate (Tc-MDP) bone scan images have limited number of counts per pixel, and hence, they have inferior image quality compared to X-rays. Theoretically, global histogram equalization (GHE) technique can improve the contrast of a given image though practical benefits of doing so have only limited acceptance. In this study, we have investigated the effect of GHE technique for Tc-MDP-bone scan images.

MATERIALS AND METHODS

A set of 89 low contrast Tc-MDP whole-body bone scan images were included in this study. These images were acquired with parallel hole collimation on Symbia E gamma camera. The images were then processed with histogram equalization technique. The image quality of input and processed images were reviewed by two nuclear medicine physicians on a 5-point scale where score of 1 is for very poor and 5 is for the best image quality. A statistical test was applied to find the significance of difference between the mean scores assigned to input and processed images.

RESULTS

This technique improves the contrast of the images; however, oversaturation was noticed in the processed images. Student's -test was applied, and a statistically significant difference in the input and processed image quality was found at < 0.001 (with α = 0.05). However, further improvement in image quality is needed as per requirements of nuclear medicine physicians.

CONCLUSION

GHE techniques can be used on low contrast bone scan images. In some of the cases, a histogram equalization technique in combination with some other postprocessing technique is useful.