Identification of optimal mask size parameter for noise filtering in 99mTc-methylene diphosphonate bone scintigraphy images

Abstract

Tc-methylene diphosphonate (Tc-MDP) bone scintigraphy images have limited number of counts per pixel. A noise filtering method based on local statistics of the image produces better results than a linear filter. However, the mask size has a significant effect on image quality. In this study, we have identified the optimal mask size that yields a good smooth bone scan image. Forty four bone scan images were processed using mask sizes 3, 5, 7, 9, 11, 13, and 15 pixels. The input and processed images were reviewed in two steps. In the first step, the images were inspected and the mask sizes that produced images with significant loss of clinical details in comparison with the input image were excluded. In the second step, the image quality of the 40 sets of images (each set had input image, and its corresponding three processed images with 3, 5, and 7-pixel masks) was assessed by two nuclear medicine physicians. They selected one good smooth image from each set of images. The image quality was also assessed quantitatively with a line profile. Fisher's exact test was used to find statistically significant differences in image quality processed with 5 and 7-pixel mask at a 5% cut-off. A statistically significant difference was found between the image quality processed with 5 and 7-pixel mask at P=0.00528. The identified optimal mask size to produce a good smooth image was found to be 7 pixels. The best mask size for the John-Sen Lee filter was found to be 7×7 pixels, which yielded Tc-methylene diphosphonate bone scan images with the highest acceptable smoothness.

Denoising Tc-99m DMSA images using Denoising Convolutional Neural Network with comparison to a Block Matching Filter

“…Although not directly related to our study; studies have been conducted for reducing noise levels in planar [2,3,35–37], SPECT [4,38–42] and PET images [43,44]. These studies do not involve neural networks for noise reduction, however.…”

“…Filtering operations can be performed in either spatial domain or in frequency domain. In spatial domain filtering, the appropriate size of the filter is required so that the filtered image is not over-smooth and preserves the clinical details [3]. In frequency domain filtering, finding the optimal cutoff frequency is important since a lower cutoff frequency produces a smooth image but certain clinical details might be lost, whereas a higher cutoff frequency preserves the clinical details but the filtered image may still be noisy [4].…”

99m-Tc MDP Bone Scan Image Enhancement using Pipeline Application of Dynamic Stochastic Resonance Algorithm and Block-Matching 3D Filter

“…Several image enhancements have been proposed and evaluated for nuclear medicine images, and some of these have been implemented by vendors and come as a part of image processing software package with SPECT/CT or PET/CT scanner. [ 14 15 16 17 18 ] NM Physicians/NM Technologists use some of these in nuclear medicine practice as per their comfort levels. We have not compared the result of our study with any of such routinely used software tool for image enhancement.…”

Restoration of Tc-99m methyl diphosphonate bone scan image using Richardson–Lucy algorithm

“…The Richardson-Lucy algorithm was used by Sasi et al [20] for deblurring of cardiac single-photon emission computerized tomography (SPECT) images using maximum-likelihood estimation of the PSF. Several studies related to enhancing bone scan images have been performed [21][22][23][24][25]. However, there is no study that is directly related to the restoration of planar Tc-99 m MDP bone scan images using the Richardson-Lucy algorithm.…”