Reduced acquisition times in whole body bone scintigraphy using a noise-reducing Pixon®-algorithm—a qualitative evaluation study

Abstract

BackgroundReducing scan-time while maintaining sufficient image quality is a common issue in nuclear medicine diagnostics. This matter can be addressed by different post-processing methods such as Pixon® image processing. The aim of the present study was to evaluate if a commercially available noise-reducing Pixon-algorithm applied on whole body bone scintigraphy acquired with half the standard scan-time could provide the same clinical information as full scan-time non-processed images.MethodsTwenty patients were administered with 500 MBq 99mTc-diphosphonate and scanned on a Siemens Symbia T16 system. Each patient was first imaged using a standard clinical protocol and subsequently imaged using a protocol with half the standard scan-time. Half-time images were processed using a commercially available software package, Enhanced Planar Processing, from Siemens. All images were anonymized and visually evaluated with regard to clinically relevant lesion detectability by three experienced nuclear medicine physicians. The result of this evaluation was grouped into four BMI intervals to investigate the performance of the algorithm with regard to different patient size. Also, a comparison study was performed where the physicians compared the standard image and the processed half-time image corresponding to the same patient with regard to lesion detectability, image noise, and artifacts.ResultsThe results showed that 93 % of the processed half-time images and 98 % of the standard images were rated as sufficient or good with regard to lesion detectability. The processed half-time images were predominately considered sufficient (65 %), whereas the majority of the standard images were graded as good (83 %). The performance of the algorithm was unaffected by patient size as the average grading of all half-time processed images was constant independent of patient BMI. The comparison study showed that the standard images were rated superior with regard to lesion detectability, image noise, and artifacts, in 32, 65, and 23 % of the evaluations, respectively.ConclusionsThe results indicate that the Pixon Enhanced Planar Processing does not fully compensate for the loss of counts associated with reducing the scan-time in half for whole body bone scintigraphies. The findings showed that implementing the Pixon-algorithm on images acquired with half the acquisition time in overall provide sufficient clinical information regardless of patient size. The half-time processed images were predominantly graded lower in comparison to images acquired with full time protocols, and a less aggressive reduction in scan-time is therefore recommended.

ICRP Publication 135: Diagnostic Reference Levels in Medical Imaging

“…(136) Imaging equipment vendors promote and invest in improvement in image quality, and in dose-reduction techniques, but they tend to emphasise the dose reduction (e.g. of half-time imaging or iterative image reconstructions in CT) and pay less attention to the risk of reduced image quality by these techniques (Guimaraes et al., 2010; Ardenfors et al., 2015). The adequacy of the image quality should be assessed and dealt with at introduction of such techniques into clinical practice.…”

Improving technetium-99m methylene diphosphonate bone scan images using histogram specification technique

“…In the past, studies have been done to improve the quality of bone scintigraphic images. [ 12 13 14 15 16 17 18 ] Various other authors[ 3 19 ] have also worked on the digital image processing and tried to improve the quality of these images by using histogram specification.…”

Role of an Intensity-Transformation Function in Enhancement of Bone Scintigraphy Images

“…Many proven contrast-enhancement methods have been described in the literature, but their use in bone scintigraphy has not been investigated (4,5). Studies to improve the quality of bone scintigraphy images have been previously published (6)(7)(8). Verdenet et al (6) used a global histogram equalization technique to enhance bone scintigraphy images.…”

“…Jeong et al (7) compared 6 histogram equalization-based techniques and reported that the exact histogram specification technique gives the best performance. Ardenfors et al (8) applied the Pixon algorithm (Siemens) to whole-body bone scintigraphy images acquired with half the standard scan time. They found that the processed images had sufficient clinical information but were of lower quality than images acquired with the full standard scan time.…”