Evaluation of the SwiftScan mode in bone single-photon emission computed tomography (SPECT) imaging: effect on imaging quality and a semi-quantitative analysis

Abstract

Background: ^99mTc-stannous methylene diphosphonate (^99mTc-MDP) bone single-photon emission computed tomography/computed tomography (SPECT/CT) imaging plays a crucial role in various clinical applications. Many strategies have been developed to reduce the injection activity and procedure time, improve the patient experience and reduce their anxiety prior to and during SPECT imaging. This study aimed to evaluate the SwiftScan mode and its effect on image quality, and diagnostic performance of malignant skeletal lesions in bone SPECT image.

Methods: ^99mTc-MDP SPECT/CT scans were acquired from the National Electrical Manufacturers Association (NEMA) phantom with a sphere-to-background ratio of 10:1, and 69 patients were enrolled in this retrospective study. The patients who showed abnormal uptake of focal ^99mTc-MDP on whole-body bone planar scans, underwent local SPECT/CT scans. The image comparison and analysis were performed in three acquisition modes: SwiftScan; SwiftScan-50% (the SwiftScan mode with a 50% reduction in acquisition time); and step-and-shoot (SS). The image mean count, coefficient of variation (COV), radioactive concentration, and signal-to-background ratio (SBR) were measured for each phantom image. Visual assessment (using a 5-point Likert scale), semi-quantitative analysis [to determine the COV, mean of the standard uptake value (SUVmean), maximum of the standard uptake value (SUVmax), and SBR], and receiver operating characteristics (ROC) curve analysis were performed for clinical assessment.

Results: The SwiftScan mode obtained better quality images than the SwiftScan-50% and SS modes, and it also had better sphere clarity and lower background COVs (P<0.05). The mean counts of the SwiftScan, and the corresponding radioactive concentration and SBR were significantly higher than those of the SwiftScan-50% and SS (P<0.05), except in relation to the 13-10 mm spheres. A total of 101 abnormal ^99mTc-MDP uptake skeletal lesions were included in the clinical study. The SwiftScan had significantly higher visual scores than both the SwiftScan-50% and SS (P<0.001). Additionally, there were significantly higher visual scores in the SwiftScan-50% than SS (P<0.05). The SwiftScan also had a lower COV, indicating reduced image noise. The SUVmax, SUVmean, and SBR for the skeletal lesions were significantly higher in the SwiftScan than the other two modes (P<0.05). The optimal diagnostic cut-off values of the SUVmax for identifying malignant skeletal lesions in the SwiftScan, SwiftScan-50%, and SS were 17.95, 14.75, and 9.94, respectively, but there was no significant difference among the three modes in terms of their differential diagnostic performance (all P>0.05).

Conclusions: The SwiftScan showed significant improvements in image quality and the semi-quantitative analysis of bone SPECT imaging. It reduced the scanning time by 50% without compromising the image quality or diagnostic performance. These findings provide valuable insights that may inform the clinical application of the SwiftScan, enhancing qualitative and quantitative diagnosis in bone SPECT imaging.

Keywords: SwiftScan; bone; image quality; semi-quantification; single-photon emission computed tomography/computed tomography (SPECT/CT).

Figure 1

Flow diagram of the study. ^99mTc-MDP, ^99mTc-stannous methylene diphosphonate; SPECT, single-photon emission computed tomography.

Figure 2

Comparison of image quality on the National Electrical Manufacturers Association phantom using the SwiftScan, SwiftScan-50%, and SS SPECT acquisition modes. CT, computed tomography; SwiftScan, step-and-shoot continuous acquisition mode; SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot; SPECT, single-photon emission computed tomography.

Figure 3

Comparison of the semi-parameters from the National Electrical Manufacturers Association phantom using the SwiftScan, SwiftScan-50% and SS SPECT acquisition modes. SwiftScan, step-and-shoot continuous acquisition mode; SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot; COV, coefficient of variation; SBR, signal-to-background ratio; SPECT, single-photon emission computed tomography.

Figure 4

The visual scores of the image quality attributed to various SPECT acquisition modes; that is, SwiftScan, SS and SwiftScan-50%. SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot; SwiftScan, step-and-shoot continuous acquisition mode; SPECT, single-photon emission computed tomography.

Figure 5

Box plot of the COV, SUVmax, SUVmean, and SBR in the skeletal lesions for the three SPECT acquisition modes (SwiftScan, SwiftScan-50%, and SS). COV was defined as the background SD/SUVmean; while SBR was defined as the lesion SUVmax/background SUVmean; COV, coefficient of variation; SPECT, single-photon emission computed tomography; SBR, signal-to-background ratio; SUVmax, maximum of the standard uptake value; SUVmean, mean of the standard uptake value; SwiftScan, step-and-shoot continuous acquisition mode; SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot.

Figure 6

Comparison of SPECT/CT images using the (A) SwiftScan, (B) SwiftScan-50%, and (C) SS modes. The SUVmax, SUVmean, and SBR of the C7 lesion were 16.50, 9.67, and 47.14 in the SwiftScan, 13.70, 8.00, and 41.52 in the SwiftScan-50%, and 7.98, 4.47, and 38.00 in the SS modes, respectively. CT, computed tomography; IRACRR, iterative reconstruction attenuation correction resolution recovery; SwiftScan, step-and-shoot continuous acquisition mode; SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot; SPECT, single-photon emission computed tomography.

Figure 7

The receiver operating characteristics curves of the (A) SUVmax and (B) SBR for malignant skeletal lesion differentiation using the three SPECT acquisition modes (i.e., SwiftScan, SwiftScan-50%, and SS). SBR is defined as lesion SUVmax/background SUVmean. SUVmax, maximum of the standard uptake value; SwiftScan, step-and-shoot continuous acquisition mode; AUC, area under the curve; SwiftScan-50%, simulates a 50% reduction in acquisition time; SS, step-and-shoot; SBR, signal-to-background ratio; SUVmean, mean of the standard uptake value.