Impact of the Adaptive Statistical Iterative Reconstruction Technique on Radiation Dose and Image Quality in Bone SPECT/CT

Abstract

The purpose of this study was to compare a routine bone SPECT/CT protocol using CT reconstructed with filtered backprojection (FBP) with an optimized protocol using low-dose CT images reconstructed with adaptive statistical iterative reconstruction (ASiR). Methods: In this prospective study, enrolled patients underwent bone SPECT/CT, with 1 SPECT acquisition followed by 2 randomized CT acquisitions: FBP CT (FBP; noise index, 25) and ASiR CT (70% ASiR; noise index, 40). The image quality of both attenuation-corrected SPECT and CT images was visually (5-point Likert scale, 2 interpreters) and quantitatively (contrast ratio [CR] and signal-to-noise ratio [SNR]) estimated. The CT dose index volume, dose-length product, and effective dose were compared. Results: Seventy-five patients were enrolled in the study. Quantitative attenuation-corrected SPECT evaluation showed no inferiority for contrast ratio and SNR issued from FBP CT or ASiR CT (respectively, 13.41 ± 7.83 vs. 13.45 ± 7.99 and 2.33 ± 0.83 vs. 2.32 ± 0.84). Qualitative image analysis showed no difference between attenuation-corrected SPECT images issued from FBP CT or ASiR CT for both interpreters (respectively, 3.5 ± 0.6 vs. 3.5 ± 0.6 and 3.6 ± 0.5 vs. 3.6 ± 0.5). Quantitative CT evaluation showed no inferiority for SNR between FBP and ASiR CT images (respectively, 0.93 ± 0.16 and 1.07 ± 0.17). Qualitative image analysis showed no quality difference between FBP and ASiR CT images for both interpreters (respectively, 3.8 ± 0.5 vs. 3.6 ± 0.5 and 4.0 ± 0.1 vs. 4.0 ± 0.2). Mean CT dose index volume, dose-length product, and effective dose for ASiR CT (3.0 ± 2.0 mGy, 148 ± 85 mGy⋅cm, and 2.2 ± 1.3 mSv) were significantly lower than for FBP CT (8.5 ± 3.7 mGy, 365 ± 160 mGy⋅cm, and 5.5 ± 2.4 mSv). Conclusion: The use of 70% ASiR blending in bone SPECT/CT can reduce the CT radiation dose by 60%, with no sacrifice in attenuation-corrected SPECT and CT image quality, compared with the conventional protocol using FBP CT reconstruction technique.

On the optimization of bone SPECT/CT in terms of image quality and radiation dose

“…The SPECT/CT image assessment was based on methodology described in Ref. 17. For the qualitative analysis, the SPECT/CT images were visually assessed by two observers in a masked manner.…”

“…Lower values in turn minimize exposure, but can also lead to lower diagnostic CT image value. Two publications presenting studies on the optimization of the patient dose as well as the CT image quality as a part of bone SPECT/CT examination can be found in the literature 17,18 . In both articles, the authors compared only two sets of CT exposure parameters.…”

Palladium-based nanomaterials for cancer imaging and therapy

“…Single photon emission computed tomography (SPECT), as a quantitative nuclear imaging method, can provide 3-dimensional spatial images of the in vivo distribution of injected radioisotopes, and plays an important role in preclinical and clinical research 34 - 36 . The commonly used radioisotopes for SPECT include 99m Tc 37 , 131 I 38 , 125 I 39 , 111 In 40 , 177 Lu 41 , and 67 Ga 42 . Compared with traditional optical imaging technologies, SPECT exhibits great potential in clinical applications with unlimited penetration depth.…”

SPECT/CT: Standing on the Shoulders of Giants, It Is Time to Reach for the Sky!

“…From approximately 2010 onward, highend multislice CT variants have been part of all SPECT/CT portfolios. At the same time, iterative reconstruction techniques for CT were gradually introduced, reducing ionizing radiation doses up to 80% without loss of image quality and solving, in part, one of the initial barriers in the implementation of SPECT/CT (18). Around 2013, SPECT/CT as a hybrid modality had come of age, available with a full set of technical capabilities (enabling correction for attenuation, scatter, partial volume, and motion).…”