Patient-specific SPECT imaging protocols to standardize image noise
- 52 Downloads
In addition to acquired photon counts, image noise depends on the image reconstruction algorithm. This work develops patient-specific activity or acquisition time protocols to standardize the average noise in a reconstructed image for different patients, cameras, and reconstruction algorithms.
Image noise was calculated for images from 43 patients acquired on both a conventional and a multiple-pinhole cardiac SPECT camera. Functions were found to relate image noise to radiotracer activity, scan time, and body mass and were validated by normalizing the image noise in a test set of 58 patients.
There was a 3.6-fold difference in photon sensitivity between the two cameras but a 16-fold difference in activity-scan time was necessary to match the noise levels. Image noise doubled from 45 to 128 kg for the conventional camera (12.8 minutes) and tripled for the multiple-pinhole camera (5 minutes) for 350 MBq (9.5 mCi) 99mTc-tetrofosmin. It was 16.3% and 6.1% respectively for an average sized patient.
A linear scaling of activity with respect to the patient weight normalizes image noise but the scaling factors depend on the choice of camera and image reconstruction parameters. Therefore, equivalent numbers of acquired photon counts are not sufficient to guarantee equivalent image noise.
KeywordsSPECT myocardial perfusion imaging activity image noise patient-centered imaging
Decay-corrected activity-scan time protocol
GE discovery NM530c SPECT camera
Maximum a posteriori expectation maximization
Myocardial perfusion imaging
Ordered-subset expectation maximization
One-step-late Green’s prior
Single photon emission computed tomography
J. M. Renaud is a consultant for Jubliant DraxImage Inc. and receives royalties for software sales from FlowQuant and Invia Medical Imaging Solutions. R. G. Wells receives research support and honoraria from GE Healthcare for speaking at meetings. S. G. Cuddy-Walsh and D. C. Clackdoyle have nothing to disclose.
- 1.Dorbala S, Ananthasubramaniam K, Armstrong IS, Chareonthaitawee P, DePuey EG, Einstein AJ, et al. Single photon emission computed tomography (SPECT) myocardial perfusion imaging guidelines: Instrumentation, acquisition, processing, and interpretation. J Nucl Cardiol 2018;25:1784.CrossRefGoogle Scholar
- 5.Oddstig J, Hindorf C, Hedeer F, Jögi J, Arheden H, Hansson MJ, et al. The radiation dose to overweighted patients undergoing myocardial perfusion SPECT can be significantly reduced: Validation of a linear weight-adjusted activity administration protocol. J Nucl Cardiol 2017;24:1912-21.CrossRefGoogle Scholar