Evaluating the Role of Routine Prone Acquisition on Visual Evaluation of SPECT Images

Abstract

Attenuation artifacts reduce our ability to evaluate perfusion of affected myocardial segments. The aim of this study was to evaluate the impact of routine prone-position image evaluation within a stepwise visual interpretation of myocardial perfusion studies. Methods: We have included 279 consecutive patients who were referred for evaluation of myocardial ischemia. All patients underwent routine electrocardiogram-gated supine SPECT imaging and non-electrocardiogram-gated proneposition SPECT imaging. Three nuclear medicine physicians interpreted the images in the following order: polar maps, supine images, raw images, motion-frozen gated images, and prone images, using a scale of 0-4. Segments with perfusion abnormalities were noted. Results: All physicians reported lower proportions of equivocal evaluations after evaluating prone images (18.3% vs. 4.7%, 19% vs. 11.1%, and 12.2% vs. 6.1%, P , 0.0001, P 5 0.0077, and P 5 0.0125, respectively). At the prone stage, normalcy rates were 89%, 87%, and 91%. Two physicians had significantly increased normalcy rates at the prone stage (72%-89%, P 5 0.039, and 66%-87%, P 5 0.006). At the prone stage, a decision reversal to normal or probably normal was observed in 40% (29/72), 33% (17/51), and 43% (21/48). In men, apical, mid, and basal inferior walls and in women apical and mid parts of anterior walls were more likely to be attributed to attenuation. The 2 steps that increased normalcy rates for interpreters were the review of raw images and of prone images. Conclusion: Routine prone imaging increases interpretive certainty and interobserver agreement and changes the final evaluation in a substantial number of patients and significantly decreases the number of equivocal evaluations.

Worldwide Variation in the Use of Nuclear Cardiology Camera Technology, Reconstruction Software, and Imaging Protocols

“…Guidelines indicate that the addition of prone positioning may help distinguish attenuation artifact from potential perfusion defects, thereby reducing the rate of false positive studies. (37,38) A study of 279 patients who underwent both prone and supine imaging reported that prone positioning reversed 40% of scans from potentially abnormal to normal or probably normal. (38) Hence, the use of multiple positions in stress-first protocols should increase the number of stress-only studies, thereby reducing radiation exposure.…”

“…(37,38) A study of 279 patients who underwent both prone and supine imaging reported that prone positioning reversed 40% of scans from potentially abnormal to normal or probably normal. (38) Hence, the use of multiple positions in stress-first protocols should increase the number of stress-only studies, thereby reducing radiation exposure. Multiple-position imaging was performed in just 7% of cases in our cohort.…”

Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging Guidelines: Instrumentation, Acquisition, Processing, and Interpretation

“…44,45 The combination of supine and prone images (2-position imaging) may be helpful identifying attenuation artifacts due to the shift in position of the attenuating structures that occur in the prone position and can improve interpretive confidence and accuracy. [46][47][48] By comparing supine and prone images, artifactual defects will resolve or change their location whereas true perfusion defects will remain in the same position. 19,49 When being used in this fashion, the acquisition time for the secondary (prone) image set can be reduced by 20% to 40%.…”

“…172 Of note, AC was performed in most series that showed the efficacy of low dose stress-only SPECT imaging, and the use of AC, upright/supine or supine/ prone imaging (Figure 27), advanced post processing, or advanced camera designs substantially increases the number of patients that can be imaged stress-only. 46,173 Another argument for stress-first / stress-only imaging comes from an unexpected finding from the recently published EXERRT study. 174 In particular, the results of the EXERRT study imply for the first time that a sameday rest-stress protocol may not be optimal for identification of regadenoson-induced perfusion defects and ischemia.…”

Radiation Safety in Children With Congenital and Acquired Heart Disease

“…Here, stress testing and stress imaging is performed first, with stress images reviewed by an attending nuclear cardiology physician before any rest imaging, and rest imaging (with its attendant radiation dose) omitted if stress perfusion and left ventricular function, wall motion, and size are all normal ( 84 ). Multiple-position imaging, which for most cameras entails both supine and prone imaging, has been demonstrated to increase the normalcy rate of stress imaging and thus can increase the proportion of children not requiring subsequent rest imaging ( 85 ). In children, when rest imaging is needed, it should be performed on a later day than stress imaging, using the same administered activity (mCi), because same-day stress–rest myocardial perfusion imaging requires a rest activity of 3 to 4 times the stress dose to minimize the effect of residual stress activity on the rest study (“shine-through artifact”) ( 86 ).…”