IQ·SPECT technology and its clinical applications using multicenter normal databases

Abstract

IQ·SPECT (Siemens Medical Solutions) is a solution for high-sensitivity and short-time acquisition imaging of the heart for a variable angle general purpose gamma camera. It consists of a multi-focal collimator, a cardio-centric orbit and advanced iterative reconstruction, modeling the image formation physics accurately. The multi-focal collimator enables distance-dependent enlargement of the center region while avoiding truncation at the edges. With the specified configuration and a cardio-centric orbit it can obtain a fourfold sensitivity increase for the heart at the center of the scan orbit. Since IQ·SPECT shows characteristic distribution patterns in the myocardium, appropriate acquisition and processing conditions are required, and normal databases are convenient for quantification of both normal and abnormal perfusion images. The use of prone imaging can be a good option when X-ray computed tomography (CT) is not available for attenuation correction. CT-based attenuation correction changes count distribution significantly in the inferior wall and around the apex, hence image interpretation training and additional use of normal databases are recommended. Recent reports regarding its technology, Japanese Society of Nuclear Medicine working group activities, and clinical studies using 201Tl and 99mTc-perfusion tracers in Japan are summarized.

EANM procedural guidelines for myocardial perfusion scintigraphy using cardiac-centered gamma cameras

“…Prone imaging compensates for these attenuated inferior myocardial counts to some extent. Although AC compensated for inferior low myocardial counts, low counts at the apex were observed (Nakajima et al 2017 ). When the myocardial perfusion distributions of IQ-SPECT 99m Tc and 201 Tl normal databases were visually compared, they showed a similar pattern.…”

“…When the myocardial perfusion distributions of IQ-SPECT 99m Tc and 201 Tl normal databases were visually compared, they showed a similar pattern. However, attenuation-corrected myocardial counts at the apex were lower in 201 Tl supine imaging than in 99m Tc supine imaging (Nakajima et al 2017 ). If an abnormality is seen only on the AC images while the NAC images look normal, an AC artifact is then very likely (e.g., due to misregistration of CT and SPECT images since alignment cannot always be perfect or due to a notch artifact on the left margin of the heart, a finding that is not uncommon with single-slice or two-slice CT scans).…”

Multimodality imaging of the left ventricle: Choosing soundly

“…This is largely achieved by using a multifocal collimator and cardiocentric orbit on a variable angle gamma camera. 8 Imaging geometry creates unique attenuation artifact in IQ-SPECT, but this can be significantly reduced with CT attenuation correction. 9,10 SUMMARY Given the multimodality approach that clinicians can take to assess and validate LVEF, it is imperative that both referring and interpreting clinicians understand the advantages and disadvantages of each; specifically, how those align with an individual patient and clinical scenario.…”

Cost-effectiveness Analysis of Anatomic vs Functional Index Testing in Patients With Low-Risk Stable Chest Pain

“… 1 Nearly all of these tests target functional assessment of myocardial ischemia (64%, nuclear imaging with single photon emission computed tomography [SPECT]; 31%, stress echocardiography). 2 , 3 However, the positive predictive value of these tests for anatomically obstructive CAD in patients referred to invasive coronary angiography (ICA) remains low (38%). 4 Meanwhile, coronary computed tomography angiography (CTA), a test permitting noninvasive visualization of CAD, is currently performed in less than 5% of chest pain evaluations.…”