Absolute Quantification of Left Ventricular Global and Regional Function at Nuclear MPI Using Ultrafast CZT SPECT: Initial Validation Versus Cardiac MR

Abstract

We sought to evaluate the accuracy of myocardial perfusion imaging (MPI) using cadmium-zinc-telluride (CZT) SPECT cameras for the measurement of left ventricular (LV) global and regional function, and the performance of absolute wall motion (WM) and wall thickness (WT) measurements for the detection of myocardial scarring, using cardiac MR as a reference. Methods: Sixty patients with known or suspected coronary artery disease underwent MPI using a CZT SPECT camera, as well as cine and delayed enhanced cardiac MR. Gated MPI data were processed using quantitative gated SPECT software. LV global function was assessed by measuring LV end-diastolic volume (EDV), endsystolic volume (ESV), and ejection fraction (EF). Regional function was assessed by quantifying segmental WM and WT according to the 17-segment model. Myocardial scarring was quantified on each segment using delayed enhanced cardiac MR. Agreement between SPECT and cardiac MR was assessed using Pearson correlation and Bland-Altman analyses. The influence of measurement magnitude on the agreement was analyzed using Spearman correlation coefficients between the mean and SD of measurements. The performance of WM and WT for the detection of segments with more than 25% scar transmurality was assessed using receiver-operating-characteristic analysis. Results: Correlation between methods was excellent for EF (R 5 0.81, P , 0.0001) and ESV (R 5 0.88, P , 0.0001) and was good for EDV (R 5 0.71, P , 0.0001). Agreement was good for EF (bias, 22.7%; limits of agreement, 215.5 to 110.1) but was lower for EDV (bias, 229.7 mL; limits of agreement, 268.3 to 18.9) and ESV (bias, 29.9 mL; limits of agreement, 230.7 to 110.9). Correlation between methods was fair for WM (R 5 0.49, P , 0.0001) and WT (R 5 0.48, P , 0.0001). SPECT underestimated WT (bias, 241%; limits of agreement, 2108 to 126), with an error depending on thickening magnitude (r 5 0.70, P , 0.0001). The agreement in WM measurement was higher (bias, 21.4 mm; limits of agreement, 26.9 to 14) and independent of motion magnitude (r 5 0.006, P 5 0.86). WM and WT were equally able to identify scarred segments (area under the receiver-operating-characteristic curve, 0.74 6 0.03 and 0.74 6 0.03, respectively). Conclusion: MPI using CZT SPECT cameras and quantitative gated SPECT analysis accurately quantifies EF but still underestimates LV volumes. WM shows a higher agreement with cardiac MR than does WT, with errors in WT measurement increasing at greater thicknesses. Absolute quantification of segmental WM and WT can equally be used to identify myocardial scarring.

Left Ventricular Function Assessment Using 2 Different Cadmium-Zinc-Telluride Cameras Compared with a γ-Camera with Cardiofocal Collimators: Dynamic Cardiac Phantom Study and Clinical Validation

“…We previously demonstrated that the increased spatial resolution provided by CZT-based detectors may lead to an underestimation of regional myocardial wall thickening under hypertrophic conditions (12). In contrast, agreement with cardiac MR was stronger for myocardial wall motion than for wall thickening (12,13). The present study demonstrated that regional myocardial wall thickening was decreased for the DNM, compared with the D-SPECT, whereas there was no significant difference in myocardial wall motion.…”

“…In patients, the assessment of LV volume and LVEF has been validated against cardiac MR (12,13,29). Using the same software package for a DNM camera and a cardiac MR system, Giorgetti et al (29) found an excellent correlation for both EDV (r 5 0.92) and ESV (r 5 0.95), although there was a significant underestimation with the DNM camera (mean difference, 233.2 6 26 mL for EDV and 217.9 6 20 mL for ESV; P , 0.001).…”

“…Previous publications have validated the performance and results of these cameras versus the conventional Anger camera in clinical practice (9,10), but recent data demonstrated that when quantitative gated SPECT is performed using CZT cameras instead of Anger cameras, LV volume is overestimated, leading to a lower estimated LVEF in healthy patients (11). This difference is likely related to the increased spatial resolution, a condition that also significantly affects the assessment of segmental wall motion and thickening (12,13). Alternatively, the multifocal collimators of IQ-SPECT technology (Siemens Healthcare) can be plugged into multipurpose cameras, offering better sensitivity and contrast-tonoise ratio than conventional Anger cameras equipped with lowenergy, high-resolution collimators (14).…”

What is the value of motion and thickening in gated myocardial perfusion SPECT?

“…Indeed, several studies demonstrated a significant underestimation of wall thickening assessed by CZT SPECT compared to cardiac MR. Cochet et al demonstrated higher agreement with MR for wall motion than wall thickening, with errors in wall thickening measurement increasing at greater thicknesses. 29 In a phantom study, Bailliez et al also demonstrated underestimation of regional wall thickening by CZT SPECT compared to cardiac MR, especially in patients with increased wall thickness. 30 Thus, using a CZT camera, assessment of regional wall motion might be preferred over thickening evaluation, particularly in patients with left ventricular hypertrophy.…”

The time for radionuclide ventriculography resurrection is coming

“…The accuracy of gated MPI-SPECT has been documented in comparison to MR 11,12 but not yet for gated blood pool SPECT by CZT cameras. A comparison between MR and CZT gated blood pool ventriculography for measuring right and left ventricular EF and volumes will be an important next step.…”