Assessment of regional myocardial wall motion and thickening by gated 99Tcm-tetrofosmin SPECT: a comparison with magnetic resonance imaging

Abstract

Gated single photon emission computed tomography (SPECT) imaging allows the simultaneous assessment of both perfusion and function by using one single study. The assessment of regional wall motion and thickening pattern with gated SPECT allows viability studies to be performed. Magnetic resonance imaging (MRI) is well validated for the assessment of myocardial wall motion and thickening in patients with normal and impaired ventricular function. The aim of the study was to analyse the concordance between wall motion and thickening scores derived by gated SPECT and MRI imaging. Furthermore, the agreement for myocardial wall motion and thickening according to myocardial perfusion was analysed with both techniques. We studied a group of 21 patients, including 13 with a previous myocardial infarction (all more than 4 months before the study), using both gated SPECT 99Tcm-tetrofosmin myocardial perfusion imaging and MRI. A 13-segment model was used for both gated SPECT and MRI and each segment was visually scored using a scale of 1-3 for wall motion and thickening. There was a high agreement between gated SPECT and MRI for both wall motion (229/273, 84%; k = 0.72, P<0.001) and wall thickening (236/273, 86%; k = 0.77, P<0.001). The agreement for wall motion and thickening was 80% (k = 0.66) and 83% (k = 0.70), respectively, for patients with myocardial infarction; and 90% (k = 0.81) and 92% (k = 0.86), respectively (P = NS), for patients without myocardial infarction. Agreement in segmental wall motion and thickening scores between gated SPECT and MRI was 90% (k = 0.80) and 91% (k = 0.84), respectively, for segments with normal or mild to moderate hypoperfusion; and 71% (k = 0.45) and 77% (k = 0.57), respectively, for segments with severe hypoperfusion or no perfusion. Of the 70 (41%) segments that had severely diminished or no perfusion in post-myocardial infarction patients, 22 (31%) showed preserved wall motion and 17 (24%) showed preserved wall thickening both by gated SPECT and MRI, suggesting residual myocardial viability in malperfused segments. Our results suggest that gated SPECT imaging is a reliable tool for the assessment of regional wall motion and thickening in patients with known or suspected coronary artery disease. In patients with a previous myocardial infarction gated SPECT imaging has the potential to detect preserved wall motion and thickening in regions with fixed perfusion defects indicating the potential presence of residual myocardial viability.

Evaluation of the Quantitative Gated SPECT (QGS) software program in the presence of large perfusion defects

“…Generally in mixed datasets, the concordance with regard to the LVEF is good for contrast ventriculography and ultrasound techniques [6][7][8][9]. Similarly, the concordance with regard to wall thickening is quite good [12]. Some data are also available on wall motion, but these data are usually limited to the use of an ordinal scale, rating wall motion as normal, hypokinetic, akinetic or dyskinetic.…”

“…Some data are also available on wall motion, but these data are usually limited to the use of an ordinal scale, rating wall motion as normal, hypokinetic, akinetic or dyskinetic. When using this ordinal scale, concordance with contrast ventriculography and ultrasound is good [12]. The methods used in literature so far, however focused on global comparisons in heterogeneous groups of patients, thereby diluting systematic discrepancies in case of specific defects or artifacts.…”

“…In which quantitative assessment of end-diastolic and end-systolic perfusion, wall motion and wall thickening using the 20-segment bull's eye representation of the QGS model [ figure 2], as well as estimates for end-diastolic (EDV) and end-systolic (ESV) ventricular volume and derived stroke volume and LVEF is incorporated. The underlying algorithms have been reviewed in literature [2][3][4][5][6][7][8][9][10][11][12][13]17]. The software algorithm implementation is the same in the different camera systems.…”

“…With regard to the validation of the Cedars-Sinai's Quantitative SPECT (QGS) software, several requirements have already been met. The algorithm and its basic validation have already been described [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, one particular issue is still not fully solved: reproducibility of the quantitative assessment of regional functional parameters in the presence of severe major defects or artifacts.…”

Heart chambers and whole heart segmentation techniques: review

“…[187][188][189] In addition, gated SPECT has been extensively validated against various two-dimensional imaging techniques, such as echocardiography, 192 but there are only a limited number of studies comparing gated SPECT with other three-dimensional techniques such as cardiac MRI, which is considered the reference standard for assessing LV volumes. [193][194][195][196] Visual interpretations of wall motion by observers on the two modalities have been compared along with LV volumes [193][194][195][196] but quantitative comparison for assessment of regional wall motion/thickening has not been reported previously. Using echocardiographic sequences, values of LV volumes, EF, and regional endocardial shortening also correlate with MR. Cardiac MRI was used as a reference method for comparison with unenhanced and contrast-enhanced echocardiography.…”