Left ventricular eccentricity index measured with SPECT myocardial perfusion imaging: An additional parameter of adverse cardiac remodeling.

BACKGROUND: Single-photon emission computed-tomography (SPECT) allows the quantification of LV eccentricity index (EI), a measure of cardiac remodeling. We sought to evaluate the feasibility of EI measurement with SPECT myocardial perfusion imaging and its interactions with relevant LV functional and structural parameters. METHODS AND RESULTS: Four-hundred and fifty-six patients underwent myocardial perfusion imaging on a Cadmium-Zinc-Telluride (CZT) camera. The summed rest, stress, and difference scores were calculated. From rest images, the LV end-diastolic (EDV) and end-systolic volumes, ejection fraction (EF), and peak filling rate (PFR) were calculated. In every patient, the EI, ranging from 0 (sphere) to 1 (line), was computed using a dedicated software (QGS/QPS; Cedars-Sinai Medical Center). Three-hundred and thirty-eight/456 (74%) patients showed a normal EF (>50%), while 26% had LV systolic dysfunction. The EI was computed from CZT images with excellent reproducibility (interclass correlation coefficient: 0.99, 95% CI 0.98-0.99). More impaired EI values correlated with the presence of a more abnormal LV perfusion (P < .001), function (EF and PFR, P < .001), and structure (EDV, P < .001). On multivariate analysis, higher EDV (P < .001) and depressed EF (P = .014) values were independent predictors of abnormal EI. CONCLUSIONS: The evaluation of LV eccentricity is feasible on gated CZT images. Abnormal EI associates with significant cardiac structural and functional abnormalities.

Effect of prolonged fasting and low molecular weight heparin or warfarin therapies on 2-deoxy-2-[18F]-fluoro-D-glucose PET cardiac uptake.

BACKGROUND: Whether anticoagulants other than unfractionated heparin are able to suppress cardiac PET uptake of 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) is unknown. METHODS: One-hundred-seventy-four patients without history and clinical evidence of cardiac dysfunction and/or coronary heart disease underwent a 18F-FDG PET/CT study. All patients were studied with a >12-hours fasting and divided into 2 groups: group-1 without anticoagulant therapy (n:75); group-2 patients on low molecular weight heparin (n:60) or warfarin therapy (n:39). Cardiac 18F-FDG uptake was estimated qualitatively using a 4-point scale and semiquantitatively as total LV glycolysis (LVG) and metabolic volume (MV), drawing isocontour volume of interest (VOI) including the whole LV. RESULTS: Qualitatively, LV 18-FDG uptake was scored 0 or 1, indicating a good suppression, in 10/75 (13%) patients of group-1 and 77/99 (78%) of group-2 (p < .001). Semiquantitatively, patients of group-1 showed higher values of 18-FDG uptake than patients of group-2, assessed as LVG (802,649 ± 468,442 vs 198,989 ± 261,439, p < .0001) or MV (219 ± 77 vs 57 ± 48 cm3, p < .0001). Subanalysis for anticoagulant drugs showed similar results. CONCLUSIONS: Prolonged fasting combined to anticoagulants other than unfractionated heparin is able to minimize glucose cardiac metabolism. Our data confirm previous observation on the possibility to influence the metabolic pattern of the heart before the PET scan and broadens the spectrum of pharmacological options.

Evaluation of left ventricular diastolic function with a dedicated cadmium-zinc-telluride cardiac camera: comparison with Doppler echocardiography.

AIMS: To evaluate the relationships between measures of left ventricular (LV) filling dynamics at cadmium-zinc-telluride (CZT) imaging and indexes of LV diastolic function at transthoracic echocardiography. METHODS AND RESULTS: Two hundred and forty-seven patients underwent myocardial perfusion imaging at rest and after stress with a low-dose CZT protocol and a baseline transthoracic echocardiography study. All patients were submitted to invasive or computed coronary angiography. The peak filling rate (PFR) and the time to PFR (TPFR) were derived from gated CZT images as measures of LV filling dynamics. LV diastolic function was also evaluated at echocardiography and the presence of significantly increased LV filling pressures determined. Increased LV filling pressures at transthoracic echocardiography were evident in 103 (42%) patients. Interestingly, independently from the presence of coronary artery disease, there was a strict correlation between the presence and severity of LV diastolic dysfunction at echocardiography and CZT-derived measures of filling dynamics, i.e., PFR (P = 0.001) and TPFR (P = 0.001). At receiving operating characteristic analysis, a composite index of reduced PFR (≤2.11 end-diastolic volume s(-1)) and increased TPFR (>234 ms) showed a sensitivity of 84% and a specificity of 67% in unmasking the presence of elevated LV filling pressures at echocardiography. CONCLUSIONS: CZT-derived measures of LV filling dynamics correlate with echocardiographic parameters of diastolic function and may identify the presence of increased LV filling pressures.

Gated SPECT evaluation of left ventricular function using a CZT camera and a fast low-dose clinical protocol: comparison to cardiac magnetic resonance imaging.

PURPOSE: CZT technology allows ultrafast low-dose myocardial scintigraphy but its accuracy in assessing left ventricular function is still to be defined. METHODS: The study group comprised 55 patients (23 women, mean age 63 ± 9 years) referred for myocardial perfusion scintigraphy. The patients were studied at rest using a CZT camera (Discovery NM530c; GE Healthcare) and a low-dose (99m)Tc-tetrofosmin clinical protocol (mean dose 264 ± 38 MBq). Gated SPECT imaging was performed as a 6-min list-mode acquisition, 15 min after radiotracer injection. Images were reformatted (8-frame to 16-frame) using Lister software on a Xeleris workstation (GE Healthcare) and then reconstructed with a dedicated iterative algorithm. Analysis was performed using Quantitative Gated SPECT (QGS) software. Within 2 weeks patients underwent cardiac magnetic resonance imaging (cMRI, 1.5-T unit CVi; GE Healthcare) using a 30-frame acquisition protocol and dedicated software for analysis (MASS 6.1; Medis). RESULTS: The ventricular volumes obtained with 8-frame QGS showed excellent correlations with the cMRI volumes (end-diastolic volume (EDV), r = 0.90; end-systolic volume (ESV), r = 0.94; p < 0.001). However, QGS significantly underestimated the ventricular volumes (mean differences: EDV, -39.5 ± 29 mL; ESV, -15.4 ± 22 mL; p < 0.001). Similarly, the ventricular volumes obtained with 16-frame QGS showed an excellent correlations with the cMRI volumes (EDV, r = 0.92; ESV, r = 0.95; p < 0.001) but with significant underestimations (mean differences: EDV, -33.2 ± 26 mL; ESV, -17.9 ± 20 mL; p < 0.001). Despite significantly lower values (47.9 ± 16 % vs. 51.2 ± 15 %, p < 0.008), 8-frame QGS mean ejection fraction (EF) was closely correlated with the cMRI values (r = 0.84, p < 0.001). The mean EF with 16-frame QGS showed the best correlation with the cMRI values (r = 0.91, p < 0.001) and was similar to the mean cMRI value (49.6 ± 16 %, p not significant). Regional analysis showed a good correlation between both 8-frame and 16-frame QGS and cMRI wall motion score indexes (8-frame WMSI, r = 0.85; 16-frame WMSI, r = 0.89; p < 0.01). CONCLUSION: Low-dose gated SPECT with a CZT camera provides ventricular volumes that correlate well with cMRI results despite significant underestimation in the measure values. EF estimation appeared to be more accurate with 16-frame reformatted images than with 8-frame images.