44 research outputs found
Myocardial perfusion imaging with real-time respiratory triggering: Impact of inspiration breath-hold on left ventricular functional parameters
Background: The latest gamma-camera generation with cadmium-zinc-telluride (CZT) detectors allows myocardial perfusion imaging (MPI) with respiratory triggering at breath-hold. We assessed its impact on functional left ventricular (LV) parameters. Methods: Twenty-eight consecutive patients underwent a one-day 99mTc-tetrofosmin pharmacologic stress/rest imaging protocol on a novel CZT camera. Electrocardiogram-gated high-dose (rest) MPI was performed without and with real-time respiratory triggering by intermittent scanning confined to breath-hold at deep inspiration. We studied the effect of respiratory triggering at deep inspiration levels on LV wall motion, wall thickening, LV volumes and ejection fraction (LVEF) compared to regular MPI without respiratory triggering. Results: Compared to regular MPI without respiratory triggering, systolic and diastolic LV volumes and stroke volumes decreased significantly (P<0.05) when respiratory triggering was applied. By contrast, there was no significant change in LVEF, with a high correlation (r=.939, P<0.001) between the two measurements. Furthermore, respiratory triggering introduced a significant change (P<0.05) in regional LV wall motion. Conclusions: Respiratory-triggered MPI with breath-hold at deep inspiration levels introduces significant changes to the measured LV volumes, stroke volumes and regional wall motion but does not significantly affect global LVEF when compared to regular MPI with normal breathin
Nuclear myocardial perfusion imaging with a novel cadmium-zinc-telluride detector SPECT/CT device: first validation versus invasive coronary angiography
Purpose: We evaluated the diagnostic accuracy of attenuation corrected nuclear myocardial perfusion imaging (MPI) with a novel hybrid single photon emission computed tomography (SPECT)/CT device consisting of an ultrafast dedicated cardiac gamma camera with cadmium-zinc-telluride (CZT) solid-state semiconductor detectors integrated onto a multislice CT scanner to detect coronary artery disease (CAD). Invasive coronary angiography served as the standard of reference. Methods: The study population included 66 patients (79% men; mean age 63 ± 11years) who underwent 1-day 99mTc-tetrofosmin pharmacological stress/rest examination and angiography within 3months. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) as well as accuracy of the CT X-ray based attenuation corrected CZT MPI for detection of CAD (≥50% luminal narrowing) was calculated on a per-patient basis. Results: The prevalence of angiographic CAD in the study population was 82%. Sensitivity, specificity, PPV, NPV and accuracy were 87, 67, 92, 53 and 83%, respectively. Conclusion: In this first report on CZT SPECT/CT MPI comparison versus angiography we confirm a high accuracy for detection of angiographically documented CA
Impact of CT attenuation correction on the viability pattern assessed by 99mTc-tetrofosmin SPECT/18F-FDG PET
SPECT myocardial perfusion imaging (MPI) is commonly used for comprehensive interpretation of metabolic PET FDG imaging in ischemic dysfunctional myocardium. We evaluated the difference in scan interpretation introduced by CT attenuation correction (CTAC) of SPECT MPI in patients undergoing viability characterization by 99mTc SPECT MPI/PET FDG. In 46 consecutive patients (mean age 64, range 36-83 years) with dysfunctional myocardium, we analyzed viability from combined SPECT MPI and PET FDG scanning without attenuation correction (NC) and with CTAC for SPECT MPI. FDG uptake was classified in groups of percent uptake using the segment with maximum tracer in SPECT perfusion uptake as reference. Viability patterns were categorized as normal, mismatch, mild match and scar by relative comparison of SPECT and PET. Applying CTAC introduced a different reference segment for the normalization of PET FDG study in 57% of cases. As a result, the flow-metabolism pattern changed in 28% of segments, yielding a normal, mismatch, mild match and scar pattern in 462, 150, 123, and 47 segments with NC and 553, 86, 108, and 35 with CTAC, respectively (P=0.001). Thus, by introducing CTAC for SPECT MPI 25% of segments originally classified as scar were reclassified and the number of normal segments increased by 20%. Introducing CTAC decreased by 54% the number of patients with possible indication for revascularization, from 26/46 to 12/46 (P<0.001). Different interpretation of myocardial viability can be observed when using CTAC instead of NC SPECT MPI as reference for PET FDG scan
Downstream resource utilization following hybrid cardiac imaging with an integrated cadmium-zinc-telluride/64-slice CT device
Purpose: Low yield of invasive coronary angiography and unnecessary coronary interventions have been identified as key cost drivers in cardiology for evaluation of coronary artery disease (CAD). This has fuelled the search for noninvasive techniques providing comprehensive functional and anatomical information on coronary lesions. We have evaluated the impact of implementation of a novel hybrid cadmium-zinc-telluride (CZT)/64-slice CT camera into the daily clinical routine on downstream resource utilization. Methods: Sixty-two patients with known or suspected CAD were referred for same-day single-session hybrid evaluation with CZT myocardial perfusion imaging (MPI) and coronary CT angiography (CCTA). Hybrid MPI/CCTA images from the integrated CZT/CT camera served for decision-making towards conservative versus invasive management. Based on the hybrid images patients were classified into those with and those without matched findings. Matched findings were defined as the combination of MPI defect with a stenosis by CCTA in the coronary artery subtending the respective territory. All patients with normal MPI and CCTA as well as those with isolated MPI or CCTA finding or combined but unmatched findings were categorized as "no match”. Results: All 23 patients with a matched finding underwent invasive coronary angiography and 21 (91%) were revascularized. Of the 39 patients with no match, 5 (13%, p < 0.001 vs matched) underwent catheterization and 3 (8%, p < 0.001 vs matched) were revascularized. Conclusion: Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilizatio
Main pulmonary artery diameter from attenuation correction CT scans in cardiac SPECT accurately predicts pulmonary hypertension
Objectives: To establish the value of the main pulmonary artery (MPA) diameter assessed from unenhanced computer tomography (CT) scans used for attenuation correction (AC) of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) to predict pulmonary hypertension (PHT). Background: In contrast-enhanced chest CT scans an MPA diameter of 29mm or greater is an established predictor of PHT. However, it is unknown, whether measurements from an unenhanced CT scan for AC may be used as predictor of PHT. Methods: 100 patients underwent SPECT MPI for assessment of coronary artery disease. PHT was defined as a right ventriculo-atrial gradient of 30mm Hg or greater by Doppler echocardiography. We compared MPA diameter from CT to SPECT findings (right ventricular hypertrophy/enlargement, septal wall motion abnormality/perfusion defect, and D-shape) to determine the best predictor of PHT. Results: PHT was found in 37 patients. An MPA diameter of 30mm or greater yielded a sensitivity, specificity, accuracy, positive, and negative predictive value of 78%, 91%, 86%, 83%, and 88%, respectively. This yielded an area under the ROC curve of 0.85. Conclusions: MPA diameter from low-dose unenhanced multi-slice CT reliably predicts PHT, providing an important added clinical value from AC for SPECT MP
Diagnostic value of PET-measured heterogeneity in myocardial blood flows during cold pressor testing for the identification of coronary vasomotor dysfunction
Background: We aimed to evaluate the diagnostic value of a positron emission tomography (PET)-measured heterogeneity in longitudinal myocardial blood flow (MBF) during cold pressor testing (CPT) and global MBF response to CPT from rest (ΔMBF) for identification of coronary vasomotor dysfunction. Methods and Results: In 35 patients CPT-induced alterations in epicardial luminal area were determined with quantitative angiography as the reference. MBF was assessed over the whole left ventricle as global MBF and regionally in the mid and mid-distal myocardium as MBF difference or MBF heterogeneity with nitrogen-13 ammonia and PET. The sensitivity and specificity of a longitudinal MBF difference during CPT in the identification of epicardial vasomotor dysfunction were significantly higher, than the global ΔMBF to CPT (88% vs 79% and 82% vs 64%, respectively; P<.05). Combining both parameters resulted in an optimal sensitivity of 100% at the expense of an intermediate specificity of 73%. The diagnostic accuracy was higher for the combined analysis than that for the MBF difference alone and global ΔMBF alone (91% vs 86% and 74%, respectively; P<.05). Conclusions: The combined evaluation of a CPT-induced heterogeneity in longitudinal MBF and the change in global MBF from rest may emerge as a new promising analytic approach to further optimize the identification and characterization of coronary vasomotor dysfunctio
Ultrafast assessment of left ventricular dyssynchrony from nuclear myocardial perfusion imaging on a new high-speed gamma camera
Purpose: To validate the ultrafast assessment of left ventricular (LV) dyssynchrony by phase analysis using high-speed nuclear myocardial perfusion imaging (MPI) on a new gamma camera with cadmium-zinc-telluride (CZT) solid-state detector technology. Methods: In 46 patients rest MPI with 960MBq 99mTc-tetrofosmin was acquired on a dual-head detector SPECT camera (Ventri, GE Healthcare) and an ultrafast CZT camera (Discovery NM 530c, GE Healthcare) with acquisition times of 15 and 5min, respectively. LV dyssynchrony was assessed using the Emory Cardiac Toolbox with established values for histogram bandwidth (male <62.4°; female <49.7°) and standard deviations (male <24.4°; female <22.1°) as the gold standard. Evaluating CZT scan times of 0.5, 1, 2, 3 and 5min (list mode) in 16 patients revealed the preferred scan time to be 5min, which was then applied in all 46 patients. Intraclass correlation and the level of agreement in dyssynchrony detection between the CZT and Ventri cameras were assessed. Results: In LV dyssynchrony the mean histogram bandwidths with the CZT camera (n = 8) and the Ventri camera (n = 9) were 123.3 ± 50.6° and 130.2 ± 43.2° (p not significant) and 42.4 ± 13.6° vs. 43.2 ± 12.7° (p not significant). Normal bandwidths and SD obtained with the CZT camera (35.9 ± 7.7°, 12.6 ± 3.5°) and the Ventri camera (34.8 ± 6.6°, 11.1 ± 2.1°, both p not significant) excluded dyssynchrony in 38 and 37 patients, respectively. Intraclass correlation and the level of agreement between the CZT camera with a 5-min scan time and the Ventri camera were 0.94 (p < 0.001, SEE 14.4) and 96% for histogram bandwidth and 0.96 (p < 0.001, SEE 3.9) and 98% for SD. Conclusion: This ultrafast CZT camera allows accurate assessment of LV dyssynchrony with a scan time of only 5min, facilitating repeat measurements which would potentially be helpful for parameter optimization for cardiac resynchronization therap
Left ventricular dyssynchrony assessment by phase analysis from gated PET-FDG scans
Background: The outcome of patients with severe ischaemic left ventricular (LV) dysfunction is determined by the extent of myocardial viability and the presence of LV dyssynchrony. We aimed at assessing both parameters from the same imaging method, i.e. gated positron emission tomography (PET) F18-fluorodeoxyglucose (FDG) scans. Methods: Phase analysis from Emory Cardiac Toolbox was applied on gated PET-FDG scans to assess histogram bandwidth and standard deviation (SD) as a measure of LV dyssynchrony in 30 heart failure patients (mean ejection fraction: 30.2%±13.8%) referred for the evaluation of myocardial viability. Cut-off values from single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) best predicting cardiac resynchronization therapy (CRT) response served as standard of reference (bandwidth<135°; phase SD<43°). Severe LV dyssynchrony was diagnosed if both SPECT-MPI values were above these limits. Intraclass correlation and clinical agreement in detection of severe LV dyssynchrony by PET vs SPECT were assessed. Results: There was a significant correlation between PET-FDG and SPECT-MPI for bandwidth (r=0.88, P<.001) and phase SD (r=0.88, P<.001) resulting in an excellent clinical agreement between the two methods of 93%. Conclusions: Accurate LV dyssynchrony assessment by phase analysis of gated PET-FDG scans is feasible, allowing assessing myocardial viability and severe LV dyssynchrony in one sca