Yoshiko Nishiyama

Three-dimensional phase-sensitive inversion recovery sequencing in the evaluation of left ventricular myocardial scars in ischemic and non-ischemic cardiomyopathy: Comparison to three-dimensional inversion recovery sequencing

BACKGROUND Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is a useful technique for detecting myocardial fibrosis. LGE images are typically acquired using the inversion recovery (IR) method. Recently, phase-sensitive inversion recovery (PSIR) technology has been developed. The purpose of this study was to evaluate free-breathing 3D PSIR sequencing in comparison with breath-held 3D IR sequencing for the detection of myocardial fibrosis. METHODS One hundred twenty-three patients with suspected ischemic cardiac disease (n=27) or non-ischemic cardiomyopathy (hypertrophic cardiomyopathy, n=29; dilated cardiomyopathy, n=22; sarcoidosis, n=21; arrhythmia, n=9; myocarditis, n=4; amyloidosis, n=3; and others, n=8) were evaluated by LGE-MRI, which was performed first with the IR sequence and then with the PSIR sequence, using a 3T MRI scanner. Image quality was scored by two independent readers using a four-point scale. The 3D LGE volume was analyzed quantitatively and compared between both sequencing methods. RESULTS There was no significant difference in overall image quality (p=0.19). LGE was detected in 73 patients, who were evaluated visually. Ultimately, 58 patients with acceptable image quality were enrolled in further quantitative analyses (volume assessment). Although quantification of LGE volume revealed a strong correlation between both methods, larger LGE volumes were detected with PSIR compared to IR in patients suspected of non-ischemic cardiomyopathy (39.5 ± 25.9 cm(3) for PSIR and 32.8 ± 23.9 cm(3) for IR, p<0.001). The LGE volume did not differ significantly in patients suspected of ischemic cardiac disease (17.9 ± 12.7 cm(3) for PSIR and 17.5 ± 11.1cm(3) for IR, p=0.34). CONCLUSIONS 3D PSIR is suitable for detection of LGE and may be an option in cases with IR images of unacceptable quality but overestimates LGE volume in non-ischemic cardiomyopathy.

Quantitative circumferential strain analysis using adenosine triphosphate-stress/rest 3-T tagged magnetic resonance to evaluate regional contractile dysfunction in ischemic heart disease

PURPOSE We evaluated whether a quantitative circumferential strain (CS) analysis using adenosine triphosphate (ATP)-stress/rest 3-T tagged magnetic resonance (MR) imaging can depict myocardial ischemia as contractile dysfunction during stress in patients with suspected coronary artery disease (CAD). We evaluated whether it can differentiate between non-ischemia, myocardial ischemia, and infarction. We assessed its diagnostic performance in comparison with ATP-stress myocardial perfusion MR and late gadolinium enhancement (LGE)-MR imaging. METHODS In 38 patients suspected of having CAD, myocardial segments were categorized as non-ischemic (n=485), ischemic (n=74), or infarcted (n=49) from the results of perfusion MR and LGE-MR. The peak negative CS value, peak circumferential systolic strain rate (CSR), and time-to-peak CS were measured in 16 segments. RESULTS A cutoff value of -12.0% for CS at rest allowed differentiation between infarcted and other segments with a sensitivity of 79%, specificity of 76%, accuracy of 76%, and an area under the curve (AUC) of 0.81. Additionally, a cutoff value of 477.3ms for time-to-peak CS at rest allowed differentiation between infarcted and other segments with a sensitivity of 61%, specificity of 91%, accuracy of 88%, and an AUC of 0.75. The differences in CS values between ATP-stress and rest conditions (ΔCS) in non-ischemic segments (median [first quartile, third quartile] -1.7 [-3.2, -0.1] %) were smaller than in segments with ischemia (+1.1 [+0.3, +2.3] %, p<0.001). A cutoff value of +0.3% for the ΔCS value could differentiate segments with ischemia from non-ischemic segments with a sensitivity of 75%, a specificity of 82%, an accuracy of 82%, and an AUC of 0.86. CONCLUSIONS Circumferential strain analysis using tagged MR can quantitatively assess contractile dysfunction in ischemic and infarcted myocardium.

Novel Cardiac SPECT Technology with Semiconductor Detectors: Emerging Trends and Future Perspective

Recently, two vendors have introduced novel SPECT scanners with solid-state semiconductor detectors: Discovery NM530c(D530c)and D-SPECT utilizing the same cadmium zinc-telluride(CZT) detectors, with a different combination of high-sensitivity multi-pinhole or parallel-hole collimator which focuses on the myocardium. The physical performance is dramatically higher than that of conventional Anger cameras, however, 2 CZT cameras are inherently different. Spatial resolution and contrast-to-noise ratio are better with the D530c, whereas detection sensitivity is higher with the D-SPECT. Although Tc-labeled myocardial perfusion tracers might not be ideal, estimation of absolute myocardial blood flow or coronary flow reserve using dynamic CZT SPECT is of great interest and a challenging subject.

Estimation of myocardial flow reserve utilizing an ultrafast cardiac SPECT: Comparison with coronary angiography, fractional flow reserve, and the SYNTAX score

BACKGROUND Quantitative assessment of myocardial flow reserve (MFR) by single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is challenging but may facilitate evaluation of multi-vessel coronary artery disease (CAD). METHODS We enrolled 153 patients with suspected or known CAD, referred for pharmacological stress MPI. They underwent a 99mTc-perfusion stress/rest SPECT with an ultrafast cadmium-zinc-telluride (CZT) camera. Dynamic data were acquired and time-activity curves fitted to a 1-tissue compartment analysis with input function. K1 was assigned for stress and rest data. The MFR index (MFRi) was calculated as K1 stress/K1 at-rest. The findings were validated by invasive coronary angiography in 69 consecutive patients. RESULTS The global MFRi was 1.46 (1.16-1.76), 1.33 (1.12-1.54), and 1.18 (1.01-1.35), for 1-vessel disease (VD), 2-VD, and 3-VD, respectively. In the 3-VD, global MFRi was lower than that in 0-VD (1.63 [1.22-2.04], P<0.0001) and 1-VD (P=0.003). Multivariate logistic regression analysis for 3-VD showed significant associations with smoking history (odds ratio [OR]: 4.4 [0.4-8.4]), left ventricular ejection fraction (OR: 61.6 [57.5-66.0]), and global MFRi (OR: 119.6 [111.5-127.7], P=0.002). A cut-off value of 1.3 yielded 93.3% sensitivity and 75.9% specificity for diagnosing 3-VD. Fractional flow reserve positively correlated with regional MFRi (r=0.62, P=0.008), and the SYNTAX score correlated negatively with global MFRi (r=0.567, P=0.0003). CONCLUSION We developed and validated a clinically available method for MFR quantification by dynamic 99mTc-perfusion SPECT utilizing a CZT camera, which improves the detectability of multi-vessel CAD.

Emerging Trends and Future Perspective of Novel Cardiac SPECT Technology

In response to concerns about overuse and increasing radiation exposure of myocardial perfusion imaging, nuclear medicine societies have declared statements aimed at lowering its radiation dose and costs. Simultaneously, two vendors have launched novel SPECT scanners with solid-state semiconductor detectors. Discovery NM 530c and D-SPECT utilize the same cadmium zinc telluride (CZT) detectors with a different combination of high-sensitivity multi-pinhole or parallel-hole collimator which focuses on the heart. The physical performance of those is dramatically higher than that of conventional Anger cameras; however, 2 CZT cameras are inherently different.