Novel indices representing heterogeneous distributions of myocardial perfusion imaging.

INTRODUCTION: Heterogeneous distribution in myocardial perfusion images (MPI) obtained by scintigraphy is often observed in cardiac diseases with normal myocardial perfusion. However, quantitative assessments of such heterogeneity have not been established. We hypothesized that the heterogeneity in MPI can be quantitatively evaluated through histogram analysis, calculating the standard deviation (SD), the 95% bandwidth (BW95%), and entropy. METHODS: We examined resting 99mTc-MIBI images in 20 healthy subjects and 29 patients with cardiac disease who had none or very-mild reduced myocardial perfusion evaluated as a low summed rest score (0 to 4, the range of the studied healthy subjects). Two nuclear medicine specialists blindly divided them into two groups: non-heterogeneity or heterogeneity group, based solely on their visual assessments of heterogeneity on splash and polar maps generated from single-photon emission computed tomography (SPECT) images. The %uptake was determined by dividing the tracer count of each pixel by the tracer count of the pixel with the highest value in the LV myocardium. SD, BW95%, and entropy from histogram patterns were analyzed from the polar map data array of each %uptake. We investigated whether heterogeneity could be assessed using SD, BW95, and entropy in two groups classified by visual assessments. Additionally, we evaluated the area under the curve (AUC) to identify heterogeneity in the receiver operating characteristic curve analysis. RESULTS: Based solely on visual assessments, 11 (22%) and 38 (78%) cases were classified into the non-heterogeneity and heterogeneity groups, respectively. The non-heterogeneity group consisted of only healthy subjects, and all patients with cardiac disease were classified into the heterogeneity group. The cases in the heterogeneity group had significantly higher values of heterogeneity indices (SD, BW95%, and entropy) in %uptake than those in the non-heterogeneity group (p < 0.05 for all). The AUCs of the heterogeneity indices were sufficiently high (AUCs > 0.90 for all) in distinguishing cases with visually heterogeneous distribution or patients with cardiac disease. CONCLUSIONS: Heterogeneity in MPI can be evaluated using SD, BW95%, and entropy through histogram analysis. These novel indices may help identify patients with subtle myocardial changes, even in images that show preserved perfusion (345/350).

Ratio of pulmonary artery diameter to ascending aortic diameter and its association with right ventricular failure after left ventricular assist device implantation.

BACKGROUND: Several invasive hemodynamic parameters help predict right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation. However, prediction using non-invasive parameters alone has not been established. The ratio of the diameters of the pulmonary artery (PAD) to those of the ascending aorta (AoD) may indicate past hemodynamic load and cardiac dysfunction. We aimed to investigate a predictive model for RVF after LVAD implantation using non-invasive parameters including PAD/AoD ratio. METHODS: We studied 141 patients who underwent primary LVAD implantation and 117 healthy individuals with computed tomography (CT) data. RVF was defined as the need for a subsequent right ventricular assist device or intravenous inotrope administration for more than 30 days after LVAD implantation. The PAD/AoD ratio was measured at the level of the pulmonary artery bifurcation on the CT transaxial slices. RESULTS: RVF was observed in 29 patients. The correlation between PAD and AoD differed among healthy individuals, patients with and without RVF. Patients with RVF had higher total bilirubin and log brain natriuretic peptide (BNP) levels, a lower left ventricular end-diastolic diameter (LVDd) index, and a higher PAD/AoD ratio than those without RVF. Decision tree analysis indicated that the subgroup with a high PAD/AoD ratio (≥1.09) and a small LVDd index (<35.4 mm/m2) showed the highest probability of RVF (100 %), while the subgroup with a low PAD/AoD ratio (<1.09) and low log BNP (<2.79) showed the lowest probability of RVF (1 %). CONCLUSION: Combining non-invasive parameters with the PAD/AoD ratio can predict RVF with high accuracy.

Focal severe decrease in myocardial technetium-99 m sestamibi uptake indicates ventricular irreversibility in patients with dilated cardiomyopathy.

OBJECTIVE: Technetium-99 m sestamibi (99mTc-MIBI) scintigraphy can identify non-viable left ventricular (LV) myocardium. However, the optimal cut-off value and the details of decreased 99mTc-MIBI uptake of the non-viable LV myocardium in patients with dilated cardiomyopathy (DCM) have not been well established. This study aimed to evaluate the decrease in 99mTc-MIBI uptake in each segment and in the whole LV myocardium, and to determine cut-off values for identifying non-viable LV myocardium in DCM patients. METHODS: Overall, 53 DCM patients with reduced LV ejection fraction (LVEF ≤ 40%) who underwent 99mTc-MIBI scintigraphy and any optimization of heart failure treatments were evaluated. LV myocardium was classified as viable or non-viable based on the absolute increase in LVEF of ≥ 10% unit leading to an LVEF of > 40% at follow-up, respectively. The decrease in myocardial 99mTc-MIBI uptake in each of the 17 segments was evaluated using three indices determined by different thresholds or standard references: segmental %uptake, rest score, and defect extent. Changes in the whole LV myocardium were evaluated by the minimum %uptake, and the summed rest score (SRS) and extent of LV defect were obtained using summed data of 17 segments. RESULTS: Segmental evaluation indicated a mild decrease in 99mTc-MIBI uptake in 18 patients with viable LV myocardium, whereas focal severe decrease in uptake was observed in patients with non-viable LV myocardium. In the receiver-operating characteristic curve analysis, the cut-off values of minimum %uptake, SRS, and LV defect extent for predicting non-viable LV were 39% (p < 0.01, area under the curve [AUC]: 0.87), 10 (p < 0.01, AUC: 0.91), and 23% (p < 0.01, AUC: 0.92), respectively. CONCLUSIONS: In DCM patients, myocardial 99mTc-MIBI %uptake of < 40% indicated non-viable myocardium. The focal and severe decrease in uptake in approximately more than a quarter of the LV myocardium may indicate non-viable LV.

Circulating markers of collagen types I, III, and IV in patients with dilated cardiomyopathy: relationships with myocardial collagen expression.

AIMS: Collagen-derived peptides such as collagen I C-terminal telopeptide (CITP) and procollagen III N-terminal propeptide (PIIINP) have been conventionally used as markers of cardiac fibrosis. Collagen IV 7S domain (P4NP 7S) has been recently reported to be correlated with haemodynamics in patients with acute heart failure. We investigated whether these markers reflect cardiac remodelling and myocardial collagen expression. METHODS AND RESULTS: In 80 patients with dilated cardiomyopathy, relationships of CITP, PIIINP, and P4NP 7S to clinical and echocardiographic variables were analysed. CITP and PIIINP were inversely correlated with estimated glomerular filtration rate (r = -0.41, P < 0.001 and r = -0.32, P = 0.004, respectively); P4NP 7S was positively correlated with B-type natriuretic peptide (r = 0.32, P = 0.003) and γ-glutamyltransferase (r = 0.38, P < 0.001). These correlations were significant even after adjustment by potential confounders, whereas all three collagen markers were not independently correlated with ejection fraction nor with left ventricular (LV) diastolic diameter. In 33 patients undergoing endomyocardial biopsy, myocardial collagen I and III mRNA expressions were correlated with LV end-diastolic volume index (r = 0.42, P = 0.02 and r = 0.54, P = 0.002, respectively), whereas myocardial collagen IV mRNA expression was not correlated with LV end-diastolic volume index nor with ejection fraction. Each collagen-derived peptide was not significantly correlated with the myocardial expression of their corresponding collagen mRNA. CONCLUSIONS: Our study shows that CITP, PIIINP, and P4NP 7S do not reflect myocardial collagen mRNA expression but presumably reflect extra-cardiac organ injury in heart failure.

Effect of supplemented sericin on the development, cell number, cryosurvival and number of lipid droplets in cultured bovine embryos.

Sericin was investigated as an alternative to fetal bovine serum (FBS) for bovine embryo culture. In vitro matured oocytes were developed using 0.05%, 0.1% or 0.15% sericin. The developmental rate, cryosurvival rate and blastulation time of these embryos were compared with those of embryos developed using 5% FBS. The number of lipid droplets was compared among the blastocysts developed using 5% FBS, using 0.05% sericin and in vivo. The rate of cleavage and blastocyst formation was similar among all groups. Blastulation occurred significantly earlier in the embryos developed using 5% FBS than in those developed using sericin at any concentration (P < 0.05). At 72 h after thawing, the cryosurvival rate of the blastocysts developed using 5% FBS and 0.05% sericin were significantly higher compared with those developed using 0.1% and 0.15% sericin (P < 0.05). The blastocysts developed using 0.05% sericin and in vivo produced a significantly fewer number of medium and large lipid droplets than those developed using 5% FBS. These results suggest that the blastocysts developed using 0.05% sericin show characteristics similar to those of the blastocysts developed in vivo and that the use of sericin as an alternative to FBS is feasible.