Left ventricular shape index and eccentricity index with ECG-gated Nitrogen-13 ammonia PET/CT in patients with myocardial infarction, ischemia, and normal perfusion.

BACKGROUND: LV geometry with shape index (SI) and eccentricity index (EI) measured by myocardial perfusion positron emission tomography/computed tomography (PET/CT) may allow the evaluation of left ventricular (LV) adverse remodeling. This first study aims to explore the relationship of SI and EI values acquired by Nitrogen-13 ammonia PET/CT in patients with normal perfusion, ischemia, and myocardial infarction. And evaluate the correlations between the variables of LV geometry, and with the variables of LV function. METHODS AND RESULTS: One hundred and forty patients who underwent an electrocardiogram (ECG)-gated PET/CT were selected and classified into 4 groups according to ischemia or infarction burden (normal perfusion, mild ischemia, moderate-severe ischemia, and infarction). The variables were automatically retrieved using dedicated software (QPS/QGS; Cedars-Sinai, Los Angeles, CA, USA). On multicomparison analysis (one-way ANOVA and Dunnett's Test), subjects in the infarction group had significant higher values of SI end-diastolic rest (P < 0.001), and stress (P = 0.003), SI end-systolic rest (P = 0.002) and stress (P < 0.001) as well as statistically significant lower values of EI rest (P < 0.001) and stress (P < 0.001) when compared with all other groups. Regarding Pearson correlation, in the infarcted group all the variables of SI and EI were significantly correlated (P < 0.001) with strong correlation coefficients (>0.60). SI end-systolic correlated significantly with the variables of LV function independently of the group of patients (P < 0.05). CONCLUSIONS: Shape and eccentricity indices differ in patients with myocardial infarction as compared to patients with ischemia or normal perfusion. This encourage further research in their potential for detecting LV adverse remodeling.

Automated Breast Density Assessment in MRI Using Deep Learning and Radiomics: Strategies for Reducing Inter-Observer Variability.

BACKGROUND: Accurate breast density evaluation allows for more precise risk estimation but suffers from high inter-observer variability. PURPOSE: To evaluate the feasibility of reducing inter-observer variability of breast density assessment through artificial intelligence (AI) assisted interpretation. STUDY TYPE: Retrospective. POPULATION: Six hundred and twenty-one patients without breast prosthesis or reconstructions were randomly divided into training (N = 377), validation (N = 98), and independent test (N = 146) datasets. FIELD STRENGTH/SEQUENCE: 1.5 T and 3.0 T; T1-weighted spectral attenuated inversion recovery. ASSESSMENT: Five radiologists independently assessed each scan in the independent test set to establish the inter-observer variability baseline and to reach a reference standard. Deep learning and three radiomics models were developed for three classification tasks: (i) four Breast Imaging-Reporting and Data System (BI-RADS) breast composition categories (A-D), (ii) dense (categories C, D) vs. non-dense (categories A, B), and (iii) extremely dense (category D) vs. moderately dense (categories A-C). The models were tested against the reference standard on the independent test set. AI-assisted interpretation was performed by majority voting between the models and each radiologist's assessment. STATISTICAL TESTS: Inter-observer variability was assessed using linear-weighted kappa (κ) statistics. Kappa statistics, accuracy, and area under the receiver operating characteristic curve (AUC) were used to assess models against reference standard. RESULTS: In the independent test set, five readers showed an overall substantial agreement on tasks (i) and (ii), but moderate agreement for task (iii). The best-performing model showed substantial agreement with reference standard for tasks (i) and (ii), but moderate agreement for task (iii). With the assistance of the AI models, almost perfect inter-observer variability was obtained for tasks (i) (mean κ = 0.86), (ii) (mean κ = 0.94), and (iii) (mean κ = 0.94). DATA CONCLUSION: Deep learning and radiomics models have the potential to help reduce inter-observer variability of breast density assessment. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 1.

Diagnostic accuracy of myocardial perfusion imaging in patients evaluated for kidney transplantation: A systematic review and meta-analysis.

BACKGROUND: Cardiovascular disease is the most common cause of death after kidney transplantation. Coronary artery disease (CAD) assessment is therefore mandatory in patients evaluated for transplantation. We aimed to assess the diagnostic accuracy for CAD of single-photon emission computed tomography (SPECT) compared to the standards invasive coronary angiography (ICA) and coronary computed tomography angiography (CCTA) in patients evaluated for kidney transplantation. METHODS: We performed a systematic literature search in PubMed, EMBASE, Web of Science, OvidSP (Medline), The Cochrane Library and Google Scholar. Studies investigating the diagnostic accuracy of myocardial perfusion imaging (MPI) SPECT in patients evaluated for kidney transplantation were retrieved. After a risk of bias assessment using QUADAS-2, a meta-analysis was conducted. RESULTS: Out of 1459 records, 13 MPI SPECT studies were included in the meta-analysis with a total of 1245 MPI SPECT scans. There were no studies available with CCTA as reference. Pooled sensitivity of MPI SPECT for CAD was 0.66 (95% CI 0.53 to 0.77), pooled specificity was 0.75 (95% CI 0.63 to 0.84) and the area under the curve (AUC) was 0.76. Positive likelihood ratio was 2.50 (95% CI 1.78 to 3.51) and negative likelihood ratio was 0.41 (95% CI 0.28 to 0.61). Pooled positive predictive value was 64.9% and pooled negative predictive value was 74.1%. Significant heterogeneity existed across the included studies. CONCLUSIONS: MPI SPECT had a moderate diagnostic accuracy in patients evaluated for kidney transplantation, with a high rate of false-negative findings. The use of an anatomical gold standard against a functional imaging test in the included studies is however suboptimal.

Association of Isolated Coronary Microvascular Dysfunction With Mortality and Major Adverse Cardiac Events: A Systematic Review and Meta-Analysis of Aggregate Data.

Background The impact of coronary microvascular dysfunction (CMD), as diagnosed by reduced coronary flow reserve, on the outcomes of patients with symptoms of myocardial ischemia and nonobstructive coronary artery disease is poorly understood. We performed a systematic review and meta-analysis of observational studies to determine the association of CMD with outcomes. Methods and Results We searched online databases for studies where coronary flow reserve was measured invasively or noninvasively, clinical events were recorded after determination of coronary flow reserve, and the frequency of those events was reported for patients with and without CMD. The primary outcome was all-cause mortality. The secondary outcome was major adverse cardiac events, including cardiac or cardiovascular death, nonfatal myocardial infarction, cardiac hospitalization, or coronary revascularization. Estimates of effect were calculated from crude event rates with a random-effects model. There were 122 deaths in the 4661 patients without CMD (2.6%) and 183 deaths in the 1970 patients with CMD (9.3%). The odds ratio for mortality in patients with CMD compared with those without CMD was 3.93 (95% CI, 2.91-5.30; P<0.001). There were 167 major adverse cardiac events in the 3742 patients without CMD (4.5%) and 245 events in the 1447 patients with CMD (16.9%). The odds ratio for major adverse cardiac events in patients with CMD compared with those without CMD was 5.16 (95% CI, 2.81-9.47; P<0.001). Conclusions CMD is associated with a nearly 4-fold increase in mortality and a 5-fold increase in major adverse cardiac events. Future studies are needed to identify effective strategies to diagnose and treat CMD.

Software reproducibility of myocardial blood flow and flow reserve quantification in ischemic heart disease: A 13N-ammonia PET study.

BACKGROUND: We explored agreement in the quantification of myocardial perfusion by cross-comparison of implemented software packages (SPs) in three distinguishable patient profile populations. METHODS: We studied 91 scans of patients divided into 3 subgroups based on their semi-quantitative perfusion findings: patients with normal perfusion, with reversible perfusion defects, and with fixed perfusion defects. Rest myocardial blood flow (MBF), stress MBF, and myocardial flow reserve (MFR) were obtained with QPET, SyngoMBF, and Carimas. Agreement between SPs was considered adequate when a pairwise standardized difference was found to be < 0.20 and its corresponding intraclass correlation coefficient was ≥ 0.75. RESULTS: In patients with normal perfusion, two out of three comparisons of global stress MBF quantifications were outside the limits of agreement. In ischemic patients, all comparisons of global stress MBF and MFR were outside the limits of established agreement. In patients with fixed perfusion defects, all SP comparisons of perfusion quantifications were within the limit of agreement. Regionally, agreement of these perfusion estimates was mostly found for the left anterior descending artery vascular territory. CONCLUSION: Reversible defects demonstrated the worst agreement in global stress MBF and MFR and discrepancies showed to be regional dependent. Reproducibility between SPs should not be assumed.

Ventricular synchrony is not significantly determined by absolute myocardial perfusion in patients with chronic heart failure: A 13N-ammonia PET study.

BACKGROUND: It is thought that heart failure (HF) patients may benefit from the evaluation of mechanical (dys)synchrony, and an independent inverse relationship between myocardial perfusion and ventricular synchrony has been suggested. We explore the relationship between quantitative myocardial perfusion and synchrony parameters when accounting for the presence and extent of fixed perfusion defects in patients with chronic HF. METHODS: We studied 98 patients with chronic HF who underwent rest and stress Nitrogen-13 ammonia PET. Multivariate analyses of covariance were performed to determine relevant predictors of synchrony (measured as bandwidth, standard deviation, and entropy). RESULTS: In our population, there were 43 (44%) women and 55 men with a mean age of 71 ± 9.6 years. The SRS was the strongest independent predictor of mechanical synchrony variables (p < .01), among other considered predictors including: age, sex, body mass index, smoking, diabetes mellitus, dyslipidemia, hypertension, rest myocardial blood flow (MBF), and myocardial perfusion reserve (MPR). Results were similar when considering stress MBF instead of MPR. CONCLUSIONS: The existence and extent of fixed perfusion defects, but not the quantitative PET myocardial perfusion parameters (sMBF and MPR), constitute a significant independent predictor of ventricular mechanical synchrony in patients with chronic HF.

Bone Mineral Density in Transgender Individuals After Gonadectomy and Long-Term Gender-Affirming Hormonal Treatment.

INTRODUCTION: Establishing the influence of long-term, gender-affirming hormonal treatment (HT) on bone mineral density (BMD) in transgender individuals is important to improve the therapeutic guidelines for these individuals. AIM: To examine the effect of long-term HT and gonadectomy on BMD in transgender individuals. METHODS: 68 transwomen and 43 transmen treated with HT who had undergone gonadectomy participated in this study. Dual-energy x-ray absorptiometry (DXA) scans were performed to measure BMD at the lumbar spine and total hip. Laboratory values related to sex hormones were collected within 3 months of performing the DXA scan and analyzed. MAIN OUTCOME MEASURE: BMD and levels of sex hormones in transwomen and transmen. RESULTS: In transwomen, the mean BMD values at the lumbar spine and total hip at the first DXA scan were, respectively, 0.99 ± 0.15 g/cm2 (n = 68) and 0.94 ± 0.28 g/cm2 (n = 65). In transmen, the mean BMD values at the lumbar spine and total hip at the first DXA scan were, respectively, 1.08 ± 0.16 g/cm2 (n = 43) and 1.01 ± 0.18 g/cm2 (n = 43). A significant decrease in total hip BMD was found in both transwomen and transmen after 15 years of HT compared with 10 years of HT (P = .02). CONCLUSION: In both transwomen and transmen, a decrease was observed in total hip bone mineral density after 15 years of HT compared to the first 10 years of HT. Dobrolinska M, van der Tuuk K, Vink P, et al. Bone Mineral Density in Transgender Individuals After Gonadectomy and Long-Term Gender-Affirming Hormonal Treatment. J Sex Med 2019; 16:1469-1477.

Long-term prognostic value of quantitative myocardial perfusion in patients with chest pain and normal coronary arteries.

BACKGROUND: Patients with chest pain and no obstructive coronary artery disease have shown a high incidence of major adverse cardiovascular events (MACE). We evaluated the role of absolute myocardial perfusion quantification in predicting all-cause mortality and MACE during long-term follow-up in this group of patients. METHODS: We studied 79 patients who underwent Nitrogen-13 ammonia PET for quantification of global myocardial blood flow (MBF) and myocardial flow reserve (MFR) due to suspected impaired myocardial perfusion. Patients with coronary artery disease (i.e., > 30% stenosis in one or more coronary arteries) were excluded. We assessed all-cause mortality and MACE. MACE was defined as the composite incidence of death, myocardial infarction (MI), or hospitalization due to heart failure. RESULTS: Median follow-up was 8 (IQR: 3-14) years. Univariate Cox regression showed that only MFR (P = 0.01) was a predictor of all-cause mortality. Univariate Cox regression analysis showed that both MFR and Stress MBF were predictors of the composite endpoint of MACE (P < 0.001 and P = 0.01, respectively). CONCLUSION: Quantitative assessment of myocardial perfusion may predict all-cause mortality and MACE in patients with chest pain and normal coronary arteries in the long-term follow-up.

Myocardial bridging of the left anterior descending coronary artery is associated with reduced myocardial perfusion reserve: a 13N-ammonia PET study.

Myocardial Bridging (MB) refers to the band of myocardium that abnormally overlies a segment of a coronary artery. This paper quantitatively evaluates the influence of MB of the left anterior descending artery (LAD) on myocardial perfusion of the entire left ventricle. We studied 131 consecutive patients who underwent hybrid rest/stress 13N-ammonia positron emission tomography (PET) and coronary computed tomography angiography (CCTA) due to suspected myocardial ischemia. Patients with previous myocardial infarction and/or significant coronary artery disease (≥ 50% stenosis) were excluded. Myocardial perfusion measurements were compared between patients with and without LAD-MB. Additionally, we evaluated the relationship between anatomical characteristics (length and depth) of LAD-MB and myocardial perfusion measurements. 17 (13%) patients presented a single LAD-MB. Global myocardial perfusion reserve (MPR) was lower in patients with LAD-MB than in patients without LAD-MB (1.9 ± 0.5 vs. 2.3 ± 0.6, p < 0.01). Global stress myocardial blood flow (MBF) was similar in patients with and without LAD-MB (2.2 ± 0.4 vs. 2.3 ± 0.7 ml/g/min, p = 0.40). Global rest MBF was higher in patients with LAD-MB than in patients without LAD-MB (1.2 ± 0.3 vs. 1.0 ± 0.2 ml/g/min, p < 0.01). Global rest MBF, stress MBF, and MPR quantifications were similar in patients with superficial and deep LAD-MB (all p = NS). We did not find any correlation between length and global rest MBF, stress MBF nor MPR (r = - 0.14, p = 0.59; r = 0.44, p = 0.07; and r = 0.45, p = 0.07 respectively). Quantitative myocardial perfusion suggests that LAD-MB may be related to impaired perfusion reserve, an indicator of microvascular dysfunction. Anatomical characteristics of LAD-MB were not related to changes in myocardial perfusion.