A machine learning-derived risk score to predict left ventricular diastolic dysfunction from clinical cardiovascular magnetic resonance imaging.

Introduction: The evaluation of left ventricular diastolic dysfunction (LVDD) by clinical cardiac magnetic resonance (CMR) remains a challenge. We aimed to train and evaluate a machine-learning (ML) algorithm for the assessment of LVDD by clinical CMR variables and to investigate its prognostic value for predicting hospitalized heart failure and all-cause mortality. Methods: LVDD was characterized by echocardiography following the ASE guidelines. Eight demographic and nineteen common clinical CMR variables including delayed enhancement were used to train Random Forest models with a Bayesian optimizer. The model was evaluated using bootstrap and five-fold cross-validation. Area under the ROC curve (AUC) was utilized to evaluate the model performance. An ML risk score was used to stratify the risk of heart failure hospitalization and all-cause mortality. Results: A total of 606 consecutive patients underwent CMR and echocardiography within 7 days for cardiovascular disease evaluation. LVDD was present in 303 subjects by echocardiography. The performance of the ML algorithm was good using the CMR variables alone with an AUC of 0.868 (95% CI: 0.811-0.917), which was improved by combining with demographic data yielding an AUC 0.895 (95% CI: 0.845-0.939). The algorithm performed well in an independent validation cohort with AUC 0.810 (0.731-0.874). Subjects with higher ML scores (>0.4121) were associated with increased adjusted hazard ratio for a composite outcome than subjects with lower ML scores (1.72, 95% confidence interval 1.09-2.71). Discussion: An ML algorithm using variables derived from clinical CMR is effective in identifying patients with LVDD and providing prognostication for adverse clinical outcomes.

Does embryo biopsy, independent of vitrification, impact perinatal outcomes? An analysis of perinatal outcomes following preimplantation genetic testing biopsy in fresh and frozen embryo transfer cycles.

Objective: To compare neonatal outcomes in pregnancies resulting from embryos that have undergone preimplantation genetic testing (PGT) biopsy compared with no biopsy in both fresh and frozen embryo transfers (ETs) and determine whether findings are mediated by multiple births. Design: Retrospective cohort study. Setting: Society of Assisted Reproductive Technologies-Clinical Outcomes Reporting System data, 2014-2015. Patients: Autologous in vitro fertilization treatment cycles using fresh or frozen blastocyst ET, with or without PGT biopsy. Interventions: Not applicable. Main Outcome Measures: Large for gestational age (LGA), small for gestational age, and preterm delivery. Secondary outcomes included high birthweight, low birthweight, and clinical pregnancy measures. Outcomes were evaluated using log-binomial regression models with repeated measures. Models were used to estimate the controlled direct effects of biopsy on birth outcomes that were not mediated by multiple gestations. Results: In fresh ET, biopsy was associated with an increase in LGA (relative risk [RR] 1.45, confidence interval [CI] 1.04-2.02) that persisted in the model mediated for multiple gestation (RR 1.36, 95% CI 1.01-1.83) but was not present in an analysis restricted to elective single ET (RR 0.99, 95% CI 0.91-1.09). In frozen ET, there were no differences in any of the primary outcomes after accounting for multiple gestations. Conclusions: In a large multicenter database, there were no differences in neonatal outcomes after PGT biopsy in frozen ET cycles, and an increase in LGA was noted in fresh transfers that persisted even after accounting for multiple gestations but was not present in analysis restricted to elective single ET.

Trends in magnetic resonance and computed tomography angiography utilization among Medicare beneficiaries between 2013 and 2020.

PURPOSE: To evaluate relative and absolute utilization trends and practice patterns in the United States for MRA and CTA. METHODS: Using Medicare Part B physician payment databases (2013-2020), MRA and CTA interpreting physicians and exams were identified using the unique MRA and CTA Healthcare Common Procedure Coding System codes. The number of exams, physicians, demographics, use of contrast, and payments were summarized annually and analyzed to evaluate trends before and during the first year of the COVID-19 pandemic. RESULTS: From 2013 to 2019, the annual number of MRA exams performed decreased by 17.9 %, while the number of CTA exams increased by 90.3 %. The number of physicians interpreting MRA decreased in both hospital (-17.2 %) and outpatient (-7.5 %) environments. The number of physicians interpreting CTA increased in both hospital (+29.4 %) and outpatient (+54.3 %) environments. During the first year of the COVID-19 pandemic, MRA utilization decreased across all imaging environments by 25.0 % whereas CTA only decreased by 5.5 %. Intracranial MRA studies were most often performed without contrast, while contrast use for neck MRA was performed at similar rates as non-contrast exams. CONCLUSION: The overall utilization of MRA and the number of interpreting physicians are decreasing. On the other hand, CTA use and its number of interpreting physicians are increasing. During the first year of the COVID-19 pandemic, use of both MRA and CTA decreased, but the utilization of MRA decreased at five times the rate of CTA.

Trends in Cardiovascular MRI and CT in the U.S. Medicare Population from 2012 to 2017.

PURPOSE: To assess the characteristics and trends of cardiovascular MRI and CT practitioners and practice in the United States. MATERIALS AND METHODS: A retrospective cross-sectional analysis of 2012-2017 Medicare Part B physician payments from the Provider Utilization and Payment Data Physician and Other Supplier Public Use Files (POSPUF) was performed. Characteristics of cardiovascular MRI and CT, including the number of providers and examinations, provider sex and location, and physician reimbursement were analyzed. Variable means, standard deviations, and changes per year were reported and compared. RESULTS: In 2017, 582 physicians provided cardiovascular MRI services in 45 states, a 16.6% increase from 2016 and an 84.8% increase from 2012. A total of 1645 physicians provided cardiovascular CT services in 49 states, a 14.2% increase from 2016 and a 77.3% increase from 2012. Of the providers, 18.0% and 13.3% of cardiovascular MRI and CT providers were women, respectively, similar to providers' respective medical specialties. Only 1.0% of radiologists and 0.2% of cardiologists provided cardiovascular MRI services. A total of 3.2% of radiologists and 0.5% of cardiologists provided cardiovascular CT services. Both cardiovascular MRI use (+75.5%) and cardiovascular CT use (+97.4%) increased markedly over the 6-year study period. CONCLUSION: Although the availability of cardiovascular MRI and CT is increasing, both are used less frequently in comparison with other cardiovascular imaging modalities.See also the commentary by Bierhals in this issue.Supplemental material is available for this article.© RSNA, 2021.

Superovulation with human chorionic gonadotropin (hCG) trigger and gonadotropin releasing hormone agonist (GnRHa) trigger differentially alter essential angiogenic factors in the endometrium in a mouse ART model†.

Gonadotropin-releasing hormone agonists (GnRHa) are used as an alternative to human chorionic gonadotropin (hCG) to trigger ovulation and decrease the risk of ovarian hyperstimulation syndrome. GnRHa is less potent at inducing ovarian vascular endothelial growth factor (VEGF), but may also affect endometrial angiogenesis and early placental development. In this study, we explore the effect of superovulation on endometrial angiogenesis during critical periods of gestation in a mouse model. We assigned female mice to three groups: natural mating or mating following injection with equine chorionic gonadotropin and trigger with GnRHa or hCG trigger. Females were killed prior to implantation (E3.5), post-implantation (E7.5), and at midgestation (E10.5), and maternal serum, uterus, and ovaries were collected. During peri-implantation, endometrial Vegfr1 and Vegfr2 mRNA were significantly increased in the GnRHa trigger group (P < 0.02) relative to the hCG group. Vegfr1 is highly expressed in the endometrial lining and secretory glands immediately prior to implantation. At E7.5, the ectoplacental cone expression of Vegfa and its receptor, Vegfr2, was significantly higher in the hCG trigger group compared to the GnRHa group (P < 0.05). Soluble VEGFR1 and free VEGFA were much higher in the serum of mice exposed to the hCG trigger compared to GnRHa group. At midgestation, there was significantly more local Vegfa expression in the placenta of mice triggered with hCG. GnRHa and hCG triggers differentially disrupt the endometrial expression of key angiogenic factors during critical periods of mouse gestation. These results may have significant implications for placental development and neonatal outcomes following human in vitro fertilization.

Effects of supplemental oxygen on cardiovascular magnetic resonance water proton relaxation time constant measurements (T1, T2 and T2*).

OBJECTIVE: To study, the effects of supplemental oxygen on the measurement of native cardiovascular water proton relaxation time constants using commercially available protocols. METHODS: T1, T2 and T2* relaxation time constant mapping were performed in twelve volunteers at 1.5 T breathing room air and supplemental oxygen supplied by nasal cannula and a non-rebreather mask. Regions-of-interest were drawn for quantitative measurements in the bloodpool of each ventricle and atria as well as septal myocardium. The effects of supplemental oxygen were investigated statistically using a mixed model analysis of variance. Intra- and inter-observer reproducibility were assessed using the Intraclass Correlation Coefficient and Coefficient of Variation. RESULTS: Blood T1 relaxation time constants in the left ventricle (T1 change = -241.0 ms) and left atrium (T1 change = -247.0 ms) decreased significantly in every subject after oxygen inhalation with a non-rebreather mask (p < 0.001). No significant changes of T1 in the right side of the heart were detected after oxygen inhalation with the non-rebreather mask (p = 0.345). Oxygen inhalation with nasal cannula did not significantly change blood T1 in the study (p = 0.497). No significant changes in myocardial T1 (p = 0.390), T2 (p = 0.960) or T2* (p = 0.438) were observed with supplemental oxygen supplied by nasal cannula or the non-rebreather mask. Results were similar in mid-short-axis and horizontal long-axis acquisitions. CONCLUSION: Supplemental oxygen does not affect myocardial relaxation time constant measurements with current protocols. On the other hand, blood T1 measurements with the inhalation of supplemental oxygen supplied by a non-rebreather mask change significantly and could affect myocardial tissue characterization if used for the calculation of extracellular volume. Additionally, current relaxation time constant mapping protocols do not reproducibly detect myocardial T1 changes with supplemental oxygen inhalation.

Water-fat separation and parameter mapping in cardiac MRI via deep learning with a convolutional neural network.

BACKGROUND: Water-fat separation is a postprocessing technique most commonly applied to multiple-gradient-echo magnetic resonance (MR) images to identify fat, provide images with fat suppression, and to measure fat tissue concentration. Recently, Numerous advancements have been reported. In contrast to early methods, the process of water-fat separation has become complicated due to multiparametric analytic models, optimization methods, and the absence of a unified framework for diverse source data. PURPOSE: To determine the feasibility and performance of MRI water-fat separation and parametric mapping via deep learning (DL) with a range of inputs. STUDY TYPE: Retrospective data usage. POPULATION/SUBJECTS: Ninety cardiac MR examinations from normal control, acute, subacute, and chronic myocardial infarction subjects were obtained, providing 1200 multiple gradient-echo acquisitions. FIELD STRENGTH/SEQUENCE: 1.5 T/2D multiple gradient-echo pulse sequence ASSESSMENT: Ground-truth training and validation water-fat separation were obtained using a graph cut method with R2 *, off-resonance correction, and a multipeak fat spectrum. U-Net DL training with single and multiecho, complex, and magnitude inputs were compared using quantitative and three-observer subjective analysis. STATISTICAL TESTS: DL methods' image structural similarity, and quantitative proton density fat fraction (PDFF), R2 *, and off-resonance quantitative values were statistically compared with the GraphCut reference standard using Student's t-test and Pearson's correlation. RESULTS: Myocardial fat deposition in chronic myocardial infarction and intramyocardial hemorrhage in acute myocardial infarction were well visualized in the DL results. Predicted values for R2 *, off-resonance, water, and fat signal intensities were well correlated with a conventional model-based water fat separation (R2 ≥ 0.97, P < 0.001) with appropriate inputs. DL parameter maps had a 14% higher signal-to-noise ratio (P < 0.001) when compared with a conventional method. DATA CONCLUSION: DL water-fat separation is feasible with a wide range of inputs, while R2 * and off-resonance mapping requires multiple echoes and complex images. With appropriate inputs, DL provides quantitative and subjective results comparable to conventional model-based methods. LEVEL OF EVIDENCE: 1 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:655-665.

How much does the uterus matter? Perinatal outcomes are improved when donor oocyte embryos are transferred to gestational carriers compared to intended parent recipients.

OBJECTIVE: To assess the reproductive and neonatal outcomes of cycles in which donor oocyte embryos were transferred to gestational carriers compared to intended parent recipients. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): Intended parent recipients and gestational carriers receiving donor oocyte embryos in 2014 in the United States. INTERVENTIONS(S): None. MAIN OUTCOMES MEASURE(S): Clinical pregnancy, live birth, miscarriage, plurality, prematurity, and birth weight from pregnancies conceived with donor oocyte embryos transferred to either a gestational carrier or an intended parent recipient. RESULT(S): The mean ages of intended parent recipients (N=18,317) and gestational carriers (N=1,927) were 41.6 and 31.6 years, respectively. Compared to an intended parent recipient, patients using a gestational carrier had significantly higher odds of a clinical pregnancy (65.2% vs. 56.3%, adjusted odds ratio (aOR) 1.33, 95% confidence interval (CI) 1.17-1.51) and live birth (57.1% vs. 46.4%, aOR 1.37, 95% CI 1.21-1.55) using fresh or frozen donor-oocyte embryos. Of the singletons born (n=716 using a gestational carrier and n=5,632 in intended parent recipients), the incidence of prematurity was significantly lower in gestational carriers compared to intended parent recipients (17.5% vs. 25.4%, aOR 0.78, 95% CI 0.61-0.99). The incidence of low birthweight among singletons was significantly reduced in gestational carrier cycles (6.4% vs. 12.1%, aOR 0.62, 95% CI 0.44-0.89). CONCLUSION: Intended parent recipients had decreased pregnancy rates and poorer neonatal outcomes compared to a gestational carrier. This suggests that a history of infertility adversely affects the uterine microenvironment, independent of the oocyte.

Forty years of IVF.

This monograph, written by the pioneers of IVF and reproductive medicine, celebrates the history, achievements, and medical advancements made over the last 40 years in this rapidly growing field.

How compliant are in vitro fertilization member clinics in following embryo transfer guidelines? An analysis of 59,689 fresh first in vitro fertilization autologous cycles from 2011 to 2012.

OBJECTIVE: To determine whether IVF clinics are compliant with American Society for Reproductive Medicine (ASRM) and Society for Assisted Reproductive Technology (SART) (ASRM/SART) guidelines and assess the multiple pregnancy outcomes according to the number of embryos transferred. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): Data from 59,689 fresh first autologous IVF cycles from the 2011-2012 SART registry. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Percentage of compliant cycles, multiple pregnancy rate (PR). RESULT(S): Between 2011 and 2012, a total of 59,689 fresh first autologous cycles were analyzed. Among cleavage-stage ET cycles, the noncompliance rate ranged from 10%-27.4% depending on the age group. The multiple PR was significantly increased in noncompliant cycles involving patients <35 years (38.1% vs. 28.7%) and 35-37 years (35.4% vs. 24.5%) compared with compliant cycles. Among blastocyst-stage ET cycles, the highest rate of noncompliance was seen in patients <35 years old (71%), which resulted in a statistically higher multiple PR (48.3% vs. 2.8%) compared with compliant cycles. Far fewer cycles were noncompliant in patients 35-40 years of age. In a subanalysis of compliant cycles, transferring two blastocyst embryos in patients 35-37 years and 38-40 years resulted in a higher live birth rate compared with the transfer of one embryo (50.4% vs. 40.9% and 42.1% vs. 30.0%, respectively) but the multiple PR was also significantly higher (40.5% vs. 1.7% and 34.0% vs. 2.0%, respectively). CONCLUSION(S): Most first fresh autologous IVF cycles performed from 2011-2012 were compliant with ASRM/SART guidelines, except those that involved a blastocyst ET in patients <35 years. Despite compliance, cycles that involved the transfer of >1 embryo resulted in a high multiple PR, whereas noncompliant cycles resulted in an even more remarkable multiple PR for both cleavage and blastocyst-stage embryos. Clinics need to be more compliant with ET limits and ASRM/SART need to consider revising their guidelines to limit the number of blastocyst transfer to one in patients ≤40 years of age undergoing their first IVF cycle. Furthermore, decreasing the number of cleavage-stage embryos transferred in patients ≤40 years of age should also be considered.

Do donor oocyte cycles comply with ASRM/SART embryo transfer guidelines? An analysis of 13,393 donor cycles from the SART registry.

OBJECTIVE: To analyze donor oocyte cycles in the Society for Assisted Reproductive Technology (SART) registry to determine: 1) how many cycles complied with the 2009 American Society for Reproductive Medicine/SART embryo transfer guidelines; and 2) cycle outcomes according to the number of embryos transferred. For donor oocyte IVF with donor age <35 years, the consideration of single-embryo transfer was strongly recommended. DESIGN: Retrospective cohort study of United States national registry information. SETTING: Not applicable. PATIENT(S): A total of 13,393 donor-recipient cycles from 2011 to 2012. INTERVENTION(S): Embryos transferred in donor IVF cycles. MAIN OUTCOME MEASURE(S): Percentage of compliant cycles, multiple pregnancy rate. RESULT(S): There were 3,157 donor cleavage-stage transfers and 10,236 donor blastocyst transfers. In the cleavage-stage cycles, 88% met compliance criteria. The multiple pregnancy rate (MPR) was significantly higher in the noncompliant cycles. In a subanalysis of compliant cleavage-stage cycles, 91% transferred two embryos and only 9% single embryos. In those patients transferring two embryos, the MPR was significantly higher (33% vs. 1%). In blastocyst transfers, only 28% of the cycles met compliance criteria. The MPR was significantly higher in the noncompliant blastocyst cohort at 53% (compared with 2% in compliant cycles). CONCLUSION(S): The majority of donor cleavage-stage transfers are compliant with current guidelines, but the transfer of two embryos results in a significantly higher MPR compared with single-embryo transfer. The majority of donor blastocyst cycles are noncompliant, which appears to be driving an unacceptably high MPR in these cycles.

Effects of transcytolemmal water exchange on the assessment of myocardial extracellular volume with cardiovascular MRI.

Quantitative analysis of the myocardial interstitial space is gaining increased interest as a biomarker in the MRI and clinical cardiovascular communities. To investigate the effect of water exchange on the calculation of myocardial extracellular volume (ECV), we employed two tissue models: the standard ECV two-point model (SM) and the shutter speed model (SSM). Twenty individuals (18 men and two women; age 61.9 ± 10.3 years) underwent MRI at 1.5 T with pre-contrast and post-contrast dynamic T1 quantification. Means, standard deviations and ranges for SM and SSM model parameters were calculated. Infarct and viable myocardial model parameters as well as apparent ECV values calculated with the SM and SSM were statistically compared. Viable ECV(SM) remained temporally constant (27.3-28.0%: P = 0.5) and infarcted myocardial ECV(SM) changed significantly (49.3-58.8%; P < 0.001), reaching a steady-state value after 15 min. The intracellular lifetime of water was three times greater in infarcted myocardium when compared with viable myocardium (τi: 66.6 ± 115 versus 208.7 ± 72.7 ms) and accompanied a twofold increase in ECV (ECV(SSM) : 30.3 ± 11.1 versus 71.0 ± 13.1%; P < 0.001). There was a consistent significant difference in ECV values of infarcted myocardium at different timepoints between the SM and SSM, but not viable myocardium, presumably due to slower water exchange. In summary, we found a significant change in apparent ECV and water exchange in infarcted myocardium when compared with viable myocardium. This was visualized by changes in dynamic contrast enhanced curve shapes and quantified using the SSM as not only an increase in apparent ECV but also a decrease in water exchange.

Pregnancy outcomes decline with increasing recipient body mass index: an analysis of 22,317 fresh donor/recipient cycles from the 2008-2010 Society for Assisted Reproductive Technology Clinic Outcome Reporting System registry.

OBJECTIVE: To examine the effect of recipient body mass index (BMI) on IVF outcomes in fresh donor oocyte cycles. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): A total of 22,317 donor oocyte cycles from the 2008-2010 Society for Assisted Reproductive Technology Clinic Outcome Reporting System registry were stratified into cohorts based on World Health Organization BMI guidelines. Cycles reporting normal recipient BMI (18.5-24.9) were used as the reference group. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Implantation rate, clinical pregnancy rate (PR), pregnancy loss rate, live birth rate. RESULT(S): Success rates and adjusted odds ratios with 95% confidence intervals for all pregnancy outcomes were most favorable in cohorts of recipients with low and normal BMI, but progressively worsened as BMI increased. CONCLUSION(S): Success rates in recipient cycles are highest in those with low and normal BMI. Furthermore, there is a progressive and statistically significant worsening of outcomes in groups with higher BMI with respect to clinical pregnancy and live birth rate.

Pregnancy outcomes decline with increasing body mass index: analysis of 239,127 fresh autologous in vitro fertilization cycles from the 2008-2010 Society for Assisted Reproductive Technology registry.

OBJECTIVE: To examine the effect of body mass index (BMI) on IVF outcomes in fresh autologous cycles. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): A total of 239,127 fresh IVF cycles from the 2008-2010 Society for Assisted Reproductive Technology registry were stratified into cohorts based on World Health Organization BMI guidelines. Cycles reporting normal BMI (18.5-24.9 kg/m(2)) were used as the reference group (REF). Subanalyses were performed on cycles reporting purely polycystic ovary syndrome (PCOS)-related infertility and those with purely male-factor infertility (34,137 and 89,354 cycles, respectively). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Implantation rate, clinical pregnancy rate, pregnancy loss rate, and live birth rate. RESULT(S): Success rates and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for all pregnancy outcomes were most favorable in cohorts with low and normal BMIs and progressively worsened as BMI increased. Obesity also had a negative impact on IVF outcomes in cycles performed for PCOS and male-factor infertility, although it did not always reach statistical significance. CONCLUSION(S): Success rates in fresh autologous cycles, including those done for specifically PCOS or male-factor infertility, are highest in those with low and normal BMIs. Furthermore, there is a progressive and statistically significant worsening of outcomes in groups with higher BMIs. More research is needed to determine the causes and extent of the influence of BMI on IVF success rates in other patient populations.

Imaging of reperfused intramyocardial hemorrhage with cardiovascular magnetic resonance susceptibility weighted imaging (SWI).

PURPOSE: To report initial experience with TE-averaged susceptibility weighted imaging (SWI) in normal subjects and acute myocardial infarction (AMI) patients for the detection of intramyocardial hemorrhage (IMH). MATERIALS AND METHODS: 15 healthy control and 11 AMI subjects were studied at 1.5T before contrast agent administration with a dark blood double inversion recovery multiple spoiled gradient-echo sequence. Magnitude, susceptibility weighted and TE-averaged images were reconstructed from raw data. Contrast and signal-difference-to-noise were measured and compared between methods for IMH detection. RESULTS: There were six patients with microvascular obstruction (MVO) and four patients with IMH detected by TE-averaged SWI imaging. All patients with IMH on SWI scans had MVO on late gadolinium-enhanced (LGE) imaging. There was a three-fold increase in IMH contrast with SWI compared to magnitude images. IMH contrast decreased and signal-to-noise increased with increased TE averages. CONCLUSIONS: TE-averaged SWI imaging is a promising method for myocardial tissue characterization in the setting of AMI for the detection of IMH. Along with gray-scale colormap inversion, it combines not only magnitude and phase information, but also images across TEs to provide a single image sensitive to IMH with characteristics similar to LGE imaging.

Magnetic resonance imaging dynamic contrast enhancement (DCE) characteristics of healed myocardial infarction differ from viable myocardium.

PURPOSE: To determine whether healed myocardial infarction alters dynamic contrast-enhancement (DCE) curve shapes as well as late gadolinium-enhancement (LGE). MATERIALS AND METHODS: Twenty patients with chronic myocardial infarction underwent MR imaging at 1.5 T with blood and myocardial T1 measurements before and after contrast administration for forty minutes. Viable and infarcted myocardial partition coefficients were calculated using multipoint slope methods for ten different DCE sampling intervals and windows. Partition coefficients and coefficients of determination were compared with paired statistical tests to assess the linearity of DCE curve shapes over the 40 min time period. RESULTS: Calculated partition coefficients did not vary significantly between methods (p=0.325) for viable myocardium but did differ for infarcted myocardium (p<0.001), indicating a difference in infarcted DCE. There was a significant difference between viable and infarcted myocardial partition coefficients estimates for all methods with the exception of methods that included measurements during the first 10 min after contrast agent administration. CONCLUSION: Myocardial partition coefficients calculated from a slope calculation vary in healed myocardial infarction based on the selection of samples due to non-linear DCE curve shapes. Partition coefficient calculations are insensitive to data sampling effects in viable myocardium due to linear DCE curve shapes.