Background-Pulmonary hypertension is a disease characterized by an elevation in pulmonary arterial pressure that is diagnosed invasively via right heart catheterization. Such pathological altered pressures in the pulmonary vascular system should lead to changes in blood flow patterns in the main pulmonary artery. Methods and Results-Forty-eight subjects (22 with manifest pulmonary hypertension, 13 with latent pulmonary hypertension, and 13 normal control subjects) underwent time-resolved 3D magnetic resonance phase-contrast imaging of the main pulmonary artery. Velocity fields that resulted from measurements were calculated, visualized, and analyzed with dedicated software. Main findings were as follows: (1) Manifest pulmonary hypertension coincides with the appearance of a vortex of blood flow in the main pulmonary artery (sensitivity and specificity of 1.00, 95% confidence intervals of 0.84 to 1.00 and 0.87 to 1.00, respectively), and (2) the relative period of existence of the vortex correlates significantly with mean pulmonary arterial pressure at rest (correlation coefficient of 0.94). To test the diagnostic performance of the vortex criterion, we furthermore investigated 55 patients in a blinded prospective study (22 with manifest pulmonary hypertension, 32 with latent pulmonary hypertension, and 1 healthy subject), which resulted in a sensitivity of 1.00 and specificity of 0.91 (95% confidence intervals of 0.84 to 1.00 and 0.76 to 0.98, respectively).Comparison of catheter-derived mean pulmonary artery pressure measurements and calculated mean pulmonary artery pressure values resulted in a standard deviation of differences of 3.6 mm Hg. Conclusions-Vortices

Duration of vortical blood flow in the main pulmonary artery that is determined by using phase-contrast MR imaging allows accurate estimation of elevated mPAP and diagnosis of PH. Clinical trial registration no. NCT00575692.

In normal myocardium, diastolic and systolic myocardial T1 values differ significantly but correlate strongly. Blood normalization eliminates sex differences in myocardial T1 values and reduces their variability.

PurposeThree-dimensional (3D) magnetic resonance phase contrast imaging (PC-MRI) allows non-invasive diagnosis of pulmonary hypertension (PH) and estimation of elevated mean pulmonary arterial pressure (mPAP) based on vortical motion of blood in the main pulmonary artery. The purpose of the present study was to compare the presence and duration of PH-associated vortices derived from different flow visualization techniques with special respect to their performance for non-invasive assessment of elevated mPAP and diagnosis of PH.MethodsFifty patients with suspected PH (23 patients with and 27 without PH) were investigated by right heart catheterization and time-resolved PC-MRI of the main pulmonary artery. PC-MRI data were visualized with dedicated prototype software, providing 3D vector, multi-planar reformatted (MPR) 2D vector, streamline, and particle trace representation of flow patterns. Persistence of PH-associated vortical blood flow (tvortex) was evaluated with all visualization techniques. Dependencies of tvortex on visualization techniques were analyzed by means of correlation and receiver operating characteristic (ROC) curve analysis.Resultstvortex values from 3D vector visualization correlated strongly with those from other visualization techniques (r = 0.98, 0.98 and 0.97 for MPR, streamline and particle trace visualization, respectively). Areas under ROC curves for diagnosis of PH based on tvortex did not differ significantly and were 0.998 for 3D vector, MPR vector and particle trace visualization and 0.999 for streamline visualization. Correlations between elevated mPAP and tvortex in patients with PH were r = 0.96, 0.93, 0.95 and 0.92 for 3D vector, MPR vector, streamline and particle trace visualization, respectively. Corresponding standard deviations from the linear regression lines ranged between 3 and 4 mmHg.Conclusion3D vector, MPR vector, streamline as well as particle trace visualization of time-resolved 3D PC-MRI data of the main pulmonary artery can be employed for accurate vortex-based diagnosis of PH and estimation of elevated mPAP.

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Increased myocardial lipid content (MYCL) recently has been linked to the development of cardiomyopathy in diabetes. In contrast to steatosis in skeletal muscle and liver, previous investigations could not confirm a link between MYCL and insulin resistance. Thus, we hypothesized that cardiac steatosis might develop against the background of the metabolic environment typical for prediabetes and early type 2 diabetes: combined hyperglycemia and hyperinsulinemia. Therefore, we aimed to prove the principle that acute hyperglycemia (during a 6-h clamp) affects MYCL and function (assessed by 1H magnetic resonance spectroscopy and imaging) in healthy subjects (female subjects: n = 8, male subjects: n = 10; aged 28 ± 5 years; BMI 22.4 ± 2.6 kg/m2). Combined hyperglycemia (202.0 ± 10.6 mg/dL) and hyperinsulinemia (110.6 ± 59.0 μU/mL) were, despite insulin-mediated suppression of free fatty acids, associated with a 34.4% increase in MYCL (baseline: 0.20 ± 0.17%, clamp: 0.26 ± 0.22% of water signal; P = 0.0009), which was positively correlated with the area under the curve of insulin (R = 0.59, P = 0.009) and C-peptide (R = 0.81, P < 0.0001) during the clamp. Furthermore, an increase in ejection fraction (P < 0.0001) and a decrease in end-systolic volume (P = 0.0002) were observed, which also were correlated with hyperinsulinemia. Based on our findings, we conclude that combined hyperglycemia and hyperinsulinemia induce short-term myocardial lipid accumulation and alterations in myocardial function in normal subjects, indicating that these alterations might be directly responsible for cardiac steatosis in metabolic diseases.

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Pulmonary hypertension (PH) is a life-threatening, multifactorial pathophysiological haemodynamic condition, diagnosed when the mean pulmonary arterial pressure equals or exceeds 25 mmHg at rest during right heart catheterization. Cardiac MRI, in general, and MR phase-contrast (PC) imaging, in particular, have emerged as potential techniques for the standardized assessment of cardiovascular function, morphology and haemodynamics in PH. Allowing the quantification and characterization of macroscopic cardiovascular blood flow, MR PC imaging offers non-invasive evaluation of haemodynamic alterations associated with PH. Techniques used to study the PH include both the routine two-dimensional (2D) approach measuring predominant velocities through an acquisition plane and the rapidly evolving four-dimensional (4D) PC imaging, which enables the assessment of the complete time-resolved, three-directional blood-flow velocity field in a volume. Numerous parameters such as pulmonary arterial mean velocity, vessel distensibility, flow acceleration time and volume and tricuspid regurgitation peak velocity, as well as the duration and onset of vortical blood flow in the main pulmonary artery, have been explored to either diagnose PH or find non-invasive correlates to right heart catheter parameters. Furthermore, PC imaging-based analysis of pulmonary arterial pulse-wave velocities, wall shear stress and kinetic energy losses grants novel insights into cardiopulmonary remodelling in PH. This review aimed to outline the current applications of 2D and 4D PC imaging in PH and show why this technique has the potential to contribute significantly to early diagnosis and characterization of PH.