Females have higher myocardial perfusion, blood volume and extracellular volume compared to males – an adenosine stress cardiovascular magnetic resonance study

Figure 1. Timeline over CMR scan. Scouts and cines were acquired first, followed by native T1 and T2 mapping a rest. Following 3 minutes of adenosine infusion, native T1 and native T2 maps were acquired, followed by first pass perfusion imaging using gadobutrol (0.05 mmol/kg). After the adenosine infusion was terminated a 10-minute pause followed to reach contrast equilibrium. First pass perfusion images were acquired using gadobutrol (0.05 mmol/kg) at rest and an additional dose of gadobutrol (0.1 mmol/kg) was administered. Post-contrast T1 maps were acquired at rest, and at stress following 3 minutes of adenosine infusion. Reproduced from15 under the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/).

Figure 2. Examples of myocardial perfusion, myocardial blood volume and extracellular volume maps at rest and stress. The top panels show images acquired during adenosine stress and the bottom panel shows rest images. The left column shows a healthy female and the right a healthy male. Myocardial perfusion and myocardial blood volume (MBV) maps were acquired in systole, and extracellular volume (ECV) maps were acquired in late diastole. Note, the ECV maps may appear to be acquired in different slice positions, however this is due to the increase in heart rate during adenosine stress, which shortens diastole thus making the acquisition closer to systole, despite that the slices positions are the same in rest and stress. It is evident that the differences in myocardial perfusion, MBV and ECV are not visually apparent, however this further highlights the importance of proper quantification for correct diagnosis, which also underscores the important of correct normal reference values.

Figure 3. Sex differences in myocardial perfusion, extracellular volume and myocardial blood volume at rest and stress. Females had higher perfusion at both rest and adenosine stress compared to males. Females had higher extracellular volume at both rest and adenosine stress compared to males. Females had higher myocardial blood volume at adenosine stress compared to males, however not at rest. Error bars show one standard deviation. p-values denote paired or unpaired t-test as appropriate.

Figure 4. Linear correlation between myocardial blood volume and extracellular volume. The equation describing the linear correlation between extracellular volume (ECV) and myocardial blood volume (MBV) was ECV = 1.1 × MBV + 17.

Figure 5. Stress-rest increase of myocardial blood volume and extracellular volume. There was no difference in stress-rest increase of myocardial blood volume and stress-rest increase of extracellular volume in all healthy volunteers, n = 37. Error bars show one standard deviation. p-value denote paired t-test.