Quantitative tissue characterization of cardiac myxomas by CMR-Mapping techniques validated by histology

Background

Non-invasive imaging modalities are crucial for the detection and diagnosis of cardiac myxomas. Newer cardiac magnetic resonance (CMR) techniques to assess, extra-cellular volume fraction (ECV) and T2 mapping provide quantitative evaluation of cardiac tissue. Our aim was to test their diagnostic value in the assessment of cardiac myxomas.

Methods

10 patients with morphologically suspected cardiac myxomas on echocardiography and confirmed by post-operative histopathology were prospectively included. CMR was performed at 1.5 Tesla in all patients pre-operatively. Standard protocol for cardiac mass assessment included T1 mapping (pre and post contrast to calculate ECV) and T2 mapping. All data are reported as mean ± standard deviation.

Results

Cardiac myxomas demonstrated significantly higher native T1 values than the myocardium with a mean of 1489 ms ± 270 and 1024 ms ± 131 respectively (p = 0.007). However, cardiac myxomas showed a non-significant trend to lower mean post contrast T1 value than the myocardium, 406 ms ± 81 and 444 ms ± 23 respectively (p = 0.24) (see figure). The mean ECV for cardiac myxomas and myocardium was 45% ± 14% and 31% ± 5% respectively (p = 0.013). Mean T2 values for cardiac myxomas were also significantly higher than for the myocardium 154 ms ± 32 and 58 ms ± 4 respectively (p = 0.028).

Conclusions

Compared to myocardium, we observed significantly higher native T1 values and increased ECV reflecting the different tissue composition and a larger extracellular interstitial compartment in cardiac myxomas. In addition, high T2 mapping values may indicate a higher fluid content in cardiac myxomas. CMR-mapping techniques might help to quantitatively assess cardiac myxomas non-invasively.

Figure 1

T1 mapping values (in milliseconds) before (native) and post contrast administration for myocardium and cardiac myxomas.