Page 18 - Rob Holtackers

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subendocardial. Due to the almost equally bright signal of the adjacent blood pool,
detection of these small areas of ischemic scar is challenging (Figure 1.6). Even when
successfully detecting such areas, identifying the exact scar-blood border remains
difficult. Scar can be interpreted as part of the blood pool and can therefore
significantly reduce, or even completely obscure the apparent scar volume. On the
other hand, scar tissue can be mimicked by the blood pool signal and therefore result
in false positive observations.

Figure 1.6: Conventional short-axis (bright-blood) LGE images of three patients with suspicion of
myocardial infarction (cyan arrows). Due to the almost equally high signal of the blood pool,
poor scar-to-blood contrast results which hampers the detection and assessment of areas of
subendocardial scar.

Dark-blood LGE
Already more than 15 years ago, advances were made to increase scar-to-blood
contrast using various additional magnetization preparation mechanisms. This need
was further strengthened after discovering that even tiny regions of scar tissue of only
2% of the mean left ventricular mass were linked with a sevenfold increase in major
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cardiac events, and that scar transmurality plays a major role in the prediction of the
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likelihood of regional functional recovery after revascularization. Furthermore,
increased scar-to-blood contrast may be beneficial for identifying papillary muscle
scar and assessing thin-walled structures, such as the right ventricle and atria. Over
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the years, various new LGE approaches have emerged that aimed to improve
subendocardial scar conspicuity. 31-44 Although these LGE methods achieved superior
scar-to-blood contrast compared to conventional LGE, the majority required additional
magnetization preparation schemes, including T 2 preparation, magnetization transfer,
and spin locking. Such additional schemes require (1) adjustments to the MR system
software and/or configuration, (2) extensive optimizations for new sequence
parameters, (3) additional training for radiographers, and therefore hamper direct
translation to routine clinical practices.

Aims and outline of this thesis

The main aim of this PhD thesis was to develop a novel blood-suppressed (dark-blood)
LGE method that achieves superior scar-to-blood contrast without requiring any