Abstract:
The aim of this study was to define the correlation between visual
qualitative method and semi-quantitative method for the study of the
extension of myocardial edema by CMR in patients with Takotsubo syndrome
(TTS).
We analyzed 22 consecutive patients with a diagnosis of typical apical
TTS. A total of 374 myocardial segments were analyzed. A high
correlation between visual method and the semi-quantitative method of
the T2 SI ratio (Pearson’s r = 0.82, p <0.001) was found.
In the clinical setting the visual method provides a valid and reliable
quantification of myocardial edema extension in patients with TTS.
Background . Myocardial edema is characteristic of the acute
phase of Takotsubo syndrome (TTS) and can be easily detected by cardiac
magnetic resonance (CMR) [1]. In
conventional edema sequences, the presence and extension of edema can be
assessed qualitatively by visual analysis of the signal intensity (SI)
or semi-quantitatively by analyzing the T2 SI ratio between myocardial
and skeletal muscle [2]. In the
clinical practice the qualitative method is widely accepted in the
scenario of acute myocardial infarction, early stages of myocarditis and
sarcoidosis [3]. However, whether a
quantitative method should be preferred in patients with TTS remains
unknown. The aim of this study was to define the correlation between
visual qualitative method and semi-quantitative method for the study of
the extension of myocardial edema in patients with TTS.
Methods . We included all consecutive patients admitted between
January 2013 and March 2016 with a diagnosis of typical apical TSS
(according to the criteria of the Mayo Clinic), following a prospective
comprehensive and systematic protocol including a CMR study in the acute
phase [4]. CMR protocol included a
specific T2-weighted sequence (double inversion recovery spin echo with
fat suppression) on short- and long-axis (2-,3-, and 4-chamber) views in
a 1.5 Tesla MRI Scanner (Signa HDXT; General Electric Healthcare®,
Milwaukee, WI, USA), using a 12-channel phased array surface coil and
ECG synchronization. All patients provided informed consent to
participate in the study. The extent of the edema was assessed by
accredited experts and expressed as number of myocardial segments
involved using the 17-segments cardiac segmentation model. The
quantification of the edema was performed both by visual SI and by the
semi-quantitative T2 SI ratio. For the T2 SI ratio, a ROI was drawn in
every myocardial segment and then compared with a ROI localized in the
skeletal muscle closest to the heart and to the center of the reception
field of the coil. A value > 1.9 in the T2 SI ratio was
considered positive for the presence of edema in the myocardial segment.
Patients negative for edema by T2 SI ratio were excluded. All the
analyses were blind and independent.
Results . 22 patients were included in the analysis. A total of
374 myocardial segments were analyzed. The median of myocardial segments
with edema was 5 (1-11) using the qualitative method and 6 (0-12) using
the semi-quantitative method. The results showed a positive correlation
between the extent of myocardial edema measured by the visual method and
the semi-quantitative method of the T2 SI ratio (Pearson’s r = 0.82, p
<0.001) (Figure).
Discussion . Postprocessing guidelines support visual analysis
for the assessment of myocardial edema in myocardial infarction, however
they do not state whether this is also appropriate for TTS
[3]. T2 SI ratio and T2 mapping are
more accurate than visual assessment
[5], but their use is limited in
clinical practice because they are time consuming and the analyses are
not widely accessible. Considering that visual edema assessment by CMR
is the most common used method in the differential diagnosis of
myocardial infarction with nonobstructive coronary arteries (MINOCA) and
that TTS may represent up 20% of MINOCA patients
[6], we considered mandatory to test
the accuracy of visual assessment in TTS with a more rigorous methods as
T2 SI ratio.
Conclusions . The visual qualitative method presents a high
correlation with T2 SI ratio in the study of myocardial edema by CMR in
patients with TTS. Therefore, in the clinical setting the visual method
provides a valid and reliable quantification of myocardial edema
extension in patients with TTS.