CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 4, July/August 2014
AFRICA
185
Review Article
Current clinical applications of cardiovascular magnetic
resonance imaging
L Scholtz, A Sarkin, Z Lockhat
Abstract
Cardiovascular magnetic resonance (CMR) imaging is unsur-
passed in the evaluation of myocardial anatomy, function
and mass. Myocardial perfusion pre- and post-stress, as well
as late enhancement is increasingly used in the work-up for
ischaemic heart disease, especially in establishing the pres-
ence of myocardial viability. Late enhancement patterns can
contribute substantially to the diagnosis of myocarditis and
various cardiomyopathies as well as infiltrative diseases and
tumours. With their high incidence of cardiovascular disease,
patients on the African continent could potentially benefit
enormously from the proper utilisation of this exciting,
continually evolving and versatile technique, via thorough
didactic and clinical training as well as interdisciplinary
co-operation.
Keywords:
cardiovascular, cardiomyopathy, imaging, Africa,
non-invasive
Submitted 9/10/13, accepted 25/4/14
Cardiovasc J Afr
2014;
25
: 185–190
DOI: 10.5830/CVJA-2014-021
Owing to initial obstacles, mainly related to cardiac motion and
ECG triggering, cardiovascular magnetic resonance (CMR)
established itself within the cardiac imaging armamentarium
long after its first diagnostic application in other disciplines.
Faster and more effective sequences were subsequently developed
to ‘freeze’ heart motion. Vector ECG and other solutions have
also minimised the initial problems during ECG triggering that
were due to the magneto-hydrodynamic effect of pulsatile blood
in the aorta.
The quality of CMR imaging has consequently improved
dramatically since the first MR images of the human heart were
described more than 20 years ago, and it is still advancing apace.
CMR now represents one of the most versatile, non-invasive
imaging modalities available, offering high spatial resolution
and image contrast along with tissue characterisation and
haemodynamic assessment, without applying ionising radiation,
and with complete multiplanar coverage of the heart.
Good communication between the referring physician and the
CMR specialist is paramount to streamline the type and order of
sequences required for each particular scenario. Although new
sequences are constantly being developed, the basic principles of
CMR remain unaltered, as follows.
Basic principles of CMR
Scout imaging
Each examination starts with a series of scout views performed
on each patient to establish the short- and long-axis views of the
heart. These act as localisers in planning the rest of the study.
The pulse sequences used for scouting are based on steady-state
free-precession (SSFP). Typically, 27 scout images are acquired
to define the thoracic contents, including nine parallel images in
each of the axial, coronal and sagittal planes.
Anatomical and morphological imaging
To assess anatomy and morphology, static images are required.
Black-blood imaging is usually preferred because it allows clear
distinguishing of the inner portion of the vessel or myocardium
from blood. Half-Fourier single-shot fast-spin echo (HASTE)
is a special variant of the fast-spin echo sequences, and ideal
for delineation of anatomy. Anatomical and morphological
information is particularly important in the diagnosis of
congenital abnormalities and cardiac tumours.
Functional imaging
Dynamic ciné CMR white blood imaging is used for global
and regional left ventricular (LV) and right ventricular (RV)
wall motion assessment as well as ventricular volume, ejection
fraction and mass measurements. It is now widely regarded as
the gold standard.
1
The SSFP sequence is fast and ideal for white
blood ciné imaging owing to its high signal-to-noise ratio and
excellent ability to visualise the endocardial border. Functional
analysis is especially important in the work-up of ischaemic
heart disease as well as the non-ischaemic cardiomyopathies.
Department of Radiology, Steve Biko Hospital, Pretoria,
South Africa
Leonie Scholtz, MB ChB, MMed (Rad) (Diag), (Pret), leonie@
scholtzrad.co.za
Z Lockhat, FFRAD (D) (SA)
Department of Cardiology, Steve Biko Hospital, Pretoria,
South Africa
Andrew Sarkin, MB BCH, FCP (Wits)
