Practical recommendations
M. Neuss, B. Schnackenburg
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Dobutamine stress magnetic
resonance tomography (DSMR)
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The basic principle of DSMR is to combine the
protocols well established in dobutamine stressechocardiography with the superior image quality achieved in MR imaging of the heart. The
imaging procedure follows the guidelines formulated by the Writing Group on Myocardial
Segmentation and Registration for Cardiac
Imaging of the American Heart Association.
Additional material needed for DSMR: infusion pump, either MR compatible inside the
scanner room, or standard equipment placed
outside the scanner room with possibility to
lead infusion lines from control room to patient
inside the magnet (contact manufacturer of
your scanner), monitoring device for blood
pressure and ECG. During examination monitor
ECG continuously for rhythm disturbances, record blood pressure every 3 min. Depending on
the aim of the DSMR two basic protocols are
possible.
n Viability and inducible ischemia
To be used in patients with regional wall motion abnormalities at rest or globally reduced
LV function at rest if chronic ischemia is suspected to be the reason.
n Inducible ischemia
To be used in patients with no regional wall
motion abnormalities at rest and normal global
LV function.
For the planning of the basic anatomy the
reader is referred to the chapter on LV function.
1. Acquire resting images (basic protocol)
2. Calculate target heart rate [(220-age) ´ 0.85]
3. Prepare scan list that contains the scans to be
repeated on each of the incremental dosages
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of dobutamine. The scan list needs to contain: 3 SA, 4ch, 3ch, 2ch
Start dobutamine
(5 lg/kg ´ min, wait for 5 min, acquire 3 SA,
4ch, 3ch, 2ch). This step is omitted for protocol B (inducible ischemia)
10 lg/kg ´ min, wait for 3 min, acquire 3
SA, 4ch, 3ch, 2ch
20 lg/kg ´ min, wait for 3 min, acquire 3
SA, 4ch, 3ch, 2ch
30 lg/kg ´ min, wait for 3 min, acquire 3
SA, 4ch, 3ch, 2ch
40 lg/kg ´ min, wait for 3 min, acquire 3
SA, 4ch, 3ch, 2ch
If target heart rate not reached: apply atropine in steps of 0.5 mg.
Indications for interruption of the study before
target heart rate are:
n Obvious new wall motion abnormality
n Severe angina pectoris
n Severe dyspnea
n Global reduction of LV function
n Drop in systolic blood pressure of ³ 40 mmHg
n Blood pressure in excess of 240/120 mmHg
(either value)
n Ventricular tachycardia/fibrillation
n Atrial fibrillation/flutter with rapid ventricular response.
Consider the application of contrast agent and
delayed enhancement using an inversion-recovery technique for the detection of scar tissue in
case of regional wall motion abnormalities at
rest.
In rare instances a seemingly normal wall
motion at rest turns out to be abnormal at
10 lg dobutamine/kg ´ min. The lack of increase
of thickening and endocardial motion in one
segment allows in retrospect to identify a subtle
resting wall motion abnormality that otherwise
had escaped the attention. Under those circumstances the application of contrast agent after
the termination of the study and scar imaging
using an inversion-recovery technique has merit
to detect small areas of myocardial scar tissue.
After images have been acquired, consider intravenous application of a short acting beta
blocker (esmolol) if symptomatically required.