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Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room.

Jekic M, Foster EL, Ballinger MR, Raman SV, Simonetti OP - J Cardiovasc Magn Reson (2008)

Bottom Line: We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table.We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress.This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dorothy M, Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH43210, USA. Mihaela.jekic@osumc.edu

ABSTRACT
Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR. It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

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Experimental setup for the treadmill CMR test inside the MRI room. The ferromagnetic components, including the treadmill motor and the ECG system, are located in the corner of the MRI room where the magnetic field is less than 5 Gauss.
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Figure 3: Experimental setup for the treadmill CMR test inside the MRI room. The ferromagnetic components, including the treadmill motor and the ECG system, are located in the corner of the MRI room where the magnetic field is less than 5 Gauss.

Mentions: Continuous 12-Lead ECG monitoring of the patient is required during the exercise test [16]. To our knowledge there is currently no commercially available, MRI-compatible 12-lead stress ECG system. Therefore, we positioned a standard 12-lead ECG system at the entrance to the MRI room (Figure 3), close enough to monitor the subject both on the treadmill and on the MRI patient table when the patient is outside of the magnet bore. While inside the bore, the ECG is non-diagnostic due to magneto-hydrodynamic artifacts caused by blood flow within the magnetic field [31]. However, heart rate and rhythm can be monitored continuously with a wireless 3-electrode unit provided by the MRI manufacturer (Siemens Medical Solutions, Malvern, PA). This setup allowed us to quickly disconnect the patient from the 12-lead ECG system after exercise, while continuing to monitor heart rate with the 3-electrode unit. MRI-compatible manual and automatic non-invasive blood pressure equipment (Medrad, Inc., Pittsburgh, PA) was used to monitor blood pressure before, during, and after the stress test.


Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room.

Jekic M, Foster EL, Ballinger MR, Raman SV, Simonetti OP - J Cardiovasc Magn Reson (2008)

Experimental setup for the treadmill CMR test inside the MRI room. The ferromagnetic components, including the treadmill motor and the ECG system, are located in the corner of the MRI room where the magnetic field is less than 5 Gauss.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2244608&req=5

Figure 3: Experimental setup for the treadmill CMR test inside the MRI room. The ferromagnetic components, including the treadmill motor and the ECG system, are located in the corner of the MRI room where the magnetic field is less than 5 Gauss.
Mentions: Continuous 12-Lead ECG monitoring of the patient is required during the exercise test [16]. To our knowledge there is currently no commercially available, MRI-compatible 12-lead stress ECG system. Therefore, we positioned a standard 12-lead ECG system at the entrance to the MRI room (Figure 3), close enough to monitor the subject both on the treadmill and on the MRI patient table when the patient is outside of the magnet bore. While inside the bore, the ECG is non-diagnostic due to magneto-hydrodynamic artifacts caused by blood flow within the magnetic field [31]. However, heart rate and rhythm can be monitored continuously with a wireless 3-electrode unit provided by the MRI manufacturer (Siemens Medical Solutions, Malvern, PA). This setup allowed us to quickly disconnect the patient from the 12-lead ECG system after exercise, while continuing to monitor heart rate with the 3-electrode unit. MRI-compatible manual and automatic non-invasive blood pressure equipment (Medrad, Inc., Pittsburgh, PA) was used to monitor blood pressure before, during, and after the stress test.

Bottom Line: We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table.We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress.This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dorothy M, Davis Heart and Lung Research Institute, 473 W 12th Ave, Columbus, OH43210, USA. Mihaela.jekic@osumc.edu

ABSTRACT
Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR. It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

Show MeSH
Related in: MedlinePlus