The assessment of left ventricular wall motion with cine magnetic resonance imaging in the cardiac long axes is useful; however, image quality is limited by reduced signal intensity due to saturation of blood flowing predominantly in plane. Twenty subjects were studied to evaluate the effects of gadopentetate dimeglumine on contrast between blood and myocardium. Contrast improved significantly on contrast agent-enhanced images in the long axes, at both end-systole (vertical axis, +62%, P < .0001; horizontal axis, +67%, P < .0001) and end-diastole (vertical axis, +50%, P < .0001; horizontal axis, +26%, P < .004). The increase in the short axis was less and significant only at end-systole (+25%, P < .0001). Subjective scoring of the cines also showed a significant and clinically useful improvement in the long axes (P < .0001 for both) on contrast-enhanced images. Improved contrast was most evident for 10 minutes after injection, but persisted for up to 20 minutes at end-systole in the long axes. Gadopentetate dimeglumine is useful for cine imaging of left ventricular wall motion when saturation effects prevent adequate clinical assessment.

Contrast Media↗

PubMedDate not supplied

Assessment of regional left ventricular long-axis motion with MR velocity mapping in healthy subjects.

The pattern of left ventricular long-axis motion during early diastole was assessed with magnetic resonance (MR) velocity mapping in 31 healthy volunteers. Regional long-axis velocity varied with time and position around the ventricle. During systole, the base descended toward the apex. The greatest magnitude of long-axis velocity occurred during early diastole. The lateral wall had the highest velocity (140 mm/sec +/- 40 [mean +/- standard deviation]); the anterior and inferior walls had lower velocities (96 mm/sec +/- 27 and 92 mm/sec +/- 34, respectively). The inferoseptal area consistently had the lowest velocities (87 mm/sec +/- 40). Absolute values of peak early-diastolic velocity declined with age (r = -.64, P < .001). Peak early-diastolic velocity was not dependent on heart rate (r = .014, P = .94). Regional variations in left ventricular wall motion were seen. MR velocity mapping is a useful technique for assessing regional left ventricular long-axis heart function.

Adult↗

PubMedDate not supplied

Blood flow imaging by cine magnetic resonance.

A technique for measuring blood flow by whole body nuclear magnetic resonance is described. This method uses imaging gradient profiles that combine even echo rephasing with a field echo sequence to overcome the problem of signal loss from flowing blood. The flow velocity component in any desired direction may be measured by appropriate gradient profile modifications, producing velocity dependent phase shifts that can be displayed by phase mapping. The sequence allows for fast repetition so that flow information may be acquired rapidly from many points in the cardiac cycle and has been used in this mode to observe and measure blood flow in the heart chambers and great vessels. Flow measurements in the femoral artery were also carried out using the same technique; these were compared with similar measurements obtained by Doppler ultrasound. The technique can readily be applied using standard imaging equipment and should prove useful in the clinical assessment of many diseases of the cardiovascular system.

Blood Flow Velocity↗

PubMedDate not supplied

In vivo validation of MR velocity imaging.

Calculations of left ventricular stroke volume obtained by summing the areas of multiple contiguous transverse magnetic resonance (MR) slices in systole and diastole using a spin echo sequence have been compared in 10 healthy volunteers with the stroke output derived from velocity maps in the ascending aorta using a field even-echo rephasing sequence. The results gave a correlation coefficient of 0.97 (p less than 0.001) and a standard error of estimate of 3.2 ml. Velocity maps have also been obtained in the pulmonary artery, the descending aorta, and the superior vena cava. The accuracy of this technique and the theoretical limitations of MR measurements have implications for the earlier detection of atheroma in the coronary and other arteries.

Aorta↗

PubMedDate not supplied

Detection of coronary artery disease using MR imaging with dipyridamole infusion.

Exercise testing in the magnetic resonance (MR) scanner is difficult because of space restriction and movement artefact, which limit its use in the investigation of patients with suspected coronary artery disease. Pharmacological stress, however, can be used as a substitute for exercise. Therefore, a patient with angina underwent MR ventricular wall motion studies before and after intravenous dipyridamole. Reversible abnormal regional contraction of the myocardium was demonstrated and correlated with a reversible perfusion defect on subsequent thallium myocardial perfusion imaging and a blocked artery at coronary angiography. A clinically useful investigative procedure may be developed.

Aged↗

PubMedDate not supplied

MR imaging of age-related dimensional changes of thoracic aorta.

Changes in the dimensions of the thoracic aorta with age were studied in 70 healthy volunteers between the ages of 10 and 83 years. Spin echo images were acquired at end-diastole in three oblique planes through the ascending aorta, aortic arch, and descending aorta. A double oblique image through the whole of the thoracic aorta was also acquired. Measurements of aortic cross-sectional area and length were corrected for body surface area, and normal magnetic resonance standards were established. The direct correlation that aortic dimensions have with age is likely to be due to loss of elasticity. The ratio between areas of the ascending aorta and the aortic arch is directly related to age whereas the ratio between the aortic arch and the descending aorta is inversely related to age.

Adolescent↗