A magnetization‐driven gradient echo pulse sequence for the study of myocardial perfusion

Abstract

A T 1 -weighted imaging pulse sequence for contrast-based studies of myocardial perfusion is presented and evaluated in phantoms and in vivo. The sequence is similar to spoiled gradient-recalled echo equences except that nonselective preparatory RF pulses drive magnetization to steady state prior to image acquisition. Steady state is thus obtained in both tissue and blood resulting in a stable, homogeneous, and dark pre-contrast baseline. Tip angles and timings are chosen so that pixel intensity approximates a linear relation to 1/T 1 . The dynamic range of signal response to contrast agent concentration is greater than that of an inversion-recovery fast low angle shot sequence. The sequence proposed should be useful for myocardial perfusion studies.

Assessment of hepatic perfusion parameters with dynamic MRI

“…The effect of various flip angles on the relationship between signal intensity and 1/T 1 was tested. A flip angle of 45°was used as a good compromise between the dynamic range and the sensitivity of the sequence (27). As shown in Fig.…”

“…An external reference containing copper sulfate and agarose was included in the field of view. To optimize the dynamic range (1/T 1 ; range associated with a monotonic increase of signal intensity) and the sensitivity (slope of the relationship between image signal intensity and 1/T 1 ) of the perfusion sequence, the use of several flip angles (15°, 45°, 90°) was tested (27). The relationship between the signal intensities on the perfusion sequence and 1/T 1 was fitted by a third-order polynomial function.…”

The Role of Cardiac MRI In Coronary Heart Disease Management

“…So, that, precise and prompt recognition of viable myocardium is considered to be an increasingly important in both prognosis and treatment of CAD. Scintigraphy techniques and stress echocardiography were the main guides of diagnosis until recently (84) . The CMR has an emerging clinical role of assessment of viable myocardium which has two important prognostic considerations (84) .…”

“…Scintigraphy techniques and stress echocardiography were the main guides of diagnosis until recently (84) . The CMR has an emerging clinical role of assessment of viable myocardium which has two important prognostic considerations (84) . First, viable myocardium which is treated medically is a herald of additional nonfatal ischemic events with higher mortality.…”

“…Some trials consider the lack of hyper enhancement as a good marker of the non-viable myocardium (91,92) , others showed a better response to re-vascularization treatment when there is no hypo-enhancement in first pass images. Whether viable or not is an important factor which determines the possibility of response to revascularization therapy and can assist in deciding whether to do the revascularization or to depend on the conservative medical treatment (84) .…”