Improved detection of acute myocardial infarction by magnetic resonance imaging using Gadolinium-DTPA

Abstract

To assess the value of the paramagnetic contrast agent Gadolinium (Gd)-DTPA in Magnetic Resonance Imaging (MRI) of acute myocardial infarction (AMI), we studied 20 patients with a first AMI by ECG-gated MRI before and after intravenous administration of 0.15 mmol/kg Gd-DTPA. The MRI studies were performed after a mean of 98 hours (range 15-241) after the acute onset of AMI. Spin-echo measurements (TE 30 msec) were made using a Philips Gyroscan (0.5 Tesla). After performing the baseline MRI scans, the MRI procedure was repeated every 10 minutes for up to 40 minutes following injection of Gd-DTPA. In 18 (90%) patients contrast enhancement in the infarcted myocardial areas was observed after Gd-DTPA. In these patients intensity versus region curves, derived from 9 to 11 adjacent myocardial regions of interest, showed increased signal intensities in the infarcted areas after administration of Gd-DTPA. The precontrast signal intensity ratio between infarcted and normal myocardium was 1.14 +/- 0.15 (mean +/- SD); the postcontrast ratios at 10 minutes were 1.41 +/- 0.21 (P less than 0.05), at 20 minutes 1.61 +/- 0.19 (P less than 0.01), at 30 minutes 1.43 +/- 0.20 (P less than 0.05), and at 40 minutes 1.33 +/- 0.20 (P = NS). It is concluded that MRI using the contrast agent Gd-DTPA significantly improves the visualization and detection of infarcted myocardial areas in patients with AMI and that optimal contrast enhancement is obtained 20 minutes after administration of Gd-DTPA.

Synchronized inversion recovery‐spin echo sequences for precise in vivo T1 measurement of human myocardium: A pilot study on 22 healthy subjects

“…We have done so using the simplified solutions to the Bloch equations in [31 and [4]. The T, contribution is omitted.…”

“…This pregenerated set of ratio values was calculated from the quotient of Eq. [3] and [4]. A similar approach was adopted for the calculation of T , from the two SE sequences, except that the ratio was based upon Eq.…”

“…[I] and [2] in conjunction with the respective generated signal intensities from [3] and [4], a measure of the Tl error can be obtained with the aid of "look-up" tables relating Tl to the calculated ratio for the different sequences.…”

“…A similar approach was adopted for the calculation of T , from the two SE sequences, except that the ratio was based upon Eq. [4]. The T2 calculation was performed using the four echoes from the SE sequences, and with the aid of a standard twoparameter linear least squares fit (based upon Eq.…”

“…Of the few quantitative MRI studies on in vivo myocardium (2)(3)(4), the majority have employed a series of standard SE sequences, in order to estimate Tl and T2. In the low field study of Wisenberg et al (2), the authors employed a combination of three spin echo (SE) sequences with differing repetition times (TR): the TR values being set to RRl2, RR and 2RR, where RR is the delay between two consecutive R-waves in the cardiac cycle.…”