Dotarem® is a paramagnetic ionic MRI contrast agent. Extracellular contrast agents like Dotarem®, can be bolus injected because of the relatively low rate of side effects. This contrast medium is useable to enhance signal intensity in magnetic resonance imaging for intracranial and spinal lesions with an abnormal blood brain barrier or abnormal vascularity, and in whole body imaging.

WARNING: NEPHROGENIC SYSTEMIC FIBROSIS Gadolinium-based contrast agents increase the risk for nephrogenic systemic fibrosis (NSF) in patients with acute or chronic severe renal insufficiency (glomerular filtration rate less than 30 mL/min/1.73m²), or acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period.

This sequence type is a TSE counterpart to double echo sequences. To keep the echo train as short as possible, only echoes for PD and T2 weighted images, where the phase encoding gradient has a small amplitude, are measured separately. The echoes that determine resolution are used in both raw data matrices. This reduces the number of echoes required. Also the SAR drops and more slices can be acquired in the same repetition time.

(DFSE) Simultaneously acquired T2 and density weighted TE in FSE echo images.

(DIR or DIRT1) Double inversion recovery T1 measurement is a T1 weighted black blood MRA sequence in which the signal from blood is suppressed. The inversion time to suppress blood is described as the duration between the initial inversion pulse and time point that the longitudinal magnetization of blood reaches the zero point. The readout starts at the blood suppression inversion time (BSP TI) and blood in the imaging slice gives no signal. This inversion time is around 650 ms with a 60 beat per minute heart rate at 1.5 T.
The TI can be decreased by using a wider receive bandwidth, shorter echo train length and/or narrow trigger window. Wide bandwidth also decreases the blurring caused by long echo trains at the expense of signal to noise ratio. In case of in plane or slow flow the suppression of the signal from blood may be incomplete. With increased TE or change of the image plane the blood suppression can be improved.
Double inversion recovery is a breath hold technique with one image per acquisition used in cardiovascular imaging. The patient is instructed to hold the breath in expiration (if not possible also inspiration can be taken), so that the end diastolic volume in the cardiac chambers would be the same during entire scanning. DIR provides fine details of the boundary between the lumen and the wall of the cardiac chambers and main vascular and heart structures, pericardium, and mediastinal tissues.

(DMSSFP) See Steady State Free Precession.