Breath hold imaging in MRI is a technique with one ore more stoppage of breathing during the sequence and require therefore a short scan time. Breath hold techniques are used with fast gradient echo sequences in thoracic or abdominal regions with much respiratory movement.
Breath hold cine MRI techniques are used in cardiovascular imaging and provide detailed views of the beating heart in different cardiac axes.
Breath hold imaging requires the full cooperation of the patient, caused by usual MRI scan times from 15 to 20 sec.. In some cases breath holding can be practiced outside the MRI scanner to improve patient cooperation with the examination. Shorter scan times e.g. by parallel imaging techniques, or the administration of oxygen can help the patient to hold the breath during the scan.
See also Abdominal Imaging.

The cardiac anatomy is complex, and cardiac structures have different appearances depending on the imaging plane. The most useful imaging planes are those parallel and perpendicular to the cardiac axes. The short axis (SA), vertical long cardiac axis (VLA - 2 chamber view - 2C) and horizontal long axis (HLA - 4 chamber view - 4C) are the standard views in cardiovascular imaging. The orientation of a heart is described relative to an imaginary line drawn from the base of the heart (valve plane) to the apex.
Obtaining cine images in these double-oblique planes requires the use of multiple localizing MRI sequences and knowledge of the cardiac anatomy. The long axis image plane is determined by the line that runs from the apex of the heart to a midpoint at the base of the heart, often taken to be midway between the mitral valve leaflets. The short axis is planned perpendicular to the long axis view.

Contrast enhanced MRI is a commonly used procedure in magnetic resonance imaging. The need to more accurately characterize different types of lesions and to detect all malignant lesions is the main reason for the use of intravenous contrast agents.
Some methods are available to improve the contrast of different tissues. The focus of dynamic contrast enhanced MRI (DCE-MRI) is on contrast kinetics with demands for spatial resolution dependent on the application. DCE-MR imaging is used for diagnosis of cancer (see also liver imaging, abdominal imaging, breast MRI, dynamic scanning) as well as for diagnosis of cardiac infarction (see perfusion imaging, cardiac MRI). Quantitative DCE-MRI requires special data acquisition techniques and analysis software.
Contrast enhanced magnetic resonance angiography (CE-MRA) allows the visualization of vessels and the temporal resolution provides a separation of arteries and veins. These methods share the need for acquisition methods with high temporal and spatial resolution.
Double contrast administration (combined contrast enhanced (CCE) MRI) uses two contrast agents with complementary mechanisms e.g., superparamagnetic iron oxide to darken the background liver and gadolinium to brighten the vessels. A variety of different categories of contrast agents are currently available for clinical use.
Reasons for the use of contrast agents in MRI scans are:
Common Indications:
Brain MRI : Preoperative/pretreatment evaluation and postoperative evaluation of brain tumor therapy, CNS infections, noninfectious inflammatory disease and meningeal disease.
Spine MRI : Infection/inflammatory disease, primary tumors, drop metastases, initial evaluation of syrinx, postoperative evaluation of the lumbar spine: disk vs. scar.
Breast MRI : Detection of breast cancer in case of dense breasts, implants, malignant lymph nodes, or scarring after treatment for breast cancer, diagnosis of a suspicious breast lesion in order to avoid biopsy.

For Ultrasound Imaging (USI) see Contrast Enhanced Ultrasound at Medical-Ultrasound-Imaging.com. See also Blood Pool Agents, Myocardial Late Enhancement, Cardiovascular Imaging, Contrast Enhanced MR Venography, Contrast Resolution, Dynamic Scanning, Lung Imaging, Hepatobiliary Contrast Agents, Contrast Medium and MRI Guided Biopsy.

(DENSE) Displacement Encoding with Stimulated Echoes is a functional cardiac MRI pulse sequence, used to create maps of myocardial displacement with high resolution.
The DENSE magnitude images produce black blood images to show better myocard-blood contrast and to reduce motion artifacts.

See also Myocardial Late Enhancement, Spin Tagging, Coronary Angiography with D-Tagging, Cardiovascular Imaging, and Black Blood MRA.

(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.