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 dem
ands 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:
•
Relaxation characteristics of normal
and pathologic tissues are not always different enough to produce obvious differences in
signal intensity.
•
Pathology that is sometimes occult on unenhanced
images becomes obvious in the presence of
contrast.
•
Enhancement significantly increases
MRI sensitivity.
•
In addition to improving delineation between normal
and abnormal tissues, the pattern of
contrast enhancement can improve diagnostic specificity by facilitating characterization of the lesion(s) in question.
•
Contrast can yield physiologic
and functional information in addition to lesion delineation.
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.