Radiology
MRI uses strong magnetic fields to align atomic nuclei (usually hydrogen protons) within body tissues, then uses a radio signal to disturb the axis of rotation of these nuclei and observes the radio frequency signal generated as the nuclei return to their baseline states. The radio signals are collected by small antennae, called coils, placed near the area of interest. An advantage of MRI is its ability to produce images in axial, coronal, sagittal and multiple oblique planes with equal ease. MRI scans give the best soft tissue contrast of all the imaging modalities. With advances in scanning speed and spatial resolution, and improvements in computer 3D algorithms and hardware, MRI has become an important tool in musculoskeletal radiology and neuroradiology.
Breast cancer screening
Despite the aids provided from MRIs, there are some disadvantages. For example, although it is 27–36% more sensitive, it has been claimed to be less specific than mammography. As a result, MRI studies may have up to 30% more false positives, which may have undesirable financial and psychological costs on the patient. Also, MRI procedures are expensive and include an intravenous injection of a gadolinium contrast, which has been implicated in a rare reaction called nephrogenic systemic fibrosis (NFS). Although NSF is uncommon, other patients with a history of renal failure/disease would not be able to undergo an MRI scan. Breast MRI is not recommended for screening all breast cancer patients, yet limited to patients with high risk of developing breast cancer that may have high familial risk or mutations in BCRA1/2 genes. Breast MRI is not a perfect tool despite its increased sensitivity for detecting breast cancer masses when compared to mammography. This due to the ability of MRIs to miss some cancers that would have been detected with conventional mammography, as a result, MRI screening for breast cancer is most affective as a combination with other tests and for certain breast cancer patients. In contrast, the use of MRIs are often limiting to patients with any body metal integration such as patients with tattoos, pacemakers, tissue expanders, and so on.