When Do I Need an MRI Study of My Body? A Discussion Guide for Patients and Caregivers

Richard C. Semelka, MD


September 12, 2005

In This Article

Before You Undergo a Body Imaging Examination: Talking Points for You and Your Doctor

In discussions with your doctor regarding the potential usefulness of a body MRI study, I have the following thoughts and recommendations that you can convey as an informed patient:

  1. MRI should be performed in patients with serious allergies or renal failure because contrast-enhanced MRI is safer than contrast-enhanced CT.

  2. MRI is the most diagnostically accurate and safe method to look at the liver because it does not employ the ionizing radiation associated with CT scanning.

  3. MRI and CT are comparable in their diagnostic accuracy -- with MRI being slightly superior -- for the pancreas, adrenals, and kidneys. At centers with considerable experience with MRI, patients with diseases of these organs should get MRI, and at centers with CT experience, CT is adequate. Practice should change, however, with more centers doing MRI.

  4. Suspected kidney stones should be studied with CT.

  5. Male and female pelvic organs are better studied by MRI than CT, although ultrasound is effective for many noncomplex female pelvic conditions.

  6. MRI and CT have differing strengths at studying bowel disease. At a few centers, MRI should be considered for bowel.

  7. Large- and medium-sized vessels are comparably studied by MRI and CT, so MRI should be employed because of safety. Small vessels are currently best studied with CT.

  8. Most lung diseases are best studied with CT.

  9. Most severe acute trauma should be studied by CT.

  10. Determining the location of tubes and catheters in very sick patients is best studied by CT.

My personal preference is to study most diseases of the abdomen and pelvis with MRI because of a varying combination of diagnostic accuracy and patient safety. A comprehensive overview of MRI of the abdomen and pelvis can provide the reader with more information on imaging diseases in these locations with MRI.[7] It should be emphasized that this review is forward-looking and not an indictment against current practice patterns. CT is unquestionably a quality diagnostic imaging modality, even in circumstances where MRI is superior. It should be stressed that CT is an important modality for assessing patients, but because of potential hazards from radiation, careful attention should be paid to the number of CTs performed on any one patient and whether effective alternative, safer imaging can be performed for any indication. It is critical that we scrutinize how often a patient is getting a CT and whether there is a diagnostically equivalent modality that can be used in its place.


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