Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
An MRI (or magnetic resonance imaging) scan is a
radiology technique that uses magnetism, radio waves, and a computer
to produce images of body structures. The MRI scanner is a tube
surrounded by a giant circular magnet. The patient is placed on
a moveable bed that is inserted into the magnet. The magnet creates
a strong magnetic field that aligns the protons of hydrogen atoms,
which are then exposed to a beam of radio waves. This spins the
various protons of the body, and they produce a faint signal
that is detected by the receiver portion of the MRI scanner.
The receiver information is processed by a computer, and an image
The image and resolution produced by MRI is quite detailed and can
detect tiny changes of structures within the body. For some procedures, contrast agents, such as gadolinium, are used to increase the accuracy of the images.
When are MRI scans used?
An MRI scan can be used as an extremely accurate
method of disease detection throughout the body. In the head,
trauma to the brain can be seen as bleeding or swelling. Other
abnormalities often found include brain aneurysms,
of the brain, as well as tumors or inflammation of the spine.
Neurosurgeons use an MRI scan not only in defining brain anatomy
but in evaluating the integrity of the spinal cord after trauma.
It is also used when considering problems associated with the
vertebrae or intervertebral discs of the spine. An MRI scan can
evaluate the structure of the heart and
aorta, where it can detect
aneurysms or tears.
It provides valuable information on glands
and organs within the abdomen, and accurate information about
the structure of the joints, soft tissues, and bones of the body.
Often, surgery can be deferred or more accurately directed after
knowing the results of an MRI scan.
Medical Author: Benjamin Wedro, MD, FAAEM
Medical Editor: Melissa Conrad Stöppler, MD
June 2008 - In the last few months, Tiger Woods has won nine out of the 12
golf tournaments he has entered. So who cares? Whenever he tees it up, it's
Tiger against the field, and Tiger always wins. But Tiger has met his match.
While his mind was willing, his body has suffered a breakdown.
The medical story goes like this. In the midst of his latest winning streak,
Tiger ruined his left knee, tearing the anterior cruciate ligament (ACL) and
damaging the cartilage. Most people can't easily walk with this injury; Tiger
played on. In mid-April he underwent
arthroscopyto trim the damaged cartilage
and began golf practice almost immediately. Without his surgeon's blessing, he
played and won the USGA Open 2008. Only afterwards was it revealed that he had
sustained a stress fracture in his
tibia. The pain on his face could now be
understood. It is time to pay the piper. Tiger is done for the year, with knee
reconstruction surgery and months of rehab in his future.
Hypertrophic cardiomyopathy (HCM) is associated with thickening of the heart muscle, most commonly at the septum between the ventricles, below the aortic valve. This leads to stiffening of the walls "...