A Blog for Healthcare Consumers

CT scans and MRI scans are high tech imaging studies that give doctors the ability to look at the internal anatomy of the body in great detail. One of the tools used to help in differentiating normal structures from abnormal structures like tumors, aneurysms, infection, is IV contrast dye. The dye used in CT scans is based on low osmolar contrast material and for MRI scans on gadolinium. The dye is injected through an IV catheter placed in a vein (usually in the arm or hand). The contrast highlights different tissue types bringing out vessels, tumors, inflammation, cysts, etc, that might be missed if the dye was not administered for the scan.

Many patients are unaware of the side effects of the dye or misinformed (and uninformed) about the risk of contrast administration. A recent contrast injection study by the Mayo Clinic in Rochester, MN looked back at over 450,000 dye injections. Below is a brief summary of their experience:

• CT scan dye side effects were 0.15%
  
• MRI dye side effects were 0.04%
  
• Most common side effects were hives and nausea
• 19 patients had a severe side effect (requiring medication, treatment)
• 1 patient died which is a mortality risk of 0.0003%

Clearly there is a risk of a severe reaction to the dye or even death. However, as the Mayo Clinic reports the vast majority of their patients did not have a reaction.

Although reactions to contrast are rare, it is standard practice to inform you of the possibility of dye administration and its potential side effects. However, keep in mind that many imaging facilities will not have a verbal discussion with you regarding IV contrast administration. It's usually in the paperwork you fill out before the test. Make sure you read and understand what you are signing in advance!

Have you had a contrast dye injection? What was your experience like? Leave your comments below.

MRI scans are frequently used to evaluate the internal structures of the brain. IAC MRIs are a type of Brain MRI that is used to evaluate the structures of the Internal Auditory Canal - IAC (aka Internal Auditory Meatus - IAM).

The IAC contains among other structures the 8th cranial nerve. This is a large nerve that conducts hearing and balance signals from your inner ear structures. This nerve can become damaged, inflamed or give rise to a tumor commonly called an "acoustic neuroma." Most IAC MRIs are ordered to rule out an acoustic neuroma in patients who are experiencing dizziness, ringing in the ears, hearing loss, fullness, for example. Although these tumors are slow growing and generally benign, they are close to vital structures in the brain and can be difficult to treat.

An MRI of the IACs is done with MRI dye. The dye helps detect small tumors and subtle inflammation that a non-contrast MRI may miss.

IAC MRIs also include the cerebellum, brainstem, vessels of the back of the brain and other nearby structures. Some IAC MRI protocols also include a few scans of the entire brain.

Your MRI IAC Scan

An MRI of the IACs generally takes about 30-40 minutes or so to complete. If you are going for one, wear loose comfortable clothing and remember to remove all metal (jewelry, phones, rings, etc) before going into the MRI scan room.

This test will be done with IV MRI contrast. The first part of the test is done without contrast. Then the scan is paused and the table on which you are lying will be pulled out (remember don't move!). The technologist will then inject the IV dye and return the table into the tube for the remainder of the scan.

If you're insured, you may need to have your test authorized (approved) by your insurance company first. If you're uninsured and need to look up prices and buy an MRI scan of the IACs (IAMs), you can use our website to look up MRI scan costs and then purchase with your credit card.

Have you had an MRI of IACs scan? What was it like? Please leave your comments below.

An CT scan can be used to image nearly every part of the body. CTs are very good at evaluating internal organs such as the liver, kidneys, pancreas and brain. They are also used to generate 3 dimensional images of bones such as the spine, ankle, and wrist. These 3D images assist in treatment and surgical planning.

CT is a relatively new technology that has rapidly advanced along with computing power. There are tens millions of CT scans done every year. Here are some commonly ordered CT scans and the sort of disease they are tailored to look for:

• CT Liver -- tumors, cysts, and cirrhosis of the liver
  
• CT Spine --degnerative disease (arthritis), fractures, bone tumors
  
• CT Brain -- stroke, tumors, bleeds, skull fractures
• CT Kidneys -- kidney stones, tumors, cysts, blockage (hydronephrosis)

What to do before your CT scan:

It helps to be prepared in advance of your appointment time. You will need to get a Radiology referral or prescription from your doctor. Check to make sure the facility you choose takes your insurance plan and your plan has authorized the CT. Get preparation instructions from the facility’s staff in advance. Many CT scans require dye/contrast.  Let the facility know if you have any kidney problems, allergies or are on medication. Although you should follow your doctor’s advice, you can choose a local imaging center to perform your CT test. Our Radiology Shopping tool will help you find a Radiology center, look up prices, and learn more about your local imaging services (if you don’t find an imaging center in your area, please let us know).

What to expect during and after your CT scan:

• The CT scan appointment may take up to 1 hour. Plan accordingly.
• Many CT scan tests will require a dye/contrast injection. An IV is placed and the dye is injected while the scanner takes pictures.
• An CT scan uses radiation, so you will be alone in the CT scan room.
• You may need to take a film or CD copy of your CT scan to your doctor.
• A physician Radiologist will interpret the CT. A report is sent to your doctor.