What are some of the potential uses of cardiac MRI?

Once certain limitations are overcome - and that day seems to be rapidly approaching - the uses of cardiac MRI will greatly increase.

MRI has the potential (and has been used in the research setting) to diagnose heart attacks in patients presenting with chest pain. Not infrequently, a patient coming to the emergency room with chest pain will not have the typical ECG changes seen with myocardial infarctions, and the doctors end up waiting for an hour or two for the results of cardiac enzyme tests. If a heart attack is actually occurring, critical time is thus lost before therapy can begin. MRI can detect myocardial infarction immediately, and can reduce the time it takes to begin definitive treatment.

Strides are being made toward being able to diagnose coronary artery disease with MRI. A new MRI processing technique called "black-blood" MRI (so called because it produces an image of an artery in which the blood appears black, and the wall of the artery appears white) seems to be able to distinguish very nicely between normal and atherosclerotic coronary arteries. While further refinements are necessary, such techniques are bringing us very close to the day in which MRI will be able to replace cardiac catheterization for diagnosing coronary artery disease.

MRI can help distinguish between "stable atherosclerotic plaques and "vulnerable" plaques. Vulnerable plaques are those that are prone to rupture, thus suddenly occluding a coronary artery and causing a myocardial infarction. If vulnerable plaques can be identified (and this is something the cardiac catheterization cannot do), those particular plaques can be targeted for intervention (angioplasty, stent, or bypass surgery), while leaving the stable plaques alone. MRI has already proven useful in the research setting for identifying restenosis after angioplasty. MRI might thus prove an accurate, noninvasive means of following patients after angioplasty.

MRI has the potential of detecting changes in the tiny blood vessels of the heart the microvascular circulation that are completely missed by cardiac catheterization. Detecting such changes seem to be useful in predicting the outcome of patients after a heart attack, and may prove to be useful in assessing patients with cardiac syndrome x, diabetes, and certain other conditions.

Ultimately, MRI may replace the x-ray tube in both diagnostic and therapeutic situations. Research is already being done in animals using MRI to image the coronary arteries instead of using x-rays for angioplasty procedures. The technology that allows these potential uses of cardiac MRI is presently being tested and refined. Within a few years, at least some of these uses will come into widespread clinical application.

Treating Gallstones and Bile Duct Stones

Gallstones and bile duct stones may be treated first with antibiotics to help control infection. They also can be treated at the time of diagnosis with miniaturized surgical instruments inserted through an ERCP. Alternatively, stones may be treated with medications that dissolve them, with lithotripsy that uses sound waves to break them up, or with surgery to remove the gallbladder.

ENDOSCOPIC TECHNIQUES
When a stone has been identified on x-ray, ultrasound or MRI imaging as blocking a bile or pancreatic duct, it can be removed with miniaturized instruments inserted through the ERCP. These surgical instruments gently enlarge the ductal opening that then allows the stone to be removed.

MEDICATIONS
Medications can be given that dissolve gallstones but they are not always effective and are not indicated in all cases. The most common medication is a bile salt (ursodiol) that slowly dissolves cholesterol within the stones. However, the stones can return when the medication is discontinued.

EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY
This treatment employs high-frequency sound waves to break up gallstones. Patients then take bile salt tablets, sometimes indefinitely, to dissolve the pieces and to ensure that the stones do not return. Only a minority of patients are candidates for this type of treatment, however. The best candidates have a single small stone. If an infection (cholangitis) or inflammation (cholecystitis) of the gallbladder is present, lithotripsy is not an option. Extracorporeal (meaning outside of the body) shock wave lithotripsy is performed by directing pulsating, high-intensity sound waves at the area where the stone is located, identified first by ultrasound. The procedure takes about 45 minutes and patients are usually lightly sedated before treatment.

SURGERY
Surgery to remove the gallbladder, called cholecystectomy, is a common procedure in the United States for individuals with symptoms caused by gallstones. Virginia Mason was one of the first medical centers in the country to remove the gallbladder by the minimally invasive laparoscopic approach, called laparoscopic cholecystectomy.

This minimally invasive surgery for removing the gallbladder is one of the most common procedures performed at Virginia Mason and is, in fact, the preferred approach today for removal of the gallbladder. In cases in which a gallstone or bile stone has blocked a bile duct - a situation that can lead to infection or inflammation of organs within the biliary tract - surgeons will likely recommend removal of the gallbladder.
Laparoscopy
During laparoscopy, the surgeon makes several ¼ to ½ inch incisions in the abdomen. He or she then inserts miniaturized endoscopic and surgical instruments, and a small camera, through these "ports." Images from the camera are sent to a video monitor that allows the surgeon to "deflate" and then remove the gallbladder through one of the ports. Individuals return to their regular activities often within a few days.

Open surgery
Sometimes the surgeon must revert to an open surgical procedure during a scheduled laparoscopy to remove the gallbladder. These occurrences happen infrequently and are most often caused when the gallbladder is found to be infected or when the gallbladder lining is hardened, making it more difficult for the organ to be removed laparoscopically.

At other times, the surgeon may make the decision that the open surgical procedure is the best option for the patient based on the severity of the individual's gallbladder disease. Open surgery involves making a large incision in the abdomen and removing the gallbladder. Recovery time is longer, five to seven days in the hospital, and there is a longer return to daily activities: two to three weeks, for example.

Symptoms of Gallstones and Bile Duct Stones

Gallstones can be miniscule in size or as large as a ping-pong ball. You may have one stone or develop many of them. Not all gallstones or bile stones cause symptoms. Some are discovered incidentally during imaging studies for other reasons.

The most common symptom is upper abdominal pain on the right side of the body, where the liver and gallbladder are situated. The pain may start suddenly and be intense. Or it may be a slow, dull pain or occur intermittently. The pain may shift from the abdominal area to the upper back or shoulder.

Prolonged blockage of a bile duct can cause a buildup of waste products in the biliary tract and in the bloodstream, leading to an infection called cholangitis. It also can prevent the release of bile into the small intestine to help digest food or cause a serious bacterial infection in the liver called ascending cholangitis.

A blocked bile duct may result in inflammation of the gallbladder, called cholecystitis. A gallstone or bile stone in the common bile duct may block the pancreatic duct, causing painful inflammation of the pancreas or pancreatitis.  

If a stone completely blocks the ducts of the gallbladder, liver, common bile duct or pancreas, other symptoms may include:

• Nausea
• Fever
• Chills
• Yellow skin or eyes (from the build up of bilirubin, a waste product in blood)
• Dark urine
• Itching
• Fatigue
• Weight loss
• Night sweats
• Loss of appetite
• Greasy or light-colored stools

Patients who develop gallstones are at a slightly increased risk of developing gallbladder cancer, called cholangiocarcinoma. However, this is a rare disease and most people with gallstones do not go on to develop cancer.