CHICAGO, Dec. 20 (UPI) -- A new study may help improve the diagnosis of cardiac sarcoidosis through better diagnostic imaging results.
Researchers at the University of Illinois at Chicago found that when patients consume a high-fat, low-sugar diet 72 hours before diagnostic imaging, the diagnosis rate of cardiac sarcoidosis was greatly improved.
Cardiac sarcoidosis is an inflammatory disease that attacks multiple organs and has higher rates of diagnosis among African Americans.
"Up until now, diagnosis is made by expert opinion based on the results of several testing techniques including imaging," Dr. Yang Lu, assistant professor of radiology in the UIC College of Medicine and corresponding author of the study, said in a press release. "But what these scans show is often ambiguous, and so using them to definitively diagnose cardiac sarcoidosis is problematic. There is really currently no gold standard for diagnosing cardiac sarcoidosis."
Diagnostic imaging such as positron emission topography, or PET scans, and computed tomography, or CT scans, are used to diagnose cardiac sarcoidosis by having patients inject a short-lived radioactive tracer fludeoxyglucose, or FDG, but the results are often hard to interpret.
This is due to FDG, which is similar to glucose, concentrating in cells with very high metabolic rates that use lots of sugar for energy such as cancer cells and neurons. Cells affected by inflammation like those found in cardiac sarcoidosis stand out more clearly in imaging scans.
Doctors had been having patients consume high-fat, low-sugar diets for a 24-hour period before scans because healthy heart cells use the abundant fat for fuel, so cells affected by disease that use sugar are more easy to see. However, when doctors used this method, they were not getting the results they wanted.
"When we used this method, we noticed that the results were not satisfactory," Lu said. "The unpredictable uptake of FDG by healthy heart cells makes the scans hard to read."
But a surprising discovery was made when a patient showed up a day late for their scheduled scan.
"The patient had been following the high-fat, low-sugar diet for two days at that point instead of the usual 24 hours," Lu said, adding that when the patient was scanned, the areas where the heart picked up FDG were clearer and showed active cardiac sarcoidosis.
"More excitingly, these abnormal areas were in the same location as abnormal findings from the patient's cardiac MRI, which was indicative of cardiac sarcoidosis. We were very confident that this patient did, indeed, have cardiac sarcoidosis."
The accidental discovery lead to the study of 215 tests from 207 patients at the University of Illinois Hospital in 2014 and 2015.
The patients were placed into two groups by the consumption of high-fat, low-sugar diets for 24 hours prior to imaging and 72 hours prior to imaging. The results showed 42 percent of patients in the 24-hour diet group had indeterminate results compared to only 4 percent of patients in the 72-hour diet group.
The study was published in Clinical Nuclear Medicine.