Imaging for Amyloid Deposits Also Shows Promise for Detecting Cardiac Amyloidosis

Whereas amyloid imaging may now be most associated with detecting plaques in the brain, it also has the potential to alter the way cardiac amyloidosis is diagnosed. According to first-of-its-kind research, positron emission tomography (PET) with 11C-PIB (Pittsburgh compound B) can effectively visualize amyloid deposits in the heart. Currently, there is no other noninvasive test available for specific diagnosis.

The study’s findings were published in the February 2013 issue of the Journal of Nuclear Medicine. Cardiac amyloidosis is a deadly disorder caused by abnormal amyloid deposits in the heart tissue. Early diagnosis before structural change to the heart tissue has occurred is important for disease prognosis and for treatment monitoring. Echocardiography is the current mainstay of imaging in cardiac amyloidosis; a cardiac biopsy is used to validate diagnosis.

“Imaging with 11C-PIB provides a noninvasive and specific means of showing distribution of amyloid in an organ. This gives a unique opportunity to follow and monitor therapy, as amyloid deposits in the heart should decrease with successful therapy,” said Gunnar Antoni, PhD, from department of medicinal chemistry, Uppsala University (Sweden), and lead author of the research.

The study included 10 patients diagnosed with cardiac amyloidosis and five healthy individuals. PET/computed tomography (CT) with 11C-PIB was used to visualize amyloid deposits in the heart and with 11C-acetate to measure myocardial blood flow.

Uptake of 11C-PIB was measured 15–25 minutes after injection. Obvious uptake of 11C-PIB was noted in the left ventricle wall of all patients with cardiac amyloidosis, while no uptake was seen in the healthy volunteers. In half of the patients, 11C-PIB was also detected in the right ventricle wall, and nine of the patients had signs of reversible uptake, with a maximum concentration at 10–15 minutes after injection. Myocardial blood flow was significantly lower in patients with cardiac amyloidosis; however, no significant correlation between myocardial blood flow and 11C-PIB uptake was found.

“This study emphasizes the strength of molecular imaging for detecting an underlying and significant molecular aberration in a disease that presents with unspecific symptoms and signs,” noted Dr. Antoni. “The potential for molecular imaging to provide valuable information for other diseases is of great value to the field of medicine.”

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