FDG PET reigns for diagnosing infected prosthetic heart valves

Infections related to heart valve prosthesis are usually diagnosed with echocardiography, but it can miss key areas of infection. It is here that FDG PET or leukocute scintigraphy can step in, but a recent comparison study of the two nuclear medicine procedures published Nov. 13 in the Journal of Nuclear Medicine shows that FDG PET may be the best option.

While this complication is relatively rare, occurring in an average 1 to 6 percent of patients who have undergone valve replacement, it comes with a very high mortality rate. Early diagnosis can save lives.

Francois Rouzet, MD, PhD, from the department of Nuclear Medicine at Bichat University Hospital in Paris, and colleagues imaged 39 patients with suspected infective endocarditis and found that FDG PET was a highly sensitive detection method. Of the 39 patients, 14 were diagnosed as having infective endocarditis and four cases were inconclusive.

While FDG PET showed great sensitivity, 93 percent, compared to leukocyte scintigraphy’s 63 percent sensitivity. Also, FDG PET had a high positive predictive value of 94 percent.

“In summary, F-18 FDG PET offers high sensitivity for the detection of active infection in patients with suspected [prosthetic valve endocarditis] and inconclusive echocardiography findings and represents a useful first-line imaging technique in this situation,” Rouzet et al concluded.

However, leukocyte scintigraphy should not be ruled out completely. It was found to have superior specificity, 100 percent, when compared to FDG PET, which had a specificity of 71 percent. This indicates that leukocyte scintigraphy could be used when FDG PET scans are unclear or in situations when other kinds of inflammation are present, such as after surgery.