Screening for acute myocarditis--is scintigraphy with (99m)Tc-Anti-Granulocyte BW 250/183 an answer?

BACKGROUND

Myocarditis is most often caused by Coxackie B virus, influenza viruses, and echoviruses. It is usually self-restricting and ending in full recovery, but in some patients the infection leads to congestive cardiomyopathy. It is difficult to identify patients with myocarditis using clinical criteria, laboratory tests, ECG and ultrasonography, and currently a myocardial biopsy is required to establish the diagnosis. The risk of complications, sampling error and costs of this procedure underline the need of non-invasive but sensitive methods of imaging. Several radiopharmaceuticals have been used so far to confirm inflammation: 67Ga, (99m)Tc-nanocolloids and 111In-leucocytes. Scintigraphy with radiolabeled autologous white blood cells (WBCs) is considered a very useful method in identifying sources of inflammation but is difficult to perform and time-consuming.

AIMS

The aim of our study was to investigate whether scintigraphy with (99m)Tc-Anti-Granulocyte BW 250/183 antibody is a valuable diagnostic method in evaluating focal and diffuse inflammation of the heart and could therefore be suggested for use in screening for acute myocarditis.

MATERIAL AND METHODS

A two dimensional scintigraphy and SPECT mode of heart imaging with the use of (99m)Tc-Anti-Granulocyte antibody (740 MBq) was performed on 14 subjects (11 males and 3 females) aged 25-60 years with a positive myocardial biopsy confirming an inflammatory process in the myocardium. After i.v. administration of the tracer a 1 minute series of planar scans was performed within the first 60 minutes. Delayed static scans were performed at 1, 2, 4 and 24 hours.

RESULTS

The scintigraphic scans revealed the uptake of the tracer in the heart area in 13 patients, confirming active inflammatory process. Follow-up scintigraphy was performed 3-5 months after the first study, when the control myocardial biopsy was negative. The results of the study showed the concordance between myocardial biopsy and scintigraphy results in patients with an inflammatory process in the heart.

CONCLUSIONS

Scintigraphy with the use of (99m)Tc-Anti-Granulocyte seems to be a useful diagnostic method in evaluating patients with suspected myocarditis, but further studies are needed to establish its sensitivity and specificity.