Cardiac FDG PET/CT in inflammatory myocarditis

Objectives Diagnosis and monitoring treatment response in Inflammatory myocarditis is mainly based on imaging.This study shows the unique role of FDG Cardiac PET/CT in the diagnosis and management of patients with Inflammatory myocarditis.

Methods This is an analysis of FDG PET/CT studies performed for the diagnosis of inflammatory myocarditis in patients who presented with dilated cardiomyopathy and to assess the treatment response on follow up.128 patients underwent FDG PET/CT, dedicated cardiac and whole body.All these were put on Very High Fat Low Carbohydrate Protein Preferred diet, to achieve adequate myocardial suppression & avoid variable uptake in fasting state. Myocardial perfusion scan with 99mTc tetrofosmin &13NAmmonia was performed prior to FDG PET in all patients.Diagnostic criteria is focal/diffuse FDG uptake in the myocardium with/with out perfusion mismatch.Chest and whole body survey also performed in all patients for the extra cardiac disease.

Results 88patients had abnormal myocardial uptake. 42 had associated nodal involvement.35 had normal scans, including 18 who had complete response following the treatment.Histopathology correlation obtained wherever possible. Non caseating granulomatous nodal disease was found in 12 ,caseating & non caseating granulomas in 18 with acid fast bacilli positive in 8 and only caseating granulomas in 4.Liver & spleen involved in 6 cases.Endomyocardial biopsywas done in 3 cases,where 1was positive with non caseating granulomas,1 showed lymphocytes and 1 was inconclusive.22 patients had followup out of which 19 showed complete response,2 had persistent cardiac disease and 1 had progressive disease.

Conclusions Cardiac FDG PET/CTwith VHFLCPP diet is shown to be an excellent modality in diagnosing inflammatory myocarditis,unmatched in patient with ICDevices where MRI could not be done.In the era of practice of evidence based medicine this has been shown to be very promising investigation to show the treatment response.