Possible Infective endocarditis confirmed by PET CT

5-year-old girl with fever (38.5) of 2 weeks duration. PDA closure 6 weeks ago.

She had 110/50 mmHg blood pressure and 150 bpm pulse with bounding peripheral pulsation and wide pulse pressure, a palpable systolic thrill at the upper left sternal border, on auscultation there was left infraclavicular continuous murmur.

X-ray

Her chest x-ray showed cardiomegaly and dilated pulmonary artery.

Echocardiography:

Her echo showed a large aneurysmally dilated pouch occupied by multiple echogenic masses connecting pulmonary artery and aortic arch, dilated left ventricle with depressed systolic function.

Blood culture was negative so according to the Modified Duke’s criteria we had only one major and minor character, however, we have a high suspicion of infective endocarditis, so, PET/CT was requested.

PET/ CT:

¹⁸F-FDG PET/CT whole body revealed an aneurysmal pouch connecting aortic arch and the main pulmonary artery (which was not on top of persistent ductus arteriosusu), containing metabolically active vegetation, the pouch wall was inflamed, there were bilateral pulmonary metabolically active septic emboli in pulmonary branch supplying left lower lung lobe with consequent infarction and impending abscess formation, the right 4^th and 5^th order branches are involved with septic emboli and ongoing abscesses. This pattern confirmed an extensive infection.

Infectious diseases of the heart are a heterogeneous and diverse group of diseases that may affect the endocardium, myocardium, and pericardium (1).

The underlying mechanisms in case of infective endocarditis are direct mechanical injury to the endothelium and under­lying endothelial inflammation, injury or bacteremia which allow circu­lating microorganisms to adhere and initiate infection (2).

Clini­cal presentations are usually nonspecific with symptoms ranging from intermittent fever to nondescript chest pain, palpitations, rapid hemodynamic decompensation, and sudden death (2).

Complications of IE including perivalvular abscess, new heart block, valve dehiscence or severe dysfunction, intracardiac fistula, and destructive penetrating lesions, pseudoaneurysm formation, septic emboli and extracardiac metastatic spread of infection (2)

The primary imaging modality remains echocardiography (2)

The other cross-section modalities used in diagnosis are (1, 2)

• CT
  • Modality of choice for complex infections or when prosthetic material, central lines, or devices are present
  • Preoperative planning
  • Complex infections with air or gas
  • Coronary evaluation/mycotic aneurysms
• MRI
  • Alternative modality for complete hemodynamic
  • imaging (affected ventricular function and valve regurgitation)
  • Repeated follow-up imaging
• PET/ CT
  • It is used for possible prosthetic valve infective endocarditis.
  • Can be used in other possible cases of difficult diagnosis with no prosthetic valve

 The presence of metabolically active vegetation and septic emboli confirmed the modified Duke’s criteria (2) found in the patient before surgery (fever and echocardiography findings) in addition to the final histopathology finding after surgery as patient underwent resection of the infected pouch and the vegetation and patch closure of the pulmonary artery and aorta.

Histopathology showed Aspergillus infection, her post-operative echo revealed no residual PDA and no masses.

The modified Duke’s criteria (2) are still used as the diagnostic criteria for infective endocarditis, they were extended to include PET/ CT in confirmation of the diagnosis in case of prosthetic cardiac material, yet, PET/ CT is not used in a liberal way in all cases, despite, being a strong confirmatory modality in confirmation and in evaluation of the extension of the infection process as it is used to scan the whole body (4).