PET/CT Case Series: Unmasking the Mystery of Cardiac Sarcoidosis

Workflow example for 1-d cardiac sarcoid PET/CT imaging. *One-day PET/CT protocols currently use ⁸²Rb-chloride or ¹³N-ammonia for rest PET perfusion imaging. Use of ¹⁸F perfusion radiopharmaceuticals may require increased time between rest PET perfusion and ¹⁸F-FDG scans.

Scan 1 ⁸²Rb-chloride rest perfusion (top rows) and ¹⁸F-FDG cardiac metabolism (bottom rows). Rest perfusion images show small mid inferolateral wall defect (white arrows) and normal distribution of activity throughout remaining LV myocardium. Gated rest LVEF is 32%. ¹⁸F-FDG cardiac slices show suboptimal display intensity for ¹⁸F-FDG cardiac sarcoidosis imaging, as neither ¹⁸F-FDG myocardial blood-pool activity nor activity in LV myocardial wall can be appreciated in current display.

Scan 1 ⁸²Rb-chloride rest perfusion (top rows) and rescaled ¹⁸F-FDG cardiac metabolism (bottom rows). Images show appropriate ¹⁸F-FDG display intensity with blood-pool activity (white arrows) brighter than LV wall, indicating normal FDG uptake pattern. No evidence of any focally increased ¹⁸F-FDG uptake in LV myocardial wall is seen, which indicates negative examination for active cardiac sarcoidosis.

Scan 1 ¹⁸F-FDG maximum-intensity projection (left), fused ¹⁸F-FDG PET/CT sagittal (middle), and fused ¹⁸F-FDG PET/CT coronal (right) views. Images show diffuse hypermetabolic uptake (arrows) in mediastinal and hilar lymphadenopathy biopsy-proven noncaseating granulomatous disease. ¹⁸F-FDG PET/CT scan 1 is negative for cardiac sarcoidosis but positive for extracardiac sarcoidosis.

Scan 2 ⁸²Rb-chloride rest perfusion (top rows) and ¹⁸F-FDG cardiac metabolism (bottom rows). Images show diagnostic evaluation with ¹⁸F-FDG blood-pool activity indicating adequate dietary preparation. Rest images show borderline hypoperfusion in basal to mid inferolateral wall and moderate LV enlargement. Rest gated images showed 31% LVEF. ¹⁸F-FDG images show suspected early-to-progressive stable cardiac sarcoidosis with moderate inflammatory ¹⁸F-FDG uptake in basal to mid inferolateral wall (arrows).

Scan 2 ¹⁸F-FDG maximum-intensity projection (left) and ¹⁸F-FDG PET/CT fused coronal (right) images. Persistent ¹⁸F-FDG–avid bilateral mediastinal and hilar/perihilar adenopathy is visualized from known extracardiac sarcoidosis (arrows). Solitary ¹⁸F-FDG–avid left upper abdominal node is suspicious for additional sarcoid involvement (circles).

Scan 3 ⁸²Rb-chloride rest perfusion (top rows) and ¹⁸F-FDG cardiac metabolism (bottom rows). Rest MPI shows no significant perfusion defects in LV. ¹⁸F-FDG PET images show diffusely increased myocardial uptake (rectangles), more prominent in lateral wall. This pattern of diffusely increased ¹⁸F-FDG cardiac uptake indicates hyperinsulinemic state, suggesting possible inadequate dietary compliance, and limits evaluation of ¹⁸FDG-PET images for cardiac sarcoidosis. Gated rest images show estimated LVEF of 24%.

Scan 3 ¹⁸F-FDG sagittal maximum-intensity projection (left), ¹⁸F-FDG PET/CT fused axial (middle), and ¹⁸F-FDG PET/CT fused coronal (right) views. Images show mediastinal, supraclavicular (white arrows), and retroperitoneal (circle) hypermetabolic lymphadenopathy with new or enlarged lymph nodes since scan 1, consistent with sarcoidosis with possible involvement of bilateral ribs (black arrows).

Scan 4 ⁸²Rb-chloride rest perfusion (top rows) and ¹⁸F-FDG cardiac metabolism (bottom rows). Rest perfusion images show medium-sized mild defect in basal to mid lateral and inferolateral wall (white arrows). Gated rest LVEF was 31%. ¹⁸F-FDG images show diffusely suppressed myocardial uptake, indicating adequate dietary preparation. Medium-sized area of increased ¹⁸F-FDG uptake is visualized in basal to mid lateral and inferolateral wall (single yellow arrows) similar to scan 2. New small-sized area of mildly increased ¹⁸F-FDG uptake is visualized in basal anteroseptal wall (double yellow arrows).