FDG PET-CT findings of extra-thoracic sarcoid are associated with cardiac sarcoid: A rationale for using FGD PET-CT for cardiac sarcoid evaluation

Abstract

Our study shows that 40% of CS patients also have FDG PET-CT findings of extra-thoracic sarcoid. This makes an intriguing case for FDG PET-CT use with pretest diet prep over cardiac MRI (CMR) for cardiac sarcoid evaluation, given that CMR is likely to overlook these extra-thoracic sites of disease.

The logic and challenges of imaging sarcoidosis with whole body FDG PET

“…7,13,14 In the present issue of the Journal of Nuclear Cardiology, Patel and colleagues from the University of Illinois, Chicago, investigate the relationship of extrathoracic sarcoid findings in patients with cardiac sarcoidosis using FDG PET-CT, performed after a 72-hour high fat, high protein, and very low carbohydrate (HFHPVLC) diet. 15 Their aim was to determine if sarcoid patients being evaluated for cardiac involvement would benefit from whole body FDG PET-CT imaging (skull base to thighs) versus the limited thoracic imaging offered by cardiac MRI. A total of 191 consecutive FDG PET-CT scans were reviewed, of which 20 scans (10%) were positive and six scans indeterminate (3%) for CS.…”

“…15 Previously their group had proven effectiveness and high compliance rates using the same dietary preparation method. 22 Similar to their prior publication, the authors report an impressive indeterminate rate of 3% and only three patients excluded from the study due to diet nonadherence, again validating its effectiveness and high compliance rate.…”

“…15 Other methods of image interpretation and pattern classification have been described, however until the recent publication of the 'Joint SNMMI-ASNC Expert Consensus Document on the Role of FDG PET/CT in Cardiac Sarcoid Detection and Therapy Monitoring,' none were formally established or validated with histological findings, 23,24,25 thus setting up for inconsistent image interpretation. For example, while diffuse myocardial FDG uptake has been described as a normal variant by some investigators, 12,26,27 Patel et al categorize this finding as ''indeterminate''.…”

“…For example, while diffuse myocardial FDG uptake has been described as a normal variant by some investigators, 12,26,27 Patel et al categorize this finding as ''indeterminate''. 15,22 There is also the mystery of FDG uptake in the lateral wall and ring-like diffuse activity at the heart base seen in some normal/healthy individuals. 23,27 Moreover, Patel et al make no reference to myocardial perfusion during image interpretation, which is considered important and essential by most practitioners.…”

“…25 Although not the focus of their study, Patel et al make reference to the added benefit of treatment monitoring with FDG PET-CT by including example images of a case study of disease progression after 17-month steroid therapy that prompted change in treatment. 15 FDG PET can be used to assess treatment response/ disease activity not only visually but also objectively by using different quantitative techniques. 13,30,31 Ahmadian and colleagues nicely demonstrate that visual interpretation of FDG PET-CT images in cardiac sarcoidosis is less sensitive than quantitative measures (cardiac metabolic volume, cardiac metabolic activity and maximum standardized uptake value) for the assessment of response to immunosuppressive treatment.…”