Hybrid CMR/FDG PET to Differentiate Active From Chronic Cardiac Sarcoidosis

Mar 08, 2022
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Authors:
Greulich S, Gatidis S, Gräni C, et al.
Citation:
Hybrid Cardiac Magnetic Resonance/Fluorodeoxyglucose Positron Emission Tomography to Differentiate Active From Chronic Cardiac Sarcoidosis. JACC Cardiovasc Imaging 2022;15:447-458.
Summary By:
Debabrata Mukherjee, MD, FACC

Quick Takes

  • A single session hybrid CMR/FDG-PET including CMR mapping techniques may offer a robust tool for the detection of cardiac sarcoidosis, as well as for determining disease activity.
  • If validated, these findings may be used in designing future imaging approaches for cardiac sarcoidosis as well as for identifying patients most likely to benefit from immunosuppressive therapies to prevent irreversible scar and LV dysfunction.

Study Questions:

What is the diagnostic value of simultaneous hybrid cardiac magnetic resonance (CMR) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for detection and differentiation of active (aCS) from chronic (cCS) cardiac sarcoidosis?

Methods:

The investigators prospectively enrolled 43 patients with biopsy-proven extracardiac sarcoidosis (median age 48 years, interquartile range 37-57 years, 65% male) for evaluation of suspected CS. After dietary preparation for suppression of myocardial glucose metabolism, patients were evaluated on a 3-T hybrid PET/MR scanner. The CMR protocol included T1 and T2 mapping, myocardial function, and late gadolinium enhancement (LGE) imaging. The authors assumed aCS if PET and CMR (i.e., LGE or T1/T2 mapping) were both positive (PET+/CMR+), cCS if PET was negative but CMR was positive (PET-/CMR+), and no CS if patients were CMR negative regardless of PET findings. Groups with categoric variables were compared by means of Fisher-Freeman-Halton test. Wilcoxon or Kruskal-Wallis with Steel-Dwass post hoc test on all groups was used to compare continuous variables.

Results:

Among the 43 patients, myocardial glucose uptake was suppressed successfully in 36 (84%) patients. Hybrid CMR/FDG-PET revealed aCS in 13 patients (36%), cCS in 5 (14%), and no CS in 18 (50%). LGE was present in 14 patients (39%); T1 mapping was abnormal in 10 (27%) and T2 mapping abnormal in 2 (6%). CS was diagnosed based on abnormal T1 mapping in 4 out of 18 CS patients (22%) who were LGE negative. PET FDG uptake was present in 17 (47%) patients.

Conclusions:

The authors concluded that comprehensive simultaneous hybrid CMR/FDG-PET imaging is useful for the detection of CS and provides additional value for identifying active disease.

Perspective:

This study reports a significant burden of CS (50%) diagnosed by using a multiparametric CMR tissue characterization protocol (LGE, T1 and T2 mapping), and further classified by simultaneous FDG-PET into active (n = 13; 72%) and chronic (n = 5; 28%) CS. These data suggest that a single session hybrid CMR/FDG-PET including CMR mapping techniques may offer a robust tool for the detection of CS, as well as for determining disease activity. Since this was a single-center study with a relatively small sample size, these results require further validation by others, and if validated, these findings may be used for future imaging approaches for augmenting the detection of CS as well as for identifying patients most likely to benefit from immunosuppressive therapies to prevent irreversible scar and left ventricular (LV) dysfunction.

Clinical Topics: Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Acute Heart Failure, Computed Tomography, Magnetic Resonance Imaging, Nuclear Imaging

Keywords: Contrast Media, Diagnostic Imaging, Fluorodeoxyglucose F18, Gadolinium, Heart Failure, Immunosuppression, Magnetic Resonance Imaging, Positron-Emission Tomography, Sarcoidosis, Secondary Prevention, Ventricular Dysfunction, Left


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