Optimizing PET/CT protocols: is 60-minute [18 F]F-FDG uptake sufficient for cardiac sarcoidosis?

Area of Science:

• Nuclear Medicine
• Cardiology
• Radiology

Background:

• [¹⁸F]F-FDG PET/CT is a key imaging tool for diagnosing cardiac sarcoidosis (CS).
• The optimal uptake time for FDG injection to target-to-background ratio in CS diagnosis is not fully established.
• A 90-minute uptake time is common, but its necessity over shorter intervals requires investigation.

Purpose of the Study:

• To compare the diagnostic performance of 60-minute versus 90-minute uptake times for [¹⁸F]F-FDG PET/CT in suspected CS.
• To evaluate if a shorter uptake protocol can maintain diagnostic accuracy for CS.

Main Methods:

• Eighty-seven patients with suspected CS underwent [¹⁸F]F-FDG PET/CT at 60 minutes post-injection, with an additional chest scan at 90 minutes.
• Standardized patient preparation included a low-carbohydrate diet, prolonged fasting, and heparin administration for myocardial suppression.
• Three blinded readers assessed scans using binary classification, with Japanese Circulation Society criteria as the reference standard.

Main Results:

• Interrater agreement was substantial (κ = 0.690-0.693) and intrarater agreement ranged from substantial to almost perfect (κ = 0.703-0.899).
• Diagnostic accuracy was high for both time points in patients with adequate myocardial suppression: 97% at 60 minutes and 92% at 90 minutes.
• No statistically significant difference in diagnostic accuracy was found between the 60-minute and 90-minute uptake times (p = 0.22).

Conclusions:

• [¹⁸F]F-FDG PET/CT with a 60-minute uptake time demonstrates comparable diagnostic accuracy to a 90-minute uptake for CS detection.
• Adequate myocardial glucose suppression is crucial for achieving high diagnostic performance with the shorter uptake time.
• A 60-minute uptake protocol offers potential benefits in streamlining workflow and enhancing patient comfort without compromising diagnostic integrity.