Improving 18F-FDG PET Imaging Using Canola Oil For Evaluation Of Cardiac Sarcoidosis

Abstract

Objective The incidence and prevalence of cardiac sarcoidosis (CS) is increasing significantly, likely due to improved noninvasive diagnostic methods such as 18F-FDG PET imaging and a higher index of suspicion among clinicians. Cardiac PET for diagnosis of CS requires a strict low carbohydrate diet which even if adhered to can still lead to false positives. One protocol that has been explored with mixed results is consuming a beverage high in fat to improve myocardial suppression. Our objective was to evaluate if a new diet preparation protocol using canola oil can improve 18F-FDG PET imaging. Methods In patients undergoing evaluation for CS with 18F-FDG PET and inadequate myocardial suppression on a prior study, we administered 1 cup of canola oil (224 grams of fat) 1 hour before repeating the study in addition to our standard diet. The repeat study was compared to the prior to determine if there was improved myocardial suppression. Canola oil was specifically chosen as we considered it to be most palatable to drink in a large quantity in one sitting. Results Our study protocol showed that all four patients had an improvement in myocardial suppression (Figure 1). Patient A is a 60-year old man with CS who underwent a PET-CT 3 months after initiating treatment which showed increased myocardial FDG uptake. The repeat scan with the canola oil protocol demonstrated less FDG myocardial uptake with an SUV max of 5.9 (previously 11.3). Similarly, Patient B is a 63-year old man with CS who initiated treatment and had a PET scan at 3 months showing increased FDG uptake with the repeat scan using our protocol showing decreased myocardial FDG uptake with an SUV of 3.1 (previously 12.8). Patient C is a 50-year old man with pulmonary sarcoidosis whose initial PET scan showed diffuse FDG uptake (SUV 6.4) and repeat with the protocol showed minimal FDG uptake (SUV 3.0). Finally, Patient D is a 54-year old man with frequent PVCs and MRI showing patchy late gadolinium enhancement whose initial PET_CT showed patchy FDG uptake (SUV 7.5) and repeat scan with the protocol showed no evidence of sarcoidosis (SUV 1.3). Overall the only side effect was steatorrhea for up to one day after canola oil consumption. Conclusion In patients undergoing evaluation for CS with 18F-FDG PET who have inadequate myocardial suppression, canola oil may improve imaging characteristics and decrease false positives. The incidence and prevalence of cardiac sarcoidosis (CS) is increasing significantly, likely due to improved noninvasive diagnostic methods such as 18F-FDG PET imaging and a higher index of suspicion among clinicians. Cardiac PET for diagnosis of CS requires a strict low carbohydrate diet which even if adhered to can still lead to false positives. One protocol that has been explored with mixed results is consuming a beverage high in fat to improve myocardial suppression. Our objective was to evaluate if a new diet preparation protocol using canola oil can improve 18F-FDG PET imaging. In patients undergoing evaluation for CS with 18F-FDG PET and inadequate myocardial suppression on a prior study, we administered 1 cup of canola oil (224 grams of fat) 1 hour before repeating the study in addition to our standard diet. The repeat study was compared to the prior to determine if there was improved myocardial suppression. Canola oil was specifically chosen as we considered it to be most palatable to drink in a large quantity in one sitting. Our study protocol showed that all four patients had an improvement in myocardial suppression (Figure 1). Patient A is a 60-year old man with CS who underwent a PET-CT 3 months after initiating treatment which showed increased myocardial FDG uptake. The repeat scan with the canola oil protocol demonstrated less FDG myocardial uptake with an SUV max of 5.9 (previously 11.3). Similarly, Patient B is a 63-year old man with CS who initiated treatment and had a PET scan at 3 months showing increased FDG uptake with the repeat scan using our protocol showing decreased myocardial FDG uptake with an SUV of 3.1 (previously 12.8). Patient C is a 50-year old man with pulmonary sarcoidosis whose initial PET scan showed diffuse FDG uptake (SUV 6.4) and repeat with the protocol showed minimal FDG uptake (SUV 3.0). Finally, Patient D is a 54-year old man with frequent PVCs and MRI showing patchy late gadolinium enhancement whose initial PET_CT showed patchy FDG uptake (SUV 7.5) and repeat scan with the protocol showed no evidence of sarcoidosis (SUV 1.3). Overall the only side effect was steatorrhea for up to one day after canola oil consumption. In patients undergoing evaluation for CS with 18F-FDG PET who have inadequate myocardial suppression, canola oil may improve imaging characteristics and decrease false positives.