This document discusses non-malignant cardiac findings that can present on FDG PET-CT scans. It presents 5 case examples of focal cardiac FDG uptake and describes the diagnostic approach and differential diagnosis in each case. Common non-malignant etiologies that can cause increased cardiac FDG uptake include physiologic variants, inflammation from conditions like sarcoidosis, infection from endocarditis, and anatomical variants like lipomatous hypertrophy of the interatrial septum. Differentiating malignant from non-malignant cardiac FDG uptake is important to avoid unnecessary diagnostic steps or treatment.

1. Non-malignant
cardiac findings on
FDG PET CT
Il Kyu Oh, MS3
Jayanth Keshavamurthy, MD
Hadyn Williams, MD
Rubjit Nagpal, MD
Darko Pucar, MD

2. Financial disclosure
• None to disclose for all authors

3. Background
• Oncologic18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)
/ computed tomography (CT)
– essential for initial cancer staging and treatment monitoring
– Focal FDG activity is a sensitive tool to localize malignant process
– Focal FDG activity can be physiologic or non-malignant process (infection,
inflammation)
• Cardiac FDG uptake
– Often not evaluated for oncologic PET-CT due to variable uptake pattern
– Physiologic findings can include diffusely increased, focally increased, or
regionally increased uptake
• Differentiating malignant and non-malignant causes of focal cardiac FDG
activity is important, as it can prevent unnecessary diagnostic steps and
treatment

4. Learning points / Educational goal
• To describe diagnostic approach in differentiating non-
malignant and malignant causes of focal cardiac FDG
activity on oncologic whole-body FDG-PET-CT scan
• To describe assessment and the management of non-
malignant cardiac lesions

5. Normal cardiac finding in PET-CT
• Variability of cardiac FDG signal in the fasting state
• Residual cardiac blood pool activity
• Certain pattern of physiologic FDG cardiac pattern
– Decreased intensity in the septum and anterior wall
of left ventricle
– Increased uptake in posterolateral side of the heart
– Increased signal in the base of the heart.

6. Case 1
– 75-year-old male admitted due to recurrent
hypoglycemic episode and persistent bacteremia
– TEE showed a mobile mass above aortic valve
– PET-CT was ordered for further evaluation

7. Crista Terminalis
PET-CT shows increased focal uptake near
the anatomical location of the crista
terminalis, which is most likely to represent
physiologic process. Cardiac MR shows right
atrial appendage at the location of FDG
uptake

8. Increased uptake in Atrium
• Crista terminalis muscle is a crescent-
shaped muscle within the right atrium
– This muscle can show increased
FDG activity mimicking a cardiac
mass.
• Atrial fibrillation is another common
etiology that can show localized FDG
uptake in the atrium.
https://www.imaios.com/en/e-Anatomy/Anatomical-Parts/Crista-terminalis

9. Case 2
• A 59-year-old white female diagnosed with renal cell
carcinoma in 2010
• Status post right nephrectomy
• Humeral metastasis found in 2015, status post surgery
and XRT.
• Currently on chemotherapy (Pazopanib)
• Follow-up PET-CT was ordered.

10. Lipomatous hypertrophy of interatrial septum (LHAS)
PET-CT shows increased
metabolic activity involving
lipomatous hypertrophy of
the interatrial septum. This is
most likely to represent
physiologic process

11. Increased uptake in myocardium
• Primary cardiac tumors are rare, less common than cardiac
metastasis from other primary tumor
• Due to variable physiologic myocardial uptake, it is difficult
to identify malignancy from PET-CT
• Lipomatous hypertrophy of interatrial septum (LHAS) is
caused by deposition of fat tissue. Benign cardiac finding
often incidentally found on imaging
– Increased uptake may be observed in LHAS, mimicking
other malignant process.
• Normal epicardial fat can also present with increased FDG
activity

12. Case 3
• 40-year-old male with history of congenital heart
diseases and ASD repair
• Presented to the hospital after several days of nausea,
vomiting, fever, and diarrhea

13. Endocarditis
There is intense focal activity at the aortic root, consistent with aortic root
abscess. There are areas of increased uptake suggesting additional hardware
infection. There are evidences of septic emboli in the lung.

14. Endocarditis
• Infective endocarditis is an infection of endocardium by
bacterial, viral or fungal organisms.
– High mortality rate
– FDG uptake in the infected tissue.
– The localized FDG uptake may mimic malignant
process.
– Clinical presentation such as fever can help to
differentiate endocarditis from malignant process.

15. Case 4
• 46-year-old male with history of coronary artery
diseases, and systemic sarcoidosis
• Presented to ER with shortness of breath
• Cardiac PET-CT for further evaluation (high fat, high
protein, no carbohydrate diet before the imaging study)

16. Cardiac Sarcoidosis
Short, vertical, and
horizontal axis SPECT
myocardial perfusion
imaging with Tc99m-
tetrofosmin
shows large perfusion
defect in anterior and
lateral wall of the
heart

17. Cardiac Sarcoidosis
On initial PET-CT obtained before the
treatment, there are focal FDG uptakes in
heart and lung. There are diffuse FDG
uptakes in the bone. There are increased
FDG uptake on anterior and lateral aspect of
the heart.
PET-CT done after steroid
treatment shows residual
pulmonary and cardiac FDG
uptake

18. Cardiac sarcoidosis: Inflammatory etiology
• Cardiac sarcoidosis is a granulomatous
diseases, which occurs in 5% of patients with
sarcoidosis.
– Increased FDG activity in the initial stage
due to inflammation, but decreased FDG
activity in later stage due to fibrosis
– Due to variability in FDG uptake, it’s hard to
differentiate malignancy vs sarcoidosis.
Clinical picture helps to diagnose
• Other inflammatory etiology that can mimic
cardiac malignancy includes: pericardiac lymph
node inflammation, myocarditis, and
endocarditis. Curr Cardiol Rep. 2013 Apr; 15(4): 352. SkaliH, et al.

19. Case 5
• 74-year-old male with history of idiopathic
retroperitoneal fibrosis
• Recent finding of multiple pulmonary nodules on CT
• PET-CT was ordered for initial treatment strategy.

20. Aortitis
PET-CT with
attenuation correction
shows increased
metabolic activity
around the aortic arch.
PET-CT without
attenuation correction
also demonstrate
increased metabolic
activity around the
aortic arch

21. Aortitis
• Aortitis is a general term that describes inflammation of
aorta
– Most common causes include infection or connective
tissue disorder
– Increased FDG uptake in the wall of the aorta in
PET-CT
– Localized FDG uptake may mimic malignancy.

22. Increased uptake in ventricle
• New diffuse uptake in ventricles
– Myocardial diseases
– Systemic/pulmonary hypertension
– Valvular heart diseases
– Myopathies
– Malignancy is rare
– Physiologic posterolateral and basal ring uptake
• Often uniformly increased FDG uptake

23. Increased uptake in pericardium:
radiation pericarditis
• FDG activity in pericardium is rare in physiologic state
• Radiation treatment can cause variable FDG uptake
changes in pericardium
• Radiation pericarditis shows diffuse FDG uptake in the
location of radiation port.
• Other post-radiation changes such as radiation
pneumonitis is often found together

24. Reference and suggested readings
• Maurer, A. H., Burshteyn, M., Adler, L. P., & Steiner, R. M. (2011). How to differentiate benign versus malignant cardiac and paracardiac
18F FDG uptake at oncologic PET/CT. Radiographics, 31(5), 1287-1305.
• Nensa, F., Tezgah, E., Poeppel, T. D., Jensen, C. J., Schelhorn, J., Köhler, J., ... & Nassenstein, K. (2015). Integrated 18F-FDG PET/MR
imaging in the assessment of cardiac masses: a pilot study. Journal of Nuclear Medicine, 56(2), 255-260.
• Skali, H., Schulman, A. R., & Dorbala, S. (2013). 18 F-FDG PET/CT for the assessment of myocardial sarcoidosis. Current cardiology
reports, 15(4), 370.
• Rybicki, B. A., Major, M., Popovich Jr, J., Maliank, M. J., & lannuzzi, M. C. (1997). Racial differences in sarcoidosis incidence: a 5-year
study in a health maintenance organization. American journal of epidemiology, 145(3), 234-241.
• Heyer, C. M., Kagel, T., Lemburg, S. P., Bauer, T. T., & Nicolas, V. (2003). Lipomatous hypertrophy of the interatrial septum: a prospective
study of incidence, imaging findings, and clinical symptoms. Chest, 124(6), 2068-2073.
• Kaneta, T., Hakamatsuka, T., Takanami, K., Yamada, T., Takase, K., Sato, A., ... & Yamada, S. (2006). Evaluation of the relationship
between physiological FDG uptake in the heart and age, blood glucose level, fasting period, and hospitalization. Annals of nuclear
medicine, 20(3), 203-208.
• Khandani, A. H., Isasi, C. R., & Blaufox, M. D. (2005). Intra-individual variability of cardiac uptake on serial whole-body 18F-FDG
PET. Nuclear medicine communications, 26(9), 787-791.
• Fujii, H., Ide, M., Yasuda, S., Takahashi, W., Shohtsu, A., & Kubo, A. (1999). Increased FDG uptake in the wall of the right atrium in people
who participated in a cancer screening program with whole-body PET. Annals of nuclear medicine, 13(1), 55-59.
• Yen, R. F., Chen, Y. C., Wu, Y. W., Pan, M. H., & Chang, S. C. (2004). Using 18-fluoro-2-deoxyglucose positron emission tomography in
detecting infectious endocarditis/endoarteritis: A preliminary report1. Academic radiology, 11(3), 316-321.

25. Presenting author
• Il Kyu Oh MS3