. 2021 Jun 1;9(4):283–297. doi: 10.1007/s40336-021-00435-y

Table 1.

Summary table on [¹⁸F]FDG PET/CT imaging in cardiovascular infections/inflammations

Disease	Clinical indication	Patient preparation	Imaging protocol	Interpretation criteria	Pitfalls	Final report
Large vessel vasculitis	Diagnosis Therapy assessment	According to EANM/ SNMMI/PIG procedural recommendations	Whole body acquisitions (60’ after i.v. injection of 2–3 MBq/Kg of [¹⁸F]FDG) Late segmental acquisitions (90’-120’ p.i.) of suspected area	Qualitative analysis (1) Location Aorta and its major branches (2) Pattern Linear/segmental uptake large vessel vasculitis;focal uptake: atherosclerotic plaque (3) Intensity of uptake: Grade 0: no uptake; Grade I: less than liver; Grade II: similar to the liver; Grade III: higher than liver Grade ≥ II: large vessel vasculitis Semi-qualitative analysis Limited value for SUV_max or TVS	Steroid treatment could reduce accuracy FP results in in atherosclerosis	Presence/absence of vascular uptake Pattern of uptake Location and extent Intensity of uptake Comparison with previous [¹⁸F]FDG PET/CT if performed Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)
Vascular graft infections	Identification of infection and evaluation of its extent Identification of septic embolism Therapy assessment	According to EANM/SNMMI procedural guidelines EANM/EACVI procedural recommendations on 4Is CV imaging	Whole body acquisitions (60’ after i.v. injection of 2.5–5.0 MBq/Kg of [¹⁸F]FDG) Steps: 1.5–3 min for bed position; Late segmental acquisitions (90’-120’ p.i.) of suspected area Administration of iodinated contrast may be useful to obtain a diagnostic CT scan	Qualitative analysis (1) Location Aorta and its major branches or peripheral grafts (2) Pattern Intense and focal and uptake, with dotted configuration: graft infection Mild and homogeneous uptake: non-infected graft (3) Intensity of uptake: Grade 0 (similar to the background): no infection; Grade I (similar to inactive muscles and fat): low [¹⁸F]FDG uptake; Grade II (≥ than inactive muscles and fat): moderate [¹⁸F]FDG uptake; Grade III (≤ than the physiologic urinary uptake by the bladder): strong [¹⁸F]FDG uptake; Grade IV (comparable with bladder uptake): very strong [¹⁸F]FDG uptake Focal uptake + Grade > II: vascular graft infections Semi-qualitative analysis Limited value for SUV_max or T/B ratios	Physiologic [¹⁸F]FDG uptake due to post-surgical inflammation; Venous thrombosis; Vasculitis; Retroperitoneal fibrosis; [¹⁸F]FDG-avid processes that are close to the graft	PET assessment Description of pattern and intensity; Location; Evaluation of extent of uptake; Description of eventual septic emboli CT assessment Description of graft’s border (regular vs irregular); Evaluation of other radiologic signs of infection (graft dislocation, presence of gas/fluid collections) Comparison with previous [¹⁸F]FDG PET/CT if performed; Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)
Infective endocarditis	Suspected PVE; Identification of septic embolisms, mycotic aneurysms, spread of infection, POE in both PVE and NVE	According to EANM/EACVI procedural recommendations: High-fat–enriched diet lacking carbohydrates for 12–24 h prior to the scan; Fasting: 12–18 h; (optional) iv heparin of 50 IU/kg 15 min prior to [¹⁸F]FDG injection	Whole body acquisitions (60’-90’after i.v. injection of 2.5–5.0 MBq/Kg of [¹⁸F]FDG) Steps: 2 min for bed position; Optional: gated PET/CTA	Qualitative analysis (1) Location Intravalvular/valvular/ perivalvular (2) Pattern focal and non homogeneous: infection (3) Intensity of uptake high uptake: infection Semi-qualitative analysis Limited value for SUV_max or prosthesis/background ratios	Incomplete myocardial suppression of [¹⁸F]FDG; Lipomatous hypertrophy of the interatrial septum; [¹⁸F]FDG-avid processes close to the graft but not involving the device; Post-surgical sterile inflammation; Primary cardiac tumours or metastasis; Libman-Sacks endocarditis	Typical findings Presence of focal, heterogeneous, valvular/peri-valvular [¹⁸F]FDG uptake persisting on NAC images; High [¹⁸F]FDG signal in the absence of prior use of surgical adhesives; Presence of focal [¹⁸F]FDG uptake in organs with low background uptake: septic embolism, mycotic aneurysms or POE Atypical findings Diffuse, homogeneous, valvular [¹⁸F]FDG uptake that is absent on NAC images; Low [¹⁸F]FDG signal Comparison with previous [¹⁸F]FDG PET/CT if performed; Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)
Cardiac implantable electronic device infection	Suspected cardiac implantable electronic device infection; Definition of the extent of infection; Positive blood culture in a patient with cardiac implantable electronic device	Same protocol described for infective endocarditis	Same protocol described for infective endocarditis; Late PET acquisitions might be useful in case of persistent high blood signal on PET images acquired at 1 h p.i	Qualitative analysis (1) Location Pocket/generator (superficial or deep) Leads (intravascular or intracardiac portion) (2) Pattern Focal or linear signal persisting on NAC images: infection (3) Intensity of uptake High uptake: infection Semi-qualitative analysis Limited value for SUV_max or T/B ratios	Same pitfalls described for infective endocarditis; Moderate uptake can be found up to 2 months after cardiac implantable electronic device implantation	Focal or linear uptake located on or alongside a lead and persisting on NAC images: infection; Multiple focal spots in the lungs: septic pulmonary emboli; Describe POE; Comparison with previous [¹⁸F]FDG PET/CT if performed; Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)
Left ventricular assist device associated infections	Suspected left ventricular assist device associated infections; Evaluation of the extent; Positive blood culture in a patient with left ventricular assist device	Same protocol described for infective endocarditis	Same protocol described for infective endocarditis	Qualitative analysis (1) Location Driveline exit site/ driveline within the subcutaneous tissue/pump/inflow cannula/outflow cannula (2) Pattern Focal or linear signal persisting on NAC images: infection (3) Intensity of uptake High uptake: infection Semi-qualitative analysis Limited value for SUV_max or T/B ratios	The analysis of the FDG signal in the pump and cannula are more complex because of the artifacts caused by the device	Presence/absence of uptake Pattern description and location Extent Intensity of uptake The persistence of [¹⁸F]FDG uptake on NAC and its association with infiltration around the pump on the non-enhanced CT: infection; Comparison with previous [¹⁸F]FDG PET/CT if performed; Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)
Cardiac sarcoidosis	Suspected cardiac sarcoidosis; Therapy assessment	Delaying steroid treatment initiation after the baseline scan is strongly recommended	Same protocol described for infective endocarditis	Qualitative analysis (1) Location Left or right cameras (2) Pattern No [¹⁸F]FDG uptake/diffuse (homogeneus) [¹⁸F]FDG uptake/ isolated [¹⁸F]FDG uptake on lateral wall uptake + normal perfusion + no LGE at CMR: No cardiac sarcoidosis; No [¹⁸F]FDG uptake + small perfusion defect + one focal area of LGE or Focal area of [¹⁸F]FDG uptake + normal perfusion + one focal area of LGE: possible cardiac sarcoidosis (50–90%); No [¹⁸F]FDG uptake + multiple non-contiguous areas of perfusion defect / + typical LGE or Focal [¹⁸F]FDG uptake/focal on diffuse [¹⁸F]FDG uptake + resting perfusion defect + typical LGE: probable cardiac sarcoidosis (50–90%) Focal area + extracardiac findings + normal perfusion + typical LGE: active cardiac sarcoidosis (> 90%); Focal on diffuse [¹⁸F]FDG uptake + perfusion defect + typical LGE: active inflammation with scar; Focal area of [¹⁸F]FDG uptake in a normally perfused area + perfusion defect in another area + typical LGE: inactive scar + inflammation (or FP [¹⁸F]FDG uptake) in different segments (3) Intensity of uptake High uptake: higher probability of cardiac sarcoidosis Semi-qualitative analysis SUV_max is reliable for both diagnosis and therapy efficacy assessment	Same pitfalls previously described	Description of the findings for both qualitative and semi-quantitative point of view; Possible differential diagnosis; Comparison to previous ¹⁸F-FDG PET/CT, if performed; Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Disease

Clinical indication

Patient preparation

Imaging protocol

Interpretation criteria

Pitfalls

Final report

Large vessel vasculitis

Diagnosis

Therapy assessment

According to EANM/ SNMMI/PIG procedural recommendations

Whole body acquisitions (60’ after i.v. injection of 2–3 MBq/Kg of [¹⁸F]FDG)

Late segmental acquisitions (90’-120’ p.i.) of suspected area

Qualitative analysis

(1) Location

Aorta and its major branches

(2) Pattern

Linear/segmental uptake large vessel vasculitis;focal uptake: atherosclerotic plaque

(3) Intensity of uptake:

Grade 0: no uptake;

Grade I: less than liver;

Grade II: similar to the liver;

Grade III: higher than liver

Grade ≥ II: large vessel vasculitis

Semi-qualitative analysis

Limited value for SUV_max or TVS

Steroid treatment could reduce accuracy

FP results in in atherosclerosis

Presence/absence of vascular uptake

Pattern of uptake

Location and extent

Intensity of uptake

Comparison with previous [¹⁸F]FDG PET/CT if performed

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Vascular graft infections

Identification of infection and evaluation of its extent

Identification of septic embolism

Therapy assessment

According to

EANM/SNMMI procedural guidelines

EANM/EACVI procedural recommendations on 4Is CV imaging

Whole body acquisitions (60’ after i.v. injection of 2.5–5.0 MBq/Kg of [¹⁸F]FDG)

Steps: 1.5–3 min for bed position;

Late segmental acquisitions (90’-120’ p.i.) of suspected area

Administration of iodinated contrast may be useful to obtain a diagnostic CT scan

Qualitative analysis

(1) Location

Aorta and its major branches or peripheral grafts

(2) Pattern

Intense and focal and uptake, with dotted configuration: graft infection

Mild and homogeneous uptake: non-infected graft

(3) Intensity of uptake:

Grade 0 (similar to the background): no infection;

Grade I (similar to inactive muscles and fat): low [¹⁸F]FDG uptake;

Grade II (≥ than inactive muscles and fat): moderate [¹⁸F]FDG uptake;

Grade III (≤ than the physiologic urinary uptake by the bladder): strong [¹⁸F]FDG uptake;

Grade IV (comparable with bladder uptake): very strong [¹⁸F]FDG uptake

Focal uptake + Grade > II: vascular graft infections

Semi-qualitative analysis

Limited value for SUV_max or T/B ratios

Physiologic [¹⁸F]FDG uptake due to post-surgical inflammation;

Venous thrombosis;

Vasculitis;

Retroperitoneal fibrosis;

[¹⁸F]FDG-avid processes that are close to the graft

PET assessment

Description of pattern and intensity;

Location;

Evaluation of extent of uptake;

Description of eventual septic emboli

CT assessment

Description of graft’s border (regular vs irregular);

Evaluation of other radiologic signs of infection (graft dislocation, presence of gas/fluid collections)

Comparison with previous [¹⁸F]FDG PET/CT if performed;

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Infective endocarditis

Suspected PVE;

Identification of septic embolisms, mycotic aneurysms,

spread of infection, POE in both PVE and NVE

According to

EANM/EACVI procedural recommendations:

High-fat–enriched diet lacking carbohydrates for 12–24 h prior to the scan;

Fasting: 12–18 h;

(optional) iv heparin of 50 IU/kg 15 min prior to [¹⁸F]FDG injection

Whole body acquisitions (60’-90’after i.v. injection of 2.5–5.0 MBq/Kg of [¹⁸F]FDG)

Steps: 2 min for bed position;

Optional: gated PET/CTA

Qualitative analysis

(1) Location

Intravalvular/valvular/

perivalvular

(2) Pattern

focal and non homogeneous: infection

(3) Intensity of uptake

high uptake: infection

Semi-qualitative analysis

Limited value for SUV_max or prosthesis/background ratios

Incomplete myocardial suppression of [¹⁸F]FDG;

Lipomatous hypertrophy of the interatrial septum;

[¹⁸F]FDG-avid processes close to the graft but not involving the device;

Post-surgical sterile inflammation;

Primary cardiac tumours or metastasis;

Libman-Sacks endocarditis

Typical findings

Presence of focal, heterogeneous, valvular/peri-valvular [¹⁸F]FDG uptake persisting on NAC images;

High [¹⁸F]FDG signal in the absence of prior use of surgical adhesives;

Presence of focal [¹⁸F]FDG uptake in organs with low background uptake: septic embolism, mycotic aneurysms or POE

Atypical findings

Diffuse, homogeneous, valvular [¹⁸F]FDG uptake that is absent on NAC images;

Low [¹⁸F]FDG signal

Comparison with previous [¹⁸F]FDG PET/CT if performed;

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Cardiac implantable electronic device infection

Suspected cardiac implantable electronic device infection;

Definition of the extent of infection;

Positive blood culture in a patient with cardiac implantable electronic device

Same protocol described for infective endocarditis

Same protocol described for infective endocarditis;

Late PET acquisitions might be useful in case of persistent high blood signal on PET images acquired at 1 h p.i

Qualitative analysis

(1) Location

Pocket/generator (superficial or deep)

Leads (intravascular or intracardiac portion)

(2) Pattern

Focal or linear signal persisting on NAC images: infection

(3) Intensity of uptake

High uptake: infection

Semi-qualitative analysis

Limited value for SUV_max or T/B ratios

Same pitfalls described for infective endocarditis;

Moderate uptake can be found up to 2 months after cardiac implantable electronic device implantation

Focal or linear uptake located on or alongside a lead and persisting on NAC images: infection;

Multiple focal spots in the lungs: septic pulmonary emboli;

Describe POE;

Comparison with previous [¹⁸F]FDG PET/CT if performed;

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Left ventricular assist device associated infections

Suspected left ventricular assist device associated infections;

Evaluation of the extent;

Positive blood culture in a patient with left ventricular assist device

Same protocol described for infective endocarditis

Qualitative analysis

(1) Location

Driveline exit site/ driveline within the subcutaneous tissue/pump/inflow cannula/outflow cannula

(2) Pattern

Focal or linear signal persisting on NAC images: infection

(3) Intensity of uptake

High uptake: infection

Semi-qualitative analysis

Limited value for SUV_max or T/B ratios

The analysis of the FDG signal in the pump and cannula are more complex because of the artifacts caused by the device

Presence/absence of uptake

Pattern description and location

Extent

Intensity of uptake

The persistence of [¹⁸F]FDG uptake on NAC and its association with infiltration around the pump on the non-enhanced CT: infection;

Comparison with previous [¹⁸F]FDG PET/CT if performed;

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

Cardiac sarcoidosis

Suspected cardiac sarcoidosis;

Therapy assessment

Delaying steroid treatment initiation after the baseline scan is strongly recommended

Same protocol described for infective endocarditis

Qualitative analysis

(1) Location

Left or right cameras

(2) Pattern

No [¹⁸F]FDG uptake/diffuse (homogeneus) [¹⁸F]FDG uptake/ isolated [¹⁸F]FDG uptake on lateral wall uptake + normal perfusion + no LGE at CMR: No cardiac sarcoidosis;

No [¹⁸F]FDG uptake + small perfusion defect + one focal area of LGE

Focal area of [¹⁸F]FDG uptake + normal perfusion + one focal area of LGE: possible cardiac sarcoidosis (50–90%);

No [¹⁸F]FDG uptake + multiple non-contiguous areas of perfusion defect / + typical LGE

Focal [¹⁸F]FDG uptake/focal on diffuse [¹⁸F]FDG uptake + resting perfusion defect + typical LGE: probable cardiac sarcoidosis (50–90%)

Focal area + extracardiac findings + normal perfusion + typical LGE: active cardiac sarcoidosis (> 90%);

Focal on diffuse [¹⁸F]FDG uptake + perfusion defect + typical LGE: active inflammation with scar;

Focal area of [¹⁸F]FDG uptake in a normally perfused area + perfusion defect in another area + typical LGE: inactive scar + inflammation (or FP [¹⁸F]FDG uptake) in different segments

(3) Intensity of uptake

High uptake: higher probability of cardiac sarcoidosis

Semi-qualitative analysis

SUV_max is reliable for both diagnosis and therapy efficacy assessment

Same pitfalls previously described

Description of the findings for both qualitative and semi-quantitative point of view;

Possible differential diagnosis;

Comparison to previous ¹⁸F-FDG PET/CT, if performed;

Time between injection and image acquisition (in order to better compare SUV_max of basal and FU studies)

EANM European Association of Nuclear Medicine, SNMMI Society of Nuclear Medicine and Molecular Imaging, PIG PET Interest Group, i.v. intra-venous, MBq Mega Bequerel, Kg Kilograms, [¹⁸F]FDG 18Fluorine fluorodeoxyglucose, p.i. post-injection, SUV_max standardized uptake value, T/B target/background, FU follow-up, PVE prosthetic valve endocarditis, NVE native valve endocarditis, POE portal of entry, NAC non-attenuated CT, TVS total vascular score, FP false positive, CT computed tomography, PET/CT positron emission tomography/computed tomography, VGI vascular graft infections, CTA computed tomography angiography, LGE late Gadolinium enhancement, CMR cardiac magnetic resonance