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

Table 3.

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

Disease	Clinical indication	Patient preparation	Imaging protocol	Interpretation criteria	Pitfalls	Final report
Retroperitoneal Fibrosis	Diagnosis; Evaluation of disease during/after treatment in patients with normal inflammatory markers and stable residual mass; Evaluation of correct time to proceed to ureteral stent removal; Discrimination between active and residual fibrotic tissue	According to EANM/SNMMI procedural guidelines	Whole body acquisitions (60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)	Qualitative analysis (1) Location Anatomical description of pathologic tissue and its relationships with vascular and ureteral structures (2) Pattern diffuse, segmental, focal (3) Intensity of uptake Score 0: no uptake Score I: uptake < liver; Score II: uptake similar to liver; Score III: uptake > liver Semi-quantitative analysis Limited value for SUV_max or T/B ratios	FP findings in Beam-hardening artifact; Diffuse aortic calcifications FN findings under steroid or immunosuppressive therapy	Presence/absence of uptake; Pattern of uptake; Location; Extent; Intensity of uptake; Possible DD; 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)
Fever of Unknown Origin / Inflammation of Unknown Origin	Evaluation of unknown inflammatory, infective or neoplastic sites; Guide biopsy; Evaluation of therapy efficacy	According to EANM/SNMMI procedural guidelines	Whole body acquisitions (60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)	Qualitative analysis Based on the identification of all sites of pathological tracer uptake	[¹⁸F]FDG is not able to discriminate between infection and inflammation; FN findings in patient under antibiotic treatment or steroid/immunosuppressive therapy FP findings in neoplastic tissues	Presence/absence of uptake; Pattern of uptake; Location; Extent; Intensity of uptake; Possible DD; 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)
Inflammatory Bowel Diseases	Diagnosis in patients with suspected inflammatory bowel diseases in equivocal cases Intestinal and extra-intestinal disease assessment; Evaluation of complications; Early evaluation of therapy efficacy Follow-up and monitoring disease evolution	According to EANM/SNMMI procedural guidelines	Whole body acquisitions 60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)	Qualitative analysis (1) Location Crohn’s Disease: any segment of GI tract; Ulcerative Colitis: mainly involves rectum with a possible extent to proximal parts (2) Pattern diffuse, segmental, focal (3) Intensity of uptake: Diffuse and mild glucose uptake in bowel: negative for inflammatory bowel diseases; Segmental and significant increased uptake in the intestinal tract: positive for inflammatory bowel diseases; Semi-quantitative analysis Bowel SUV_max > than liver is suggestive for inflammatory bowel diseases However, no defined SUV_max cut-off has been identified	FP findings in: Diabetic patients assuming hypoglycemic oral therapy; Diverticulitis; Infectious colitis; Malignancies FN findings in: Disease with a low grade activity; Recent administration of high dose of corticosteroid	Presence of increased glucose uptake in bowel segments and/or in extra-intestinal sites, Pattern of uptake Extent Intensity of uptake; Possible DD; 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)
Systemic sarcoidosis and tubercolosis	Evaluation of disease activity and extent; DD between reversible granuloma from irreversible fibrosis; Diagnosis of occult disease; Evaluation of treatment response; Guide biopsy	According to EANM/SNMMI procedural guidelines	Whole body acquisitions (from vertex to distal extremities of the lower limbs, 60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)	Qualitative analysis Description of lymph nodes (lambda sign), pulmonary, pleural, lacrimal and a salivary glands, brain, musculoskeletal and brain involvement; For assessing myocardial involvement, see Table 1 Semi-quantitative analysis Limited value for SUV_max or T/B ratios	[¹⁸F]FDG is not able to achieve an accurate DD between infections, inflammation and Malignancies (lymphomas)	Description of any site of increased glucose uptake, Pattern of uptake distribution Intensity of uptake; Possible DD; 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)

Disease

Clinical indication

Patient preparation

Imaging protocol

Interpretation criteria

Pitfalls

Final report

Retroperitoneal Fibrosis

Diagnosis;

Evaluation of disease during/after treatment in patients with normal inflammatory markers and stable residual mass;

Evaluation of correct time to proceed to ureteral stent removal;

Discrimination between active and residual fibrotic tissue

According to

EANM/SNMMI procedural guidelines

Whole body acquisitions (60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)

Qualitative analysis

(1) Location

Anatomical description of pathologic tissue and its relationships with vascular and ureteral structures

(2) Pattern

diffuse, segmental, focal

(3) Intensity of uptake

Score 0: no uptake

Score I: uptake < liver;

Score II: uptake similar to liver;

Score III: uptake > liver

Semi-quantitative analysis

Limited value for SUV_max or T/B ratios

FP findings in

Beam-hardening artifact;

Diffuse aortic calcifications

FN findings under

steroid or

immunosuppressive therapy

Presence/absence of uptake;

Pattern of uptake;

Location;

Extent;

Intensity of uptake;

Possible DD;

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)

Fever of Unknown Origin / Inflammation of Unknown Origin

Evaluation of unknown inflammatory, infective or neoplastic sites;

Guide biopsy;

Evaluation of therapy efficacy

According to

EANM/SNMMI procedural guidelines

Whole body acquisitions (60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)

Qualitative analysis

Based on the identification of all sites of pathological tracer uptake

[¹⁸F]FDG is not able to discriminate between infection and inflammation;

FN findings in patient under antibiotic treatment or steroid/immunosuppressive therapy

FP findings in

neoplastic tissues

Presence/absence of uptake;

Pattern of uptake;

Location;

Extent;

Intensity of uptake;

Possible DD;

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)

Inflammatory Bowel Diseases

Diagnosis in patients with suspected inflammatory bowel diseases in equivocal cases

Intestinal and extra-intestinal disease assessment;

Evaluation of complications;

Early evaluation of therapy efficacy

Follow-up and monitoring disease evolution

According to

EANM/SNMMI procedural guidelines

Whole body acquisitions 60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)

Qualitative analysis

(1) Location

Crohn’s Disease: any segment of GI tract;

Ulcerative Colitis: mainly involves rectum with a possible extent to proximal parts

(2) Pattern

diffuse, segmental, focal

(3) Intensity of uptake:

Diffuse and mild glucose uptake in bowel: negative for inflammatory bowel diseases;

Segmental and significant increased uptake in the intestinal tract: positive for inflammatory bowel diseases;

Semi-quantitative analysis

Bowel SUV_max > than liver is suggestive for inflammatory bowel diseases

However, no defined SUV_max cut-off has been identified

FP findings in:

Diabetic patients assuming hypoglycemic oral therapy;

Diverticulitis;

Infectious colitis;

Malignancies

FN findings in:

Disease with a low grade activity;

Recent administration of high dose of corticosteroid

Presence of increased glucose uptake in bowel segments and/or in extra-intestinal sites,

Pattern of uptake

Extent Intensity of uptake; Possible DD;

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)

Systemic sarcoidosis and tubercolosis

Evaluation of disease activity and extent;

DD between reversible granuloma from irreversible fibrosis;

Diagnosis of occult disease;

Evaluation of treatment response;

Guide biopsy

According to

EANM/SNMMI procedural guidelines

Whole body acquisitions (from vertex to distal extremities of the lower limbs, 60’ after i.v. injection of 2.5–3 MBq/Kg of [¹⁸F]FDG)

Qualitative analysis

Description of lymph nodes (lambda sign), pulmonary, pleural, lacrimal and a salivary glands, brain, musculoskeletal and brain involvement;

For assessing myocardial involvement, see Table 1

Semi-quantitative analysis

Limited value for SUV_max or T/B ratios

[¹⁸F]FDG is not able to achieve an accurate DD between infections, inflammation and

Malignancies (lymphomas)

Description of any site of increased glucose uptake,

Pattern of uptake distribution

Intensity of uptake;

Possible DD;

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)

EANM European Association of Nuclear Medicine, 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, DD differential diagnosis, SS systemic sarcoidosis, SNMMI Society of Nuclear Medicine and Molecular Imaging, CT computed tomography, PET/CT positron emission tomography/computed tomography, FP false positive, FN false negative, FU follow-up, GI gastro-intestinal