Table 3.

Overview of the selected studies on the role of positron emission tomography in diagnosing inflammatory bowel disease

Ref.	Year of pub	Journal	n of pts	Indication	Imaging technique	Gold standard	Conclusions
Meisner et al[6]	2007	Inflamm Bowel Dis	12	To identify regions of active inflammation in patients with known and at least moderate UC or CD	18F-FDG-PET/CT	Clinical evaluation including colonoscopy and radiologic imaging	There is high correlation between 18F-FDG-PET activity and clinical disease activity CT is necessary for anatomical identification of different bowel segments in CD patients with small bowel involvement or surgically treated
Das et al[1]	2010	Eur J Nucl Med Mol Imaging	15	To assess the extent and severity of disease in patients with active, mild to moderate UC	18F-FDG-PET/CT colonography	Colonoscopy	18F-FDG-PET/CT colonography is a useful tool for the assessment of extent and activity of UC
Ahmadi et al[7]	2010	Inflamm Bowel Dis	41	To identify disease activity in patients with known or suspected active CD of the small intestine To find out possible risk factors for therapy failure	Localized 18F-FDG-PET/CTe	NA	18F-FDG-PET scan does not increase CTe in detection of active disease A low 18F-FDG uptake in at least one small bowel segment, resulted to be pathological on CTe, represent a risk factor for medical treatment failure
Groshar et al[20]	2010	J Nucl Med	28	To evaluate disease activity in patients with known or suspected active CD	18F-FDG-PET/CTe	NA	SUVmax correlates well with CTe findings of active disease. It might be a reliable objective method for quantifying CD’s activity
Shyn et al[21]	2010	J Nucl Med	13	To detect active disease and assess severity of inflammation in patients with clinically suspected active CD	18F-FDG-PET/CTe	Histology after surgery or after biopsy performed during endoscopy	18F-FDG-PET added to CTe may improve the detection of active disease
Holtmann et al[2]	2012	Dig Dis Sci	43	To detect bowel segments with active CD	18F-FDG-PET	Endoscopy for distal ileum and colon, hydro-MRI for proximal ileum	18F-FDG-PET diagnostic performance in the detection of bowel segments with active disease is high. Compared to 18F-FDG-PET, hydro-MRI shows much lower sensitivity but higher specificity for all colon segments, higher sensitivity and the same specificity for terminal ileum and same performance for proximal ileum. Both methods seem to have high accuracy in strictures detection and characterization of their nature
Lenze et al[4]	2012	Inflamm Bowel Dis	30	To detect CD strictures and differentiate inflammatory from fibrotic ones	18F-FDG-PET/CT enteroclysis, MR enteroclysis, transabdominal ultrasound	Endoscopy + hystology	All the three studied techniques have good strictures detection rates relating to the gold standard, but none of them can accurately differentiate strictures’ nature. However, a combination of methods allows the detection of all strictures requiring surgery
Catalano et al[5]	2016	Radiology	19	To differentiate fibrotic from inflammatory strictures in CD patients	18F-FDG-PET/MR enterography	Post-surgical histology	18F-FDG-PET/MR enterography offers valid biomarkers for stricture evaluation

SPECT: Single photon emission tomography; CD: Crohn’s disease; UC: Ulcerative colitis; NA: Not available; ¹⁸F-FDG-PET: Positron emission tomography with ¹⁸F-Fluorodehoxiglucose; CT: Computed tomography; MRI: Magnetic resonance imaging; SUV: Standardized uptake value; CTe: CT esensitivity; pts: Patients.