Prediction of the Need for Surgical Intervention in Obstructive Crohn's Disease by ¹⁸F-FDG PET/CT

Abstract

We preoperatively determined the accuracy of 18 F-FDG PET/CT for differentiating fixed muscle hypertrophy and fibrotic stenoses from acute transmural inflammatory stenoses in patients with Crohn's disease (CD) scheduled to undergo surgical resection for obstructive symptoms. Methods: Seventeen patients with known CD prospectively underwent 18 F-FDG PET/CT before already-planned surgery for obstructive symptoms. Image interpretation was by consensus of 2 readers with knowledge of patient participation in the study but not of other clinical history. Lesions were qualitatively graded on a 5-point scale for the presence of increased 18 F-FDG uptake consistent with active inflammation. Maximum lean standardized uptake value (SUL max ) was determined for lesions scored 1 or more. Imaging results were compared with the pathologic grading of inflammation and predominant histopathologic subtype for each patient's surgical specimen, whether mainly inflammation, fibrosis, or muscle hypertrophy. Results: Thirteen of the 17 patients underwent surgery (median, 28 d after PET/CT; range, 2-148 d), and 12 of these 13 had histopathologic correlation. Despite the predominant histopathologic subtype (inflammation, 5; fibrosis, 4; and muscle hypertrophy, 3), acute and chronic inflammation, fibrosis (median, 50%; range, 40%290%), and muscle hypertrophy (median, 20-fold thickening; range, 9-to 40-fold thickening) were found in all patients. SUL max was significantly higher in severe than in mild-to-moderate chronic inflammation (8.2 6 2.8 vs. 4.7 6 2.5, P 5 0.04). No patient with predominantly fibrosis or muscle hypertrophy (n 5 7) had an SUL max greater than 8. Visually, 10 of 12 patients on PET/CT were considered to have active inflammation of the bowel. Conclusion: Patients with CD who undergo surgery for obstructive symptoms have histopathologically mixed findings of inflammation, fibrosis, and muscle hypertrophy. Qualitative PET interpretations were quite sensitive, but additional semiquantitative analyses using SUL max helped identify patients with active inflammation. This information may be beneficial for referring gastroenterologists considering medical therapy versus surgery for patients with CD who present with obstructive symptoms.

The Role of Positron Emission Tomography in Inflammatory Bowel Disease

“…There is still limited evidence on these imaging methods both in adult and in pediatric IBO patients, but there is a good correlation between PET findings and disease activity (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

“…The accuracy of FDG-PET/CT for differentiating fixed muscle hypertrophy and fibrotic stenoses from acute transmural inflammatory stenoses in patients with CD scheduled to undergo surgical resection for obstructive symptoms was also assessed; qualitative PET interpretations and, in particular, semiquantitative analyses helped to identify patients with active inflammation (17).…”

Role of 18F-fluorodeoxyglucose Positron Emission Tomography in the Monitoring of Inflammatory Activity in Crohnʼs Disease

“…9/13 patients who completed PET scanning both at baseline and a median [range] of 12 [11][12][13][14][15][16][17][18] weeks after initiation of anti-TNF treatment had favourable clinical responses 27 (median [range] responder ΔHBI = 5 [3][4][5][6][7][8][9]; non-responder ΔHBI = 1[-1-2]), (Table 1). …”

“…A target dose of 185MBq of 18 F-FDG in 10ml of normal saline was administered intravenously, followed by a saline flush. The patients then were asked to rest semi-recumbently in a quiet room, and, in keeping with similar protocols in the literature 10,11,[21][22][23][24] , they were given between 800-1200ml of an oral bowel distension, agent. 2.5% mannitol was used according to local protocol in our institution.…”

“…The majority of these early studies characterized lesions using maximal Standardised Uptake Values (SUV) in involved gut segments. More recent reports also have explored composite measures that additionally reflect signal volume 11,12 . The potential of FDG-PET to demonstrate changes in lesion activity over time was first suggested in a report which included 3 CD patients 13 .…”