The use of FDG-PET/CT on patients with obstructive Crohn’s disease can provide physicians with information about whether surgical or medical therapy is the preferred treatment option, according to a study in the November issue of the Journal of Nuclear Medicine.
Heather A. Jacene, MD, and colleagues from the division of nuclear medicine, department of radiology and radiological science at Johns Hopkins University School of Medicine in Baltimore analyzed 17 patients with Crohn’s disease in a prospective study. The 17 patients underwent FDG-PET/CT before already planned surgery for obstructive symptoms.
After an FDG-uptake phase of approximately 60 minutes, the patients underwent a combined PET/CT scan from the mid-thorax to pelvis. A non-contrast-enhanced CT scan was obtained first, with a 4-slice multidetector helical scanner.
After the PET/CT scan, the researchers reported that eight patients also received 120 mL of Omnipaque 350 and underwent venous phase intravenous contrast-enhanced CT. Images were obtained from the mid-thorax to pelvis.
All FDG-PET/CT and intravenous contrast-enhanced CT scans were reviewed in consensus by two readers on a Xeleris workstation (GE Healthcare). Images were viewed to find FDG uptake in the abdomen or pelvis, which could have represented active bowel inflammation. Images were also viewed with the secondary objective of determining whether semiquantitative analysis of FDG uptake could be used as a measure of inflammation.
PET/CT was able to identify 33 lesions in the abdomen that potentially represented active bowel inflammation. All 17 patients had at least one lesion and the researchers found 18 lesions that were abnormal and five more that were probably abnormal.
For the eight patients who had both PET/CT and contrast-enhanced PET/CT, the addition of IV contrast didn’t result in significant alterations of the interpretation of PET/CT.
According to the investigators, a semiquantitative analysis of PET found that cutoff values of eight for the maximum lean standardized uptake value (SUV) and 223.6 for total inflammation value were optimal for distinguishing inflammation and fibrosis or hypertrophy in the bowel.
For maximum lean SUV greater than eight, the authors wrote that the sensitivity for detecting active inflammation of the bowel was 60 percent, specificity was 100 percent, positive predictive value was 100 percent, negative predictive value was 78 pecent and accuracy was 83 percent. For total inflammation value greater than 223.6, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy was 60 percent, 71 percent, 71 percent, 60 percent and 67 percent, respectively.
No patient with predominantly fibrosis or muscle hypertrophy had a maximum lean SUV greater than eight. Visually, 10 of 12 patients on PET/CT were considered to have active inflammation of the bowel.
Jacene and colleagues concluded that qualitative PET was “quite sensitive” to Crohn’s disease and that additional semiquantitative analysis using maximum lean SUV helped identify patients with active inflammation. This information should help referring gastroenterologists when weighing therapy versus surgery as treatment options when presented with Crohn’s disease patients with obstructive symptoms, the authors noted.