Emerging role of intestinal ultrasound in IBD management

Intestinal ultrasound (IUS) is increasingly acknowledged as a valid point-of-care tool that objectively assesses inflammatory bowel disease (IBD) activity. At the International Digestive Disease Forum (IDDF) 2023, Professor Christian Maaser of the Municipal Hospital of Lüneburg, Lüneburg, Germany, discussed the emerging role of IUS in IBD management. He also shared practical tips in using IUS, including how and when to use it as well as what to look for while performing IUS.

Advantages of point-ofcare IUS in IBD care
“IBD is a chronic illness requiring constant monitoring to ensure that disease activity is controlled and responsiveness to current therapies is retained,” said Maaser.

Recent clinical guidelines recognize the value of IUS as a noninvasive method in IBD management. For instance, joint consensus guidelines of the European Crohn’s and Colitis Organisation (ECCO) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) made several recommendations in favour of using IUS in Crohn’s disease (CD) management, from initial diagnosis to treatment response monitoring as well as for symptomatic bowel disease investigations, relapse assessments, and as a noninvasive option to detect postoperative recurrence (eg, after small bowel resection). [J Crohns Colitis 2019;13:144-164]

As a cross-sectional imaging procedure, IUS requires no or minimal bowel preparation, does not expose patients to radiation, can be performed by treating physicians in a point-of-care setting, and can immediately deliver findings to both physicians and patients. “Since it is a widely available and safe imaging modality [ie, no radiation exposure] with low costs and prompt results, it can facilitate timely therapy optimization and repeated evaluations to monitor lesions without being as time-consuming [eg, CT scan or MRI] or invasive [eg, endoscopy] as other imaging modalities,” Maaser stressed. [GE Port J Gastroenterol 2021;29:223-239; J Crohns Colitis 2019;13:144-164]

“It is practical to have IUS in IBD clinics since it provides real-time feedback on patients’ disease activity, assisting physicians in clinical decision-making and helping patients understand their disease and treatment options better, which may eventually improve treatment adherence and clinical outcomes,” he added. [Aliment Pharmacol Ther 2021;54:652-666]

IUS in IBD: When and what to look for?
“For trained physicians, IUS is easy to use and IBD assessment can be completed within a few minutes since they know what they are looking for,” opined Maaser. Aside from disease activity, IUS also shows the extent of IBD as well as its location, severity and presence of complications. [GE Port J Gastroenterol 2021;29:223-239; J Crohns Colitis 2020;1:465-479; Nat Rev Gastroenterol Hepatol 2021;18:209-210]

“When performing IUS, it is important to know anatomical landmarks on the patient’s abdomen, and to perform the procedure in an organized manner to ensure complete bowel examination,” he noted.

“IUS may be used to detect characteristic IBD abnormalities, namely, bowel wall thickening with increased vascularization and maintenance or loss of wall stratification in CD,” he explained. (Figure 1)

“IUS may also be used to detect IBD complications,” noted Maaser. “For instance, real-time observation of bowel movement during IUS allows visualization of strictures, which become obvious when luminal contents are unable to pass through the area with bowel wall thickening. Other IBD complications that can be detected with IUS include abscesses and fistulas.” (Table)

“In our centre, IUS is performed in every patient with active IBD, and IUS follow-ups are scheduled every 4–6 weeks or 3 months [depending on disease severity], 6 months along with endoscopy, and 1 year,” he said. “Early IBD control is important, and it is not desirable to waste half a year [for endoscopy results] before therapy is optimized.” (Figure 2)

“Repeated IUS assessments are crucial because while IBD patients may be asymptomatic, they may actually be suboptimally treated. Clinical remission in IBD may not be predictive of actual disease activity and may not necessarily mean transmural healing in CD or mucosal healing in ulcerative colitis,” he explained. [United European Gastroenterol J 2023;11:51-59; Therap Adv Gastroenterol 2021;14:17562848211016259; World J Gastroenterol 2013;19:7552-7560; J Clin Med 2021;10:5551]

IUS in IBD: Clinical evidence
In the last decade, there has been growing interest in understanding and defining the role of IUS in IBD diagnosis, disease activity monitoring and treatment response assessments. Several expert reviews and consensus statements on the role of IUS in IBD have been published to standardize cross-sectional imaging reports, homogenize disease activity definitions and criteria, and provide guidance on optimal timing of assessments. [J Crohns Colitis 2021;15:609-616; J Crohns Colitis 2022;16:523-543; J Crohns Colitis 2022;16:554-580]

“IUS is also increasingly used in clinical studies for endpoint assessments, such as for monitoring IBD activity in response to therapy,” he noted.

STARDUST: Early IUS response to ustekinumab
STARDUST is an international, multicentre, phase IIIb, interventional, randomized controlled trial that compared treat-to-target and standard- of-care strategies in patients with moderate-to-severe CD who received ustekinumab. In a substudy of STARDUST (n=77), the effect of ustekinumab was assessed using IUS. [Clin Gastroenterol Hepatol 2023;21:153-163.e12; Stelara Hong Kong Prescribing Information; Clin Gastroenterol Hepatol 2023;21:153-163.e12]

IUS response was seen as early as 4 weeks after ustekinumab initiation, with progressive improvements through week 48. At week 48, IUS response and transmural remission rates were 46.3 percent and 24.1 percent, respectively. The most robust responses to ustekinumab therapy were observed in the colon (62.5 percent for IUS response at week 48 vs 39.5 percent for the terminal ileum) and in biologic-naive patients (59.1 percent vs 37.5 percent for patients with prior exposure to one biologic therapy). (Figure 3) These robust results support the use of IUS to complement biomarker and symptom assessments in patients with CD, which may help provide a more complete clinical depiction of therapeutic responses. [Clin Gastroenterol Hepatol 2023;21:153-163.e12]

Summary
“At our centre, we recognize the value of IUS in routine IBD management because it is noninvasive, easy to perform, and has advantages over other imaging modalities in disease activity assessment,” said Maaser. “IUS is gradually changing the landscape of IBD management in terms of diagnosis, disease activity monitoring and repeated assessments of treatment response, and has thus become increasingly used in both routine clinical care and clinical trial settings.