Unveiling the superior diagnostic efficacy of double-balloon endoscopy compared to small intestine dual-energy CT enterography in small bowel Crohn’s disease
Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects the entire gastrointestinal tract, characterized by its progressive and destructive nature. The segmental transmural lesions associated with CD can lead to recurrent abdominal pain, diarrhoea, intestinal obstruction, and perianal lesions, among other clinical manifestations . According to the existing literature, the surgical risks at 1 year, 5 years, and 10 years following the diagnosis of CD are 16.3%, 33.3%, and 46.6%, respectively . Furthermore, life-threatening adverse events, including gastrointestinal bleeding and intestinal perforation, may occur . Thus, an accurate diagnosis of CD is essential to prevent the onset of adverse events. The diagnosis of CD currently lacks a definitive gold standard, requiring a comprehensive strategy that integrates clinical assessment, laboratory testing, imaging, endoscopy, and histopathological analysis. While pathological evaluation is central to diagnosing CD, practical issues such as sampling limitations and patient cooperation can complicate its application. Ulcers, a dominant manifestation of CD, can occur in any part of the gastrointestinal tract, including the small intestine , and magnetic resonance enterography (MRE), diffusion weighted imaging (DWI), and endoscopy can detect the intestinal mucosal one . After penetrating the intestinal wall, ulcers may lead to the formation of fistulas that connect the intestine with other organs. Following the fistula formation, abscesses may develop, especially in the perianal region . The chronic inflammation finally may result in intestinal stenosis. Within the first 10 years after initial diagnosis, nearly 35% of cases will lead to intestinal stenosis . However, the detection of complications in CD, such as stenosis, fistulas, and perianal lesions, may be more challenging. The efficacy of MRE on CD complications was controversial , and abdominal CT and ultrasound seem to be valid . Consequently, there is a pressing need for a diagnostic method for CD and its complications that is fast, easy to use, and reliable. Virtual Monoenergetic Imaging (VMI) using Dual-energy computed omography enterography (DECTE) has recently gained prominence for evaluating IBD . DECTE is an imaging technique based on two different energy settings for data acquisition and has been widely used in IBD. Images were reconstructed at single-keV energies (ranging from 40 to 200 keV). This technique offers enhanced sensitivity and precision in detecting subtle contrast differences compared with conventional Computed Tomography (CT) . VMI at low keV values (< 60 keV) enhances the visualisation of contrast-enhanced lesions, which aids in diagnosing and assessing CD activity . In addition, DECTE reduces the volume of the intravenous contrast medium required, making it suitable for patients with compromised renal function . DECTE provides clearer visualization of morphological changes and demonstrates greater sensitivity in identifying subtle differences in contrast enhancement . For instance, in diagnosing CD, DECTE manifests as characteristic features such as mural hyperenhancement, bowel wall thickening, and mucosal hyperenhancement. It is particularly sensitive to the stenosis complications of CD (wall thickening) . Additionally, DECTE can assess the location of fistulas. The VMI 40 keV enhances the detection capability of fistulas, aiding surgeons in making well-informed preoperative plans for managing CD fistulas . Approximately 70–80% of CD patients involve small bowel lesions, with 30% presenting as isolated small bowel CD . Due to the unique anatomical structure and technical limitations, the diagnosis and evaluation of isolated small intestinal involvement in CD present challenges for gastroenterologists. Double-balloon endoscopy (DBE) introduced by Yamamoto et al. (2001), is effective for both diagnostic and therapeutic purposes, demonstrating high efficacy and safety on small bowel lesions . For patients with confirmed small bowel CD, DBE serves as a valuable tool for assessing disease activity and guiding treatment . This study aimed to compare the diagnostic efficacy of small intestine DECTE and DBE in Crohn’s disease by evaluating their performance in detecting stenosis, fistulas, and ulcers; diagnosing CD across different clinical manifestations; and assessing disease activity in various inflammatory states.   Patients At the Endoscopic Centre of the First Affiliated Hospital of Soochow University, patients with suspicious small intestinal disease who underwent DBE between 1 July 2016 and 1 November 2023 were included initially. The inclusion criteria were as follows: (1) Diagnosis of CD ; (2) Undergoing both DECTE and DBE within 3 months; and (3) availability of complete data from DECTE, DBE, and clinical assessments. The exclusion criteria were as follows: (1) Pathological results indicating conditions other than CD or inconclusive diagnoses, (2) incomplete data, and (3) the period between DBE and DECTE > 3 months. This study was reviewed and approved by the Medical Ethics Committee of the First Affiliated Hospital of Soochow University (Approval No. 2024–249). DECTE Preparation Patients were instructed to follow a liquid or semi-liquid diet the day before DECTE. Patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water twice on the night before examination, and on the day of examination respectively, until a clear, watery stool was obtained. One hour before the scan, patients ingested 2000 ml of 2.5% isotonic mannitol solution at five 10-min intervals. An additional 300 ml of the solution was used to fill the stomach and the upper jejunum. To suppress intestinal motility, anisodamine (10 mg) was administered intramuscularly 10 min before scanning. Scanning procedure The small intestine was scanned using a Philips Healthcare IQon Spectral CT, covering the top of the diaphragm to the pubic symphysis. The patients were asked to hold their breath to enhance their image quality. The scanning parameters included a tube voltage of 120 kVp, automatic tube current modulation, and a rotation speed of 0.5 s/r. A contrast agent (Iohexol, Bonorex 350) was injected intravenously at 1.6 ml/kg body weight with a rate of 5 m/s. Contrast bolus tracking was performed using the abdominal aorta as the detection area. Dual-phase-enhanced scanning was performed with delays of 6 and 39 s after reaching a threshold of 120 HU. Following the scan, 30 ml of normal saline was injected at the same flow rate. After dual-phase image acquisition, venous-phase data were reconstructed using the iterative reconstruction algorithm iDose4 (Philips Healthcare) at 120 kVp, generating traditional mixed-energy images and VMI at 40 keV. The optimal keV for DECTE, as determined by Lee et al., provided the best contrast-noise ratio and attenuation values, thus improving the diagnostic performance for active CD . Taguchi et al. confirmed that the sensitivity and specificity of intestinal wall CT values at 40 keV are relatively high . Consequently, VMI was reconstructed at 40 keV to enhance the diagnostic performance. Conventional images and VMI were reconstructed in the axial and coronal planes with a slice thickness of 1 mm and a reconstruction interval of 1 mm. The reconstructed data were transferred to a postprocessing workstation for dual-energy image analysis. DBE Bowel preparation All patients adhered to a full liquid diet one day prior to DBE and fasted for 12 h before the examination. Four patients who underwent only oral DBE do not need bowel preparation. Other patients need bowel preparation. The evening before the procedure, patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water. On the day of the examination, patients consumed 137.12 g of polyethylene glycol electrolyte powder mixed with 2000 ml of warm water in multiple oral doses starting at 06:00 until a clear, watery stool was obtained. Depending on the estimated location of the target lesion, either the oral or the anal route was selected. During the procedure, patients were sedated with propofol. Equipment and technique DBE was performed using the FUJINON EN-580T system, which includes a main unit, a 200-cm long endoscope, a 160-cm sheath, and an air pump. Latex balloons at the tip of the endoscope and sheath, which were controlled by a pressure-regulated pump system, were inflated and deflated to facilitate insertion. To minimise friction, water and olive oil were introduced between the endoscope and the sheath. Utilising the “push-and-pull” technique described by Yamamoto et al., the balloons were alternately inflated and deflated to advance the endoscope as deeply as possible into the small intestine. If the intestine was too narrow for passage, the procedure was terminated. Definitions and diagnostic criteria Detection rate Proportion of patients with positive examination results. Diagnostic rate Proportion of patients diagnosed by examination who met the diagnostic criteria. Terminal ileum The last 30 cm of the ileum, irrespective of prior small intestine resection. Long ulcer An ulcer greater than 2 cm in length. Diagnostic criteria of DBE Discontinuous or segmental lesions, cobblestone appearance, and longitudinal ulcers . The diagnostic criteria for DECTE include discontinuous or segmental lesions, cobblestone appearance, longitudinal ulcers, transmural inflammation, fissures, and fistulas . Definition of stenosis using DBE Observed luminal narrowing. Definitions of stenosis by DECTE Meeting two of the following three criteria: luminal diameter ≤ 10 mm or ≤ 50% luminal narrowing, wall thickness ≥ 3 mm, and pre-stenotic dilation ≥ 30 mm . Inflammatory stenosis Recoverable with anti-inflammatory therapy. Fibrous stenosis Characterised by luminal narrowing without oedema, typically requiring surgical intervention. Evaluation method Two senior endoscopists and radiologists independently assessed the DBE and DECTE images in a blinded manner to determine the presence of CD, stenosis, fistulas, perianal lesions, and ulcers (Figs. and ). Statistical analysis The results with normal distribution are presented as the means ± standard error of means (SEM) and the non-normal results are presented as medians ± interquartile ranges (IQRs). An unpaired/Welch’s t test was used to analyze normal data and Mann–Whitney U test was used to analyze non-normal data in two groups. Categorical data are presented as frequencies and percentages, and group comparisons were performed using the chi-square test. A Kappa consistency test was used to assess the agreement. P < 0.05 was considered statistically significant.   At the Endoscopic Centre of the First Affiliated Hospital of Soochow University, patients with suspicious small intestinal disease who underwent DBE between 1 July 2016 and 1 November 2023 were included initially. The inclusion criteria were as follows: (1) Diagnosis of CD ; (2) Undergoing both DECTE and DBE within 3 months; and (3) availability of complete data from DECTE, DBE, and clinical assessments. The exclusion criteria were as follows: (1) Pathological results indicating conditions other than CD or inconclusive diagnoses, (2) incomplete data, and (3) the period between DBE and DECTE > 3 months. This study was reviewed and approved by the Medical Ethics Committee of the First Affiliated Hospital of Soochow University (Approval No. 2024–249).   Preparation Patients were instructed to follow a liquid or semi-liquid diet the day before DECTE. Patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water twice on the night before examination, and on the day of examination respectively, until a clear, watery stool was obtained. One hour before the scan, patients ingested 2000 ml of 2.5% isotonic mannitol solution at five 10-min intervals. An additional 300 ml of the solution was used to fill the stomach and the upper jejunum. To suppress intestinal motility, anisodamine (10 mg) was administered intramuscularly 10 min before scanning. Scanning procedure The small intestine was scanned using a Philips Healthcare IQon Spectral CT, covering the top of the diaphragm to the pubic symphysis. The patients were asked to hold their breath to enhance their image quality. The scanning parameters included a tube voltage of 120 kVp, automatic tube current modulation, and a rotation speed of 0.5 s/r. A contrast agent (Iohexol, Bonorex 350) was injected intravenously at 1.6 ml/kg body weight with a rate of 5 m/s. Contrast bolus tracking was performed using the abdominal aorta as the detection area. Dual-phase-enhanced scanning was performed with delays of 6 and 39 s after reaching a threshold of 120 HU. Following the scan, 30 ml of normal saline was injected at the same flow rate. After dual-phase image acquisition, venous-phase data were reconstructed using the iterative reconstruction algorithm iDose4 (Philips Healthcare) at 120 kVp, generating traditional mixed-energy images and VMI at 40 keV. The optimal keV for DECTE, as determined by Lee et al., provided the best contrast-noise ratio and attenuation values, thus improving the diagnostic performance for active CD . Taguchi et al. confirmed that the sensitivity and specificity of intestinal wall CT values at 40 keV are relatively high . Consequently, VMI was reconstructed at 40 keV to enhance the diagnostic performance. Conventional images and VMI were reconstructed in the axial and coronal planes with a slice thickness of 1 mm and a reconstruction interval of 1 mm. The reconstructed data were transferred to a postprocessing workstation for dual-energy image analysis.   Patients were instructed to follow a liquid or semi-liquid diet the day before DECTE. Patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water twice on the night before examination, and on the day of examination respectively, until a clear, watery stool was obtained. One hour before the scan, patients ingested 2000 ml of 2.5% isotonic mannitol solution at five 10-min intervals. An additional 300 ml of the solution was used to fill the stomach and the upper jejunum. To suppress intestinal motility, anisodamine (10 mg) was administered intramuscularly 10 min before scanning.   The small intestine was scanned using a Philips Healthcare IQon Spectral CT, covering the top of the diaphragm to the pubic symphysis. The patients were asked to hold their breath to enhance their image quality. The scanning parameters included a tube voltage of 120 kVp, automatic tube current modulation, and a rotation speed of 0.5 s/r. A contrast agent (Iohexol, Bonorex 350) was injected intravenously at 1.6 ml/kg body weight with a rate of 5 m/s. Contrast bolus tracking was performed using the abdominal aorta as the detection area. Dual-phase-enhanced scanning was performed with delays of 6 and 39 s after reaching a threshold of 120 HU. Following the scan, 30 ml of normal saline was injected at the same flow rate. After dual-phase image acquisition, venous-phase data were reconstructed using the iterative reconstruction algorithm iDose4 (Philips Healthcare) at 120 kVp, generating traditional mixed-energy images and VMI at 40 keV. The optimal keV for DECTE, as determined by Lee et al., provided the best contrast-noise ratio and attenuation values, thus improving the diagnostic performance for active CD . Taguchi et al. confirmed that the sensitivity and specificity of intestinal wall CT values at 40 keV are relatively high . Consequently, VMI was reconstructed at 40 keV to enhance the diagnostic performance. Conventional images and VMI were reconstructed in the axial and coronal planes with a slice thickness of 1 mm and a reconstruction interval of 1 mm. The reconstructed data were transferred to a postprocessing workstation for dual-energy image analysis.   Bowel preparation All patients adhered to a full liquid diet one day prior to DBE and fasted for 12 h before the examination. Four patients who underwent only oral DBE do not need bowel preparation. Other patients need bowel preparation. The evening before the procedure, patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water. On the day of the examination, patients consumed 137.12 g of polyethylene glycol electrolyte powder mixed with 2000 ml of warm water in multiple oral doses starting at 06:00 until a clear, watery stool was obtained. Depending on the estimated location of the target lesion, either the oral or the anal route was selected. During the procedure, patients were sedated with propofol. Equipment and technique DBE was performed using the FUJINON EN-580T system, which includes a main unit, a 200-cm long endoscope, a 160-cm sheath, and an air pump. Latex balloons at the tip of the endoscope and sheath, which were controlled by a pressure-regulated pump system, were inflated and deflated to facilitate insertion. To minimise friction, water and olive oil were introduced between the endoscope and the sheath. Utilising the “push-and-pull” technique described by Yamamoto et al., the balloons were alternately inflated and deflated to advance the endoscope as deeply as possible into the small intestine. If the intestine was too narrow for passage, the procedure was terminated.   All patients adhered to a full liquid diet one day prior to DBE and fasted for 12 h before the examination. Four patients who underwent only oral DBE do not need bowel preparation. Other patients need bowel preparation. The evening before the procedure, patients ingested 68.56 g of polyethylene glycol electrolyte powder dissolved in 1000 ml of warm water. On the day of the examination, patients consumed 137.12 g of polyethylene glycol electrolyte powder mixed with 2000 ml of warm water in multiple oral doses starting at 06:00 until a clear, watery stool was obtained. Depending on the estimated location of the target lesion, either the oral or the anal route was selected. During the procedure, patients were sedated with propofol.   DBE was performed using the FUJINON EN-580T system, which includes a main unit, a 200-cm long endoscope, a 160-cm sheath, and an air pump. Latex balloons at the tip of the endoscope and sheath, which were controlled by a pressure-regulated pump system, were inflated and deflated to facilitate insertion. To minimise friction, water and olive oil were introduced between the endoscope and the sheath. Utilising the “push-and-pull” technique described by Yamamoto et al., the balloons were alternately inflated and deflated to advance the endoscope as deeply as possible into the small intestine. If the intestine was too narrow for passage, the procedure was terminated.   Detection rate Proportion of patients with positive examination results. Diagnostic rate Proportion of patients diagnosed by examination who met the diagnostic criteria. Terminal ileum The last 30 cm of the ileum, irrespective of prior small intestine resection. Long ulcer An ulcer greater than 2 cm in length. Diagnostic criteria of DBE Discontinuous or segmental lesions, cobblestone appearance, and longitudinal ulcers . The diagnostic criteria for DECTE include discontinuous or segmental lesions, cobblestone appearance, longitudinal ulcers, transmural inflammation, fissures, and fistulas . Definition of stenosis using DBE Observed luminal narrowing. Definitions of stenosis by DECTE Meeting two of the following three criteria: luminal diameter ≤ 10 mm or ≤ 50% luminal narrowing, wall thickness ≥ 3 mm, and pre-stenotic dilation ≥ 30 mm . Inflammatory stenosis Recoverable with anti-inflammatory therapy. Fibrous stenosis Characterised by luminal narrowing without oedema, typically requiring surgical intervention. Evaluation method Two senior endoscopists and radiologists independently assessed the DBE and DECTE images in a blinded manner to determine the presence of CD, stenosis, fistulas, perianal lesions, and ulcers (Figs. and ).   Proportion of patients with positive examination results.   Proportion of patients diagnosed by examination who met the diagnostic criteria.   The last 30 cm of the ileum, irrespective of prior small intestine resection.   An ulcer greater than 2 cm in length.   Discontinuous or segmental lesions, cobblestone appearance, and longitudinal ulcers . The diagnostic criteria for DECTE include discontinuous or segmental lesions, cobblestone appearance, longitudinal ulcers, transmural inflammation, fissures, and fistulas .   Observed luminal narrowing.   Meeting two of the following three criteria: luminal diameter ≤ 10 mm or ≤ 50% luminal narrowing, wall thickness ≥ 3 mm, and pre-stenotic dilation ≥ 30 mm .   Recoverable with anti-inflammatory therapy.   Characterised by luminal narrowing without oedema, typically requiring surgical intervention.   Two senior endoscopists and radiologists independently assessed the DBE and DECTE images in a blinded manner to determine the presence of CD, stenosis, fistulas, perianal lesions, and ulcers (Figs. and ).   The results with normal distribution are presented as the means ± standard error of means (SEM) and the non-normal results are presented as medians ± interquartile ranges (IQRs). An unpaired/Welch’s t test was used to analyze normal data and Mann–Whitney U test was used to analyze non-normal data in two groups. Categorical data are presented as frequencies and percentages, and group comparisons were performed using the chi-square test. A Kappa consistency test was used to assess the agreement. P < 0.05 was considered statistically significant.   At the Endoscopic Centre of the First Affiliated Hospital of Soochow University, 330 patients with suspicious small intestinal disease underwent DBE between 1 July 2016 and 1 November 2023. Among them, 92 patients were diagnosed with CD. Of these, 81 patients underwent small intestine DECTE. The study ultimately enrolled 72 patients who underwent both DECTE and DBE, with 4 patients repeating both procedures within 3 months. Data from 76 patients with CD were analyzed to ensure that no treatment was administered within 3 months (Fig. ). There were significant time gap existed between the procedures in the four repeated cases, The durations are 324, 371, 463 and 498 days, respectively, which we believe represent different points in the inflammatory process, suggesting potential different findings. Therefore, we chose not to exclude these four repeated cases. The demographic and clinical characteristics of the enrolled patients with CD are summarised in Tables and . Of these, 13 underwent both oral and anal DBE, 59 underwent only anal DBE, and 4 underwent only oral DBE. Diagnostic accuracy The diagnostic rate for small bowel CD was 80.3% for DBE, significantly higher than 65.8% for DECTE (χ2 = 4.041, P = 0.044). The combined diagnostic rate was 89.5%, exceeding DECTE alone (χ2 = 12.275, P < 0.001), but not significantly different from DBE alone (χ2 = 2.510, P = 0.113) (Table ). For patients with abdominal pain, DBE had a diagnostic rate of 79.4%, higher than 63.5% of DECTE (χ2 = 3.889, P = 0.049). The combined diagnostic rate was 87.3%, which was higher than that of DECTE alone (χ2 = 9.626, P = 0.002), but not significantly different from that of DBE alone ( P = 0.339). For patients with diarrhoea, the DBE’s diagnostic rates were 86.8% and 68.4% for DECTE, with no significant difference between the two ( P = 0.097). The combined diagnostic rate was 94.7%, higher than DECTE alone (χ2 = 7.092, P = 0.008), but not significantly different from DBE alone ( P = 0.430) (Table ). For patients with other symptoms, such as abdominal distension or vomiting, the DBE diagnostic rate was 79.4% compared with 61.8% for DECTE, with no significant difference between the two ( P = 0.183). The combined diagnostic rate was higher than DECTE alone (χ2 = 6.620, P = 0.010), but not significantly different from DBE alone ( P = 0.305) (Table ). Consistency CD diagnosis The consistency between DBE and DECTE in diagnosing small bowel CD was low (Kappa = 0.187, T = 1.743, P = 0.081). Montreal classification B1-B3 The consistency in the Montreal classification of disease behavior (B1-B3) between DBE and DECTE was poor (kappa = 0.059, T = 0.744, P = 0.457). Montreal classification L1-L4 There was poor consistency in the Montreal classification of disease location L1-L4 (Ileal, Colonic, Ileo-colonic, Isolated upper gastrointestinal disease) between DBE and DECTE (kappa = 0.293, T = 3.170, P = 0.002). For specific categories L1 and L3 (ileal and ileocolonic), consistency was also poor (kappa = 0.369, T = 3.117, P = 0.002). Assessment of adverse events associated with CD Stenosis The detection rate of stenosis by DBE was 46.1%, significantly higher than 13.2% by DECTE (χ2 = 19.730, P < 0.001). The combined detection rate of stenosis was 52.6%, higher than DECTE alone (χ2 = 26.824, P < 0.001), with no significant difference compared to DBE alone ( P = 0.417) (Table ). DBE identified 35 cases of stenosis, including 3 cases of fibrous stenosis (8.6%). DECTE identified 10 cases, including two cases of fibrous stenosis (20.0%). There was no significant difference in the detection rate of fibrous stenosis between the two methods ( P = 0.306). Fistula DECTE detected 2 fistulas (one anal fistula and one intestinal fistula), whereas DBE detected 3 fistulas (one anal fistula and two intestinal fistulas). No fistulas were detected simultaneously using either method (Table ). The detection rates of fistulas using DBE and DECTE was 3.9%, and 2.6%, respectively. The combined detection rate was 5.3%, with no significant difference between the methods ( P > 0.05). Perianal lesion Both DBE and DECTE identified a perianal lesion (anal fistula). Among the 27 patients who underwent perianal Magnetic Resonance Imaging (MRI), 11 perianal lesions were detected (9 anal fistulas, 1 perianal abscess, and 1 combined anal fistula and perianal abscess), with a detection rate of 40.7%, which was significantly higher than that of DBE or DECTE. Assessment of ulcers Detection rate of ulcers Regarding ulcer detection, DBE exhibited a detection rate of 73.7%, significantly higher than the 7.9% detection rate achieved by DECTE (χ 2 = 68.100, P < 0.001). The combined ulcer detection rate, when using both methods, reached 76.3%, which was also significantly higher than DECTE alone (χ 2 = 72.977, P < 0.001), but not statistically different from DBE alone (χ 2 = 0.140, P = 0.708) (Table ). DBE identified 10 long ulcers (≥ 2 cm), corresponding to a detection rate of 17.9%. Additionally, DBE detected 46 ulcers in the terminal ileum, 1 in the colon, and 9 in the ileo-colon, resulting in a 17.9% detection rate of non-terminal ileal ulcers. Conversely, DECTE exclusively identified ulcers in the terminal ileum. These findings indicate that DBE is superior to DECTE for detecting long ulcers (≥ 2 cm) and non-terminal ileal ulcers. Laboratory tests DECTE identified 6 ulcer-positive and 70 ulcer-negative patients. No significant differences were observed in the levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), faecal calprotectin (FC), haemoglobin (Hb), platelet count (PLT), albumin (ALB), haematocrit (HCT), Crohn’s Disease Activity Index (CDAI) scores, or Simple Endoscopic Score for Crohn’s Disease (SES-CD) scores between ulcer-positive and ulcer-negative patients ( P > 0.05) (Table ). In contrast, DBE was used to identify 56 ulcer-positive and 20 ulcer-negative patients. Significant differences were observed in CRP, ESR, FC, Hb, PLT, ALB, HCT, CDAI, and SES-CD scores between ulcer-positive and those patients ( P < 0.05) (Table ).   The diagnostic rate for small bowel CD was 80.3% for DBE, significantly higher than 65.8% for DECTE (χ2 = 4.041, P = 0.044). The combined diagnostic rate was 89.5%, exceeding DECTE alone (χ2 = 12.275, P < 0.001), but not significantly different from DBE alone (χ2 = 2.510, P = 0.113) (Table ). For patients with abdominal pain, DBE had a diagnostic rate of 79.4%, higher than 63.5% of DECTE (χ2 = 3.889, P = 0.049). The combined diagnostic rate was 87.3%, which was higher than that of DECTE alone (χ2 = 9.626, P = 0.002), but not significantly different from that of DBE alone ( P = 0.339). For patients with diarrhoea, the DBE’s diagnostic rates were 86.8% and 68.4% for DECTE, with no significant difference between the two ( P = 0.097). The combined diagnostic rate was 94.7%, higher than DECTE alone (χ2 = 7.092, P = 0.008), but not significantly different from DBE alone ( P = 0.430) (Table ). For patients with other symptoms, such as abdominal distension or vomiting, the DBE diagnostic rate was 79.4% compared with 61.8% for DECTE, with no significant difference between the two ( P = 0.183). The combined diagnostic rate was higher than DECTE alone (χ2 = 6.620, P = 0.010), but not significantly different from DBE alone ( P = 0.305) (Table ).   CD diagnosis The consistency between DBE and DECTE in diagnosing small bowel CD was low (Kappa = 0.187, T = 1.743, P = 0.081). Montreal classification B1-B3 The consistency in the Montreal classification of disease behavior (B1-B3) between DBE and DECTE was poor (kappa = 0.059, T = 0.744, P = 0.457). Montreal classification L1-L4 There was poor consistency in the Montreal classification of disease location L1-L4 (Ileal, Colonic, Ileo-colonic, Isolated upper gastrointestinal disease) between DBE and DECTE (kappa = 0.293, T = 3.170, P = 0.002). For specific categories L1 and L3 (ileal and ileocolonic), consistency was also poor (kappa = 0.369, T = 3.117, P = 0.002).   The consistency between DBE and DECTE in diagnosing small bowel CD was low (Kappa = 0.187, T = 1.743, P = 0.081).   The consistency in the Montreal classification of disease behavior (B1-B3) between DBE and DECTE was poor (kappa = 0.059, T = 0.744, P = 0.457).   There was poor consistency in the Montreal classification of disease location L1-L4 (Ileal, Colonic, Ileo-colonic, Isolated upper gastrointestinal disease) between DBE and DECTE (kappa = 0.293, T = 3.170, P = 0.002). For specific categories L1 and L3 (ileal and ileocolonic), consistency was also poor (kappa = 0.369, T = 3.117, P = 0.002).   Stenosis The detection rate of stenosis by DBE was 46.1%, significantly higher than 13.2% by DECTE (χ2 = 19.730, P < 0.001). The combined detection rate of stenosis was 52.6%, higher than DECTE alone (χ2 = 26.824, P < 0.001), with no significant difference compared to DBE alone ( P = 0.417) (Table ). DBE identified 35 cases of stenosis, including 3 cases of fibrous stenosis (8.6%). DECTE identified 10 cases, including two cases of fibrous stenosis (20.0%). There was no significant difference in the detection rate of fibrous stenosis between the two methods ( P = 0.306). Fistula DECTE detected 2 fistulas (one anal fistula and one intestinal fistula), whereas DBE detected 3 fistulas (one anal fistula and two intestinal fistulas). No fistulas were detected simultaneously using either method (Table ). The detection rates of fistulas using DBE and DECTE was 3.9%, and 2.6%, respectively. The combined detection rate was 5.3%, with no significant difference between the methods ( P > 0.05). Perianal lesion Both DBE and DECTE identified a perianal lesion (anal fistula). Among the 27 patients who underwent perianal Magnetic Resonance Imaging (MRI), 11 perianal lesions were detected (9 anal fistulas, 1 perianal abscess, and 1 combined anal fistula and perianal abscess), with a detection rate of 40.7%, which was significantly higher than that of DBE or DECTE.   The detection rate of stenosis by DBE was 46.1%, significantly higher than 13.2% by DECTE (χ2 = 19.730, P < 0.001). The combined detection rate of stenosis was 52.6%, higher than DECTE alone (χ2 = 26.824, P < 0.001), with no significant difference compared to DBE alone ( P = 0.417) (Table ). DBE identified 35 cases of stenosis, including 3 cases of fibrous stenosis (8.6%). DECTE identified 10 cases, including two cases of fibrous stenosis (20.0%). There was no significant difference in the detection rate of fibrous stenosis between the two methods ( P = 0.306).   DECTE detected 2 fistulas (one anal fistula and one intestinal fistula), whereas DBE detected 3 fistulas (one anal fistula and two intestinal fistulas). No fistulas were detected simultaneously using either method (Table ). The detection rates of fistulas using DBE and DECTE was 3.9%, and 2.6%, respectively. The combined detection rate was 5.3%, with no significant difference between the methods ( P > 0.05).   Both DBE and DECTE identified a perianal lesion (anal fistula). Among the 27 patients who underwent perianal Magnetic Resonance Imaging (MRI), 11 perianal lesions were detected (9 anal fistulas, 1 perianal abscess, and 1 combined anal fistula and perianal abscess), with a detection rate of 40.7%, which was significantly higher than that of DBE or DECTE.   Detection rate of ulcers Regarding ulcer detection, DBE exhibited a detection rate of 73.7%, significantly higher than the 7.9% detection rate achieved by DECTE (χ 2 = 68.100, P < 0.001). The combined ulcer detection rate, when using both methods, reached 76.3%, which was also significantly higher than DECTE alone (χ 2 = 72.977, P < 0.001), but not statistically different from DBE alone (χ 2 = 0.140, P = 0.708) (Table ). DBE identified 10 long ulcers (≥ 2 cm), corresponding to a detection rate of 17.9%. Additionally, DBE detected 46 ulcers in the terminal ileum, 1 in the colon, and 9 in the ileo-colon, resulting in a 17.9% detection rate of non-terminal ileal ulcers. Conversely, DECTE exclusively identified ulcers in the terminal ileum. These findings indicate that DBE is superior to DECTE for detecting long ulcers (≥ 2 cm) and non-terminal ileal ulcers. Laboratory tests DECTE identified 6 ulcer-positive and 70 ulcer-negative patients. No significant differences were observed in the levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), faecal calprotectin (FC), haemoglobin (Hb), platelet count (PLT), albumin (ALB), haematocrit (HCT), Crohn’s Disease Activity Index (CDAI) scores, or Simple Endoscopic Score for Crohn’s Disease (SES-CD) scores between ulcer-positive and ulcer-negative patients ( P > 0.05) (Table ). In contrast, DBE was used to identify 56 ulcer-positive and 20 ulcer-negative patients. Significant differences were observed in CRP, ESR, FC, Hb, PLT, ALB, HCT, CDAI, and SES-CD scores between ulcer-positive and those patients ( P < 0.05) (Table ).   Regarding ulcer detection, DBE exhibited a detection rate of 73.7%, significantly higher than the 7.9% detection rate achieved by DECTE (χ 2 = 68.100, P < 0.001). The combined ulcer detection rate, when using both methods, reached 76.3%, which was also significantly higher than DECTE alone (χ 2 = 72.977, P < 0.001), but not statistically different from DBE alone (χ 2 = 0.140, P = 0.708) (Table ). DBE identified 10 long ulcers (≥ 2 cm), corresponding to a detection rate of 17.9%. Additionally, DBE detected 46 ulcers in the terminal ileum, 1 in the colon, and 9 in the ileo-colon, resulting in a 17.9% detection rate of non-terminal ileal ulcers. Conversely, DECTE exclusively identified ulcers in the terminal ileum. These findings indicate that DBE is superior to DECTE for detecting long ulcers (≥ 2 cm) and non-terminal ileal ulcers.   DECTE identified 6 ulcer-positive and 70 ulcer-negative patients. No significant differences were observed in the levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), faecal calprotectin (FC), haemoglobin (Hb), platelet count (PLT), albumin (ALB), haematocrit (HCT), Crohn’s Disease Activity Index (CDAI) scores, or Simple Endoscopic Score for Crohn’s Disease (SES-CD) scores between ulcer-positive and ulcer-negative patients ( P > 0.05) (Table ). In contrast, DBE was used to identify 56 ulcer-positive and 20 ulcer-negative patients. Significant differences were observed in CRP, ESR, FC, Hb, PLT, ALB, HCT, CDAI, and SES-CD scores between ulcer-positive and those patients ( P < 0.05) (Table ).   This study retrospectively examined the diagnostic performance of DBE and compared it with that of DECTE in patients diagnosed with CD. The results indicated that DBE had a higher diagnostic rate for small bowel CD than did DECTE. Furthermore, the combined diagnostic rate of small bowel CD using both methods was higher than that achieved with DECTE alone, with no significant difference compared with DBE alone. It has been found by Halloran that for patients with suspected or confirmed CD, DBE is a safe and effective procedure. Moreover, during the follow-up period, patients who underwent stricture dilation via DBE had an 80% surgery-free rate . Similarly, Wang et al. conducted Multidetector Computed Tomography Enterography (MDCTE) and DBE examinations on 190 patients with suspected small bowel diseases. The overall detection rates of DBE and MDCTE were 92.6% and 55.8%, respectively ( P < 0.05), with total diagnostic rates of 83.2% and 33.7% ( P < 0.05). Among these, 10 patients were diagnosed with CD. MDCTE identified 8 cases of CD, whereas DBE diagnosed all 10 , indicating a higher diagnostic accuracy of DBE for small bowel CD, which aligns with our findings. The difference lies in that our study included confirmed CD patients, and our sample size was larger. Huang et al. performed DBE on 18 patients with suspected isolated small bowel CD between April 2014 and June 2018. Considering clinical manifestations, pathological features, endoscopic and histological findings, and experimental treatments, 14 out of 18 (78%) patients were confirmed to have CD, with a DBE-assisted diagnostic rate of 86% (12/14), suggesting a high diagnostic accuracy of DBE for isolated small bowel CD . Our study reported a DBE diagnostic rate of 80.3%, with the distinction that our patients were not exclusively those with isolated small bowel CD. In a tertiary care setting such as ours, where many patients have a prolonged disease history and severe conditions, DBE’s ability of DBE to detect lesions may be enhanced owing to the presence of more pronounced clinical features. DECTE, being non-invasive, is valuable for identifying lesion locations and guiding the insertion route for DBE. DECTE shows small bowel disease more effectively than conventional CT . Current research on DECTE focuses on quantitative analyses such as virtual monoenergetic CT values and iodine density . However, Ohliger highlighted that despite advancements in DECTE, the evaluation of CD imaging features, such as mucosal hyperenhancement, remains subjective. This subjectivity complicates the correlation between these features and the severity of inflammation and intestinal damage, highlighting the need for further research . The contraindications for DECTE include: pregnant women; individuals with renal insufficiency; patients with hyperthyroidism; individuals with allergies; and others such as patients with severe cardiac arrhythmias . The contraindications for DBE encompass those with severe dysfunction of organs such as the heart and lungs, as well as patients who are unable to tolerate or cooperate with endoscopic examinations, including those who are unconscious, mentally abnormal, or unable to cooperate with the examination. Therefore, if there are contraindications for DECTE, DBE can be chosen for examination, and vice versa. The clinical manifestations of CD are highly diverse, encompassing symptoms such as abdominal pain, diarrhoea, abdominal distension and vomiting. These symptoms are similar to those of many other abdominal diseases, which complicates the early identification of CD. In patients presenting with abdominal pain, DBE demonstrated a higher diagnostic rate for small bowel CD than DECTE, and the combined diagnostic rate was superior to that of DECTE alone. For patients with diarrhoea and additional symptoms, such as abdominal distension and vomiting, the combined diagnostic rate also exceeded that of DECTE alone (Table ). These findings suggest that DBE or a combination of DBE and DECTE may serve as a more effective diagnostic tool for patients with CD with varying clinical symptoms. By integrating the strengths of DBE and DECTE, a synergistic effect can be achieved, thereby enhancing the diagnostic yield for CD. This approach is particularly beneficial for patients who present with different clinical symptoms or for whom a definitive diagnosis cannot be readily established using conventional diagnostic methods. Marques et al. noted that the concordance between single-balloon enteroscopy and CT or MRI was only moderate . We observed poor concordance between DECTE and DBE regarding lesion localisation. Specifically, there is limited agreement between DECTE and DBE in identifying ileal and ileocolonic lesions. Although DBE is an invasive technique that allows the direct visualisation of superficial intestinal lesions, it does not assess transmural lesions . Consequently, when DBE identifies only superficial ulcers and mucosal inflammation, it may be insufficient for a definitive diagnosis of CD. Research indicates that during diagnosis, 77% of CD patients present purely with inflammatory disease, whereas 11% and 16% have already developed stenosis and fistulas, respectively . Therefore, evaluation of common CD adverse events is an essential diagnostic step. Hu et al. ‘s study, which included 165 CD patients with stenosis, demonstrated that DBE is a more effective diagnostic tool than computed tomography enterography (CTE) for detecting stenosis in CD patients . This finding is consistent with our results, indicating that DBE or combined methods are superior to DECTE for stenosis detection. DECTE identified one case of an intestinal fistula that presented as a clustered ileal mucosa, whereas DBE did not detect this lesion at the same location. The prolonged duration of chronic inflammation in CD often results in a more pronounced clustering of the ileal mucosa, thereby making it more detectable by DECTE. Regarding perianal lesions in CD, among the 76 cases studied, DECTE and DBE detected only one anal fistula. The detection rate by perianal MRI was 40.7%, making it the preferred method for assessing perianal lesions. In this study, the detection rate of ulcers using DBE was notably higher than using DECTE alone. Furthermore, the combined detection rate of ulcers using both DBE and DECTE was higher than that achieved using DECTE alone. Significant differences in CRP, ESR, FC, Hb, PLT, ALB, HCT, CDAI, SES-CD were observed between ulcer-positive and ulcer-negative patients detected by DBE, whereas DECTE did not show such differences. Inflammatory markers play a significant role in the diagnosis and management of CD. CRP and ESR are the most commonly used markers, with CRP being more sensitive and capable of more rapidly reflecting changes in inflammation. FC also provides a novel tool for the management of CD. Patients with positive ulcers identified by DBE have significantly higher levels of inflammatory markers compared to those with negative findings, highlighting the reliability and sensitivity of DBE in detecting small intestinal inflammation. Given that DBE allows for a direct visual assessment of the presence of ulcers and the status of inflammation, comparing DBE findings before and after treatment can provide crucial evidence for clinical decision-making regarding therapeutic strategies. Therefore, DBE should be considered for precise evaluation and determination of treatment strategies in the management of CD . Specifically, DBE has been utilized to assess mucosal healing in patients with CD following treatment. Among patients with ulcers detected by DBE but not by DECTE, 33 corresponding pathological reports were available: 23 cases of chronic inflammation and 10 cases of mixed acute and chronic inflammation, indicating a higher proportion of chronic inflammation. This disparity may be attributed to the less pronounced enhancement of chronic inflammation on DECTE compared to acute inflammation, which is more directly visible on DBE. While the results of this study highlight the advantages of DBE, DECTE offers numerous benefits, including improved image quality and contrast, reduced contrast agent usage, and the provision of rich information. DBE also has clinical limitations, including the risk of complications such as bleeding, pancreatitis, perforation, intra-abdominal infection, hypotension, and arrhythmia. The procedure for DBE is time-consuming, and most patients cannot complete a full small intestine examination in a single session, requiring high patient compliance. Additionally, DBE poses anesthesia risks, particularly for elderly patients or those with abnormal cardiopulmonary function or unstable vital signs. DBE has limitations in terms of restricted vision, as the field of view is limited by the inflation of the balloons, preventing complete access to every part of the small intestine. The operation of DBE is relatively complex and requires experienced doctors to perform; otherwise, it may increase the risk of complications. For patients with CD, DECTE is non-invasive and can serve as an alternative for those who cannot tolerate DBE. This study provides a novel comparison of lesion location assessment and disease behaviour in patients with CD between concurrent DECTE and DBE. We also evaluated the diagnostic accuracies of both modalities for CD across various clinical symptoms. Additionally, this study incorporated laboratory markers, CDAI, and SES-CD scores to assess the correlation among disease activity, clinical severity of inflammation, and endoscopic findings. This study focused on qualitative analysis using VMI at 40 keV, a method that is both practical and amenable to broader applications. Nevertheless, as this was a retrospective, single-centre study, it was subject to selection bias due to inclusion and exclusion criteria, it is subject to temporal bias within a particular period. Berkson’s Bias is present due to this hospital-based study. In this study, confounding variables such as age, gender, lifestyle habits and past medical history have influenced the research results to some extent. Although control over some confounding variables was lacking, there was corresponding control over key confounding variables, such as whether treatment for CD was received between DBE and DECTE examinations. All patients did not receive CD treatment during the interval between the two examinations. Therefore, it is still considered feasible to compare the diagnostic value of the two methods under the same conditions. Overall, although there is some influence from selection bias and confounding variables, the impact is not significant. We have also done our best to address these influences, making the results credible. Another limitation of this study is the exclusion of multicenter data. As the study hospital is a tertiary care center capable of conducting both DECT and DBE, conducting a multicenter study would require cross-regional collaboration with more tertiary hospitals, posing challenges such as resource constraints and difficulties in data acquisition. In the future, simultaneous conduct across multiple locations or institutions, encompassing different regions, populations, and medical institutions, could better represent the diversity of the target population and enhance the generality of the research results. Furthermore, it is necessary to compare DECTE or DBE with the gold standard diagnostic methods for Small Bowel CD, such as MRI Enterography or Small Bowel Capsule Endoscopy. Despite discussing these limitations, it is also important to emphasize the strengths of this study, such as the detailed retrospective data and its novelty and uniqueness.   DBE or the combined use of DECTE and DBE provides superior diagnostic performance for small bowel CD, particularly in detecting stenosis and ulcers, compared with DECTE alone. Moreover, DBE can be used to identify long ulcers and non-ileocecal ulcers. DBE helps diagnose CD across different clinical manifestations and assess disease activity in various inflammatory states.   