Endoscopic Diagnosis of Small Bowel Tumor

Recent technological advances, including capsule endoscopy (CE) and balloon-assisted endoscopy (BAE), have revealed that small intestinal disease is more common than previously thought. CE has advantages, including a high diagnostic yield, discomfort-free, outpatient basis, and physiological images. BAE enabled endoscopic diagnosis and treatment in the deep small bowel. Computed tomography (CT) enterography with negative oral contrast can evaluate masses, wall thickening, and narrowing of the small intestine. In addition, enhanced CT can detect abnormalities outside the gastrointestinal tract that endoscopy cannot evaluate. Each modality has its advantages and disadvantages, and a good combination of multiple modalities leads to an accurate diagnosis. As a first-line modality, three-phase enhanced CT is preferred. If CT shows a mass, stenosis, or wall thickening, a BAE should be selected. If there are no abnormal findings on CT and no obstructive symptoms, CE should be selected. If there are significant findings in the CE, determine the indication for BAE and its insertion route based on these findings. Early diagnosis of small intestinal tumors is essential for favorable outcomes. For early diagnosis, the possibility of small bowel lesions should be considered in patients with unexplained symptoms and signs after examination of the upper and lower gastrointestinal tract.

Prediction of pathological activity in Crohn's disease based on dual-energy CT enterography

PURPOSE

To explore the feasibility of predicting the pathological activity of Crohn's disease (CD) based on dual-energy CT enterography (DECTE).

METHODS

The clinical, endoscopic, imaging and pathological data of 55 patients with CD scanned by DECTE were retrospectively analyzed; the pathological results were used as a reference standard to classify the diseased bowel segments into active and inactive phases. The normalized iodine concentration (NIC), energy-spectrum curve slope K, dual energy index (DEI), fat fraction (FF) of the arterial phases and venous phases were compared. To assess the parameters' predictive ability, receiver-operating characteristic curves were used. The Delong test was used to compare the differences between the diagnostic efficiency of each parameter.

RESULTS

A total of 84 intestinal segments were included in the study, including 54 active intestinal segments and 30 inactive intestinal segments. The NIC, energy-spectrum curve slope K and DEI were significantly different between active and inactive bowel segments in the arterial and venous phases (P < 0.05), while FF were not significantly different (P > 0.05). The largest area under the curve (AUC) of NIC, energy-spectrum curve slope K and DEI were higher in arterial phase than in venous phase. For identifying the intestinal activity of CD, the maximum AUC of NIC in arterial phase was 0.908, with a sensitivity of 0.833 and a specificity of 0.800, and the DEI in arterial phase had the highest sensitivity (0.944).

CONCLUSION

The NIC, energy-spectrum curve slope K and DEI can effectively distinguish the active and inactive phases of the intestinal segments of CD patients and provide good assistance for determining further treatment.

Diagnosis and staging of small intestinal neuroendocrine tumors with CT enterography and PET with Gallium-68: preoperative risk stratification protocol

PURPOSE

Pre-operative diagnosis and staging of small intestine neuroendocrine tumors (SI-NETs) remain sub-optimal, with open palpation during surgery still considered the gold standard. This limits a standardized implementation of minimally invasive surgery (MIS). The aim of this single-center retrospective study was to assess a tailored diagnostic work-up to identify candidates at low risk of undetected disease who may benefit from MIS.

METHODS

Patients diagnosed with SI-NETs between 2013 and 2022 who underwent contrast-enhanced computed tomography enterography (CTE) and Ga68-DOTATOC-positron emission tomography-CT (68 Ga DOTATATE PET/CT) preoperatively and subsequently underwent open surgical resection were included. Imaging studies were reassessed by two radiologists. Combined use of CTE and 68 Ga DOTATATE PET/CT in determining primary lesion disease burden (number of lesions) and LN disease stage (distal and proximal relative to superior mesenteric vessels) was assessed, using surgical reports and pathology as gold standard.

RESULTS

Overall, 56 patients were included. Sensitivity of CTE and 68 Ga DOTATATE PET/CT for at least one primary SI-NET was 100% and 94%, respectively. In the presence of concordance between studies, combined use of CTE and 68 Ga DOTATATE PET/CT for detection of single primary tumors improved specificity to 89% (n = 25/28) with a positive predictive value of 87.5% (n = 21/24). Distal LN disease was identified in 89.2% of cases (n = 33/37). The association of single lesion and distal LN disease was found pre-operatively in 32% of patients (n = 18).

CONCLUSION

Combined use of CTE and 68 Ga DOTATATE PET/CT enables identifying low-risk surgical candidates (single SI-NET lesions with distal LN disease).

CT energy spectral parameters of creeping fat in Crohn's disease and correlation with inflammatory activity

OBJECTIVES

Creeping fat is a kind of unique abnormal mesenteric tissue at the sites of diseased bowel of Crohn's disease. By using dual-energy CT enterography, this study aimed to evaluate the feasibility of spectral parameters in the quantitative analysis of mesenteric adipose tissue or creeping fat.

METHODS

In this study, patients with known or suspected Crohn's disease who underwent dual-energy CT enterography from March 1, 2019, to March 31, 2021, were enrolled. Among them, 40 patients with surgery and pathology-proven creeping fat were selected as the creeping fat Crohn's disease group, and 40 normal patients were selected as the control group. The quantitative spectral parameters including the slope of the Hounsfield unit curve, normalised fat-water concentration, normalised fat-iodine concentration, and normalised fat volume fraction at the enteric phases were obtained. Mann-Whitney U test, Kruskal-Wallis H test, and receiver operating characteristic curve analysis were applied to compare quantitative parameters among various groups.

RESULTS

A significant difference was observed in the slope of the Hounsfield unit curve, normalised fat-water concentration, normalised fat-iodine concentration, and normalised fat volume fraction between mesenteric adipose tissue and creeping fat with Crohn's disease at the enteric phase (all p < 0.001). The slope of the Hounsfield unit curve of creeping fat at the enteric phase had a better capability to distinguish inactive and active Crohn's disease (AUC = 0.93, p < 0.001).

CONCLUSION

Dual-energy CT enterography with quantitative spectral parameters is a potentially novel noninvasive tool for evaluating creeping fat in Crohn's disease.

CRITICAL RELEVANCE STATEMENT

Energy spectral parameters of creeping fat in Crohn's disease are significantly different from normal mesenteric adipose tissues and are correlated with inflammatory activity.

KEY POINTS

• Dual-energy CT enterography allows quantitatively assessing creeping fat with spectral parameters. • The creeping fat has distinct spectral parameters to normal mesenteric adipose. • The spectral parameters accurately differentiate active and inactive Crohn's disease.

A systematic review and meta-analysis of magnetic resonance and computed tomography enterography in the diagnosis of small intestinal tumors

Objective

To explore the potential value of magnetic resonance (MR) and computed tomography (CT) enterography in the diagnosis of small intestinal tumor (SIT).

Methods

Articles reporting on the diagnosis of SIT by MR and CT enterography deposited in Chinese and foreign literature databases were identified and evaluated using the quality assessment of diagnostic accuracy studies (QUADAS). The diagnostic data extracted from the articles were adopted for meta-analysis using Meta-disc 1.40 software. Analysis was undertaken to compare the sensitivity, specificity, positive and negative likelihood ratios, and the diagnostic odds ratio (DOR) of MR and CT enterography in the diagnosis of SIT. The diagnostic values of the two imaging methods were analyzed by summary receiver operating characteristic (SROC) curves. The meta-analysis was registered at INPLASY (202380053).

Results

A total of eight articles, including 551 cases of SIT were included in this analysis. The pooled sensitivity and specificity of MR enterography were 0.92 (95% CI [0.89-0.95]) and 0.81 (95% CI [0.74-0.86]), respectively, whilst CT enterography had a sensitivity of 0.93 (95% CI [0.90-0.95]) and a specificity of 0.83 (95% CI [0.76-0.88]). For MR enterography, the combined positive likelihood ratio was 4.90 (95% CI [3.50-6.70]), the combined negative likelihood ratio was 0.10 (95% CI [0.07-0.14]), and the area under the receiver operating characteristic curve (AUROC) was 0.940. For CT enterography, the corresponding values were 5.40 (95% CI [3.90-7.40]), 0.08 (95% CI [0.06-0.12]), and 0.950, respectively. When the pretest probability for MR was assumed to be 50%, the posterior probabilities for positive and negative results were calculated as 83% and 9%, respectively. For CT enterography with a pretest probability of 50%, the posterior probabilities of positive and negative results were 84% and 8%, respectively.

Conclusion

MR and CT enterography have high accuracy in the diagnosis of SIT and have a valuable role in the diagnosis and management of these tumors.

Where does capsule endoscopy fit in the diagnostic algorithm of small bowel intussusception?

INTRODUCTION

The investigation of small bowel (SB) intussusception is variable, reflecting the lack of existing standards. The aim of this study was to understand the role of small bowel capsule endoscopy (SBCE) to investigate this pathology.

METHODOLOGY

This was a retrospective multi-centre study. Patients with intussusception on SBCE and those where SBCE was carried out due to findings of intussusception on radiological investigations were included. Relevant information was collected.

RESULTS

Ninety-five patients (median age 39+/-SD19.1 years, IQR 30) were included. Radiological investigations were carried out in 71 patients (74.7%) prior to SBCE with intussusception being present in 60 patients on radiological investigations (84.5%). Thirty patients (42.2%) had intussusception on radiological investigations followed by a normal SBCE. Ten patients (14.1%) had findings of intussusception on radiological investigations, a normal SBCE and repeat radiological investigations that were also normal. Abnormal findings were noted on SBCE that could explain intussusception on imaging in (16 patients) 22.5% of patients. Five patients (5.3%) underwent radiological investigations and SBCE to investigate coeliac disease and intussusception. None had associated malignancy. Four patients (4.2%) underwent SBCE to investigate familial polyposis syndromes and went on to SB enteroscopy and surgery accordingly. Most patients (n = 14; 14.8%) with intussusception on initial SBCE (without prior radiological imaging) had suspected SB bleeding (n = 10, 10.5%). Four patients (4.2%) had additional findings of a mass on CT scan and went on to have surgery.

CONCLUSION

SBCE should be used to complement radiology when investigating intussusception. It is a safe non-invasive test that will minimise unnecessary surgery. Additional radiological investigations following a negative SBCE in cases of intussusception noted on initial radiological investigations are unlikely to yield positive findings. Radiological investigations following intussusception noted on SBCE in case of patients presenting with obscure gastrointestinal bleeding, may yield additional findings.

Imaging of Strictures in Crohn's Disease

Crohn's disease (CD) is a chronic inflammation of the digestive tract, and it frequently affects young patients. It can involve any intestinal segment, even though it frequently affects the distal ileum. Up to 80% of patients with CD present with inflammatory behavior, and 5% to 28% develop stricturing disease. Based on the predominant mechanism causing them, strictures can be categorized as inflammatory, fibrotic, or mixed. Determining the relative amounts of inflammation and fibrosis in a stricture can influence treatment decisions. Imaging is an extremely useful tool in patients with small bowel stricturing CD to confirm the diagnosis and to evaluate disease characteristics, usually using CT or MRI. The aim of this paper is to describe how imaging can evaluate a patient with small bowel CD stricture.

Evaluation of symptomatic small bowel stricture in Crohn's disease by double-balloon endoscopy

PURPOSE

To assess the efficacy of double-balloon endoscopy (DBE) for the detection of small-bowel strictures in Crohn's disease (CD).

METHODS

This tertiary-referral hospital cohort study was conducted between January 2018 and May 2022. CD patients with symptoms of small-bowel stricture were enrolled sequentially. All of the patients were subjected to both computed tomography enterography (CTE) and DBE, and their symptoms of stricture were assessed using the Crohn's Disease Obstructive Score (CDOS). The diagnostic yield of DBE was compared to that of CTE, and the relationship between the DBE findings and CDOS was investigated. The factors influencing the DBE diagnosis were examined using Cox regression analysis.

RESULTS

This study included 165 CD patients. The CDOS scores were higher in 95 patients and lower in 70 patients. DBE detected 92.7% (153/165) and CTE detected 85.5% (141/165) of the strictures. The DBE diagnostic yields were 94.7% (90/95) in the high CDOS patients and 91.4% (64/70) in the low CDOS patients (P = 0.13). Patients with a history of abdominal surgery and abscess had a lower diagnosis rate in the multivariate analysis.

CONCLUSION

DBE has been demonstrated to be an efficient diagnostic method for detecting small bowel strictures in CD patients. Additionally, there was no difference in the diagnostic yields between patients with low and high obstructive scores.

Crohn's disease phenotype analysis with iodine density from dual-energy CT enterography

PURPOSE

To compare dual-source dual-energy CT enterography (dsDECTE) obtained iodine density (I) (mg/mL) and I normalized to the aorta (I%) with Crohn's disease (CD) phenotypes defined by the SAR-AGA small bowel CD consensus statement.

METHODS

Fifty CD patients (31 male, 19 female; mean [SD] age: 50.4 [15.2] years) who underwent dsDECTE were retrospectively identified. Two abdominal radiologists assigned CD phenotypes: no active inflammation (group-2), active inflammation without (group-3) or with luminal narrowing (group-4), stricture with active inflammation (group-5), stricture without active inflammation (group-1), and penetrating disease (group-6). Semiautomatic prototype software was used to determine the median I and I% of CD-affected small bowel mucosa for each patient. The means of the I and I% medians were compared among 4 groups ("1 + 2", "3 + 4", "5", "6") using one-way ANOVA (significance level 0.05 for each outcome) for each outcome individually followed by Tukey's range test for pairwise comparisons with adjusted p-values (overall alpha = 0.05).

RESULTS

Mean [SD] I was 2.14 [1.07] mg/mL for groups 1 + 2 (n = 16), 3.54 [1.71] mg/mL for groups 3 + 4 (n = 15), 5.5 [3.27] mg/mL for group- "5" (n = 9), and 3.36 [1.43] mg/mL for group-"6" (n = 10) (ANOVA p = .001; group "1 + 2" versus "5" adj-p = .0005). Mean [SD] I% was 21.2 [6.13]% for groups 1 + 2, 39.47 [9.71]% for groups 3 + 4, 40.98 [11.76]% for group-5, and 35.01 [7.58]% for group-6 (ANOVA p < .0001; groups "1 + 2" versus "3 + 4" adj-p < .0001, group "1 + 2" versus "5" adj-p < .0001, and groups "1 + 2" versus "6" adj-p = .002).

CONCLUSION

Iodine density obtained from dsDECTE significantly differed among CD phenotypes defined by SAR-AGA, with I (mg/mL) increasing with phenotype severity and decreasing for penetrating disease. I and I% can be used to phenotype CD.

Updates in the diagnosis and management of small-bowel tumors

Small-bowel tumors represent a rare entity comprising 0.6% of all new cancer cases in the US, and only 3% of all gastrointestinal neoplasms. They are a heterogenous group of neoplasms comprising of about forty different histological subtypes with the most common being adenocarcinoma, neuroendocrine tumors, stromal tumors and lymphomas. Their incidence has been reportedly increasing over recent years, partly owing to the advances and developments in the diagnostic modalities. Small-bowel capsule endoscopy, device assisted enteroscopy and dedicated small-bowel cross-sectional imaging are complimentary tools, supplementing each other in the diagnostic process. Therapeutic management of small-bowel tumors largely depends on the histological type and staging at diagnosis. The aim of the present review article is to discuss relevant advances in the diagnosis and management of small-bowel tumors.

Can preoperative CT/MR enterography preclude the development of Crohn's disease-like pouch complications in ulcerative colitis patients undergoing J pouch surgery?

AIM

We aimed to determine whether ulcerative colitis patients with preoperative negative computed tomography or magnetic resonance enterography (CTE/MRE) were less likely to develop Crohn's disease-like pouch complications (CDLPC) and establish risk factors and predictors for developing CDLPC.

METHODS

This was a single centre retrospective analysis of patients with ulcerative colitis (UC) and inflammatory bowel disease unclassified (IBDU) who underwent total proctocolectomy with ileal J-pouch between January 2010 and December 2020. The study group comprised patients with negative preoperative CTE/MRE and the control group included patients operated without preoperative CTE/MRE.

RESULTS

A total of 131 patients were divided into the negative CTE/MRE study group (76 [58%] patients) and control group (55 [42%] patients). There were no significant differences in incidence rates (21% vs. 23.6%, p = 0.83), time to developing CDLPC from ileostomy closure (22.3 vs. 23.8 months; p = 0.81), pouchitis rates (23.6% vs. 27.2%; p = 0.68), or pouch failure rates (5.2 vs. 7.2; p = 0.71). Multivariate Cox regression analysis showed backwash ileitis (HR 4.1; p = 0.03, CI: 1.1-15.1), severe pouchitis (HR 3.4; p = 0.039, CI: 1.0-10.9), and history of perianal disease (HR 3.4; p = 0.017, CI: 1.4-39.6) were independent predictors for CDLPC.

CONCLUSIONS

Negative findings on MRE/CTE prior to J-pouch surgery in ulcerative colitis should be interpreted with caution as it is does not reliably exclude or predict development of CDLPC. These patients should be preoperatively counselled concerning the possibility of developing CDLPC regardless of lack of positive findings on preoperative CTE/MRE. Patients with backwash ileitis with a previous history of perianal disease should be informed of the potentially increased risk of developing such complications.

Improved comprehensive evaluation of Crohn's disease activity by intestinal computed tomography enterography combined with endoscopy and biochemical indicators

BACKGROUND AND STUDY AIMS

The treatment approach for Crohn's disease (CD) is focused on mucosal healing and resolution of transmural inflammation. The aim of this study is to evaluate the correlation between computed tomography enterography (CTE) and other treatments, in particular, endoscopy and biochemical indicators, in newly diagnosed patients with CD.

PATIENTS AND METHODS

One hundred twenty-three patients with CD who received CTE in Xiangya Hospital, Central South University, China, from April 2017 to April 2019 were included. The clinical case data and imaging results were retrospectively reviewed. The clinical activity of CD was determined by the Crohn's disease activity index (CDAI) score and biochemical indicators. The relationships between CTE and endoscopy, CDAI score, and inflammatory markers were evaluated.

RESULTS

The diagnostic rate of CTE of the 123CD patients was 68.3% (84/123). Logistic regression analysis showed that the specific CTE manifestations related to CD activity were intestinal wall stratification, comb sign, and abdominal abscesses (P < 0.05). Spearman's rank correlation analysis showed that inflammatory markers positively correlated with different CTE imaging manifestations.

CONCLUSION

Intestinal CTE combined with endoscopy and biochemical indicators is both comprehensive and effective in evaluating the condition of CD patients.

Imaging Evaluation of Inflammatory Bowel Disease Complications

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that can progress to fibrostenotic and penetrating complications. Cross-sectional imaging is often needed for accurate diagnosis of IBD complication and for planning the appropriate management strategy. Computed tomography enterography, magnetic resonance enterography, and IBD ultrasound have become key tools for clinicians and interventional endoscopists. This article highlights and discusses various radiologic imaging techniques and their application to the diagnosis and management of IBD complications.

Crohn's disease active inflammation assessment with iodine density from dual-energy CT enterography: comparison with endoscopy and conventional interpretation

PURPOSE

To compare terminal ileum (TI) mucosal iodine density obtained at dual-energy CT enterography (DECTE) with conventional CT interpretation and endoscopy in patients with Crohn's disease (CD).

MATERIALS AND METHODS

Twenty-three CD patients (14 men; mean[SD] age:48.1[16.7] years) with endoscopy within 30 days of DECTE were retrospectively identified. An inflammatory bowel disease gastroenterologist reviewed endoscopic images. Two radiologists qualitatively assessed the presence of active TI inflammation. Mean iodine density normalized to the aorta (I%), mean absolute iodine density (I), and iodine density standard deviation (I_SD) from the distal 2 cm ileum (TI) mucosa obtained using semiautomatic prototype software were compared with endoscopic assessment using Mann Whitney tests. The optimal threshold I% and I were determined from receiver operating curves (ROC). Sensitivity and specificity of conventional interpretation and determined iodine thresholds were compared using McNemar's test. Inter-reader agreement was assessed using kappa. A p < 0.05 indicated statistical significance.

RESULTS

Twelve (52.1%) patients had endoscopic active inflammation. I% was 37.9[13.3]% for patients with and 21.7[7.5]% for patients without endoscopic active inflammation (p = 0.001). The optimal ROC threshold 24.6% had 100% sensitivity and 81.8% specificity (AUC = 0.909, 95% CI 0.777-1). I was 2.44[0.73]mg/mL for patients with and 1.77[1.00]mg/mL for patients without active endoscopic inflammation (p = 0.0455). The optimal ROC threshold 1.78 mg/mL I had 91.7% sensitivity and 63.6% specificity (AUC = 0.75, 95% CI 0.532-0.968). I_SD was similar for patients with and without endoscopic active inflammation (0.82[0.33]mg/mL and 0.77[0.28]mg/mL, respectively, p = 0.37). Conventional interpretation sensitivity and specificity (R1/R2) were 83.3%/91.7% and 72.7%/54.5%, respectively (all p > 0.05) with moderate inter-reader agreement (Κ = 0.542[95% CI 0.0202-0.088]).

CONCLUSION

Mean normalized iodine density is highly sensitive and specific for endoscopic active inflammation. DECTE could be considered as a surrogate to endoscopy in CD patients. Despite trends towards improved sensitivity and specificity compared with conventional interpretation, future larger studies are needed.

CT enterography for evaluation of disease activity in patients with ileocolonic Crohn's disease

BACKGROUND

CT enterography (CTE) is used routinely for assessment of activity and severity in Crohn's disease (CD), but there are few CTE scoring systems. The aim of this study was to develop a quantitative CTE scoring system for ileocolonic Crohn's disease activity.

METHODS

Forty-nine CD patients with ileocolonic involvement were retrospectively included between March 2015 and May 2018. All patients underwent CTE and ileocolonoscopy. Mural hyperenhancement and mural thickening at CTE were scored quantitatively, while mural stratification, submucosal fat deposition, comb sign, perienteric fat hypertrophy and mesenteric fibrofatty proliferation were qualitative variables. A Tobit regression model was applied for assessing the association between Crohn's disease endoscopic index of severity (CDEIS) and CTE variables.

RESULTS

A total of 280 intestinal segments were evaluated. Independent predictors for CDEIS were mural thickness (p < 0.001), mural stratification (p < 0.001) and comb sign (p = 0.002). In order to quantify disease activity based on CTE findings in each segment, a simplified CT enterography index of activity (CTEIA) was derived from logistic regression analysis. The formula was as follows: CTEIA (segment) = 2.1 mural thickness(mm) + 9.7 mural stratification + 5.2 comb sign. There was a high and significant correlation coefficient between CDEIS and CTEIA (r = 0.779, p < 0.001) for per-segment analysis. The model for the detection of ulcerative lesions in the colon and terminal ileum achieved an area under the receiver-operating curve of 0.901 using a cut-off point of 6.25.

CONCLUSIONS

CTEIA is a new qualitative tool for evaluation of ileocolonic Crohn's disease, which need to be validated in further studies.

Is the Mixed Use of Magnetic Resonance Enterography and Computed Tomography Enterography Adequate for Routine Periodic Follow-Up of Bowel Inflammation in Patients with Crohn's Disease?

OBJECTIVE

Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are considered substitutes for each other for evaluating Crohn's disease (CD). However, the adequacy of mixing them for routine periodic follow-up for CD has not been established. This study aimed to compare MRE alone with the mixed use of CTE and MRE for the periodic follow-up of small bowel inflammation in patients with CD.

MATERIALS AND METHODS

We retrospectively compared two non-randomized groups, each comprising 96 patients with CD. One group underwent CTE and MRE (MRE followed by CTE or vice versa) for the follow-up of CD (interval, 13-27 months [median, 22 months]), and the other group underwent MRE alone (interval, 15-26 months [median, 21 months]). However, these two groups were similar in clinical characteristics. Three independent readers from three different institutions determined whether inflammation had decreased, remained unchanged, or increased within the entire small bowel and the terminal ileum based on sequential enterography of the patients after appropriate blinding. We compared the two groups for inter-reader agreement and accuracy (terminal ileum only) using endoscopy as the reference standard for enterographic interpretation.

RESULTS

The inter-reader agreement was greater in the MRE alone group for the entire small bowel (intraclass correlation coefficient [ICC]: 0.683 vs. 0.473; p = 0.005) and the terminal ileum (ICC: 0.656 vs. 0.490; p = 0.030). The interpretation accuracy was higher in the MRE alone group without statistical significance (70.9%-74.5% vs. 57.9%-64.9% in individual readers; adjusted odds ratio = 3.21; p = 0.077).

CONCLUSION

The mixed use of CTE and MRE was inferior to MRE alone in terms of inter-reader reliability and could probably be less accurate than MRE alone for routine monitoring of small bowel inflammation in patients with CD. Therefore, the consistent use of MRE is favored for this purpose.

The Evaluation of Transmural Healing by Low-dose Computed Tomography Enterography in Patients with Crohn's Disease

Objective Transmural healing (TH) has been attracting attention as a new therapeutic target for Crohn's disease, but there are few clinical data on TH in Japan. We introduced low-dose computed tomography enterography (CTE) as a monitoring method for Crohn's disease and retrospectively investigated the accuracy of evaluating TH by CTE. Methods Among Crohn's disease patients who underwent low-dose CTE at our hospital from January 2009 to March 2021, 122 patients who underwent colonoscopy or balloon endoscopy within 2 weeks were included. Results of radiological and endoscopic examinations were reviewed independently by radiologists and gastrointestinal endoscopists, respectively. The concordance rate of the diagnosis between CTE and endoscopy was evaluated. Results Twenty-six patients (21.3%) achieved TH, and the kappa index was 0.743. On comparing the TH and non-TH groups, the Crohn's disease activity index (p=0.02), endoscopic healing rate (p<0.001), serum albumin (p=0.043), and serum C-reactive protein level (p=0.018) showed significant differences. Among the 122 patients, 69 (56.5%) showed concordance between the diagnosis of CTE and endoscopy, and 22 (18.0%) achieved both TH and endoscopic healing. Conclusion This study provides real-world data on Crohn's disease evaluated with low-dose CTE in Japan. The TH criterion used in this study has a high kappa coefficient and can be used reproducibly in many institutions.

Efficiency of dual-energy computed tomography enterography in the diagnosis of Crohn's disease

Background

This retrospective study aimed to investigate the usefulness of the optimized kiloelectron volt (keV) for virtual monoenergetic imaging (VMI) combined with iodine map in dual-energy computed tomography enterography (DECTE) in the diagnosis of Crohn’s disease (CD).

Methods

Seventy-two patients (mean age: 41.89 ± 17.28 years) with negative computed tomography enterography (CTE) were enrolled for investigating the optimized VMI keV in DECTE by comparing subjective and objective parameters of VMIs that were reconstructed from 40 to 90 keV. Moreover, 68 patients (38.27 ± 15.10 years; 35 normal and 33 CD) were included for evaluating the diagnostic efficacy of DECTE iodine map at the optimized VMI energy level and routine CTE for CD and active CD. Statistical analysis for all data was conducted.

Results

Objective and subjective imaging evaluations showed the best results at 60 keV for VMIs. The CT values of the normal group, active subgroup, and CD group during the small intestinal phase at routine 120 kVp or 60 keV VMI had significant differences. The diagnostic efficacy of an iodine map was the best when NIC = 4% or fat value = 45.8% for CD, whereas NIC < 0.35 or the fat value < 0.38 for active CD. The combined routine CTE and optimized VMI improved the diagnostic efficacy (P < 0.001).

Conclusions

VMI at 60 keV provided the best imaging quality on DECTE. NIC and fat value provided important basis for active CD evaluation. Routine CTE combined with VMI at 60 keV improved the diagnostic efficiency for CD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12880-021-00716-y.

CT and MRI Evaluations in Crohn's Complications: A Guide for the Radiologist

Inflammatory bowel diseases (IBD) are a group of chronic inflammatory intestinal conditions with unknown etiology. Crohn's disease (CD) and ulcerative colitis (UC) are the two main types of IBD and they have some interchangeable and some different clinical and pathological characteristics. When diagnosis is performed for the first time, the majority of CD patients have a predominant inflammatory condition. As the disease progresses most patients experience the development of complications, such as abscesses, fistulas, perforation, strictures, and others. Both computed tomography (CT) and Magnetic Resonance Imaging (MRI) allow great view of the whole length of the intestinal tract together with the eventual extra-and intra-intestinal complications. MR enterography (MRE) and CT enterography (CTE), performed after oral administrations of contrast medium, have similar diagnostic accuracy for the diagnosis of CD and its complications. Even though CT is still the most familiar diagnostic technique used for studying CD worldwide, MRE have several important benefits that are leading to rapid increase in its employment in the last years. In particular, MRE allows a superior soft tissue contrast resolution compared to CT, offering a better visualization of bowel wall and its inflammatory and fibrotic characteristics. Moreover, Pelvic Magnetic Resonance is the principal technique in patients with perianal disease due to its ability of providing precise and fine detail images of the sphincter complex, which are crucial for evaluating pelvic disease. In this paper we describe common and uncommon complications in patients with CD, and explain how to identify their findings in CT and MR exams.

Combined Use of Computed Tomography Enterography/Enteroclysis and Capsule Endoscopy Improves the Accuracy of Diagnosis of Small Bowel Bleeding

Objective CT enterography/enteroclysis (CTE) is listed in the clinical practice guidelines as a method for diagnosing small bowel bleeding, as is capsule endoscopy (CE), but there are no real-world data yet available on CTE in Japan. This study aimed to investigate the diagnostic ability of CTE and long-term prognosis after CTE in Japan. Patients We conducted a retrospective cohort study of patients suspected of having small bowel bleeding who underwent both CTE and CE within 30 days between April 2008 and March 2019. The number of patients free from rebleeding for up to 24 months was thus determined. Results Seventy-one patients were extracted from the database. The 43 patients (60.6%) with a definite and suspicious source of bleeding in the small bowel were detected by CTE. When the 31 patients with a definite source of bleeding in the small bowel were analyzed, the sensitivity of CTE was 19/31 (61.3%) and that of CE was 24/31 (77.4%), thus indicating no significant difference (p=0.332). However, the sensitivity when CTE and CE were used in combination was 30/31 (96.8%), which was significantly higher than that of CE alone (p=0.0412). No rebleeding was observed in the CTE and CE negative group (p=0.0965). Conclusion The combined use of CTE and CE increased the detection rate of small bowel bleeding. Therefore, in patients with suspected tumor/polyp lesions, not only CE, but also CTE should be performed. This study provides the first real-world data on the diagnostic accuracy of CTE for small bowel bleeding in Japan.

Prospective comparison of diffusion-weighted magnetic resonance enterography and contrast enhanced computed tomography enterography for the detection of ileocolonic Crohn's disease

BACKGROUND AND AIMS

Crohn's disease (CD) is a chronic and relapsing course with various status of different segments, and there were no investigations comparing the lesion detection between magnetic resonance (MR) and computed tomography (CT) in term of the severity of CD. We aim to assess the performances of diffusion-weighted MR enterography (DW-MRE) and contrast enhanced CT enterography (CTE) for detecting different grade lesions in ileocolonic CD.

METHODS

Forty-one consecutive patients finally diagnosed with ileocolonic CD were included. All the patients prospectively underwent DW-MRE, contrast enhanced CTE, and ileocolonoscopy within 2 weeks. DW-MRE and CTE images were interpreted for the presence or absence of active CD segments by two experienced radiologists independently. Ileocolonic segments (terminal ileum, right colon, transverse colon, left colon, and rectum) were graded as inactive (0-2), mild (3-6), or moderate-severe (≥ 7) by the simplified endoscopic score for CD (SES-CD). Diagnostic efficiencies of DW-MRE and CTE for mild and/or moderate-severe CD segments were calculated and compared, using ileocolonoscopy as reference standard.

RESULTS

According to SES-CD, 190 ileocolonic segments from 41 CD patients were scored as 91 inactive, 68 mild, and 31 moderate-severe CD lesions. The sensitivity of DW-MRE for detecting active from inactive segments was higher than that of CTE, and the specificities of them had no significant differences. As for the subgroup analysis, DW-MRE was more sensitive for mild CD lesions than CTE (76.5% vs 60.3%; P = 0.019), while the sensitivities for moderate-severe CD were similar between these two modalities (96.8% for DW-MRE and 93.5% for CTE; P = 1.00).

CONCLUSIONS

Both DW-MRE and CTE had comparably excellent performances for moderate-severe CD detection; DW-MRE demonstrated better sensitivity in mild lesions compared with CTE and could be more suitable for the diagnosis of mild CD.

Imaging Findings of Ileal Inflammation at Computed Tomography and Magnetic Resonance Enterography: What do They Mean When Ileoscopy and Biopsy are Negative?

BACKGROUND AND AIMS

Our goal was to determine the importance of ileal inflammation at computed tomography or magnetic resonance enterography in Crohn's disease patients with normal ileoscopy.

METHODS

Patients with negative ileoscopy and biopsy within 30 days of CT or MR enterography showing ileal inflammation were included. The severity [0-3 scale] and length of inflammation within the distal 20 cm of the terminal ileum were assessed on enterography. Subsequent medical records were reviewed for ensuing surgery, ulceration at ileoscopy, histological inflammation, or new or worsening ileal inflammation or stricture on enterography. Imaging findings were classified as: Confirmed Progression [subsequent surgery or radiological worsening, new ulcers at ileoscopy or positive histology]; Radiologic Response [decreased inflammation with medical therapy]; or Unlikely/Unconfirmed Inflammation.

RESULTS

Of 1471 patients undergoing enterography and ileoscopy, 112 [8%] had imaging findings of inflammation with negative ileoscopy, and 88 [6%] had negative ileoscopy and ileal biopsy. Half [50%; 44/88] with negative biopsy had moderate/severe inflammation at enterography, with 45%, 32% and 11% having proximal small bowel inflammation, stricture or fistulas, respectively. Two-thirds with negative biopsy [67%; 59/88] had Confirmed Progression, with 68%, 70% and 61% having subsequent surgical resection, radiological worsening or ulcers at subsequent ileoscopy, respectively. Mean length and severity of ileal inflammation in these patients was 10 cm and 1.6. Thirteen [15%] patients had Radiologic Response, and 16 [18%] had Unlikely/Unconfirmed Inflammation.

CONCLUSION

Crohn's disease patients with unequivocal imaging findings of ileal inflammation at enterography despite negative ileoscopy and biopsy are likely to have active inflammatory Crohn's disease. Disease detected by imaging may worsen over time or respond to medical therapy.

Assessing Small Bowel Stricturing and Morphology in Crohn's Disease Using Semi-automated Image Analysis

BACKGROUND

Evaluating structural damage using imaging is essential for the evaluation of small intestinal Crohn's disease (CD), but it is limited by potential interobserver variation. We compared the agreement of enterography-based bowel damage measurements collected by experienced radiologists and a semi-automated image analysis system.

METHODS

Patients with small bowel CD undergoing a CT-enterography (CTE) between 2011 and 2017 in a tertiary care setting were retrospectively reviewed. CT-enterography studies were reviewed by 2 experienced radiologists and separately underwent automated computer image analysis using bowel measurement software. Measurements included maximum bowel wall thickness (BWT-max), maximum bowel dilation (DIL-max), minimum lumen diameter (LUM-min), and the presence of a stricture. Measurement correlation coefficients and paired t tests were used to compare individual operator measurements. Multivariate regression was used to model identification of strictures using semi-automated measures.

RESULTS

In 138 studies, the correlation between radiologists and semi-automated measures were similar for BWT-max (r = 0.724, 0.702), DIL-max (r = 0.812, 0.748), and LUM-min (r = 0.428, 0.381), respectively. Mean absolute measurement difference between semi-automated and radiologist measures were no different from the mean difference between paired radiologists for BWT-max (1.26 mm vs 1.12 mm, P = 0.857), DIL-max (2.78 mm vs 2.67 mm, P = 0.557), and LUM-min (0.54 mm vs 0.41 mm, P = 0.596). Finally, models of radiologist-defined intestinal strictures using automatically acquired measurements had an accuracy of 87.6%.

CONCLUSION

Structural bowel damage measurements collected by semi-automated approaches are comparable to those of experienced radiologists. Radiomic measures of CD will become an important new data source powering clinical decision-making, patient-phenotyping, and assisting radiologists in reporting objective measures of disease status.

Computed tomography and magnetic resonance enterography protocols and techniques: survey of the Society of Abdominal Radiology Crohn's Disease Disease-Focused Panel

PURPOSE

To survey Society of Abdominal Radiology Crohn's Disease (CD) Disease-Focused Panel (DFP) members to understand state-of-the-art CT/MR enterography (CTE/MRE) protocols and variability between institutions.

METHODS

This study was determined by an institutional review board to be "exempt" research. The survey consisted of 70 questions about CTE/MRE patient preparation, administration of contrast materials, imaging techniques, and other protocol details. The survey was administered to DFP members using SurveyMonkey® (Surveymonkey.com). Descriptive statistical analyses were performed.

RESULTS

Responses were received from 16 DFP institutions (3 non-USA, 2 pediatric); 15 (94%) were academic/university-based. 10 (63%) Institutions image most CD patients with MRE; 4 (25%) use CTE and MRE equally. Hypoperistaltic medication is given for MRE at 13 (81%) institutions versus only 2 (13%) institutions for CTE. Most institutions have a technologist or nurse monitor oral contrast material drinking (n = 12 for CTE, 75%; n = 11 for MRE, 69%). 2 (13%) institutions use only dual-energy capable scanners for CTE, while 9 (56%) use either a single-energy or dual-energy scanner based on availability. Axial CTE images are reconstructed at 2-3 mm thickness at 8 (50%) institutions, > 3 mm at 5 (31%), and < 2 mm at 3 (19%) institutions. 13 (81%) institutions perform MRE on either 1.5 or 3T scanners without preference. All institutions perform MRE multiphase postcontrast imaging (median = 4 phases), ranging from 20 to 600 s after contrast material injection.

CONCLUSION

CTE and MRE protocol knowledge from DFP institutions can help radiology practices optimize/standardize protocols, potentially improving image quality and patient outcomes, permitting objective comparisons between examinations, and facilitating research.

The efficacy of new oral contrast mixture for computed tomography enterography

Purpose

To show the reliabilities of the new mixture (composed of water, methylcellulose, lactulose, locust bean gum, and sorbitol) and to compare the luminal distension and radiological confidence scores of this solution with water-lactulose mixture.

Material and methods

Computed tomography enterography (CTE) images in a three-year period were included randomly in our institutional review board-approved and retrospective study. Ninety-one patients drank a lactulose and water mixture (Group 1), and 54 patients drank the new mixture (Group 2). Patients who drank the oral contrast agent were taken to a 64-detector row multiple detector computed tomography machine. Coronal and sagittal reformatted images were also formed. The gastrointestinal tract was divided into 11 segments for scoring. Each segment was graded for distensional and radiological confidence. CTE images were evaluated by two radiologists.

Results

Inter- and intra-reader reliabilities were good or excellent for all gastrointestinal segments in both groups (p < 0.001). The best κ values were obtained in sigmoid colon assessments. Lower agreement values were detected in duodenum and jejunum scores. The new mixture group (Group 2) showed better results than Group 1 for ileum and colonic segments according to distension and confidence scorings.

Conclusions

Inter- and intra-reader reliabilities of the new mixture were good or excellent for CTE. The new mixture seems to be more efficient and reliable for ileum and colon. The new mixture can increase bowel distention, radiological confidence, and quality in CTE evaluations.

Imaging Features Associated With Failure of Nonoperative Management of Intraabdominal Abscesses in Crohn Disease

BACKGROUND

Intraabdominal abscess management decisions in the treatment of Crohn disease (CD) can be challenging. Our aim was to determine the effect of clinical, medication use, and imaging disease characteristics on the need for future surgical management.

METHODS

A retrospective chart review was performed in patients with CD hospitalized for abscess confirmed by imaging between 2008 and 2016. Selection criteria included nonoperative management with intravenous antibiotics at the index hospitalization and a minimum of 2 years of follow up. Demographic, disease, and medication history were extracted from electronic medical records. Radiographic disease features were assessed by an expert abdominal radiologist, blinded to clinical data. The primary outcome was resection of the bowel segment involving the abscess within 2 years of index hospitalization. Cox proportional hazards regression and statistical methods were performed using SAS 9.4.

RESULTS

Of the 121 patients meeting the selection criteria, 36.4% avoided surgery after 2 years of follow up. On adjusted multivariable analysis, disease-activity factors including bowel wall thickness (HR 3.08, 95% CL 1.20-6.21), disease length (HR 2.67, 95% CL 1.40-6.20), bowel dilation (HR 2.19, 95% CL 1.02-4.68), and abscess size of greater than 6 cm (HR 2.47, 95%CL 1.17-5.21) were independent risk factors for future surgery in patients not undergoing immediate bowel resection for abscess management. Biologic use and percutaneous drainage were not risk factors for ultimate surgical management.

CONCLUSIONS

Radiographic CD features and abscess size over 6 cm are predictors of ultimately requiring bowel resection. Radiographic measures may help stratify patients to immediate surgery or conservative management for intraabdominal CD-related abscesses.

The potential role of CT enterography and gastrointestinal ultrasound in the evaluation of anti-tubercular therapy response of intestinal tuberculosis: a retrospective study

Background

Accurate evaluation of anti-tubercular therapy (ATT) responses is crucial for both diagnosis and treatment of intestinal tuberculosis (ITB). Little is known about the role of cross-sectional imaging techniques in ITB follow-up assessment. We aimed to investigate the accuracy of cross-sectional imaging modalities, CT enterography (CTE) and gastrointestinal ultrasound (GIUS), in the evaluation of ATT responses in ITB patients.

Methods

Patients diagnosed with ITB and followed up by CTE and/or GIUS were retrospectively searched in the databases. Clinical, imaging, laboratory and endoscopic data were collected at baseline and the first follow-up visit. Responses were graded as good, partial and no response based on protocols described in the literature and by our institution. CTE evaluation was based on changes in the lesion area, mural thickness, enhancement patterns and lymph nodes, while GIUS evaluation was based on changes in bowel wall morphology and the Limberg score. Clinical evaluation was used as the gold-standard evaluation method, which was determined by a comprehensive impression of endoscopic changes along with symptomatic improvement and laboratory tests, with imaging results masked.

Results

Twenty patients with ITB were enrolled in our study. The first follow-up time was from 2 to 12 months (average 6 months). According to the gold standard evaluation, 11 patients were evaluated as having a good ATT response, while 9 had a partial response. A total of 18 patients were followed up by CTE, while 7 were followed up by GIUS, depending on medical and/or financial considerations. The accuracy of CTE and GIUS was 83% (15/18) and 85.7% (6/7), respectively. The sensitivity, specificity, PPV and NPV of CTE were 88.9, 77.8, 80 and 87.5%, respectively. Moreover, the sensitivity, specificity, PPV and NPV of GIUS were 100, 50, 83.3 and 100%, respectively. By combining the results of CTE and GIUS results, the overall accuracy was 90%, with sensitivity and specificity of 91.7 and 87.5%, respectively.

Conclusion

To our knowledge, this is the first study exploring the accuracy of the cross-sectional imaging modalities CTE/GIUS in the evaluation of ATT responses. Our results indicated their promising application prospect in clinical practice as a non-invasive and cost-effective approach.

Electronic supplementary material

The online version of this article (10.1186/s12876-019-1030-0) contains supplementary material, which is available to authorized users.

Feasibility study using iodine quantification on dual-energy CT enterography to distinguish normal small bowel from active inflammatory Crohn's disease

BACKGROUND

Assessment of Crohn's disease (CD) activity is important to identify patients with active inflammation for therapy management. Quantitative analysis can provide objective measurement of disease presence.

PURPOSE

To evaluate the feasibility of quantitative analysis of contrast-enhanced dual-energy computed tomography (DECT) data in detection of small bowel inflammation in patients with CD with an emphasis on iodine quantification.

MATERIAL AND METHODS

DECT enterography was prospectively performed in 20 patients with active CD and in 20 healthy individuals, as the control group. Iodine overlay images were created. Wall thickness, attenuation, absolute iodine density, relative iodine density, and fat fraction were measured in the terminal ileum of all patients by two radiologists. Intraclass correlation coefficients were calculated to assess inter-rater agreement. Parameters were compared between patient groups using mixed model analysis. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

Both absolute and relative iodine density were significantly higher in active disease than in normal small bowel (all P < 0.001). In contrast, measurement of fat fraction was not significantly different in affected terminal ileal loops compared to normal terminal ileum ( P = 0.075). ROC analysis demonstrated a similar excellent diagnostic accuracy of wall thickness, attenuation, and absolute and relative iodine density with area under the ROC curve (AUC) values in the range of 0.96 for attenuation to 1 for relative iodine density.

CONCLUSION

DECT with iodine quantification can be used in distinguishing normal small bowel from active inflammatory CD. Further research should investigate the value of iodine quantification in grading CD activity and in monitoring therapeutic response.

Findings of CT-Derived Bone Strength Assessment in Inflammatory Bowel Disease Patients Undergoing CT Enterography in Clinical Practice

BACKGROUND

Inflammatory bowel disease (IBD) patients are at risk of developing complications from metabolic bone disease, but the exact prevalence is unknown. We evaluated fracture risk in IBD patients using (1) biomechanical CT analysis (BCT) using bone strength and bone mineral density (BMD), (2) Cornerstone guidelines, and (3) other clinical features predicting fracture risk.

METHODS

A retrospective review of consecutive IBD patients who underwent CT enterography (CTE) with BCT from March 2014 to March 2017 was performed. Measured outcomes were overall fracture risk classification (not increased, increased, or high) and femoral neck BMD World Health Organization classification (normal, osteopenia, or osteoporosis).

RESULTS

Two hundred fifty-seven patients with IBD underwent CTE and BCT. Fracture risk was classified as not increased in 45.5% (116/255) of patients, increased in 44.7% (114/255), and high in 9.8% (25/255). Femoral neck BMD was classified as normal in 56.8% (142/250), osteopenia in 37.6% (94/250), and osteoporosis in 5.6% (14/250). In multivariate analysis, only increasing age was associated with increased fracture risk (odds ratio, 1.06; 95% confidence interval, 1.04-1.08; P < 0.001). Cornerstone guidelines were met by 35.3% (41/116), 56.1% (64/114), and 76.0% (19/25) of patients in the not increased, increased, and high-risk groups, respectively (P = 0.0001). No Cornerstone criteria were met by 40% (56/139) of patients in the increased and high-risk groups.

CONCLUSIONS

Using BCT, increased or high fracture risk was detected in more than half of this cohort, the prevalence being associated with increased age. A significant proportion of patients with increased or high fracture risk did not meet Cornerstone guidelines. Therefore, IBD patients who do not meet Cornerstone guidelines may benefit from BCT screening.

Differences in the imaging of Crohn's disease patients between North America and Europe: are we ready to bridge the divide?

The emphasis of treatment in Crohn's disease has evolved from a reactive model to "treat-to-target" approaches. Cross-sectional imaging has rapidly evolved in parallel, with a growing evidence base supporting its abilities for diagnosis, monitoring and prognostication. Whilst there are differences in emphasis between Europe and North America, particularly around the type of imaging modalities and patterns of multidisciplinary care, there is increasing convergence. This perspective piece provides an overview of the evolving role of cross-sectional imaging in Crohn's disease, discusses practice differences between North America and Europe and provides suggestions on areas for future collaboration and research priorities.

Three-dimensional CT enterography versus barium follow-through examination in measurement of remnant small intestinal length in short bowel syndrome patients

PURPOSE

To evaluate the feasibility and accuracy of remnant small intestinal length measured by barium follow-through (BaFT) examination and three-dimensional CT enterography (CTe).

MATERIALS AND METHODS

Twenty-nine consecutive short bowel syndrome patients (SBS) who underwent BaFT, CTe, and prior surgical measurements of small intestine were included. Measurements of total remnant small intestinal length on BaFT and CTe were compared to surgical measurements using Spearman's rank correlation coefficients, Bland-Altman plots, and paired t test.

RESULTS

The average remnant intestinal length was 73.1 ± 37.2 cm according to surgical measurement. There was a significant positive correlation between CTe and surgical measurement (r² = 0.99; p < 0.0001), and a relatively weaker correlation between BaFT and surgical measurement (r² = 0.71; p < 0.001). Compared with surgical measurement, the percentage differences of CTe and BaFT were 5.71 ± 6.71% and 27.14 ± 18.41% (mean ± SD), respectively. Furthermore, Bland-Altman plots showed good agreement between CTe and surgical measurement, whereas relatively poor agreement between BaFT and surgical measurement. However, significant difference was found among the three measurement methods by paired t test (p < 0.0001).

CONCLUSIONS

Assessment of remnant small intestinal length by CTe is accurate and acceptable for clinical application, whereas BaFT is less accurate although BaFT is more convenient and cheaper for clinical application. And CTe can provide a cost-effective and noninvasive determination of remnant small intestinal length in planning surgical and nutritional intervention in SBS patients.

Computed Tomography and Magnetic Resonance Small Bowel Enterography: Current Status and Future Trends Focusing on Crohn's Disease

Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are presently state-of-the-art radiologic tests used to examine the small bowel for various indications. This article focuses on CTE and MRE for the evaluation of Crohn disease. The article describes recent efforts to achieve more standardized interpretation of CTE and MRE, summarizes recent research studies investigating the role and impact of CTE and MRE more directly for several different clinical and research issues beyond general diagnostic accuracy, and provides an update on progress in imaging techniques. Also addressed are areas that need further exploration in the future.

Advanced parametric imaging for evaluation of Crohn's disease using dual-energy computed tomography enterography

We describe a case of small bowel Crohn's disease in which dual-energy computed tomography enterography using dual-layer spectral detector scanner contributed to quantitative assessment, and provided a higher degree of confidence pertaining to the diagnosis. Dual-layer spectral detector computed tomography enables retrospective analysis including virtual monochromatic imaging, iodine mapping, and determining the effective atomic number Z with routine scan protocols. These advanced parametric dual-energy imaging holds promising potential as an imaging biomarker for diagnosis, risk-stratification, monitoring of disease progression and therapy, and outcome prediction.

Comparison of diagnostic performance between 1 millisievert CT enterography and half-standard dose CT enterography for evaluating active inflammation in patients with Crohn's disease

PURPOSE

To compare the diagnostic performance of CT enterography (CTE) images obtained at 1 millisievert (mSv) and reconstructed with filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) with those of half-dose CTE images for the evaluation of active inflammation in patients with Crohn's disease.

METHODS

Forty-six consecutive patients (mean age 29 years; range 15-59 years) with Crohn's disease underwent CTE which comprised a standard-dose scan at the enteric phase (45 s), a half-dose scan with ASIR at the portal venous phase (70 s), and 1 mSv scans with FBP and ASIR at the delayed phase (90 s) under a fixed 120 kVp and variable mAs. Two blinded readers independently recorded confidence scores for active inflammation in the ileum and terminal ileum, respectively. The diagnostic performance of each image set was compared by pairwise comparison of receiver operating characteristic curves. The established image findings on standard-dose scan and ileocolonoscopy served as the reference standard.

RESULTS

A total of 92 bowel segments were analyzed. For reader 1, the diagnostic performance was increased from 1 mSv CT with FBP and 1 mSv CT with ASIR to half-dose scan with ASIR (AUC, 0.759, 0.794, and 0.845; P = 0.1429, P = 0.0107, respectively). For reader 2, there was no significant difference among the three image sets (AUC, 0.848, 0.865, and 0.845; P > 0.05, respectively).

CONCLUSIONS

The diagnostic performance of 1 mSv CTE may be comparable to that of half-dose CTE.

Effective communication of cross-sectional imaging findings in Crohn's disease: comparing conventional EMR reporting to a published scoring system

PURPOSE

The purpose of the article is to compare information regarding small bowel lesions in Crohn's disease (CD) patients communicated by a published scoring system and radiology reports from electronic medical record (EMR) of cross-sectional abdominal imaging.

METHODS

Two gastrointestinal radiologists (reference readers) blinded to EMR reports scored cross-sectional imaging exams using a published scoring system. Investigators compared EMR and radiologist scores based on the mentioned findings and severity documentation of each variable. Statistical analysis involved means and difference in proportions and logistic regression modeling.

RESULTS

Seventy-three CD patients, with average age 40.6 years (± SD 14.4), having 80 small bowel lesions on imaging were included. EMR reports reliably mentioned within the consensus score included thickness (79%, p = 0.000), enhancement (70%, p = 0.000), active inflammation (86%, p = 0.000), perienteric fluid (82%, p = 0.000), and presence of stricture (62%, p = 0.002). Minimal lumen diameter (19%, p = 0.000), comb sign (19%, p = 0.000), lesion length (57%, p = 0.06), and fistula (50%, p = 1.0) were reported less often. There was a strong association between the EMR and scoring scale in noting severity of active inflammation (88%, p = 0.000), perienteric fluid (76%, p = 0.000), and internal fistula (71%, p = 0.000). The proportion matching severity values of comb sign and minimal lumen were 24% and 21%, respectively (p = 0.000). Severity matches for stricture were less likely among the non-GI radiologists (odds ratio = 0.33, SE = 0.168, p = 0.029). The odds of reporting stricture and fistula severity were 3.6 and 5.7, respectively, on MRE.

CONCLUSIONS

Findings and severity of inflammation were communicated consistently. Stricture severity including minimal luminal diameter, was less reliably reported, though its prognostic significance impacts management.

Prospective Comparison of Standard- Versus Low-Radiation-Dose CT Enterography for the Quantitative Assessment of Crohn Disease

OBJECTIVE

CT enterography (CTE) is sensitive and specific for active inflammatory changes of Crohn disease (CD), but its use has been limited by exposure to ionizing radiation. The objective of this study is to show the noninferiority of a model-based iterative reconstruction (MBIR) technique using lower radiation doses compared with standard-dose CTE in the assessment of CD.

SUBJECTS AND METHODS

Patients referred to a hospital radiology department for CTE for the evaluation of CD underwent both a standard examination (used to generate filtered back-projection and adaptive statistical iterative reconstruction [ASIR] images) and low-dose MBIR CTE performed in a random sequence on the same day. Images were reviewed by two radiologists for signs of small-bowel CD. Radiologic findings obtained using ASIR and clinical assessments of disease activity served as the reference standard for comparison with low-dose CTE findings.

RESULTS

A total of 163 patients, 92 (56.4%) of whom had active disease, underwent CTE. MBIR was found to be noninferior to the two standard-dose techniques, with no significant differences noted between the three types of images when compared with the clinical reference standard. As compared with the radiologic standard of ASIR, the very-low-dose scans had a high degree of accuracy, with sensitivity ranging from 0.85 to 0.94 and specificity ranging from 0.84 to 0.97 depending on the reader. A significant reduction in radiation exposure was noted with MBIR (mean [± SD] reduction, 3.30 ± 3.17 mSv) versus standard-dose imaging (7.16 ± 4.61 mSv; p < 0.001).

CONCLUSION

Low-dose CTE using MBIR is sensitive and specific for the detection of active inflammatory changes of CD while utilizing radiation doses substantially lower than those associated with standard techniques.

Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine

OBJECTIVES

To evaluate the feasibility and time saving of fusing CT and MR enterography with ultrasound for ultrasound molecular imaging (USMI) of inflammation in an acute small bowel inflammation of swine.

METHODS

Nine swine with ileitis were scanned with either CT (n = 3) or MR (n = 6) enterography. Imaging times to load CT/MR images onto a clinical ultrasound machine, fuse them to ultrasound with an anatomical landmark-based approach, and identify ileitis were compared to the imaging times without anatomical road mapping. Inflammation was then assessed by USMI using dual selectin-targeted (MB_Selectin) and control (MB_Control) contrast agents in diseased and healthy control bowel segments, followed by ex vivo histology.

RESULTS

Cross-sectional image fusion with ultrasound was feasible with an alignment error of 13.9 ± 9.7 mm. Anatomical road mapping significantly reduced (P < 0.001) scanning times by 40%. Localising ileitis was achieved within 1.0 min. Subsequently performed USMI demonstrated significantly (P < 0.001) higher imaging signal using MB_Selectin compared to MB_Control and histology confirmed a significantly higher inflammation score (P = 0.006) and P- and E-selectin expression (P ≤ 0.02) in inflamed vs. healthy bowel.

CONCLUSIONS

Fusion of CT and MR enterography data sets with ultrasound in real time is feasible and allows rapid anatomical localisation of ileitis for subsequent quantification of inflammation using USMI.

KEY POINTS

• Real-time fusion of CT/MRI with ultrasound to localise ileitis is feasible. • Anatomical road mapping using CT/MRI significantly decreases the scanning time for USMI. • USMI allows quantification of inflammation in swine, verified with ex vivo histology.

CT Enterography for Surveillance of Anastomotic Recurrence within 12 Months of Bowel Resection in Patients with Crohn's Disease: An Observational Study Using an 8-Year Registry

OBJECTIVE

To investigate the diagnostic yield and accuracy of CT enterography (CTE) for early (< 12 postoperative months) surveillance of anastomotic recurrence after bowel resection for Crohn's disease (CD).

MATERIALS AND METHODS

We analyzed 88 adults (60 males and 28 females; mean age, 31.4 ± 9.6 years) who underwent bowel surgery for CD that created ileocolic anastomosis without enteric stoma, and underwent CTE for surveillance of CD recurrence/aggravation within 12 post-operative months. The CD activity index (CDAI) at the time of CTE was < 150 (i.e., clinically silent) in 51 patients, and ≥ 150 in 37 patients. Diagnostic yields of CTE regarding CD recurrence in the ileocolic anastomosis and extraluminal penetrating complications were determined. CTE-related step-up therapy was recorded. These outcomes were compared between the two CDAI groups after accounting for major risk factors for CD recurrence. In a subgroup of 31 patients who underwent both CTE and ileocolonoscopy within 1 month, CTE accuracy for anastomotic recurrence was assessed using the Rutgeerts scoring as the reference standard.

RESULTS

CTE diagnostic yield was 35.2% (31/88) for the anastomotic recurrence and 9.1% (8/88) for penetrating complications. 20.5% (18/88) of the patients underwent step-up therapy after CTE detection of anastomotic recurrence. These outcomes were not significantly different between CDAI < 150 and CDAI ≥ 150, except that CTE yield for extraluminal penetrating complications was significantly higher in CDAI ≥ 150 (16.2% [6/37] vs. 3.9% [2/51]; multivariable-adjusted p = 0.029). CTE showed 92.3% (12/13) sensitivity and 83.3% (15/18) specificity for anastomotic recurrence.

CONCLUSION

CTE may be a viable option for the early postsurgical surveillance of recurred disease in CD patients.

Split-Bolus Injection Producing Simultaneous Late Arterial and Portal Venous Phases in CT Enterography: Preliminary Results

OBJECTIVE

The purpose of this article is to evaluate the image quality and added value of split-bolus contrast agent injection combining late arterial and portal venous phases compared with single-bolus contrast agent injection late arterial phase CT enterography.

MATERIALS AND METHODS

Consecutive patients who underwent CT enterography before and after implementation of a single-bolus CT enterography protocol were included. Attenuation and contrast-to-noise ratio (CNR) were assessed by ROI measurements of the bowel wall and arterial and venous structures. Subjective enhancement of the bowel wall (1, arterial; 2, mucosal; 3, transmural; 4, transmural with mucosal hyperenhancement) and bowel abnormalities were assessed by two independent readers. MR enterography examinations, endoscopy reports, and surgery reports within 30 days after CT enterography were used to produce a composite outcome.

RESULTS

Sixty-six patients were included in our study: 33 (mean [± SD] age, 46.0 ± 19.8 years) who underwent split-bolus CT enterography and 33 (mean age, 49.9 ± 19.0 years) who underwent single-bolus CT enterography. Bowel wall attenuation and CNR were higher for split-bolus CT enterography than for single-bolus CT enterography at 120 kVp (enhancement, 98.7 ± 23.1 HU vs 85.1 ± 23.3 HU; CNR, 6.4 ± 2.5 vs 4.4 ± 2.3; p < 0.01). Subjective ratings of bowel wall enhancement were higher with the split-bolus CT enterography than the single-bolus CT enterography (2.6 ± 0.8 vs 2.3 ± 0.6; p < 0.001). Split-bolus CT enterography led to a higher detection rate of mucosal hyperenhancement than did single-bolus CT enterography in patients with active inflammatory bowel disease (100.0% [7/7; 95% CI, 59.0-100.0%] vs 33.3% [2/6; 95% CI, 4.3-77.7%]; p = 0.02), whereas both protocols had a specificity of 100.0% (9/9).

CONCLUSION

Split-bolus CT enterography led to improved CNR (47%) compared with single-bolus CT enterography and significantly increased the detection rate of mucosal hyperenhancement in patients with active inflammatory bowel disease.

Impact of CT enterography on the diagnosis of small bowel gastrointestinal stromal tumors

OBJECTIVE

Our purpose is to determine the impact of CT enterography on small bowel gastrointestinal stromal tumor (GIST) detection and biologic aggressiveness, and to identify any imaging findings that correlate with biologic aggressiveness.

METHODS

Records of patients with histologically confirmed small bowel GISTs who underwent CT imaging were reviewed. Biologic aggressiveness was based on initial histologic grading (very low, low, intermediate, high grade; or malignant), with upgrade to malignant category if local or distant metastases developed during clinical follow-up. Imaging indications, findings, and type of CT exam were compared with the biologic aggressiveness.

RESULTS

111 small bowel GISTs were identified, with suspected small bowel bleeding being the most common indication (45/111; 40.5%). While the number of malignant GISTs diagnosed by CT remained relatively constant (2-3 per year), the number of non-malignant GISTs increased substantially (mean 1.5/year, 1998-2005; 8.4/year, 2006-2013). In patients with suspected small bowel bleeding, CT enterography identified 33 GISTs (7/33, 21% malignant) compared to 12 GISTs by abdominopelvic CT (6/12, 50% malignant; p < 0.03). Tumor size (p < 0.0001), internal necrosis (p = 0.005), internal air or enteric contrast (p ≤ 0.021), and ulceration (p ≤ 0.021) were significantly associated with high-grade and malignant tumors, and irregular or invasive tumor borders (p < 0.01) was associated with malignant tumors.

CONCLUSION

The detection of small bowel GISTs can increase due to the use of CT enterography in patients with suspected small bowel bleeding. The large majority of small bowel GISTs detected by CT enterography are not malignant.

Multidetector CT enterography of focal small bowel lesions: a radiological-pathological correlation

Focal small bowel lesions present a diagnostic challenge for both the radiologist and gastroenterologist. Both the detection and characterization of small bowel masses have greatly improved with the advent of multidetector CT enterography (MD-CTE). As such, MD-CTE is increasingly utilized in the workup of occult gastrointestinal bleeding. In this article, we review the spectrum of focal small bowel masses with pathologic correlation. Adenocarcinoma, the most common primary small bowel malignancy, presents as a focal irregular mass occasionally with circumferential extension leading to obstruction. Small bowel carcinoid tumors most commonly arise in the ileum and are characterized by avid enhancement and marked desmoplastic response of metastatic lesions. Aneurysmal dilatation of small bowel is pathognomonic for lymphoma and secondary findings of lymphadenopathy and splenomegaly should be sought. Benign small bowel masses such as leiomyoma and adenoma may be responsible for occult gastrointestinal bleeding. However, primary vascular lesions of the small bowel remain the most common cause for occult small bowel gastrointestinal bleeding. The arterial phase of contrast obtained with CTE aids in recognition of the vascular nature of these lesions. Systemic conditions such as Peutz-Jeghers syndrome and Crohn's disease may be suggested by the presence of multiple small bowel lesions. Lastly, potential pitfalls such as ingested material should be considered when faced with focal small bowel masses.

Cross-sectional imaging in refractory celiac disease

PURPOSE

The purpose of this study is to identify unique imaging findings of refractory celiac disease (RCD) including Type I RCD, Type II RCD versus healed celiac disease (CD).

METHODS

A retrospective study of patients with known CD and refractory symptoms with cross-sectional imaging was performed. We included patients who underwent T cell receptor rearrangement or T-cell immunophenotyping studies on small bowel (SB) biopsies to classify patients into: healed CD, Type I RCD, or Type II RCD. GI radiologists performed a blinded review of the imaging studies.

RESULTS

One-hundred eighteen patients (32 healed; 67 Type I RCD; 19 Type II RCD) were included (mean age 53 ± 6 years; 62% female). The presence of any fold pattern abnormality was more likely to be found in Type II and Type I RCD than healed CD (53% vs. 43% vs.16%; p = 0.009). Type II RCD patients were more likely than Type I RCD and healed CD to have imaging findings of ulcerative jejunitis (26% vs. 6% vs. 3%; p = 0.009), SB wall thickening (37% vs. 16% vs. 0%; p = 0.002) and SB dilation (26% vs. 7% vs. 6%; p = 0.04). Type II RCD demonstrated non-significant trends for decreased number of jejunal folds only, SB mass, mesenteric lymphadenopathy, localized peri-mural edema, and intramural duodenal edema.

CONCLUSIONS

Fold pattern abnormalities, ulcerative jejunitis, SB wall thickening, and SB dilation are more likely to be identified in cross-sectional imaging of RCD than healed CD. SB dilatation and ulcerative jejunitis are more likely to be found in Type II than Type I RCD.

Collagenous sprue cross-sectional imaging: a comparative blinded study

PURPOSE

Collagenous sprue (CS) is a rare enteropathy characterized by villous atrophy and a thickened subepithelial collagen band. The aim of this study is to describe the cross-sectional imaging findings of CS.

METHODS

A case-control, retrospective study with cases of all CS patients from January 2000 to 2015 was performed. Inclusion criteria were (1) Histopathologic diagnosis and (2) Imaging with computed tomography abdomen/pelvis (CT A/P), CT enterography (CTE), or magnetic resonance enterography within 6 months of small bowel (SB) biopsy. Control subjects were irritable bowel syndrome (IBS) patients who underwent CTE. Imaging studies were examined by two GI radiologists, blinded to patient data.

RESULTS

108 patients (54 CS; 54 IBS) were included. Mean age was 56.7 ± 16.5 years, and 68% were female (72% in CS group vs. 63% in IBS group; p = 0.3). CS patients were significantly older (67 ± 12 vs. 47 ± 15 year; p < 0.001) and more likely to be on angiotensin receptor blockers (41% vs. 6%; p < 0.001) as compared to the IBS group. Compared to IBS, CS patients were more likely to have mesenteric lymph node (LN) prominence (56% vs. 15%; p < 0.001), jejunoileal fold pattern reversal (46% vs. 6%; p < 0.001), SB dilation (28% vs. 0%; p < 0.001), SB conformational change (28% vs. 6%; p = 0.002), SB wall thickening (13% vs. 2%; p = 0.03), and ulcerative jejunoileitis (4% vs. 0%; p = 0.01). Radiologists suspected malabsorption in 72% in the CS group and 2% in the IBS group (p < 0.001).

CONCLUSION

Imaging findings suggestive of mucosal malabsorption are commonly demonstrated in CS.

Small Bowel Imaging: Computed Tomography Enterography, Magnetic Resonance Enterography, Angiography, and Nuclear Medicine

Radiology examinations play a major role in the diagnosis, management, and surveillance of small bowel diseases and are complementary to endoscopic techniques. Computed tomography enterography and magnetic resonance enterography are the cross-sectional imaging studies of choice for many small bowel diseases. Angiography still plays an important role for catheter-directed therapies. With the emergence of hybrid imaging techniques, radionuclide imaging has shown promise for the evaluation of small bowel bleeding and Crohn disease and may play a larger role in the future. This article reviews recent advances in technology, diagnosis, and therapeutic options for selected small bowel disorders.

Neoplastic Diseases of the Small Bowel

The incidence of small bowel tumors is increasing over time. Until recently, their diagnosis was delayed and it was often reached only at the time of surgery. New diagnostic tools, such as capsule endoscopy, device-assisted enteroscopy, and dedicated small bowel cross-sectional imaging techniques, have been introduced recently in clinical practice. The combination of these tools allows medical practitioners to detect small bowel tumors at an early stage and to reach a definite diagnosis before surgery, thus enabling minimally invasive treatments.

Inflammatory Disorders of the Small Bowel

The most common small bowel inflammatory disorders include Crohn disease, nonsteroidal antiinflammatory drug (NSAID) enteropathy, and celiac disease. Capsule endoscopy, computed tomography enterography, and magnetic resonance enterography have a complementary role in the diagnosis of Crohn disease and evaluation of patients with established Crohn disease. The higher risk of capsule retention with known Crohn disease and NSAID enteropathy can be minimized by cross-sectional imaging or the patency capsule. The main role of deep enteroscopy is tissue diagnosis, endoscopic management of small bowel lesions and strictures, and retrieval of retained capsules.

Mesenteric findings of CT enterography are well correlated with the endoscopic severity of Crohn's disease

BACKGROUND

Maintenance of mucosal healing is a primary goal when treating Crohn's disease (CD). Endoscopy is the most precise method for the assessment of mucosal healing, but is considered overly invasive for patients with CD. In contrast, CT enterography (CTE) is less invasive, but little is known about the correlation between mucosal status and CTE parameters.

METHODS

We recruited CD patients who underwent CTE and double balloon endoscopy (DBE) on the same day at our hospital between 2012 and 2014. CTE parameters evaluated included bowel-wall thickening, mural hyperenhancement, mural stratification (target sign), submucosal fat deposition, mesenteric hypervascularity (comb sign), increased fat density, mesenteric fibrofatty proliferation, enlarged mesenteric lymph nodes, and stenosis/sacculation. Endoscopic findings were evaluated using the Simple Endoscopic Score for Crohn's Disease (SES-CD). CTE parameters that were predictive of higher values in the SES-CD were extracted statistically.

RESULTS

Forty-one patients were recruited, from which 191 intestinal segments were evaluated. Spearman's rank correlation coefficients showed that the majority of CTE values exhibited mild to moderate correlations with SES-CD values. Notably, multiple ordinal logistic regression analysis demonstrated that CTE findings obtained from the mesenteric area, such as mesenteric hypervascularity (comb sign) and enlarged mesenteric lymph nodes, were more critical predictors of endoscopic mucosal ulceration than those obtained from the bowel wall.

CONCLUSIONS

This study was the first of its kind to assess correlations between CTE values and SES-CD values. Mesenteric findings of CTE, rather than mural findings, were highly correlated with the endoscopically evaluated severity of ulceration.

Potential model for differential diagnosis between Crohn's disease and primary intestinal lymphoma

AIM

To evaluate the usefulness of different parameters to differentiate Crohn’s disease (CD) from primary intestinal lymphoma (PIL).

METHODS

The medical records of 85 patients with CD and 56 patients with PIL were reviewed retrospectively. Demographic, clinical, laboratory, endoscopic, and computed tomographic enterography (CTE) parameters were collected. The univariate value of each parameter was analyzed. A differentiation model was established by pooling all the valuable parameters. Diagnostic efficacy was analyzed, and a receiver operating characteristic (ROC) curve was plotted.

RESULTS

The demographic and clinical parameters that showed significant values for differentiating CD from PIL included age of onset, symptom duration, presence of diarrhea, abdominal mass, and perianal lesions (P < 0.05). Elevated lactate dehydrogenase and serum β2-microglobulin levels suggested a PIL diagnosis (P < 0.05). The endoscopic parameters that showed significant values for differentiating CD from PIL included multiple-site lesions, longitudinal ulcer, irregular ulcer, and intraluminal proliferative mass (P < 0.05). The CTE parameters that were useful in the identification of the two conditions included involvement of ≤ 3 segments, circular thickening of the bowel wall, wall thickness > 8 mm, aneurysmal dilation, stricture with proximal dilation, “comb sign”, mass showing the “sandwich sign”, and intussusceptions (P < 0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the differentiation model were 91.8%, 96.4%, 93.6%, 97.5%, and 88.5%, respectively. The cutoff value was 0.5. The area under the ROC curve was 0.989.

CONCLUSION

The differentiation model that integrated the various parameters together may yield a high diagnostic efficacy in the differential diagnosis between CD and PIL.

Detection of suspected small bowel bleeding: challenges and controversies

Detection of small bowel (SB) bleeding remains a challenge to gastroenterologists, with a dearth of standardized recommendations regarding evaluation and management. Areas covered: A recursive literature search was performed using PubMed, Cochrane and Medline databases for original and review articles on SB and obscure gastrointestinal bleeding (OGIB). Based upon the available literature, this review outlines the main challenges and controversies, and provides a practical and cost-effective approach towards SB bleeding. Expert commentary: SB bleeding is suspected in patients with persistent or recurrent bleeding after negative bidirectional endoscopy, and unexplained iron deficiency anemia. Selection of test(s) should be individualized based upon patient presentation and suspicion for type of underlying lesion. Endoscopic or radiologic evaluation and treatment is the mainstay in the majority of patients, while pharmacologic agents may have a role in patients with refractory bleeding, and those unable to undergo evaluation.