Crohn's disease: Clinical–surgical questions and imaging answers

CT enterography: Diagnostic value of 4th generation iterative reconstruction algorithm in low dose studies in comparison with standard dose protocol for follow-up of patients with Crohn's disease

PURPOSE

To compare radiation dose, image quality and diagnostic performance of low dose CT enterography (CTE) protocol combined with iterative reconstruction algorithm (iDose(4)) with standard dose CTE in follow-up of patients with known Crohn's disease (CD).

MATERIALS AND METHOD

Thirty-six patients (12 females), with CD underwent a low-dose CTE scan during single venous phase on 256 MDCT scanner, with the following parameters: 120 kV, automated mAs dose-modulation, slice thickness 2mm and iDose(4) iterative reconstruction algorithm. A control group of thirty-seven patients underwent standard dose CTE examination on the same CT scanner. Two radiologists, blinded to clinical and pathological findings, independently evaluated in each scan, HU values in bowel wall and any presence of CD activity features and disease complications. Image noise and diagnostic quality were evaluated using a 4-point scale. Dose-length product (DLP) and CT-dose-index (CTDI) were recorded and data from both examinations were compared and statistically analyzed.

RESULTS

Low-dose CTE protocol showed high diagnostic quality in assessment of Crohn's disease obtaining significantly (p ≤ 0.001) lower values of DLP and CTDI (604.98 mGy*cm and 12.29 mGy) as compared to standard dose examinations (974.85 mGy*cm and 19.71 mGy), with an overall dose reduction of 37.6%. Noise resulted slightly higher in iDose(4) images (SD=15.97) than in standard dose ones (SD=13.61) but this difference was not statistically significant (p=0.064).

CONCLUSION

Low-dose CTE combined with iDose(4) reconstruction algorithm offers high quality images with significant reduction of radiation dose, and therefore can be considered a useful tool in the management of CD patients, considering their young age and the frequent imaging follow-up required.

Accuracy of imaging for predicting operative approach in Crohn's disease

Background

The aim of this study was to assess the accuracy of preoperative imaging in detecting the extent of disease and predicting the operative approach in patients with Crohn's disease.

Methods

Patients with Crohn's disease who were scheduled to undergo operation were evaluated before operation using computed tomography enteroclysis (CTE) and magnetic resonance enterography (MRE). Preoperative imaging findings were correlated with intraoperative and pathological findings to estimate the capabilities of preoperative imaging in detecting lesions due to Crohn's disease. The operative approach determined before surgery was compared with the procedure actually performed, which was based on intraoperative findings.

Results

Fifty-two patients with Crohn's disease were studied; 26 were evaluated before surgery with CTE and 26 with MRE. Eighty-nine lesions due to Crohn's disease were confirmed surgically (60 small bowel stenoses, 21 fistulas and 8 abscesses). CTE confirmed the presence of 38 of 41 lesions (sensitivity 93 per cent) and MRE 48 of 48 lesions (sensitivity 100 per cent); a correct estimation of the disease with an exact prediction of the operative approach was obtained in 49 (94 per cent) of 52 patients. Discrepant findings between preoperative imaging and operative findings were observed in three patients (6 per cent), who had CTE.

Conclusion

Preoperative imaging using CTE or MRE is highly accurate for assessing Crohn's disease lesions before operation, allowing correct prediction of the operative approach.

Inflammatory activity in Crohn's disease: CE-US

The evaluation of inflammatory activity in Crohn's disease (CD), a crucial aspect of treatment planning and monitoring, is currently based on a sum of clinical data and imaging findings. Among the contrast enhanced cross-sectional imaging techniques (CE-US, CE-CT, CE-MR), CE-US is less invasive, more comfortable for the patient, and has significant diagnostic accuracy. In addition, it is a portable, easily repeatable, well tolerated, and ionizing radiation-free imaging modality. CE-US has been introduced as effective method in the quantitative and qualitative evaluation of CD inflammatory activity. CE-US might help in characterizing bowel-wall thickening by differentiating inflammatory neovascularisation, edema, and fibrosis. The recent chance to evaluate the bowel-wall stiffness by US elastography imaging could allow further assessment of fibrosis that characterizes the evolution of the inflammatory activity.