1Department of Radiology, Hospital Clinic Barcelona, Barcelona, Spain
2Centro de Investigación Biomédica en Red Enfermedades Hepáticas y Digestivas (CIBER-EHD), Spain
3Department of Radiology, University Hospital Sant’Orsola Malpighi, Bologna, Italy
© Copyright 2020. Korean Association for the Study of Intestinal Diseases. All rights reserved.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
FINANCIAL SUPPORT
The authors received no financial support for the research, authorship, and/or publication of this article.
CONFLICT OF INTEREST
No potential conflict of interest relevant to this article was reported.
AUTHOR CONTRIBUTION
Writing - original draft: Rimola J, Capozzi N. Writing - review and editing: Rimola J. Approval of final manuscript: all authors.
Author (year) | Technique | Nature of the study | Main clinically relevant findings | |
---|---|---|---|---|
Magnetic resonance | ||||
Punwani et al. (2009) [11] | MRE (morphologic and enhancement features) | Single-center study | The study aimed to determine the association between MRI features of CD activity against a histopathologic reference. | |
Prospective | Different MR features were correlated with inflammation was found in both studies including wall thickness, T2 hypersignal and layered enhancement of gadolinium. | |||
Wall thickness was not correlated with the degree of fibrosis. | ||||
Zappa et al. (2011) [9] | MRE (morphologic and enhancement features) | Single-center study | The study aimed to evaluate the value of MRI findings in CD in correlation with pathological scores of inflammation and fibrosis. | |
Retrospective | Different MR features were correlated with inflammation including wall thickness, T2 hypersignal and layered enhancement of gadolinium. Layered enhancement was not associated with the degree of fibrosis. | |||
Both inflammation and fibrosis scores were positively correlated (r = 0.63, P = 0.0001). | ||||
Wilkens et al. (2018) [21] | MRE (morphologic and enhancement features) | Single-center study | Authors investigated the perfusion by MRE as objective marker to distinguishing between the inflammation and fibrosis. | |
Prospective | Wall thickness correlated with the degree of inflammation. | |||
No significant correlation between the severity of inflammation or fibrosis on histopathology, and mural enhancement (r = –0.13, P = 0.54 for inflammation and r = 0.41, P = 0.05 for fibrosis). | ||||
Tielbeek et al. (2014) [13] | MRE with DWI and perfusion analysis of contrast injection | Single-center study | Different advanced MR techniques were applied before surgical resection, including diffusion- weighted image, perfusion analysis including time-intensity curves, and morphological assessment as well. | |
Retrospective | Mural thickness, maximum intravenous contrast enhancement and the slope of increase after its injection correlated significantly with histological inflammation (r = 0.63, 0.41, 0.53, respectively; P< 0.05). | |||
The quantification of diffusion-weighted imaging by mean of ADC correlated significantly with fibrosis (all P< 0.05). | ||||
Rimola et al. (2015) [10] | MRE using DCE (gain of enhancement between early and late phases) | Single-center study | Different imaging acquisitions were obtained after gadolinium injection. The hypothesis of this study was that dense fibrotic typically show a slow enhancement of gadolinium contrast over time. | |
Retrospective | Using percentage of enhancement gain between early and late phases after gadolinium injection, MRI is able to discriminate between mild–moderate and severe fibrosis deposition with a sensitivity of 0.94 and a specificity of 0.89. | |||
T2 hypersignal (edema) has a high and significant predictive value for detecting severe inflammation. | ||||
Li et al. (2018) [14] | MRE using MTR, ADC and gain of enhancement | Single-center study | MT sequence attempts to identify tissue with water linked to macromolecules (such as collagen). The study compared MT with diffusion and the gain of gadolinium enhancement. | |
Prospective | Differentiating moderately to severely fibrotic bowel walls from those non-to-mildly fibrotic with an AUC of 0.919 (P = 0.000) for MT measurements; AUC of 0.747 (P = 0.001) for ADC; and AUC of 0.592 (P = 0.209) for the percentage of enhancement gain. | |||
Repeated measurements | ||||
Wagner et al. (2018) [15] | MRE using DWI | Single-center study | Authors hypothesized that muscular hypertrophy is an additional lesion that reduces bowel lumen in strictures and should be differentiated from fibrosis. Analyzing the bowel wall thickness on T2W (> 7.4 mm) had a sensitivity of 61% and a specificity of 89% to differentiate fibrosis from muscular hypertrophy. | |
Retrospective | ||||
Ultrasound | ||||
Dillman et al. (2014) [22] | USE (SWE) | Single-center study | The study aimed to determine if US elastography could discriminate low- from high-grade fibrosis in the bowel. The authors used 2 different methods of SWE. | |
Prospective | Significant correlation between shear wave speed and bowel fibrosis (P = 0.01). USE using 2 different methods of USE it is possible to differentiate low– from high–fibrosis score bowel segments with AUC of 0.77–0.91. No significant differences in USE in mean shear wave speed between high- and low-inflammation score bowel segments. | |||
Fraquelli et al. (2015) [23] | USE (strain ratio) | Single-center study | The aim was to evaluate the feasibility of USE toward the assessment of ileal fibrosis in CD patients. USE strain ratio measurement was significantly correlated with the severity of bowel fibrosis 0.917 (95% CI, 0.788–1.000). | |
Prospective | ||||
Wilkens et al. (2018) [21] | Bowel US and CEUS | Single-center study | Authors investigated the perfusion by CEUS as objective marker to distinguishing between the inflammation and fibrosis. | |
Prospective | No correlation was found between the severity of inflammation or fibrosis on histopathology and the degree of enhancement (P =0.45 for inflammation and P =0.19 for fibrosis); Wall thickness assessed by US correlated with both, histological inflammation (P =0.001) and fibrosis (P =0.048). | |||
Chen et al. (2018) [24] | USE (SWE) | Single-center study | The aim of this study was to investigated whether the quantification of stiffness using USE is able to distinguishing between the inflammation and fibrotic component of strictures. | |
Prospective | A cutoff of 22.55 kPa can discriminate mild to moderate and severe fibrosis (sensitivity 69.6%, specificity 91.7% with AUC of 0.822; P =0.002). | |||
Ding et al. (2019) [25] | USE (SWE, strain ratio, ARFI) | Single-center study | To evaluate the diagnostic performance of USE (different modalities) for assessment of the predominant types of intestinal stenosis. | |
Prospective | The optimal cutoff value to discriminate predominantly fibrotic strictures on point-SWE was >2.73 m/s (sensitivity, 75%; specificity, 100%; accuracy, 96%; AUROC, 0.833; P<0.05). | |||
Point-SWE outperforms ARFI and strain ratio for strictures characterization. |
MRE, magnetic resonance enterography; DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient; DCE, dynamic contrast enhancement; MTR, magnetization transfer ratio; MT, magnetization transfer; AUC, area under received operating characteristic curve; USE, ultrasound elastography; US, ultrasound; SWE, shear wave elastography; CEUS, contrast-enhanced ultrasound; ARFI, acoustic radiation force impulse.
Novel imaging modality | Principle | Advantages | Limitations |
---|---|---|---|
MR-DWI | Provides information related to the motion of water molecules in the extracellular and cellular compartments, without use of contrast agents. | Part of most routine scan protocols. | Motion water molecules can be restricted by either fibrotic tissue or inflammation. It could be difficult to determine the contribution of inflammation and fibrosis over the motion restriction. |
Allows quantitative data by means of ADC maps. | |||
Good correlation with presence of fibrosis in different studies. | |||
MT ratio | Produces image contrast between protons in free water molecules and those in large macromolecules, including collagen, increasing its signal (MT ratio) with the increased amount of collagen. | In animal models and in humans, MT ratio well correlated with the presence of fibrosis. | Further studies are warranted to confirm and validate this technique against histopathology. |
High specific absorption rate that may cause heating of patient’s tissue. | |||
Gain of enhancement on MR | Technique commonly used for assessing myocardial fibrosis. Extravascular-extracellular volume fraction in fibrotic tissue is low on early phase post gadolinium injection, increasing its gain of enhancement compared with latter phases. | Easy to implement as routine. | Not validated on multicentric setting. Values may be subject to vendor characteristics. |
Ultrasound elastography: strain ratio | Measures the tissue strain (the degree of compression) developed under an applied force by the operator. | Easy to incorporate together standard bowel ultrasound. | Limited by bowel location, body habitus and operator. |
Different vendors may have different scale of values. | |||
Lack of absolute values. | |||
Ultrasound elastography: shear wave | A focused ultrasound pulse is generated by a mechanical vibrating device and transmitted by the transducer. Then a shear waves are generated and propagate off-axis. The measure of the speed of a shear wave provides a quantitative estimate of tissue stiffness. | Direct quantification over any area of interest. | Limited by bowel location and body habitus. |
Easy and fast to get quantitative data. | Different vendors may have different scale of values. | ||
CEUS | Based on the injection of micro bubbles on vein and real-time visualization of slow blood flows at the area of interest using ultrasound. | Provides information relative to the perfusion level at real time. | Not standardizes measures. |
Differences between different available methods. | |||
Limited by bowel location and body habitus. |
Author (year) | Technique | Nature of the study | Main clinically relevant findings | |
---|---|---|---|---|
Magnetic resonance | ||||
Punwani et al. (2009) [11] | MRE (morphologic and enhancement features) | Single-center study | The study aimed to determine the association between MRI features of CD activity against a histopathologic reference. | |
Prospective | Different MR features were correlated with inflammation was found in both studies including wall thickness, T2 hypersignal and layered enhancement of gadolinium. | |||
Wall thickness was not correlated with the degree of fibrosis. | ||||
Zappa et al. (2011) [9] | MRE (morphologic and enhancement features) | Single-center study | The study aimed to evaluate the value of MRI findings in CD in correlation with pathological scores of inflammation and fibrosis. | |
Retrospective | Different MR features were correlated with inflammation including wall thickness, T2 hypersignal and layered enhancement of gadolinium. Layered enhancement was not associated with the degree of fibrosis. | |||
Both inflammation and fibrosis scores were positively correlated (r = 0.63, P = 0.0001). | ||||
Wilkens et al. (2018) [21] | MRE (morphologic and enhancement features) | Single-center study | Authors investigated the perfusion by MRE as objective marker to distinguishing between the inflammation and fibrosis. | |
Prospective | Wall thickness correlated with the degree of inflammation. | |||
No significant correlation between the severity of inflammation or fibrosis on histopathology, and mural enhancement (r = –0.13, P = 0.54 for inflammation and r = 0.41, P = 0.05 for fibrosis). | ||||
Tielbeek et al. (2014) [13] | MRE with DWI and perfusion analysis of contrast injection | Single-center study | Different advanced MR techniques were applied before surgical resection, including diffusion- weighted image, perfusion analysis including time-intensity curves, and morphological assessment as well. | |
Retrospective | Mural thickness, maximum intravenous contrast enhancement and the slope of increase after its injection correlated significantly with histological inflammation (r = 0.63, 0.41, 0.53, respectively; P< 0.05). | |||
The quantification of diffusion-weighted imaging by mean of ADC correlated significantly with fibrosis (all P< 0.05). | ||||
Rimola et al. (2015) [10] | MRE using DCE (gain of enhancement between early and late phases) | Single-center study | Different imaging acquisitions were obtained after gadolinium injection. The hypothesis of this study was that dense fibrotic typically show a slow enhancement of gadolinium contrast over time. | |
Retrospective | Using percentage of enhancement gain between early and late phases after gadolinium injection, MRI is able to discriminate between mild–moderate and severe fibrosis deposition with a sensitivity of 0.94 and a specificity of 0.89. | |||
T2 hypersignal (edema) has a high and significant predictive value for detecting severe inflammation. | ||||
Li et al. (2018) [14] | MRE using MTR, ADC and gain of enhancement | Single-center study | MT sequence attempts to identify tissue with water linked to macromolecules (such as collagen). The study compared MT with diffusion and the gain of gadolinium enhancement. | |
Prospective | Differentiating moderately to severely fibrotic bowel walls from those non-to-mildly fibrotic with an AUC of 0.919 (P = 0.000) for MT measurements; AUC of 0.747 (P = 0.001) for ADC; and AUC of 0.592 (P = 0.209) for the percentage of enhancement gain. | |||
Repeated measurements | ||||
Wagner et al. (2018) [15] | MRE using DWI | Single-center study | Authors hypothesized that muscular hypertrophy is an additional lesion that reduces bowel lumen in strictures and should be differentiated from fibrosis. Analyzing the bowel wall thickness on T2W (> 7.4 mm) had a sensitivity of 61% and a specificity of 89% to differentiate fibrosis from muscular hypertrophy. | |
Retrospective | ||||
Ultrasound | ||||
Dillman et al. (2014) [22] | USE (SWE) | Single-center study | The study aimed to determine if US elastography could discriminate low- from high-grade fibrosis in the bowel. The authors used 2 different methods of SWE. | |
Prospective | Significant correlation between shear wave speed and bowel fibrosis (P = 0.01). USE using 2 different methods of USE it is possible to differentiate low– from high–fibrosis score bowel segments with AUC of 0.77–0.91. No significant differences in USE in mean shear wave speed between high- and low-inflammation score bowel segments. | |||
Fraquelli et al. (2015) [23] | USE (strain ratio) | Single-center study | The aim was to evaluate the feasibility of USE toward the assessment of ileal fibrosis in CD patients. USE strain ratio measurement was significantly correlated with the severity of bowel fibrosis 0.917 (95% CI, 0.788–1.000). | |
Prospective | ||||
Wilkens et al. (2018) [21] | Bowel US and CEUS | Single-center study | Authors investigated the perfusion by CEUS as objective marker to distinguishing between the inflammation and fibrosis. | |
Prospective | No correlation was found between the severity of inflammation or fibrosis on histopathology and the degree of enhancement (P =0.45 for inflammation and P =0.19 for fibrosis); Wall thickness assessed by US correlated with both, histological inflammation (P =0.001) and fibrosis (P =0.048). | |||
Chen et al. (2018) [24] | USE (SWE) | Single-center study | The aim of this study was to investigated whether the quantification of stiffness using USE is able to distinguishing between the inflammation and fibrotic component of strictures. | |
Prospective | A cutoff of 22.55 kPa can discriminate mild to moderate and severe fibrosis (sensitivity 69.6%, specificity 91.7% with AUC of 0.822; P =0.002). | |||
Ding et al. (2019) [25] | USE (SWE, strain ratio, ARFI) | Single-center study | To evaluate the diagnostic performance of USE (different modalities) for assessment of the predominant types of intestinal stenosis. | |
Prospective | The optimal cutoff value to discriminate predominantly fibrotic strictures on point-SWE was >2.73 m/s (sensitivity, 75%; specificity, 100%; accuracy, 96%; AUROC, 0.833; P<0.05). | |||
Point-SWE outperforms ARFI and strain ratio for strictures characterization. |
MR, magnetic resonance; DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient; MT, magnetization transfer; CEUS, contrast-enhanced ultrasound.
MRE, magnetic resonance enterography; DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient; DCE, dynamic contrast enhancement; MTR, magnetization transfer ratio; MT, magnetization transfer; AUC, area under received operating characteristic curve; USE, ultrasound elastography; US, ultrasound; SWE, shear wave elastography; CEUS, contrast-enhanced ultrasound; ARFI, acoustic radiation force impulse.