Quantitative evaluation of Crohn's disease using dynamic contrast-enhanced MRI in children and young adults

Multiparametric MRI for Staging of Bowel Inflammatory Activity in Crohn's Disease with MUSE-IVIM and DCE-MRI: A Preliminary Study

RATIONALE AND OBJECTIVES

To investigate if the combination of multishot diffusion imaging-based multiplexed sensitivity encoding intravoxel incoherent motion (MUSE-IVIM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is feasible for staging Crohn's disease (CD) activity.

MATERIALS AND METHODS

A total of 65 CD patients were enrolled and analyzed in this retrospective study. The simplified endoscopic score for Crohn's disease (SES-CD) and magnetic resonance index of activity (MaRIA) were used as the reference. The MUSE-IVIM and DCE-MRI data were acquired at 3.0-T MRI scanner and processed by two radiologists. Three MUSE-IVIM parameters: fast apparent diffusion coefficient (ADCfast), slow apparent diffusion coefficient (ADCslow), and the fractional perfusion (Fraction of ADCfast), as well as four DCE-MRI parameters: volume transfer constant (Ktrans), rate constant (Kep), extravascular extracellular volume fraction (Ve), and plasma volume fraction (Vp) were generated. Intraclass correlation coefficient (ICC), non-parametric test (Kruskal-Wallis H and Mann-Whitney U), logistic regression, receiver operating characteristic analysis, Delong test, and Spearman's correlation test were performed.

RESULTS

According to SES-CD, 116 ileocolonic segments with CD lesions were identified as: inactive, mild, and moderate to severe. With multivariable logistic regression analysis, ADCfast (p < 0.001), Fraction of ADCfast (p = 0.005), Ktrans (p < 0.001) and Kep (p = 0.003) were identified as significant factors for differentiating among the three groups. Binary logistic analyses identified ADCfast (p = 0.001), Ktrans (p = 0.014), and Kep (p = 0.029) as independent predictors for the active status. The combination of ADCfast, Ktrans, and Kep performed better than MaRIA score (p = 0.028), for differentiating inactive and active status. MaRIA score was positively correlated with ADCfast (p < 0.001), Ktrans (p < 0.001), Kep (p < 0.001), and Ve (p = 0.001), however, negatively correlated with Fraction of ADCfast (p < 0.001).

CONCLUSION

The combination of MUSE-IVIM and DCE-MRI has been demonstrated to accurately stage inflammatory activity in CD.

Contrast-Enhanced Ultrasonography for the Evaluation of Crohn's Disease in Pediatric Patients

BACKGROUND

Contrast-enhanced ultrasonography (CEUS) of the bowel wall has been suggested as an alternative imaging modality for the follow-up of children with Crohn's disease. To demonstrate the feasibility and clinical usefulness of CEUS in the estimation of Crohn's disease activity in children with endoscopy as the reference standard.

METHOD

In this prospective study, 30 pediatric patients with Crohn's disease (24 males and 6 females; median age 14 years) underwent CEUS from December 2020 to August 2021. The simple endoscopic score for Crohn's disease, pediatric Crohn's disease activity index, serologic inflammatory markers, fecal calprotectin and CEUS perfusion parameters were assessed and compared between the inactive and active group based on endoscopic findings.

RESULTS

CEUS was performed successfully in all 30 patients. Two patients showed mild adverse side effects such as temporary dysosmia. The active Crohn's disease group showed higher erythrocyte sedimentation rate (mm/hr) (13.0 vs. 2.0, P = 0.003), C-reactive protein (mg/dL) (4.7 vs. 0.55, P = 0.018) and fecal calprotectin (mcg/g) (1,503 vs. 237.5, P = 0.005). Among the quantitative parameters for CEUS, the mean gradient to the peak value was higher in the active group (1.18 vs. 0.93, P = 0.034). The sensitivity and specificity of the mean gradient to the peak value for predicting active Crohn's disease was 55.6% and 83.3%, respectively, with a cut-off of 1.09 (P = 0.015).

CONCLUSION

CEUS can be a safe and specific diagnostic modality for Crohn's disease activity in children. Among quantitative CEUS parameters, the mean gradient to the peak value could be used to differentiate active and inactive Crohn's disease.

Bowel wall MRI T1 relaxation estimates for assessment of intestinal inflammation in pediatric Crohn's disease

PURPOSE

To compare bowel wall T1 relaxation estimates in young patients with newly diagnosed ileal CD to healthy control participants, characterize their change over time in response to biologic medical therapy, and evaluate their associations with clinical markers of intestinal inflammation.

MATERIALS AND METHODS

Patients with newly diagnosed ileal CD and healthy control participants were prospectively recruited between December 2018 and October 2021. Patients underwent research MRI examinations of the bowel at baseline and at 6-weeks and 6-months into biologic medical treatment; control participants underwent single MRI examinations. MRI examinations included native T1 relaxometry of the terminal ileum using a modified Look-Locker inversion recovery (MOLLI) sequence. T1 estimates were measured on scanner-generated parametric maps. Clinical markers of intestinal inflammation were recorded at each visit. Group differences were assessed using the Mann-Whitney U test; the Friedman test was used to assess longitudinal changes in T1 estimates. Spearman correlation was used to evaluate associations between T1 estimates and inflammatory markers.

RESULTS

Nineteen participants with CD (12 males; median age 14 years) and 15 control participants (7 males; median age 17 years) were included in the study. Bowel wall T1 estimates in CD patients (median 1302 ms) were significantly longer compared to control participants (median 1159 ms) (p < 0.001). In CD patients, T1 estimates changed over time after treatment (p = 0.001), with largest reductions between baseline and 6-weeks (p < 0.001). T1 estimates correlated with inflammatory markers, including erythrocyte sedimentation rate (ρ = 0.35; p = 0.01), c-reactive protein level (ρ = 0.34; p = 0.02), and weighted Pediatric Crohn's Disease Activity Index (ρ = 0.39; p = 0.005). T1 estimates did not correlate with serum albumin (ρ = - 0.28; p = 0.051) and fecal calprotectin (ρ = 0.07; p = 0.63).

CONCLUSION

Bowel wall T1 estimates are abnormally increased in newly diagnosed ileal CD patients and decrease in response to medical therapy.

Evaluation of dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging for predicting muscular hyperplasia/hypertrophy in Crohn's disease

OBJECTIVES

The existence of smooth muscle alteration in Crohn's disease (CD) is often neglected. It has been found that muscular hyperplasia/hypertrophy rather than fibrosis was the primary component of bowel wall thickening. This study aimed to assess the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted imaging for the characterization of histopathologic tissue composition of CD, particularly smooth muscle hypertrophy, as well as inflammation and fibrosis.

METHODS

The study included patients diagnosed with CD who received MRI examination 30 days before resection from August 2016 to December 2020. A semiquantitative histological grading scheme was employed to evaluate the pathological tissues. Resected sections were matched with MRI according to pathological marks. Parameters evaluated included: mural thickness, T2 ratio, apparent diffusion coefficient value; and maximum enhancement, initial slope of increase, perfusion parameters of DCE-MRI and enhancement pattern. These parameters were compared with location-matched histopathological grade.

RESULTS

Ninety-one sections were enrolled in this retrospective study. When active inflammation is moderate or severe, volume transfer coefficient (K^trans), maximum enhancement (ME) and initial slope of increase (ISI) are lower, mural thickness is higher when a certain degree of smooth muscle alteration is present. When active inflammation is absent or mild, ME, mural thickness and ISI can differentiate the presence of predominant muscular alteration. By combining ME and thickness comparisons against their cutoff values to create a combined ordinal parameter, the area under the curve value for whether significant muscular alteration coexists with moderate or severe active inflammation was found to be 0.953.

CONCLUSIONS

MRI predicts the degree of inflammation, and can distinguish the degree of muscular alteration coexists with moderate or severe active inflammation with reasonable accuracy.

Dynamic contrast-enhanced (DCE) imaging: state of the art and applications in whole-body imaging

Dynamic contrast-enhanced (DCE) imaging is a non-invasive technique used for the evaluation of tissue vascularity features through imaging series acquisition after contrast medium administration. Over the years, the study technique and protocols have evolved, seeing a growing application of this method across different imaging modalities for the study of almost all body districts. The main and most consolidated current applications concern MRI imaging for the study of tumors, but an increasing number of studies are evaluating the use of this technique also for inflammatory pathologies and functional studies. Furthermore, the recent advent of artificial intelligence techniques is opening up a vast scenario for the analysis of quantitative information deriving from DCE. The purpose of this article is to provide a comprehensive update on the techniques, protocols, and clinical applications - both established and emerging - of DCE in whole-body imaging.

Magnetic resonance colonography with intestine-absorbable nanoparticle contrast agents in evaluation of colorectal inflammation

OBJECTIVES

To develop a nanoparticle-based MRI protocol based on transrectal administration of intestine-absorbable nanoparticle contrast agents to evaluate ulcerative colitis (UC).

METHODS

Solid lipid nanoparticles (SLNs) were synthesized by loading gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) and octadecylamine-fluorescein isothiocyanate to produce Gd-FITC-SLNs as T1 contrast agents. Twenty mice with acute UC were divided into four groups: enema with Gd-FITC-SLNs, intravenous injection of Gd-FITC-SLNs, enema with Gd-DTPA, and intravenous injection of Gd-DTPA. Five mice with chronic UC and five mice without UC underwent enema with Gd-FITC-SLNs. Axial T1- and T2-weighted MR images were obtained before and 20, 40, 60, 80,100, and 120 min after enema or intravenous injection of the contrast agent. The signal-to-noise ratios (SNRs) of the colorectal wall were measured in both groups. The MRI findings were correlated with subsequent histological confirmation.

RESULTS

At 20 min after enema with Gd-FITC-SLNs, MRI showed the following contrast enhancement pattern: acute UC > normal intestinal wall > chronic UC. A continuous enhancement effect was observed in mice with acute UC, whereas a slight continuous enhancement of the colorectal wall was observed in mice with chronic UC. The normal intestinal wall rapidly metabolized the contrast agent, and the enhancement decreased on sequential scans. There was no significant difference between the SNRs of the intestinal wall at 20 min after intravenous Gd-DTPA and transrectal Gd-FITC-SLN administration.

CONCLUSIONS

Enema with Gd-FITC-SLNs may be helpful for the diagnosis and differential diagnosis of acute and chronic UC and can confer the same or better results than with intravenous Gd-DTPA.

KEY POINTS

• Enema with Gd-FITC-SLNs may be helpful for the diagnosis and differential diagnosis of acute and chronic UC. • Enema with Gd-FITC-SLNs can achieve the same or better result than that with intravenous Gd-DTPA. • SLN-based MR colonography enhances the colorectal wall inflammation, based on the colonic absorption of the nanoparticle contrast agents.

Emerging Imaging Biomarkers in Crohn Disease

ABSTRACT

In this review article, we present the latest developments in quantitative imaging biomarkers based on magnetic resonance imaging (MRI), applied to the diagnosis, assessment of response to therapy, and assessment of prognosis of Crohn disease. We also discuss the biomarkers' limitations and future prospects. We performed a literature search of clinical and translational research in Crohn disease using diffusion-weighted MRI (DWI-MRI), dynamic contrast-enhanced MRI (DCE-MRI), motility MRI, and magnetization transfer MRI, as well as emerging topics such as T1 mapping, radiomics, and artificial intelligence. These techniques are integrated in and combined with qualitative image assessment of magnetic resonance enterography (MRE) examinations. Quantitative MRI biomarkers add value to MRE qualitative assessment, achieving substantial diagnostic performance (area under receiver-operating curve = 0.8-0.95). The studies reviewed show that the combination of multiple MRI sequences in a multiparametric quantitative fashion provides rich information that may help for better diagnosis, assessment of severity, prognostication, and assessment of response to biological treatment. However, the addition of quantitative sequences to MRE examinations has potential drawbacks, including increased scan time and the need for further validation before being used in therapeutic drug trials as well as the clinic.