Johannes M. Froehlich

Faecal tagging to avoid colonic cleansing before MRI colonography.

Colonic cleansing is unpleasant and has low acceptance by patients. We show the feasibility of faecal tagging, which obviates the need for colonic cleansing, in conjunction with internal magnetic resonance imaging colonography.

MR imaging in Crohn's disease: correlation of MR motility measurement with histopathology in the terminal ileum

The objective of the study was to correlate MR‐detectable motility alterations of the terminal ileum with biopsy‐documented active and chronic changes in Crohns disease.

Crohn's disease: small bowel motility impairment correlates with inflammatory-related markers C-reactive protein and calprotectin

To evaluate the correlation between the levels of C‐reactive protein (CRP), calprotectin, and small bowel motility in patients with Crohns disease assessed with MRI.

Software-assisted small bowel motility analysis using free-breathing MRI: Feasibility study

To validate a software prototype allowing for small bowel motility analysis in free breathing by comparing it to manual measurements.

Differentiation between active and chronic Crohn's disease using MRI small-bowel motility examinations — Initial experience

AIMnTo evaluate the influence of locally active Crohns disease on systemic small-bowel motility in patients with chronic Crohns disease compared to healthy individuals.nnnMATERIAL AND METHODSnFifteen healthy individuals (11 men, four women; mean age 37 years) and 20 patients with histopathologically proven active (n = 15; 10 women, 5 men; mean age 45 years) or chronic (n = 5; four women, one man; mean age 48 years) Crohns disease were included in this institutional review board-approved, retrospective study. Magnetic resonance imaging (MRI; 1.5 T) was performed after standardized preparation. Two-dimensional (2D) cine sequences for motility acquisition were performed in apnoea (27 s). Motility assessment was performed using dedicated software in three randomly chosen areas of the small-bowel outside known Crohns disease-affected hotspots. The main quantitative characteristics (frequency, amplitude, occlusion rate) were compared using Students t-test and one-way analysis of variance (ANOVA).nnnRESULTSnThree randomly chosen segments were analysed in each participant. Patients with active Crohns disease had significantly (p < 0.05) reduced contraction frequencies (active Crohns disease: 2.86/min; chronic: 4.14/min; healthy: 4.53/min) and luminal occlusion rates (active: 0.43; chronic: 0.70; healthy: 0.73) compared to healthy individuals and patients with chronic Crohns disease. Contraction amplitudes were significantly reduced during active Crohns disease (6.71 mm) compared to healthy participants (10.14 mm), but this only reached borderline significance in comparison to chronic Crohns disease (8.87 mm). Mean bowel lumen diameter was significantly (p = 0.04) higher in patients with active Crohns disease (16.91 mm) compared to healthy participants (14.79 mm) but not in comparison to patients with chronic Crohns disease (13.68).nnnCONCLUSIONnThe findings of the present study suggest that local inflammatory activity of small-bowel segments in patients with active Crohns disease alters small-bowel motility in distant, non-affected segments. The motility patterns revealed reduced contraction-wave frequencies, amplitudes, and decreased luminal occlusion rates. Thus evaluation of these characteristics potentially helps to differentiate between chronic and active Crohns disease.

Automatic detection of small bowel contraction frequencies in motility plots using lomb‐scargle periodogram and sinus‐fitting method—initial experience

Contraction frequencies are an important parameter for the analysis of bowel motility in MRI. The contraction curve can be rather noisy and the frequency‐evaluation might be difficult. The aim was to evaluate manual calculations of small bowel contraction frequency in comparison with automatic calculations using two mathematically established methods.

Software-assisted quantitative analysis of small bowel motility compared to manual measurements

AIMnTo validate a newly developed software prototype that automatically analyses small bowel motility by comparing it directly with manual measurement.nnnMATERIAL AND METHODSnForty-five patients with clinical indication for small bowel magnetic resonance imaging (MRI) were retrospectively included in this institutional review board-approved study. MRI was performed using a 1.5 T system following a standard MR-enterography protocol. Small bowel motility parameters (contractions-per-minute, luminal diameter, amplitude) were measured three times each in identical segments using the manual and the semiautomatic software-assisted method. The methods were compared for agreement, repeatability, and time needed for each measurement. All parameters were compared between the methods.nnnRESULTSnA total of 91 small-bowel segments were analysed. No significant intra-individual difference (p > 0.05) was found for peristaltic frequencies between the methods (mean: 4.14/min manual; 4.22/min software-assisted). Amplitudes (5.14 mm; 5.57 mm) and mean lumen diameters (17.39 mm; 14.68) differed due to systematic differences in the definition of the bowel wall. Mean duration of single measurement was significantly (p < 0.01) shorter with the software (6.25 min; 1.30 min). The scattering of repeated measurements was significantly (p < 0.05) lower using the software.nnnCONCLUSIONnThe software-assisted method accomplished highly reliable, fast and accurate measurement of small bowel motility. Measurement precision and duration differed significantly between the two methods in favour of the software-assisted technique.

Software‐supported evaluation of gastric motility in MRI: A feasibility study

The aim of this study was to evaluate the feasibility of dedicated motility assessment software for quantitative evaluation of basic gastric motility and to validate it using manual measurements.

Small-bowel dislocation during long-term MRI observation - insights in intestinal physiology.

Magnetic resonance imaging (MRI) of the abdomen is a widely established imaging modality in the diagnostic workup of patients suffering from abdominal disorders. Small‐bowel motility analyses using MRI have recently been introduced to provide functional information about the intestine not provided by morphological analyses. This is of clinical importance as motility disorders correlate with inflammation. Yet motility analyses mainly rely on a series of acquisitions in coronal orientation. Temporal displacement of small‐bowel loops out of the coronal slice could falsify qualitative and quantitative motility analyses. Thus, our study quantified three‐dimensional (3D) dislocation of small‐bowel loops during abdominal MRI examinations with the patient lying in prone position to investigate its influence on motility analyses. Our study revealed segmental small‐bowel displacement during MRI examinations in prone position to predominantly occur in craniocaudal orientation and in a smaller extent in lateral and ventrodorsal orientation. However, the displacement amplitudes are rather small and might not significantly influence small‐bowel motility analyses in 2D coronal plane in general.

Gadoxetate uptake as a possible marker of hepatocyte damage after liver resection-preliminary data

AIMnTo determine the feasibility of evaluating surgically induced hepatocyte damage using gadoxetate disodium (Gd-EOB-DTPA) as a marker for viable hepatocytes at magnetic resonance imaging (MRI) after liver resection.nnnMATERIAL AND METHODSnFifteen patients were prospectively enrolled in this institutional review board-approved study prior to elective liver resection after informed consent. Three Tesla MRI was performed 3-7 days after surgery. Three-dimensional (3D) T1-weighted (W) volumetric interpolated breath-hold gradient echo (VIBE) sequences covering the liver were acquired before and 20xa0min after Gd-EOB-DTPA administration. The signal-to-noise ratio (SNR) was used to compare the uptake of Gd-EOB-DTPA in healthy liver tissue and in liver tissue adjacent to the resection border applying paired Students t-test. Correlations with potential influencing factors (blood loss, duration of intervention, age, pre-existing liver diseases, postoperative change of resection surface) were calculated using Pearsons correlation coefficient.nnnRESULTSnBefore Gd-EOB-DTPA administration the SNR did not differ significantly (pxa0=xa00.052) between healthy liver tissue adjacent to untouched liver borders [59.55xa0±xa025.46 (SD)] and the liver tissue compartment close to the resection surface (63.31xa0±xa027.24). During the hepatocyte-specific phase, the surgical site showed a significantly (pxa0=xa00.04) lower SNR (69.44xa0±xa024.23) compared to the healthy site (78.45xa0±xa027.71). Dynamic analyses revealed a significantly lower increase (pxa0=xa00.008) in signal intensity in the healthy tissue compared to the resection border compartment.nnnCONCLUSIONnEOB-DTPA-enhanced MRI may have the potential to be an effective non-invasive tool for detecting hepatocyte damage after liver resection.