Research article
Intra- and interobserver variability in the diagnosis of GERD by real-time MRI

https://doi.org/10.1016/j.ejrad.2018.04.029Get rights and content

Abstract

The purpose of this study was to assess the reproducibility of functional and anatomical parameters of swallowing events as determined by real-time MRI at 40 ms temporal resolution (25 frames per second). Twenty-three consecutive patients with gastroesophageal reflux disease (GERD) underwent real-time MRI of the gastroesophageal junction at 3.0 T. Real-time MRI was based on highly undersampled radial fast low angle shot (FLASH) acquisitions with iterative image reconstruction by regularized nonlinear inversion (NLINV). MRI movies visualized the esophageal transport of a pineapple juice bolus, its passage through the gastroesophageal junction and functional responses during a Valsalva maneuver. His-angle, sphincter position, sphincter length and sphincter transit time were assessed by two radiologists. Interobserver and intraobserver intraclass correlation coefficients (ICC) were evaluated and Bland-Altman plots were constructed to assess the observer agreement. Interobserver agreement was excellent for sphincter transit time (ICC = 0.92), His-angle (ICC = 0.93), His-angle during Valsalva maneuver (ICC = 0.91) and sphincter-to-diaphragm distance (ICC = 0.98). Sphincter length and oesophageal diameter showed good interobserver agreement (ICC = 0.62 and ICC = 0.70). Intraobserver agreement was good for sphincter length (ICC = 0.80) and excellent for sphincter transit time, His-angle and His-angle during Valsalva maneuver, sphincter-to-diaphragm distance, and esophageal diameter (ICC = 0.91; ICC = 0.97; ICC = 0.97; ICC = 0.998; ICC = 0.93). All functional parameters of the gastroesophageal junction had good to excellent reproducibility. Visual assessment of Bland Altman plots did not reveal any systematic interobserver bias. In conclusion, the visualization of swallowing events by real-time MRI has a high potential for clinical application in gastroesophageal reflux disease.

Introduction

Gastroesophageal reflux disease (GERD) has a prevalence of 10–20% in Western countries and about 5% in Asia and may lead to inflammation or histological changes occasionally resulting in cancer [1]. Proton pump inhibitors (PPI) are the mainstay of GERD treatment, but recent studies reported serious side effects of long-time PPI therapy, including hip fractures and pneumonias [2], [3]. Recent gastroenterological guidelines therefore revived surgery as therapeutic option [4]. However, defining the pathology of GERD by identifying dysfunction of gastroesophageal anti-reflux barrier or poor oesophageal and/or gastric motility is crucial for any treatment [5].

Traditionally, diagnosis of GERD relies on endoscopy and pH monitoring. Endoscopy is able to detect advanced oesophagitis, but has its drawbacks in determining pathological reflux in patients, who present without macroscopic erosions. Overall, 50–70% off all patients with GERD-related symptoms show non-erosive reflux disease (NERD) with normal endoscopy without mucosal injury [6,7]. Monitoring of pH has a better sensitivity and specificity than endoscopy, but non-acidic reflux episodes may provoke false positives and false negative results [8]. Moreover, the procedure requires discontinuation of acid-suppressive medication and may thus aggravate clinical symptoms. Due to low diagnostic accuracy, barium radiographs are currently not recommended to establish GERD diagnosis [4,9].

On the other hand, real-time MRI offers dynamic visualization of arbitrary physiologic processes with high image quality and 10–40 ms temporal resolution per frame, when based on highly undersampled radial fast low angle shot (FLASH) acquisitions with iterative image reconstruction by regularized nonlinear inversion (NLINV) [10,11]. This allows for the identification of gastroesophageal reflux by anatomical and functional visualization of the gastroesophageal junction, including the His-angle, sphincter position, sphincter length and transit time. In a preceding application to a small series of patients, this technique was able to identify the pathology responsible for GERD [12]. The diagnostic accuracy of real-time MRI for detection of GERD still has to be analysed, in particular given its complex, time consuming and expensive imaging procedure. Moreover, the influence of radiological observers on real-time MRI measures of the gastroesophageal junction has yet to be defined. Therefore, we conducted this study to evaluate the observer-dependent reproducibility of real-time MRI in the diagnosis of GERD.

Section snippets

Study population

Twenty-three consecutive patients who presented themselves in our surgical outpatient clinic (Department of Surgery and Department of Gastroenterology and Gastrointestinal Oncology of the University Medical Center Goettingen, Germany) with typical GERD-related symptoms and pathological endoscopy, pH monitoring, or manometry were included in this study. No patients were excluded for contraindications to MRI imaging or inability to swallow. Previous or concurrent PPI therapy was no exclusion

Patient collective, endoscopy, impedance, pH monitoring and manometry

All 23 patients (10 men and 13 women) presented with typical GERD-related symptoms. Mean age was 53 (SD ± 17) years with a range of 21–74 years and mean time of symptoms was 36 months (range of 6–120 months). Sixteen patients were under PPI medication and three patients reported no relief of symptoms by medication. Endoscopy of all 23 patients revealed gastric hernia in 15 patients. There was evidence of esophagitis in 4 patients and no evidence for cancer. Impedance and pH monitoring was

Discussion

In this study, we evaluated the observer-dependent reproducibility of real-time MRI analyses in the diagnosis of GERD. There was no difference in the interobserver and intraobserver judgment of the underlying pathology causing GERD in a group of 23 patients using real-time MRI in non-standard planes as previously proposed by Zhang et al., [12].

First, a high concordance of interobserver data on functional parameters was found. Sphincter transit time, His-angle and sphincter-to-diaphragm distance

Conclusions

Functional parameters of swallowing events based on real-time MRI analyses of the gastroesophageal junction show excellent inter- and intraobserver agreement. Overall, real-time MRI is a promising new technique for the evaluation of the gastroesophageal junction.

Conflicts of interest

JF and MU are co-inventors of a patent covering the real-time MRI technique used in this study.

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    Modern ultrafast MRI sequences visualize the esophagus and gastroesophageal junction and allows for dynamic assessment of reflux during repetitive Valsalva maneuver with a high tissue contrast of surrounding anatomical structures in real time at a temporal resolution of up to 20 ms. These sequences are optimized for pineapple juice as an oral contrast agent and do not necessitate off-label oral or intravenous application of gadolinium-based MRI contrast agents [16,17]. Previous feasibility studies showed promising results for the evaluation of anatomical and functional parameters as well as detection of fundoplication failure [18,19]. The diagnostic potential of real-time MRI for the detection of gastroesophageal reflux has yet to be evaluated.

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