Diagnosis of Gastroesophageal Reflux Disease Using Real-time Magnetic Resonance Imaging

Visualization of deglutition and gastroesophageal reflux using real-time MRI: a standardized approach to image acquisition and assessment

This study aims to develop a standardized algorithm for gastroesophageal image acquisition and diagnostic assessment using real-time MRI. Patients with GERD symptoms undergoing real-time MRI of the esophagus and esophagogastric junction between 2015 and 2018 were included. A 10 ml bolus of pineapple juice served as an oral contrast agent. Patients performed Valsalva maneuver to provoke reflux and hiatal hernia. Systematic MRI assessment included visual presence of achalasia, fundoplication failure in patients with previous surgical fundoplication, gastroesophageal reflux, and hiatal hernia. A total of 184 patients (n = 92 female [50%], mean age 52.7 ± 15.8 years) completed MRI studies without adverse events at a mean examination time of 15 min. Gastroesophageal reflux was evident in n = 117 (63.6%), hiatal hernia in n = 95 (52.5%), and achalasia in 4 patients (2.2%). Hiatal hernia was observed more frequently in patients with reflux at rest (n = 67 vs. n = 6, p < 0.01) and during Valsalva maneuver (n = 87 vs. n = 8, p < 0.01). Real-time MRI visualized a morphologic correlate for recurring GERD symptoms in 20/22 patients (90%) after fundoplication procedure. In a large-scale single-center cohort of patients with GERD symptoms undergoing real-time MRI, visual correlates for clinical symptoms were evident in most cases. The proposed assessment algorithm could aid in wider-spread utilization of real-time MRI and provides a comprehensive approach to this novel imaging modality.

Real-Time Magnetic Resonance Imaging

Real-time magnetic resonance imaging (RT-MRI) allows for imaging dynamic processes as they occur, without relying on any repetition or synchronization. This is made possible by modern MRI technology such as fast-switching gradients and parallel imaging. It is compatible with many (but not all) MRI sequences, including spoiled gradient echo, balanced steady-state free precession, and single-shot rapid acquisition with relaxation enhancement. RT-MRI has earned an important role in both diagnostic imaging and image guidance of invasive procedures. Its unique diagnostic value is prominent in areas of the body that undergo substantial and often irregular motion, such as the heart, gastrointestinal system, upper airway vocal tract, and joints. Its value in interventional procedure guidance is prominent for procedures that require multiple forms of soft-tissue contrast, as well as flow information. In this review, we discuss the history of RT-MRI, fundamental tradeoffs, enabling technology, established applications, and current trends. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 1.

Computed tomographic features of gastric and esophageal content in dogs undergoing CT myelography and factors influencing the presence of esophageal fluid

Background

Gastroesophageal reflux (GER) has been reported to be a common finding in dogs under general anesthesia.

Objectives

The aim of this retrospective study was to assess the esophageal and gastric contents in a population of dogs undergoing computed tomographic myelography (myelo-CT) examination and to evaluate the factors influencing the presence of esophageal fluid (gastric content, duration of anesthesia, body position, and intrinsic factors).

Methods

Esophageal and gastric contents of 83 non-brachycephalic dogs were retrospectively assessed based on plain and myelo-CT scans. Age, weight, breed, sex, and the time between the 2 computed tomography [CT] scans were included.

Results

Esophageal fluid was present in 19% (16/83) of the animals, and 14% (12/83) and 46% (37/83), respectively, had fluid or food material in their stomachs. The frequency of observing esophageal fluid on myelo-CT scans was significantly increased compared with plain CT scans (p = 0.006). The presence of gastric fluid was significantly associated with an increased frequency of observing esophageal fluid compared to other gastric contents (p = 0.049; odds ratio, 3.1). The presence of esophageal fluid was not correlated with alimentary gastric contents (p = 0.17). Increased body weight and duration of anesthesia were significantly associated with an increased frequency of observing esophageal fluid (p = 0.022, p = 0.021).

Conclusions

Unlike alimentary gastric contents, fluid gastric contents were correlated with the presence of esophageal fluid upon myelo-CT. The observation of fluid in the esophagus may be consistent with GER. This study provides data additional to pH monitoring studies of GER and may support previous studies recommending shorter pre-anesthetic fasting periods in dogs.

Performance of a new natural oral contrast agent (LumiVision®) in dynamic MR swallowing

Objectives

To evaluate image quality by first use of LumiVision® in dynamic MR swallowing, a contrast medium consisting of biological substances versus a gadolinium-buttermilk mixture in patients who underwent Nissen fundoplication due to gastroesophageal reflux disease (GERD).

Methods

The protocol of this retrospective study was approved by the local Institutional Review Board. A hundred twenty-nine patients (146 examinations) underwent a dynamic MR swallowing study (at 1.5 T or 3.0 T) and received an oral contrast agent. Two readers evaluated the distention of the esophagus, contrast, and traceability of the bolus in a 3-point scale. A steady-state coherent sequence (B-FFE, TrueFISP) was used. The patients were divided into 3 different groups: 53 patients received gadolinium chelate (Dotarem®)–buttermilk mixture (GBM) in a dilution of 1:40 as an oral contrast agent; 44 patients received LumiVision® water mixture (LWM) in a dilution of 1:1 and 49 patients received LumiVision® (L) undiluted.

Results

GBM showed significantly better results in overall evaluation for both readers in contrast to LWM (p = .003, p = .002). L also reached significantly better results in overall evaluation than LWM in both readers (p = .004, p = .042). There was no significant difference in the overall evaluation between L and GBM (p = .914, p = .376).According to Landis and Koch, interobserver agreement was “substantial” (Cohen’s kappa = 0.738) between both readers.

Conclusion

LumiVision® undiluted showed equal image quality compared to gadolinium-buttermilk mixture. The constellation of LumiVision® water mixture led to a clearly negative result in relation to the image quality compared to LumiVision® undiluted. Therefore, oral ingestion of LumiVision® undiluted is recommended for MR swallowing examinations.

Key Points

• LumiVision® undiluted shows significantly better image quality in comparison to LumiVision® diluted in oral application in swallowing MRI.

• LumiVision® undiluted shows equal image quality in comparison to gadolinium-buttermilk mixture in oral application.

• Oral ingestion of LumiVision® undiluted can replace gadolinium-buttermilk mixture in oral MR examinations.

Assessment of esophageal motility disorders by real-time MRI

PURPOSE

To investigate imaging findings of esophageal motility disorders on dynamic real-time.

MATERIAL AND METHODS

102 patients with GERD-like symptoms were included in this retrospective study between 2015-2018. Dynamic real-time MRI visualized the transit of a 10 mL pineapple juice bolus through the esophagus and EGJ with a temporal resolution of 40 ms. Dynamic and anatomic parameters were measured by consensus reading. Imaging findings were compared to HRM utilizing the Chicago classification of esophageal motility disorders, v3.0.

RESULTS

All 102 patients completed real-time MRI in a median examination time of 15 min. On HRM, 14 patients presented with disorders with EGJ outlet obstruction (EGJOO) (13.7 %), 7 patients with major disorders of peristalsis (6.9 %), and 32 patients with minor disorders of peristalsis (31.4 %). HRM was normal in 49 patients (48.0 %). Incomplete bolus clearance was significantly more frequent in patients with esophageal motility disorders on HRM than in patients with normal HRM (p = 0.0002). In patients with motility disorders with EGJOO and major disorders of peristalsis, the esophageal diameter tended to be wider (23.6 ± 8.0 vs. 21.2 ± 3.5 mm, p = 0.089) and the sphincter length longer (19.7 ± 7.3 vs. 16.7 ± 3.0 mm, p = 0.091) compared to patients with normal HRM. 3/7 patients with achalasia type II were correctly identified by real-time MRI and one further achalasia type II patient was diagnosed with a motility disorder on MRI films. The other 3/7 patients presented no specific imaging features.

CONCLUSION

Real-time MRI is an auxiliary diagnostic tool for the assessment of swallowing events. Imaging parameters may assist in the detection of esophageal motility disorders.

Real-Time Magnetic Resonance Imaging: Radial Gradient-Echo Sequences With Nonlinear Inverse Reconstruction

OBJECTIVE

The aim of this study is to evaluate a real-time magnetic resonance imaging (MRI) method that not only promises high spatiotemporal resolution but also practical robustness in a wide range of scientific and clinical applications.

MATERIALS AND METHODS

The proposed method relies on highly undersampled gradient-echo sequences with radial encoding schemes. The serial image reconstruction process solves the true mathematical task that emerges as a nonlinear inverse problem with the complex image and all coil sensitivity maps as unknowns. Extensions to model-based reconstructions for quantitative parametric mapping further increase the number of unknowns, for example, by adding parameters for phase-contrast flow or T1 relaxation. In all cases, an iterative numerical solution that minimizes a respective cost function is achieved with use of the iteratively regularized Gauss-Newton method. Convergence is supported by regularization, for example, to the preceding frame, whereas temporal fidelity is ensured by downsizing the regularization strength in comparison to the data consistency term in each iterative step. Practical implementations of highly parallelized algorithms are realized on a computer with multiple graphical processing units. It is "invisibly" integrated into a commercial 3-T MRI system to allow for conventional usage and to provide online reconstruction, display, and storage of regular DICOM image series.

RESULTS

Depending on the application, the proposed method offers serial imaging, that is, the recording of MRI movies, with variable spatial resolution and up to 100 frames per second (fps)-corresponding to 10 milliseconds image acquisition times. For example, movements of the temporomandibular joint during opening and closing of the mouth are visualized with use of simultaneous dual-slice movies of both joints at 2 × 10 fps (50 milliseconds per frame). Cardiac function may be studied at 30 to 50 fps (33.3 to 20 milliseconds), whereas articulation processes typically require 50 fps (20 milliseconds) or orthogonal dual-slice acquisitions at 2 × 25 fps (20 milliseconds). Methodological extensions to model-based reconstructions achieve improved quantitative mapping of flow velocities and T1 relaxation times in a variety of clinical scenarios.

CONCLUSIONS

Real-time gradient-echo MRI with extreme radial undersampling and nonlinear inverse reconstruction allows for direct monitoring of arbitrary physiological processes and body functions. In many cases, pertinent applications offer hitherto impossible clinical studies (eg, of high-resolution swallowing dynamics) or bear the potential to replace existing MRI procedures (eg, electrocardiogram-gated cardiac examinations). As a consequence, many novel opportunities will require a change of paradigm in MRI-based radiology. At this stage, extended clinical trials are needed.

Measuring three-dimensional tibiofemoral kinematics using dual-slice real-time magnetic resonance imaging

PURPOSE

The purpose of this study is to propose and evaluate a slice-to-volume registration (SVR) method integrating an advanced dual-slice real-time magnetic resonance image (MRI) and three-dimensional (3D) MRI volume of the tibiofemoral joint for determining their 3D kinematics.

METHODS

The real-time and 3D MRI of the knee were collected from 12 healthy adults at 5 static flexion positions and during dynamic flexion/extension movement. The 3D positions and orientations of the femur and tibia were obtained by registering their volumetric models constructed from the 3D MRI to dual-slice real-time MRI using an optimization process. The proposed method was quantitatively evaluated for its performance in terms of the robustness and measurement accuracy, and compared to those of a single-slice SVR method. Its repeatability in measuring knee kinematics during flexion/extension movement was also determined.

RESULTS

In comparison to the single-slice SVR method, the dual-slice method was significantly superior, giving a successful registration rate > 95%, a bias less than 0.5 mm in translations and 0.6° in rotations and a precision <0.7 mm in translations and 0.9° in rotations for determining the 3D tibiofemoral poses. For repeatability of the dual-slice SVR in measuring tibiofemoral kinematics during dynamic flexion/extension, the means of the time-averaged standard deviations were <0.9° for joint angles and 0.5 mm for joint translations.

CONCLUSION

A dual-slice SVR method in conjunction with real-time MRI has been developed and evaluated for its performance in measuring 3D kinematics of the tibiofemoral joint in 12 young adults in terms of the accuracy, robustness, and repeatability. The proposed MRI-based 3D measurement method provides a noninvasive and ionizing radiation-free approach for 3D kinematic measurement of the tibiofemoral joint, which will be helpful for future academic and clinical applications.

Follow Up Data of MRI-Visible Synthetic Meshes for Reinforcement in Large Hiatal Hernia in Comparison to None-Mesh Repair-A Prospective Cohort Study

Background: Mesh augmentation for large hiatal hernia is still controversial because of high alleged risk of chronic reaction or shrinkage of mesh orifice surrounding the esophagus. The aim of this cohort study was to develop and establish an image analysis scheme, including 3D reconstruction, for MRI-visible meshes (DynaMesh®) to measure postoperative mesh shrinkage in order to observe potential complications. Methods: Between 12/2012 and 10/2016, n = 33 patients underwent surgery to correct symptomatic hiatal hernia (implantation indicated: n = 18). Intraoperative measurement of the hiatal surface area (HSA) > 5 cm² was indication for mesh implantation. Early postoperatively, and during long-term follow-up, MRI was performed and patients filled out the gastrointestinal quality of life index (GIQLI score). Results: Follow-up rate was 76% (n = 25/33). Overall recurrence rate was 4% (1/25). No other patient showed reflux or dysphagia symptoms. Mesh related complications were not observed during follow-up period. Median GIQLI score of patients with mesh was 123 (range: 67-144), and 93 (52-141) for patients without mesh. Comparison of early and mid-term postoperative MRI for patients with mesh showed changes in mesh orifice size of 3% (corresponding to a slight increase in size of about 6 mm²) without any significant correlations with BMI, HSA, or patient age. Conclusion: We established an image analysis and 3D reconstruction scheme for MRI visible meshes in hiatal hernia repair. MRI images of normal clinical quality are sufficient for this analysis. Mesh orifice size in MRI-visible meshes does not seem to change at a clinically relevant level in the small cohort observed here. Further studies of large cohorts are necessary to establish if HSA >5 cm² could be a suitable measure for indication of mesh implantation.

Multi-slice real-time MRI of temporomandibular joint dynamics

OBJECTIVES

The purpose of this work was to improve the clinical versatility of high-speed real-time MRI studies of temporomandibular joint (TMJ) dynamics by simultaneous recordings of multiple MRI movies in different sections.

METHODS

Real-time MRI at 3 T was realized using highly undersampled radial FLASH acquisitions and image reconstruction by regularized nonlinear inversion (NLINV). Multi-slice real-time MRI of two, three or four slices at 0.75 mm resolution and 6 to 8 mm thickness was accomplished at 50.0 ms, 33.3 ms or 25.5 ms temporal resolution, respectively, yielding simultaneous movies at 2 × 10, 3 × 10 or 4 × 10 frames per second in a frame-interleaved acquisition mode. Real-time MRI movies were evaluated by three blinded raters for visibility of the anterior and posterior border of disc, shape of the disk body and condyle head as well as movement of the disc and condyle (1 = excellent, 5 = no visibility).

RESULTS

Effective delineation of the disk atop the mandibular condyle was achieved by T1-weighted images with opposed-phase water-fat contrast. Compared to 8 mm sections, multi-slice recordings with 6 mm thickness provided sharper delineation of relevant structures as confirmed by inter-rater evaluation. Respective dual-slice and triple-slice recordings of a single TMJ as well as dual-slice recordings of both joints (one slice per TMJ) received the highest visibility ratings of ≤ 2 corresponding to high confidence in diagnostic content.

CONCLUSIONS

The improved access to TMJ dynamics by multi-slice real-time MRI will contribute to more effective treatment of temporomandibular disorders.

Concentrated pineapple juice for visualisation of the oesophagus during magnetic resonance angiography before atrial fibrillation radiofrequency catheter ablation

The purpose of this study was to compare in vitro pineapple juice and a solution of concentrated pineapple juice with a paramagnetic contrast agent in order to determine the feasibility of using the solution of concentrated pineapple juice in vivo for oesophagus visualisation at magnetic resonance angiography (MRA) before the radiofrequency catheter ablation procedure for atrial fibrillation. The pineapple juice was concentrated by a microwave heating evaporation process performed in a domestic microwave oven. Five grams of modified potato starch for every 40 mL of concentrated pineapple juice were added to the concentrated pineapple juice in order to thicken the solution. The solution resulted visually and quantitatively as hyperintense as the contrast agent in vitro (ratio = 1.02). in vivo, no technical difficulties were encountered during the MRA acquisition and a complete enhanced oesophagus was obtained in 37/38 patients (97.4%). The volumetric analysis and the three-dimensional reconstruction were feasible; the quality was rated as diagnostic in every patient. The intensified oesophagus was successfully merged into the electro-anatomical maps in all the patients. In summary, we demonstrated that this technique allows a feasible and safe oesophagus visualisation during MRA.

Accelerated Computing in Magnetic Resonance Imaging: Real-Time Imaging Using Nonlinear Inverse Reconstruction

Purpose

To develop generic optimization strategies for image reconstruction using graphical processing units (GPUs) in magnetic resonance imaging (MRI) and to exemplarily report on our experience with a highly accelerated implementation of the nonlinear inversion (NLINV) algorithm for dynamic MRI with high frame rates.

Methods

The NLINV algorithm is optimized and ported to run on a multi-GPU single-node server. The algorithm is mapped to multiple GPUs by decomposing the data domain along the channel dimension. Furthermore, the algorithm is decomposed along the temporal domain by relaxing a temporal regularization constraint, allowing the algorithm to work on multiple frames in parallel. Finally, an autotuning method is presented that is capable of combining different decomposition variants to achieve optimal algorithm performance in different imaging scenarios.

Results

The algorithm is successfully ported to a multi-GPU system and allows online image reconstruction with high frame rates. Real-time reconstruction with low latency and frame rates up to 30 frames per second is demonstrated.

Conclusion

Novel parallel decomposition methods are presented which are applicable to many iterative algorithms for dynamic MRI. Using these methods to parallelize the NLINV algorithm on multiple GPUs, it is possible to achieve online image reconstruction with high frame rates.

High-resolution manometry in patients with and without globus pharyngeus and/or symptoms of laryngopharyngeal reflux

Background

Globus pharyngeus is common and has a low cure rate. Its etiology is complex and reported to be associated with laryngopharyngeal reflux (LPR). However, some patients with globus do not exhibit any reflux symptoms or respond to proton pump inhibitors (PPIs) treatments. The purpose of this study was to clarify the related risk factors of these patients with a final objective of improving the curative effect.

Methods

Forty two patients afflicted with globus pharyngeus (G group) and 38 patients without globus pharyngeus (NG group) were included in this study. According to the laryngopharyngeal Reflux Symptom Index and the response to PPIs treatments, the patients were further divided into reflux groups (G-R, NG-R) and non-reflux groups (G-NR, NG-NR). High Resolution Manometry (HRM) was performed to assess esophageal motility. Questionnaires, including categories such as life exposure factors, were conducted.

Results

a) The average resting and residual pressures of the upper esophageal sphincter (UES) in the G-NR group was higher than in the NG-NR and NG-R groups (P < 0.05). b) The average resting and residual pressures of the lower esophageal sphincter showed no differences between the G-NR group and the NG-NR group (P > 0.05). c) The esophageal distal contractile integral score of the G-NR group was not different from the NG-NR group (P > 0.05). d) Compared to the NG-NR group, the G-NR group showed higher incidence of stress, smoking, drinking, high salt and anxiety (P < 0.05).

Conclusions

Globus pharyngeus without LPR may occur due to high UES pressure. Stress, smoking, alcoholic drinking, high salt and anxiety may be its risk factors.

Electronic supplementary material

The online version of this article (10.1186/s12876-017-0666-x) contains supplementary material, which is available to authorized users.

Towards MRI temperature mapping in real time-the proton resonance frequency method with undersampled radial MRI and nonlinear inverse reconstruction

BACKGROUND

Optimal control of minimally invasive interventions by hyperthermia requires dynamic temperature mapping at high temporal resolution.

METHODS

Based on the temperature-dependent shift of the proton resonance frequency (PRF), this work developed a method for real-time MRI thermometry which relies on highly undersampled radial FLASH MRI sequences with iterative image reconstruction by regularized nonlinear inversion (NLINV). As a first step, the method was validated with use of a temperature phantom and ex vivo organs (swine kidney) subjected to heating by warm water or a pulsed laser source.

RESULTS

The temperature maps obtained by real-time PRF MRI demonstrate good accuracy as independently controlled by fiber-optic temperature sensors. Moreover, the dynamic results demonstrate both excellent sensitivity to single laser pulses (20 ms duration, 6 J energy output) and high temporal resolution, i.e., 200 ms acquisition times per temperature map corresponding to a rate of 5 frames per second. In addition, future extensions to in vivo applications were prepared by addressing the breathing-related motion problem by a pre-recorded library of reference images representative of all respiratory states.

CONCLUSIONS

The proposed method for real-time MRI thermometry now warrants further developments towards in vivo MRI monitoring of thermal interventions in animals.

Real-time magnetic resonance imaging of deep venous flow during muscular exercise-preliminary experience

BACKGROUND

The accurate assessment of peripheral venous flow is important for the early diagnosis and treatment of disorders such as deep-vein thrombosis (DVT) which is a major cause of post-thrombotic syndrome or even death due to pulmonary embolism. The aim of this work is to quantitatively determine blood flow in deep veins during rest and muscular exercise using a novel real-time magnetic resonance imaging (MRI) method for velocity-encoded phase-contrast (PC) MRI at high spatiotemporal resolution.

METHODS

Real-time PC MRI of eight healthy volunteers and one patient was performed at 3 Tesla (Prisma fit, Siemens, Erlangen, Germany) using a flexible 16-channel receive coil (Variety, NORAS, Hoechberg, Germany). Acquisitions were based on a highly undersampled radial FLASH sequence with image reconstruction by regularized nonlinear inversion at 0.5×0.5×6 mm³ spatial resolution and 100 ms temporal resolution. Flow was assessed in two cross-sections of the lower leg at the level of the calf muscle and knee using a protocol of 10 s rest, 20 s flexion and extension of the foot, and 10 s rest. Quantitative analyses included through-plane flow in the right posterior tibial, right peroneal and popliteal vein (PC maps) as well as signal intensity changes due to flow and muscle movements (corresponding magnitude images).

RESULTS

Real-time PC MRI successfully monitored the dynamics of venous flow at high spatiotemporal resolution and clearly demonstrated increased flow in deep veins in response to flexion and extension of the foot. In normal subjects, the maximum velocity (averaged across vessel lumen) during exercise was 9.4±5.7 cm·s^-1 for the right peroneal vein, 8.5±4.6 cm·s^-1 for the right posterior tibial vein and 17.8±5.8 cm·s^-1 for the popliteal vein. The integrated flow volume per exercise (20 s) was 1.9, 1.6 and 50 mL (mean across subjects) for right peroneal, right posterior tibial and popliteal vein, respectively. A patient with DVT presented with peak flow velocities of only about 2 cm·s^-1 during exercise and less than 1 cm·s^-1 during rest.

CONCLUSIONS

Real-time PC MRI emerges as a new tool for quantifying the dynamics of muscle-induced flow in deep veins. The method provides both signal intensity changes and velocity information for the assessment of blood flow and muscle movements. It now warrants extended clinical trials to patients with suspected thrombosis.

Real-time MRI of swallowing: intraoral pressure reduction supports larynx elevation

The reduction in intraoral pressure during swallowing has previously been linked to bolus transport, although no such relation has yet been proven. The purpose of this work was to evaluate the time course of intraoral pressure during swallowing using simultaneous real-time magnetic resonance imaging (MRI) and dynamic pressure recordings. Real-time MRI based on highly undersampled radial fast low-angle shot (FLASH) and regularized nonlinear inverse reconstruction was performed at 3 T using a standard head coil and a mid-sagittal section covering the entire oral cavity. Voluntary swallowing (10 mL of pineapple juice or saliva) was monitored for about 30 s in 11 normal subjects at spatial and temporal resolution of 1.3 × 1.3 × 8 mm³ and 40 ms, respectively. Simultaneously, the intraoral atmospheric pressure was recorded at a resolution of 10 ms during the entire course of deglutition. Quantitative measures of bolus transport, larynx elevation and submental muscle changes were obtained from the image series. As a key result, negative intraoral pressure accompanied laryngeal elevation during swallowing in all subjects. A reduction in submental muscle length during swallowing was also observed. No correlations of maximum negative pressure with larynx elevation and submental muscle change were found. In conclusion, intraoral pressure reduction during swallowing is not connected to oral bolus transport, but supports laryngeal elevation by palatal fixation of the tongue.