The Role of MRI in GERD

Fig. 2.1

Dynamic FFE pulse sequence in the sagittal view shows spontaneous gastroesophageal reflux (arrows) with typical caudo-cranial propagation of the bolus (a–d)

Dynamic MR imaging of reflux events requires an image plane that should be oriented through the GEJ. Thus, sagittal and coronal double-oblique angulated planes are preferred [14]. An axial orientation is favored for the detection and measurement of an axial hiatal hernia (Fig. 2.2).

Fig. 2.2

Dynamic B-FFE pulse sequence shows a fixed axial hernia filled with buttermilk-gadolinium (arrows) in the coronal (a), sagittal (b), and axial views (c). A spontaneous gastroesophageal reflux from the hiatal hernia is demonstrated (thick arrow)

These orientations, in combination with the use of three contiguous slices for better coverage of the entire esophagus, which is the main challenge in this examination, promise a good correlation between reflux events in MRI and pathologic DeMeester score in pH-metric studies [14]. Another publication did not report any correlation between reflux events in MRI and grade of reflux with endoscopic findings and Carlson’s questionnaire score [16]. Gastroesophageal reflux, detected on MRI, correlated to a Demeester score >14.7, which is indicative of gastroesophageal reflux, was diagnosed in 11 of 12 patients in a study by Zhnag et al. [7]. When comparing functional parameters between healthy volunteers and patients, statistically significant differences between healthy volunteers and patients could be evaluated based on diaphragm-to-sphincter distance, sphincter length, and sphincter transit time [7]. There was no significant difference of the HIS angle between healthy volunteers and patients, which is contrary to the longstanding hypothesis that a smaller HIS angle forms an anatomical antireflux barrier by a flap valve mechanism [26, 27].

The use of a simple and quick MR protocol, in combination with a good visible contrast medium, is mandatory to integrate this examination into the clinical routine.

The MRI is usually performed in the supine position on a 1.5 T or 3 T MRI, provided the patient is not at risk of aspiration. A body phased-array coil should be placed upon the chest. After a reference scan, a coronal T2-weighted, single-shot Turbo-Spin-Echo-sequence (TSE) or a T2-weighted half-Fourier-acquired, single-shot turbo spin echo (HASTE) sequence for orientation of the course of the esophagus and the gastro-esophageal junction (GEJ) should be performed. Then, a sagittal and an axial plane are obtained. After the “anatomical” static T2-weigthed sequences, a sagittal, oblique B-FFE (Balanced Fast Field Echo Sequence) or TrueFisp sequence (True Fast Imaging with steady state precession) with three contiguous slices is centered on the lower esophagus in the coronal view of the T2-weighted image according to these sequence parameters (Fig. 2.3). An additional coronal plane then is planned in the sagittal view. During these dynamic series, a buttermilk-gadolinium mixture (Dotarem^®, gadoterate meglumine, Guerbet, Germany) at a dilution of 40:1 is placed in a cup with a long plastic tube in the MR gantry. The other end of the plastic tube is placed into the patient’s mouth. Patients then are instructed to take a bolus in their mouth and swallow in a single gulp to prevent repetitive swallowing. If the coverage of the esophagus and the GEJ is inadequate, the pulse sequence is repeated in a slightly different angulation. Since there is increased awareness of the possible side effects of gadolinium or possible interaction between gadolinium and gastric acid, which has not, as yet, been verified, we have changed the oral contrast medium to Lumivision^® (Bender Group, b.e. imaging, Baden-Baden, Germany). Lumivision^® is a natural liquid contrast for oral application in MRI and contains different special fruit juices like pineapple, agave, and black currant. Patients with a hypersensitivity to these fruits, as well as patients with fructose malabsorption, should avoid taking this contrast medium. Diabetic patients must adjust their medication according to the sugar content (6.5BE per bottle of 250 ml Lumivision^®).

Fig. 2.3

Sequence parameter our routinely used MRI protocol

Real-time MRI offers a new perspective for a robust anatomic visualization combined with functional assessment of gastroesophageal reflux in patients. Another advantage is the possibility to directly view the surrounding structures, which is not possible with conventional examination techniques, for example, and represents a reliable tool with which to identify extraluminal findings. As a consequence, this non-invasive and non-ionizing approach has already shown great promise for the characterization of complex motions during swallowing, which could be of particular interest in pregnant and young patients. This method cannot replace ph-metry and manometry as measurable tools for the identification of reflux events and motility problems, but it could be a worthwhile method in pregnant patients, children, and other patients in whom a ph-metric/manometric tube cannot be placed.

2.3 The Role of MRI in Patients After Fundoplication

After a fundoplication procedure, radiologic work-up plays an important role in identifying possible problems.

The impact of a routinely conducted postoperative swallowing examination has been discussed controversially [28]. However, 2–17% of patients need a postoperative diagnostic clarification of their new or recurrent clinical symptoms, such as recurrent heartburn, regurgitation, or dysphagia. During the last several decades, a wide range of diagnostic modalities, such as endoscopy, pH monitoring, manometry, and barium swallow, were used to solve the possible problems. However, the modalities cover only a partial aspect of potential postoperative failure and are inaccurate in up to 40% of cases [29] in explaining the reason for dysphagia.

Because these patients are often young, a functional and morphologic imaging method without ionizing radiation was introduced in [15]. This study analyzed the role of MRI for the evaluation of anatomical and functional disorders after Nissen fundoplication compared to intraoperative findings in 29 patients. MRI was able to determine the position of the fundoplication wrap in 93% (Fig. 2.4), and correctly identified 67% of all malpositions of the wrap. Intrathoracic migration of the wrap, in particular, can be detected very well (Fig. 2.5). All wrap disruptions (Fig. 2.6), as well as all stenosis could be identify by MRI. In three cases, stenosis were caused by too-tight crural sutures, and, in two cases, by too-tight wraps. Stenosis that are shorter than 1 cm in length are usually caused by too-tight crural sutures. A stenosis measuring 2–3 cm in length is usually caused by a too-tight (Fig. 2.7) or too-long wrap (>3 cm).

Fig. 2.4

Normal postoperative appearance after Nissen fundoplication on MRI. The coronal (a) and sagittal (b) view shows the correct position of the wrap under the diaphragm. A ring-like “pseudotumor” (long arrow) of the fundoplication, and a well-defined smooth defect in the fundus (short arrow) acquired in the axial plane (c)

Fig. 2.5

Intrathoracic wrap migration. T2w HASTE sequences in the coronal view were performed to demonstrate the integrity of the wrap (long arrow) (a), but the wrap was detected above the esophageal hiatus and above the diaphragms (thin arrows) (b)

Fig. 2.6

Complete wrap disruption. Complete wrap disruption obtained in a patient with symptoms of recurrent reflux. The typical “pseudotumor” is missed on the coronal, sagittal and axial (arrows) view (a–c)

Fig. 2.7

Stenosis at the gastroesophageal junction. If the stenosis measures less than 1 cm in length (thin arrow) on the coronal and sagittal view, it strongly suggests too-tight crural sutures as the cause of dysphagia (a, b). A ballooning of the distal esophagus can be shown in the coronal view of the dynamic FFE pulse sequence (thick arrow) (c)

When abnormal esophageal motility is present before surgery, there is a greater likelihood of dysphagia developing after fundoplication [30]. The prolonged mechanical obstruction of the distal esophagus by the fundoplication wrap, with loss of peristalsis above the wrap, could be the cause of so-called secondary achalasia , even if there was normal esophageal motility before surgery.

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