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Page 2 of 11 Stier et al. Mini-invasive Surg 2020;4:18 I http://dx.doi.org/10.20517/2574-1225.2019.75

Conclusion: 3D-CT is easy-to-perform and facilitates identification of the post-surgical three-dimensional gastric
anatomy. It represents a valuable additional diagnostic tool in post-bariatric patients with post-procedural complications.
3D-CT might be an important preoperative tool prior to revisional surgery. In addition, this is the only exact and
reproducible calculation of the gastric volume.

Keywords: Gastrointestinal tract, computed tomography, gastric volumetry, 3D-reconstruction, anatomical accuracy

INTRODUCTION
Bariatric surgery has been shown to be an effective and safe treatment for obesity and metabolic
[1-3]
disorders . However, a number of postsurgical complications may arise, including gastroesophageal
reflux disease (GERD), epigastric pain, vomiting, and, especially in bariatric patients, poor weight loss
[4,5]
or weight regain . These symptoms can appear at different times. Some are evident already shortly
after the operation, but others appear only years after a procedure. Whilst weight regain is such a special
issue in bariatric patients, an objective measurement of gastric or pouch volume is difficult, even if the
increase in gastric volume is being discussed more and more as an underlying cause. Comparability
of former, contemporary and future examinations is even more complex. Upper endoscopy (UE) and
upper gastrointestinal series (UGI) are the most important diagnostic tools after general surgery of the
upper gastrointestinal tract. While the sensitivity of UE is high in patients with upper gastrointestinal
[6]
symptoms , in the case of insufficient weight loss or weight regain, as well as in anatomically confusing
conditions, UE and UGI contrast studies are often not conclusive. UE is more useful in gathering
information concerning pouch- or stoma-related complications, whereas UGI is a more effective means
[7]
of detecting oesophageal or Roux-limb abnormalities , all of which are possible standard reasons for
upper abdominal pain after bariatric surgery, but mostly do not account for an occurring weight regain or,
moreover, the special complications that have already tried to be clarified before and elsewhere.

Quantitative three-dimensional computed tomography volumetry (3D-CT) of the upper gastrointestinal
tract is a not very widespread technique and is rarely used in general, but for years has been frequently
used in some specialised bariatric centres. By providing pivotable, 3D-reconstructed pictures of the
anatomy, on the one hand, it enables robust and accurate preoperative planning in patients undergoing
[8]
complex revisional bariatric surgery . On the other hand, and as a worthwhile side-effect of the technique
itself, 3D-CT is a useful and exclusive tool for accurate volume measurement. For example, with the aid
[9]
of 3D-CT, Hanssen et al. demonstrated that initial sleeve volume ≥ 100 mL is significantly related to
insufficient weight loss after bariatric surgery.

The aim of this study was to demonstrate the clinical usefulness of 3D-CT to assess accurately the shape
and anatomy, and, further, its additional value as an exclusive diagnostic tool for gastric volumetry and
quantitation after bariatric surgery.

METHODS
Examination protocol of the 3D-CT
To achieve a high level of comparability, a standardised examination protocol for the 3D-CT was invented
and established years ago. A dedicated and trained bariatric team monitored all examinations.

Patients had to fast at least 6 h before the scheduled examination. To prepare for the CT-study, shortly before
the examination, all patients received 20 mg butylscopolamin as intravenous injection to reduce gastrointestinal
motility during the procedure. Immediately before scanning, each patient swallowed 11.8 g (two sachets) of a
commercially available effervescent powder (Ahoi Brause, Frigeo), which is normally used in the preparation