Biomedical subjects

Jens B Frøkjaer

Publications and source records attributed to Jens B Frøkjaer.

3 recordsLinked to original sources

PubMed2006

The functional lumen imaging probe (FLIP) for evaluation of the esophagogastric junction.

There is a need for new methods to study the dynamics of the esophagogastric junction (EGJ). The aims were to verify the efficacy and usefulness of a "functional lumen imaging probe" (FLIP) for the evaluation of the EGJ. Eight healthy volunteers (6 men), median age 26 (21-35) yr, and two achalasia patients underwent the FLIP procedure. The EGJ was located by manometry. The FLIP measured eight cross-sectional areas (CSAs) 4 mm apart together with the pressure inside a saline-filled cylindrical bag. The data showed the geometric profile of the EGJ reconstructed in a video animation of its dynamic activity. A plot of curve-fitted data for the smallest CSA vs. pressure after balloon distension indicated that the pressure increased from 18 cmH2O at a CSA of 38 mm2 to a pressure of 37 cmH2O at a CSA of 230 mm2 for the healthy controls. In one achalasia patient (unsuccessfully treated with dilations), the CSA never rose above the minimal measurable value despite the pressure increasing to 50 cmH2O. In another achalasia patient (successfully treated with dilations), the pressure only reached 15 cmH2O despite opening to a CSA of 250 mm2. In conclusion, FLIP represents the first dynamic technique to profile the function and anatomy of the EGJ. The method can be used practically to evaluate difficult cases of EGJ dysfunction and may provide a role in evaluating patients before and after therapies for diseases affecting the EGJ such as achalasia and gastroesophageal reflux disease.

Adult↗

PubMed2006

Three-dimensional surface model analysis in the gastrointestinal tract.

The biomechanical changes during functional loading and unloading of the human gastrointestinal (GI) tract are not fully understood. GI function is usually studied by introducing probes in the GI lumen. Computer modeling offers a promising alternative approach in this regard, with the additional ability to predict regional stresses and strains in inaccessible locations. The tension and stress distributions in the GI tract are related to distensibility (tension-strain relationship) and smooth muscle tone. More knowledge on the tension and stress on the GI tract are needed to improve diagnosis of patients with gastrointestinal disorders. A modeling framework that can be used to integrate the physiological, anatomical and medical knowledge of the GI system has recently been developed. The 3-D anatomical model was constructed from digital images using ultrasonography, computer tomography (CT) or magnetic resonance imaging (MRI). Different mathematical algorithms were developed for surface analysis based on thin-walled structure and the finite element method was applied for the mucosa-folded three layered esophageal model analysis. The tools may be useful for studying the geometry and biomechanical properties of these organs in health and disease. These studies will serve to test the structure-function hypothesis of geometrically complex organs.

Algorithms↗

PubMed2005

Magnetic resonance imaging of the small bowel in Crohn's disease.

OBJECTIVE: There may be advantages in using magnetic resonance imaging (MRI) in small-bowel disease. The aims of this study were to optimize the MRI examination technique and to evaluate the capabilities of MRI compared with those of conventional enteroclysis (CE). MATERIALS AND METHODS: MRI and CE were performed in 36 patients suspected of Crohn's disease. Based on 26 pilot studies optimal oral administration of plum juice and bulk fibre laxative was found. T2-weighted and gadolinium enhanced T1-weighted images were obtained using a breath-holding technique and butylscopolamine. Virtual endoscopy was performed. Conventional enteroclysis entailed duodenal intubation and administration of barium and air. Two radiologists evaluated the examinations independently. Finally, each patient scored the degree of discomfort, and preference for either MRI or CE was found. RESULTS: The MRI technique ensured sufficient distension of the small bowel and small-bowel changes were found in 12 patients. In 3 patients this was not seen on conventional enteroclysis, which did not reveal any pathology that was not already seen on MRI. Pathological abdominal changes were found in 70% more patients during MRI than during conventional enteroclysis (p < 0.001). Endoscopic examination corresponded with the MRI findings. The examination quality decreased with increasing age (p = 0.002) and the interobserver agreement of the pathological changes was high (p < 0.001). Virtual endoscopy resulted in excellent demonstration of the mucosal surface. The examination discomfort scores obtained during the MRI were lower than those during conventional enteroclysis (p < 0.001). CONCLUSIONS: MRI using the current technique is preferable to conventional enteroclysis because of superior demonstration of the entire small-bowel pathology, low level of patient discomfort and absence of radiation exposure.

Administration, Oral↗