Normal small bowel wall characteristics on MR enterography

Cronin, Carmel G.; DeLappe, Eithne; Lohan, Derek G.; Roche, Clare; Murphy, Joseph

doi:10.1016/j.ejrad.2009.04.066

Cited by 77 publications

(47 citation statements)

References 15 publications

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“…Two concentric 8 cm high cylinders parallel to the applicator represented inner and outer surfaces of the duodenum, which was assumed to have an outer diameter of 25 mm (Fig. 3b) [49]. Duodenal wall thickness has been reported as 1.5–3 mm [49, 50], so a wall thickness of 3 mm was assumed to avoid underestimation of duodenal heating.…”

Section: Methodsmentioning

confidence: 99%

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Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas

et al. 2017

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BackgroundThe goal of this study was to theoretically investigate the feasibility of intraductal and transgastric approaches to ultrasound-based thermal therapy of pancreatic tumors, and to evaluate possible treatment strategies.MethodsThis study considered ultrasound applicators with 1.2 mm outer diameter tubular transducers, which are inserted into the tissue to be treated by an endoscopic approach, either via insertion through the gastric wall (transgastric) or within the pancreatic duct lumen (intraductal). 8 patient-specific, 3D, transient, biothermal and acoustic finite element models were generated to model hyperthermia (n = 2) and ablation (n = 6), using sectored (210°–270°, n = 4) and 360° (n = 4) transducers for treatment of 3.3–17.0 cm3 tumors in the head (n = 5), body (n = 2), and tail (n = 1) of the pancreas. A parametric study was performed to determine appropriate treatment parameters as a function of tissue attenuation, blood perfusion rates, and distance to sensitive anatomy.ResultsParametric studies indicated that pancreatic tumors up to 2.5 or 2.7 cm diameter can be ablated within 10 min with the transgastric and intraductal approaches, respectively. Patient-specific simulations demonstrated that 67.1–83.3% of the volumes of four sample 3.3–11.4 cm3 tumors could be ablated within 3–10 min using transgastric or intraductal approaches. 55.3–60.0% of the volume of a large 17.0 cm3 tumor could be ablated using multiple applicator positions within 20–30 min with either transgastric or intraductal approaches. 89.9–94.7% of the volume of two 4.4–11.4 cm3 tumors could be treated with intraductal hyperthermia. Sectored applicators are effective in directing acoustic output away from and preserving sensitive structures. When acoustic energy is directed towards sensitive structures, applicators should be placed at least 13.9–14.8 mm from major vessels like the aorta, 9.4–12.0 mm from other vessels, depending on the vessel size and flow rate, and 14 mm from the duodenum.ConclusionsThis study demonstrated the feasibility of generating shaped or conformal ablative or hyperthermic temperature distributions within pancreatic tumors using transgastric or intraductal ultrasound.

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Section: Methodsmentioning

confidence: 99%

“…3b) [49]. Duodenal wall thickness has been reported as 1.5–3 mm [49, 50], so a wall thickness of 3 mm was assumed to avoid underestimation of duodenal heating. The contents of the duodenum were modeled as water.…”

Section: Methodsmentioning

confidence: 99%

Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas

et al. 2017

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“…The dimensions of the tissue layers were estimated from several histology slides of intestinal tissue, where the relative thickness of each layer was determined [35]. Measurements of intestinal wall thickness from the literature [17] were then applied to these estimates to give the dimensions used for the simulation and the phantom.…”

Section: Monte Carlo Modelingmentioning

confidence: 99%

“…Many medical monitors use transmission mode through the finger, and for these or the reflection approaches with the larger sourcedetector separations the use of NIR wavelengths maximizes penetration depth to probe deeper microvasculature. However, in the case of the intestine, the intestinal wall is relatively thin (~2 mm) [17], and current sensors utilizing NIR light would probe through the wall of the intestine with measurements impacted by luminal contents or adjacent tissues. Such devices would also suffer from poor signal and high background when measuring intestinal perfusion and oxygenation.…”

Section: Introductionmentioning

confidence: 99%

In-silico and in-vitro investigation of a photonic monitor for intestinal perfusion and oxygenation

Robinson

Butcher

Wilson

et al. 2017

Biomed. Opt. Express

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Abstract:The quantification of visceral organ oxygenation after trauma-related systemic hypovolemia and shock is critical to enable effective resuscitation. In this work, a photoplethysmography-based (PPG) sensor was specifically designed for probing the perfusion and oxygenation condition of intestinal tissue with the ultimate goal to monitor patients post trauma to guide resuscitation. Through Monte Carlo modeling, suitable optofluidic phantoms were determined, the wavelength and separation distance for the sensor was optimized, and sensor performance for the quantification of tissue perfusion and oxygenation was tested on the in-vitro phantom. In particular, the Monte Carlo simulated both a standard block three-layer model and a more realistic model including villi. Measurements were collected on the designed three layer optofluidic phantom and the results taken with the small form factor PPG device showed a marked improvement when using shorter visible wavelengths over the more conventional longer visible wavelengths. Overall, in this work a Monte Carlo model was developed, an optofluidic phantom was built, and a small form factor PPG sensor was developed and characterized using the phantom for perfusion and oxygenation over the visible wavelength range. The results show promise that this small form factor PPG sensor could be used as a future guide to shock-related resuscitation.

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“…We performed an a priori sample size estimation (power, 0.80; a, 0.05) by using data from previous studies that examined bowel diameter and had used either sorbitol 5 or psyllium. 6 In order to detect a 20% difference in distension between the OCAs, while assuming a standard deviation of 3.5, we calculated that a sample size of 20 in each cohort would be sufficient.…”

Section: Study Populationmentioning

confidence: 99%

Comparison of 3% sorbitolvspsyllium fibre as oral contrast agents in MR enterography

Saini

Colak

Anthwal

et al. 2014

BJR

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Objective: To compare the degree of small bowel distension achieved by 3% sorbitol, a high osmolarity solution, and a psyllium-based bulk fibre as oral contrast agents (OCAs) in MR enterography (MRE). Methods: This retrospective study was approved by our institutional review board. A total of 45 consecutive normal MRE examinations (sorbitol, n 5 20; psyllium, n 5 25) were reviewed. The patients received either 1.5 l of 3% sorbitol or 2 l of 1.6 g kg 21 psyllium prior to imaging.Quantitative small bowel distension measurements were taken in five segments: proximal jejunum, distal jejunum, proximal ileum, distal ileum and terminal ileum by two independent radiologists. Distension in these five segments was also qualitatively graded from 0 (very poor) to 4 (excellent) by two additional independent radiologists. Statistical analysis comparing the groups and assessing agreement included intraclass coefficients, Student's t-test and Mann-Whitney U-test.Results: Small bowel distension was not significantly different in any of the five small bowel segments between the use of sorbitol and psyllium as OCAs in both the qualitative (p 5 0.338-0.908) and quantitative assessments (p 5 0.083-0.856). The mean bowel distension achieved was 20.1 6 2.2 mm for sorbitol and 19.8 6 2.5 mm for psyllium (p 5 0.722). Visualization of the ileum was good or excellent in 65% of the examinations in both groups. Conclusion: Sorbitol and psyllium are not significantly different at distending the small bowel and both may be used as OCAs for MRE studies. Advances in knowledge: This is the first study to directly compare the degree of distension in MRE between these two common, readily available and inexpensive OCAs.MR enterography (MRE) is an imaging technique used to evaluate the small bowel for diagnoses that include inflammatory bowel disease and neoplasms. Sufficiently distending the small bowel with an oral contrast agent (OCA) is critical, as collapsed loops may hide or mimic abnormalities.The OCAs employed in MRE can be classified as positive, negative or biphasic contrast agents according to their signal properties on T 1 and T 2 weighted imaging. Biphasic contrast agents typically provide low signal intensity on T 1 weighted imaging and high signal intensity on T 2 weighted imaging (T2W), and are most commonly used today because of their favourable signal characteristics for detecting bowel pathology. Water is a biphasic contrast agent, but its rapid physiological absorption from the small bowel necessitates the use of additives. These additives are often highly osmolar agents or non-osmotic agents that form hydrogels that trap water molecules in the bowel lumen. Combinations of highly osmolar agents and non-osmotic agents are also frequently used, as in the case of sorbitol and locust bean gum. 1,2Ideally, the chosen contrast agent should (i) provide adequate distension of the entire small bowel, (ii) provide uniform and homogenous opacification of the lumen, (iii) provide good delineation of the bowel wall, (iv) be below cost and eas...

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Normal small bowel wall characteristics on MR enterography

Cited by 77 publications

References 15 publications

Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas

Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas

In-silico and in-vitro investigation of a photonic monitor for intestinal perfusion and oxygenation

Comparison of 3% sorbitolvspsyllium fibre as oral contrast agents in MR enterography

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