Keywords
1. Mesenteric Ischemia MRI
2. Small Bowel Obstruction Imaging
3. Non-contrast MRI Diagnosis
4. Experimental Mesenteric Venous Occlusion
5. MRI Strangulated Obstruction Research
Introduction: Mesenteric ischemia, a potentially life-threatening condition, is commonly caused by strangulated small bowel obstruction (SBO) and mesenteric venous occlusion (MVO). Accurate diagnosis is critical for timely intervention and improved patient outcomes. A pioneering experimental study using rabbits has opened new frontiers in the evaluation of mesenteric ischemia employing magnetic resonance imaging (MRI). This article delves into this groundbreaking research, providing insights into non-contrast MRI’s effectiveness in diagnosing mesenteric ischemia caused by SBO and MVO.
Research Outline: In an article published in “Magnetic Resonance in Medical Sciences,” a team led by Akitoshi Inoue from the Department of Radiology at the Shiga University of Medical Science, Japan presented their findings on MR imaging-based evaluations of mesenteric ischemia. They generated strangulated SBO and MVO models in rabbits, using 3T MRI to assess the condition. This innovative approach to visualizing ischemia offers potential for early detection without the need for contrast agents, which can cause complications such as anaphylactoid reactions (Davis PL. AJR Am J Roentgenol 2015; 204:1140–1145, DOI: 10.2463/mrms.mp.2019-0010).
Experimental Study and Results: Twenty rabbits underwent surgical procedures to create models of strangulated SBO and MVO. Nine rabbits were allocated to the study group, while two underwent sham surgery to serve as controls. Angiographic, macroscopic, and microscopic findings confirmed the successful creation of the models. MRI was performed pre- and post-procedure to identify changes in the mesenteric structures.
The MRI findings were enlightening. After mesenteric ischemia induction, the ischemic bowel wall appeared thicker, particularly in the MVO model, with an average thickness of 3.17 ± 0.55 mm compared to 2.26 ± 0.46 mm in the strangulated SBO model. Signal intensity and signal intensity ratio (SI ratio) of the bowel wall significantly increased after the procedure across all sequences and models, indicating potential biomarkers for ischemia. Notably, the mesentery adjacent to the ischemic bowel loop exhibited high signal intensity in all animals on fat-suppressed T2-weighted images (FS-T2).
Significance: This study’s significance lies in its potential application in clinical settings. Mesenteric ischemia’s early detection is crucial for reducing the risk of bowel necrosis and potential fatality. Traditional diagnostic methods, such as multidetector CT (MDCT), though effective, involve radiation exposure and contrast media, which have associated risks, particularly in patients with renal insufficiency or contrast allergies (Kanasaki S et al., Radiographics 2018; 38:945–961).
The use of non-contrast MRI, as demonstrated by this study, could mitigate these risks. MRI also has the advantage of being safe during pregnancy, compared to CT, and thus could be invaluable for evaluating pregnant patients with acute abdominal conditions (Ray JG et al., JAMA 2016; 316:952–961).
Implications for Future Research: The study by Inoue et al. suggests a new avenue for diagnosing strangulated SBO and MVO without the use of invasive techniques or iodinated contrast media. Their findings align with the growing body of evidence supporting MRI’s utility in evaluating acute abdominal conditions, such as acute appendicitis, where non-contrast MRI has shown diagnostic accuracy (Repplinger MD et al., Radiology 2018; 288:467–475).
Further studies could investigate the application of this MRI approach in larger cohorts and compare its efficacy with that of traditional techniques. Additionally, researchers could explore the potential of advanced MRI sequences, such as diffusion-weighted imaging (DWI), in identifying small bowel strangulation (Takahara T et al., Jpn J Radiol 2011; 29:11–18).
Conclusion: The study by Inoue et al. provides compelling evidence that non-contrast MRI is a viable and potentially superior tool for evaluating mesenteric ischemia caused by strangulated SBO and MVO. As MRI technology continues to advance, its role in abdominal imaging is likely to expand, offering safer and more accurate diagnostics for patients with acute abdominal conditions.
References
1. Inoue A, et al. MR Imaging-based Evaluation of Mesenteric Ischemia Caused by Strangulated Small Bowel Obstruction and Mesenteric Venous Occlusion: An Experimental Study Using Rabbits. Magn Reson Med Sci. 2020;19(2):125-134. DOI: 10.2463/mrms.mp.2019-0010.
2. Wadman M, et al. Survival after operations for ischaemic bowel disease. Eur J Surg. 2000;166:872-877. DOI: 10.1080/110241500750007501.
3. Kanasaki S, et al. Acute mesenteric ischemia: multidetector CT findings and endovascular management. Radiographics. 2018;38(4):945-961. DOI: 10.1148/rg.2018170162.
4. Ray JG, et al. Association between MRI exposure during pregnancy and fetal and childhood outcomes. JAMA. 2016;316(9):952-961. DOI: 10.1001/jama.2016.12126.
5. Repplinger MD, et al. Prospective comparison of the diagnostic accuracy of MR imaging versus CT for acute appendicitis. Radiology. 2018;288(2):467-475. DOI: 10.1148/radiol.2018171505.