What’s New in Gastrointestinal Imaging? – Januray 2023

2 weeks ago

The value of MSCT in evaluating the passability of bezoar by conservative treatment for bezoars-induced small bowel obstruction. Gao, W. Hua, Y. Meng, H. et al. Abdominal Radiology (2023) 48:236-243

Bezoar is an uncommonly encountered cause of small bowel obstruction. The most well known unique risk factor for bezoar formation is ingestion of hair, usually due to an underlying psychiatric disorder. There are other dietary risks such as ingestion of foods which contain high levels of tannic acid, pectin, and other compounds. These substances can compound the traditional risk factors of adhesions and motility disorders. Treatment of bezoar induced SBO is mainly conservative with surgery utilized when conservative treatment fails. The authors of this study examined the clinical and CT imaging data of patients with bezoar induced SBO to determine the characteristics of patients who were more likely to fail conservative treatment. Specific imaging factors that were analyzed included bezoar shape, density and dimensions, location within the small bowel, bowel dilation, intestinal wall thickness, and mesenteric stranding or fluid. Clinical findings included composition of recent dietary intake, length of symptoms, history of surgery, among others. Bezoar shape, density, intestinal wall thickness, mesenteric haziness and fluid were found to be statistically significant predictors of the ability to pass the bezoar with conservative treatment. Bezoar shape and degree of mesenteric haziness were found to be independent risk factors for prediction of bezoar passage. Clinical findings were found to not be a significant predictor of treatment success.

 

CT‑derived body composition measurements as predictors for neoadjuvant treatment tolerance and survival in gastroesophageal adenocarcinoma. DeFreitas, MR. Toronka, A. Nedrud, MA. et al. Abdominal Radiology (2023) 48:211-219

Gastric and esophageal malignancies result in significant morbidity and carry a poor prognosis with a 5 year survival rate of 32% and 20% respectively. Adenocarcinoma is the most common histologic subtype for both gastric and esophageal malignancies, and they share the same chemotherapy treatment. The authors of this study sought to use CT-derived body composition, patient and tumor features to supplement treatment strategy. Growing evidence shows that body composition can predict treatment tolerance and post treatment outcomes. The authors utilized a model that analyzed cross sectional areas of visceral fat, subcutaneous fat and skeletal muscle on a single CT slice at the L3 vertebral level. The model then derived metrics including a skeletal muscle to fat ratio, visceral fat to subcutaneous fat ratio and skeletal muscle to height ratio. The findings showed that patients with increased skeletal muscle was associated with better treatment tolerance, and higher BMI and higher skeletal muscle index were associated with increased survival. Increased visceral fat to subcutaneous fat was associated with higher frequency of unplanned admissions and ER encounters. These findings can help patients and medical teams assess functional status during treatment planning.

 

Routine postoperative CT to detect anastomotic leakage after low anterior resection for rectal cancer has a low sensitivity and specificity and a poor interobserver agreement. Lynglund, OM. Ellebaek, MB. et al. Clinical Radiology (2022) e719-e722.

Anastomotic leakage is a major complication to low anterior resection, and has been reported to occur in up to 20% of patients following resection. Leakage is most often diagnosed via CT, with false negatives having an increased mortality rate. The authors of this study examined the accuracy and interobserver variation of routine CT on postoperative days 6-8 in the detection of anastomotic leak. They also attempted to identify the predictive values of different CT findings as indicators for anastomotic leakage. The authors found that the sensitivity for detecting anastomotic leakage for  CT without rectal contrast for two reviewers was 71.4% and 50%, and specificity was 55.3% and 81.6%. For CT with rectal contrast the sensitivity was 57.1% and 35.7%, and specificity was 94.7% and 92.1%. For the observed predictors of leakage, peri-anastomotic free air showed the highest interobserver reliability, and peri-anastomotic free air and contrast medium leakage were the best predictors of anastomotic leakage. This study demonstrates the low sensitivity, specificity, and interobserver agreement in detection of anastomotic leakage by CT.

 

A pilot study on preoperative vascular anatomy and clinical application in rectal cancer resection. Wu, D. Bian, L. et al. Clinical Radiology 77 (2022) 701-707

Rectal cancer is one of the most prevalent cancers worldwide with surgical resection the mainstay of treatment. Prior to resection, CT angiography with image fusion is commonly performed to evaluate mesenteric vascular anatomy to aid in operative planning. Obesity has been identified as an important factor in interference with laparoscopic surgery due to impairing exposure of the surgical field. The authors conducted a prospective, randomized controlled trial to evaluate the utility of preoperative evaluation of vascular anatomy using CT angiography in obese patients undergoing laparoscopic resection for rectal cancer. Patients in the test group received CTA with image fusion, while the control group received CTA without image fusion. The authors found that compared with the control group the image fusion group had shorter duration of surgery, lower bleeding volume, and a greater number of lymph node dissections. No significant difference in length of hospitalization, return of bowel function, conversion to laparotomy, or perioperative complications were seen between the two groups.

 

Extramural venous invasion and depth of extramural invasion on preoperative CT as prognostic imaging biomarkers in patients with locally advanced ascending colon cancer. Cho, J. Kim, YH. et al. Abdominal Radiology (47) 3679-3687

Determination of extramural tumor invasion depth (DEMI) and extramural venous invasion (EMVI) in colon cancer is an important factor in treatment planning, but the prognostic implications of these findings are unclear. This retrospective study assessed the preoperative CT scans for patients with T3 ascending colon cancer for EMVI, DEMI, nodal status, age, and sex for the presence of metastasis on preoperative CT and compared disease-free survival for the same variables. The authors found that positive EMVI was significantly associated with metastasis on preoperative CT. Positive EMVI was also associated with worse disease free survival. The authors also found good interobserver agreement between the participating radiologists for determining EMVI and DEMI. Establishing these CT findings as imaging markers for risk stratification provides an important tool for prognostic planning.

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