Contrast media for fluoroscopic examinations of the GI and GU tracts: current challenges and recommendations

Clinical issues and challenges in imaging of gastrointestinal diseases: A minireview and our experience

Imaging techniques play a crucial role in the modern era of medicine, particularly in gastroenterology. Nowadays, various non-invasive and invasive imaging modalities are being routinely employed to evaluate different gastrointestinal (GI) diseases. However, many instrumental as well as clinical issues are arising in the area of modern GI imaging. This minireview article aims to briefly overview the clinical issues and challenges encountered in imaging GI diseases while highlighting our experience in the field. We also summarize the advances in clinically available diagnostic methods for evaluating different diseases of the GI tract and demonstrate our experience in the area. In conclusion, almost all imaging techniques used in imaging GI diseases can also raise many challenges that necessitate careful consideration and profound expertise in this field.

Diagnostic reliability and accuracy of the hydraulic contrast lift protocol in the radiographic detection of sinus lift and perforation: ex vivo randomized split-mouth study in an ovine model

OBJECTIVES

Assessing the diagnostic reliability, validity, and accuracy of the hydraulic contrast lift protocol during transcrestal sinus floor elevation in detecting the lift and perforation of the sinus membrane before graft material application and assessing the effect of its use on the operator's diagnostic confidence.

MATERIAL AND METHODS

A single-blind randomized split-mouth study on fresh refrigerated sheep heads. The first intervention consisted of injecting 0.5 ml iodinated contrast medium on the test side and 0.5 ml saline on the control side. In the second intervention artificial sinus membrane perforations were created followed by injecting 0.5 ml iodinated contrast medium on the test side and 0.5 ml saline on the control side. Intraoperative periapical radiographs were taken for both interventions. The resulting 40 radiographs were assessed by 10 examiners to provide interpretations and confidence ratings. The primary endpoints were diagnostic reliability, validity, accuracy, and perceived diagnostic confidence.

RESULTS

In the hydraulic contrast lift protocol, the detection rate was 99% for sinus elevations and 98% for perforations, the saline protocol yielded a detection rate of 28% and 20% respectively. The hydraulic contrast lift protocol demonstrated a high level of inter-rater agreement for the diagnosis of elevations (p < 0.001) and perforations (p < 0.001), strong diagnostic validity for the diagnosis of elevations (p < 0.001) and perforations (p < 0.001), high sensitivity and specificity (p < 0.001) and higher mean diagnostic confidence ratings for both interventions when compared to the saline protocol (p < 0.001). The difference between the predicted probability for correct diagnosis of the hydraulic contrast lift protocol and the saline protocol was significant (p < 0.001) for the detection of both elevations and perforations.

CONCLUSION

Following the hydraulic contrast lift protocol, the use of a radiographic contrast medium can reliably confirm sinus membrane lift and detect perforation during transcrestal sinus floor elevation prior to bone graft application in addition to improving the diagnostic confidence of the operator while relying on periapical radiographs.

Water soluble swallow for leak detection after total laryngectomy post radiotherapy

AIM

Pharyngeal leak (PL) and pharyngocutaneous fistula (PCF) are serious complications following total laryngectomy and their incidence is higher in the salvage setting. The aim of this study is to describe the accuracy of water soluble swallow (WSS) to rule out salivary postoperative leak after salvage total laryngectomy (STL) to expedite start of oral intake.

MATERIAL AND METHODS

Retrospective study including patients undergoing STL between 2008 and 2021 at Guy's Hospital. WSS was routinely performed within 15 days post operation.

RESULTS

Sixty-six patients underwent STL. Nine developed clinically diagnosed PCF; one died before having WSS. Fifty-six patients underwent WSS post STL. WSS was performed within 15 days after STL when no postoperative complications occurred (76.8%). Among patients undergoing WSS with no clinical suspicion for fistula (56), PL was identified in 15 cases (26.8%). They were managed conservatively; PCF was avoided in 7(46.7%) cases. Three patients (7.3%) developed PCF after having started oral intake with a negative WSS. These three cases were further analysed, 2 cases where recorded at the beginning of the studied period when less experience was available possibly leading to incorrect results. Sensitivity and negative predictive value (NPV) for fistula prediction were 72.7% and 92.7%, respectively.

CONCLUSION

Taking into account the high NPV of WSS, it is safe to start oral intake after negative WSS. Further studies to evaluate its accuracy earlier on after SLT are justified taking into account the results and the impact that delayed feeding has on patient's quality of life.

Human Gut Microbiota-associated Gastrointestinal Malignancies: A Comprehensive Review

The human gastrointestinal tract houses trillions of microbes. The gut and various types of microorganisms, including bacteria, viruses, fungi, and archaea, form a complex ecosystem known as the gut microbiota, and the whole genome of the gut microbiota is referred to as the gut microbiome. The gut microbiota is essential for homeostasis and the overall well-being of a person and is increasingly considered an adjunct "virtual organ," with a complexity level comparable to that of the other organ systems. The gut microbiota plays an essential role in nutrition, local mucosal homeostasis, inflammation, and the mucosal immune system. An imbalanced state of the gut microbiota, known as dysbiosis, can predispose to development of various gastrointestinal malignancies through three speculated pathogenic mechanisms: (a) direct cytotoxic effects with damage to the host DNA, (b) disproportionate proinflammatory signaling inducing inflammation, and (c) activation of tumorigenic pathways or suppression of tumor-suppressing pathways. Several microorganisms, including Helicobacter pylori, Epstein-Barr virus, human papillomavirus, Mycoplasma species, Escherichia coli, and Streptococcus bovis, are associated with gastrointestinal malignancies such as esophageal adenocarcinoma, gastric adenocarcinoma, gastric mucosa-associated lymphoid tissue lymphoma, colorectal adenocarcinoma, and anal squamous cell carcinoma. Imaging plays a pivotal role in diagnosis and management of microbiota-associated gastrointestinal malignancies. Appropriate use of probiotics, fecal microbiota transplantation, and overall promotion of the healthy gut are ongoing areas of research for prevention and treatment of malignancies. Online supplemental material is available for this article. ^©RSNA, 2021.

Early postoperative imaging after non-bariatric gastric resection: a primer for radiologists

Abstract

Surgical resection represents the mainstay treatment and only potentially curative option for gastric carcinoma, and is increasingly performed laparoscopically. Furthermore, other tumours and selected cases of non-malignant disorders of the stomach may require partial or total gastrectomy. Often performed in elderly patients, gastric resection remains a challenging procedure, with significant morbidity (14–43% complication rate) and non-negligible postoperative mortality (approximately 3%). This paper provides an overview of contemporary surgical techniques for non-bariatric gastric resection, reviews and illustrates the expected postoperative imaging appearances, common and unusual complications after partial and total gastrectomy. Albeit cumbersome or unfeasible in severely ill or uncooperative patients, contrast fluoroscopy remains useful to rapidly check for anastomotic patency and integrity. Currently, emphasis is placed on multidetector CT, which comprehensively visualizes the surgically altered anatomy and consistently detects complications such as anastomotic leaks and fistulas, duodenal stump leakage, afferent loop syndrome, haemorrhages, pancreatic fistulas and porto-mesenteric venous thrombosis. Our aim is to help radiologists become familiar with early postoperative imaging, in order to understand the surgically altered anatomy and to differentiate between expected imaging appearances and abnormal changes heralding iatrogenic complications, thus providing a consistent basis for correct choice between conservative, interventional or surgical treatment.

Teaching points

• Radical gastrectomy is associated with frequent postoperative morbidity and non-negligible mortality.

• In cooperative patients fluoroscopy allows checking for anastomotic patency and leaks.

• Multidetector CT with / without oral contrast comprehensively visualizes the operated abdomen.

• Awareness of surgically altered anatomy and expected postoperative appearances is warranted.

• Main complications include anastomotic and duodenal leaks, haemorrhages and pancreatic fistulas.