Use of positive oral contrast agents in abdominopelvic computed tomography for blunt abdominal injury: meta-analysis and systematic review

Enteral Contrast Administration in Abdominal Computed Tomography: Status Quo in Germany

In an online survey conducted by the Gastrointestinal and Abdominal Imaging Working Group of the German Radiological Society (DRG), the current state regarding enteral contrast administration in computed tomography (CT) of the abdomen in Germany was established and critically evaluated. The results of the survey are intended to serve as a basis for expert recommendations on enteral contrast administration in abdominal CT.DRG members were invited to take part in the online survey by email, newsletter, and via the DRG online portal. The survey was available for 70 days. It comprised 61 questions on enteral contrast administration in various clinical scenarios, with an average operation approximately 10 to 15 minutes. The results were analyzed using descriptive statistical methods.1,001 radiologists completed the survey. Of the participants, 67% worked in a hospital and 33% in private practice or a medical care center. Furthermore, 52% of the participants were senior physicians or board-certified radiologists. Enteral contrast administration is being performed selectively for various indications, but with considerable differences in technique and regularity. A lack of substantial diagnostic gain, as well as time-related or organizational factors, were the main reasons cited against enteral contrast administration.The results of the survey demonstrate a heterogeneous, selective, and indication-specific implementation of enteral contrast administration. There are considerable differences regarding technical implementation and realization. There is a strong desire for generally applicable recommendations along with their integration in respective SOPs. · Enteral contrast administration in abdominal CT is being performed very heterogeneously.. · Guidelines lack specifications regarding enteral contrast administration.. · There is a strong desire for recommendations and their implementation in relevant SOPs.. · Stadelmann J, Grenacher L, Juchems MS et al. Enteral Contrast Administration in Abdominal Computed Tomography: Status Quo in Germany. Rofo 2025; DOI 10.1055/a-2594-7579.

An Unusual Presentation of a Small Bowel Injury in an Adult Following a Fall From Height

Blunt trauma to the abdomen (BTA) poses a challenge to surgeons in diagnosing the exact intra-abdominal injuries, including hollow viscus injuries. This case report discusses a 40-year-old male patient, a case of BTA following a fall from a height, who did not present any features of peritonitis. Upon evaluation, the patient was found to have a small bowel obstruction in the distal jejunum. The patient was taken for exploratory laparotomy, and the inflammatory mass was removed. A side-to-side distal jejunal anastomosis was performed. This case report teaches us that not all small bowel injuries present as perforation peritonitis; they can also manifest as intestinal obstruction. Delays in diagnosis and treatment can lead to increased morbidity and complications.

Positive Versus Neutral Oral Contrast Material for Detection of Malignant Deposits in Intraabdominal Nonsolid Organs on CT

BACKGROUND. Data are limited regarding utility of positive oral contrast material for peritoneal tumor detection on CT. OBJECTIVE. The purpose of this article is to compare positive versus neutral oral contrast material for detection of malignant deposits in nonsolid intraabdominal organs on CT. METHODS. This retrospective study included 265 patients (133 men, 132 women; median age, 61 years) who underwent an abdominopelvic CT examination in which the report did not suggest presence of malignant deposits and a subsequent CT examination within 6 months in which the report indicated at least one unequivocal malignant deposit. Examinations used positive (iohexol; n = 100) or neutral (water; n = 165) oral agents. A radiologist reviewed images to assess whether the deposits were visible (despite clinical reports indicating no deposits) on unblinded comparison with the follow-up examinations; identified deposits were assigned to one of seven intraabdominal compartments. The radiologist also assessed adequacy of bowel filling with oral contrast material. Two additional radiologists independently reviewed examinations in blinded fashion for malignant deposits. NPV was assessed of clinical CT reports and blinded retrospective readings for detection of malignant deposits visible on unblinded comparison with follow-up examinations. RESULTS. Unblinded review identified malignant deposits in 58.1% (154/265) of examinations. In per-patient analysis of clinical reports, NPV for malignant deposits was higher for examinations with adequate bowel filling with positive oral contrast material (65.8% [25/38]) than for examinations with inadequate bowel filling with positive oral contrast material (45.2% [28/62], p = .07) or with neutral oral contrast material regardless of bowel filling adequacy (35.2% [58/165], p = .002). In per-compartment analysis of blinded interpretations, NPV was higher for examinations with adequate and inadequate bowel filling with positive oral contrast material than for examinations with neutral oral contrast regardless of bowel filling adequacy (reader 1: 94.7% [234/247] and 92.5% [382/413] vs 88.3% [947/1072], both p = .045; reader 2: 93.1% [228/245] and 91.6% [361/394] vs 85.9% [939/1093], both p = .01). CONCLUSION. CT has suboptimal NPV for malignant deposits in intraabdominal nonsolid organs. Compared with neutral material, positive oral contrast material improves detection, particularly with adequate bowel filling. CLINICAL IMPACT. Optimization of bowel preparation for oncologic CT may help avoid potentially severe clinical consequences of missed malignant deposits.

Positive oral contrast material for CT evaluation of non-traumatic abdominal pain in the ED: prospective assessment of diagnostic confidence and throughput metrics

OBJECTIVE

Evaluate the impact of positive oral contrast material (POCM) for non-traumatic abdominal pain on diagnostic confidence, diagnostic rate, and ED throughput.

MATERIALS AND METHODS

ED oral contrast guidelines were changed to limit use of POCM. A total of 2,690 abdominopelvic CT exams performed for non-traumatic abdominal pain were prospectively evaluated for diagnostic confidence (5-point scale at 20% increments; 5 = 80-100% confidence) during a 24-month period. Impact on ED metrics including time from CT order to exam, preliminary read, ED length of stay (LOS), and repeat CT scan within 7 days was assessed. A subset of cases (n = 729) was evaluated for diagnostic rate. Data were collected at 2 time points, 6 and 24 months following the change.

RESULTS

A total of 38 reviewers were participated (28 trainees, 10 staff). 1238 exams (46%) were done with POCM, 1452 (54%) were performed without POCM. For examinations with POCM, 80% of exams received a diagnostic confidence score of 5 (mean, 4.78 ± 0.43; 99% ≥ 4), whereas 60% of exams without POCM received a score of 5 (mean, 4.51 ± 0.70; 92% ≥ 4; p < .001). Trainees scored 1,523 exams (57%, 722 + POCM, 801 -POCM) and showed even lower diagnostic confidence in cases without PCOM compared with faculty (mean, 4.43 ± 0.68 vs. 4.59 ± 0.71; p < 0.001). Diagnostic rate in a randomly selected subset of exams (n = 729) was 54.2% in the POCM group versus 56.1% without POCM (p < 0.655). CT order to exam time decreased by 31 min, order to preliminary read decreased by 33 min, and ED LOS decreased by 30 min (approximately 8% of total LOS) in the group without POCM compared to those with POCM (p < 0.001 for all). 205 patients had a repeat scan within 7 days, 74 (36%) had IV contrast only, 131 (64%) had both IV and oral contrast on initial exam. Findings were consistent both over a 6-month evaluation period as well as the full 24-month study period.

CONCLUSION

Limiting use of POCM in the ED for non-traumatic abdominal pain improved ED throughput but impaired diagnostic confidence, particularly in trainees; however, it did not significantly impact diagnostic rates nor proportion of repeat CT exams.

Diagnostic accuracy of positive oral contrast in abdominal computed tomography for non-traumatic pathologies: a systematic review protocol

OBJECTIVE

The objective of this review is to determine the diagnostic accuracy of positive oral contrast versus no oral contrast for common, non-traumatic computed tomography abdominal indications in adults.

INTRODUCTION

Positive oral contrast is regularly administered to patients to drink prior to computed tomography scans of the abdomen and pelvis. The purpose of the preparation is to improve visualization of the bowel, however, technological advances in scanner design may mean positive oral contrast is no longer required.

INCLUSION CRITERIA

Eligible studies will consider the use of positive oral contrast in non-traumatic indications for computed tomography of the abdomen and pelvis to include appendicitis, bowel obstruction, diverticulitis, intestinal neoplasms and metastasis (screening or staging), or acute abdomen. The review will use the discharge diagnosis as the reference standard. Studies that describe adult patients (18+) and published from 2000 on will be considered.

METHODS

MEDLINE Complete, Embase, CINAHL, and Scopus will be searched, along with Google Scholar and numerous radiology college websites. Screening of potential titles and abstracts, retrieval of full-text studies, assessment of methodological quality, and data extraction will be performed independently by two reviewers. Meta-analyses will be performed, if possible, and a Grading of Recommendations, Assessment, Development and Evaluation Summary of Findings presented.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO (CRD42020184285).

CT Enterography Using Four Different Endoluminal Contrast Agents: A Comparative Study

Objectives To determine the most preferable endoluminal contrast agent among mannitol, polyethylene glycol (PEG), iohexol, and water by comparing various qualitative (distension, fold visibility, and homogeneity) and quantitative parameters (distension) along with artifacts and patient feedback for computed tomography enterography (CTE).

Methods This was a prospective study including 120 patients of age more than or equal to 18 years who were randomized equally into four groups. Group 1 was given 1500 mL of 3% mannitol solution, group 2 was given 1500 mL of PEG, group 3 was given 20 mL of iohexol dissolved in 1500 mL of water, and group 4 was given 1500 mL of plain water. CTE was done and images were evaluated in axial and coronal planes. Various quantitative and qualitative parameters were taken at the level of second part of duodenum, jejunum, ileum and ileocecal junction (ICJ). Artifacts and patient feedback were also taken into consideration.

Results The quantitative distension and grading, qualitative distension, fold visibility, and homogeneity of the second part of duodenum, jejunum at the level of superior mesenteric artery, inferior mesenteric artery and renal artery on both sides of abdomen, ileum at the level of aortic bifurcation, common iliac bifurcation, and deep pelvis on both sides of abdomen and ICJ were significantly more in PEG group as compared with mannitol group, followed by iohexol and water group. The results were calculated by ANOVA test using p-value. In terms of patient feedback and artifacts, water was the best agent.

Conclusions PEG is the most suitable contrast agent to carry out CTE. Distension, fold visibility, and homogeneity are the essential features for a better diagnostic outcome of CTE, which was better with PEG.

Utility of enteric contrast material in abdominal penetrating trauma: A narrative review

Penetrating trauma is an important cause of morbidity and mortality. With the possibility of conservative management for hemodynamically stable trauma patient, computed tomography (CT) has become an important tool in diagnosis and management of penetrating trauma. There have been multiple studies examining the utility and lack of perceived benefit of using enteric contrast material in the initial CT evaluation. We provide a narrative review of the surgical and radiological literature, offer our own protocol for how to approach the imaging of patients with suspected bowel injury following penetrating traumatic injury and discuss the potential of using enteric contrast material.

Use of Enteric Contrast Material for Abdominopelvic CT in Penetrating Traumatic Injury in Adults: Comparison of Diagnostic Accuracy Systematic Review and Meta-Analysis

BACKGROUND. Scarce evidence exists on the diagnostic benefit of enteric contrast administration for abdominopelvic CT performed in the setting of penetrating trauma. OBJECTIVE. The purpose of this systematic review and meta-analysis is to compare the diagnostic accuracy of CT using enteric contrast material with that of CT not using enteric contrast material in penetrating traumatic abdominopelvic injury in adults. EVIDENCE ACQUISITION. A protocol was registered a priori (PROSPERO CRD42019139613). MEDLINE and EMBASE databases were searched until June 25, 2019. Studies were included that evaluated the diagnostic accuracy of abdominopelvic CT either with or without enteric (oral and/or rectal) contrast material in patients presenting with penetrating traumatic injury. Relevant study data metrics and risk of bias were assessed. Bivariate random-effects meta-analyses and meta-regression modeling were performed to assess and compare diagnostic accuracies. EVIDENCE SYNTHESIS. From an initial sample of 829 studies, 12 studies were included that reported on 1287 patients with penetrating injury (389 with confirmed bowel, mesenteric, or other abdominopelvic organ injury). The enteric contrast material group (seven studies; 506 patients; 124 patients with confirmed penetrating injury) showed a sensitivity of 83.8% (95% CI, 73.7-90.5%) and specificity of 93.8% (95% CI, 83.6-97.8%). The group without enteric contrast administration (six studies; 781 patients; 265 patients with confirmed penetrating injury) showed a sensitivity of 93.0% (95% CI, 86.8-96.4%) and a specificity of 90.3% (95% CI, 81.4-95.2%). No statistically significant difference was identified for sensitivity (p = .07) or specificity (p = .37) between the groups with and without enteric contrast material according to meta-regression. Nine of 12 studies showed risk of bias in at least one QUADAS-2 domain (most frequently limited reporting of blinding of radiologists or lack of blinding of radiologists, insufficient clinical follow-up for the reference standard, and limited reporting of sampling methods). CONCLUSION. The use of enteric contrast material for CT does not provide a significant diagnostic benefit for penetrating traumatic injury. CLINICAL IMPACT. Eliminating enteric contrast administration for CT in penetrating traumatic injury can prevent delays in imaging and surgery and reduce cost.

ACR Appropriateness Criteria® Major Blunt Trauma

This review assesses the appropriateness of various imaging studies for adult major blunt trauma or polytrauma in the acute setting. Trauma is the leading cause of mortality for people in the United States <45 years of age, and the fourth leading cause of death overall. Imaging, in particular CT, plays a critical role in the management of these patients, and a number of indications are discussed in this publication, including patients who are hemodynamically stable or unstable; patients with additional injuries to the face, extremities, chest, bowel, or urinary system; and pregnant patients. Excluded from consideration in this review are penetrating traumatic injuries, burns, and injuries to pediatric patients. Patients with suspected injury to the head and spine are also discussed more specifically in other appropriateness criteria documents. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Emergent Comprehensive Imaging of the Major Trauma Patient: A New Paradigm for Improved Clinical Decision-Making

Modern advances in the medical imaging layered onto sophisticated trauma resuscitation strategies in highly organized regionalized trauma systems have created a paradigm shift in the management of severely injured patients. Although immediate exploratory surgery to identify and control life-threatening injuries still has its place, accelerated image acquisition and interpretation procedures now make it rare for trauma surgeons in major centers to venture into damage control surgery unaided by computed tomography (CT) or other imaging, particularly in cases of blunt trauma. Indeed, because of the high incidence of clinically occult injuries associated with major mechanism trauma, and even lower energy trauma in frail or elderly patients, CT imaging has become as invaluable as physical examination, if not more so, in critical decision-making in support of optimal outcomes. In particular, whole-body computed tomography (WBCT) completed promptly after initial assessment of a major trauma provides a quick, comprehensive survey of injuries that enables better surgical planning, obviates the need for multiple subsequent studies, and permits specialized reconstructions when needed. For those at risk for problematic occult injury after modest trauma, WBCT facilitates safer discharge planning and simplified follow-up. Through standardized guidelines, streamlined protocols, synoptic reporting, accessible web-based platforms, and active collaboration with clinicians, radiologists dedicated to trauma and emergency imaging enable clearer understanding of complex injuries in high-risk patients which leads to superior clinical decision-making. Whereas dated dogma has long warned that the CT scanner is the last place to take a challenging trauma patient, modern practice suggests that, more often than not, early comprehensive imaging can be done safely and efficiently and is in the patient's best interest. This article outlines how the role of diagnostic imaging for major trauma has evolved considerably in recent years.

Imaging of blunt bowel and mesenteric injuries: Current status

Blunt abdominal trauma often presents a diagnostic challenge. Clinical examination demonstrates low reliability in detecting abdominal injury (16 %) when there is a history of head injury or loss of consciousness. This can prove detrimental, as delays in the diagnosis of traumatic bowel injury of 8 h or less can result in increased morbidity and mortality, as well as prolonged hospitalization. Although hemodynamically unstable patients will require an urgent laparotomy following clinical assessment, MDCT is the modality of choice for comprehensive imaging of blunt abdominal trauma in hemodynamically stable patients. Despite the use of MDCT, blunt injury to the bowel and mesentery, which accounts for up to 5% of injuries in cases of trauma, may be difficult to detect. The use of a constellation of direct and indirect signs on MDCT can help make the diagnosis and guide clinical management. Direct signs on MDCT, such as bowel wall discontinuity, and extraluminal gas may assist in the diagnosis of traumatic bowel injury. However, these signs are not sensitive. Therefore, the astute radiologist may have to rely on indirect signs of injury, such as free fluid, bowel wall thickening, and abnormal bowel wall enhancement to make the diagnosis. This review will focus on MDCT imaging findings of bowel and mesenteric injuries secondary to blunt abdominal trauma.

Positive Oral Contrast Material for Abdominal CT: Current Clinical Indications and Areas of Controversy

OBJECTIVE. The use of positive oral contrast material for abdominal CT is a frequent protocol issue. Confusion abounds regarding its use, and practice patterns often appear arbitrary. Turning to the existing literature for answers is unrewarding, because most studies are underpowered or not designed to address key endpoints. Even worse, many decisions are now being driven by nonradiologists for throughput gains rather than patient-specific considerations. Herein, the current indications for positive oral contrast material are discussed, including areas of controversy. CONCLUSION. As radiologists, we owe it to our patients to drive the appropriate use of positive oral contrast material. At the very least, we should not allow nonradiologists to restrict its use solely on the basis of throughput concerns; rather, we should allow considerations of image quality and diagnostic confidence to enter into the decision process. Based on differences in prior training and practice patterns, some radiologists will prefer to limit the use of positive oral contrast material more than others. However, for those who believe (as I do) that it can genuinely increase diagnostic confidence and can sometimes (rather unpredictably) make a major impact on diagnosis, it behooves us to keep fighting for its use.

Duodeno-pancreatic and extrahepatic biliary tree trauma: WSES-AAST guidelines

Duodeno-pancreatic and extrahepatic biliary tree injuries are rare in both adult and pediatric trauma patients, and due to their anatomical location, associated injuries are very common. Mortality is primarily related to associated injuries, but morbidity remains high even in isolated injuries. Optimal management of duodeno-bilio-pancreatic injuries is dictated primarily by hemodynamic stability, clinical presentation, and grade of injury. Endoscopic and percutaneous interventions have increased the ability to non-operatively manage these injuries. Late diagnosis and treatment are both associated to increased morbidity and mortality. Sequelae of late presentations of pancreatic injury and complications of severe pancreatic trauma are also increasingly addressed endoscopically and with interventional radiology procedures. However, for moderate and severe extrahepatic biliary and severe duodeno-pancreatic injuries, immediate operative intervention is preferred as associated injuries are frequent and commonly present with hemodynamic instability or peritonitis. The aim of this paper is to present the World Society of Emergency Surgery (WSES) and American Association for the Surgery of Trauma (AAST) duodenal, pancreatic, and extrahepatic biliary tree trauma management guidelines.

Comparison of Positive Oral Contrast Agents for Abdominopelvic CT

OBJECTIVE. The objective of our study was to compare the quality of bowel opacification from three different positive oral contrast agents-barium sulfate, diatrizoate, and iohexol-at abdominopelvic CT. MATERIALS AND METHODS. Abdominopelvic CT examinations with three different oral contrast agents (each contrast agent: n = 300 patients) of 900 patients were retrospectively evaluated by two independent readers. For four segments of the gastrointestinal tract (i.e., the stomach, jejunum, ileum, and colon), readers recorded qualitative data (grade of nonuniform lumen opacification, types of inhomogeneous opacifications, presence of artifacts, and distribution of contrast agent) and quantitative data (CT attenuation of lumen [in Hounsfield units]). The results were compared among the three contrast agents using the Mann-Whitney U test and repeated-measures ANOVA with a post hoc Bonferroni correction. RESULTS. Fewer artifacts were detected with iohexol (4.3%) as the oral contrast agent than with diatrizoate (13.0%) and barium sulfate (14.3%) (each, p < 0.05). Barium showed a greater frequency of bowel lumen heterogeneity (388/831 segments, 47%) than iohexol (155/679, 23%) and diatrizoate (185/763, 24% segments) (p < 0.001). Barium showed higher CT attenuation than iohexol and diatrizoate in the stomach but lower CT attenuation in the ileum (each, p < 0.05). CONCLUSION. The frequency of inhomogeneous bowel opacification was lower for iohexol than for diatrizoate or barium sulfate. Barium showed the highest frequency of bowel lumen heterogeneity. The iodinated agents showed greater increases in mean CT attenuation from the proximal bowel segments to the distal bowel segments than barium sulfate.

Radiologic assessment of gastric emptying of water-soluble contrast media: New data security from a longitudinal study

BACKGROUND AND OBJECTIVES

Practice guidelines for preoperative fasting have not clearly established the fasting time needed after oral administration of water-soluble contrast media. The aim of this study was to determine the time required for the gastric emptying during the water-soluble contrast media in patients with acute abdominal pain.

METHODS

This prospective longitudinal study included sixty-eight patients older than 18 years of age with acute abdominal pain, who required a water-soluble contrast media enhanced abdominal computed tomography study. Plain radiographs were obtained hourly until complete the gastric emptying. Patients with probable bowel obstruction were not included in the study.

RESULTS

A total of 31 (45,6%), 54 (79,4%), and 64 (94,1%) patients achieved a complete gastric clearance of barium in 1, 2 and 3 hours, respectively. All patients achieved complete emptying of water-soluble contrast media within 6 hours. Gastric emptying time was not associated with gender (P=0,44), body mass index (P=.35), fasting time prior to water-soluble contrast media intake (P=0,12), administration of opioids in the emergency room (P=0,7), and the presence of comorbidities (P=0,36).

CONCLUSION

Ninety-four percent of the patients with acute abdominal pain achieved complete gastric emptying within 3hours after the administration of water-soluble contrast media. All of them achieved complete gastric emptying within 6hours. The results suggested 6hours after oral intake of the contrast media is enough to complete transit of water-soluble contrast media through the stomach and avoid unnecessary risks.

An international survey to assess use of oral and rectal contrast in CT protocols for penetrating torso trauma

PURPOSE

There is controversy regarding the administration of oral and rectal contrast for CT performed to detect bowel injury in the context of penetrating torso trauma. Given the lack of published societal guidelines, our goal was to survey radiologists from the American Society of Emergency Radiology membership database to determine consensus on CT protocols for penetrating trauma.

METHODS

With ethics board approval, an anonymous ten-question online survey was distributed via email to 589 radiologists in the American Society of Emergency Radiology (ASER) member database. The survey was open for a 4-week period in February 2018. A commercially available website that allows subscribers to create and analyze survey results was used for analysis.

RESULTS

We received 124 responses (21% response rate) with a majority from U.S. institutions (82%). Seventy-four percent of respondents indicated they do not routinely administer oral contrast in penetrating trauma, 68% do not administer rectal contrast, and 90% do not use commercially available software to assess penetrating injury trajectory. Results from U.S. and non-U.S. practices were comparable. The decision to administer intraluminal contrast is made by the referring physician at 52% of institutions. There is in-house attending level radiology coverage at 54% of institutions and when asked if trauma scans are reviewed before removing the patient from the table, 41% of respondents answered "No."

CONCLUSION

Enteric contrast is used in a minority of respondents' centers for penetrating trauma cases, which is likely driven by a perceived lack of added benefit and delays in patient care.

Effectiveness of computed tomography scanning to detect blunt bowel and mesenteric injuries requiring surgical intervention: A systematic literature review

BACKGROUND

Computed tomography (CT) diagnostic accuracy for blunt bowel and mesenteric injuries (BBMI) is controversial.

DATA SOURCES

A literature review to compute aggregate CT performance and individual CT sign sensitivity, specificity, and positive predictive value (PPV) for operative BBMI.

CONCLUSIONS

Sensitivity, specificity, and PPV were: overall CT performance 85.3%, 96.1%, 51.4%; abnormal wall enhancement 30.1%, 95.7%, 64.0%; bowel wall discontinuity 22.3%, 99.0%, 87.9%; bowel wall hematoma 22.5%, 100%, 19.5%; bowel wall thickening 35.2%, 96.5%, 32.1%; free air 32.0%, 98.7%, 57.1%; free fluid 65.6%, 85.0%, 25.5%; mesenteric air 27.6%, 99.1%, 85.3%; mesenteric extravasation 22.9%, 99.6%, 73.9%; mesenteric hematoma/fluid 33.9%, 98.7%, 52.8%; mesenteric stranding/streaking 34.3%, 91.8%, 31.6%; mesenteric vessel beading 32.1%, 97.2%, 60.4%; mesenteric vessel termination 31.6%, 97.2%, 63.5%; oral contrast extravasation 10.0%, 100%, 100%; retroperitoneal air 9.4%, 94.9%, 55.6%; and retroperitoneal fluid 44.2%, 49.4%, 38.5%. Sensitivity, specificity, and PPV vary substantially among known signs. Other clinical factors are necessary for comprehensive BBMI identification.

Impact of low-kVp scan technique on oral contrast density at abdominopelvic CT

PURPOSE

To assess quantitative and qualitative effects of kVp on oral contrast density.

MATERIALS AND METHODS

Three readers retrospectively reviewed 100 CT scans performed at a range of high- and low-energy settings, independently determining their preferred window and level settings for evaluation of the oral-contrast-opacified bowel. Contrast density was also assessed quantitatively in the stomach, jejunum, and ileum. Subsequently, a range of oral contrast dilutions were imaged at varying kVp's in a commercially available CIRS tissue equivalent phantom model.

RESULTS

In the retrospective patient study, mean oral contrast density increased significantly in the ileum compared to the jejunum (455.2 and 308.8 HU, respectively, p < 0.01). Similar findings were seen in patients regardless of patients' weight. Mean oral contrast density was higher on lower-energy scans, requiring more window/level adjustment. An oral contrast iodine concentration of 5.82-7.77 mg I/mL most closely approximated a target oral contrast density of 200 HU.

CONCLUSIONS

Oral contrast density is strongly influenced by kVp, supporting use of more dilute oral contrast when using lower-kVp techniques.

Single-Contrast CT for Detecting Bowel Injuries in Penetrating Abdominopelvic Trauma

OBJECTIVE

Many centers advocate use of triple-contrast (IV, oral, and rectal) CT for assessing hemodynamically stable patients with penetrating abdominopelvic trauma. Enteric contrast material has several disadvantages, leading our practice to pursue use of single-contrast (IV) CT. We conducted a retrospective review of electronic medical records at our institution to assess the accuracy of single-contrast CT for diagnosing bowel injuries in cases of penetrating abdominopelvic trauma.

MATERIALS AND METHODS

We retrospectively reviewed patients who presented to our emergency department between January 1, 2004, and March 1, 2014, with penetrating abdominopelvic trauma, underwent an abdominopelvic CT, and had surgery performed thereafter. We reviewed pertinent emergency department records for details regarding the site of injury, the number of injuries per patient, and the type of weapon used. We correlated CT reports with operative notes for presence and sites of bowel injury.

RESULTS

A total of 274 patients (median age, 27 years old) met our inclusion criteria; 77% had sustained gunshot wounds (GSWs). CT showed bowel injury in 173 cases; surgery revealed bowel injury in 162 cases. CT had 142 true-positive, 31 false-positive, 81 true-negative, and 20 false-negative cases, resulting in sensitivity of 88%, specificity of 72%, positive predictive value of 82%, and negative predictive value of 80% for detecting bowel injuries. CT had the highest sensitivity and specificity in patients with multiple GSWs (94% and 79%, respectively) and those with injuries to the stomach and rectum.

CONCLUSION

Single-contrast CT can show bowel injuries in patients with penetrating abdominopelvic trauma with accuracy comparable with that reported for triple-contrast CT.

Nontraumatic large bowel perforation: spectrum of etiologies and CT findings

Large bowel perforation is an abdominal emergency that results from a wide range of etiologies. Computed tomography is the most reliable modality in detecting the site of large bowel perforation. The diagnosis is made by identifying direct CT findings such as extraluminal gas or contrast and discontinuity along the bowel wall. Indirect CT findings can help support the diagnosis, and include bowel wall thickening, pericolic fat stranding, abnormal bowel wall enhancement, abscess, and a feculent collection adjacent to the bowel. Common etiologies that cause large bowel perforation are colon cancer, foreign body aspiration, stercoral colitis, diverticulitis, ischemia, inflammatory and infectious colitides, and various iatrogenic causes. Recognizing a large bowel perforation on CT can be difficult at times, and there are various entities that may be misinterpreted as a colonic perforation. The purpose of this article is to outline the MDCT technique used for evaluation of suspected colorectal perforation, discuss relevant imaging findings, review common etiologies, and point out potential pitfalls in making the diagnosis of large bowel perforation.

Emergency CT of blunt abdominal trauma: experience from a large urban hospital in Southern China

Trauma is one of the leading causes of death for men and women under the age of 45 years old, and abdominal injuries contribute to a large number of these deaths. Prompt diagnosis is very important for treatment decision making and can be life-saving. CT has become an essential imaging modality in emergency medicine. In this pictorial review, we present our experience of CT in blunt abdominal trauma and describe CT findings of common injuries, including hemoperitoneum, solid viscera, hollow viscera, mesenteric and diaphragmatic injuries. Unenhanced CT is routinely used, tailored protocols should be reserved for patients with questionable or subtle findings at unenhanced CT, especially for bowel and mesenteric injuries. The decision can be made by radiologists based on initial findings or by referring clinicians based by clinical presentations or deterioration of patients' condition.

Impact of low-energy CT imaging on selection of positive oral contrast media concentration

OBJECTIVES

To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish optimal OCM concentrations for low-energy diagnostic CT exams.

METHODS

One hundred patients (38 men and 62 women; age 62 ± 11 years; BMI 26 ± 5) with positive OCM-enhanced 120-kVp single-energy CT (SECT), and follow-up 100-kVp acquisitions (group A; n = 50), or 40-70-keV reconstructions from rapid kV switching-single-source dual-energy CT (ssDECT) (group B; n = 50) were included. Luminal attenuation from different GIT segments was compared between exams. Standard dose of three OCM and diluted solutions (75%, 50%, and 25% concentrations) were introduced serially in a gastrointestinal phantom and scanned using SECT (120, 100, and 80 kVp) and DECT (80/140 kVp) acquisitions on a ssDECT scanner. Luminal attenuation was obtained on SECT and DECT images (40-70 keV), and compared to 120-kVp scans with standard OCM concentrations.

RESULTS

Luminal attenuation was higher on 100-kVp (328 HU) and on 40-60-keV images (410-924 HU) in comparison to 120-kVp scans (298 HU) in groups A and B (p < 0.05). Phantom: There was an inverse correlation between luminal attenuation and X-ray energy, increasing up to 527 HU on low-kVp and 999 HU on low-keV images (p < 0.05). 25% and 50% diluted OCM solutions provided similar or higher attenuation than 120 kVp, at low kVp and keV, respectively.

CONCLUSIONS

Low-energy CT imaging increases the attenuation of GIT opacified with positive OCM, permitting reduction of 25%-75% OCM concentration.

Bowel and mesenteric injuries from blunt abdominal trauma: a review

The bowel and the mesentery represent the third most frequently involved structures in blunt abdominal trauma after the liver and the spleen. Clinical assessment alone in patients with suspected intestinal and/or mesenteric injury from blunt abdominal trauma is associated with unacceptable diagnostic delays. Multi-detector computed tomography, thanks to its high spatial, time and contrast resolutions, allows a prompt identification and proper classification of such conditions. The radiologist, in fact, is asked not only to identify the signs of trauma but also to provide an indication of their clinical significance, suggesting the chance of conservative treatment in the cases of mild and moderate, non-complicated or self-limiting injuries and focusing on life-threatening conditions which may benefit from immediate surgical or interventional procedures. Specific and non-specific CT signs of bowel and mesenteric injuries from blunt abdominal trauma are reviewed in this paper.

Duodenal hematoma following EGD: comparison with blunt abdominal trauma-induced duodenal hematoma

BACKGROUND

Duodenal hematoma (DH) is a rare complication of esophagogastroduodenoscopy (EGD) with duodenal biopsy and uncommon, but better described following blunt abdominal trauma (BAT). We aimed to describe DH incidence and investigate risk factors for DH development post-EGD and compare its features to those post-BAT.

METHODS

Multiple electronic databases were searched for the diagnosis of DH from 2000 to 2012. Inclusion criteria were patients 0 to 21 years of age who developed a DH following EGD with biopsy or BAT. Exclusion criteria were DH secondary to any other mechanism, EGD performed at another medical center, and insufficient information in the electronic medical record to determine treatments or outcomes.

RESULTS

A total of 14 post-EGD and 15 post-BAT patients with DH were included in the study. There were 26,905 EGDs with duodenal biopsies performed during the study period, for an incidence of 1:1922 procedures. Thirteen of 14 (93%) post-EGD DH events occurred between 2007 and 2012 (P < 0.001). The proportion of procedures performed under general anesthesia versus moderate sedation, and performed in the supine position versus left lateral decubitus were close to but did not reach statistical significance. DH-related complications and time to hematoma resolution was similar between groups.

CONCLUSIONS

In a 13-year study period, 14 patients developed DH after EGD, for an incidence of 1:1922. Method of sedation and supine positioning of the patient during endoscopy warrant further investigation as potential risks. The clinical course and time to recovery with conservative management are similar between patients with EGD and BAT-induced DH.

Improvement of distension and mural visualization of bowel loops using neutral oral contrasts in abdominal computed tomography

AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2% (positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.

METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 mL of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 mL of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%.

RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent (P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent (P < 0.05).

CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.