Abdominal trauma: use of oral contrast material for CT is safe

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.

Rectal trauma in adults

Rectal trauma is associated with high rates of morbidity and mortality and generally affects young males due to its aetiology of violent crime and vehicular collision. Historically, management has followed principles derived from military practice, with faecal diversion, pre-sacral drainage and distal washout being mandatory. Civilian trauma studies examining management of colon and rectum injuries from the early 1950s identified major differences in the level of energy transfer between civilian and military wounds, given that the vast majority are penetrating in nature. This led to a re-evaluation of the necessity for these interventions for all rectal injuries. Current management depends on whether the injury is intra- or extraperitoneal, with those above the peritoneal reflection being readily accessible and amenable to treatment as for colon injury. Extraperitoneal injuries remain difficult to access and direct repair is usually impossible; the mainstay of treatment in most instances remains faecal diversion. The role of pre-sacral drainage and distal washout remains contentious in the realms of civilian rectal injury but retains a place in battlefield or other high-energy transfer rectal injuries where aggressive early management reduces septic complications. This article reviews the historical and current evidence for the management of both civilian and military extraperitoneal rectal injuries.

Gastric emptying time of oral contrast material in children and adolescents undergoing abdominal computed tomography

OBJECTIVES

: Considering the hazards of pulmonary aspiration of oral contrast material (OCM) during general anesthesia, we investigated the gastric emptying time (GET) of OCM in children and adolescents undergoing abdominal computed tomography (CT).

PATIENTS AND METHODS

: Included in the study were 101 consecutive patients ages 3.1 to 17.9 years (mean age 12.2 +/- 3.3 years), who underwent contrast-enhanced abdominal CT for suspected acute appendicitis (n = 90), abdominal trauma (n = 10), or suspected ileus (n = 1). Oral iodinated ioxithalamate was given for bowel opacification. Background data (age, sex, weight, chronic diseases, and medication intake), time of initiation and completion of OCM, and time of CT scanning were recorded. To estimate the GET of OCM, CT images were reviewed to examine whether the stomach was empty or full of OCM at the time of imaging.

RESULTS

: The Kaplan-Meier curve showed that 75% of the patients had OCM in the stomach 48 +/- 5.2 minutes after its completion, 50% after 74 +/- 7.9 minutes, and 25% after 135 +/- 32.5 minutes; 1 patient still had OCM after 162 minutes. Except for the length of time taken to drink the contrast material (< or =90 minutes was associated with slower empting of the stomach; log rank, P = 0.03), GET of OCM was not correlated with sex (P = 0.16), age (P = 0.15), weight (P = 0.13), or type of diagnosis (P = 0.41).

CONCLUSIONS

: Given the variability of GET of OCM and if clinically feasible, we advocate waiting at least 3 hours between completion of OCM ingestion and general anesthesia induction.

Free abdominal fluid without obvious solid organ injury upon CT imaging: an actual problem or simply over-diagnosing?

Whereas a non-operative approach for hemodynamically stable patients with free intraabdominal fluid in the presence of solid organ injury is generally accepted, the presence of free fluid in the abdomen without evidence of solid organ injury not only presents a challenge for the treating emergency physician but also for the surgeon in charge. Despite recent advances in imaging modalities, with multi-detector computed tomography (CT) (with or without contrast agent) usually the imaging method of choice, diagnosis and interpretation of the results remains difficult. While some studies conclude that CT is highly accurate and relatively specific at diagnosing mesenteric and hollow viscus injury, others studies deem CT to be unreliable. These differences may in part be due to the experience and the interpretation of the radiologist and/or the treating physician or surgeon.A search of the literature has made it apparent that there is no straightforward answer to the question what to do with patients with free intraabdominal fluid on CT scanning but without signs of solid organ injury. In hemodynamically unstable patients, free intraabdominal fluid in the absence of solid organ injury usually mandates immediate surgical intervention. For patients with blunt abdominal trauma and more than just a trace of free intraabdominal fluid or for patients with signs of peritonitis, the threshold for a surgical exploration - preferably by a laparoscopic approach - should be low. Based on the available information, we aim to provide the reader with an overview of the current literature with specific emphasis on diagnostic and therapeutic approaches to this problem and suggest a possible algorithm, which might help with the adequate treatment of such patients.

Hollow viscus injury

BACKGROUND

Hollow viscus injuries are uncommon and occur in approximately 1% of all blunt trauma patients.

DISCUSSION

These injuries are often not suspected and are difficult to diagnosis. Morbidity and mortality are high, and a negative abdominal computed tomography is not sufficient to rule out these injuries in certain clinical scenarios.

CONCLUSION

Using a case-based approach, the epidemiology and diagnostic pathways to manage hollow viscus injuries are reviewed.

Emergency department imaging: current practice

PURPOSE

To provide a snapshot of the demographics of radiologists providing coverage for emergency departments (EDs) and current imaging practices in EDs in the United States.

METHODS

An online survey was created with Views Flash 3 software (Cogix, Monterey, California). Random e-mail addresses from a variety of databases were chosen. A total of 678 surveys were sent over a 9-month period.

RESULTS

One hundred ninety-two radiology groups (28%) responded to the survey. Forty-one groups (21%) had designated emergency radiology divisions. Sixty-three groups (33%) were using computed tomographic (CT) coronary angiography in the ED workup of chest-pain. Thirty-five groups (18%) were using "triple-rule-out scans" (ie, a single CT scan to rule out coronary artery disease, pulmonary embolism, and aortic dissection). Multiplanar reconstructions of chest, abdominal, and pelvic CT images were routinely performed by 95 groups (49%). Forty-four percent used reformatted CT images instead of conventional radiographs in the workup of cervical spine trauma, and 68 groups (35%) used reformations in thoracic and lumbar spine trauma. Ninety groups (47%) did not use oral contrast for blunt abdominal trauma CT scanning. Sixty-seven respondents (35%) preferred computed tomography to evaluate for acute appendicitis in the setting of pregnancy. Forty percent of imaging equipment located within the EDs was CT scanners. The majority of the groups still communicated unexpected findings via telephone (49%).

CONCLUSION

New imaging practices for the evaluation of entities such as chest pain, spine trauma, and abdominal pain and trauma are emerging in EDs. As one plans ED development, these trends should be considered.

Multidetector-Row Computed Tomography Imaging of Splenic Trauma

The spleen is the intra-abdominal organ most often injured as a result of blunt trauma. Multidetector-row computed tomography (MDCT) plays an important role in the detection and characterization of splenic injury. It has been shown to be highly accurate and can detect splenic vascular lesions, the presence of which has been shown to be a predictor of failure of nonoperative management. The increased use of angiography and splenic artery embolization in the management of such injuries has led to improved success rates with nonoperative management. This article reviews the various appearances of the injured spleen and discusses the use of MDCT in the initial evaluation of injury. The indications for angiography and embolization are reviewed, with examples of appearances of the postembolization spleen.

Multidetector CT evaluation of abdominal trauma

CT is the imaging modality of choice to evaluate blunt abdominal trauma. With the advent of multidetector CT (MDCT), scanning times have progressively decreased while image resolution has increased owing to thinner collimation and reduced partial volume and motion artifacts. MDCT also allows high quality two-dimensional and three-dimensional multiplanar reformatted images to be obtained, which aid in the diagnosis of the complex multisystem injuries seen in the trauma patient. This article describes the authors' current imaging protocol with 16-detector MDCT, the spectrum of CT findings seen in patients with blunt abdominal injuries, and the role MDCT has in guiding injury management.

Computed tomography without oral contrast solution for blunt diaphragmatic injuries in abdominal trauma

OBJECTIVE

The aim of this study was to estimate the sensitivity, specificity, and positive predictive value (PPV) of computed tomography (CT) without oral contrast for diaphragm injuries (DIs) in blunt abdominal trauma.

METHODS

We prospectively enrolled 500 consecutive "trauma-one" patients who received CT imaging and interpretation (CT-Read1) of the abdomen within 45 minutes of their arrival from July 2000 to December 2001. All patients were imaged without oral contrast but with intravenous contrast. Computed tomographic images were reviewed within 24 hours of admission by research radiologists (CT-Read2) blinded to CT-Read1. True DIs were determined hierarchically by either laparotomy or autopsy.

RESULTS

There were 9 patients with laparotomy or autopsy-proven blunt DIs; 8 of these injuries involved the left hemidiaphragm. The CT-Read1 correctly detected only 6 of 9 blunt DIs, thus missing 3 DIs. One of these involved the right hemidiaphragm, whereas the other 2 were left sided. There were no false-positive findings with CT-Read1 for blunt DI. The sensitivity and specificity of CT imaging with respect to DI were 66.7% (95% CI, 29.9%-92.5%) and 100% (95% CI, 99.2%-100%), respectively. The PPV for the test was 1.00 (95% CI, 0.65-1.00).

CONCLUSION

Although the low number of blunt DIs in this study limits its general applicability, CT imaging of the diaphragm without oral contrast appears to perform within the range of reported imaging techniques using oral contrast. Still, CT scanning appears to have an unsatisfactorily low sensitivity to be reliably used in eliminating the diagnosis of blunt DI.

Blunt Abdominal Trauma: Performance of CT without Oral Contrast Material

PURPOSE

To retrospectively evaluate multi-detector row computed tomography (CT) without oral contrast material for depiction of bowel and mesenteric injuries that require surgical repair in patients with blunt abdominal trauma.

MATERIALS AND METHODS

The investigational review board approved the study. Informed consent was waived. CT reports for October 2001 to September 2003 were reviewed and 1082 patients were identified who had undergone abdominopelvic CT with a multi-detector row scanner and without oral contrast material. Findings were divided into four categories: negative, solid organ injury with or without hemoperitoneum, free fluid only, and suspected bowel or mesenteric injury. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated by comparing CT findings with laparotomy reports and hospital course.

RESULTS

CT findings were no intraabdominal injury (n = 932), solid organ injury only (n = 102), free fluid only (n = 34), and suspected bowel or mesenteric injury (n = 14). CT findings in patients suspected of having bowel or mesenteric injury were pneumoperitoneum with other secondary findings (n = 4), mesenteric hematoma and bowel wall abnormality (n = 2), mesenteric hematoma only (n = 4), and bowel wall thickening only (n = 4). In 11 patients, bowel or mesenteric injury was proved surgically. Thus, the study included 1066 true-negative, nine true-positive, two false-negative, and five false-positive results. Based on these data, sensitivity was 82% (95% confidence interval [CI]: 52%, 95%), specificity was 99% (95% CI: 98%, 99%), positive predictive value was 64% (95% CI: 39%, 83%), and negative predictive value was 99% (95% CI: 98%, 99%) for depiction of bowel and mesenteric injuries.

CONCLUSION

Multi-detector row CT without oral contrast material is adequate for depiction of bowel and mesenteric injuries that require surgical repair. Results are comparable with previously reported data for single-detector row helical CT with oral contrast material.

Computed tomographic scanning without oral contrast solution for blunt bowel and mesenteric injuries in abdominal trauma

BACKGROUND

Computed tomographic (CT) scanning using intravenous and oral contrast material has traditionally been advocated for the evaluation of intra-abdominal injury, including blunt bowel and mesenteric injuries (BBMIs). The necessity of oral contrast in detecting these injuries has recently been called into question. The purpose of this study was to determine the sensitivity and specificity of CT scanning without oral contrast for BBMIs.

METHODS

We prospectively enrolled 500 consecutive blunt trauma patients who received CT imaging and interpretation (CT-Read1) of the abdomen from July 2000 to November 2001. All patients were imaged without oral contrast, but with intravenous contrast. CT images were reviewed within 24 hours of admission by a research radiologist (CT-Read2) blinded to CT-Read1. For study purposes, true BBMI was determined to be present if either laparotomy or autopsy identified bowel or mesenteric injury, or both CT-Read2 and the hospital discharge summary described bowel or mesenteric injury. Three-month telephone follow-up was also completed.

RESULTS

CT-Read1 detected 19 of 20 bowel and mesenteric injuries. CT-Read1 missed one duodenal perforation. There were two patients with false-positive interpretations of CT-Read1 for bowel injury. The sensitivity and specificity of CT imaging for the detection of BBMIs were 95.0% and 99.6%, respectively.

CONCLUSION

CT imaging of the abdomen without oral contrast for detection of BBMIs compares favorably with CT imaging using oral contrast.

Blunt injury to mesentery and small bowel:

Helical CT now allows rapid acquisition of sections through the abdomen and pelvis with optimal vascular opacification and minimal motion artifact. Oral contrast may aid in the identification of subtle bowel and mesenteric injuries and does not have any significant deleterious effects. CT findings of extraluminal enteric contrast, active hemorrhage, or free intraperitoneal-retroperitoneal air allow accurate diagnosis of SBMI in the setting of blunt abdominal trauma. Mesenteric hematoma in association with bowel wall thickening or the presence of significant amounts of free fluid without solid organ injury is highly suspicious for SBMI requiring laparotomy. CT alone or in concert with DPL and physical examination is a valuable tool in the timely diagnosis and treatment of bowel and mesenteric injury caused by blunt trauma.

Imaging of renal trauma

Trauma is a major cause of death and disability and renal injuries occur in up to 10% of patients with significant blunt abdominal trauma. Patients with penetrating trauma and hematuria, blunt trauma with shock and hematuria, or gross hematuria warrant imaging of the urinary tract specifically and CT is the preferred modality. If there is significant perinephric fluid, especially medially, or deep laceration, delayed images should be obtained to evaluate for urinary extravasation. Most renal injuries are minor, including contusions, subcapsular and perinephric hematoma, and superficial lacerations. More significant injuries include deep lacerations, shattered kidney, active hemorrhage, infarctions, and vascular pedicle and UPJ injuries. These injuries are more likely to need surgery or have delayed complications but may still often be managed conservatively. The presence of urinary extravasation and large devitalized areas of renal parenchyma, especially with associated injuries of intraperitoneal organs, is particularly prone to complication and usually requires surgery. Active hemorrhage should be recognized because it often indicates a need for urgent surgery or embolization to prevent exsanguination.

Common tasks and problems in paediatric trauma radiology

Scope of this article is to give practical hints for the most common, typical and important topics of trauma radiology in children to those radiologists who are not exclusively occupied with paediatric imaging. Due to the increased radiation sensitivity of children compared with adults balancing radiation protection and necessary image quality is of utmost importance. Outlines for this optimisation process are given. Especially in imaging of the extremities perhaps the greatest difficulties are posed by the dynamically changing face of the immature, growing, only partially ossified skeleton. Lack of experience must be compensated by meticulous comparison with the normal skeletal development as shown in standard textbooks, and by knowledge of the radiological image of the developmental variants. Besides general remarks about paediatric trauma radiology, some important topics are discussed into more detail. Especially the elbow joint poses a challenge for those less experienced with its radiological appearance in children. More than in adults, ultrasound should remain the primary imaging modality of choice especially in the assessment of abdominal trauma, and CT be tailored to radiological and clinical findings. Imaging and diagnosis of non-accidental injury (NAI) may be a less common task for the general radiologist, however, the severe social implications of physical child abuse mandate a basic knowledge about the radiological symptoms and the imaging management of this problem for all physicians occupied with paediatric radiology.

Is administration of enteric contrast material safe before abdominal CT in children who require sedation? Experience with chloral hydrate and pentobarbital

OBJECTIVE

It has been common practice to administer enteric contrast material in preparation for abdominal CT in children who require sedation to be examined. At some institutions, the practice of administering an anesthetic or enteric contrast material before sedation is being challenged because it violates the "nothing by mouth" status that is otherwise strictly enforced before sedation. Our purpose was to review our safety record in administering enteric contrast material for CT before sedation.

MATERIALS AND METHODS

Radiology reports, medical records, and department incident reports were reviewed for the past 5 years from all patients who required sedation for abdominal CT. Patient age and sex, type of sedation, and complications (defined as vomiting with aspiration) related to enteric contrast material before the sedation were recorded. For routine oral contrast material, diluted Hypaque (meglumine diatrizoate) was administered in an age-based amount 1-2 hr before scanning. For sedation, depending on the patient's age, either oral chloral hydrate (70-100 mg/kg) or IV pentobarbital (3 mg/kg with repeated doses of up to 7 mg/kg) was used.

RESULTS

Three hundred sixty-seven patients who received oral contrast material before sedation for abdominal CT were identified (200 boys, 167 girls; age range, 1 month-19 years; mean age, 2.9 years). Chloral hydrate was used in 30 patients and IV pentobarbital in 337 patients. No complications related to the administration of oral contrast material before sedation were identified.

CONCLUSION

The practice of administering oral contrast material in children before sedation for abdominal CT appears to be safe when using the sedation drugs and protocols in place at our institution. Further study of the safety of this practice should be undertaken.

Application of oral contrast media in coregistered positron emission tomography-CT

OBJECTIVE

Coregistration of positron emission tomography (PET) and CT images results in significantly improved localization of abnormal FDG uptake compared with PET images alone. For delineation of intestinal structures, application of oral contrast media is a standard procedure in CT. The influence of oral contrast agents in PET imaging using CT data for attenuation correction was evaluated in a comparative study on an in-line PET-CT system.

SUBJECTS AND METHODS

Sixty patients referred for PET-CT were evaluated in two groups. One group of 30 patients received oral Gastrografin 45 min before data acquisition. The second group received no contrast medium. PET images were reconstructed, using CT data for attenuation correction. Image analysis was performed by two reviewers in consensus, using a 4-point scale comparing FDG-uptake in the gastrointestinal tract in PET images of both groups. Furthermore, correlation of FDG uptake and localization of contrast media in the intestinal tract in CT images were determined.

RESULTS

No significant difference in FDG uptake in PET images in all regions of the gastrointestinal tract except the ascending colon was seen in both groups. No correlation was found in the location of increased FDG uptake and contrast media in the CT images.

CONCLUSION

An oral contrast agent can be used for coregistered PET-CT without the introduction of artifacts in PET.

Performance of CT in detection of bowel injury

OBJECTIVE

The objective of our study was to identify relevant and reliable CT signs of bowel injury, to determine the overall performance of CT in detection of bowel injuries, and to establish the effect of the training level of radiologists on this performance.

MATERIALS AND METHODS

Abdominal CT scans of 112 patients with blunt abdominal trauma were prospectively and retrospectively reviewed. Fifty patients had proven bowel injuries (with or without other visceral injuries), whereas 62 patients had no bowel injury and comprised the comparison or control group. Thirty-one of the 62 patients in the comparison group had surgical proof of abdominal but not bowel or mesenteric injuries. The retrospective review of the 112 CT scans was performed randomly and individually by nine radiologists unaware of the diagnosis, including three faculty abdominal radiologists, three senior residents in training, and three junior residents in training. Individual performance and group performance were evaluated by receiver operating characteristic analysis, and interobserver agreement was tested. Individual CT signs as relevant predictors of bowel injury were identified by logistic regression.

RESULTS

Relevant predictors of bowel injury included mesenteric infiltration, bowel wall thickening, extravasation of vascular or enteric contrast agent, and the presence free air. In the retrospective blinded review, CT showed good to excellent interobserver reliability for individual CT signs as well as for diagnosis of bowel and visceral injuries. Faculty radiologists tended to diagnose injuries with greater accuracy and confidence, but they showed significantly better performance than residents only in diagnosing duodenal perforation. For the prospective CT diagnosis of bowel injury, CT had a sensitivity of 64%, an accuracy of 82%, and a specificity of 97%.

CONCLUSION

Bowel injuries are challenging to diagnose on CT. Radiologists with various levels of experience and expertise can achieve accurate and reproducible results using a variety of CT criteria.

Abdominal trauma in infants and children: prompt identification and early management of serious and life-threatening injuries. Part I: injury patterns and initial assessment

Evaluation of children with abdominal trauma can be a difficult process. Unique anatomic features predispose children to specific injuries and potentially make identification of life-threatening injuries difficult. While Part I of this review discusses the initial assessment and diagnostic testing in children with abdominal trauma, Part II will review specific injuries and ED management of children with possible abdominal trauma. Knowledge of each of these factors will improve the ability of general and pediatric emergency physicians to expeditiously identify children with potential serious injury and initiate appropriate treatment.

Retrospective analysis of the adequacy of oral contrast material for computed tomography scans in trauma patients

BACKGROUND

This study examined the adequacy of oral contrast (OC) in adult trauma patients, the differences in the incidence of pathology and other patient characteristics related to OC adequacy, and the incidence of OC-associated emesis.

METHODS

The cases of 129 adult trauma patients were reviewed from January to December 1996 for utilization of OC, administration time, time to computed tomography (CT), and emesis within 4 hours. CT films were reviewed for adequacy of OC (AC = adequate contrast, IC = inadequate contrast) and pathology.

RESULTS

Data are presented as median and range, or percentage and 95% confidence interval (CI). Pathology was found in 24% (CI 17% to 31%) and was not associated with AC. OC administration to CT was 14 minutes (0 to 139). IC was present for 60% (CI 52% to 69%). Subjects with IC had higher injury severity scores. 10% (CI 5% to 15%) with OC had emesis.

CONCLUSION

OC is not necessary for diagnostic accuracy, and may contribute to patient morbidity or discomfort.