Location of the transition zone in CT of small-bowel obstruction: added value of multiplanar reformations

Computed Tomographic Features of Bezoars and Other Gastrointestinal Foreign Bodies in Dogs and Cats: A Comparative Analysis

This study presents a comparative analysis of the computed tomographic (CT), radiographic, and ultrasonographic (US) characteristics of gastrointestinal foreign bodies, including bezoars, in dogs and cats, and evaluates their association with complications and clinical outcomes. A total of 33 cases (26 dogs, 7 cats) with surgically or endoscopically confirmed foreign bodies were reviewed, classified as bezoars (n = 15) or distinct foreign bodies (n = 18). CT features such as attenuation values, transition zones, and proximal-to-distal small intestinal diameter ratios were compared. Bezoars typically appeared as intraluminal masses with mottled gas patterns and indistinct boundaries (33.3% vs. 94.4%, p < 0.001) and were associated with longer clinical signs (median 14 vs. 5.5 days, p = 0.013), more frequent transition zones (92.3% vs. 41.7%, p = 0.011), and a greater diameter ratio (2.9 vs. 1.25, p = 0.012) across the transition zone. Radiographic and US evaluations were available in six bezoar cases; only one radiograph (17%) detected the bezoar, while US showed acoustic shadowing in four cases (67%). Six patients (18%) experienced adverse outcomes, with bowel wall ruptures significantly associated with poor prognosis (p < 0.001). These findings highlight the superior diagnostic performance of CT, particularly for bezoars, and emphasize the importance of identifying transition zones and bowel diameter ratios in assessing gastrointestinal foreign bodies and their associated risks. Early CT evaluation may thus facilitate timely intervention and improve clinical outcomes.

Band adhesions in a virgin abdomen: A case report

INTRODUCTION

Small bowel obstruction secondary to adhesions in a virgin abdomen is encountered very rarely. Its rarity may cause a delay in diagnosis that can lead to complications among which is sepsis and death. In contrast, On-time diagnosis constitutes one of many pillars of the best outcome for the patient.

CASE PRESENTATION

We present a case of a 46-year-old female exhibiting symptoms of small bowel obstruction that persisted for five days. Her previous surgical history was negative. Upon testing, we found a neutrophilic leukocytosis and an abdominal x-ray revealed dilated bowel loops with multiple air-fluid levels and no air under the diaphragm with an increased pulse rate and respiratory rate. An emergency exploratory laparotomy definitively identified congenital band adhesions as the root cause of the obstruction.

DISCUSSION

Abdominal x-ray is the starting investigation in rural health facilities of Low and Middle Income Countries (LMICs), but lacks the ability to detect complications such as strangulation and ischemia as can the multidetector Computed Tomography scan and the Magnetic Resonance Imaging. A non-resolving small bowel obstruction or the one associated with peritonitis or bowel ischemia should undergo a surgical intervention.

CONCLUSION

A negative surgical history should not annihilate the suspicion of band adhesions in small bowel obstruction. Early diagnostic imaging is helpful. When this is not possible, a laparotomy should be done if clinically indicated. The patient had an uneventful recovery.

Multiplanar CT reconstructions allow optimization of the laparoscopic surgical approach for liver lesions

PURPOSE

Resection of hepatic lesions can be difficult and requires careful analysis of pre-operative imaging. The aim of this study is to highlight the use of multiplanar CT reconstruction in liver surgery, which helps to anticipate intra-operative technical difficulties.

METHODS

We retrospectively selected the imaging of several patients managed for liver lesions in specific locations: liver dome (IVa, VIII), the left lobe (intra-parenchymal, left edge), and the antero-inferior edge of segment VI. The IWATE classification was used to grade the difficulty of these resections.

RESULTS

Multiplanar analysis has made it possible to change the level of difficulty of liver resection and to anticipate intra-operative difficulties. Frontal and/or sagittal section in addition to axial sections analysis increased the IWATE score.

CONCLUSION

Multi-planar reconstruction must be a tool used by the liver surgeon pre-operatively in order to limit intra-operative complications.

The value of MSCT in evaluating the passability of bezoar by conservative treatment for bezoars-induced small bowel obstruction

PURPOSE

To explore the multi-slice spiral computed tomography (MSCT) imaging characteristics of patients with bezoars-induced small bowel obstruction (BI-SBO) to evaluate the risk of conservative treatment.

MATERIALS AND METHODS

This retrospective study included 72 patients with BI-SBO who underwent whole-abdominal MSCT scan within 1 day before treatment. The patients were classified as the non-pass group and pass group depending on whether bezoar can pass after conservative treatment. The CT images were observed and measured by two radiologists. Statistical analysis was performed by using Student's t test, Pearson's chi-squared test, Fisher's exact test, Logistic linear regression, and receiver operating characteristic curve (ROC).

RESULTS

The study population consisted of 72 patients with a mean age of 52.2 ± 16.2 years (32 men and 40 women with an age range of 13-81 years). There were statistical differences between the two groups in the bezoar appearance, maximum HU of bezoar, thickness of intestinal wall, mesenteric haziness, mesenteric fluid, and peritoneal fluid (P = 0.002, 0.024, 0.017, 0.006, 0.021, and 0.030). The appearance of bezoar and mesenteric haziness is independent risk factors affecting whether bezoar can be passed by the conservative treatment. Sensitivity (41.7%) was decreased, NPV (76.3%) was not significantly changed, specificity (93.8%) and PPV (76.9%) were improved when both parameters were met to assess failure of conservative treatment.

CONCLUSION

The observation of important signs by MSCT and its reconstruction technology is of great clinical value in evaluating the passability of bezoar by conservative treatment, and which can provide radiographic basis for clinical treatment selection.

Adhesion-related small bowel obstruction: deep learning for automatic transition-zone detection by CT

Background

To train a machine-learning model to locate the transition zone (TZ) of adhesion-related small bowel obstruction (SBO) on CT scans.

Materials and methods

We used 562 CTs performed in 2005–2018 in 404 patients with adhesion-related SBO. Annotation of the TZs was performed by experienced radiologists and trained residents using bounding boxes. Preprocessing involved using a pretrained model to extract the abdominopelvic region. We modeled TZ localization as a binary classification problem by splitting the abdominopelvic region into 125 patches. We then trained a neural network model to classify each patch as containing or not containing a TZ. We coupled this with a trained probabilistic estimation of presence of a TZ in each patch. The models were first evaluated by computing the area under the receiver operating characteristics curve (AUROC). Then, to assess the clinical benefit, we measured the proportion of total abdominopelvic volume classified as containing a TZ for several different false-negative rates.

Results

The probability of containing a TZ was highest for the hypogastric region (56.9%). The coupled classification network and probability mapping produced an AUROC of 0.93. For a 15% proportion of volume classified as containing TZs, the probability of highlighted patches containing a TZ was 92%.

Conclusion

Modeling TZ localization by coupling convolutional neural network classification and probabilistic localization estimation shows the way to a possible automatic TZ detection, a complex radiological task with a major clinical impact.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-021-01150-y.

Computed Tomography in Emergency Diagnosis and Management Considerations of Small Bowel Obstruction for Surgical vs. Non-surgical Approach

BACKGROUND

Small bowel obstruction (SBO) accounts for 15% of abdominal pain complaints referred to emergency departments and imposes significant financial burdens on the healthcare system. The absence of passage of flatus or stool and abdominal distention are reported as the most common symptom and a sign of SBO, respectively. Patients who do not demonstrate severe clinical or imaging findings are typically treated with conservative approaches. Patients with clinical signs of sepsis or physical findings of peritonitis are often instantly transferred to the operating room without supplementary imaging assessment. However, in cases where symptoms are non-specific, or the physical examination is challenging, such as in cases with loss of consciousness, the diagnosis can be complicated. This paper discusses the key findings detectable on Computed tomography (CT), which are vital for the emergent triage, proper treatment, and decision making in patients with speculated SBO.

METHOD

Narrative review of the literature.

RESULTS AND CONCLUSION

CT plays a key role in emergent triage, proper treatment, and decision making. It provides high sensitivity, specificity, and accuracy in the detection of early-stage obstruction and acute intestinal vascular compromise. It can also differentiate between various etiologies of this entity which is considered an important criterion in the triage of patients into surgical vs. non-surgical treatment. There are multiple CT findings, such as mesenteric edema, lack of the small-bowel feces, bowel wall thickening, fat stranding in the mesentery, and intraperitoneal fluid, which are predictive of urgent surgical exploration.

Imaging Modalities for Evaluation of Intestinal Obstruction

It is essential for the colon and rectal surgeon to understand the evaluation and management of patients with both small and large bowel obstructions. Computed tomography is usually the most appropriate and accurate diagnostic imaging modality for most suspected bowel obstructions. Additional commonly used imaging modalities include plain radiographs and contrast imaging/fluoroscopy, while less commonly utilized imaging modalities include ultrasonography and magnetic resonance imaging. Regardless of the imaging modality used, interpretation of imaging should involve a systematic, methodological approach to ensure diagnostic accuracy.

Adhesive Small Bowel Obstruction: Predictive Radiology to Improve Patient Management

Adhesive small bowel obstruction (SBO) remains one of the leading causes of emergency room visits and is still associated with high morbidity and mortality rates. Because the management of adhesive SBO has shifted from immediate surgery to nonoperative treatment in the absence of ischemia, it is crucial to rapidly detect or predict strangulation, which requires emergent surgery. CT is now established as the best imaging technique for the initial assessment of patients suspected of having adhesive SBO. CT helps confirm the diagnosis of mechanical SBO, locate the site of obstruction, establish the cause, and detect complications. This article is a review of the role of imaging in answering specific questions to help predict the management needs of each individual patient. It includes (a) an update on the best CT signs for predicting ischemia and a need for bowel resection; (b) a discussion of the CT features that help differentiate open-loop from closed-loop obstruction and a single adhesive band from matted adhesions and how these differences can influence the management; and (c) a review of the main CT predictors of the success or failure of nonoperative management in adhesive SBO.

ACR Appropriateness Criteria® Suspected Small-Bowel Obstruction

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. 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.

Detection of Transition Zone in Bowel Obstruction via Curved Multiplanar Reformations with Multidetector Computed Tomography

Objective

We conducted this study to determine the added value of curved multiplanar reformations (CMPR) and multiplanar reformations (MPR) of multidetector computed tomography (MDCT) scan in the visualization and localization of the zone of transition in patients with intestinal obstruction.

Materials and methods

A total of 100 patients with suspected bowel obstruction were evaluated in a retrospective cross-sectional study from September 2016 to September 2018 at Dr. Ziauddin University Hospital, Clifton Campus. All patients underwent multidetector computed tomography (CT) scans with oral and intravenous contrast before surgical exploration. CMPR and MPR were acquired at the time of examination in each patient in addition to routine axial images. The CT scans were analyzed by two independent, experienced radiologists skilled at detecting the zones of transition in patients with bowel obstruction using the axial images alone, followed by axial images along with MPR, and then MPR plus CMPR. Patient data were masked to the radiologists. The CT scan findings were compared with surgical findings to determine the accuracy of CMPR in detecting the zone of transition between distended and collapsed bowel loops. The added CMPR showed high accuracy in the diagnosis of intestinal obstruction with a remarkable advantage over the conventional axial images. Data analysis was done on IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY). Cohen’s kappa statistics were obtained to show the measure of agreement between the two readers. McNemar’s test was also applied to determine the homogeneity.

Results

Two radiologists, one with two years of experience and the other with five years of experience were 80% and 81% accurate, respectively, in identifying the zones of transition using axial images alone. Using axial images plus MPR, their accuracy was 88% and 92%, respectively. Using MPR plus CMPR, their accuracy was 96% and 98%, respectively. The accuracy of MPR plus CMPR views was significantly increased when compared to the accuracy using axial images alone. CT findings were compared to surgical findings in terms of diagnostic performance. The kappa value of 0.6 indicates moderate association and substantial agreement between two radiologists. McNemar’s test showed homogeneity in the number of valid cases.

Conclusion

CMPR is an important and accurate technique for evaluating intestinal obstruction in addition to MPR as it helps in better localization of the zone of transition and in determining the cause of obstruction. This insight provides guidance for the appropriate treatment.

Optimized protocol of multiple post-processing techniques improves diagnostic accuracy of multidetector computed tomography in assessment of small bowel obstruction compared with conventional axial and coronal reformations

BACKGROUND

Axial and coronal reformations have been a widely used image post-processing protocol for the ordinary multidetector computed tomography (MDCT) examination of patients with small bowel obstruction (SBO) or other abdominal diseases. The diagnostic accuracy of MDCT for assessing SBO is expected to be further improved through the use of multiple post-processing techniques.

AIM

To systemically evaluate the diagnostic accuracy and efficiency of an optimized protocol using multiple post-processing techniques for MDCT assessment of SBO and secondary bowel ischemia.

METHODS

This retrospective cross-sectional study included 106 patients with clinically suspected SBO. Two readers applied three protocols to image post-processing and interpretation of patients' MDCT volume data. We compared the three protocols based on time spent, number of images, diagnostic self-confidence, agreement, detection rate, and accuracy of detection of SBO and secondary bowel ischemia.

RESULTS

Protocol 2 resulted in more time spent and number of images than protocols 1 and 3 (P < 0.01), but the results of the two readers using the same protocol were not different (P > 0.05). Using protocol 3, both readers added multiple post-processing techniques at frequencies of 29.2% and 34.9%, respectively, for obstruction cause, and 32.1% and 30.2%, respectively, for secondary bowel ischemia. Protocols 2 and 3 had higher total detection rates of obstruction cause and secondary bowel ischemia than protocol 1 (P < 0.01), but no difference was detected between protocols 2 and 3 (P > 0.05). The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of protocols 2 and 3 were superior to those of protocol 1 for evaluating obstruction cause and secondary bowel ischemia.

CONCLUSION

Our optimized protocol of multiple post-processing techniques can both guarantee efficiency and improve diagnostic accuracy of MDCT for assessing SBO and secondary bowel ischemia.

Emergency Medicine Evaluation and Management of Small Bowel Obstruction: Evidence-Based Recommendations

BACKGROUND

Small bowel obstruction (SBO) is a commonly diagnosed disease in the emergency department (ED). Recent literature has evaluated the ED investigation and management of SBO.

OBJECTIVE

This review evaluates the ED investigation and management of adult SBO based on the current literature.

DISCUSSION

SBO is most commonly due to occlusion of the small intestine, resulting in fluid and gas accumulation. This may progress to mucosal ischemia, necrosis, and perforation. A variety of etiologies are present, but in adults, adhesions are the most common cause. Several classification systems are present. However, the most important distinction is complete vs. partial and complicated vs. simple obstruction, as complete complicated SBO more commonly requires surgical intervention. History and physical examination can vary, but the most reliable findings include prior abdominal surgery, history of constipation, abdominal distension, and abnormal bowel sounds. Signs of strangulation include fever, hypotension, diffuse abdominal pain, peritonitis, and several others. Diagnosis typically requires imaging, and though plain radiographs are often ordered, they cannot exclude the diagnosis. Computed tomography and ultrasound are reliable diagnostic methods. Management includes intravenous fluid resuscitation, analgesia, and determining need for operative vs. nonoperative therapy. Nasogastric tube is useful for patients with significant distension and vomiting by removing contents proximal to the site of obstruction. Surgery is needed for strangulation and those that fail nonoperative therapy. Surgical service evaluation and admission are recommended.

CONCLUSION

SBO is a common reason for admission from the ED. Knowledge of recent literature can optimize diagnosis and management.

Small-Bowel Obstruction Secondary to Ileal Trichobezoar in a Patient with Rapunzel Syndrome

Bezoars are conglomerations of undigested foreign material retained in the gastrointestinal tract. Trichobezoar is a compact conglomeration of swallowed hair and constitutes less than 6% of all bezoars. Their most frequent location is in the stomach but they may extend through the pylorus into the small bowel. This condition is known as Rapunzel syndrome. Many patients may remain asymptomatic or present a mild form of the disease characterized by abdominal pain, early satiety, nausea, and vomiting. Complications may manifest as gastric outlet obstruction or bleeding, and intestinal obstruction. A 15-year-old female patient presented with clinical findings of intestinal obstruction. The patient suffered from depressive and anxiety disorders and trichotillomania, although trichophagy could not be assured. Alopecia circumscripta and irregular hair length on the scalp were identified. A computed tomography (CT) scan showed two images highly suggestive of trichobezoars, one in the stomach and the second one causing obstruction at the ileocecal valve. At laparotomy, both a mobile gastric trichobezoar with a tail extending to the duodenum and a trichobezoar causing obstruction at the ileocecal valve were removed. The postoperative course was uneventful. The passage of a detached trichobezoar fragment in a patient with Rapunzel syndrome may cause intestinal obstruction. CT is the preferred image modality for the evaluation of suspected trichobezoars in order to characterize their size and locations, the presence and level of obstruction, and complications such as ischemia or perforation. A case of small-bowel obstruction secondary to ileal trichobezoar in a patient with Rapunzel syndrome is herein reported.

MDCT findings in small bowel obstruction: implications of the cause and presence of complications on treatment decisions

Small bowel obstruction (SBO) accounts for a considerable proportion of emergency room visits, inpatient admissions, and surgical interventions in the United States. Multi-detector computed tomography (MDCT) plays a key role in imaging patients presenting with acute symptoms suggestive of SBO, which helps in establishing the diagnosis, elucidating the cause of obstruction, and detecting complications, such as ischemia or frank bowel necrosis and perforation. Recently, management of patients with SBO has shifted toward a more conservative approach with supportive care and nasogastric tube decompression, as the obstruction in many cases can resolve spontaneously without the need for operative intervention. However, management decisions in SBO remain notoriously difficult, relying on a combination of clinical, laboratory, and imaging factors to help stratify patients into conservative or surgical treatment. Imaging is often an important factor assisting in the decision-making process since traditional clinical signs of vascular compromise, such as acidosis, fever, leukocytosis, and tachycardia are often unreliable in predicting the need for operative intervention. Thus, it is critically important for radiologists to identify imaging features that suggest or indicated high likelihood of bowel vascular compromise in order to help optimize management prior to the development of bowel ischemia and eventually necrosis. By excluding signs of potentially ischemic or necrotic bowel on MDCT, patients may be spared unnecessary surgery, thus decreasing postsurgical complications and averting potential increase for the risk of future SBO and repeated surgery. Conversely, if imaging features indicate potential vascular compromise of the bowel wall that may lead to bowel ischemia, urgent surgical intervention may prevent progression to bowel necrosis and subsequent perforation.

Diagnostic performance of MDCT in identifying closed loop small bowel obstruction

PURPOSE

To assess the diagnostic performance of MDCT in the diagnosis of closed loop small bowel obstruction.

MATERIALS AND METHODS

One hundred fifty patients with CT reports including "small bowel obstruction (SBO)" between 1/30/2011 and 12/4/2012 were included (65 men, 85 women, mean age 63 years). CT examinations were independently and blindly reviewed by five radiologists to determine the presence of closed loop obstruction (CL-SBO) and to assess findings of bowel ischemia. Clinical records were reviewed to determine management and operative findings. Using operative findings as a gold standard, reader agreement for the diagnosis of and the CT findings associated with CLO was analyzed using Pearson's correlation (r). Positive predictive value (PPV) and negative predictive value for the diagnosis of CL-SBO and CT signs of bowel ischemia were analyzed.

RESULTS

Eighty-eight of 150 patients underwent operative intervention for SBO and 24/88 were considered CL-SBO operatively. Average reader sensitivity and specificity for CL-SBO was 53 % (95 % CI 44-63 %) and 83 % (95 % CI 79-87 %). Reader agreement on CL-SBO was poor to moderate (K = 0.39-0.63). Reader agreement for CT signs of bowel ischemia resulting in a diagnosis of CL-SBO was weak (r = 0.19-0.32).

CONCLUSION

The CT diagnosis of CL-SBO is complex and associated imaging findings have variable sensitivity for predicting a closed loop operative diagnosis. CT can be helpful in excluding a closed loop component in patients with SBO.

Prediction of Small Bowel Obstruction Caused by Bezoars Using Risk Factor Categories on Multidetector Computed Tomographic Findings

Objectives. The aim of this study was to detect factors associated with small bowel obstruction (SBO) caused by bezoars on multidetector computed tomographic findings. Methods. We retrospectively reviewed 61 patients who had bezoars in the small bowels on MDCT. The patients were divided into SBO patients group and non-SBO patients group. The mean values of the diameter, volume, and CT attenuation as well as location and characteristics of the bezoars were compared between the two groups. Multivariate analysis was performed to determine factors associated with SBO. Results. There were 32 patients (52.5%) in the SBO group and 29 patients (47.5%) in the non-SBO group. The bezoars in the SBO group had greater values of each mean diameter and mean volume than those in the non-SBO group (3.2 ± 0.5 cm versus 1.6 ± 0.7 cm, P < 0.0001, 14.9 ± 6.4 cm(3) versus 2.5 ± 2.7 cm(3), P < 0.0001, resp.) and had a lower CT attenuation than the non-SBO group (55.5 ± 23.4 versus 173.0 ± 68.0, P < 0.0001). The SBO group had higher prevalence of phytobezoar appearance (75.0% versus 10.3%, P < 0.0001). Major diameters of bezoar and phytobezoar were significant independent risk factors associated with SBO (odds ratio = 36.09, 8.26, resp., and P = 0.0004, 0.044, resp.). Conclusions. Major diameter of bezoar or phytobezoar is a potential risk factor associated with SBO.

COMPARISON OF COMPUTED TOMOGRAPHY AND ABDOMINAL RADIOGRAPHY FOR DETECTION OF CANINE MECHANICAL INTESTINAL OBSTRUCTION

Vomiting, often caused by mechanical intestinal obstruction, is common in dogs. Equivocal radiographic signs often necessitate repeat radiographs or additional imaging procedures. For our prospective, case-controlled, accuracy study, we hypothesized the following: (1) using computed tomography (CT), radiologists will be more sensitive and specific for detecting mechanical intestinal obstruction and recommending surgery compared to using radiographs; and (2) using measurements, radiologists will be more sensitive and specific using radiographs or CT for detecting mechanical intestinal obstruction and recommending surgery. Twenty dogs had abdominal radiographs and abdominal CT. Seventeen dogs had abdominal surgery and three dogs were not obstructed based on clinical follow-up. Confidence levels (five-point scale) of three experienced radiologists for mechanical intestinal obstruction and recommending surgery were recorded before and after making selected measurements. Eight dogs had surgically confirmed mechanical intestinal obstruction, and 12 dogs did not have obstruction. For detecting mechanical intestinal obstruction, CT was more sensitive (95.8% vs. 79.2%) and specific (80.6% vs. 69.4%) compared to radiographs, but the difference was not statistically significant. For recommending surgery, radiography was more sensitive (91.7% vs. 83.3%) and specific (83.3% vs. 72.2%) than using CT, but differences were not statistically significant. We reported objective CT measurements for predicting small mechanical intestinal obstruction. By incorporating these objective data, the diagnosis of mechanical intestinal obstruction changed in five of 120 instances (radiographs and CT). In no instance (0/120), did the objective data change the recommendation for surgery. Using CT or abdominal radiographs for the detection of canine mechanical intestinal obstruction is sensitive and specific when evaluated by experienced veterinary radiologists.

Review of small-bowel obstruction: the diagnosis and when to worry

This is a review of small-bowel obstruction written primarily for residents. The review focuses on radiography and computed tomography (CT) for diagnosing small-bowel obstruction and CT for determining complications. (©) RSNA, 2015.

Added Value of Using a CT Coronal Reformation to Diagnose Adnexal Torsion

Objective

To evaluate the increased value of using coronal reformation of a transverse computed tomography (CT) scan for detecting adnexal torsion.

Materials and Methods

This study included 106 woman suspected of having adnexal torsion who underwent CT with coronal reformations and subsequent surgical exploration. Two readers independently recorded the CT findings, such as the thickening of a fallopian tube, twisting of the adnexal pedicle, eccentric smooth wall thickening of the torsed adnexal mass, eccentric septal thickening of the torsed adnexal mass, eccentric poor enhancement of the torsed adnexal mass, uterine deviation to the twisted side, ascites or infiltration of pelvic fat, and the overall impression of adnexal torsion with a transverse scan alone or combined with coronal reformation and a transverse scan. The areas under the receiver operating characteristic curves (AUCs), sensitivity, specificity, and positive predictive value were used to compare diagnostic performance.

Results

Fifty-two patients were confirmed to have adnexal torsion. The addition of coronal reformations to the transverse scan improved AUCs for readers 1 and 2 from 0.74 and 0.75 to 0.92 and 0.87, respectively, for detecting adnexal torsion (p < 0.001 and p = 0.004, respectively). Sensitivity of CT for detecting twisting of the adnexal pedicle increased significantly for readers 1 and 2 from 0.27 and 0.29 with a transverse scan alone to 0.79 and 0.77 with a combined coronal reformation and a transverse scan, respectively (p < 0.001 and p < 0.001, respectively).

Conclusion

Use of a coronal reformation with transverse CT images improves detection of adnexal torsion.

Visual search in abdominopelvic CT interpretation: accuracy and time efficiency between coronal MPR and axial images

RATIONALE AND OBJECTIVES

The objective of this study was to compare reader accuracy and time efficiency between coronal reformats of abdominopelvic computed tomography (CT) and axial images, by means of a visual search task.

MATERIALS AND METHODS

In this experimental crossover study, a novel visual search task, containing targets placed on actual CT images, was constructed to assess reader performance on both planes. Six trials were shown to participants in each plane, at a fixed time of 0.5 seconds per slice. The task was presented to 43 junior doctors. On each trial, participants were assessed for accuracy and confidence in finding the target on a five-point scale. Statistical analysis was performed using the Wilcoxon signed rank test, and Fleiss kappa.

RESULTS

Coronal images took 40% less time to view overall. No significant difference was found in reader accuracy or reader confidence between the two planes. Interrater agreement was observed as fair, across a very large number of raters (43).

CONCLUSIONS

Target identification in the coronal plane is extremely similar to the axial plane on abdominopelvic CT in this study and offers a substantial time benefit. A perceptual limit to visual processing of CT images may contribute to this similarity. Greater use of coronal reformats in day-to-day practice could substantially improve radiologist workflow.

Performance of multidetector CT in the evaluation of the endometrium: Measurement of endometrial thickness and detection of disease

AIM

To evaluate the performance of multidetector computed tomography (MDCT) in the measurement of endometrial thickness and assessment for endometrial disease.

MATERIALS AND METHODS

Seventy-nine MDCT examinations, including sagittal reformats from isotropic data, were retrospectively evaluated for the presence of endometrial abnormality, endometrial thickness, and recommendation for transvaginal ultrasound (TVUS) after CT. The endometrial thickness was measured on sagittal images using two different methods, between the inner-to-inner hypoattenuating stripe, and when visible, between the outer-to-outer hyperattenuating stripe. TVUS performed within 48 h of CT in premenopausal and 1 month in postmenopausal patients served as reference standard. Interobserver agreement for endometrial thickness and abnormalities was assessed using concordance correlation (CC) and kappa statistics.

RESULTS

Interobserver agreement for endometrial thickness on sagittal CT images was excellent (CC 0.98), and highly accurate using the inner-to-inner measurement. For determination of abnormal thickening, the positive predictive value and negative predictive value were 67-100% and 99.5-100%. For detection of any endometrial abnormality, the positive predictive value and negative predictive value were 79-90% and 84-95%, respectively. False-negative missed abnormalities included small volume hydrometra, a polyp, and endometrial distortion by a fibroid.

CONCLUSION

At MDCT, sagittal reformatted images provide reliable endometrial measurement using the inner-to-inner hypoattenuating stripe and are accurately categorized as normal or abnormal thickness using the same numerical criteria as at sonography.

Iterative reconstruction improves image quality and preserves diagnostic accuracy in the setting of blunt solid organ injuries

This study aims to investigate the effect of iterative reconstruction (IR) on MDCT image quality and radiologists' ability to diagnose and grade blunt solid organ injuries. One hundred (100) patients without and 52 patients with solid organ injuries were scanned on a 64-slice MDCT scanner using reference 300 mAs, 120 kVp, and fixed 75 s delay. Raw data was reconstructed using filtered back projection (FBP) and three levels of iterative reconstruction (Philips iDose levels 2, 4, and 6). Four emergency radiologists, blinded to the reconstruction parameters and original interpretation, independently reviewed each case, assessed image quality, and assigned injury grades. Each reader was then asked to determine if they thought that IR was used and, if so, what level. There was no significant difference in diagnostic accuracy between FBP and the various IR levels or effect on the detection and grading of solid organ injuries (p > 0.8). Images reconstructed using iDose level 2 were judged to have the best overall image quality (p < 0.01). The radiologists had high sensitivity in detecting if IR was used (80 %, 95 % CI 76-84 %). IR performed comparably to FBP with no effect on radiologist ability to accurately detect and grade blunt solid organ injuries.

MDCT of Small Bowel Obstruction: How Reliable Are Oblique Reformatted Images in Localizing Point of Transition?

The goal of this study is to prospectively assess the additional value of oblique reformatted images for localizing POT, having surgery as a reference standard. Materials and Methods. 102 consecutive patients with suspected small bowel obstruction (SBO) underwent 64-slice multidetector row CT (MDCT) using surgical findings as reference standard. Two independent GI radiologists reviewed the CT scans to localize the exact POT by evaluating axial images (data set A) followed by axial, coronal, and oblique MPR images. CT findings were compared to surgical findings in terms of diagnostic performance. McNemar's test was used to detect any statistical difference in POT evaluation between datasets A and B. Kappa statistics were applied for measuring agreement between two readers. Results. There was a diagnostic improvement of 9.9% in the case of the less experienced radiologist in localizing POT by using oblique reformatted images. The more experienced radiologist showed diagnostic improvement by 12.9%.

Increased unenhanced bowel-wall attenuation at multidetector CT is highly specific of ischemia complicating small-bowel obstruction

PURPOSE

To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard.

MATERIALS AND METHODS

The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30-100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ(2) tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement.

RESULTS

In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308).

CONCLUSION

Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent.

CT findings of patients with small bowel obstruction due to bezoar: a descriptive study

PURPOSE. The aim of this study was to present the computed tomography (CT) findings of bezoars that cause obstruction in the small bowel and to emphasize that some CT findings can be considered specific to some bezoar types. MATERIALS AND METHODS. The records of 39 patients who underwent preoperative abdominal CT and subsequent operation with a diagnosis of intestinal obstruction due to bezoars were retrospectively analyzed. RESULTS. In total, 56 bezoars were surgically removed from 39 patients. Bezoars were most commonly located in the jejunum (n = 26/56, 46.4%). Sixteen (41.0%) patients had multiple bezoar locations in the gastrointestinal tract. Common CT findings in all patients were a mottled gas pattern and a focal ovoid or round intraluminal mass with regular margins and a heterogeneous internal structure. Furthermore, some CT findings were determined to be specific to bezoars caused by persimmons. CONCLUSIONS. Preoperative CT is valuable in patients admitted with signs of intestinal obstruction in geographic regions with a high bezoar prevalence. We believe that the correct diagnosis of bezoars and the identification of their number and location provide a great advantage for all physicians and surgeons. In addition, some types of bezoars have unique CT findings, and we believe that these findings may help to establish a diagnosis.

Evaluation and management of small-bowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline

BACKGROUND

Small-bowel obstruction (SBO) represents as many as 16% of surgical admissions and more than 300,000 operations annually in the United States. The optimal strategies for the diagnosis and management of SBO continue to evolve secondary to advances in imaging techniques, critical care, and surgical techniques. This updated systematic literature review was developed by the Eastern Association for the Surgery of Trauma to provide up-to-date evidence-based recommendations for SBO.

METHODS

A search of the National Library of Medicine MEDLINE database was performed using PubMed interface for articles published from 2007 to 2011.

RESULTS

The search identified 53 new articles that were then combined with the 131 studies previously reviewed by the 2007 guidelines. The updated guidelines were then presented at the 2012 annual EAST meeting.

CONCLUSION

Level I evidence now exists to recommend the use of computed tomographic scan, especially multidetector computed tomography with multiplanar reconstructions, in the evaluation of patients with SBO because it can provide incremental clinically relevant information over plains films that may lead to changes in management. Patients with evidence of generalized peritonitis, other evidence of clinical deterioration, such as fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain, or patients with evidence of ischemia on imaging should undergo timely exploration. The remainder of patients can safely undergo initial nonoperative management for both partial and complete SBO. Water-soluble contrast studies should be considered in patients who do not clinically resolve after 48 to 72 hours for both diagnostic and potential therapeutic purposes. Laparoscopic treatment of SBO has been demonstrated to be a viable alternative to laparotomy in selected cases.

CT diagnosis of the nature of bowel obstruction: morphological evaluation of the transition point

PURPOSE

This study evaluated transition-point morphology for defining the nature of bowel obstructions.

MATERIALS AND METHODS

Computed tomography (CT) examinations of 95 patients affected by severe bowel obstruction (23 neoplastic, 72 nonneoplastic) were retrospectively reviewed.

RESULTS

The transition point was identified in 89 patients (94%); morphology in relation to the proximal loop was concave in 64 cases (68%), linear in five (5%) and convex in 20 (21%). Concave transition-point morphology was indicative of a nonneoplastic condition, with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy values of 89%, 100%, 100%, 74% and 92%, respectively. A linear shape had almost identical incidence among neoplastic (60%) and nonneoplastic (40%) conditions. A convex appearance correlated with neoplastic disease with sensitivity, specificity, PPV, NPV and diagnostic accuracy values of 87%, 100%, 100%, 96% and 97%, respectively.

CONCLUSIONS

In the case of bowel obstruction, transitionpoint detection indicates the obstruction site, whereas its morphological evaluation can contribute to defining the nature of the obstruction. A concave morphology indicates a nonneoplastic condition with a high probability; a convex morphology correlates with neoplastic disease, whereas linearity is not significant.

CT findings of misleading features of colonic diverticulitis

Colonic diverticulitis (CD) is a common entity whose diagnosis is particularly based on computed tomography (CT) examination, which is the imaging technique of choice. However, unusual CT findings of CD may lead to several difficulties and potential pitfalls: due to technical errors in the management of the CT examination, due to the anatomical situation of the diseased colon, in diagnosing unusual complications that may concern the gastrointestinal tract, intra- and retroperitoneal viscera or the abdominal wall, and in differentiating CD from other abdominal inflammatory and infectious conditions or colonic cancer. The aim of this work is to delineate the pitfalls of CT imaging and illustrate misleading CT features in patients with suspected CD.

Value of "protruding lips" sign in malignant bowel obstructions

OBJECTIVE

This study aims to evaluate the diagnostic accuracy of a new CT sign in order to define or exclude a malignant aetiology of bowel obstruction.

MATERIALS AND METHODS

CT scans of 137 patients affected by bowel obstruction were reviewed. Colonic obstruction occurred in 47 (34%) cases, small bowel obstruction in 90 (66%). Neoplastic aetiology was found in 42 cases (31%), while in the remaining 95 (69%) obstruction was caused by non-neoplastic conditions. Definitive diagnosis was surgically confirmed in all patients. CT images were evaluated searching for bowel obstruction's signs and for the presence of the "protruding lips" sign on the proximal surface of stenosis, which is represented by the evidence of a protrusion within the dilated loop.

RESULTS

The sign was found in 31 (23%) cases, all of neoplastic origin. When malignant obstruction was diagnosed, sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy values of the described sign were 74%, 100%, 100%, 90% and 92%, respectively.

CONCLUSIONS

The "protruding lips" sign represents an alteration to be searched when bowel obstruction is diagnosed by CT examination. Its evidence correlates to a malignant condition with a 100% probability and when it is not found, the probability of a non-neoplastic condition is 90%.

Are multiplanar reconstructions necessary in routine body computed tomography practice?: what is the published evidence?

OBJECTIVE

During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume.

CONCLUSIONS

Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

Influence of body habitus and use of oral contrast on reader confidence in patients with suspected acute appendicitis using 64 MDCT

The purpose of this study is to evaluate how body habitus affects reader confidence in diagnosing acute appendicitis and appendiceal visualization using 64 MDCT technology with and without oral contrast. We conducted a HIPAA compliant, IRB approved study of adult patients presenting to the Emergency Department with nontraumatic abdominal pain. Subjects were randomized to two groups: 64 MDCT scans performed with oral and intravenous contrast or scans performed solely with intravenous contrast. Three radiologists established their confidence about the presence of appendicitis as well as recording whether the appendix was visualized. Reader confidence in diagnosing acute appendicitis was compared between the two groups for the three readers. The impact of patient BMI and estimated intra-abdominal fat on reader confidence in diagnosing appendicitis was determined. Finally, a comparison of the effect of BMI and intra-abdominal fat on appendiceal visualization between the two groups was carried out. Three hundred three patients were enrolled in this study. There was a statistically significant difference in confidence based on BMI for reader 2, group 1 in diagnosing appendicitis. No further statistically significant differences in reader confidence for diagnosing appendicitis based on BMI or intra-abdominal fat were identified. There was no influence of BMI or intra-abdominal fat on appendiceal visualization. Increasing BMI was seen to improve reader confidence for one of three readers in patients that received both oral and intravenous contrast. No further effects of BMI or intra-abdominal fat on confidence in diagnosing or excluding appendicitis were seen. Neither BMI nor intra-abdominal fat were seen to influence appendiceal visualization.

Use of a Dedicated Server to Perform Coronal and Sagittal Reformations in Trauma Examinations

The purpose of this study was to evaluate the impact of implementing an automated process for generating coronal and sagittal reformatted images on radiologist workflow. When performing trauma-related CT examinations of the cervical, thoracic, and lumbar spine at our institution, technologists manually generate coronal and sagittal reconstructions at the scanner console and send these images to a picture archiving and communication system (PACS) for interpretation by radiologists and clinical viewing. Although certain PACS, thin-client three-dimensional systems, and CT scanners are capable of automatically generating reconstructed or reformatted images, the systems at our institution do not support this functionality. We have recently integrated a dedicated server that is capable of automatically generating multiplanar reformatted (MPR) images from source thin-section axial images and sending these images to PACS without requiring technologist input. This dedicated server was used to generate coronal and sagittal MPRs for trauma-related spine studies in parallel with technologist-generated coronal and sagittal reconstructions. When comparing the two methods, using the dedicated server to automatically generate reformations resulted in substantial time savings for the radiologist compared to technologist-generated reconstructions. Additionally, a survey of interpreting radiologists indicated that a significant majority preferred to view the automatically generated MPRs on PACS compared to the thin-client system, considered the image quality to be good or excellent, and believed that viewing MPRs increased diagnostic accuracy and confidence. It is expected that this automated process will significantly improve radiologist workflow with respect to image interpretation time and report turnaround time.

Taxonomy and imaging spectrum of small bowel obstruction after Roux-en-Y gastric bypass surgery

OBJECTIVE

For most patients with morbid obesity, bariatric surgery is the only effective method to achieve sustainable weight loss. Small bowel obstruction (SBO) after bariatric surgery is a major complication that affects postoperative course and management. Knowledge of the types of and imaging findings for SBO is essential to prompt diagnosis.

CONCLUSION

We discuss different types of SBO and a taxonomic schemata of bowel obstruction (ABC classification) and present a review of imaging findings that facilitates optimal patient management.

The relevance of transition zones on computed tomography in the management of small bowel obstruction

BACKGROUND

Frequently, radiologists emphasize radiographic transition zones (RTZs) on computed tomography (CT), which are areas of abrupt change from dilated to collapsed bowel, as pathognomonic for small-bowel obstruction (SBO) diagnosis and location. The relevance of RTZs to patient management remains unknown. The purpose of this study was to determine the surgical predictive value and intraoperative accuracy of RTZ.

METHODS

A retrospective review of 200 patients with SBO who underwent abdominal CT at a single institution from 2002 to 2007 was performed. Statistical analysis was conducted using an unpaired t test, a Chi-square test, and multivariate analysis.

RESULTS

Of the 200 patients with SBO, 150 (75%) had an RTZ. Seventy-five (38%) patients required operative intervention; 58 (39%) patients had RTZ and 17 (34%) patients did not have RTZ (P=NS). The presence of RTZ was not associated with increased probability of operative versus nonoperative management (odds ratio=1.19; 95% confidence interval [0.61-2.32]). The mean time to operative intervention was 3.6 days. Immediate operative intervention (<24 h) was equivalent in patients with versus without RTZ (57% vs 53%; P=NS) as was intervention for failed nonoperative management (43% vs 47%; P=NS). For patients who required operative intervention, RTZ correlated with intraoperative site of obstruction in only 31 (63%) patients.

CONCLUSION

The presence of RTZs does not increase the likelihood of operative intervention or identify patients who will fail nonoperative management. RTZ should, therefore, not be used as a major criterion influencing operative versus nonoperative management decisions in patients with SBO. For patients who required operative intervention, RTZ had a 63% correlation with intra-operative findings, which makes it a useful adjunct to pre-operative planning.

Improving the management of acute adhesive small bowel obstruction with CT-scan and water-soluble contrast medium: a prospective study

PURPOSE

Adhesive small bowel obstruction is usually managed nonoperatively, but there is still debate over the optimal duration of nonoperative management and the factors that predict failure of medical treatment. The aim of this study was to evaluate an algorithm using CT-scans and Gastrografin in the management of small bowel obstruction.

METHODS

In a prospective study, each patient admitted for small bowel obstruction underwent a physical examination, a plain film, and a CT-scan evaluation. Patients underwent emergency surgical exploration when bowel ischemia was suspected. Other patients received oral Gastrografin, and a second plain abdominal radiograph was done after 12 hours. In patients with clinical improvement, the nasogastric tube was removed and an immediate liquid diet was resumed. Other patients were referred for surgery.

RESULTS

In total, 118 patients with 123 episodes of small bowel obstruction were included. Thirty-six (29%) required immediate surgery because they presented clinical characteristics of bowel ischemia (36/36; 100%) or a defect in vascularization of the small bowel on CT-scan (5/36; 14%). The 87 remaining patients were managed nonoperatively, of which 28 deteriorated and were referred for surgery. The 59 other patients showed clinical improvement.

CONCLUSION

This study demonstrated the diagnostic role of Gastrografin(R) in discriminating between partial and complete small bowel obstruction. CT-scans were disappointing in their ability to predict the necessity of emergent laparotomies. We therefore recommend the use of Gastrografin(R) in adhesive small bowel obstruction patients who do not have clinical evidence of bowel ischemia. CT-scans should not be routinely performed in the decision-making process except when clinical history, physical examination, and plain film are not conclusive for small bowel obstruction diagnosis.