Diagnostic accuracy of low-dose CT compared with abdominal radiography in non-traumatic acute abdominal pain: prospective study and systematic review

Current abdominal X-rays practice in accident and emergency

INTRODUCTION

Previous literature reviews revealed that abdominal X-rays (AXR) performed for the accident and emergency department (A&E), had low sensitivity, high further imaging and non-alignment rate to the Royal College of Radiologists (RCR) guidelines. A study was performed to investigate the current practice with the aim of making recommendations to improve practice, which can reduce patients' radiation exposures, while can re-routing resources to other priorities.

METHODS

A study was performed in one of the UK's largest A&Es, in accordance with the RCR guidelines. All the AXR requests from A&E, regardless of the patient's age, within a 28-day period, were retrospectively assessed. Non-A&E patients and abandoned examinations due to uncooperative patients were excluded. The total number of AXR requests received by the A&E imaging department was 169, with 28/169 falling into the exclusion criteria.

RESULTS

Of the 141 included requests, five unjustified requests were correctly rejected. The remaining 136 requests were accepted and performed, though only 115/136 (84.6%) of these were justified. The most common justified and unjustified indications were obstruction and renal stones, respectively. Only 4% of reported AXR had pathological abnormalities, while 45/136 patients had further imaging.

CONCLUSIONS

The small proportion of significant findings echoed previous studies, suggesting an AXR overuse. Over 80% of non-compliant requests were performed, and awareness of the justification guidelines can be increased by clinical governance, posters, or an algorithm previously presented. The 32.4% further imaging rate recorded in this study, as opposed to the 73.7% reported in previous literature, merits attention.

IMPLICATIONS TO PRACTICE

Stopping the overuse of AXR can minimise the radiation dose received and relieve the mounting pressure in imaging and reporting, which can serve other patients who would benefit from the services otherwise.

Acute Colonic Diverticulitis

Acute colonic diverticulitis is a gastrointestinal condition that is frequently encountered by primary care and emergency department practitioners, hospitalists, surgeons, and gastroenterologists. Clinical presentation ranges from mild abdominal pain to peritonitis with sepsis. It is often diagnosed on the basis of clinical features alone, but imaging is necessary in more severe presentations to rule out such complications as abscess and perforation. Treatment depends on the severity of the presentation, the presence of complications, and underlying comorbid conditions. Medical and surgical treatment algorithms are evolving. This article provides an evidence-based, clinically relevant overview of the epidemiology, diagnosis, and treatment of acute diverticulitis.

Transfer learning framework for low-dose CT reconstruction based on marginal distribution adaptation in multiscale

BACKGROUND

With the increasing use of computed tomography (CT) in clinical practice, limiting CT radiation exposure to reduce potential cancer risks has become one of the important directions of medical imaging research. As the dose decreases, the reconstructed CT image will be severely degraded by projection noise.

PURPOSE

As an important method of image processing, supervised deep learning has been widely used in the restoration of low-dose CT (LDCT) in recent years. However, the normal-dose CT (NDCT) corresponding to a specific LDCT (it is regarded as the label of the LDCT, which is necessary for supervised learning) is very difficult to obtain so that the application of supervised learning methods in LDCT reconstruction is limited. It is necessary to construct a unsupervised deep learning framework for LDCT reconstruction that does not depend on paired LDCT-NDCT datasets.

METHODS

We presented an unsupervised learning framework for the transferring from the identity mapping to the low-dose reconstruction task, called marginal distribution adaptation in multiscale (MDAM). For NDCTs as source domain data, MDAM is an identity map with two parts: firstly, it establishes a dimensionality reduction mapping, which can obtain the same feature distribution from NDCTs and LDCTs; and then NDCTs is retrieved by reconstructing the image overview and details from the low-dimensional features. For the purpose of the feature transfer between source domain and target domain (LDCTs), we introduce the multiscale feature extraction in the MDAM, and then eliminate differences in probability distributions of these multiscale features between NDCTs and LDCTs through wavelet decomposition and domain adaptation learning.

RESULTS

Image quality evaluation metrics and subjective quality scores show that, as an unsupervised method, the performance of the MDAM approaches or even surpasses some state-of-the-art supervised methods. Especially, MDAM has been favorably evaluated in terms of noise suppression, structural preservation, and lesion detection.

CONCLUSIONS

We demonstrated that, the MDAM framework can reconstruct corresponding NDCTs from LDCTs with high accuracy, and without relying on any labeles. Moreover, it is more suitable for clinical application compared with supervised learning methods.

Effects of sex, age, size and location of perforation on the sensitivity of erect chest X-ray for gastroduodenal perforation

INTRODUCTION

This study aimed to evaluate the sensitivity of the erect chest X-ray for diagnosing subdiaphragmatic free air. Furthermore, we examined the effects of different parameters, including sex, age, size of perforation, and the location of perforation on the sensitivity of the erect CXR.

METHODS

This study included all patients with perforated peptic ulcer (107 cases) referred to the Shahid Rajaei hospital of Tonekabon from April 2015 to August 2020. The perforated peptic ulcer was confirmed by laparotomy, and the erect chest X-ray was performed as a preoperative procedure. The collected checklist was analyzed using the IBM SPSS Statistics V22.0 software.

RESULTS

Achieved results showed total sensitivity of 86% for the erect chest X-ray. The sensitivity of the erect CXR was calculated, 88.5% and 82.6% at males and females, respectively. However, the sensitivity for different age groups was about 86%. The larger perforations resulted in higher sensitivity. Furthermore, the erect chest X-ray sensitivity for duodenal perforations (92.5%) was significantly greater than the gastric perforations (75%).

CONCLUSION

Based on this study, the erect chest X-ray could be utilized as a preoperative procedure with total sensitivity of 86% for gastroduodenal perforations. Patients' age and sex have no significant impact on the sensitivity (P-value > 0.05). However, the size and location of perforation significantly influenced the sensitivity (P-value < 0.05). The results demonstrated that larger perforations and duodenal perforations lead to the higher erect CXR sensitivity.

IMPLICATIONS FOR PRACTICE

The erect chest X-ray is used as a routine procedure to detect subdiaphragmatic free air in gastroduodenal perforations. The effects of different factors such as age, sex, size of perforation, and the location of perforation on the sensitivity of the erect chest X-ray are discussed for the first time in this study.

[Acute Abdominal Pain in the Emergency Department]

Abdominal pain is a common leading symptom in emergency medicine. This symptom complex includes a variety of different causes, ranging from intra-abdominal to extra-abdominal and retroperitoneal pathologies, which can affect all age groups. Abdominal complaints can include diseases ranging from trivialities to life-threatening emergencies. The acute abdominal condition is an interdisciplinary emergency in which interdisciplinary teamwork is mandatory. A rapid initial assessment and risk stratification is necessary in order to detect critically ill patients with an acute need for intervention at an early stage and to provide them with a suitable emergency therapy. A structured approach can identify the most important differential diagnoses.

CT predictive model for torsion angle as a marker for risk of necrosis in patients with adnexal torsion

AIM

To assess the feasibility of preoperative computed tomography (CT) prediction of torsion angle for stratifying the risk of necrosis in patients with adnexal torsion.

MATERIALS AND METHODS

In this multicentre, retrospective study, 72 patients underwent preoperative CT and surgically verified adnexal torsion. Surgeons identified the torsion angle and adnexal necrosis requiring adnexectomy. The twisted angles were compared between conservative surgery group and salpingo-oophorectomy group. Variables included demographic, pathological and CT details. Logistic analysis was used to identify the indicators of twisted angle associated with high-risk necrosis.

RESULTS

The necrosis associated with adnexal torsion treated with adnexectomy was performed more often in patients with a torsion angle of ≥720° (odds ratio [OR]=7, 95% confidence interval [CI]: 1.314-37.295, p=0.023). The enlarged twisted pedicle (OR=14.592, 95% CI: 2.048-103.953, p=0.007) and pedicle haemorrhage (OR=5.612, 95% CI: 1.088-28.941, p=0.039) can predict a torsion angle of ≥720°, and area under the receiver operating characteristic (ROC) curve (AUC=0.758±0.058) was generated with the combined variables.

CONCLUSION

The risk of adnexal necrosis is high in patients with torsion angle of ≥720°. CT findings of enlarged twisted pedicle and pedicle haemorrhage can be used to predict torsion angle of ≥720° and can imply adnexal necrosis indirectly.

Low-dose CT for diagnosing intestinal obstruction and pneumoperitoneum; need for retakes and diagnostic accuracy

Background

One of the main concerns using low-dose (LD) CT for evaluation of patients with suspected intestinal obstruction or pneumoperitoneum is the potential need to make an additional standard-dose (SD) CT scan (retake) due to insufficient diagnostic accuracy of the LD CT.

Purpose

To determine the frequency of retakes and evaluate the diagnostic accuracy of LD CT for the assessment of intestinal obstruction and pneumoperitoneum.

Material and Methods

This retrospective study registered all LD CT scans over a one-year period at Aarhus University Hospital, Denmark in patients with suspected intestinal obstruction or perforation, comprising a total of 643 LD CT scans. A retake was defined as a SD CT scan of the abdomen and pelvis performed with or without intravenous contrast within 72 h after the initial LD CT due to either continued suspicion of intestinal obstruction or perforation or due to unclarified secondary findings. The sensitivity and specificity of LD CT for diagnosing intestinal obstruction and pneumoperitoneum compared to the discharge diagnoses of the scanned patients were determined.

Results

The frequency of retakes was 3%. The overall LD CT sensitivity and specificity for assessment of patients with suspected intestinal obstruction and pneumoperitoneum was 83% and 99%, respectively, but higher in certain subgroups.

Conclusions

LD CT led to few retakes and had a high diagnostic accuracy for diagnosing intestinal obstruction and pneumoperitoneum. Thus, LD CT can be recommended as the examination of choice in patients with suspected intestinal obstruction or perforation in order to reduce radiation dose.

Trends in emergent diverticular disease management: a nationwide cohort study from 2009 to 2018

BACKGROUND

Diverticular disease is a common disorder. Several guidelines report on its optimal management. The aim of this study was to describe the evolution of the prevalence of this disease, the treatment strategies, and the mortality rate on a national level.

METHODS

We conducted a retrospective study on prospective data using a nationwide database. All consecutive adult patients diagnosed with diverticular disease and admitted via the emergency department from 2009 to 2018 were included in the study. We performed a descriptive analysis for epidemiologic data, diagnosis, and treatment.

RESULTS

During the data collection period, 233,386 patients were included in the study. The number of admissions for emergent diverticular disease increased by 65.8%, from 16,754 in 2009 to 27,781 in 2018, for both uncomplicated and complicated diverticular disease. Among these patients, 19,350 (8.3%) were operated on. The rate of surgical treatment progressively decreased from 9.7% in 2009 to 7.6% in 2018. The three main interventions were Hartmann's procedure (HP, n = 9111, 47.1%), resection with primary anastomosis (RPA, n = 4335, 22.4%), and peritoneal lavage (PL, n = 4836, 25%). We observed a progressive annual increase in HPs (n = 716 in 2009 and n = 1055 in 2018) as well as a decline in PLs since 2015, while the number of RPAs remained stable.

CONCLUSIONS

Although admissions for emergent diverticular disease have increased during the study period, the rate of surgical treatment has decreased, suggesting an evolution toward more conservative management of this pathology.

Low-dose Computed Tomography (CT) for the Diagnosis of Congenital Heart Disease in Children: A Meta-analysis

BACKGROUND

Low dose CT has become a promising examination method for the diagnosis of Congenital heart disease (CHD) in children because it has a low radiation dose, but it has not been widely accepted as an alternative to standard-dose CT in clinical applications due to concerns about image quality. Therefore, we suggest that the diagnostic accuracy, image quality, and radiation dose of low-dose CT for CHD in children should be fully explored through a metaanalysis of existing studies.

METHODS

A comprehensive search was performed to identify relevant English and Chinese articles (from inception to May 2019). All selected studies concerned the diagnosis of CHD in children using low-dose CT. The accuracy of low-dose CT was determined by calculating pooled estimates of sensitivity, specificity, diagnostic odds ratio, and likelihood ratio. Pooling was conducted using a bivariate generalized linear mixed model. Forest plots and summary receiver operating characteristic (SROC) curves were generated.

RESULTS

Ten studies, accounting for 577 patients, met the eligibility criteria. The pooled sensitivity and specificity were 0.95 (95% confidence interval (CI) 0.92-0.97) and 1.00 (95% CI 1.00- 1.00), respectively. The pooled diagnostic odds ratio, positive likelihood ratio, and negative likelihood ratio of low-dose CT were 12705.53 (95% CI 5065.00-31871.73), 671.29 (95% CI 264.77- 1701.97), and 0.05 (95% CI 0.03-0.08), respectively. Additionally, the area under the SROC curve was 1.00 (95% CI 0.99-1.00), suggesting that low-dose CT is an excellent diagnostic tool for CHD in children.

CONCLUSION

Low-dose CT, especially with a prospective ECG-triggering mode, provides excellent imaging quality and high diagnostic accuracy for CHD in children.

Gastrointestinal Ultrasound (GIUS) in Intestinal Emergencies - An EFSUMB Position Paper

An interdisciplinary group of European experts summarizes the value of gastrointestinal ultrasound (GIUS) in the management of three time-critical causes of acute abdomen: bowel obstruction, gastrointestinal perforation and acute ischemic bowel disease. Based on an extensive literature review, statements for a targeted diagnostic strategy in these intestinal emergencies are presented. GIUS is best established in case of small bowel obstruction. Metanalyses and prospective studies showed a sensitivity and specificity comparable to that of computed tomography (CT) and superior to plain X-ray. GIUS may save time and radiation exposure and has the advantage of displaying bowel function directly. Gastrointestinal perforation is more challenging for less experienced investigators. Although GIUS in experienced hands has a relatively high sensitivity to establish a correct diagnosis, CT is the most sensitive method in this situation. The spectrum of intestinal ischemia ranges from self-limited ischemic colitis to fatal intestinal infarction. In acute arterial mesenteric ischemia, GIUS may provide information, but prompt CT angiography is the gold standard. On the other end of the spectrum, ischemic colitis shows typical ultrasound features that allow correct diagnosis. GIUS here has a diagnostic performance similar to CT and helps to differentiate mild from severe ischemic colitis.

Hybrid and Model-Based Iterative Reconstruction Influences the Volumetry of Visceral and Subcutaneous Adipose Tissue on Ultra-Low-Dose CT

OBJECTIVE

The aim of this study was to compare three different reconstruction algorithms for the volumetry of the visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) on ultra-low-dose computed tomography (CT) images.

METHODS

Thirty-seven male patients underwent ultra-low-dose CT at the level of the fourth lumbar vertebra (22.5 mm in z-axis). The acquisitions were reconstructed in 5-mm slices with 50% overlap using filtered back projection (FBP), hybrid iterative reconstruction (HIR), and iterative model-based reconstruction (IMR) techniques. The volume of VAT and SAT was measured using an interactive seed-growing segmentation and by thresholding (-30 to -190 HU).

RESULTS

The volume of SAT measured by the interactive method was smaller in FBP compared with both HIR (P = 0.0011) and IMR (P = 0.0034), and the volume of VAT was greater in IMR compared with HIR (P = 0.0253) or FBP (P = 0.0065). Using the thresholding method, IMR volumes of VAT were greater compared with HIR (P < 0.0001), and volumes of SAT were greater compared with both HIR and FBP (both P ≤ 0.0001). The VAT to SAT ratio was greater in IMR compared with HIR or FBP (both P < 0.0001).

CONCLUSIONS

There are significant differences among FBP, HIR, and IMR in the volumetry of SAT and VAT, their ratios, and attenuation measured on ultra-low-dose images.

Highly reduced-dose CT of the lumbar spine in a human cadaver model

Purpose

Feasibility of a highly reduced-dose lumbar spine CT protocol using iterative reconstruction (IR) in a human cadaver model.

Materials and methods

The lumbar spine of 20 human cadavers was repeatedly examined using three different reduced-dose protocols (RDCT) with decreasing reference tube current-exposure time products (RDCT-1: 50 mAs; RDCT-2: 30 mAs; RDCT-3: 10 mAs) at a constant tube voltage of 140 kV. A clinical standard-dose protocol (SDCT) served as the reference (reference tube current–exposure time product: 70 mAs; tube voltage: 140 kV). Images were reconstructed using filtered back projection (FBP) and two increasing levels of IR: IRL4 and IRL6. A five-point scale was used by two observers to assess the diagnostic quality of anatomical structures (cortical and trabecular bone, intervertebral foramina, pedicles and intervertebral joints, spinous and transverse processes). Objective image noise (OIN) was measured. Results were interpreted using a linear mixed-effects regression model.

Results

RDCT-2 with IRL6 (1.2 ± 0.5mSv) was the lowest reduced-dose protocol which provided diagnostically acceptable and equivalent image quality compared to the SDCT (2.3 ± 1.1mSV) with FBP (p > 0.05). All RDCT protocols achieved a significant reduction of the mean (±SD) effective radiation doses (RDCT-1: 1.7±0.9mSv; RDCT-2: 1.2±0.5mSv; RDCT-3: 0.4±0.2mSv; p < 0.05) compared to SDCT. OIN was lower in all RDCT protocols with the application of IRL4 and IRL6, compared to the SDCT with FBP (p < 0.05).

Conclusion

Highly reduced-dose lumbar spine CT providing diagnostically acceptable image quality is feasible using IR in this cadaver model and may be transferred into a clinical setting.

Noncontrast MRI of acute abdominal pain caused by gastrointestinal lesions: indications, protocol, and image interpretation

Gastrointestinal tract lesions are major causes of acute abdominal pain. A rapid, accurate, and reliable diagnosis is required to manage patients. Magnetic resonance imaging (MRI) is a nonionizing modality that is beneficial for pregnant women, children, and young adults who are sensitive to ionizing radiation. For patients with renal impairment who are not accurately diagnosed with noncontrast computed tomography, noncontrast MRI can serve as an alternative diagnostic modality. MRI protocols used for acute abdominal pain are supposed to be optimized and prioritized to shorten scanning times. Single-shot T2-weighted and fat-suppressed T2-weighted imaging are important pulse sequences that are used to reveal pathology and inflammation in the gastrointestinal tract. Diffusion-weighted imaging clearly depicts inflammation and abscesses as hyperintense lesions. Most acute gastrointestinal tract lesions, including inflammation, ischemia, obstruction, and perforation, demonstrate bowel wall thickening. Bowel obstruction and adynamic ileus present bowel dilatation, and perforation and penetration show bowel wall defects. MRI can be used to reveal these pathological findings with some characteristics depending on their underlying pathophysiology. This review article discusses imaging modalities for acute abdominal pain, describes a noncontrast MRI protocol for acute abdominal pain caused by gastrointestinal tract lesions, and reviews MRI findings of acute gastrointestinal tract lesions.

ACR Appropriateness Criteria® Left Lower Quadrant Pain-Suspected Diverticulitis

This review summarizes the relevant literature regarding imaging of suspected diverticulitis as an etiology for left lower quadrant pain, and imaging of complications of acute diverticulitis. The most common cause of left lower quadrant pain in adults is acute sigmoid or descending colonic diverticulitis. Appropriate imaging triage for patients with suspected diverticulitis should address the differential diagnostic possibilities and what information is necessary to make a definitive management decision. Patients with diverticulitis may require surgery or interventional radiology procedures because of associated complications, including abscesses, fistulas, obstruction, or perforation. As a result, there has been a trend toward greater use of imaging to confirm the diagnosis of diverticulitis, evaluate the extent of disease, and detect complications before deciding on appropriate treatment. Additionally, in the era of bundled payments and minimizing health care costs, patients with acute diverticulitis are being managed on an outpatient basis and rapid diagnostic imaging at the time of initial symptoms helps to streamline and triage patients to the appropriate treatment pathway. 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.

[Acute abdomen : What does the nonradiologist expect from the radiologist?]

BACKGROUND

The acute abdomen is a life-threatening condition that demands urgent intervention. The required diagnostics should address the core problem and has to be chosen based upon the diagnostic strength of each diagnostic tool. Modalities with limited discriminating information regarding differential diagnosis have to be avoided. Expectancy and thoughts of the radiologist often differ from the view of the clinician in the emergency department.

OBJECTIVE

The decision about which diagnostic tools are valuable or unnecessary in the emergency setting is made from a surgeon's point of view. Close communication with radiologists is mandatory. We demonstrate the importance of clinical signs and symptoms and their correlation with helpful radiologic diagnostics.

CONCLUSION

The emergency radiologic diagnostic workup of acute abdomen has to be targeted and the radiologist must answer the questions in order to clarify whether an operation is indicated and to help define the surgical strategy. In emergency surgery as in acute abdomen extended diagnostics to reach a decision is a dangerous waste of time and must be avoided at all costs. Therefore close communication with the radiologist is crucial.

Ultra-low dose CT abdomen and pelvis for the detection of acute abdominal pathology in the emergency room: initial experience from an academic hospital

PURPOSE

The aim of this study is to describe our initial experience using ULDCT performed in the emergency room in the evaluation of acute abdominal pathology.

METHODS

Data from consecutive patients who underwent ULDCT for assessment of bowel obstruction, free intraperitoneal air, unexplained abdominal pain, or fecal loading for constipation between June 1, 2016 and March 31, 2017 was retrospectively assessed. Demographic data, radiation dose, CT findings, and clinical outcomes including performance of full dose contrast-enhanced CT (CECT), hospitalization, and surgery was collected. Concordance of ULDCT to CECT was calculated.

RESULTS

ULDCT was performed in 325 patients (188 women and 137 men; mean age, 65.1 years). ULDCT detected acute abdominal pathology in 134/325 (41.2%), and in 89/134 (66.4%) it was concordant with the clinical working diagnosis. The average dose length product (DLP) was 101.6 mGy cm (range 51.7-614; median, 82.6). CECT was performed in 44/325 patients (13.5%). In 7/44 (15.9%), CECT identified discordant findings which likely impacted management. A greater proportion of patients were admitted to hospital after a positive ULDCT 99/137 (72.3%), compared to those with a negative study 81/188 (43.1%); p < 0.0001(Chi², 27.30). Of those admitted to hospital, 11/99 (11.1%) with positive ULDCT had surgery compared to 1/81 (1.2%) with a negative ULDCT; p < 0.008 (Chi², 6.98).

CONCLUSION

With its high clinical yield and similar radiation dose, ULDCT appears as a suitable alternative to abdominal radiography for the detection of select acute abdominal pathology in the emergency room.

Exploring the evidence-practice gap in the use of plain radiography for acute abdominal pain and intestinal obstruction: a systematic review and meta-analysis

AIM

Previous studies, some dating back several decades, have recommended that the use of plain abdominal radiography should be curbed, particularly with the growth of more accurate imaging modalities. However, evidence from referral data suggests that plain abdominal radiography continues to be a commonly requested examination. The aim of this review was to explore the gap between evidence and practice by re-examining the evidence using a robust methodology, investigating the diagnostic accuracy of plain abdominal radiography.

METHODS

Studies were identified from electronic databases and reference lists. Eligible studies provided data as to the sensitivity and specificity of plain abdominal radiography for either acute abdominal pain (Group A) or suspected intestinal obstruction (Group B). Version 2 of the Quality Assessment of Diagnostic Accuracy Studies was used to assess the quality of studies and hierarchical summary receiver operator characteristic curves and coupled forest plots were generated.

RESULTS

Four studies evaluated plain abdominal radiography for acute abdominal pain (Group A) and 10 for suspected intestinal obstruction (Group B). Two studies investigated both presentations and were included in both groups. Methodological quality of studies was moderately high, though incorporation bias was a common limitation. Sensitivity for Group A studies ranged from 30 to 46%, with specificity from 75 to 88%. For Group B, the range of sensitivity was 48 to 96% and specificity from 50 to 100%.

CONCLUSION

The results suggest that use of plain abdominal radiography could be substantially reduced, particularly for patients with undifferentiated acute abdominal pain. While some guidelines exist, there is sound argument for clinical decision rules for abdominal imaging to inform evidence-based clinical decision-making and radiology referrals.

Double Obstruction Following Third Renal Transplant: A Case Report

As the field of transplant evolves and patients with chronic disease live longer, retransplant for end-stage renal disease becomes more common because kidney allografts have a limited lifespan. In renal retransplant, graft and patient survival is near equivalent to first-time transplant; however, these procedures present a unique surgical risk profile, especially third and subsequent transplants, which are reviewed in this manuscript. The risk of bowel obstruction in primary kidney transplant recipients is much lower than patients who have undergone laparotomy for second or third transplant because of the retroperitoneal location of the transplanted kidney. Internal hernia is an uncommon cause of small bowel obstruction, particularly after kidney transplant, and often diagnosis and intervention are delayed because of diagnostic uncertainty. We report a case of a 34-year-old man with acute kidney injury and bowel obstruction, whose final diagnosis was an internal hernia around the transplanted ureter of an intra-abdominally placed third renal transplant resulting in ureteric obstruction associated with small bowel obstruction-a case of double obstruction.

Image quality and pathology assessment in CT Urography: when is the low-dose series sufficient?

BACKGROUND

Our aim was to compare CT images from native, nephrographic and excretory phases using image quality criteria as well as the detection of positive pathological findings in CT Urography, to explore if the radiation burden to the younger group of patients or patients with negative outcomes can be reduced.

METHODS

This is a retrospective study of 40 patients who underwent a CT Urography examination on a 192-slice dual source scanner. Image quality was assessed for four specific renal image criteria from the European guidelines, together with pathological assessment in three categories: renal, other abdominal, and incidental findings without clinical significance. Each phase was assessed individually by three radiologists with varying experience using a graded scale. Certainty scores were derived based on the graded assessments. Statistical analysis was performed using visual grading regression (VGR). The limit for significance was set at p = 0.05.

RESULTS

For visual reproduction of the renal parenchyma and renal arteries, the image quality was judged better for the nephrogram phase (p < 0.001), whereas renal pelvis/calyces and proximal ureters were better reproduced in the excretory phase compared to the native phase (p < 0.001). Similarly, significantly higher certainty scores were obtained in the nephrogram phase for renal parenchyma and renal arteries, but in the excretory phase for renal pelvis/calyxes and proximal ureters. Assessment of pathology in the three categories showed no statistically significant differences between the three phases. Certainty scores for assessment of pathology, however, showed a significantly higher certainty for renal pathology when comparing the native phase to nephrogram and excretory phase and a significantly higher score for nephrographic phase but only for incidental findings.

CONCLUSION

Visualisation of renal anatomy was as expected with each post-contrast phase showing favourable scores compared to the native phase. No statistically significant differences in the assessment of pathology were found between the three phases. The low-dose CT (LDCT) seems to be sufficient in differentiating between normal and pathological examinations. To reduce the radiation burden in certain patient groups, the LDCT could be considered a suitable alternative as a first line imaging method. However, radiologists should be aware of its limitations.

Fully covered self-expanding metal stents for benign refractory pancreatic duct strictures in chronic pancreatitis

Background: Pancreatic duct (PD) stricture is a common adverse event in chronic pancreatitis (CP). Primary treatment for refractory PD strictures is endotherapy (ET), including the insertion of multiple plastic stents. In addition, fully covered self-expandable metal stents (FC-SEMSs) have also been successfully used. More long-term studies are necessary to clarify the complication rate and efficiency, however. Methods: This retrospective study was comprised of 17 patients with symptomatic CP and refractory fibrotic main pancreatic duct (MPD) stricture treated with FC-SEMSs between 2010-2018 at the Helsinki University Hospital. Treated strictures were located in the pancreatic head. Technical success was defined as the accurate positioning of the stent and resolution of the MPD stricture. Clinical success was defined as pain relief at the end of the follow-up. Results: In 12 patients (71%), stricture resolution was accomplished. Clinical success was achieved in 12 patients (71%). The median duration of stenting was 169 days (range 15-804). Ten patients (58.8%) underwent a follow-up of two years or more. Early complications (≤7 days) occurred in two patients (12%): one pancreatitis and one cholestasis. Late complications (≥7 days) included severe abdominal pain (n = 2, 12%), pancreatitis (n = 3, 18%), cholestasis (n = 1, 6%) and stent migration (n = 7, 35%). Significant differences in stricture resolution and pain improvement were evident in patients with stent migration compared to patients without stent migration [1(14.3%) vs. 11(84.6%), p = .004 and 2(28.6%) vs. 11(84.6%), p = .022]. Conclusion: FC-SEMS placement is a safe and potentially effective treatment for this challenging group of patients. However, stent migration appears to affect the clinical and technical outcome.

Overuse of plain abdominal radiography in emergency departments: a retrospective cohort study

BACKGROUND

Plain abdominal radiography (PAR) is routinely performed in emergency departments (EDs). This study aimed to (1) identify the indications for PAR in EDs and compare them against international guidelines, (2) uncover predictors of non-compliance with guidelines, and (3) describe the use of additional radiological examinations in EDs.

METHODS

Retrospective cohort study in the EDs of two hospitals in Geneva, Switzerland, including all adult patients who underwent PAR in the EDs. Indications were considered "appropriate" if complying with guidelines. Predictors of non-compliance were identified by univariate and multivariate analyses.

RESULTS

Over 1 year, PAR was performed in 1997 patients (2.2% of all admissions). Their mean age was 59.7 years, with 53.1% of female patients. The most common indications were constipation (30.8%), suspected ileus (28.9%), and abdominal pain (15.3%). According to the French and American guidelines, only 11.8% of the PARs were indicated, while 46.2% of them complied with the Australian and British guidelines. On multivariate analysis, admission to the private hospital ED (odds ratio [OR] 3.88, 95% CI 1.78-8.45), female gender (OR 1.95, 95% CI 1.46-2.59), and an age >  65 years (OR 2.41, 95%CI 1.74-3.32) were associated with a higher risk of inappropriate PAR. Additional radiological examinations were performed in 73.7% of patients.

CONCLUSIONS

Most indications for PAR did not comply with guidelines and elderly women appeared particularly at risk of being exposed to inappropriate examination. PAR did not prevent the need for additional examinations. Local guidelines should be developed, and initiatives should be implemented to reduce unnecessary PARs.

TRIAL REGISTRATION

ClinicalTrials.gov , identifier NCT02980081 .

Digital tomosynthesis for detection of ingested foreign objects in the emergency department: a case of razor blade ingestion

A 46-year-old schizophrenic male presented to the emergency department (ED) after deliberate ingestion of an undetermined number of open razor blades. Abdominal radiograph revealed one razor blade but raised suspicion of a second blade which was subsequently confirmed by digital tomosynthesis (DTS), seen as two razor blades superimposed upon each other placed at slightly different angles. A careful search was made during endoscopy and the two razor blades were retrieved from the stomach and duodenum, respectively. This case illustrates the use of digital tomosynthesis as a smart, timely, cost-effective, and low-dose alternative to conventional computed tomography (CT) that can be conveniently employed in the ED for foreign body localization.

The value of the erect abdominal radiograph for the diagnosis of mechanical bowel obstruction and paralytic ileus in adults presenting with acute abdominal pain

INTRODUCTION

There is discord on the value of the erect abdominal radiograph for diagnosing acute abdominal pathologies. The erect radiograph can be uncomfortable for patients in pain and increases patient radiation dose.

AIM

To determine if including the erect abdominal radiograph in plain abdominal radiography (PAR) improved diagnostic accuracy for identifying mechanical bowel obstruction and/or paralytic ileus in adults presenting with acute abdominal pain.

METHODS

PAR of 40 consecutive adults presenting with suspected bowel obstruction or paralytic ileus was retrospectively sampled and independently reviewed by two emergency department (ED) consultants and two radiology consultants for bowel obstruction and paralytic ileus across two sessions. In session 1, the assessors assessed the supine abdominal radiographs (PAR 1) and clinical details in a randomised order, and session 2, at least 6 weeks later, they assessed the supine and erect radiographs (PAR 2) and clinical details of the randomly re-ordered cases. Computed tomography was the reference standard. Pair-wise comparisons of receiver operating characteristic curves were calculated to assess for significant differences in participants' diagnostic accuracy using MedCalc 16.4.3.

RESULTS

Average sensitivity, specificity and area under the receiver operating characteristic curves (AUROC) were 69.7%, 61.0% and 0.642 for PAR 1, respectively, and 80.0%, 53.4% and 0.632 for PAR 2 respectively. For AUROC there were no significant differences (P > 0.05) between PAR 1 and PAR 2. Intra-rater and inter-rater agreement improved in PAR 2.

CONCLUSION

There was no statistically significant improvement in diagnostic accuracy when including the erect radiograph in PAR for the acute abdomen.

Feasibility of predictive model by clinical and laboratory parameters for risk stratification of geriatric abdominal pain

Background:

Assessment of geriatric patients presented with abdominal pain had been challenge for emergency physicians with the ageing population. A rapid, reproducible risk stratification model for the assessment of the need for admission for geriatric abdominal pain would be required to identify low-risk patients to be managed as out-patient basis.

Objective:

Assess the feasibility of risk stratification model to predict the need of hospital admission based on readily available bedside parameters in emergency departments.

Methods:

This is a multicenter retrospective cohort study in four emergency departments. Patients aged at least 65 who presented with chief complaint of abdominal pain within the previous 7 days of attendance as the chief complaint were included. Chart review was performed for the included patients. The primary outcome was defined as a composite of mortality, abdominal surgery or endoscopic treatment, and other inpatient treatments for abdominal diseases within 14 days, surrogating the need of hospital admission. Logistic regression was modeled to identify independent predictors. The diagnostic accuracy of the risk model was evaluated with the receiver operating characteristic curve and compared with the clinical gestalt of decision for hospital admission by the attending physician.

Results:

In total, 553 patients were included. Symptoms of upper gastrointestinal bleeding, non-ambulatory presenting status, pain duration, focal abdominal tenderness, hyperglycemia, leukocytosis, and elevated creatinine were independent predictors of the outcome. The area under the receiver operating characteristic curve of the predicted probabilities of the logistic model was 0.741. In keeping for a low-risk criterion to achieve more than 90% sensitivity, the predictive model would only achieve 18.2% specificity which was inferior to clinical gestalt for hospital admission (sensitivity 99.3%, specificity 44.3%).

Conclusion:

Risk stratification model by clinical assessment and laboratory markers alone were inadequate and inferior to clinical gestalt for identification of the group of patients requiring inpatient treatment.

Appropriateness of CT scans for patients with non-traumatic acute abdominal pain

OBJECTIVE

Acute abdominal pain is the most common reason for surgical admission. CT scans are increasingly used to aid early diagnosis. Excessive use of CT scans is associated with increased length of stay, healthcare costs and radiation. The aim of this study was to evaluate the appropriateness of CT scans for patients presenting with acute abdominal pain.

METHODS

We examined 100 consecutive patients presenting with new acute abdominal pain who underwent a CT scan. Clinical information available at the time the scan was ordered, was summarised and reviewed independently by five consultant general surgeons and five consultant radiologists.

RESULTS

A CT scan was judged to be not indicated in a median of 21% of cases (range 12-53%), more information was required in a median of 16% (0-41%) and in a median of 58% (37-88%) the CT scan was considered indicated. There was a good level of agreement (Cronbach's α 0.704) across the 10 experts.

CONCLUSION

These data suggest that a large proportion of CT scans for patients with acute abdominal pain are not clinically indicated or are being performed prior to adequate clinical work-up. Optimising CT scan requests for this patient group will improve use of healthcare resources. Advances in knowledge: Both radiologists and general surgeons agree that there is no indication for an abdominal CT scan for a patient presenting with acute abdominal pain in a median of 21% of the cases.

Evaluation of reduced-dose CT for acute non-traumatic abdominal pain: evaluation of diagnostic accuracy in comparison to standard-dose CT

Background Patients with acute non-traumatic abdominal pain often undergo abdominal computed tomography (CT). However, abdominal CT is associated with high radiation exposure. Purpose To evaluate diagnostic performance of a reduced-dose 100 kVp CT protocol with advanced modeled iterative reconstruction as compared to a linearly blended 120 kVp protocol for assessment of acute, non-traumatic abdominal pain. Material and Methods Two radiologists assessed 100 kVp and linearly blended 120 kVp series of 112 consecutive patients with acute non-traumatic pain (onset < 48 h) regarding image quality, noise, and artifacts on a five-point Likert scale. Both radiologists assessed both series for abdominal pathologies and for diagnostic confidence. Both 100 kVp and linearly blended 120 kVp series were quantitatively evaluated regarding radiation dose and image noise. Comparative statistics and diagnostic accuracy was calculated using receiver operating curve (ROC) statistics, with final clinical diagnosis/clinical follow-up as reference standard. Results Image quality was high for both series without detectable significant differences ( P = 0.157). Image noise and artifacts were rated low for both series but significantly higher for 100 kVp ( P ≤ 0.021). Diagnostic accuracy was high for both series (120 kVp: area under the curve [AUC] = 0.950, sensitivity = 0.958, specificity = 0.941; 100 kVp: AUC ≥ 0.910, sensitivity ≥ 0.937, specificity = 0.882; P ≥ 0.516) with almost perfect inter-rater agreement (Kappa = 0.939). Diagnostic confidence was high for both dose levels without significant differences (100 kVp 5, range 4-5; 120 kVp 5, range 3-5; P = 0.134). The 100 kVp series yielded 26.1% lower radiation dose compared with the 120 kVp series (5.72 ± 2.23 mSv versus 7.75 ± 3.02 mSv, P < 0.001). Image noise was significantly higher in reduced-dose CT (13.3 ± 2.4 HU versus 10.6 ± 2.1 HU; P < 0.001). Conclusion Reduced-dose abdominal CT using 100 kVp yields excellent image quality and high diagnostic accuracy for the assessment of acute non-traumatic abdominal pain.

Qualitative and quantitative radiological analysis of non-contrast CT is a strong indicator in patients with acute pyelonephritis

OBJECTIVE

To evaluate the performance of non-contrast computed tomography (CT) by reporting the difference in attenuation between normal and inflamed renal parenchyma in patients clinically diagnosed with acute pyelonephritis (APN).

MATERIAL AND METHODS

This is a retrospective study concerned with non-contrast CT evaluation of 74 patients, admitted with a clinical diagnosis of APN and failed to respond to 48h antibiotics treatment. Mean attenuation values in Hounsfield units (HU) were measured in the upper, middle and lower segments of the inflamed and the normal kidney of the same patient. Independent t-test was performed for statistical analysis. Image evaluation included receiver operating characteristic (ROC), visual grading characteristic (VGC) and kappa analyses.

RESULTS

The mean attenuation in the upper, middle and lower segments of the inflamed renal cortex was 32%, 25%, and 29% lower than the mean attenuation of the corresponding cortical segments of the contralateral normal kidney, respectively (p<0.01). The mean attenuation in the upper, middle, and lower segments of the inflamed renal medulla was 48%, 21%, and 30%, lower than the mean attenuation of the corresponding medullary segments of the contralateral normal kidney (p<0.02). The mean attenuation between the inflamed and non-inflamed renal cortex and medulla was 29% and 30% lower respectively (p<0.001). The AUCROC (p<0.001) analysis demonstrated significantly higher scores for pathology detection, irrespective of image quality, compared to clinical and laboratory results with an increased inter-reader agreement from poor to substantial.

CONCLUSION

Non-contrast CT showed a significant decrease in the parenchymal density of the kidney affected with APN in comparison to the contralateral normal kidney of the same patient. This can be incorporated in the diagnostic criteria of APN in NCCT in the emergency setting.

Comparison of Low- and Standard-Dose CT for the Diagnosis of Acute Appendicitis: A Meta-Analysis

OBJECTIVE

A meta-analysis was performed to compare low-dose CT and standard-dose CT in the diagnosis of acute appendicitis with an emphasis on diagnostic value.

MATERIALS AND METHODS

A systematic literature search for articles published through June 2016 was performed to identify studies that compared low-dose CT with standard-dose CT for the evaluation of patients suspected of having acute appendicitis. Summary estimates of sensitivity and specificity with 95% CIs were calculated using a bivariate random-effects model. Meta-regression was used to perform statistical comparisons of low-dose CT and standard-dose CT.

RESULTS

Of 154 studies, nine studies investigating a total of 2957 patients were included in this meta-analysis. The pooled sensitivity and specificity of low-dose CT were 96.25% (95% CI, 91.88-98.31%) and 93.22% (95% CI, 88.75-96.00%), respectively. The pooled sensitivity and specificity of standard-dose CT were 96.40% (95% CI, 93.55-98.02%) and 92.17% (95% CI, 88.24-94.86%), respectively. In a joint model estimation of meta-regression, lowand standard-dose CT did not show a statistically significant difference (p = 0.71). Both lowand standard-dose CT seem to be characterized by high positive and negative predictive values across a broad spectrum of pretest probabilities for acute appendicitis.

CONCLUSION

Low-dose CT is highly effective for the diagnosis of suspected appendicitis and can be considered a valid alternative first-line imaging test that reduces the potential risk of exposure to ionizing radiation.

Emergency assessment of patients with acute abdominal pain using low-dose CT with iterative reconstruction: a comparative study

OBJECTIVES

To determine if radiation dose delivered by contrast-enhanced CT (CECT) for acute abdominal pain can be reduced to the dose administered in abdominal radiography (<2.5 mSv) using low-dose CT (LDCT) with iterative reconstruction algorithms.

METHODS

One hundred and fifty-one consecutive patients requiring CECT for acute abdominal pain were included, and their body mass index (BMI) was calculated. CECT was immediately followed by LDCT. LDCT series was processed using 1) 40% iterative reconstruction algorithm blended with filtered back projection (LDCT-IR-FBP) and 2) model-based iterative reconstruction algorithm (LDCT-MBIR). LDCT-IR-FBP and LDCT-MBIR images were reviewed independently by two board-certified radiologists (Raters 1 and 2).

RESULTS

Abdominal pathology was revealed on CECT in 120 (79%) patients. In those with BMI <30, accuracies for correct diagnosis by Rater 1 with LDCT-IR-FBP and LDCT-MBIR, when compared to CECT, were 95.4% (104/109) and 99% (108/109), respectively, and 92.7% (101/109) and 100% (109/109) for Rater 2. In patients with BMI ≥30, accuracies with LDCT-IR-FBP and LDCT-MBIR were 88.1% (37/42) and 90.5% (38/42) for Rater 1 and 78.6% (33/42) and 92.9% (39/42) for Rater 2.

CONCLUSIONS

The radiation dose delivered by CT to non-obese patients with acute abdominal pain can be safely reduced to levels close to standard radiography using LDCT-MBIR.

KEY POINTS

• LDCT-MBIR (<2.5 mSv) can be used to assess acute abdominal pain. • LDCT-MBIR (<2.5 mSv) cannot safely assess acute abdominal pain in obese patients. • LDCT-IR-FBP (<2.5 mSv) cannot safely assess patients with acute abdominal pain.