Making computed tomography safer for patients with Crohn's disease.

Background and aims: Computed tomography (CT), often more accessible than magnetic resonance imaging (MRI), remains widely used though radiation exposure is an obvious disadvantage. We previously showed that modern CT technology can achieve over 70% reduction in radiation-dose without loss of accuracy. Here, we compare low- versus conventional-dose CT in patients with known Crohn's disease to assess clinical confidence and accuracy of the low-dose procedure in the semi-acute setting.Methods: A comparative study of low-dose CT with full iterative reconstruction (IR) versus conventional-dose CT was conducted in 50 consecutive outpatients with Crohn's disease. Clinicians were provided with the low-dose images and reports, whereas conventional-dose images were reviewed after 4 weeks.Results: The clinical question was adequately addressed with low-dose IR imaging in all cases. Complications of Crohn's were detected in 37/50 (74%) with no disagreement between low- and conventional-dose imaging. The effective radiation dose reduction was 76.5% (low-dose mean 2.15 mSv versus conventional-dose CT 6.99 mSv).Conclusion: Low-dose IR CT is safe and accurate for evaluating distribution and complications of known Crohn's disease in the outpatient setting. We propose that low-dose radiation imaging should be adopted as standard-of-care for the evaluation of Crohn's disease and an acceptable alternative to MR particularly in the acute setting. ClinicalTrials.gov: NCT03140306.

Body Composition, Inflammation, and 5-Year Outcomes in Colon Cancer.

Importance: Obesity, particularly visceral obesity and sarcopenia, are poor prognostic indicators in colon cancer. Objectives: To explore the association between body composition profiles and 5-year colon cancer outcomes and delineate the associated underlying inflammatory processes. Design, Setting, and Participants: This multicenter translational cohort study included patients with nonmetastatic colon cancer who did not have underlying chronic inflammatory disorders and were not receiving anti-inflammatory drugs referred to tertiary cancer centers from 2009 to 2015. Preoperative acute phase proteins (white cell count, C-reactive protein, and albumin), cytokines (interleukin [IL]-1b, IL-2, IL-6, IL-10, interferon γ, and tumor necrosis factor α), vascular endothelial growth factor (VEGF), and cell surface receptor expression levels (CD11b and CD14) were measured. All patients underwent follow-up for at least 5 years. Data were analyzed in December 2020. Exposure: Nonmetastatic colon cancer. Main Outcomes and Measures: The associations of body composition profiles with 5-year cancer recurrence and disease-specific mortality were analyzed using Mantel Cox log-rank test and Kaplan-Meier curves. Results: A total of 28 patients were included (median [interquartile range] age, 67 [58-72] years; 22 [78.6%] men). Low skeletal muscle area (SMA) and high visceral to total fat ratio were associated with poor clinical and oncological outcomes, including increased 5-year recurrence (low SMA: hazard ratio [HR], 2.30 [95% CI, 1.41-2.89]; P = .04; high visceral to total fat ratio: HR, 5.78 [95% CI, 3.66-7.95]; P = .02). High visceral to total fat ratio was associated with increased 5-year disease-specific mortality (HR, 5.92 [95% CI, 4.04-8.00]; P = .02). Patients with low SMA who developed a cancer recurrence, compared with those who did not, had higher C-reactive protein (mean [SD], 31.24 [6.95] mg/dL vs 8.11 [0.58] mg/dL; P = .003), IL-6 (mean [SD], 1.93 [1.16] ng/mL vs 0.88 [0.14] ng/mL; P = .004), VEGF (mean [SD], 310.03 [122.66] ng/mL vs 176.12 [22.94] ng/mL; P = .007), and CD14 (mean [SD], 521.23 [302.02] ng/mL vs 322.07 [98.35] ng/mL; P = .03) expression and lower albumin (mean [SD], 3.8 [0.6] g/dL vs 43.50 [3.69] g/dL; P = .01), IL-2 (mean [SD], 0.45 [0.25] ng/mL vs 0.94 [0.43] ng/mL; P < .001), IL-10 (mean [SD], 8.15 [1.09] ng/mL vs 16.32 [4.43] ng/mL; P = .004), and interferon γ (mean [SD], 2.61 [1.36] ng/mL vs 14.87 [3.43] ng/mL; P = .02) levels. Patients with high visceral to total fat ratio who developed recurrence had higher levels of IL-6 (mean [SD], 5.26 [7.05] ng/mL vs 2.76 [3.11] ng/mL; P = .03) and tumor necrosis factor α (mean [SD], 5.74 [4.53] ng/mL vs 4.50 [1.99] ng/mL; P = .03). Conclusions and Relevance: These findings suggest that low SMA and high visceral to total fat ratio were associated with worse colon cancer outcomes and with increased expression of proinflammatory cytokines and VEGF and inhibition of anti-inflammatory cytokines.

Development and implementation of an ultralow-dose CT protocol for the assessment of cerebrospinal shunts in adult hydrocephalus.

BACKGROUND: Cerebrospinal fluid shunts in the treatment of hydrocephalus, although associated with clinical benefit, have a high failure rate with repeat computed tomography (CT) imaging resulting in a substantial cumulative radiation dose. Therefore, we sought to develop a whole-body ultralow-dose (ULD) CT protocol for the investigation of shunt malfunction and compare it with the reference standard, plain radiographic shunt series (PRSS). METHODS: Following ethical approval, using an anthropomorphic phantom and a human cadaveric ventriculoperitoneal shunt model, a whole-body ULD-CT protocol incorporating two iterative reconstruction (IR) algorithms, pure IR and hybrid IR, including 60% filtered back projection and 40% IR was evaluated in 18 adult patients post new shunt implantation or where shunt malfunction was suspected. Effective dose (ED) and image quality were analysed. RESULTS: ULD-CT permitted a 36% radiation dose reduction (median ED 0.16 mSv, range 0.07-0.17, versus 0.25 mSv (0.06-1.69 mSv) for PRSS (p = 0.002). Shunt visualisation in the thoracoabdominal cavities was improved with ULD-CT with pure IR (p = 0.004 and p = 0.031, respectively) and, in contrast to PRSS, permitted visualisation of the entire shunt course (p < 0.001), the distal shunt entry point and location of the shunt tip in all cases. For shunt complications, ULD-CT had a perfect specificity. False positives (3/22, 13.6%) were observed with PRSS. CONCLUSIONS: At a significantly reduced radiation dose, whole body ULD-CT with pure IR demonstrated diagnostic superiority over PRSS in the evaluation of cerebrospinal fluid shunt malfunction.

Determining the accurate placement of a posterior portal in shoulder arthroscopy with the use of computerized tomography images.

Background: Portal placement is an important factor in performing a successful shoulder arthroscopy. Recent cadaveric studies have found variance in the anatomy of the glenohumeral joint. Our aim was to determine if computerized tomography (CT) images could be used to map the trajectory of the posterior portal objectively and then measure the distance between this trajectory and palpable landmarks to apply this knowledge to clinical practice. Methods: Two-dimensional multiplanar reformatted CT images were generated using OsiriX (Pixmeo, Switzerland) from CT images performed in a tertiary hospital over a 1-month period. The center of the glenoid was identified and a trajectory through it radiologically mapped. Horizontal and lateral measurements were taken from this trajectory to both the posterolateral edge of the acromion and tip of the coracoid. Results: Following application of inclusion and exclusion criteria, 226 shoulders were analyzed. Fifty scans were selected at random and re-reviewed by the primary examiner to assess intra-rater reliability which showed strong correlation and no significant differences between first and second measurements (P < .01, r > 0.6). The mean distance from acromion to portal trajectory was 1.39 cm inferiorly (95% confidence interval [CI] 1.31-1.48, standard deviation [SD] 0.65 cm) and 1.44 cm medially (95% CI 1.35-1.53, SD 0.71 cm). The mean distance from the coracoid to the trajectory was 1.71 cm inferiorly (95% CI 1.64-1.78, SD 0.55 cm) and 1.26 cm medially (95% CI 1-2-1.31, SD 0.45 cm). Paired t-test analysis between right and left shoulders within the same subject, where these data were available (n = 81), showed no significant difference (P > .05) between sides. Subset analysis was also performed between males and females, but only showed a significant difference between the vertical distance from the coracoid process to the center of the glenohumeral joint. This distance was shorter in females compared to males (1.56 cm in females compared to 1.84 cm in males, P < .001). Conclusions: Knowledge of shoulder anatomy is vital to the placement of arthroscopic portals, yet research on this topic has been based primarily on surface anatomy, small sample sized cadaveric studies or expert opinion alone. Our study shows that posterior portal placement in shoulder arthroscopy can be measured objectively using CT scanning.

Fast acquisition abdominal MRI study for the investigation of suspected acute appendicitis in paediatric patients.

OBJECTIVES: To assess the diagnostic accuracy of fast acquisition MRI in suspected cases of paediatric appendicitis presenting to a tertiary referral hospital. MATERIALS AND METHODS: A prospective study was undertaken between May and October 2017 of 52 children who presented with suspected appendicitis and were referred for an abdominal ultrasound. All patients included in this study received both an abdominal ultrasound and five-sequence MRI consisting of axial and coronal gradient echo T2 scans, fat-saturated SSFSE and a diffusion-weighted scan. Participants were randomised into groups of MRI with breath-holds or MRI with free breathing. A patient satisfaction survey was also carried out. Histopathology findings, where available, were used as a gold standard for the purposes of data analysis. Statistical analysis was performed, and p values < 0.05 were considered statistically significant. RESULTS: Ultrasound had a sensitivity and specificity of 25% and 92.9%, respectively. MRI with breath-hold had a sensitivity and specificity of 81.8% and 66.7%, respectively, whilst MRI with free breathing was superior with sensitivity and specificity of 92.3% and 84.2%, respectively. MRI with free breathing was also more time efficient (p < 0.0001). Group statistics were comparable (p < 0.05). CONCLUSIONS: The use of fast acquisition MRI protocols, particularly free breathing sequences, for patients admitted with suspected appendicitis can result in faster diagnosis, treatment and discharge. It also has a statistically significant diagnostic advantage over ultrasound. Additionally, the higher specificity of MR can reduce the number of negative appendectomies performed in tertiary centres.

Rapid diffusion-weighted MRI for the investigation of recurrent temporal bone cholesteatoma.

BACKGROUND: Suspected cholesteatoma recurrence is commonly investigated with magnetic resonance imaging (MRI) of the temporal bone. Non-echo planar diffusion-weighted imaging (non-EP DWI) has become the sequence of choice. PURPOSE: To assess the agreement between an MRI protocol incorporating both non-EP DWI and contrast-enhanced sequences, and a shortened protocol without contrast-enhanced sequences in the assessment of suspected cholesteatoma recurrence. MATERIALS AND METHODS: One hundred consecutive MRIs, consisting of T2-weighted, non-EP DWI and pre- and post-contrast T1-weighted sequences, were reviewed by two radiologists at a tertiary referral centre. Agreement between the two protocols was assessment by means of a weighted Cohen kappa coefficient. RESULTS: We found a near perfect agreement between the two protocols (kappa coefficient with linear weighting 0.98; 95% confidence interval 0.95-1.00). There were two cases in which the two protocols were discordant. In both cases, the lesion measured <3 mm and images were degraded by artefact at the bone-air interface. The shortened protocol without post-contrast sequences yielded a 32% reduction in acquisition time. CONCLUSION: When non-EP DWI is available, contrast-enhanced sequences can be omitted in the vast majority of cases without compromising diagnostic accuracy. Contrast-enhanced sequences may provide additional value in equivocal cases with small (<3 mm) lesions or in cases where images are degraded by artefact.

C-arm cone-beam CT parenchymal blood volume imaging for transarterial chemoembolization of hepatocellular carcinoma: implications for treatment planning and response.

We report on the feasibility of C-arm cone-beam computed tomography (CBCT) parenchymal blood volume imaging (PBVI) performed immediately following transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC) to assess the need for repeat treatment. Eighteen TACE procedures were included. A retrospective assessment was made for the presence or absence of residual disease requiring treatment on immediate post-TACE PBVI and on interval follow-up multidetector computed tomography (MDCT) or magnetic resonance imaging (MRI). In 9/18 cases, both PBVI and MDCT/MRI showed that no further treatment was required. In 6/18 cases, further treatment was required on both PBVI and MDCT/MRI. In three cases, PBVI showed that further treatment was not required but MDCT/MRI showed residual disease requiring repeat treatment. There were no cases with PBVI showing residual disease not detected on follow-up MDCT/MRI. The PBVI sensitivity for detecting disease requiring repeat TACE was 67% (95% confidence interval [CI] 30-93%), and specificity was 100% (95% CI 66-100%). The use of C-arm CBCT PBVI for the detection of residual viable tumor within a treated lesion immediately after TACE is feasible. It may allow repeat TACE to be planned without performing interval imaging with MDCT or MRI.

Low-dose CT imaging of the acute abdomen using model-based iterative reconstruction: a prospective study.

OBJECTIVES: Performance of a modified abdominopelvic CT protocol reconstructed using full iterative reconstruction (IR) was assessed for imaging patients presenting with acute abdominal symptoms. MATERIALS AND METHODS: Fifty-seven patients (17 male, 40 female; mean age of 56.5 ± 8 years) were prospectively studied. Low-dose (LD) and conventional-dose (CD) CTs were contemporaneously acquired between November 2015 and March 2016. The LD and CD protocols imparted radiation exposures approximating 10-20% and 80-90% those of routine abdominopelvic CT, respectively. The LD images were reconstructed with model-based iterative reconstruction (MBIR), and CD images with hybrid IR (40% adaptive statistical iterative reconstruction (ASIR)). Image quality was assessed quantitatively and qualitatively. Independent clinical interpretations were performed with a 6-week delay between reviews. RESULTS: A 74.7% mean radiation dose reduction was achieved: LD effective dose (ED) 2.38 ± 1.78 mSv (size-specific dose estimate (SSDE) 3.77 ± 1.97 mGy); CD ED 7.04 ± 4.89 mSv (SSDE 10.74 ± 5.5 mGy). LD-MBIR images had significantly lower objective and subjective image noise compared with CD-ASIR (p < 0.0001). Noise reduction for LD-MBIR studies was greater for patients with BMI < 25 kg/m2 than those with BMI ≥ 25 kg/m2 (5.36 ± 3.2 Hounsfield units (HU) vs. 4.05 ± 3.1 HU, p < 0.0001). CD-ASIR studies had significantly better contrast resolution, and diagnostic acceptability (p < 0.0001 for all). LD-MBIR studies had significantly lower streak artifact (p < 0.0001). There was no difference in sensitivity for primary findings between the low-dose and conventional protocols with the exception of one case of enteritis. CONCLUSIONS: Low-dose abdominopelvic CT performed with MBIR is a feasible radiation dose reduction strategy for imaging patients presenting with acute abdominal pain.

Low-Dose Computed Tomography for the Optimization of Radiation Dose Exposure in Patients with Crohn's Disease.

Magnetic resonance imaging (MRI) is the mainstay method for the radiological imaging of the small bowel in patients with inflammatory bowel disease without the use of ionizing radiation. There are circumstances where imaging using ionizing radiation is required, particularly in the acute setting. This usually takes the form of computed tomography (CT). There has been a significant increase in the utilization of computed tomography (CT) for patients with Crohn's disease as patients are frequently diagnosed at a relatively young age and require repeated imaging. Between seven and eleven percent of patients with IBD are exposed to high cumulative effective radiation doses (CEDs) (>35-75 mSv), mostly patients with Crohn's disease (Newnham E 2007, Levi Z 2009, Hou JK 2014, Estay C 2015). This is primarily due to the more widespread and repeated use of CT, which accounts for 77% of radiation dose exposure amongst patients with Crohn's disease (Desmond et al., 2008). Reports of the projected cancer risks from the increasing CT use (Berrington et al., 2007) have led to increased patient awareness regarding the potential health risks from ionizing radiation (Coakley et al., 2011). Our responsibilities as physicians caring for these patients include education regarding radiation risk and, when an investigation that utilizes ionizing radiation is required, to keep radiation doses as low as reasonably achievable: the "ALARA" principle. Recent advances in CT technology have facilitated substantial radiation dose reductions in many clinical settings, and several studies have demonstrated significantly decreased radiation doses in Crohn's disease patients while maintaining diagnostic image quality. However, there is a balance to be struck between reducing radiation exposure and maintaining satisfactory image quality; if radiation dose is reduced excessively, the resulting CT images can be of poor quality and may be nondiagnostic. In this paper, we summarize the available evidence related to imaging of Crohn's disease, radiation exposure, and risk, and we report recent advances in low-dose CT technology that have particular relevance.

Review of the role of abdominal imaging in irritable bowel syndrome.

The role of radiologic imaging in the investigation of irritable bowel syndrome (IBS) remains a subject of debate and there is some evidence, from recent studies of utilization of imaging in IBS, which focused on associated costs and radiation exposure, that imaging is being used relatively widely in these patients. This review aims to assess current best evidence to accurately define the role of radiologic imaging in IBS patients. Primary and secondary literature searches were performed. Evidence suggests that the lack of "red flag" or alarm features in IBS patients should reassure the clinician that the diagnosis of IBS is correct and United States and United Kingdom guidelines recommend no radiologic imaging for IBS patients if alarm features are not present. In patients presenting with IBS symptoms and alarm features, radiologic testing may be used to exclude an alternative diagnosis and the imaging modality should be chosen based on the most likely alternative diagnosis.

Using body mass index to estimate individualised patient radiation dose in abdominal computed tomography.

BACKGROUND: The size-specific dose estimate (SSDE) is a dose-related metrics that incorporates patient size into its calculation. It is usually derived from the volume computed tomography dose index (CTDIvol) by applying a conversion factor determined from manually measured anteroposterior and lateral skin-to-skin patient diameters at the midslice level on computed tomography (CT) localiser images, an awkward, time-consuming, and not highly reproducible technique. The objective of this study was to evaluate the potential for the use of body mass index (BMI) as a size-related metrics alternative to the midslice effective diameter (DE) to obtain a size-specific dose (SSDE) in abdominal CT. METHODS: In this retrospective study of patients who underwent abdominal CT for the investigation of inflammatory bowel disease, the DE was measured on the midslice level on CT-localiser images of each patient. This was correlated with patient BMI and the linear regression equation relating the quantities was calculated. The ratio between the internal and the external abdominal diameters (DRATIO) was also measured to assess correlation with radiation dose. Pearson correlation analysis and linear regression models were used. RESULTS: There was good correlation between DE and patient BMI (r = 0.88). An equation allowing calculation of DE from BMI was calculated by linear regression analysis as follows: DE = 0.76 (BMI) + 9.4. A weak correlation between radiation dose and DRATIO was demonstrated (r = 0.45). CONCLUSIONS: Patient BMI can be used to accurately estimate DE, obviating the need to measure anteroposterior and lateral diameters in order to calculate a SSDE for abdominal CT.

The impact of sarcopenia and myosteatosis on postoperative outcomes in patients with inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease (IBD) is a relatively common disorder with significant associated morbidity. Sarcopenia and myosteatosis are associated with adverse postoperative outcomes. This study investigated outcomes in IBD patients undergoing surgical resection relative to the presence of sarcopenia and myosteatosis. METHODS: A retrospective analysis of a prospectively maintained surgical database was conducted. All patients undergoing elective or emergency resection for IBD between 2011 and 2016, with a contemporaneous perioperative computed tomography (CT) scan, were included. Patient demographics, clinical and biochemical measurements were collected. Skeletal muscle index and attenuation were measured on perioperative CT scans using Osirix version 5.6.1. Univariate and multivariate regression analysis was used to identify risk factors for adverse postoperative outcomes. RESULTS: Seventy-seven patients (46 male, 31 female; mean age 42 years, range 20-80 years) were included. Thirty patients (30%) had sarcopenia and 26 (34%) had myosteatosis. Myosteatosis was significantly associated with increased hospital stay postoperatively (9 versus 13 days). Sarcopenia and myosteatosis were associated with hospital readmission within 30 days on univariate analysis. Multivariate regression analysis demonstrated an independent association between myosteatosis and hospital readmission. Sixteen patients (21%) had a clinically relevant postoperative complication, but an association with sarcopenia and myosteatosis was not observed. A neutrophil-lymphocyte ratio greater than 5 was predictive of clinically relevant postoperative complications on multivariate regression analysis. CONCLUSIONS: Myosteatosis was associated with increased hospital stay and increased 30-day hospital readmission rates on multivariate regression analysis. Sarcopenia and myosteatosis in IBD were not associated with clinically relevant postoperative complications.

Diagnostic Utility of Computed Tomographic Angiography in Giant-Cell Arteritis.

Background and Purpose- The diagnosis of giant-cell arteritis (GCA) is challenging. Superficial temporal artery biopsy and ultrasound are positive in only 50%. We evaluated computed tomographic angiography (CTA) of the head in GCA. Methods- This case-control study was performed using a prospective GCA registry. Cases presented with stroke symptoms, had a CTA, and were subsequently diagnosed with GCA. Age- and sex-matched controls presented with stroke symptoms, had a CTA, and were not diagnosed with GCA. CTAs were evaluated for the presence of superficial temporal artery abnormalities. Results- Fourteen cases met the inclusion criteria and were matched with 14 controls. Blurred vessel wall margins and perivascular enhancement was found in 10 cases (71.4%) and 2 controls (14.3%). CTA has an accuracy of 78.6%, sensitivity of 71.4%, and a specificity of 85.7% for GCA. Conclusions- CTA detects superficial temporal artery abnormalities in GCA. This may facilitate early diagnosis and prompt implementation of potentially sight-saving and stroke-preventing treatment.

Sarcopenia and Post-Operative Morbidity and Mortality in Patients with Gastric Cancer.

PURPOSE: Surgical resection for gastric adenocarcinoma is associated with significant post-operative morbidity and mortality. The aim of this study was to assess the prognostic significance of sarcopenia in patients undergoing resection for gastric adenocarcinoma with respect to post-operative morbidity and survival. MATERIALS AND METHODS: A retrospective analysis was conducted on a cohort of consecutive patients who underwent surgical resection for gastric adenocarcinoma between 2008 and 2014. Patient demographics, radiological parameters, and pathological data were collected. OsiriX software (Pixmeo) was used to measure skeletal muscle area, which was normalized for height to calculate skeletal muscle index. RESULTS: A total of 56 patients (41 male, 15 female; mean age, 68.4 ± 11.9 years) met the inclusion criteria. Of these, 36% (20 of 56) of the patients were sarcopenic pre-operatively. Both sarcopenic and non-sarcopenic patient groups were equally matched with the exception of weight and body mass index (P=0.036 and 0.001, respectively). Sarcopenia was associated with a decreased overall survival (log-rank P=0.003) and was an adverse prognostic predictor of overall survival in multivariate analysis (hazard ratio, 10.915; P=0.001). Sarcopenia was a predictor of serious in-hospital complications in multivariate analysis (odds ratio, 3.508; P=0.042). CONCLUSIONS: In patients undergoing curative resection for gastric cancer, there was a statistically significant association between sarcopenia and both decreased overall survival and serious post-operative complications. The measurement and reporting of skeletal muscle index on pre-operative computed tomography should be considered.

Determination of a suitable low-dose abdominopelvic CT protocol using model-based iterative reconstruction through cadaveric study.

INTRODUCTION: Cadaveric studies provide a means of safely assessing new technologies and optimizing scanning prior to clinical validation. Reducing radiation exposure in a clinical setting can entail incremental dose reductions to avoid missing important clinical findings. The use of cadavers allows assessment of the impact of more substantial dose reductions on image quality. Our aim was to identify a suitable low-dose abdominopelvic CT protocol for subsequent clinical validation. METHODS: Five human cadavers were scanned at one conventional dose and three low-dose settings. All scans were reconstructed using three different reconstruction algorithms: filtered back projection (FBP), hybrid iterative reconstruction (60% FBP and 40% adaptive statistical iterative reconstruction (ASIR40)), and model-based iterative reconstruction (MBIR). Two readers rated the image quality both quantitatively and qualitatively. RESULTS: Model-based iterative reconstruction images had significantly better objective image noise and higher qualitative scores compared with both FBP and ASIR40 images at all dose levels. The greatest absolute noise reduction, between MBIR and FBP, of 34.3 HU (equating to a 68% reduction) was at the lowest dose level. MBIR reduced image noise and improved image quality even in CT images acquired with a mean radiation dose reduction of 62% compared with conventional dose studies reconstructed with ASIR40, with lower levels of objective image noise, superior diagnostic acceptability and contrast resolution, and comparable subjective image noise and streak artefact scores. CONCLUSION: This cadaveric study demonstrates that MBIR reduces image noise and improves image quality in abdominopelvic CT images acquired with dose reductions of up to 62%.

Monitoring neurointerventional radiation doses using dose-tracking software: implications for the establishment of local diagnostic reference levels.

OBJECTIVES: There is potential for high radiation exposure during neurointerventional procedures. Increasing regulatory requirements mandate dose monitoring of patients and staff, and justification of high levels of radiation exposure. This paper demonstrates the potential to use radiation dose-tracking software to establish local diagnostic reference levels. METHODS: Consecutive neurointerventional procedures, performed in a single institution within a one-year period, were retrospectively studied. Dose area product (DAP) data were collected using dose-tracking software and clinical data obtained from a prospectively generated patient treatment database. RESULTS: Two hundred and sixty-four procedures met the selection criteria. Median DAP was 100 Gy.cm2 for aneurysm coiling procedures, 259 Gy.cm2 for arteriovenous malformation (AVM) embolisation procedures, 87 Gy.cm2 for stroke thrombolysis/thrombectomy, and 74 Gy.cm2 for four-vessel angiography. One hundred and nine aneurysm coiling procedures were further studied. Six significant variables were assessed using stepwise regression analysis to determine effect on DAP. Aneurysm location (anterior vs posterior circulation) had the single biggest effect (p = 0.004). CONCLUSIONS: This paper confirms variable radiation exposures during neurointerventional procedures. The 75th percentile (used to define diagnostic reference levels) of DAP measurements represents a reasonable guidance metric for monitoring purposes. Results indicate that aneurysm location has the greatest impact on dose during coiling procedures and that anterior and posterior circulation coiling procedures should have separate diagnostic reference levels. KEY POINTS: • Dose-tracking software is useful for monitoring patient radiation dose during neurointerventional procedures • This paper provides a template for methodology applicable to any interventional suite • Local diagnostic reference levels were defined by using the 75th percentile of DAP as per International Commission on Radiological Protection recommendations • Aneurysm location is the biggest determinant of radiation dose during coiling procedures. • Anterior and posterior circulation coiling procedures should have separate diagnostic reference levels.

Body composition determinants of radiation dose during abdominopelvic CT.

OBJECTIVES: We designed a prospective study to investigate the in-vivo relationship between abdominal body composition and radiation exposure to determine the strongest body composition predictor of dose length product (DLP) at CT. METHODS: Following institutional review board approval, quantitative analysis was performed prospectively on 239 consecutive patients who underwent abdominopelvic CT. DLP, BMI, volumes of abdominal adipose tissue, muscle, bone and solid organs were recorded. RESULTS: All measured body composition parameters correlated positively with DLP. Linear regression (R2 = 0.77) revealed that total adipose volume was the strongest predictor of radiation exposure [B (95% CI) = 0.027(0.024-0.030), t=23.068, p < 0.001]. Stepwise linear regression using DLP as the dependent and BMI and total adipose tissue as independent variables demonstrated that total adipose tissue is more predictive of DLP than BMI [B (95% CI) = 16.045 (11.337-20.752), t=6.681, p < 0.001]. CONCLUSIONS: The volume of adipose tissue was the strongest predictor of radiation exposure in our cohort. MAIN MESSAGE: • Individual body composition variables correlate with DLP at abdominopelvic CT. • Total abdominal adipose tissue is the strongest predictor of radiation exposure. • Muscle volume is also a significant but weaker predictor of DLP.

An Assessment of the Quality of CT Radiation Dose Information on the Internet.

OBJECTIVES: Our goal was to ascertain the quality of health information related to CT radiation exposure using a simulated Internet search and from incident information that may be available during day-to-day Internet usage. METHODS: We entered 14 terms relating to information on CT dose into the most commonly used Internet search engine and analyzed the first 100 web page results for each. A Rich Search Site (RSS) feed search was also used to evaluate incidental information over a 12-week period in 2014. Each web page was classified as being "completely accurate," "somewhat accurate," or "inaccurate." RESULTS: Of 1,400 web pages, 290 were relevant and accessible. We deemed 12.8% of these pages as inaccurate and 67.2% of pages as completely accurate. The highest proportion of web pages was from media sources, which, along with discussion forums, commercial websites, and blogs, were found to have proportionally the largest amount of inaccurate information. Of 1,943 posts, 136 (7.0%) identified by the RSS were relevant, 9.6% were deemed inaccurate, and only 29.9% were deemed completely accurate. The results of our simulated query highlight the importance of public education regarding Internet usage when researching topics relating to radiation exposure associated with CT.

Comparative Effectiveness of Imaging Modalities for the Diagnosis and Treatment of Intussusception: A Critically Appraised Topic.

RATIONALE AND OBJECTIVES: The purpose of this study was to critically appraise and compare the diagnostic performance of imaging modalities that are used for the diagnosis of intussusception and methods used in the treatment of ileocolic intussusception. METHODS: A focused clinical question was constructed and the literature was searched using the patient, intervention, comparison, outcome (PICO) method comparing radiography, ultrasound, and computed tomography in the detection of intussusception. The same methods were used to compare pneumatic (gas) reduction and hydrostatic (liquid) reduction using saline, water-soluble contrast, and barium. Retrieved articles were appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-Based Medicine hierarchy of validity for diagnostic studies. RESULTS: The retrieved sensitivity for the diagnosis of intussusception using plain radiography is 48% (95% confidence interval [CI], 44%-52%), with a specificity of 21% (95% CI, 18%-24%). The retrieved sensitivity for the diagnosis of intussusception using ultrasound is 97.9% (95% CI, 95%-100%), with a specificity of 97.8% (95% CI, 97%-99%). Based on a good quality meta-analysis, the combined success rate of gas enema reduction was shown to be 82.7% (95% CI, 79.9%-85.6%) compared to a combined success rate of 69.6% (95% CI, 65.0%-74.1%) for liquid enema reduction. CONCLUSIONS: The best available evidence recommends ultrasound as the diagnostic modality of choice for the diagnosis of ileocolic intussusception in children. In stable children without signs of peritonism, nonoperative reduction is the treatment of choice. Pneumatic (gas) reduction enema has been shown to be superior to hydrostatic (liquid) enema reduction.

Population impacts in white sucker (Catostomus commersonii) exposed to oil sands-derived contaminants in the Athabasca River.

Biological and chemical endpoints were measured in white sucker collected downstream of Athabasca oil sands developments (AB, Canada) and compared with those at Calling Lake (AB, Canada), a reference location upstream of the Athabasca oil sands deposit. Naphthenic acid concentrations were also measured at 14 sites in the Athabasca River watershed. Concentrations of naphthenic acids were elevated in tributaries adjacent to oil sands mining developments. Tributary naphthenic acid profiles were more similar to aged oil sands process water than samples from the Athabasca River, suggesting an influence of tailings in the tributaries. White sucker showed higher energy storage in the Athabasca River as indicated by significantly higher condition and liver size. White sucker were not investing that energy into reproductive effort as measured by gonad size and fecundity, which were significantly reduced relative to the reference location. White sucker showed increased exposure to polycyclic aromatic hydrocarbons as indicated by hepatic cytochrome P4501A (CYP1A) activity and fluorescent bile metabolites, as well as higher concentrations of naphthenic acids in bile. Cadmium, copper, nickel, and selenium were also elevated in white sucker liver tissue compared with the reference location. Based on the exposure profile and response pattern observed, effects on energy storage and utilization in white sucker from the Athabasca River most likely resulted from exposure to polycyclic aromatic hydrocarbons derived from petrogenic and pyrolytic sources. Environ Toxicol Chem 2017;36:2058-2067. © 2017 SETAC.