The Emerging Role and Clinical Applications of Morphomics in Diagnostic Imaging.

Analytic morphomics refers to the accurate measurement of specific biological markers of human body composition in diagnostic medical imaging. The increasing prevalence of disease processes that alter body composition including obesity, cachexia, and sarcopenia has generated interest in specific targeted measurement of these metrics to possibly prevent or reduce negative health outcomes. Typical morphomic measurements include the area and density of muscle, bone, vascular calcification, visceral fat, and subcutaneous fat on a specific validated axial level in the patient's cross-sectional diagnostic imaging. A distinct advantage of these measurements is that they can be made retrospectively and opportunistically with pre-existing datasets. We provide a narrative review of the current state of art in morphomics, but also consider some potential future directions for this exciting field. Imaging based quantitative assessment of body composition has enormous potential across the breadth and scope of modern clinical practice. From risk stratification to treatment planning, and outcome assessment, all can be enhanced with the use of analytic morphomics. Moreover, it is likely that many new opportunities for personalized medicine will emerge as the field evolves. As radiologists, embracing analytic morphomics will enable us to contribute added value in the care of every patient.

Paediatric Thoracic Imaging in Cystic Fibrosis in the Era of Cystic Fibrosis Transmembrane Conductance Regulator Modulation.

Cystic fibrosis (CF) is one of the most common progressive life-shortening genetic conditions worldwide. Ground-breaking translational research has generated therapies that target the primary cystic fibrosis transmembrane conductance regulator (CFTR) defect, known as CFTR modulators. A crucial aspect of paediatric CF disease is the development and progression of irreversible respiratory disease in the absence of clinical symptoms. Accurate thoracic diagnostics have an important role to play in this regard. Chest radiographs are non-specific and insensitive in the context of subtle changes in early CF disease, with computed tomography (CT) providing increased sensitivity. Recent advancements in imaging hardware and software have allowed thoracic CTs to be acquired in paediatric patients at radiation doses approaching that of a chest radiograph. CFTR modulators slow the progression of CF, reduce the frequency of exacerbations and extend life expectancy. In conjunction with advances in CT imaging techniques, low-dose thorax CT will establish a central position in the routine care of children with CF. International guidelines regarding the choice of modality and timing of thoracic imaging in children with CF are lagging behind these rapid technological advances. The continued progress of personalised medicine in the form of CFTR modulators will promote the emergence of personalised radiological diagnostics.

Analytic Morphomics in Myositis-Related Interstitial Lung Disease.

PURPOSE: Interstitial lung disease (ILD) is the most common non-musculoskeletal manifestation of idiopathic inflammatory myopathies (IIM). Identification of body composition change may enable early intervention to improve prognosis. We investigated muscle quantity and quality derived from cross-sectional imaging in IIM, and its relationship to ILD severity. METHODS: A retrospective cohort study assessing IIM of ILD patients (n = 31) was conducted. Two datasets separated in time were collected, containing demographics, biochemical data, pulmonary function testing and thoracic CT data. Morphomic analysis of muscle quantity (cross-sectional area) and quality (density in Hounsfield Units) on thoracic CT were analysed utilising a web-based tool allowing segmentation of muscle and fat. Bilateral erector spinae and pectoralis muscle (ESM&PM) were measured at defined vertebral levels. RESULTS: FVC and DLCO decreased but within acceptable limits of treatment response (FVC: 83.7-78.7%, p < 0.05, DLCO 63.4-60.6%, p < 0.05). The cross-sectional area of the PM and ESM increased (PM: 39.8 to 40.7 cm2, p = 0.491; ESM: 35.2 to 39.5 cm2, p = 0.098). Density significantly fell for both the PM and ESM (PM: 35.3-31 HU, p < 0.05; ESM: 38-33.7, p < 0.05). Subcutaneous fat area increased from 103.9 to 136.1 cm2 (p < 0.05), while the visceral fat area increased but not reaching statistical significance. The change in PM density between time points demonstrated an inverse correlation with DLCO (p < 0.05, R = - 0.49). CONCLUSION: Patients with IIM ILD demonstrated significant body composition changes on CT imaging unlikely to be detected by traditional measurement tools. An increase in muscle area with an inverse decrease in density suggests poor muscle quality.

Replacing Plain Radiograph with ultra-low dose CT thorax in cystic fibrosis (CF) in the era of CFTR modulation and its impact on cumulative effective dose.

BACKGROUND: Medical radiation exposure is of increasing concern in patients with cystic fibrosis (PWCF) due to improving life expectancy. We aimed to assess and quantify the cumulative effective dose (CED) in PWCF in the context of CFTR-modulator therapy and the advancement of dose reduction techniques. METHODS: We performed a retrospective observational study in a single University CF centre over a 11-year period. We included PWCF, aged over 18 years who exclusively attended our institution. Relevant clinical data (demographics, transplantation history and modulator status) and radiological data (modality, quantity, and radiation exposure measured as CED) were collected. For those on modulator therapy the quantified imaging and radiation data was dichotomised into pre-and-post therapy periods. RESULTS: The study included 181 patients: 139 on CFTR modulator therapy, 15 transplant recipients and 27 with neither exposure. 82% of patients received <25 mSv over the study period. Mean study duration was 6.9 ± 2.6 years pre-modulation and 4.2 ± 2.6 years post-modulation. Pre-modulation CT contributed 9.6% of total chest imaging (n = 139/1453) and 70.9% of the total CED. Post-modulation CT use increased contributing 42.7% of chest imaging (n = 444/1039) and comprised 75.8% of CED. Annual CED was 1.55 mSv pre and 1.36 mSv post modulation (p = 0.41). Transplant recipients had an annual CED of 64 ± 36.1mSv. CONCLUSION: Chest CT utilisation for PWCF is rising in our institution, replacing chest radiography amidst CFTR-modulation. Despite the increasing use of CT, no significant radiation dose penalty was observed with a reduction in mean annual CED, primarily due to the influence of CT dose reduction strategies.

Uterine Artery Embolisation of Fibroids and the Phenomenon of Post-Embolisation Syndrome: A Systematic Review.

Post-embolisation syndrome (PES) is a prevalent complication that occurs in patients following uterine artery embolisation (UAE) for the treatment of uterine fibroids. The aetiology of PES remains incompletely understood, although postulated to result secondary to tissue infarction resulting in release of inflammatory mediators. We followed PRISMA guidelines and performed a systematic review of studies of PES following UAE from inception to October 2022. Our published protocol was prospectively registered. Our search yielded 54 results. We reviewed 22 full texts, and nine articles were included. Observational studies comprised 6/9 relevant studies, with 5/9 retrospective design. The rate of PES was documented in 5/8 studies (excluding case report) with a reported incidence ranging from 4-34.6%. Five of the nine studies studies postulated that the aetiological basis of PES is inflammatory related. Further research is necessary to advance our understanding of PES to define the biological basis of the syndrome with more certainty and gain a consensus on peri-procedure management to reduce incidence and improve patient outcomes.

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.

The evolving role of radiological imaging in cystic fibrosis.

PURPOSE OF REVIEW: Radiological imaging has a crucial role in pulmonary evaluation in cystic fibrosis (CF), having been shown to be more sensitive than pulmonary function testing at detecting structural lung changes. The present review summarizes the latest published information on established and evolving pulmonary imaging techniques for assessing people with this potentially life-limiting disorder. RECENT FINDINGS: Chest computed tomography (CT) has taken over the predominant role of chest radiography in many centres for the initial assessment and surveillance of CF lung disease. However, several emerging techniques offer a promising means of pulmonary imaging using less ionizing radiation. This is of particular importance given these patients tend to require repeated imaging throughout their lives from a young age. Such techniques include ultra-low-dose CT, tomosynthesis, dynamic radiography and magnetic resonance imaging. In addition, deep-learning algorithms are anticipated to improve diagnostic accuracy. SUMMARY: The recent introduction of triple-combination CF transmembrane regulator therapy has put further emphasis on the need for sensitive methods of monitoring treatment response to allow for early adaptation of treatment regimens in order to limit irreversible lung damage. Further research is needed to establish how emerging imaging techniques can contribute to this safely and effectively.

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.

Best Practices: Imaging Strategies for Reduced-Dose Chest CT in the Management of Cystic Fibrosis-Related Lung Disease.

OBJECTIVE. Cystic fibrosis (CF) is a multisystemic life-limiting disorder. The leading cause of morbidity in CF is chronic pulmonary disease. Chest CT is the reference standard for detection of bronchiectasis. Cumulative ionizing radiation limits the use of CT, particularly as treatments improve and life expectancy increases. The purpose of this article is to summarize the evidence on low-dose chest CT and its effect on image quality to determine best practices for imaging in CF. CONCLUSION. Low-dose chest CT is technically feasible, reduces dose, and renders satisfactory image quality. There are few comparison studies of low-dose chest CT and standard chest CT in CF; however, evidence suggests equivalent diagnostic capability. Low-dose chest CT with iterative reconstructive algorithms appears superior to chest radiography and equivalent to standard CT and has potential for early detection of bronchiectasis and infective exacerbations, because clinically significant abnormalities can develop in patients who do not have symptoms. Infection and inflammation remain the primary causes of morbidity requiring early intervention. Research gaps include the benefits of replacing chest radiography with low-dose chest CT in terms of improved diagnostic yield, clinical decision making, and patient outcomes. Longitudinal clinical studies comparing CT with MRI for the monitoring of CF lung disease may better establish the complementary strengths of these imaging modalities.

Computed tomography in cystic fibrosis lung disease: a focus on radiation exposure.

Thoracic computed tomography (CT) is the imaging reference method in the diagnosis, assessment and management of lung disease. In the setting of cystic fibrosis (CF), CT demonstrates increased sensitivity compared with pulmonary function tests and chest radiography, and findings correlate with clinical outcomes. Better understanding of the aetiology of CF lung disease indicates that even asymptomatic infants with CF can have irreversible pulmonary pathology. Surveillance and early diagnosis of lung disease in CF are important to preserve lung parenchyma and to optimise long-term outcomes. CF is associated with increased cumulative radiation exposure due to the requirement for repeated imaging from a young age. Radiation dose optimisation, important for the safe use of CT in children with CF, is best achieved in a team environment where paediatric radiologists work closely with paediatric respiratory physicians, physicists and radiography technicians to achieve the best patient outcomes. Despite the radiation doses incurred, CT remains a vital imaging tool in children with CF. Radiologists with special interests in CT dose optimisation and respiratory disease are key to the appropriate use of CT in paediatric imaging. Paediatric radiologists strive to minimise radiation dose to children whilst providing the best possible assessment of lung disease.

Bridging the divide between medical school and clinical practice: identification of six key learning outcomes for an undergraduate preparatory course in radiology.

BACKGROUND: There exists a significant divide between what is learnt in medical school and subsequently what is required to practice medicine effectively. Despite multiple strategies to remedy this discordance, the problem persists. Here, we describe the identification of a comprehensive set of learning outcomes for a preparation for practice course in radiology. METHODS: Assessment of interns' readiness to interact with the radiology department was conducted using a national survey of both interns and radiologists. In parallel, group concept mapping (GCM) which involves a combination of qualitative and quantitative techniques was used to identify the shared understanding of participants from a diverse range of medical specialties regarding what topics should be included in an intern preparatory course for interacting with the radiology department. RESULTS: The survey demonstrated that most interns and radiologists felt that undergraduate medical training did not prepare interns to interact with the radiology department. GCM identified six learning outcomes that should be targeted when designing a preparatory module: requesting investigations; clinical decision support; radiology department IT and communication; adverse reactions and risks; interpretation of radiology results and urgent imaging. The thematic clusters from the group concept mapping corroborated the deficiencies identified in the national survey. CONCLUSION: We have identified six key learning outcomes that should be included in a preparation for practice module in radiology. Future courses targeting these thematic clusters may facilitate a smoother transition from theory to practice for newly graduated doctors.

Transbronchial lung cryobiopsy (TBLC) in the diagnosis of interstitial lung disease: experience of first 100 cases performed under conscious sedation with flexible bronchoscope.

BACKGROUND: Diagnosing the aetiology of interstitial lung disease (ILD) may require histology via a surgical lung biopsy (SLB). SLB is associated with significant complications. Transbronchial lung cryobiopsy (TBLC) can provide large, adequate biopsies with fewer complications offering a potential alternative to SLB. AIMS: This study evaluated the safety, diagnostic yield and impact of TBLC on diagnostic certainty in the multidisciplinary diagnosis (MDD) of ILD within routine clinical practice. METHODS: A retrospective study of all TBLC performed in a tertiary institute from March 2014 to December 2016 was performed. Procedures were performed using a flexible bronchoscope and cryoprobe without fluoroscopic guidance. RESULTS: One hundred procedures were performed on 85 patients. A total of 272 cryobiopsies were obtained with a mean biopsy diameter of 5.9 ± 3.2 mm. Ninety-seven percent contained alveolated lung tissue. Diagnosis based against MDD gold standard was confirmed using TBLC in 67.1% of patients and in 72/100 procedures. Three patients proceeded to SLB. The addition of histological information changed the clinic-radiological diagnosis in twelve patients. The most common diagnosis based on clinical-radiologic-pathologic correlation at MDD was idiopathic pulmonary fibrosis (IPF) (51.2%) and hypersensitivity pneumonitis (15.9%). Moderate bleeding occurred in 18% of cases and five patients (5%) developed pneumothorax requiring intervention. Eleven patients required admission, with a mean length of stay of 1.3 ± 0.9 days. CONCLUSION: TBLC aids the diagnosis of ILD in the appropriate patient and may be an acceptable alternative to SLB with fewer complications. Further work on standardizing the procedure is required.

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.

Virtual Mechanical Testing Based on Low-Dose Computed Tomography Scans for Tibial Fracture: A Pilot Study of Prediction of Time to Union and Comparison with Subjective Outcomes Scoring.

BACKGROUND: Quantitative outcomes assessment remains a persistent challenge in orthopaedic trauma. Although patient-reported outcome measures (PROMs) and radiographic assessments such as Radiographic Union Scale for Tibial Fractures (RUST) scores are frequently used, very little evidence has been presented to support their validity for measuring structural bone formation or biomechanical integrity. METHODS: In this pilot study, a sequential cohort of patients with a tibial shaft fracture were prospectively recruited for observation following standard reamed intramedullary nailing in a level-I trauma center. Follow-up at 6, 12, 18, and 24 weeks included radiographs and completion of PROMs (EuroQol 5-Dimension [EQ-5D] and pain scores). Low-dose computed tomography (CT) scans were also performed at 12 weeks. Scans were reconstructed in 3 dimensions (3D) and subjected to virtual mechanical testing via the finite element method to assess torsional rigidity in the fractured limb relative to that in the intact bone. RESULTS: Patients reported progressive longitudinal improvement in mobility, self-care, activity, and health over time, but the PROMs were not correlated with structural bone healing. RUST scoring showed moderate intrarater agreement (intraclass coefficient [ICC] = 0.727), but the scores at 12 weeks were not correlated with the time to union (R = 0.104, p = 0.193) and were only moderately correlated with callus structural integrity (R = 0.347, p = 0.010). In contrast, patient-specific virtual torsional rigidity (VTR) was significantly correlated with the time to union (R = 0.383, p = 0.005) and clearly differentiated 1 case of delayed union (VTR = 10%, union at 36 weeks) from the cases in the normally healing cohort (VTR > 60%; median union time, 19 weeks) on the basis of CT data alone. CONCLUSIONS: PROMs provide insight into the natural history of the patient experience after tibial fracture but have limited utility as a measure of structural bone healing. RUST scoring, although reproducible, may not reliably predict time to union. In contrast, virtual mechanical testing with low-dose CT scans provides a quantitative and objective structural callus assessment that reliably predicts time to union and may enable early diagnosis of compromised healing. LEVEL OF EVIDENCE: Therapeutic Level IV. Please see Instructions for Authors for a complete description of levels of evidence.

Virtual structural analysis of tibial fracture healing from low-dose clinical CT scans.

Quantitative assessment of bone fracture healing remains a significant challenge in orthopaedic trauma research. Accordingly, we developed a new technique for assessing bone healing using virtual mechano-structural analysis of computed tomography (CT) scans. CT scans from 19 fractured human tibiae at 12 weeks after surgery were segmented and prepared for finite element analysis (FEA). Boundary conditions were applied to the models to simulate a torsion test that is commonly used to access the structural integrity of long bones in animal models of fracture healing. The output of each model was the virtual torsional rigidity (VTR) of the healing zone, normalized to the torsional rigidity of each patient's virtually reconstructed tibia. This provided a structural measure to track the percentage of healing each patient had undergone. Callus morphometric measurements were also collected from the CT scans. Results showed that at 12 weeks post-op, more than 75% of patients achieved a normalized VTR (torsional rigidity relative to uninjured bone) of 85% or above. The predicted intact torsional rigidities compared well with published cadaveric data. Across all patients, callus volume and density were weakly and non-significantly correlated with normalized VTR and time to clinical union. Conversely, normalized VTR was significantly correlated with time to union (R2 = 0.383, p = 0.005). This suggests that fracture scoring methods based on the visual appearance of callus may not accurately predict mechanical integrity. The image-based structural analysis presented here may be a useful technique for assessment of bone healing in orthopaedic trauma research.

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.

A comparison of embalming fluids on the structures and properties of tissue in human cadavers.

Cadaveric material has long been used to teach anatomy and more recently to train students in clinical skills. The aim of this study was to develop a systematic approach to compare the impact of four embalming solutions on the tissues of human cadavers. To this end, a formalin-based solution, Thiel, Genelyn and Imperial College London soft-preservation (ICL-SP) solution were compared. The effect of these chemicals on the properties of the tissue was assessed by measuring the range of motion (ROM) of joints and measuring the dimensions of different structures on computed tomography (CT) images before and after embalming. The mean changes in the ratio (angle to ROM) differed statistically between embalming methods (Welch Statistic 3,1.672  = 67.213, p = 0.026). Thiel embalmed cadavers showed an increase in range of motion while ICL-SP cadavers remained relatively the same. Genelyn and formalin embalmed cadavers registered a notable decrease in range of motion. Furthermore, investigation into the impact of the embalming chemicals on the dimensions of internal organs and vessels revealed that Thiel embalming technique leads to a decrease in the dimension of the cardiovascular system alone while formalin-based solutions maintain the shape of the organs and vessels investigated. Our findings suggest that the joints of cadavers' embalmed using ICL-SP technique may faithfully mimic that of unembalmed cadavers and that formalin is necessary to retain shape and size of the organs and vessels investigated in this study. Despite this, a study with larger numbers of cadavers is required to confirm these findings.

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.

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.