In response to an ageing global population, the primary hip and knee arthroplasty rate continues to increase. Although an effective treatment, up to 25% patients may require revision arthroplasty during their lifetime, commonly due to periprosthetic loosening. Revision procedures are associated with significantly increased healthcare costs; therefore, timely and accurate diagnostics are critical for clinicians and patients. Loosening, which may be septic or aseptic, remains a challenge and requires thorough clinical examination and multimodal imaging evaluation. Plain radiographs remain an essential diagnostic tool but advanced imaging modalities such as computed tomography, magnetic resonance imaging and nuclear medicine are playing an increasingly important role. This comprehensive review, through outlining the available radiological modalities, their respective strengths and weaknesses and the pertinent imaging findings, may help radiologists and orthopaedic surgeons make more informed decisions in the management of periprosthetic loosening.

BACKGROUND Primary ciliary dyskinesia (PCD) is a rare condition characterised by dysmotile, immotile, or absent cilia. As a result of the impairment in respiratory mucociliary clearance, patients with PCD typically develop neonatal respiratory distress, nasal congestion, otitis media and recurrent respiratory infections leading to bronchiectasis and structural lung changes. These changes have been shown by chest computed tomography (CT) to develop in infancy and early childhood. Recent development and refinement of radiation-reducing CT techniques have allowed significant radiation dose reductions, with chest CT doses now in the range of chest radiography (CR). AIM To evaluate the efficacy of ultra-low dose CT (ULDCT) chest in identifying pulmonary changes within a PCD paediatric patient cohort. METHODS Paediatric patients with PCD who presented for routine clinical outpatient follow-up within the study period, were eligible for inclusion in the study. ULDCT and CR were performed on these patients and the results compared. Comparison metrics included radiation dose, subjective and objective image quality and disease severity. RESULTS Six paediatric patients (mean age 9 years) underwent clinically indicated ULDCT chest examinations and CR for surveillance of their PCD. The mean effective dose was 0.08 ± 0.02 mSv, a dose that approximates that of a frontal and lateral chest radiograph. The average Brody II score across the entire cohort was 12.92, with excellent inter-rater reliability and intra-class correlation coefficient (ICC) of 0.98. The average Chrispin-Norman score on CR was 1 with excellent inter-rater reliability and ICC of 0.92. CONCLUSION ULDCT demonstrates superior diagnostic capabilities, minimal radiation dose penalty, and high interobserver reliability in comparison to CR. Thus, we advocate for ULDCT to be the preferred modality for surveillance imaging in paediatric PCD.

Summary: In this study, we used routine ultra-low dose computed tomography scans of patients with cystic fibrosis to predict bone mineral density (BMD). A strong correlation was found between the attenuation of trabecular bone in thoracic vertebrae and the BMD in the proximal femur and lumbar spine as measured on DEXA. Purpose: Osteoporosis is a serious global health concern with millions of people affected worldwide. A particularly vulnerable cohort in developing osteoporosis are patients with cystic fibrosis (CF). Bone mineral density (BMD) is typically measured with dual energy X-ray absorptiometry (DEXA) scanning; however, this comes at a cost to the healthcare system and an exposure to ionising radiation. In our institution, patients with cystic fibrosis undergo routine ultra-low dose computed tomography (ULDCT) for monitoring of disease progression. The aim of this study was to assess the validity of estimating BMD using data derived from ULDCT scans. Methods: Adult CF patients were included if they had undergone a routine ULDCT scan within 12 months of a DEXA scan. Additionally, 100 non-CF patients with non-contrast standard dose CT scans were selected to act as the control group. Trabecular bone density (T-BD) at T4, T7 and T10 was measured on PACS in Hounsfield units (HU) and compared to DEXA scan results and a formula developed to the predict BMD. Results: Fifty-two female and 62 male patients were included with mean ages of 34.4 and 35.1 respectively. Moderately strong correlation was found between the T-BD and BMD of both the lumbar spine ( r = 0.629, p < 0.001) and proximal femur ( r = 0.649, p < 0.001). Receiver operator characteristic (ROC) curve analysis found a sensitivity and specificity of 0.700 and 0.714 respectively at predicting osteoporosis at T-BD of 193.33 HU or below. Conclusion: T-BD measured on ULDCT may be a valuable tool in the early identification of CF patients at risk of osteoporosis.

Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects the entire gastrointestinal (GI) tract from the mouth to anus and has an estimated incidence of up to 20 cases per 100 000. It is a chronic remitting disease associated with significant morbidity and increasing incidence worldwide. While endoscopy and biopsy form the cornerstone of diagnosis, cross-sectional imaging modalities such as ultrasound (US), CT, and MRI play a pivotal role in assessing disease extent and treatment response. Luminal complications such as stenoses, strictures, and complications such as fistula and abscesses are accurately detected and characterized non-invasively with these modalities. The appropriate use of imaging in CD, therefore, facilitates identification and localization of diseased bowel segments and detection of complications and associations such as sclerosing cholangitis and sacroiliitis. Due to undisputed value of cross-sectional imaging combined with the chronic remitting and relapsing nature of CD, patients often undergo large numbers of imaging studies throughout their lifetime for diagnostic and surveillance purposes. This includes plain radiography and CT scanning, both of which involve exposure to ionizing radiation. While the diagnostic information obtained from imaging is crucial for appropriate patient management, over a lifetime, patients with CD may be cumulatively exposed to high levels of ionizing radiation. Therefore, consideration of patient radiation safety is of great importance and should form part of the risk-benefit analysis preceding each imaging study in CD patients. Given the increasing incidence of Crohn’s disease, and the development and optimization of alternative imaging modalities in CD, which avoid radiation exposure, as well as the sustained advances in CT technology which facilitate radiation dose reduction, the preparation of this article is timely. This article aims to deliver an up-to-date overview of the role of imaging in Crohn’s disease and how consideration of radiation safety and radiation dose optimization impacts choice of imaging modality in CD.

Rationale: In cystic fibrosis (CF), body composition alterations are observed. The prevalence of obesity in CF is increasing, with evidence suggesting a subsequent increase in cardiometabolic risk. We sought to assess body composition using analytic morphomics from ultra-low–dose thoracic computed tomography (CT) scans in patients with CF on the triple CFTR (cystic fibrosis transmembrane conductance regulator) modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI). Objectives: Our objective was to use analytical morphomics on routine ultra-low–dose CTs to assess patterns of change in body composition in patients with CF on ETI therapy. Methods: Forty-two patients with CF on ETI who had baseline and follow-up ultra-low–dose thoracic CT imaging were retrospectively analyzed. The CTs were acquired at a radiation dose equivalent to two frontal chest X-rays using our previously published acquisition parameters. The Bhalla score was used as a marker of structural lung disease severity. Analytic morphomics variables, including cross-sectional area and attenuation of pectoralis muscle, visceral fat (epicardial and upper abdominal), and subcutaneous fat, were extracted using the validated image segmentation software CoreSlicer. Paired-samples mean testing (Wilcoxon matched-pairs signed-rank test) and Spearman rank correlation analyses were performed. Results: Total Bhalla scores significantly improved over time in patients on ETI (P < 0.0001). In addition, body composition also changed, with an increase in the cross-sectional area of subcutaneous and epicardial visceral fat (P < 0.0001 and P = 0.0062, respectively). In those with a normal BMI at follow-up, epicardial and subcutaneous fat had also increased significantly in the interval (P = 0.0066 and P = 0.0002, respectively). Conclusions: In CF, ETI produced a significant improvement in structural lung disease over time; however, it also resulted in an increase in visceral and subcutaneous fat. The analytic morphomics methodology presented herein may help identify those patients for aggressive primary prevention strategies and permit the creation of more personalized nutritional plans.

Background/Objectives: Non-enhanced computed tomography of the kidneys, ureters and bladder (NECT KUB) is the initial imaging modality for suspected nephroureterolithiasis. However, for alternative diagnoses, NECT may not be the ideal technique. Our institution changed the protocol for this cohort from NECT to intravenous contrast-enhanced CT (CECT) KUB. We aimed to retrospectively compare the rate of alternative diagnosis seen and the rates of calculus detection in CECT versus NECT KUB as a means of assessing performance. Our secondary aim was to compare the radiation dose between CECT and NECT KUB. Methods: Patients referred from the emergency department with suspected nephroureterolithiasis who underwent NECT and CECT KUB over two years were included. Key performance metrics included calculus detection rate, alternative findings, and negative studies. The metrics were compared between genders and age groups. Categorical variables were analysed using Chi-squared or Fisher’s Exact Test and continuous with T-testing. Results: A total of 423 patients had CT KUB imaging (209 NECT, 214 CECT). The incidence of alternative findings in the NECT group was 23% and 40% in CECT (p < 0.001). There were 48 findings (13 major, 11 moderate and 24 minor) in NECT studies and 85 findings (23 major, 43 moderate and 19 minor) in CECT (p < 0.001). Major diagnoses ranged from acute emergencies to more indolent findings, including suspicious nodules/masses. The calculus detection rate (NECT 56%, CECT 54%, p = 0.643) and negative studies (NECT 28%, CECT 22%, p = 0.168) did not significantly differ between protocols. CECT had a mean effective dose of 8.71 ± 2.58 mSv representing 2.4 times the exposure of NECT (p < 0.001). Conclusions: CECT is associated with a greater alternative diagnosis rate with similar calculus detection rates compared to NECT KUB, suggesting superior performance. However, CECT exposes patients to significantly greater levels of ionizing radiation.