Accuracy of iodine quantification in dual energy CT: A phantom study across 3 different CT systems.

INTRODUCTION: No study has rigorously compared the performances of iodine quantification on recent CT systems employing different emission-based technologies, depending on the manufacturers and models. METHODS: A specific bespoke phantom was used for this study, with 12 known concentrations of iodinated contrast agent: 0.4, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 15.0, 20.0, 30.0 and 50.0 mg/mL. Three different dual-energy scanners were tested: one system using dual-source acquisition (CT#1) and two systems using Fast kilovolt-peak switching technology ± artificial intelligence (AI) reconstruction methods (CT#2 and #3) from two different manufacturers. For each system, helical scans were performed following recommended clinical protocols. Four acquisitions were performed per iodine concentration (mg/mL), and measurements were made on iodine-maps using ROIs. Mean measured values were compared to the known concentrations, and the absolute quantification error (AQE) and the relative percentage error (RPE) were used to compare the performances of each CT. RESULTS: The accuracy of the obtained measurements varied depending on the studied model but not on the acquisition mode (dual-source vs kVp switch ± AI). The quantification was more precise at high concentrations. RPE values were below 10 % with CT#2 (kVp switch) and below 25 % with CT#1 (dual-source), but were significantly higher with CT#3 (kVp switch + AI), exceeding 50 % at low concentrations (<3 mg/mL). CONCLUSIONS: With the help of a phantom, we identified variability in the results accuracy depending on the CT model, with sometimes significant deviation. Considering the performances of the different DECT technologies in iodine mapping, dual-source (CT#1) and kVp switch (CT#2) technologies appear more accurate than kVp switch technology combined with deep-learning-based reconstruction (CT#3) especially at low concentrations (<3 mg/mL). IMPLICATIONS FOR PRACTICE: As the primary and daily user of medical imaging devices, the radiographer role is to be attentive to the performance of imaging systems, particularly when performing quantitative acquisitions like iodine-quantification. In CT quantitative imaging (iodine map), it's essential for radiographers to consider their CT systems as measuring tools, and to be aware of their accuracies and limits.

"Triple low" free-breathing CTPA protocol for patients with dyspnoea.

AIM: To assess the performance of a "triple-low" free-breathing protocol for computed tomography pulmonary angiography (CTPA) evaluated on patients with dyspnoea and suspected pulmonary embolism and discuss its application in routine clinical practice for the study of the pulmonary parenchyma and vasculature. MATERIAL AND METHODS: This study was conducted on a selected group of dyspnoeic patients referred for CTPA. The protocol was designed using fast free-breathing acquisition and a small, fixed volume (35 ml) of contrast agent in order to achieve a low-exposure dose. For each examination, radiodensity of the pulmonary trunk and ascending aorta, and the dose-length product (DLP) were recorded. A qualitative analysis was performed of pulmonary arterial enhancement and the pulmonary parenchyma. RESULTS: This study included 134 patients. Contrast enhancement of the pulmonary arteries (409 ± 159 HU) was systematically >250 HU. The duration of acquisition ranged from 0.9 to 1.3 seconds for free-breathing imaging. The mean DLP was in the range of low-dose chest CT acquisitions (145 ± 73 mGy·cm). The analysis was deemed optimal in 90% (120/134) of cases for the pulmonary parenchyma. Sixty-nine per cent (92/134) of cases demonstrated homogeneous enhancement of the pulmonary arteries to the subsegmental level. Only 6% (8/134) of examinations were considered uninterpretable. CONCLUSION: The present "triple-low" CTPA protocol allows convenient analysis of the pulmonary parenchyma and arteries without hindrance by respiratory motion artefacts in dyspnoeic patients.

Why the preclinical imaging field needs nuclear medicine technologists and radiographers?

INTRODUCTION: Preclinical imaging is still seen as a new field, and its recognition as a specific topic occurring only about 20 years ago. Nuclear medicine technologists (NMTs) and radiographers' skills covering technical, anatomical and clinical fields can be highly beneficial to preclinical imaging research centres: many tasks and knowledge are complementary between clinics and preclinical laboratories. Our goal is to reach a consensus on the required set of competencies needed to translate the work of NMTs and radiographers from the clinic to the preclinical laboratory, particularly in regard to multimodal imaging. PRECLINICAL IMAGING ENVIRONMENT: Currently, all imaging modalities used in clinical routine (ultrasound, CT, MRI, PET, SPECT, radiographs) are available, using specific architectures allowing for the spatial resolution and sensitivity needed for small rodents (which are the most commonly used species in research). Ideally, a preclinical laboratory should produce images/examinations at a high throughput in order to meet the statistical expectations of the studies (while respecting the 3R principles for animal research) and the care and welfare of each individual. To reach the quality and throughput expectations of such an organization, specific qualified professionals are needed to complete the scientific/research staff. WHERE NMTS AND RADIOGRAPHERS FIT IN: The increasing use of preclinical imaging requires professionals who can put imaging procedures into action, ensuring a significant success throughput. NMTs and radiographers have a variety of skills that work well within a preclinical laboratory, with the ability to perform the following tasks independently: animal preparation, positioning, monitoring and anaesthesia recovery, acquisition parameter programming, archiving and data processing, device quality controls, surface cleaning and disinfection, radioactive and biological waste management, radiation safety for users, use of hot lab equipment and auxiliary equipment, injected products and material management. In light of the current European Qualification Framework, a set of skills, knowledge and competencies were defined to cover the whole set of duties and tasks deliverable to an NMT or radiographer working in a preclinical laboratory. One of the key responsibilities of the NMT or radiographer is related to compliance on animal care and welfare when undertaking any animal procedures, including imaging. CONCLUSION: We believe that NMTs and radiographers' skills match perfectly with the requirements of a preclinical imaging lab, and that they could be considered a keystone of such an organization in the future. Moreover, some evidence has also shown that an experienced NMT or radiographer in this sector can take on roles as research investigators.

Motivation of student radiographers in learning situations based on role-play simulation: A multicentric approach involving trainers and students.

INTRODUCTION: Role-play simulation is implemented in different radiography institutions. This tool develops Knowledge, Skills and Competences (KSC) in students. The aim of this study was to identify the strategies implemented by trainers in order to encourage student motivational dynamics and to find those that resonate with students. METHODS: Three role-play simulation sessions using a grid were observed in two different radiography institutions that have a simulation centre (two French institutions and one Swiss). In order to identify explicitly or implicitly the motivational strategies used, four interviews with trainers were conducted. To understand students' opinions about these strategies, seven interviews with radiography students were done. RESULTS: Defining motivation was not easy. The trainers used various strategies to motivate students, not all of which were verbalized in interviews. Although students said they were stressed prior to participating in role-play simulation, this study shows that such simulation sessions are effective to develop high motivational dynamics for students. CONCLUSION: This study has identified three main areas of improvement: exploring students' expectations, give importance to patients briefing so that they can fully perform their role and improving the authenticity of the environment. The latter issue can only be addressed through access to up-to-date equipment in training institutions.

An illustrative review to understand and manage metal-induced artifacts in musculoskeletal MRI: a primer and updates.

This article reviews and explains the basic physical principles of metal-induced MRI artifacts, describes simple ways to reduce them, and presents specific reduction solutions. Artifacts include signal loss, pile-up artifacts, geometric distortion, and failure of fat suppression. Their nature and origins are reviewed and explained though schematic representations that ease the understanding. Then, optimization of simple acquisition parameters is detailed. Lastly, dedicated sequences and options specifically developed to reduce metal artifacts (VAT, SEMAC, and MAVRIC) are explained.