Relevance of Motion Artifacts in Planning Computed Tomography on Outcomes After Transcatheter Aortic Valve Implantation.

Background: Motion artifacts in planning computed tomography (CT) for transcatheter aortic valve implantation (TAVI) can potentially skew measurements required for procedural planning. Whether such artifacts may affect safety or efficacy has not been studied. Methods: We conducted a retrospective analysis of 852 consecutive patients (mean age, 82 years; 47% women) undergoing TAVI-planning CT at a tertiary care center. Two independent observers divided CTs according to the presence of motion artifacts at the annulus level (Motion vs. Normal group). Endpoints included surrogate markers for inappropriate valve selection: annular rupture, valve embolization or misplacement, need for a new permanent pacemaker, paravalvular leak (PVL), postprocedural transvalvular gradient, all-cause death. Results: Forty-six (5.4%) patients presented motion artifacts on TAVI-planning CT (Motion group). These patients had more preexisting heart failure, moderate-severe mitral regurgitation, and atrial fibrillation. Interobserver variability of annular measurement (Normal vs. Motion group) did not differ for mean annular diameter but was significantly different for perimeter and area. Presence of motion artifacts on planning CT did not affect the prevalence of PVL (≥moderate PVL 0% vs. 2.5% p = 0.5), mean transvalvular gradient (6±3 mmHg vs 7±5 mmHg, p = 0.1), or the need for additional valve implantation (0% vs. 2.8%, p = 0.6). One annular rupture occurred (Normal group). Pacemaker implantation, procedural duration, hospital stay, 30-day outcomes, and all-cause mortality did not differ between the groups. Conclusions: Motion artifacts on planning CT were found in about 5% of patients. Measurements for valve selection were possible without the need for repeat CT, with mean diameter-derived annulus measurement being the most accurate. Motion artifacts were not associated with worse outcomes.

Incorporation of CAD (computer-aided detection) with thin-slice lung CT in routine 18F-FDG PET/CT imaging read-out protocol for detection of lung nodules.

OBJECTIVE: To evaluate the detection rate and performance of 18F-FDG PET alone (PET), the combination of PET and low-dose thick-slice CT (PET/lCT), PET and diagnostic thin-slice CT (PET/dCT), and additional computer-aided detection (PET/dCT/CAD) for lung nodules (LN)/metastases in tumor patients. Along with this, assessment of inter-reader agreement and time requirement for different techniques were evaluated as well. METHODS: In 100 tumor patients (56 male, 44 female; age range: 22-93 years, mean age: 60 years) 18F-FDG PET images, low-dose CT with shallow breathing (5 mm slice thickness), and diagnostic thin-slice CT (1 mm slice thickness) in full inspiration were retrospectively evaluated by three readers with variable experience (junior, mid-level, and senior) for the presence of lung nodules/metastases and additionally analyzed with CAD. Time taken for each analysis and number of the nodules detected were assessed. Sensitivity, specificity, positive and negative predictive value, accuracy, and Receiver operating characteristic (ROC) analysis of each technique was calculated. Histopathology and/or imaging follow-up served as reference standard for the diagnosis of metastases. RESULTS: Three readers, on an average, detected 40 LN in 17 patients with PET only, 121 LN in 37 patients using ICT, 283 LN in 60 patients with dCT, and 282 LN in 53 patients with CAD. On average, CAD detected 49 extra LN, missed by the three readers without CAD, whereas CAD overall missed 53 LN. There was very good inter-reader agreement regarding the diagnosis of metastases for all four techniques (kappa: 0.84-0.93). The average time required for the evaluation of LN in PET, lCT, dCT, and CAD was 25, 31, 60, and 40 s, respectively; the assistance of CAD lead to average 33% reduction in time requirement for evaluation of lung nodules compared to dCT. The time-saving effect was highest in the less experienced reader. Regarding the diagnosis of metastases, sensitivity and specificity combined of all readers were 47.8%/96.2% for PET, 80.0%/81.9% for PET/lCT, 100%/56.7% for PET/dCT, and 95.6%/64.3% for PET/CAD. No significant difference was observed regarding the ROC AUC (area under the curve) between the imaging methods. CONCLUSION: Implementation of CAD for the detection of lung nodules/metastases in routine 18F-FDG PET/CT read-out is feasible. The combination of diagnostic thin-slice CT and CAD significantly increases the detection rate of lung nodules in tumor patients compared to the standard PET/CT read-out. PET combined with low-dose CT showed the best balance between sensitivity and specificity regarding the diagnosis of metastases per patient. CAD reduces the time required for lung nodule/metastasis detection, especially for less experienced readers.

Usefulness of augmented reality in radiological protection education and training for interventional radiologists.

OBJECTIVE: The aim of this work is to evaluate the usefulness of using augmented reality (AR) to train medical professionals in radiological protection (RP) in fluoroscopy. METHODS: A Microsoft HoloLens 2 device has been used to simulate a fluoroscopic device. The teaching scenario considers a Philips Azurion able to rotate to pre-defined gantry positions,a dorsal decubitus patient and a ceiling shield. Radiation exposures were simulated using the FLUKA Monte Carlo code. 11 radiologists were asked to reproduce their positioning as per a clinical procedure and to correctly position the ceiling shield. Then, they were presented with the radiation exposure of their choices and were able to further optimise it. After the session, they were asked to complete a questionnaire. RESULTS: Users rated the AR educational approach as Intuitive and relevant to RP education (35%) and inspiring to deepen their knowledge (18%). Nevertheless, a negative aspect was mainly the difficulty in dealing with the system (58%). Although the participants were radiologists, a minority recognised themselves as having accurate knowledge of the RP (18%), indicating a relevant knowledge gap. CONCLUSION: The usefulness of using AR in RP education for radiologists has been shown. The visual aid of such technology is likely to improve the consolidation of practical knowledge. ADVANCES IN KNOWLEDGE: The use of interactive teaching techniques has the possibility to both help radiology professionals consolidate their radiation protection training and confidence in their practices.

3D Printed Percutaneous Transhepatic Cholangiography and Drainage (PTCD) Simulator for Interventional Radiology.

PURPOSE: Learning how to perform percutaneous transhepatic bile duct drainage (PTCD) is challenging for interventional radiology (IR) trainees. Therefore, simulators are crucial for IR training and are being increasingly demanded in the evolving healthcare environment of value-based care. To facilitate interventional training, we tried to evaluate our newly developed liver phantom for further use in IR training. METHODS: We developed a liver phantom with a flexible hollow biliary tree, hydrogel-based liver parenchyma, plastic ribs, and silicone skin. The phantom was evaluated by 20 radiology residents from two hospitals. After an introduction, all participants tried to obtain biliary access by fluoroscopic guidance within 25 min. Puncture time, fluoroscopy time, and kerma area product were measured. After 7 days, the participants repeated the procedure on an altered and more difficult model. Additionally, a survey was handed out to every participant (20 residents, 5 experts, and 5 IR fellows) to evaluate the phantom in terms of accuracy and haptic feedback, as well as general questions regarding simulation. RESULTS: The residents performed significantly faster and were more self-confident on Day 7 than on Day 1, significantly decreasing puncture time, fluoroscopy time, and kerma area product (p ≤ 0.0001). The participants were very satisfied with their simulation experience and would trust themselves more in real-life scenarios. CONCLUSION: We were able to develop a phantom with high anatomical accuracy for fluoroscopy and ultrasound-guided interventions. The phantom successfully helped residents learn and improve their PTCD performance.

Optimising whole body computed tomography doses for paediatric trauma patients: a Swiss retrospective analysis.

We aimed to evaluate the impact of a low-dose whole-body computed tomography (WBCT) protocol on radiation doses in paediatric major trauma patients. Retrospective cohort study of paediatric trauma patients (<16 years) at a national level 1 paediatric trauma centre (PTC) over a 6 year period prior and post introduction of a low-dose WBCT protocol (2014-2019). Demographic data, patient characteristics, CT device, and exposure information including scan range, dose-length product, and volume CT dose index were collected. Effective dose (ED) and exposure parameters were compared before and after protocol introduction. Forty-eight patients underwent WBCT during the study period. Prior to introduction of the low-dose protocol (n= 18), the ED was 20.6 mSv (median 20.1 ± 5.3 mSv [range 12.5-30.7]). After introduction of the low-dose WBCT protocol (n= 30), mean ED was 4.8 mSv (median 2.6 ± 5.0 [range: 0.8-19.1]). This resulted in a reduction of 77% in mean ED (pvalue <0.001). Significant radiation dose reduction of 77% can be achieved with low-dose WBCT protocols in PTCs.

Technical considerations and tips for using the Tegus remote proctoring system in elective and emergency cases and in webinars.

Smart angiography suites (SAS) refer to the incorporation of audio-video technology and internet connectivity into the angiography suite to enable bidirectional communication for teleproctoring. Remote streaming support (RESS) is intended to increase patient safety by supporting interventionalists with limited experience or who are practicing in geographically remote areas. The aim of this review is to describe real-life experience of the Tegus system and to share practical tips concerning its use and setup. We describe the platform itself, settings and integration in our angiography suite. We provide technical tips intended to help new and potential users to achieve an optimal experience for both neurointerventionalists and proctors. We describe both elective cases that we have performed with teleproctoring and emergencies. Lastly, we describe a different room setup and software solutions used in live workshops. Use of teleproctoring enabled involvement of proctors in cases where an already experienced interventionalist needed support in the decision-making process concerning the sizing and deployment of devices with which he was familiar only on a basic level. Excellent video feed quality and instant communication enabled optimal preparation and in vivo implantation of those devices without the need for physical proctors' presence. In emergency cases the system allowed a senior physician to offer support during cases where optimal device sizing is critical. Our usage concept of the rig permitted monitoring of thrombectomy cases by junior physicians. During webinars a remote streaming platform enabled us to conduct workshops that simulated an "on-site" experience as closely as possible during the COVID-19 pandemic.

Interventional treatment of biliodigestive anastomosis leaks with a modified percutaneous transhepatic cholangiodrainage.

INTRODUCTION: Biliodigestive leaks are typically caused by an insufficiency at the surgical anastomosis. Biliodigestive anastomosis (BDA) insufficiencies can lead to bilomas, abscesses and vascular erosion in chronic conditions. MATERIAL AND METHODS: We performed a retrospective analysis of the medical and radiological records of all patients with biliodigestive insufficiency who received interventional treatment between July 2015 and February 2021. Nine patients (three with unilateral drainage and six with bilateral drainage) were treated with a modified percutaneous transhepatic cholangiodrainage (PTCD). Clinical success was considered after complete resolution of the peribiliary collections, absence of bile within the surgical drains, radiological patency of the BDA (contrast medium flowing properly through the BDA and no signs of leakage) and haemodynamic stability of the patient without signs of sepsis. RESULTS: Clinical success was achieved in all nine patients. No patients required revision surgery to repair their BDA. The mean indwelling drainage time was 34.8±16.5 days. The mean number of interventional procedures performed per patient was 6.6±2.0. CONCLUSION: Patients who present with BDA insufficiency may benefit from interventional radiological techniques. Our modified PTCD resolved the BDA leak in all nine cases and should be considered as a valuable option for the treatment of patients with this complication. Our technique demonstrated to be feasible and effective.

Impact of the incorrect use of lead drapes on staff and patient doses in interventional radiology.

To evaluate the usefulness of commercially available scatter reduction drapes in mitigating staff exposure in interventional radiology and the potential harmful effects of drape malpositioning in terms of exposure levels to both patients and staff. An anthropomorphic phantom was irradiated on an angiography device under three scenarios: no drape and correct and incorrect drape positioning. Different levels of incorrect drape positioning relative to the field-of-view (FOV) were evaluated: slight, mild and severe. Real-time dosimeter systems (positioned on the operator's eye, chest and thyroid) were used to evaluate accumulative doses and dose rates. Different obstruction levels were evaluated and compared to the observer's perception. Additionally, patient exposure was evaluated for all scenarios using a dose area product (DAP). Up to a mild obstruction, by using the drape a dose reduction of up to 86% was obtained while a severe obstruction produced a 1000% increase in exposure, respectively for all dosimeter positions compared to the use of no drape. A similar order of magnitude was observed for patient exposure. Good agreement was obtained for the observer perception of the FOV obstruction up to 25% of the FOV; for larger obstructions, an overestimate of the obstruction was observed. Patient lead drapes can reduce staff doses in interventional radiology procedures even when mildly malpositioned and obscuring the FOV. Special attention to protective drape positioning is necessary, since the severe obstruction of the FOV results in a large increase in both operator and patient exposure.

The Columbus steerable guidewire in neurointerventions: early clinical experience and applications.

OBJECTIVE: To report our early experience in using the steerable 'Columbus' guidewire, also known as 'Drivewire' in the USA, and its potential applications in neurovascular interventions. METHODS: Neurointerventions in 36 patients (20 female, 16 male) using the steerable Columbus guidewire were recorded from August 2019 to December 2020 and included a variety of neurovascular procedures: Treatment of aneurysms (n=17), thrombectomy in acute ischemic stroke (n=12), and others (n=7), such as treatment of stenosis and embolization procedures. Immediate follow-up with digital subtraction angiography and tracking of each patient's clinical outcome was performed. RESULTS: In 35 out of 36 cases, the target vessel was reached with Columbus, including advancement of the appropriate microcatheter. In 14 cases, additional wires were used, mainly because of the nature of the procedures (eg, use of multiple wires/buddy wires or exchange maneuvers). In five cases, the Columbus wire was damaged by the operator and had to be replaced. Peri-interventional complications occurred in two patients, neither attributed to the Columbus guidewire. CONCLUSIONS: The new Columbus neurovascular guidewire has the unique ability to be shaped within the patient. Currently available versions lack torquability compared with other available guidewires but offer tremendous support at the tip, allowing maneuvers which are impossible with other wires on the market.

Applications of the Columbus steerable guidewire.

The Columbus steerable guidewire (Rapid Medical, Israel) is a 0.014 inch guidewire with a remotely controlled deflectable tip intended for neuronavigational purposes. 1 The tip can be shaped by pulling or pushing the handle. Pulling the handle decreases the radius (from 4 mm to 2 mm) and curves the tip, while pushing the handle increases the curvature radius and straightens the tip until it bends in the opposite direction. The amount of deflection is at the discretion of the operator. Video 1 The response of the Columbus guidewire to rotational movements is inferior to that of standard wires, and the tip is very soft and malleable but brings great support when bent. We present two cases where the Columbus guidewire was used. In the first case, the Columbus enabled us to probe a posterior cerebral artery arising from a giant basilar tip aneurysm without wall contact. In the second case, the Columbus was used as a secondary wire to help cannulate the pericallosal artery in a patient with a recurrent anterior complex aneurysm; this subsequently permitted successful stent-assisted coiling of the aneurysm. neurintsurg;14/10/1045/V1F1V1Video 1.

Fifty Shades of Scandium: Comparative Study of PET Capabilities Using Sc-43 and Sc-44 with Respect to Conventional Clinical Radionuclides.

Scandium-44 has been proposed as a valuable radionuclide for Positron Emission Tomography (PET). Recently, scandium-43 was introduced as a more favorable option, as it does not emit high-energy γ-radiation; however, its currently employed production method results in a mixture of scandium-43 and scandium-44. The interest in new radionuclides for diagnostic nuclear medicine critically depends on the option for image-based quantification. We aimed to evaluate and compare the quantitative capabilities of scandium-43/scandium-44 in a commercial PET/CT device with respect to more conventional clinical radionuclides (fluorine-18 and gallium-68). With this purpose, we characterized and compared quantitative PET data from a mixture of scandium-43/scandium-44 (~68% scandium-43), scandium-44, fluorine-18 and gallium-68, respectively. A NEMA image-quality phantom was filled with the different radionuclides using clinical-relevant lesion-to-background activity concentration ratios; images were acquired in a Siemens Biograph Vision PET/CT. Quantitative accuracy with scandium-43/scandium-44 in the phantom's background was within 9%, which is in agreement with fluorine-18-based PET standards. Coefficient of variance (COV) was 6.32% and signal recovery in the lesions provided RCmax (recovery coefficient) values of 0.66, 0.90, 1.03, 1.04, 1.12 and 1.11 for lesions of 10-, 13-, 17-, 22-, 28- and 37-mm diameter, respectively. These results are in agreement with EARL reference values for fluorine-18 PET. The results in this work showed that accurate quantitative scandium-43/44 PET/CT is achievable in commercial devices. This may promote the future introduction of scandium-43/44-labelled radiopharmaceuticals into clinical use.

Percutaneous transhepatic biliary puncture simulator: a cord network prototype.

BACKGROUND: The aim of this study was to present a percutaneous transhepatic biliary puncture simulator that can be used without radiation exposure and that reflects the conventional anatomy of the biliary ducts and its vicinity structures. METHODS: An anatomically based model of the biliary tree was developed using a cord network fixed to a wooden frame. The skin, ribs, intercostal muscles, and right lower lobe pleura were simulated using foam sponge, plastic tubes, a polystyrene foam panel, and an air pad, respectively. For the puncture, we used a 20-G Chiba needle and a wire with distal double arches; these were used to troll a cord, simulating the successful puncture of a bile duct. A camera was also placed above the model to allow the trainees to train eye-hand coordination while viewing the image on a monitor in real time. The simulator was tested with 60 radiology residents to evaluate the confidence and skills transferability of the training model. RESULTS: After receiving an introduction of the system and 5 min of training under tutor surveillance, all participants were able to troll a cord of the biliary simulator by themselves in less than 4 min. Only one participant punctured the simulated pleura. The participants' evaluations showed positive results, with increased user confidence and skills transferability after the training session. CONCLUSIONS: This proposed simulator can be an effective tool to improve a trainee's confidence and competence while achieving procedural and non-procedural interventional radiology skills related to the liver. TRIAL REGISTRATION: Retrospectively registered.

The value of intravenous contrast medium in PSMA PET/CT imaging in patients with biochemical recurrence of prostate cancer.

PURPOSE: To investigate the added value of diagnostic abdominal contrast-enhanced computed tomography (ceCT) in Ga-68 PSMA PET/CT in prostate cancer patients with biochemical recurrence (BCR). METHODS: Eighty-two consecutive patients (median age, 69 years; range, 45-86 years) with BCR underwent Ga-68 PSMA PET/CT with low-dose nonenhanced (ne) whole-body CT and diagnostic ceCT. Imaging results were retrospectively reviewed by two readers (R1, R2) for diagnostic certainty, local recurrence, lymph node metastasis (LNM) and bone metastasis. Interobserver agreement was assessed. Histopathology served as reference standard in 7, imaging and clinical follow-up in 65 and clinical follow-up alone in 10 patients. RESULTS: Certain local recurrence, LNM and bone metastasis diagnoses increased substantially from ceCT (R1: 5%/18%/32%; R2: 37%/50%/82%) to nePET/CT (R1: 78%/87%/93%; R2: 81%/87%/95%) for both readers, but the difference between nePET/CT and cePET/CT (R1: 77%/96%/92%; R2: 89%/94%/96%) was marginal. Interobserver agreement was minimal with ceCT (Krippendorff's alpha: 0.04-0.26), substantial with nePET/CT (0.60-0.86) and best with cePET/CT (0.76-0.86). The areas under the receiver operating characteristic curve (AUCs) for local recurrence for R1/R2 were 0.60/0.65 for ceCT, 0.81/0.79 for nePET/CT and 0.81/0.82 for cePET/CT. AUCs for LNMs for R1/R2 were 0.67/0.77 for ceCT, 0.91/0.82 for nePET/CT and 0.92/0.87 for cePET/CT. AUCs for BMs for R1/R2 were 0.60/0.53 for ceCT, 0.93/0.84 for nePET/CT and 0.93/0.86 for cePET/CT. CONCLUSION: Diagnostic abdominal ceCT increases the diagnostic certainty and interobserver agreement in Ga-68 PSMA PET/CT in BCR of prostate cancer. The diagnostic performance of cePET/CT is significantly better than ceCT alone but not nePET/CT.

Bronchoalveolar lavage-detected SARS-CoV-2 infection in presence of serial negative nasopharyngeal swabs: a case report.

We describe a case of a SARS coronavirus 2 (SARS-CoV-2) infection in a Swiss 54-years-old immunocompromised patient (lymphoma, therapy with the anti-CD20 antibody Rituximab® ), with initial scarce respiratory symptoms but typical coronavirus disease 2019 (COVID-19) radiological presentation, and symptoms onset during a holiday trip to Texas (USA). Three nasopharyngeal swabs in the 96 hours following hospital admission were negative, despite a CT thorax suggestive for an early stage of infection. COVID-infection was finally confirmed in the bronchoalveolar lavage (BAL) fluid, performed for exclusion of an alternative diagnosis in immunocompromised. In the BAL an increased cellularity with marked lymphocytosis of 35%, a reduced CD4/CD8 ratio of 0.1 and borderline neutrophilia of 3% were found. This finding might be due to the concomitant therapy with anti-CD20 antibodies, but the presence of lymphocytosis in the BAL despite peripheral lymphopenia with decreased CD4/CD8 T-cells ratio are described here for the first time in a SARS-CoV-2 infection. Persistent gastrointestinal symptoms (diarrhea), fever and initially headache were the predominant symptoms. The respiratory symptoms were scarce (variable mild dyspnea mMRC1). The respiratory conditions worsened during the hospital stay, with tachypnea up to 35/min, increased need for supplemental oxygen up to 8 L/min and worsening lung infiltrates on CT thorax on day 5. A therapy with hydroxychloroquine (HCQ) and an immunoglobulin-supplementation were given, with clinical and respiratory improvement, without need for intensive care or any ventilator support, and hospital discharge on day 16. Our case highlights some diagnostic and therapeutical challenges occurring in patients with COVID-19 infection. As take-home message, in the presence of clinical and radiological findings compatible with SARS-CoV-2 infection we outline the importance of treating patients accordingly, also in presence of repeated negative nasopharyngeal swabs. In selected patients as in our case a bronchoscopic BAL should be considered to exclude other infections, but in our opinion not primarily to confirming COVID-19 infection. Our unique finding of a lymphocytosis in the BAL during a COVID-19 infection needs further investigations.

Monitoring jaw osteomyelitis therapy with single-photon emission computed tomography/computed tomography.

OBJECTIVE: The aim of the study was to evaluate the value of single-photon emission computed tomography/computed tomography (SPECT/CT) for therapy response assessment of jaw osteomyelitis. MATERIALS AND METHODS: Thirty-four baseline and 74 follow-up SPECT/CT examinations for therapy response assessment were performed in 34 patients with jaw osteomyelitis. SPECT/CT and planar late-phase bone scintigraphy images were assessed at baseline and follow-up, according to the following criteria: tracer uptake grade (0 = no uptake, 1 = low uptake, 2 = moderate uptake and 3 = high uptake); and morphologic signs (osteolysis, sequestration, sclerosis, periosteal reaction and pathologic fracture). RESULTS: At baseline, SPECT/CT showed marked (grade 2 or 3) uptake in 91% (31/34) of the patients, osteolysis in 85% (29/34), sclerosis in 71% (24/34), periosteal reaction in 44% (15/34) and a sequestrum in 24% (8/34). In 24 patients with clinically complete remission during or after at least 12 months' therapy, bone scintigraphy showed grade 0 or 1 uptake in 100% (24/24) and SPECT/CT in 91% (22/24) of the patients. Sclerosis with the disappearance of osteolysis, sequestration and periosteal reactions was the predominant morphologic finding in complete responders (68%; 16/24). In 10 patients with symptoms of exacerbation of the osteomyelitis, 80% (8/10) showed increasing uptake, 90% (9/10) sclerosis, 80% osteolysis (8/10) and 40% (4/10) osteolysis and periosteal reactions. CONCLUSION: SPECT/CT is a valuable tool to accurately assess therapy response, disease exacerbation and complications of jaw osteomyelitis. Low-grade (grade 1) residual tracer uptake is common in patients with clinically complete remission and is suggestive of ongoing bone remodeling and healing.

Minimum perceivable size difference: how well can radiologists visually detect a change in lung nodule size from CT images?

OBJECTIVE: The purpose of this study was to determine how well radiologists could visually detect a change in lung nodule size on the basis of visual image perception alone. SUBJECTS AND METHODS: Under IRB approval, 109 standard chest CT image series were anonymized and exported from PACS. Nine hundred forty virtual lung nodule pairs (six baseline diameters, six relative volume differences, two nodule types-solid and ground glass-and 14 repeats) were digitally inserted into the chest CT image series (same location, different sizes between the pair). These digitally altered CT image pairs were shown to nine radiologists who were tasked to visually determine which image contained the larger nodule using a two-alternative forced-choice perception experimental design. These data were statistically analyzed using a generalized linear mixed effects model to determine how accurately the radiologists were able to correctly identify the larger nodule. RESULTS: Nominal baseline nodule diameter, relative volume difference, and nodule type were found to be statistically significant factors (p < 0.001) in influencing the radiologists' accuracy. For solid (ground-glass) nodules, the baseline diameter needed to be at least 6.3 mm (13.2 mm) to be able to visually detect a 25% change in volume with 95 ± 1.4% accuracy. Accuracy was lowest for the nodules with the smallest baseline diameters and smallest relative volume differences. Additionally, accuracy was lower for ground-glass nodules compared to solid nodules. CONCLUSIONS: Factors that impacted visual size assessment were baseline nodule diameter, relative volume difference, and solid versus non-solid nodule type, with larger and more solid lesions offering a more precise assessment of change. KEY POINTS: • For solid nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 6.3-mm baseline diameter. • For ground-glass nodules, radiologists could visually detect a 25% change in volume with 95% accuracy for nodules having greater than 13.2-mm baseline diameter. • Accuracy in detecting a change in nodule size began to stabilize around 90-100% for nodules with larger baseline diameters (> 8 mm for solid nodules, > 12 mm for ground-glass nodules) and larger relative volume differences (>15% for solid nodules, > 25% for ground-glass nodules).

Temperature-induced configuration changes in hydrogel-coated coils and their relevance in embolization procedures.

BACKGROUND: The present study attempted to demonstrate how the configuration of hydrogel-coated coils is influenced by different temperature exposures. Thirty detachable hydrogel-coated coils were evaluated in an in vitro water immersion test under five different temperature ranges (22.6 °C, 37 °C, 40-50 °C, 50-60 °C, and 60-70 °C). The configuration changes were classified (configuration I, configuration II, and configuration III) according to the curling that occurred during 30 min of immersion. Configuration stability of five Hydrogel-coated coils was also evaluated in a two-step temperature immersion test. RESULTS: All hydrogel-coated coils showed some configuration changes during water immersion. However, a logarithmic transformation of the time and temperature data showed a significant (p < 0.05) negative linear correlation between time and temperature for all coil configurations (configuration I: R = 0.97, configuration II: R = 0.98, configuration III: R = 0.97). The time needed to reach configuration III (complete coiling) was 160.4 ± 41.9 s at 37.5 °C (range: 100-205 s), 45.7 ± 22.2 s at 47.5 °C (range: 23-70 s), 20.2 ± 7.2 s at 57.5 °C (range: 14-32 s), and 10.3 ± 2.4 s at 67.5 °C (range: 7-13 s). CONCLUSIONS: Temperatures above 55 °C induced immediate configurational changes in the hydro-coated coils, achieving complete curling within less than 30 s. Temperatures near 36 °C (normal body temperature) require more time to reach optimal coil curling (configuration III). The optimization of HydroCoil preparation can reduce interventional procedural time and improve clinical results.

Imaging features and differential diagnoses of non-neoplastic diffuse mediastinal diseases.

Acute or chronic non-neoplastic diffuse mediastinal diseases have multiple causes, degrees of severity, and a wide range of management. Some situations require emergency care while others do not need specific treatment. Although the diagnosis may be suspected on chest X-ray, it is mainly based on CT. A delayed recognition is not uncommonly observed. Some findings may prompt the radiologist to look for specific associated injuries or lesions.This pictorial review will successively describe the various non-neoplastic causes of diffuse mediastinal diseases with their typical findings and major differentials.First, pneumomediastinum that can be provoked by extra- or intra-thoracic triggers requires the knowledge of patient's history or recent occurrences. Absence of any usual etiological factor should raise suspicion of cocaine inhalation in young individuals.Next, acute mediastinitis may be related to post-operative complications, esophageal perforation, or contiguous spread of odontogenic or retropharyngeal infections. The former diagnosis is not an easy task in the early stage, owing to the similarities of imaging findings with those of normal post-operative appearance during the first 2-3 weeks.Finally, fibrosing mediastinitis that is linked to an excessive fibrotic reaction in the mediastinum with variable compromise of mediastinal structures, in particular vascular and airway ones. Differential diagnosis includes tumoral and inflammatory infiltrations of the mediastinum.

COVID-19 and the role of imaging: early experiences in Central Switzerland.

The SARS-CoV-2 virus (COVID-19) was initially observed in a group of Chinese patients with unclear pneumonia in Wuhan, Hubei [1] in late December 2019. The first positive case in Switzerland was confirmed on 25 February 2020 in a patient from canton Tessin, who most likely caught the virus during a visit to Milan, Italy [2]. The country has since been preparing for an imminent public health emergency caused by the pandemic. As of 14 May 2020, the Swiss healthcare system is facing a total of 30,463 corona virus-positive people [3]. With numbers of new infections decreasing after the first pandemic wave, the continuing endemic situation will continue to be a major challenge for the Swiss healthcare system. It remains crucial to separate the clinically low-symptomatic from the severely affected patients in order to offer a specific therapeutic strategy to every SARS-CoV-2 patient. Reports from Chinese cohorts describe an increasing role of imaging strategies in the detection and surveillance of COVID-19 patients because of insufficient testing sensitivity of real-time reverse transcription polymerase chain reaction (RT-PCR) tests [4]. Chest computed tomography (CT), with a reported sensitivity of up to 97% [5, 6], gained importance particularly in patients with false negative RT-PCR results. In this short communication, we describe our first clinical experiences with 55 COVID-19 patients in Central Switzerland, who were either imaged with a standard chest x-ray, chest CT, or both. We provide an illustrative and schematic description of typical COVID-19 imaging features and suggest that imaging plays an important role in the clinical work-up of suspected or confirmed COVID-19 patients. This study was approved by the national ethics review committee (EKNZ, Switzerland) and patients’ informed consent was waived.