Go Green in Neuroradiology: towards reducing the environmental impact of its practice.

Raising public awareness about the relevance of supporting sustainable practices is required owing to the phenomena of global warming caused by the rising production of greenhouse gases. The healthcare sector generates a relevant proportion of the total carbon emissions in developed countries, and radiology is estimated to be a major contributor to this carbon footprint. Neuroradiology markedly contributes to this negative environmental effect, as this radiological subspecialty generates a high proportion of diagnostic and interventional imaging procedures, the majority of them requiring high energy-intensive equipment. Therefore, neuroradiologists and neuroradiological departments are especially responsible for implementing decisions and initiatives able to reduce the unfavourable environmental effects of their activities, by focusing on four strategic pillars-reducing energy, water, and helium use; properly recycling and/or disposing of waste and residues (including contrast media); encouraging environmentally friendly behaviour; and reducing the effects of ionizing radiation on the environment. The purpose of this article is to alert neuroradiologists about their environmental responsibilities and to analyse the most productive strategic axes, goals, and lines of action that contribute to reducing the environmental impact associated with their professional activities.

Energy consumption in MRI: Determinants and management options.

BACKGROUND: Energy consumption awareness is a known concern, and radiology departments have energy-intensive consuming machines. The means of energy consumption management in MRI scanners have yet to be evaluated. PURPOSE: To measure the MRI energy consumption and to evaluate the means to reduce it. MATERIALS AND METHODS: Data was retrieved for two MRI scanners through the hospital's automated energy consumption measurement software. After correlation with picture archiving and communication system (PACS) files, they were segmented by machine and mode (as follows: stand-by, idle and active) and analyzed. Active mode data for a specific brain MRI protocol have been isolated, and equivalent low energy consuming protocol was made. Both were performed on phantom and compared. Same protocol was performed on a phantom using 3.0T 16 and 32 head channels coils. Multiples sequences were acquired on phantom to evaluate power consumption. RESULTS: Stand-by mode accounted for 60 % of machine time and 40 % of energy consumption, active mode accounted for 20 % machine time and 40 % energy consumption, idle mode for 20 % imachine time and 20 % consumption. DWI and TOF sequences were the most consuming in our brain-MRI protocol. The low energy consuming protocol allowed a saving of approximately 10 % of energy consumption, which amounted for 0.20€ for each examination. This difference was mainly due to an energy consumption reduction of the DWI sequence. There were no difference in consumption between a 3.0T 16 and 32 channels head coils. Sequence's active power and duration (especially considering slice thickness) have to be taken into account when trying to optimize energy consumption. CONCLUSION: There are two key factors to consider when trying to reduce MRI scan energy consumption. Stand-by mode energy consumption has to be taken into account when choosing an MRI scan, as it can't be changed further on. Active mode energy consumption is dependent of the MRI protocols used, and can be reduced with sequences adaptation, which must take into account sequence's active power and duration, on top of image quality.

CT analysis of skull contents in naturally mummified human corpses, a multicentric study.

INTRODUCTION: This study aimed to assess skull contents, brain appearance, and density on postmortem computed tomography in naturally mummified corpses. MATERIAL AND METHODS: For this purpose, a retrospective multicentric study, including mummified corpses from two French centers (Brest and Nantes) and from the New Mexico Decedent Image Database (USA), was performed by analyzing postmortem computed tomography (PMCT) focused on the head and neck of partially or fully mummified corpses discovered between 2011 and 2022. The PMCT analysis provided data on the CT appearance of brains, allowing them to be classified into four different categories (desiccation, liquefaction, dura mater only (DMO), and absence), and to measure densities (HU) of the brain remains. In addition, data on postmortem intervals (PMI) from Nantes and Brest centers were collected and analyzed to test the link between brain densities and PMIs. RESULTS: 54 cases of naturally mummified corpses were included. The brains were classified as liquefied (56%), desiccated (17 %), DMO (20 %), and absent (7 %) based on their CT appearance. Dehydrated brains were significantly (p < 0.004) denser (median 102 HU, interquartile range (IQR) 41) than either liquefied brains (median 39.5 HU, IQR 9) or brains with DMO (median -25 HU, IQR 57). However, the density of brain remains was not significantly affected by where the bodies were found (p = 0,41). Analysis of PMI and brain densities was performed on 22 cases. The results showed that brain remains were significantly (p = 0.039) denser when they were found after a PMI of more than six months. CONCLUSION: Brain desiccation was the aspect with the highest densities on PMCT, and for which we were able to highlight great preservation of anatomical structures observable in living organisms.

Angioplasty, stenting, or both - rescue maneuvers and reperfusion after endovascular therapy for intracranial atherosclerosis-related occlusion.

PURPOSE: Data concerning reperfusion strategies of intracranial atherosclerosis-related occlusion (ICARO) and clinico-angiographic outcomes remain scarce, particularly in Caucasians. We aim to compare the reperfusion rate and functional outcome between reperfusion strategies in the setting of the ICARO. METHODS: Retrospective analysis of prospectively maintained endovascular thrombectomy (EVT) registries at three high-volume stroke centers were retrospectively analyzed for consecutive ICARO patients from January 2015 to December 2019. We defined ICARO as any fixed high-degree (> 70%) focal narrowing or stenosis of any degree with a perpetual tendency for reocclusion. We categorized reperfusion strategies into four groups: EVT [group 1], balloon angioplasty [(BAp), group 2], placement of self-expandable stents [(SES), group 3], and BAp combined with implantation of SES; or direct placement of balloon mounted stents (BMS) [(BAp-SES/BMS), group 4]. We evaluated the association with the successful reperfusion [mTICI 2b - 3] and favorable outcome [mRS 0-2] with logistic regression analysis. RESULTS: Out of 2550 EVT, 124 patients (median age, 70 (61-80) years; 76 men) with ICARO and 130 reperfusion attempts [36 EVT, 38 BAp, 17 SES, and 39 BAp + SES/BMS] were analyzed. SES implantation showed the highest frequency of post-procedural symptomatic intracranial hemorrhage [(18%, 3/17), p = .03]; however, we observed no significant differences in the mortality rate. Overall, we achieved successful reperfusion in 71% (92/130) and favorable outcomes in 42% (52/124) of the patients. BAp + SES/BMS was the only independent predictor of the final successful reperfusion [aOR, 4.488 (95% CI, 1.364-14.773); p = .01], which was significantly associated with the 90-day favorable outcome [aOR, 10.837 (95% CI, 3.609-32.541); p = < .001] after adjustment for confounding variables between the reperfusion strategies. CONCLUSION: Among patients with ICARO, the rescue angioplasty stenting effectively contributed to higher odds of successful reperfusion with no increased risk for intracranial hemorrhage.

Complete recanalization predicts favorable outcome in patients with distal M2-M3 middle cerebral artery occlusions following endovascular thrombectomy.

BACKGROUND: - scanty articles illustrate the prognostic factors for favorable outcome after endovascular thrombectomy (EVT) in distal vessel occlusion (DMVO). Moreover, the current literature is diversified; conglomerating both primary, secondary, and anterior, posterior circulations embolic strokes in the same shell. PURPOSE: to identify the association between complete reperfusion and favorable outcome following EVT for DMVO in the middle cerebral artery (MCA) territory. METHODS: -we performed a retrospective analysis of prospectively maintained EVT registries at two comprehensive stroke centers between January 2015 and December 2019 for consecutive stroke patients with MCA-DMVO. DMVO was defined as an occlusion of distal M2 and M3 segments of the MCA. Only patients with primary isolated occlusions were included. A multivariate logistic regression was utilized to identify clinical and procedural-related factors associated with the 90-day favorable clinical outcome [defined as modified Rankin score (mRS) 0-2] after EVT. RESULTS: -Out of 1823 within the registries; 66 patients (median age was 72 (60-78) and 59% were males) with primary isolated DMVO of the MCA were eligible for inclusion in the current study. Complete reperfusion was achieved in 56% (37/66) of the patients with no difference among the reperfusion strategies while the favorable outcome was observed in 68% (45/66). In the multivariate analysis, final complete reperfusion [modified Thrombolysis In Cerebral Infarction (mTICI) score 2c-3] was significantly associated with favorable outcome [aOR=7.69; (95% CI 1.73-34.17); p=.01], while higher baseline NIHSS score [aOR=0.82; (95% CI 0.69-0.98); p=.03] and increased imaging to puncture interval [aOR=0.99; (95% CI 0.98, 1.00); p=.01] decreased the probability of the favorable outcome. CONCLUSION: according to our results, complete reperfusion was the most significant predictor of the favorable outcome, while higher baseline NIHSS and longer imaging to puncture interval decreased the probability of the favorable outcome.

Feasibility of use of medical dual energy scanner for forensic detection and characterization of explosives, a phantom study.

OBJECTIVE: Detection of explosives is a challenge due to the use of improvised and concealed bombs. Post-bomb strike bodies are handled by emergency and forensic teams. We aimed to determine whether medical dual-energy computed tomography (DECT) algorithm and prediction model can readily detect and distinguish a range of explosives on the human body during disaster victim identification (DVI) processes of bombings. MATERIALS AND METHODS: A medical DECT of 8 explosives (Semtex, Pastex, Hexamethylene triperoxide diamine, Acetone peroxide, Nitrocellulose, Pentrite, Ammonium Nitrate, and classified explosive) was conducted ex-vivo and on an anthropomorphic phantom. Hounsfield unit (HU), electron density (ED), effective atomic number (Zeff), and dual energy index (DEI),were compared by Wilcoxon signed rank test. Intra-class (ICC) and Pearson correlation coefficients (r) were computed. Explosives classification was performed through a prediction model with test-retest samples. RESULTS: Except for DEI (p = 0.036), means of HU, ED, and Zeff were not statistically different (p > 0.05) between explosives ex-vivo and on the phantom (r > 0.80). Intra- and inter-reader ICC were good to excellent: 0.806 to 0.997 and 0.890, respectively. Except for the phantom DEI, all measurements from each individual explosive differed significantly. HU, ED, Zeff, and DEI differed depending on the type of explosive. Our decision tree provided Zeff and ED for explosives classification with high accuracy (83.7%) and excellent reliability (100%). CONCLUSION: Our medical DECT algorithm and prediction model can readily detect and distinguish our range of explosives on the human body. This would avoid possible endangering of DVI staff.

Patent Foramen Ovale and Ischemic Stroke in Patients With Pulmonary Embolism: A Prospective Cohort Study.

Background: Pulmonary embolism (PE) is associated with increased risk for ischemic stroke, but the underlying mechanism remains unclear. The authors hypothesized that paradoxical embolism through patent foramen ovale (PFO) should be the main mechanism. Objective: To determine the frequency of recent ischemic stroke in patients with symptomatic PE according to whether PFO was detected. Design: Prospective cohort study with masked assessment of stroke outcomes. (ClinicalTrials.gov: NCT01216423). Setting: 4 French hospital centers. Participants: 361 consecutive patients with symptomatic acute PE from 13 November 2009 through 21 December 2015. Intervention: Systematic contrast transthoracic echocardiography (TTE) and cerebral magnetic resonance imaging (MRI) within 7 days after enrollment. Measurements: Recent symptomatic or silent ischemic stroke was diagnosed on the basis of clinical examination and cerebral MRI showing a hypersignal on the trace diffusion-weighted image with reduction or pseudonormalization of apparent diffusion coefficient. Results: Contrast TTE was conclusive in 324 of 361 patients and showed PFO in 43 patients (13%). The median age was 66 years (interquartile range, 54 to 77 years). In total, 51% of patients (145/284) had associated deep venous thrombosis, 91% (279/306) had cardiovascular risk factors, and 10% (16/151) presented with arrhythmia (no difference between PFO and non-PFO groups). Cerebral MRI was conclusive in 315 patients. Recent ischemic stroke was more frequent in the PFO group than in the non-PFO group (9 of 42 patients [21.4%] vs. 15 of 273 patients [5.5%]; difference in proportions, 15.9 percentage points [95% CI, 4.7 to 30.7 percentage points]). Limitation: Because of inconclusive contrast TTE or MRI, 46 patients were excluded from analysis. Conclusion: Frequency of recent ischemic stroke in patients with symptomatic PE was higher in patients with PFO than in those without PFO. This finding supports the hypothesis that paradoxical embolism is an important mechanism of ischemic stroke in patients with PFO. Primary Funding Source: French Ministry of Health.

Brain MRIs make up the bulk of the gadolinium footprint in medical imaging.

BACKGROUND AND PURPOSE: Assess the evolution of gadolinium consumption and magnetic resonance imaging (MRI) scanners in France and Western Brittany (France) and compare regional practices between public and private hospitals for each organ specialty. MATERIAL AND METHODS: We collected data from national and universal health registries, and Western Brittany's health care structures, between 2011 and 2018, about the number of MR imaging exams and machines, the number of delivered GBCAs (gadolinium-based contrast agents), prescriptions and administration protocols. RESULTS: Over the last eight years, we observed an increase in the number of MRI machines implemented in France (62%), correlated with the increase of annual gadolinium consumption (amount of delivered GBCAs in kg, 64%), without modification of the annual quantity of gadolinium used per machine (2.7kg in 2018). In Western Brittany, gadolinium impact is assigned to neuroimaging exams (50% CI95% [45;56] of all the contrast-enhanced exams), followed by thorax and abdomen exams (23% CI95% [18;28]). The ratio of injected exams to all exams is greater in public than in private hospitals (respectively 48% CI95% [46;49] versus 29% CI95% [26;30]). CONCLUSION: Gadolinium consumption is increasing, correlated with the increase in the number of examinations carried out. Regionally, the main impact comes from neuroimaging exams. No change in practices has been observed in recent years despite some warnings about gadolinium deposits and environmental consequences.

Central mechanisms of itch: A systematic literature review and meta-analysis.

In recent years, studying the central mechanism of itch has gained momentum. However, a proper meta-analysis has not been conducted in this domain. In this study, we tried to respond to this need. A systematic search and a meta-analysis were carried out to estimate the central mechanism of itch. The itch matrix comprises the thalamus and the parietal, secondary somatosensory, insular and cingulate cortices. We have shown that the basal ganglia (BG) play an important role in itch reduction. Finally, we explored itch processing in AD patients and observed that the itch matrix in these patients was different. In conclusion, this is the first meta-analysis on the central mechanisms of itch perception and processing. Our study demonstrated that different modalities of itch induction can produce a common pattern of activity in the brain and provided further insights into understanding the underlying nature of itch central perception.

Consensus Guidelines of the French Society of Neuroradiology (SFNR) on the use of Gadolinium-Based Contrast agents (GBCAs) and related MRI protocols in Neuroradiology.

Gadolinium-based contrast agents (GBCAs) are used in up to 35% of magnetic resonance imaging (MRI) examinations and are associated with an excellent safety profile. Nevertheless, two main issues have arisen in the last two decades: the risk of nephrogenic systemic fibrosis and the risk of gadolinium deposition and retention. As a first step, this article reviews the different categories of GBCAs available in neuroradiology, their issues, and provides updates regarding the use of these agents in routine daily practice. Recent advances in MRI technology, as well as the development of new MRI sequences, have made GBCA injection avoidable in many indications, especially in patients with chronic diseases when iterative MRIs are required and when essential diagnostic information can be obtained without contrast enhancement. These recent advances also lead to changes in recommended MRI protocols. Thus, in a second step, this review focuses on consensus concerning brain MRI protocols in 10 common situations (acute ischemic stroke, intracerebral hemorrhage, cerebral venous thrombosis, multiple sclerosis, chronic headache, intracranial infection, intra- and extra-axial brain tumors, vestibular schwannoma and pituitary adenoma). The latter allowing the standardization of practices in neuroradiology. Recommendations were also made concerning the use of GBCAs in neuroradiology, based on evidence in the literature and/or by consensus between the different coauthors.

Automated contour detection in spine radiographs and computed tomography reconstructions for forensic comparative identification.

This study was conducted to test an automated method to identify unknown individuals. It relies on a previous radiographic file and uses an edge-based comparison of lumbar CT/PMCT reconstructions and radiographs. The living group was composed of 15 clinical lumbar spine CT scans and 15 paired radiographs belonging to the same patients. The deceased group consisted of 5 lumbar spine PMCT scans and 5 paired antemortem radiographs of deceased individuals plus the 15 unpaired radiographs belonging to the living. An automated method using image filtering (anisotropic diffusion) and edge detection (Canny filter) provided image contours. Cross comparisons of all the exams in each group were performed using similarity measurements under the affine registration hypothesis. The Dice coefficient and Hausdorff distance values were significantly linked (p < 0.001 and p = 0.001 respectively) to the matched examinations in the living group (p < 0.001; pseudo-R2 = 0.70). 12 of the 15 examinations were correctly paired, 2 were wrongly paired and 3 were not paired when they must have been. In the deceased group, the Hausdorff distance was significantly linked (p = 0.018) to the matched examinations (p < 0.001; pseudo-R2 = 0.62; Dice coefficient p = 0.138). The paired examinations were all correctly found, but one was wrongly paired. The negative predictive value was above 98% for both groups. We highlighted the feasibility of comparative radiological identification using automated edge detection in cross-modality (CT/PMCT scan and radiographs) examinations. This method could be of significant help to a radiologist or coroner in identifying unknown cadavers.

A "one-stop-shop" 4D CTA protocol using 320-row CT for advanced imaging in acute ischemic stroke: a technical note.

This technical note describes a novel CT scan protocol that includes a non-enhanced CT, dynamic CTA, and perfusion of the whole brain and CTA of the carotid arteries using a 320-row area detector CT scanner, with a unique contrast injection and acceptable radiation exposure dose in patients presenting with acute ischemic stroke. The acquisition parameters and reconstruction parameters will be discussed including the use of model-based iterative reconstruction (MBIR), time summing (tMIP), and subtraction techniques to optimize the results of this protocol.Key Points• Scanning on a 320-row area detector CT can achieve both brain perfusion with dynamic angiography and reconstructed arterial and venous CTA, and supra aortic trunk angiography, in a single acquisition. • It provides, in a single exam, a full diagnostic workup, i.e., all the acquisitions that are needed to make a quick decision, with reasonable exposure to ionizing radiation and reduced amount of medium contrast, in case of acute ischemic stroke presentation.

Manual and Fully Automated Segmentation to Determine the Ferromagnetic Status of Bullets Using Computed Tomography Dual-Energy Index: A Phantom Study.

OBJECTIVE: The aim was to determine if dual-energy computed tomography (DECT) can discriminate ferromagnetic bullets from nonferromagnetic ones. METHODS: The ferromagnetic properties of 29 bullets were determined. All bullets underwent a DECT evaluation, and a manual measurement of the dual-energy index was performed by 2 radiologists, followed by a fully automatic measurement, in 3 different positions in a phantom (air, water, and bone). RESULTS: Twenty-one bullets were found to be nonferromagnetic. There were significant differences between the mean of the dual-energy index measured in the core of ferromagnetic projectiles and those of nonferromagnetic ones in the lung position of the phantom (P = 0.007). Specificity was 86.36%, and negative predictive value was 90.48%. Among the 29 bullets, 24 were correctly classified. CONCLUSIONS: Our study demonstrates that DECT can assess the ferromagnetic status of bullets and their magnetic resonance imaging compatibility using an extended computed tomography scale in an ex vivo phantom model.

Edge detector-based automatic segmentation of the skin layers and application to moisturization in high-resolution 3 Tesla magnetic resonance imaging.

INTRODUCTION: Previous studies have demonstrated the feasibility to explore moisturization with quantification imaging based on T2 mapping. The aim of this study was to describe and validate the first robust automated method to segment the first layers of the skin. MATERIALS AND METHODS: Data were picked from a previous study that included 35 healthy subjects who underwent a 3T MRI (multi spin echo calculation T2-weighted sequence) with a microscopic coil on the left heel before and one hour after moisturization. The automatic algorithm was composed of the T2 map generation, a Canny filter, a selection of boundaries, and a local regression to delimitate stratum corneum, epidermis, and dermis. An automated affine registration was applied between the exams before and after moisturization. RESULTS: The failure rate of the algorithm was below 5%. Mean computation time was 139.12s. There was a significant and strong correlation between the automatic measurements and the manual ones for the T2 values (ρ: 0.905, P < 0.001) and for the thickness measurements (ρ: 0.8663; P < 0.001). For registration, mean of the Dice index was 0.64 [0.47; 0.80] and of the Hausdorff distance was 0.29 mm 95% CI: [0.28; 0.30]. CONCLUSION: The proposed automatic method to study the first skin layers in 3T MRI using micro-coils was robust and described T2 values and thickness measurements with a strong correlation to manual measurements. The use of an automated affine registration could also permit the generation of a mapping for a visual assessment of moisturization.

Post-mortem X-ray computed tomography (PMCT) identification using ante-mortem CT-scan of the sphenoid sinus.

PURPOSE: To evaluate forensic identification of individuals through visual comparison of sphenoid sinus anatomical configuration using ante- and post-mortem CT-scans. METHOD AND MATERIALS: Ante- and post-mortem head CT-scan of 33 individuals were retrospectively collected. Ten head CT-scans were randomly selected from various neurological contexts and added to the ante-mortem group. Ten other head CT-scans were randomly selected from our post-mortem PACS and added to the post-mortem group. These CT-scans were assigned into 2 groups for analysis: an ante-mortem group (33 + 10) and a post-mortem group (33 + 10). For ethics and to avoid identification bias, CT-scans were anonymized - not showing any head structure but only sphenoid sinuses. An anatomical based classification system using the sphenoid sinuses anatomical variations was created according to anatomical and surgical literature. This classification was used by readers to identify in two different steps a maximum of matched and then unmatched scans. RESULTS: The first reader had a sensitivity of 100% [CI: 89.4%-100%] and a specificity of 100% [CI: 99.8%-100%]. Sensitivity and specificity were respectively 93.9% [CI: 79.8%-99.3%] and 99.9% [CI: 99.6%-100%] for the second reader. Positive and negative predictive values were respectively 100% [CI: 89.4%-100%] and 100% [CI: 99.8%-100%] for the first reader. Positive and negative values were respectively 96.9% [CI: 83.8%-99.9%] and 99.9% [CI: 99.7%-100%] for the second reader. Inter-reader variability was estimated by Cohen's kappa and an excellent agreement was found. CONCLUSION: We reported an excellent validity and reliability of subjective visual comparison of ante- and post-mortem CT-data using an anatomical based classification of the sphenoid sinus.

A new time-resolved 3D angiographic technique (4D DSA): Description, and assessment of its reliability in Spetzler-Martin grading of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: The Spetzler and Martin (SM) cerebral arteriovenous malformation (AVM) classification is a widely used 5-tier classification. This common language allows specialists to exchange about AVMs and must be reliably characterized by the imaging methods. We presented an agreement study on a new method of digital subtracted 3D rotational angiography resolved in time (four-dimensional DSA: 4D DSA) compared to the gold standard (two-dimensional DSA: 2D DSA) in AVM grading using the SM classification. METHODS: Ten patients with AVMs were included during one year, they had an angiographic exploration with both 4D DSA and 2D DSA. Three readers assessed the SM classification. One reader conducted a second reading. The inter-, intra-observer and intermodality agreements were calculated by Kappas. Dose to patient was reported. RESULTS: Considering the SM grade, the inter-observer agreement between 4D DSA and 2D DSA was equivalent (κ=0.45 and 0.46), and calculated as substantial κ=0.76 between the 2 methods. The agreement between 4D DSA and 2D DSA was calculated as moderate κ=0.46 assessing the size of the nidus, slight κ=0.18 analyzing the drainage and almost perfect κ=0.95 depicting the localization. 4D DSA performed during a standard initial angiographic assessment of AVM represented approximately 6% of the total dose. CONCLUSION: The addition of this new technique 4D DSA could be performed regularly in addition to the 2D DSA if available, to assess SM grading, with an acceptable exposure to ionizing radiation.

Central nervous system MRI and cardiac implantable electronic devices.

As the population ages and indications for MRI increase, it is estimated that 50 to 75% of patients with a cardiac implantable electronic device (CIED) - pacemaker (PM) or implanted cardiac defibrillator (ICD) - will need an MRI during their CIED's lifetime. Three categories of materials are defined: MRI compatible, MRI non-compatible, and MRI conditional. MRI compatible CIEDs without electrodes have been developed, but do not allow battery changes, so that they are exclusively indicated for patients whose life expectancy is less than that of the battery (6-7years). For MRI conditional CIEDs, all manufacturers publish restrictions. These restrictions can relate to the patient (size, position in the MRI, body temperature), the MRI parameters (magnetic field), or the examination in itself (gradients, specific absorption rate, duration, isocenter). The neuroradiologist can expect to be confronted with the issue of MRI in patients with a CIED. The purpose of this review is to provide them with updated information on MRI and CIEDs.