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Objectives: CT perfusion (CTP) has been suggested to increase the rate of large vessel occlusion (LVO) detection in patients suspected of acute ischemic stroke (AIS) if used in addition to a standard diagnostic imaging regime of CT angiography (CTA) and non-contrast CT (NCCT). The aim of this study was to estimate the costs and health effects of additional CTP for endovascular treatment (EVT)–eligible occlusion detection using model-based analyses. Methods: In this Dutch, nationwide retrospective cohort study with model-based health economic evaluation, data from 701 EVT-treated patients with available CTP results were included (January 2018–March 2022; trialregister.nl:NL7974). We compared a cohort undergoing NCCT, CTA, and CTP (NCCT + CTA + CTP) with a generated counterfactual where NCCT and CTA (NCCT + CTA) was used for LVO detection. The NCCT + CTA strategy was simulated using diagnostic accuracy values and EVT effects from the literature. A Markov model was used to simulate 10-year follow-up. We adopted a healthcare payer perspective for costs in euros and health gains in quality-adjusted life years (QALYs). The primary outcome was the net monetary benefit (NMB) at a willingness to pay of €80,000; secondary outcomes were the difference between LVO detection strategies in QALYs (ΔQALY) and costs (ΔCosts) per LVO patient. Results: We included 701 patients (median age: 72, IQR: [62–81]) years). Per LVO patient, CTP-based occlusion detection resulted in cost savings (ΔCosts median: € − 2671, IQR: [€ − 4721; € − 731]), a health gain (ΔQALY median: 0.073, IQR: [0.044; 0.104]), and a positive NMB (median: €8436, IQR: [5565; 11,876]) per LVO patient. Conclusion: CTP-based screening of suspected stroke patients for an endovascular treatment eligible large vessel occlusion was cost-effective. Clinical relevance statement.: Although CTP-based patient selection for endovascular treatment has been recently suggested to result in worse patient outcomes after ischemic stroke, an alternative CTP-based screening for endovascular treatable occlusions is cost-effective. Key Points: • Using CT perfusion to detect an endovascular treatment-eligible occlusions resulted in a health gain and cost savings during 10 years of follow-up. • Depending on the screening costs related to the number of patients needed to image with CT perfusion, cost savings could be considerable (median: € − 3857, IQR: [€ − 5907; € − 1916] per patient). • As the gain in quality adjusted life years was most affected by the sensitivity of CT perfusion-based occlusion detection, additional studies for the diagnostic accuracy of CT perfusion for occlusion detection are required. [ABSTRACT FROM AUTHOR]

Whether the fascia iliaca compartment block (FICB) involves the obturator nerve (ON) remains controversial. Involvement may require that the injectate spreads deep in the cranial direction, and might thus depend on the site of injection. Therefore, the effect of suprainguinal needle insertion with five centimeters of hydrodissection-mediated needle advancement (S-FICB-H) on ON involvement and cranial injectate spread was studied in this radiological cadaveric study. Results were compared with suprainguinal FICB without additional hydrodissection-mediated needle advancement (S-FICB), infrainguinal FICB (I-FICB), and femoral nerve block (FNB). Seventeen human cadavers were randomized to receive ultrasound-guided nerve block with a 40 mL solution of local anesthetic and contrast medium, on both sides. Injectate spread was objectified using computed tomography. The femoral and lateral femoral cutaneous nerves were consistently covered when S-FICB-H, S-FICB or FNB was applied, while the ON was involved in only one of the 34 nerve blocks. I-FICB failed to provide the same consistency of nerve involvement as S-FICB-H, S-FICB or FNB. Injectate reached most cranial in specimens treated with S-FICB-H. Our results demonstrate that even the technique with the most extensive cranial spread (S-FICB-H) does not lead to ON involvement and as such, the ON seems unrelated to FICB. Separate ON block should be considered when clinically indicated. [ABSTRACT FROM AUTHOR]

Background and Purpose: Intracranial collateral capacity is conducive to imply parenchymal perfusion of affected territory after acute vessel occlusion. The Tan collateral score is commonly used to assess the intracranial collateral capacity; however, this score is coarsely grained and interobserver agreement is low, which reduces prognostic value and clinical utility. We introduce and evaluate an alternative extended Tan score based on the conventional Tan scale and assess the agreement with a quantitative score. Methods: We included 100 consecutive patients with a proven acute single large vessel occlusion of the proximal anterior circulation. Collaterals were graded with the conventional and extended Tan score and an automated quantitative score. The extended Tan score is a finer 6‑scale manual score based on the conventional 4‑point Tan scale. The quantitative score is calculated by an automatic software package (StrokeViewer). Interobserver agreement of the manual scores was assessed with the weighted kappa. The Spearman correlation coefficient was calculated to determine the agreement between the manual and automated collateral scores. Results: The interobserver agreement was higher for the extended score than for the conventional score with a weighted kappa of 0.70 and 0.65, respectively. For the extended and conventional score, the Spearman correlation coefficient for the agreement with the automated score was 0.78 and 0.76, respectively. Conclusion: Because of the good interobserver agreement and good agreement with quantitative assessment, the extended collateral score is a strong candidate to improve prognostic value of collateral assessment and implementation in clinical practice. [ABSTRACT FROM AUTHOR]

Background: Computed tomography perfusion (CTP) is frequently performed during the diagnostic workup of acute ischemic stroke patients. Yet, ischemic core estimates vary widely between different commercially available software packages. We assessed the volumetric and spatial agreement of the ischemic core on CTP with the follow-up infarct on diffusion-weighted imaging (DWI) using an automated software. Methods: We included successfully reperfused patients who underwent endovascular treatment (EVT) with CTP and follow-up DWI between November 2017 and September 2020. CTP data were processed with a fully automated software using relative cerebral blood flow (rCBF) < 30% to estimate the ischemic core. The follow-up infarct was segmented on DWI imaging data, which were acquired at approximately 24 h. Ischemic core on CTP was compared with the follow-up infarct lesion on DWI using intraclass correlation coefficient (ICC) and Dice similarity coefficient (Dice). Results: In 59 patients, the median estimated core volume on CTP was 16 (IQR 8–47) mL. The follow-up infarct volume on DWI was 11 (IQR 6–42) mL. ICC was 0.60 (95% CI 0.33–0.76), indicating moderate volumetric agreement. Median Dice was 0.20 (IQR 0.01–0.35). The median positive predictive value was 0.24 (IQR 0.05–0.57), and the median sensitivity was 0.3 (IQR 0.13–0.47). Severe core overestimation on computed tomography perfusion > 50 mL occurred in 4/59 (7%) of the cases. Conclusions: In patients with successful reperfusion after EVT, CTP-estimated ischemic core showed moderate volumetric and spatial agreement with the follow-up infarct lesion on DWI, similar to the most used commercially available CTP software packages. Severe ischemic core overestimation was relatively uncommon. Key points: CTP-estimated ischemic core has moderate volumetric and spatial agreement with the infarct lesion on 24 h follow-up DWI. The studied CTP software shows similar performance to the most used CTP softwares and can be used interchangeably. Severe ischemic core overestimation by the CTP software was relatively uncommon. [ABSTRACT FROM AUTHOR]

Objectives: Closer reading of computed tomography pulmonary angiography (CTPA) scans of patients presenting with acute pulmonary embolism (PE) may identify those at high risk of developing chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to validate the predictive value of six radiological predictors that were previously proposed. Methods: Three hundred forty-one patients with acute PE were prospectively followed for development of CTEPH in six European hospitals. Index CTPAs were analysed post hoc by expert chest radiologists blinded to the final diagnosis. The accuracy of the predictors using a predefined threshold for 'high risk' (≥ 3 predictors) and the expert overall judgment on the presence of CTEPH were assessed. Results: CTEPH was confirmed in nine patients (2.6%) during 2-year follow-up. Any sign of chronic thrombi was already present in 74/341 patients (22%) on the index CTPA, which was associated with CTEPH (OR 7.8, 95%CI 1.9–32); 37 patients (11%) had ≥ 3 of 6 radiological predictors, of whom 4 (11%) were diagnosed with CTEPH (sensitivity 44%, 95%CI 14–79; specificity 90%, 95%CI 86–93). Expert judgment raised suspicion of CTEPH in 27 patients, which was confirmed in 8 (30%; sensitivity 89%, 95%CI 52–100; specificity 94%, 95%CI 91–97). Conclusions: The presence of ≥ 3 of 6 predefined radiological predictors was highly specific for a future CTEPH diagnosis, comparable to overall expert judgment, while the latter was associated with higher sensitivity. Dedicated CTPA reading for signs of CTEPH may therefore help in early detection of CTEPH after PE, although in our cohort this strategy would not have detected all cases. Key Points: • Three expert chest radiologists re-assessed CTPA scans performed at the moment of acute pulmonary embolism diagnosis and observed a high prevalence of chronic thrombi and signs of pulmonary hypertension. • On these index scans, the presence of ≥ 3 of 6 predefined radiological predictors was highly specific for a future diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH), comparable to overall expert judgment. • Dedicated CTPA reading for signs of CTEPH may help in early detection of CTEPH after acute pulmonary embolism. [ABSTRACT FROM AUTHOR]

Purpose: Follow-up infarct volume (FIV) is moderately associated with functional outcome. We hypothesized that accounting for infarct location would strengthen the association of FIV with functional outcome. Methods: We included 252 patients from the HERMES collaboration with follow-up diffusion weighted imaging. Patients received endovascular treatment combined with best medical management (n = 52%) versus best medical management alone (n = 48%). FIV was quantified in low, moderate and high modified Rankin Scale (mRS)-relevant regions. We used binary logistic regression to study the relation between the total, high, moderate or low mRS-relevant FIVs and favorable outcome (mRS < 2) after 90 days. The strength of association was evaluated using the c-statistic. Results: Small lesions only occupied high mRS-relevant brain regions. Lesions additionally occupied lower mRS-relevant brain regions if FIV expanded. Higher FIV was associated with a higher risk of unfavorable outcome, as were volumes of tissue with low, moderate and high mRS relevance. In multivariable modeling, only the volume of high mRS-relevant infarct was significantly associated with favorable outcome. The c-statistic was highest (0.76) for the models that included high mRS-relevant FIV or the combination of high, moderate and low mRS-relevant FIV but was not significantly different from the model that included only total FIV (0.75). Conclusion: This study confirms the association of FIV and unfavorable functional outcome but showed no strengthened association if lesion location was taken into account. [ABSTRACT FROM AUTHOR]

COVID-19 patients have increased risk of pulmonary embolism (PE), but symptoms of both conditions overlap. Because screening algorithms for PE in COVID-19 patients are currently lacking, PE might be underdiagnosed. We evaluated a screening algorithm in which all patients presenting to the ED with suspected or confirmed COVID-19 routinely undergo D-dimer testing, followed by CT pulmonary angiography (CTPA) if D-dimer is ≥ 1.00 mg/L. Consecutive adult patients presenting to the ED of two university hospitals in Amsterdam, The Netherlands, between 01-10-2020 and 31-12-2020, who had a final diagnosis of COVID-19, were retrospectively included. D-dimer and CTPA results were obtained. Of 541 patients with a final diagnosis of COVID-19 presenting to the ED, 25 (4.6%) were excluded because D-dimer was missing, and 71 (13.1%) because they used anticoagulation therapy. Of 445 included patients, 185 (41.6%; 95%CI 37.0–46.3) had a D-dimer ≥ 1.00 mg/L. CTPA was performed in 169 of them, which showed PE in 26 (15.4%; 95%CI 10.3–21.7), resulting in an overall detection rate of 5.8% (95%CI 3.9–8.4) in the complete study group. In patients with and without PE at CTPA, median D-dimer was 9.84 (IQR 3.90–29.38) and 1.64 (IQR 1.17–3.01), respectively (p < 0.001). PE prevalence increased with increasing D-dimer, ranging from 1.2% (95%CI 0.0–6.4) if D-dimer was 1.00–1.99 mg/L, to 48.6% (95%CI 31.4–66.0) if D-dimer was ≥ 5.00 mg/L. In conclusion, by applying this screening algorithm, PE was identified in a considerable proportion of COVID-19 patients. Prospective management studies should assess if this algorithm safely rules-out PE if D-dimer is < 1.00 mg/L. [ABSTRACT FROM AUTHOR]

Background: Accumulated airway secretions in the endotracheal tube increase work of breathing and may favor airway colonization eventually leading to pneumonia. The aim of this preplanned substudy of the 'Preventive Nebulization of Mucolytic Agents and Bronchodilating Drugs in Intubated and Ventilated Intensive Care Unit Patients trial' (NEBULAE) was to compare the effect of routine vs on-demand nebulization of acetylcysteine with salbutamol on accumulation of secretions in endotracheal tubes in critically ill patients. Results: In this single-center substudy of a national multicenter trial, patients were randomized to a strategy of routine nebulizations of acetylcysteine with salbutamol every 6 h until end of invasive ventilation, or to a strategy with on-demand nebulizations of acetylcysteine or salbutamol applied on strict clinical indications only. The primary endpoint, the maximum reduction in cross-sectional area (CSA) of the endotracheal tube was assessed with high-resolution computed tomography. Endotracheal tubes were collected from 72 patients, 36 from patients randomized to the routine nebulization strategy and 36 of patients randomized to the on-demand nebulization strategy. The maximum cross-sectional area (CSA) of the endotracheal tube was median 12 [6 to 15]% in tubes obtained from patients in the routine nebulization group, not different from median 9 [6 to 14]% in tubes obtained from patients in the on-demand nebulization group (P = 0.33). Conclusion: In adult critically ill patients under invasive ventilation, routine nebulization of mucolytics and bronchodilators did not affect accumulation of airway secretions in the endotracheal tube. Trial registration Clinicaltrials.gov Identifier: NCT02159196 [ABSTRACT FROM AUTHOR]

Background: A challenge in imaging research is a diagnostic classification of study participants. We hypothesised that a structured approach would be efficient and that classification by medical students, residents, and an expert panel whenever necessary would be as valid as classification of all patients by experts. Methods: OPTIMACT is a randomised trial designed to evaluate the effectiveness of replacing chest x-ray for ultra-low-dose chest computed tomography (CT) at the emergency department. We developed a handbook with diagnostic guidelines and randomly selected 240 cases from 2,418 participants enrolled in OPTIMACT. Each case was independently classified by two medical students and, if they disagreed, by the students and a resident in a consensus meeting. Cases without consensus and cases classified as complex were assessed by a panel of medical specialists. To evaluate the validity, 60 randomly selected cases not referred to the panel by the students and the residents were reassessed by the specialists. Results: Overall, the students and, if necessary, residents were able to assign a diagnosis in 183 of the 240 cases (76% concordance; 95% confidence interval [CI] 71–82%). We observed agreement between students and residents versus medical specialists in 50/60 cases (83% concordance; 95% CI 74–93%). Conclusions: A structured approach in which study participants are assigned diagnostic labels by assessors with increasing levels of medical experience was an efficient and valid classification method, limiting the workload for medical specialists. We presented a viable option for classifying study participants in large-scale imaging trials (Netherlands National Trial Register number NTR6163). [ABSTRACT FROM AUTHOR]

Objectives: Initial trauma care could potentially be improved when conventional imaging and selective CT scanning is omitted and replaced by immediate total-body CT (iTBCT) scanning. Because of the potentially increased radiation exposure by this diagnostic approach, proper selection of the severely injured patients is mandatory.Methods: In the REACT-2 trial, severe trauma patients were randomized to iTBCT or conventional imaging and selective CT based on predefined criteria regarding compromised vital parameters, clinical suspicion of severe injuries, or high-risk trauma mechanisms in five trauma centers. By logistic regression analysis with backward selection on the 15 study inclusion criteria, a revised set of criteria was derived and subsequently tested for prediction of severe injury and shifts in radiation exposure.Results: In total, 1083 patients were enrolled with median ISS of 20 (IQR 9-29) and median GCS of 13 (IQR 3-15). Backward logistic regression resulted in a revised set consisting of nine original and one adjusted criteria. Positive predictive value improved from 76% (95% CI 74-79%) to 82% (95% CI 80-85%). Sensitivity decreased by 9% (95% CI 7-11%). The area under the receiver operating characteristics curve remained equal and was 0.80 (95% CI 0.77-0.83), original set 0.80 (95% CI 0.77-0.83). The revised set retains 8.78 mSv (95% CI 6.01-11.56) for 36% of the non-severely injured patients.Conclusions: Selection criteria for iTBCT can be reduced from 15 to 10 clinically criteria. This improves the positive predictive value for severe injury and reduces radiation exposure for less severely injured patients.Key Points: • Selection criteria for iTBCT can be reduced to 10 clinically useful criteria. • This reduces radiation exposure in 36% of less severely injured patients. • Overall discriminative capacity for selection of severely injured patients remained equal. [ABSTRACT FROM AUTHOR]

Consecutive adults scheduled to undergo abdominal CT with oral contrast were asked to choose between 1000 ml water only or positive oral contrast (50 ml Télébrix-Gastro diluted in 950 ml water). Two abdominal radiologists independently reviewed each scan for image quality of the abdomen, the diagnostic confidence per system (gastrointestinalsystem/organs/peritoneum/retroperitoneum/lymph nodes) and overall diagnostic confidence to address the clinical question (not able/partial able/fully able). Radiation exposure was extracted from dose reports. Differences between both groups were evaluated by Student's t-test, Mann-Whitney-U-test or chi-square-test. Of the 320participants, 233chose water only. All baseline characteristics, image quality of the abdomen and the diagnostic confidence of the organs were comparable between groups and both observers. Diagnostic confidence in the water only group was more commonly scored as less than good by observer1. The results were as follows: the gastrointestinal system(18/233vs1/87; p = 0.031), peritoneum (21/233vs1/87; p = 0.012), retroperitoneum (11/233vs0/87; p = 0.040) and lymph nodes (11/233vs0/87; p = 0.040). These structures were scored as comparable between both groups by observer2. The diagnostic confidence to address the clinical question could be partially addressed in 6/233 vs 0/87 patients (p = 0.259). The water only group showed a tendency towards less radiation exposure. In summary, most scan ratings were comparable between positive contrast and water only, but slightly favored positive oral contrast for one reader for some abdominal structures. Therefore, water only can replace positive oral contrast in the majority of the outpatients scheduled to undergo an abdominal CT. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to review and compare the image quality and radiation dose of split-bolus single-pass computed tomography(CT) in the assessment of trauma patients in comparison to standard multi-phase CT techniques.Methods: An online electronic database was searched using the MESH terms "split-bolus," "dual phase," and "single pass." Inclusion criteria required the research article to compare a split contrast bolus protocol in a single-pass scan in the assessment of trauma patients. Studies using split-bolus CT technique in non-traumatic injury assessment were excluded. Six articles met the inclusion criteria.Conclusions: Parenchymal and vascular image qualities, as well as subjective image quality assessments, were equal or superior in comparison to non-split-bolus multi-phase trauma CT protocols. Split-bolus single-pass CT decreased radiation exposure in all studies. Further research is required to determine the superior split-bolus protocol and the specificity and sensitivity of detecting blunt cerebrovascular injury screening, splenic parenchymal vascular lesions, and characterization of pelvic vascular extravasation. [ABSTRACT FROM AUTHOR]

Objective: To quantify and optimize metal artifact reduction using virtual monochromatic dual-energy CT for different metal implants compared to non-metal reference scans.Methods: Dual-energy CT scans of a pair of human cadaver limbs were acquired before and after implanting a titanium tibia plate, a stainless-steel tibia plate and a titanium intramedullary nail respectively. Virtual monochromatic images were analyzed from 70 to 190 keV. Region-of-interest (ROI), used to determine fluctuations and inaccuracies in CT numbers of soft tissues and bone, were placed in muscle, fat, cortical bone and intramedullary tibia canal.Results: The stainless-steel implant resulted in more pronounced metal artifacts compared to both titanium implants. CT number inaccuracies in 70 keV reference images were minimized at 130, 180 and 190 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively. Noise, measured as the standard deviation of pixels within a ROI, was minimized at 130, 150 and 140 keV for the titanium tibia plate, stainless-steel tibia plate and titanium intramedullary nail respectively.Conclusion: Tailoring dual-energy CT protocols using implant specific virtual monochromatic images minimizes fluctuations and inaccuracies in CT numbers in bone and soft tissues compared to non-metal reference scans. [ABSTRACT FROM AUTHOR]

Introduction: Thrombus density may be a predictor for acute ischemic stroke treatment success. However, only limited data on observer variability for thrombus density measurements exist. This study assesses the variability and bias of four common thrombus density measurement methods by expert and non-expert observers. Methods: For 132 consecutive patients with acute ischemic stroke, three experts and two trained observers determined thrombus density by placing three standardized regions of interest (ROIs) in the thrombus and corresponding contralateral arterial segment. Subsequently, absolute and relative thrombus densities were determined using either one or three ROIs. Intraclass correlation coefficient (ICC) was determined, and Bland-Altman analysis was performed to evaluate interobserver and intermethod agreement. Accuracy of the trained observer was evaluated with a reference expert observer using the same statistical analysis. Results: The highest interobserver agreement was obtained for absolute thrombus measurements using three ROIs (ICCs ranging from 0.54 to 0.91). In general, interobserver agreement was lower for relative measurements, and for using one instead of three ROIs. Interobserver agreement of trained non-experts and experts was similar. Accuracy of the trained observer measurements was comparable to the expert interobserver agreement and was better for absolute measurements and with three ROIs. The agreement between the one ROI and three ROI methods was good. Conclusion: Absolute thrombus density measurement has superior interobserver agreement compared to relative density measurement. Interobserver variation is smaller when multiple ROIs are used. Trained non-expert observers can accurately and reproducibly assess absolute thrombus densities using three ROIs. [ABSTRACT FROM AUTHOR]

Introduction: Head movement during CT brain perfusion (CTP) acquisition can deteriorate the accuracy of CTP analysis. Most CTP software packages can only correct in-plane movement and are limited to small ranges. The purpose of this study is to validate a novel 3D correction method for head movement during CTP acquisition. Methods: Thirty-five CTP datasets that were classified as defective due to head movement were included in this study. All CTP time frames were registered with non-contrast CT data using a 3D rigid registration method. Location and appearance of ischemic area in summary maps derived from original and registered CTP datasets were qualitative compared with follow-up non-contrast CT. A quality score (QS) of 0 to 3 was used to express the degree of agreement. Furthermore, experts compared the quality of both summary maps and assigned the improvement score (IS) of the CTP analysis, ranging from −2 (much worse) to 2 (much better). Results: Summary maps generated from corrected CTP significantly agreed better with appearance of infarct on follow-up CT with mean QS 2.3 versus mean QS 1.8 for summary maps from original CTP ( P = 0.024). In comparison to original CTP data, correction resulted in a quality improvement with average IS 0.8: 17 % worsened (IS = −2, −1), 20 % remained unchanged (IS = 0), and 63 % improved (IS = +1, +2). Conclusion: The proposed 3D movement correction improves the summary map quality for CTP datasets with severe head movement. [ABSTRACT FROM AUTHOR]