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There are numerous bone tumors in the pediatric population, with imaging playing an essential role in diagnosis and management. Our understanding of certain bone tumors has rapidly evolved over the past decade with advancements in next-generation genetic sequencing techniques. This increased level of understanding has altered the nomenclature, management approach, and prognosis of certain lesions. We provide a detailed update of bone tumors that occur in the pediatric population with emphasis on the recently released nomenclature provided in the 5

There are numerous bone tumors in the pediatric population, with imaging playing an essential role in diagnosis and management. Our understanding of certain bone tumors has rapidly evolved over the past decade with advancements in next-generation genetic sequencing techniques. This increased level of understanding has altered the nomenclature, management approach, and prognosis of certain lesions. We provide a detailed update of bone tumors that occur in the pediatric population with emphasis on the recently released nomenclature provided in the 5

The value of artificial intelligence (AI) in healthcare has become evident, especially in the field of medical imaging. The accelerated pace and acuity of care in the Emergency Department (ED) has made it a popular target for artificial intelligence-driven solutions. Software that helps better detect, report, and appropriately guide management can ensure high quality patient care while enabling emergency radiologists to better meet the demands of quick turnaround times. Beyond diagnostic applications, AI-based algorithms also have the potential to optimize other important steps within the ED imaging workflow. This review will highlight the different types of AI-based applications currently available for use in the ED, as well as the challenges and opportunities associated with their implementation.

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous organ soft tissues, as well as the peripheral and autonomic nervous system.

An earlier incorrect version of this article appeared in print. The online version is correct.

Background and Purpose— The clinical utility of positron emission tomography (PET) imaging in evaluating carotid artery plaque vulnerability remains unclear. Two tracers of recent interest for carotid plaque imaging are 18 F-fluorodeoxyglucose ( 18 F-FDG) and 18 F-sodium fluoride ( 18 F-NaF). We performed a systematic review and meta-analysis evaluating the association between carotid artery 18 F-FDG or 18 F-NaF uptake and recent or future cerebral ischemic events. Methods— A systematic review of Ovid MEDLINE, Ovid EMBASE, and the Cochrane library was conducted from inception to December 2017 for articles evaluating PET tracer uptake in recently symptomatic versus asymptomatic carotid arteries, and articles evaluating carotid uptake in relation to future ischemic events. Cerebral ischemic events were defined as ipsilateral strokes, transient ischemic attacks, or amaurosis fugax. We quantitatively pooled studies by a random-effects model when 3 or more studies were amenable for analysis. We assessed the standardized mean difference between tracer uptake in the symptomatic versus asymptomatic carotid artery using Cohen’s d metric. Results— After screening 4144 unique articles, 13 prospective cohort studies assessing carotid artery 18 F-FDG uptake in patients with recent cerebral ischemia were eligible for review. Eleven cohorts of 290 subjects scanned with 18 F-FDG were eligible for meta-analysis. We found that carotid arteries ipsilateral to recent ischemic events had significantly higher 18 F-FDG uptake than asymptomatic arteries (Cohen’s d =0.492; CI=0.130–0.855; P =0.008) as well as significant heterogeneity (Cochran’s Q =31.5; P =0.0005; I 2 =68.3%). Meta-regression was not performed due to the limited number of studies in the analysis. Only 2 studies investigating 18 F-NaF PET imaging, and another 2 articles investigating ischemic event recurrence were found. Conclusions— Recent ipsilateral cerebral ischemia may be associated with increased carotid 18 F-FDG uptake on PET imaging regardless of degree of carotid stenosis, although significant heterogeneity was found, and these results should be interpreted with caution. Emerging evidence suggests a similar association may be present with 18 F-NaF plaque uptake. More studies are warranted to provide definitive conclusions on the utility of 18 F-FDG or 18 F-NaF in carotid plaque evaluation before investigating carotid PET as a diagnostic tool for cerebral ischemic events.

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous-organ soft tissues, as well as the peripheral and autonomic nervous system.

Background and Purpose: We aim to examine effects of collateral status and post-thrombectomy reperfusion on final infarct distribution and early functional outcome in patients with anterior circulation large vessel occlusion ischemic stroke. Methods: Patients with large vessel occlusion who underwent endovascular intervention were included in this study. All patients had baseline computed tomography angiography and follow-up magnetic resonance imaging. Collateral status was graded according to the criteria proposed by Miteff et al and reperfusion was assessed using the modified Thrombolysis in Cerebral Infarction (mTICI) system. We applied a multivariate voxel-wise general linear model to correlate the distribution of final infarction with collateral status and degree of reperfusion. Early favorable outcome was defined as a discharge modified Rankin Scale score ≤2. Results: Of the 283 patients included, 129 (46%) had good, 97 (34%) had moderate, and 57 (20%) had poor collateral status. Successful reperfusion (mTICI 2b/3) was achieved in 206 (73%) patients. Poor collateral status was associated with infarction of middle cerebral artery border zones, whereas worse reperfusion (mTICI scores 0–2a) was associated with infarction of middle cerebral artery territory deep white matter tracts and the posterior limb of the internal capsule. In multivariate regression models, both mTICI ( P P P P =0.058), predicted favorable outcome at discharge. Conclusions: In this cohort of patients with large vessel occlusion stroke, both the collateral status and endovascular reperfusion were strongly associated with middle cerebral artery territory final infarct volumes. Our findings suggesting that baseline collateral status predominantly affected middle cerebral artery border zones infarction, whereas higher mTICI preserved deep white matter and internal capsule from infarction; may explain why reperfusion success—but not collateral status—was among the independent predictors of favorable outcome at discharge. Infarction of the lentiform nuclei was observed regardless of collateral status or reperfusion success.

Aim: The angiographic collateral status is a major predictor of final infarct volume in patients with large vessel occlusion (LVO). In this study, we assessed the effects of collateral status on final infarct lesion distribution after thrombectomy. Methods: Acute ischemic stroke patients with occluded terminal ICA and/or MCA M1 segment who underwent thrombectomy and had a follow up MRI within a week were included. The angiographic collateral status was evaluated on pre-thrombectomy CTA and graded according to Miteff et al. (Brain 2009;132(8):2231-8). The final infarct lesion was segmented on DWI; and using voxel-wise general linear model, we determined the correlation of final infarct volume with post-thrombectomy TICI (thrombolysis in cerebral infarction) score, and collateral status - as a covariate. Results: Among 106 patients with terminal ICA and/or MCA M1 occlusion in analysis, final infarct volume had a significant correlation with TICI reperfusion score (rho=0.384, p Conclusion: A successful thrombectomy in LVO stroke patients can preserve the cortical and deep white matter of MCA territory - including eloquent speech and motor regions - while CTA collateral status mainly determines the fate of the MCA-PCA border zone. On the other hand, lentiform nuclei tend to infarct despite successful reperfusion and good CTA collateral status.

BACKGROUND: CTA is a widely available imaging examination that may allow the evaluation of high-risk carotid plaque features. PURPOSE: Our aim was to evaluate the association between specific carotid plaque features on CTA and ipsilateral cerebrovascular ischemia. DATA SOURCES: We performed a systematic review of Ovid MEDLINE, Ovid Embase, Scopus, and the Cochrane Library from inception to March 2016 for articles that evaluated the relationship between CTA-detected carotid plaque features and ischemic events, defined as ipsilateral ischemic stroke or transient ischemic attack. STUDY SELECTION: Sixteen studies were ultimately included after screening 12,557. DATA ANALYSIS: Two readers recorded data from each study and assessed the study quality with all disagreements resolved by a third reader. A random-effects OR was used to evaluate the association between cerebrovascular ischemia and each of the evaluated plaque features. DATA SYNTHESIS: We found significant positive relationships with cerebrovascular ischemia for the presence of soft plaque (OR, 2.9; 95% CI, 1.4–6.0), plaque ulceration (OR, 2.2; 95% CI, 1.4–3.4), and increased common carotid artery wall thickness (OR, 6.2; 95% CI, 2.5–15.6). We found a significant negative relationship between calcified plaque and ipsilateral ischemia (OR, 0.5; 95% CI, 0.4–0.7). LIMITATIONS: We found heterogeneity in the existing literature secondary to lack of standardized plaque features and clinical definitions. CONCLUSIONS: Soft plaque, plaque ulceration, and increased common carotid artery wall thickness on CTA are associated with ipsilateral cerebrovascular ischemia, while calcified plaque is negatively associated with downstream ischemic events.

BACKGROUND AND PURPOSE: Intracranial atherosclerosis is a common cause of ischemic stroke. Intracranial stenosis is most commonly quantified by the Warfarin-Aspirin Symptomatic Intracranial Disease method, which involves calculating a ratio of luminal diameter measurements on conventional angiography. Our purpose was to determine whether a single linear measurement of the narrowest caliber of the intracranial ICA on MRA can accurately predict Warfarin-Aspirin Symptomatic Intracranial Disease stenosis measurements. MATERIALS AND METHODS: We identified patients from a prospective stroke registry who had undergone head MRAs to quantitatively evaluate the degree of Warfarin-Aspirin Symptomatic Intracranial Disease–derived stenosis in each intracranial ICA. We also made a single linear millimeter measurement at the site of maximal narrowing of the ICA. We calculated a correlation coefficient between the lumen diameter in millimeters and percentage Warfarin-Aspirin Symptomatic Intracranial Disease stenosis. We performed receiver operating characteristic analysis to determine optimal luminal diameter cutoff values. RESULTS: In 386 unique intracranial ICAs, we found a strong linear relationship between single lumen measurements and Warfarin-Aspirin Symptomatic Intracranial Disease–style stenosis measurements (R = −0.84, P CONCLUSIONS: There is a strong linear relationship between the narrowest lumen diameter of the intracranial ICA and percentage stenosis. Our results suggest that a single lumen diameter measurement on MRA allows accurate estimation of Warfarin-Aspirin Symptomatic Intracranial Disease stenosis, which may affect risk stratification and treatment decisions.

Background Studies have shown that pericoronary artery inflammation can be accurately detected via increased attenuation on computed tomography. Our purpose was to evaluate the association between pericarotid inflammation, measured by density of carotid perivascular fat on computed tomography angiography, with stroke and transient ischemic attack. Methods and Results We screened computed tomography angiography examinations for patients with unilateral internal carotid artery ( ICA ) stenosis ≥50% to 99%. A blinded neuroradiologist placed regions‐of‐interest in the pericarotid fat on the slice showing maximal stenosis. Two‐sample t tests were performed to assess between‐subject differences in mean Hounsfield Units in carotid perivascular fat between symptomatic and asymptomatic patients. Paired t tests were used to assess within‐subject differences in mean Hounsfield Units between stenotic versus nonstenotic ICA s in a given patient. We included 94 patients, including 42 symptomatic and 52 asymptomatic patients. In the between‐subject analysis of stenotic ICA s, we found symptomatic patients had higher mean pericarotid fat density compared with asymptomatic patients (−66.2±19.2 versus −77.1±20.4, P =0.009). When comparing nonstenotic ICA s, there was no significant difference between pericarotid fat density in symptomatic compared with asymptomatic patients (−81.0±13.3 versus −85.3±18.0: P =0.198). Within‐subject comparison showed statistically significant increased density in stenotic ICA versus nonstenotic ICA with mean Hounsfield Units difference of 11.1 ( P Conclusions We found increased density, a surrogate marker for perivascular inflammation, in the fat surrounding ICA s ipsilateral to stroke or transient ischemic attack compared with asymptomatic ICA s. Our findings suggest that inflammation associated with culprit carotid plaques extends beyond the vessel lumen and can be identified using simple methods on computed tomography angiography imaging.

Background The extent of calcium volume in the carotid arteries of contrast-based computer tomography (CT) is a valuable indicator of stroke risk. This study presents an automated, simple and fast calcium volume computation system. Since the high contrast agent can sometimes obscure the presence of calcium in the CT slices, it is therefore necessary to identify these slices before the corrected volume can be estimated. Methods The system typically consists of segmenting the calcium region from the CT scan into slices based on Hounsfield Unit-based threshold, and subsequently computing the summation of the calcium areas in each slice. However, when the carotid volume has intermittently higher concentration of contrast agent, a dependable approach is adapted to correct the calcium region using the neighboring slices, thereby estimating the correct volume. Furthermore, mitigation is provided following the regulatory constraints by changing the system to semi-automated criteria as a fall back solution. We evaluate the automated and semi-automated techniques using completely manual calcium volumes computed based on the manual tracings by the neuroradiologist. Results A total of 64 patients with calcified plaque in the internal carotid artery were analyzed. Using the above algorithm, our automated and semi-automated system yields correlation coefficients (CC) of 0.89 and 0.96 against first manual readings and 0.90 and 0.96 against second manual readings, respectively. Using the t-test, there was no significant difference between the automated and semi-automated methods against manual. The intra-observer reliability was excellent with CC 0.98. Conclusions Compared to automated method, the semi-automated method for calcium volume is acceptable and closer to manual strategy for calcium volume. Further work evaluating and confirming the performance of our semi-automated protocol is now warranted.

Background Gadolinium enhancement on high‐resolution magnetic resonance imaging ( MRI ) has been proposed as a marker of inflammation and instability in intracranial atherosclerotic plaque. We performed a systematic review and meta‐analysis to summarize the association between intracranial atherosclerotic plaque enhancement and acute ischemic stroke. Methods and Results We searched the medical literature to identify studies of patients undergoing intracranial vessel wall MRI for evaluation of intracranial atherosclerotic plaque. We recorded study data and assessed study quality, with disagreements in data extraction resolved by a third reader. A random‐effects odds ratio was used to assess whether, in any given patient, cerebral infarction was more likely in the vascular territory supplied by an artery with MRI ‐detected plaque enhancement as compared to territory supplied by an artery without enhancement. We calculated between‐study heterogeneity using the Cochrane Q test and publication bias using the Begg‐Mazumdar test. Eight articles published between 2011 and 2015 met inclusion criteria. These studies provided information about plaque enhancement characteristics from 295 arteries in 330 patients. We found a significant positive relationship between MRI enhancement and cerebral infarction in the same vascular territory, with a random effects odds ratio of 10.8 (95% CI 4.1–28.1, P P =0.14) or publication bias ( P =0.80) was present. Conclusions Intracranial plaque enhancement on high‐resolution vessel wall MRI is strongly associated with ischemic stroke. Evaluation for plaque enhancement on MRI may be a useful test to improve diagnostic yield in patients with ischemic strokes of undetermined etiology.