Clinical, Imaging, and Lab Correlates of Severe COVID-19 Leukoencephalopathy.

BACKGROUND AND PURPOSE: Patients infected with the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) can develop a spectrum of neurological disorders, including a leukoencephalopathy of variable severity. Our aim was to characterize imaging, lab, and clinical correlates of severe coronavirus disease 2019 (COVID-19) leukoencephalopathy, which may provide insight into the SARS-CoV-2 pathophysiology. MATERIALS AND METHODS: Twenty-seven consecutive patients positive for SARS-CoV-2 who had brain MR imaging following intensive care unit admission were included. Seven (7/27, 26%) developed an unusual pattern of "leukoencephalopathy with reduced diffusivity" on diffusion-weighted MR imaging. The remaining patients did not exhibit this pattern. Clinical and laboratory indices, as well as neuroimaging findings, were compared between groups. RESULTS: The reduced-diffusivity group had a significantly higher body mass index (36 versus 28 kg/m2, P < .01). Patients with reduced diffusivity trended toward more frequent acute renal failure (7/7, 100% versus 9/20, 45%; P = .06) and lower estimated glomerular filtration rate values (49 versus 85 mL/min; P = .06) at the time of MRI. Patients with reduced diffusivity also showed lesser mean values of the lowest hemoglobin levels (8.1 versus 10.2 g/dL, P < .05) and higher serum sodium levels (147 versus 139 mmol/L, P = .04) within 24 hours before MR imaging. The reduced-diffusivity group showed a striking and highly reproducible distribution of confluent, predominantly symmetric, supratentorial, and middle cerebellar peduncular white matter lesions (P < .001). CONCLUSIONS: Our findings highlight notable correlations between severe COVID-19 leukoencephalopathy with reduced diffusivity and obesity, acute renal failure, mild hypernatremia, anemia, and an unusual brain MR imaging white matter lesion distribution pattern. Together, these observations may shed light on possible SARS-CoV-2 pathophysiologic mechanisms associated with leukoencephalopathy, including borderzone ischemic changes, electrolyte transport disturbances, and silent hypoxia in the setting of the known cytokine storm syndrome that accompanies severe COVID-19.

Brain MR Spectroscopic Findings in 3 Consecutive Patients with COVID-19: Preliminary Observations.

Brain multivoxel MR spectroscopic imaging was performed in 3 consecutive patients with coronavirus disease 2019 (COVID-19). These included 1 patient with COVID-19-associated necrotizing leukoencephalopathy, another patient who had a recent pulseless electrical activity cardiac arrest with subtle white matter changes, and a patient without frank encephalopathy or a recent severe hypoxic episode. The MR spectroscopic imaging findings were compared with those of 2 patients with white matter pathology not related to Severe Acute Respiratory Syndrome coronavirus 2 infection and a healthy control subject. The NAA reduction, choline elevation, and glutamate/glutamine elevation found in the patient with COVID-19-associated necrotizing leukoencephalopathy and, to a lesser degree, the patient with COVID-19 postcardiac arrest, follow a similar pattern as seen with the patient with delayed posthypoxic leukoencephalopathy. Lactate elevation was most pronounced in the patient with COVID-19 necrotizing leukoencephalopathy.

Perfusion CT Imaging Follows Clinical Severity in Left Hemispheric Strokes.

OBJECTIVE: The purpose of this study was to assess how imaging findings on admission perfusion CT (PCT) and follow-up noncontrast CT (NCT), and their changes over time, correlate with clinical scores of stroke severity measured on admission, at discharge and at 6-month follow-up. METHODS: Fifty-two patients with suspected hemispheric acute ischemic stroke underwent a PCT within the first 24 h of symptom onset and a follow-up NCT of the brain between 24 h and 3 months after the initial stroke CT study. NIH Stroke Scale (NIHSS) scores were recorded for each patient at admission, discharge and 6 months; modified Rankin scores were determined at discharge and 6 months. Baseline PCT and follow-up NCT were analyzed quantitatively (volume of ischemic/infarcted tissue) and semiquantitatively (anatomical grading score derived from the Alberta Stroke Program Early CT Score). The correlation between imaging volumes/scores and clinical scores was assessed. Analysis was performed for all patients considered together and separately for those with right and left hemispheric strokes. RESULTS: Significant correlations were found between clinical scores and both quantitative and semiquantitative imaging. The volume of the acute PCT mean transit time lesion showed best correlation with admission NIHSS scores (R2 = 0.61, p < 0.001). This association was significantly better for left hemispheric strokes (R(2) = 0.80, p < 0.001) than for right hemispheric strokes (R2 = 0.39, p = 0.131). Correlation between imaging and NIHSS scores was better than correlation between imaging and modified Rankin scores (p = 0.047). The correlation with discharge clinical scores was better than that with 6-month clinical scores (p = 0.012). CONCLUSIONS: Baseline PCT and follow-up NCT volumes predict stroke severity at baseline, discharge and, to a lesser extent, 6 months. The correlation is stronger for left-sided infarctions. This finding supports the use of PCT as a surrogate stroke outcome measure.

First-pass quantitative CT perfusion identifies thresholds for salvageable penumbra in acute stroke patients treated with intra-arterial therapy.

BACKGROUND AND PURPOSE: The purpose of this study was to determine whether, in acute stroke patients treated with intra-arterial (IA) recanalization therapy, CT perfusion (CTP) can distinguish ischemic brain tissue destined to infarct from that which will survive. METHODS: Dynamic CTP was obtained in 14 patients within 8 hours of stroke onset, before IA therapy. Initial quantitative cerebral blood volume (CBV) and flow (CBF) values were visually segmented and normalized in the "infarct core" (region 1: reduced CBV and CBF, infarction on follow-up), "penumbra that infarcts" (region 2: normal CBV, reduced CBF, infarction on follow-up), and "penumbra that recovers" (region 3: normal CBV, reduced CBF, normal on follow-up). Normalization was accomplished by dividing the ischemic region of interest value by that of a corresponding, contralateral, uninvolved region, which resulted in CBV and CBF "ratios." Separate CBV and CBF values were obtained in gray matter (GM) and white matter (WM). RESULTS: Mean CBF ratios for regions 1, 2, and 3 were 0.19 +/- 0.06, 0.34 +/- 0.06, and 0.46 +/- 0.09, respectively (all P < .001). Mean CBV ratios for regions 1, 2, and 3 were similarly distinct (all P < .05). Absolute CBV and CBF values for regions 2 and 3 were not significantly different. All regions with CBF ratio <0.32, CBV ratio <0.68, CBF <12.7 mL/100 g/min, or CBV <2.2 mL/100 g infarcted. No region with CBF ratio >0.44 infarcted. GM versus WM CBF and CBV values were significantly different for region 2 compared with region 3 (P < .05). CONCLUSIONS: In acute stroke patients, quantitative CTP can distinguish ischemic tissue likely to infarct from that likely to survive.

Percentage insula ribbon infarction of >50% identifies patients likely to have poor clinical outcome despite small DWI infarct volume.

BACKGROUND AND PURPOSE: Large admission DWI infarct volume (>70 mL) is an established marker for poor clinical outcome in acute stroke. Outcome is more variable in patients with small infarcts (<70 mL). Percentage insula ribbon infarct correlates with infarct growth. We hypothesized that percentage insula ribbon infarct can help identify patients with stroke likely to have poor clinical outcome, despite small admission DWI lesion volumes. MATERIALS AND METHODS: We analyzed the admission NCCT, CTP, and DWI scans of 55 patients with proximal anterior circulation occlusions on CTA. Percentage insula ribbon infarct (>50%, ≤50%) on DWI, NCCT, CT-CBF, and CT-MTT were recorded. DWI infarct volume, percentage DWI motor strip infarct, NCCT-ASPECTS, and CTA collateral score were also recorded. Statistical analyses were performed to determine accuracy in predicting poor outcome (mRS >2 at 90 days). RESULTS: Admission DWI of >70 mL and DWI-percentage insula ribbon infarct of >50% were among significant univariate imaging markers of poor outcome (P < .001). In the multivariate analysis, DWI-percentage insula ribbon infarct of >50% (P = .045) and NIHSS score (P < .001) were the only independent predictors of poor outcome. In the subgroup with admission DWI infarct of <70 mL (n = 40), 90-day mRS was significantly worse in those with DWI-percentage insula ribbon infarct of >50% (n = 9, median mRS = 5, interquartile range = 2-5) compared with those with DWI-percentage insula ribbon infarct of ≤50% (n = 31, median mRS = 2, interquartile range = 0.25-4, P = .036). In patients with admission DWI infarct of >70 mL, DWI-percentage insula ribbon infarct did not have added predictive value for poor outcome (P = .931). CONCLUSIONS: DWI-percentage insula ribbon infarct of >50% independently predicts poor clinical outcome and can help identify patients with stroke likely to have poor outcome despite small admission DWI lesion volumes.

Multiple Procedure Payment Reduction: Health Policy Update.

Multiple Procedure Payment Reduction currently applies to multiple diagnostic imaging services administered to the same patient during the same day and entails a 50% decrease in the technical component and a 25% decrease in the professional component reimbursement. This might change with time due to further legislation, so it is important to be up-to-date on these health policy developments.

Utility of perfusion-weighted CT imaging in acute middle cerebral artery stroke treated with intra-arterial thrombolysis: prediction of final infarct volume and clinical outcome.

BACKGROUND AND PURPOSE: The goal of this study was to evaluate the utility of perfusion-weighted CT (PWCT) in predicting final infarct volume and clinical outcome in patients with acute middle cerebral artery (MCA) stroke. METHODS: Twenty-two consecutive patients with MCA stem occlusion who underwent intra-arterial thrombolysis within 6 hours of stroke onset had noncontrast CT and CT angiography with whole-brain PWCT imaging before treatment. Infarct volumes were computed from the initial PWCT and follow-up scans; clinical outcome was measured with the modified Rankin scale. RESULTS: Initial PWCT lesion volumes correlated significantly with final infarct volume (P=0.0002) and clinical outcome (P=0.01). For the 10 patients with complete recanalization, the relationship between initial and final lesion volume was especially strong (R(2)=0.94, P<0.0001, slope of regression line=0.92). For those without complete recanalization, there was progression of lesion volume on follow-up imaging (R(2)=0.50, P=0.01, slope of regression line=1.61). All patients with either initial PWCT lesion volumes >100 mL or no recanalization had poor outcomes (Rankin scores, 4 to 6). Mean admission NIH Stroke Scale scores and mean lesion volumes in the poor outcome group were significantly different compared with the good or fair outcome (Rankin scores, 0 to 3) group (21+/-4 versus 17+/-5, P=0.05, and 106+/-79 versus 29+/-37 mL, P=0.01). Patients with initial volumes <100 mL and partial or complete recanalization all had good (Rankin scores, 0 to 2) or fair (Rankin score, 3) outcomes. CONCLUSIONS: Lesion volumes on admission PWCT images approximate final infarct volume for patients with early complete recanalization of MCA stem occlusion. For those without complete recanalization, there is subsequent enlargement of lesion volume on follow-up. Initial PWCT lesion volumes also have predictive value; volumes >100 mL are associated with a poor clinical outcome. In these highly selected patients, initial PWCT lesion volume was a stronger predictor of clinical outcome than was initial NIH Stroke Scale score.

Parotid pleomorphic adenomas: delayed CT enhancement.

BACKGROUND AND PURPOSE: Weak or absent CT enhancement in pleomorphic adenomas of the parotid gland has been observed immediately after i.v. contrast administration. This feature can result in poor lesion conspicuity relative to both normal parotid tissue and other parotid abnormalities. The purpose of this study was to document the delayed CT enhancement characteristics of parotid pleomorphic adenomas and to preliminarily compare these results with the enhancement characteristics of other parotid gland tumors. METHODS: Preoperative CT scans from 18 pathologically proved parotid gland neoplasms were reviewed retrospectively. Lesions included eight pleomorphic adenomas, four Warthin's tumors, two squamous cell carcinomas, two mucoepidermoid cancers, one acinic cell carcinoma, and one melanoma metastasis. In all cases, axial CT was performed after the administration of 100 to 150 mL of i.v. contrast material, followed by delayed (average, 24 minutes; range, 13 to 34 minutes) coronal CT scanning. The mean normalized Hounsfield unit (HU) attenuation of each lesion was computed by drawing a region of interest around the entire mass and dividing the resulting HU value by that of the contralateral uninvolved parotid gland. RESULTS: For all eight pleomorphic adenomas, the degree of contrast enhancement increased and became progressively more uniform with time. Mean normalized axial lesion enhancement averaged 1.20 +/- 0.35 at 8 minutes, compared with 2.30 +/- 0.66 on the coronal scans at 24 minutes. For the 10 nonpleomorphic adenomas, no significant change was found in either the degree or pattern of contrast enhancement between the immediate and delayed CT scans. In these tumors, peak enhancement was reached early, during axial scanning. CONCLUSION: Delayed CT contrast enhancement is observed in parotid pleomorphic adenomas, increasing in both degree and homogeneity with time. This feature may be useful in selecting an appropriate contrast delay when scanning possible pleomorphic adenomas to improve lesion conspicuity and, potentially, to better distinguish these tumors from other parotid abnormalities.

Reduction of aneurysm clip artifacts on CT angiograms: a technical note.

We describe a head tilt technique for use with CT angiography that reduces beam-hardening artifacts in patients with aneurysm clips. This simple maneuver directs the artifacts away from pertinent anatomy, thus increasing the chances for diagnostic accuracy. No significant changes in the CT angiographic protocol are required, and the maneuver can easily be combined with other artifact-minimizing strategies.

Assessment of cerebral perfusion and arterial anatomy in hyperacute stroke with three-dimensional functional CT: early clinical results.

PURPOSE: Our purpose was to determine the clinical feasibility of quantitative three-dimensional functional CT in patients with hyperacute stroke. METHODS: Twenty-two patients who underwent clinically indicated CT angiography were studied: nine patients had no stroke, eight had mature stroke, and five had hyperacute stroke (less than 3 hours since ictus). Maps were obtained of perfused cerebral blood volume (PBV), and CT angiograms were generated by using standard techniques. RESULTS: Normal PBV values (mean +/- SEM) were 4.6 +/- 0.15% in the gray matter, 1.75 +/- 0.09% in the white matter, 2.91 +/- 0.20% in the cerebellum, 3.18 +/- 0.10% in the caudate, 2.84 +/- 0.23% in the putamen, 2.92 +/- 0.29% in the thalamus, and 1.66 +/- 0.03% in the brain stem. For patients with mature stroke, ischemic changes were visible on noncontrast, contrast-enhanced, and PBV scans. In patients with hyperacute stroke, ischemic changes were either absent or subtle before contrast administration, but became apparent on contrast-enhanced scans. Quantitative PBV maps confirmed reduced regional perfusion. CT angiograms in the hyperacute group showed occlusion of vessels in locations appropriate to the PBV deficits seen. CONCLUSION: Quantitative three-dimensional functional CT is feasible for patients with hyperacute stroke. It is performed by using helical CT techniques, and yields measures of cerebrovascular physiological function, which are useful in this patient population.

Imaging of cystic lesions.

Cystic neck masses are varied in their histology and embryogenesis. Because neural, vascular, and lipomatous lesions may all appear cystic, a multimodality imaging approach can help identify these potential mimics. Developmental neck cysts include thyroglossal duct, thymic, and branchial cleft cysts, and teratomatous lesions or lymphangiomas. Although laryngoceles are acquired lesions, congenital anomalies (e.g., abnormally long saccules) may play a role in their formation. Lesion location is at least as important a determinant as morphology in formulating the differential diagnosis of a cystic neck mass. Midline cystic lesions are most commonly thyroglossal duct cysts, although dermoid tumors are also frequently midline. Squamous cell carcinoma metastatic to anterior triangle lymph nodes (Fig. 17), and cystic, necrotic schwanommas, can mimic the typical appearance of an infected second branchial cleft cyst. Posterior triangle lymphadenopathy and lipomatous lesions may resemble cystic hygromas. Cystic-appearing masses in the carotid space include neurogenic tumors, vascular thromboses, and carotid chain lymphadenopathy. Neural-based lesions typically occur posterolateral to the carotid artery. Necrotic lymphadenopathy may be suggested by lesion multiplicity, or by the presence of ancillary features, such as systemic symptoms, or the existence of a primary tumor. It must be emphasized that the primary role of the radiologist in head and neck imaging is to help stage disease and guide surgery. Despite clinical and radiographic analysis, the diagnosis of many lesions ultimately depends on image-guided or excisional biopsy.

Accelerated fractionated proton/photon irradiation to 90 cobalt gray equivalent for glioblastoma multiforme: results of a phase II prospective trial.

OBJECT: After conventional doses of 55 to 65 Gy of fractionated irradiation, glioblastoma multiforme (GBM) usually recurs at its original location. This institutional phase II study was designed to assess whether dose escalation to 90 cobalt gray equivalent (CGE) with conformal protons and photons in accelerated fractionation would improve local tumor control and patient survival. METHODS: Twenty-three patients were enrolled in this study. Eligibility criteria included age between 18 and 70 years, Karnofsky Performance Scale score of greater than or equal to 70, residual tumor volume of less than 60 ml, and a supratentorial, unilateral tumor. Actuarial survival rates at 2 and 3 years were 34% and 18%, respectively. The median survival time was 20 months, with four patients alive 22 to 60 months postdiagnosis. Analysis by Radiation Therapy Oncology Group prognostic criteria or Medical Research Council indices showed a 5- to 11-month increase in median survival time over those of comparable conventionally treated patients. All patients developed new areas of gadolinium enhancement during the follow-up period. Histological examination of tissues obtained at biopsy, resection, or autopsy was conducted in 15 of 23 patients. Radiation necrosis only was demonstrated in seven patients, and their survival was significantly longer than that of patients with recurrent tumor (p = 0.01). Tumor regrowth occurred most commonly in areas that received doses of 60 to 70 CGE or less; recurrent tumor was found in only one case in the 90-CGE volume. CONCLUSIONS: A dose of 90 CGE in accelerated fractionation prevented central recurrence in almost all cases. The median survival time was extended to 20 months, likely as a result of central control. Tumors will usually recur in areas immediately peripheral to this 90-CGE volume, but attempts to extend local control by enlarging the central volume are likely to be limited by difficulties with radiation necrosis.

Computed tomographic angiography and computed tomographic perfusion imaging of hyperacute stroke.

The roles of noncontrast computed tomography (NCCT) and CT angiographic/CT perfusion (CTA/CTP) imaging in the rapid triage of clinically suspected hyperacute stroke patients to appropriate therapy is reviewed. Contraindications to thrombolysis include NCCT hemorrhage (absolute) and significant parenchymal hypodensity (relative). The sensitivity of NCCT for early (<6 h) stroke detection, higher than that of conventional magnetic resonance imaging, is improved further by using nonstandard window and level review settings. CTA/CTP is fast and convenient, adding approximately 10 min to the NCCT examination. CTA/CTP's accuracy in diagnosing ischemia and localizing thrombus to proximal or distal intracranial vessels far exceeds that of clinical examination (including National Institutes of Health stroke scale use), facilitating triage of appropriate candidates to intra-arterial thrombolysis. The size of the ischemic CTP hypodensity (proportional to reduced cerebral blood volume) predicts final infarct volume and clinical outcome; its location can guide the decision to perform intra-arterial thrombolysis, intravenous thrombolysis, or other treatment.

Potential influence of acute CT on inpatient costs in patients with ischemic stroke.

RATIONALE AND OBJECTIVES: Patients presenting with ischemic brain symptoms have widely variable outcomes dependent to some degree on the pathologic basis of their stroke syndrome. The purpose of this study was to determine the cost implications of the emergency use of a computed tomographic (CT) protocol comprising unenhanced CT, head and neck CT angiography, and whole-brain CT perfusion. MATERIALS AND METHODS: By using a retrospective patient database from a tertiary care facility and publicly available cost data, the authors derived the potential savings from the use of CT angiography. CT perfusion, or both at hospital arrival by means of a cost model. The cost of the CT angiography-CT perfusion protocol was determined from Medicare reimbursement rates and compared with that of traditional imaging protocols. Cost savings were estimated as a decrease in the length of stay for most stroke patients, whereas the most benign (lacunar) strokes were assumed to be managed in a non-acute setting. Misdiagnosis cost (erroneously not admitting a patient with nonlacunar stroke) was calculated as the cost of a severe complication. Sensitivity testing included varying the percentage of misdiagnosed patients and admitting patients with lacunar stroke. RESULTS: The nationwide net savings that would result from the adoption of the CT angiography-CT perfusion protocol are in the $1.2 billion range (-$154 million to $2.1 billion) when patients with lacunar strokes are treated nonacutely and $1.8 billion when those patients are admitted for acute care. CONCLUSION: The results demonstrate the potential effect of implementing a CT angiography-CT perfusion protocol. In particular, prompt CT angiography-CT perfusion imaging could have an effect on the cost of acute care in the treatment of stroke.

Clinical applications of intracranial perfusion MR imaging.

Dynamic susceptibility MR perfusion imaging of the brain offers clinically relevant physiological data not obtainable by conventional MR imaging. As new treatments continue to be developed for stroke, neoplasm, dementia, psychiatric illness, headache, and trauma, the potential clinical applications of perfusion MR imaging in the diagnosis, triage, and therapeutic monitoring of these diseases will increase. MR perfusion techniques are likely to be at least as sensitive and specific as radionuclide-based techniques, and offer the added advantage of higher intrinsic resolution, convenient coregistration with conventional MR imaging, as well as, time and cost-effective imaging in patients for whom a routine MR imaging is obtained.

Larynx.

The complex anatomy of the larynx, best conceptualized as a set of mucosal folds draped over a cartilaginous skeleton, has developed as a consequence of its many upper airway functions. Despite its deep location in the neck, much of the mucosal surface of the larynx is amenable to direct laryngoscopic inspection. The role of the radiologist in laryngeal imaging, therefore, is not primarily to diagnose disease, but to aid in both surgical staging and in the evaluation of potential clinical "blind spots." In this article, the normal anatomy of the larynx is reviewed, with special attention to important surgical and functional structures.

Dynamic contrast-enhanced brain perfusion imaging: technique and clinical applications.

Magnetic resonance (MR) and computed tomographic (CT) perfusion imaging are evolving noninvasive imaging techniques that, unlike conventional MR and CT angiographic methods, can be used to evaluate capillary level tissue perfusion. These techniques can provide early, highly accurate delineation of ischemic tissue, allowing the underlying hemodynamic disturbances of disorders such as stroke and vasospasm to be further analyzed, as well as defining abnormal regions of blood pool in brain tumors. Because MR perfusion (MRP) and CT perfusion (CTP) imaging can assess physiologic parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT), they offer additional data that can be useful in the detection and characterization of entities such as tumor, infection, inflammation, and infarction, which all can have similar appearances on both contrast and noncontrast enhanced conventional CT and MR images. They can also facilitate the further evaluation of processes such as early dementia, psychiatric illnesses, and migraine headaches, which may appear normal on routine CT and MR imaging. MRP and CTP might also be of value in distinguishing residual or recurrent tumor from treatment effects such as radiation-induced necrosis. This article reviews the background principles, scanning techniques, and clinical applications of noninvasive cerebral perfusion imaging.

Contrast extravasation on CT angiography predicts hematoma expansion and mortality in acute traumatic subdural hemorrhage.

BACKGROUND AND PURPOSE: The presence of active contrast extravasation at CTA predicts hematoma expansion and in-hospital mortality in patients with nontraumatic intracerebral hemorrhage. This study aims to determine the frequency and predictive value of the contrast extravasation in patients with aSDH. MATERIALS AND METHODS: We retrospectively reviewed 157 consecutive patients who presented to our emergency department over a 9-year period with aSDH and underwent CTA at admission and a follow-up NCCT within 48 hours. Two experienced readers, blinded to clinical data, reviewed the CTAs to assess for the presence of contrast extravasation. Medical records were reviewed for baseline clinical characteristics and in-hospital mortality. aSDH maximum width in the axial plane was measured on both baseline and follow-up NCCTs, with hematoma expansion defined as >20% increase from baseline. RESULTS: Active contrast extravasation was identified in 30 of 199 discrete aSDHs (15.1%), with excellent interobserver agreement (κ = 0.80; 95% CI, 0.7-0.9). The presence of contrast extravasation indicated a significantly increased risk of hematoma expansion (odds ratio, 4.5; 95% CI, 2.0-10.1; P = .0001) and in-hospital mortality (odds ratio, 7.6; 95% CI, 2.6-22.3; P = 0.0004). In a multivariate analysis controlled for standard risk factors, the presence of contrast extravasation was an independent predictor of aSDH expansion (P = .001) and in-hospital mortality (P = .0003). CONCLUSIONS: Contrast extravasation stratifies patients with aSDH into those at high risk and those at low risk of hematoma expansion and in-hospital mortality. This distinction could affect patient treatment, clinical trial selection, and possible surgical intervention.