Utilization and Availability of Advanced Imaging in Patients With Acute Ischemic Stroke

Abstract

Background: Recent clinical trials have established the efficacy of endovascular stroke therapy and intravenous thrombolysis using advanced imaging, particularly computed tomography perfusion (CTP). The availability and utilization of CTP for patients and hospitals that treat acute ischemic stroke (AIS), however, is uncertain. Methods: We performed a retrospective cross-sectional analysis using 2 complementary Medicare datasets, full sample Texas and 5% national fee-for-service data from 2014 to 2017. AIS cases were identified using International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision coding criteria. Imaging utilization performed in the initial evaluation of patients with AIS was derived using Current Procedural Terminology codes from professional claims. Primary outcomes were utilization of imaging in AIS cases and the change in utilization over time. Hospitals were defined as imaging modality–performing if they submitted at least 1 claim for that modality per calendar year. The National Medicare dataset was used to validate state-level findings, and a local hospital-level cohort was used to validate the claims-based approach. Results: Among 50 797 AIS cases in the Texas Medicare fee-for-service cohort, 64% were evaluated with noncontrast head CT, 17% with CT angiography, 3% with CTP, and 33% with magnetic resonance imaging. CTP utilization was greater in patients treated with endovascular stroke therapy (17%) and intravenous thrombolysis (9%). CT angiography (4%/y) and CTP (1%/y) utilization increased over the study period. These findings were validated in the National dataset. Among hospitals in the Texas cohort, 100% were noncontrast head CT–performing, 77% CT angiography–performing, and 14% CTP-performing in 2017. Most AIS cases (69%) were evaluated at non-CTP–performing hospitals. CTP-performing hospitals were clustered in urban areas, whereas large regions of the state lacked immediate access. Conclusions: In state-wide and national Medicare fee-for-service cohorts, CTP utilization in patients with AIS was low, and most patients were evaluated at non-CTP–performing hospitals. These findings support the need for alternative means of screening for AIS recanalization therapies.

Noncontrast Computed Tomography vs Computed Tomography Perfusion or Magnetic Resonance Imaging Selection in Late Presentation of Stroke With Large-Vessel Occlusion

“…Discharge NIHSS scores were lower among patients selected with NCCT (median [IQR], 7 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]) and CTP (median [IQR],…”

“…6 [2][3][4][5][6][7][8][9][10][11][12][13][14]) than those undergoing MRI (median [IQR], 11 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]; P < .001). Overall, symptomatic intracranial hemorrhage was present in 6.3% (n = 100) of this cohort and was similar between the 3 imaging modalities (NCCT, 42 [ 1).…”

Pharmacological brain cytoprotection in acute ischaemic stroke — renewed hope in the reperfusion era

“…Application of imaging in trials to test the hypothesis that cytoprotectants can promote penumbral survival in patients with LVOs at community hospitals before transfer for thrombectomy requires several logistical and practical challenges to be overcome. CT perfusion is not available at most community hospitals 51 but CT angiography is now possible at many, at least in the USA, so could be used to screen patients for endovascular therapies and to facilitate implementation of cytoprotection studies. Furthermore, approaches based on machine learning are being studied to determine whether the images acquired with CT angiography can be analysed to distinguish the penumbra from the infarct core 52 .…”

Acute stroke imaging selection for mechanical thrombectomy in the extended time window: is it time to go back to basics? A review of current evidence

“…CTP requires extensive technical and human resources including specifically trained CT technicians and dedicated postprocessing workstations along with commercial postprocessing software licenses limiting the availability of perfusion imaging especially in smaller centres. A recent analysis of US-Medicare data found the proportion of hospitals performing CTP to be relatively low (14% in 2017) and involve mainly high-end centres clustered in urban areas, while the majority of patients who had an acute ischaemic stroke are treated in non-CTP performing hospitals 6…”

“…In addition, the large treatment effect sizes in these trials suggest that less restrictive patient selection may still result in significant treatment benefits. Importantly, the availability of perfusion imaging outside tertiary stroke centres or in non-metropolitan areas is limited warranting more pragmatic, resource-efficient patient selection approaches 6…”