Exposing Hidden Truncation-Related Errors in Acute Stroke Perfusion Imaging

Copen, W.A.; Deipolyi, Amy R.; Schaefer, Pamela W.; Schwamm, Lee H; González, Ramón; Wu, Ona

doi:10.3174/ajnr.a4186

Cited by 36 publications

(30 citation statements)

References 27 publications

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“…Since the approach in this study is based on the concept that the largest magnitude of signal variance across time can be found in the larger feeding vessels and thus does not consider the amount of contrast agent that is delivered to the tissue compartment via the perforating arteries, the reability of this method might be less limited by a shorter scan duration than the realibility of conventional established perfusion measures. 48,49 In previous studies, apart from conventionally generated PWI parameter maps, PWI source data have also been applied to assess collateral flow in acute ischaemic stroke by using an image subtraction approach in order to visualize vascular filling at every time point in the PWI timeseries. [50][51][52] Although this approach allows for the visualization of the temporal dynamics of collateral flow and precise assessment of collateral filling until the late venous phase, it carries the disadvantages of being operator-dependent and needs considerable time and effort in image postprocessing and analysis.…”

Section: Discussionmentioning

confidence: 99%

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

Seiler

Lauer

Deichmann

et al. 2019

J Cereb Blood Flow Metab

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As a determinant of the progression rate of the ischaemic process in acute large-vessel stroke, the degree of collateralization is a strong predictor of the clinical outcome after reperfusion therapy and may influence clinical decision-making. Therefore, the assessment of leptomeningeal collateralization is of major importance. The purpose of this study was to develop and evaluate a quantitative and observer-independent method for assessing leptomeningeal collateralization in acute large-vessel stroke based on signal variance characteristics in T2*-weighted dynamic susceptibility contrast (DSC) perfusion-weighted MR imaging (PWI). Voxels representing leptomeningeal collateral vessels were extracted according to the magnitude of signal variance in the PWI raw data time series in 55 patients with proximal large-artery occlusion and an intra-individual collateral vessel index (CVIPWI) was calculated. CVIPWI correlated significantly with the initial ischaemic core volume (rho = −0.459, p = 0.0001) and the PWI/DWI mismatch ratio (rho = 0.494, p = 0.0001) as an indicator of the amount of salvageable tissue. Furthermore, CVIPWI was significantly negatively correlated with NIHSS and mRS at discharge (rho = −0.341, p = 0.015 and rho = −0.305, p = 0.023). In multivariate logistic regression, CVIPWI was an independent predictor of favourable functional outcome (mRS 0–2) (OR = 16.39, 95% CI 1.42–188.7, p = 0.025). CVIPWI provides useful rater-independent information on the leptomeningeal collateral supply in acute stroke.

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Section: Discussionmentioning

confidence: 99%

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

Seiler

Lauer

Deichmann

et al. 2019

J Cereb Blood Flow Metab

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“…Fixed-duration CTP scan protocols, which are currently the standard in clinical practice, and vary in length from 40–90s, are often either too short to accurately assess the ischemic lesion volume or too long, thus exposing patients to unnecessary radiation. 2, 11, 15, 17–24 Future development of case-specific CTP protocols, informed by a low-radiation ‘scout’ with a test bolus, could mitigate the limitations of fixed duration scan protocols. A simple method to individualize the CTP acquisition, that can already be implemented, is to base the delay between contrast administration and start of CTP scanning on contrast arrival data from a CTA.…”

Section: Discussionmentioning

confidence: 99%

Optimal Computed Tomographic Perfusion Scan Duration for Assessment of Acute Stroke Lesion Volumes

Kasasbeh

Christensen

Straka

et al. 2016

Stroke

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Background and Purpose The minimal scan duration needed to obtain reliable lesion volumes with CT perfusion (CTP) has not been well established in the literature. Methods We retrospectively assessed the impact of gradual truncation of the scan duration on acute ischemic lesion volume measurements. For each scan, we identified its “optimal scan time”, defined as the shortest scan duration that yields measurements of the ischemic lesion volumes similar to those obtained with longer scanning, and the relative height of the fitted venous output function at its optimal scan time (rVOF). Results We analyzed 70 CTP scans of acute stroke patients. An optimal scan time could not be determined in 11 (16 %) scans. For the other 59 scans, the median optimal scan time was 32.7s (90th percentile 52.6s; 100th percentile 68.9s) and the median rVOF of their optimal scan times was 0.39 (90th percentile 0.02; 100th percentile 0.00). Based on a linear model, the optimal scan time was T0 plus 1.6 times the width of the Venous Output Function plus (p < 0.001, R2 = 0.49). Conclusions This study shows how the optimal duration of a CTP scan relates to the arrival time and width of the contrast bolus of the scan. This knowledge can be used to optimize CTP scan protocols and to determine if a scan is of sufficient duration. Provided a baseline (T0) of 10s, a total scan duration of 60–70s, which includes the entire downslope of the VOF in most patients, is recommended.

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“…80 data points were acquired using gradient-echo echo planar imaging readout. Mean-transit time (MTT) and Tmax (time at which the tissue response function reached maximum value) perfusion maps were calculated using automated oscillation index regularized deconvolution 23 .…”

Section: Patient Selection and Evaluation This Study Was Compliant Wmentioning

confidence: 99%

Identifying Severe Stroke Patients Likely to Benefit From Thrombectomy Despite Delays of up to a Day

González

Silva

et al. 2020

Sci Rep

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Selected patients with large vessel occlusions (LVO) can benefit from thrombectomy up to 24 hours after onset. Identifying patients who might benefit from late intervention after transfer from community hospitals to thrombectomy-capable centers would be valuable. We searched for presentation biomarkers to identify such patients. Frequent MR imaging over 2 days of 38 untreated LVO patients revealed logarithmic growth of the ischemic infarct core. In 24 patients with terminal internal carotid artery or the proximal middle cerebral artery occlusions we found that an infarct core growth rate (IGR) <4.1 ml/hr and initial infarct core volumes (ICV) <19.9 ml had accuracies >89% for identifying patients who would still have a core of <50 ml 24 hours after stroke onset, a core size that should predict favorable outcomes with thrombectomy. Published reports indicate that up to half of all LVO stroke patients have an IGR <4.1 ml/hr. Other potentially useful biomarkers include the NIHSS and the perfusion measurements MTT and Tmax. We conclude that many LVO patients have a stroke physiology that is favorable for late intervention, and that there are biomarkers that can accurately identify them at early time points as suitable for transfer for intervention.

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Exposing Hidden Truncation-Related Errors in Acute Stroke Perfusion Imaging

Cited by 36 publications

References 27 publications

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

Signal variance-based collateral index in DSC perfusion: A novel method to assess leptomeningeal collateralization in acute ischaemic stroke

Optimal Computed Tomographic Perfusion Scan Duration for Assessment of Acute Stroke Lesion Volumes

Identifying Severe Stroke Patients Likely to Benefit From Thrombectomy Despite Delays of up to a Day

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