Minds treating brains: understanding the interpretation of non-contrast CT ASPECTS in acute ischemic stroke

Wilson, Adam D.; Dey, Sadanand; Evans, James; Najm, Mohamed; Qiu, Wu; Menon, Bijoy K

doi:10.1080/14779072.2018.1421069

Cited by 20 publications

(11 citation statements)

References 38 publications

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“…Therefore, the attending's performance might be explained by the level of experience he had in detecting subtle hypoattenuation in CT images reconstructed with a certain algorithm. 18,19 This is in line with a previous study, wherein a neurology consultant (8 years of experience), who presumably received his training exclusively with FBP, showed the best correlation of ASPECTS rating with expert groundtruth for FBP compared to HIR. 20 Training seems essential to perceive subtle changes of attenuation in noncontrast CT, as summarized in a previous literature review.…”

Section: Discussionsupporting

confidence: 88%

“…Thus, the expert neuroradiologist with 10 years of experience was trained and gained the most experience with CT reconstructions other than IMR, whereas the residents were equally familiar with both reconstruction algorithms investigated in this study. Therefore, the attending's performance might be explained by the level of experience he had in detecting subtle hypoattenuation in CT images reconstructed with a certain algorithm 18,19 . This is in line with a previous study, wherein a neurology consultant (8 years of experience), who presumably received his training exclusively with FBP, showed the best correlation of ASPECTS rating with expert ground‐truth for FBP compared to HIR 20 .…”

Section: Discussionsupporting

confidence: 79%

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Improved Reliability of Automated ASPECTS Evaluation Using Iterative Model Reconstruction from Head CT Scans

Löffler

Sollmann

Mönch

et al. 2021

Journal of Neuroimaging

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Iterative model reconstruction (IMR) has shown to improve computed tomography (CT) image quality compared to hybrid iterative reconstruction (HIR). Alberta Stroke Program Early CT Score (ASPECTS) assessment in early stroke is particularly dependent on high-image quality. Purpose of this study was to investigate the reliability of ASPECTS assessed by humans and software based on HIR and IMR, respectively. METHODS: Forty-seven consecutive patients with acute anterior circulation large vessel occlusions (LVOs) and successful endovascular thrombectomy were included. ASPECTS was assessed by three neuroradiologists (one attending, two residents) and by automated software in noncontrast axial CT with HIR (iDose4; 5 mm) and IMR (5 and 0.9 mm). Two expert neuroradiologists determined consensus ASPECTS reading using all available image data including MRI. Agreement between four raters (three humans, one software) and consensus were compared using square-weighted kappa (κ). RESULTS: Human raters achieved moderate to almost perfect agreement (κ = .557-.845) with consensus reading. The attending showed almost perfect agreement for 5 mm HIR (κ HIR = .845), while residents had mostly substantial agreements without clear trends across reconstructions. Software had substantial to almost perfect agreement with consensus, increasing with IMR 5 and 0.9 mm slice thickness (κ HIR = .751, κ IMR = .777, and κ IMR0.9 = .814). Agreements inversely declined for these reconstructions for the attending (κ HIR = .845, κ IMR = .763, and κ IMR0.9 = .681). CONCLUSIONS: Human and software rating showed good reliability of ASPECTS across different CT reconstructions. Human raters performed best with the reconstruction algorithms they had most experience with (HIR for the attending). Automated software benefits from higher resolution with better contrasts in IMR with 0.9 mm slice thickness.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 79%

Improved Reliability of Automated ASPECTS Evaluation Using Iterative Model Reconstruction from Head CT Scans

Löffler

Sollmann

Mönch

et al. 2021

Journal of Neuroimaging

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“…The traditional methods for radiation reduction include reducing tube voltage, tube current, and acquisition time and frequency, but these measures are easy to increase image noise. With the application of IMR, the image quality can be guaranteed within the maximum range, thus making the traditional methods well applied [ 16 ]. In this study, patients with the CTP scanning mode of 80 kV–150 mAs routine dose combined with FBP image reconstruction were regarded as group A to evaluate the changing patterns of each indicator of gray and white matter in patients from group B under different image reconstruction methods.…”

Section: Discussionmentioning

confidence: 99%

Study on Model Iterative Reconstruction Algorithm vs. Filter Back Projection Algorithm for Diagnosis of Acute Cerebral Infarction Using CT Images

Tang¹,

Liu

Wang³

et al. 2021

Journal of Healthcare Engineering

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The aim was to explore the application value of computed tomography (CT) perfusion (CTP) imaging based on the iterative model reconstruction (IMR) in the diagnosis of acute cerebral infarction (ACI). 80 patients with ACI, admitted to hospital, were selected as the research objects and divided randomly into a routine treatment group (group A) and a low-dose group (group B) (each group with 40 patients). Patients in group A were scanned at 80 kV–150 mAs, and the traditional filtered back projection (FBP) algorithm was employed to reconstruct the images; besides, 80 kV–30 mAs was adopted to scan the patients in group B, and the images were reconstructed by IMR1, IMR2, IMR3, iDose4 (a kind of hybrid iterative reconstruction technology), and FBP, respectively. The application values of different algorithms were evaluated by CTP based on the collected CTP images of patients and detecting indicators. The results showed that the gray and white matter CT value, SD value, SNR, CNR, and subjective image scores of patients in group B were basically consistent with those of group A ( p > 0.05) after the IMR1 reconstruction, and the CT and SD of gray and white matter in patients from group B reduced steeply ( p < 0.05), while SNR and CNR increased dramatically after IMR2 and IMR3 reconstruction in contrast to group A ( p < 0.05). Furthermore, the cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) of contrast agent, and time to peak (TTP) of contrast agent in patients from group B after iDose4 and IMR reconstruction were basically the same as those of group A ( p > 0.05). Therefore, IMR combined with low-dose CTP could obtain high-quality CTP images of the brain with stable perfusion indicators and low radiation dose, which could be clinically applied in the diagnosis of ACI.

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“…Appx. p. 22;Hill et al 2014, Supp. p. 1 ("All, " "posterior"); Wilson et al 2018: "current methods overwhelmingly use the whole scan. " 61 Brainomix 2019;iSchemaView 2019;cf.…”

Section: §1 Prefacementioning

confidence: 99%

ASPECTS, The Mismeasure of Stroke: A Metrological Investigation

Suss¹

2019

Preprint

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ASPECTS (Alberta Stroke Program Early CT Score) is an irregular scoring systemthat reads out as 10 to 0 points. It was originally conceived to reflect acute MCA (middle cerebral artery) territory infarct volume on (plain) CT, but it is equally applicable to and testable by MRI.Background material prepares the reader by explaining pertinent measurement principles and ASPECTS’s genesis, definitions, claims, and quirks. This report investigates ASPECTS as a volume surrogate without independently advocating for or against the therapies it might help plan.Method: The original authors of four publications provided their unpublished primary numerical data for further analysis. A CT study expands on the ACCESS database, which compares ASPECTS with two other subjective infarct scales: the legacy 1/3 MCA estimate and the multivariate IST-3 scale. An MRI study pools three diffusion-weighted (DWI) series as a patient-level meta-analysis unifying their comparisons of ASPECTS to the volumes that were found by semiautomated measurement.CT results: ASPECTS is unreliable, showing wide interrater variation with three quantifiable effects. It delivers little more than half as much entropy reduction as the IST-3 scale shows CT can support. Its large standard deviation (SD) takes up much of the scale width. Converting SD to a loss function with respect to a reference standard neuroradiologist gives an alarming weighted measure of error in ratings.MRI results: There are many-fold ranges of volume per ASPECTS and of ASPECTS per volume, causing sometimes large misclassifications one or both ways by any ASPECTS dichotomization. Looking past the ranges to averages, an estimate of 1/3 of the MCA territory corresponds best to ASPECTS cutting between 6 and 5 (6//5) and a volume of 65 mL (<1/4 of the average MCA territory).Discussion: There is already a simple, quick, and reliable manual volume measure (ABC/2, 2Sh/3). An attempt to salvage ASPECTS by reinterpreting its purpose does not hold up under scrutiny. ASPECTS can be replaced in stroke guidelines: the guideline cutting at ASPECTS 6//5 is consistent on average with the increasingly commonly stated, and better defined, 70 mL threshold. Arguments defending ASPECTS are rebutted by the evidence herein and by literature citations.Conclusion: ASPECTS subtracts value from the more objective direct volume measurements that are universally available by manual calculation and are becoming available by automatic software. ASPECTS inherently risks clinically significant misclassification (harm) for many patients.

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Minds treating brains: understanding the interpretation of non-contrast CT ASPECTS in acute ischemic stroke

Cited by 20 publications

References 38 publications

Improved Reliability of Automated ASPECTS Evaluation Using Iterative Model Reconstruction from Head CT Scans

Improved Reliability of Automated ASPECTS Evaluation Using Iterative Model Reconstruction from Head CT Scans

Study on Model Iterative Reconstruction Algorithm vs. Filter Back Projection Algorithm for Diagnosis of Acute Cerebral Infarction Using CT Images

ASPECTS, The Mismeasure of Stroke: A Metrological Investigation

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