A new index for CTP assessment when making decisions about thrombus removal in acute ischemic stroke, 5 minutes to understand

*Only for medical professionals to read and refer to the 3 new indicators, and analyze them one by one
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 Since 2015, several large randomized controlled trials (RCTs) have confirmed the safety and effectiveness of thrombectomy for acute ischemic stroke with anterior circulation and great vessel occlusion, and AIS thrombectomy has been carried out in full swing in China
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At the 24th National Conference on Neurology (NCN) of the Chinese Medical Association, Professor Li Gang from the Department of Neurology, Tongji University Affiliated Dongfang Hospital gave a wonderful report on "New CTP Evaluation Indicators for AIS Thrombosis Removal Decision-making"! A brief introduction to the principle of CTP and traditional evaluation index CTP is a functional imaging that evaluates the perfusion state of brain tissue
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Perform continuous dynamic scanning on the selected layer of interest to obtain the time-density curve (TDC) of each pixel in the selected layer, and obtain the local cerebral blood flow through different mathematical model conversions and computer pseudo-color processing according to this curve Hemodynamics such as volume (cercbral blood volume, CBV), cerebral blood flow (cercbral blood flow, CBF), mean transit time (MTT), and time to peak (TTP) Parameters and perfusion image performance to evaluate the perfusion state of brain tissue is a kind of functional imaging
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Two traditional indicators of CTP used in AIS mainly include: core infarct volume: core
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Ischemic penumbra: penumbra
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The ratio of ischemic tissue volume to core infarct volume: mismatch
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1) CTP is used as a traditional indicator of AIS: core infarction is based on the core infarct volume shown on MRI-DWI as the standard.
Most studies define the threshold of core on CTP as CBF<30-50%
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The current threshold accepted by the guidelines for widespread use is 30%
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2) CTP is used in the traditional indicators of AIS: the penumbra is at CBFCBF<30%, the difference between CTP and DWI is the smallest, and the core infarct zone is at Tmax>6s, and the difference between CTP and MRP is the smallest, which is considered to be the total ischemic zone
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The subtraction of the two is the penumbra
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3) CTP is used for traditional indicators of AIS: mismatchEXTEND-IA uses mismatch>1.
2 as the entry criteria, confirming that patients with acute ischemic stroke within 6 hours, endovascular treatment is more beneficial than traditional drug treatment
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The DIFFUSE3 experiment confirmed that 6-16h endovascular treatment of acute ischemic stroke patients with core<70ml, penumbra>15ml, and mismatch>1.
8 still has benefits
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Three CTP is used for the new index of AIS 1) CTP is used for the new index of AIS: core infarction growth rate The core infarction growth rate is defined as the ratio of core infarction growth volume to time.
In various reports, there are two definition methods: in patients Under the premise of clear onset time: admission core infarct volume/onset-imaging examination time
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Patients with two imaging examinations: (core infarct volume shown in the second imaging examination-core infarct volume shown in the first imaging examination) / time between two imaging examinations
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Features: The two methods are based on a linear model of core infarction growth.
There are reports in the literature that the core infarction grows linearly before recanalization is achieved within the first 8 hours, but the infarct core grows after 8 hours or after recanalization.
The method is not yet known, so the first method is more common
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Example: Related factors affecting the growth rate of core infarction: related research on collateral circulation genetic factors and neuroprotection.
Then, the guiding significance of the growth rate of core infarction on vascular opening strategy: for aortic occlusive ischemic stroke within a time window of 4.
5h Compared with thrombolytic therapy, the rapid growth of patients with arterial thrombectomy may have greater benefits
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For patients with ischemic stroke with large arterial occlusion within 24 hours of onset, endovascular treatment for slowly growing patients is still associated with a good outcome compared with the best medical treatment, suggesting that endovascular treatment may still benefit
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And for these patients, histological evaluation is more important, and the time window of endovascular treatment may be further expanded
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At present, there is no clear definition of rapid growth and slow growth.
At present, it is considered that <15ml/h and >25ml/h are rapid growth
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2) CTP is used as a new indicator of AIS: The collateral circulation index used to assess the collateral circulation is mainly based on the CTA/MRA/DSA to assess the collateral circulation.
Its shortcomings: it is not quantitative and subjective
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Some studies have proposed a way to quantitatively evaluate collateral circulation by CTP in patients with acute ischemic stroke-the collateral circulation index
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Collateral circulation index: CTP the volume of delayed time＞6s/the volume of delayed time＞2s, obtained by ROC curve
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DT6/DT2 represents the relative size of the collateral blood supply in the area with no forward blood flow
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3) CTP is used as a new indicator of AIS: The remaining rescue organization time is based on the linear growth of core infarction
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Defined as: ischemic penumbra volume/core infarction growth rate
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This indicator assesses the time left for rescue of the brain tissue of the patient.
Beyond this time, there may be no salvageable tissue in the brain.
It may be used to clinically judge whether there is enough time to recanalize the blood vessels and further help the doctor to judge
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This indicator is based on the linear growth of core infarction, so there are few studies at present
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Fourth summary Finally, Professor Li Gang summarized the content
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1.
For patients with acute anterior circulation and great vessel occlusion stroke, the core volume growth rate may have guiding significance for decision-making
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Within 4.
5 hours of onset, for fast-growing patients, endovascular treatment will benefit more than thrombolytic therapy
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For 4.
5-24h, more RCT studies are needed
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For patients 24 hours after the onset, they can still benefit from endovascular treatment.
Among them, patients with slow-growth type benefit more than those with fast-growth type.
For patients with slow-growth type, histological evaluation may be more important than time window.
, The intravascular time window may be further expanded
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2.
For patients whose onset time is unknown, the collateral circulation index has the potential to predict the growth rate of core infarction, and is used for thrombus removal decision-making
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3.
Through the ischemic penumbra and core infarction growth rate, the remaining time of rescue can be predicted, which can be used to further help clinicians to judge (whether to transfer to hospital? Surgery sequence, etc.
)
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Source: Medical Neurology Channel Reliable, but does not make any promises or guarantees regarding the timeliness of the published content, as well as the accuracy and completeness of the cited information (if any), and does not assume that the content is out of date and the cited information may be inaccurate any liability or incomplete and so caused
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Relevant parties are requested to check separately when adopting or using this as a basis for decision-making
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