MRI Interscanner Agreement of the Association between the Susceptibility Vessel Sign and Histologic Composition of Thrombi

Bourcier, Romain; Détraz, Lili; Serfaty, Jean Michel; Delasalle, Béatrice; Mirza, Mahmood; Derraz, Imad; Toulgoat, F.; Naggara, Olivier; Toquet, Claire; Desal, Hubert

doi:10.1111/jon.12464

Cited by 21 publications

(15 citation statements)

References 24 publications

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“…3,5,6 Furthermore, the diagnostic accuracy of the SVS to predict thrombus composition varies according to the MR imaging machine. 8 This variation seems to be a crucial pitfall for any extensive use of the SVS in large multicenter studies. The appearance of the SVS is related to technical parameters such as TE, voxel size, and magnetic field.…”

Section: Discussionmentioning

confidence: 99%

“…Last, the diagnostic accuracy of the SVS to determine RBC content varies dramatically among MR imaging machines. 8 Because T2* maps are commonly used to assess the cardiac and liver iron load in patients with thalassemia, 9,10 measuring the thrombus T2* relaxation time (TT2*RT) could provide quantitative insight into thrombus composition rather than a qualitative evaluation using the SVS. 11 In this study, we aimed to analyze the RBC content of in vitro thrombi in relation to the thrombus-T2* relaxation time and to examine the intra-and interobserver agreement of the TT2*RT measurements.…”

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confidence: 99%

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MRI Quantitative T2* Mapping to Predict Dominant Composition of In Vitro Thrombus

Bourcier¹,

Pautre²,

Mirza³

et al. 2019

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: MR imaging quantitative T2* mapping, which provides information about thrombus composition and specifically the red blood cell content, may be obtained in the setting of acute ischemic stroke before treatment. This could be useful to adapt the endovascular strategy. We aimed to analyze the red blood cell content of in vitro thrombi in relation to the thrombus-T2* relaxation time. MATERIALS AND METHODS:Thirty-five thrombus analogs of different compositions were scanned with an MR imaging quantitative T2* mapping sequence. Two radiologists, blinded to thrombus composition, measured the thrombus-T2* relaxation time twice at an interval of 2 weeks. Quantitative histologic evaluations of red blood cell content were performed. Inter-and intraobserver reproducibility of the thrombus-T2* relaxation time was assessed by calculating intraclass correlation coefficients. Finally, a Spearman product moment correlation between the thrombus-T2* relaxation time and red blood cell content was performed. RESULTS:The median thrombus-T2* relaxation time was 78.5 ms (range, 16 -268 ms; interquartile range, 60.5 ms). The median red blood cell content was 55% (range, 0%-100%; interquartile range, 75%). Inter-and intraobserver reproducibility of the thrombus-T2* relaxation time was excellent (Ͼ0.9). The Spearman rank correlation test found a significant inverse correlation between thrombus-T2* relaxation time and red blood cell content ( ϭ Ϫ0.834, P Ͻ .001).CONCLUSIONS: MR imaging quantitative T2* mapping can reliably identify the thrombus red blood cell content in vitro. This fast, easy-to-use sequence could be implemented in routine practice to predict stroke etiology and adapt devices or techniques for endovascular treatment of acute ischemic stroke. ABBREVIATIONS: RBC ϭ red blood cell; SVS ϭ susceptibility vessel sign; TT2*RT ϭ thrombus-T2* relaxation time

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

MRI Quantitative T2* Mapping to Predict Dominant Composition of In Vitro Thrombus

Bourcier¹,

Pautre²,

Mirza³

et al. 2019

AJNR Am J Neuroradiol

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“…Deoxygenated hemoglobin has four unpaired electrons and will act as a paramagnetic center that modifies tissue magnetic susceptibility, leading to a more prominent SVS response. The induced local magnetic field inhomogeneity works as a tissue contrast mechanism owing to the spin dephasing effect and the T2* relaxation time perturbation 8–10 19–21. In that context, the occluded vessels will be visualized as a hypointense signal on the image and the proportional reduction in the SI should be considered as consequence of increased RBC concentration.…”

Section: Discussionmentioning

confidence: 99%

“…The hyperdense middle cerebral artery sign was measured with Hounsfield units density on native CT images, and thrombus attenuation was correlated with RBC concentration and recanalization rates 8 9. MRI provides different sequences to extract thrombus analysis data; qualitative analysis being essentially based on individual perception of the ‘negative’ or ‘positive’ appearance of the susceptibility vessels sign (SVS) effect 8 10 11. A positive SVS is also named a ’blooming artifact' and is considered to be a biomarker of RBC-rich thrombi under T2-weighted gradient echo (T2GE) and susceptibility-weighted imaging (SWI) sequences.…”

Section: Introductionmentioning

confidence: 99%

Quantitative estimation of thrombus-erythrocytes using MRI. A phantom study with clot analogs and analysis by statistic regression models

Janot

Oliveira

Fromont-Hankard

et al. 2019

J NeuroIntervent Surg

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BackgroundThrombus composition has the potential to affect acute ischemic stroke (AIS) treatment.ObjectiveTo evaluate in an in vitro test the correlation of clot composition, especially erythrocytes (red blood cells (RBCs)), with the variation of signal intensity ratio (SIR) obtained with MRI sequences used for AIS, and qualification of the susceptibility vessel sign effect using clot analogs.Materials and methodsNine ovine clots were fixed in a gelatin-manganese solution and studied by MRI (T2GE, T2-weighted gradient echo; SWI, susceptibility-weighted imaging; FLAIR, fluid attenuated inversion recovery). RBC concentration was estimated using regression models (SLR, single linear regression; MLR, multiple linear regression; RF, random Forest; and ANN, artificial neural networking), which combined the SIR–histology relationship of three MRI sequences.ResultsNegative correlation was found between SIR and RBC concentration. T2GE SWI could not statistically distinguish clots with RBC content >54% and <23%. SLR was applied only to FLAIR images since T2GE and SWI demonstrated signal saturation. All four regression models showed a correlation between MRI and histology: SLR=0.981; MLR=0.986; RF=0.994, and ANN=0.971. One unknown clot was studied and agreement between SIR and histological analyses was found in all models.ConclusionsWe presented a method to quantify RBC concentration in clot analogs, combining SWI, T2GE, and FLAIR. This in vitro study has some limitations, so clot collection after thrombectomy with simultaneous imaging analysis is necessary to validate this model.

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“…10 Second, no information was registered on the anticoagulation regimen, the use of antiplatelet agents, or the platelet count before imaging, all factors that may have influenced the SVS. Third, the diagnostic accuracy of the SVS to predict thrombus composition varies according the MR imaging machines, 14 and there was no standardization of gradient-echo sequence parameters among the 26 participating centers in the THRACE trial. In our opinion, this limitation enhances the generalizability of our findings.…”

Section: Discussionmentioning

confidence: 99%

Two-Layered Susceptibility Vessel Sign and High Overestimation Ratio on MRI Are Predictive of Cardioembolic Stroke

Bourcier

Derraz

Bracard

et al. 2018

AJNR Am J Neuroradiol

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In a prospective study among patients in the THRombectomie des Artères Cerebrales trial, we analyzed the diagnostic accuracy of 2 imaging biomarkers, the 2-layered susceptibility vessel sign and a high overestimation ratio, obtained on pretreatment brain T2* sequences, to identify cardioembolic stroke etiology (107/260 patients). In combination, these 2 biomarkers, on 1.5T or 3T systems (159 and 101 patients, respectively), demonstrated high specificity (0.77 at 1.5T and 1 at 3T) and their simultaneous presence is highly associated with cardioembolism.ABBREVIATIONS: CES ϭ cardioembolic stroke; HOR ϭ high overestimation ratio; NPV ϭ negative predictive value; overR ϭ overestimation ratio; PPV ϭ positive predictive value; SVS ϭ susceptibility vessel sign; THRACE ϭ THRombectomie des Artères Cerebrales; TL-SVS ϭ 2-layered susceptibility vessel sign

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MRI Interscanner Agreement of the Association between the Susceptibility Vessel Sign and Histologic Composition of Thrombi

Abstract: The diagnostic accuracy of SVS to determine thrombus composition varies significantly among MRI scanners. Normalization of T2*sequences between scanners may be needed to better predict thrombus composition in multicenter studies.

Cited by 21 publications

References 24 publications

MRI Quantitative T2* Mapping to Predict Dominant Composition of In Vitro Thrombus

MRI Quantitative T2* Mapping to Predict Dominant Composition of In Vitro Thrombus

Quantitative estimation of thrombus-erythrocytes using MRI. A phantom study with clot analogs and analysis by statistic regression models

Two-Layered Susceptibility Vessel Sign and High Overestimation Ratio on MRI Are Predictive of Cardioembolic Stroke

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