Martin Bretzner1, Renaud Lopes2, Ray McCarthy3, Delphine Corseaux4, Florent Auger5, Gillian Gunning3, Nicolas Beauval6, Antonino Bongiovanni7, Meryem Tardivel7, Charlotte Cordonnier8, Jean-Pierre Pruvo2, Sophie Susen4, Xavier Leclerc2, Grégory Kuchcinski2. 1. Inserm U1171 Degenerative & Vascular Cognitive Disorders, University of Lille, 59000 Lille, France; CHU de Lille, Department of Neuroradiology, 59000 Lille, France. Electronic address: martin.bretzner@gmail.com. 2. Inserm U1171 Degenerative & Vascular Cognitive Disorders, University of Lille, 59000 Lille, France; CHU de Lille, Department of Neuroradiology, 59000 Lille, France. 3. Cerenovus, Neuravi Thromboembolic Initiative, Galway, Ireland. 4. Inserm U1011-EGID, Lille, France; Institut Pasteur de Lille, Lille, France; CHU Lille, Hematology and Transfusion, 59000, Lille, France. 5. Inserm U1171 Degenerative & Vascular Cognitive Disorders, University of Lille, 59000 Lille, France. 6. CHU Lille, Unité Fonctionnelle de Toxicologie, 59000 Lille, France. 7. Bio imaging center Lille Nord-de-France Campus HU, faculté de médecine, Université de Lille, 59000 Lille, France. 8. CHU de Lille, Department of Neurology, 59000 Lille, France.
Abstract
BACKGROUND AND PURPOSE: Previous studies have suggested that mechanical revascularization in acute ischemic stroke (AIS) patients could be affected by clot histology. In this 7-T micro-MRI study, we used R2* relaxometry of clot analogs to evaluate the relationship between texture parameters of R2* maps and clot constituents. MATERIALS AND METHODS: Twelve AIS clot analogs were experimentally generated to obtain a wide range of red blood cell concentrations. All clots underwent a MR acquisition using a 7-T micro-MR system. A 3D multi-echo gradient-echo sequence was performed and R2* maps were generated. First order and second order statistics of R2* histograms within the clots were calculated. Iron concentration in clots was measured using absorption spectrometry and red blood cell count (RBC) was obtained by histopathological analysis. RESULTS: RBC count was strongly correlated with iron concentration within clots (r=0.87, P<.001). Higher RBC count and iron concentration were significantly correlated with first order parameters including: (a) global positive shift of the R2* histogram with higher '10th percentile', 'median', 'mean' and '90th percentile'; (b) increase of the global magnitude of voxel values with higher 'total energy' and 'root mean squared'; (c) greater uniformity of the voxel values with higher 'uniformity' and lower 'entropy'. Second order statistical parameters confirmed that higher RBC count and iron concentration correlated with (a) greater concentration of high gray-level values in the image; (b) more "coarse" texture of R2* maps. CONCLUSIONS: Texture analysis of MRI-R2* maps can accurately estimate the red blood cell count and iron content of AIS clot analogs.
BACKGROUND AND PURPOSE: Previous studies have suggested that mechanical revascularization in acute ischemic stroke (AIS) patients could be affected by clot histology. In this 7-T micro-MRI study, we used R2* relaxometry of clot analogs to evaluate the relationship between texture parameters of R2* maps and clot constituents. MATERIALS AND METHODS: Twelve AIS clot analogs were experimentally generated to obtain a wide range of red blood cell concentrations. All clots underwent a MR acquisition using a 7-T micro-MR system. A 3D multi-echo gradient-echo sequence was performed and R2* maps were generated. First order and second order statistics of R2* histograms within the clots were calculated. Iron concentration in clots was measured using absorption spectrometry and red blood cell count (RBC) was obtained by histopathological analysis. RESULTS: RBC count was strongly correlated with iron concentration within clots (r=0.87, P<.001). Higher RBC count and iron concentration were significantly correlated with first order parameters including: (a) global positive shift of the R2* histogram with higher '10th percentile', 'median', 'mean' and '90th percentile'; (b) increase of the global magnitude of voxel values with higher 'total energy' and 'root mean squared'; (c) greater uniformity of the voxel values with higher 'uniformity' and lower 'entropy'. Second order statistical parameters confirmed that higher RBC count and iron concentration correlated with (a) greater concentration of high gray-level values in the image; (b) more "coarse" texture of R2* maps. CONCLUSIONS: Texture analysis of MRI-R2* maps can accurately estimate the red blood cell count and iron content of AIS clot analogs.
Authors: S T Fitzgerald; Y Liu; D Dai; O M Mereuta; M Abbasi; J L A Larco; A S Douglas; D F Kallmes; L Savastano; K M Doyle; W Brinjikji Journal: AJNR Am J Neuroradiol Date: 2021-04-08 Impact factor: 4.966