By Barbara Casolla, MD, PhD, Univ. Lille, Inserm U1172, Degenerative and Vascular Cognitive Disorders, CHU Lille, Department of Neurology, France
In the acute stroke setting, accurate estimation of ischemic core volume has important therapeutic and prognostic implications. However, ischaemic core volume thresholds need to be interpreted with caution. Indeed, type of neuroimaging and technical parameters impact reproducibility, intraobserver and interobserver variability and therefore, measurement results1–4. Automated software limits human errors but introduce a software-related variability. Moreover, neuronal death “maturation” is a dynamic process, in both time and space, and delays of ischaemic core volume measurement from stroke onset also impact its clinical meaning.
Diffusion-weighted magnetic resonance imaging (DWI) measures cytotoxic edema: it has been considered the gold standard for ischemic core estimation and it is the most accurate method for prediction of malignant middle cerebral artery (MCA) infarct4,5. Accordingly, infarct volume thresholds for decompressive hemicraniectomy (DH) indications are based on b-1000 DWI6–8. However, in the era of mechanical thrombectomy, infarct volume measurement is routinely performed using semi-automatic methods based on apparent diffusion coefficient (ADC) maps9. Discrepancies between infarct volumes on b-1000 DWI and ADC are expected, because ischaemic region on b-1000 DWI contains voxels with a wide range of ADC values and potentially different physiopathological meanings. Therefore, using ADC maps instead of b-1000 DWI volumes for DH candidates may have implications for surgery indications and prognostic prediction. For instance, in patients treated with DH for large MCA infarcts, the cut off for the prediction of catastrophic outcome (defined as a modified Rankin Scale (mRS) of 5 or 6) differs according to the methods of measurement, with significantly higher optimal b-1000 DWI volume thresholds compared to ADC maps10. Importantly, b-1000 DWI and ADC volume thresholds seem to have similar sensitivity and specificity, suggesting that both of them can be used in clinical practice10.
Indeed, as elegantly discussed in a recent review, clinicians should be aware that the physiopathological meaning of the ischaemic core volume is uncertain and needs clinical interpretation in the real life4. This is an important field of research with many potential implications, for acute phase therapy and beyond.
- Brott T, Marler JR, Olinger CP, Adams HP, Tomsick T, Barsan WG, Biller J, Eberle R, Hertzberg V, Walker M. Measurements of acute cerebral infarction: lesion size by computed tomography. Stroke. 1989;20:871–875.
- van der Worp HB, Claus SP, Bär PR, Ramos LM, Algra A, van Gijn J, Kappelle LJ. Reproducibility of measurements of cerebral infarct volume on CT scans. Stroke. 2001;32:424–430.
- Schaefer PW, Souza L, Kamalian S, Hirsch JA, Yoo AJ, Kamalian S, Gonzalez RG, Lev MH. Limited Reliability of Computed Tomographic Perfusion Acute Infarct Volume Measurements Compared With Diffusion-Weighted Imaging in Anterior Circulation Stroke. Stroke. 2015;46:419–424.
- Goyal M, Ospel JM, Menon B, Almekhlafi M, Jayaraman M, Fiehler J, Psychogios M, Chapot R, van der Lugt A, Liu J, et al. Challenging the Ischemic Core Concept in Acute Ischemic Stroke Imaging. Stroke . 2020 ;Available from: https://www.ahajournals.org/doi/10.1161/STROKEAHA.120.030620
- Oppenheim C, Samson Y, Manaï R, Lalam T, Vandamme X, Crozier S, Srour A, Cornu P, Dormont D, Rancurel G, et al. Prediction of Malignant Middle Cerebral Artery Infarction by Diffusion-Weighted Imaging. Stroke. 2000;31:2175–2181.
- Vahedi K, Vicaut E, Mateo J, Kurtz A, Orabi M, Guichard J-P, Boutron C, Couvreur G, Rouanet F, Touzé E, et al. Sequential-design, multicenter, randomized, controlled trial of early decompressive craniectomy in malignant middle cerebral artery infarction (DECIMAL Trial). Stroke. 2007;38:2506–2517.
- Vahedi K, Hofmeijer J, Juettler E, Vicaut E, George B, Algra A, Amelink GJ, Schmiedeck P, Schwab S, Rothwell PM, et al. Early decompressive surgery in malignant infarction of the middle cerebral artery: a pooled analysis of three randomised controlled trials. Lancet Neurol. 2007;6:215–222.
- European Stroke Organisation (ESO) Executive Committee, ESO Writing Committee. Guidelines for management of ischaemic stroke and transient ischaemic attack 2008. Cerebrovasc. Dis. 2008;25:457–507.
- Lansberg MG, Straka M, Kemp S, Mlynash M, Wechsler LR, Jovin TG, Wilder MJ, Lutsep HL, Czartoski TJ, Bernstein RA, et al. MRI profile and response to endovascular reperfusion after stroke (DEFUSE 2): a prospective cohort study. Lancet Neurol. 2012;11:860–867.
- Casolla B, Kuchcinski G, Kyheng M, Hanafi R, Lejeune J-P, Leys D, Cordonnier C, Hénon H. Infarct Volume Before Hemicraniectomy in Large Middle Cerebral Artery Infarcts Poorly Predicts Catastrophic Outcome. Stroke. 2020;51:2404–2410.