Acute Ischemic Stroke: False Positives Of The Brain Perfusion Computed Tomography Confirmed After Endovascular Vessel Recanalization

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1 Acute Ischemic Stroke: False Positives Of The Brain Perfusion Computed Tomography Confirmed After Endovascular Vessel Recanalization Poster No.: C-1339 Congress: ECR 2014 Type: Educational Exhibit Authors: E. S. Morales Deza, A. L. Salgado Bernal, J. Peña Suarez, P Vega Valdes, E. Murias ; Oviedo/ES, Gijon/ES Keywords: Emergency, Interventional vascular, Neuroradiology brain, CT, MR-Diffusion/Perfusion, Catheter arteriography, Computer Applications-Detection, diagnosis, Thrombolysis, Ischemia / Infarction DOI: /ecr2014/C-1339 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 17

2 Learning objectives Understand that Perfusión Cerebral Tomography (PCT) could have falses postives to determine the infarcted tissue, which is important to consider before to take the best therapeutic decision. Background #Acute ischemic stroke is a clinical syndrome characterized by acute focal cerebral dysfunction, caused by inadequate cerebral perfusion as a result of decreased blood flow, thrombosis or embolism of the vessels.# They account for 80% of all strokes. #The incidence is estimated at per 100,000 inhabitants / year.# Stroke is the third leading cause of death in Spain.#Risk factors include age, male sex, hypertension, atrial fibrillation (AF), heart failure, diabetes, dyslipidemia, obesity, smoking, alcohol and drug abuse, etc. The multimodal tomographic study in stroke includes standard CT and craniocervical angiographic CT, which exclude nonischemic pathology and determine the vascular occlusion point. Some centers complements with PCT, that depicts the functional status of the cerebral circulation by calculating the mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV) maps to define the core and ischemic penumbra. Images for this section: Page 2 of 17

3 Fig. 1 Page 3 of 17

4 Fig. 2: The key role of nonenhanced CT is the detection of hemorrhage or other possible mimics of stroke (eg, neoplasm, arteriovenous malformation) that could be the cause of the neurologic deficit. Page 4 of 17

5 Fig. 3: The main role of CT angiography is to reveal the status of large cervical and intracranial arteries and thereby help define the occlusion site, depict arterial dissection, grade collateral blood flow, and characterize atherosclerotic disease. Page 5 of 17

6 Fig. 4: Depicts the functional status of the cerebral circulation at tissue level. Perfusion CT can help distinguish the penumbra from infarcted tissue in acute stroke patients. Page 6 of 17

7 Fig. 5: The most reliable method for detecting acute ischemia. The limitations include the time required for MR scanning, cost and limited availability in the emergency setting Page 7 of 17

8 Findings and procedure details #Perfusion CT is performed by monitoring only the first pass of an iodinated contrast agent bolus through the cerebral circulation#the contrast agent passes through the brain tissue, causing a transient hyperattenuation that is directly proportional to the amount of contrast material in the vessels and blood in that region.#the radiation dose is reduced by using lower milliamperage and kilovoltage PROTOCOL OF STUDY: #Equipment: Toshiba Aquilion 64 (TSX-101A/EC), 64 detectors.# 120 kvp.# 80 ma.# Field of View (FOV) 240.# 24 sequential slices, four sections of 8 mm, on the same plane, at the level of basal ganglia.# Patient in supine position. 20G puncture needle# Intravenous injection of nonionic contrast (volume 50ml, concentration 320mg/ml, flow rate 5ml/sec.# Postprocessing software: Toshiba We present 4 cases of patients with ischemic stroke diagnosis secondary to acute obstruction of a great vessel, less than 4.5 hours of clinic, and PCT maps that suggest established infarction with decreased CBV. In some cases MRI diffusion was immediately performed, which was normal or inconclusive to corroborate this finding. Then, mechanical thrombectomy was decided because the suspected infarction was not congruent with the evolution time. Complete arterial recanalization was obtained, and all patients had a good clinical outcome. The imaging controls did not identify established ischemic lesions (or they were minimal) in the territories indicated as core by the CBV maps. Images for this section: Page 8 of 17

9 Fig. 6: Example image acquisition and contrast enhancement protocols for Perfusion CT. Page 9 of 17

10 Fig. 7 Page 10 of 17

11 Fig. 8: Mismatch when CBF or MTT map abnormality greater then core. Mismatch=Penumbra. Page 11 of 17

12 Fig. 9: 68 year old man with 90 minutes of right hemispheric symptoms (NIHSS = 20). NCT shows no significant findings (A). PCT maps depict low CBV in more than 50% of the MCA territory (B) secondary to right ICA dissection (D). No restriction in DW1 (C) previous to treatment. The patient underwent endovascular treatment: two stents were implanted and got complete recanalization (E). NCT after 24 hrs shows minimun infarct that affects the basal ganglia (F). Page 12 of 17

13 Fig. 10: Man, 76 years old. Anticoagulated for Atrial Fibrilation. Left hemispheric neurological symptoms (NIHSS = 22) of two hours duration. NCT is normal (A). The TCP maps show decreased CBV in 40% of the left MCA territory (B) secondary to oclusion of terminal segment of the ICA which involves the A1 and M1 vascular segments (C). Mechanical thrombectomy was performed and complete recanalization without complications was obtained (D). Control NCT scan shows a small subacute ischemic injury in the insula and a lacunar infarction in the left lenticular nucleous (E). Page 13 of 17

14 Fig. 11: Woman 78 year old who presents right hemisphere symptoms of 1 hour and 50 minutes (NIHSS =16) secondary to obstruction of right MCA M1 segment (C). The NCT shows only chronic ischemic lesions (B). Decreased CBV (>1/3 of the MCA territory) is sugested by PCT maps (A), and urgent MRI showed restricted diffusion in less than one third of this territory, mainly affecting the right temporal lobe (D). After complete recanalization of the MCA by mechanical thrombectomy (E), NCT and MRI scan show only small infarction that affect the temporal lobe and insula (F and G). Page 14 of 17

15 Fig. 12: Man 80 years old, anticoagulated for AF, with two hours of right hemispheric neurological symptoms (NIHSS = 18). Basal TC has no pathologic findings. CBV is decreased in the right insula and frontal operculum (B). CTA shows a complicated calcified plaque in the origin of the ICA which produce complete obstruction, and distal thrombus which ocludes the right MCA (C and D). After performing mechanical thrombectomy followed by angioplasty and stenting of carotid artery, the angiographic control shows complete recanalization (E). The control NCT is normal, without established ischemic injury (F). Page 15 of 17

16 Conclusion It is known that under certain physiological, technical and of post-processing conditions, there are good correlation between CBV maps and the final infarcted volumen. Then, it can avoid the need to transfer the patient to another imaging device. Like any other test, there are false positives and negatives, so each case must be individualized. We should consider the time, the clinical parameters and,when it is necessary-available, perform another tests such as MRI diffusion, to value the risk-benefit of the rescue therapies. Personal information References von Kummer R, Allen KL, Holle R, et al. Acute stroke: usefulness of early CT findings before thrombolytic therapy. Radiology 1997; 205: Bozzao L, Bastianello S, Fantozzi LM, et al. Correlation of angiographic and sequential CT findings in patients with evolving cerebral infarction. AJNR Am J Neuroradiol 1989; 10: von Kummer R, Meyding-Lamadé U, Forsting M, et al. Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk. AJNR Am J Neuroradiol 1994; 15: 9-15 Hacke W, Kaste M, Fieschi C, et al. Intravenous thrombolysis with recombinant tissue plasminogen activator for acute hemispheric stroke. The European Cooperative Acute Stroke Study (ECASS). JAMA 1995; 274: von Kummer R, Nolte PN, Schnittger H, et al. Detectability of cerebral hemisphere ischaemic infarcts by CT within 6 h of stroke. Neuroradiology 1996; 38: 31-3 Schriger D, Kalafut M, Starkman S, et al. Cranial computed tomography interpretation in acute stroke. JAMA 1998; 279: Grond M, von Kummer R, Sobesky J, et al. Early X-ray hypoattenuation of brain parenchyma indicates extended critical hypoperfusion in acute stroke. Stroke 2000; 31: Koenig M, Klotz E, Luka B, et al. Perfusion CT of the brain: diagnostic approach for early detection of ischemic stroke. Radiology 1998; 209: Klotz E, König M. Perfusion measurements of the brain: using dynamic CT for the quantitative assessment of cerebral ischemia in acute stroke. Eur J Radiol 1999; 30: Page 16 of 17

17 10. Mayer TE, Hamann GF, Baranczyk J, et al. Dynamic CT perfusion imaging of acute stroke. AJNR Am J Neuroradiol 2000; 21: Esteban JM, Cervera V. Perfusion CT and angio CT in the assessment of acute stroke. Neuroradiology 2004; 46: Cenic A, Nabavi DG, Craen RA, et al. Dynamic CT measurement of cerebral blood flow: a validation study. AJNR Am J Neuroradiol 1999; 20: Wintermark M, Thiran JP, Maeder P, et al. Simultaneous measurement of regional cerebral blood flow by perfusion CT and stable xenon CT: a validation study. AJNR Am J Neuroradiol 2001; 22: Sanelli PC, Lev MH, Eastwood JD, et al. The effect of varying user-selected input parameters on quantitative values in CT perfusion maps. Acad Radiol 2004; 11: Fiorella D, Heiserman J, Prenger E, Partovi S. Assessment of the reproducibility of postprocessing dynamic CT perfusion data. AJNR Am J Neuroradiol 2004; 25: Koenig M, Kraus M, Theek C, et al. Quantitiative assessment of the ischemic brain by means of perfusion related parameters derived from perfusion CT. Stroke 2001; 32: Wintermark M, Reichhart M, Thiran JP, et al. Prognostic accuracy of cerebral blood flow measurements by perfusion computed tomography, at the time of emergency room admission, in acute stroke patients. Ann Neurol 2002; 51: Tomandl BF, Klotz E, Handschuh, et al. Comprehensive imaging of ischemic stroke with multisection CT. Radiographics 2003; 23: Eastwood JD, Lev MH, Wintermark M, et al. Correlation of early dynamic CT perfusion imaging with whole-brain MR diffusion and perfusion imaging in acute hemispheric stroke. AJNR Am J Neuroradiol 2003; 24: Eastwood JD, Lev MH, Azhari T, et al. CT perfusion scanning with deconvolution analysis: pilot study in patients with acute middle cerebral artery stroke. Radiology 2002; 222: Sorensen AG, Copen WA, Ostergaard L, et al. Hyperacute stroke: simultaneous measurement of relative cerebral blood volume, relative cerebral blood flow, and mean tissue transit time. Radiology 1999; 210: Wintermark M, Reichhart M, Cuisenaire O, et al. Comparison of admission perfusion computed tomography and qualitative diffusion- and perfusionweighted magnetic resonance imaging in acute stroke patients. Stroke 2002; 33: Røhl L, Ostergaard L, Simonsen CZ, et al. Viability thresholds of ischemic penumbra of hyperacute stroke defined by perfusion-weighted MRI and apparent diffusion coefficient. Stroke 2001; 32: Neumann-Haefelin T, Wittsack HJ, Wenserski F, et al. Diffusion- and perfusion- weighted MRI. The DWI/PWI mismatch region in acute stroke. Stroke 1999; 30: Page 17 of 17