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Is MRI in the Angiographic Suite a New Frontier?

2021; Radiological Society of North America; Volume: 299; Issue: 1 Linguagem: Inglês

10.1148/radiol.2021204563

1527-1315

Michael H. Lev, Thabele M Leslie‐Mazwi,

Venous Thromboembolism Diagnosis and Management

HomeRadiologyVol. 299, No. 1 PreviousNext Reviews and CommentaryFree AccessEditorialIs MRI in the Angiographic Suite a New Frontier?Michael H. Lev , Thabele M. Leslie-MazwiMichael H. Lev , Thabele M. Leslie-MazwiAuthor AffiliationsFrom the Departments of Radiology (M.H.L.), Neurosurgery (T.M.L.M.), and Neurology (T.M.L.M.), Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114-2622.Address correspondence to M.H.L. (e-mail: [email protected]).Michael H. Lev Thabele M. Leslie-MazwiPublished Online:Feb 9 2021https://doi.org/10.1148/radiol.2021204563MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In See also the article by Narsinh et al in this issue.Dr Michael H. Lev is director of emergency radiology and emergency neuroradiology at Massachusetts General Hospital (Boston, Mass) and professor of radiology at Harvard Medical School (Cambridge, Mass). He is an elected fellow of both the American Heart Association and the American College of Radiology and has longstanding involvement in funded research. He served as a deputy editor for Radiology from 2007 to 2009 and continues as a senior consultant to the editor.Download as PowerPointOpen in Image Viewer Dr Thabele Leslie-Mazwi is the director of endovascular stroke services at Massachusetts General Hospital and a neuroendovascular and neurocritical care neurologist. His research interests are broad but mainly focused on large vessel occlusion treatment. He holds multiple stroke leadership roles, is closely involved in the major societies in the field and, among other things, believes passionately that improved care delivery will unlock the true potential of thrombectomy for stroke treatment.Download as PowerPointOpen in Image Viewer In 1927, after much trial and error, Dr António Egas Moniz of Portugal produced what is to our knowledge the world’s first arterial encephalography. This made it possible to directly view in situ the cerebral circulation by using radiography with intravascular radiopaque contrast material (1). Although it was Dr Moniz’s later innovations in psychosurgery (ie, frontal lobotomy) that led to his 1949 Nobel Prize, this revolutionary advance facilitated noninvasive assessment and localization of intracranial abnormalities by direct viewing of the displacement of the cerebral vasculature. Indeed, this technique remained essential to neurodiagnostics until the advent of cross-sectional imaging with CT in 1974. Early and steadfast efforts by Moniz evolved into contemporary cerebral angiography, ultimately resulting in the field of neuroendovascular radiology, with its capability to help diagnose, manage, and treat a wide range of lesions in the central nervous system. Despite these successes, one challenge remains true for both Moniz and today’s angiographer: Although angiographic data provide vascular luminal information, there is no direct information about brain tissue.Brain parenchymal tissue assessment requires cross-sectional CT or MRI. In angiography suites, this is routinely available in the form of cone-beam CT capability. This technique generates CT-like images from rotational, C-arm angiographic acquisitions, with the patient on the procedure table. The impact of this CT-based tissue assessment on endovascular practice varies. Cone-beam CT images allow for detection of interventional hemorrhagic complications and evaluation of low-density intracranial stents and coil packing of aneurysms, whereas three-dimensional CT angiography helps delineate vessel anatomy with small volume boluses of radiographic contrast material. This dynamic scanning capability also permits perfusion imaging (2). Conventional C-arm CT has been further refined to enhance the information obtained from the scan, including but not limited to improvements in spatial resolution and reduction in metal artifacts (3). With increasing accuracy and speed, the clinical implications and applications of this imaging technology continue to expand. A recent example is the increasing transfer of patients suspected of having large-vessel occlusive stroke directly to the angiography suite for their initial imaging, bypassing fixed CT and MRI scanners in the emergency department (4).Whereas the role of CT in the angiography suite is already widely recognized and accepted, the integration of MRI into angiography suites has yet to be established. Because MRI technology, unlike CT, cannot be incorporated into existing C-arm units, hybrid angiography suite and MRI installation configurations are variable. These configurations include layouts that require patients to be moved into separate scanner rooms and floor plans where the scanner is advanced from an adjoining “barn” into the angiography suite (5). Although MRI provides unparalleled tissue definition (particularly regarding acute ischemic changes at diffusion-weighted imaging), MRI, again unlike CT, additionally necessitates the implementation of strict safety requirements, which must be maintained despite the wide variety of equipment used in interventional suites. Moreover, a range of highly trained staff, including technologists, nurses, anesthesiologists, residents, and fellows, must sustain familiarity with the MRI environment to assure safe and efficient interventional procedures. Furthermore, there is a substantial difference between CT and MRI scanners and installation costs. For these and other reasons, intraprocedural use of MRI in the neurointerventional suite remains rare.In this issue Radiology, Dr Narsinh and colleagues (6) describe their experience with a hybrid angiography and 3.0-T MRI suite. They present a series of patients with acute stroke evaluated by using MRI during endovascular procedures as a proof of concept and assess the impact of this imaging on intraprocedural decision making.In stroke, diffusion-weighted imaging is the operational reference standard for imaging evaluation of cerebral tissue viability. Diffusion-weighted imaging enables direct assessment of changes in water diffusivity attributable to cytotoxic edema, which helps to identify with high accuracy tissue that is likely to have an irreversible infarct. The study by Narsinh et al (6) applied the information gained from diffusion-weighted imaging to procedural decision making in patients undergoing stroke thrombectomy. The hybrid room design allowed for patient transport on a dockable table between their biplane angiographic system and the 3.0-T MRI scanner. The decision to use MRI and the specific pulse sequences were at the discretion of the treating proceduralist. At minimum, all patients underwent diffusion-weighted imaging for delineation of the core infarction. Additional sequences including susceptibility-weighted imaging for microbleed depiction and perfusion imaging for depicting ischemic at-risk tissue were used on a case-by-case basis, depending on the clinical scenario. Of 47 consecutive patients undergoing thrombectomy, 12 patients underwent intraprocedural MRI and were included in the analysis. In all 12 patients, MRI had a substantial impact on decision making, with the types of decisions stratified by the authors into three categories.The first decision category was whether to proceed with the thrombectomy procedure. For four patients, the MRI scan showed either sufficient viable tissue to continue recanalization attempts (two patients) or too large an infarct to justify further treatment (two patients). The second decision category was regarding intracranial stent placement for patients with symptomatic atherosclerotic disease as the cause of their stroke (three patients). In two of these three patients, diffusion-weighted imaging showed a small infarct with border zone pattern, which supported the decision for stent placement following antiplatelet agent administration. In another patient, the entire at-risk territory already showed an infarct; these MRI results argued against stent placement because of the increased risk of hemorrhagic transformation with dual antiplatelet therapy. The third and final decision category related to postprocedural blood pressure and antithrombotic medication management. Infarct size or hemorrhagic conversion informed the use of antithrombotic medication in three patients and permissive hypertension in two (for the interested reader, these details are documented in the article’s Appendix E1 [online]).Although the average image acquisition time was 12 minutes ± 11 (standard deviation), total transfer time between the angiography unit and MRI scanner, which included the time for MRI safety screening, was considerably longer at 45 minutes ± 27. This additional time required for MRI assessment clearly risks the possibility of infarct progression (ie, “time is brain”), which has the potential to nullify the benefits of the MRI data acquisition. Workflow optimization therefore becomes an important target for the operator. Although there were several other limitations to this nonrandomized retrospective single-center study of 12 patients, the message was clear: The combination of MRI and angiographic data was feasible and had a positive impact on intraprocedural treatment decisions in patients with acute stroke.Widespread adoption of a hybrid MRI and angiography suite will require definitive demonstration of the benefits versus the costs of this technology. Speed and practicality will be key factors, especially in situations where minutes matter. Because stents and flow diverters must be imaged soon after implantation, MRI device safety will be paramount (7). An exciting opportunity in the future development of hybrid MRI and angiography suites is the recent progress made with low-field-strength strength (eg, 0.06 T) portable MRI (8,9). Such devices could hypothetically be wheeled into and out of the angiography suite, decreasing capital costs for upgrade and installation, allowing service of multiple angiographic suites with a single scanner, and mitigating high-field-strength strength safety concerns for MRI conditional devices.In summary, Narsinh et al (6) showed that additional, MRI-derived information regarding brain parenchymal tissue status is feasible and may be valuable in making intraprocedural therapeutic decisions for patients with acute stroke in the angiography suite. Although the impact of that information relative to its cost, time, and safety considerations remains an open question, it is not hard to imagine the role of this approach in other neurovascular disease states. Much work remains to be done, but the ability to view both the vasculature and the brain parenchyma, in real time, suggests that the realization of the dream that Dr Antonio Egas Moniz introduced almost a century ago is within our grasp.Disclosures of Conflicts of Interest: M.H.L. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: disclosed money paid to author for consultancy from Takeda Pharm; money to author’s institution for grants/grants pending from GE Healthcare; and patents pending for EIS, AI. Other relationships: disclosed no relevant relationships. T.M.L.M. disclosed no relevant relationships.References1. Doby T. Cerebral angiography and Egas Moniz. AJR Am J Roentgenol 1992;159(2):364. Crossref, Medline, Google Scholar2. Kamran M, Nagaraja S, Byrne JV. C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology. Neuroradiology 2010;52(4):319–327. Crossref, Medline, Google Scholar3. Li TF, Ma J, Han XW, et al. Application of High-Resolution C-Arm CT Combined with Streak Metal Artifact Removal Technology for the Stent-Assisted Embolization of Intracranial Aneurysms. AJNR Am J Neuroradiol 2019;40(10):1752–1758. Medline, Google Scholar4. Mendez B, Requena M, Aires A, et al. Direct Transfer to Angio-Suite to Reduce Workflow Times and Increase Favorable Clinical Outcome. Stroke 2018;49(11):2723–2727. Crossref, Medline, Google Scholar5. White MJ, Thornton JS, Hawkes DJ, et al. Design, operation, and safety of single-room interventional MRI suites: practical experience from two centers. J Magn Reson Imaging 2015;41(1):34–43. Crossref, Medline, Google Scholar6. Narsinh KH, Kilbride BF, Mueller K, et al. Combined use of x-ray angiography and intraprocedural MRI enables tissue-based decision making regarding revascularization during acute ischemic stroke intervention. Radiology 2021;299:167–176. Link, Google Scholar7. Russo RJ, Costa HS, Silva PD, et al. Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator. N Engl J Med 2017;376(8):755–764. Crossref, Medline, Google Scholar8. Sheth KN, Mazurek MH, Yuen MM, et al. Assessment of Brain Injury Using Portable, Low-Field Magnetic Resonance Imaging at the Bedside of Critically Ill Patients. JAMA Neurol 2020. 10.1001/jamaneurol.2020.3263. Published online September 8, 2020. Google Scholar9. Cooley CZ, McDaniel PC, Stockmann JP, et al. A portable scanner for magnetic resonance imaging of the brain. Nat Biomed Eng 2020. 10.1038/s41551-020-00641-5. Published online November 23, 2020. Crossref, Medline, Google ScholarArticle HistoryReceived: Dec 11 2020Revision requested: Dec 29 2020Revision received: Dec 29 2020Accepted: Jan 4 2021Published online: Feb 9 2021Published in print: Apr 2021 FiguresReferencesRelatedDetailsAccompanying This ArticleCombined Use of X-ray Angiography and Intraprocedural MRI Enables Tissue-based Decision Making Regarding Revascularization during Acute Ischemic Stroke InterventionFeb 9 2021RadiologyRecommended Articles Diving into a Shallow Pool: Endovascular Treatment for Basilar Artery OcclusionRadiology2019Volume: 291Issue: 3pp. 738-739Automated Detection of Large Vessel Occlusion in Acute Stroke: Faster Imaging Assessment for Faster TreatmentRadiology2021Volume: 298Issue: 3pp. 671-672Combined Use of X-ray Angiography and Intraprocedural MRI Enables Tissue-based Decision Making Regarding Revascularization during Acute Ischemic Stroke InterventionRadiology2021Volume: 299Issue: 1pp. 167-176Perfusion from Diffusion: Yet Another Take on MismatchRadiology2022Volume: 307Issue: 1Cervical Internal Carotid Occlusion versus Pseudo-occlusion at CT Angiography in the Context of Acute Stroke: An Accuracy, Interobserver, and Intraobserver Agreement StudyRadiology2017Volume: 286Issue: 3pp. 1008-1015See More RSNA Education Exhibits Acute Ischemic Stroke: Time is Life — An Approach for No MistakesDigital Posters2019MRI Evaluation Of Thrombectomy Candidates In Acute Ischemic Stroke (AIS): Is It Time For A Change?Digital Posters20212022: a Stroke Flowchart Odyssey in the Emergency RoomDigital Posters2022 RSNA Case Collection Acute ischemic strokeRSNA Case Collection2020Superior sagittal sinus thrombosisRSNA Case Collection2022Cerebral Air EmboliRSNA Case Collection2021 Vol. 299, No. 1 Metrics Altmetric Score PDF download