CTA vs. MRA: Advantages. MRA and CTA of the Head and Neck. DSA vs. CTA and MRA. Left MCA AIS: 8 hours from onset. Left MCA AIS: 8 hours from onset

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1 MRA and CTA of the Head and Neck Ronald L. Wolf, M.D., Ph.D. University of Pennsylvania Medical Center CT/CTA Faster CTA vs. MRA: Advantages Better 24/7 availability Unstable patients, pacemakers or other MR contraindications, etc. Better with some hardware (eg, titanium clips) Bone depiction, landmarks MRI/MRA More options for image contrast (eg, DWI) Better functional imaging options No ionizing radiation Better with some hardware (eg, aneurysm coils) Less sensitive to calcification/ossification DSA vs. CTA and MRA Large coiled aneurysm - which is best? CT Excellent spatial and temporal resolution Individual vessels/territories routinely resolved Rotational angiography available Diagnostic plus interventional But Invasive, with small risk Ionizing radiation Not optimal for screening or multiple follow ups Lumen only DWI CE MRA (source image) Left MCA AIS: 8 hours from onset Left MCA AIS: 8 hours from onset Small infarct, MCA occlusion, and tissue at risk (DWI/PWI mismatch)

2 Acute Left MCA Occlusion with Baseline Stenosis Acute Ischemic Syndrome, ~ 6 hours NECT CTA source axial Acute Ischemic Syndrome, ~ 6 hours CTA: occluded RICA, extended infarct CTP: small mismatch Intracranial Stenosis MRA, CTA good for normal and severe stenoticocclusive disease, problem in between MRA good negative predictive value for excluding 50-99% but low positive predictive value (SONIA - Neurology 2007; 68: 2099) CTA NPV (about 84%) also better than PPV in SONIA (Ann Neurol 2009; 667: 30) CTA may be better than this, e.g., sensitivity/specificity for detecting 50% stenosis 97.1 and 99.5% in a recent study (Neurology 2008; 39: 1184) Source data, coronal reformat Axial MIP Axial MIP Left MCA stenosis Vertebral Artery Occlusion CTA: Coronal MIP MRA: Coronal MIP DSA 2D TOF MRA source images 2D TOF MRA MIP

3 Distal Vertebral Artery Occlusion CTA better than MRA for slow flow CTA Heavy calcification can limit accuracy CTA: slab-mip Atherosclerotic Calcifications CTA overestimated degree of stenosis ICA Aneurysm CTA better than MRA in depicting bony landmarks MRA CTA Sinus Thrombosis Sinus Thrombosis SAG PC MRV COR PC MRV

4 CT Venography MR Venography: Stenosis Meningioma 2D TOF MRV 3D CE-MRV Initial NECT Catastrophic Acute SAH CTA only NECT + CTA 40 minutes later Aneurysm Detection Ruptured Aneurysm but Missed Unruptured Aneurysm on CTA CTA excellent for demonstrating ruptured aneurysm site, with good sensitivity and specificity improving with MDCT Wintermark et al, J Neurosurg 2003; 98: 828 Hoh et al, Neurosurgery 2004; 54: 1329 MRA probably better choice for screening Both with 3D data for rendering, though now have rotational angiography with DSA MRA and CTA have decreased performance with aneurysm <3mm Left Left

5 CTA Leading to Shorter DSA Acute SAH PICA Aneurysm Angio negative DSA vertebral artery spasm Screening: 3D TOF MRA at 3T Dolichoectasia and Aneurysm Dolichoectasia and Aneurysm

6 Aneurysm Coils: CTA vs. MRA Aneurysm Clips: CTA vs. MRA CT CT 3D TOF MRA: Source 3D TOF MRA 3D CE MRA: Source 3D TOF MRA: MIP 3D CE MRA: MIP CTA Thrombus Cobalt alloy CTA: Aneurysm Clips Titanium Vascu-Statt plastic Carbon-Elgiloy Cobalt alloy mm slices, 140 kv, 380 ma, pitch of 0.96 Left nonoverlapping and right overlapping sections Mamourian et al, J Neurosurg 2007; 107: 1238 Vasospasm Wintermark et al, AJNR 2006 Encephalopathy, Progressive Infarcts DWI ADC CE MRA ADC

7 Left Carotid CE MRA: intracranial dz exaggerates extracranial dz VZV Vasculitis Progressive infarcts and progressive ICA stenosis DSA 2 days later Vasculitis/Vasculopathy Neurosyphilis Catastrophic Bleed and AVM Dural AVF T11 level preembolization

8 Time-Resolved MRA: AVM Temp resolution: 1s In-plane resolution: 1 x 1mm² at 3.0T using GRAPPA x4 Nael et al, ISMRM 2005 Temp resolution: 1s In-plane resolution: 1 x 1mm² at 3.0T using GRAPPA x4 Courtesy of K. Nael, UCLA Atherosclerosis and Ischemia Hemodynamic impairment = reduced cerebral perfusion pressure Sources and modifying factors Arterial stenosis or occlusion Collateral status Compensatory mechanisms Autoregulation Increased oxygen extraction Plaque structure and content ( vulnerable plaque ) CTA vs. DSA: 50-60% LICA Stenosis AP LAT AP LAT CE-MRA CE MRA: Carotid Stenosis DSA CE-MRA DSA CTA, MRA: Cervical Occlusive Disease Multidetector CTA and CE MRA good for 70% or greater carotid artery stenosis or occlusion (Wardlaw et al, Lancet 2006; 367: 1503) For lesser degree of stenosis (50-69%), accuracy less clear Combination of noninvasive tests: DUS, MRA, CTA: if 2/3 disagree, adding 3 rd decreases mistakes (Patel et al, JNNP 2002) High-grade Moderate Courtesy of John Huston, MD

9 Occlusion and Near-Occlusion Improving Temporal Resolution Time-resolved CE MRA: Right subclavian steal CTA CEMRA string sign CTA string sign Temp resolution 1.5s, In-plane resolution: 1 x 1.3 x 4mm 3, at 3.0T using GRAPPA x3, TREAT, partial Fourier 6/8 Courtesy of K. Nael, UCLA (Nael et al, Invest Radiol 2006; 41: 116) Vulnerable Plaque Plaque Ulceration Lipid Core lumen Hemorrhage lumen (Ca Unstable ++ ) fibrous cap Thinning or defect, including ulceration SCM lipid core hemorrhage Inflammatory cell infiltrate TOF T1W FSE PDW DIR T2W DIR Type IV Plaque CTA Arterial Dissection and Trauma Spontaneous vs. traumatic Extracranial usually does not extend intracranial, better prognosis than for intracranial dissection Imaging findings: Enlarged vessel cross section or caliber change Wall hematoma (may not be T1-bright acutely) Pseudoaneurysm

10 Carotid Artery Dissection Dissection: Wall Hematoma Vertebral Artery Dissection Subarachnoid hemorrhage presentation Traumatic Arterial Injury Penetrating and blunt carotid/vertebral injury Incidence <1% of all blunt trauma patients, but 30% - 40% of high risk patients (Biffl) Screening Indications Neurologic deficit Adjacent penetrating injury Fractures Severe blunt trauma to neck Hyperextension/hyperflexion Seatbelt sign MRA and CTA reasonable for screening MRI and MRA probably better for BCVI, CTA is also good CTA better for penetrating injury Seatbelt Injury Right MCA branch infarct Carotid Dissection

11 Carotid Canal Fracture Dissection and Pseudoaneurysm CTA: Carotid Transection and Infarct Penetrating Injury: GSW GSW: Carotid Dissection Intraluminal thrombi better depicted on CTA DSA GSW Head: VB Transection/Occlusion CTA source Cor MIP VR

12 FMD on CTA (ICA) Giant Cell Arteritis Wall pathology better depicted on CT cross section OBL LAT OBL LAT Right Left Takayasu Arteritis Wall pathology better depicted on MR cross section Stents: : MRA vs. CTA Variables: material, orientation, diameter (AJNR 2009; 30: 1993) -C CE MRA CTA SMART Stent (nitinol, Cordis) + C 2D TOF MRA CTA WALLSTENT (stainless steel, Boston Scientific) Conclusions Technique of choice depends on Clinical question and flow dynamics of vascular territory Resolution and field of view Physiologic motion Need for speed MRA and/or CTA augments and for some applications can replace conventional angiography. Acknowledgments John Huston, III, MD Mayo Clinic Linda Bagley, MD Hospital of University of Pennsylvania Pat Reilly, MD Hospital of University of Pennsylvania Richard Farb, MD Toronto Western Hospital Kambiz Nael, MD David Geffen School of Medicine at UCLA Chuck Mistretta, PhD University of Wisconsin, Madison