M Suzuki 1, R Irie 1, N Takano 2, M Yamamoto 3, M Hori 1, K Kumamaru 1, K Kamagata 1, A Hagiwara 1, T Tabata 1, H Oishi 2, S Aoki 1 1 Juntendo University School of Medicine, Tokyo, Japan, 2 Juntendo University Hospital, Tokyo, Japan 3 Juntendo University School of Medicine, Department of Neuroendovascular Therapy, Tokyo, Japan BASICS AND CLINICAL APPLICATION OF ULTRASHORT TE MRA COMBINED WITH ARTERIAL SPIN LABELING ALGORITHEM - SILENT MRA -

Discovery MR750w Expert 3.0T (GE-MS) Magnetic resonance angiography based on a Silenz algorithm. Because the Silenz algorithm acquires data just after RF-pulse excitation (ultrashort echo time: UTE), susceptibility or dephasing artifact is reduced. To visualize a blood flow, in an algorithm, uses an arterial-spin-labeling (ASL) technique as preparation pulse, and UTE by 3D radial sampling for data acquisition.

Silent Scan Technology Magnetic gradient: Sequence chart of common 3D data acquisition RF pulse: Data sampling: TE Sequence chart of SILENT SCAN (Silenz ) TE = zero 0.018ms Magnetic gradient: RF pulse: Data sampling: spoke This slide is supplied by a courtesy of GE medical systems, Japan

The blood within the carotid arteries is “tagged” using a long RF inversion pulse commonly referred to as a “ Labeling ” pulse. Once the blood is tagged, it is allowed to flow into the vasculature and captured by the Silenz acquisition. This is followed by the collection of a control dataset where a “Labeling” pulse is applied above the head to minimize magnetization transfer effects and to control artifacts. these two datasets are subtracted to eliminate the background, leaving a depiction of the entire vascular tree. SILENT SCAN TECHNOLOGY

SPOKES PER SEGMENT Few parameter were able to handle in the MR console. In a few parameter, spoke number per segment seemed to enhance a signal, and we confirmed with circulatory flow phantom. Spokes per Segment : 128, 256, 512 Bandwidth : ±20 kHz Flow velocity : 25, 40 cm/sec

THE BLOOD FLOW VISUALIZATION ABILITY IN THE INTRACRANIAL STENT AT EACH CONDITION 25 cm/sec 40 cm/sec Matrix : 150×150 、 Thickness : 1.2mm 、 BW: ±20kHz 、 1NEX Enterprise VRD® 25cm/sec Spokes : NEX 7:40 8:08 Spokes per Segment Signal intensity was enhanced by decreasing spokes number. 1.0 NEX 1.5 NEX 1.0 NEX

THE TIME CHART OF ASL IN THE SILENT MRA ・ Signal intensity was enhanced by decreasing spokes number. ・ Data acquisition seemed to be done before the attenuation of labeled signal → results in a signal enhancement

TOF-MRA Based on a in-flow effect Long scan time Effect by a saturation effect Difficult to demonstrate a slow fblood flow Possibility of a signal loss due to a fast, whirlpool and turbulance flow Difficult to depict a flow that runs parallel to a scan slice Comparison with existing TOF-MRA

TOF-MRA Based on a in-flow effect Long scan time Effect by a saturation effect Difficult to demonstrate a slow fblood flow Possibility of a signal loss due to a fast, whirlpool and turbulance flow Difficult to depoct a flow that runs parallel to a scan slice SILENT-MRA Very quiet scan ( + 3dB with environmental sound ) Based on ASL, ultra short TE and a subtraction of T1WI Similar scan time with TOF-MRA Never affected by a saturation effect Easy to depict a slow blood flow Homogeneous depiction of a slow, whirlpool and turbulence flow Never affected by a flow direction ⇒ Whenever the flow exists, depicted precisely Comparison with exisiting TOF-MRA

SCAN PROTOCOL MRAs were scanned in the same session on 3T unit (Discovery MR750w 3.0T, GE Healthcare, Milwaukee, WI, U.S.A.). Silent MRAs : TR/TE, /0.016 msec; flip angle, 5°; field of view, 180×180 mm; matrix, 150×150; section thickness, 1.2 mm; number of excitations (NEX), 1.5; band width, ±20 kHz; and acquisition time, 7 min 40 s. TOF MRAs : TR/TE, 19/2.9 msec; flip angle, 15°; field of view, 200×200 mm; matrix, 416×192; section thickness, 1.2 mm; NEX, 1; band width, ±41.7 kHz; and acquisition time, 3 min 31 s. In some patients, DSA was performed with the following angiographic systems: AXIOM Artis dTA (Siemens AG, Erlangen, Germany) until February 2014 and Artis Q BA Twin (Siemens AG).

SILENT MRA ① Ultra short TE Reduced Susceptibility artifact Reduced Metallic artifact ② Arterial spin labeling Enabled to depict a very slow flow, regardless of its direction ③ Subtraction of T1-weighted images Characteristics of ⇒ Treatment for a brain aneurysm ・ coiling ・ stent assisted coil embolization ・ clipping ⇒ Moyamoya disease dural AVF, AVMs ⇒ subarachnoid hemorrhage dissecting aneurysm There are 3 major efficacies that can produce SILENT MRA images.

SILENT MRA ① Ultra short TE Reduced Susceptibility artifact Reduced Metallic artifact ② Arterial spin labeling Enabled to depict a very slow flow, regardless of its direction ③ Subtraction of T1-weighted images Characteristics of ⇒ Treatment for a brain aneurysm ・ coiling ・ stent assisted coil embolization ・ clipping ⇒ Moyamoya disease dural AVF, AVMs ⇒ subarachnoid hemorrhage dissecting aneurysm Let’s strart from the UTE effect !

APPLICATION FOR STENT ASSISTED COIL EMBOLIZATION (SACE) There is a limitation to evaluate a precise recanalization even with an angiogram Prevalence of late in-stent restenosis is 5% (0.8~20%) ⇊ Need to establish a reliable method for restenosis of recanalization ① Ultra short TE Sergin Akpek et al. AJNR Am J Neuroradiol 2005;26:

SACE 1 TOF Silent Stent is deployed between the yellow arrows. Dephasing due to a susceptibility effect was reduced Out pouching of stented part and in-stent flow was evident on Silent MRA Rt carotid angiogram ① Ultra short TE Irie R, et al. AJNR Am J Neuroradiol May;36(5):

SACE FOR ICA BIG ANEURYSM silent TOFSilent ① Ultra short TE Even with a carotid angiogram, recanalized flow between the coil mass and stent is difficult to demonstrate. Though TOF showed signal loss at the region, Silent showed the flow. Irie R, et al. AJNR Am J Neuroradiol May;36(5):

SACE FOR BA-TIP ANEURYSM ① Ultra short TE Silent TOF Though weak, depict precisely

SACE WITH DOUBLE STENTS (Y-GRAFT DEPLOYMENT) ① Ultra short TE Especially for an aneurysm located at a bifurcation of artery, Y-graft implantation is developed. Through the mesh of a deployed stent, another stent are deployed. Through the mesh of them, aneurysm is embolized. This technique widened the applicability for the aneurysm with wide neck, located at branch. Microcatheter for coil

① Ultra short TE Y-graft deployment was planned for basilar tip aneurysm SACE （ Y-GRAFT (STENT X2) ＋ COIL ）

TOF Silent ① Ultra short TE Silent showed an in-stent flow and residual flow inside the aneurysm. On the other side, TOF-MRA could not depict neither in-stent flow, nor residual flow..

Silent-MRATOF-MRA ① Ultra short TE In patient with coil embolization for an aneurysm bigger than 10mm, it is well known that is difficult to know the recanalization inside the aneurysm, even with an angiogram. Silent showed complete occlusion of an aneurysm without showing parent artery’s pseudostenosis depicted on TOF. POST COIL EMBOLIZATION FOR BIG ANEURYSM

SILENT MRA TOF MRA POST CLIPPING FOR BRAIN ANEURYSM ① Ultra short TE In patient with post clipping for braian aneurysm, Silent could depict a distal flow. It will be better follow-up tool to check up a de novo aneurysm.

FLOW DIVERTER Silent-MRATOF-MRA Flow diverter stent (PIPELINE®) was deployed for the rt. Internal carotid giant aneurysm. Three stents were deployed partially in piles. Even at the piled part, less signal loss was observed on Silent-MRA image. Remnant flow at the carotid cave is demonstrated on Silent-MRA only(  ).

FLOW DIVERTER + COIL Silent-MRATOF-MRA Flow diverter stent (PIPELINE®) was deployed for the rt. Internal carotid large aneurysm. In this case, coil embolization was added for protruded part of the aneurysm. Note that less signal loss was observed on Silent-MRA image at the deployed part of FD.

TOF-MRA Silent-MRA This susceptibility artifact is reduced by Ultra-short TE Flow depiction is enhanced by ASL ENHANCED FLOW DEPICTION IN STENT-DEPLOYED CASES Combinationo of UTE and ASL is the key in SACE cases

SILENT MRA ① Ultra short TE Reduced Susceptibility artifact Reduced Metallic artifact ② Arterial spin labeling Enabled to depict a very slow flow, regardless of its direction ③ Subtraction of T1-weighted images Characteristics of ⇒ Treatment for a brain aneurysm ・ coiling ・ stent assisted coil embolization ・ clipping ⇒ Moyamoya disease dural AVF, AVMs ⇒ subarachnoid hemorrhage dissecting aneurysm Next, go on to the

MOYAMOYA DISEASE SILENT MRA TOF MRA ② Arterial spin labeling In any direction Not only basal moyamoya vessel, leptomeningeal anastomosis is well demonstrated compared with TOF.

CLIPPING + BYPASS A case with post rt. ICA ligation for giant aneurysm. Rt STA-MCA anastomosis was performed. SILENT MRA TOF MRA ② Arterial spin labeling In any direction

silentTOF CLIPPING + BYPASS On Silent MRA, we could delineate a bypass route between a STA and a opercular branch of MCA. ② Arterial spin labeling In any direction

Reconstruction with Partial MIP will facilitate to understand the anastomoisis ② Arterial spin labeling In any direction

CAVERNOUS SINUS DURAL AVF 1 Female on her 40’s. Sudden exophthalmos from yesterday. Dilated supra orbital vein was confirmed on CT, came to MR for further examination. ② Arterial spin labeling In any direction

TOF-MRASilent-MRA cranial CAVERNOUS SINUS DURAL AVF 1 Both images could demonstrate a cranial direction of shunt flow from ascending pharyngeal artery(APA). Though not strong flow, Silent could depict a flow from the contralateral APA (thickened arrow). ② Arterial spin labeling In any direction

Shunt flow from both sides of APA was confirmed on angiogram, similar to the Silent scan ② Arterial spin labeling In any direction cranial

CAROTID-CAVERNOUS SINUS DURAL AVF CCdAVF during coil embolization for ICA aneurysm. ② Arterial spin labeling In any direction

TOF-MRA Silent-MRA Different from TOF, Silent could demonstrate a caudal flow clearly (yellow arrow). ② Arterial spin labeling In any direction

ARTERIOVENOUS MALFORMATION (LARGE) TOF-MRA Silent-MRA Silent could demonstrate each vessel clearly, especially deep part of AVM. For example, could you find a yellow arrow artery on TOF? ② Arterial spin labeling In any direction

ARTERIOVENOUS MALFORMATION (SMALL/SLOW) TOF-MRA Silent-MRA Male on her 40’s. An AVM located at lt. occipital lobe was removed 3 months ago. Because of its location (visual cortex), total removal was avoided on purpose. To confirm the remnant AVM, the patient came to the MR unit. Only Silent could depict the small vascular structure that continues to a cotton-like high signal. ② Arterial spin labeling In any direction

Similar to the angiogram, recurrent feeding artery and small nidus was demonstrated on Silent ② Arterial spin labeling In any direction

SILENT MRA ① Ultra short TE Reduced Susceptibility artifact Reduced Metallic artifact ② Arterial spin labeling Enabled to depict a very slow flow, regardless of its direction ③ Subtraction of T1-weighted images Characteristics of ⇒ Treatment for a brain aneurysm ・ coiling ・ stent assisted coil embolization ・ clipping ⇒ Moyamoya disease dural AVF, AVMs ⇒ subarachnoid hemorrhage dissecting aneurysm

SAH & VASOSPASM ③ Subtraction of T1-WI SILENT TOF Silent could remove a hyperintense hematoma at subarachnoid space.

Female on her 70’sSAH during multiple brain aneurysm coiling. Silent MRA SAH 3D-TOF

DISSECTING ANEURYSM OF PICA SILENT TOF We could see a mural hematoma demonstrated as crescent high signal on TOF. No communication between true and false lumen is evident on Silent. ③ Subtraction of T1-WI Mural hematoma was hyper intensity on TOF because of its T1 shortening effect. It was subtracted, in this case. However, if there was flow inside the false lumen, ASL effect would enhance the signal intensity on Silent.

SILENT TOF ③ Subtraction of T1-WI A case with lt. MCA thrombosed aneurysm. Inside of the aneurysm was hyperintense on the other MR contrasts. However, because it continued to a MCA bifurcation on TOF, his aneurysm has been believed to have a flow inside at the previous clinical physician. THROMBOSED MCA ANEURYSM

SILENT-MRA Very quiet scan ( + 3dB with environmental sound ) Based on combination of ASL, ultra short TE and a subtraction of T1WI Similar scan time with TOF-MRA (if extended FOV) Never affected by a saturation effect Easy to depict a slow blood flow Homogeneous depiction of a slow, whirlpool and turbulence flow Never affected by a flow direction ⇒ Whenever the flow exists, depicted precisely IN SUMMARY, Thank you