Concurrent Demonstration of Cerebral Infarction and the Involved Pyramidal Tract by 3D-FLAIR Imaging Using a Variable Refocusing Flip Angle Kazuhiro Tsuchiya, Motoyuki Yamashita, Naoki Shimatani Misako Yorimitsu, Motonori Kokan, Takeo Suzuki, Shuichi Ichisaka Department of Radiology, Tokyo Teishin Hospital Tokyo, Japan

☑ The author has no conflict of interest to disclose with respect to this presentation.

Background and Purpose We have found that FLAIR imaging using a VISTA (Volume ISotropic TSE Acquisition) sequence can highlight some major nerve tracts by changing a refocusing flip angle (RFA) from that (60°) recommended by the vendor for conventional FLAIR contrast. We assessed the feasibility of the FLAIR VISTA sequence in demonstrating the pyramidal tract (PT) and an infarct that developed in its vicinity on one image.

VISTA （Volume ISotropic TSE Acquisition） Available for imaging of T1WI, T2WI, and FLAIR 3D non volume-selective　→　 echo space↓, blurring↓ Refocusing flip angle　→ 　pseudo steady state, long ETL Signal Gx Gy Gz RF 90° RF pulse 90+α/2 α Refocusing pulse Echo space ↓ 3D non volume selective α α

3D FLAIR VISTA images obtained with an RFA of 110° show the pyramidal tract as a hyperintense structure.

Contrast of the pyramidal tract changes according to the RFA. Normal volunteer (34F)

Comparison of diffusion tensor color map and tractography shows good correspondence.

SNR/CNR assessments at various RFAs in 5 volunteers show 110 ° as a favorable value. Recommended value by PHILIPS

Patients Fifteen patients (9 men, 6 women; aged 45 to 87 years, average age 65.8 years ) of acute/subacute infarction who underwent MR imaging including the FLAIR VISTA sequence (RFA=110°) between June, 2013 and March, 2014. Equipment : PHILIPS Achieva 1.5T (Release 2.6)

Methods 1.5-T imager (PHILIPS Achieva Release 2.6) Imaging parameters: TR/TE/TI, 6000/312/2000 ms; FOV, 250 mm; matrix, 208 x 208; slice thickness. 0.6 mm; SENSE factor, 2.8 (phase) x 2 (slice); flip angle, 90°; turbo factor, 140; and imaging time; 6 min 18 sec; scan plane, sagittal followed by reconstruction of coronal images Images were visually assessed by consensus reading of 2 experienced radiologists regarding the visualization of the pyramidal tract and the infarct using a three-point grading scale (3 = good, 2 = fair, 1 = poor). Equipment : PHILIPS Achieva 1.5T (Release 2.6)

Patient clinical data and summary of MR findings Symptoms MR findings PT visualization 62M transient weakness of LUE R temporal infarction 3 45M dysarthria, weakness of RUE L posterior limb of the internal capsule infarction 64F R hemiplegia, total aphasia L MCA area infarction 87F L basal ganglia/corona radiata infarction 65F weakness of RUE, limb ataxia R thalamus infarction DOC L frontotemporal infarction weakness of LUE, limb ataxia R thalamus/posterior limb of the internal capsule infarction 79M DOC, L hemiparesis 51M numbness of LUE, L hemiparesis R corona radiata/putamen, and frontal subcortical infarction 61M R hemiplegia L frontoparietal infarction 54F transient dysarthria, slight L facial palsy R posterior limb of the internal capsule infarction 56M dysarthria, headache R corona radiata infarction 70M dysarthria, slight R facial palsy 73M R hemiplegia, L concomitant deviation L PCA area infarction 68M weakness of RUE wamble ふらつき *R : right, L : left, LUE : left upper extremity , RUE : right upper extremity, DOC : disturbance of consciousness MCA: middle cerebral artery, PCA: posterior cerebral artery

Summary of results In all of the 15 cases, the PT was depicted on both sides. FLAIR VISTA images also showed the PT and the adjacent infarct that caused motor paresis of a variable degree. The average grading score was 3.

Case 1 (62M) transient weakness of left upper extremity after right cervical pain

Case 1 (62M) transient weakness of left upper extremity after right cervical pain

Case 1 (62M) transient weakness of left upper extremity after right cervical pain

Case 2 (45M) dysarthria and weakness of right upper extremity

Case 2 (45M) dysarthria and weakness of right upper extremity

Case 3 (65F) weakness of right upper extremity and limb ataxia

Case 3 (65F) weakness of right upper extremity and limb ataxia

Case 3 (65F) weakness of right upper extremity and limb ataxia

Discussion The PT was depicted on both sides in all cases probably reflecting histological characteristics of anisotropic fibers. Limitation of this method Not available in acute infarction that is not hyperintense on FLAIR images Advantages of this method　 This method may be available for lesions other than infarct (e.g., tumors and demyelinating diseases). It may present different contrast of infarct from conventional 3D FLAIR (RFA=60°). → possibly depict infarct in an earlier stage than conventional method? The PT was depicted on both sides in all cases. ＜Limitation＞ Not available in acute infarction that is not hyperintense on FLAIR images ＜Advantages＞　 Possibly available for other lesions (ex. tumor and demyelinating disease) May present different contrast of infarct from conventional 3D FLAIR (RFA=60 deg) → depict infarct in an earlier stage than conventional method?

Conclusion The 3D FLAIR VISTA technique using a RFA of 110° readily visualizes the relationship between the PT and cerebral infarct involving it. The FLAIR VISTA technique allows prompt visualization of the relationship between the PT and an adjacent infarct without complicated postprocessing. Probably reflecting histological characteristics of anisotropic fibers, the FLAIR VISTA technique can readily visualize the relationship between the PT and cerebral infarct involving it.