Hongli Fan^1,2, Pan Su², Doris Da May Lin³, Emily B. Goldberg³, Alexandra Walker³, Richard Leigh³, Argye E. Hillis³, and Hanzhang Lu^1,2,4
1Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ²The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ³Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁴F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States

        Tissue perfusion and structural imaging provides important information in the evaluation of ischemic stroke. MR-fingerprinting (MRF) arterial spin labeling (ASL) is a novel noninvasive method of ASL perfusion that allows simultaneous estimation of cerebral blood flow (CBF), bolus arrival time (BAT), and tissue T₁ map in a single scan of <4 minutes. Here we evaluated the utility of MRF-ASL in ischemic stroke patients in depicting hemodynamic and structural abnormalities, as well as predicting neurological deficits and disability.

Christian R. Meixner¹, Max Müller¹, Sebastian Schmitter^2,3, Jürgen Herrler⁴, Arnd Dörfler⁴, Michael Uder¹, and Armin M. Nagel^1,3
1Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander- Universität Erlangen-Nürnberg (FAU), Erlangen, Germany, ²Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Germany, ³Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, ⁴Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander- Universität Erlangen-Nürnberg (FAU), Erlangen, Germany

In this work, a whole-brain 4D-pcASL angiography sequence exploiting a radial density-adapted gradient echo readout with golden angle sampling was implemented and evaluated on a 7T system. Various parallel transmission (pTx) strategies were compared to the standard circularly polarized mode: To counteract low transmit efficiency in the labeling, B1+-shimming was used in combination with a full spiral-nonselective pTx-optimized readout train. Further, constant flip angle pTx-excitations in the readout were compared to pTx-pulses that were ramped from 3.5° to 6.5° using a linear scaling factor. This ramped readout strategy outperforms constant flip angles and reveals more of the vascular tree

Ferdinand Seith¹, Cecilia Zhang¹, Manuel Kolb¹, Brigitte Gückel¹, Rolf Pohmann², Petros Martirosian³, and Ahmed E. Othman^1,4
1Diagnostic and Interventional Radiology, University Hospital of Tübingen, Tübingen, Germany, ²High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, ³Section on Experimental Radiology, University Hospital of Tübingen, Tübingen, Germany, ⁴Neuroradiology, University Hospital of Mainz, Mainz, Germany

We present preliminary results of a prospective study of 96 patients examined with pCASL-MRI of the lung with suspected pulmonary embolism. pCASL-MRI of the lung was acquired in a 1.5T scanner by labeling the pulmonary trunk during systole. Coronal, sagittal and axial images were acquired using a fast bSSFP sequence. Additionally, a mulit-slice coronal bSSFP imaging the whole lung was performed. Two blinded readers evaluated MR-images to detect pulmonary embolism and noted the diagnostic confidence (5=very good). Compared to CT, sensitivity and specificity were 0.971 and 0.951. The median diagnostic confidence was 5 in both readers (kappa 0.739).

Meher R Juttukonda^1,2, Kimberly A Stephens¹, Yi-Fen Yen^1,2, Casey M Howard¹, Jonathan R Polimeni^1,2, Bruce R Rosen^1,2, and David H Salat^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Radiology, Harvard Medical School, Boston, MA, United States

Hypoperfusion is frequently considered a cause of age-related white matter lesions (WML). However, reductions in oxygen availability to brain tissue may also be caused by impaired oxygen extraction fraction (OEF). Here, we tested the hypothesis that venous hyperintense signal (VHS) in arterial spin labeling (ASL) MRI is indicative of impaired OEF in typically aging older adults. In participants aged 60–80 years (n=40), we measured VHS with ASL and maximum OEF (OEF_max) with dynamic susceptibility contrast MRI. Lower OEF_max was uniquely associated with higher WML volume in participants with VHS, indicating a potentially distinct cerebrovascular aging pattern in these individuals.

Simon Reiss¹, Kevin Waescher¹, Thomas Lottner¹, Ali Caglar Özen^1,2, Timo Heidt³, Constantin von zur Mühlen³, and Michael Bock^1
1Dept. of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, ²German Consortium for Translational Cancer Research Partner Site Freiburg, German Cancer Research Center (DKFZ), Heidelberg, Germany, ³Dept. of Cardiology and Angiology I, University Hospital Freiburg and Faculty of Medicine, University of Freiburg, Freiburg, Germany

Arterial spin labeling (ASL) provides a method for myocardial perfusion quantification without exogenous contrast agents. In MR-guided coronary catheterizations, perfusion measurements can provide a valuable tool to diagnose myocardial perfusion deficits and monitor the success of the intervention. In these interventions, catheters are usually visualized by active receive RF coils attached to the catheter. Using these active coils in transmit mode would enable intra-arterial spin labeling (iASL) in the coronary arteries with an increased labeling efficiency compared to conventional ASL. Here, we show the first in vivo results using iASL for myocardial perfusion measurements during coronary interventions in pigs.

Xingfeng Shao¹ and Danny JJ Wang^1
1Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States

We proposed a new sequence which improves the SNR of diffusion weighted ASL signals, and simultaneously estimates kw, water extraction ratio (Ew) and PSw using a multi-delay approach with PLDs ranging from 1500 to 2700 msec. Whole brain average CBF = 67.8±6.7 ml/100g/min, kw = 103.7±16.6 min-1, Ew = 94.8±1.3% and PSw = 202.2±41.3 ml/100g/min. These results match the recent literatures on kw and PSw studies. Ew ~95% suggests two long PLDs of 2400 and 2700 msec are sufficient to allow complete water extraction.

Nikolaos Mouchtouris¹, Mahdi Alizadeh², Adam Flanders², Chengyuan Wu¹, Feroze Mohamed², Reid Gooch¹, Stavropoula Tjoumakaris¹, and Pascal Jabbour^1
1Neurosurgery, THOMAS JEFFERSON UNIVERSITY HOSPITAL, Philadelphia, PA, United States, ²Radiology, THOMAS JEFFERSON UNIVERSITY HOSPITAL, Philadelphia, PA, United States

In this pilot study, we apply diffusion-prepared pseudo-continuous arterial spin labeling (DP-pCASL) non-contrast MRI sequence to patients with anterior circulation ischemic strokes and determine the cerebral blood flow (CBF) and blood-brain barrier (BBB) permeability in the affected vascular territories. When comparing their imaging findings to 24 control hemispheres (12 healthy volunteers), we demonstrated that both the CBF and BBB of the affected MCA territory was significantly lower than the MCA territories in healthy volunteers. Additionally, the BBB permeability in the affected territory appears to be elevated in acute ischemic strokes but decreases in subacute strokes.