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Publication for the Philips MRI Community Issue 44 – SUMMER 2011 Towards time-resolved non-CE MRA with CINEMA This article is part of FieldStrength issue 44 Summer 2011 34 Research Masanobu Nakamura Towards time-resolved non-CE MRA with CINEMA Non-contrast enhanced imaging has gained momentum over the past years. Newly developed techniques, such as B-TRANCE, have proven useful in the evaluation of several diseases1. One aspect that has been lacking though, was the ability to depict hemodynamic processes. Yaesu clinic, Chuo-ku, Tokyo, Japan is using an Achieva 3.0T scanner with special software to perform of non-CE MRA research in this field2,3. The team led by Masanobu Nakamura, radiotechnologist, is exploring time-resolved non-CE MRA in collaboration with Kumamoto University, Kumamoto Central hospital and Juntendo University Hospital. Time-resolved non-CE MRA with CINEMA CINEMA stands for Contrast inherent Inflow Enhanced Multi-phase Angiography. In order to depict inflow into the vascular tree, the team has developed an imaging sequence based on a multi-phase ASL approach using the FAIR preparation scheme. In this approach, two acquisitions are performed – one with and one without labeling of the inflowing blood. The two acquisitions are subsequently subtracted, resulting in an image where only the inflowing blood is depicted. Acquisition 1 global 180° α α α .... Acquisition 2 Acquisition 2 α Acquisition 1 .... Subtraction Image Basic principle of the ASL based CINEMA sequence. Two acquisitions are performed, one with and one without labeling of the blood. Subtraction of the two images results in an image of the inflowing blood. global 180° TI1 spoiler T TFE Phase N Phase 2 Phase 1 α Time-resolved information is obtained by performing a segmented readout, at multiple time points after the labeling pulse. The temporal resolution can be controlled by changing the duration of the readout segments. Inflow of blood into the region of interest can be followed as long as the label persists. selective 180° α spoiler T TFE α spoiler T TFE selective 180° Phase 1 α ∆TI TI2 TI3 TIN TR Time resolved information is obtained from the multi-phasic readout. 34 FieldStrength - Issue 44 - Summer 2011 spoiler T TFE TOF MRA TI=420ms TI=620ms TI=820ms TI=1020ms Rt-ICAPCA Lt-ICA TI=1220ms TOF (left) and CINEMA-FAIR (right) images acquired from a healthy volunteer. MIP images are shown from representative phases in one subject. Temporal resolution 200 ms, spatial resolution 1x1x1 mm3, scan time 6:49 min. Selective labeling for identification of supplying arteries The CINEMA technique may further be extended by the use of selective labeling slabs. In this way, blood flow from a particular artery can be selectively visualized. Upper left: TOF image used for planning of the labeling slabs. Upper right: Schematic depiction of the labeling slabs. Lower row: Arterial structures supplied by the right internal carotid artery (Rt-ICA), posterior communicating artery (PCA), and left internal carotid artery (Lt-ICA). Clinical applications Information on the hemodynamics of blood flow is crucial in several cerebrovascular diseases, such as arterio-venous malformations (AVM’s) and Moyamoya disease. Therefore, CINEMA might potentially play a role in the diagnosis of these diseases. TOF MRA TI=230ms TI=460ms TI=690ms TI=920msTI=1150ms TI=1380ms References 1 Wyttenbach et al., Radiology (2007)245;186-195 2. Nakamura et al., Proc. ISMRM (2011), 3345 3. Nakamura et al., Proc. ISMRM (2011), 4036 Moyamoya disease CINEMA TOF (left) and CINEMA-FAIR (right) images in a patient with Moyamoya disease. The characteristic ‘puff-of-smoke-like’ arterial structures are well depicted. FieldStrength 35