Improved Visualization of Intracranial Vessels by Gradient Moment Nulling in Hybrid of Opposite-contrast Magnetic Resonance Angiography (HOP MRA)

Abstract

Hybrid of opposite-contrast (HOP) magnetic resonance angiography (MRA) is a new method that combines the advantages of 3-dimensional (3D) time-of-‰ight (TOF) MRA and black-blood (BB) MRA without prolonging acquisition time. In phantom and clinical studies, we focused on image diŠerences when we applied gradient moment nulling (GMN) to 2 or 3 axes in theˆrst echo. We made an original phantom with a semicircular tube of 3-and 5-mm internal diameter, with ‰ow rate in the tube of 0, 20, 60, 80, or 120 cm/s. In original images of the phantom obtained with TOF MRA and ‰ow-sensitive BB MRA and inˆlter frequency-weighted subtraction (FWS) processed images acquired with HOP MRA, we measured the contrast-to-noise ratio (CNR) of both the inside and outside of the tubes. In FWS processed images with GMN applied to 2 axes, the CNR was high at various ‰ow rates in both straight and bending portions of the tubes in comparison with TOF images. In a clinical study in 15 patients, we evaluated vessel visualization in images obtained using conventional TOF MRA with magnetization transfer contrast (MTC) and HOP MRA. In clinical studies, visualization scores of HOP MRA were equivalent to those of conventional TOF MRA in the bilateral internal carotid arteries (ICA) and inferior in the basilar arteries. However, visualization of the peripheral portion of the middle cerebral artery (MCA) improved signiˆcantly in HOP MRA with GMN applied to 2 and 3 axes. Visualization of the main trunk of the ICA and MCA was superior in HOP MRA with GMN applied to 2 axes. HOP MRA with 2-axis GMN may be useful for excellent visualization of both major arteries and peripheral vessels in the head.

Safety of Gadopentetate Dimeglumine after 120 Million Administrations over 25 Years of Clinical Use

“…Advances in hardware and software that have enhanced the signal-tonoise ratio and improvements in contrast resolution with gadolinium-based contrast agents (GBCAs) 1 make contrast-enhanced MR imaging (CE-MRI) a comparable or better diagnostic tool than computed tomography and other conventional imaging methods. [2][3][4][5] Further advances in dynamic CE-MRI perfusion 6 and contrast-enhanced magnetic resonance angiography (MRA) 7 have improved the e‹ciency of clinical diagnoses, and highlight the importance of imaging techniques in diagnostic medicine.…”

MRI-Compatible Microcirculation System Using Ultrasonic Pumps for Microvascular Imaging on 3T MRI

“…Studies on magnetic resonance angiography (MRA) used blood circulation systems and manufactured vascular phantoms [6][7][8][9][10]. However, these vascular structural and flow studies were mainly performed using relatively large arterial vascular models [6,[11][12][13] (Table 1). Furthermore, the circulation pump used in the previous flow studies featured tubes that were >5 m long because the pump must be located outside the magnetic field due to the magnetic force [6].…”

“…Furthermore, such studies could not generate a continuous flow within the small vessel phantom, making the evaluation of the characteristics of normal microvascular blood flow challenging. [10] Circle of Willis 4.9 mm 3T Peristaltic (Yes) N-M Ooij (2012) [11] Anterior communicating artery 2.1 mm 3T Centrifugal (Yes) 10.46 cm/s Brindise (2019) [12] Basilar artery 5 mm 3T Gear (Yes) 3.09 mL/s Azuma (2010) [13] Internal carotid artery 5 mm 1.5T N-M 20 cm/s Wang (2020) [14] Small artery 0.…”