Shuhei Shibukawa

Acceleration-selective arterial spin labeling for intracranial MR angiography with improved visualization of cortical arteries and suppression of cortical veins.

A new approach for intracranial MR angiography (MRA) is introduced, using acceleration‐selective arterial spin labeling (AccASL). The aim of this study was to investigate the arterial visualization and venous suppression using AccASL.

Balanced Turbo Field Echo with Extended k-space Sampling: A Fast Technique for the Thoracic Ductography

We evaluated the visibility of the thoracic duct by fast balanced turbo field echo with extended k-space sampling (bTFEe). The thoracic duct of 10 healthy volunteers was scanned by bTFEe using a 1.5-T magnetic resonance imaging (MRI), which was acquired in approximately 2 minutes. Three-dimensional (3D) turbo spin-echo (TSE) was obtained for comparison. The thoracic duct including draining location of the venous system was overall well visualized on bTFEe, compared to TSE.

Non-contrast enhanced 4D intracranial MR angiography based on pseudo-continuous arterial spin labeling with the keyhole and view-sharing technique

4D dynamic MR angiography (4D‐MRA) using pseudo‐continuous arterial spin labeling (pCASL), combined with Keyhole and View‐sharing (4D‐PACK) for scan acceleration, is introduced. Its validity for arterial inflow dynamics visualization was investigated through comparison with 4D‐pCASL and contrast inherent inflow enhanced multiphase angiography (CINEMA).

Optimized 4D time‐of‐flight MR angiography using saturation pulse

To assess arterial visibility on 4D time‐of‐flight (4D‐TOF) by temporal magnetization transfer contrast pulse (t‐MTC) and temporal tilted optimized nonsaturating excitation (t‐TONE). 3D‐TOF magnetic resonance angiography (MRA) is used for the noninvasive assessment of the intracranial arteries. However, it does not provide temporal information for diagnosing hemodynamics. To noninvasively obtain more detailed hemodynamics‐related information, we developed a novel time‐resolved MRA without the arterial spin labeling technique, termed 4D‐TOF MRA using saturation pulse.

Characteristic phase distribution in the white matter of infants on phase difference enhanced imaging

BACKGROUND AND PURPOSE The infantile brain is continuously undergoing development. Non-invasive methods to assess the neurological development of infants are important for the early detection of abnormalities. Some microstructures in the brain have been demonstrated via phase difference-enhanced imaging (PADRE), which may reflect myelin-related microstructures. We aimed to assess the white matter (WM) signal distribution in infants using PADRE and compared it with that using T1-weighted images (T1WI) and diffusion tensor imaging (DTI) on magnetic resonance imaging (MRI). MATERIALS AND METHOD This study included 18 infants (postmenstrual age at MRI, 37-40 weeks) without abnormal findings on MRI. Signal distribution using T1WI, a fractional anisotropy (FA) map and PADRE was assessed regarding the following intraparenchymal structures: the optic radiation (OR), internal capsule (IC), corpus callosum, corticospinal tract (CST), semiovale center and subcortical regions. RESULTS We found that the signal distribution was significantly different (P<0.001) with a relatively large signal change found at the IC and CST across the three imaging methods. Signal changes were also greater at the OR and rolandic subcortical WM on PADRE, whereas these were smaller on T1WI and FA. CONCLUSION PADRE demonstrated a characteristic phase shift distribution in infantile WM, which was different from that observed on T1WI and FA maps, and may demonstrate the developing myelin-related structures. PADRE can be a unique indicator of infantile brain development.

Magnetic resonance thoracic ductography assessment of serial changes in the thoracic duct after the intake of a fatty meal

The thoracic duct, a terminal lymph vessel, is thought to dilate after the intake of a fatty meal. However, this physiological change has not been well explored in vivo. Therefore, the present study aimed to assess serial changes in the thoracic duct after the intake of a fatty meal using magnetic resonance thoracic ductography (MRTD). Eight healthy volunteers were subjected to one MRTD scan before a fatty meal and eight serial MRTD scans every hour thereafter. The cross‐sectional areas of the thoracic duct were estimated using MRTD measurements of the diameters of the thoracic duct at the upper edge of the aortic arch, the tracheal bifurcation, the mid‐point between the tracheal bifurcation and the left part of the diaphragm and the left part of the diaphragm. The change‐rates in these areas were calculated before and after the fatty meal intake, and the maximal change‐rate and timing of its achievement were determined for each subject. The summed change‐rates in the four portions of the thoracic duct ranged from −40.1 to 81.3%, with maximal change‐rates for each subject ranging from 22.8 to 81.3% (mean, 50.4%). Although individual variations were observed, most subjects (88.9%) exhibited a maximal change‐rate at 4–6 h after meal intake, with subsequent decreases at 7–8 h. In conclusion, MRTD revealed a tendency toward thoracic duct enlargement at 4–6 h after the intake of a fatty meal, followed by contraction.

The Visibility of the Terminal Thoracic Duct Into the Venous System Using MR Thoracic Ductography with Balanced Turbo Field Echo Sequence

RATIONALE AND OBJECTIVES Magnetic resonance thoracic ductography (MRTD) with balanced turbo field echo (bTFE) can visualize both the thoracic duct and its surrounding vessels. This study aimed to investigate the visibility of the terminal thoracic duct into the venous system in the subclavian region using MRTD with bTFE. MATERIALS AND METHODS MRTD was performed with bTFE as a preoperative workup comprising respiratory gating on a 1.5-T magnetic resonance system for patients with esophageal cancer. The portion and the number of terminal thoracic ducts into the venous system and preterminal branching in the left subclavian region were assessed using MRTD in 132 patients. The confidence level of the visibility using MRTD was also evaluated. RESULTS The most frequent terminal portion of the thoracic duct was the jugulovenous angle (92 patients, 69.7%), followed by the subclavian vein (27 patients, 20.5%) and the internal jugular vein (8 patients, 6.1%). Four patients also exhibited double entry of the thoracic duct into the venous system. The preterminal branching was single in 96 patients (72.7%) and multiple in 36 patients (27.3%). The confidence level of the visibility of the thoracic duct using MRTD was absolutely certain in 112 patients (84.8%) and was somewhat certain in 20 patients (15.2%). CONCLUSIONS MRTD with bTFE is a robust imaging modality to visualize the terminal portion of the thoracic duct into the venous system in the subclavian region.

Time-spatial Labeling Inversion Pulse (Time-SLIP) with Pencil Beam Pulse: A Selective Labeling Technique for Observing Cerebrospinal Fluid Flow Dynamics

We assessed labeling region selectivity on time-spatial labeling inversion pulse (Time-SLIP) with pencil beam pulse (PB Time-SLIP) for the use of visualizing cerebrospinal fluid (CSF) flow dynamics. We compared the selectivity of labeling to the third and fourth ventricles between PB Time-SLIP and conventional Time-SLIP (cTime-SLIP) in eight volunteers and one patient using a 1.5T MRI. PB Time-SLIP provided more selective labeling in CSF than cTime-SLIP, particularly in complex anatomical regions.

High-resolution imaging of complex aortic plaques in ischemic stroke patients using 3.0 Tesla MRI with VISTA

Complex aortic plaques (CAP) in the thoracic aorta are considered a recurrent risk factor of ischemic stroke in association with instability [1]. Magnetic resonance (MR) plaque imaging of CAP in the thoracic aorta, using black blood imaging by the conventional double inversion recovery (DIR) method has not been challenging due to motion artifacts from cardiac pulsation. This study tried to evaluate the quality of CAP using MR plaque imaging with a new method. The present study was a prospective study and the participants were selected involving acute ischemic stroke patients admitted to Tokai University Hospital between October 2013 and September 2014. Written informed consent was obtained from all patients. This study was approved by the Tokai University Ethics Committee (13R-118). Ten acute ischemic stroke patients where aortic arch plaque was detected with transesophageal echocardiography (TEE) were recruited (age median, 76 years [interquartile range (IQR), 65–80 years], 5 were women [50%]). All recruited patients were classified as stroke of other determined etiology based on the diagnosis of clinical subtype made by an experienced neurologist according to the Trial of Org 10172 in the Acute Stroke Treatment classification [2]. Regarding vessel wall analysis of the aorta with plaque imaging, evaluation revealed CAP using MR imaging (MRI) and TEE. MRI was performed using 3.0 Tesla MRI (Achieva 3.0T; Philips Healthcare, Andover, MA, USA). All cases underwent T1 black blood imaging by a new sequence of volume isotropic TSE acquisition (VISTA) [3]. We measured the consecutive thoracic aorta on the coronal view by synchronizing with heartbeats of the maximal systolic phase to reduce flow artifacts. Upon imaging, the scan time/parameters were standardized across all patients. Aortic vessel wall were verified and results were compared with TEE findings. TEE was performed using ARTIDA (TOSIBA, Japan) with a 5 MHz, multiplane probe. Aortic plaques were evaluated from the ascending aorta to the aortic arch. Evaluation included plaques in the short axial view for maximal plaque thickness, low echoic lesion, mobility, and ulcerative lesion. An ulcerative lesion was defined as the presence of surface defects showing a depth of over 2.0 mm. Based on the MRI findings, patients were divided into the following two groups: positive or negative findings of high signal resolution along the vessel wall, following the previous reports (Fig. 1) [3, 4]. Evaluation included correlations with age, sex, atherosclerotic risk factors (hypertension, diabetes mellitus, and dyslipidemia), inflammatory marker (high sensitivity C-reactive protein [hsCRP]), and high the Calcification in the Aortic Arch, Age, Multiple Infarction (CAM) score (≥ 3) [5]. High signal resolution was detected along the thoracic aorta wall in 5 patients (positive group). Age, sex, and atherosclerotic risk factors were not significantly different between the positive group and negative group. Low echoic lesion (4 [80%] vs. 1 [20%], respectively, p = 0.06) and ulcerated/mobile lesion (2 [20%] vs. 0 [0%], respectively) of TEE were detected at a higher frequency in the positive group compared to the negative group, which is in agreement with the high signal resolution. The median plaque thickness was not significantly different between the positive and negative group (5 [4–6; IQR] vs. 4 [3–6], respectively). Hs-CRP was also significantly higher in the positive group than in