Masami Yoneyama

Comparison between two types of improved motion-sensitized driven-equilibrium (iMSDE) for intracranial black-blood imaging at 3.0 tesla.

To investigate the image quality impact of a new implementation of the improved motion‐sensitized driven‐equilibrium (iMSDE) pulse scheme in the human brain at 3.0 Tesla.

Vessel-selective, non-contrast enhanced, time-resolved MR angiography with vessel-selective arterial spin labeling technique (CINEMA–SELECT) in intracranial arteries

We demonstrate the feasibility of the vessel-selective, non-contrast, time-resolved magnetic resonance angiography (MRA) technique, “contrast inherent inflow enhanced multi-phase angiography combining vessel-selective arterial spin labeling technique (CINEMA–SELECT)”. This sequence consists of two major techniques: pulsed star labeling of arterial regions (PULSAR) and Look–Locker sampling. We hypothesize that this technique allows selective labeling of single intracranial arteries, consisting of high-resolution four-dimensional data with a wide coverage of the brain. In this study, a new vessel-selective, time-resolved angiographic technique is demonstrated that can produce individual angiograms non-invasively by labeling the principal arterial vessels proximal to the circle of Willis. Clear vessel delineation is achieved, and the separation of the three vessels is evident in healthy volunteers. This technique could play an important role in the assessment of the structure and hemodynamics of intracranial arteries without the use of contrast agents.

Three-dimensional T2-weighted imaging for liver MRI: Clinical values of tissue-specific variable refocusing flip-angle turbo spin echo imaging

To assess the clinical utility of tissue‐specific variable refocusing flip‐angle (VRFA) turbo‐spin echo imaging for three‐dimensional T2‐weighted imaging (3D‐T2WI) of the liver.

Amide proton transfer imaging of brain tumors using a self‐corrected 3D fast spin‐echo dixon method: Comparison With separate B0 correction

To assess the quantitative performance of three‐dimensional (3D) fast spin‐echo (FSE) Dixon amide proton transfer (APT) imaging of brain tumors compared with B0 correction with separate mapping methods.

Amide Proton Transfer Imaging of Diffuse Gliomas: Effect of Saturation Pulse Length in Parallel Transmission-Based Technique

In this study, we evaluated the dependence of saturation pulse length on APT imaging of diffuse gliomas using a parallel transmission-based technique. Twenty-two patients with diffuse gliomas (9 low-grade gliomas, LGGs, and 13 high-grade gliomas, HGGs) were included in the study. APT imaging was conducted at 3T with a 2-channel parallel transmission scheme using three different saturation pulse lengths (0.5 s, 1.0 s, 2.0 s). The 2D fast spin-echo sequence was used for imaging. Z-spectrum was obtained at 25 frequency offsets from -6 to +6 ppm (step 0.5 ppm). A point-by-point B0 correction was performed with a B0 map. Magnetization transfer ratio (MTRasym) and ΔMTRasym (contrast between tumor and normal white matter) at 3.5 ppm were compared among different saturation lengths. A significant increase in MTRasym (3.5 ppm) of HGG was found when the length of saturation pulse became longer (3.09 ± 0.54% at 0.5 s, 3.83 ± 0.67% at 1 s, 4.12 ± 0.97% at 2 s), but MTRasym (3.5 ppm) was not different among the saturation lengths in LGG. ΔMTRasym (3.5 ppm) increased with the length of saturation pulse in both LGG (0.48 ± 0.56% at 0.5 s, 1.28 ± 0.56% at 1 s, 1.88 ± 0.56% at 2 s and HGG (1.72 ± 0.54% at 0.5 s, 2.90 ± 0.49% at 1 s, 3.83 ± 0.88% at 2 s). In both LGG and HGG, APT-weighted contrast was enhanced with the use of longer saturation pulses.

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.

Lumbar plexus in patients with chronic inflammatory demyelinating polyneuropathy: Evaluation with 3D nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement imaging (3D SHINKEI)

PURPOSE To evaluate whether 3D SHINKEI in the lumbar plexus could identify patients with chronic inflammatory demyelinating polyneuropathy (CIDP). MATERIALS AND METHODS Twenty-one patients with CIDP and 15 non-CIDP patients were studied in this retrospective study. The SNR, contrast-to-noise ratio (CNR), contrast ratio (CR) and the size of the lumbar ganglions and roots were measured. Statistical analyses were performed with Mann-Whitney U test and receiver operating characteristics (ROC) analysis. RESULTS The SNRs of the ganglions and roots were larger in patients with CIDP (8.30±4.87 and 8.24±4.92) than in non-CIDP patients (4.95±2.05 and 5.08±1.97, P<0.0001, respectively). The CNRs of the ganglions and roots were larger in patients with CIDP (40.79±43.19 and 37.16±48.31) than in non-CIDP patients (25.90±10.41 and 18.37±32.83, P<0.0001, respectively). The CRs of the ganglions and roots were larger in patients with CIDP (0.74±0.13 and 0.66±0.17) than in non-CIDP patients (0.72±0.12 and 0.50±0.17, P=0.004 and P<0.0001, respectively). The sizes of the ganglions and the roots were larger in patients with CIDP (6.62±1.81mm and 5.76±3.24mm) than in non-CIDP patients (5.23±1.17mm and 4.24±1.11mm, P<0.0001, respectively). ROC analysis showed the best diagnostic performance with the CNR of the roots. CONCLUSION Patients with CIDP could be distinguished from controls on 3D SHINKEI.

3D MR Sequence Capable of Simultaneous Image Acquisitions with and without Blood Vessel Suppression: Utility in Diagnosing Brain Metastases

AbstractObjectiveVolume isotropic simultaneous interleaved bright- and black-blood examination (VISIBLE) is a recently developed 3D MR sequence that provides simultaneous acquisitions of images with blood vessel suppression (Black) and images without it (Bright). Our purpose was to evaluate the usefulness of VISIBLE in detecting brain metastases.MethodsThis prospective study included patients with suspected brain metastasis imaged with both VISIBLE and MPRAGE. From a data set, we compared the number of visualized blood vessels and the lesion-to-normal contrast-to-noise ratio (CNR) in 60 patients. We also performed an observer test to compare their diagnostic performance with VISIBLE, MPRAGE and only Black in 34 patients. Diagnostic performance was evaluated using a figure of merit (FOM), sensitivity, false-positive results per case (FPs/case) and reading time.ResultsThe number of vessels was significantly fewer in Black compared to MPRAGE and Bright (P < 0.0001). CNR was significantly higher with both Black and Bright than with MPRAGE (P < 0.005). In the observer test, significantly higher sensitivity (P < 0.0001) and FOM (P < 0.0001), significantly shorter reading time (P = 0.0001) and similar FPs/case were achieved with VISIBLE compared to MPRAGE. Compared to only Black, VISIBLE resulted in comparable sensitivity, but significantly fewer FPs/case (P = 0.0008).ConclusionVISIBLE can improve radiologists’ diagnostic performance for brain metastasis.Key Points• VISIBLE can achieve higher sensitivity and shorter reading time than MPRAGE. • VISIBLE can achieve lower false-positive rates than blood vessel suppressed images. • Compared to MPRAGE, VISIBLE can improve diagnostic performance for brain metastasis.

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).

Reevaluation of T2-weighted fast field echo (T2FFE): application to rapid volumetric black-blood imaging.

T2-fast field echo (T2FFE) sequence is a rapid T2-weighted steady state free precession sequence, but has not become a widely utilized MR-imaging strategy because of its low signal-to-noise ratio and high sensitivity to motion. These effects have seriously limited the clinical use of T2FFE and therefore T2FFE has not been used for routine clinical studies. Nevertheless, in this study, we have investigated the possibility of clinical application by re-optimization of the T2FFE on the current MRI systems. Our purpose in this study was to explore the sensitivity of T2FFE to flow spins using a flow phantom and a contrast optimization/comparison with 2D turbo spin-echo (TSE) T2-weighted images, and to evaluate its feasibility in volunteers and patients. This study demonstrated that the T2FFE sequence achieves rapid 3D T2-weighted black-blood imaging while minimizing the impact of motion using a low flip angle under the shortest repetition time and the shortest echo time conditions. Furthermore, 3D T2FFE with use of an optimal flip angle (30°–40°) can provide contrast equivalent to that of 2D TSE T2-weighted images. This proposed T2FFE sequence might be promising for numerous clinical applications.