Ayako Ninomiya

Visualization of the lenticulostriate artery with flow-sensitive black-blood acquisition in comparison with time-of-flight MR angiography

To evaluate the capability of flow‐sensitive black blood (FSBB) acquisition to visualize the lenticulostriate artery (LSA) in comparison with time‐of‐flight (TOF) angiography.

Whole-heart coronary magnetic resonance angiography with parallel imaging: comparison of acceleration in one-dimension vs. two-dimensions.

PURPOSE To evaluate visualization of the whole-heart coronary arteries accelerated with parallel imaging (PI) applied in two-dimension (2D) in comparison with one-dimension (1D). MATERIALS AND METHODS Seventeen healthy subjects were studied with a 1.5-T scanner equipped with a whole body phased array coil system and 16-channel receivers. Using 16 coil elements, whole-heart coronary magnetic resonance angiography (CMRA) was acquired in two conditions of 1D-PI and 2D-PI. The former scan was accelerated in phase direction by factor of 2 and the latter in phase and slice directions by factors of 2.5 and 2, respectively. Visualized length of right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) was measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was also measured. The CMRA quality was assessed in segment-wise with a five-point scale. RESULTS The average scan time decreased to 5.3+/-2.2 min in 2D-PI from 11.6+/-3.5 min in 1D-PI, reducing the scan time to 45%. The visualized length, SNR, and CNR in average were smaller for images of 2D-PI compared with those of 1D-PI, however, statistically significant results were observed only in RCA (P<0.05). Score reduction of 2D-PI image quality was limited to 0.34 in average, and only two out of fifteen segments (#2, 6) showed significant score deterioration (P<0.05). CONCLUSIONS Compared with the relatively limited degree of image degradation, 2D-PI offered a large reduction of the acquisition time, which is of large benefit in clinical situations.

Differentiating between Central Nervous System Lymphoma and High-grade Glioma Using Dynamic Susceptibility Contrast and Dynamic Contrast-enhanced MR Imaging with Histogram Analysis

Purpose: We evaluated the diagnostic performance of histogram analysis of data from a combination of dynamic susceptibility contrast (DSC)-MRI and dynamic contrast-enhanced (DCE)-MRI for quantitative differentiation between central nervous system lymphoma (CNSL) and high-grade glioma (HGG), with the aim of identifying useful perfusion parameters as objective radiological markers for differentiating between them. Methods: Eight lesions with CNSLs and 15 with HGGs who underwent MRI examination, including DCE and DSC-MRI, were enrolled in our retrospective study. DSC-MRI provides a corrected cerebral blood volume (cCBV), and DCE-MRI provides a volume transfer coefficient (Ktrans) for transfer from plasma to the extravascular extracellular space. Ktrans and cCBV were measured from a round region-of-interest in the slice of maximum size on the contrast-enhanced lesion. The differences in t values between CNSL and HGG for determining the most appropriate percentile of Ktrans and cCBV were investigated. The differences in Ktrans, cCBV, and Ktrans/cCBV between CNSL and HGG were investigated using histogram analysis. Receiver operating characteristic (ROC) analysis of Ktrans, cCBV, and Ktrans/cCBV ratio was performed. Results: The 30th percentile (C30) in Ktrans and 80th percentile (C80) in cCBV were the most appropriate percentiles for distinguishing between CNSL and HGG from the differences in t values. CNSL showed significantly lower C80 cCBV, significantly higher C30 Ktrans, and significantly higher C30 Ktrans/C80 cCBV than those of HGG. In ROC analysis, C30 Ktrans/C80 cCBV had the best discriminative value for differentiating between CNSL and HGG as compared to C30 Ktrans or C80 cCBV. Conclusion: The combination of Ktrans by DCE-MRI and cCBV by DSC-MRI was found to reveal the characteristics of vascularity and permeability of a lesion more precisely than either Ktrans or cCBV alone. Histogram analysis of these vascular microenvironments enabled quantitative differentiation between CNSL and HGG.

Whole-heart coronary MR angiography under a single breath-hold: A comparative study with respiratory-gated acquisition using a multi-element phased-array coil

AIM To compare visualization using whole-heart coronary magnetic resonance angiography (CMRA) acquired during a single breath-hold (BH) with that using conventional respiratory-gated (RG) CMRA. MATERIALS AND METHODS The CMRAs of 14 healthy subjects under either BH or RG conditions were studied using a 1.5 T system equipped with a whole-body phased-array coil and 16-channel receivers. The BH examination was accelerated using parallel imaging (PI) by factors of 2.5 and 2 in the phase and section directions, respectively. For the RG examination, a PI factor of 2 was used only in the phase direction. The visualization quality of 15 coronary segments using each condition was evaluated with a five-point scale (0-4). Differences between two conditions were compared at segments with an average score greater than 2 in RG-CMRA. RESULTS The average examination time for BH and RG acquisition scans was 34 s and 11 min 31 s, respectively. Ten segments (segments 1-3, 5-9, 11, and 13) had average scores higher than 2 in RG-CMRA. Of these, BH-CMRA had significantly lower scores than RG-CMRA at six segments (segments 1, 5-8, and 11) after correction for multiple comparisons (p<0.005). However, in BH-CMRA, proximal segments (segments 1-2, 5-7, and 11) showed average scores over 2, indicating marginally acceptable image quality. CONCLUSION Compared with the relatively limited degree of image degradation with RG-CMRA, the present data suggest that BH-CMRA would be useful for screening and as an adjunct to RG-CMRA that is occasionally incomplete.

Whole-heart magnetic resonance coronary angiography with multiple breath-holds and automatic breathing-level tracking

Whole-heart (WH) magnetic resonance coronary angiography (MRCA) studies are usually performed during free breathing while monitoring the position of the diaphragm with real-time motion correction. However, this results in a long scan time and the patient’s breathing pattern may change, causing the study to be aborted. Alternatively, WH MRCA can be performed with multiple breath-holds (mBH). However, one problem in the mBH method is that patients cannot hold their breath at the same position every time, leading to image degradation. We have developed a new WH MRCA imaging method that employs both the mBH method and automatic breathing-level tracking to permit automatic tracking of the changes in breathing or breath-hold levels. Evaluation of its effects on WH MRCA image quality showed that this method can provide high-quality images within a shorter scan time. This proposed method is expected to be very useful in clinical WH MRCA studies.

Feasibility study of Global-to-Local Tandem Method for detecting the coronary stationary period in whole-heart magnetic resonance coronary angiography (WH MRCA)

Introduction WH MRCA studies are usually performed during the stationary period of coronary arteries, which is determined using cine display and therefore depends on the operators experience. Several automatic methods have been developed. One such method uses the global heart signal for analysis [1] and is suitable for detecting motion during all cardiac phases, but this method tends to suffer from noise. Another method employs a ROI for analysis [2] and is suitable for precise detection of the stationary period, but not for all cardiac phases. We have developed the Global-to-Local Tandem Method, in which the coronary stationary period is roughly analyzed by the global method and then precisely analyzed by the local method. We have also conducted clinical feasibility studies.

Feasibility study of motion pre-analysis method for whole-heart magnetic resonance coronary angiography (WH MRCA)

Introduction WH MRCA [1] examinations are usually performed during free breathing, and the Realtime Motion Correction (RMC) coefficient is important for obtaining good image quality. However, this coefficient differs in each patient, which may result in image degradation. We have developed the Motion Pre-Analysis Method to determine the appropriate RMC coefficient before WH MRCA and have conducted feasibility studies to investigate the appropriate method for using an abdominal band.

1127 Optimal scanning conditions for whole-heart coronary MR angiography in clinical practice

Introduction In whole-heart coronary MR angiography (WH-CMRA), positional changes due to respiratory motion are corrected using Real-Time Motion Correction (RMC) or are suppressed by instructing the patient to hold his or her breath. The present study was conducted to investigate the optimal scanning conditions for obtaining the required information within a specified time period in WH-CMRA with the objective of making WH-CMRA a useful imaging method in clinical practice.

2124 Whole-Heart Magnetic Resonance Coronary Angiography (WH MRCA) with visual feedback

Introduction Currently, WH MRCA studies are usually performed during free breathing while monitoring the position of the diaphragm. However, since the scan time is rather long, the patients breathing pattern may change during scanning, and scanning sometimes cannot be completed. In another method, WH MRCA is performed during multiple breath-holds. However, patients cannot hold their breath within a threshold each time, and it is also difficult to perform scans in a short time. These problems are attributable to the fact that patients cannot recognize their breathing level and therefore cannot adjust it.