Comparison between 2D and 3D high-resolution black-blood techniques for carotid artery wall imaging in clinically significant atherosclerosis

PURPOSE: To compare two- (2D) and three-dimensional (3D) black-blood imaging methods for morphological measurements of the carotid artery wall and atherosclerotic plaque. MATERIALS AND METHODS: A total of 18 subjects with 50% to 79% carotid stenosis were scanned with 2D (2-mm slice thickness) and 3D (1-mm/0.5-mm actual/interpolated slice thickness) T1-weighted fast spin-echo (FSE) black-blood imaging sequences with double inversion-recovery (DIR) blood suppression. Morphological measurements (lumen area, wall area, vessel area, mean wall thickness, and maximal wall thickness), signal-to-noise ratio (SNR) in the wall and lumen, and wall-lumen contrast-to-noise ratio (CNR) were compared between 2D and 3D images. The effect of improved slice resolution in 3D imaging was evaluated for visualization of small plaque components. RESULTS: Lumen SNR (P = 0.16), wall SNR (P = 0.65), and CNR (P = 0.94) were comparable between 2D/3D. There was no difference in average lumen area (P = 0.16), average wall area (P = 0.99), average vessel area (P = 0.0.58), mean wall thickness (P = 0.09), and maximum wall thickness (P = 0.06) between 2D/3D. Distributions of small plaque components such as calcification were better characterized by the 3D acquisition. There was a higher sensitivity to motion artifacts with 3D imaging, resulting in three examinations with low image quality. CONCLUSION: 2D and 3D protocols provided comparable morphometric measurements of the carotid artery. The major advantage of 3D imaging is improved small plaque component visualization, while the 2D technique provides higher reliability for image quality.     

Submillimeter isotropic resolution carotid wall MRI with swallowing compensation: imaging results and semiautomated wall morphometry

PURPOSE: To assess a swallowing-compensated, three-dimensional (3D) diffusion-prepared segmented steady-state free precession (3D Nav-D-SSFP) technique for carotid wall MRI with 0.6-mm isotropic spatial resolution, and its utility for semiautomated carotid wall morphometry. MATERIALS AND METHODS: The carotid arteries of seven healthy volunteers (N=14) were imaged with 3D Nav-D-SSFP and black-blood T2-weighted (T2w) two-dimensional (2D) fast spin-echo (FSE). Carotid wall-lumen contrast-to-noise ratio (CNR) was measured with both sequences. Measurement of carotid wall area (WA) and lumen area (LA) made in a semiautomated manner off of the 3D Nav-D-SSFP images were compared to those made manually. RESULTS: Adjusted for voxel volume and number of slices, a near six-fold improvement in CNR per unit time was achieved with 3D Nav-D-SSFP relative to 2D T2w FSE (P<0.001). Manual and semiautomated measurements of carotid WA and LA on the 3D Nav-D-SSFP images were highly correlated (intraclass correlation coefficient (ICC)=0.961 and 0.996, respectively; P<0.001). CONCLUSION: 3D Nav-D-SSFP is a time-efficient, swallowing-compensated, black-blood technique that lends itself for semiautomated measurements of carotid WA and LA that are in good agreement with manual measurements.     

Multislice dark-blood carotid artery wall imaging: a 1.5 T and 3.0 T comparison

PURPOSE: To compare two multislice turbo spin-echo (TSE) carotid artery wall imaging techniques at 1.5 T and 3.0 T, and to investigate the feasibility of higher spatial resolution carotid artery wall imaging at 3.0 T. MATERIALS AND METHODS: Multislice proton density-weighted (PDW), T2-weighted (T2W), and T1-weighted (T1W) inflow/outflow saturation band (IOSB) and rapid extended coverage double inversion-recovery (REX-DIR) TSE carotid artery wall imaging was performed on six healthy volunteers at 1.5 T and 3.0 T using time-, coverage-, and spatial resolution-matched (0.47 x 0.47 x 3 mm3) imaging protocols. To investigate whether improved signal-to-noise ratio (SNR) at 3.0 T could allow for improved spatial resolution, higher spatial resolution imaging (0.31 x 0.31 x 3 mm3) was performed at 3.0 T. Carotid artery wall SNR, carotid lumen SNR, and wall-lumen contrast-to-noise ratio (CNR) were measured. RESULTS: Signal gain at 3.0 T relative to 1.5 T was observed for carotid artery wall SNR (223%) and wall-lumen CNR (255%) in all acquisitions (P < 0.025). IOSB and REX-DIR images were found to have different levels of SNR and CNR (P < 0.05) with IOSB values observed to be larger. Normalized to a common imaging time, the higher spatial resolution imaging at 3.0 T and the lower spatial resolution imaging at 1.5 T provided similar levels of wall-lumen CNR (P = NS). CONCLUSION: Multislice carotid wall imaging at 3.0 T with IOSB and REX-DIR benefits from improved SNR and CNR relative to 1.5 T, and allows for higher spatial resolution carotid artery wall imaging.     

Multicontrast black-blood MRI of carotid arteries: comparison between 1.5 and 3 tesla magnetic field strengths

PURPOSE: To compare black-blood multicontrast carotid imaging at 3T and 1.5T and assess compatibility between morphological measurements of carotid arteries at 1.5T and 3T. MATERIALS AND METHODS: Five healthy subjects and two atherosclerosis patients were scanned in 1.5T and 3T scanners with a similar protocol providing transverse T1-, T2-, and proton density (PD)-weighted black-blood images using a fast spin-echo sequence with single- (T1-weighted) or multislice (PD-/T2-weighted) double inversion recovery (DIR) preparation. Wall and lumen signal-to-noise ratio (SNR) and wall/lumen contrast-to-noise ratio (CNR) were compared in 44 artery cross-sections by paired t-test. Interscanner variability of the lumen area (LA), wall area (WA), and mean wall thickness (MWT) was assessed using Bland-Altman analysis. RESULTS: Wall SNR and lumen/wall CNR significantly increased (P < 0.0001) at 3T with a 1.5-fold gain for T1-weighted images and a 1.7/1.8-fold gain for PD-/T2-weighted images. Lumen SNR did not differ for single-slice DIR T1-weighted images (P = 0.2), but was larger at 3T for multislice DIR PD-/T2-weighted images (P = 0.01/0.03). The LA, WA, and MWT demonstrated good agreement with no significant bias (P 0.5), a coefficient of variation (CV) of < 10%, and intraclass correlation coefficient (ICC) of > 0.95. CONCLUSION: This study demonstrated significant improvement in SNR, CNR, and image quality for high- resolution black-blood imaging of carotid arteries at 3T. Morphologic measurements are compatible between 1.5T and 3T.     

Three-dimensional black-blood MR imaging of carotid arteries with segmented steady-state free precession: initial experience

This HIPAA-compliant study had institutional review board approval. Informed consent was obtained. The purpose was to prospectively evaluate a segmented three-dimensional (3D) double inversion recovery (DIR)-prepared steady-state free precession (SSFP) magnetic resonance (MR) imaging sequence for fast high-spatial-resolution black-blood carotid arterial wall imaging. Carotid wall-lumen contrast-to-noise ratio (CNR) obtained with this sequence was compared with those obtained with two-dimensional (2D) single- and multisection black-blood fast spin-echo (SE) sequences. MR imaging of both carotid artery bifurcations over 3 cm of transverse coverage was performed in eight volunteers (seven men, one woman; age range, 26-56 years) with no known history of carotid artery disease. Adjusted for section thickness and imaging time per section, higher effective mean CNR was achieved with segmented 3D DIR-prepared SSFP than with single-section 2D DIR-prepared fast SE or multisection 2D saturation-band fast SE (P < .05). Segmented 3D DIR-prepared SSFP enables black-blood carotid arterial wall MR imaging with contiguous thin-section coverage and greater imaging speed and effective CNR than conventional 2D fast SE techniques.     

Parallel and nonparallel simultaneous multislice black-blood double inversion recovery techniques for vessel wall imaging

PURPOSE: To reduce long examination times of black-blood vessel wall imaging by acquiring multiple slices simultaneously and by using parallel acquisition techniques. MATERIALS AND METHODS: DIR-rapid acquisition with relaxation enhancement (RARE) techniques imaging up to 10 simultaneous slices per acquisition with single and multiple 180 degrees -reinversion pulses were developed. A slab-selective reinversion multislice DIR-RARE sequence incorporating generalized autocalibrating partially parallel acquisitions (GRAPPA) imaging was implemented. Four-channel and eight-channel carotid coils were built to test these sequences. A total of 11 subjects were studied. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) efficiency factor (SEF, SNR/unit time/slice) were measured from aortic images of three healthy subjects to determine optimal MR parameters. The DIR-RARE-GRAPPA sequence was run on aortas and carotid arteries of the five remaining healthy subjects and three atherosclerotic patients with optimal parameters (acquisition times 12-21 seconds). RESULTS: SEFs of slab-selective protocols were significantly higher than those of slice-selective protocols, and SEFs of DIR-RARE-GRAPPA protocols were significantly higher than corresponding non-GRAPPA protocols (P < 0.05). CNR was not significantly different for all imaging protocols. The DIR-RARE-GRAPPA multislice sequence showed 8.35-fold time improvement vs. single-slice DIR-2RARE sequence. CONCLUSION: Future MRI atherosclerotic plaque studies can be performed in substantially shorter times using these methods.     

Volume-selective 3D turbo spin echo imaging for vascular wall imaging and distensibility measurement

PURPOSE: To use a volume-selective 3D turbo spin echo (TSE) technique to image the carotid artery wall and measure distensibility. MATERIALS AND METHODS: A high-resolution volume-selective 3D TSE sequence has been developed. Volume selection is accomplished by orthogonal gradients for the 90 degrees and 180 degrees excitations and allows a 3D volume of vessel wall to be imaged in a relatively short time. The technique has been developed to allow imaging at any defined phase of the cardiac cycle so that the vascular function and distensibility can be studied. RESULTS: Scan efficiency is increased by the reduced phase encode field of view (FOV) (k(y) steps) by the use of selective volume excitation. Significantly more slices (k(z) phase encode steps) for vessel coverage can be acquired with the same scan time as that of the conventional sequence while maintaining signal-to-noise ratio (SNR) levels. The practical value of the technique was demonstrated on 10 normal subjects with high-resolution vessel distensibility measurements of the carotid arteries. CONCLUSION: A volume-selective TSE method has been used for carotid artery wall imaging and measurement of distensibility in normal subjects. Larger coverage of the vessel, and therefore more information for clinical diagnostics, was achieved with the same overall scan time with an SNR comparable to that of 2D full FOV images.     

Improved suppression of plaque-mimicking artifacts in black-blood carotid atherosclerosis imaging using a multislice motion-sensitized driven-equilibrium (MSDE) turbo spin-echo (TSE) sequence

In this study, a turbo spin-echo (TSE) based motion-sensitized driven-equilibrium (MSDE) sequence was used as an alternative black-blood (BB) carotid MRI imaging scheme. The MSDE sequence was first optimized for more efficient residual blood signal suppression in the carotid bulb of healthy volunteers. Effective contrast-to-noise ratio (CNR_eff) and residual signal-to-noise ratio (SNR) in the lumen measured from MSDE images were then compared to those measured from inflow saturation (IS) and double inversion-recovery (DIR) images. Statistically significant higher CNR_eff and lower lumen SNR were obtained from MSDE images. To assess MSDE sequence in a clinical carotid protocol, 42 locations from six subjects with 50% to 79% carotid stenosis by duplex ultrasound were scanned with both MSDE and multislice DIR. The comparison showed that MSDE images present significantly higher CNR and lower lumen SNR compared to corresponding multislice DIR images. The vessel wall area and mean wall thickness measurements in MSDE images were slightly but significantly lower than those obtained with other blood suppression techniques. In conclusion, in vivo comparisons demonstrated that MSDE sequence can achieve better blood suppression and provide a more accurate depiction of the lumen boundaries by eliminating plaque mimicking artifacts in carotid artery (CA) imaging. Magn Reson Med 58:973–981, 2007. © 2007 Wiley-Liss, Inc.     

斜矢状位高分辨三维黑血磁共振成像在粥样硬化颈动脉支架术前评估的应用价值

目的探讨斜矢状位高分辨三维黑血磁共振成像(3D-BB-MRI)在粥样硬化颈动脉支架术前评估管腔狭窄及斑块形态方面的价值。资料与方法18例患者因至少一侧的症状性颈动脉粥样硬化病变进行颈动脉支架治疗。术前1周,对双侧颈总动脉远端、分叉处及颈内动脉近端进行斜矢状位高分辨二维黑血磁共振成像(2D-BB-MRI)及3D-BB-MRI扫描,同时对所有患者双侧颈动脉进行数字减影血管造影(DSA)检查。由2名放射科医师分别在2D-BB-MRI、3D-BB-MRI及DSA图像上评价颈动脉(颈总动脉远端、分叉处及颈内动脉近端)管腔最大狭窄程度(Max-stenosis)、斑块横向最大厚度(Max-TPT)、斑块纵向最大范围(Max-LPE),以DSA图像为标准分别分析2D-BB-MRI和3D-BB-MRI、DSA在评价Max-stenosis方面的差异,并对照分析2D-BB-MRI和3D-BB-MRI在显示Max-TPT、Max-LPE方面的差异。结果在评估Max-stenosis方面,2D-BB-MRI和3D-BB-MRI与DSA差异均无统计学意义(P=0.121及P=0.849),但3D-BB-MRI的显示结果更接近于DSA(79.80%±4.06%vs80.63%±4.67%,r=0.945,P=0.001),而2D-BB-MRI与DSA的相关性略低(77.75%±5.61%vs80.63%±4.67%,r=0.516,P=0.001)。对于Max-TPT的显示,2D-BB-MRI和3D-BB-MRI差异无统计学意义(P=0.450),而3D-BB-MRI所显示的Max-LPE明显大于2D-BB-MRI(16.74±5.54mmvs14.01±3.89mm,P=0.001)。结论作为一种无创的检查方法,3D-BB-MRI可以客观地显示粥样硬化颈动脉管腔最大狭窄程度、斑块厚度、累及范围,对颈动脉支架治疗手术具有很好的术前评估价值。     

Carotid MRA – what advantages do the turbo field-echo and 3D phase-contrast sequences offer?

Our purpose was to investigate some of the newer MR angiography (MRA) techniques for studying the carotid arteries. Forty-two arteries in seven asymptomatic, healthy volunteers were studied using five MRA sequences: two conventional time-of-flight sequences, 2D time-of-flight (2DTOF) and 3D time-of-flight (3DTOF); 2D and 3D magnetisation-prepared, segmented time-of-flight sequences (2DTFE and 3DTFE); and a 3D phase contrast angiography (3DPCA) sequence. A protocol that could be realistically employed in a routine clinical situation was chosen. 2DTOF had significantly (P < 0.05) better signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than 2DTFE. 3DTOF demonstrated better SNR than 3DTFE but 3DTFE demonstrated better CNR than 3DTOF. 3DPCA provided maximal anatomical coverage. No one sequence provided optimal anatomical coverage, accurate demonstration of the carotid bulb and maximal SNR and CNR. The combination of 3DPCA and a 3D inflow sequence was best. 2DTOF sequences are useful when only one brief sequence is practicably feasible. Received: 5 July 1996 Accepted: 25 July 1996     

Dynamic coronary MR angiography and first-pass perfusion with intracoronary administration of contrast agent

PURPOSE: To evaluate whether dynamic imaging of the coronary arteries can be performed with intracoronary infusion of low-dose gadolinium (Gd)-based contrast agent and assess the effect of long duration and multiple infusions on the image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). MATERIALS AND METHODS: Dynamic coronary magnetic resonance (MR) imaging (130 msec/image) and contrast agent first pass myocardial perfusion studies were performed with intracoronary infusions of low-dose Gd-based MR contrast agent on dogs (N = 4) using a fast multislice gradient recalled echo (GRE) sequence. RESULTS: Contrast-enhanced coronary arteries were clearly imaged during infusion periods as long as 2.3 minutes. The SNR and CNR of the contrast-enhanced coronary arteries remained essentially unchanged over multiple consecutive angiographic sessions. In addition, we demonstrated that first pass studies performed with intracoronary injection of MR contrast agent can be used as a means of assessing regional myocardial perfusion. CONCLUSION: These studies demonstrated that, using intracoronary infusion of Gd, coronary magnetic resonance angiography (MRA) can be performed with high temporal resolution, and multiple low-dose slow infusions of Gd-based MR contrast agent can be performed without compromise of the vessel SNR and CNR.     

3.0T MR单源与多源发射技术对肝脏成像质量影响的对比研究

目的 探讨3.0T MR单源与多源发射技术对肝脏成像质量的影响.方法 回顾性分析107例行3.0 T MR肝脏扫描受试者的图像,检查序列包括频谱选择性衰减反转恢复T2WI( SPAIRT2WI序列、DWI以及平衡式快速场回波(Balanced FFE)序列.每一序列均在单源和多源的激发模式下进行双重采集,采用Student＇st检验比较单多源图像的均匀性与对比度,采用Wilcoxon秩和检验比较单多源图像质量的评分.2名放射科医师独立进行阅片,采用Kappa检验比较读片者之间的诊断一致性.结果 采用单源和多源发射技术测量图像的均匀性分别为418.40±66.75和416.26±50.61,多源发射技术图像均匀性优于单源发射技术,差异有统计学意义(=2.524,P＜0.05).单源和多源发射技术测得的信噪比(SNR)分别为20.36±11.21和22.03±12.16,对比噪声比(CNR)分别为15.22±8.95和18.33±10.01,差异均有统计学意义(t值分别为- 2.630和- 4.238,P值均＜0.05).多源发射技术图像对比度优于单源发射技术图像.SPAIR T2WI序列单源和多源发射技术图像质量评分分别为(1.40±0.42)和(1.81±0.27)分,DWI序列分别为(1.08±0.46)和(1.63±0.36)分,Balanced FFE序列分别为(0.95±0.45)和(1.65±0.37)分,多源发射技术图像质量在上述3个序列中均优于单源发射技术图像(Z值分别为-5.894、-5.801和-6.985,P值均＜0.01).2名评判医师之间的诊断一致性好(Kappa值均＞0.8,P值均＜0.05).结论 相对于单源发射技术来说,多源发射技术能够消除电解质阴影,提供更好的图像均匀性、更高的图像对比度和更佳的图像质量,3.0T多源技术在腹部成像上具有很明显的优势.     

Water-saturated three-dimensional balanced steady-state free precession for fast abdominal fat quantification

PURPOSE: To compare the performance of a novel water-saturated b-SSFP sequence with that of a conventional T1-weighted turbo spin echo (T1W TSE) sequence for abdominal fat quantification. MATERIALS AND METHODS: A water-saturated, segmented, three-dimensional balanced steady-state free precession (b-SSFP) sequence and a traditional T1W TSE sequence were both employed on phantom and human studies. For phantom studies, a dual-layered phantom with known internal/external oil volumes was imaged using the two sequences. Images obtained by the two sequences were both processed using a computer-aided semiautomatic program for oil volume quantification. For human studies, six volunteers were scanned axially, centered at L2-L3 levels. Signal-to-noise ratio (SNR)(fat), contrast-to-noise ratio (CNR)(fat-muscle), CNR(fat-large bowel), and CNR(fat-small bowel) were calculated on hand-drawn regions of interest (ROIs), and averaged over all six slices for each subject. Statistical analyses were then performed to determine the SNR and CNR differences between images obtained by the two techniques. RESULTS: The phantom studies show that water-saturated b-SSFP offers a significantly closer estimation of true oil volumes compared with that of T1W TSE (P < 0.0001), as well as a more accurate internal/external volume ratio (P = 0.0001). In human studies, three-dimensional water-saturated b-SSFP images demonstrated higher CNR than that of T1W TSE (P < 0.0005), and very close SNR(fat) (P = 0.045). CONCLUSION: The proposed three-dimensional water-saturated b-SSFP sequence can generate high quality fat-only abdominal images with high CNR and SNR in shorter scan duration than the conventional T1W TSE approach. As images generated by this sequence suffer from no flow artifacts, and are less sensitive to bulk, respiratory, and bowel motion, three-dimensional water-saturated b-SSFP is a faster and more robust method for improving abdominal fat quantification using MRI.     

3D magnetization-prepared true-FISP: a new technique for imaging coronary arteries.

The purpose of this work was to develop an ECG-triggered, segmented 3D true-FISP (fast imaging with steady-state precession) technique to improve the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of breath-hold coronary artery imaging. The major task was to optimize an appropriate magnetization preparation scheme to permit saturation of the epicardial fat signal. An alpha/2 preparation pulse was used to speed up the approach to steady-state following a frequency-selective fat-saturation pulse in each heartbeat. The application of dummy cycles was found to reduce the oscillation of the magnetization during data acquisition. The fat saturation and magnetization preparation scheme was validated with simulations and phantom studies. Volunteer studies demonstrated substantially increased SNR (55%) and CNR (178%) for coronary arteries compared to FLASH (fast low-angle shot) with the same imaging time. In conclusion, true-FISP is a promising technique for coronary artery imaging.     

Coronary artery imaging using contrast-enhanced 3D segmented EPI

The purpose of the work was to evaluate the effectiveness of extracellular contrast media in improving MR coronary angiography using breath-hold segmented echo-planar imaging (SEPI). Two protocols were designed to optimize the inversion recovery-prepared contrast-enhanced SEPI method. In 15 healthy volunteers, significant improvements in signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), vessel sharpness, and length of visualization were observed post-contrast. The method with two targeted scans to cover the left and right arteries, respectively, following separate 20-mL contrast injections, was found to yield thinner slices and longer right coronary artery (RCA) visualization than a single scan following a 40-mL contrast injection without compromising SNR and CNR. In conclusion, extracellular contrast media substantially improves the delineation of coronary arteries with SEPI. J. Magn. Reson. Imaging 2001;13:676-681.     

化学位移成像和反转恢复快速自旋回波成像在肝脏的应用价值

目的 评价化学位移成像和反转恢复快速自旋回波对肝脏病变的检出能力。材料与方法 45例肝脏病变患者在进行常规SE T1WI和半傅立叶采集单次激发快速自旋回波（half-fFourier acquistition single-shot turbo spin-echo,HASTE)T2WI的同时,加用化学位移成像T1WI和反转恢复HASTE（IR－HASTE）T2WI。比较图像的信噪比（SNR）、肝脾对比噪声比（L－S CNR）、病灶对比噪声比（CNR）及病灶检出率。结果 化学位移成像T1WI的SNR、L－S CNR及SE T1WI均无显著性差异（P＞0．05）,但却能检出SET1WI无法显示的局灶性脂肪浸润和脂肪肝。IR－HASTE的SNR与HASTE相近（P＞0．05）,前者的L－S CNR及实性病灶的CNR均显著高于后者（P＜0．05）,特别是对较小的实质性病灶。结论 化学位移成像T1WI能提高肝脂肪成分的检出率,IR－HASTE的SNR与HASTE相近（P＞0．05）,前者的L－S CNR及实性病灶的CNR均显著高于后者（P＜0．05）,特别是对较小的实质性病灶。结论 化学位移成像T1WI能提高肝脂肪成分的检出率,IR－HASTE能提高肝实性病变的检出率,两种成像方法可作为常规肝脏检查方法的有力补充。     

Comparison of 2D and multislab 3D magnetic resonance techniques for measuring carotid wall volumes

Purpose

To compare a multislab three‐dimensional volume‐selective fast spin‐echo (FSE) magnetic resonance (MR) sequence with a routine two‐dimensional FSE sequence for quantification of carotid wall volume.

Materials and Methods

One hundred normal subjects (50 men, mean age 44.6 years) underwent carotid vessel wall MR using 2D and 3D techniques. Carotid artery total vessel volume, lumen volume, wall volume, and wall/outer wall (W/OW) ratio were measured over 20 contiguous slices. Two‐ (2D) and three‐dimensional (3D) results were compared.

Results

The mean difference between 2D and 3D datasets (as a percentage of the mean absolute value) was 1.7% for vessel volume, 4.9% for lumen volume, 4.7% for wall volume, and 5.8% for W/OW ratio. There was good correlation between 2D and 3D models for total vessel volume (R² = 0.93, P < 0.001), lumen area (R² = 0.92, P < 0.001), and wall volume (R² = 0.77, P < 0.001). The correlation for the W/OW ratio was weaker (R² = 0.30; P < 0.001). The signal‐to‐noise ratio (SNR) for the 3D technique was 2.1‐fold greater than for the 2D technique (P < 0.001). When using the 3D sequence, scan time was reduced by 63%.

Conclusion

Multislab volume selective 3D FSE carotid arterial wall imaging performs similarly to a conventional 2D technique, but with over twice the SNR and substantially reduced scan time. J. Magn. Reson. Imaging 2008;28:1476–1482. © 2008 Wiley‐Liss, Inc.     

磁共振B-TFE技术肾动脉成像与CE-MRA对照

目的：探讨磁共振三维平衡式快速场梯度回波（B-TFE）技术非对比剂血管成像在肾动脉成像中的临床应用价值。方法：选择17例临床怀疑有肾动脉狭窄的患者行B-TFE和CE-MRA检查;B-TFE组并行采集加速因子取值为1和2。B-TFE组在横轴面图像上测量双侧肾动脉在不同加速因子时的信号噪声比（SNR）、肾动脉与肾周脂肪的对比噪声比（CNR）,CE-MRA组在冠状面图像上分别测量肾动脉的SNR和CNR。所有原始数据经三维MIP重组后由两位放射科医师对肾动脉三维图像质量、肾动脉狭窄程度、肾动脉分支显示及肾静脉伪影等情况进行评分。测量数据和图像评分进行统计学处理。结果：B-TFE组加速因子为1时图像的SNR为118.0±25.1（左）和105.9±29.1（右）,CNR为103.7±33.5（左）和93.1±26.5（右）;B-TFE组加速因子为2时SNR为93.5±23.1（左）和81.5±31.7（右）,CNR为83.1±34.5（左）和69.8±28.8（右）。CE-MRA组肾动脉的SNR为103.8±31.5（左）和93.1±40.8（右）,CNR为88.7±30.1（左）和79.7±38.6（右）。组内和组间SNR及CNR差异均无统计学意义（P〉0.05）。B-TFE图像上肾动脉分支的显示情况好、肾静脉伪影较CE-MRA小,2组间肾动脉三维图像质量、狭窄程度的显示无明显差异。结论：3DB-TFE肾动脉成像技术具有较高的图像信噪比和对比噪声比,可以作为一种新的无创性磁共振血管成像技术应用于肾动脉成像。     

双层探测器光谱CT单能量成像联合个性化注射方案在颅脑CT血管成像中的应用研究

目的:探讨双层探测器光谱CT单能量成像联合个性化对比剂注射方案在颅脑CT血管成像（CTA）中的应用价值。方法:回顾性分析2020年8月至11月在华中科技大学同济医学院附属协和医院采用双层探测器光谱CT和个性化对比剂注射方案行颅脑CTA检查的76例患者的影像资料。对基于双层探测器光谱CT数据重建生成的120 kVp混合迭...     

Fast projective carotid MR angiography using arterial spin-labeled balanced SSFP

PURPOSE: To determine whether pulsed arterial spin-labeled (pulsed ASL) balanced steady-state free precession (bSSFP) imaging allows for rapid projective depiction of the carotid arteries without electrocardiographic (ECG) gating. MATERIALS AND METHODS: The carotid arteries of six volunteers were scanned at 1.5 T using an ASL two-dimensional bSSFP sequence. Three configurations were tested, with and without ECG gating: (a) full field-of-view (FOV) acquisition (scan time=48 s), (b) full-FOV acquisition with parallel acceleration of 2 (24 s), and sequence C (half-FOV acquisition (24 s). Vessel-to-background contrast-to-noise ratios (CNRs) and vessel lengths were compared between sequence configurations. Vessel caliber measurements were compared with those obtained from three-dimensional time-of-flight (TOF) angiography. RESULTS: The carotid arteries were seen over extensive lengths with ASL two-dimensional bSSFP. Projected vessel length and vessel-to-background CNR did not differ with ECG gating (P=NS). Nonaccelerated full-FOV and half-FOV scans provided larger apparent vessel-to-background CNR and slightly longer vessel lengths than the parallel-accelerated scans (P<0.01). Carotid diameter measurements were in agreement with those obtained from three-dimensional TOF (intraclass correlation coefficient=0.810; P<0.001). CONCLUSION: pulsed ASL bSSFP is a fast technique for projective carotid angiography that may not require ECG gating. Acquisition time may be decreased with reduced FOV or parallel imaging strategies.