Reliability of Three Dimentional Pseudo-continuous Arterial Spin Labeling:A Volumetric Cerebral Perfusion Imaging with Different Post-labeling Time and Functional State in Health Adults

To evaluate the reliability of three dimensional spiral fast spin echo pseudo-continuous arterial spin labeling(3D pc-ASL)in measuring cerebral blood flow(CBF)with different post-labeling delay time(PLD)in the resting state and the right finger taping state.Methods 3D pc-ASL and three dimensional T1-weighted fast spoiled gradient recalled echo(3D T1-FSPGR)sequence were applied to eight healthy subjects twice at the same time each day for one week interval.ASL data acquisition was performed with post-labeling delay time(PLD)1.5 seconds and 2.0 seconds in the resting state and the right finger taping state respectively.CBF mapping was calculated and CBF value of both the gray matter(GM)and white matter(WM)was automatically extracted.The reliability was evaluated using the intraclass correlation coefficient(ICC)and Bland and Altman plot.Results ICC of the GM(0.84)and WM(0.92)was lower at PLD 1.5 seconds than that(GM,0.88;WM,0.94)at PLD 2.0 seconds in the resting state,and ICC of GM(0.88)was higher in the right finger taping state than that in the resting state at PLD 1.5 seconds.ICC of the GM and WM was 0.71 and 0.78 for PLD 1.5 seconds and PLD 2.0 seconds in the resting state at the first scan,and ICC of the GM and WM was 0.83 and 0.79 at the second scan,respectively.Conclusion This work demonstrated that 3D pc-ASL might be a reliable imaging technique to measure CBF over the whole brain at different PLD in the resting state or controlled state.

Arterial spin labeling in neuroimaging

Arterial spin labeling(ASL) is a magnetic resonance imaging technique for measuring tissue perfusion using a freely diffusible intrinsic tracer.As compared with other perfusion techniques,ASL offers several advantages and is now available for routine clinical practice in many institutions.Its noninvasive nature and ability to quantitatively measure tissue perfusion make ASL ideal for research and clinical studies.Recent technical advances have increased its sensitivity and also extended its potential applications.This review focuses on some basic knowledge of ASL perfusion,emerging techniques and clinical applications in neuroimaging.

Three-dimensional arterial spin labeling and diffusion kurtosis imaging in evaluating perfusion and infarct area size in acute cerebral ischemia

BACKGROUND Early thrombolytic therapy is crucial to treat acute cerebral infarction,especially since the onset of thrombolytic therapy takes 1-6 h.Therefore,early diagnosis and evaluation of cerebral infarction is important.AIM To investigate the diagnostic value of magnetic resonance multi-delay threedimensional arterial spin labeling(3DASL)and diffusion kurtosis imaging(DKI)in evaluating the perfusion and infarct area size in patients with acute cerebral ischemia.METHODS Eighty-four patients who experienced acute cerebral ischemia from March 2019 to February 2021 were included.All patients in the acute stage underwent magnetic resonance-based examination,and the data were processed by the system’s own software.The apparent diffusion coefficient(ADC),average diffusion coefficient(MD),axial diffusion(AD),radial diffusion(RD),average kurtosis(MK),radial kurtosis(fairly RK),axial kurtosis(AK),and perfusion parameters post-labeling delays(PLD)in the focal area and its corresponding area were compared.The correlation between the lesion area of cerebral infarction under MK and MD and T2-weighted imaging(T2WI)was analyzed.RESULTS The DKI parameters of focal and control areas in the study subjects were compared.The ADC,MD,AD,and RD values in the lesion area were significantly lower than those in the control area.The MK,RK,and AK values in the lesion area were significantly higher than those in the control area.The MK/MD value in the infarct lesions was used to determine the matching situation.MK/MD<5 mm was considered matching and MK/MD≥5 mm was considered mismatching.PLD1.5s and PLD2.5s perfusion parameters in the central,peripheral,and control areas of the infarct lesions in MK/MD-matched and-unmatched patients were not significantly different.PLD1.5s and PLD2.5s perfusion parameter values in the central area of the infarct lesions in MK/MD-matched and-unmatched patients were significantly lower than those in peripheral and control areas.The MK and MD maps showed a lesion area of 20.08±5.74 cm^(2) and 22.09±5.58 cm^(2),respectively.T2WI showed a lesion area of 19.76±5.02 cm^(2).There were no significant differences in the cerebral infarction lesion areas measured using the three methods.MK,MD,and T2WI showed a good correlation.CONCLUSION DKI parameters showed significant difference between the focal and control areas in patients with acute ischemic cerebral infarction.3DASL can effectively determine the changes in perfusion levels in the lesion area.There was a high correlation between the area of the infarct lesions diagnosed by DKI and T2WI.

Blood oxygen level–dependent functional magnetic resonance imaging can evaluate the efficiency of transcatheter arterial chemoembolization in hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is among the most common malignant tumors worldwide, and transcatheter arterial chemoembolization(TACE) technology has become the first-line treatment for advanced HCC. Another important, recently developed technique is blood oxygen level–dependent functional magnetic resonance imaging(BOLD-fMRI), which utilizes hemoglobin as an endogenous contrast agent and measures deoxygenated hemoglobin content by sampling the oxygen content of tissues, thus reflecting the hemodynamics and pathophysiologic changes in body organs. Currently this technology is being used in patients with liver tumors;that is, it serves as an important tool in follow-up after TACE. The present paper summarizes these developments.

Coronary arterial bypass graft patency evaluated by multi-detector computed tomography and magnetic resonance imaging

The progression of atherosclerosis of the coronary artery does not stop after coronary arterial bypass grafting (CABG) surgery.……

Irregular surface of carotid atherosclerotic plaque is associated with ischemic stroke: a magnetic resonance imaging study

Objective To determine the association between the irregularity of carotid plaque surface using multidimensional magnetic resonance imaging(MRI) of ipsilateral acute cerebral infarction(ACI) cases. Methods Patients with recent cerebrovascular symptoms(stroke or transient ischemic attack < 2 weeks) and atherosclerotic plaque in at least one carotid artery were diagnosed by B-mode ultrasound imaging(intima-media thickness ≥ 1.5 mm) and recruited for the present study. Irregular surface was defined when plaque surface was uneven with high and low fluctuation or plaque with surface ulceration. The irregularity of carotid plaque surface was determined on axial or oblique images alone(single-dimension) and on both axial images and oblique images(multidimensions), separately. Univariate and multivariate logistic regression analyses were performed to calculate the odds ratio(OR) and the corresponding 95% CI of the irregular plaque surface in discriminating the presence of ipsilateral ACI. Results A total of 217 included subjects(mean age: 60.7 ± 10.2 years, 149 men) were recruited and 89(41.0%), 88(40.6%) and 118(54.4%) of them exhibited irregular plaque surface on axial, oblique and multidimensional MR images, respectively. The OR of irregularity of the plaque surface was determined by multidimensional MRI to be 5.88(95% CI: 3.16–10.96, P < 0.001) in discriminating the presence of ipsilateral ACI. Following adjustment for clinical confounding factors, this association remained statistically significant(OR = 5.65, 95% CI: 2.53–12.60, P < 0.001). The analysis included further adjustment for the presence of lipid-rich necrotic core, intraplaque hemorrhage and stenosis and the results included that this association also remained statistically significant(OR = 6.08, 95% CI: 2.52–14.68, P < 0.001). Conclusions The irregular plaque surface was determined by multidimensional MRI as an independent indicator for ipsilateral acute cerebral infarction.

In vivo tracking of human adipose-derived stem cells labeled with ferumoxytol in rats with middle cerebral artery occlusion by magnetic resonance imaging

Ferumoxytol, an iron replacement product, is a new type of superparamagnetic iron oxide ap- proved by the US Food and Drug Administration. Herein, we assessed the feasibility of tracking transplanted human adipose-derived stem cells labeled with ferumoxytol in middle cerebral artery occlusion-injured rats by 3.0 T MRI in vivo. 1 × 104 human adipose-derived stem cells labeled with ferumoxytol-heparin-protamine were transplanted into the brains of rats with middle cerebral artery occlusion. Neurologic impairment was scored at 1, 7, 14, and 28 days after transplantation. T2-weighted imaging and enhanced susceptibility-weighted angiography were used to observe transplanted cells. Results of imaging tests were compared with results of Prussian blue staining. The modified neurologic impairment scores were significantly lower in rats transplanted with cells at all time points except I day post-transplantation compared with rats without transplantation. Regions with hypointense signals on T2-weighted and enhanced susceptibility-weighted angiography images corresponded with areas stained by Prussian blue, suggesting the presence of superparamagnetic iron oxide particles within the engrafted cells. Enhanced susceptibility-weighted angiography image exhibited better sensitivity and contrast in tracing ferumoxytol-heparin-protamine-labeled human adipose-derived stem ceils compared with T2-weighted imaging in routine MRI.

Current and future applications of magnetic resonance imaging and spectroscopy of the brain in hepatic encepha-lopathy

肝的脑病(他) 普通 neuro 精神病学的畸形，它从肝细胞失败或 portosystemic 与肝疾病和结果复杂化病人的功课正在推延。表明他是广泛地可变的并且从温和无临床症状的骚乱包含一个系列到深昏迷。研究兴趣集中于传播导出勇气的毒素的角色，特别地氨，胀大的大脑的开发和在导致全球 CNS 消沉和混乱功能的服的 neurotransmitter 系统的变化。直到最近，服的功能的直接调查有在人是困难的。然而，当磁性的回声光谱学( 1H 太太)检测的质子在大脑生物化学变化时，新磁性的回声成像( MRI )技术在大脑体积( coregistered MRI )和损害大脑功能( fMRI )提供对变化的评价的一个非侵略的工具，包括服的 osmolytes 的直接测量，例如 myoinositol ，充斥管理对细胞的动态平衡内在的过程的使挫折和夫酸安，包括细胞内部的水的累积。这些细胞内部的 osmolytes 的集中与 hyperammonaemia 改变。有 neuropsychiatric 缺陷并且自从先生系列的严厉的检测太太的代谢物畸形相互关联向正常术后疗法回来，技术可能具有在客观耐心的监视并且在估计各种各样的治疗政体的有效性的使用。

Three-dimensional-arterial spin labeling perfusion correlation with diabetes-associated cognitive dysfunction and vascular endothelial growth factor in type 2 diabetes mellitus rat

BACKGROUND Type 2 diabetes mellitus(T2DM) has been strongly associated with an increased risk of developing cognitive dysfunction and dementia.The mechanisms of diabetes-associated cognitive dysfunction(DACD) have not been fully elucidated to date.Some studies proved lower cerebral blood flow(CBF) in the hippocampus was associated with poor executive function and memory in T2DM.Increasing evidence showed that diabetes leads to abnormal vascular endothelial growth factor(VEGF) expression and CBF changes in humans and animal models.In this study,we hypothesized that DACD was correlated with CBF alteration as measured by three-dimensional(3D) arterial spin labeling(3D-ASL) and VEGF expression in the hippocampus.AIM To assess the correlation between CBF(measured by 3D-ASL and VEGF expression) and DACD in a rat model of T2DM.METHODS Forty Sprague-Dawley male rats were divided into control and T2DM groups.The T2DM group was established by feeding rats a high-fat diet and glucose to induce impaired glucose tolerance and then injecting them with streptozotocin to induce T2DM.Cognitive function was assessed using the Morris water maze experiment.The CBF changes were measured by 3D-ASL magnetic resonance imaging.VEGF expression was determined using immunofluorescence.RESULTS The escape latency time significantly reduced 15 wk after streptozotocin injection in the T2DM group.The total distance traveled was longer in the T2DM group;also,the platform was crossed fewer times.The percentage of distance in the target zone significantly decreased.CBF decreased in the bilateral hippocampus in the T2DM group.No difference was found between the right CBF value and the left CBF value in the T2DM group.The VEGF expression level in the hippocampus was lower in the T2DM group and correlated with the CBF value.The escape latency negatively correlated with the CBF value.The number of rats crossing the platform positively correlated with the CBF value.CONCLUSION Low CBF in the hippocampus and decreased VEGF expression might be crucial in DACD.CBF measured by 3D-ASL might serve as a noninvasive imaging biomarker for cognitive impairment associated with T2DM.

IN VIVO ~1 H MAGNETIC RESONANCE SPECTROSCOPY IN EVALUATION OF HEPATOCELLULAR CARCINOMA AND ITS EARLY RESPONSE TO TRANSCATHETER ARTERIAL CHEMOEMBOLIZATION

客观：调查值在 vivo 质子在对 hepatocellular 癌(HCC ) 和监视器的评价的磁性的回声光谱学(太太) 它立即在 transcatheter 以后的新陈代谢的变化动脉的 chemoembolization (不作声) 。方法：在这未来的研究，有大 HCC 的 28 个连续病人(】 或 = 在直径的 3 厘米) 由好针渴望活体检视证实了被招募。所有肝的损害和某 uninvolved 肝实质的 1H 太太与 1 被执行。5T 全部身体先生扫描仪。在他们之中， 15 个案例大约一个星期再被评估在以后不作声。主要代谢物象胆碱和类脂化合物和 afterinterventional 治疗在前那样被测量估计肿瘤的早反应。结果：在肝的 1H 太太的 Thetechnical 成功率高(33/41， 80%) ，仔细与呼吸运动，损害的地点，和 voxel 的尺寸有关。在系列， HCC 的胆碱混合物山峰与 uninvolved 肝实质相比提高了。在以后不作声，振幅和胆碱回声山峰的区域显著地下降了(从 0.352 +/- 的 choline-to-lipid 比率 0.080 ～ 0.167 +/-0.030， P = 0.026；从 0.205 +/- 0.060 ～ 0.070 +/-0.020， P = 0.042，分别地) ；然而，类脂化合物回声山峰上升了。结论：然而，在 vivo 1H，太太为大焦点的肝的损害的评估是技术上可行的重制度和稳定性不是几乎平淡的先生扫描。1H 太太能监视早阶段 HCC 在以后的新陈代谢的变化不作声但是限制 likequantification 仍然存在。

Angioplasty and stenting for severe vertebral artery orifice stenosis: effects on cerebellar function remodeling verified by blood oxygen level-dependent functional magnetic resonance imaging

Vertebral artery orifice stenting may improve blood supply of the posterior circulation of the brain to regions such as the cerebellum and brainstem. However, previous studies have mainly focused on recovery of cerebral blood flow and perfusion in the posterior circulation after interventional therapy. This study examined the effects of functional recovery of local brain tissue on cerebellar function remodeling using blood oxygen level-dependent functional magnetic reso- nance imaging before and after interventional therapy. A total of 40 Chinese patients with severe unilateral vertebral artery orifice stenosis were enrolled in this study. Patients were equally and randomly assigned to intervention and control groups. The control group received drug treat- ment only. The intervention group received vertebral artery orifice angioplasty and stenting ＋ identical drug treatment to the control group. At 13 days after treatment, the Dizziness Handicap Inventory score was compared between the intervention and control groups. Cerebellar function remodeling was observed between the two groups using blood oxygen level-dependent functional magnetic resonance imaging. The improvement in dizziness handicap and cerebellar function was more obvious in the intervention group than in the control group. Interventional therapy for severe vertebral artery orifice stenosis may effectively promote cerebellar function remodeling and exert neuroprotective effects.

Comprehensive assessment of a post-coronary bypass graft patient with cardiovascular magnetic resonance imaging and multi-detector computed tomography

Coronary bypass graft surgery (CABG) is a revascularization procedure which reduces myocardial ischemia and cardiovascular morbidity and mortality in selected patients;however, up to 40% of saphanous vein grafts may degenerate over 10 years. Although coronary angiography is the gold standard to detect graft patency and native vessel disease, sometimes it is difficult to locate the grafts resulting in increased exposure to radiation and contrast administration. This case highlights the utility of cardiac computerized tomography and magnetic resonance imaging to provide comprehensive noninvasive assessment in a patient post CABG.(J Geriatr Cardiol 2007;4:244-247.)

Recent Advances in ^(19)Fluorine Magnetic Resonance Imaging with Perfluorocarbon Emulsions

The research roots of ^(19)fluorine( ^(19)F) magnetic resonance imaging(MRI) date back over 35 years. Over that time span, ~1H imaging flourished and was adopted worldwide with an endless array of applications and imaging approaches, making magnetic resonance an indispensable pillar of biomedical diagnostic imaging. For many years during this timeframe, ^(19)F imaging research continued at a slow pace as the various attributes of the technique were explored. However, over the last decade and particularly the last several years, the pace and clinical relevance of ^(19)F imaging has exploded. In part, this is due to advances in MRI instrumentation, ^(19)F/~1H coil designs, and ultrafast pulse sequence development for both preclinical and clinical scanners. These achievements, coupled with interest in the molecular imaging of anatomy and physiology, and combined with a cadre of innovative agents, have brought the concept of ^(19)F into early clinical evaluation. In this review, we attempt to provide a slice of this rich history of research and development, with a particular focus on liquid perfl uorocarbon compound-based agents.

Diagnosis and management of ischemic cardiomyopathy: Role of cardiovascular magnetic resonance imaging

Coronary artery disease(CAD) represents an important cause of mortality. Cardiovascular magnetic resonance(CMR) imaging evolved as an imaging modality that allows the assessment of myocardial function, perfusion, contractile reserve and extent of fibrosis in a single comprehensive exam. This review highlights the role of CMR in the differential diagnosis of acute chest pain by detecting the location of obstructive CAD or necrosis and identifying other conditions like stress cardiomyopathy or myocarditis that can present with acute chest pain. Besides, it underlines the prognostic implication of perfusion abnormalities in the setting of acute chest pain. Furthermore, the review addresses the role of CMR to detect significant CAD in patients with stable CAD. It elucidates the accuracy and clinical utility of CMR with respect to other imaging modalitieslike single-photon emission computed tomography and positron emission tomography. Besides, the prognostic value of CMR stress testing is discussed. Additionally, it summarizes the available CMR techniques to assess myocardial viability and describes algorithm to identify those patient who might profit from revascularization those who should be treated medically. Finally, future promising imaging techniques that will provide further insights into the fundamental disease processes in ischemic cardiomyopathy are discussed.

Computer-aided differential diagnosis system for Alzheimer’s disease based on machine learning with functional and morphological image features in magnetic resonance imaging

Alzheimer’s disease (AD) is a dementing disorder and one of the major public health problems in countries with greater longevity. The cerebral cortical thickness and cerebral blood flow (CBF), which are considered as morphological and functional image features, respectively, could be decreased in specific cerebral regions of patients with dementia of Alzheimer type. Therefore, the aim of this study was to develop a computer-aided classification system for AD patients based on machine learning with the morphological and functional image features derived from a magnetic resonance (MR) imaging system. The cortical thicknesses in ten cerebral regions were derived as morphological features by using gradient vector trajectories in fuzzy membership images. Functional CBF maps were measured with an arterial spin labeling technique, and ten regional CBF values were obtained by registration between the CBF map and Talairach atlas using an affine transformation and a free form deformation. We applied two systems based on an arterial neural network (ANN) and a support vector machine (SVM), which were trained with 4 morphological and 6 functional image features, to 15 AD patients and 15 clinically normal (CN) subjects for classification of AD. The area under the receiver operating characteristic curve (AUC) values for the two systems based on the ANN and SVM with both image?features were 0.901 and 0.915, respectively. The AUC values for the ANN-and SVM-based systems with the morphological features were 0.710 and 0.660, respectively, and those with the functional features were 0.878 and 0.903, respectively. Our preliminary results suggest that the proposed method may have potential for assisting radiologists in the differential diagnosis of AD patients by using morphological and functional image features.

More Peripheral Visualization of Hepatic Arteries by Using Respiratory-Triggered 3D True Steady-State Free-Precession Projection Magnetic Resonance Angiographic Sequences with Time-Spatial Labeling Inversion Pulse

Purpose: To evaluate respiratory-triggered three-dimensional (3D) true steady-state free-precession (SSFP) projection magnetic resonance angiographic sequences with time-spatial labeling inversion pulse (Time-SLIP) for visualizing the hepatic arteries and to optimize the image acquisition protocol. Materials and Methods: A 1.5-T clinical magnetic resonance imager was used to perform abdominal magnetic resonance angiography (MRA) in 25 consecutive patients before transcatheter arterial chemoembolization or surgery. We compared two selective space-labeling inversion pulse (tag pulse) patterns (Patterns I and II, oblique and parallel tag pulses, respectively). Two experienced radiologists evaluated the number of hepatic arterial branches visible on the acquired MRA images, and the results were referenced with those on images from intra-arterial digital subtraction angiography. Results: Images were acquired from all patients. The two radiologists clearly visualized branches of the left and right hepatic arteries. More peripheral hepatic arterial branches were identified in MRA images captured by using tag pulse Pattern I than in those acquired by using Pattern II (P P > 0.05). Conclusion: Non-contrast-enhanced Time-SLIP hepatic MRA with true SSFP allowed selective visualization of peripheral hepatic vessels.

Morphological and functional evaluation of chronic kidney disease using magnetic resonance imaging

X-ray computed tomography(CT),ultrasonography(US)and radionuclide scanning are important clinical methods for evaluating morphology of the kidney.These modalities are also applicable for estimating kidney function with time lapse analysis using proper contrastmedia as may be necessary.In the case of US,it can estimate kidney function based on the measurement of blood flow using the Doppler effect.Formerly,magnetic resonance imaging(MRI)was an inappropriate diagnostic imaging technique for abdominal organs because of their respiratory displacements.However,MRI is now actively used for kidney as well as liver or other parenchymal organs,in tandem with the technological advances.Unlike unenhanced X-ray CT,"conventional"MRI can distinguish the border between cortex and medulla in T1 or T2 weighted images.It was known that the border blurred with decreasing kidney function.Moreover,several other particular imaging methods were introduced in recent years,and these could be called"functional"MRI.In this review,the following are discussed:functional MRI for chronic kidney disease,which include blood oxygenation level-dependent MRI for evaluation of hypoxia,diffusion-weighted imagingfor evaluation of fibrosis,diffusion tensor imaging for evaluation of microstructure,and arterial spin labeling to evaluate the amount of organ perfusion,accompanied with several related articles.The ultimate goal of functional MRI is to provide useful in vivo information repeatedly for daily medical treatment non-invasively.

Advances in arterial spin labeled cerebral perfusion imaging in cerebrovascular diseases

Cerebrovascular disease is a disease with high morbidity,disability and mortality rates,which seri-ously affects the daily life of patients and is a heavy burden on families and society.Arterial spin labeling(ASL)is a magnetic resonance imaging(MRI)technology that uses the magnetic labeling of hydrogen atoms in arterial blood as tracers to noninvasively evaluate brain blood flow.ASL does not require injection of an exogenous contrast agent,and has the advantages of no radiation,simplicity and low cost.In cerebrovascular diseases,ASL can evaluate the collateral cerebrovascular circulation and abnormal perfusion of brain tissue,which can provide a reliable basis for early diagnosis and clinical decision-making.This study reviewed ASL and its application in the diagnosis,treatment and prognosis of cerebrovascular diseases.

Superparamagnetic Iron Oxide Labeling of Neural Stem Cells and 4.7T MRI Tracking in vivo and in vitro

Neural stem cells were labeled with superparamagnetic iron oxide （SPIO） and tracked by MRI in vitro and in vivo after implantation, Rat neural stem cells were labeled with SPIO combined with PLL by the means of receptor-mediated endocytosis. Prussian blue staining and electron microscopy were conducted to identify the iron particles in these neural stem cells. SPIO-labeled cells were tracked by 4.7T MRI in vivo and in vitro after implantation, The subjects were divided into 5 groups, including 5× 10^5 labeled cells cultured for one day after labeling, 5 × 10^5 same phase unlabeled cells, cell culture medium with 25μg Fe/mL SPIO, cell culture medium without SPIO and distilled water. MR/scanning sequences included TIWI, T2WI and T2＊WI. R2 and R2＊ of labeled cells were calculated. The results showed： （1） Neural stem cells could be labeled with SPIO and labeling efficiency was 100%. Prussian blue staining showed numerous blue-stained iron particles in the cytoplasm; （2） The average percentage change of signal intensity of labeled cells on TIWI in 4.7T MRI was 24.06%, T2WI 50.66% and T2＊WI 53.70% respectively; （3） T2 of labeled cells and unlabeled cells in 4.7T MRI was 516 ms and 77 ms respectively, R2 was 1.94 s^-1 and 12.98 s^-1 respectively, and T2＊ was 109 ms and 22.9 ms, R2＊ was 9.17 s^-1 and 43.67 s^-1 respectively; （4） Remarkable low signal area on T2WI and T2＊WI could exist for nearly 7 weeks and then disappeared gradually in the left brain transplanted with labeled cells, however no signal change in the right brain implanted with unlabeled cells. It was concluded that neural stem cells could be labeled effectively with SPIO. R2 and R2＊ of labeled cells were increased obviously. MRI can be used to track labeled cells in vitro and in vivo.

Comparison of 16 slice multi-detector computed tomography and breath hold 3D magnetic resonance angiography in the detection of coronary stenosis

Objective To compare 16-slice multi-detector spiral computed tomography (MDCT) and breathhold 3D magnetic resonance (MR) coronary angiography in the visualization of coronary arteries and the accuracy of detecting significant (＞ 50%) coronary stenoses in patients with suspected coronary artery disease. Methods Forty patients were examined by 16-slice CT (GE, Lightspeedl6)and MR (GE,Twinspeed) within 3 days; 31 of them underwent conventional coronary angiography (CAG) within 2 weeks after CT and MR scan. CT was performed with 16× 1.25 mm detector collimation, 0.5 s rotation time and images were reconstructed at 60%-75% of the cardiac cycle. MR was performed with breath hold 3D FIESTA (TR4.0 ms, TE1.7 ms, flip angle 65, slice thickness 3 mm, FOV 280 mm, matrix 256× 192). Mean heart rate was 63 ± 5.8 bpm and β-blocker was used in 24 patients. MR and CT image quality was evaluated in 9 coronary segments (RCA1, RCA2, RCA3, LM, LAD1, LAD2, LAD3, LCX1, LCX2) using a four-point grading scale.Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were calculated for detection of significant stenosis using CAG as the gold standard. Results 16-slice CT showed higher image quality in most coronary segments except RCA2.Forty-three segments were diagnosed as significant stenosis by CAG, 36 and 27 of these were correctly detected by CT and MR respectively. Sensitivity, specificity, positive predictive value, and negative predictive value of 16-slice CT and MR for detecting significant stenosis were 83 %, 84 %, 49 %, 97 % and 63 %, 90 %, 55 %, 93 %, respectively. Conclusion Sixteen-slice CT showed higher image quality in most coronary segments excepted for middle RCA. 16-slice CT had higher sensitivity than MR for detection of coronary significant stenosis, whereas MR had higher specificity than CT. Both CT and MR showed high negative predictive value,which is useful for excluding coronary stenosis in symptomatic patients.