CT未见钙化和脂肪的肺错构瘤的MRI与病理对比分析

作者对5例CT扫描未发现钙化和脂肪者行MRI检查,并经手术确诊为肺错构瘤的患者进行分析。年龄52～70岁(平均59.4岁)男4例,女1例。1.5T MRI装置。用SE T_1 WI(TR=1心动周期,TE=12～20ms,矩阵132×256～192×256,2～4次激发),T_2 WI(TR=2～4心动周期,TE=90～128ms,矩阵128×256～138×256,2～4次激发)及3D FLASH(TR/TE=10/4ms,翻转角18°),另外使用3D FISP(TR/TE=5/2ms,翻转角15°)进行动态     

MRA在胸内肿块的临床应用

作者使用MRA评价了15例胸内肿块。MR扫描仪场强1.5T。先用环形极化体部线圈常规作胸部冠状面和横断面T_1加权MRI,TR600～1000 ms,TE15ms,扫描线400mm,层厚8 mm。然后用FLASH二维脉冲序列行MRA检查(TR30ms/TE10ms,翻转角30°,矩阵256×256,层厚5 mm,重叠1 mm)。扫描时让病人在深吸气后屏气,一般需做25～30个切面才能覆盖纵隔和肺内血管。最初得到的是MRA冠状面图象,全部检查时间(MR+MRA)约为90分钟。FLASH二维图象经MIP     

扩散加权MRI在软组织肿瘤中的应用

为了探讨扩散加权MRI对软组织肿瘤的诊断价值,作者对23例软组织肿瘤病人(男11例,女11例,年龄11～70岁,其中1例患两种肿瘤)行扩散加权MRI,MR场强为1.5T,最大梯度场强为23mT/m。采用表面线圈,TR=2-RR,TE=70ms,翻转角为90°,FOV 200～300mm,b=0、176、     

彩色多普勒超声诊断Cockett综合征的价值探讨

目的探讨彩色多普勒超声对Cockett综合征的价值。方法对经CT血管造影成像或数字减影血管造影证实的47例未形成深静脉血栓的Cockett综合征声像图表现进行回顾性分析。结果 Cockett综合征声像图直接表现为左侧髂总静脉管腔局部受压变窄、血流速度增高,受压远段髂总静脉扩张、血流速度减低、侧支静脉形成或髂内静脉血流反向。结论彩色多普勒超声是诊断Cockett综合征有价值的影像学方法。     

慢性多发性关节炎的手部磁共振成象

作者为39例风湿性关节炎患者的40只手作了MRI 检查。磁场强发1.5T,梯度磁场强度为10mT/m。其中10例使用了一个矩形线圈(规格10×20cm)分别摄取关节腔、腕部、掌部和手指图象。另30例使用了一个直径为8cm 的环形线圈。层厚为3和4mm。T_1一加权SE 序列(TR550ms,TE30ms)中矩阵为512×512(4次测量),T_2加权SE 序列(TR1800ms,TE50和100ms)中和快场回波序列(Fast—Field—Echo—SequenzenTR371ms,TE13.3ms,翻转角度70°)中矩阵为256×256(分别为2次和4次测量)。由于相位编码中矩阵减少到70%,故每只手两个方向上成象共约需45分钟。检查时病人取俯卧位,手臂过     

腔内介入治疗Cockett综合征伴左下肢深静脉血栓形成

目的 探讨Cockett综合征伴左下肢深静脉血栓形成(DVT)腔内介入治疗的临床效果.方法 回顾性分析2011年1月至2015年1月收治的256例Cockett综合征伴左下肢DVT患者,采用经导管接触溶栓、球囊扩张闭塞/狭窄段或支架植入术治疗,比较治疗前后患肢周径差、远期通畅率.结果 256例Cockett综合征伴左下肢DVT患者中232例(90.6％)血栓完全溶解.24例(9.4％)部分溶解,治疗前后患肢大腿与小腿周径差分别为(7.12±2.15) cm、(4.57±2.81) cm.206例髂静脉重建患者中单纯球囊扩张46例,球囊扩张联合髂静脉支架植入160例;平均随访15个月(9～24个月),单纯球囊扩张患者失访3例,出现髂静脉闭塞26例(60.5％),血栓后综合征(PTS)21例(48.8％),球囊扩张联合支架植入患者失访11例,支架狭窄/闭塞13例(8.7％),PTS 15例(10.1％),两组闭塞/狭窄、PTS差异有统计学意义(P＜0.001).结论 导管接触溶栓、球囊扩张联合支架植入治疗Cockett综合征,具有确切的临床疗效.     

颅内出血性病变:用0.5T和1.5T SE和GR MRI的评价

作者对20例典型的颅内出血(50处病变)的MR表现作3回顾性分析。MRI使用两种场强(0.5T和1.5T)、SE(自旋回波序列)和GR(梯度聚焦回波序列)T_2加权。两种场强的SE T_2加权TR/TE均为500/30,T_2加权TR/TE为250/30,60,层厚在0.5T和1.5T分别为8mm和7mm,层面间隔为层厚的10%;两种场强的GR T_2~*加权TR/TE均为500/35,层厚10mm,使用35°翻转角。根据两种场强三种序列的检查所见,作者认     

胰导管腺癌:CT和1.5T MRI评价的比较

作者前瞻性分析了50例临床疑诊胰腺癌病人的CT和1.5T MR检查。男18例,女32例,平均年龄57岁。41例(82%)进行了CT平扫和增强扫描,34例系动态扫描。平均层厚5mm,层间距5.7mm或10mm。增强扫描层厚和层间距均为10mm。动态CT扫描于静脉快注60ml造影剂(2ml/s)后开始,另继续团注入40～90ml造影剂连续作3～6次动态扫描。48例(96%)行MR检查者均采用1.5T超导系统,假门控自旋回波:T_1加权象TR250～300,TE20;T_2加权象TR2000,TE70;梯度回波成象翻转角为30°～50°,层厚10mm,间距     

用MRA和3D CTA诊断未破裂脑动脉瘤

作者研究了MRA、3D CTA、DSA对未破裂脑动脉瘤的诊断率。MRA摄像选用GE Signa Advantage(1.5T),用3D TOF快速SPGR成像,参数为TR/TE14.8ms/3.4ms,矩阵256×128,层厚1.0mm,翻转角20°,NEX2次,60mm层块,FOV12cm,扫描时间4min49s×3。在枕骨大孔至胼胝体的3个层块摄像,从椎动脉至大脑前动脉末端的动脉瘤均能诊断。3D CTA选用GE Hispeed Advantage,Advantage     

颈内动脉“假性闭塞”:颅内MRA检查的一种错误

由于MRA具有不用对比剂即可显示血管的能力,因而已成为神经系统血管性病变可选择性的检查方法。然而TOF MRA潜在存在着一些伪影和误区,可导致错误诊断。作者报道了1例因颅内MRA检查误导而显示的颈内动脉“假性闭塞”。MRA检查用1.5T超导型机,以颅底动脉环为中心行3D-TOF MRA检查(翻转角20°,TR40 ms,TE6 ms,采     

Imaging of the intracranial venous system with a contrast-enhanced volumetric interpolated examination

A contrast-enhanced interpolated, three-dimensional (3D) gradient-echo MR sequence with asymmetric k-space sampling, which we refer to as volumetric interpolated brain examination (VIBE), was evaluated for its depiction of the normal intracranial venous system and compared with two-dimensional (2D) time-of-flight (TOF) MR venography (MRV). Fifteen subjects underwent contrast-enhanced VIBE imaging (TR/TE 8 ms/4.4 ms, flip angle 18°, acquisition time, 2 min 20 s, voxel size approximately 1.5 mm³) and standard 2D TOF MRV (TR/TE 27 ms/9 ms, flip angle 35°). The presence of 19 venous structures per subject was assessed on maximum intensity projections (MIP) of the whole data set (whole-brain MIP) and on MIP images reconstructed spontaneously from source images (interactive MIP/source images). Results from a consensus reading where all imaging techniques and display modalities were available were taken as the standard of reference for the presence of venous structures. In addition, 10 subjects underwent both unenhanced and enhanced VIBE imaging. The value of subtracted data sets (unenhanced VIBE subtracted from enhanced VIBE) was then evaluated. Overall, VIBE provided a superior visualization of the cerebral veins than 2D TOF MRV (VIBE, sensitivity (reader 1/reader 2): 98%/99%, negative predictive value 64%/71%; TOF sensitivity: 85%/84%, negative predictive value 15%/15%; Wilcoxon signed-rank test VIBE vs TOF, p<0.001 for both readers). The VIBE interactive MIP/source images were superior to whole-brain MIP reconstructions. Image subtraction was not necessary for delineation of venous structures but improved small vein conspicuity. Contrast-enhanced VIBE acquisitions are faster and enable a visualization of the normal intracranial venous system superior to that of 2D TOF MRV. Electronic Publication     

Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results

The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradient-echo (GE) images were obtained (TR 32 ms, TE 10 ms, flip angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45 ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE 96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences. Received 24 May 1996; Accepted 30 August 1996     

Time-reduced T2-weighted celebral MRI with optimized flip angles

This study was set up to see whether lowering the flip angle in proton density- and T2-weighted double-spin echo sequences allows for shortening of repetition time (TR) and imaging time without significant change of image quality. Ten patients with celebral white matter lesions were investigated with an 1.5 T MR scanner using a conventional long- TR double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and reduced-TR double-spin echo sequences (TR = 1900 ms, TE = 15 and 70 ms) at flip angles of 90°, 80°, 70°, 60°, and 50°. Lowering the flip angle resulted in less T1-contrast and a relative increase of T2-contrast. At a flip angle of 70°, contrast-to noise ratios (NNRs) between lesions and brain, as well as image artifacts of the reduced-TR sequence (CNR: 22.4) were similar to the conventional long-TR sequence (CNR:21.1), while imaging time was shortened by about 25%. Offprint requests to: Peter Schubeus     

Selective water excitation for faster MR imaging of articular cartilage defects: initial clinical results

Our objective was to compare a water-excitation (WE) 3D fast low-angle shot (FLASH) MR sequence for faster imaging of articular cartilage defects of the knee to a conventional fat-saturated (FS) 3D FLASH MR sequence. This prospective study included 16 knees of 16 patients with suspected cartilage lesions. The MR imaging in transverse and sagittal planes included (a) FS 3D FLASH (TR/TE: 45 ms/11 ms, scan time 8 min, flip angle 50°), and (b) WE 3D FLASH (TR/TE: 28 ms/11 ms, scan time 4 min 58 s, flip angle 40°). For each sequence signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were quantified. The detected cartilage lesions were evaluated using a semi-quantitative four-scale scoring system (grades 0–III). The data were compared between the sequences using the paired Student's t-test. No statistically significant differences between the sequences were found for SNR, CNR, and cartilage defect grading (p=0.14–0.8). The WE 3D FLASH MR imaging seems to be promising for fast imaging of articular cartilage lesions of the knee. Electronic Publication     

High‐resolution maps of magnetization transfer with inherent correction for RF inhomogeneity and T1 relaxation obtained from 3D FLASH MRI

An empirical equation for the magnetization transfer (MT) FLASH signal is derived by analogy to dual‐excitation FLASH, introducing a novel semiquantitative parameter for MT, the percentage saturation imposed by one MT pulse during TR. This parameter is obtained by a linear transformation of the inverse signal, using two reference experiments of proton density and T₁ weighting. The influence of sequence parameters on the MT saturation was studied. An 8.5‐min protocol for brain imaging at 3 T was based on nonselective sagittal 3D‐FLASH at 1.25 mm isotropic resolution using partial acquisition techniques (TR/TE/α = 25ms/4.9ms/5° or 11ms/4.9ms/15° for the T₁ reference). A 12.8 ms Gaussian MT pulse was applied 2.2 kHz off‐resonance with 540° flip angle. The MT saturation maps showed an excellent contrast in the brain due to clearly separated distributions for white and gray matter and cerebrospinal fluid. Within the limits of the approximation (excitation <15°, TR/T₁ ? 1) the MT term depends mainly on TR, the energy and offset of the MT pulse, but hardly on excitation and T₁ relaxation. It is inherently compensated for inhomogeneities of receive and transmit RF fields. The MT saturation appeared to be a sensitive parameter to depict MS lesions and alterations of normal‐appearing white matter. Magn Reson Med 60:1396–1407, 2008. © 2008 Wiley‐Liss, Inc.     

Incidence of adrenal masses in patients referred for renal artery stenosis screening MR

RATIONALE AND OBJECTIVES: Prior work has shown the efficacy of magnetic resonance (MR) in renal artery stenosis evaluation. The increasing role of renal artery stenosis in the differential diagnostic evaluation of hypertension raises the question of whether MR should be used as a screening modality. This project evaluated the additional potential benefits of MR by determining the incidence of adrenal masses in this selected population. METHODS: A 2-year retrospective study analysis of patients who failed to respond to antihypertensive medical management and were referred for renal MR for hypertension amassed 77 subjects ranging in age from 18 to 88 years. A masked analysis for adrenal masses was performed on this data set. Magnetic resonance techniques included T2-weighted turbo spin-echo (repetition time [TR] 2000-4000 ms, echo time [TE] 80-100 ms, turbo factor 2-16), T1-weighted spin-echo (TR 200-500 ms, TE 10-30 ms), gradient-echo time-of-flight (TR 26 ms, TE 6.9 ms, 40 degrees flip angle, 2 excitations), and dynamic gadopentetate dimeglumine-enhanced MR angiography (three-dimensional gradient recalled echo, TR 10 ms, TE 3 ms, 40 degrees flip angle, 1 excitation). RESULTS: Thirty-three patients had renal artery disease, 44 had normal renal arteries, and 7 had adrenal masses. Forty-three percent of patients who underwent renal MR had disease of the renal arteries detected, and 9% of patients referred for MR had adrenal masses that would have been missed with scintigraphy and/or angiography, of which 57% were responsible for hypertension. CONCLUSIONS: The ability to evaluate renal artery and adrenal anatomy globally can be useful, as exemplified in the current series, and the adrenals should be examined carefully in any renal MR in a hypertensive patient.     

Cervical spine: MR imaging with a partial flip angle, gradient- refocused pulse sequence. Part I. General considerations and disk disease

A magnetic resonance imaging pulse sequence with a short repetition time (TR), short echo time (TE), partial flip angle, and gradient refocused echo was evaluated for the detection of cervical disk disease in a prospective study of 90 patients. These parameters were manipulated to adjust signal-to-noise ratio (S/N) and contrast: flip angle (3 degrees-18 degrees), TR (22-60 msec), and TE (12.5-25 msec). Flip angle had the greatest effect on S/N and contrast; its effect differed between axial and sagittal imaging. Cerebrospinal fluid S/N reached a peak at a smaller flip angle in sagittal imaging than in axial imaging. The useful range of flip angles depended on TR. Increasing TR had minimal direct effect on S/N or contrast, but because a longer TR allowed the use of larger flip angles for both axial and sagittal imaging, higher S/N could be achieved with similar contrast. This effect of increasing TR had to be balanced against increased imaging time and increased probability of motion artifact. Increasing TE decreased S/N, increased contrast, and increased magnetic susceptibility artifacts. For the diagnosis of cervical disk disease, the best sequence appears to be one with a very short TR, short TE, and small flip angles within a narrow range.     

Value of blood pool contrast agents in magnetic resonance angiography of the pelvis and lower extremities

Our objective was: (1) to determine the appropriate dose of new ultrasmall superparamagnetic iron oxide particles for magnetic resonance angiography (MRA). This agent comprised of a single iron oxide crystal stabilized with a carbohydrate-polyethylene glycol coat (PEG-Ferron/NC 100150 injection); (2) to determine the proper flip angle for PEG-Ferron-enhanced 3 D time-of-flight (TOF) MRA sequence; and (3) to compare the enhancement of peripheral vessels following PEG-Ferron and GdDTPA-BMA. MRA parameters were: TR/TE = 50/2.1 ms, NEX = 1, FOV = 30 × 30 × 1.8 cm, and matrix = 256 × 128 × 64. In anesthetized beagle dogs (n = 10), the effects of PEG-Ferron and GdDTPA-BMA on regional signal were monitored for 45 min and compared. The lowest dose of PEG-Ferron (0.05 mmol/kg) produced the best enhancement of primary, secondary and tertiary vessels. The flip angle 60 ° provided better enhancement than 20 ° on contrast enhanced images. Unlike GdDTPA-BMA, PEG-Ferron allowed prolonged delineation (> 45 min) of the pelvis and lower extremities circulation. PEG-Ferron provided greater Contrast-to-noise ratio CNR (80.2 ± 6.2, P < 0.05) than GdDTPA-BMA (63.5 ± 2.5). It may be possible for blood pool contrast-enhanced 3 D TOF MRA to provide valuable information for visualization of vascular tree including guiding interventions. Received 6 August 1997; Revision received 25 November 1997; Accepted 3 February 1998     

MR imaging of hyaline cartilage at 0.5 T: a quantitative and qualitative in vitro evaluation of three types of sequences

Objective. To identify an optimal pulse sequence for in vitro imaging of hyaline cartilage at 0.5 T. Materials and methods. Twelve holes of varying diameter and depth were drilled in cartilage of two pig knees. These were submerged in saline and scanned with a 0.5-T MR system. Sixteen T1-weighted gradient echo (GE), two T2-weighted GE, and 16 fast spin echo sequences were used, by varying repetition time (TR), echo time (TE), flip angle (FA), echo train length, profile order, and by use of fat saturation. Contrast-to-noise ratios (CNR) of cartilage versus saline solution and cartilage versus subchondral bone were measured. Cartilaginous lesions were evaluated separately by three independent observers. Interobserver variability and correlation between the quantitative and qualitative analyses were calculated. Results. The mean CNRs of two specimens of cartilage versus saline solution ranged from 6.3 (±2.1) to 27.7 (±2.5), and those of cartilage versus subchondral bone from 0.3 (±0.2) to 22.5 (±1.4). The highest CNR was obtained with a T1-weighted spoiled 3D-GE technique (TR 65 ms, TE 11.5 ms, FA 45°). The number of lesions observed per sequence varied from 35 to 69. Observer agreement was fair to good. The T1-weighted spoiled GE sequences with a TR of 65 ms, TE of 11.5 ms and FA of 30° and 45° were significantly superior to the other 34 sequences in the qualitative analysis. Conclusion. T1-weighted spoiled 3D-GE sequences with a TR of 65 ms, a TE of 11.5 ms, and a FA of 30–45° were found to be optimal for in vitro imaging of cartilage at 0.5 T.