MR多回波回复梯度回波序列在骶髂关节软骨成像中的应用

目的 探讨MR多回波回复梯度回波（MERGE）序列在骶髂关节（SIJ）软骨成像中的应用价值。方法 对30名健康志愿者SIJ软骨行MERGE、三维扰相梯度回波（3D-FSPGR）、质子密度加权成像脂肪抑制（PDWI-FS）、T2WI脂肪抑制（T2WI-FS）和T1WI脂肪抑制（T1WI-FS）序列成像,比较MERGE序列与其他各序列图像显示SIJ软骨的图像评分和SNR、CNR。结果 MERGE序列显示SIJ软骨的图像评分、CNR和SNR与3D-FSPGR序列比较差异均无统计学意义（P均>0.05）,与PDWI-FS、T2WI-FS、T1WI-FS序列比较差异有统计学意义（P均<0.001）。结论 MERGE序列显示SIJ软骨的图像质量较高。     

High-resolution T1-weighted gradient echo imaging for liver MRI using parallel imaging at high-acceleration factors

Purpose

To determine whether application of a high-acceleration parallel acquisition can provide three-dimensional (3D)-fat-suppressed T1-weighted gradient-recalled-echo (T1W-GRE) imaging at 3T for liver MR imaging.

Materials and methods

This retrospective study was approved by our institutional review board. Seventy patients underwent liver MRI at a 3T scanner. After administration of a standard dose of Gadoxetic acid for 20 min, 3D-T1W-GRE images were obtained twice using sensitivity encoding with acceleration factors (AFs) 2.6 [332 × 298 matrix, 3-mm slice thickness (ST)] and 4 (380 × 320 matrix, 1.5-mm ST). The image qualities of the two image sets were graded using a five-point scale.

Results

The high-resolution (HR) 3D-T1W-GRE image sets were obtained with an AF 4 within a single breath-hold (18.5 s). It showed a better anatomic depiction than conventional 3D-T1W-GRE image sets with an AF 2.6 (p < 0.05). Although the image noise was higher on the HR image sets (p < 0.05), the HR image sets showed better lesion conspicuity and overall image quality than the conventional image sets (p < 0.05).

Conclusion

With the use of high AFs, HR 3D-T1W-GRE imaging was demonstrated to be clinically more feasible and advantageous than the conventional 3D-T1W-GRE.     

同反相位图像减影技术及T2校正1H-MRS定量分析非酒精性脂肪肝的临床研究

目的：探讨双回波同反相位（IP-OP）减影法及T2校正1H-MRS定量分析非酒精性脂肪肝患者的肝脂肪含量（LFC）的可行性。方法：对42例临床怀疑脂肪肝的患者行3D T1WI IP-OP成像结合减影技术及1H-MRS检查。选取5名患者行多次回波PRESS序列以测量水、脂的T2值。采用非参数Spearman分析及Mann-Whitney U检验,比较评价两种影像方法定量分析脂肪肝的能力。结果：1H-MRS各峰值采用T2进行校正（T2水=33.1 ms,T2亚甲基=64.2 ms）。IP-OP减影法、1H-MRS对脂肪肝定性诊断的敏感度及特异度分别为89.2%、100%及91.2%、100%。IP-OP减影法及1H-MRS测得的脂肪含量与病理结果均呈显著的相关性（r=0.80,0.92;P＜0.01）。1H-MRS可有效区分无脂肪肝与轻度脂肪肝（Z=-2.97,P＜0.01）、轻度与中度脂肪肝（Z=-3.72,P＜0.01）、中度与重度脂肪肝（Z=-3.25,P＜0.01）,IP-OP减影法可有效区分无脂肪肝与轻度脂肪肝（Z=-2.54,P＜0.01）、轻度与中度脂肪肝（Z=-3.72,P＜0.01）,不能区分中度与重度脂肪肝（Z=-1.77,P=0.08）。1H-MRS、IP-OP减影法测得的LFC均低于病理结果（除无脂肪肝组外,Z≤-2.21,P＜0.05）。结论：IP-OP减影法可简单快速的诊断脂肪肝程度,1H-MRS对脂肪肝的定量诊断具有更高的准确性。     

3.0T水脂分离梯度回波成像定量分析肝脏脂肪含量的可行性

目的 探讨3.0T水脂分离梯度回波序列在一次屏息内完成定量分析肝脏脂肪的可行性及其参数优化。方法 利用GE Signa HDx 3.0T MR系统对自制体模及42名受检者行迭代最小二乘法非对称采集水脂分离（IDEAL）梯度回波序列和单体素¹H-MRS,通过分析接收带宽（BW）、翻转角（FA）和矩阵（Matrix）的变化对体模脂肪定量分析的影响,确定以IDEAL梯度回波行脂肪定量分析的最优成像参数;以¹H-MRS测定的脂肪含量为参考标准,采用Spearman相关分析对IDEAL梯度回波序列测得数据进行相关性分析。结果 应用IDEAL梯度回波序列行体模脂肪定量分析时,BW和FA对结果的影响较大;BW为200 kHz、FA为12°时,体模脂肪定量分析结果与MRS的关联性最佳（r=0.997,P<0.05）,在此条件下,应用IDEAL梯度回波序列和¹H-MRS测得的肝脏脂肪含量分别为（9.48±5.42）%和（10.13±8.06）%,二者呈正相关（r=0.872,P<0.05）。结论 经参数优化的IDEAL梯度回波序列可在一次屏息内定量分析肝脏脂肪含量;成像时需合理调整FA和BW。     

梯度回波同、反相位T1WI在不典型脂肪肝的应用价值

目的:探讨MR梯度回波同相位与反相位T1WI在不典型脂肪肝诊断中的应用价值。材料与方法:前瞻随访性研究24例不典型脂肪肝患者的常规MR成像及MR梯度回波同相位与反相位T1WI,直接观察肝脏脂肪变性灶在MRI常规序列及SPGR T1WI同相位与反相位像上的信号变化,并计算梯度回波同相位与反相位T1WI上肝脏脂肪变性灶与脾脏的信号强度比(SIR),应用小样本配对t检验作统计学差异分析。结果:弥漫性脂肪肝伴正常肝岛8例,肝内局灶性脂肪浸润16例,肝脂肪变性灶在SE T1WI及FSE T2WI上为均等或稍高信号,正常肝岛呈相对低信号。在SPGR T1WI同相位与反相位像上,肝脂肪变性灶信号分别为等或稍高信号及低信号,脂肪变性灶与脾脏的信号强度比值分别为1.37±0.13和0.92±0.13,有明显统计学差异(t=-13.187,P=0.000)。结论:MR梯度回波同相位与反相位T1WI能对脂肪肝进行简单而敏感的定性检出,在US或CT表现不典型脂肪肝的诊断上具有重要价值。     

肝脏恶性肿瘤扩散加权成像与T2加权成像对比研究

目的比较肝脏扩散加权成像(DWI)和T2WI反映肝脏恶性肿瘤扩散特征、病理特征及肿瘤范围的价值.方法回顾性研究肝脏恶性肿瘤44例48灶(肝细胞癌30例30灶,肝转移瘤10例14灶,胆管细胞癌4例4灶),比较DWI与T2WI图像液体(脑脊液,胆囊胆汁)和肝脏恶性肿瘤的信号,肿瘤/肝脏信号强度比(SIR),对比噪声比(CNR)以及肿瘤范围,测量肿瘤表观扩散系数(ADC)值.结果在b=600 s/mm2的图像中,所有病例的脑脊液均显示为低信号.肝脏恶性肿瘤多表现为高信号,其信号分布特征与T2WI不同;肿瘤的信号强度和瘤/肝SIR,DWI与T2WI不相关;DWI信号强度与ADC值呈负相关.DWI的病灶对比噪声比高于T2WI,二者差异有显著性.DWI显示病灶范围与T2WI差异无显著性.结论b=600 s/mm2的肝脏DWI图像受T2穿透效应影响较小,能够较好地反映肝脏恶性肿瘤的扩散特征.DWI肿瘤对比噪声比更高,有助于病灶边界的确定.DWI反映的肝脏恶性肿瘤的扩散特征,可作为其影像学特征之一.     

T2-weighted magnetic resonance imaging of the liver: comparison of fat-suppressed GRASE with conventional spin echo, fat-suppressed turbo spin echo, and gradient echo at 1.0 T

BACKGROUND: Fat-suppressed T2-weighted gradient and spin echo (GRASE) magnetic resonance imaging in the liver was compared with three other sequences: conventional spin echo (SE), fat-suppressed and respiratory-triggered turbo SE (TSE), and fast field echo (FFE). METHODS: All sequences were applied in 48 prospective patients. Quantitative and qualitative analyses were performed. Biopsy or clinical follow-up established the final diagnosis of the lesions. RESULTS: GRASE showed the second best contrast-to-noise ratio, the second best artifact level, the same lesion detectability as TSE, and very short acquisition time. GRASE and TSE had the highest sensitivity, specificity, and accuracy. CONCLUSION: Fat-suppressed GRASE offers a fast and accurate method for imaging the liver.     

T2WI、DWI及Gd-EOB-DTPA增强扫描独立序列对结直肠癌肝转移瘤检出率的比较

目的 比较T2WI、DWI及Gd-EOB-DTPA增强扫描单独序列对结直肠癌肝转移瘤的检出效能。方法 选取31例结直肠癌肝转移患者,均行MR检查,包括T2WI/FS、DWI、Gd-EOB-DTPA常规动态增强(MR-Dyn)和肝细胞期(MR-Late)扫描。由2名医师共同阅片,对每组影像图像进行单独分析。记录所有检出病灶所在层面、肝段、与肝脏边缘的距离及病变大小。以手术病理、术中超声及治疗前后影像图像的综合评价作为金标准。采用配对McNemar检验比较各序列对肝转移瘤的检出率。结果 31例患者中,共检出156个肝转移瘤,大小0.3~7.3 cm,≤0.5 cm、0.6~1.0 cm、1.1~2.0 cm 和>2.0 cm 分别为 20、52、50和34个。对肝转移瘤的总体检出率,T2WI/FS、DWI、MR-Dyn和MR-Late分别为84.62%(132/156)、87.18%(136/156)、67.31%(105/156)和93.59%(146/156)。MR-Late对肝转移瘤的总体检出率明显高于T2WI /FS(P=0.020)和 MR-Dyn (P<0.001),与DWI的差异无统计学意义(P=0.064)。对≤0.5 cm肝转移瘤,T2WI/FS、DWI、MR-Dyn和MR-Late的检出率分别为30.00%(6/20)、65.00%、(13/20)25.00%(5/20)和85.00%(17/20),MR-Late检出率明显高于T2WI/FS(P=0.013)和MR-Dyn(P<0.001),与DWI的差异无统计学意义(P=0.219)。对0.6~1.0 cm肝转移瘤,T2WI/FS, DWI和MR-Late检出率分别为88.46%(46/52)、88.46%(46/52)和86.54%(45/52),均明显高于MR-Dyn(26/52,50.00%)。而对于>1.0 cm的肝转移瘤,所有序列检出率的差异均无统计学意义(P均>0.05)。结论 Gd-EOB-DTPA增强扫描对结直肠癌肝转移的检出率高,尤其有助于提高≤0.5 cm的肝转移瘤病灶检出率。     

3D T1WI动态增强成像诊断乳腺良恶性病变的价值

目的:评价T1WI动态增强成像在鉴别乳腺良恶性肿瘤方面的诊断价值。方法:54例乳腺疾病患者的59个病灶经T1WI动态增强成像,分析每个病灶的强化曲线类型、定量分析T1WI动态增强的早期强化率和达到强化峰值的时间,进行统计学处理。结果:应用T1WI动态增强成像序列,良、恶性病变的时间-信号强度曲线的分布有特异性,良性病变多为I、II型,恶性病变多为IV、V型,表现为III型曲线的病灶大部分为恶性病灶,少部分为良性病灶;信号强度增加率之间差异有显著性意义(t=2.563,P=0.015),但两者的早期增强程度范围有很大的重叠,敏感性为89.1%,特异性仅为30.7%;良、恶性病变增强信号达到峰值时间的差异有非常显著性意义(t=3.450,P=0.000),且二者之间重叠很少,诊断的敏感性为93.4%,特异性为69.2%。结论:T1WI动态增强的强化曲线类型、早期强化率在鉴别良恶性乳腺肿瘤方面有较高的敏感性,但特异性较差,病灶强化的峰值时间在乳腺肿瘤的良恶性鉴别方面具有较高的敏感性和特异性,可以提高乳腺MR成像诊断的准确性,减少组织穿刺活检率。     

Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery

Background: The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions. Methods: We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver–spleen contrast-to-noise ratio (CNR) and liver–lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader. Results: No significant difference was detected between R. trig. FSE and CSE or STIR in either liver–spleen CNR or liver–lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p < 0.01) and presence of artifact (p < 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p < 0.01) and CSE (p < 0.05). Conclusions: Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time. Received: 5 April 1995/Accepted: 2 May 1995     

外源性锰在大鼠脑内选择性沉积的磁共振成像研究

目的观察不同摄入方式下外源性锰在大鼠脑内的沉积与分布情况。方法采用T1加权磁共振成像研究了静脉注射(n=5)、腹腔注射(n=8)、鼻腔滴入(n=3)和口腔摄入(n=7)MnCl2溶液时,二价锰离子(Mn2 )在大鼠脑中的分布与选择性沉积。结果除口腔摄入方式外,其他摄入方式均可导致Mn2 在大鼠脑中具有空间选择性的分布,且分布模式与摄入方式有关。结论不同摄入方式、摄入时间及摄入总量均会影响Mn2 在脑中的沉积与分布。了解不同摄入条件下Mn2 在中枢神经系统中的分布,可为进一步研究锰的神经毒性提供基础实验数据。     

Detection and characterization of focal liver lesions using superparamagnetic iron oxide-enhanced magnetic resonance imaging: comparison between ferumoxides-enhanced T1-weighted imaging and delayed-phase gadolinium-enhanced T1-weighted imaging

Background: Double contrast magnetic resonance (MR) imaging using superparamagnetic iron oxide (SPIO) and gadolinium (Gd) is performed to detect and characterize focal liver lesions. However, this technique is a costly and lengthy process. The purpose of this study was to determine the usefulness of SPIO-enhanced MR imaging including SPIO-enhanced T1-weighted imaging in diagnosing focal liver lesions. Methods: Eighty-four focal liver lesions were examined with a 1.5-T MR unit. Transverse precontrast T1- and T2-weighted images and SPIO (ferumoxides)-enhanced T1- and T2-weighted images were obtained, followed by Gd-enhanced T1-weighted imaging. The Gd set (i.e., precontrast T1- and T2-weighted and delayed-phase gadolinium-enhanced T1-weighted images) and ferumoxides set (i.e., precontrast T1- and ferumoxides-enhanced T1- and T2-weighted images) were reviewed by two independent readers. Results: More lesions were detected from the ferumoxides set than from the Gd set. Ferumoxides-enhanced T1-weighted imaging showed enhancement patterns of the lesions similar to those of delayed-phase Gd-enhanced T1-weighted imaging. The diagnoses of hepatic metastasis and cyst by the ferumoxides set were similar to those by the Gd set. However, a dynamic study may be inevitable for the diagnosis of hepatocellular carcinoma and hemangioma. Conclusion: The ferumoxides set was useful for the detection of focal hepatic lesions. Ferumoxides-enhanced T1-weighted imaging may replace delayed-phase gadolinium-enhanced T1-weighted imaging in the diagnosis of hepatic metastasis and cysts.     

Dynamic T1-weighted ferumoxides enhanced MRI for imaging liver hemangiomas: preliminary observations

The T1-based signal-enhancing effects of ferumoxides was studied in five liver hemangiomas on short echo-time gradient-recalled echo dynamic magnetic resonance imaging to assess the utility of this technique to image perfusion patterns in liver hemangiomas. We observed peripheral nodular enhancement with centripetal fill in all hemangiomas. Our results suggest that this imaging technique, after rapid injection of ferumoxides, can be used for lesion characterization. Received: 25 February 2000/Revision accepted: 25 May 2000     

MR imaging of cervical carcinoma: comparison among T2-weighted,dynamic, and postcontrast T1-weighted images with histopathological correlation

Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images. Received: 10 November 1995/Accepted after revision: 13 March 1996     

T2-weighted MR imaging for hepatic hemangiomas: comparison of breath-hold and non-breath-hold turbo spin-echo pulse sequences with phased-array multicoil

Background: We compared T2-weighted and heavily T2-weighted breath-hold turbo spin-echo (TSE) sequences with T2-weighted non-breath-hold TSE sequence to evaluate hepatic hemangiomas on magnetic resonance (MR) with a phased-array multicoil. Methods: Twenty-two patients with 27 hemangiomas were studied at 1.0-T scanner by using T2-weighted and heavily T2-weighted breath-hold TSE sequences (18 s each) and non-breath-hold T2-weighted TSE sequences with use of a phased-array multicoil. Images were quantitatively analyzed for tumor-to-liver signal-difference-to-noise ratios (SD/Ns) and tumor-to-liver signal intensity ratios (T/Ls) and qualitatively analyzed for tumor conspicuity and motion-induced image artifacts. Results: Quantitatively, T2-weighted breath-hold TSE images showed the highest SD/Ns among the three sequences, although the differences from the heavily T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were not statistically significant (p= 0.61 and 0.06, respectively). Heavily T2-weighted breath-hold TSE images showed the highest T/Ls among the three sequences. The differences from the T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were statistically significant (p < 0.001). Qualitatively, breath-hold TSE images were superior to non-breath-hold TSE images in terms of tumor conspicuity (p < 0.01) and motion artifacts (p < 0.01). Conclusion: T2-weighted breath-hold TSE sequence is superior to T2-weighted non-breath-hold TSE sequence in the evaluation of hepatic hemangiomas on MR with a phased-array multicoil. Received: 7 April 1997/Accepted: 28 May 1997     

MR三维快速扰相梯度回波序列显示甲状腺结节图像质量

目的 评价MR三维快速扰相梯度回波(3D FSPGR)序列显示甲状腺结节的图像质量.方法 回顾性分析60例甲状腺结节患者的快速自旋回波(FSE)及3D FSPGR序列脂肪抑制增强T1WI,对甲状腺结节及正常甲状腺组织的图像质量及脂肪抑制效果、呼吸吞咽运动伪影进行主观评价,并对比甲状腺结节和正常甲状腺组织图像的信噪比(S...