二维超声多普勒及磁共振诊断纵隔肿瘤的对比分析

本文对３５例经手术和病理证实的纵隔肿瘤进行二维超声多普勒（２Ｄ－Ｄ）及磁共振（ＭＲＩ）诊断分析。结果表明，２Ｄ－Ｄ能在短时间内迅速全面地对纵隔肿瘤进行扫查，明确分辨出实质性和囊性肿物，同时多普勒能很好的将无回声的囊肿及血管区别开。由于胸廓及肺气的影响，个别患者超声不能显示肿瘤的全貌，其诊断符合率为９４％。ＭＲＩ可显示纵隔肿瘤的全貌，其诊断符合率为１００％，但该项检查费用较贵，有些患者不易接受     

经静脉声学造影诊断睾丸扭转的价值

目的:探讨睾丸扭转时超谐波造影增强后血流灌注特点及诊断价值.材料和方法:对10例疑诊睾丸扭转病例行间歇超谐波声学造影,间歇成像触发间隔1～4s,造影剂剂量0.003ml/kg体重.结果:注射造影剂后16～22s睾丸周边及实质血管显影,回声增强;触发间隔3s时睾丸实质回声强度最大.8例确诊睾丸扭转,睾丸实质内见完全性或区域性造影缺损;2例排除睾丸扭转,睾丸实质内见带状增强回声弥漫性充填.结论:间歇超谐波声学造影低剂量水平即能够敏感地显示组织血流灌注特点,有助于睾丸扭转的诊断.     

踝关节的磁共振成像技术与临床应用探讨

目的 探讨踝关节的磁共振成像技术与临床应用价值.方法 42例病例(男33例,女9例)应用矩形表面线圈(GPFLX线圈)作患侧踝关节的T2加权像扫描、T1加权像扫描、脂压T2加权像扫描.扫描范围包括踝关节的矢状位、冠状位、轴位.结果 优片率达到90%以上.42例中,创伤性关节炎及创伤性关节炎术后改变6例,踝关节挫伤14例,跟腱撕裂9例,其他软组织损伤6例,踝关节退行性变4例,未见异常3例.结论 踝关节的磁共振检查,可以较好地显示踝关节的损伤程度和范围,为临床提供了有价值的影像学资料.     

Usefulness of Gd‐EOB‐DTPA‐enhanced MR imaging in the evaluation of simple steatosis and nonalcoholic steatohepatitis

Purpose:

To evaluate the usefulness of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA)‐enhanced MR imaging (EOB‐MRI) in differentiating between simple steatosis and nonalcoholic steatohepatitis (NASH), as compared with MR in‐phase/out‐of‐phase imaging. The correlations between the MR features and histological characteristics were preliminarily investigated.

Materials and Methods:

From April 2008 to October 2011, 25 patients (13 simple steatosis and 12 NASH) who underwent both EOB‐MRI and in‐phase/out‐of‐phase imaging were analyzed. The hepatobiliary‐phase enhancement ratio and signal intensity loss on opposed‐phase T1‐weighted images (fat fraction) were compared between the simple steatosis and NASH groups. In the simple steatosis and NASH groups, the correlations between enhancement ratio and histological grade/stage were explored. In the NASH group, fat fraction was correlated with the steatosis score.

Results:

The enhancement ratio in NASH was significantly lower than that in simple steatosis (P = 0.03). In the simple steatosis and NASH groups, the enhancement ratio was significantly correlated with the fibrosis stage (r = ?0.469, P = 0.018). Fat fraction in NASH was strongly correlated with the steatosis score (r = 0.728, P = 0.007).

Conclusion:

In simple steatosis and NASH, the hepatobiliary‐phase enhancement ratio of EOB‐MRI showed significant association with fibrosis stage, and may be a useful discriminating parameter compared with the fat fraction measured by in‐phase/out‐of‐phase imaging. J. Magn. Reson. Imaging 2012;37:1137–1143. © 2012 Wiley Periodicals, Inc.

     

MR直接关节造影在腕三角纤维软骨复合体损伤中的应用

目的 通过与腕关节镜结果对照,探讨MR直接关节造影在腕三角纤维软骨复合体(TFCC)损伤中的作用.方法 14例临床怀疑腕TFCC损伤的患者接受了常规MRI和MR直接关节造影,其中10例行腕关节镜检查.MR直接关节造影在腕拇长伸肌腱与伸指总肌腱间隙(相当于桡舟关节间隙)处进针,注入5～7 ml的钆喷替酸葡甲胺(0.1 mmol/L)混合液(0.3 ml钆喷替酸葡甲胺+100 ml生理盐水),与腕关节镜结果相对照,分析常规MRI和MR直接关节造影表现.结果 (1)14例中TFCC尺侧撕裂5例,桡侧撕裂4例,整体损伤5例(包括2例长期类风湿关节炎).(2)在脂肪抑制序列(STIR)及T2和T1WI序列上,损伤的TFCC表现为高信号或等信号,正常的低信号部分或完全消失,MR直接关节造影显示4例桡侧撕裂在腕TFCC的下尺桡关节和5例尺侧撕裂在尺骨茎突附着处可见不同程度的高信号对比剂聚集,5例整体损伤在下尺桡关节和尺骨茎突附着处均可见对比剂.MR直接关节造影表现与腕关节镜结果在损伤部位相符合,包括4例桡侧撕裂,3例尺侧撕裂和3例整体损伤.(3)14例腕TFCC损伤患者,8例伴有下尺桡关节半脱位,6例伴有尺桡骨骨挫伤,常规MRI和MR直接关节造影均可清晰地显示其滑膜反应和骨髓水肿等表现.结论 MR直接关节造影可以清晰地显示腕TFCC损伤,同时与常规MRI相结合能显示伴随的滑膜反应和骨髓水肿.     

髋关节MR造影在髋臼唇撕裂诊断中的应用

目的 探讨髋关节MR造影在髋臼唇撕裂诊断中的应用价值.方法 临床高度怀疑髋臼唇撕裂的15例20个髋关节在透视下行髋关节穿刺造影,采用SE T1WI加脂肪抑制技术,进行髋关节冠状面、矢状面、斜轴面及放射状位扫描.其中12例行关节镜检查.结果 在行髋关节镜检查的12例14个髋关节中,11例13个髋关节MR造影诊断为髋臼唇撕裂,与关节镜诊断相符;1例MR造影示正常,关节镜检查亦未发现髋臼唇撕裂.13个髋臼唇撕裂中位于前上象限12个髋关节,后上象限1个髋关节.在关节镜诊断髋臼唇撕裂的13个髋关节中,MR造影冠状面诊断髋臼唇撕裂3个髋关节,矢状面诊断10个髋关节,斜轴面及放射状位诊断髋臼唇撕裂均为13个髋关节.15例20个髋关节中有5例6个髋关节在后下象限有髋臼唇下沟表现.结论 MR髋关节造影是诊断髋臼唇撕裂的可靠方法,扫描方法应选择T1WI加脂肪抑制的矢状面及斜轴面或矢状面加放射状位.后下象限撕裂的诊断中应注意正常变异的存在.

Abstract：

Objective To investigate the application value of MR rthrography (MRA) in the diagnosis of acetabular labral tears. Methods Fifteen patients with a high degree of suspected acetabular labral tears received fluoroscope-guided injection of the contrast media into the hip joint ( hip arthrography) and fat-saturated spin-echo T1-weighted images were obtained in the coronal, sagittal, oblique-axial and radial planes. Hip arthroscopy was performed on 12 of them. Results Labral tears which were diagnosed in 11 patients by hip MRA were confirmed at hip arthroscopy. One patient showed no MRA indication of labral tear, also showed normal on arthroscopy. Tear in the anterior-superior quadrant 10 cases of 12 joints ( 12/13), posterior-superior quadrant 1 case of a joint (1/13). In 11 patients who underwent arthroscopy, hip MRA diagnosed 3 (3/13) joints labral tears in coronal planes, 10 (10/13) joints in sagittal planes and 13 (13/13) labral tears in axial-oblique and radial planes. In 15 patients with 20 hip joints, 5 cases 6 joints (6/20) with normal acetabular sublabral sulcus were performed. Conclusions MR arthrography of hip is a reliable method in the diagnosis of acetabular labral tears. Scanning method should be included fat-saturated spin-echo T1-weighted images in sagittal and oblique-axial planes or sagittal plus radial planes. The diagnosis of tor posterior-inferior quadrant should pay attention to the existence of a normal variation.     

Novel liver macromolecular MR contrast agent with a polypropylenimine diaminobutyl dendrimer core: comparison to the vascular MR contrast agent with the polyamidoamine dendrimer core.

As MRI contrast agents, more hydrophobic molecules reportedly accumulate in the liver and thus are potentially useful as liver MRI contrast agents. In this study, a generation-4 polypropylenimine diaminobutane dendrimer (DAB-Am64), which is expected to be more hydrophobic than the generation-4 polyamidoamine dendrimer (PAMAM-G4D), was used to synthesize a conjugate with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M) [DAB-Am64-(1B4M-Gd)(64)] for complexing Gd(III) ions. This DAB conjugate quickly accumulated in the liver and its characteristics were studied and compared with those of a PAMAM conjugate [PAMAM-G4D-(1B4M-Gd)(64)], which is known to be a useful vascular MRI contrast agent, in regard to its availability as a liver MRI contrast agent. DAB-Am64-(1B4M-Gd)(64) accumulated significantly more in the liver and less in blood than PAMAM-G4D-(1B4M-Gd)(64) (P < 0.001). Contrast-enhanced MRI with DAB-Am64-(1B4M-Gd)(64) was able to homogeneously enhance liver parenchyma and visualize both portal and hepatic veins of 0.5 mm diameter in mice. In conclusion, DAB-Am64-(1B4M-Gd)(64) is a good candidate for a liver MRI contrast agent.     

Sacro-iliac joint arthrography in low back pain: feasibility of MRI guidance

Objective: Evaluation of the feasibility of MR-guidance in sacro-iliac joint arthrography in patients whose low back pain is suspected to arise from the sacro-iliac joint (SIJ). Methods and patients: Twenty patients with low back pain underwent MR-guided sacro-iliac joint arthrography. Needles made from titanium (size 20 G, MDTech, USA) were used. For image guidance a 0.23T open-configuration C arm magnet (Proview, Marconi Medical Systems, USA) with special interventional hardware and software package (I-Path 200, Marconi Medical Systems) containing an MR compatible in-room console, large-screen (36″) display, optical navigator and accompanying software with dedicated sequences was used. No other image guidance modalities were used. Results: MR-guided SIJ arthrography was successfully performed in all twenty patients without complications. The optimal imaging sequence both for preoperative and intraoperative images was 3D-Gradient Echo sequence. The dispersal of the injected saline and anaesthetic could be determined inside the joint in all cases with heavily T2-weighted fast spin echo sequence. In the present study, 60% of the patients had significant reduction of pain after sacro-iliac joint arthrography and sacro-iliac joint was considered to be the source of patients low back pain in these patients. Conclusion: The present study shows that MR guidance with open configuration low field scanner is an accurate guiding method for sacro-iliac joint arthrography.     

Cerebral perfusion imaging using contrast-enhanced MRI

New developments in fast magnetic resonance imaging (MRI) have enabled imaging of cerebral haemodynamics. This article describes the theory behind perfusion imaging and provides an overview of the most commonly used MRI technique. Limitations of this technique are described, and the potential clinical applications are discussed, with particular attention to the role of perfusion imaging in the context of stroke and brain tumour.     

动态增强MRI在肺癌诊断中的应用

目的：探讨动态增强ＭＲＩ在肺癌诊断中的作用。材料和方法：前瞻性动态增强ＭＲＩ研究１２例原发支气管肺癌，６例良性肺内结节并与手术、病理对照；测量不同病变区（肿瘤、继发炎变、结核球、炎性假瘤和淋巴结）在静脉团注造影剂后不同时间的信号强度。结果：绝大多数肺癌在团注造影剂后明显强化，３～１０ｍｉｎ达到高峰，随后信号逐渐下降，而多数结核球主体无明显强化，动态曲线平坦。肺癌周围继发炎变增强程度高于瘤体，可将两者区分。炎性假瘤增强显著但边缘模糊，可见较长索条影。结论：动态增强ＭＲＩ能提供更多的信息，对肺癌的诊断、鉴别诊断和分期等均有帮助。     

Phantom and animal studies of a new hepatobiliary agent for MR imaging: comparison of Gd-DTPA-DeA with Gd-EOB-DTPA

PURPOSE: To investigate the characteristics of Gd-DTPA-DeA as a hepatobiliary contrast agent for MR imaging in comparison with those of Gd-EOB-DTPA. MATERIALS AND METHODS: We undertook phantom experiments to assess T1 relaxivity for Gd-DTPA-DeA, Gd-EOB-DTPA, and Gd-DTPA in human plasma. For Gd-DTPA-DeA and Gd-EOB-DTPA, we evaluated the contrast effect in rats using an SPGR sequence. The contrast ratios of liver and abdominal aorta were measured up to 21 minutes after intravenous administration of the agents. Visualization of the bile duct and renal pelvis was also assessed. RESULTS: In human plasma, T1 relaxivity was similar for Gd-DTPA-DeA and Gd-EOB-DTPA, and higher than those for Gd-DTPA. Whereas the contrast ratio of liver peaked about five minutes after the injection of Gd-EOB-DTPA and was followed by a subsequent decline, a continuous rise was shown for Gd-DTPA-DeA, resulting in a larger maximal contrast effect. Contrast ratios of the abdominal aorta were larger for Gd-DTPA-DeA. Biliary excretion was observed for both agents but occurred earlier with Gd-EOB-DTPA. While renal excretion was shown for all rats three minutes after the injection of Gd-EOB-DTPA, it was not observed for Gd-DTPA-DeA. CONCLUSION: Gd-DTPA-DeA may be used as a hepatobiliary contrast agent and shows different pharmacokinetics from Gd-EOB-DTPA.     

Assessment of myocardial viability in rats: Evaluation of a new method using superparamagnetic iron oxide nanoparticles and Gd-DOTA at high magnetic field.

The aim of this study was to detect salvageable peri-infarction myocardium by MRI in rats after infarction, using with a double contrast agent (CA) protocol at 7 Tesla. Intravascular superparamagnetic iron oxide (SPIO) nanoparticles and an extracellular paramagnetic CA (Gd-DOTA) were used to characterize the peri-infarction zone, which may recover function after reperfusion occurs. Infarcted areas measured from T1-weighted (T1-w) images post Gd-DOTA administration were overestimated compared to histological TTC staining (52% +/- 3% of LV surface area vs. 40% +/- 3%, P=0.03) or to T2-w images post SPIO administration (41% +/- 4%, P=0.04), whereas areas measured from T2-w images post SPIO administration were not significantly different from those measured histologically (P=0.7). Viable and nonviable myocardium portions of ischemically injured myocardium were enhanced after diffusive Gd-DOTA injection. The subsequent injection of vascular SPIO nanoparticles enables the discrimination of viable peri-infarction regions by specifically altering the signal of the still-vascularized myocardium.     

Whole-heart coronary magnetic resonance angiography at 3 Tesla in 5 minutes with slow infusion of Gd-BOPTA, a high-relaxivity clinical contrast agent.

T(1)-shortening contrast agents have been used to improve the depiction of coronary arteries with breath-hold magnetic resonance angiography (MRA). The spatial resolution and coverage are limited by the duration of the arterial phase of the contrast media passage. In this study we investigated the feasibility of acquiring free-breathing, whole-heart coronary MRA during slow infusion of the contrast media (0.3 ml/s) for prolonged blood signal enhancement time. Ultrashort TR (3 ms) and parallel data acquisition were used to allow the whole-heart MRA in approximately 5 min. A newly approved gadolinium (Gd)-based high T(1) relaxivity contrast agent, gadobenate dimeglumine ([Gd-BOPTA](2-)), was used and coronary MRA was performed on a whole-body 3 Tesla (T) system to improve the signal-to-noise ratio (SNR). Results from eight volunteers demonstrate that this coronary MRA method is capable of imaging the whole heart in 4.5 +/- 0.6 min. Major coronary arteries are well depicted with high SNR (42.4 +/- 12.5) and contrast-to-noise ratio (CNR; 27.1 +/- 7.6).     

Enhancement of liver parenchyma after injection of hepatocyte‐specific MRI contrast media: A comparison of gadoxetic acid and gadobenate dimeglumine

Purpose:

To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte‐specific contrast media.

Materials and Methods:

Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1‐weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs).

Results:

The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed‐imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46–2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%).

Conclusion:

In the delayed, hepatocyte‐specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine. J. Magn. Reson. Imaging 2010; 31: 356–364. © 2010 Wiley‐Liss, Inc.

     

A simple catheter-vessel model for MR assessment of drug distribution in arteries and optimization of catheter design for intraarterial infusion therapy

PURPOSE: To investigate the efficacy of a new catheter-vessel model for MRI to evaluate drug distribution and to optimize catheter design for intraarterial infusion therapy MATERIALS AND METHODS: The model consisted of a hepatic artery simulant tube through which blood simulant water flowed continuously and a water cistern. Catheters were inserted into the tube and a gadolinium contrast medium was injected at rates suitable for angiographic or computed tomographic evaluation and commensurate with the clinical drug infusion rate. Axial images of the tube were obtained with a 0.2-T scanner and gradient echo technique. Preliminary studies and catheter tests were conducted. The points at which drug and water were completely mixed were defined as the site with uniform enhancement nearest the catheter tip. RESULTS: Flip angle and gadolinium concentrations were optimized at 90 degrees, and at 62.5 and 500 mM for the high and low infusion rates, respectively. Drug distribution near the catheter tips was clearly visualized. The drug was mixed in shorter distances via the slit side-hole than the end- or side-hole catheters, and the smaller diametrical than the larger at either rate. CONCLUSION: This model appeared to be effective for evaluation of drug distribution and optimization of catheter design.     

Effects of iodinated contrast and field strength on gadolinium enhancement: implications for direct MR arthrography

PURPOSE: To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength. MATERIALS AND METHODS: Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed. RESULTS: Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images. CONCLUSION: Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.     

Relaxation enhancing properties of MnDPDP in human myocardium

PURPOSE: To assess magnitude and duration of changes in myocardial longitudinal relaxation rate (R1) in humans following infusion of the manganese (Mn) releasing contrast agent MnDPDP (Mn-dipyridoxyl-diphosphate). MATERIALS AND METHODS: Fifteen healthy volunteers were divided into three groups. After initial myocardial and liver R1 measurements using an inversion recovery (IR) turbo fast low-angle shot (FLASH) sequence at 1.5 Tesla, the groups were given different doses of intravenous MnDPDP: 5, 10 and 15 micromol/kg body weight, respectively, over 30 minutes. R1 measurements were then repeated at 1, 2, 4, 8, and 24 hours after the infusion ended. RESULTS: The left ventricular wall R1 prevalue was 0.98 second(-1) (+/-0.04). R1 increased on average (all 15 subjects) 0.41 second(-1) (+/-0.09). The increase was present one hour after the end of the infusion, remained relatively constant the next two hours, and then declined gradually. After 24 hours, there was still a moderate R1 elevation present, with an average R1-value of 1.16 (+/-0.05). There were only small differences in myocardial R1 responses between the three doses investigated, which was contrasted by a marked dose-response in liver tissue. CONCLUSION: MnDPDP gave a significant and prolonged rise in myocardial R1 even at a dose of 5 micromol/kg. The R1-values in the myocardium did not increase linearly with higher doses.