MR imaging of acute myocardial infarction in pigs using Gd-DTPA-labeled dextran.

Myocardial infarctions were induced in 12 pigs. In 6 pigs, dextran-(Gd-DTPA)15 (approximately 0.1 mmol Gd/kg b.w.) was injected i.v. 4 to 4.5 hours after coronary artery occlusion. ECG gated MR images were obtained repeatedly before (n = 4) and after (n = 6) contrast medium injection. Relaxation times in blood samples were measured repeatedly. The animals were sacrificed 2 hours after contrast medium administration. The hearts were excised, reexamined in the MR equipment and stained with triphenyltetrazolium chloride (TTC) in order to define areas of infarction. The remaining 6 pigs were sacrificed 6 hours after occlusion without administration of contrast medium. These hearts were only imaged ex vivo. In vivo, the infarctions could not be identified with or without dextran-(Gd-DTPA)15. Ex vivo, without contrast medium, the infarctions had an increased signal intensity, most pronounced in the T2-weighted images. Dextran-(Gd-DTPA)15 caused a prolonged, pronounced shortening of T1 and T2 in blood samples. The infarct demarcation improved in the T1-weighted images after injection of dextran-(Gd-DTPA)15, due to a moderate enhancement in normal myocardium and a stronger enhancement at the periphery of the infarctions, while the central parts of the infarctions were only weakly enhanced.     

The value of paramagnetic contrast agent gadolinium-DTPA in the diagnosis of pituitary adenomas

Summary The purpose of this study was to assess the role of MR imaging and the paramagnetic contrast agent Gadolinium-DTPA(Gd-DTPA) in the diagnosis of pituitary macroadenomas. 44 macroadenomas were examined with MRI before and after intravenous application of Gd-DTPA. Gd-DTPA produced excellent enhancement of solid adenoma. The best contrast between adenoma and surrounding structures could be gained on post-Gd T1-weighted images. Post-Gd images were equivalent to pre-Gd images in the evaluation of supra-and infrasellar extensions of macroadenomas. Post-Gd images had advantages in the evaluation of cavernous sinus invasion by adenoma. The difference in degree of contrast enhancement between adenoma and cavernous sinus facilitated the exact evaluation of lateral extension by adenoma in 18 cases. Almost equal degree of enhancement of both structures impaired tumor-sinus contrast in 2 cases. In the other 24 cases the tumor filled the cavernous sinus completely. It is our opinion that Gd-DTPA can be used on a widespread basis because of its excellent capability to highlight and delineate pituitary adenomas.     

Contrast-enhanced MRI with new biodegradable macromolecular Gd(III) complexes in tumor-bearing mice.

The structures of polydisulfide-based biodegradable macromolecular Gd(III) complexes were modified to improve their in vivo retention time and MRI contrast enhancement. Steric hindrance was introduced around the disulfide bonds to control their access to free thiols in order to alter the degradation rate of the copolymers. Two new macromolecular agents, (Gd-DTPA)-cystine copolymers (GDCP) and (Gd-DTPA)-cystine diethyl ester copolymers (GDCEP), were prepared. Both agents were readily degraded in vitro and in vivo by the disulfide-thiol exchange reaction, but at a slow rate. The introduction of COOH and COOEt groups slowed down the degradation of the copolymers in the incubation with 15 microM cysteine. Metabolic degradation products were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry in the urine samples from rats injected with the agents. The T(1) relaxivity (r(1)) was 5.43 mM(-1)s(-1) for GDCP, and 5.86 mM(-1)s(-1) for GDCEP, respectively, at 3T. MRI contrast enhancement of both agents was studied in nude mice bearing MDA-BM-231 human breast carcinoma xenografts, on a Siemens Trio 3T scanner. The modified agents resulted in more significant contrast enhancement in the blood pool and tumor periphery than (Gd-DTPA)-cystamine copolymers (GDCC) and a low-molecular-weight control agent, Gd-(DTPA-BMA), at a dose of 0.1 mmol-Gd/kg. The results demonstrate that the structural modification of the biodegradable macromolecular Gd(III) complexes resulted in a relatively slow degradation of the macromolecules and significantly improved in vivo contrast enhancement. The modified agents show promise for use in investigations of blood pool and cancer by contrast-enhanced (CE) MRI.     

MR imaging of hilar cholangiocarcinoma--comparative study with CT]

Magnetic resonance (MR) images of 18 cases of hilar cholangiocarcinoma were evaluated to compare the effectiveness of Gd-DTPA with that of high dose contrast enhancement computed tomography (HCE-CT) in detecting the primary tumor. The primary tumor was demonstrated as having slightly low intensity compared with liver parenchyma and high intensity compared with the dilated bile duct on T1 weighted images. In contrast, MRI using Gd-DTPA, which was carried out in five cases, revealed intense enhancement of the tumor. As the differentiation between cholangiocarcinoma and dilated bile duct was difficult, it was concluded that the use of Gd-DTPA improves the efficacy of MRI in diagnosing cholangiocarcinoma. Gd-DTPA was also effective in differentiating the growth pattern of the tumor: the infiltrating type was demonstrated as thickening of the wall of the bile duct, the polypoid type as a soft tissue mass in the bile duct. Contrast MRI study is effective for the detection of cholangiocarcinoma. It is also expected to be effective in the staging diagnosis of cholangiocarcinoma.     

Tissue distribution and magnetic resonance spin lattice relaxation effects of gadolinium-DTPA

Gadolinium-DTPA complex (Gd-DTPA) is a potential clinical magnetic resonance (MR) contrast agent that enhances images primarily by decreasing spin-lattice relaxation time (T1) in tissues in which it localizes. This study was designed to determine the immediate tissue distribution of intravenously administered Gd-DTPA in selected organs of interest as a function of administered dose and tissue Gd-DTPA concentration. An intravenous bolus of Gd-DTPA with a tracer quantity of Gd-153 was administered to three groups of rabbits at the following doses: 0.01 mM/kg (n = 6); 0.05 mM/kg (n = 6); 0.10 mM/kg (n = 6). A control group received sham injections. Five minutes after Gd-DTPA was administered, all animals were killed; samples of serum, lung, heart, kidney, liver, and spleen were analyzed in a 0.25 T MR spectrometer to measure T1, and then in a gamma well counter to determine tissue concentration of Gd-DTPA. Tissue distribution (per cent dose/tissue weight in g) at five minutes after injection was proportionally constant over the range of doses given. Tissue concentration varied linearly with injected dose (r greater than 0.98 for all tissues). Relaxation rate (1/T1) varied linearly with injected dose and with tissue Gd-DTPA concentration (r greater than 0.97 for all tissues). The order of tissue relaxation rate response to a given dose was: kidney greater than serum greater than lung greater than heart greater than liver greater than spleen. We conclude that because of its extracellular distribution and linear relaxation rate versus concentration relationship, Gd-DTPA enhancement in MR images may be a good marker of relative organ perfusion.     

In vitro evaluation of alternative oral contrast agents for MRI of the gastrointestinal tract

PURPOSE: In vitro evaluation of different materials as potential alternative oral contrast agents for small bowel MRI. MATERIALS AND METHODS: The T1 and T2 relaxation times of rose hip syrup, black currant extract, cocoa, iron-deferoxamine solution and a commonly used oral contrast material (1 mM Gd-DTPA) were determined in vitro at different concentrations on a 1.0 T clinical MR scanner. T1 values were obtained with an inversion prepared spoiled gradient echo sequence. T2 values were obtained using multiple echo sequences. Finally the materials were visualized on T1-, T2- and T2*-weighted MR images. RESULTS: The relaxation times of the undiluted rose hip syrup (T1=110+/-5 ms, T2=86+/-3 ms), black currant extract (T1=55+/-3 ms, T2=39+/-2 ms) and 5 mM iron-deferoxamine solution (T1=104+/-4 ms, T2=87+/-2 ms) were much shorter than for a 1mM Gd-DTPA solution (T1=180+/-8 ms, T2=168+/-5 ms). Dilution of black currant extract to 30% or a 3 mM iron-deferoxamine solution conducted to T1 relaxation times which are quite comparable to a 1 mM Gd-DTPA solution. Despite its much lower metal content an aqueous cocoa suspension (100 g/L) produced T2 relaxation times (T1=360+/-21 ms, T2=81+/-3 ms) more or less in the same range like the 5 mM iron-deferoxamine solution. Imaging of our in vitro model using clinical sequences allowed to anticipate the T1-, T2- and T2*-depiction of all used substances. Cocoa differed from all other materials with its low to moderate signal intensity on T1- and T2-weighted sequences. While all substances presented a linear 1/T1 and 1/T2 relationship towards concentration, rose hip syrup broke ranks with a disproportionately high increase of relaxation at higher concentrations. CONCLUSIONS: Rose hip syrup, black currant extract and iron-deferoxamine solution due to their positive T1 enhancement characteristics and drinkability appear to be valuable oral contrast agents for T1-weighted small bowel MRI. Cocoa with its differing relaxation and signal enhancement properties is a promising oral contrast agent but needs further clinical evaluation.     

MR-imaging with Gd-DTPA in carcinomas of tongue, oro- and hypopharynx

High-field MRI was performed in a series of 24 patients with squamous cell carcinomas of the tongue, oro- and hypopharynx. The value of contrast enhanced T1-weighted images in tumor staging was established prospectively. Non-contrast T1-weighted images did not provide sufficient tumor-delineation. Marked contrast enhancement produced by Gd-DTPA was observed in all carcinomas and in normal pharyngeal mucosa. In tumors of the tongue and upper pharynx clinical examination and ultrasound were equally sensitive as post-contrast MRI; in tumors of the lower pharynx the true tumor extension could be better assessed by contrast-enhanced MRI.     

脑实质内海绵状血管瘤MRI表现

目的分析脑实质内海绵状血管瘤的MRI表现，提高本病的诊断水平。方法回顾分析18例经临床及手术病理证实脑实质内海绵状血管瘤的MRI影像表现。结果18例共26个病灶，表现为T1WI等信号、高信号、混杂信号或环状高信号，T2WI低信号、均匀高信号或环状高信号，周围可见低信号环；大部分病灶无占位效应及周围水肿，所有病灶在梯度回波（GRE）序列上均可见到病灶边缘低信号环；Gd—DTPA增强扫描部分病灶强化。结论海绵状血管瘤MRI表现较为特异，MRI检查是诊断脑实质内海绵状血管瘤最为敏感的方法。     

MR imaging of the oropharynx and tongue: comparison of plain and Gd-DTPA studies

The effect of intravenously administered gadolinium-diethylene-triamine pentaacetic acid (Gd-DTPA) on signal intensity in comparison to plain noncontrast imaging was analyzed. Sixty-one patients with diseases of the oropharynx and tongue base were examined using multiplanar magnetic resonance (MR) imaging. The contrast medium Gd-DTPA was administered in 26 cases. Thirty-eight patients also underwent CT. Forty-one patients had surgery and pathological verification. Plain MR imaging was equal or superior to CT in all except one patient. Marked contrast enhancement produced by Gd-DTPA was observed in carcinomas, sarcomas, inflamed salivary glands, and in normal pharyngeal mucosa. The usefulness of Gd-DTPA may be increased by measuring the enhancement in signal intensity versus time to allow a better differentiation of histological features.     

肝脏占位性病变的磁共振成像研究：超顺磁性氧化铁与钆喷替酸葡甲胺的比较

通过与常用造影剂钆喷替酸葡甲胺（Gd-DTPA）的配对实验来评价新型造影剂超磁性氧化铁（SPIO）对有肝占位的检出率和定性诊断能力。材料和方法：53个病例132个肝占位首日行平扫及Gd-DTPA的动态增强扫描,次日行SPIO增强扫描,对照病理及临床随访证实结果,探讨各种占位SPIO增强扫描的强化特点,比较平扫联合Gd-DTPA动态增强扫描与平扫联合SPIO增强扫描的病灶检出率和定性诊断率。结果：SPIO增强扫描良性肝占位的信号随肝实质降低,而恶性肝占位的信号保持不变。平扫联合SPIO增强扫描的病灶检出率和定性诊断率较平扫联合Gd-DTPA增强扫描的略高,但统计学上相差不显著。结论：SPIO强化的原理、强化方式直至临床应用方法、特点与Gd-DTPA均完全不同,两者可相互补充和印证,当Gd-DTPA动态增强扫描定性诊断困难时应积极行SPIO增强扫描。     

Hepatic metastases: liposomal Gd-DTPA-enhanced MR imaging

Liposomal gadolinium diethylenetriaminepentaacetic acid (DTPA) encapsulated within 70- and 400-nm vesicles was tested as a contrast agent for magnetic resonance (MR) imaging of the liver in rats with hepatic metastases. Liposomal Gd-DTPA caused significant improvement in contrast between liver and tumor (P less than .005) on T1-weighted MR images. Smaller 70-nm liposomal Gd-DTPA vesicles caused greater contrast enhancement, reflecting the larger surface-area-to-volume ratio of the smaller vesicles. Liposomal Gd-DTPA-enhanced images permitted significant improvement in metastasis detection by five blinded radiologists (P less than .005). By comparison, free Gd-DTPA without liposomes caused a statistically significant reduction in contrast between tumor and liver and reduced lesion detection (P less than .01). Liposomal Gd-DTPA also resulted in sustained vascular enhancement for 1 hour after administration. The results suggest that paramagnetic liposomes may become a useful MR imaging contrast agent.     

Gd-DTPA in clinical MR of the brain: 2. Extraaxial lesions and normal structures

Fifteen patients with suspected extraaxial tumors were evaluated with MR before and after intravenous injection of Gadolinium-DTPA (Gd-DTPA). Meningiomas (7), neurinomas (4), chordomas (2), a previously irradiated dural metastasis, and a giant aneurysm were studied. All the lesions except the dural metastasis enhanced. In two patients with asymptomatic meningiomas, the use of Gd-DTPA with MR allowed definitive diagnosis of the lesions when the routine MR did not. Gd-DTPA also provided improved definition of intracranial tumor margins, produced differential enhancement of dura and nasopharyngeal mucosa from tumor, and caused enhancement of the choroid plexus, some venous structures, the pituitary gland, and its stalk. The enhancement of the pituitary suggests a role for Gd-DTPA in the diagnosis of microadenomas. Routine T2-weighted images without Gd-DTPA were useful in differentiating neurinomas from meningiomas. Judicious use of Gd-DTPA should improve the ability of MR to detect extraaxial lesions, delineate their extent, and characterize their perfusion.     

Magnetic resonance imaging of human cerebral infarction: Enhancement with Gd-DTPA

Summary Five patients (1 female and 4 males) with cerebral infarction of 4 h to 27 months duration were studied 9 times with magnetic resonance (MR) using Gd-DTPA. Spin-echo (SE) MR images (MRI) were obtained before and after the administration of Gd-DTPA, and correlative CT scans were performed on the same day. In 2 cases, 4 h and 27 months after the ictus, there was no enhancement with Gd-DTPA. There was faint enhancement in 2 cases with cerebral infarction of about 24h duration and obvious enhancement in all cases in the subacute stage. Compared with enhanced CT, MR using Gd-DTPA demonstrated more obvious enhancement of infarcted areas. MR enhancement using Gd-DTPA showed a gradual increase and the accumulated Gd-DTPA in infarcted areas slowly diffused to the periphery. MR enhancement with Gd-DTPA is similar to that of enhanced CT, but may be more sensitive in the detection of blood brain barrier breakdown.     

Magnetic Resonance Imaging of Acute Reperfused Myocardial Infarction: Intraindividual Comparison of ECIII-60 and Gd-DTPA in a Swine Model

Purpose To compare a necrosis-avid contrast agent (NACA) bis-Gd-DTPA-pamoic acid derivative (ECIII-60) after intracoronary delivery with an extracellular agent Gd-DTPA after intravenous injection on magnetic resonance imaging (MRI) in a swine model of acute reperfused myocardial infarction (MI). Methods Eight pigs underwent 90 min of transcatheter coronary balloon occlusion and 60 min of reperfusion. After intravenous injection of Gd-DTPA at a dose of 0.2 mmol/kg, all pigs were scanned with T1-weighted MRI until the delayed enhancement of MI disappeared. Then they were intracoronarily infused with ECIII-60 at 0.0025 mmol/kg and imaged for 5 hr. Signal intensity, infarct-over-normal contrast ratio and relative infarct size were quantified, compared, and correlated with the results of postmortem MRI and triphenyltetrazolium chloride (TTC) histochemical staining. Results A contrast ratio over 3.0 was induced by both Gd-DTPA and ECIII-60. However, while the delayed enhancement with Gd-DTPA virtually vanished in 1 hr, ECIII-60 at an 80× smaller dose depicted the MI accurately over 5 hr as proven by ex vivo MRI and TTC staining. Conclusion Both Gd-DTPA and ECIII-60 strongly enhanced acute MI. Comparing with fading contrast in a narrow time window with intravenous Gd-DTPA, intracoronary ECIII-60 persistently demarcated the acute MI, indicating a potential method for postprocedural assessment of myocardial viability after coronary interventions.     

Diagnostic value of MRI in tuberculous meningitis

In this study 15 patients with clinical findings and positive cerebrospinal fluid analyses for tuberculous meningitis were evaluated with magnetic resonance imaging (MRI). Tuberculous meningitis was diagnosed in 11 cases when thick meningeal enhancement was present after intravenous injection of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) in T1-weighted images. Intra-axial tuberculomas were present in 8 patients, 2 of whom had intra-axial tuberculomas without MRI evidence of meningitis. Tuberculomas showed ring or nodular enhancement in postcontrast T1-weighted images, but the most significant MR feature of intraparenchymal tuberculomas was the hypointense appearance of the lesions on T2-weighted images.Correspondence to: C. Tayfun     

Assessment of magnetic resonance contrast enhancement with Gd-DTPA: comparison with the uptake of Tc-99m-DTPA

To compare the contrast enhancement of Gd-DTPA with the uptake of 99mTc-DTPA, a study was carried out in two steps. In the first step, images comparable in terms of data acquisition time and thickness were obtained after computer processing, and processed images of 99mTc-DTPA and Gd-DTPA enhanced MRI were compared from the morphological aspect. In the second step, the arterial blood concentration of Gd-DTPA and the effect of T2 shortening on signal intensity were studied. It was concluded that Gd-DTPA enhanced MRI can provide functional information analogous to that obtained from radionuclide studies, possibly enabling semiquantitative analysis of contrast enhancement to be performed.     

Gadofluorine M增强磁共振成像在大鼠放射性脑损伤早期诊断中的实验研究

目的 探讨新型对比剂Gadofluorine M(Gf)在MRI早期诊断大鼠放射性脑损伤中的应用。方法 66只大鼠随机分为25、35、45、55和65 Gy组,各12只,对照组6只,X射线照射构建大鼠放射性脑损伤模型,照射后1~8周行MRI平扫及Gf增强扫描,每周1次。另取12只大鼠分为55及65 Gy组,每组6只,照后3~8周行钆喷酸葡胺(Gd-DTPA)增强及Gf增强扫描,每周1次。比较损伤显像时间、MRI参数和病理学改变评价放射损伤。结果 25及35 Gy放射组在观察2个月内MRI未发现异常信号改变,45、55及65 Gy组在放射后4~6周内,T1WI Gf增强扫描中逐渐出现强化改变,信号强度与对照组、25和35 Gy组差异有统计学意义(F =2.15, P ＜0.05),出现时间与剂量成反比(r=－0.62, P ＜0.05)。Gd-DTPA增强及Gf增强扫描对比结果显示,Gd-DTPA增强扫描未发现明显改变时Gf增强可见损伤改变,Gf增强信号强度较平扫及Gd-DTPA增强明显强化(F =2.74, P ＜0.01)。病理检查示65 Gy组病理学检查发现部分区域出现毛玻璃样变性,其余各组均未发现明显异常。结论 Gadofluorine M增强改变出现在病理改变之前,可用以早期发现放射性脑损伤,较常规扫描序列及Gd-DTPA增强扫描具有明显优势。     

Gd-DTPA增强的MRI在脑转移瘤诊断中的应用

目的探讨Gd-DTPA增强MRI对脑转移瘤的诊断价值及意义。方法回顾分析100例脑部转移瘤病人的平扫和增强MRI资料。结果100例脑转移瘤病人,平扫检出198个转移病灶,增强扫描检出354个转移病灶。平扫检出坏死囊变病灶85个,增强扫描检出183个。平扫检出病灶最小直径0.8cm,增强扫描检出病灶最小直径0.3cm,98例增强后可清晰显示病灶边界。16例没有症状的病人平扫7例未显示病灶,增强后均发现有转移病灶。结论Gd-DTPA是一种安全的MRI对比剂,增强MRI在显示脑转移瘤的大小、数目、边界、内部结构及位置等方面具有明显优势,可以帮助早期诊断。     

Enhanced MRI of breast cancer smaller than 3 cm]

Twenty-two patients with breast cancers were studied using magnetic resonance (MR) imaging with a cylindrical surface coil at 1.5 Tesla. All were examined with the FE sequence and Gd-DTPA as a contrast medium. These images were compared with micrographs of the specimens. All cancers were enhanced clearly, and demarcated margins or spiculations of the tumors were seen as clearly on MR images as on micrographs of the specimens. In 12 patients (9 carcinomas, 2 fibroadenomas and 1 benign phyllodes tumor), dynamic studies were performed after the intravenous injection of Gd-DTPA. All nine carcinomas showed enhancement characterized by a sudden increase in signal intensity on the order of 100% or more within the first 2 minutes after injection. Two fibroadenomas were enhanced slowly. Thirteen patients with breast cancers were examined with several sequences (FE, T1-weighed SE, T2-weighed SE and STIR) with or without Gd-DTPA. The most clearly delineated images of the tumors were those of FE images with Gd-DTPA enhancement. A phantom constituted of various concentrations of Gd-DTPA in 20% albumin solution was measured by signal intensities with T1-weighted SE sequence and FE sequence. The ratio of enhancement of the 20% albumin solution relative to the Gd-DTPA concentration was higher with the FE sequence than with the SE sequence. The sensitivity of the FE sequence to Gd-DTPA enhancement was 1.5 times that of the SE sequence under the usual concentration of Gd-DTPA.     

Low-dose gadobenate dimeglumine versus standard dose gadopentetate dimeglumine for contrast-enhanced magnetic resonance imaging of the liver: an intra-individual crossover comparison

RATIONALE AND OBJECTIVES: Gadobenate dimeglumine (Gd-BOPTA) has a two-fold higher T1 relaxivity compared with gadopentetate dimeglumine (Gd-DTPA) and can be used for both dynamic and delayed liver MRI. This intraindividual, crossover study was conducted to compare 0.05 mmol/kg Gd-BOPTA with 0.1 mmol/kg Gd-DTPA for liver MRI. MATERIALS AND METHODS: Forty-one patients underwent two identical MR examinations separated by >or= 72 hours. Precontrast T1-FLASH-2D and T2-TSE sequences and postcontrast T1-FLASH-2D sequences were acquired during the dynamic and delayed (1-2 hours) phases after each contrast injection. Images were evaluated on-site by two independent, blinded off-site readers in terms of confidence for lesion detection, lesion number, character and diagnosis, enhancement pattern, lesion-to-liver contrast, and benefit of dynamic and delayed scans. Additional on-site evaluation was performed of the overall diagnostic value of each agent. RESULTS: Superior diagnostic confidence was noted by on-site investigators and off-site assessors 1 and 2 for 6, 4 and 2 patients with Gd-BOPTA, and for 3, 1 and 2 patients with Gd-DTPA, respectively. No consistent differences were noted for other parameters on dynamic phase images whereas greater lesion-to-liver contrast was noted for more patients on delayed images after Gd-BOPTA. More correct diagnoses of histologically confirmed lesions (n = 26) were made with the complete Gd-BOPTA image set than with the complete Gd-DTPA set (reader 1: 68% vs. 59%; reader 2: 78% vs. 68%). The overall diagnostic value was considered superior after Gd-BOPTA in seven patients and after Gd-DTPA in one patient. CONCLUSION: The additional diagnostic information on delayed imaging, combined with the possibility to use a lower overall dose to obtain similar diagnostic information on dynamic imaging, offers a distinct clinical advantage for Gd-BOPTA for liver MRI.