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PubMed2005

Liver metastases in candidates for hepatic resection: comparison of helical CT and gadolinium- and SPIO-enhanced MR imaging.

PURPOSE: To prospectively compare accuracy of dynamic contrast material-enhanced thin-section multi-detector row helical computed tomography (CT), high-spatial-resolution three-dimensional (3D) dynamic gadolinium-enhanced magnetic resonance (MR) imaging, and superparamagnetic iron oxide (SPIO)-enhanced MR imaging with optimized gradient-echo (GRE) sequence for depiction of hepatic lesions; surgery and histologic analysis were the reference standard. MATERIALS AND METHODS: Local ethics committee approval was granted, and written informed consent was obtained. Fifty-eight patients (45 men, 13 women; age range, 47-82 years) with hepatic metastases were imaged with multi-detector row CT (3.2-mm section thickness), 3D dynamic gadolinium-enhanced MR imaging (2.5-mm effective section thickness), and SPIO-enhanced MR by using an optimized T2-weighted GRE sequence. Images were reviewed independently by two blinded observers who identified and localized lesions with a four-point confidence scale. Accuracy of each technique was measured with alternative free-response receiver operating characteristic analysis. Results were correlated with findings at surgery with intraoperative ultrasonography or histopathologic examination. Statistical differences among techniques for each observer were measured. RESULTS: Accuracy values for each observer for all metastases (n = 215) and 1.0-cm or smaller metastases (n = 80), respectively, follow: For CT, those for reader 1 were 0.82 and 0.65; for reader 2, 0.81 and 0.68. For gadolinium-enhanced MR imaging, those for reader 1 were 0.92 and 0.79; for reader 2, 0.90 and 0.76. For SPIO-enhanced MR imaging, those for reader 1 were 0.92 and 0.83; for reader 2, 0.92 and 0.81. For all metastases for both observers, there was no significant difference between MR techniques, but both were significantly more accurate than CT (P < .01). For metastases 1.0 cm or smaller and one observer, there was no significant difference between MR techniques, but both were more accurate than CT (P < .01); for the other observer, SPIO-enhanced MR imaging was more accurate than gadolinium-enhanced MR imaging (P < .05) and CT (P < .02), but there was no significant difference between gadolinium-enhanced MR imaging and CT (P = .2). CONCLUSION: Accuracy for gadolinium-enhanced MR imaging and SPIO-enhanced MR imaging was similar. Both techniques were significantly more accurate than CT.

Aged↗
PubMed1991

Renal lesion characterization with gadolinium-enhanced MR imaging: efficacy and safety in patients with renal insufficiency.

Five patients with renal insufficiency were studied with T1-weighted magnetic resonance (MR) imaging before and after intravenous administration of gadopentetate dimeglumine (0.1 mmol/kg) to characterize renal lesions that were detected with nonenhanced computed tomography (CT) and were considered indeterminate. Four patients demonstrated renal lesions that enhanced after gadolinium administration. A total of five lesions in these four patients were surgically resected and found to be renal cell carcinoma at pathologic examination. The fifth patient was spared surgery because a hyperattenuated lesion noted at nonenhanced CT did not enhance with intravenous gadolinium, indicating a benign cyst. Five incidentally occurring benign cysts removed at the time of nephrectomy in two of the patients did not demonstrate enhancement with gadolinium on MR images. Serial serum creatine levels were obtained before and after gadolinium administration in all patients; no changes were noted after gadolinium administration. Gadolinium-enhanced MR imaging is an effective method for characterizing renal lesions in patients with renal insufficiency. At the usual dosage, there appears to be no nephrotoxic reaction in these patients.

Aged↗
PubMed2006

Gadolinium does not blunt the cardiovascular responses at the onset of voluntary static exercise in cats: a predominant role of central command.

The cardiovascular adaptation at the onset of voluntary static exercise is controlled by the autonomic nervous system. Two neural mechanisms are responsible for the cardiovascular adaptation: one is central command descending from higher brain centers, and the other is a muscle mechanosensitive reflex from activation of mechanoreceptors in the contracting muscles. To examine which mechanism played a major role in producing the initial cardiovascular adaptation during static exercise, we studied the effect of intravenous administration of gadolinium (55 micromol/kg), a blocker of stretch-activated ion channels, on the increases in heart rate (HR) and mean arterial blood pressure (MAP) at the onset of voluntary static exercise (pressing a bar with a forelimb) in conscious cats. HR increased by 31 +/- 5 beats/min and MAP increased by 15 +/- 1 mmHg at the onset of voluntary static exercise. Gadolinium affected neither the baseline values nor the initial increases of HR and MAP at the onset of exercise, although the peak force applied to the bar tended to decrease to 65% of the control value before gadolinium. Furthermore, we examined the effect of gadolinium on the reflex responses in HR and MAP (18 +/- 7 beats/min and 30 +/- 6 mmHg, respectively) during passive mechanical stretch of a forelimb or hindlimb in anesthetized cats. Gadolinium significantly blunted the passive stretch-induced increases in HR and MAP, suggesting that gadolinium blocks the stretch-activated ion channels and thereby attenuates the reflex cardiovascular responses to passive mechanical stretch of a limb. We conclude that the initial cardiovascular adaptation at the onset of voluntary static exercise is predominantly induced by feedforward control of central command descending from higher brain centers but not by a muscle mechanoreflex.

Animals↗
PubMed2005

Synthesis and evaluation of gadolinium complexes based on PAMAM as MRI contrast agents.

Diethylenetriaminepentaacetic acid (DTPA) and pyridoxamine (PM) were incorporated into the amine groups on the surface of ammonia-core poly(amidoamine) dendrimers (PAMAM, Generation 2.0-5.0) to obtain dendritic ligands. These dendritic ligands were reacted with gadolinium chloride to yield the corresponding dendritic gadolinium (Gd) complexes. The dendritic ligands and their gadolinium complexes were characterized by(1)HNMR, IR, UV and elemental analysis. Relaxivity studies showed that the dendritic gadolinium complexes possessed higher relaxation effectiveness compared with the clinically used Gd-DTPA. After administration of the dendritic gadolinium complexes (0.09 mmol kg(-1) ) to rats, magnetic resonance imaging of the liver indicated that the dendritic gadolinium complexes containing pyridoxamine groups enhanced the contrast of the MR images of the liver, provided prolonged intravascular duration and produced highly contrasted visualization of blood vessels.

Animals↗
PubMed1998

Usefulness of optimized gadolinium-enhanced fast fluid-attenuated inversion recovery MR imaging in revealing lesions of the brain.

OBJECTIVE: The purpose of this study was to compare the contrast enhancement of lesions of the brain revealed by gadolinium-enhanced optimized fast fluid-attenuated inversion recovery (FLAIR) MR imaging with that of lesions on gadolinium-enhanced optimized T1-weighted spin-echo MR imaging. SUBJECTS AND METHODS: Using computer simulations, we optimized the fast FLAIR parameters (TR, TEeff, and inversion time) and the T1-weighted spin-echo parameters (TR and TE) to provide maximum difference in signal intensity between enhancing lesions of the brain and white matter. Seventy-six consecutive patients referred for single-dose gadolinium-enhanced MR imaging of the brain underwent both optimized techniques, which were matched for spatial resolution, bandwidth, and number of excitations. The gadolinium-enhanced fast FLAIR and T -weighted spin-echo MR images were evaluated independently by two observers for number and size of enhancing lesions and for the degree of gray-white matter differentiation. Contrast-to-noise ratios were measured for enhancing lesions 1.0 cm or larger in diameter using 8 x 8 pixel regions of interest in the enhancing lesions and normal white matter. RESULTS: The most revealing parameters for fast FLAIR MR imaging proved to be a TR of 1500 msec, an inversion time of 683 msec, and a TEeff of 16 msec. For T1-weighted spin-echo MR imaging, the optimized parameters were a TR of 550 msec and a TE of 16 msec. In 28 patients, we saw enhancing lesions of the brain with at least one MR imaging technique. More lesions were seen on the T1-weighted spin-echo sequence (n = 141) than on the fast FLAIR sequence (n = 94) (p < .03). Gray-white matter differentiation was significantly better on the fast FLAIR sequence (p < .001). Contrast-to-noise ratios of enhancing lesions were greater on the T1-weighted spin-echo sequence (p < .001). CONCLUSION: In this study, optimized gadolinium-enhanced conventional T1-weighted spin-echo MR imaging proved superior to gadolinium-enhanced fast FLAIR MR imaging in revealing lesions of the brain.

Adult↗
PubMed2000

Usefulness of gadolinium-enhanced MR imaging in the evaluation of the vascularity of scaphoid nonunions.

OBJECTIVE: The objective of this article is to identify the role of gadolinium-enhanced MR imaging in the preoperative evaluation of the vascular status of the proximal fragment in scaphoid nonunions. SUBJECTS AND METHODS: Thirty consecutive patients (27 men and three women; age range, 19-52 years; mean age, 28 years) with nonunion of the scaphoid were prospectively examined with unenhanced and gadolinium-enhanced MR imaging. MR images and surgical findings were classified in four groups according to the vascular status of the proximal fragment (normal bone, moderate ischemic bone, severe ischemic bone, and avascular necrosis). Sensitivity, specificity, and accuracy of unenhanced and gadolinium-enhanced MR studies were calculated. Surgical findings were used as the gold standard. The postoperative rate of union at 12 months was evaluated for each group. RESULTS: Unenhanced MR imaging showed a global sensitivity of 36%, specificity of 78%, and accuracy of 68% in the preoperative evaluation of the vascular status of the proximal fragment. Correlation with the surgical findings was not statistically significant (p < 0.149). Global sensitivity, specificity, and accuracy of gadolinium-enhanced MR imaging were 66%, 88%, and 83%, respectively. Correlation with the surgical findings was good (p < 0.0001). Gadolinium-enhanced sequences allowed accurate diagnosis and enabled the creation of prognostic groups having better correlation with surgical findings and postoperative results. CONCLUSION: Gadolinium-enhanced MR imaging is the most reliable imaging method for investigating the vascularity of the proximal pole in scaphoid nonunions.

Adult↗
PubMed2000

Accuracy of three-dimensional gadolinium-enhanced MR angiography in the assessment of extracranial carotid artery disease.

OBJECTIVE: The purpose of this study was to assess three-dimensional (3D) gadolinium-enhanced MR angiography, used alone or in association with duplex Doppler sonography, with a fast acquisition time (8 sec) for evaluating the extracranial carotid arteries. SUBJECTS AND METHODS: In this prospective study, 48 successive patients with carotid artery stenoses were examined with 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography. Of the 44 eligible patients, conventional angiography was available in 33 and duplex sonography in 27. We used the North American Symptomatic Carotid Endarterectomy Trial technique to quantify stenosis on all angiograms, and a 250 cm/sec threshold at duplex sonography to diagnose stenoses greater than 70%. Image quality of 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography was assessed, as well as sensitivity and specificity for each technique alone and in combination with duplex sonography. Conventional angiography was the gold standard. RESULTS: Three-dimensional gadolinium-enhanced MR angiography yielded good image quality in 90% of cases. When used alone, it yielded a sensitivity and a specificity of 94% and 85%, respectively, in screening stenoses greater than 70% (70-99%). When combined with duplex Doppler sonography, it provided a 100% sensitivity and specificity for detection of stenoses between 70% and 99% and would have obviated 61% of conventional angiography. In comparison, 3D time-of-flight MR angiography used alone yielded a sensitivity of 88% and a specificity of 94%. In combination with duplex Doppler sonography, its use would have obviated conventional angiography in 74% of cases. Three-dimensional gadolinium-enhanced MR angiography provided accurate results in the diagnosis of occlusions and ulcers and can visualize distant stenoses. CONCLUSION: Used alone, 3D gadolinium-enhanced MR angiography is not accurate enough to replace conventional angiography in the evaluation of extracranial carotid arteries. In association with duplex Doppler sonography, however, it is accurate and may obviate a significant number of conventional angiographic examinations.

Adult↗
PubMed2001

Detection of malignant hepatic tumors: comparison of gadolinium-and ferumoxide-enhanced MR imaging.

OBJECTIVE: The purpose of our study was to compare how well gadolinium-enhanced and ferumoxide-enhanced MR imaging reveal malignant hepatic tumors. SUBJECTS AND METHODS: Both gadolinium-enhanced and ferumoxide-enhanced MR imaging were separately performed in 53 patients with a total of 87 malignant hepatic tumors (57 hepatocellular carcinomas, 28 metastases, two cholangiocarcinomas). Thirty-one of the 53 patients had hepatic cirrhosis. Images were reviewed by three independent off-site observers. Observer performance was evaluated by means of sensitivity, specificity, and receiver operating characteristic curve analyses. RESULTS: Gadolinium-enhanced MR imaging outperformed ferumoxide-enhanced MR imaging in sensitivity (81% versus 62%, p < 0.01) for malignant-tumor detection. Specificity was comparable (94%) between the two types of MR imaging. Area under receiver operating characteristic curve (A(z)) value was significantly higher with gadolinium-enhanced MR imaging than with ferumoxide-enhanced MR imaging in patients overall (A(z) = 0.896 versus 0.805, p < 0.001), in patients with cirrhosis (A(z) = 0.907 versus 0.807, p < 0.001), and in patients without cirrhosis (A(z) = 0.899 versus 0.834, p < 0.01). The superiority was enhanced in the subset of patients with cirrhosis. CONCLUSION: Gadolinium-enhanced MR imaging outperforms ferumoxide-enhanced MR imaging in revealing malignant hepatic tumors. Gadolinium-enhanced MR imaging is recommended, particularly for patients with cirrhosis.

Aged↗
PubMed2002

Comparison of intraarterial and IV gadolinium-enhanced MR angiography with digital subtraction angiography for the detection of renal artery stenosis in pigs.

OBJECTIVE: Catheter-based intraarterial injections of gadolinium are useful during MR imaging-guided endovascular procedures to generate rapid vascular road maps. Using an animal model of renal artery stenosis, we tested the hypothesis that intraarterial gadolinium-enhanced MR angiography is as accurate as IV gadolinium-enhanced MR angiography and digital subtraction angiography (DSA). We also tested the hypothesis that intraarterial MR angiography uses less gadolinium than IV MR angiography. MATERIALS AND METHODS: We induced bilateral renal artery stenosis in five pigs. All pigs underwent comparative imaging with DSA, IV MR angiography, and aortic catheter-directed intraarterial MR angiography. For IV and intraarterial MR angiography, we used the same three-dimensional acquisition. We assessed differences in quantitative stenosis measurements among DSA, IV MR angiography, and intraarterial MR angiography using the Wilcoxon's signed rank test. RESULTS: Mean stenosis measurements (+/-SD) were as follows: DSA, 58% +/- 12%; IV MR angiography, 63% +/- 9.3%; and intraarterial MR angiography, 64% +/- 11%. There were no statistically significant differences in accuracy between DSA and IV MR angiography (p = 0.06), DSA and intraarterial MR angiography (p = 0.16), or IV and intraarterial MR angiography (p = 0.70). Intraarterial MR angiography used a mean gadolinium dose of 5.6 mL, compared with 9 mL for IV MR angiography. CONCLUSION: In swine, IV and intraarterial MR angiography have a similar accuracy for detecting renal artery stenosis. Intraarterial MR angiography uses smaller doses of injected gadolinium.

Angiography, Digital Subtraction↗
PubMed2002

[Fundamental study of DSA images using gadolinium contrast agent].

Most contrast agents used in digital subtraction angiography (DSA) are non-ionic iodinated contrast agents, which can cause severe side effects in patients with contraindications for iodine or allergic reactions to iodine. Therefore, DSA examinations using carbon dioxide gas or examinations done by magnetic resonance imaging (MRI) and ultrasound (US) were carried out in these patients. However, none of these examinations provided images as clear as those of DSA with an iodinated contrast agent. We experienced DSA examination using a gadolinium contrast agent in a patient contraindicated for iodine. The patient had undergone MRI examination with a gadolinium contrast agent previously without side effects. The characteristics of gadolinium and the iodinated contrast agent were compared, and the DSA images obtained clinically using these media were also evaluated. The signal-to-noise (SN) ratio of the gadolinium contrast agent was the highest at tube voltages of 70 to 80 kilovolts and improved slightly when the image intensifier (I.I.) entrance dose was greater than 300 microR (77.4 nC/kg). The dilution ratios of five iodinated contrast agents showed the same S/N value as the undiluted gadolinium contrast agent. Clinically, the images obtained showed a slight decrease in contrast but provided the data necessary to make a diagnosis and made it possible to obtain IVR without any side effects. DSA examinations using a gadolinium contrast agent have some benefit with low risk and are thought to be useful for patients contraindicated for iodine.

Angiography, Digital Subtraction↗
PubMed2000

[Magnetic resonance imaging of hepatic focal lesions: dynamic contrastographic evaluation with gadolinium versus reticulo-endothelial hepato-specific contrast media].

PURPOSE: To compare the potentials of AMI-25 (Endoren) to those of Gadolinium with the dynamic contrast-enhanced technique in the differential diagnosis of focal liver lesions. MATERIAL AND METHODS: Forty patients with at least one focal liver lesion diagnosed at US underwent MRI. We used a 1.5 T unit and employed single-shot half-Fourier T2-weighted FSE and spoiled gradient-echo T1-weighted sequences before and after Gadolinium injection. Multiple acquisitions were obtained during the arterial, portal and delayed phases. Twenty-four to 48 hours later T2*-weighted GRE and SPGR/90 degrees sequences were obtained after AMI-25 administration. In the characterization of solid lesions the gold standard was biopsy performed with a shearing needle; for the diagnosis of angiomas and of 11 metastatic lesions we considered follow-up and clinical data as important diagnostic elements. RESULTS: We found 12 hepatocarcinomas, 14 metastases, 4 cases of focal nodular hyperplasia (FNH), 4 adenomas and 6 angiomas. The diagnosis was correct and confirmed by the conventional examination in all cases but 2 adenomatous lesions and 2 angiomas. Precontrast studies showed slight hyperintensity in 2 of 4 cases of FNH, while the other 2 lesions appeared isointense and were therefore detected only on postcontrast images, where there was contrast agent uptake during the arterial phase and rapid washout. We found only one central scar hyperintense on T2- and hypointense on T1-weighted images. After AMI-25 administration all lesions appeared isointense to surrounding parenchyma on T2* GRE sequences. Adenomas were isointense in the precontrast phase and postcontrast 3 of them showed strong Gadolinium uptake and rapid washout. After AMI-25 two of the 4 lesions were hyperintense while the other two were isointense to the parenchyma. Four of 6 angiomas exhibited a typical pattern characterized by signal hyperintensity on T2-weighted sequences and on AMI-25-enhanced T1- and T2-weighted sequences. Two angiomas were supposed to be of malignant nature but histology showed the presence of a strong fibrotic component. Hepatocarcinomas could be detected on precontrast images. After Gadolinium administration 10 lesions appeared hyperintense in the arterial phase and 2 were hypointense. After AMI-25 all lesions exhibited homogeneous signal hyperintensity and appeared slightly bigger than on Gadolinium-enhanced images. The metastases were only partly demonstrated by MRI. Postgadolinium studies showed 13 lesions with hyperintense signal in the portal phase. AMI-25 administration detected 14 lesions that appeared slightly bigger than on Gadolinium-enhanced images. CONCLUSIONS: AMI-25 can help also in characterizing primary lesions with an atypical signal pattern after contrast agent administration thanks to its intrinsic capability of accumulating in benign lesions. However it remains difficult to characterize well differentiated hepatocarcinomas and adenomas. Finally, AMI-25 improves MR capabilities in detecting secondary lesions and possible satellite nodules.

Adenoma↗
PubMed2005

MRI evaluation of myometrial invasion by endometrial carcinoma. Comparison between fast-spin-echo T2w and coronal-FMPSPGR Gadolinium-Dota-enhanced sequences.

PURPOSE: The depth of myometrial invasion by endometrial carcinoma strongly affects the incidence of metastasis to regional nodes and influences the surgical strategies. The aim of this paper is to compare the results of FSE T2-w and Gadolinium-enhanced FMPSGR MR sequences in assessing the depth of myometrial invasion by endometrial cancer. MATERIALS AND METHODS: Forty-five women with histopathologically-proven endometrial carcinoma underwent preoperative MRI. Axial SE T1w, axial, sagittal and para-coronal FSE T2w and para-coronal Gadolinium-enhanced FMPSGR sequences were performed using a high field strength magnet (1.5T). Within one month of MR all patients underwent hysterectomy, and anatomical evaluation of the surgical specimen was done sectioning the uterus along the short axis. Based upon the results of the histological evaluation the results of the FSE T2w and Gadolinium-enhanced sequences were compared and the statistical difference between the results obtained was statistically evaluated. RESULTS: The histological evaluation showed intramucosal neoplasm in 11 patients, myometrial infiltration less than 50% in 31 patients, myometrial infiltration more than 50% in 12 patients and transmural cancer in 1 patient. Statistical evaluation showed that the FSE T2w sequence had a global sensitivity and specificity of 80.6% and 87.6%, respectively, with a mean Negative Predictive Value of 92.6% and a mean Positive Predictive Value of 86%. Gadolinium-enhanced FMPSPGR sequence had a global sensitivity and specificity of 90.6% and 93.3%, respectively, with a mean Negative Predictive Value of 96,3% and a mean Positive Predictive Value of 88%. The staging accuracy (chi2 test) on FMPSPGR images (95%) was higher than that on FSE T2w images (78%). CONCLUSIONS: In our experience Gadolinium-enhanced dynamic sequences increase the accuracy of MR imaging in diagnosing the depth of myometrial invasion. In particular they improve the visualisation of the inner myometrium, the so called subendometrial enhancing zone, whose disruption or changes are essential for diagnosing myometrial invasion. The major diagnostic advantages of the enhanced sequences were found in postmenopausal women, where visualisation of the junctional zone may be difficult in the T2w sequences. We believe that Gadolinium-enhanced dynamic sequences should be used whenever the diagnosis is unclear at FSE T2w sequences.

Adenocarcinoma↗
PubMed1990

Radiation effect of gadolinium-neutron capture reactions on the survival of Chinese hamster cells.

In gadolinium-neutron capture reactions, prompt gamma rays with an energy spectrum of up to 7 MeV, X-rays and electrons are released. We measured the effect of radiation as a result of capture reactions on cultured Chinese hamster cells. Cells in the medium containing 5000 ppm gadolinium were exposed to thermal neutrons from a nuclear reactor. The survival curve for those cells exhibited a shoulder in the low neutron fluence region. The survival curve for cells exposed to thermal neutrons in the absence of gadolinium was a simple exponential function. To obtain 10% survival levels, 5.4 x 10(12) neutrons/cm2 were required for cells irradiated in the absence of gadolinium, and 1.55 x 10(12) neutrons/cm2 for those irradiated in the presence of gadolinium. The therapeutic ratio in gadolinium-neutron capture therapy depends on the difference in 157Gd concentrations between the tumor and normal tissues. Thus, our current effort has been to develop a method of selectively delivering 157Gd to tumors.

Animals↗
PubMed1989

The role of gadolinium-DTPA in the evaluation of extracranial head and neck mass lesions.

Based on our experience with 28 patients, there is good evidence that gadolinium-enhanced MR will be useful in evaluation of skull base involvement, sinus involvement, or intracranial extension by neoplasms that involve the neck above the hard palate. This region has historically been a difficult area to image with any modality, because of the detailed anatomy and numerous important structures that traverse it. Gadolinium-enhanced MR should provide a valuable tool in the evaluation and management of these patients. The evidence that gadolinium is useful in staging of primary and nodal squamous cell carcinoma of the extracranial head and neck is less apparent. Areas where gadolinium may be helpful include size and extent of primary tumor and internal architecture of nodes that do not meet size criteria for malignant adenopathy. This is an area in which more experience is necessary, employing careful correlation with enhanced CT, unenhanced MR, and surgical specimens. Posttreatment follow-up of head and neck squamous cell lesions is a potential use for gadolinium, but this too is yet to be adequately studied. We have found that gadolinium enhancement provides no additional information important to the management of benign head and neck lesions over enhanced CT or unenhanced MR.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Assessment of breast cancer with dynamic gadolinium-enhanced MR imaging combined with magnetization transfer contrast using a newly developed breast surface coil for the supine position.

To assess the value of dynamic gadolinium-enhanced MR imaging combined with magnetization transfer contrast (MTC) of breast cancer by SPGR sequence, 15 patients with breast cancer were imaged in the supine position with the newly developed breast coil in a 1.5 Tesla imager. Dynamic gadolinium-enhanced MR imaging combined with MTC (10 cases) and conventional dynamic gadolinium-enhanced MR imaging (5 cases) were performed after the administration of Gd-DTPA (0.2 ml/kg). Sagittal images were obtained every 22 seconds during the first 264 seconds. Thus, a total of 15 images were obtained in each lesion. The signal intensity ratio (SIR) of lesion to mammary glarid was calculated for each image as follows: (SI lesion/SI mammary gland)/(SI (pre)lesion/SI (pre)mammary gland). Dynamic gadolinium-enhanced MR imaging with MTC always allowed better SIR at 88 seconds than conventional dynamic gadolinium-enhanced MR imaging after bolus injection (p < 0.01). Dynamic gadolinium-enhanced MR imaging with MTC improved detection of the boundary of the lesion and mammary gland.

Adult↗
PubMed1998

Current uses of gadolinium chelates for clinical magnetic resonance imaging examination of the liver.

The use of gadolinium chelates has become an integral part of magnetic resonance imaging (MRI) of the liver and extrahepatic abdomen. Although liver specific contrast agents are now available, gadolinium chelates continue to offer significant advantages for abdominal MRI. The gadolinium chelates uniquely provide important information about tumor perfusion that is key in our assessment of liver masses. These paramagnetic contrast agents assist with liver lesion detection, characterization, and in establishing the volume of viable perfused tumor. Gadolinium chelates are equally important for MRI of the extrahepatic abdomen. The interstitial accumulation of these agents within peritoneal, omental, and gastrointestinal tumor produces marked enhancement and is key in accurate tumor staging. Depiction of lesions within solid visceral organs such as the pancreas, kidneys, and spleen is also improved following gadolinium injection. The versatility of this workhorse contrast agent assures that gadolinium chelates will continue to occupy a central role in any busy abdominal MRI practice.

Chelating Agents↗
PubMed2006

Population pharmacokinetics and bioavailability of motexafin gadolinium (Xcytrin) in CD1 mice following intravenous and intraperitoneal injection.

Motexafin gadolinium (Xcytrin) is an expanded porphyrin macrocyclic compound under development for the treatment of several types of cancer. Currently clinical trials and non-clinical pharmacology and toxicology studies are ongoing. The goals of this open label, four arm, non-crossover bioavailability study were to explore motexafin gadolinium pharmacokinetics, determine the i.p. bioavailability, and define a pharmacokinetic model suitable for descriptive and predictive use. Mice received one or seven daily i.v. or i.p. injections (40 mg/kg) then blood samples were collected and analyzed. Plasma concentration data were modelled using population pharmacokinetic methods and a two compartment model was the most appropriate model. The stability and predictive performance of the model were evaluated using bootstrap procedures. The accuracy of the predicted concentrations was 8.3%. Motexafin gadolinium was rapidly cleared from the plasma and although T(1/2beta) was 12.9 h there was no accumulation following seven doses. The i.p. bioavailability was 87.4% and higher plasma concentrations were sustainable for a longer period with i.p. dosing. V(c) was larger than the blood volume and the tissue compartment volume was 38% of V(c), suggesting motexafin gadolinium was not widely distributed into less well perfused tissues. The pharmacokinetic profile in this study was similar to that in oncology patients administered multiple doses of motexafin gadolinium. The unbiased model yields reliable parameter estimates and insight into the pharmacokinetics of motexafin gadolinium in mice, is suitable for both descriptive and predictive purposes, and is a valuable tool in the planning, analysis, and interpretation of pharmacology and toxicology studies in mice.

Animals↗
PubMed1995

Abdominal aortic aneurysms: assessment with gadolinium-enhanced time-of-flight coronal MR angiography (MRA).

A prospective study was performed to evaluate the efficacy of a gadolinium-chelate-enhanced MR angiography (MRA) using a coronal acquisition in the preoperative assessment of aneurysms of the abdominal aorta (AAA). Twenty patients with AAA were explored with MR using a two-dimensional (2D) time-of-flight MRA technique with a coronal acquisition, before and after intravenous administration of 0.1 mmol/kg of a gadolinium-chelate. Gadolinium-chelate-enhanced MRA with a coronal acquisition decreased deleterious saturation effects within aorta and iliac arteries in 16 of 20 patients (80%) and improved the overall quality of the images of the upper and lower parts of the AAA (i.e. extent of the aneurysm). Furthermore, gadolinium-chelate-enhanced MRA with a coronal acquisition allowed a better differentiation between slow flow and mural thrombus. Gadolinium-chelate-enhanced MRA had a sensitivity of 100% and a specificity of 96% for evaluation of renal artery involvement, and a sensitivity of 93% and a specificity of 100% for iliac artery involvement. The results of this study show that gadolinium-chelate-enhanced MRA obtained with a coronal acquisition is efficacious for the preoperative assessment of AAA.

Aorta, Abdominal↗