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PubMed1996

Free gadolinium and gadodiamide, a gadolinium chelate used in magnetic resonance imaging: evaluation of their in vitro effects on human neutrophil viability.

Gadolinium (Gd3+) is known to be the most paramagnetic ion but is also a very toxic cation often used in pharmacology as a putative stretch-activated channel inhibitor. Gadodiamide, a nonionic Gd3+ chelate, is frequently injected i.v. into magnetic resonance imaging (MRI) to enhance contrast. To determine whether this complex is innocuous in humans, a cytotoxicity study was performed on artificially stimulated human neutrophils (HN). HN were incubated with gadodiamide and with free Gd3+ (GdCl3). The purpose of the study was to estimate possible cell damage after incubation, and to validate further trials based on stimulated cellular models. Measurement of lactate dehydrogenase (LDH) release and the Trypan blue exclusion test were used to assess viability. HN were separated from the blood of healthy volunteers and stimulated by phorbol 12-myristate 13-acetate, a pharmacological reactive which induces protein kinase C activation, superoxide generation, and degranulation by leukotcytes. This study demonstrated that an acellular model is necessary to interpret LDH results. In addition, the experimental conditions of the study demonstrated GdCl3 toxicity on HN viability, while gadodiamide was not harmful.

Analysis of Variance↗
PubMed2006

Delivery of gadolinium-labeled nanoparticles to the sentinel lymph node: comparison of the sentinel node visualization and estimations of intra-nodal gadolinium concentration by the magnetic resonance imaging.

Sentinel node imaging is commonly performed prior to surgery for breast cancer and melanoma. While current methods are based on radio-lymphoscintigraphy, MR lymphangiography (MRL) offers the benefits of better spatial resolution without ionizing radiation. However, the optimal nanoparticle for imaging the sentinel nodes remains unclear. Gadolinium-labeled (Gd) contrast agents ranging in diameter from <1 to 12 nm were evaluated to determine which size provides the most rapid and most concentrated delivery of contrast agent to the lymph nodes in a mouse model of lymphatic metastases. Specifically, PAMAM-G2, -G4, -G6 and -G8, and DAB-G5 Gd-dendrimer agents, as well as Gadomer-17 and Gd-DTPA, were compared. Among these agents, the G6 Gd dendrimer depicted the lymphatics and lymph nodes with the highest peak concentrations and this occurred 24-36 min post-injection (p<0.01; all except G8). Based on ex vivo concentration phantoms, high accumulations of Gd(III) ions occurred within lymph nodes (1.7-4.4 mM Gd/270-680 ppm Gd) with high target to background ratios (>100). These concentrations are sufficient to contemplate the use of Gd-neutron capture therapy of regional lymph nodes. Thus, when injected interstitially, the PAMAM-G6 Gd dendrimer not only provides excellent opacification of sentinel lymph nodes, but also provides the potential for targeted therapy of sentinel lymph nodes.

Animals↗
PubMed2006

Delayed gadolinium-enhanced magnetic resonance imaging (dGEMRIC) of hip joint cartilage: better cartilage delineation after intra-articular than intravenous gadolinium injection.

PURPOSE: To investigate and compare delayed gadolinium (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) in the hip joint using intravenous (i.v.) or ultrasound-guided intra-articular (i.a.) Gd-DTPA injection. MATERIAL AND METHODS: In 10 patients (50% males, mean age 58 years) with clinical and radiographic hip osteoarthritis (OA; Kellgren score II-III), MRI of the hip was performed twice on a clinical 1.5T MR scanner: On day 1, before and 90-180 min after 0.3 mmol/kg body weight i.v. Gd-DTPA and, on day 8, 90-180 min after ultrasound-guided i.a. injection of a 4 mmol/l Gd-DTPA solution. Coronal STIR, coronal T1 fat-saturated spin-echo, and a cartilage-sensitive gradient-echo sequence (3D T1 SPGR) in the sagittal plane were applied. RESULTS Both the post-i.v. and post-i.a. Gd-DTPA images showed significantly higher signal-to-noise (SNR) and contrast-to-noise (CNR) in the joint cartilage compared to the non-enhanced images (P < 0.002). I.a. Gd-DTPA provided significantly higher SNR and CNR compared to i.v. Gd-DTPA (P < 0.01). Furthermore, a better delineation of the cartilage in the synovial/cartilage zone and of the chondral/subchondral border was observed. CONCLUSION: The dGEMRIC MRI method markedly improved delineation of hip joint cartilage compared to non-enhanced MRI. The i.a. Gd-DTPA provided the best cartilage delineation. dGEMRIC is a clinically applicable MRI method that may improve identification of early subtle cartilage damage and the accuracy of volume measurements of hip joint cartilage.

Adult↗
PubMed1988

In vitro interactions of gadolinium DOTA meglumine and gadolinium DTPA meglumine on hemostasis.

The interactions of two gadolinium complexes (Gd-DOTA meglumine and Gd-DTPA meglumine) with hemostatic function have been analyzed using: (1) coagulation reactions (extrinsic and intrinsic pathways and fibrinoformation) and (2) platelet function investigations (aggregation, release of Ca++ and ATP after stimulation with collagen 2.5 micrograms/mL). The data obtained with Gd-DTPA meglumine (Mgl) exhibited a significant increase of the intrinsic coagulation pathway and a delay in fibrinoformation, although there is no alteration of the effect of thrombin on fibrinogen (fibrinopeptid A determinations). Platelet aggregation and release are moderately modified. In contrast, Gd-DOTA Mgl exerts no effect on the coagulation system and only minor effects on platelet functions. It is suggested that at least one mechanism involves the complexation of ionized calcium because Gd-DTPA Mgl and Gd-DOTA Mgl complex, respectively, 45% and 23% of ionized calcium in plasma. However, other mechanisms such as an alteration of fibrin polymerization are not unlikely.

Contrast Media↗
PubMed1995

Comparison of gadolinium Cy2DOTA, a new hepatobiliary agent, and gadolinium HP-DO3A, an extracellular agent, in healthy liver and metastatic disease.

RATIONALE AND OBJECTIVES: A new gadolinium (Gd) chelate with preferential hepatobiliary uptake, Gd Cy2DOTA, was compared in two animal species with Gd HP-DO3A (gadoteridol), a clinically approved contrast agent with extracellular distribution. Liver enhancement was evaluated for these two contrast agents using magnetic resonance imaging, whereas an experimental model of metastatic disease was used to evaluate the agents' efficacy for liver-lesion delineation. METHODS: The two agents were compared in four healthy Rhesus monkeys (eight studies) and five New Zealand White rabbits with implanted VX-2 liver tumors (ten studies). The contrast dose was 0.1 mmol/kg, with the agents given in random order and at least 72 hours between contrast injections. Breathhold T1-weighted spin echo scans were obtained at 1.5 tesla (T) before and after contrast was administered. Postcontrast scans were obtained 1 to 90 minutes after injection in the monkeys and 1 to 240 minutes after injection in the rabbits. RESULTS: Prolonged hepatic enhancement, superior in degree to that with Gd HP-DO3A, was noted in both monkeys and rabbits after injection of Gd Cy2DOTA. Two minutes after contrast, liver SI was 1.94 +/- 0.05 with Gd Cy2DOTA compared with 1.51 +/- 0.05 with Gd HP-DO3A in monkeys. Sixty minutes after contrast, liver SI was 1.60 +/- 0.09 compared with 1.20 +/- 0.02. The difference between agents was significant at all times from 2 to 60 minutes after contrast injection (P < 0.01). Excretion of contrast into the gall bladder was observed in both animal species with Gd Cy2DOTA but not with Gd HP-DO3A. The maximum improvement in lesion conspicuity (rabbit) occurred 45 minutes after injection of Gd Cy2DOTA and 5 minutes after injection of Gd HP-DO3A. Sixty minutes after injection, liver-lesion contrast was 246 +/- 61 with Gd Cy2DOTA and 106 +/- 28 with Gd HP-DO3A, with a significant difference (P < 0.02). CONCLUSIONS: Gd Cy2DOTA provides greater enhancement of the liver parenchyma on immediate and delayed magnetic resonance scans than does Gd HP-DO3A. On delayed scans, Gd Cy2DOTA provides superior delineation of metastatic liver lesions.

Adenocarcinoma↗
PubMed2005

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy?

OBJECTIVE: Gadolinium neutron capture therapy (GdNCT) is a potential treatment for malignant tumors based on two steps: (1) injection of a tumor-specific (157)Gd compound; (2) tumor irradiation with thermal neutrons. The GdNC reaction can induce cell death provided that Gd is proximate to DNA. Here, we studied the nuclear uptake of Gd by glioblastoma (GBM) tumor cells after treatment with two Gd compounds commonly used for magnetic resonance imaging, to evaluate their potential as GdNCT agents. METHODS: Using synchrotron X-ray spectromicroscopy, we analyzed the Gd distribution at the subcellular level in: (1) human cultured GBM cells exposed to Gd-DTPA or Gd-DOTA for 0-72 hours; (2) intracerebrally implanted C6 glioma tumors in rats injected with one or two doses of Gd-DOTA, and (3) tumor samples from GBM patients injected with Gd-DTPA. RESULTS: In cell cultures, Gd-DTPA and Gd-DOTA were found in 84% and 56% of the cell nuclei, respectively. In rat tumors, Gd penetrated the nuclei of 47% and 85% of the tumor cells, after single and double injection of Gd-DOTA, respectively. In contrast, in human GBM tumors 6.1% of the cell nuclei contained Gd-DTPA. DISCUSSION: Efficacy of Gd-DTPA and Gd-DOTA as GdNCT agents is predicted to be low, due to the insufficient number of tumor cell nuclei incorporating Gd. Although multiple administration schedules in vivo might induce Gd penetration into more tumor cell nuclei, a search for new Gd compounds with higher nuclear affinity is warranted before planning GdNCT in animal models or clinical trials.

Animals↗
PubMed2001

Gadolinium in human glioblastoma cells for gadolinium neutron capture therapy.

157Gd is a potential agent for neutron capture cancer therapy (GdNCT). We directly observed the microdistribution of Gd in cultured human glioblastoma cells exposed to Gd-diethylenetriaminepentaacetic acid (Gd-DTPA). We demonstrated, with three independent techniques, that Gd-DTPA penetrates the plasma membrane, and we observed no deleterious effect on cell survival. A systematic microchemical analysis revealed a higher Gd accumulation in cell nuclei compared with cytoplasm. This is significant for prospective GdNCT because the proximity of Gd to DNA increases the cell-killing potential of the short-range, high-energy electrons emitted during the neutron capture reaction. We also exposed Gd-containing cells to thermal neutrons and demonstrated the GdNC reaction effectiveness in inducing cell death. These results in vitro stimulated in vivo Gd-DTPA uptake studies, currently underway, in human glioblastoma patients.

Cell Death↗
PubMed2005

Gadolinium and neodymium citrates: evidence for weak ferromagnetic exchange between gadolinium(III) cations.

A new lanthanide citrate motif of general formula [Ln(Hcit)(H2O)2.H2O]n, where Ln = Gd (1) and Nd (2) and Hcit3- = C(OH)(COO-)(CH2COO-)2, has been synthesized hydrothermally from Ln2O3 and citric acid at 100 degrees C and characterized by elemental analysis, IR, TG-DTA, single-crystal X-ray diffraction, and magnetic measurements. The structures can be seen as "ladder chains" along the a axis, with dinuclear Ln2O2 units serving as "steps" and R-COO groups as "uprights", which are connected by H bonds. The magnetic susceptibility between 2 and 300 K and the magnetization at 2 K, as a function of magnetic field between 0 and 5 T, were measured for both compounds. By modeling the magnetic behavior of the Gd compound with a dinuclear Hamiltonian [symbol: see text](S) = gmu(B)(S(A) + S(B))B(o) - J(o)S(A)S(B) (S(A) = S(B) = 7/2), a ferromagnetic exchange interaction J(o) = 0.039 cm(-1) was evaluated between Gd ions situated at d(o) = 4.321 angstroms in dinuclear units bridged by two symmetry-related tridentate carboxylate oxygens. The EPR spectrum of the Gd compound is discussed. The temperature dependence of the susceptibility of the Nd compound is caused by the depopulation of the excited crystal-field levels when the temperature decreases. The magnetic-field dependence of the magnetization of 2 is attributed to the ground-state Kramers' doublet populated at 2 K. The g factor of this ground-state doublet is calculated from the data and compared with values for other compounds reported in the literature.

Cations↗
PubMed1979

Crystal structures of hen egg-white lysozyme complexes with gadolinium(III) and gadolinium(III)-N-acetyl-D-glucosamine.

Analysis at 0.25 nm resolution of the crystal structures of lysozyme-Gd(III) and lysozyme-Gd(III)-N-acetyl-D-glucosamine (GlcNac), prepared by diffusion methods, show that there are two main binding positions for Gd(III), one of which is close to glutamic acid-35 and the other close to aspartic acid-52. The two sites are 0.36 nm part. There is no evidence for the weak binding of Gd(III) to any of the eight other carboxy groups of lysozyme. In the presence of Gd(III), the binding of GlcNac is similar to that observed for the binding of the beta-anomer in subsite C. There are numerous small conformational changes in the protein on binding (Gd(III) and the sugar, and these have been quantified to a first approximation by real-space refinement. These changes are similar in both structures, and involve, among other small movements, shifts of one of the disulphide bridges by up to 0.05 nm. The movement of residues 70--74 observed in the binary complex of lysozyme-GlcNac [Perkins, Johnson, Machin & Phillips (1978) Biochem. J. 173-617] is not observed in the ternary complex of lysozyme-Gd(III)-GlcNac. The nature of the lysozyme-Gd(III) complex is discussed in the light of evidence from other crystallographic studies and n.m.r. solution studies. Preliminary findings for a lysozyme-Gd(III) complex prepared by co-crystallization methods are reported.

Acetylglucosamine↗
PubMedDate not supplied

Prediction of q-values and conformations of gadolinium chelates for magnetic resonance imaging.

For gadolinium chelates, we determined that there is a linear correlation between calculated solvent-accessible surface area and q-value, the number of rapidly exchanging water molecules directly bound to the gadolinium ion. A calibration curve was developed to predict q-value based on the solvent-accessible surface area of gadolinium. This predictive method was validated with the following gadolinium crystal structures: (ethylenediaminetetraacetic acid)-gadolinium(III) [Gd(EDTA)] [Templeton, L. K., Templeton, D. H., Zalkin, A., and Ruben, H. W. (1982) Anomalous Scattering by Praseodymium, Samarium, and Gadolinium and Structures of their Thylenediaminetetraacetate (EDTA) Salts. Acta Crystallogr., Sect. B 38, 2155], (1,4,7,10-tetraazacyclododecane-N,N',N' ',N' "-tetraacetic acid)-gadolinium(III) [Gd(DOTA)] [Dubost, J.-P., Leger, J.-M., Langlois, M.-H., Meyer, D., and Schaefer, M. (1991) Structure of a Magnetic Resonance Imaging Agent - The Gadolinium-DOTA Complex C(16)H(24)N(4)O(8)NaGd, 5H(2)O. C. R. Acad. Sci., Ser. 2 312, 349], (diethylenetriaminepentaacetic acid)-gadolinium(III) [Gd(DTPA)] [Stezowski, J. J., and Hoard, J. L. (1984) Heavy Metal Ionophores - Correlations Among Structural Parameters of Complexed Nonpeptide Polyamino Acids. Isr. J. Chem. 24, 323], (diethylenepenta-acetato)-gadolinium(III) [Gd(DTPA-BEA)] [Smith, P. H., Brainard, J. R., Morris, D. E., Jarvinen, G. D., and Ryan, R. R. (1989) Solution and Solid-State Characterization of Europium and Gadolinium Schiff-Base Complexes and Assessment of their Potential as Contrast Agents in Magnetic Resonance Imaging. J. Am. Chem. Soc. 111, 7437], and (1,7,13-triaza-4,10, 16-trioxacyclo-octadecane-N,N',N' '-triacetato)-gadolinium(III) [Gd(TTTA)] [Chen, D., Squattrito, P. J., Martell, A. E., and Clearfield, A. (1990) Synthesis and Crystal Structure of a 9-Coordinate Gadolinium(III) Complex of 1,7,13-Triaza-4,10, 16-Trioxacyclooctadecane-N,N',N' '-Tri-Acetic Acid. Inorg. Chem. 29, 4366]. Predicted q-values were in complete agreement with experimentally determined q-values. A genetic algorithm-based conformational search method was developed to generate valid 3D models for gadolinium chelates. The method was successfully tested on the following gadolinium chelates: Gd(EDTA) (Templeton et al., 1982), Gd(DOTA) (Dubost et al., 1991), Gd(DTPA-BEA) (Smith et al., 1989), Gd(TTTA) (Chen et al., 1990), Gd(triethylene glycol) [Rogers, R. D., Voss, E. J., and Etzenhouser, R. D. (1988) F-Element Crown Ether Complexes. 17. Synthetic and Structural Survey of Lanthanide Chloride Tiethylene Glycol Complexes. Inorg. Chem. 27, 533], and Gd(tetraethylene glycol) [Rogers, R. D., Etzenhouser, R. D., Murdoch, J. S., and Reyes, E. (1991) Macrocycle Complexation Chemistry. 35. Survey of the Complexation of the Open-Chain 15-Crown-5 Analogue tetraethylene Glycol with the Lanthanide Chlorides. Inorg. Chem. 30, 1445].

Algorithms↗
PubMedDate not supplied

Use of a mixture of gadolinium and iodinated contrast for angiography.

The purpose of this study was to determine if the image quality of gadolinium digital subtraction angiography (DSA) can be improved by the addition of small quantities of iodinated contrast to gadolinium. The optical density (OD) of a mixture of four parts gadolinium-based contrast to one part iodinated contrast was measured through a phantom study and compared to that of full-strength gadolinium, full strength iodinated contrast, and a 20% solution of iodinated contrast. We also compared the clinical image quality of the mixture of gadolinium-based contrast and iodinated contrast relative to full-strength gadolinium and full strength iodinated contrast during DSA. The DSA image quality of the gadolinium-iodinated contrast mixture was significantly improved relative to images obtained with full-strength gadolinium and compared favorably to that obtained with full-strength iodinated contrast. The phantom data showed that the OD of the gadolinium-iodinated contrast mixture was much greater than that of full strength gadolinium and the 20% iodinated contrast solution. The increase in OD was greater than that expected from a simple additive effect of the OD of the contrast agents. Adding a small amount of iodinated contrast to gadolinium results in a significant improvement in the radiographic density and DSA image quality of gadolinium. This simple technique appears to overcome one of the major limitations of gadolinium-based angiography-poor radiographic density-while continuing to minimize the volume of administered iodinated contrast.

Aged↗
PubMed2006

Gadolinium is detectable within the tissue of patients with nephrogenic systemic fibrosis.

BACKGROUND: Nephrogenic systemic fibrosis (NSF) is a disease of unknown etiology that affects a subset of patients with renal insufficiency. Recent publications suggested an association between exposure to gadolinium-containing contrast agents and subsequent development of NSF. We sought to detect gadolinium within the skin and soft tissue of patients with NSF who were exposed to gadolinium-based contrast. METHODS: Paraffin-embedded skin and soft tissue from NSF patients exposed to gadolinium, and from negative controls, was provided by the NSF Registry (New Haven, Conn). The tissue was searched for metals using a field emission scanning electron microscope that was equipped with energy dispersive spectroscopy. The presence of gadolinium and other metals was verified through identification of unique and requisite X-ray emission spectra. RESULTS: Gadolinium was detected in 4 of 13 tissue specimens from 7 patients with documented NSF who were exposed to gadolinium-based radiographic contrast. No gadolinium was detected in a paraffin-embedded specimen from a negative control. Based upon the known exposure history of patients with detectable gadolinium, a tissue residence time of 4 to 11 months was observed. LIMITATIONS: As this was a pilot investigation, only a single control specimen and a single histological section from each block of tissue were utilized. CONCLUSION: In this pilot investigation, gadolinium was detected in the tissue of a number of patients with NSF. Although neither dispositive of a pathophysiologic mechanism, nor proof of causation, the detection of gadolinium within tissue of NSF patients is supportive of an epidemiologic association between exposure to gadolinium-containing contrast material and development of disease.

Acidosis↗
PubMed2003

Gadolinium, carbon dioxide, and iodinated contrast material for planning inferior vena cava filter placement: a prospective trial.

PURPOSE: To prospectively compare the diagnostic accuracy of CO(2) and gadolinium to iodinated contrast material for inferior vena cavography before inferior vena cava (IVC) filter placement. MATERIALS AND METHODS: Forty patients underwent injection of iodinated contrast material, CO(2), and gadolinium. Iodinated contrast material was used as the standard. Caval diameter was determined with calibrated software. Three readers blinded to contrast agent used measured the distance from the superior image border to the inferior margin of the renal veins and from the inferior image border to the iliac bifurcation. The measurements with CO(2) and gadolinium were compared to those with iodinated contrast material to obtain the interobserver and intraobserver variability. The presence or absence of caval thrombus and variant anatomy was noted. The same readers reexamined 12 studies in a separate session to determine intraobserver variability and correlation. RESULTS: Caval diameter differed by 0.4 mm or less for all three agents. Measurements with all agents were within 2 mm of each other for all patients. Gadolinium and CO(2) were not significantly different from one another in measuring caval diameter. At the initial reading, compared with iodinated contrast material, gadolinium had greater mean interobserver error in measuring the distance to the iliac bifurcation and both renal veins (range, 1.6-1.8 mm) than CO(2) (range, 0.2-1.4 mm). This finding, although statistically significant for gadolinium (P <.05), was of doubtful clinical relevance. Interobserver correlation was significantly worse for CO(2) at the levels of the iliac bifurcation (P =.02) and right renal vein (P =.008). Interobserver correlation for gadolinium was similar to that for iodinated contrast material at all levels. At repeat reading, there was significantly inferior intraobserver correlation with use of CO(2) for both renal veins (P <.05) compared to iodinated contrast material and for the left renal vein (P <.05) compared to gadolinium. Gadolinium identified three of three renal vein anomalies identified with iodinated contrast material whereas CO(2) localized one of three. CONCLUSION: CO(2) and gadolinium had limitations when compared with iodinated contrast material. Gadolinium provided superior consistency in identifying relevant landmarks for filter placement. CO(2) demonstrated significantly greater mean correlative error than gadolinium at initial and repeat readings.

Aged↗
PubMed2002

Hepatocellular carcinoma: detection with gadolinium- and ferumoxides-enhanced MR imaging of the liver.

PURPOSE: To test the hypothesis that the accuracy of gadolinium- and ferumoxides-enhanced magnetic resonance (MR) imaging is different in small (< or =1.5-cm) and large (>1.5-cm) hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Forty-three consecutive patients with chronic liver disease were enrolled in this study. The imaging protocol included unenhanced breath-hold T1-weighted fast field-echo sequences, unenhanced respiratory-triggered T2-weighted turbo spin-echo (SE) sequences, dynamic gadolinium-enhanced T1-weighted three-dimensional turbo field-echo sequences, and ferumoxides-enhanced T2-weighted turbo SE sequences. Images of each sequence and two sets of sequences (ferumoxides set and gadolinium set) were reviewed by four observers. The ferumoxides set included unenhanced T1- and T2-weighted images and ferumoxides-enhanced T2-weighted turbo SE MR images. The gadolinium set included unenhanced T1- and T2-weighted images and dynamic gadolinium-enhanced three-dimensional turbo field-echo MR images. In receiver operating characteristic (ROC) curve analysis, the sensitivity and accuracy of the sequences were compared in regard to the detection of all, small, and large HCCs. RESULTS: Imaging performance was different with gadolinium- and ferumoxides-enhanced images in the detection of small and large HCCs. For detection of small HCCs, the sensitivity and accuracy with unenhanced and gadolinium-enhanced imaging (gadolinium set) were significantly (P =.017) superior to those with unenhanced and ferumoxides-enhanced imaging (ferumoxides set). The area under the composite ROC curves, or A(z), for the gadolinium set and the ferumoxides set was 0.97 and 0.81, respectively. For large HCC, the ferumoxides set was superior compared with the gadolinium set, but this difference was not statistically significant. Analysis of all HCCs demonstrated no significant differences for gadolinium- and ferumoxides-enhanced imaging. CONCLUSION: For the detection of early HCC, gadolinium-enhanced MR imaging is preferred to ferumoxides-enhanced MR imaging because the former demonstrated significantly greater accuracy in the detection of small HCCs.

Adult↗
PubMed1995

MR diagnosis of hepatic metastases from neuroendocrine tumors versus hemangiomas: relative merits of dynamic gadolinium chelate-enhanced gradient-recalled echo and unenhanced spin-echo images.

OBJECTIVE: Hepatic metastases from neuroendocrine tumors are often markedly hyperintense on unenhanced T2-weighted MR images, making their appearance similar to that of cavernous hemangiomas. In contrast, cavernous hemangiomas show characteristic enhancement on dynamic gadolinium chelate-enhanced gradient-recalled echo MR images. The purpose of this study was to determine the relative merits of dynamic gadolinium chelate-enhanced gradient-recalled echo MR imaging versus MR imaging with unenhanced spin-echo pulse sequences for distinguishing between hepatic metastases from neuroendocrine tumors and cavernous hemangiomas. MATERIALS AND METHODS: The unenhanced spin-echo and dynamic gradient-recalled echo MR images obtained after IV administration of a gadolinium chelate in 28 patients (14 patients with pathologically proven hepatic metastases from neuroendocrine tumors and 14 patients with hepatic cavernous hemangiomas) were reviewed blindly and independently by three interpreters. Unenhanced spin-echo and dynamic gadolinium chelate-enhanced gradient-recalled echo MR images were compared for accuracy in characterizing liver lesions. RESULTS: The most intense enhancement of hepatic metastases from neuroendocrine tumors was observed on early dynamic gadolinium chelate-enhanced gradient-recalled echo MR images; enhancement was peripheral in four patients, global and heterogeneous in seven patients, and global and homogeneous in three patients. On late dynamic gadolinium chelate-enhanced gradient-recalled echo MR images, enhancement of hepatic metastases from neuroendocrine tumors was predominantly peripheral in five patients, global and heterogeneous in five patients, and global and homogeneous in four patients. Differentiation between cavernous hemangiomas and hepatic metastases from neuroendocrine tumors was impossible in five cases with unenhanced spin-echo MR imaging alone, in five cases with dynamic gadolinium chelate-enhanced gradient-recalled echo MR imaging alone, and in no case with the combination of unenhanced spin-echo MR imaging and dynamic gadolinium chelate-enhanced gradient-recalled echo MR imaging. In comparison with unenhanced spin-echo MR imaging alone or dynamic gadolinium chelate-enhanced gradient-recalled echo MR imaging alone, the combination of unenhanced spin-echo MR imaging and dynamic gadolinium chelate-enhanced gradient-recalled echo MR imaging allowed significantly (p < .001) clearer differentiation between hepatic metastases from neuroendocrine tumors and cavernous hemangiomas. CONCLUSIONS: Early enhancement and heterogeneity on dynamic gadolinium chelate-enhanced gradient-recalled echo MR images are the most common features of hepatic metastases from neuroendocrine tumors. The combination of unenhanced spin-echo and dynamic gadolinium chelate-enhanced gradient-recalled echo MR images allows more accurate characterization of hepatic metastases from neuroendocrine tumors and clearer differentiation from cavernous hemangiomas.

Abdominal Neoplasms↗
PubMed2002

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.

Arthrography↗