Contrast-enhanced MR imaging of coronary arteries: comparison of intra- and extravascular contrast agents in swine

PURPOSE: To compare the efficacy of an intravascular contrast agent, gadomer-17, in improving magnetic resonance (MR) imaging of coronary arteries with that of an extravascular agent, gadopentetate dimeglumine, in pigs. MATERIALS AND METHODS: Eight pigs underwent imaging after three injections: 0.20 mmol of gadopentetate dimeglumine per kilogram of body weight and 0.05 and 0.10 mmol/kg gadomer-17. Coronary images were acquired repeatedly after each injection by using an inversion-recovery-prepared segmented three-dimensional sequence with either breath holding (n = 4) or respiratory gating (n = 4). Coronary artery-to-myocardium contrast-to-noise ratios (CNRs) were compared between injections. RESULTS: At breath-hold imaging, substantial CNR improvement over precontrast images was observed in images acquired during the first pass of gadopentetate dimeglumine in coronary arteries and up to 6 and 10 minutes after 0.05 and 0.10 mmol/kg of gadomer-17 injections, respectively. The CNR with 0.10 mmol/kg of gadomer-17 was 20% (P <.05) higher than that with gadopentetate dimeglumine at first-pass imaging. At respiratory-gated imaging, significant CNR improvement (P <.05) over precontrast images was observed in images acquired up to 10, 30, and 50 minutes after gadopentetate dimeglumine and both gadomer-17 injections, respectively. The CNR on the first images obtained after 0.10 mmol/kg gadomer-17 injection was 168% (P <.05) higher than that on the images obtained after gadopentetate dimeglumine injection. CONCLUSION: Gadomer-17 provided greater and more persistent CNR improvements than did gadopentetate dimeglumine; further evaluation of its utility for coronary imaging in humans is warranted.     

Comparison of two blood pool contrast agents for 0.5-T MR angiography: experimental study in rabbits

PURPOSE: To evaluate two experimental blood pool agents for potential use in equilibrium phase abdominal magnetic resonance (MR) angiography. MATERIALS AND METHODS: MR imaging at 0.5 T was performed in 37 rabbits before and after intravenous injection of a gadolinium-based blood pool contrast agent (SH L 643 A), superparamagnetic iron oxide blood pool agent (SH U 555 C), or gadopentetate dimeglumine. T1-weighted fast spoiled gradient-echo images from the renal arteries to below the iliac bifurcation were obtained. The aorta-to-tissue signal difference-to-noise ratio (SDNR) was measured over time. RESULTS: Both blood pool agents yielded excellent demonstration of the rabbit abdominal aorta. At a dose of 0.1 mmol/kg, both provided a statistically significant increase in aorta-to-tissue SDNR in comparison with that achieved with gadopentetate dimeglumine (200% increase for SH L 643 A, 95% increase for SH U 555 C; P < .05). A 0.1 mmol/kg dose of SH L 643 A provided a 24% increase in SDNR relative to the increase with a 0.37 mmol/kg dose of gadopentetate dimeglumine. Time-dependent enhancement properties of the blood pool agents differed due to differences in elimination method. CONCLUSION: Both blood pool agents were found to be promising contrast agents for 0.5-T MR angiography; however, their clinical applicability warrants further investigation. The gadolinium-based agent had several advantages over the iron oxide compound, including less T2* dephasing, lack of susceptibility artifacts, and fast renal elimination.     

Rectal carcinoma: Prospective comparison of conventional and gadopentetate dimeglumine enhanced fat-suppressed MR imaging

The purpose of this study is to compare the usefulness of conventional MR imaging and gadopentetate dimeglumine enhanced fat-suppressed MR imaging for the depiction and staging of rectal carcinoma. Thirty-two patients were prospectively evaluated by MR imaging using a 1.5-T unit. Based on the results of a barium study and/or digital examination, a balloon catheter was inserted to the level of the lesion before examination. Both conventional T1- and T2-weighted images and gadopentetate dimeglumine enhanced fat-suppressed T1-weighted images were obtained for all patients. The kappa statistics were performed for the evaluation of interobserver agreement and the McNemar test was performed for the analysis of staging accuracy. When only T1- and T2-weighted images were used, 5 of 32 tumors were not detected and the extent of 18 of 32 tumors were unclear. However, when gadopentetate dimeglumine enhanced fat-suppressed imaging was added, 24 of 32 tumors were well defined and only one tumor was not detected. In determining the depth of invasion, the staging accuracy was 72% for conventional imaging and 68% for all images combined. There was no significant difference between with gadopentetate dimeglumine fat-suppressed imaging and conventional imaging (P > .05). Use of gadopentetate dimeglumine (fat-suppressed imaging) resulted in overestimation of muscular invasion, peri-rectal fat invasion, and adjacent organ invasion in 12 patients, whereas nine patients were overestimated without the use of gadopentetate dimeglumine. In the detection of metastatic lymph nodes, gadopentetate dimeglumine enhanced fat-suppressed imaging also was not useful. Tumor detection was excellent using gadopentetate dimeglumine enhanced fat-suppressed images. However, the accuracy of staging was not improved by obtaining such images.     

Effects of gadopentetate dimeglumine administration after osmotic blood-brain barrier disruption: toxicity and MR imaging findings

Osmotic blood-brain barrier disruption with intraarterial chemotherapy has been shown to be beneficial in the treatment of malignant brain tumors. Imaging blood-brain barrier disruption is necessary to document the extent and degree of disruption and to correlate disruption with drug delivery. The present study evaluated blood-brain barrier disruption with gadopentetate dimeglumine-enhanced MR imaging and the associated toxicity of gadopentetate dimeglumine administration. Blood-brain barrier disruption was performed in seven dogs for imaging analysis and 17 dogs for toxicity evaluation. In the absence of gadopentetate dimeglumine administration, blood-brain barrier disruption could not be imaged. Enhanced MR imaging with a gadopentetate dimeglumine dose of 0.1 mmol/kg provided good images of disruption at an imaging time of 3 hr after disruption. However, when gadopentetate dimeglumine was given intravenously in conjunction with osmotic blood-brain barrier disruption, there was a statistically significant (p = .02) dose-dependent increase in the frequency of seizures, with 50% of the animals who received 0.1 mmol/kg and 75% who received 0.2 mmol/kg developing delayed seizures. Our findings show that, as with ionized iodinated CT contrast agents, gadopentetate dimeglumine is associated with toxicity when used in conjunction with osmotic blood-brain barrier disruption in dogs. Such toxicity may be a contraindication to the use of gadopentetate dimeglumine for monitoring patients with osmotically induced disruption of the blood-brain barrier.     

Gadobenate dimeglumine-enhanced MR imaging breast vascular maps: association between invasive cancer and ipsilateral increased vascularity

PURPOSE: To retrospectively compare three different doses of gadobenate dimeglumine with a standard dose of gadopentetate dimeglumine for magnetic resonance (MR) imaging evaluation of breast vessels and to evaluate the accuracy of one-sided increased vascularity seen on gadobenate dimeglumine-enhanced MR images as an indicator of ipsilateral breast cancer. MATERIALS AND METHODS: The original study had local ethics committee approval; informed consent was obtained from all enrolled patients. Ninety-five patients known to have or suspected of having breast cancer were randomly assigned to four groups to receive gadobenate dimeglumine at a dose of 0.05, 0.10, or 0.20 mmol per kilogram of body weight or gadopentetate dimeglumine at a dose of 0.10 mmol/kg. T1-weighted gradient-echo MR images were acquired before and 2 minutes after intravenous contrast material injection. Subtracted images were used to obtain maximum intensity projections (MIPs). Two readers blinded to the type and dose of contrast agent administered scored the MIPs obtained in the dose groups for vessel number, length, and conspicuity from 0, which indicated absent or low breast vascularity, to 3, which indicated high breast vascularity. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of one-sided increased vascularity in association with ipsilateral malignancy for 69 histopathologically confirmed lesions (reference standard) were determined after gadobenate dimeglumine-enhanced MR imaging. RESULTS: The mean MIP scores assigned to the gadobenate dimeglumine groups were significantly higher than those assigned to the gadopentetate dimeglumine group (P < or = .044). Histopathologic analysis revealed malignant lesions in 52 of 69 patients examined with gadobenate dimeglumine MR imaging: invasive ductal carcinoma in 45, invasive lobular carcinoma in four, and invasive mixed ductal-lobular carcinoma in three patients. Seventeen patients had benign lesions. Two cases of bilateral invasive cancer with symmetric breast vascular maps were excluded. Thus, the overall sensitivity, specificity, accuracy, PPV, and NPV of one-sided increased vascularity as a finding associated with ipsilateral malignancy were 88% (44 of 50 patients), 82% (14 of 17 patients), 87% (58 of 67 patients), 94% (44 of 47 patients), and 70% (14 of 20 patients), respectively. CONCLUSION: Gadobenate dimeglumine is effective for MR imaging evaluation of breast vessels at doses as low as 0.05 mmol/kg. One-sided increased vascularity is an MR imaging finding frequently associated with ipsilateral invasive breast cancer.     

Magnetic resonance enhancement pattern and diagnostic accuracy of gadofluorine M in a rabbit VX2 tumor model: Comparison with gadopentetate dimeglumine

Objective

The purpose of this study was to evaluate the enhancement pattern and the diagnostic accuracy of gadofluorine M in comparison with gadopentetate dimeglumine in a rabbit VX2 tumor model.

Materials and methods

Thirteen rabbits with experimentally induced VX2 carcinomas in the thighs underwent sequential T1-weighted enhancement MR imaging using a 3.0 T MR imager, first with gadopentetate dimeglumine, and then 24 (n = 4) or 4 h (n = 9) later with gadofluorine M. In 4 rabbits with 13 tumors, the time-percentage enhancement (PE; i.e., percentage of signal intensity increase) curve was obtained for up to 24 h for each contrast agent. In 9 rabbits with 49 tumors (random numbers of VX2 tumors were inoculated at random sites in the thigh), 3 readers unaware of the histopathologic results interpreted the MR images and determined the number and conspicuity level of the detected tumors. The reference standard was the histopathology of the specimen.

Results

The time-to-peak PE for gadopentetate dimeglumine was 1 min and gadopentetate dimeglumine showed a rapid washout pattern. The time-to-peak PE for gadofluorine M was 30 min and gadofluorine M showed a plateau enhancement pattern for up to 24 h. The peak PE of gadofluorine M was approximately twice that of the same dose of gadopentetate dimeglumine (108.2 ± 14.8 vs. 51.5 ± 24.0). The sensitivities for detecting VX2 tumors by 3 readers were 89.8% (44/49), 85.7% (42/49), and 95.9% (47/49) for gadopentetate dimeglumine-enhanced MR imaging, and 87.8% (43/49), 89.8% (44/49), and 89.8% (44/49) for gadofluorine M-enhanced MR imaging. No significant differences in the sensitivities existed between the two contrast agents for any reader. However, the conspicuity level of tumors was superior with gadofluorine M-enhanced MR imaging for two readers and similar for the other reader.

Conclusion

Gadofluorine M showed strong and plateau enhancement of tumors for up to 24 h. In the reader study, gadofluorine M showed better conspicuity for VX2 tumors than gadopentetate dimeglumine, but had a similar sensitivity.     

Evaluation of myocardial perfusion abnormalities with gadolinium-enhanced snapshot MR imaging in humans. Work in progress.

To determine whether myocardial perfusion abnormalities could be detected in patients with coronary artery disease by means of contrast material-enhanced magnetic resonance (MR) images, a snapshot imaging technique was used in six patients with coronary artery disease and four healthy subjects in conjunction with pharmacologic stress (dipyridamole infusion) and bolus injection of gadopentetate dimeglumine. MR images from all patients and healthy subjects were quantitatively analyzed to define spatial changes in signal intensity after administration of dipyridamole and gadopentetate dimeglumine. The resultant findings were compared with findings on thallium-201 scintigrams obtained after administration of dipyridamole and on coronary arteriograms in all patients. Nine myocardial regions supplied by stenosed arteries showed diminished levels of signal intensity after infusion of the contrast agent compared with those of normally perfused regions. These findings were in agreement with those obtained with T1-201 scintigraphy (in eight of nine regions) and arteriography. Thus, contrast-enhanced high-speed MR imaging with use of dipyridamole enabled detection of regional perfusion abnormalities in humans.     

Gadopentetate dimeglumine-enhanced MR of the brain: clinical utility and safety in patients younger than two years of age.

PURPOSETo evaluate the clinical utility and safety of gadopentetate dimeglumine as a contrast agent for MR of the brain in patients younger than 2 years of age.METHODSIn 125 consecutive patients younger than 2 years of age, MR images obtained before and after gadopentetate dimeglumine administration (0.1 mmol/kg) were independently and prospectively evaluated. After interpreting the unenhanced T1- and T2-weighted images, we rated the utility of contrast administration in each patient as not helpful, helpful, or essential for formulation of the radiologic diagnosis. Ratings were categorized both on the basis of the referring clinical diagnoses and on the basis of a radiologic diagnosis that was established from the clinical history and from the findings on the precontrast and postcontrast T1- and T2-weighted images. Patients'' vital signs were recorded, and general medical status was observed for 120 minutes after gadopentetate dimeglumine administration.RESULTSIn no case did gadopentetate dimeglumine permit detection of lesions when precontrast T1- and T2-weighted images were normal. In only 4 of 125 patients were postcontrast images considered essential for establishing the radiologic diagnosis. Abnormal contrast enhancement was radiologically helpful in 20 of 125 patients. Lack of enhancement was considered helpful in 22 of 125 patients. No adverse clinical events or clinically important trends in vital signs were observed after contrast administration.CONCLUSIONThe indiscriminate use of contrast agents in the MR imaging of patients younger than 2 years of age is not warranted. Appropriate decisions regarding the use of gadopentetate dimeglumine can be based on the findings in unenhanced T1- and T2-weighted images and on the referring clinical diagnosis.     

Bowel disease: prospective comparison of CT and 1.5-T pre- and postcontrast MR imaging with T1-weighted fat-suppressed and breath-hold FLASH sequences.

The potential of new high-field-strength magnetic resonance (MR) imaging sequences to evaluate bowel disease was investigated and compared with computed tomographic (CT) studies. Thirty-two patients were studied, 14 with known or suspected gastrointestinal tumors and 18 with known or suspected bowel inflammatory conditions. T1-weighted fat-suppressed spin-echo and breath-hold FLASH (fast low-angle shot) images were obtained before and after intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine. Pathologic confirmation was obtained by biopsy (n = 18), surgical excision (n = 8), or endoscopy (n = 6). CT and MR images were analyzed separately in a prospective fashion and reviewed by consensus. Information from CT and MR images was comparable in cases of confirmed bowel neoplasia. CT scans had better spatial resolution, while fat-suppressed gadolinium-enhanced MR images had better contrast resolution. In the 18 cases of bowel inflammation, CT scans showed concentric wall thickening in 16, while MR images showed concentric wall thickening in 14 and increased contrast enhancement in 17. Contrast enhancement was better appreciated on fat-suppressed images than on FLASH images. The results suggest that MR imaging may play a role in the evaluation of bowel disease.     

Focal liver lesions: SPIO-, gadolinium-, and ferucarbotran-enhanced dynamic T1-weighted and delayed T2-weighted MR imaging in rabbits

PURPOSE: To compare a superparamagnetic iron oxide (SPIO), VSOP-C184, with a gadopentetate dimeglumine with regard to signal-enhancing effects on T1-weighted dynamic magnetic resonance (MR) images and with another SPIO contrast medium with regard to signal-reducing effects on delayed T2-weighted MR images. MATERIALS AND METHODS: All experiments were approved by the responsible Animal Care Committee. Twenty rabbits (five for each contrast agent and dose) implanted with VX-2 carcinoma were imaged at 1.5 T. VSOP-C184 at 0.015 and 0.025 mmol Fe/kg was compared with gadopentetate dimeglumine at 0.15 mmol Gd/kg and ferucarbotran at 0.015 mmol Fe/kg. The imaging protocol comprised a T1-weighted dynamic gradient-echo (GRE) MR before injection and at 6-second intervals for up to 42 seconds after injection and a T2-weighted turbo spin-echo MR before and 5 minutes after injection. Images were evaluated quantitatively, and contrast media were compared by using nonparametric analysis of variance. RESULTS: At dynamic T1-weighted GRE MR imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median peak contrast-to-noise ratio (CNR) was 20.7 (25th percentile, 16.3; 75th percentile, 22.6), 24.2 (25th percentile, 19.3; 75th percentile, 28.5), 16.4 (25th percentile, 13.7; 75th percentile, 20.3), and 14.0 (25th percentile, 11.4; 75th percentile, 16.8), respectively. Both doses of VSOP-C184 yielded significantly higher CNR (P < .05) than the other two agents. At T2-weighted turbo spin-echo imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median CNR was 15.0 (25th percentile, 13.4; 75th percentile, 21.3), 15.7 (25th percentile, 14.5; 75th percentile, 19.8), 11.3 (25th percentile, 8.2; 75th percentile, 12.2), and 15.7 (25th percentile, 12.5; 75th percentile, 22.4), respectively. There was no significant difference between VSOP-C184 and ferucarbotran; both had a significantly higher CNR than did gadopentetate dimeglumine. CONCLUSION: VSOP-C184 produces higher liver-to-tumor contrast at dynamic T1-weighted imaging than does gadopentetate dimeglumine; at delayed T2-weighted imaging, the contrast is comparable to that achieved with ferucarbotran.     

Multiphasic MR angiography as an intra-individual comparison between the contrast agents Gd-DTPA,Gd-BOPTA,and Gd-BT-DO3A

QUESTION: The availability of new MR contrast agents having either a protein binding effect or higher concentration leads to the question if they differ from standard compounds in their vascular contrasting properties. METHODS: By intraindividual comparison five volunteers were examined (1.5 T MR system) with a multi-phasic MRA of the abdomen each receiving three different contrast agents (gadopentetate dimeglumine 0.5 M; gadobenate dimeglumine 0.5 M, and gadobutrol 1.0 M).The dose (0.15 mmol/kg body weight) and flow rate (3.0 ml/s) were kept identical. All images were quantitatively and qualitatively evaluated by blinded assessment. RESULTS: Significantly higher maximum signal intensity was found in the arteries for the protein interacting gadobenate dimeglumine (p = 0.05). No significant difference in vascular enhancement was demonstrated in the comparison of gadobutrol to gadopentetate dimeglumine. CONCLUSION: Gadobenate dimeglumine was shown to be a favorable contrast agent for multi-phasic MRA. A higher concentrated Gd-chelate does not automatically lead to improved vascular contrast if standard imaging protocols are used.     

Enhancement effects of hepatic dynamic MR imaging at 3.0 T and 1.5 T using gadoxetic acid in a phantom study: comparison with gadopentetate dimeglumine

To identify the optimum sequence at gadoxetic acid enhanced hepatic dynamic magnetic resonance imaging in the arterial phase, we studied phantoms that contained gadoxetic acid or gadopentetate dimeglumine diluted in human blood. We obtained magnetic resonance images at 3.0 T and 1.5 T with one vendor (Siemens) using 3D‐gradient echo (GRE)‐, 2D‐fast low angle shot (FLASH)‐, and turbo spin echo sequences. Contrast ratio was highest for 3D‐GRE; at both 3.0 T and 1.5 T it was superior when the contrast agent was gadoxetic acid. With both gadoxetic acid and gadopentetate dimeglumine, contrast ratio peaked at around 5‐and 2 mmol/L on 3D‐GRE‐ and 2D‐FLASH images, respectively. Compared with gadopentetate dimeglumine, at 3.0 T, the peak contrast ratio of gadoxetic acid was 14.1% better on 3D‐GRE images and 14.0% better on 2D‐FLASH images; at 1.5 T it was 16.4% better on 3D‐GRE‐ and 5.7% better on 2D‐FLASH images. With respect to the magnetic field strength, at 3.0 T the peak contrast ratio of gadoxetic acid was 6.0% better than at 1.5 T on 3D‐GRE images and 49.5% better on 2D‐FLASH images; it was 8.5% better on 3D‐GRE‐ and 44.6% better on 2D‐FLASH images than when the contrast agent was gadopentetate dimeglumine. Thus, gadoxetic acid yielded better enhancement on 3D‐GRE images acquired at 3.0 T than at 1.5 T and enhancement was better than that obtained with gadopentetate dimeglumine at the same concentration. Magn Reson Med 66:213–218, 2011. © 2011 Wiley‐Liss, Inc.     

Gadodiamide injection and gadopentetate dimeglumine. A double-blind study in MR imaging of the CNS.

A double-blind, randomized parallel phase III study in MR imaging of the central nervous system was conducted to compare the safety and diagnostic utility of gadodiamide injection and gadopentetate dimeglumine at a dose of 0.1 mmol/kg b.w. in 60 adult patients. Seven patients in the gadodiamide injection group experienced 10 adverse events, 5 of the events possibly related to the contrast agent. In the gadopentetate dimeglumine group 5 patients reported 3 contrast agent-related adverse events out of 8 events. All events were transient and required no treatment. Seven incidents of patient discomfort, and some minor changes in vital signs and laboratory parameters were of no clinical concern. Contrast enhancement was observed in 60% and 44% of the patients with structural abnormalities in the gadodiamide injection group and gadopentetate dimeglumine group, respectively. No difference in overall efficacy was observed. Gadodiamide injection was found to be a safe and effective contrast agent.     

Gadolinium-enhanced magnetization transfer contrast imaging of intracranial tumors.

The magnetization transfer contrast (MTC) technique was used in low-field-strength (0.1 T) magnetic resonance (MR) imaging of 28 patients with intracranial tumors. MTC images were generated with an off-resonance, low-power radio-frequency pulse applied during the interpulse delay period of a gradient-echo partial-saturation sequence (TR msec/TE msec = 200/20). Images in the presence and absence of the MTC pulse were concurrently acquired before and after injection of gadopentetate dimeglumine at a dose of 0.1 mmol/kg. The contrast agent enhanced 27 of 28 tumors. Application of the MTC pulse improved the contrast-to-noise ratio (C/N) between tumor and normal white matter in 26 of 28 cases on the preinjection images and in 25 of 28 cases on the postinjection images. On the gadolinium-enhanced images, the mean C/N was 2.6 +/- 1.7 without the MTC pulse and 3.2 +/- 1.9 with the MTC pulse. The greatest contrast improvement with the MTC technique was obtained in tumors showing the strongest paramagnetic enhancement. The results indicate that MTC can improve contrast between normal brain and some intracranial neoplasms. The use of gadopentetate dimeglumine generally intensified this effect.     

Transtympanic iontophoresis with a biocompatible paramagnetic solution at MR imaging: experimental feasibility study in rabbits

PURPOSE: To determine the feasibility of transtympanic iontophoresis in experimental animals with a paramagnetic contrast agent at magnetic resonance (MR) imaging. MATERIALS AND METHODS: Optimal MR sequence parameters and appropriate paramagnetic ion concentrations of a water and gadopentetate dimeglumine solution were initially assessed with phantoms. Iontophoresis was performed in left ears of five rabbits after the external auditory canals were filled with a solution of water and gadopentetate dimeglumine of optimal concentration, and right ears were used as controls. Signal-to-structural noise ratio (SSNR) and contrast-to-structural noise ratio (CSNR) were measured by using regions of interest, and the overall image quality was assessed subjectively. RESULTS: Spin-echo (SE) MR sequences were superior to gradient-echo (GRE) MR sequences in terms of SSNR, CSNR, and overall image quality. Highest SSNR and CSNR values were achieved with 2 mmol/L (2 mM) of gadopentetate dimeglumine solution with both SE (repetition time msec/echo time msec, 500/12; flip angle, 90 degrees ) and GRE (300/10; flip angle, 90 degrees ) sequences in both phantoms and animals. The high signal intensity of gadopentetate dimeglumine solution was recognized in middle ears, vestibules, and semicircular canals of all rabbit ears that had undergone iontophoresis and in none of the control ears. CONCLUSION: With the solution of water and gadopentetate dimeglumine, the maximum SSNR and CSNR with both SE and GRE MR imaging sequences were achieved. The solution can be transferred to the middle and inner ear cavities across an intact tympanic membrane by using transtympanic iontophoresis.     

VX2 carcinoma in rabbits after radiofrequency ablation: comparison of MR contrast agents for help in differentiating benign periablational enhancement from residual tumor

PURPOSE: To prospectively compare the accuracy of a blood pool agent, SH L 643A, with that of gadopentetate dimeglumine in differentiating benign periablational enhancement from residual tumor in VX2 carcinomas in rabbits after radiofrequency (RF) ablation. MATERIALS AND METHODS: Experiment was approved by the animal care committee. Sequential MR images were obtained before and with SH L 643A (17 000 Da, 0.05 mmol/kg) and, after a 24-hour interval, gadopentetate dimeglumine (546 Da, 0.1 mmol/kg) in 12 rabbits with VX2 carcinoma in the back muscle prior to (n = 12) and early (n = 12), 1 week (n = 8), and 4 weeks (n = 4) after RF ablation. RF ablation was performed with output of 90 W but at less than 300 seconds to ensure incomplete tumor ablation. The pathologic specimens were sectioned in the same plane as MR imaging, and the enhancement ratios (ie, the ratios of postcontrast to precontrast signal intensity) and the microvessel densities of residual tumor and benign periablational enhancement were assessed. RESULTS: With SH L 643A, the peak enhancement ratios of residual tumor (1.64 +/- 0.31 [standard deviation]) were significantly higher than those of benign periablational enhancement (0.97 +/- 0.16) (P < .001). With gadopentetate dimeglumine, the peak enhancement ratios of residual tumor (1.82 +/- 0.33) were not different from those of benign periablational enhancement (1.71 +/- 0.36). In benign periablational enhancement, enhancement ratios with injection of SH L 643A were lower than those with injection of gadopentetate dimeglumine for all time points up to 30 minutes (P < .05). The microvessel density was 25.72 +/- 5.43 vessels per field of view for residual tumor and 10.37 +/- 2.88 vessels per field of view for benign periablational enhancement (P < .001). CONCLUSION: Blood pool contrast agent SH L 643A permits more accurate differentiation of benign periablational enhancement from residual tumor compared with the extracellular agent gadopentetate dimeglumine.     

Efficacy and safety of gadopentetate dimeglumine in the evaluation of patients with a suspected tumor of the extracranial head and neck

The clinical efficacy and safety of gadopentetate dimeglumine as a paramagnetic contrast agent for magnetic resonance (MR) imaging of the extracranial head and neck was evaluated in a multicenter trial involving 60 patients. Patients with signs and/or symptoms of a tumor in the nasopharynx, oropharynx, hypopharynx, larynx, or neck were studied. T1-weighted images were obtained before and after injection of gadopentetate dimeglumine, 0.1 mmol/kg, at a rate of 10 mL/min. No lesions were seen on the pre- or postinjection images of five of the 60 patients. Postinjection lesion enhancement was present in 53 of the remaining 55 (96%) patients. The absence of postinjection lesion enhancement in one of the two remaining patients was useful information. Postinjection impressions differed from preinjection diagnosis in 22 of 60 (37%) patients. Additional information was obtained from postinjection relative to preinjection images in 38 of 60 (63%) patients. Four adverse experiences were reported in three of 60 (5%) patients. Two mild (chest wall pain and headache) and one moderate (nausea) adverse experiences were considered by the authors to be unrelated to the studied drug. One severe adverse experience was reported. This patient had a seizure, considered by the investigator to be remotely related to the study drug and attributed to the abrupt withdrawal of anticonvulsant medications. The data indicate that gadopentetate dimeglumine is safe and efficacious in the evaluation of patients with extracranial head and neck lesions.     

Patellar articular cartilage lesions: in vitro MR imaging evaluation after placement in gadopentetate dimeglumine solution

PURPOSE: To evaluate T1-weighted magnetic resonance (MR) imaging after diffusion of gadopentetate dimeglumine for visualization of articular cartilage lesions. MATERIALS AND METHODS: MR imaging was performed in eight human cadaveric patella specimens immediately and 4 hours after placement into a vessel filled with gadopentetate dimeglumine solution (2.5 mmol/L). T1-weighted spin-echo and inversion-recovery turbo spin-echo MR sequences with nulled cartilage signal (inversion time of 300 msec) were used. In a total of 128 articular cartilage areas, MR imaging findings were compared with macroscopic and histopathologic findings. Pathologic evaluation was performed by one musculoskeletal pathologist. With knowledge of pathologic observations, MR images were analyzed by one musculoskeletal radiologist with regard to intrinsic signal intensity characteristics and surface abnormalities of articular cartilage. RESULTS: Histopathologic findings demonstrated 67 areas of normal articular cartilage and 66 cartilage lesions (grade 1, n = 19; grade 2, n = 15; grade 3, n = 26; grade 4, n = 6). All grade 3 and 4 lesions could be identified on MR images obtained immediately after submersion and after 4 hours. Ninety-four percent of grade 1 and 2 lesions were identified as areas of predominantly decreased contrast enhancement on delayed MR images obtained with both sequences. MR images obtained immediately after submersion demonstrated abnormal signal intensity in only 9% and 12% of grade 1 and 2 lesions, respectively. CONCLUSION: T1-weighted MR images obtained in vitro after gadopentetate dimeglumine diffusion allow demonstration of articular cartilage surface lesions and early stages of cartilage degradation.     

Contrast-enhanced MR imaging of postoperative scars and VX2 carcinoma in rabbits: comparison of macromolecular contrast agent and gadopentetate dimeglumine

PURPOSE: To compare the magnetic resonance (MR) imaging enhancement patterns of a blood pool contrast agent, SH L 643A, with those of gadopentetate dimeglumine in postoperative scars and VX2 carcinomas in rabbits and to compare these enhancement patterns with microvessel density in pathologic specimens. MATERIALS AND METHODS: Eighteen rabbits with experimentally induced postoperative scars (n = 12) or VX2 carcinoma (n = 6) in the thighs underwent sequential MR imaging first with gadopentetate dimeglumine and then, 24 hours later, with SH L 643A. The enhancement ratios (ie, the ratios of postcontrast to precontrast signal intensity) and the microvessel densities of postoperative scars and VX2 carcinomas were assessed. Differences were tested for by using the Mann-Whitney U and Wilcoxon signed rank tests. RESULTS: In postoperative scars, enhancement ratios were consistently lower with injection of SH L 643A than with injection of gadopentetate dimeglumine for up to 30 minutes (P <.05). In postoperative scars, mean peak enhancement ratios were 1.29 +/- 0.15 (SD) with injection of SH L 643A and 1.61 +/- 0.31 with injection of gadopentetate dimeglumine (P <.01). In VX2 carcinomas, the enhancement ratios were not significantly different with injection of SH L 643A than with injection of gadopentetate dimeglumine at all time points. The mean difference between the enhancement ratios of the VX2 carcinomas and postoperative scars was 0.64 +/- 0.10 (range, 0.50-0.77) with SH L 643A and 0.36 +/- 0.16 (range, 0.17-0.66) with gadopentetate dimeglumine (P <.01). The mean microvessel density (in terms of vessels per field of view) was 10.7 +/- 5.5 for postoperative scars and 30.0 +/- 7.7 for VX2 carcinoma (P <.001). CONCLUSION: The difference between the enhancement ratios of postoperative scars and VX2 carcinomas with SH L 643A was greater than that with gadopentetate dimeglumine. Enhancement ratios at SH L 643A-enhanced MR imaging corresponded well with microvessel density in postoperative scars and VX2 carcinomas.     

MR imaging of the stomach: potential use for mangafodipir trisodium--a study in swine

PURPOSE: To evaluate mangafodipir trisodium as a potential contrast agent at magnetic resonance (MR) imaging of the stomach. MATERIALS AND METHODS: Mangafodipir trisodium was injected intravenously into three swine at a dose of 5 micromol per kilogram of body weight. For comparison, gadopentetate dimeglumine was injected into three other swine at a dose of 0.1 mmol per kilogram of body weight. T1-weighted three-dimensional MR images were acquired in all six swine at 1.5 T before and approximately 10, 15, 20, 25, 30, and 40 minutes after contrast material administration. Extracted stomach specimens were imaged at 3.0 T. In vivo and ex vivo images were evaluated visually and quantitatively for contrast enhancement of the stomach, and in vivo images were evaluated for the presence of reflux from the duodenum. RESULTS: Mangafodipir trisodium produced prolonged and selective enhancement of the inner surface of the stomach, in contrast to the more general enhancement seen with gadopentetate dimeglumine, and reflux from the duodenum could not account for this selective enhancement. Ex vivo images confirmed that T1 enhancement in the stomach wall with mangafodipir trisodium was limited to the inner surface. Gadopentetate dimeglumine did not produce selective enhancement of the inner surface of the stomach. CONCLUSION: Mangafodipir trisodium preferentially enhances the inner surface of the stomach on MR images acquired in swine and, therefore, may have potential for use as a contrast agent at MR imaging of the human stomach.