Gadobenate dimeglumine-enhanced MRI of the breast: analysis of dose response and comparison with gadopentetate dimeglumine

OBJECTIVE: The purpose of this study was to evaluate the clinical efficacy and dose response relationship of three doses of gadobenate dimeglumine for MRI of the breast and to compare the results with those obtained after a dose of 0.1 mmol/kg of body weight of gadopentetate dimeglumine. SUBJECTS AND METHODS. Gadobenate dimeglumine at 0.05, 0.1, or 0.2 mmol/kg of body weight or gadopentetate dimeglumine at 0.1 mmol/kg of body weight was administered by IV bolus injection to 189 patients with known or suspected breast cancer. Coronal three-dimensional T1-weighted gradient-echo images were acquired before and at 0, 2, 4, 6, and 8 min after the administration of the dose. Images were evaluated for lesion presence, location, size, morphology, enhancement pattern, conspicuity, and type. Lesion signal intensity-time curves were acquired, and lesion matching with on-site final diagnosis was performed. A determination of global lesion detection from unenhanced to contrast-enhanced and combined images was performed, and evaluations were made of the diagnostic accuracy for lesion detection and characterization. A full safety evaluation was conducted. RESULTS: Significant dose-related increases in global lesion detection were noted for patients who received gadobenate dimeglumine (p < 0.04, all evaluations). The sensitivity for detection was comparable for 0.1 and 0.2 mmol/kg of gadobenate dimeglumine, and specificity was highest with the 0.1 mmol/kg dose. Higher detection scores and higher sensitivity values for lesion characterization were found for 0.1 mmol/kg of gadobenate dimeglumine compared with 0.1 mmol/kg of gadopentetate dimeglumine, although more variable specificity values were obtained. No differences in safety were observed, and no serious adverse events were reported. CONCLUSION: Gadobenate dimeglumine is a capable diagnostic agent for MRI of the breast. Although preliminary, our results suggest that 0.1 mmol/kg of gadobenate dimeglumine may offer advantages over doses of 0.05 and 0.2 mmol/kg of gadobenate dimeglumine and 0.1 mmol/kg of gadopentetate dimeglumine for breast lesion detection and characterization.     

Visceral metastases from melanoma: findings on MR imaging.

Typical ocular and CNS melanomas are hyperintense on T1-weighted MR images and hypointense on T2-weighted MR images. We performed MR imaging in 48 patients with melanoma metastatic to visceral organs. Images were reviewed retrospectively in order to determine whether there were predominant MR features specific for visceral melanoma and to see if visceral metastases have MR characteristics similar to metastases in the CNS. Eleven patients also were examined after injection of gadopentetate dimeglumine to evaluate the enhancement characteristics of these tumors. Two hundred sixty-one lesions were found. Lesions were classified according to their signal intensities relative to uninvolved liver on T1-weighted, T2-weighted, and short TI inversion recovery (STIR) pulse sequences. Most commonly, lesions were either hypointense or isointense on T1-weighted sequences and hyperintense on T2-weighted and STIR sequences (185 lesions). Less frequently, lesions were hyperintense on T1-weighted sequences and hypointense or isointense on T2-weighted and STIR sequences (59 lesions). A mixed pattern was seen on T1- and T2-weighted sequences in 17 lesions. The patterns did not correlate with lesion size. Of the three sequences studied by subjective comparison, the STIR sequence in our series had the highest sensitivity for lesion detection and yielded the highest lesion conspicuity. Injection of gadopentetate dimeglumine in 11 patients did not increase either the number or the conspicuity of lesions seen. Our results show that visceral metastases from melanoma have a wide variety of appearances on MR images. The STIR sequence appears to be optimal, and the metastases do not enhance with gadopentetate dimeglumine.     

Dynamic gadolinium-enhanced rapid acquisition spin-echo MR imaging of the liver

Rapid acquisition spin-echo (RASE) magnetic resonance (MR) imaging allows for coverage of the entire liver with highly T1-weighted SE images during a single 23-second breath-holding period. The RASE sequence was implemented in conjunction with rapid intravenous injection of gadopentetate dimeglumine to enable performance of dynamic contrast material-enhanced MR imaging of the liver. Prospective evaluation of 24 patients with 62 liver lesions 1 cm or greater in diameter was performed. Images obtained with RASE were devoid of respiratory-related ghost artifacts or edge blurring. The dynamic contrast-enhanced RASE technique resulted in contrast-to-noise and contrast-to-artifact values and time efficiency measures significantly greater (P less than .05) than those obtained with use of conventional T1- and T2-weighted pulse sequences, indicating a higher likelihood for lesion detectability. Lesion conspicuity was maximal during or immediately following bolus administration of gadopentetate dimeglumine, with lesions often becoming obscured at delayed postcontrast imaging.     

Primary and secondary brain tumors at MR imaging: bicentric intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine

PURPOSE: To evaluate the safety of and compare the enhancement characteristics of gadobenate dimeglumine (MultiHance; Bracco Imaging, Milan, Italy) with those of a standard gadolinium chelate (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) in primary and secondary brain tumors on the basis of qualitative and quantitative parameters, on an intraindiviual basis. MATERIALS AND METHODS: Twenty-seven patients with either high-grade glioma or metastases were enrolled in a bicentric intraindividual crossover study to compare lesion enhancement with doses of 0.1 mmol per kilogram of body weight of 0.5 mol/L gadopentetate dimeglumine and 0.5 mol/L gadobenate dimeglumine. MR imaging was performed before injection (T1-weighted spin-echo [SE] and T2-weighted fast SE acquisitions) and at 1, 3, 5, 7, 9, and 16 minutes after injection (T1-weighted SE acquisitions). Qualitative assessment was performed by blinded off-site readers (for 22 patients) and on-site investigators (for 24 patients) in terms of global contrast enhancement, lesion-to-brain contrast, lesion delineation, internal lesion morphology and structure, tumor vascularization, and global image preference. Additional quantitative assessment with region-of-interest analysis was performed by off-site readers alone. Statistical analysis of qualitative data was performed with the Wilcoxon signed rank test, whereas a nonparametric approach was adopted for analysis of quantitative data. RESULTS: Significant (P <.05) preference for gadobenate dimeglumine over gadopentetate dimeglumine was noted both off-site and on-site for the global assessment of contrast enhancement. For off-site readers 1 and 2 and the on-site investigators, respectively, gadobenate dimeglumine was preferred in 13, 17, and 16 patients; gadopentetate dimeglumine was preferred in four, four, and four patients; and equality was found in five, one, and four patients). Similar preference for gadobenate dimeglumine was noted by off-site readers and on-site investigators for lesion-to-brain contrast and all other qualitative parameters. Off-site quantitative evaluation revealed significantly (P <.05) superior enhancement for gadobenate dimeglumine compared with that for gadopentetate dimeglumine at all time points from 3 minutes after injection. CONCLUSION: Significantly superior contrast enhancement of intraaxial enhancing brain tumors was achieved with 0.1 mmol/kg gadobenate dimeglumine compared with that with 0.1 mmol/kg gadopentetate dimeglumine.     

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.     

Dynamic gadolinium-enhanced MR imaging of the spleen: normal enhancement patterns and evaluation of splenic lesions

The authors studied the ability to improve detection of splenic lesions during suspended respiration with dynamic gadolinium-enhanced T1-weighted spin-echo magnetic resonance (MR) imaging. In the first phase of the study, normal splenic contrast material enhancement patterns were assessed in 10 control patients without splenic lesions. A heterogeneous signal intensity pattern was observed in 11 patients with splenic lesions during bolus injection of gadopentetate dimeglumine, with conversion to homogeneous enhancement 1 minute later. Mean splenic enhancement was 321% during bolus injection, with a rapid return toward baseline signal intensity thereafter. In the second phase, evaluation of 18 splenic lesions detected with contrast-enhanced computed tomography in 11 patients revealed that dynamic gadolinium-enhanced MR pulse sequences significantly improved lesion conspicuity and detectability compared with conventional T1-and T2-weighted pulse sequences. Contrast-to-artifact ratio measurements were 0.5, 3.7, and 9.3 for conventional T1-weighted, T2-weighted, and dynamic gadolinium-enhanced MR images, respectively.     

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.     

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.     

Rheumatoid knee: role of gadopentetate-enhanced MR imaging

Physical examination is often insufficient in distinguishing between joint effusion and inflamed synovium in the knee joints of patients with rheumatoid arthritis. The authors prospectively evaluated the role of intravenously administered gadopentetate dimeglumine in distinguishing between these two conditions. Fourteen patients with classic rheumatoid arthritis were examined first by a rheumatologist and then by means of magnetic resonance (MR) imaging with T1- and T2-weighted sequences. T1-weighted images were also obtained following the intravenous administration of gadopentetate dimeglumine. T1-weighted images obtained prior to contrast material administration demonstrated an identical low-intensity signal from both effusion and inflamed synovium, and T2-weighted images demonstrated increased signal intensity in both cases. Intravenous administration of gadopentetate dimeglumine allowed distinction between effusion and abnormal synovium, with the effusion remaining of low signal intensity and the synovium demonstrating enhancement and increased signal intensity. The authors conclude that the use of gadopentetate allows distinction between synovial thickening and joint effusion in the knee, which may affect treatment decisions.     

Diagnostic value of gadopentetate dimeglumine for 1.5-T MR imaging of musculoskeletal masses: comparison with unenhanced T1- and T2-weighted imaging.

Three magnetic resonance (MR) imaging techniques (T1-weighted, T2-weighted, and T1-weighted gadopentetate dimeglumine--enhanced) were compared in 32 consecutive MR imaging studies of 26 patients with suspected musculoskeletal masses. T2-weighted images were superior to T1-weighted enhanced images with respect to detection and definition of lesions in 12% of cases (n = 4) and were equal in 88% of cases (n = 28). T2-weighted images were also superior to T1-weighted images in 38% of cases (n = 12). In no cases were T1-weighted enhanced images superior to T2-weighted images. In two cases, T1-weighted images were superior to both T1-weighted enhanced and T2-weighted images. The authors conclude that gadopentetate dimeglumine did not provide much value in lesion detection above that obtained with T2-weighted images. They also conclude that T1-weighted images were occasionally superior to T1-weighted enhanced images and T2-weighted images because of loss of definition between fat and lesion on the latter.     

Detection of hepatocellular carcinoma arising in cirrhotic livers: comparison of gadolinium- and ferumoxides-enhanced MR imaging.

OBJECTIVE: We prospectively compared the detectability of hepatocellular carcinoma (HCC) arising in cirrhotic livers using dynamic gadolinium-enhanced fast low-angle shot (FLASH), ferumoxides-enhanced T2-weighted turbo spin-echo, and ferumoxides-enhanced T2*-weighted FLASH MR imaging. SUBJECTS AND METHODS: Fifty-three patients with HCC (32 men and 21 women) who were 33-86 years old (mean, 63 years old) were enrolled in a prospective MR study to assess hepatic lesions using both gadopentetate dimeglumine and ferumoxides. Dynamic gadolinium-enhanced imaging was obtained before and 30, 60, and 180 sec after rapid bolus injection of gadopentetate dimeglumine (0.1 mmol/kg). Ferumoxides-enhanced T2-weighted turbo spin-echo imaging and ferumoxides-enhanced T2*-weighted FLASH imaging were performed between 30 min and 2 hr after i.v. infusion of ferumoxides (10 micromol/kg). Images were analyzed qualitatively and quantitatively. A receiver operating characteristic curve study was performed to compare the diagnostic value of gadolinium-enhanced imaging with that of ferumoxides-enhanced imaging for the detection of HCC. RESULTS: Quantitative analysis revealed a significantly higher percentage of signal-intensity loss and higher liver-lesion contrast-to-noise ratio on ferumoxides-enhanced T2*-weighted FLASH imaging than on ferumoxides-enhanced T2-weighted turbo spin-echo imaging. The percentage of signal-intensity loss and liver-lesion contrast-to-noise ratio on ferumoxides-enhanced images was significantly higher in patients with mild liver cirrhosis (Child's class A) than in patients with severe liver cirrhosis (Child's class C). Qualitative analysis showed that dynamic gadolinium-enhanced images revealed significantly higher lesion conspicuity than did ferumoxides-enhanced T2-weighted turbo spin-echo images. According to receiver operating characteristic analysis, dynamic gadolinium-enhanced FLASH imaging achieved the highest sensitivity, and ferumoxides-enhanced T2*-weighted FLASH imaging was the second most sensitive. We found that ferumoxides-enhanced turbo spin-echo imaging was the least valuable technique for revealing HCC lesions. Gadolinium-enhanced imaging revealed more HCC lesions than did ferumoxides-enhanced imaging, particularly for lesions smaller than 2 cm in diameter. CONCLUSION: Ferumoxides-enhanced imaging revealed fewer findings, such as lesion conspicuity of HCCs arising in cirrhotic livers, than did gadolinium-enhanced FLASH imaging.     

Efficacy of contrast-enhanced MR imaging in cardiomyopathy: an experimental study using Bio14.6 hamsters

RATIONALE AND OBJECTIVES: Myocardial fibrosis was evaluated with magnetic resonance (MR) imaging in Bio14.6 hamsters. MATERIALS AND METHODS: Gated gradient-echo T1-weighted images and spin-echo images with gadopentetate dimeglumine enhancement (0.2 mmol/kg) were obtained. RESULTS: Myocardial enhancement persisted for 13 minutes after administration of gadopentetate dimeglumine, and myocardial signal intensity peaked at 13 minutes on gradient-echo T1-weighted images. The enhanced areas were greater in Bio14.6 hamsters at 25-42 weeks than at 10 weeks. Pathologic data revealed enhancement with inflammation at 10 weeks and fibrosis with vessel proliferation at 25-42 weeks. Pathologic fibrotic change was greater at 32-42 weeks than at 10 weeks. The myocardium of 42-week-old Bio14.6 hamsters showed remarkable contrast enhancement, which continued for 13 minutes. There was no correlation between gadolinium enhancement and pathologic findings in the evaluation of myocardial degeneration and fibrosis. CONCLUSION: Gadolinium-enhanced MR imaging was useful for estimating myocardial fibrotic changes with vessel proliferation and myocardial damage.     

Gadobenate dimeglumine--a new contrast agent for MR imaging: preliminary evaluation in healthy volunteers.

Gadobenate dimeglumine (formerly known as Gd-BOPTA) is a recently developed paramagnetic contrast agent that undergoes biliary as well as renal excretion. It may, therefore, be useful in MR imaging of the liver. Its safety, tolerance, and usefulness in visualizing hepatobiliary structures were studied in eight healthy subjects. Axial abdominal images were obtained with T1-weighted spin-echo and gradient-echo sequences at 1.5 T before and after IV administration of gadobenate dimeglumine in doses of 0.005, 0.05, 0.1, and 0.2 mmol/kg body weight. Two subjects received each dose. Administration of 0.1 mmol/kg resulted in a maximum liver enhancement of 149% on the gradient-echo sequence and of 90% on the T1-weighted spin-echo sequence 60 min after injection. The contrast enhancement of the liver remained virtually constant for 2 hr. The signal-to-noise ratio of the biliary tract increased from 38 to 121 after 2 hr on gradient-echo images. In addition, there was significant contrast enhancement of the kidneys. Optimal visualization of the liver parenchyma was achieved with doses of 0.05 and 0.1 mmol gadobenate dimeglumine/kg. Mild to moderate side effects such as nausea and retching, a sense of warmth at the infusion site, and transient pruritus lasting 1 min were reported by three (38%) of the subjects. The initial results of the first application of gadobenate dimeglumine in humans are encouraging because the contrast agent appears to be reasonably well tolerated at the doses appropriate for hepatobiliary imaging. Further clinical studies of this contrast agent are warranted to assess its effect on liver lesion conspicuity and the frequency with which side effects occur.     

Multishot echo-planar imaging with gadopentetate dimeglumine. Preliminary study of efficacy for detection of hypovascular metastatic liver tumors

OBJECTIVE: To evaluate the usefulness of sequential T2-weighted spin-echo type multishot echo-planar (T2-EP) imaging with gadopentetate dimeglumine for the detection of hypovascular metastatic liver tumors. MATERIAL AND METHODS: Fifteen consecutive patients with 56 proven hypovascular metastatic liver tumors were included in the study. Three observers blindly and independently read the whole-liver images obtained with T2-weighted spin-echo, T2-weighted single-shot fast spin-echo, T1-weighted fast multiplanar spoiled GRASS and T2-EP images obtained before and 25, 60, 90 and 120 s after injection of 0.2 mmol/kg b.w. of gadopentetate dimeglumine. The diagnostic accuracy was estimated by calculating the area under the observer-specific binomial receiver operating characteristics curves (Az). RESULTS: T2-EP images obtained 60 s after contrast injection showed significantly higher contrast-to-noise (C/N) ratios than the other imaging techniques. A combination of all phases of the T2-EP images produced the highest sensitivity and specificity. In terms of the Az value, the diagnostic accuracy for tumor detection achieved with a combination of all phases of the T2-EP images was significantly higher than that with T1-SPGR and T2-SSFSE images (p<0.01). The Az values of the T2-EP images (Az=0.975) were higher than those of T2-CSE images (Az=0.948), but the difference was not significant. CONCLUSION: Our preliminary study revealed that sequential imaging with enhanced T2-EP images was useful for the detection of hypovascular metastatic liver tumors because of its superior C/N ratio and sensitivity.     

Glial neoplasms: dynamic contrast-enhanced T2*-weighted MR imaging.

PURPOSE: To evaluate the role of T2*-weighted echo-planar perfusion imaging by using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood volume (CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy. MATERIALS AND METHODS: MR imaging was performed in 29 patients by using a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV. This information formed the basis for targeting the stereotactic biopsy. Relative CBV values were computed with a nondiffusible tracer model. The relative CBV of lesions was expressed as a percentage of the relative CBV of normal white matter. The maximum relative CBV of each lesion was correlated with the histopathologic grading of astrocytomas obtained from samples from stereotactic biopsy or volumetric resection. RESULTS: The maximum relative CBV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7, with a mean of 5.07 +/- 2.79 (+/- SD), and in the low-grade cohort (n = 3) varied from 0.92 to 2.19, with a mean of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P < .001; Student t test). CONCLUSION: Echo-planar perfusion imaging is useful in the preoperative assessment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invaluable in the precise targeting of the stereotactic biopsy.     

Aggressive fibromatosis of the prevertebral and retropharyngeal spaces: MR and CT characteristics.

A 47-year-old man had aggressive fibromatosis, and CT and MR showed a large, multilobulated soft-tissue mass within the prevertebral and retropharyngeal spaces. On CT, the lesion was slightly higher in attenuation than adjacent muscle; on MR, it was intermediate between muscle and fat on unenhanced T1-weighted images, isointense with fat on intermediate-weighted images, hyperintense relative to fat on T2-weighted images, and markedly enhanced after administration of gadopentetate dimeglumine. Multiple small focal and linear areas of decreased signal intensity that did not enhance with gadopentetate dimeglumine were observed on all pulse sequences.     

Evaluation of the hepatocyte-specific contrast agent gadobenate dimeglumine for MR imaging of acute hepatitis in a rat model

This work was conducted to test the hypothesis that contrast-enhanced MRI with hepatocyte-specific contrast agents facilitates quantitation and mapping of diffuse liver diseases such as hepatitis and cirrhosis. Gadobenate dimeglumine (Gd-BOPTA/Dimeg, Bracco SpA, Milano, Italy) is a new paramagnetic hepatocytespecific contrast agent currently undergoing clinical trials. We have assessed the usefulness of gadobenate dimeglumine for the diagnosis of diffuse liver diseases in a rat model of chemically induced hepatitis. The study was based on the measurements of in vivo liver relaxation times as well as on the acquisition of standard SE images. Acute hepatitis considerably reduced the degree of T1 shortening of liver parenchyma caused by intravenous injection of .25 mmol/kg of gadobenate dimeglumine. Analogously, the enhancement of the MRI signal intensity of the liver of rats with hepatitis observed in T1-weighted spin-echo (SE) images was inferior, in terms of both strength and duration, to that recorded in control rats at doses of .25 mmol/kg and .075 mmol/kg of gadobenate dimeglumine. Our results show that gadobenate dimeglumine enhanced MR imaging has the potential for visualization of hepatitis and for assessment of liver function. Our conclusions differ from those previously published on this subject by other authors. The reasons that led to differing conclusions are discussed.     

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.     

Optimizing brain MR imaging protocols with gadopentetate dimeglumine: enhancement of intracranial lesions on spin-density- and T2-weighted images

To determine whether long TR MR imaging is best performed before or after IV administration of gadopentetate dimeglumine, we obtained spin-density- and T2-weighted images before and after contrast administration in 21 patients with known intracranial enhancing lesions. Of 25 lesions demonstrating enhancement on T1-weighted sequences, 21 showed mild or moderate enhancement on spin-density-weighted sequences and 20 showed mild enhancement on T2-weighted sequences. Importantly, no spin-density or T2 information was obscured by the administration of gadopentetate dimeglumine, and no T2 shortening effects were visible. Two new foci of enhancement were visible on postcontrast spin-density- and T2-weighted images that were missed on postcontrast T1-weighted images and on precontrast spin-density- and T2-weighted studies. Visualization of new areas of enhancement is the main advantage provided by the long TR images obtained after IV injection of gadopentetate dimeglumine. The most likely reason for the appearance of these newly visualized lesions is thought to be delayed enhancement. This imaging protocol also allows the display of adjacent edema or gliosis and enhancing lesions on a single image. Additionally, in three cases, posterior fossa phase-shift artifacts raised the suspicion of an enhancing lesion on postcontrast T1-weighted images, but the cerebellum was shown to be normal on the postcontrast spin-density- and T2-weighted studies. On the basis of our results, we recommend obtaining long TR images after rather than before the administration of gadopentetate dimeglumine in patients with intracranial enhancing lesions.     

Administration of gadopentetate dimeglumine in MR imaging of intracranial tumors: dosage and field strength.

PURPOSE: To investigate the efficacy of 0.025, 0.05 and 0.1 mmol/kg gadopentetate dimeglumine in MR imaging of patients with intracranial tumors at mid and high field strength. METHODS: In 88 patients, an open-label phase III multicenter dose-finding study was performed at 0.5, 1.0, and 1.5 T MR units. Before and after (5, 15, 25 minutes) intravenous administration of gadopentetate dimeglumine, imaging was performed with T1-weighted spin-echo sequences. RESULTS: With 0.1 mmol/kg yielding the highest values, tumor enhancement and numerical tumor/brain contrast showed dose-dependent 5-minute postcontrast values (P less than 0.05). Compared to 5-minute postcontrast values, there was no significant change at 15 and 25 minutes. Although the lowest values of enhancement were found at 0.5 T, differences in enhancement among the field strengths were not statistically significant. The numerical data were confirmed by visual assessment of tumor/brain contrast. Eighty to 90% of cases had diagnostically valuable enhancement at 0.1 mmol/kg, 50% at 0.05 mmol/kg, and 10% at 0.025 mmol/kg (P less than 0.05). There were no adverse events. CONCLUSION: Our results confirm that 0.1 mmol/kg gadopentetate dimeglumine is more effective at enhancing intracranial tumors than lower doses at mid and high field MR units.