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Gastrointestinal Imaging |
1 From the Institute for Radiodiagnostics, Medizinische Fakultät der Humboldt-Universität, Berlin, Germany (J.P., B.H.). Medical and Regulatory Affairs, Bracco SpA, Milan, Italy (G.P., M.A.K., A.S.); Centro di Risonanza Magnetica, Ospedale Torrette, Ancona, Italy (A. Giovagnoni); Departement de Radiologie, Hopital Lariboisière, Paris, France (P.S.); Departement de Radiologie, Hopital Cantonal Universitaire, Geneva, Switzerland (F.T.); Instituto di Radiologia, Ente Ospedaliero di Pisa, Italy (R.L., C.B.); II Servizio di Radiologia, Ente Ospedaliero Spedali Civili, Brescia, Italy (L.G., A.C.); Instituto di Radiologia, Policlinico A. Gemelli, Rome, Italy (R.M., P.M.); Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands (E.L.V.P.v.M., J.L.B.); Department of Radiology, University Hospital Leuven, Belgium (C.P., G.M.); MRI Centre, Princess Grace Hospital, Monaco, Principaute de Monaco (A. Greco, M.T.M.); Ludwig-Maximilians-Universität-München, Institute für Radiologische Klinik, München, Germany (A.H., M.R.); Eberhardt Karls-Universität, Radiologische Universitätsklinik, Abteilung für Radiologische Diagnostik, Tübingen, Germany (M.L., C.C.); and Westfälische Wilhelms-Universität Münster, Institute für Klinische Radiologie, Münster, Germany (H.E.D., E.R.). Received Oct 12, 1998; revision requested Dec 11; final revision received Oct 8, 1999; accepted Oct 17. Address correspondence to A.S., Bracco SpA, Medical and Regulatory Affairs, Via Egidio Folli 50, 20134 Milan, Italy (e-mail: aspinazzi@bracco.it).
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Abstract |
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 TOP Abstract IntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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MATERIALS AND METHODS: In 126 of 214 patients, MR imaging was performed before Gd-BOPTA administration, immediately after bolus administration of a 0.05- mmol/kg dose of Gd-BOPTA, and 60–120 minutes after an additional intravenously infused 0.05-mmol/kg dose. In 88 patients, imaging was performed before and 60–120 minutes after a single, intravenously infused 0.1-mmol/kg dose. T1- and T2-weighted spin-echo and T1-weighted gradient-echo images were acquired. On-site and blinded off-site reviewers prospectively evaluated all images. Intraoperative ultrasonography, computed tomography (CT) during arterial portography, and/or CT with iodized oil served as the reference methods in 110 patients.
RESULTS: Significantly more lesions were detected on combined pre- and postcontrast images compared with on precontrast images alone (P < .01). All reviewers reported a decreased mean size of the smallest detected lesion and improved lesion conspicuity on postcontrast images. All on-site reviewers and two off-site reviewers reported increased overall diagnostic confidence (P < .01). Additional lesion characterization information was provided on up to 109 (59%) of 184 delayed images and for up to 50 (42%) of 118 patients in whom dynamic images were assessed. Gd-BOPTA would have helped change the diagnosis in 99 (47%) of 209 cases and affected patient treatment in 408 (23%) of 209 cases.
CONCLUSION: Gd-BOPTA increases liver lesion conspicuity and detectability and aids in the characterization of lesions.
Index terms: Contrast media • Gadobenate dimeglumine • Liver neoplasms, 76.316, 76.32, 76.33 • Liver neoplasms, MR, 76.121411, 76.121412, 76.121416, 76.12143 • Magnetic resonance (MR), contrast media, 76.12143 • Magnetic resonance (MR), phase imaging, 76.121411, 76.121412, 76.121416, 76.12143
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Introduction |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Despite the advent of fast imaging techniques, magnetic resonance (MR) imaging is used mainly in critical cases, such as when US and/or CT are not fully definitive in terms of the number and location of liver lesions or when the differential diagnosis of selected liver lesions may affect subsequent patient treatment. Given this background, any diagnostic clues that are independent of and additional to those obtained with nonenhanced MR imaging are of benefit. A possible solution is the use of liver-specific MR contrast materials—that is, agents targeted to either the hepatocytes or the Kupffer cells.
Gadobenate dimeglumine (MultiHance; Bracco SpA, Milan, Italy) is a sterile, intravenously injected contrast material proposed for use in MR imaging of focal liver disease. The active ingredient of gadobenate dimeglumine, Gd-BOPTA, is an octadentate chelate of the paramagnetic ion gadolinium. In animal studies (15,16), this agent has been shown to be different from other available gadolinium chelates in that it not only is distributed to the extracellular fluid space, but thanks to a chain containing a benzene ring on the chelate, also is selectively taken up by hepatocytes and excreted into the bile by the so-called canalicular, multispecific organic anion transporter. In humans, gadobenate dimeglumine (Gd-BOPTA) couples specific, long-lasting enhancement of MR signal intensity in the liver parenchyma with the plasma kinetics of agents targeted to the extracellular fluid space—the so-called extracellular fluid contrast agents (17). In previous studies (17,18) of the pharmacokinetics and biodistribution of Gd-BOPTA in humans, 2%–4% of the injected dose has been shown to be excreted through the biliary route. Given these unique properties, the present study was aimed at evaluating the extent to which Gd-BOPTA improves liver lesion detection in delayed MR imaging and at assessing its potential for use in bolus dynamic MR imaging for the characterization of liver lesions in patients with known or suspected primary or secondary liver cancer.
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MATERIALS AND METHODS |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Patients
After the approval of the local ethics committee at each study center, 214 patients (126 men, 88 women; mean age, 59.6 years; age range, 22.0–83.0 years) were enrolled and received the test contrast material. Each patient gave written or witnessed informed consent and was evaluated for eligibility. The patients were included in the study if they were older than 18 years and had been referred for MR imaging for the diagnosis or follow-up of suspected or known focal liver lesions. Women of child-bearing potential were required to be using a safe contraceptive method or to have had a negative pregnancy test within 7 days of the injection of the test compound.
The exclusion criteria in the study were as follows: patients undergoing the procedure in an emergency situation, patients with a history of hypersensitivity to any metals and/or chelates of gadolinium, patients treated with any other intravenous contrast material within the 48 hours preceding the MR examination, patients with congestive heart failure (New York Heat Association class III or IV), patients with severely impaired renal or liver function, patients with a body weight of more than 145 kg or with any contraindication to MR imaging (eg, pacemaker, claustrophobia), or patients with any medical condition that would substantially decrease the chances of obtaining reliable data—for example, drug dependence or psychiatric disorders.
Each patient was required to undergo a reference-standard examination. Because the best method to confirm imaging findings—that is, pathologic confirmation—was unavailable in the majority of patients in this study, intraoperative US, CTAP, and/or CT with iodized oil (Lipiodol; Laboratoire Guerbet, Aulnay-sous-Bois, France) were used as the next best examinations to determine the number and location of lesions (standard-of-reference procedures). Specifically, intraoperative US was performed in patients referred for surgical resection of a primary abdominal malignancy, intraoperative US and/or CTAP was performed in patients with colorectal cancer or endocrine tumor detected at MR imaging, and CT with iodized oil was performed in patients referred for chemoembolization of a primary liver tumor. In those cases in which multiple reference-standard procedures were performed, the intraoperative US findings took precedence, followed by the CT with iodized oil and then the CTAP findings. In all cases, the reference-standard method was assumed to have demonstrated the definitive number and location of lesions per patient, as well as the size of the smallest lesion identified.
A total of 125 reference-standard examinations were performed in 110 patients. Of these, 14 patients underwent an intraoperative US examination and a CTAP examination, and one patient underwent an intraoperative US examination and a CT with iodized oil examination. In all, 60 patients underwent intraoperative US as the definitive examination, 40 underwent CT with iodized oil as the definitive examination, and 10 underwent CTAP as the definitive examination. The intraoperative US and CT with iodized oil examinations were completed 1–14 days after Gd-BOPTA administration, whereas the CTAP examinations were performed either 2–7 days before or 1–14 days after Gd-BOPTA administration.
Each examination was performed according to routine procedures at each study center, and each study was assessed by experienced on-site reviewers, who recorded the number of lesions, if present, in each liver segment (segments 1–8) and the size of the smallest lesion depicted in each segment. Each lesion detected by using the reference-standard examination was drawn on liver maps for subsequent lesion tracking among the MR imaging assessments by the three off-site readers.
Contrast Material
All patients were administered a 0.2 mL/kg dose of a 0.5 mol/L solution of Gd-BOPTA—in 88 patients with a single 10 mL/min intravenous infusion (monophasic dose regimen) and in 126 patients, in which dynamic imaging was performed, with a biphasic intravenous injection of half the dose in a bolus (administered manually at 2 mL/sec) followed by the other half in a slow, 10 mL/min infusion (biphasic dose regimen). In both cases, the total dose corresponded to 0.1 mmol/kg Gd-BOPTA.
Imaging
All imaging centers were equipped with either midfield-strength (0.5-T) or high-field-strength (1.0–1.5-T) MR imaging units. Each patient underwent two MR imaging examinations, one before and the other 60–120 minutes after the administration of Gd-BOPTA. The window for the delayed acquisitions was selected on the basis of results of previous clinical testing of the agent, which showed that both the signal-to-noise and the contrast-to-noise ratios increase in a dose- and time-related manner, with maximum and constant liver parenchymal signal intensity enhancement observed between 40–60 and 120 minutes after contrast material administration (17–19). In the present study, T1-weighted spin-echo images, conventional or fast T2-weighted spin-echo images, and T1-weighted gradient-echo images were obtained in each examination. The imaging parameters differed among the centers because of the different MR hardware available but were nevertheless kept constant throughout each study. The following parameters were used: for T1-weighted spin-echo sequences, 280–600/12–17 (repetition time msec/echo time msec), four signals acquired, a 128–224 x 256 matrix, and a 300–500 x 300–500 field of view; for conventional T2-weighted spin-echo sequences, 2,000–3,000/90–130, two signals acquired, a 128–192 x 256 matrix, and a 300–500 x 300–500 field of view; for fast T2-weighted spin-echo sequences, 
4,000/70–200, four or more signals acquired, a 128–192 x 256 matrix, and a 300–500 x 300–500 field of view; for T1-weighted gradient-echo sequences, 45–150/4–12, a 45°–80° flip angle, one to two signals acquired, a 128–256 x 256 matrix, and a 300–500 x 300–500 field of view. For all sequences, the field of view was tailored to the patient's size, and in each case a mean section thickness of 8–10 mm was used.
The patients who received the biphasic dose regimen underwent dynamic MR imaging of the liver during the arterial (15–45-second), portal venous (60–90-second), and delayed (3–5-minute) phases, after the initial bolus administration of 0.05 mmol/kg Gd-BOPTA, with breath-hold T1-weighted gradient-echo sequences. Rather than perform dynamic imaging of the entire liver, the dynamic imaging in the present study was targeted at one or more lesions that were previously identified at precontrast MR imaging or contrast material–enhanced CT. One to five sections were imaged in dynamic acquisitions for preliminary assessment of the potential of Gd-BOPTA for lesion characterization.
Evaluation
Experienced, blinded on-site investigators who were not involved in the assessment of the MR images evaluated the standard-of-reference images in terms of the presence or absence of disease, the actual number and location of lesions, and the size of the smallest lesion depicted. The segmental anatomy of the liver according to Couinaud and Bismuth (20,21), an eight-segment partition system widely used for liver resections, was used to localize the lesions detected by using MR imaging and the standard-of-reference procedures to best guide the matching between the MR imaging and standard-of-reference findings.
The MR images were rated in terms of lesion detection and characterization by the principal investigator at each study center, who was blinded to the results of the standard-of-reference imaging procedures, and by three independent, experienced radiologists (A.G., P.S., F.T.), who were blinded to all clinical data and the results of all the other imaging procedures, including the standard-of-reference examinations.
The MR image sets were evaluated in four groups of reading sessions, which were conducted both on site and off site. First, to avoid any bias from prior expectations, all precontrast image sets were read separately from the 60–120-minute postcontrast sets, with separate randomization schedules assigned to the order in which the two image sets were read. Second, the two image sets were read jointly to assess the diagnostic performance achieved by combining the precontrast images with the postcontrast ones. Third, the pre- and postcontrast images were assessed in matched pairs to directly compare the quality of the precontrast images with the quality of the postcontrast images. Finally, the fourth reading session was performed to assess the diagnostic information contained on the contrast-enhanced images from the dynamic studies. No assessment was performed on images that were considered to be technically inadequate. Furthermore, patients were excluded from the final analysis if either all their precontrast or all their delayed postcontrast images were considered to be technically inadequate.
To minimize the risk of multiple counts, lesions were counted only in those patients with eight or fewer lesions at standard-of-reference examination. The size of the smallest detectable lesion was recorded. The reviewer's confidence in lesion detection was rated according to the following five-point scale: 1, definitely present; 2, probably present; 3, undetermined; 4, probably absent; and 5, definitely absent.
Because histologic data were not available for all patients, the accuracy of the MR imaging examination for lesion characterization was not assessed. However, to obtain preliminary information on the potential of Gd-BOPTA for lesion characterization, each off-site reviewer was asked to evaluate each lesion according to the following seven-point scale: 1, definitely nonsolid; 2, probably nonsolid; 3, undetermined; 4, probably solid; 5, definitely solid; 6, probably regenerating nodule; and 7, definitely regenerating nodule. Image evaluation was in all cases performed by each reviewer in the absence of specific guidelines. Hence, regenerating nodules were differentiated from other focal lesions on the basis of the established criteria for such lesions—that is, a low-signal-intensity appearance on precontrast T2-weighted spin-echo and T1-weighted gradient-echo images when such nodules contain iron deposits or a low-signal-intensity appearance on T2-weighted spin-echo images and isointensity on T1-weighted gradient-echo images when such lesions do not contain iron deposits (22). In the absence of defined enhancement patterns for regenerating nodules on the images obtained 60-120 minutes after the administration of Gd-BOPTA, the evaluation of these images was based exclusively on the opinions of the three reviewers.
Lesion characterization was evaluated also in terms of enhancement pattern and whether, in the opinion of the off-site reviewers, the postcontrast MR images provided additional information for lesion diagnosis.
The total number of detected lesions, the sensitivity for lesion detection (calculated on the basis of lesion-by-lesion matching with reference-standard findings by using the Couinaud-Bismuth liver segmentation system), and the assessor's confidence in detecting or excluding liver lesions were the primary efficacy end points. No attempt was made to determine the specificity for lesion detection, because there were no patients without lesions in this study—that is, there were no true-negative lesions at standard-of-reference examination.
The principal on-site investigators, who were fully aware of the pertinent clinical information, the results of all the imaging-based diagnostic procedures, and the subsequent patient treatment, were also required to assess the diagnostic and therapeutic effect of Gd-BOPTA–enhanced MR imaging. To accomplish this, the evaluations were performed during the matched pairs assessment of overall diagnostic confidence, lesion detectability and delineation, and visibility of internal lesion morphology. To assess overall diagnostic confidence, the following three-point scale was used: -1, better confidence on precontrast images; 0, equal confidence on pre- and postcontrast images; and +1, better confidence on postcontrast images. To assess lesion detectability and delineation and visibility of internal lesion morphology, the following five-point scale was used: -2, substantially worse on postcontrast images than on precontrast images; -1, slightly worse on postcontrast images; 0, comparable on post- and precontrast images; +1, slightly better on postcontrast images; and +2, substantially better on postcontrast images. Furthermore, assessments (expressed as "yes" or "no") were made as to whether Gd-BOPTA facilitated the acquisition of additional information that led to a change in diagnostic conclusions and as to whether and how, in the opinion of the principal investigators, Gd-BOPTA theoretically could have affected a change in patient treatment.
The statistical analysis plan for the study, as drawn up by a qualified clinical trials statistician, was finalized before the completion of data processing. The per-patient difference between the total number of lesions detected by using precontrast MR images alone and the total number of lesions detected on all the available pre- and postcontrast images was tested by using the Wilcoxon signed rank test. Similarly, the matched pairs assessment of diagnostic confidence was summarized on a per-patient basis and tested by using the nonparametric sign test. Finally, to test for the significance of changes in sensitivity between pre- and postcontrast imaging, inferential statistics were applied by using the McNemar test with one degree of freedom. All statistical tests were performed by using SAS, version 6 software (SAS/STAT User's guide, version 6; SAS Institute, Cary, NC).
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RESULTS |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Efficacy
The on-site reviewers examined 214 patients and detected a total of 352 lesions on the technically adequate T1- and T2-weighted precontrast MR images, 375 lesions on the postcontrast MR images, and 396 lesions on the combined pre- and postcontrast image sets (a significantly greater number compared with the number of lesions detected on the precontrast images alone; P = .001). Overall, lesions were detected in 183 (85.5%) patients when the precontrast images alone were assessed and in 204 (95.3%) patients when the combined pre- and postcontrast image sets were assessed (9.8% more patients than those with lesions detected when the precontrast images alone were assessed). The three off-site reviewers detected lesions in 166, 166, and 175 patients, respectively (Table 2). In each case, significantly more lesions were detected on the combined data sets that consisted of both pre- and postcontrast images (P < .01).
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The on-site reviewers indicated a preference for either the precontrast images or the postcontrast images in 146 patients. They reported having increased diagnostic confidence in lesion detection or exclusion on the postcontrast images in 111 (52%) patients and decreased confidence on the postcontrast images in 35 (16%) patients. Of the pre- and postcontrast image sets in the remaining 68 patients, 65 (30%) were judged to yield equivalent diagnostic confidence, whereas in three patients, a matched pair assessment was not applicable. The postcontrast increase in diagnostic confidence was significant (P < .01).
In the matched pairs assessment, off-site reviewers 2 and 3 reported having increased overall diagnostic confidence in the detection or exclusion of lesions on the postcontrast images in 89 (42%) of 210 and in 81 (39%) of 208 cases, respectively; in an additional 92 (44%) and 88 (42%) cases, respectively, their overall diagnostic confidence was equivalent on the pre- and postcontrast images, and in the remaining 29 (14%) and 39 (19%) cases, respectively, their overall diagnostic confidence was higher at precontrast imaging than at postcontrast imaging. For off-site reviewer 1, the corresponding numbers were 59 (28%) of 209 cases for greater diagnostic confidence at postcontrast imaging than at precontrast imaging, 100 (48%) of 209 cases for equal diagnostic confidence at pre- and postcontrast imaging, and 50 (24%) of 209 cases for greater diagnostic confidence at precontrast imaging, respectively. The change in diagnostic confidence was significant for off-site reviewers 2 and 3 (P < .01), but not for reviewer 1 (P = .44) (Fig 3).
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Lesion Characterization
The lesion types were evaluated only in those lesions that were given confidence scores of definitely present, probably present, or undefinable, and included data from only those patients with no more than eight lesions on the pre- and postcontrast images (n = 184 for on-site readings; n = 166, 166, and 175 for off-site reviewers 1, 2, and 3, respectively).
For the on-site reviewers and for off-site reviewers 2 and 3, there was a clear trend toward a smaller number of undetermined lesion types on the Gd-BOPTA–enhanced images (Table 4). However, for off-site reviewer 1, an opposite trend was apparent. The results with both spin-echo and gradient-echo sequences were comparable.
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Finally, the principal investigators at each study center reported that Gd-BOPTA administration would have facilitated a change in patient treatment in 48 (23%) of 209 evaluated cases. Although the manner in which these changes were reported varied among the different centers, the changes essentially involved the following: the cancellation of a previously planned surgery owing to the detection of additional lesions (17 patients, 8% of evaluated cases), the cancellation of a previously planned surgery owing to the postcontrast exclusion of a lesion or lesions previously depicted on nonenhanced images (four patients, 2% of evaluated cases), the commencement of some form of nonsurgical treatment (ie, chemotherapy or percutaneous ethanol injection) (15 patients, 7% of evaluated cases), and/or the recommendation for surgical resection (12 patients, 6% of evaluated cases).
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DISCUSSION |
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TOPAbstractIntroductionMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Contrast materials that are distributed to the interstitial compartment are the least suitable for lesion detection because they affect both the normal liver parenchyma and the lesion equally. With these agents, the lesion-to-liver contrast increases only in the nonequilibrium phase of perfusion, and for this reason, only fast dynamic imaging is of any benefit. A well-known example of this type of contrast material is gadopentetate dimeglumine.
Particulate contrast materials that are cleared from the circulation by the reticuloendothelial system (ie, Kupffer cells) promise a more liver-specific approach, because it is uncommon for hepatic tumors to exhibit phagocytic activity. Thus, various compounds have been developed and tested—for example, iron oxide- containing substances (24,25). Because of the higher rate of adverse reactions with these agents, however, they tend to be administered by means of a slow drip infusion that renders them unsuitable for use with dynamic imaging (26).
The hepatobiliary pathway is the third contrast material distribution approach. Paramagnetic agents with hepatocellular uptake and biliary excretion have great potential as contrast materials for MR imaging of the liver (27). One such example, manganese dipyroxyl diphosphate, has been shown to enhance lesion-to-liver contrast and have a duration of contrast enhancement that is considerably longer than that obtained after the injection of extracellular fluid contrast materials such as gadopentetate dimeglumine. Although this allows a slow and presumably safer infusion of the contrast material (28), in more recent studies it has been shown that manganese dipyroxyl diphosphate partially dissociates in the liver (29). Another contrast material aimed at the hepatocytes that has been shown to sufficiently increase tumor-liver contrast is gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (30). Despite almost 50% biliary excretion (31), this agent may nevertheless be of use in dynamic studies (26).
Gd-BOPTA is the first gadolinium-based agent that, after an initial distribution to the interstitial compartment, is specifically taken up by functioning hepatocytes (17,18). The results of previous testing have shown that the liver-specific distribution of Gd-BOPTA yields an increase in liver-lesion contrast that is comparable to that obtained after the injection of manganese dipyroxyl diphosphate (32). In the present study, both the on-site and the off-site reviewers detected more lesions after the administration of Gd-BOPTA, and there was a concomitant, significant increase in MR imaging sensitivity when the pre- and postcontrast image sets were assessed together. That two of the three off-site reviewers also had greater overall diagnostic confidence at Gd-BOPTA–enhanced imaging was indicative of an increase in lesion conspicuity. This, combined with the fact that the three off-site reviewers also noted a decrease in the size of the smallest detectable lesion after Gd-BOPTA administration, is further evidence of the increased lesion conspicuity and detectability with Gd-BOPTA.
With regard to differential diagnosis, there was not only a decrease in the number of "undetermined" cases at postcontrast delayed phase imaging, but also a higher number of lesions with more information about the internal morphology on the postcontrast images than on the precontrast images. Although the washout from some lesions may be slower than that from others, with the result being a longer retention of contrast material, a clear benefit may arise from the fact that metastases, cysts, hemangiomas, and other lesions do not contain functioning hepatocytes and thus cannot retain the agent and show delayed enhancement. Our study results suggest that the liver-lesion enhancement patterns observed on delayed phase images provide important information in addition to that obtained with dynamic imaging, which essentially reveals only the perfusion status and homogeneity of a lesion.
The use of Gd-BOPTA combined with the bolus dynamic imaging technique yielded additional information about lesion characterization in up to 42% of patients in whom dynamic images were assessed. This percentage is comparable to those reported for dynamic contrast-enhanced MR imaging with bolus administration of 0.1 mmol/kg of gadopentetate dimeglumine (33) and demonstrates that it is possible to target a contrast material to the liver without losing any dynamic imaging capability.
This report summarizes the results of a phase III clinical trial aimed at assessing the efficacy of Gd-BOPTA for dynamic and delayed MR imaging of the liver. Although the results presented provide preliminary information about the diagnostic efficacy of Gd-BOPTA for liver imaging, the limitations of the study are that no data are available regarding the specificity of MR imaging with this agent for lesion detection and that no attempt was made to assess the accuracy of the lesion characterization data for this particular patient population or the accuracy of the diagnostic conclusions made by the principal investigators. Although past experiences with this agent suggest otherwise (18,34), the absence of data on the specificity for lesion detection in this study might lead one to speculate that the increased numbers of lesions seen on delayed postcontrast images occur at the expense of reduced specificity. Given these limitations, further work to define more precisely and extensively the usefulness of Gd-BOPTA in liver imaging to detect and characterize focal lesions is clearly necessary.
In conclusion, the results of the present study indicate that Gd-BOPTA can be used not only as a standard extracellular contrast material for dynamic imaging of the liver but also as a liver-specific agent for the acquisition of delayed phase images. A possible limitation of this approach is the time- and cost-consuming necessity of a third, delayed image in addition to the conventional pre- and postcontrast dynamic studies. However, the fact that delayed imaging often yields additional diagnostic information without limiting the efficacy of the contrast material on fast dynamic images makes Gd-BOPTA a valuable all-purpose agent for the screening of primary and secondary liver cancer.
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Footnotes |
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Author contributions: Guarantor of integrity of entire study, A.S.; study concepts and design, A.S., G.P.; definition of intellectual content, A.S.; literature research, J.P., M.A.K.; clinical studies, R.L., C.B., L.G., A.C., R.M., P.M., E.L.V.P.v.M., J.L.B., C.P., G.M., A. Greco, M.T.M., A.H., M.R., M.L., C.C., H.E.D., E.R., B.H.; data acquisition, A. Giovagnoni, P.S., F.T.; data analysis, A.S., G.P., M.A.K.; statistical analysis, A.S., G.P.; manuscript preparation, J.P., M.A.K., G.P.; manuscript editing, M.A.K.; manuscript review, A.S., G.P., M.A.K.
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A. Huppertz, T. Balzer, A. Blakeborough, J. Breuer, A. Giovagnoni, G. Heinz-Peer, M. Laniado, R. M. Manfredi, D. G. Mathieu, D. Mueller, et al. Improved Detection of Focal Liver Lesions at MR Imaging: Multicenter Comparison of Gadoxetic Acid-enhanced MR Images with Intraoperative Findings Radiology, January 1, 2004; 230(1): 266 - 275. [Abstract] [Full Text] [PDF]
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C. M. Pastor, C. Planchamp, S. Pochon, V. Lorusso, X. Montet, J. Mayer, F. Terrier, and J.-P. Vallee Kinetics of Gadobenate Dimeglumine in Isolated Perfused Rat Liver: MR Imaging Evaluation Radiology, October 1, 2003; 229(1): 119 - 125. [Abstract] [Full Text] [PDF]
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C. Del Frate, M. Bazzocchi, K. J. Mortele, C. Zuiani, V. Londero, G. Como, R. Zanardi, and P. R. Ros Detection of Liver Metastases: Comparison of Gadobenate Dimeglumine-enhanced and Ferumoxides-enhanced MR Imaging Examinations Radiology, December 1, 2002; 225(3): 766 - 772. [Abstract] [Full Text] [PDF]
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A. Kawashima, C. M. Sandler, F. M. Corl, O. C. West, E. P. Tamm, E. K. Fishman, and S. M. Goldman Imaging of Renal Trauma: A Comprehensive Review RadioGraphics, May 1, 2001; 21(3): 557 - 574. [Abstract] [Full Text] [PDF]
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G. Pirovano, A. Vanzulli, L. Marti-Bonmati, L. Grazioli, R. Manfredi, A. Greco, N. Holzknecht, H. E. Daldrup-Link, E. Rummeny, B. Hamm, et al. Evaluation of the Accuracy of Gadobenate Dimeglumine-Enhanced MR Imaging in the Detection and Characterization of Focal Liver Lesions Am. J. Roentgenol., October 1, 2000; 175(4): 1111 - 1120. [Abstract] [Full Text] [PDF]
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L. Grazioli, G. Morana, M. P. Federle, G. Brancatelli, M. Testoni, M. A. Kirchin, K. Menni, L. Olivetti, N. Nicoli, and C. Procacci Focal Nodular Hyperplasia: Morphologic and Functional Information from MR Imaging with Gadobenate Dimeglumine Radiology, December 1, 2001; 221(3): 731 - 739. [Abstract] [Full Text] [PDF]
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