Gadopentetate Dimeglumine-enhanced MR Imaging Research Articles

Hepatic pseudolymphoma: imaging features on dynamic contrast-enhanced MRI and diffusion-weighted imaging.

To investigate dynamic contrast-enhanced (DCE) MR findings and diffusion-weighted imaging (DWI) characteristics of hepatic pseudolymphoma. The MR data of 20 lesions in 14 patients with histopathologically proven hepatic pseudolymphoma were retrospectively analyzed. All patients underwent dynamic gadopentetate dimeglumine-enhanced MR imaging and DWI. Morphologic characteristics and signal features on T1- and T2-weighted images (T1WI, T2WI), and DCE pattern were qualitatively evaluated. The quantitative analysis was performed for the size, the degree of enhancement on arterial phase, signal intensity (SI) of DWI, and apparent diffusion coefficient (ADC) values. The Wilcoxon signed ranks test was used for statistical analysis. The contour of all lesions was round. The lesion size was 0.7-2.8cm (mean 1.3±0.5cm). All lesions manifested as homogeneous hypointensity on T1WI and hyperintensity on T2WI. All lesions were shown as hypervascular with various enhancement patterns on DCE MR imaging. The presence of peripheral enhancement and pseudocapsule was observed in 7 and 4 lesions, respectively. SI of the hepatic pseudolymphoma was significantly lower than that of portal vein on arterial phase (P<0.001) and the ADC was significantly lower than that of spleen (P=0.012). A homogeneous nodule with small size (<2cm), manifestation of hypervascular with lower SI than that of portal vein on arterial phase and lower ADC values than that of spleen are the common MR features of hepatic pseudolymphoma.

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

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. Thirteen rabbits with experimentally induced VX2 carcinomas in the thighs underwent sequential T1-weighted enhancement MR imaging using a 3.0T MR imager, first with gadopentetate dimeglumine, and then 24 (n=4) or 4h (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 24h 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. The time-to-peak PE for gadopentetate dimeglumine was 1min and gadopentetate dimeglumine showed a rapid washout pattern. The time-to-peak PE for gadofluorine M was 30min and gadofluorine M showed a plateau enhancement pattern for up to 24h. 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. Gadofluorine M showed strong and plateau enhancement of tumors for up to 24h. In the reader study, gadofluorine M showed better conspicuity for VX2 tumors than gadopentetate dimeglumine, but had a similar sensitivity.

Value of FDG positron emission tomography in conjunction with MR imaging for evaluating therapy response in patients with musculoskeletal sarcomas.

The purpose of our study was to investigate the potential of FDG positron emission tomography (PET) to distinguish viable tumor from changes caused by therapy in areas with equivocal MR imaging findings in patients with musculoskeletal sarcomas. We evaluated 12 patients (nine males, three females; age range, 9-56 years; mean age, 25 years) with a history of bone or soft-tissue sarcoma who had undergone various treatments (surgery, chemotherapy, radiation therapy, or a combination of treatments) and who presented with clinically suspected recurrent or residual tumor. All patients underwent gadopentetate dimeglumine-enhanced MR imaging and whole-body FDG PET. Imaging results were correlated with histologic findings or with clinical findings from long-term follow-up. In nine patients, MR imaging findings were equivocal in differentiating between posttherapeutic changes and tumor recurrence. FDG PET images showed increased uptake, suggestive of recurrent tumor, in five patients. These findings were confirmed by biopsy. Four patients showed no increased uptake on FDG PET and were closely monitored clinically. No tumor recurrence was found in these patients. One patient showed MR imaging findings suggestive of recurrent tumor that was confirmed on FDG PET and at histology. Two patients underwent a limb salvage procedure before MR imaging, but MR images were deemed inadequate for interpretation because of extensive metallic artifacts. FDG PET was helpful in evaluating these patients for tumor recurrence. FDG PET is a useful adjunct to MR imaging in distinguishing viable tumor from posttherapeutic changes in patients with bone and soft-tissue sarcomas.

Using relative cerebral blood flow and volume to evaluate the histopathologic grade of cerebral gliomas: preliminary results.

Relative cerebral blood flow has rarely been studied as part of the preoperative assessment of tumor grade, although relative cerebral blood volume is known to be useful for this assessment. The purpose of our study was to determine the usefulness of relative cerebral blood flow in assessing the histopathologic grade of cerebral gliomas. MR imaging was performed in 17 patients with proven cerebral gliomas (11 high-grade gliomas and six low-grade gliomas), using a first-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion sequence. The perfusion data were deconvoluted with an arterial input function, using singular value decomposition to obtain a color map of relative cerebral blood volume and flow; the relative cerebral blood volume and flow ratios were expressed relative to values measured in the contralateral white matter. The Wilcoxon's rank sum test was performed to test the difference between the mean of the relative cerebral blood volume (or flow) ratio in high-grade gliomas and that in low-grade gliomas. Receiver operating characteristic curve analysis was used to evaluate the association between the relative cerebral blood volume (or flow) ratio and the grade of the glioma, as well as to calculate the relative cerebral blood volume and flow ratio cutoff value permitting discrimination between high- and low-grade gliomas. The correlation between relative cerebral blood volume and flow ratios was evaluated using Spearman's rank correlation analysis. We also made a qualitative assessment regarding the match or mismatch of areas of maximal contrast enhancement with the areas of highest color perfusion maps. The mean of the relative cerebral blood volume ratio was 4.91 in the high-grade gliomas and 2.00 in the low-grade gliomas. The mean relative cerebral blood flow ratio was 4.82 in the high-grade gliomas and 1.83 in the low-grade gliomas. A significant difference in each relative cerebral blood volume and flow ratio was found between the high- and low-grade gliomas (Wilcoxon's rank sum test, p < 0.05). Both the relative cerebral blood volume and flow ratios strongly matched the grade of the glioma, but the difference between the two areas was not significant (receiver operating characteristic curve analysis, p > 0.05). The desired cutoff value was 2.93 in the relative cerebral blood volume ratio and 3.57 in the relative cerebral blood flow ratio. Additionally, there was a strong correlation between the relative cerebral blood volume and flow ratios (Spearman's rank correlation coefficient = 0.762; p < 0.05). There was frequent mismatch (33%) between the qualitative assessment of the contrast-enhanced T1-weighted MR images and the perfusion maps. First-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion MR imaging is useful for the preoperative assessment of tumor grade. A relative cerebral blood flow ratio, in addition to a relative cerebral blood volume ratio, can be a useful tool in the evaluation of the histopathologic grade of cerebral gliomas.

MR imaging of enhancing intraosseous disk herniation (Schmorl's nodes).

This study was conducted to show vascularization of Schmorl's nodes with enhanced MR imaging and to correlate this finding with clinical complaints. Retrospectively, 412 gadopentetate dimeglumine-enhanced MR imaging examinations of the lumbar and thoracic spine of 372 patients were reviewed for Schmorl's nodes, vascularization of Schmorl's nodes, and associated bone marrow edema. Sagittal T2-weighted spin-echo and unenhanced and enhanced T1-weighted spin-echo images with and without fat suppression were evaluated in symptomatic and asymptomatic patients. Of the 372 patients, 142 (38%) had 341 Schmorl's nodes. Gadopentetate dimeglumine-enhanced MR imaging revealed vascularized tissue in 30 Schmorl's nodes of 23 patients (mean age of patients, 53 years old). Associated bone marrow edema was found in nine of 30 vascularized Schmorl's nodes. The mean diameter (8.2 mm) of the nine vascularized Schmorl's nodes that were surrounded by bone marrow edema was significantly (p < .05) greater than the mean diameter (6.4 mm) of the 21 vascularized Schmorl's nodes that had no bone marrow edema. The vascularized Schmorl's nodes were significantly (p < .05) smaller in the seven asymptomatic patients (mean, 5.2 mm) than in the 23 patients with back pain (mean, 7.9 mm). We saw bone marrow edema adjacent to Schmorl's nodes less frequently in asymptomatic patients (one of seven) than in symptomatic patients (10 of 23). Vascularized Schmorl's nodes were larger and more frequently associated with bone marrow edema in patients with back pain than in asymptomatic patients. Enhanced MR images of Schmorl's nodes revealed vascularity, which was not shown on unenhanced MR images.

Gadopentetate dimeglumine-enhanced MR imaging of subdural hematoma in an abused infant.

Gadopentetate dimeglumine-enhanced MR imaging of subdural hematoma in an abused infant.

Dynamic gadopentetate dimeglumine-enhanced MR imaging of hepatocellular carcinoma

Nineteen patients with 28 histologically proven hepatocellular carcinomas (HCCs) were examined using T1- and T2-weighted spin-echo sequences and dynamic gadopentetate dimeglumine-enhanced magnetic resonance imaging (MRI) performed by fast T1-weighted gradient-echo sequence (100/5/80°) which was performed before and repeatedly (12 sets of images) after intravenous bolus injection of gadopentetate dimeglumine (Gd-DTPA) over a period of 10 min. Enhancement of HCC was heterogeneous in 24 lesions (85.7%). Intra-lesional non-enhancing areas were seen in 18 cases (64%). A late-enhancing pseudocapsule was seen in 12 lesions (42.9%). In addition, two groups were distinguished in the examined HCCs: 16 lesions (57.1%) showed stronger enhancement compared to liver parenchyma with maximum positive lesion-to-liver contrast on the 15-s images, while 12 lesions (42.9%) had an enhancement less than normal liver with a maximum negative contrast on the 15-s images. We conclude that the morphologic features most frequently encountered in HCC on dynamic Gd-DTPA-enhanced MRI are inhomogeneity of enhancement, intra-lesional non-enhancing areas, and relatively late enhancement of a pseudocapsule. Taking the degree of enhancement to be representative of the degree of vascularity, we also conclude that HCC can appear either hypervascular or hypovascular in the early phase of the dynamic study.

Acute fracture of the femoral neck: assessment of femoral head perfusion with gadopentetate dimeglumine-enhanced MR imaging.

Evaluation of the perfusion and viability of the femoral head after fracture of the femoral neck is important because the outcome of conservative treatment or joint-preserving surgery is adversely affected by the development of capital osteonecrosis. We evaluated the use of MR imaging, before and after IV administration of gadopentetate dimeglumine, for assessing perfusion of the femoral head in 13 patients with acute fracture of the femoral neck. Multiecho (1600/30-240 [TR/TE]) MR images were obtained before contrast administration and gradient-echo (315/14, 90 degrees flip angle) MR images were obtained both before and after contrast administration. MR findings were correlated with findings on superselective digital subtraction angiograms of the vessels supplying the femoral head and with clinical-radiographic follow-up for at least 12 months. Digital subtraction angiography showed impaired blood supply to the femoral head in five patients. On contrast-enhanced MR images of these patients, the femoral head did not enhance and was lower in signal intensity than were the enhancing femoral shaft and neck distal to the fracture and the enhancing femoral head on the unaffected side. In the patients with persistent perfusion, contrast-enhanced MR images showed a uniform increase in signal intensity in the femoral shaft and neck as well as the femoral head; the femoral head on the fractured side showed contrast enhancement similar to that on the healthy side. These preliminary results indicate that contrast-enhanced MR imaging may be useful for noninvasive evaluation of femoral head perfusion after fracture of the femoral neck. MR findings also may aid the clinician in deciding between joint-preserving therapy and hip arthroplasty.

Dynamic MR imaging of the abdomen with gadopentetate dimeglumine: normal enhancement patterns of the liver, spleen, stomach, and pancreas.

To show the normal contrast enhancement patterns of the upper abdominal organs, dynamic gadopentetate dimeglumine-enhanced MR imaging of the upper abdomen was performed in 48 patients. Although all patients were originally examined for focal hepatic lesions, none of them had diffuse parenchymal disease of any of the examined organs. Dynamic gadopentetate dimeglumine-enhanced MR imaging was done by using a heavily T1-weighted gradient-echo sequence (100/5 [TR/TE], 80 degrees flip angle) performed before, and repeatedly for a period of 10 min after, an IV bolus injection of gadopentetate dimeglumine (0.1 mmol/kg). Signal enhancement in each of the organs was calculated by measuring the signal intensity before and after administration of contrast medium. All organs showed signal enhancement within the first 2 min (p less than .001) and a continuous decline thereafter. The enhancement of the pancreas, liver, stomach wall, spleen, and renal cortex reached peaks of 75%, 78%, 96%, 144%, and 216%, respectively, 45 sec after administration of contrast medium. Liver and pancreas showed a homogeneous enhancement pattern throughout the examination. The spleen appeared heterogeneous during the first 60 sec and homogeneous thereafter. Two zones could be distinguished on the contrast-enhanced images of the stomach wall: an enhanced inner zone and an unenhanced outer zone. We conclude that homogeneous enhancement of the liver and pancreas, early heterogeneous enhancement of the spleen, and enhancement of the inner gastric wall are normal patterns on dynamic gadopentetate dimeglumine-enhanced MR images.

Gadopentetate dimeglumine-enhanced chemical-shift MR imaging of the breast.

Standard T1-weighted MR images enhanced with gadopentetate dimeglumine show relatively minimal enhancement of breast lesions due to the high background signal from fat in the breast. Strongly enhancing lesions may become isointense relative to the fat signal and become invisible or indistinct after contrast administration. Fat-suppressed chemical-shift imaging (CSI) combined with administration of gadopentetate dimeglumine improves lesion detection and characterization in other areas of the body where a strong lipid signal is present. We evaluated this technique in the breast. Twenty patients with mammographic lesions were studied with standard unenhanced T1- and T2-weighted images and enhanced T1-weighted images, as well as with CSI before and after administration of gadopentetate dimeglumine. The series were ranked independently for border and matrix characteristics. The border was assessed for a smooth, irregular, or spiculated margin. The matrix or internal substance was evaluated for visibility and type of enhancement, homogeneous or inhomogeneous. The enhanced CSI images were superior to all other images in the depiction of border and matrix characteristics. Of 20 patients, a corresponding mass was detected on MR in 14. In two of the 14 patients, the lesion was seen only in the enhanced CSI images. Chemical-shift artifacts on enhanced T1-weighted images obscured border detail in several cases. Enhanced CSI improves visualization of breast lesions as compared with conventional MR imaging with or without enhancement. The enhanced CSI technique produces differential enhancement between glandular tissue and lesions while suppressing the signal from fat. This improves the visualization of border and matrix characteristics and depicts lesions that otherwise might be obscured.

Preoperative evaluation of osteosarcoma: value of gadopentetate dimeglumine-enhanced MR imaging.

Decisions regarding the surgical approach in osteosarcoma require accurate assessment of tumor extent. In order to determine whether enhancement with gadopentetate dimeglumine could add clinically significant information to that available with unenhanced MR imaging, 21 patients with osteosarcoma underwent preoperative MR imaging. T1- and T2-weighted spin-echo MR images obtained before and after administration of IV gadopentetate dimeglumine were evaluated to determine the conspicuity of marrow and soft-tissue extent of tumor, including tumor involvement of major neurovascular bundles and adjacent joints. MR results were correlated with tumor margins found at surgery. In some instances, use of gadopentetate dimeglumine obscured differentiation of tumor from normal marrow or tumor infiltration into perineurovascular fat, and tumor extension through pseudocapsule could not be differentiated from peritumoral edema after contrast administration. Contrast enhancement did assist in differentiation of intraarticular tumor from effusion; however, synovial invasion could be identified on unenhanced T1-weighted images by loss of synovial fat and cortical disruption. These results indicate that gadopentetate dimeglumine does not assist in defining tumor margins of osteosarcoma.

Diagnosis of pancreatic transplant dysfunction: value of gadopentetate dimeglumine-enhanced MR imaging.

Sixteen MR studies performed in four patients who had undergone combined pancreatic and renal transplantation were reviewed retrospectively to determine if dynamic gadopentetate dimeglumine-enhanced gradient-echo imaging is useful in the early diagnosis of pancreatic transplant rejection. The MR studies were performed between 3 days and 6 months after transplantation and consisted of T1- and T2-weighted spin-echo images as well as a gradient-echo image prior to administration of an IV bolus of gadopentetate dimeglumine (0.1 mmol/kg). After injection of gadopentetate dimeglumine, a static dynamic gradient-echo scan was obtained. Signal-intensity measurements were determined for each of the gradient-echo images and used to generate an enhancement curve. Because T2 values have previously been used as an objective indicator of rejection, the mean T2 of each pancreatic transplant was calculated also. The MR results were compared with clinical and laboratory data and/or percutaneous biopsy results. In six studies of normally functioning pancreatic allografts, the percent enhancement during the first minute of the enhancement curve was 98 +/- 23% (1 SD). In six episodes of acute dysfunction (rejection or infarction), the first-minute enhancement was 42 +/- 20%. In four cases of dysfunction, the finding of an abnormal enhancement curve preceded a significant drop in urinary amylase by 1-4 days. The calculated T2 value was prolonged in only two cases in which biopsy-proved pancreatic infarction had occurred. No prolongation of T2 was evident in four cases of rejection alone. These results suggest that mean T2 calculation at 1.5 T may not be a reliable indicator of pancreatic transplant rejection, but that gadopentetate dimeglumine-enhanced gradient-echo MR imaging of the pancreatic transplant may be a reliable early indicator of pancreatic transplant dysfunction.

Gadopentetate dimeglumine-enhanced MR imaging of the musculoskeletal system.

Contrast-enhanced MR imaging with gadopentetate dimeglumine has been used in the evaluation of musculoskeletal disorders only in recent years, and for the most part it is still under investigation. Review of the literature identified potential uses for this technique: (1) in the spine, for differentiation between scar tissue and recurrent disk herniation and for evaluation of epidural tumors; (2) in musculoskeletal tumors, for differentiation between tumor necrosis and peritumoral edema and for characterization and evaluation of tumors before and after treatment; (3) in the joints for delineation of cartilage and tendon tears, with intraarticular injection, and for differentiation between pannus and joint effusion, with IV injection; and (4) for delineation of infectious processes. Further studies are needed to confirm most of these potential indications. It is unlikely that gadopentetate dimeglumine-enhanced MR imaging will become a routine part of musculoskeletal MR imaging, and its use will be reserved for specific circumstances.

Rheumatoid arthritis of the knee: value of gadopentetate dimeglumine-enhanced MR imaging.

In an attempt to differentiate among joint effusion, synovitis, pannus, and subchondral sclerosis in patients with clinically proved chronic rheumatoid arthritis, we used gadopentetate dimeglumine-enhanced MR imaging to examine 23 patients with acute knee symptoms. All patients had had rheumatoid arthritis for more than 6 months and satisfied four or more of the criteria of the American Rheumatism Association for rheumatoid arthritis. MR imaging was performed on a 1.5-T machine by using unenhanced T1-weighted spin-echo imaging, unenhanced T2*-weighted gradient-echo imaging, and unenhanced and enhanced T1-weighted gradient-echo imaging. Signal intensities of the synovium and bone marrow were measured with the region-of-interest technique on unenhanced and enhanced T1-weighted gradient-echo scans. Conventional radiographs were available for each patient. Joint effusion, synovitis, intraarticular pannus, subchondral sclerosis, and subchondral pannus had the same signal intensities on unenhanced T1-weighted spin-echo, unenhanced T1-weighted gradient-echo, and unenhanced T2*-weighted gradient-echo MR images, and could not be differentiated from one another. On enhanced T1-weighted gradient-echo sequences, pannus and synovitis showed marked enhancement in 15 patients, whereas joint effusion and sclerosis did not. Synovitis was diagnosed if the synovial membrane showed high enhancement; pannus was diagnosed if enhancing masses were seen within the joint space or in the subchondral area. In eight of the 23 joints, there was no enhancement of the synovium or intraarticular or subchondral tissue. We conclude that gadopentetate dimeglumine-enhanced MR imaging allows differentiation between synovitis and joint effusion and between subchondral pannus and subchondral sclerosis. Enhancement of the synovium and pannus indicates acute inflammation of the joint.

Persistent and recurrent hyperparathyroidism: assessment with gadopentetate dimeglumine-enhanced MR imaging.

The effect of gadopentetate dimeglumine on signal intensity of abnormal parathyroid glands was assessed in 14 patients with persistent and recurrent hyperparathyroidism. Non-contrast material-enhanced T1- and T2-weighted spin-echo images were compared with T1-weighted images obtained 1 minute and 10 minutes after administration of gadopentetate dimeglumine. Percentage of contrast between the abnormal gland and surrounding tissue was determined with the use of skeletal muscle, subcutaneous fat, and thyroid gland as reference tissues. All 11 abnormal parathyroid glands showed low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Gadopentetate dimeglumine significantly increased the signal intensity enhancement ratio of all abnormal parathyroid glands, causing increased percentage of contrast relative to the thyroid gland and skeletal muscle on T1-weighted images. However, the percentage of contrast relative to these tissues was even greater on nonenhanced T2-weighted images. Thus, gadopentetate dimeglumine can substantially enhance the signal intensity of abnormal parathyroid glands and improve differential contrast with some neighboring tissues on T1-weighted images, but it does not improve contrast with surrounding tissue beyond that achieved on T2-weighted images.

Fast MR imaging: techniques and clinical applications.

Fast MR imaging has matured in the past few years and is now of established value for several aspects of clinical MR imaging. The initial impetus for rapid imaging was to reduce scan times. Today its usefulness includes reducing motion artifacts, improved contrast per unit time, three-dimensional (3-D) imaging, real-time imaging, cine-mode imaging, and flow imaging. The focus of this review is on short-TR steady-state gradient-echo imaging. We discuss the basic sequence design of the mainstream fast techniques. Many important applications exist, including gadopentetate dimeglumine-enhanced MR imaging of the brain and spine, subsecond imaging of real-time applications, myelographic imaging of the spine, cardiac cine-mode imaging; 3-D musculoskeletal (knee) imaging, 3-D pituitary imaging; two-dimensional and 3-D body imaging; 3-D carotid and intravascular imaging, and reformatting 3-D images into arbitrary planes.