Injection Of Gadopentetate Dimeglumine Research Articles

Hormone Replacement Therapy in Postmenopausal Women: Breast Tissue Perfusion Determined with MR Imaging—Initial Observations

To use magnetic resonance (MR) imaging to evaluate tissue perfusion in the normal breast parenchyma of postmenopausal women with current or recent hormone replacement therapy (HRT). The study was approved by the institutional subcommittee on human studies, and informed consent was obtained from all patients prior to MR imaging. Sixty postmenopausal women (age range, 44-77 years) were grouped according to HRT received: estrogen replacement therapy (ERT) (n = 13), combined (estrogen and progesterone) replacement therapy (CRT) (n = 16), selective estrogen receptor modulator (SERM) therapy (n = 8), and no (hormone replacement) therapy (NT) (n = 23). MR imaging with a 1.5-T magnet was performed by using gradient-echo and dynamic contrast material-enhanced echo-planar pulse sequences before and after gadopentetate dimeglumine injection. Precontrast T1 relaxation times were measured, after which extraction-flow product (EFP) maps were calculated with a multicompartmental model. Analysis of variance was performed. Age did not significantly differ between the groups (P > .3). Women receiving ERT or CRT at the time of MR imaging had higher EFP values (7.3 mL . 100 g(-1) . min(-1)+/- 2.6 and 7.1 mL . 100 g(-1) . min(-1)+/- 3.8, respectively) than did women receiving NT (4.4 mL . 100 g(-1) . min(-1)+/- 2.1) (P = .012 and P = .008, respectively) or SERM therapy (3.9 mL . 100 g(-1) . min(-1)+/- 1.1) (P = .015 and P = .013, respectively). Women who ended ERT or CRT 1-47 months before MR examination had lower EFP values than did women with current ERT or CRT and had higher EFP values than did women receiving NT or SERM therapy (6.2 mL . 100 g(-1) . min(-1)+/- 2.4 and 5.9 mL . 100 g(-1) . min(-1)+/- 3.8, respectively), but the observed differences were not significant (P > .1). Differences in T1 between all groups were not significant (P > .5). Higher breast tissue perfusion is observed in postmenopausal women receiving HRT.

VX2 Carcinoma in Rabbits after Radiofrequency Ablation: Comparison of MR Contrast Agents for Help in Differentiating Benign Periablational Enhancement from Residual Tumor

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

Potential of magnetic resonance lymphography with intrapulmonary injection of gadopentetate dimeglumine for visualization of the pulmonary lymphatic basin in dogs: preliminary results.

To evaluate a new approach of magnetic resonance (MR) lymphography with intraalveolar injection of a conventional extracellular contrast agent (gadopentetate dimeglumine) for imaging lymphatic basin draining from specific portions of the lung. Three-dimensional T1-weighted spoiled gradient-recalled echo MR sequence images were acquired serially before and for 40 minutes after intraalveolar injection of gadopentetate dimeglumine in a total of 14 anesthetized beagle dogs. Six of these dogs received 1 mL undiluted and low-concentration (75%) contrast agent into the same portion of the right caudal lobe during a 7-day interval. In all dogs, including these 6 dogs, MR lymphography was repeated with injection of the low-concentration contrast agent into different lung regions at 7-day intervals to evaluate the differences of the visualized draining lymphatic station. Lymphatic enhancement was quantified by percent increases of signal intensity against precontrast. Postmortem examination of the lymphatic anatomy was performed in 7 of these animals. In all dogs, the lymphatic station draining from the injection sites was visualized within 5 minutes after contrast injection. The maximum percent increase of signal intensity of the same middle tracheobronchial lymph nodes was significantly greater with a low-concentration (75%) contrast agent than with an undiluted one in the same 6 dogs (n = 6, 247.6 +/- 30.5% vs. 204.2 +/- 33.8%; P < 0.01). Different lymphatic stations draining from the different injection sites were visualized in all dogs. In a total of 12 MR studies that showed extended nodal enhancement after injection of the low-concentration contrast agent, the enhancement peak of the most proximal nodes (n = 12) from the injection sites appeared earlier than that of their distant nodes (n = 12), with a maximum percent increase of signal intensity of 249.8 +/- 42.4%. The visualized lymph nodes were found in the appropriate locations postmortem, with significant correlation for nodal sizes (r = 0.965; P < 0.0001). MR lymphography with low-concentration gadopentetate dimeglumine can quickly and sufficiently visualize the drainage lymphatic station from specific lung portions, and may have the potential of sentinel node mapping in lung cancer.

Diffusion-weighted MR imaging of cholesteatoma in pediatric and adult patients who have undergone middle ear surgery.

The aim of this prospective study was to determine the role of diffusion-weighted MR imaging combined with conventional MR imaging for the detection of residual or recurrent cholesteatoma in patients who have undergone middle ear surgery. Twenty-two patients who had undergone resection of cholesteatoma were referred for MR imaging. MR imaging (1.5 T) was performed using a diffusion-weighted single-shot spin-echo echoplanar sequence, a proton density and T2-weighted double-echo turbo spin-echo sequence, and T1-weighted spin-echo sequences before and after IV injection of gadopentetate dimeglumine (0.1 mmol/kg of body weight). An experienced reviewer evaluated the diffusion-weighted MR images for the presence of a high-signal-intensity cholesteatoma. Imaging findings were correlated with findings from surgery in 17 patients and with findings from clinical follow-up examination in five patients. Diffusion-weighted MR imaging combined with conventional MR imaging depicted 10 of 13 cholesteatomas (sensitivity, 77%). The three lesions that were missed were smaller than 5 mm. All the MR images of patients without cholesteatoma were correctly interpreted as showing negative findings for cholesteatoma (specificity, 100%). The positive predictive value and negative predictive value were 100% and 75%, respectively. Diffusion-weighted MR imaging combined with conventional MR imaging can confirm residual or recurrent cholesteatoma in patients who have undergone middle ear surgery by showing a high-signal-intensity lesion. Because tumors smaller than 5 mm may be missed, a diffusion-weighted MR imaging study with negative findings does not exclude small residual or recurrent cholesteatoma.

Invasive ductal breast carcinoma response to neoadjuvant chemotherapy: noninvasive monitoring with functional MR imaging pilot study.

To investigate if the extraction flow product (EFP), as determined on dynamic contrast material-enhanced magnetic resonance (MR) images, could be a potential marker of tumor response to neoadjuvant chemotherapy in patients with locally advanced breast cancer. Fourteen women with proven breast cancer underwent MR imaging prior to and following neoadjuvant chemotherapy. Dynamic gradient-echo and echo-planar MR images were acquired before and after injection of gadopentetate dimeglumine. Precontrast T1s were measured before EFP maps were calculated by using a multicompartmental model. Mean EFP (EFPmean) and distribution analysis of EFP (EFPcount) were measured in tumors before and after neoadjuvant chemotherapy and were compared with tumor response at MR imaging. The significance of the difference in EFP values between the responders and nonresponders was calculated with a two-tailed Student t test. EFPmean after neoadjuvant chemotherapy in partial responders and nonresponders was 33 mL x 100 g-1 x min-1 +/- 9.8 and 54.2 mL x 100 g-1 x min-1 +/- 10.3, respectively (P <.005). EFPmean decreased after neoadjuvant chemotherapy in the responders and nonresponders by 37% +/- 30 and -5% +/- 35, respectively (P >.05). An increase in EFPmean values was observed only in nonresponders who received taxanes. For regimens without taxanes, EFPmean decreased regardless of the morphologic response. EFPcount decreased for all the responders by 77% +/- 33 and increased for all the nonresponders by 45% +/- 68 (P <.02). EFPcount appears to provide functional information regarding changes in tumor angiogenesis due to neoadjuvant chemotherapy. Functional MR imaging of the breast may be useful in monitoring tumor response to neoadjuvant chemotherapy.

MR arthrography in chondromalacia patellae diagnosis on a low-field open magnet system

Objective: The purpose of this study was to compare the diagnostic efficacy conventional MRI and MR arthrography (MRA) in the diagnosis of chondromalacia patella (CP) on a low-field open magnet system (LFOMS), correlated with arthroscopy. Subjects and methods: Forty-two patients (50 knees) with pain in the anterior part of the knee were prospectively examined with LFOMS, including T1-weighted, proton density-weighted and T2-weighted sequences. All were also examined T1-weighted MRI after intraarticular injection of dilue gadopentetate dimeglumine. Two observers, who reached a consensus interpretation, evaluated each imaging technique independently. Thirty-six of the 50 facets examined had chondromalacia shown by arthroscopy, which was used as the standard of reference. The sensitivity, specificity and accuracy of each imaging technique in the diagnosis of each stage of CP were determined and compared by using the McNemar two-tailed analysis. Results: Arthroscopy showed that 16 facets were normal. Four (30%) of 13 grade 1 lesions were detected with T1. Four lesions (30%) with T2 and three lesions (23%) with proton-weighted images were detected. Seven (53%) of 13 grade 1 lesions were detected with MRA. Grade 2 abnormalities were diagnosed in two (33%) of six facets with proton density-weighted pulse sequences, two (33%) of six facets with T1-weighted pulse sequences, in three (50%) of six facets with T2-weighted pulse sequences, in five (83%) of six facets with MRA sequences. Grade 3 abnormalities were diagnosed in three (71%) of seven facets with proton density- and T1-weighted images, five (71%) of seven facets with T2-weighted pulse sequences, six (85%) of seven facets with MRA sequences. Grade 4 CP was detected with equal sensitivity with T1-, proton density- and T2-weighted pulse sequences, all showing seven (87%) of the eight lesions. MRA again showed these findings in all eight patients. All imaging techniques were insensitive to grade 1 lesions and highly sensitive to grade 4 lesion, so that no significant difference among the techniques could be shown. Conclusion: All imaging technique studied had high specificity and accuracy in the detection and grading of CP; however, MRA was more sensitive than T1-weighted and proton density-weighted MR imaging on a LFOMS. Although the arthrographic techniques were not significantly better than T2-weighted imaging, the number of false-positive diagnosis was greatest with T2-weighted MRI.

Clinical testing of high-spatial-resolution parametric contrast-enhanced MR imaging of the breast.

We performed a prospective clinical test of a high-spatial-resolution model-based parametric method for diagnosis of breast lesions detected on contrast-enhanced MR imaging. Fifty-seven women with 68 pathologically confirmed breast lesions were imaged (45 masses, 23 microcalcifications). Seven consecutive 2-min three-dimensional gradient-recalled echo acquisitions were performed after suitably timed gadopentetate dimeglumine injections. We derived a composite parametric image from three judiciously selected time points (three-time-point method), using a model-based kinetic algorithm. In this composite image, color brightness and hue signify contrast uptake and washout characteristics related to the product of microvessel surface area and permeability, as well as to the extracellular volume fraction. The reviewer was provided with the slice location of lesions, but with no other radiographic or clinical information. The reviewer then classified the lesions as benign or malignant using a 5-step receiver operating characteristic scale. Observers using the three-time-point method correctly diagnosed 27 of 31 malignant and 31 of 37 benign lesions (sensitivity, 87%; specificity, 84%). The area under the receiver operating characteristic curve was 0.911. False-negative results were found for three patients with low- to intermediate-grade ductal carcinoma in situ and one patient with 5-mm invasive ductal cancer. For the 45 solid lesions, sensitivity and specificity were 96% and 82%, respectively. Application of the three-time-point method permitted, in most cases, differentiation of malignant and benign lesions, even in the presence of complex breast enhancement patterns. Sensitivity for solid tumors was higher than for ductal carcinoma in situ.

Contrast-enhanced MR angiography of the hand.

Contrast material-enhanced magnetic resonance (MR) angiography of the hand noninvasively provides information comparable to that provided by conventional angiography. It is a quick and easy examination that takes less than 5 minutes to perform and produces high-quality images with use of a dedicated surface coil that provides a high signal-to-noise ratio, allowing small pixel size and high spatial resolution. Contrast-enhanced MR angiography requires intravenous injection of gadopentetate dimeglumine and acquisition of a volumetric slab of image data from the hand. This information is then projected with a maximum-intensity-projection algorithm. The technique is generally robust with reproducible findings. Image interpretation requires an understanding of (a) the normal vascular anatomy and anatomic variants of the hand and (b) common vascular diseases. MR angiography of the hand is commonly used to create an arterial "road map" prior to surgery, manage traumatic transection, and identify emboli. Vascular malformations are readily identified and connective tissue disorders including vasculitis are well demonstrated with this technique, which can also be used to assess bone viability following trauma to the carpus or to evaluate the viability of vascularized bone. Common artifacts may be secondary to contracture deformities or "wraparound" effect. However, most potential pitfalls can be avoided by being vigilant.

Coronary MR angiography: experimental results with a monomer-stabilized blood pool contrast medium.

To evaluate the signal-enhancing characteristics of monomer-coated very small superparamagnetic iron oxide (SPIO) particles used as a blood pool contrast medium for magnetic resonance (MR) angiography in the coronary arteries. The particles used in this study were coated with citrate as the monomer (VSOP-C91). The particles have a total diameter of 7 nm and show the following relaxivities at 0.47 T: T1, 19 L/mmol. sec(-1); T2, 29 L/mmol. sec(-1). Fifteen cardiac MR examinations were performed at 1.5 T in five pigs. Images were acquired from immediately to 35 minutes (equilibrium phase) after intravenous injection of gadopentetate dimeglumine, gadobenate dimeglumine, and the very small SPIO particles (n = 5 for each substance). Immediately after administration of gadopentetate dimeglumine, gadobenate dimeglumine, and the very small SPIO particles, respectively, increases in the signal-to-noise ratio in blood were 94%, 103%, and 102% and in myocardium were 83%, 83%, and 29% (P <.05, very small SPIO particles versus the low-molecular-weight gadolinium-based compounds). Differences in the blood-to-myocardium contrast-to-noise ratio and visualization of the coronary arteries and their branches were also significant. VSOP-C91 significantly improves visualization of the coronary arteries at MR angiography from immediately to 35 minutes after injection.

Analysis of Signal Intensity Curve on Dynamic Contrast-Enhanced MR Imaging of Postoperative Scars in Rabbits:Comparison of Gadopentetate Dimeglumine and 24-gadolinium-tetraazacy-clododecanetetraacetic acid (DOTA)-dendrimer

Purpose: To compare the enhancement patterns of 24-gadolinium-tetrazacyclodode-cane tetracetic acid (DOTA)-dendrimer (Gadomer-17) with those of gadopentetate dimeglumine (Magnevist) in postoperative scars in rabbits. Materials and Methods: Twelve rabbit thighs with experimentally induced postoperative scars underwent dynamic contrast-enhanced MR imaging with both Gadomer-17 and gadopentetate dimeglumine at a 24-hr interval at one (n = 10), two (n = 8) and three months (n = 4) after scar induction. The enhancement and the ratios of lesions at each time point, peak enhancement ratios, and the slope and shape of curves were assessed. Results: At all time points, enhancement ratios were significantly lower after the injection of Gadomer-17 than with gadopentetate dimeglumine (p 0.17) than with gadopentetate dimeglumine (1.61 0.31) (p 2.72 after Gadomer-17 injection and 8.99%/min 7.32 after gadopentetate dimeglumine injection (p

Comparison of gadomer-17 and gadopentetate dimeglumine for differentiation of benign from malignant breast tumors with MR imaging

This study compared gadopentetate dimeglumine (molecular weight, 0.5 kD), a standard contrast medium, and Gadomer-17 (apparent molecular weight, approximately 35 kD), a new, clinically applicable, large-molecular contrast medium, with respect to their microvascular characterizations of experimentally induced breast tumors at magnetic resonance (MR) imaging. A spectrum of breast tumors, benign through highly malignant, was induced in Sprague-Dawley rats (n = 30) by intraperitoneal administration of N-ethyl-N-nitrosourea (ENU), a potent carcinogen. All animals underwent three-dimensional spoiled gradient-recalled MR imaging, with precontrast imaging and dynamic postcontrast imaging after injection of gadopentetate dimeglumine (0.1 mmol/kg) and Gadomer-17 (0.03 mmol/kg), administered in a random order at a 24-hour interval. Several microvascular parameters were compared: the endothelial transfer coefficient (K(PS)), a measure of microvascular permeability; the fractional plasma volume (fPV), and the plasma equivalent volume. Each MR imaging parameter was correlated with histopathologic findings. With Gadomer-17, the mean values for K(PS) and fPV were significantly greater in carcinomas than in fibroadenomas (P < .004 and .04, respectively). With gadopentetate dimeglumine, the mean values for fPV and PEV were significantly greater in carcinomas (P <. 004 and .02, respectively). Because of the high variability within both fibroadenoma and carcinoma groups, however, there were no significant correlations between K(PS), fPV, or PEV and histopathologic tumor grade as indicated by the Scarff-Bloom-Richardson score, for either agent. Although the K(PS) and fPV estimates obtained from dynamic MR imaging data with Gadomer-17 enhancement offer some potential for characterizing breast tumors, none of the quantitative microvascular parameters derived with either agent were significantly correlated with histopathologic tumor grade.

Comprehensive MR Imaging of Acute Gynecologic Diseases

Rapid advances in techniques of magnetic resonance (MR) imaging have enabled diagnosis of acute gynecologic conditions, which are characterized by sudden onset of lower abdominal pain, fever, genital bleeding, intraperitoneal bleeding, or symptoms of shock. The chemical-selective fat-suppression technique not only helps establish the characteristics of lesions that contain fat components but also increases the conspicuity of inflammatory lesions. When a T2-weighted image is obtained with a very long effective echo time (>250 msec), even a small amount of ascites can be easily identified and the contrast between urine and complex fluid becomes more conspicuous. T2*-weighted images are useful for identification of hemorrhagic lesions by demonstrating deoxyhemoglobin and hemosiderin. Contrast material-enhanced dynamic subtraction MR imaging performed with a three-dimensional fast field-echo sequence and a rapid bolus injection of gadopentetate dimeglumine allows evaluation of lesion vascularity and the anatomic relationship between pelvic vessels and a lesion and allows identification of the bleeding point by demonstrating extravasation of contrast material. To optimize the MR imaging examination, attention should be given to the parameters of each pulse sequence and proper combination of the sequences.

Magnetic resonance arthrography of the temporomandibular joint

Purpose: This study evaluated the usefulness of magnetic resonance arthrography (MRAr) in imaging the pathologic temporomandibular joint (TMJ). Patients and Methods: Thirteen TMJs of 11 patients with chronic TMJ pain and disability were examined with MRAr. T1-weighted and T2-weighted first spin-echo sequence with fat suppression images were obtained after the intra-articular injection of gadopentetate dimeglumine. Results: The disc, the posterior attachment, and the presence of perforations and adhesions were evaluated in each image. All of these anatomic and pathologic structures were clearly detected. Conclusion: MRAr appears to be a promising imaging modality in detecting adhesions and perforations in the TMJ. The MRAr findings simplified the decision of whether a patient should undergo surgery. © 2000 American Association of Oral and Maxillofacial Surgeons

Analysis of First-Pass and Delayed Contrast-Enhancement Patterns of Dysfunctional Myocardium on MR Imaging

The purpose of the study was to analyze first-pass and delayed contrast-enhancement patterns of dysfunctional myocardial regions on MR imaging after injection of gadopentetate dimeglumine to predict myocardial viability in patients with coronary artery disease. Twelve patients with wall motion abnormalities and related coronary artery disease revealed by conventional coronary angiography underwent MR imaging at 1.5-T before and 3 months after revascularization therapy. Short-axis images were acquired using a cine gradient-echo sequence. Each slice was divided into eight segments. Overall, 73 segments with impaired contractility were imaged during the first-pass and 14 +/- 2 min after injection of 0.05-mmol/kg gadopentetate dimeglumine at a flow of 3 ml/sec using a T1-weighted turbo fast low-angle shot sequence. Improved systolic wall thickening 3 months after revascularization served as the criterion of viability. At study entry, 26 dysfunctional segments showed delayed hyperenhancement compared with the adjacent functional segments within the same slice, and 47 did not reveal hyperenhancement. After revascularization, 25 (96%) of the 26 hyperenhanced segments did not recover function, whereas 39 (83%) of the 47 segments without hyperenhancement showed mechanical improvement. Segment-related sensitivity and specificity for the correlation of lack of delayed hyperenhancement with myocardial viability were 39 (98%) of 40 and 25 (76%) of 33, respectively. Hypoenhancement during first-pass did not serve as a reliable criterion of viability. Evidence of delayed hyperenhancement of dysfunctional myocardium may be used to predict lack of mechanical improvement or nonviability, whereas the lack of hyperenhancement can be correlated with improvement of regional contractility or viability after revascularization.

THE POTENTIAL INFLUENCE OF FINE-NEEDLE ASPIRATION ON MR IMAGING OF THE BREAST

The aim of this study was to determine whether fine-needle aspiration biopsy (FNAB) of breast lesions causes structural changes or changes in contrast enhancement, that could impair the evaluation of these lesions at MR investigation of the breast. Fifteen patients with 17 lesions were examined with MR imaging of the breast both before and after the FNAB with a mean interval of 7.1 days. At both examinations, signal intensities were measured pre- and post-contrast enhancement in the lesions as well as in surrounding breast parenchyma and muscle. Imaging with contrast enhancement was performed semidynamically with two images obtained in rapid sequence (acquisition time 6.23 min) immediately after bolus injection of gadopentetate dimeglumine, 0.1 mmol/kg b.w., and the contrast enhancement in both images was calculated. The diagnostic value of MR images was unimpaired by FNAB, and no statistical difference between contrast enhancement in corresponding images obtained before and after FNAB was found, either within the lesions or in the breast parenchyma or muscle. FNAB of the breast can be performed without impairing the diagnostic outcome of MR investigation.

The Potential Influence of Fine-Needle Aspiration on MR Imaging of the Breast

The aim of this study was to determine whether fine-needle aspiration biopsy (FNAB) of breast lesions causes structural changes or changes in contrast enhancement, that could impair the evaluation of these lesions at MR investigation of the breast. Fifteen patients with 17 lesions were examined with MR imaging of the breast both before and after the FNAB with a mean interval of 7.1 days. At both examinations, signal intensities were measured pre- and post-contrast enhancement in the lesions as well as in surrounding breast parenchyma and muscle. Imaging with contrast enhancement was performed semidynamically with two images obtained in rapid sequence (acquisition time 6.23 min) immediately after bolus injection of gadopentetate dimeglumine, 0.1 mmol/kg b.w., and the contrast enhancement in both images was calculated. The diagnostic value of MR images was unimpaired by FNAB, and no statistical difference between contrast enhancement in corresponding images obtained before and after FNAB was found, either within the lesions or in the breast parenchyma or muscle. FNAB of the breast can be performed without impairing the diagnostic outcome of MR investigation.

Detection of small, functional islet cell tumors in the pancreas: selection of MR imaging sequences for optimal sensitivity.

To determine the sensitivity and specificity of magnetic resonance (MR) imaging for depicting pancreatic small, functional islet cell tumors and the minimum number of sequences for expedient diagnosis. Twenty-eight patients clinically suspected to have functional islet cell tumors underwent T1- and T2-weighted spin-echo (SE) MR imaging with and without fat suppression, T2-weighted fast SE imaging, and spoiled gradient-echo (GRE) imaging before and after injection of gadopentetate dimeglumine. Sensitivity, specificity, and the best and minimum number of sequences for definitive diagnosis were determined. MR images depicted proved islet cell tumors in 17 of 20 patients (sensitivity, 85%). Images were true-negative in eight patients with negative follow-up examination results for more than 1 year. Specificity was 100%; positive predictive value, 100%; and negative predictive value, 73%. Among 20 patients with tumor, T1-weighted SE images with fat suppression and nonenhanced spoiled GRE images each showed lesions in 15 (75%); T2-weighted conventional SE with fat suppression, in 13 (65%); gadolinium-enhanced spoiled GRE, in 12 (60%); and T2-weighted fast SE, in seven of 10 patients (70%). MR imaging accurately depicts small islet cell tumors. T2-weighted fast SE and spoiled GRE sequences usually suffice. Gadolinium-enhanced sequences are needed only if MR imaging results are equivocal or negative.

Dynamic Contrast Enhanced MRI of Prostate Cancer: Correlation with Morphology and Tumour Stage, Histological Grade and PSA

AIM: To quantify MRI enhancement characteristics of normal and abnormal prostatic tissues and to correlate these with tumour stage, histological grade and tumour markers.MATERIALS AND METHODS: Quantitative gradient recalled echo MR images were obtained following bolus injection of gadopentetate dimeglumine in 48 patients with prostate cancer. Turbo spin-echo T2-weighted images at the same anatomical position were reviewed for the presence of tumours (45 regions), normal peripheral zone (33 regions), and normal appearing central gland (30 regions). Time-signal intensity parameters (onset time, mean gradient and maximal amplitude of enhancement and wash-out score) and modelling parameters (permeability surface area product, lesion leakage space and maximum gadolinium concentration) were correlated with tumour stage, histological grade (Gleason score) and serum prostatic specific antigen (PSA) levels.RESULTS: Significant differences were noted between peripheral zone and tumour with respect to signal intensity and modelling parameters (P=0.0001), except onset time. No differences between central gland and tumour enhancement values were seen. There was weak correlation between MRI tumour stage and tumour vascular permeability (r2=12%;P=0.02) and maximum tumour gadolinium concentration (r2=14%;P=0.015). However, no significant correlations were seen with Gleason score or PSA levels.CONCLUSION: Quantification of MR contrast enhancement characteristics allows tissue discrimination in prostate cancer consistent with known variations in microvessel density estimates.Padhani, A. R. (2000). Clinical Radiology55, 99–109.

Occurrence of adverse reactions to gadolinium-based contrast material and management of patients at increased risk: A survey of the American society of neuroradiology fellowship directors

The authors attempted to determine the frequency and severity of adverse reactions to gadolinium-based magnetic resonance (MR) contrast agents and to identify strategies for management of patients at increased risk. American Society of Neuroradiology program directors were surveyed about adverse reactions at their institutions to gadolinium-based contrast agents, the contrast agents responsible, and the management of patients with allergy-like reactions to iodinated or gadolinium-based agents who required MR contrast agent administration. Fifty-three (50.5%) surveys were received from 105 centers. Of 687,255 gadopentetate dimeglumine injections, 314 (0.046%) nonallergic reactions and 107 (0.016%) mild, 28 (0.004%) moderate, and five (0.001%) severe allergy-like reactions occurred. Of 74,275 gadodiamide injections, 11 (0.015%) nonallergic and 12 (0.016%) mild allergy-like reactions occurred. Of 64,005 gadoteridol administrations, 171 (0.267%) nonallergic reactions and 49 (0.077%) mild, 29 (0.047%) moderate, and 11 (0.017%) severe allergy-like reactions occurred. Twenty-six departments took no precautions for patients with previous allergy-like reactions to iodinated contrast material. Nineteen did not premedicate patients who previously had reactions to gadolinium-based agents before repeat administration of MR contrast agents. Although MR contrast agents are safe, adverse reactions occur. Many centers have not adopted policies for the OFF

Breast MRI in the Evaluation of Patients with Occult Primary Breast Carcinoma.

Occult primary breast carcinoma presenting as isolated ipsilateral axillary lymph node metastases in patients with normal mammograms and normal physical exams accounts for less than 1% of all breast carcinomas. Contrast-enhanced magnetic resonance imaging (MRI) may identify the site of primary breast carcinoma and effect management of these patients. We report on eight consecutive women evaluated in our multidisciplinary clinic who had biopsy-proven metastatic adenocarcinomas to axillary lymph nodes and occult primary carcinomas. Each patient underwent MRI at 1.5 T with a volumetric fast-spoiled gradient-echo (3D FSPGR) pulse sequence before and after injection of gadopentetate dimeglumine. Wire localization of suspicious areas of enhancement was performed under MRI or mammography guidance followed by surgical excision. Seven (88%) of the eight normal mammograms showed dense (>50%) breast parenchyma. In two (25%) of the eight patients, suspicious focal or regional enhancement was seen on MRI. Following wire localization and excision, pathologic exam showed an invasive ductal carcinoma and ductal carcinoma in situ with invasion corresponding to the MRI enhancement in the two cases. Breast MRI can identify the primary tumor site and influence management of patients presenting with clinically and mammographically occult primary breast carcinomas.