Gadolinium-enhanced MR angiography of the breast: is breast cancer associated with ipsilateral higher vascularity?

The aim of this study was to assess a possible association between breast malignancy and ipsilateral higher vascularity on gadolinium-enhanced MR angiography. One hundred six patients were examined by dynamic gadolinium-enhanced 3D MR imaging. Magnetic resonance angiographic views were generated by image subtraction and maximum intensity projection. The study included 85 patients with unilateral malignant breast neoplasms and 21 with unilateral benign lesions. Three blinded readers independently reviewed the MR angiograms after masking the lesions and the corresponding contralateral sites. The readers were asked to determine whether vascularity was higher on the right side, higher on the left side, or equal on both sides. The results were analyzed by the Kappa statistic and Pearson's chi-square test. The blood vessels of the breasts were clearly seen in all cases. There was good agreement among the observers (kappa > 0.54) in assessing vascularity on both sides. Breasts harboring malignant neoplasms were found to have a higher vascularity than the contralateral breasts (p < 0.005). This sign of malignancy had a sensitivity of 76.5%, a specificity of 57%, and an accuracy of 72.6%. Blood vessels of the breast can be depicted by MR angiography. Unilateral malignant neoplasms are associated with a higher ipsilateral vascularity. In conjunction with other indications of malignancy on gadolinium-enhanced MR images, a higher ipsilateral vascularity may serve as an additional sign of malignancy.

MS-325 EPIX.

EPIX is developing MS-325 (AngioMARK), an intravascular magnetic resonance contrast agent for use in the imaging of blood vessels and blood flow in patients with cardiovascular disease, including peripheral vascular disease (PVD). In June 1999, EPIX and Mallinckrodt began phase III trials of MS-325 for the detection of aortoiliac occlusive disease in patients with PVD or abdominal aortic aneurysm [328640]. NDAs for the peripheral and cardiac applications were expected in 1999 and 2000, respectively [275240], [325717]. MS-325 has also shown promise in demonstrating the presence of microscopic muscular dystrophy, as well as monitoring the effects of gene therapy in a mouse model of the disease [360974]. MS-325 is a stable complex of gadolinium and an organic chelating agent. It resembles approved agents in terms of stability, safety and elimination profile, but possesses novel chemical groups which allow it to bind reversibly to albumin. This retains the agent in the blood and, via a patented biophysical phenomenon, enhances the magnetic properties of the gadolinium ion approximately ten-fold.

MRI of intralesional hemolysis in focal nodular hyperplasia of the liver.

A case of Kasabach-Merritt syndrome caused by focal nodular hyperplasia of the liver is presented with atypical magnetic resonance findings due to intratumoral hemosiderin deposition. The high sensitivity of magnetic resonance imaging for iron served to identify the site of hemolysis in this patient with Kasabach-Merritt syndrome.

Comparison of angiography, CT arteriography and MR imaging in assessment of liver metastases treated by percutaneous transcatheter intraarterial chemotherapy.

The purpose of this study was to compare results of digital subtraction angiography (DSA), computed tomographic arteriography (CTA), and magnetic resonance imaging (MRI) in the assessment of patients with liver metastases subjected to percutaneous transcatheter intraarterial chemotherapy. Forty-four patients with liver metastases treated by cyclic percutaneous transcatheter intra-arterial chemotherapy were examined before each cycle by an imaging protocol consisting of DSA and CTA. MRI was added to this protocol in 18 patients. DSA and CTA equally detected thrombosis of the catheter or arteries distal to the catheter tip in 16 examinations. DSA detected arterial reflux in 15 examinations, while CTA detected only one case of reflux. CTA was superior to DSA in demonstrating perfusion abnormalities and superior to MRI in detecting metastases. CT was the only method that demonstrated intratumoral calcification. In conclusion, in patients with liver metastases subjected to percutaneous transcatheter intra-arterial chemotherapy, DSA is the best method for detection of arterial reflux, whereas CTA is the best method for detection of metastases and demonstration of perfusion abnormalities.

Peripheral washout sign on contrast-enhanced MR images of the breast.

PURPOSE: To assess the value of the peripheral washout sign on delayed contrast material-enhanced magnetic resonance (MR) images in differentiation of benign from malignant breast masses. MATERIALS AND METHODS: In 49 women with 79 breast lesions (55 malignant and 24 benign), dynamic contrast-enhanced MR imaging was performed every 90 seconds during the first 7 minutes and repeated at 10, 20, 30, 40, 50, and 60 minutes after injection of contrast material. Qualitative analysis of the images was performed to evaluate the presence of the peripheral washout sign (a hypointense zone in the periphery of the lesion relative to the center). Quantitative analysis of the images was performed by measuring the signal intensity of the periphery and center of the lesions. RESULTS: The peripheral washout sign was seen in 28 (51%) of the 55 carcinomas on delayed contrast-enhanced MR images (> 10 minutes). Quantitative analysis demonstrated different enhancement profiles of the periphery and center of these lesions. The periphery showed early increase and decrease of enhancement, while the center showed gradual increase and persistent enhancement. The peripheral washout sign was not seen in any of the benign lesions. Specificity was 100% and sensitivity was 51% for diagnosis of breast carcinoma. CONCLUSION: Peripheral washout may be a reliable sign of malignancy on delayed contrast-enhanced MR images of the breast.

Hepatic magnetic resonance imaging: new techniques and contrast agents.

Magnetic resonance (MR) imaging is a relatively new method of examining the liver. Attempts have been made to optimize the method by developing new imaging techniques and introducing new contrast agents. The new imaging techniques have improved the image quality by shortening the examination time, reducing motion artifacts, and improving contrast-to-noise ratio. Contrast agents have improved the diagnosis of focal hepatic lesions in MR imaging in several ways. Extracellular gadolinium chelates have significantly improved the characterization of lesions, and can be optimally used as a problem-solving method for differentiating focal lesions of an unknown nature that have already been detected by other imaging modalities or by unenhanced MR imaging. Hepatobiliary and macrophage monocytic phagocytic system (MMPS)-targeted contrast agents have improved the detection of hepatic lesions. These agents are best used for preoperative evaluation of the exact number of lesions in patients with primary or secondary hepatic neoplasms.

Hyperintense benign liver lesions on spin-echo T1-weighted MR images: pathologic correlations.

BACKGROUND: To determine the incidence of hyperintensity on T1-weighted spin echo (SE) images in benign liver lesions, value of fat-suppressed magnetic resonance (MR) imaging for the detection of fat within these lesions, and the causes of hyperintensity by correlation to pathologic examinations. METHODS: Five hundred forty-nine patients with 805 benign liver lesions including 585 hemangiomas, 188 focal nodular hyperplasias (FNHs), 14 hepatic adenomas (HAs), 14 focal fatty infiltrations (FFIs), two biliary cystadenomas, and two hemorrhagic cysts were examined by T2-weighted and T1-weighted SE MR imaging. For hyperintense lesions on T1-weighted SE images, fat-suppressed images were obtained by selective presaturation of fat. RESULTS: Thirty-two lesions (four FNHs, 10 HAs, 14 FFIs, two biliary cystadenomas, and two hemorrhagic cysts) appeared hyperintense on T1-weighted SE images; 21 of these became hypointense on the fat-suppressed T1 weighted SE images (one FNH, six HAs, and 14 FFIs) and contained fat at pathological examination. The other 11 lesions remained hyperintense on fat-suppressed T1-weighted SE images and had no fat deposition. Causes of hyperintensity in these cases were sinusoidal dilatation, copper deposition, hemorrhage, and high protein content. CONCLUSION: Among benign liver lesions, hyperintensity on T1-weighted SE images is rare (3.9%). Causes of this hyperintensity are fat deposition, copper accumulation, sinusoidal dilatation, bemorrhage, and high protein content. Fat-suppressed imaging can distinguish fat deposition from other causes of hyperintensity.

Benign liver tumors.

This article focuses on the main clinicopathologic and MR findings in the more frequent benign liver lesions (excluding hemangiomas) such as cysts, focal nodular hyperplasia, hepatocellular adenoma, and fatty tumors. These entities raise several questions concerning their pathogenesis, differential diagnosis from various malignant tumors or pseudotumoral hepatic lesions, and management that remain frequently controversial.

Liver metastases: improved detection with dynamic gadolinium-enhanced MR imaging?

PURPOSE: To compare dynamic gadolinium-enhanced with unenhanced magnetic resonance (MR) imaging in detection of liver metastases. MATERIALS AND METHODS: Two groups of patients were prospectively examined with unenhanced and dynamic gadolinium-enhanced MR imaging. The first group (n = 48) had proved liver metastases; the second group (n = 49) did not. One set of unenhanced and one set of gadolinium-enhanced MR images were selected per patient. Three independent, blinded readers assessed the images for presence, number, location, and conspicuity of lesions. Data were analyzed with receiver operating characteristic curves, and contrast-to-noise ratios were calculated for the images. RESULTS: There was no statistically significant difference between the use of unenhanced and gadolinium-enhanced MR images in the differentiation of patients with from patients without metastases. The numbers of false-positive and false-negative diagnoses of individual lesions were higher (not statistically significant) with dynamic MR images than with unenhanced MR images. At dynamic MR imaging, contrast-to-noise ratio was highest in the early phase (30 seconds after injection of the contrast agent) but was not significantly different from the contrast-to noise ratio of the T2-weighted images. CONCLUSION: Dynamic gadolinium-enhanced MR imaging showed no improvement over unenhanced MR imaging in detectability of liver metastases.

Imaging of metastases to the liver.

Metastatic disease to the liver is an important disease from the diagnostic, prognostic and therapeutic points of view. Different imaging modalities, such as US, CT, scintigraphy, and MRI, have been used for detection, characterization, therapy planning, and follow-up of this disease with variable degrees of success and failure. This review handles the problems which face the different imaging modalities in diagnosis of liver metastases in view of the pathological background of the disease. It also discusses the indications, strong points, and shortcomings of each of the imaging modalities in diagnosis of metastases, and surveys the recent efforts done to improve their performance through the optimization of quality control and in the innovations in the field of contrast agents. Finally, a protocol is suggested for the clinical management of patients with liver metastases to optimize cost-effectiveness of the imaging modalities in this era of multimodality approach in diagnostic imaging.

Focal liver lesions: characterization with nonenhanced and dynamic contrast material-enhanced MR imaging.

PURPOSE: To evaluate prospectively the diagnostic accuracy of non-enhanced and gadolinium-enhanced magnetic resonance (MR) imaging in characterization of hepatic lesions. MATERIALS AND METHODS: Fifty-five patients with benign and 52 patients with malignant focal liver lesions underwent examination at 1.5 T that comprised nonenhanced and dynamic contrast material-enhanced images. Four experienced radiologists independently read the different sets of images without and with knowledge of clinical history. RESULTS: Receiver operating characteristic analysis showed that dynamic contrast-enhanced MR imaging added information to nonenhanced MR studies and thereby improved distinction between benign and malignant lesions (P < .05). Knowledge of clinical data further improved lesion characterization with nonenhanced and combined nonenhanced and contrast-enhanced MR imaging (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is a useful adjunct for characterization of hepatic lesions. Knowledge of clinical history still has a decisive effect on interpretation of MR images of the liver.

Peripheral washout: a sign of malignancy on dynamic gadolinium-enhanced MR images of focal liver lesions.

PURPOSE: To assess the value of peripheral washout of contrast medium in differentiating benign from malignant focal liver lesions. MATERIALS AND METHODS: One hundred two patients, 49 with malignant liver tumors and 53 with benign lesions, underwent unenhanced T1- and T2-weighted and dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Dynamic contrast material-enhanced MR imaging was performed before and up to 10 minutes after intravenous administration of a bolus of gadopentetate dimeglumine (0.1 mmol/kg). RESULTS: On the dynamic contrast-enhanced images, 12 of the 49 malignant tumors had a rim that was hypo-intense to the center of the lesion ("peripheral washout" sign); this rim was best seen 10 minutes after administration of contrast material. This sign was absent in the remaining 37 malignant tumors as well as in all 53 benign lesions (P < .001). The peripheral washout sign had a sensitivity of 24.5% and a specificity of 100% in the diagnosis of malignancies of the liver. The malignant tumors with peripheral washout showed no difference in signal intensity between the periphery and the center on the unenhanced T1- and T2-weighted images. CONCLUSION: Peripheral washout is a specific sign of malignancy in dynamic gadolinium-enhanced MR imaging of liver lesions.

Hypervascular liver lesions: differentiation of focal nodular hyperplasia from malignant tumors with dynamic gadolinium-enhanced MR imaging.

The differentiating points between focal nodular hyperplasia (FNH) and malignant hypervascular liver lesions were studied at dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Thirty-six patients with 50 hypervascular lesions (28 FNH, 12 hepatocellular carcinoma, nine metastases, and one cholangiocarcinoma) underwent unenhanced spin-echo (SE) T1- and T2-weighted imaging and T1-weighted gradient-recalled-echo imaging before and repeatedly for 10 minutes after intravenous bolus injection of gadopentetate dimeglumine. On unenhanced SE images, the signal intensity of 25 FNH lesions (89%) and 10 malignant tumors (45%) was homogeneous. A central scar was detected in 12 FNH lesions (43%) and in none of the malignant tumors. On dynamic gadolinium-enhanced images, all lesions had early vigorous enhancement that was homogeneous in 27 FNH lesions (96%) and in seven malignant tumors (32%) (P < .001). After administration of gadopentetate dimeglumine, central scars were seen in 22 FNH lesions (79%) and in one malignant tumor (4%) (P < .001). All FNH lesions (100%) and six malignant tumors (27%) had well-defined enhancement (P < .001). There was overlap in the enhancement pattern between hypervascular malignant lesions and FNH, but by using the combination of unenhanced and enhanced images, they could be distinguished.