Superparamagnetic iron oxide was applied as a reticuloendothelial contrast agent in the diagnosis of cirrhosis and hepatitis in seven patients. Three patients had compensated cirrhosis, and four had active hepatitis. T1- and T2-weighted spin-echo magnetic resonance images were obtained before and 1 hour after the administration of iron oxide. Eight patients without diffuse liver disease served as a control group. Normal liver tissue showed a 75% +/- 9% reduction in signal intensity after the administration of iron oxide, and the liver appeared homogeneously hypointense. Cirrhotic liver tissue showed a smaller response (P less than .05) to iron oxide, with a 52% +/- 13% reduction in liver signal intensity. Inhomogeneous structures could be observed in enhanced images and are thought to represent fibrous bands or regenerating nodules. Liver tissue with active hepatitis showed a markedly reduced response to iron oxide (11% +/- 2%) (P less than .05), and the parenchyma appeared homogeneous. The authors conclude that the uptake of iron oxide particles is inhomogeneously altered in cirrhosis because of structural changes and homogeneously decreased in hepatitis because of functional changes of hepatic parenchyma.

To determine which quantitative methods of image analysis are most suitable for the differential diagnosis of benign and malignant hepatic lesions, the authors analyzed magnetic resonance images obtained at 0.6 T in 42 patients with proved hepatic cavernous hemangioma and 63 patients with various hepatic malignancies. The lesion-liver signal-intensity ratio for images obtained with a repetition time of 2,350 msec and echo time of 180 msec was most helpful in distinguishing hemangiomas from cancer (area under the receiving operator characteristic curve [ROC] = 0.99 +/- 0.005). All 38 lesions with lesion-liver signal-intensity ratios greater than 3.5 were hemangiomas, whereas all 57 hepatic tumors with a ratio less than 2.5 were malignant neoplasms. A specificity of 93% and sensitivity of 89% can be achieved with use of quantitative signal-intensity data only. The authors conclude that in conjunction with heavily T2-weighted pulse sequences, signal-intensity ratios are an important adjunct to morphologic analysis in the differential diagnosis of hepatic neoplasms.

Magnetic resonance (MR) imaging allows freedom in choosing oblique planes of section and rotation of the image plane with respect to the frequency-encoded (F) and phase-encoded (P) dimensions. A general method is described for understanding geometric relationships between the fixed magnetic coordinate system, patient positioning, and the flexible observer's coordinate system. Oblique planes of section are clinically useful in studying organs with an axis of symmetry that is oblique to the magnet coordinate system, such as the heart. Rotation of the image plane can be used to move motion artifacts away from anatomic regions of interest, such as the liver and spine. Appropriate use of oblique section selection and image rotation can improve MR image quality and diagnostic value of the patient study.