title: Leo J. Rigler lecture. MR imaging of the liver.
abstract: Recent technical and clinical advances in MR of the liver are reviewed with special reference to the role of MR as a primary screening technique for detection of space-occupying lesions, especially metastases. The major current problem in upper abdominal MR imaging is physiologic motions, and this appears to have been effectively solved by newly introduced pulse-sequence and timing-parameter strategies. Short-TR/TE spin-echo sequences with extensive signal averaging and heavy T1-weighting produce images with exceptional anatomic detail and liver-cancer contrast differences. With this sequence superior sensitivity for liver-cancer detection has been shown in quantitative signal-difference to noise comparisons with other pulse sequences and in clinical comparisons with CT. MR discovered 14% more individual metastases and 3% more patients with liver cancer than CT in a blinded comparative study of 142 patients undergoing both exams. MR also showed greater specificity (98%) than CT (91%) in distinguishing patients without liver metastases. Differentiation of hemangioma from metastases was possible with greater than 90% specificity by using heavily T2-weighted sequences. Use of a fast-scan, gradient-recalled echo technique can also produce good-quality, multislice, T1-weighted studies of the liver in 20 sec--a breath-hold. MR contrast agents (such as gadolinium-DTPA and reticuloendothelial-system-specific, superparamagnetic ferrite-iron-oxide particles) offer further promise for enhanced sensitivity for liver-cancer detection. When optimal pulse sequences are employed, MR can now be appropriate as a primary screening method for detecting liver neoplasms.
mesh_terms: D000328:Adult; D000818:Animals; D003287:Contrast Media; D003560:Cysts / Q000175:diagnosis; D003937:Diagnosis, Differential; D005188:False Negative Reactions; D005234:Fatty Liver / Q000175:diagnosis; D006391:Hemangioma / Q000175:diagnosis; D006801:Humans; D008107:Liver Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary*; D009682:Magnetic Resonance Spectroscopy; D009068:Movement; D055585:Physical Phenomena; D010825:Physics; D051381:Rats; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media