MR-IMAGING OF HEPATIC MASSES - DIAGNOSTIC-SIGNIFICANCE OF WEDGE-SHAPED AREAS OF INCREASED SIGNAL INTENSITY SURROUNDING THE LESION

OBJECTIVE. Wedge-shaped areas of increased signal intensity surroundin g focal hepatic lesions on T2-weighted images have been described as a n occasional finding in patients with hepatic metastases. We reviewed MR images of patients with benign and malignant focal hepatic lesions to determine the prevalence and diagnostic significance of this findin g, and in particular to determine if these wedge-shaped areas are char acteristic of cancer. MATERIALS AND METHODS. One hundred twenty-one pa tients with focal hepatic lesions (65 patients with metastases, 14 pat ients with hepatocellular carcinoma, and 42 patients with benign condi tions) underwent MR imaging of the liver at 1.0 T. Axial spin-echo T1- weighted and spin-echo and turbo spin-echo T2-weighted MR images were obtained. The MR images were retrospectively evaluated: the number and size of the lesions and the presence of wedge-shaped areas surroundin g the lesions were recorded; in patients with cancer, follow-up MR ima ges and a clinical course were used to study the evolution of the lesi ons and the adjacent wedge-shaped areas. The final diagnosis in patien ts with cancer was proved by clinical course (54 patients) or fine-nee dle aspiration biopsy (25 patients); in patients with benign lesions, the findings on various other imaging techniques were accepted as conc lusive. RESULTS. The wedge-shaped areas were noted on TP-weighted imag es in 16 (25%) of 65 patients with metastases, in 3 (21%) of 14 patien ts with hepatocellular carcinoma, and in 5 (12%) of 42 patients with b enign lesions, In 11 of the 16 patients with metastases and wedge-shap ed areas of increased signal intensity, a metastatic lesion within the wedge-shaped area was detectable; in the remaining five patients, a m etastatic lesion appeared during the subsequent clinical course. In so me instances, the wedge-shaped area obscured the lesion. In patients w ith benign conditions, the wedge-shaped area was frequently seen in as sociation with hemangiomas (4 of 13, 31%). CONCLUSION. Our results sho w that wedge-shaped areas of increased signal intensity surrounding le sions on T2-weighted MR images are a common finding in patients with f ocal hepatic lesions. The wedge-shaped areas cannot be considered path ognomonic of malignant lesions because they are also seen in patients with benign conditions (hemangioma, abscess). However, the appearance of these wedge-shaped areas in a patient with cancer should suggest a metastasis. The possibility that hepatic lesions could be obscured by these wedge-shaped areas also should be considered when response to tr eatment is being evaluated.