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 surrounding focal hepatic lesions on T2-weighted images have been described as an 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 finding, and in particular to determine if these wedge-shaped areas are characteristic of cancer.

MATERIALS AND METHODS

One hundred twenty-one patients with focal hepatic lesions (65 patients with metastases, 14 patients with hepatocellular carcinoma, and 42 patients with benign conditions) 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 surrounding the lesions were recorded; in patients with cancer, follow-up MR images and a clinical course were used to study the evolution of the lesions and the adjacent wedge-shaped areas. The final diagnosis in patients with cancer was proved by clinical course (54 patients) or fine-needle aspiration biopsy (25 patients); in patients with benign lesions, the findings on various other imaging techniques were accepted as conclusive.

RESULTS

The wedge-shaped areas were noted on T2-weighted images in 16 (25%) of 65 patients with metastases, in 3 (21%) of 14 patients with hepatocellular carcinoma, and in 5 (12%) of 42 patients with benign lesions. In 11 of the 16 patients with metastases and wedge-shaped areas of increased signal intensity, a metastatic lesion within the wedge-shaped area was detectable; in the remaining five patients, a metastatic lesion appeared during the subsequent clinical course. In some instances, the wedge-shaped area obscured the lesion. In patients with benign conditions, the wedge-shaped area was frequently seen in association with hemangiomas (4 of 13, 31%).

CONCLUSION

Our results show that wedge-shaped areas of increased signal intensity surrounding lesions on T2-weighted MR images are a common finding in patients with focal hepatic lesions. The wedge-shaped areas cannot be considered pathognomonic 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 treatment is being evaluated.