Hepatic metastases: Perilesional enhancement on dynamic MRI

OBJECTIVE. Our purpose was to determine whether the perilesional parenchymal enhancement of hepatic metastases could be correlated with tumoral enhancement on arterial phase images or tumor size on dynamic MRI. MATERIALS AND METHODS. One hundred thirty-four lesions of hepatic metastases in 44 patients were subjected to a retrospective analysis of the dynamic MR images obtained with 3D spoiled gradient-echo sequences. The thickness of the enhancing rim on arterial phase images was regarded as a summation of the enhancing component of tumor periphery and perilesional enhancement, which were estimated by the tumor size on precontrast T1-weighted images. The presence of wedge-shaped perilesional enhancement was also correlated with the lesion size. RESULTS. Except for 17 diffusely enhanced lesions, lesion size was comparable between the lesions with (n = 87; 26 ± 19 [SD] mm) and without rim enhancement (n = 30; 27 ± 23 mm) on the arterial phase dynamic MR images (p > 0.05). The degree of peripheral tumoral enhancement showed an inverse correlation (r = -0.389) with the thickness of the circumferential perilesional enhancement (p < 0.001). The mean size of the lesions with wedge-shaped perilesional enhancement (n = 44; 33 ± 20 mm) was larger than that of the other lesions (n = 90; 25 ± 19 mm) (p = 0.016). CONCLUSION. The degree of circumferential perilesional enhancement of hepatic metastases on arterial phase dynamic MR images would be independent of the lesion size but inversely correlated with the degree of peripheral tumoral vascularity. An understanding of these features may help tumor characterization and should prompt hypotheses and studies of microvascular phenomena in tumoral and epitumoral environments.