Study on the diagnosis of metastatic hepatic neuroendocrine neoplasms by contrast-enhanced ultrasound

Objective To retrospectively analyze the contrast-enhanced ultrasound (CEUS) features of metastatic hepatic neuroendocrine neoplasm (MHNEN) and their diagnostic value. Methods Twenty-eight patients with 35 MHNEN lesions were enrolled in this retrospectively study and underwent CEUS examination. The dynamic enhancement features, including enhancement pattern, peak intensity, and washout pattern were analyzed. Results The arrival time of contrast agent, time to peak, time to iso-echogenity and time to hypo-echogenity was (15.96±4.14)s, (21.42±5.01)s, (29.41±4.83)s and (42.06±22.84)s, respectively. Compared with adjacent liver parenchyma, rapid enhancement, synchronous enhancement and slow enhancement were found in 42.9% (15/35), 48.6%(17/35), 8.5%(3/35) of MHNEN lesions, respectively. As for enhancement patterns, 82.9% (29/35) of MHNEN lesions showed global enhancement, while 17.1%(6/35) showed rim-like enhancement. In addition, 22.9%(8/35) of the selesions had a centripetal pattern during the arterial phase. Compared with liver parenchyma, all lesions demonstrated hyper-enhancement at peak enhancement. In portal venous phase, 68.6%(24/35) of MHNEN lesions presented marked hypo-enhancement and 31.4%(11/35) with slight hypo-enhancement. And in late phase, all the lesions showed marked hypo-enhancement.Moreover, the boundaries of the lesions became distinct after contrast injection and another 36 lesions were identified on CEUS compared with conventional ultrasound. Conclusions CEUS can afford more diagnostic information of MHNEN and may be a good technique for diagnosing MHNEN. Key words: Contrast enhanced ultrasound; Liver neoplasms; Neuroendocrine neoplasm; Neoplasms metastasis