Purpose: The behaviour of contrast media in the assessment of focal hepatic malignancies is not always concordant among the different imaging techniques. The purpose of our paper is to investigate the reasons of these differences.
Method and Materials: We selected 124 patients who underwent both a CEMDCT and a CEUS at our Institution from July 2007 to July 2008. CEUS was performed after the injection of 4.8 ml of ultrasonographic 2nd generation contrast medium and with dedicated imaging algorithms. CEMDCT was performed on 16 or 64-row equipments, with bolus tracking contrast medium injection in 65 cases and standard time of acquisition (30 sec, 60/90sec, 3/5min) in 59 cases. All cases where diagnosis was uncertain underwent an ultrasound-guided biopsy.
Results: 21 cases of discrepancy between CEUS and CEMDCT were found. In 16/21 cases, these lesions were metastases from colorectal cancer; in 7/24 cases hepatocarcinoma was found; 1/24 case was a capillary hemangioma. In 20/21 cases, during arterial phase CEUS was positive while CEMDCT showed hypodense lesions. The hemangioma showed a centripetal late enhancement at 5 minutes at CEMDCT that was not detected at CEUS. In 19/20 cases, the injection of contrast medium during CEMDCT scan was performed with standard timing.
Conclusions: the discrepancies between CEUS and CEMDCT are related to the earlier arterial perfusion of some lesions that cannot be understood in advance when bolus tracking technique is not used.