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Modified magnetic resonance angiography of the liver using sensitivity encoding in comparison with digital subtraction angiography and CT arterial portography.

BACKGROUND
Over 355 patients have received orthotopic liver transplantation (OLT) at this hospital since 1993. Preoperative imaging studies of both hepatic vessels and parenchyma in these recipients bettered surgical planning or even precluded the necessity of surgery. Here we report our preliminary results of modified magnetic resonance angiography (MRA) using sensitivity encoding (SENSE) through comparative study with conventional digital subtraction angiography (DSA) and CT arterial portography (CTAP).


METHODS
Sixteen patients with suspected liver diseases were included in the study. All of them received both dynamic MRI of the liver using SENSE and digital DSA with CTAP within a two-week interval. The four-phase MRA was reconstructed from source images of the coronal dynamic study. The arterial phase of the modified MRA was compared with DSA in the evaluation of hepatic arteries and the portal phase compared with CT portography reconstructed from source images of CTAP. In dynamic study of the liver, a fixed dose (20 ml) of contrast medium and scan timing were used.


RESULTS
The main branches and variations of the hepatic arterial system were well shown on the modified MRA, although the marginal branches of hepatic arteries were of poor quality. The figures of portal veins on MRA were as clear as or superior to those of CTAP. In addition, the suprarenal inferior vena cava (IVC) was well demonstrated on MRA and/or non contrast-enhanced coronal balanced fast-field echo (b-FFE) scan sequence in most cases. MRI detected most parenchymal lesions of the liver and hemodynamics of these lesions could be evaluated on source images of the modified MRA. MRI/MRA also serendipitously revealed several extrahepatic disease entities or variations that were not found on DSA/CTAP.


CONCLUSIONS
The modified MRA using SENSE is a cost-effective modality of examination for the demonstration of the whole hepatic vascular system. Combined with MRI, it has the potential as a one-stop imaging modality in the preoperative evaluation in fields such as OLT.