Abstract
BackgroundMRI and perfusion-CT (PCT) are both useful imaging techniques for detection and characterization of liver lesions. The aim of this study was to compare the diagnostic accuracy of imaging parameters derived from PCT and gadoxetic acid-enhanced MRI in patients with hepatocellular carcinoma (HCC).Methods36 patients with liver cirrhosis and a total of 67 lesions referred to our hospital for multi-parametric diagnosis of HCC-suspected liver lesions in the setting of liver cirrhosis were prospectively enrolled and underwent PCT and MRI. HCC diagnosis was confirmed either by histology (n = 60) or interval growth (n = 7). For PCT, mean/max blood flow (BF), blood volume (BV), k-trans, arterial liver perfusion (ALP), portal venous perfusion (PVP) and hepatic perfusion index (HPI) were quantified. Two readers identified the lesions based on single maps each being blinded to the number of lesions.MRI-protocol included fat-suppressed T1w-VIBE sequences obtained before, 2, 5, 10 and 20 min after the injection of gadoxetic acid as well as non-enhanced coronal HASTE, axial T1w-VIBE, fat-suppressed T2w-TSE and DWI. Quantitative analysis was performed using enhancement ratios between tumor and liver parenchyma for post-contrast in the hepatobiliary phase (RIRHB), arterial (ERa) and late-venous (ERv) phases as well as signal intensity ratios (liver/parenchyma) on T1w (RIRT1) and T2w (RIRT2).ResultsIn PCT analysis, all lesions exhibited high BFmax values (63–250 mL/100 g tissue) and were visible on HPI maps with high degrees of arterial blood supply of (HPI > 96%).In MRI, RIRHB was negative in 8/67. 12/67 HCCs were missed on DWI. 46/67 HCCs showed wash-in and 47/67 HCC showed wash-out of contrast agent. 6/67 HCCs were missed on T1w and 11/67 were missed on T2w-sequences when analyzed separately, while analysis of multiparametric MRI combining typical enhancement pattern, visibility on hepatobiliary phase and T1w-images the same number of lesions as PCT irrespective of their size (1–19 cm) were detected. Quantification of early enhancement by ERa or ERv did not improve detection rates.ConclusionsPerfusion-CT and gadoxetic acid-enhanced MRI were comparable in detecting HCC lesions. For PCT a mean HPI > 96% proved to be a very robust parameter for detection and characterization of HCC.
Highlights
MRI and perfusion-CT (PCT) are both useful imaging techniques for detection and characterization of liver lesions
MRI and PCT were performed within a mean of 8.8 days (SD 21.4); all examinations could be included in the following analysis
Quantitative and qualitative measurements in MRI First, MRI data were analyzed and the mean hepatocellular carcinoma (HCC) lesion size measured on T1w MRI images was 5.12 cm (SD 4.06). 6/67 HCCs were missed on T1w-images
Summary
MRI and perfusion-CT (PCT) are both useful imaging techniques for detection and characterization of liver lesions. Current guidelines recommend the use of dynamic contrast-enhanced CT ( volume perfusion CT, PCT) or MRI studies for assessment of “typical” enhancement patterns such as wash-in and wash-out [3]. These features reflect the temporal differences in the arterial and portal-venous blood supply of liver lesions vs liver parenchyma. Liver cirrhosis might as well lead to an increase in arterial supply of the liver parenchyma due to architectural distortion and subsequent portal hypertension This in turn may limit the contrast differences between HCC-precursors (e.g. dysplastic nodules) and liver parenchyma, hampering their accurate detection. With increasing dedifferentiation of focal liver lesions, their arterial supply steadily increases and the wash-in effect becomes more obvious
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