Correlation between liver iron content and magnetic resonance imaging in rats

Currently, serum ferritin concentration is the best noninvasive estimator of liver iron content. This study investigated the ability of magnetic resonance imaging to determine hepatic iron concentration. Fisher rats were treated with either parenteral iron to increase levels or phlebotomy to lower them and achieved a wide range of liver iron concentrations. Rats were imaged using a clinical whole body scanner at 1.5 Tesla with a 15-cm Helmholtz surface coil and a 23-cm field of view. The ratio of signal intensity of liver to skeletal muscle from images of the live intact rats correlated well with chemically measured iron concentration of the liver (r = −.89, p < .0001, linear regression analysis). Transverse relaxation rates (1/calculated T₂ relaxation times) also correlated with liver iron content (r = .66, p < .0001). The observation of a significant correlation between liver iron content and both signal intensities and T₂ relaxation rates, obtained by magnetic resonance imaging, may have considerable clinical relevance. If adapted to humans, this technique would have obvious applications in the diagnosis and management of diseases associated with iron overload as well as in the investigation of the overall role of iron in various human liver diseases.     

Relaxivities of human liver and spleen ferritin

Ferritin, the iron-storing protein of mammals, is known to darken T₂-weighted magnetic resonance images. This darkening can be used to noninvasively measure an organ's iron content. Significant discrepancies exist between T₂ data obtained with ferritin-containing tissues and with aqueous solutions of horse spleen ferritin (HSF). The NMR properties of stable human ferritin have never been studied in aqueous solutions. Relaxometry results on human liver and spleen ferritin are reported here, showing that the relaxation induced in aqueous solutions by human ferritins is comparable to that induced by HSF. As a consequence, the differences between ferritin-containing human tissues and ferritin solutions cannot be attributed to different NMR properties of human and horse ferritins, but probably to a clustering of the protein in vivo.     

MR findings of focal eosinophilic liver disease using gadoxetic acid

Purpose

The purpose of this study was to describe magnetic resonance (MR) findings of focal eosinophilic liver disease using gadoxetic acid (Gd-EOB-DTPA).

Materials and Methods

Nineteen patients (M:F=14:5; age range, 26–66 years; mean age, 50 years) with 35 focal eosinophilic liver lesions were included after reviewing the medical records of 482 patients who underwent Gd-EOB-DTPA-enhanced MR imaging (MRI) on a 3.0-T unit between April 2008 and June 2009. The diagnosis of focal eosinophilic liver disease was established by means of percutaneous liver biopsy or surgery and consistent clinical findings. Two radiologists retrospectively reviewed MR images with consensus. Margin, shape and distribution of the lesions were analyzed. We also evaluated signal intensity of focal hepatic lesions on T₁- and T₂-weighted images and patterns of enhancement in dynamic contrast study.

Results

The mean diameter of the lesions was 1.7 cm (range, 0.7–6.1 cm). Most of the focal eosinophilic liver lesions [n=31/35 (88.6%)] had poorly defined margins. They were usually isointense or slightly hypointense [n=34/35 (97.2%)] on T₁-weighted images and hyperintense [n=32/35 (91.4%)] on T₂-weighted images. Dynamic study showed enhancement (rim or homogeneous) on the arterial phase [n=21/35 (60%)] and hypointensity on the late venous phase [n=31/35 (88.6%)]. All the lesions were hypointense on the hepatobiliary phase images.

Conclusion

Focal eosinophilic liver lesions tend to be hyperintense on the arterial phase and hypointense on the late venous phase during dynamic study of Gd-EOB-DTPA-enhanced MRI. Although these findings mimic other focal hepatic lesions, poorly defined margins of the lesions and peripheral eosinophilia might help distinguish focal eosinophilic liver disease from other hepatic lesions.     

Comparison between multi-echo T2* with and without fat saturation pulse for quantification of liver iron overload

Purpose

To test a magnetic resonance image (MRI) technique that uses an additional pulse in multi-echo T2* sequence that works to suppress the fat signal, in subjects with liver iron overload and concomitant presence of fat in the liver, which have been revealed as a major drawback that compromises the correct iron quantification by MRI.

Materials and Methods

Fifty magnetic resonance images of the liver (1.5 T scanner) of individuals with blood ferritin increases were retrospectively reviewed for the presence of steatosis, using the sequence in and out of phase, and iron overloading, using two sequences T2 * multi-echo: one standard and other with additional fat suppression pulse. T2 * values and their standard deviations were analyzed statistically.

Results

Our results showed that a significantly lower standard deviation of T2* values is obtained when the fat saturation pulse is applied in patients with steatosis. We found that modulation of fat signal on liver iron overload resulted in a different categorization of some patients. In one case, the patient was re-classified within normal levels of liver iron.

Conclusion

Our findings may contribute to a better measure of liver iron overload with relevant implications for patient treatment and care.     

Potential clinical factors affecting hepatobiliary enhancement at Gd-EOB-DTPA-enhanced MR imaging

Objective

The objective was to clarify the clinical factors that might affect the degree of hepatic parenchymal enhancement at gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging.

Materials and Methods

A total of 84 patients with (n=63) and without chronic liver disease (n=21) underwent Gd-EOB-DTPA-enhanced MR imaging. Contrast-enhanced MR images of hepatobiliary phase (HP) were obtained at 20 min after Gd-EOB-DTPA administration. The relative enhancement (RE) of liver parenchyma at 20 min HP was calculated from region of interest measurements at each patient. Then, these results were correlated with various clinical parameters using Pearson correlation coefficient or Spearman rank correlation coefficient. Furthermore, the predictor of the degree of hepatic parenchymal enhancement was determined using multiple regression analysis.

Results

The presence or absence of chronic liver disease (P=.002), ascites (P=.005) and splenomegaly (P=.027), and the values of prothrombin activity (P=.008), total bilirubin (T-Bil) (P=.001), albumin (P=.001), aspartate aminotransferase (AST) (P=.002) and cholinesterase (P=.007) were significantly correlated with the RE of liver parenchyma at 20 min HP. Among these parameters, increases of T-Bil (P=.011 to .028) and AST (P=.018 to .049) were predictors of decreased hepatic parenchymal enhancement.

Conclusions

Hepatic parenchymal enhancement of Gd-EOB-DTPA was affected by various clinical parameters. Impaired hepatobiliary enhancement may be predicted by routine biochemical tests, such as T-Bil and AST.     

Optimal techniques for magnetic resonance imaging of the liver using a respiratory navigator-gated three-dimensional spoiled gradient-recalled echo sequence

Purpose

To optimize the navigator-gating technique for the acquisition of high-quality three-dimensional spoiled gradient-recalled echo (3D SPGR) images of the liver during free breathing.

Materials and methods

Ten healthy volunteers underwent 3D SPGR magnetic resonance imaging of the liver using a conventional navigator-gated 3D SPGR (cNAV-3D-SPGR) sequence or an enhanced navigator-gated 3D SPGR (eNAV-3D-SPGR) sequence. No exogenous contrast agent was used. A 20-ms wait period was inserted between the 3D SPGR acquisition component and navigator component of the eNAV-3D-SPGR sequence to allow T1 recovery. Visual evaluation and calculation of the signal-to-noise ratio were performed to compare image quality between the imaging techniques.

Result

The eNAV-3D-SPGR sequence provided better noise properties than the cNAV-3D-SPGR sequence visually and quantitatively. Navigator gating with an acceptance window of 2 mm effectively inhibited respiratory motion artifacts. The widening of the window to 6 mm shortened the acquisition time but increased motion artifacts, resulting in degradation of overall image quality. Neither slice tracking nor incorporation of short breath holding successfully compensated for the widening of the window.

Conclusion

The eNAV-3D-SPGR sequence with an acceptance window of 2 mm provides high-quality 3D SPGR images of the liver.     

The use of multivariate MR imaging intensities versus metabolic data from MR spectroscopic imaging for brain tumour classification

This study investigated the value of information from both magnetic resonance imaging and magnetic resonance spectroscopic imaging (MRSI) to automated discrimination of brain tumours. The influence of imaging intensities and metabolic data was tested by comparing the use of MR spectra from MRSI, MR imaging intensities, peak integration values obtained from the MR spectra and a combination of the latter two. Three classification techniques were objectively compared: linear discriminant analysis, least squares support vector machines (LS-SVM) with a linear kernel as linear techniques and LS-SVM with radial basis function kernel as a nonlinear technique. Classifiers were evaluated over 100 stratified random splittings of the dataset into training and test sets. The area under the receiver operating characteristic (ROC) curve (AUC) was used as a global performance measure on test data. In general, all techniques obtained a high performance when using peak integration values with or without MR imaging intensities. For example for low- versus high-grade tumours, low- versus high-grade gliomas and gliomas versus meningiomas, the mean test AUC was higher than 0.91, 0.94, and 0.99, respectively, when both MR imaging intensities and peak integration values were used. The use of metabolic data from MRSI significantly improved automated classification of brain tumour types compared to the use of MR imaging intensities solely.     

MR tracking of magnetically labeled mesenchymal stem cells in rats with liver fibrosis

Purpose

In vivo magnetic resonance (MR) tracking of magnetically labeled bone marrow mesenchymal stem cells (BMSCs) administered via the mesenteric vein to rats with liver fibrosis.

Materials and Methods

Rat BMSCs were labeled with superparamagnetic iron oxide (SPIO) and the characteristics of the BMSCs after labeling were investigated. Eighteen rats with CCL4-induced liver fibrosis were randomized to three groups to receive SPIO-labeled BMSCs (BMSC-labeled group), cell-free SPIO (SPIO group), or unlabeled BMSCs (control group). MR imaging of the liver was performed at different time points, and signal-to-noise ratio (SNR) of the liver was measured. In vivo distribution of delivered BMSCs was assessed by histological analysis.

Results

Labeling of BMSCs with SPIO did not significantly alter cell viability and proliferation activity. In BMSC-labeled group, the liver SNR immediately decreased from 8.56±0.26 to 3.53±0.41 at 1 h post injection and remained at a significantly lower level till 12 days (P<.05 versus the level before). By contrast, the liver SNR of the SPIO group almost recovered to the preinjection level (P=.125) at 3 days after a transient decrease. In control group, the liver SNR demonstrated no significant difference at the tested time points. Additionally, Prussian blue-positive cells were mainly distributed in the liver parenchyma, especially in injured areas.

Conclusion

The magnetically labeled BMSCs infused through the mesenteric vein can be detected in the fibrotic liver of rats using in vivo MR imaging up to 12 days after injection.     

Predictability of SNR and reader preference in clinical MR imaging

Fifty-four independent scans were performed in two volunteers covering one anatomic region in each (the brain and knee) with the purpose of ascertaining the agreement between predicted and measured signal-to-noise ratios (SNR). Systematically varied parameters were number of excitations (NEX), field of view (FOV), section thickness (d_z), and the number of phase-encoding steps (N_y). Correlation coefficients of measured versus predicted SNR were 0.82 and 0.86, respectively, in the anatomies studied. Significantly improved correlations were found for data subpopulations in which NEX was held constant. To assess the criteria guiding reader preference, a blinded study was performed in which radiologists were asked to rate images from least to most desirable. In order to quantitatively determine the criteria for reader preference, plots of mean rating versus SNR, voxel volume, and an image quality index [IQI = SNR/(voxel volume)] were performed. The latter was found to be a better predictor of reader preference than either SNR or spatial resolution alone. The data suggests T₁-weighted scan protocols yielding SNR of approximately 20 are preferable with any excess SNR being traded for smaller voxel size or shorter scan times.     

Hypervascular hepatocellular carcinoma in the cirrhotic liver: diffusion-weighted imaging versus superparamagnetic iron oxide-enhanced MRI

Purpose

The purpose of the study was to validate diffusion-weighted imaging (DWI) in the assessment of hypervascular hepatocellular carcinoma (HCC) compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the cirrhotic liver.

Material and Methods

Forty-six consecutive patients with 106 hypervascular focal lesions in the cirrhotic liver who underwent DWI using three b factors and gadopentetate dimeglumine-enhanced dynamic MRI followed by SPIO-enhanced MRI were enrolled. Two independent radiologists evaluated two separated image sets (SPIO set, dynamic MRI and SPIO-enhanced T2*-weighted images; DWI set, DWI and dynamic MRI) and assigned confidence levels for diagnosis of HCC using a five-point scale for each lesion. Area under the receiver operating characteristic curve (A_z) was calculated for each image set.

Results

The A_z value of the DWI set was larger than the SPIO set by both readers (reader 1, 0.936 vs. 0.900, P=.050; reader 2, 0.938 vs. 0.905, P=.110). For the sensitivity (reader 1, 93.1% vs. 86.2%, P=.146; reader 2, 95.4% vs. 88.5%, P=.070) and specificity (reader 1, 89.5% vs. 73.7%, P=.250; reader 2, 79.0% vs. 73.7%, P=1.000) of HCC diagnosis, DWI sets were superior to SPIO sets without statistically significant differences.

Conclusion

For assessment of hypervascular HCC, DWI in combination with dynamic MRI provides comparable or slightly better information compared with the combination of dynamic and SPIO-enhanced MRI.     

Diffusion-weighted MR imaging for assessing synovitis of wrist and hand in patients with rheumatoid arthritis: A feasibility study

The purpose of this study was to investigate the feasibility of diffusion-weighted imaging (DWI) in detecting synovitis of wrist and hand in patients with rheumatoid arthritis (RA) and evaluate its sensitivity, specificity and accuracy as compared to T₂-weighted imaging (T2WI) with short tau inversion recovery (STIR) with the reference standard contrast-enhanced magnetic resonance imaging (CE-MRI). Twenty-five patients with RA underwent MR examinations including DWI, T2WI with STIR and CE-MRI. MR images were reviewed for the presence and location of synovitis of wrist and hand. The sensitivity, specificity and accuracy of DWI and T2WI with STIR were calculated respectively and then compared. All patients included in this study completed MR examinations and yielded diagnostic image quality of DWI. For individual joint, there was good to excellent inter-observer agreement (k = 0.62–0.83) using DWI images, T2WI with STIR images and CE-MR images, respectively. There was a significance between DWI and T2WI with STIR in analyzing proximal interphalangeal joints II–V, respectively (P < 0.05). The k-values for the detection of synovitis indicated excellent overall inter-observer agreements using DWI images (k = 0.86), T2WI with STIR images (k = 0.85) and CE-MR images (k = 0.91), respectively. Overall, DWI demonstrated a sensitivity, specificity and accuracy of 75.6%, 89.3% and 84.6%, respectively, for detection of synovitis, while 43.0%, 95.7% and 77.6% for T2WI with STIR, respectively. DWI showed positive lesions much better and more than T2WI with STIR. Our results indicate that DWI presents a novel non-invasive approach to contrast-free imaging of synovitis. It may play a role as an addition to standard protocols.     

The short TI inversion recovery sequence--an approach to MR imaging of the abdomen

Initial clinical experience with magnetic resonance imaging (MRI) of the abdomen using short TI inversion-recovery (STIR) pulse sequences is described and compared with X-ray CT in a variety of abdominal disease. The extent of abnormality shown with MRI was greater than that with CT in 21 of 30 cases and equal in 9 cases. Lesion contrast was greater with MRI in 15 cases, equal in 14 and less in 1. The level of artefact was equal in 27 cases and greater with MRI in 3 cases. The STIR pulse sequence has significant advantages in producing high soft-tissue contrast, controlling respiratory artefact, avoiding confusion with intra-abdominal fat and identifying bowel loops.     

Labeling of macrophages using bacterial magnetosomes and their characterization by magnetic resonance imaging

This work investigated macrophages labeled with magnetosomes for the possible detection of inflammations by MR molecular imaging. Pure magnetosomes and macrophages containing magnetosomes were analyzed using a clinical 1.5 T MR-scanner. Relaxivities of magnetosomes and relaxation rates of cells containing magnetosomes were determined. Peritonitis was induced in two mice. T₁, T₂ and T₂* weighted images were acquired following injection of the probes. Pure magnetosomes and labeled cells showed slight effects on T₁, but strong effects on T₂ and T₂* images. Labeled macrophages were located with magnetic resonance imaging (MRI) in the colon area, thus demonstrating the feasibility of the proposed approach.     

Magnetic resonance imaging with superparamagnetic iron oxide particles for the detection of myocardial reperfusion

The effect of superparamagnetic iron oxide particles on magnetic resonance myocardial signal intensity was examined in order to define the ability of this agent to identify normal, ischemic, and reperfused myocardium. Data were obtained from 6 normal rats (group 1) and from 6 heterotopic isogenic rat heart transplants (group 2) at 4.7 T with a multislice spin-echo sequence. Images were acquired in (a) normal rats before and after the infusion of 36 μmol Fe/kg of AMI-25 (group 1) and (b) rat heart transplants during control, global myocardial ischemia (before and after the injection of 72 μmol Fe/kg of AMI-25), and following reperfusion (group 2). Myocardial signal intensity decreased by 36 ± 4%, p < 0.001, following contrast infusion in normal hearts (group 1). The intensity remained constant in the rat heart transplants (group 2) during coronary occlusion, both before and after the infusion of AMI-25 and decreased by 61 ± 7%, p < 0.001, upon reperfusion. The larger effect of AMI-25 in reperfused as compared to normal myocardium suggests the presence of ischemia-induced hyperemia. There was no significant difference (analysis of variance) among intensities from different myocardial regions in either group at any stage of the experiment. We conclude that the use of AMI-25 permits identification of normal, ischemic, and reperfused myocardium and may therefore be helpful for the early detection of reperfusion following thrombolytic therapy for acute myocardial infarction.     

Improved T2* assessment in liver iron overload by magnetic resonance imaging

In the clinical MRI practice, it is common to assess liver iron overload by T2* multi-echo gradient-echo images. However, there is no full consensus about the best image analysis approach for the T2* measurements. The currently used methods involve manual drawing of a region of interest (ROI) within MR images of the liver. Evaluation of a representative liver T2* value is done by fitting an appropriate model to the signal decay within the ROIs vs. the echo time. The resulting T2* value may depend on both ROI placement and choice of the signal decay model. The aim of this study was to understand how the choice of the analysis methodology may affect the accuracy of T2* measurements. A software model of the iron overloaded liver was inferred from MR images acquired from 40 thalassemia major patients. Different image analysis methods were compared exploiting the developed software model. Moreover, a method for global semiautomatic T2* measurement involving the whole liver was developed. The global method included automatic segmentation of parenchyma by an adaptive fuzzy-clustering algorithm able to compensate for signal inhomogeneities. Global liver T2* value was evaluated using a pixel-wise technique and an optimized signal decay model. The global approach was compared with the ROI-based approach used in the clinical practice. For the ROI-based approach, the intra-observer and inter-observer coefficients of variation (CoVs) were 3.7% and 5.6%, respectively. For the global analysis, the CoVs for intra-observers and inter-observers reproducibility were 0.85% and 2.87%, respectively. The variability shown by the ROI-based approach was acceptable for use in the clinical practice; however, the developed global method increased the accuracy in T2* assessment and significantly reduced the operator dependence and sampling errors. This global approach could be useful in the clinical arena for patients with borderline liver iron overload and/or requiring follow-up studies.     

Quantitative comparison between a multiecho sequence and a single-echo sequence for susceptibility-weighted phase imaging

The aim of this study was to investigate the benefits arising from the use of a multiecho sequence for susceptibility-weighted phase imaging using a quantitative comparison with a standard single-echo acquisition. Four healthy adult volunteers were imaged on a clinical 3-T system using a protocol comprising two different three-dimensional susceptibility-weighted gradient-echo sequences: a standard single-echo sequence and a multiecho sequence. Both sequences were repeated twice in order to evaluate the local noise contribution by a subtraction of the two acquisitions. For the multiecho sequence, the phase information from each echo was independently unwrapped, and the background field contribution was removed using either homodyne filtering or the projection onto dipole fields method. The phase information from all echoes was then combined using a weighted linear regression. R2 maps were also calculated from the multiecho acquisitions. The noise standard deviation in the reconstructed phase images was evaluated for six manually segmented regions of interest (frontal white matter, posterior white matter, globus pallidus, putamen, caudate nucleus and lateral ventricle). The use of the multiecho sequence for susceptibility-weighted phase imaging led to a reduction of the noise standard deviation for all subjects and all regions of interest investigated in comparison to the reference single-echo acquisition. On average, the noise reduction ranged from 18.4% for the globus pallidus to 47.9% for the lateral ventricle. In addition, the amount of noise reduction was found to be strongly inversely correlated to the estimated R2 value (R=-0.92). In conclusion, the use of a multiecho sequence is an effective way to decrease the noise contribution in susceptibility-weighted phase images, while preserving both contrast and acquisition time. The proposed approach additionally permits the calculation of R2 maps.     

Diffusion-weighted imaging versus superparamagnetic iron oxide (SPIO)-enhanced MRI: exclusive and combined values in the assessment of hepatic metastases

Purpose

The purpose was to validate diffusion-weighted imaging (DWI) in the assessment of hepatic metastases compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging.

Materials and Methods

For 21 consecutive patients with 160 metastases from extrahepatic malignancy and 25 benign focal lesions, two radiologists evaluated four separate review sessions (I, SPIO-enhanced T2?-weighted images; II, precontrast DWI; III, SPIO-enhanced T2?-weighted images and precontrast DWI; IV, SPIO-enhanced T2?-weighted images plus precontrast and SPIO-enhanced DWI) and assigned confidence levels using a five-grade scale for each hepatic lesion.

Results

The A_z values after receiver operating characteristic curve analysis for Reader 1 and Reader 2 were 0.80 and 0.75 on session I, 0.91 and 0.91 on session II, 0.97 and 0.96 on session III and 0.96 and 0.96 on session IV, respectively. The A_z value of session II was significantly higher than that of session I (Reader 1, P=.004; Reader 2, P<.001), and that of session III was significantly higher than that of session I (P<.001 for each reader) or session II (Reader 1, P=.004; Reader 2, P=.003). Although there was no significant difference of A_z value between session III and session IV (Reader 1, P=.231; Reader 2, P=.878), the sensitivity improved for session IV compared with that for session III (Reader 1, P=.031; Reader 2, P=.039).

Conclusion

In the assessment of hepatic metastases, DWI can provide more accurate information than can SPIO-enhanced images. Diagnostic accuracy can be increased even more through the combination of both techniques.     

Magnetic resonance imaging and pulsed Doppler sonography of poststenotic jets: Correlation between signal void and flow velocity distribution

To correlate the appearance of poststenotic jets on gradient echo images with features of localized Doppler spectra of the jets, we studied an in vitro model of steady flow-through stenoses of 86, 96, and 99% area reduction. As fluids, water and a 40% glycerol solution in water were used. MRI was performed with a 1.5 T whole body imager and gradient echo images were obtained in planes parallel to the direction of flow. Doppler spectra were acquired separately from the MR measurements at 1 cm intervals for a distance of 10 cm downstream from the stenosis. Poststenotic signal void was observed for water and for the 40% glycerol solution only if the mean velocity within the stenosis exceeded a limit of 50–60 cm/sec. On the MR images, the jets could be divided into two segments: A proximal jet segment of uniform width equal to the diameter of the stenosis, followed by a distal jet segment which was characterized by broadening and then dissipating signal void. Except for the 99% stenosis, a high signal intensity core was present within the proximal jet segment. In the proximal jet segment, the Doppler measurements showed a low temporal fluctuation of the maximal flow velocity and only little flow opposite to the main flow direction. In the distal jet segment, the velocity fluctuation and the intensity of reverse flow increased sharply. The high signal intensity core of the jet was associated with a poststenotic zone of constant maximal flow velocity. The results demonstrate a close relationship between characteristic features of poststenotic jets in MRI and pulsed Doppler sonography.     

Staging liver fibrosis by using liver-enhancement ratio of gadoxetic acid-enhanced MR imaging: comparison with aspartate aminotransferase-to-platelet ratio index

Objective

To compare the diagnostic ability of gadoxetic acid-enhanced hepatocyte-phase MR images with aspartate aminotransferase-to-platelet ratio index (APRI) to predict liver fibrosis stage.

Materials and Methods

Our study included 100 patients who underwent gadoxetic acid-enhanced MRI and either liver biopsy or liver surgery. Liver fibrosis stage was histologically determined according to the METAVIR system: F0 (n=16), F1 (n=17), F2 (n=10), F3 (n=21) and F4 (n=36). Four measures were used as imaging-based fibrosis markers: liver-spleen contrast ratio, liver-enhancement ratio, corrected liver-enhancement ratio and spleen index. APRI represented a blood test-based fibrosis marker. The diagnostic ability of those fibrosis markers were compared through receiver-operating characteristic analysis.

Results

The area under the curve (AUC) for APRI prediction of severe fibrosis (≥F3 and F4) was significantly greater than that of corrected liver-enhancement ratio. However, corrected liver-enhancement ratio had a greater AUC for prediction of mild fibrosis (≥F1) than APRI, although the difference was insignificant.

Conclusion

Corrected liver-enhancement ratio with gadoxetic acid-enhanced MRI is correlated to the stage of liver fibrosis. APRI, however, has greater reliability for predicting severe fibrosis and cirrhosis than does the imaging-based fibrosis marker tested in this study.