Distinguishing hemangiomas from malignant solid hepatic lesions: a comparison of heavily T2-weighted images obtained before and after administration of gadoxetic acid

Purpose:

To compare the use of heavily T2‐weighted images obtained before and after administration of gadoxetic acid in differentiating hemangiomas from malignant solid hepatic lesions.

Materials and Methods:

Heavily T2‐weighted images (TE = 150 msec) were obtained for 70 patients (42 men and 28 women) with 74 focal hepatic lesions (25 hepatocellular carcinomas [HCC], 22 metastases, and 27 hemangiomas) ≤3 cm in diameter before and after gadoxetic acid‐enhanced dynamic magnetic resonance imaging (MRI). Quantitative analysis was performed using receiver operating characteristic (ROC) curves with lesion‐to‐liver signal intensity difference‐to‐noise ratio (SDNR) on precontrast and postcontrast images. Qualitative analysis was also performed by two blinded reviewers.

Results:

The SDNR of the solid lesions was significantly higher on the postcontrast (1.66 ± 1.18) than on the precontrast (1.38 ± 1.07) images (P = 0.0012), while the SDNR of hemangiomas was comparable for pre‐ and postcontrast images (P = 0.8164). The best SDNR cutoff values for distinguishing solid lesions from hemangiomas were ≤1.85 (Az = 0.948) for precontrast and ≤2.58 (Az = 0.901) for postcontrast images (P = 0.057). Reader performances for distinguishing hemangiomas from solid lesions were comparable between the precontrast (Az = 0.975 and 0.970 for readers 1 and 2) and postcontrast (Az = 0.977 and 0.972) images (P = 0.899 and 0.946).

Conclusion:

Heavily T2‐weighted images obtained after administration of gadoxetic acid have a diagnostic capability comparable to precontrast images for differentiating between small hemangiomas and malignant solid lesions of the liver. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

MRI of the lung: value of different turbo spin-echo, single-shot turbo spin-echo, and 3D gradient-echo pulse sequences for the detection of pulmonary metastases

PURPOSE: To compare the value of different MRI sequences of the lung for the detection of pulmonary metastases. MATERIALS AND METHODS: A total of 28 patients with 225 pulmonary metastases confirmed at multidetector-row computed tomography (MDCT) underwent MRI of the lung, including breathhold T2-weighted single-shot turbo spin-echo (half-Fourier single-shot turbo spin-echo [HASTE] and inversion recovery [IR]-HASTE) and conventional turbo spin-echo (TSE and short-tau inversion recovery [STIR]) sequences, a respiratory- and pulse-triggered black-blood STIR sequence (triggered STIR), and breathhold pre- and postcontrast volumetric interpolated 3D gradient-echo (VIBE) sequences. MR images were reviewed by three independent observers and results were correlated with MDCT, which served as standard of reference. Lesion-to-lung contrast-to-noise ratios (CNRs) and image artifacts were also assessed. RESULTS: CNRs were highest on TSE images (P < 0.001). Mean sensitivities for lesion detection with triggered STIR, TSE, and STIR were 72.0%, 69.0%, and 63.4%, respectively. With HASTE, IR-HASTE, and pre- and postcontrast VIBE, significantly lower sensitivities were obtained (P < 0.05), although artifacts due to physiological motion were less distinct with these sequences compared to TSE and STIR (P < 0.05). CONCLUSION: Conventional TSE sequences are more sensitive in depicting pulmonary metastases than single-shot TSE or 3D gradient-echo sequences. Respiratory and pulse triggering can improve lesion detection, but increases acquisition time substantially.     

Combined gadoxetic acid and gadofosveset enhanced liver MRI for detection and characterization of liver metastases

Purpose

To compare gadoxetic acid alone and combined gadoxetic acid/gadofosveset trisodium-enhanced liver MRI for detection of metastases and differentiation of metastases from haemangiomas.

Methods

Ninety-one patients underwent gadoxetic acid-enhanced liver MRI before and after additional injection of gadofosveset. First, two readers retrospectively identified metastases on gadoxetic acid alone enhanced delayed hepatobiliary phase T1-weighted images together with all other MR images (dynamic images, T2-weighted images, diffusion-weighted images). Second, readers assessed additional T1-weighted images obtained after administration of gadofosveset trisodium. For both interpretations, readers rated lesion conspicuity and confidence in differentiating metastases from haemangiomas. Results were compared using alternative free-response receiver-operating characteristic (AFROC) and conventional ROC methods. Histology and follow-up served as reference standard.

Results

There were 145 metastases and 16 haemangiomas. Both readers detected more metastases using combined gadoxetic acid/gadofosveset (reader 1?=?130; reader 2?=?124) compared to gadoxetic acid alone (reader 1?=?104; reader 2?=?103). Sensitivity of combined gadoxetic acid/gadofosveset (reader 1?=?90 %; reader 2?=?86 %) was higher than that of gadoxetic acid alone (reader 1?=?72 %; reader 2?=?71 %, both P?<?0.01). AFROC-AUC was higher for the combined technique (0.92 vs. 0.86, P?<?0.001). Sensitivity for correct differentiation of metastases from haemangiomas was higher for the combined technique (reader 1?=?98 %; reader 2?=?99 % vs. reader 1?=?86 %; reader 2?=?91 %, both P?<?0.01). ROC-AUC was significantly higher for the combined technique (reader 1?=?1.00; reader 2?=?1.00 vs. reader 1?=?0.87; reader 2?=?0.92, both P?<?0.01).

Conclusion

Combined gadoxetic acid/gadofosveset-enhanced MRI improves detection and characterization of liver metastases compared to gadoxetic acid alone.

Key Points

? Combined gadoxetic acid and gadofosveset-enhanced liver MRI significantly improves detection of metastases. ? The combined enhancement technique improves the accuracy to differentiate metastases from haemangiomas. ? Prospective studies need to determine the clinical impact of the combined technique

     

Comparative study of image quality between axial T2-weighted BLADE and turbo spin-echo MRI of the upper abdomen on 3.0 T

Objective

To compare image quality of turbo spin-echo (TSE) with BLADE [which is also named periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER)] on magnetic resonance imaging (MRI) for upper abdomen.

Materials and methods

This study involved the retrospective evaluation of 103 patients (63 males, 40 females; age range 19–76 years; median age 53.8 years) who underwent 3.0 T MRI with both conventional TSE T2-weighted imaging (T2WI) and BLADE TSE T2WI. Two radiologists assessed respiratory motion, gastrointestinal peristalsis, and vascular pulsation artifacts, as well as the sharpness of the liver and pancreas edges. Scores for all magnetic resonance (MR) images were recorded. Wilcoxon’s rank test was used to compare hierarchical data. Cohen’s kappa coefficient was adopted to analyze interobserver consistency.

Results

Compared to TSE T2WI, BLADE TSE T2WI reduced all of the examined motion artifacts and increased the sharpness of the liver and pancreas edges (all P < 0.05). Medium to good interobserver consistency was obtained for evaluating these indicators. The scanning time of BLADE TSE T2WI was 4–16 s shorter than that of conventional TSE T2WI.

Conclusion

Compared to TSE sequence, the BLADE technique can reduce the respiratory motion, gastrointestinal peristalsis, and vascular pulsation artifacts, while decreasing the scanning time and improving the anatomic detail and image quality.

     

Differentiating malignant from benign hyperintense nodules on unenhanced T1-weighted images in patients with chronic liver disease: using gadoxetic acid-enhanced and diffusion-weighted MR imaging

Purpose

To evaluate value of gadoxetic acid-enhanced and diffusion-weighted (DW) MRI for distinguishing malignant from benign hyperintense nodules on unenhanced T1-weighted images (T1WIs) in patients with chronic liver disease.

Materials and methods

Forty-two patients with 37 malignant and 41 benign hyperintense nodules on unenhanced T1WIs who underwent gadoxetic acid-enhanced and DW MRI, followed by histopathological examination, were included. Qualitative and quantitative analyses were conducted. Significant findings on univariate and multivariate analyses were identified and their diagnostic performances were analyzed for predicting hyperintense hepatocellular carcinomas (HCCs).

Results

In univariate analysis, hyperintensity on T2WI, arterial enhancement, washout, hypointensity on hepatobiliary phase, and diffusion restriction were more frequently observed (P?<?0.05) in hyperintense HCCs. Tumor-to-liver SI ratio on hepatobiliary phase and minimum apparent diffusion coefficient (ADC_min) were significantly lower in hyperintense HCCs (P?<?0.05). In multivariate analysis, hyperintensity on T2WI (OR, 13.58; P?=?0.02), arterial enhancement (OR, 8.21; P?=?0.002), and ADC_min?≤?0.83?×?10^?3 mm²/s (OR, 6.88; P?=?0.008) were independently significant factors for predicting hyperintense HCCs. When two of three criteria were combined, 75.7% (28/37) of hyperintense HCCs were identified with a specificity of 92.7%, and when all three criteria were satisfied, the specificity was 97.6%.

Conclusion

Gadoxetic acid-enhanced and DW MRI may be helpful for differentiating malignant from benign hyperintense nodules on unenhanced T1WI.

     

T2-Weighted Liver MRI Using the MultiVane Technique at 3T: Comparison with Conventional T2-Weighted MRI

Objective

To assess the value of applying MultiVane to liver T2-weighted imaging (T2WI) compared with conventional T2WIs with emphasis on detection of focal liver lesions.

Materials and Methods

Seventy-eight patients (43 men and 35 women) with 86 hepatic lesions and 20 pancreatico-biliary diseases underwent MRI including T2WIs acquired using breath-hold (BH), respiratory-triggered (RT), and MultiVane technique at 3T. Two reviewers evaluated each T2WI with respect to artefacts, organ sharpness, and conspicuity of intrahepatic vessels, hilar duct, and main lesion using five-point scales, and made pairwise comparisons between T2WI sequences for these categories. Diagnostic accuracy (Az) and sensitivity for hepatic lesion detection were evaluated using alternative free-response receiver operating characteristic analysis.

Results

MultiVane T2WI was significantly better than BH-T2WI or RT-T2WI for organ sharpness and conspicuity of intrahepatic vessels and main lesion in both separate reviews and pairwise comparisons (p < 0.001). With regard to motion artefacts, MultiVane T2WI or BH-T2WI was better than RT-T2WI (p < 0.001). Conspicuity of hilar duct was better with BH-T2WI than with MultiVane T2WI (p = 0.030) or RT-T2WI (p < 0.001). For detection of 86 hepatic lesions, sensitivity (mean, 97.7%) of MultiVane T2WI was significantly higher than that of BH-T2WI (mean, 89.5%) (p = 0.008) or RT-T2WI (mean, 84.9%) (p = 0.001).

Conclusion

Applying the MultiVane technique to T2WI of the liver is a promising approach to improving image quality that results in increased detection of focal liver lesions compared with conventional T2WI.     

The uptake transporter OATP8 expression decreases during multistep hepatocarcinogenesis: correlation with gadoxetic acid enhanced MR imaging

Objectives

To clarify the changes in organic anion-transporting polypeptide 8 (OATP8) expression and enhancement ratio on gadoxetic acid-enhanced MR imaging in hepatocellular nodules during multistep hepatocarcinogenesis.

Methods

In imaging analysis, we focused on 71 surgically resected hepatocellular carcinomas (well, moderately and poorly differentiated HCCs) and 1 dysplastic nodule (DN). We examined the enhancement ratio in the hepatobiliary phase of gadoxetic acid enhanced MR imaging [(1/postcontrast T1 value?1/precontrast T1 value)/(1/precontrast T1 value)], then analysed the correlation among the enhancement ratio, tumour differentiation grade and intensity of immunohistochemical OATP8 expression. In pathological analysis, we focused on surgically resected 190 hepatocellular nodules: low-grade DNs, high-grade DNs, early HCCs, well-differentiated, moderately differentiated and poorly differentiated HCCs, including cases without gadoxetic acid-enhanced MR imaging. We evaluated the correlation between the immunohistochemical OATP8 expression and the tumour differentiation grade.

Results

The enhancement ratio of HCCs decreased in accordance with the decline in tumour differentiation (P?R?=?0.28) and with the decline of OATP8 expression (P?R?=?0.81). The immunohistochemical OATP8 expression decreased from low-grade DNs to poorly differentiated HCCs (P?R?=?0.15).

Conclusions

The immunohistochemical expression of OATP8 significantly decreases during multistep hepatocarcinogenesis, which may explain the decrease in enhancement ratio on gadoxetic acid-enhanced MR imaging.     

Three-dimensional contrast-enhanced hepatic MR imaging: comparison between a centric technique and a linear approach with partial Fourier along both slice and phase directions

Purpose

To compare the image quality of two variants of a three‐dimensional (3D) gradient echo sequence (GRE) for hepatic MRI.

Materials and Methods

Thirty‐nine patients underwent hepatic MRI on a 3.0 Tesla (T) magnet (Intera Achieva; Philips Medical Systems). The clinical protocol included two variants of a 3D GRE with fat suppression: (i) a “centric” approach, with elliptical centric k‐space ordering and (ii) an “enhanced” approach using linear sampling and partial Fourier in both the slice and phase encoding direction. “Centric” and “Enhanced” 3D GRE images were obtained both precontrast (n = 32) and after gadoxetic acid injection (n = 39). Two reviewers jointly reviewed MR images for anatomic sharpness, overall contrast, homogeneity, and absence of artifacts. The liver‐to‐lesion signal difference ratio (SDR) was measured. Paired sample Wilcoxon test and paired t‐tests were used.

Results

Enhanced 3D GRE images performed better than centric 3D GRE images with respect to anatomic sharpness (P = 0.0156), overall contrast (P = 0.0195), homogeneity (P < 0.0001), and absence of artifacts (P = 0.0003) on precontrast images. For postcontrast MRI, enhanced 3D GRE images showed better quality in terms of overall contrast (P = 0.0195), homogeneity (P < 0.0001), and absence of artifacts (P = 0.009). Liver‐to‐lesion SDR on enhanced 3D GRE images (0.48 ± 0.13) was significantly higher than that of conventional 3D GRE images (0.40 ± 0.19, P = 0.0004) on postcontrast images, but not on precontrast images.

Conclusion

The enhanced 3D GRE sequence available on our scanner provided better hepatic image quality than the centric variant, without compromising lesion contrast. J. Magn. Reson. Imaging 2011;33:160–166. © 2010 Wiley‐Liss, Inc.     

Comparison of gadoxetic acid-enhanced dynamic imaging and diffusion-weighted imaging for the preoperative evaluation of colorectal liver metastases

Purpose:

To retrospectively compare the diagnostic accuracy for the detection of colorectal liver metastases between gadoxetic acid‐enhanced MRI (EOB‐MRI) and diffusion‐weighted imaging (DWI) on 3.0 Tesla (T) system, and then to determine whether a combination of the two techniques may improve the diagnostic performance.

Materials and Methods:

Forty‐seven patients underwent MR imaging at 3.0T, including DWI (DWI set) and dynamic and hepatobiliary phase EOB‐MRI (EOB set) for the preoperative evaluation of colorectal liver metastases. All suspicious metastases were confirmed by hepatic surgery. Two blinded readers independently reviewed three different image sets, which consisted of DWI set, EOB set, and combined set. The accuracy was assessed by the area (Az) under the alternative‐free response receiver operating characteristic curve, and the sensitivity and positive predictive value (PPV) were calculated.

Results:

We found a total of 78 confirmed colorectal liver metastases in 42 of 47 patients. Each reader noted higher diagnostic accuracy of combined set of EOB‐MRI and DWI than DWI set and EOB set, without statistical significance. Regardless of the size of colorectal liver metastasis, each reader detected significantly more metastases on combined set than on DWI set, and PPV was significantly higher with DWI set than with EOB set or with combined set for one reader.

Conclusion:

EOB‐MRI was more useful for the detection of colorectal liver metastases, while DWI was more useful for their characterization. The combination of EOB‐MRI and DWI showed significantly higher accuracy and sensitivity for the preoperative detection of small colorectal liver metastases than DWI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

MRI in focal liver disease: A comparison of small and ultra-small superparamagnetic iron oxide as hepatic contrast agents

The purpose of this study was to compare small and ultrasmall superparamagnetic iron oxide particles (SPIO and USPIO, respectively) as MR contrast agents for the evaluation of focal hepatic disease. In two different patient groups (SPIO [n = 53], USPIO [n = 27]), with focal liver disease (metastases, hepatocellular carcinoma [HCC], hepatocellular adenoma [HCA], and focal nodular hyperplasia [FNH]), spin-echo T1- and T2-weighted images (T1WI, T2WI) were obtained at 1.0T, before and after intravenous contrast administration. The percentage signal-to-noise ratio (SNR) change and lesion-to-liver contrast (LLC) were measured and statistically compared. The liver decreased in signal intensity (SI) after SPIO administration (?28%) and increased after USPIO administration (+16%) on T1WI. On T2WI, the liver decreased in SI on postcontrast images with both agents (?78% SPIO, ?73% USPIO). This difference was not statistically significantly different (P ? .07). Both SPIO and USPIO provided >500% improvement in LLC on T2WI. On T1WI, LLC was increased in metastases (120%) and HCC (325%) with SPIO. Post-USPIO, LLC was increased on T1WI only in metastases (>500%). Both SPIO and USPIO show excellent hepatic uptake, presumed secondary to reticuloendothelial activity, based on the degree of %SI change seen in the liver after administration of contrast on T2WI. However, USPIO preparations exhibit blood pool activity that may aid in further characterization of focal liver lesions, as is evidenced by their greater T1 effect in the liver and in some focal liver lesions.     

Enhancement of the liver and pancreas in the hepatic arterial dominant phase: Comparison of hepatocyte‐specific MRI contrast agents,gadoxetic acid and gadobenate dimeglumine,on 3 and 1.5 tesla MRI in the same patient

Purpose:

To evaluate the relative enhancement of liver, pancreas, focal nodular hyperplasia (FNH), pancreas‐to‐liver index, and FNH‐to‐liver index in the hepatic arterial dominant phase (HADP) after injection of hepatocyte‐specific MRI contrast agents, gadoxetic acid and gadobenate dimeglumine, on 3 and 1.5 Tesla (T) MRI in the same patient.

Materials and Methods:

The MRI database was retrospectively searched to identify consecutive patients who underwent abdominal MRI at 3T and 1.5T systems, using both 0.025 mmol/kg gadoxetic acid‐enhanced and 0.05 mmol/kg gadobenate dimeglumine‐enhanced MRI at the same magnetic strength field system. 22 patients were identified, 10 were scanned at 3T system and 12 at 1.5T system. The enhancement of liver, pancreas, and FNH was evaluated quantitatively on MR images.

Results:

The relative enhancement of liver in HADP in the gadobenate dimeglumine‐enhanced group in all subjects was significantly higher than that in gadoxetic acid‐enhanced group (P = 0.023). The gadobenate dimeglumine‐enhanced group in HADP had better relative enhancement of pancreas and FNH, pancreas‐to‐liver index, and FNH‐to‐liver index than gadoxetic acid‐enhanced group, but the difference was not statistically significant.

Conclusion:

The 0.05 mmol/kg gadobenate dimeglumine‐enhanced abdominal MRI studies at 3T and 1.5T MR systems are superior in relative enhancement of the liver in HADP to 0.025 mmol/kg gadoxetic acid‐enhanced MRI. This type of assessment may provide comparative effectiveness data. J. Magn. Reson. Imaging 2013;37:903–908. © 2012 Wiley Periodicals, Inc.     

Whole-body MRI including diffusion-weighted imaging (DWI) for patients with recurring prostate cancer: technical feasibility and assessment of lesion conspicuity in DWI

Purpose:

To evaluate the principal methodological aspects of whole‐body magnetic resonance imaging (MRI) including diffusion‐weighted imaging (DWI) with background suppression using a time‐optimized protocol for restaging of prostate cancer patients in a technical feasibility study.

Materials and Methods:

Seventeen patients underwent MRI at 1.5T from the base of the skull to the proximal thigh using axial T1‐weighted (T1w), T2w short‐tau inversion recovery (STIR), and DWI (b‐values: 50 and 500 s/mm²) and sagittal T1w and T2w STIR of the spine. Apparent diffusion coefficient (ADC) values of liver, spleen, kidney, muscle, and bone were measured. Image quality in DWI was assessed by using a scale from 0–9. Contrast‐to‐noise ratios (CNRs) of lymph node and bone metastases were determined in T1w, T2w STIR, and DWI. Bone metastases were further subclassified according to their Hounsfield units (HU) in computed tomography (CT).

Results:

Mean acquisition and mean room times were 66:20 and 75:21 minutes, respectively. ADC values of normal organs showed good concordance with reported data. Good to excellent image quality was observed for DWI (mean scores 7.41–8.00) with the exception of the neck (mean score 4.76). CNR of DWI (b‐value 50 s/mm²) for lymph node metastases was clearly superior compared to all other sequences. For bone metastases T1w performed significantly better for sclerotic lesions (HU > 600), DWI (b‐value 50 s/mm²) for nonsclerotic lesion (HU < 300).

Conclusion:

In patients with recurrent prostate cancer a whole‐body MR protocol including DWI is technically robust. Due to the high CNR of DWI compared to T1w and T2w STIR, detection of malignant lesions should be facilitated by DWI, except for sclerotic bone metastases. J. Magn. Reson. Imaging 2011;33:1160–1170. © 2011 Wiley‐Liss, Inc.     

Improved detection of focal liver lesions at MR imaging: multicenter comparison of gadoxetic acid-enhanced MR images with intraoperative findings

PURPOSE: To evaluate the safety and efficacy of gadoxetic acid disodium-enhanced magnetic resonance (MR) imaging for the detection of focal liver lesions, with results of histopathologic examination and/or intraoperative ultrasonography used as a standard of reference. MATERIALS AND METHODS: One hundred sixty-nine patients who were known to have or suspected of having focal liver lesions and were scheduled for liver surgery were included in this study. Results in 131 patients could be included in the efficacy analysis. MR imaging was performed before and immediately and 20 minutes after bolus injection of 0.025 mmol/kg of the liver-specific hepatobiliary contrast agent gadoxetic acid. T1-weighted gradient-echo (with and without fat saturation and including dynamic data sets) and T2-weighted fast spin-echo/turbo spin-echo sequences were performed. All images were evaluated on site and by three independent and blinded off-site reviewers. Lesion matching based on the standard-of-reference results was performed. Differences in lesion detection with precontrast and with postcontrast MR images were assessed with the two-sided Wilcoxon signed rank test. RESULTS: Gadoxetic acid was well tolerated. In the on-site review, the number of patients in whom all lesions were correctly matched increased from 89 of 129 patients at precontrast MR imaging to 103 of 129 patients at postcontrast MR imaging. In the off-site evaluation, the number of patients in whom all lesions were correctly matched and the corresponding sensitivity values increased from 72 (55.8%), 68 (52.7%), and 66 (51.2%) with the precontrast images to 88 (68.2%), 69 (53.5%), and 76 (58.9%) with the postcontrast images for readers 1, 2, and 3, respectively. Two of the three blinded readers showed a statistically significant difference in lesion detection between precontrast and postcontrast MR imaging (P <.001 and P =.008). A large number of additionally correctly detected and localized lesions were smaller than 1 cm. CONCLUSION: MR imaging with gadoxetic acid is safe and improves lesion detection and localization.     

Comparison of different magnetic resonance imaging sequences for assessment of fistula-in-ano

AIM: To assess agreement between different forms of T2 weighted imaging (T2WI), and post-contrast T1WI in the depiction of fistula tracts, inflammation, and internal openings with that of a reference test.METHODS: Thirty-nine consecutive prospective cases were enrolled. The following sequences were used for T2WI: 2D turbo-spin-echo (2D T2 TSE); 3D T2 TSE; short tau inversion recovery (STIR); 2D T2 TSE with fat saturation performed in all patients. T1WI were either a 3D T1-weighted prepared gradient echo sequence with fat saturation or a 2D T1 fat saturation [Spectral presaturation with inversion (SPIR)]. Agreement for each sequence for determination of fistula extension, internal openings, and the presence of active inflammation was assessed separately and blindly against a reference test comprised of follow-up, surgery, endoscopic ultrasound, and assessment by an independent experienced radiologist with access to all images.RESULTS: Fifty-six fistula tracts were found: 2 inter-sphincteric, 13 trans-sphincteric, and 24 with additional tracts. The best T2 weighted sequence for depiction of fistula tracts was 2D T2 TSE (Cohen’s kappa = 1.0), followed by 3D T2 TSE (0.88), T2 with fat saturation (0.54), and STIR (0.19). Internal openings were best seen on 2D T2 TSE (Cohen’s kappa = 0.88), followed by 3D T2 TSE (0.70), T2 with fat saturation (0.54), and STIR (0.31). Detection of inflammation showed Cohen’s kappa of 0.88 with 2D T2 TSE, 0.62 with 3D T2 TSE, 0.63 with STIR, and 0.54 with T2 with fat saturation. STIR, 3D T2 TSE, and T2 with fat saturation did not make any contributions compared to 2D T2 TSE. Post-contrast 3D T1 weighted prepared gradient echo sequence with fat saturation showed better agreement in the depiction of fistulae (Cohen’s kappa = 0.94), finding internal openings (Cohen’s kappa = 0.97), and evaluating inflammation (Cohen’s kappa = 0.94) compared to post-contrast 2D T1 fat saturation or SPIR where the corresponding figures were 0.71, 0.66, and 0.87, respectively. Comparing the best T1 and T2 sequences showed that, for best results, both sequences were necessary.CONCLUSION: 3D T1 weighted sequences were best for the depiction of internal openings and active inflammatory components, while 2D T2 TSE provided the best assessment of fistula extension.     

Characterization of hyperintense nodules on precontrast T1-weighted MRI: utility of gadoxetic acid-enhanced hepatocyte-phase imaging

Purpose:

To evaluate the utility of gadoxetic acid‐enhanced hepatocyte‐phase magnetic resonance imaging (MRI) in characterization of T1‐weighted hyperintense nodules within cirrhotic liver.

Materials and Methods:

This retrospective study was approved by our Institutional Review Board. Thirty‐four nodules hyperintense in unenhanced T1‐weighted MRI with histopathological confirmation from a collection of 19 patients were included. Tumor size, signal intensity on T1‐weighted, and T2‐weighted imaging as well as enhancement patterns on contrast‐enhanced dynamic/hepatocyte‐phase imaging were recorded. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of hepatocyte‐phase imaging.

Results:

Evaluation of the nodules with standard of reference revealed 15 dysplastic nodules (DN), seven well‐differentiated hepatocellular carcinomas (wHCC), and 12 moderately differentiated HCCs (mHCC). The mean size of dysplastic nodules was smaller than that of HCCs (P < 0.001). Using the HCC criteria (T2W or arterial enhancement followed with portal venous washout), 11/19 HCC were correctly characterized. Using solely hypointensity (compared to the surrounding liver parenchyma) during the hepatocyte phase as the criterion, 18/19 HCC were correctly characterized. There were seven additional HCCs diagnosed with hepatocyte‐phase imaging (P = 0.02).

Conclusion:

Gadoxetic acid‐enhanced MRI with hepatocyte‐phase imaging is superior to gadoxetic acid‐enhanced MRI with conventional criteria alone in characterization of T1W hyperintense nodules. J. Magn. Reson. Imaging 2011;33:625–632. © 2011 Wiley‐Liss, Inc.     

Microperfusion‐induced elevation of ADC is suppressed after contrast in breast carcinoma

Purpose

To investigate the effect of gadolinium (Gd)‐DTPA on the apparent diffusion coefficient (ADC) of breast carcinoma and to analyze the relationship between pre/postcontrast ADC and the degree of contrast enhancement.

Materials and Methods

Nineteen histopathologically confirmed breast carcinomas (mean size = 22 mm) were analyzed. Their ADCs before and after contrast administration were measured. The contrast‐to‐noise ratios (CNRs) of the tumors were measured on fat‐suppressed 3D T1‐weighted images in precontrast, early, and late postcontrast phases. These results were correlated with the measured ADC values.

Results

A significant decrease in the measured ADC was noted after contrast administration (?23%, P = 0.01). Lesions with relatively high ADC before contrast (>1.3 × 10^?3 mm²/sec; n = 12) demonstrated a larger degree of ADC reduction (mean 34%) than lesions with low ADC (≤1.3 × 10^?3 mm²/sec; n = 7) (mean 4.5%). When an early postcontrast image was used as a surrogate marker of malignant potential, we found a significant inverse correlation with postcontrast ADC (γ = ?0.57, P = 0.02).

Conclusion

Postcontrast ADC exhibited lower values than precontrast ADC, which is thought to reflect suppression of the microperfusion‐induced effect on diffusion‐weighted imaging. Postcontrast ADC may be a better indicator than precontrast ADC to reflect malignant potential of tumors. J. Magn. Reson. Imaging 2009;29:1080–1084. © 2009 Wiley‐Liss, Inc.

     

Evaluation of possible drug-drug interaction between gadoxetic acid and erythromycin as an inhibitor of organic anion transporting peptides (OATP)

Purpose

To evaluate if erythromycin compromises liver‐specific enhancement of gadoxetic acid; both compounds competing in organic anion transporting peptides (OATP) ‐mediated hepatocytic uptake.

Materials and Methods

The study was approved by institutional review board. Twelve healthy subjects (nine men, three woman; mean age, 38.7 years) were examined twice by MR imaging with prior administration of NaCl solution (placebo) or 1000 mg of erythromycin following a randomized sequence. Gadoxetic acid (0.025 mmol/kg body weight) was administered 15 min after the end of infusions. Pre‐ and 20 min postcontrast two‐dimensional gradient‐recalled‐echo sequences were acquired. Relative enhancements of liver parenchyma and ratio of means were calculated from signal intensity measurements. Plasma levels of gadoxetic acid and erythromycin were determined and given in geometric means and coefficients of variation (CV).

Results

Concentration of erythromycin directly after end of infusion was 13.9 mg/L (CV 14.9%). Gadolinium plasma concentrations 5 min after gadoxetic acid administration were 138.7 μmol/L (CV 20.4%) after erythromycin infusion and 129.6 μmol/L (CV 22.8%) after placebo. Mean relative enhancements of liver parenchyma were 88.1 (SD 24.9%) after erythromycin infusion and 92.6 (SD 17.9%) after placebo. Ratio of relative enhancements was 0.951 (95% confidence interval, 0.833; 1.061; statistically not significant).

Conclusion

Coadministration of erythromycin has no effect on gadoxetic acid enhanced liver MR imaging. J. Magn. Reson. Imaging 2011;33:409–416. © 2011 Wiley‐Liss, Inc.     

T2-weighted and diffusion-weighted MRI for discriminating benign from malignant focal liver lesions: diagnostic abilities of single versus combined interpretations

Purpose:

To compare the diagnostic accuracies of diffusion‐weighted imaging (DWI), T2‐weighted imaging (T2WI), and the combination of both sequences in discriminating benign from malignant focal liver lesions (FLLs).

Materials and Methods:

In all, 166 patients with 269 FLLs (153 benign and 116 malignant) were retrospectively evaluated. Two abdominal readers visually assessed the DWI, T2WI, and the combined (DWI+T2WI) image sets in an independent and blinded manner. The diagnostic abilities of each image set in discriminating the benign from the malignant FLLs set were compared using a binary logistic regression model. Pathologic results, consensus reading, and follow‐up imaging were used as the reference standard.

Results:

The overall characterization accuracy in all lesions of the combined set (80.3%) was significantly higher than those of the T2WI set (68.8%) and DWI set (73.2%) (combined vs. T2WI, P < 0.001; combined vs. DWI, P = 0.001), while there was no significant difference between the T2WI and DWI sets (P = 0.058). All image sets were more accurate in the characterization of malignant FLLs than of benign FLLs (P < 0.001).

Conclusion:

T2WI and DWI are complementary in discriminating benign from malignant FLLs; their combination improves diagnostic confidence. J. Magn. Reson. Imaging 2012;35:1388–1396. © 2012 Wiley Periodicals Inc.     

Characterization of hepatic adenoma and focal nodular hyperplasia with gadoxetic acid

Purpose:

To characterize imaging features of histologically proven hepatic adenoma (HA) as well as histologically and/or radiologically proven focal nodular hyperplasia (FNH) using delayed hepatobiliary MR imaging with 0.05 mmol/kg gadoxetic acid.

Materials and Methods:

Five patients with six HAs with histological correlation were retrospectively identified on liver MRI studies performed with gadoxetic acid, and T1‐weighted imaging acquired during the delayed hepatobiliary phase. Additionally, 23 patients with 34 radiologically diagnosed FNH lesions (interpreted without consideration of delayed imaging) were identified, two of which also had histological confirmation. Signal intensity ratios relative to adjacent liver were measured on selected imaging sequences.

Results:

All six hepatic adenomas (100%), which had histological confirmation, demonstrated hypointensity relative to adjacent liver on delayed imaging. Furthermore, all of the FNH (including 34 radiologically proven, 2 of which were also histologically proven) were either hyperintense (23/34, 68%) or isointense (11/34, 32%) relative to the adjacent liver on delayed imaging. None of the FNHs were hypointense relative to liver.

Conclusion:

Distinct imaging characteristics of HA versus FNH on delayed gadoxetic acid‐enhanced MRI, with adenomas being hypointense and FNH being iso‐ or hyperintense on delayed imaging may improve specificity for characterization, and aid in the differentiation of these two lesions. J. Magn. Reson. Imaging 2012;36:686–696. © 2012 Wiley Periodicals, Inc.     

Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI

Purpose:

To examine the differential features of combined hepatocellular and cholangiocarcinoma (HCC‐CC) from mass‐forming intrahepatic cholangiocarcinoma (ICC) on gadoxetic acid‐enhanced MRI.

Materials and Methods:

Forty patients with pathologically proven combined HCC‐CC (n = 20) and ICCs (n = 20) who had undergone gadoxetic acid‐enhanced MRI were enrolled in this study. MR images were analyzed for the shape of lesions, hypo‐ or hyperintense areas on the T2‐weighted image (T2WI), rim enhancement during early dynamic phases, and central enhancement with hypointense rim (target appearance) on the 10‐min and 20‐min hepatobiliary phase (HBP). The significance of these findings was determined by the χ² test.

Results:

Irregular shape and strong rim enhancement during early dynamic phases, and absence of target appearance on HBP favored combined HCC‐CCs (P < 0.05). Lobulated shape, weak peripheral rim enhancement, and the presence of complete target appearance on the 10‐min and 20‐min HBP favored ICCs (P < 0.05). However, 10 CC‐predominant type of combined HCC‐CC showed complete or partial target appearance on 10‐min HBP.

Conclusion:

The shape of tumors, degree of rim enhancement during early dynamic phases, and target appearance on HBP were valuable for differentiating between combined HCC‐CC and mass‐forming ICC on gadoxetic acid‐enhanced MRI. J. Magn. Reson. Imaging 2012;36:881–889. © 2012 Wiley Periodicals, Inc.