Effect of Gd-EOB-DTPA on hepatic fat quantification using high-speed T2-corrected multi-echo acquisition in H MR spectroscopy

Purpose

To determine whether gadolinium ethoxybenzyldiethylenetriaminepentaacetic acid (Gd-EOB-DTPA) administration affects hepatic fat quantification by magnetic resonance spectroscopy (MRS) using the fast breath-hold high-speed T2-corrected multiecho (HISTO) technique.

Materials and Methods

Seventy-six patients underwent Gd-EOB-DTPA-enhanced liver MR and 15 sec breath-hold HISTO MRS (4 times), twice before and twice after Gd-EOB-DTPA administration. Two consecutive MRSs were performed immediately before the dynamic study. Post-contrast MRS was performed twice continuously, approximately 15 min after contrast injection, prior to obtaining 20-min hepatobiliary phase images. We used paired t-test and intraclass correlation coefficient (ICC) to evaluate the variability of the mean fat fraction (FF) on pre-contrast MRS and post-contrast MRS and the effect of the contrast agent on the mean FF.

Results

The mean FFs were not significantly different between pre-contrast MRS and post-contrast MRS (6.50% ± 6.54 versus 6.70% ± 6.61, P = 0.15). The ICC of FF calculation between pre- and post-contrast MRS was 0.984. The ICCs for the FF magnitude between pre- and post-contrast MRS were 0.452, 0.771, and 0.995 for FF < 5%, FF 5–10%, and FF ≥ 10%, respectively.

Conclusion

Gd-EOB-DTPA does not appear to influence hepatic fat quantification, especially for patients with hepatic steatosis.     

Quantitative liver iron measurement by magnetic resonance imaging: in vitro and in vivo assessment of the liver to muscle signal intensity and the R2* methods

Purpose

To evaluate the liver-to-muscle signal intensity and R2* methods to gain a transferable, clinical application for liver iron measurement.

Materials and Methods

Sixteen liver phantoms and 33 human subjects were examined using three 1.5-T MRI scanners from two different vendors. Phantom-to-muscle and liver-to-muscle signal intensity ratios were analyzed to determine MRI estimated phantom and hepatic iron concentration (M-PIC and M-HIC, respectively). R2* was calculated for the phantoms and the liver of human subjects. Seven patients' biochemical hepatic iron concentration was obtained.

Results

M-PIC and R2* results of three scanners correlated linearly to phantom iron concentrations (r=0.984 to 0.989 and r=0.972 to 0.981, respectively), and no significant difference between the scanners was found (P=.482 and P=.846, respectively) in vitro. The patients' R2* correlated linearly to M-HIC of the standard scanner (r=0.981). M-HIC values did not differ from those obtained from the biopsy specimens (P=.230). The difference in M-HIC was significant, but the difference in R2* was not significant between the scanners (P<.0001 and P=.505, respectively) in vivo.

Conclusion

Both methods, M-HIC and R2*, are reliable iron concentration indicators with linear dependence on iron concentration in vivo and in vitro. The R2* method was found to be comparable among different scanners. Transferability testing is needed for the use of the methods at various scanners.     

MRI findings in nonalcoholic steatohepatitis: correlation with histopathology and clinical staging

Purpose

To evaluate magnetic resonance imaging (MRI) findings of nonalcoholic steatohepatitis (NASH) and to determine the correlation of MRI findings with histopathology and Mayo End-Stage Liver Disease (MELD) score.

Materials and Methods

Thirty patients (18 males, 12 females; mean age: 57±8.9 years; age range: 35–71 years) with histopathologically proven NASH who underwent MRI examinations between January 2001 and October 2005 were included in the study. Two radiologists retrospectively reviewed all magnetic resonance (MR) examinations in consensus to evaluate the presence and extent of predetermined findings of NASH including liver steatosis, early patchy liver enhancement indicating inflammation and liver fibrosis. The findings detected on MRI were correlated and compared to histopathological findings and MELD score by using nonparametric Spearman correlation coefficient and Kruskal–Wallis analysis of variance.

Results

Liver steatosis was observed in 10 of 30 patients; early patchy liver enhancement, in 8 of 30 patients and liver fibrosis in 19 of 30 patients on MR images. Liver fibrosis was reticular in all these patients. There were statistically significant moderate correlations between MRI findings of liver steatosis and histopathologic grades of steatosis (r=0.43; P<.05), and between MRI findings of fibrosis and histopathologic stages of fibrosis (r=0.61; P<.001). Early patchy enhancement did not demonstrate statistically significant correlation with inflammation (P=.28). There was no statistically significant overall correlation between MRI findings of NASH and MELD score.

Conclusion

MRI findings of liver steatosis and fibrosis in NASH showed moderate correlations with histopathologic grades of steatosis and stages of fibrosis, but MRI findings of NASH did not demonstrate any significant correlations with MELD score.     

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.     

Hepatic sarcoidosis: MR appearances in patients with chronic liver disease

Purpose

To describe the MR appearances of hepatic sarcoidosis in patients with chronic liver disease and correlate the results with clinical stage of disease as measured with the Mayo end-stage liver disease (MELD) score.

Materials and methods

Twenty patients with chronic liver disease and histopathological diagnosis of hepatic sarcoidosis who underwent MR imaging were included in this study. Two abdominal radiologists retrospectively reviewed all images for the presence of cirrhosis, imaging pattern of the liver, intrahepatic biliary dilatation, presence of areas of parenchymal atrophy, presence of splenic nodules and lymphadenopathy. Imaging findings were correlated with the MELD score.

Results

Of the patients, 14/20 had imaging findings of cirrhosis, 9/20 had a large macronodular pattern of liver cirrhosis and 5/20 had a diffuse pattern of liver cirrhosis. Peripheral wedge-shaped areas of parenchymal atrophy were observed in 10 patients. The combination of a central macronodular pattern and peripheral atrophy was observed in 9/20 patients. The pattern of cirrhosis had statistically significant correlation with the presence of wedge-shaped areas of parenchymal atrophy (p < 0.005). No statistically significant difference was revealed between the clinical score of patients who had imaging findings consistent with cirrhosis and those who did not.

Conclusion

MR imaging appearances of chronic sarcoid liver disease are diverse and do not appear to correlate with severity of clinical disease. Large central regenerative nodules and wedge-shaped areas of peripheral parenchymal atrophy are frequent findings and may help to suggest the diagnosis.     

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.     

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.     

Impact of diffusion-weighted MR imaging on the characterization of small hepatocellular carcinoma in the cirrhotic liver

Purpose

The purpose of this study was to determine whether or not adding diffusion-weighted magnetic resonance imaging (DWI) to conventional magnetic resonance (MR) imaging sequences improves the characterization of small hepatocellular carcinoma (HCC) (≤2 cm) in the setting of cirrhotic liver compared to conventional sequences alone.

Materials and Methods

A total of 62 cirrhotic liver patients with 82 nodules smaller than 2 cm in diameter were enrolled, and all lesions were pathologically confirmed. For the first reading session, which included precontrast T1- and T2-weighted images and T1 dynamic contrast-enhanced images, preindicated lesions by a study coordinator were characterized by two radiologists. They determined the confidence levels in consensus for the presence of small HCC into four grades. In another session, respiratory-triggered diffusion-weighted MR images (b factor=50, 400 and 800 s/mm²) were added to the previously reviewed images, and the same two radiologists again determined the confidence levels. The diagnostic performance of the combined DWI–conventional sequences set and the conventional sequences alone set was evaluated using receiver operating characteristic curves. Sensitivity and specificity values for characterizing small HCCs were also calculated.

Results

The area under the receiver operating characteristic curve for the second interpretation session (0.86) was significantly higher (P=.038) than that of the first session (0.76). The sensitivity was significantly increased from 75.7% to 87.8% by adding DWI to the conventional sequences (P=.015). No significant differences were observed for specificity values.

Conclusion

Adding DWI to conventional imaging modalities improves the diagnosis of small HCCs in the cirrhotic liver in terms of diagnostic performance and sensitivity by increasing reader confidence.     

White matter hyperintensities and dynamics of postural control

Background

White matter hyperintensities (WMHs) on MRI have been associated with age, cardiovascular risk factors and falls in the elderly. This study evaluated the relationship between WMHs and dynamics of postural control in older adults without history of falls.

Methods

We studied 76 community-living subjects without history of falls (age 64.5±7.3 years). Brain and WMH volume calculations and clinical rating were done on fluid-attenuation inversion recovery (FLAIR) and MP-RAGE MR images on 3 T. Balance was assessed from the center of pressure displacement using the force platform during 3 min of quiet standing using traditional and dynamic measures (using stabilogram-diffusion analysis). Gait speed was measured from 12-min walk.

Results

Age-adjusted periventricular and focal WMHs were associated with changes in certain dynamic balance measures, including reduced range of postural sway in anteroposterior direction (fronto-temporal WMHs, P=.045; parieto-occipital WMHs, P=.009) and more irregular long-term mediolateral fluctuations (P=.046). Normal walking speed was not affected by WMHs.

Conclusions

Periventricular and focal WMHs affect long-term dynamics of postural control, which requires engagement of feedback mechanisms, and may contribute to mobility decline in the elderly.     

Early contrast enhancement of the liver: exact description of subphases using MRI

Purpose

The purpose of this study was to describe the subphases of early post-contrast enhancement of the liver, using vessel enhancement patterns, and correlate these findings with enhancement patterns of abdominal organs.

Materials and Methods

A total of 114 patients who underwent gadolinium-enhanced abdominal magnetic resonance imaging examinations constituted the final study group, of which 56 were women (age range, 3–94 years; mean, 50 years) and 58 were men (age range, 6–85 years; mean, 54 years). Early post-contrast sequences in all patients were evaluated retrospectively by two reviewers for the determination of the presence of contrast enhancement in predetermined major vessels of the abdomen and qualitative and quantitative extent of enhancement of the renal cortex, spleen, pancreas and liver. Based on the overall findings, subphases of early contrast enhancement of the liver were described and quantitative extent of enhancement of organs was correlated with subphases of early contrast enhancement of the liver. Mann–Whitney U test and one-way unbalanced analysis of variance tests were used for the comparisons.

Results

Early hepatic arterial phase was observed in 14/114 patients, mid-hepatic arterial phase in 23/114 patients, late hepatic arterial phase in 33/114 patients, splenic vein only hepatic arterial dominant phase in 20/114 patients and hepatic arterial dominant phase in 24/114 patients. There was an overall association between the subphases of enhancement and the quantitative extent of enhancement for all studied organs (P<.0001).

Conclusion

The evaluation of vessel and organ enhancement patterns has allowed the characterization of five different subphases in early post-contrast enhancement of the liver. The quantitative extent of enhancement of abdominal organs also demonstrated significant correlation with these five subphases.     

Focal nodular hyperplasia of the liver: diffusion and perfusion MRI characteristics

Purpose

To present diffusion and perfusion magnetic resonance imaging (MRI) characteristics of focal nodular hyperplasia (FNH) of the liver.

Materials and Methods

Thirty-five patients with 52 FNHs (21 were pathologically-confirmed) underwent MRI at 1.5-T device. MR diffusion [diffusion-weighted imaging (DWI)] was performed using a free-breathing single-shot, spin-echo, echo-planar sequence with b gradient factor value of 500 s/mm². MR perfusion [perfusion-weighted imaging (PWI)] consisted of a 3D free-breathing LAVA sequence repeated up to 5 minutes after injection of 7 mL Gd-BOPTA (MultiHance, Bracco, Italy) and 20 mL saline flush at a flow rate of 4 mL/s. Apparent diffusion coefficient (ADC) and time-signal intensity curve (TSIC) were obtained for both normal liver and each FNH by two reviewers in conference; maximum enhancement (ME) percentage, time to peak enhancement (TTP), and maximal slope (MS) were also calculated.

Results

On DWI mean ADC value was 1.624×10^− 3 mm²/s for normal liver and 1.629×10^− 3 mm²/s for FNH. ADC value for each FNH and the normal liver was not statistically different (P= .936). On PWI, TSIC-Type 1 (quick and marked enhancement and quick decay followed by slowly decaying) was observed in all 52 FNHs, and TSIC-Type 2 (fast enhancement followed by slowly decaying plateau) in all normal livers. The mean ME, TTP and MS values were significantly different for FNH and normal liver (P= .005).

Conclusion

FNHs of the liver showed typical diffusion and perfusion MRI characteristics in all cases. On the ADC map, we could get similar value between the FNHs and the background parenchyma. On the perfusion imaging, FNHs showed a different pattern distinguished from the background liver.     

Imaging features of small (≤ 3 cm) pancreatic solid tumors on gadoxetic-acid-enhanced MR imaging and diffusion-weighted imaging: an initial experience

Objective

The objective was to determine imaging features that distinguish small (≤3cm) solid pancreatic adenocarcinoma, neuroendocrine tumor (NET) and solid pseudopapillary tumor (SPT) on gadoxetic-acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighed imaging (DWI).

Materials and methods

Twenty-four adenocarcinomas, 10 NETs and 8 SPTs were retrospectively included. Two radiologists analyzed morphologic features, signal intensity of the tumors on MR images including DWI (b=800) and dynamic enhancement pattern with consensus. Tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed.

Results

All adenocarcinomas had an ill-defined margin and irregular shape, and more frequently had pancreatic duct dilatation compared with other tumors (P<.05). All SPTs and all but one of the adenocarcinomas (95.8%) had no arterial enhancement with progressively increased enhancement, whereas seven NETs (70%) had arterial enhancement with progressively decreased enhancement (P<.01). The mean value of tumor-to-parenchyma ratio on arterial and portal phases was significantly higher for NETs, and the mean value of tumor ADCs was significantly lower for SPTs than for other tumors (P<.05).

Conclusions

Gadoxetic-acid-enhanced MRI may aid in differentiation between small adenocarcinomas, NETs and SPTs based on morphologic features with dynamic enhancement pattern in adenocarcinomas, dynamic enhancement pattern with tumor-to-parenchyma ration on arterial and portal phases in NETs, and dynamic enhancement pattern with lower ADC value in SPTs.     

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MR finding of radiation-induced hepatic injury: Relationship to absorbed dose and time course after irradiation

Purpose

To evaluate if Gd-EOB-DTPA-enhanced MRI could identify liver tissue damage caused by radiation exposure in patients undergoing external beam radiation therapy.

Materials and methods

We enrolled 11 patients who underwent Gd-EOB-DTPA-enhanced MRI during or after radiotherapy in which the radiation field included the liver. External beam radiotherapy was delivered through multiple fields using a 10-MV linear accelerator. The hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI were qualitatively evaluated for the presence of a decreased uptake of Gd-EOB-DTPA in the irradiated area in the liver. Next, signal intensity (SI) ratio of the irradiated area to the non-irradiated liver parenchyma was also calculated. The absorbed dose of the irradiated area in the liver was standardized using equivalent dose in 2 Gy fraction (EQD2) and biological effective dose (BED). The results of qualitative analysis were compared with EQD2 or BED, and linear regression analysis was performed between EQD2 or BED and SI ratio.

Results

Twenty-two irradiated areas were evaluated. Qualitative analysis revealed a decreased uptake of Gd-EOB-DTPA in 14 areas and no decreased uptake of Gd-EOB-DTPA in eight areas. The thresholds of EQD2 and BED causing a decreased uptake of Gd-EOB-DTPA were considered to be 24 to 29 Gy and 29 to 35 Gy, respectively. Quantitatively, SI ratio decreased as EQD2 or BED increased (r = 0.89, p < 0.001), and the inverse relationship between signal enhancement and the absorbed dose in the irradiated area was obtained. One area with EQD2 of 50 Gy and BED of 60Gy showed a slightly decreased uptake of Gd-EOB-DTPA on the 40th day but a clearly decreased uptake of Gd-EOB-DTPA on the 123rd day from initiation of radiotherapy.

Conclusions

Gd-EOB-DTPA-enhanced MRI described RLI as a decreased uptake of Gd-EOB-DTPA matching the irradiated area. The occurrence of this finding was significantly correlated with the absorbed dose of the irradiated area in the liver.     

Monitoring the brain metabolites of children with acute encephalopathy caused by the H1N1 virus responsible for the 2009 influenza pandemic: a quantitative in vivo H MR spectroscopy study

Background and Purpose

Influenza viral infection, which results in central nervous system dysfunction, is a major cause of acute encephalopathy (AE). The purpose of this study was to investigate the changes in the concentrations of brain metabolites in children with AE using single-voxel magnetic resonance spectroscopy (MRS) and to provide diagnostic information about the relationship between the symptoms of AE and metabolite concentrations.

Materials and Methods

The subjects were 10 children (mean age: 6.2 years; range: 1–13) with AE caused by the novel influenza A virus responsible for the 2009 influenza pandemic. The serial MRS data (TE/TR=30/5000 ms, 3 T) acquired from the basal ganglia (BG) and centrum semiovale (CS) of each patient were categorized into three periods: (1) initial neurological symptom presentation and the start of treatment (n= 10), (2) short-term follow-up (n= 9) and (3) long-term follow-up (n= 3). As controls, the magnetic resonance (MR) spectra of eight age-matched children were also investigated.

Results

In both regions, the concentrations of the major metabolites (N-acetylaspartate, creatine, choline, myo-inositol, glutamate/glutamine complex and glutamate) only showed minor fluctuations between the three periods. On the other hand, higher levels of taurine (Tau) were observed in the BG during the second period (P=.005), and increased levels of glucose were observed in the CS during the first (P=.005) and second (P=.036) periods.

Conclusions

Serial monitoring of brain metabolite changes was carried out with a clinical MR system. The concentrations of major metabolites only displayed very minor fluctuations in response to mild H1N1-related AE. However, a higher Tau concentration was found to be associated with neurological symptoms. Further studies are required to improve our understanding of the detailed activity of Tau in AE.     

The use of T2*-weighted multi-echo GRE imaging as a novel method to diagnose hepatocellular carcinoma compared with gadolinium-enhanced MRI: a feasibility study

Background

The goal of the study was to assess a T2*-weighted MRI sequence for the ability to identify hepatocellular carcinoma (HCC).

Methods

Hepatic iron deposition, which is common in chronic liver disease (CLD), may increase the conspicuity of HCC on GRE imaging due to increased T2* signal decay in liver parenchyma. In this study, a breath-hold T2*-weighted MRI sequence was evaluated by a blinded observer for HCC and the results compared to a reference standard of gadolinium-enhanced MRI in these same patients. Forty-one patients (mean age 56.2 years; 17 females) were included in this approved, retrospective study.

Results

By the reference standard, 14 of 41 patients had a total of 25 HCCs. The sensitivity of the T2*-weighted MR sequence for identifying HCC, per lesion, was 60%, while the specificity was 100%. There was a significantly lower T2* value of liver parenchyma in patients with HCC identified by the T2*-weighted sequence than in those with HCCs which were not identified by the T2*-weighted sequence (27.8±2.2 vs. 21.9±2.1 ms; P=.02).

Conclusions

A T2*-weighted MRI sequence can identify HCC in patients with CLD. This technique may be beneficial for imaging of patients contraindicated for gadolinium.     

Paradoxical uptake of Gd-EOB-DTPA on the hepatobiliary phase in the evaluation of hepatic metastasis from breast cancer: is the “target sign” a common finding?

Purpose

The purpose was to describe magnetic resonance imaging (MRI) findings of breast cancer liver metastasis using gadoxetic acid (Gd-EOB-DTPA) with an emphasis on the added value of the hepatobiliary phase (HBP).

Material and methods

Nine patients with 13 liver metastases were included in the study after the medical records of 29 breast cancer patients who underwent Gd-EOB-DTPA-enhanced MRI between February 2008 and June 2010 were reviewed. The diagnoses of liver metastasis were established by percutaneous liver biopsy or surgery and on the basis of image findings. Two radiologists retrospectively evaluated signal intensity (SI) and sizes of metastases and patterns of enhancement in an HBP. The SI ratio was calculated as the SI of the central hyperintense portion in “target” lesions divided by the SI of nearby normal liver parenchyma on the HBP. We also measured apparent diffusion coefficient (ADC) values from Diffusion Weighted Image (DWI).

Results

Liver metastases were all hypointense [n=13/13 (100%)] on T1-weighted imaging (WI), and many lesions had a “target” appearance with a central high SI and a peripheral low SI rim (47%) on T2WI. Dynamic study showed rim enhancement on the arterial phase (85%) and a “target” appearance, consisting of a central enhancing portion with peripheral washout or hypointense rim, on the HBP (62%). The mean SI ratio was 0.7. The mean ADC value of “target” appearing metastases was 1.25 (×10⁻³ mm²/s; range 1.3–1.6) compared with a mean value of 0.8 (×10⁻³ mm²/s; range 0.8–1.4) in homogeneous defect on the HBP. There was statistically significant difference (P<.05).

Conclusion

Breast cancer liver metastases commonly demonstrated as a peripheral ring enhancement on arterial dominant phase and a target sign with a central round enhancing portion and a peripheral hypointense rim on the HBP.     

Three-dimensional susceptibility-weighted imaging at 3 T using various image analysis methods in the estimation of grading intracranial gliomas

Object

Although three-dimensional (3D), high-spatial resolution susceptibility-weighted imaging (SWI) appears to be valuable in the evaluation of central nervous system gliomas, several evaluation methods are proposed in the literature. The purpose of this study was to evaluate the use of 3D SWI for grading intracranial gliomas with various analysis methods.

Materials and Methods

Twenty-three patients suspected of having gliomas participated in this study. SWI was performed in addition to conventional MR sequences. In 15 cases, post-gadolinium enhanced SWI was also obtained. Imaging evaluation criteria were conventional grade, hypointensity ratio in the tumor-dominant structure of hypointensity on SWI (hemorrhage or vascular structure) and presence of abnormal enhancement surrounding the tumor.

Results

Mean grading scores of conventional grade showed no statistically significant difference among WHO grades. Mean grading scores of hypointensity ratios in the tumor were higher for WHO Grades 3 and 4 than for lower grade tumors (P=.05, Mann–Whitney U test). Hemorrhagic foci were more frequently seen in the higher grade tumor. Post-contrast susceptibility-weighted images of five of 11 WHO Grade 3 and 4 cases showed bright enhancement surrounding the tumor, suggesting a breakdown of the blood–brain barrier.

Conclusions

SWI at 3 T may be a useful method to analyze the structural characteristics of gliomas and to evaluate pathology in vivo. Assessment of hypointensity ratios in the glioma was the most preferable method in grading glioma. However, more studies, specifically concerning a suitable method for image analysis, are needed to establish SWI at 3 T as a useful tool in clinical routine.     

Hepatic parenchymal enhancement at Gd-EOB-DTPA-enhanced MR imaging: correlation with morphological grading of severity in cirrhosis and chronic hepatitis

The aim was to clarify whether enhancement effects of the liver parenchyma in the hepatobiliary phase (HP) of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MR imaging were correlated with the morphological grading of the severity in cirrhosis. A total of 62 patients with chronic hepatitis or cirrhosis underwent Gd-EOB-DTPA-enhanced MR imaging. Relative enhancement (RE) of liver parenchyma was calculated from signal intensity (SI) measurements obtained at precontrast images (SIpre) and 20-min postcontrast HP images (SIpost) as: (SIpost-SIpre)/SIpre. Morphological MR grades of severity in cirrhosis were divided into four groups. Then, RE of liver parenchyma and morphologic MR grading were correlated. Regarding the morphologic severity of cirrhosis, the numbers of patients with MR grade 1, 2, 3 and 4 were 14 (23%), 7 (11%), 28 (45%) and 13 (21%), respectively. The mean REs of liver parenchyma in each group of MR morphologic grade 1, 2, 3 and 4 were 0.71±0.21, 0.62±0.16, 0.70±0.22 and 0.77±0.18, respectively. There was no significant correlation between the MR grading of morphologic severity and the RE of liver parenchyma at 20-min HP. Hepatic parenchymal enhancement in the HP of Gd-EOB-DTPA-enhanced MR imaging did not necessarily decrease according to the severity of morphologic changes in cirrhosis. This fact may suggest that the hepatic uptake of Gd-EOB-DTPA depends on the preserved hepatocytes function rather than the severity of morphologic changes in cirrhosis.     

Diffusion-weighted magnetic resonance imaging in differentiation of postobstructive consolidation from central lung carcinoma

Purpose

To prospectively evaluate diffusion-weighted (DW) magnetic resonance (MR) imaging for differentiation of postobstructive consolidation from centrally located lung carcinomas by using apparent diffusion coefficients (ADCs).

Materials and Methods

An institutional review board approved this study; informed consent was obtained from patients. Forty-nine consecutive patients (3 women, 46 men; mean age, 63.6 years; age range, 42–85 years) with lung carcinoma underwent DW MR imaging. Forty patients had central and nine patients had peripheral lung carcinomas. ADC of each lung carcinoma was calculated from DW MR images obtained with two different b values (0, 1000 s/mm²).In the final study group including 27 patients with central lung carcinoma accompanying distal lung consolidation (mean age, 67.2 years; 3 women, 24 men), ADCs of lung carcinomas were statistically compared among cytologic/histologic types and accompanying postobstructive consolidations. Unpaired t test was used for measurable variables with normal distribution, and Kruskal–Wallis variance analysis and Mann–Whitney U tests were used for the measurable variables without normal distribution.

Results

There was no significant difference between mean ADC values of all types of carcinomas (P=.302) and also between mean ADC values of central (1.91 ± 0.7×10⁻³ mm²/s) and peripheral carcinomas (1.58 ± 0. 6×10⁻³ mm²/s) (P=.224). The mean ADC value for the masses of central lung carcinoma with postobstructive consolidations was 1.83 ± 0.75×10⁻³ mm²/s, and for consolidation was 2.50 ± 0.76×10⁻³ mm²/s. ADC of central carcinoma masses was significantly lower than that of postobstructive consolidations (P=.003).

Conclusions

ADC values of central lung carcinoma masses appear to be lower than accompanying postobstructive consolidations. ADC values could be considered useful as a differentiating parameter among central lung carcinomas and accompanying postobstructive consolidations.