Diffusion and perfusion MRI prediction of progression-free survival in patients with hepatocellular carcinoma treated with concurrent chemoradiotherapy.

PURPOSE: To assess whether MR perfusion and diffusion parameters taken before concurrent chemoradiotherapy (CCRT) are useful imaging biomarkers for predicting progression-free survival (PFS) in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty patients with locally advanced HCC who had no treatment before CCRT underwent dynamic contrast-enhanced (DCE) and diffusion-weighted MRI. Mean values of the volume transfer constant (K(trans) ), reflex constant (Kep ), extravascular extracellular volume fraction (Ve ) and the apparent diffusion coefficient (ADC) were estimated on a region of interest. The best cutoff value for each factor was assessed to differentiate between patients who had PFS shorter or longer than the median PFS. Patients were dichotomized in terms of the cutoff value. The survival outcome of the two groups and the predictive ability of each factor on PFS were evaluated. RESULTS: Median time to PFS was 179 days. The best cutoff values for ADC, K(trans) , Kep , and Ve was 1.008 × 10(-3) mm(2) s(-1) , 0.108 min(-1) , 0.570 min(-1) , and 0.298%. Patients with higher ADC had significantly longer PFS than those with lower ADC(P < 0.0001). CONCLUSION: The ADC of HCC acquired before CCRT correlated with PFS and was valuable in the prediction of the clinical outcome of HCC treated with CCRT.

Dynamic enhancement pattern of HCC smaller than 3 cm in diameter on gadoxetic acid-enhanced MRI: comparison with multiphasic MDCT.

BACKGROUND & AIMS: The dynamic enhancement pattern of HCCs smaller than 3 cm in diameter on gadoxetic acid-enhanced magnetic resonance imaging (MRI) have not been extensively investigated. We aimed to evaluate the dynamic enhancement patterns of small HCCs (≤3 cm) on gadoxetic acid-enhanced magnetic resonance imaging (MRI) and compare enhancement patterns with multiphasic multidetector computed tomography (MDCT) based on tumour cellular differentiation and size. METHODS: We retrospectively included 55 patients with 67 surgically confirmed small HCCs (≤3 cm) who underwent multiphasic MDCT and gadoxetic acid-enhanced MRI. Dynamic enhancement patterns were analysed according to tumour cellular differentiation and size. Hepatobiliary phase images were also analysed to assess their additional value. RESULTS: The proportion of small HCCs demonstrating the typical enhancement pattern differed depending on tumour cellular differentiation on both MRI (P = 0.001) and MDCT (P = 0.001), but differed depending on tumour size only on CT (P = 0.008). Gadoxetic acid-enhanced MRI more sensitively depicted the typical enhancement pattern than CT for all tumours (P = 0.001), for moderately or poorly differentiated HCCs (P = 0.021) and for HCCs ≤2 cm (P = 0.001). 80% of tumours with atypical enhancement could be diagnosed as HCC based on tumour size and hepatobiliary phase images. CONCLUSIONS: On both gadoxetic acid-enhanced MRI and multiphasic CT, the dynamic enhancement patterns of small HCCs (≤3 cm) differed according to tumour cellular differentiation. Gadoxetic acid-enhanced MRI more frequently demonstrated the typical HCC enhancement pattern than CT in small HCCs.

Metal artifact reduction software used with abdominopelvic dual-energy CT of patients with metal hip prostheses: assessment of image quality and clinical feasibility.

OBJECTIVE: The objective of our study was to determine the feasibility of using Metal Artifact Reduction (MAR) software for abdominopelvic dual-energy CT in patients with metal hip prostheses. MATERIALS AND METHODS: This retrospective study included 33 patients (male-female ratio, 19:14; mean age, 63.7 years) who received total hip replacements and 20 patients who did not have metal prostheses as the control group. All of the patients underwent dual-energy CT. The quality of the images reconstructed using the MAR algorithm and of those reconstructed using the standard reconstruction was evaluated in terms of the visibility of the bladder wall, pelvic sidewall, rectal shelf, and bone-prosthesis interface and the overall diagnostic image quality with a 4-point scale. The mean and SD attenuation values in Hounsfield units were measured in the bladder, pelvic sidewall, and rectal shelf. For validation of the MAR interpolation algorithm, pelvis phantoms with small bladder "lesions" and metal hip prostheses were made, and images of the phantoms both with and without MAR reconstruction were evaluated. RESULTS: Image quality was significantly better with MAR reconstruction than without at all sites except the rectal shelf, where the image quality either had not changed or had worsened after MAR reconstruction. The mean attenuation value was changed after MAR reconstruction to its original expected value at the pelvic sidewall (p < 0.001) and inside the bladder (p < 0.001). The SD attenuation value was significantly decreased after MAR reconstruction at the pelvic sidewall (p = 0.019) but did not show significant differences at the bladder (p = 0.173) or rectal shelf (p = 0.478). In the phantom study, all lesions obscured by metal artifacts on the standard reconstruction images were visualized after MAR reconstruction; however, new artifacts had developed in other parts of the MAR reconstruction images. CONCLUSION: The use of MAR software with dual-energy CT decreases metal artifacts and increases diagnostic confidence in the assessment of the pelvic cavity but also introduces new artifacts that can obscure pelvic structures.

Detection of recurrent hepatocellular carcinoma on post-operative surveillance: comparison of MDCT and gadoxetic acid-enhanced MRI.

OBJECTIVE: To compare the accuracy of multidetector computed tomography (MDCT) and gadoxetic acid-enhanced magnetic resonance imaging (MRI) for the detection of intrahepatic tumor recurrence after curative resection of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-six patients who underwent MDCT and gadoxetic acid-enhanced MRI for postoperative surveillance after resection of HCC were retrospectively analyzed; 26 patients had a recurrence (36 lesions) and 30 patients did not. Recurrent HCCs were confirmed by histological examinations in two, typical dynamic imaging findings on CT and/or MRI in 28, and by demonstration of growth or tumor staining on angiography on six. Two reviewers graded the confidence for the presence of recurrence on CT and MRI, using a five-point scale. The jackknife free-response receiver operating characteristic method was used to compare diagnostic performance. The accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. RESULTS: For 36 recurrent lesions, the figure of merit was significantly higher for MRI than MDCT for detecting recurrence for both reviewers (p < 0.005 for both reviewers). In lesion-by-lesion analysis, the sensitivity was significantly higher on MRI (100% for reviewer 1 and 97% for reviewer 2) than on MDCT (44.4% and 66.6%) for both reviewers (p < 0.005 for both reviewers). Also in patient-by-patient analysis, sensitivity was significantly higher on MRI (100% and 96.1%) than on MDCT (57.6% and 76.9%) for both reviewers (p < 0.05 for both reviewers). CONCLUSION: Gadoxetic acid-enhanced MRI is superior to MDCT for detecting intrahepatic recurrence after curative resection of HCC.

Assessment of angiogenesis of hepatocellular carcinoma using dynamic contrast enhanced MR and histopathologic correlation in an experimental rat model.

BACKGROUND/AIMS: To assess the perfusion parameters and angiogenesis of HCC using dynamic contrast enhanced(DCE) MR and to correlate it with histopathologic findings in an experimental rat model. METHODOLOGY: Twenty rats were continuously infused with diethylnitrosamine (DEN) for tumor induction. After 32 to 36 weeks of DEN treatment, the rats underwent MRI of the liver with a 3-T MR imaging system. Perfusion parametric maps and perfusion parameters such as, time to peak (TTP) and peak enhancement (PE) were obtained by using a commercially available software package. The nodules were correlated precisely to DCE MR images. RESULTS: A total of 13 nodules were found in 12 rats; 5 dysplastic nodule (DN)s were identified in 5 rats and 8 HCCs (3 Edmonson grade I, 2 Edmonson grade I-II, 3 Edmonson grade II) were found in 7 rats. There were significant differences in mean values of PE and HPH (histogram peak height) of PE between DN and HCC. Mean value and HPH of PE showed statistically significant correlation with tumor grade. CONCLUSIONS: There were significant differences in perfusion parameters between DN and HCC. DCE MR imaging can be used in the differential diagnosis and management of liver disease in hepatocarcinogenesis.

Histological characteristics of small hepatocellular carcinomas showing atypical enhancement patterns on gadoxetic acid-enhanced MR imaging.

PURPOSE: To define the histological characteristics of hepatocellular carcinomas (HCCs) showing atypical dynamic enhancement patterns on gadoxetic acid-enhanced dynamic magnetic resonance imaging (EOB-MRI). MATERIALS AND METHODS: We evaluated a total of 130 small (≤ 3 cm) HCCs from 114 patients that were surgically removed after EOB-MRI. Two radiologists blinded to the histological findings retrospectively classified the HCCs into typical or atypical lesions. Gross morphology, nuclear histological grade, presence of vascular invasion, and capsule formation and infiltration were compared between the two groups using Chi-square or Fisher tests. RESULTS: Atypical dynamic enhancement patterns were seen in 23 HCCs (17.7%). None of the atypical HCC showed vascular invasion (P < 0.001). Atypical HCCs also showed more frequently smaller size (1.6 ± 0.6 cm versus 2.1 ± 0.6 cm, P = 0.001) with 86.9% (n = 20) of which 2 cm or less in diameter (P = 0.001), vaguely nodular appearance (56.5% vs 3.7%, P < 0.001), and nuclear grade I (69.6% versus 6.5%, P < 0.001), while less frequently showed capsule formation (26.1% versus 77.6%, P < 0.001) or capsular infiltration (16.7% versus 77.1%, P = 0.005). CONCLUSION: Atypical HCCs on EOB-MRI may be characterized by the absence of vascular invasion, smaller (< 2 cm or less) size, vaguely nodular appearance, and well differentiation, and infrequent capsule formation or capsular infiltration.

Comparison of breathhold, navigator-triggered, and free-breathing diffusion-weighted MRI for focal hepatic lesions.

PURPOSE: To compare the breathhold, navigator-triggered, and free-breathing techniques in diffusion-weighted magnetic resonance imaging (MRI) for the evaluation of focal liver lesions on a 3.0T system. MATERIALS AND METHODS: Fifty-two patients (36 men, 16 women; mean age, 56.4 years) with focal liver lesions underwent breathhold, navigator-triggered, and free-breathing diffusion-weighted imaging (DWI) of the liver on a 3.0 Tesla (T) system. All sequences were performed with b values of 50 and 800 s/mm(2) and identical parameters except for signal averages (two for navigator-triggered, one for breathhold, and four for free-breathing) and repetition time (3389 ms for navigator-triggered, 1500 ms for breathhold, and 4400 ms for free-breathing). A total of 74 lesions (50 malignant, 24 benign) were evaluated. The signal-to-noise ratios (SNR) of the liver and lesions, contrast-to-noise ratios (CNR) of each lesion, and ADC values of the liver and lesions were compared for each DWI sequence. The detection sensitivity and characterization accuracy were also compared. RESULTS: The SNRs of the liver and lesions were significantly lower for breathhold DWI than for non-breathhold DWI (navigator-triggered and free-breathing DWI) for all b values. The CNRs of the lesions were also significantly lower for breathhold DWI than for non-breathhold DWI. The ADC values of the liver and focal lesions measured using the three DWI techniques were not significantly different and showed good correlation. For lesion detection and characterization, there were no significant differences between breathhold and non-breathhold DWI. CONCLUSION: Both breathhold and non-breathhold DWI are comparable for the detection or characterization of focal liver lesions at 3.0T; however, non-breathhold DWI provides higher SNR and CNR than breathhold DWI. In addition, although free-breathing and navigator-triggered DWI sequences show similar performance for 3.0T liver imaging, free-breathing DWI is more time efficient than navigator-triggered DWI.

Added value of subtraction imaging in detecting arterial enhancement in small (<3 cm) hepatic nodules on dynamic contrast-enhanced MRI in patients at high risk of hepatocellular carcinoma.

OBJECTIVES: To determine the importance of arterial enhancement in diagnosing small (<3 cm) hepatocellular carcinomas (HCCs) and to evaluate the added value of dynamic subtraction magnetic resonance imaging (MRI) in detecting arterial enhancement in small (<3 cm) hepatic nodules in high-risk patients. METHODS: Eighty-six patients with 135 pathologically confirmed small (<3 cm) hepatic nodules (104 HCCs, 31 benign nodules) underwent MRI before curative surgery. Arterial enhancement was determined by three methods: (1) visual assessment of the arterial phase alone, (2) visual comparison of the arterial phase with the unenhanced phase and (3) additional review of subtraction images. The diagnostic performance of each method was calculated and compared using generalised estimating equations analysis. RESULTS: Arterial enhancement demonstrated high positive predictive value (PPV) (96.5-98.9 %) and specificity (90.3-96.8 %), but low negative predictive value (NPV) (54.6-62.5 %) and intermediate sensitivity (76-79.8 %) for diagnosing small HCCs. Diagnostic performance was highest for subtraction imaging. There were significant differences among the three methods in sensitivity (P = 0.04), accuracy (P = 0.044), PPV (P < 0.001) and NPV (P = 0.024), but not in specificity (P = 0.167). CONCLUSION: The accurate detection of arterial enhancement in small hepatic nodules is important for diagnosing HCC and may be enhanced by subtraction imaging.

Usefulness of the tensile gallbladder fundus sign in the diagnosis of early acute cholecystitis.

OBJECTIVE: The purpose of this article is to evaluate the usefulness of the tensile gallbladder fundus sign on CT in diagnosing early acute cholecystitis. MATERIALS AND METHODS: The tensile gallbladder fundus sign on CT is defined as the absence of gallbladder fundus flattening by the anterior abdominal wall due to increased gallbladder pressures. Between October 2010 and March 2012, 222 patients with confirmed diagnoses of acute cholecystitis by surgery or follow-up imaging studies underwent CT scans in the emergency department because of right upper quadrant pain. Two radiologists retrospectively reviewed all CT images to determine the presence of the tensile gallbladder fundus sign and other CT findings previously reported to be suggestive of acute cholecystitis. Diagnostic performances were calculated and analyzed using pairwise comparisons of receiver operating characteristic curves. The kappa statistic was calculated to evaluate the interobserver agreement. RESULTS: Using the diagnostic criteria in which acute cholecystitis is defined as the presence of three or more classic CT findings, the addition of the tensile gallbladder fundus sign increased the area under the receiver operating characteristic curve (Az) value from 0.693 to 0.739 (p = 0.003). In the subgroup of 91 patients with no other CT features suggestive of acute cholecystitis, the sensitivity, specificity, and Az value of the tensile gallbladder fundus sign for acute cholecystitis were 74.1%, 96.9%, and 0.855, respectively. Interobserver agreement was good with the tensile gallbladder fundus sign (κ = 0.721). CONCLUSION: The tensile gallbladder fundus sign may be useful for diagnosing acute cholecystitis, especially in the early stage when other CT findings are absent.

Gadoxetate disodium-enhanced MRI of mass-forming intrahepatic cholangiocarcinomas: imaging-histologic correlation.

OBJECTIVE: The purpose of this study was to describe the enhancement patterns of mass-forming intrahepatic cholangiocarcinomas on gadoxetate disodium-enhanced MR images using imaging-histologic correlation. MATERIALS AND METHODS: We retrospectively evaluated the preoperative gadoxetate disodium-enhanced MR images of 19 patients with mass-forming intrahepatic cholangiocarcinomas. Two readers independently interpreted enhancement patterns on arterial (globally high, rimlike), dynamic (washout, progressive), and hepatobiliary (target, nontarget) phase images. Dynamic enhancement was categorized as washout (hypoenhancement on later phase compared with arterial phase images) or progressive (persistent or gradually increased enhancement). Tumor enhancement ratio and tumor-to-liver signal difference curves were analyzed. The enhancement patterns were correlated with the extent of stromal fibrosis within the tumors. RESULTS: Rimlike arterial enhancement (89%, reader 1; 84%, reader 2) and a progressive dynamic pattern (89%, both readers) were predominant. Tumor enhancement ratio increased gradually from the arterial to the equilibrium phase then decreased in the hepatobiliary phase, but the tumor signal intensities were lower than liver signal intensity in all phases. The two lesions that both readers considered to have globally high arterial enhancement and a washout dynamic pattern presented with minimal or scattered stromal fibrosis. Target appearance in the hepatobiliary phase (reader 1, 42%; reader 2, 47%) was more commonly seen in tumors with central stromal fibrosis (reader 1, p = 0.025; reader 2, p = 0.001). CONCLUSION: Mass-forming intrahepatic cholangiocarcinomas may be characterized by rimlike enhancement and a progressive dynamic pattern on gadoxetate disodium-enhanced MR images, and these features seem related to the extent of stromal fibrosis in the tumor. Furthermore, mass-forming intrahepatic cholangiocarcinomas may have a pseudowashout pattern on gadoxetate disodium-enhanced MR images because of progressive background liver enhancement. Therefore, radiologists need to be aware of this pattern as a possible pitfall.

Preoperative prediction of the microvascular invasion of hepatocellular carcinoma with diffusion-weighted imaging.

The aim of this study was to investigate whether diffusion-weighted imaging (DWI) could be useful in predicting the microvascular invasion (MVI) of hepatocellular carcinoma (HCC). Sixty-seven surgically proven HCCs from 65 patients (54 men and 11 women with an age range of 35-75 years and a mean age of 56.0 years) were retrospectively analyzed. The signal intensities (SIs) of the lesions on preoperative diffusion-weighted (DW) images were visually categorized as isointense or hyperintense in comparison with the adjacent liver. We also quantitatively measured SIs and apparent diffusion coefficients (ADCs) by drawing regions of interest in HCCs and livers on DW images with b values of 50, 400, and 800 second/mm(2) and on ADC map images. Logistic regression analyses were performed so that we could identify independent predictors of MVI among laboratory and DWI findings. A univariate analysis showed that a histological grade of 3, a larger tumor size, a higher SI ratio on DW images, and a lower ADC value were significantly associated with MVI. A multiple logistic regression analysis showed that a histological grade of 3 and the ADC value were independent predictors of MVI. With a cutoff of 1.11 × 10(-3) mm(2)/second, the ADC value provided a sensitivity of 93.5% and a specificity of 72.2% for the prediction of MVI with an odds ratio of 24.5 (95% confidence interval = 4.14-144.8, P < 0.001). In conclusion, lower ADC values (1.11 × 10(-3) mm(2)/second or less) can be a useful predictor of MVI during the preoperative evaluation of HCC.

Quantitative evaluation of liver cirrhosis using T1 relaxation time with 3 tesla MRI before and after oxygen inhalation.

PURPOSE: To quantify liver T1 relaxation times before and after oxygen inhalation in patients with and without liver cirrhosis using a 3 Tesla (T) MRI. MATERIALS AND METHODS: Institutional Review Board approval and written informed consent were obtained. Ninety-two noncirrhotic patients and 87 patients with hepatitis B viral liver cirrhosis (72 Child-Pugh class A and 15 Child-Pugh class B or C) underwent MRI with a 3.0T system before and after the supply of 100% oxygen at a rate of 15 L/min by means of a nonrebreather ventilation mask for 3 min. T1 maps were acquired using three-dimensional spoiled gradient echo sequences with two different flip angles (2° and 14°) and a fixed TR/TE (2.54 ms/0.95 ms). Liver T1 values were obtained using a T1 processing tool (MapIT software). The mean baseline T1 values of three groups (control, Child-Pugh class A, and Child-Pugh class B/C) were compared using an analysis of variance test. Liver T1 value before and after oxygenation was compared using a paired t-test for each group. RESULTS: The baseline liver T1 value was significantly higher in the control group (941 ± 136 ms) than in Child-Pugh A (858 ± 143 ms) and Child-Pugh B/C (783 ± 164 ms) group (P < 0.001 and P < 0.0001). The reduction in the liver T1 value after oxygen inhalation was significant in the control group (P = 0.012) but not significant in Child-Pugh class A (P = 0.079) and Child-Pugh class B/C (P = 0.752). CONCLUSION: The baseline liver T1 relaxation time was significantly different between the patients with and without liver cirrhosis. The shortening effect of oxygen on the liver T1 value was significant in the control group but not in the cirrhotic patients.

Prediction of the histopathological grade of hepatocellular carcinoma using qualitative diffusion-weighted, dynamic, and hepatobiliary phase MRI.

OBJECTIVES: To investigate the effectiveness of qualitative diffusion-weighted imaging (DWI), subtraction of unenhanced from arterial phase images, and hepatobiliary phase (HBP) images in estimating the histopathological grade of hepatocellular carcinoma (HCC). METHODS: We retrospectively reviewed gadoxetic acid-enhanced magnetic resonance images of 175 patients with 201 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed for each sequence and a combination of sequences. RESULTS: There was a tendency towards higher grades in tumours showing restricted diffusion on DWI (P < 0.001) or arterial enhancement on subtraction imaging (P < 0.001), but not hepatocyte-defect on HBP images (P = 0.33). When lesions were divided into three groups based on combined findings on DWI and subtraction imaging, a linear trend was observed between group and grade (P < 0.001). The positive predictive value (PPV) of the combination of no restricted diffusion and no arterial enhancement in predicting well-differentiated HCC was 100%, higher than the PPV of individual findings on DWI (74%) or subtraction imaging (81%). CONCLUSIONS: DWI and subtraction imaging are helpful for predicting the histopathological grade of HCC, especially when the two sequences are considered together. KEY POINTS: • Predicting the histopathological grade of hepatocellular carcinoma (HCC) preoperatively is important. • Diffusion-weighted imaging (DWI) and subtraction imaging are recently developed MR techniques. • Retrospective study showed DWI and subtraction imaging helps predict HCC grades. • Management of patients with HCC becomes more appropriate.

Perfusion MRI for the prediction of treatment response after preoperative chemoradiotherapy in locally advanced rectal cancer.

OBJECTIVES: To evaluate the utility of perfusion MRI as a potential biomarker for predicting response to chemoradiotherapy (CRT) in locally advanced rectal cancer. METHODS: Thirty-nine patients with primary rectal carcinoma who were scheduled for preoperative CRT were prospectively recruited. Perfusion MRI was performed with a 3.0-T MRI system in all patients before therapy, at the end of the 2nd week of therapy, and before surgery. The K (trans) (volume transfer constant) and V (e) (extracellular extravascular space fraction) were calculated. RESULTS: Before CRT, the mean tumour K (trans) in the downstaged group was significantly higher than that in the non-downstaged group (P = 0.0178), but there was no significant difference between tumour regression grade (TRG) responders and TRG non-responders (P = 0.1392). Repeated-measures analysis of variance (ANOVA) showed significant differences for evolution of K (trans) values both between downstaged and non-downstaged groups (P = 0.0215) and between TRG responders and TRG non-responders (P = 0.0001). Regarding V (e), no significant differences were observed both between downstaged and non-downstaged groups (P = 0.689) or between TRG responders and TRG non-responders (P = 0.887). CONCLUSION: Perfusion MRI of rectal cancer can be useful for assessing tumoural K (trans) changes by CRT. Tumours with high pre-CRT K (trans) values tended to respond favourably to CRT, particularly in terms of downstaging criteria. KEY POINTS: • Perfusion MRI can now assess therapeutic response of tumours to therapy. • Tumours with high initial K ( trans ) values responded favourably to chemoradiotherapy. • Perfusion MRI of rectal cancer may help with decisions about management.

Accuracy of gadoxetic acid-enhanced magnetic resonance imaging for the diagnosis of sinusoidal obstruction syndrome in patients with chemotherapy-treated colorectal liver metastases.

OBJECTIVE: To assess whether reticular hypointensity on hepatobiliary phase images of gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) is a diagnostic finding of sinusoidal obstruction syndrome (SOS) in patients with hepatic metastases who have undergone chemotherapy. METHODS: We retrospectively analysed EOB-MRI of 42 patients who had undergone chemotherapy before hepatic resection of colorectal hepatic metastases. Two radiologists, who were unaware of whether or not the patients had SOS, reviewed the hepatobiliary phase images to determine the presence of hypointense reticulation in the liver using a 5-point scale. The sensitivity, specificity and area under the receiver operating characteristics curve (A(z)) were calculated for each reviewer. RESULTS: The sensitivity, specificity and A(z) for the diagnosis of SOS were 75%, 100% and 0.957 for reader 1 and 75%, 96.2% and 0.936 for reader 2, respectively. In one patient who received a false-positive diagnosis by one reader, there was sinusoidal fibrosis on histological examination, but not diagnostic for SOS. False-negative diagnosis occurred in four patients for both readers; histology of these patients showed minimal and localised sinusoidal congestion and fibrosis. CONCLUSIONS: Reticular hypointensity on hepatobiliary phase images of EOB-MRI is highly specific for the diagnosis of SOS in patients with treated colorectal hepatic metastases. KEY POINTS: Gadoxetic acid enhanced magnetic resonance imaging (EOB-MRI) can identify the sinusoidal obstruction syndrome (SOS). The diagnosis can be achieved with high specificity and good interobserver agreement. SOS typically demonstrates diffuse hypointensity on hepatobiliary phase images on EOB-MRI. EOB-MRI may be falsely negative in patients with minimal degree of SOS.

The impact of CT follow-up interval on stages of hepatocellular carcinomas detected during the surveillance of patients with liver cirrhosis.

OBJECTIVE: The purpose of our study was to assess the relationship between time intervals of CT examinations and the stages of hepatocellular carcinomas (HCCs) detected during the surveillance of patients with liver cirrhosis. MATERIALS AND METHODS: In this study, 73 patients with 93 HCCs (reference standard: surgery, n=7 [8 HCCs]; biopsy, n=2 [3 HCCs]; imaging criteria, n=64 [82 HCCs]) who showed no evidence of HCC on prior CT examinations were included. Patients were stratified into three groups based on the time interval between the two CT examinations: groups A (interval≤1 year, n=21), B (interval between 1 and 2 years, n=25), and C (interval≥2 years, n=27). Tumor stages according to the American Joint Committee on Cancer (AJCC), the Barcelona Clinic Liver Cancer (BCLC) staging system, and the Milan criteria were evaluated retrospectively by two reviewers. The Fisher exact test was used to compare tumor stages. Spearman correlation coefficients were used to assess the correlation between the CT interval and tumor size. RESULTS: One (4%) HCC in group B and four (15%) HCCs in group C were larger than 5 cm in diameter, whereas no tumor was larger than 3 cm in diameter in group A. There was no difference in tumor diameter between groups, but tumor size was positively correlated with time interval between examinations (Spearman correlation coefficient, 0.472; p<0.001). In group A, 19 (90%) patients had cancers categorized as T1, and the remaining patients had cancers categorized as T2. In group B, one (4%) patient had a cancer that was categorized as T3b according to the AJCC classification, in the intermediate stage according to the BCLC classification, and above the Milan criteria. In group C, three (11%) patients had T3b cancers, and five had cancers in either intermediate or higher stage and above the Milan criteria. CONCLUSION: HCC detected on CT performed within 1 year of a negative examination was at a curable stage in patients with liver cirrhosis.

Hepatocellular carcinoma: clinical and radiological findings in patients with chronic B viral hepatitis and chronic C viral hepatitis.

AIM: To compare clinical and radiological findings of newly diagnosed hepatocellular carcinomas (HCCs) in patients with chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) infections. MATERIALS AND METHODS: Dynamic contrast-enhanced CT images in 532 patients with newly diagnosed HCC were retrospectively reviewed. Of these patients, 418 had chronic HBV infections and 114 had chronic HCV infections. The number, size, shape (nodular vs. non-nodular) and enhancement pattern (typical vs. atypical) of hepatic lesions were assessed. The presence of portal vein thrombosis and bile duct invasion were determined. RESULTS: The mean age of the HBV group (54.31 [range 27-85], median 54) was younger than that of the HCV group (64.21 [range 30-86], median 64) (P < 0.001). Lesions in patients with HBV were more likely to be multifocal (>5; P < 0.001); larger than 5 cm (P = 0.023); non-nodular shape (P < 0.001); atypical enhancement pattern (P = 0.047), association with portal vein thrombosis (P = 0.004); association with bile duct invasion (P < 0.001). CONCLUSIONS: Clinical and radiological findings of HCC differ between patients with HBV and HCV infections.

Liver trauma diagnosis with contrast-enhanced ultrasound: interobserver variability between radiologist and emergency physician in an animal study.

OBJECTIVE: The purpose of our study was to evaluate interobserver variability between the radiologist and emergency physician in detecting blunt liver trauma by conventional and contrast-enhanced ultrasound (US) (CEUS). METHODS: We created 20 sites of blunt liver trauma in rabbits and performed conventional US and CEUS on the animals. A radiologist and an emergency physician independently evaluated the degree of liver trauma. Using contrast-enhanced computed tomography as a reference standard, the diagnostic performance of US and CEUS was calculated. Interobserver variability between radiologist and emergency physician was compared before and after contrast enhancement of US. RESULTS: Overall sensitivity and specificity for detecting liver trauma on conventional US, regardless of the degree of trauma, were 61.1% and 100% for the radiologist and 50% and 100% for the emergency physician. On CEUS, the sensitivity and specificity were 94.4% and 100% for both the radiologist and emergency physician. The interobserver agreement between emergency physician and radiologist increased from 0.867 to 0.955 after contrast enhancement on US. CONCLUSIONS: Contrast-enhanced US may permit a more accurate diagnosis for liver trauma than conventional US by both the radiologist and emergency physician. Contrast-enhanced US may also reduce interobserver variability for this diagnosis.

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.

Comparison of diffusion-weighted MRI and MR volumetry in the evaluation of early treatment outcomes after preoperative chemoradiotherapy for locally advanced rectal cancer.

PURPOSE: To compare diffusion-weighted imaging (DWI) and magnetic resonance (MR) volumetry for predicting treatment outcomes of locally advanced rectal cancers with preoperative chemoradiotherapy (CRT). MATERIALS AND METHODS: This prospective study was approved by our Institutional Review Board. Thirty-four patients underwent three MR examinations: pre-CRT (before CRT), early CRT (2 weeks after CRT initiation), and post-CRT (before surgery). The tumor apparent diffusion coefficient (ADC), ADC increase rate, and volume reduction rate were compared between responders and nonresponders using three reference standards: downstaging, modified Response Evaluation Criteria in Solid Tumors (mRECIST), and tumor regression grade (TRG). For DWI and volumetry, differences between responders and nonresponders were assessed by receiver operating characteristic analysis. RESULTS: The median early tumor volume reduction rate of responders, subgrouped by downstaging and mRECIST (47.97% and 53.97%, respectively), was significantly higher than that of nonresponders (20.94% and 20.36%; P = 0.0024 and 0.0001, respectively), but there were no significant differences in pre-CRT ADC and early ADC increase rate using all references. When using the downstaging and mRECIST, the diagnostic performance of early tumor volume reduction rate (Az = 0.81 and 0.94, respectively) was higher than that of pre-CRT ADC (Az = 0.55 and 0.62; P = 0.033 and 0.007) and early ADC increase rate (Az = 0.58 and 0.64; P = 0.055 and 0.01) for predicting the treatment outcome. For TRG, there were no significant differences between DWI and volumetry. CONCLUSION: Early tumor volume reduction rate at the second week after CRT initiation may be a better indicator than DWI based on the mean ADC measurements for predicting CRT treatment outcome.