Search

Objective: To investigate the diagnostic performance of contrast-enhanced ultrasound (CEUS) and its role as a second-line imaging modality after gadoxetate-enhanced MRI (Gd-EOB-MRI) in the diagnosis of hepatocellular carcinoma (HCC) among at risk observations., Materials and Methods: We prospectively enrolled participants at risk of HCC with treatment-naïve solid hepatic observations (≥ 1 cm) of Liver Imaging Reporting and Data System (LR)-3/4/5/M during surveillance and performed Gd-EOB-MRI. A total of one hundred and three participants with 103 hepatic observations (mean size, 28.2 ± 24.5 mm; HCCs [n = 79], non-HCC malignancies [n = 15], benign [n = 9]; diagnosed by pathology [n = 57], or noninvasive method [n = 46]) were included in this study. The participants underwent CEUS with sulfur hexafluoride. Arterial phase hyperenhancement (APHE) and washout on Gd-EOB-MRI and CEUS were evaluated. The distinctive washout in CEUS was defined as mild washout 60 seconds after contrast injection. The diagnostic ability of Gd-EOB-MRI and of CEUS as a second-line modality for HCC were determined according to the European Association for the Study of the Liver (EASL) and the Korean Liver Cancer Association and National Cancer Center (KLCA-NCC) guidelines. The diagnostic abilities of both imaging modalities were compared using the McNemar's test., Results: The sensitivity of CEUS (60.8%) was lower than that of Gd-EOB-MRI (72.2%, p = 0.06 by EASL; 86.1%, p < 0.01 by KLCA-NCC); however, the specificity was 100%. By performing CEUS on the inconclusive observations in Gd-EOB-MRI, HCCs without APHE (n = 10) or washout (n = 12) on Gd-EOB-MRI further presented APHE (80.0%, 8/10) or distinctive washout (66.7%, 8/12) on CEUS, and more HCCs were diagnosed than with Gd-EOB-MRI alone (sensitivity: 72.2% vs. 83.5% by EASL, p < 0.01; 86.1% vs. 91.1% by KCLA-NCC, p = 0.04). There were no false-positive cases for HCC on CEUS., Conclusion: The addition of CEUS to Gd-EOB-MRI as a second-line diagnostic modality increases the frequency of HCC diagnosis without changing the specificities., Competing Interests: The authors have no potential conflicts of interest to disclose., (Copyright © 2021 The Korean Society of Radiology.)

Background Perfluorobutane (PFB) and sulfur hexafluoride (SHF) have different physiologic characteristics, but it is unclear whether hepatocellular carcinomas (HCCs) show similar wash-in and washout patterns to both contrast agents at US. Purpose To investigate Contrast-Enhanced US Liver Imaging Reporting and Data System (LI-RADS) version 2017 HCC categorization by comparing PFB-enhanced US and SHF-enhanced US in participants at high risk for HCC. Materials and Methods In this prospective study conducted from February to August 2019, participants at high risk for HCC with treatment-naive hepatic observations (≥1 cm) categorized as LR-3, LR-4, LR-5, or LR-M (intermediate probability of HCC, probable HCC, definitely HCC, and probably malignant but not HCC specific, respectively) on cross-sectional images were screened. They underwent same-day PFB-enhanced US and SHF-enhanced US. Arterial phase hyperenhancement (APHE), washout time and degree, and echogenicity in the Kupffer phase (PFB-enhanced US) were evaluated and categorized by the operator using CEUS LI-RADS, who referred to the radiologist who performed the contrast-enhanced US, and by a reviewer. Diagnostic performance was analyzed using the McNemar test. Results Fifty-nine participants were evaluated (43 with HCC, 10 with non-HCC malignancies, six with benign findings). Nonrim APHE was identically observed in 95% (41 of 43, operator) or 88% (38 of 43, reviewer) of HCCs with both contrast agents. Among 43 HCCs, late (≥60 seconds) and mild washout were more frequent with PFB-enhanced US (34 with operator, 33 with reviewer) than with SHF-enhanced US (24 with operator, 26 with reviewer) ( P = .04 or P = .12). The washout time for HCCs was later at PFB-enhanced US (median, 101 seconds ± 11) than at SHF-enhanced US (median, 84 seconds ± 5; P = .04). Sensitivity (34 of 43; 79%; 95% confidence interval [CI]: 64%, 90%) was higher with PFB-enhanced US than with SHF-enhanced US (23 of 43; 54%; 95% CI: 38%, 67%; P = .01). Specificity was 100% (95% CI: 79%, 100%) with both. Hypoenhancement in the Kupffer phase was more common in malignant (49 of 53 [92%] for both operator and reviewer) than in benign (two of six [33%] for operator, one of six [16%] for reviewer) lesions. Conclusion On the basis of the Contrast-Enhanced US Liver Imaging Reporting and Data System version 2017 algorithm, noninvasive US diagnosis of hepatocellular carcinoma by using perfluorobutane-enhanced US had higher diagnostic performance than sulfur hexafluoride-enhanced US, without loss of specificity. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Kim and Jang in this issue.

Purpose: To determine the added value of CEUS on arterial phase non-hyperenhancement (APNHE) observations (LR-3 and LR-4) of CT/MRI in high-risk patients., Methods: Forty-three patients with APNHE observations (≥ 2 cm) from CT/MRI were prospectively enrolled in this IRB-approved study and underwent CEUS. All observations were assessed by LI-RADS for CT/MRI and CEUS. The hemodynamic findings were compared. The mean follow-up period was 11.8 ± 2.1 months. Reference standard was made on 34-APNHE observations based on biopsy (n = 2), surgery (n = 2), and follow-up image (n = 30)., Results: The median of observation size was 2.3 cm (IQR 2.0-2.5 cm). Among the 43-APNHE observations, 12-observations (27.9%) were further presented as arterial phase hyperenhancement (APHE) in CEUS with early (n = 1, CEUS LR-M), late (n = 10, CEUS LR-5), or no (n = 1, CEUS LR-4) washout. Compared to CT, CEUS presented concordant enhancement patterns in 16 (44.4%) in AP and 20 (55.6%) in PVP, respectively. Similarly, 13 (59.1%) and 14 (63.6%) observations showed concordant enhancement patterns between CEUS and MRI in AP and PVP, respectively. Of the 34-APNHE observations with final diagnosis (hepatocellular carcinoma [HCC] n = 12; intrahepatic cholangiocarcinoma [IHCC], n = 1; non-malignancy, n = 21), 4 HCCs (33.3%) and 1 IHCC (100%) were additionally diagnosed by CEUS, while 1 non-malignant lesion (4.5%) was misdiagnosed as HCC by CEUS., Conclusion: Adding CEUS to APNHE observations from CT/MRI would be useful not only for definitely diagnosing HCC (CEUS LR-5) but also for other malignancies (CEUS LR-M). The discordance of dynamic features between the LI-RADS for CEUS and CT/MRI may reflect the different properties of contrast media, although the systems are not interchangeable.

Objectives: While hypersensitivity reactions (HSR) to intravenously administered iodinated contrast media (ICM) have been well studied, not much is known about HSR to intra-arterially administered ICM., Methods: A prospective observational study was performed to evaluate coronary angiography (CAG)-induced ICM hypersensitivity in patients who underwent CAG using ICM including ioversol, a low-osmolar non-ionic monomer, and iodixanol, an iso-osmolar non-ionic dimer. The HSR were investigated through in-patient monitoring after CAG and telephone interview after discharge., Results: A total of 714 patients were enrolled during the observation period, of whom 26 (3.6%) showed immediate HSR and 108 (15.1%) showed delayed HSR. With regard to severity, proportion of immediate HSR grades 1, 2, and 3 was 57.7%, 38.5%, and 3.8%, respectively, whereas that of delayed HSR grades 1, 2, and 3 was 85.2%, 13.9%, and 0.9%, respectively. Multivariate analysis revealed that previous intra-arterial exposure to ICM was an independent risk factor for immediate HSR (odds ratio (OR) 2.92, 95% confidence interval (CI) 1.22-6.96; p = 0.015). Iodixanol was a significant risk factor for delayed HSR (OR 1.61, 95% CI 1.07-2.43; p = 0.024) and correlated with a higher incidence of delayed HSR within 24-h post-ICM administration compared to ioversol., Conclusion: The incidence rate of immediate and delayed HSR in intra-arterially administered ICM was 3.6% and 15.1%, respectively. Previous exposure to intra-arterially administered contrast media was a significant risk factor for immediate HSR. Compared to ioversol, iodixanol was associated with relatively earlier and more frequent delayed HSR., Key Points: • In this prospective study, the incidence of immediate and delayed hypersensitivity in intra-arterial injection of contrast media during coronary angiography was 3.6% and 15.1%, respectively. • Delayed hypersensitivity reactions were more common but less severe than immediate hypersensitivity reactions during coronary angiography. • Previous exposure to ICM via intra-arterial route was a significant risk factor for immediate hypersensitivity to intra-arterial contrast medium.

Objectives: To differentiate between large (≥ 1 cm in diameter) gallbladder (GB) non-neoplastic and neoplastic polyps using quantitative analysis of contrast-enhanced ultrasound (CEUS) findings., Methods: From September 2017 to May 2018, 29 patients (10 males; median age, 63 years) with GB polyps of ≥ 1 cm in diameter who were undergoing cholecystectomy were consecutively enrolled. All patients underwent preoperative conventional US and CEUS examinations. Quantitative analysis of CEUS findings using time-intensity curves between the two groups was independently performed by two radiologists. The interobserver agreement for the quantitative analysis of the CEUS results was measured using the intraclass correlation coefficient. Receiver operating characteristic analysis was performed to evaluate the diagnostic performance of CEUS examination., Results: After the cholecystectomy, the patients were classified into the non-neoplastic polyp group (n = 12) and the neoplastic polyp group (n = 17) according to the pathological results. The interobserver agreement for quantitative assessment between the two radiologists was near perfect to substantial. Quantitative assessment of the CEUS findings revealed that the rise time, mean transit time, time to peak, and fall time of non-neoplastic GB polyps were significantly shorter than those of neoplastic polyps (p < 0.001, p = 0.008, p = 0.013, and p = 0.002, respectively). The sensitivity and specificity of the quantitative CEUS parameters for the differentiation between the two groups were 76.5-100% and 75%, respectively, with an area under the curve of 0.765-0.887., Conclusions: Quantitative analysis of CEUS findings could be valuable in differentiating GB neoplastic polyps from non-neoplastic polyps., Key Points: • Quantitative analysis of CEUS findings could be valuable in differentiating gallbladder neoplastic polyps from non-neoplastic polyps. • Quantitative analysis of CEUS findings in gallbladder polyps provides cut-off values for differentiation between neoplastic polyps and non-neoplastic polyps with near-perfect to substantial interobserver agreement.

Aims: To determine whether contrast-enhanced US using perfluorobutane-containing microbubbles (SEUS) would be helpful for planning a hepatic biopsy., Material and Methods: This prospective study included 40 patients who planned to undergo hepatic biopsy for focal hepatic lesions. All patients underwent B-mode US followed by SEUS. The radiologist evaluated the number of detected lesions, presence of necrosis, conspicuity of target lesion and technical feasibility using 4-point scale. Technical failure and occurrence of change of the target were also assessed. Computer tomography (CT) or magnetic resonance (MR) images were the reference techniques., Results: The mean number of lesions detected on CT and MR images was 6.5±8.4. In 20 (50%) of 40 patients, more focal lesions were detected on SEUS. Targeted lesion was changed in sixpatients (15%) on SEUS. Mean number of detected lesions on SEUS was significantly higher comparing with B-US (5.1±6.2 vs. 2.8±3.8, p<0.001). Conspicuity of the targeted lesion was improved in 67.5% (27 of 40) on SEUS and significantly more visualized than B-US (3.6±0.8 vs. 2.8±0.9, p<0.001). In 7 more patients the necrosis within the lesion was visualized (17.5%) using SEUS. The technical feasibility on SEUS was significantly higher than B-US (2.3±1.0 vs. 3.3±0.9, p<0.001). Technical failure was observed in only one patient (2.5%)., Conclusions: SEUS is a helpful technique for planning the hepatic biopsyin terms of detection, improving lesion conspicuity, tumor viable portion assessment and consequently higher operator confidence, compared with B-US.

Objective: To assess the relationship between contrast-enhanced ultrasound (CEUS) parameters and perfusion CT (PCT) parameters of gastric cancers and their correlation with histologic features., Materials and Methods: This prospective study was approved by our Institutional Review Board. We included 43 patients with pathologically-proven gastric cancers undergoing CEUS using SonoVue® (Bracco) and PCT on the same day. Correlation between the CEUS parameters (peak intensity [PI], area under the curve [AUC], rise time [RT] from 10% to 90% of PI, time to peak [TTP US ], and mean transit time [MTT US ]) and PCT parameters (blood flow, blood volume, TTP CT , MTT CT , and permeability surface product) of gastric cancers were analyzed using Spearman's rank correlation test. In cases of surgical resection, the CEUS and PCT parameters were compared according to histologic features using Mann-Whitney test., Results: CEUS studies were of diagnostic quality in 88.4% (38/43) of patients. Among the CEUS parameters of gastric cancers, RT and TTP US showed significant positive correlations with TTP CT (rho = 0.327 and 0.374, p = 0.045 and 0.021, respectively); PI and AUC were significantly higher in well-differentiated or moderately-differentiated tumors (n = 4) than poorly-differentiated tumors (n = 18) ( p = 0.026 and 0.033, respectively), whereas MTT CT showed significant differences according to histologic types (poorly cohesive carcinoma [PCC] vs. non-PCC), T-staging (≤ T2 vs. ≥ T3), N-staging (N0 vs. N-positive), and epidermal growth factor receptor expression (≤ faint vs. ≥ moderate staining) ( p values < 0.05)., Conclusion: In patients with gastric cancers, CEUS is technically feasible for the quantification of tumor perfusion and may provide correlative and complementary information to that of PCT, which may allow prediction of histologic features., Competing Interests: The authors have no potential conflicts of interest to disclose., (Copyright © 2019 The Korean Society of Radiology.)

Background: Kupffer cells (KC) have an important role in the host defense in obstructive cholangitis. Non-invasive monitoring of phagocytic function of KC is pivotal. Several studies showed the possibility of non-invasive monitoring of phagocytic function of KC using superparamagnetic iron oxide-enhanced magnetic resonance imaging (SPIO-MRI) or contrast-enhanced ultrasound (CEUS)., Purpose: To investigate the serial change of KC function using SPIO-MRI and CEUS and whether the SPIO-MRI parameter correlates with the CEUS parameter in obstructive cholangitis rat models., Material and Methods: With our institutional Animal Care and Use Committee approval, 19 rats (common bile duct ligation [CBDL]: n = 9; control: n = 10) underwent SPIO-MRI and CEUS at baseline, two, and four weeks after CBDL. The relative signal loss (RSL) of T2* value on SPIO-MRI and Kupffer phase parenchymal echogenicity (KPE) on CEUS were measured. The correlation between SPIO-MRI and CEUS parameters were compared with KC count., Results: In CBDL group, RSL and KPE had significantly decreased (72.1% to 29.5%, 2.7 to 0.4) at four weeks compared with those in the control group (68.2% to 58.3%, 2.5 to 3.0, P < 0.05). During the follow-up period, RSL showed significantly positive correlations with KPE ( P = 0.007). In addition, at four weeks, we found RSL was positively correlated with KPE (ρ = 0.750, P = 0.002). KC count was negatively correlated to RSL and KPE at four weeks (ρ = -0.771, P = 0.001 and ρ = -0.644, P = 0.013)., Conclusion: SPIO-MRI and CEUS may be equally useful for monitoring the serial changes of KC phagocytic function in vivo.

Purpose: To investigate whether pre-operative gadoxetic acid-enhanced MRI can predict early recurrence after curative resection of single HCC using image features and texture analysis., Materials and Methods: 179 patients with single HCC and who underwent pre-operative MRI were included. Two reviewers analyzed MR findings, including the tumor margin, peritumoral enhancement, peritumoral hypointensity on the hepatobiliary phase (HBP), diffusion restriction, capsule, tumoral fat, washout, portal-vein thrombus, signal intensity on HBP, and satellite nodule. Texture analysis on the HBP was also quantified. A multivariate analysis was used to identify predictive factors for early recurrence, microvascular invasion (MVI), and the tumor grade., Results: For early recurrence, satellite nodule, peritumoral hypointensity, absence of capsule, and GLCM ASM were predictors (P < 0.05). For MVI, satellite nodule, peritumoral hypointensity, washout, and sphericity were predictors (P < 0.05). Satellite nodules, peritumoral hypointensity, diffusion restriction, and iso to high signal intensity on HBP were predictor for higher tumor grade (P < 0.05). Satellite nodules and peritumoral hypointensity were important showed common predictors for early recurrence, MVI, and grade (P < 0.05). The sensitivity and specificity for satellite nodule were 47.36% and 96.25%. When added texture variables to MRI findings, the diagnostic performance for predicting early recurrence is improved from 0.7 (SD 0.604-0.790) to 0.83 (SD 0.787-0.894)., Conclusion: MR finding, including satellite nodule and peritumoral hypointensity on the HBP, as well as the texture parameters are useful to predict not only early recurrence, but also MVI and higher grade.

Purpose: To determine the value of CEUS for real-time, fusion-guided, percutaneous biopsies of focal liver lesions., Materials and Methods: Institutional review board approval and written informed consents were obtained for this study. Forty patients with focal liver lesions identified on CT/MRI were prospectively enrolled. For biopsy planning, real-time fusion of CT/MRI with USG (USG-Fusion) was performed, and subsequently real-time CEUS was fused with CT/MRI (CEUS-Fusion). We evaluated lesion visibility, confidence level of technical success before the procedure, and safety route accessibility on USG-Fusion and CEUS-Fusion. Occurrence of change in the biopsy target was also assessed., Results: Among 40 target lesions, nine (22.5%) lesions were invisible on USG-Fusion. After applying CEUS-Fusion, seven of nine (77.8%) lesions were visualized. Confidence level of technical success of procedure was significantly increased on CEUS-Fusion compared USG-Fusion (p = 0.02), and presumed target lesions were changed in 16 (40%) patients after CEUS-Fusion. As the lesion is necrotic, presumed target was more frequently changed after CEUS-Fusion (50.0% and 25.0%). Confirmative diagnostic results were reported in 39 (97.5%) patients. Accessibility of the safety route to target lesions did not reach statistical differences., Conclusion: Applying a new, real-time CEUS-Fusion with CT/MRI improved tumor visibility and viable portion assessment, thus leading to higher operator confidence and diagnostic yield, when compared with conventional USG-Fusion.

Objective: To correlate CT parameters on detector-based dual-energy CT enterography (DECTE) with Crohn's disease activity index (CDAI) and externally validate quantitative CT parameters., Materials and Methods: Thirty-nine patients with CD were retrospectively enrolled. Two radiologists reviewed DECTE images by consensus for qualitative and quantitative CT features. CT attenuation and iodine concentration for the diseased bowel were also measured. Univariate statistical tests were used to evaluate whether there was a significant difference in CTE features between remission and active groups, on the basis of the CDAI score. Pearson's correlation test and multiple linear regression analyses were used to assess the correlation between quantitative CT parameters and CDAI. For external validation, an additional 33 consecutive patients were recruited. The correlation and concordance rate were calculated between real and estimated CDAI., Results: There were significant differences between remission and active groups in the bowel enhancement pattern, subjective degree of enhancement, mesenteric fat infiltration, comb sign, and obstruction ( p < 0.05). Significant correlations were found between CDAI and quantitative CT parameters, including number of lesions (correlation coefficient, r = 0.573), bowel wall thickness ( r = 0.477), iodine concentration ( r = 0.744), and relative degree of enhancement ( r = 0.541; p < 0.05). Iodine concentration remained the sole independent variable associated with CDAI in multivariate analysis ( p = 0.001). The linear regression equation for CDAI (y) and iodine concentration (x) was y = 53.549x + 55.111. For validation patients, a significant correlation ( r = 0.925; p < 0.001) and high concordance rate (87.9%, 29/33) were observed between real and estimated CDAIs., Conclusion: Iodine concentration, measured on detector-based DECTE, represents a convenient and reproducible biomarker to monitor disease activity in CD.

Objective: To evaluate the diagnostic value of T2 * mapping using 3D multi-echo Dixon gradient echo acquisition on gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) as a tool to evaluate hepatic function., Materials and Methods: This retrospective study was approved by the IRB and the requirement of informed consent was waived. 242 patients who underwent liver MRIs, including 3D multi-echo Dixon fast gradient-recalled echo (GRE) sequence at 3T, before and after administration of gadoxetic acid, were included. Based on clinico-laboratory manifestation, the patients were classified as having normal liver function (NLF, n = 50), mild liver damage (MLD, n = 143), or severe liver damage (SLD, n = 30). The 3D multi-echo Dixon GRE sequence was obtained before, and 10 minutes after, gadoxetic acid administration. Pre- and post-contrast T2 * values, as well as T2 * reduction rates, were measured from T2 * maps, and compared among the three groups., Results: There was a significant difference in T2 * reduction rates between the NLF and SLD groups (-0.2 ± 4.9% vs. 5.0 ± 6.9%, p = 0.002), and between the MLD and SLD groups (3.2 ± 6.0% vs. 5.0 ± 6.9%, p = 0.003). However, there was no significant difference in both the pre- and post-contrast T2 * values among different liver function groups ( p = 0.735 and 0.131, respectively). A receiver operating characteristic (ROC) curve analysis showed that the area under the ROC curve for using T2 * reduction rates to differentiate the SLD group from the NLF group was 0.74 (95% confidence interval: 0.63-0.83)., Conclusion: Incorporation of T2 * mapping using 3D multi-echo Dixon GRE sequence in gadoxetic acid-enhanced liver MRI protocol may provide supplemental information for liver function deterioration in patients with SLD.

Objective: To determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI)., Materials and Methods: Informed consent was waived for this retrospective study by our Institutional Review Board. In 752 consecutive patients who underwent gadoxetic acid-enhanced liver MRI, either single (n = 587) or triple (n = 165) arterial phases was obtained in a single breath-hold under MR fluoroscopy guidance. Arterial phase timing was assessed, and the degree of motion was rated on a four-point scale. The percentage of patients achieving the late arterial phase without significant motion was compared between the two methods using the χ(2) test., Results: The late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001)., Conclusion: Triple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.

Objective: To compare multidetector computed tomography (MDCT) and MRI for lesion conspicuity, as well as the detection and characterization of small solid pancreatic lesions (SPLs)., Materials and Methods: 193 patients with small SPLs (< 3 cm) and 52 patients with normal pancreas who underwent both multiphasic MDCT and gadobutrol-enhanced MRI were included in our study. Two radiologists blinded to the pathologic diagnoses independently reviewed those images, and determined the detection of "SPL per se" and "SPL in consideration of secondary features", the lesion conspicuity, the probability of pancreatic ductal adenocarcinoma (PDAC), and the most likely specific diagnosis., Results: The sensitivity of MRI for "detection of SPL per se" was significantly higher than that of CT in both reviewers: 92.7% (179/193) and 97.9% (189/193), respectively, for reviewer 1 (p = 0.031) and 90.7% (175/193) and 99.5% (192/193), respectively, for reviewer 2 (p < 0.001). In addition, MRI provided better lesion conspicuity than MDCT for both reviewers (p < 0.001). However, CT and MRI did not show significant difference in sensitivity for "detection of SPL in consideration of secondary features", specificity for SPL detection, and differentiation of PDAC vs. non-PDAC (p > 0.05). The accuracies of CT and MRI for making a specific diagnosis were as follows: 85.7% (210/245) vs. 86.9% (213/245), respectively, for reviewer 1 (p = 0.736), and 91.8% (225/245) vs. 93.5% (229/245), respectively, for reviewer 2 (p = 0.454)., Conclusion: MRI showed better lesion conspicuity than MDCT, but did not show significantly different diagnostic performance compared with MDCT for detecting and characterizing small SPLs.

The aim of this study was to assess the feasibility of using dynamic contrast-enhanced ultrasound (DCE-US) with a 3-D transducer to evaluate therapeutic responses to targeted therapy. Rabbits with hepatic VX2 carcinomas, divided into a treatment group (n = 22, 30 mg/kg/d sorafenib) and a control group (n = 13), were evaluated with DCE-US using 2-D and 3-D transducers and computed tomography (CT) perfusion imaging at baseline and 1 d after the first treatment. Perfusion parameters were collected, and correlations between parameters were analyzed. In the treatment group, both volumetric and 2-D DCE-US perfusion parameters, including peak intensity (33.2 ± 19.9 vs. 16.6 ± 10.7, 63.7 ± 20.0 vs. 30.1 ± 19.8), slope (15.3 ± 12.4 vs. 5.7 ± 4.5, 37.3 ± 20.4 vs. 15.7 ± 13.0) and area under the curve (AUC; 1004.1 ± 560.3 vs. 611.4 ± 421.1, 1332.2 ± 708.3 vs. 670.4 ± 388.3), had significantly decreased 1 d after the first treatment (p = 0.00). In the control group, 2-D DCE-US revealed that peak intensity, time to peak and slope had significantly changed (p < 0.05); however, volumetric DCE-US revealed that peak intensity, time-intensity AUC, AUC during wash-in and AUC during wash-out had significantly changed (p = 0.00). CT perfusion imaging parameters, including blood flow, blood volume and permeability of the capillary vessel surface, had significantly decreased in the treatment group (p = 0.00); however, in the control group, peak intensity and blood volume had significantly increased (p = 0.00). It is feasible to use DCE-US with a 3-D transducer to predict early therapeutic response after targeted therapy because perfusion parameters, including peak intensity, slope and AUC, significantly decreased, which is similar to the trend observed for 2-D DCE-US and CT perfusion imaging parameters., (Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Objectives: To investigate the diagnostic performance of gadoxetic acid-enhanced MRI including diffusion-weighted imaging (DWI) for the detection of colorectal liver metastases (CRLMs) after neoadjuvant chemotherapy (NAC)., Methods: Our study population comprised 77 patients with 140 CRLMs who underwent gadoxetic acid-enhanced MRI within 1 month prior to surgery: group A (without NAC, n = 38) and group B (with NAC, n = 39). Two radiologists independently assessed all MR images and graded their diagnostic confidence for CRLM on a 5-point scale. Diagnostic accuracy, sensitivity and positive predictive values (PPV) were calculated and compared between the two groups., Results: Diagnostic accuracy of gadoxetic acid-enhanced MRI in group B was slightly lower than in group A, but a statistically significant difference was not observed (observer 1: A z, 0.926 in group A, 0.905 in group B; observer 2: A z, 0.944 in group A, 0.885 in group B; p > 0.05). Sensitivity and PPV of group B were comparable to those of group A (observer 1: sensitivity = 93.5 % vs. 93.6 %, PPV = 95.1 % vs. 86.9 %; observer 2: sensitivity = 96.8 % vs. 91.0 %; PPV = 90.0 % vs. 89.7 %; all p > 0.05)., Conclusions: Gadoxetic acid-enhanced MRI including DWI provided good diagnostic performance with high sensitivity (>90 %) for the detection of CRLMs, regardless of the influence of NAC., Key Points: • Gadoxetic acid-enhanced MRI including DWI shows high sensitivity for CRLMs. • Chemotherapy does not influence the diagnostic performance of liver MRI for CRLMs. • Gadoxetic acid-enhanced MRI can be used for evaluation of CRLMs after NAC.

Purpose: To determine whether a navigator-gated three-dimensional T1-weighted gradient-echo sequence (T1W-GRE, navigated LAVA) can improve diagnostic performance for the detection of focal liver lesions (FLLs) compared to standard breath-hold (BH) T1W-GRE breath-hold LAVA (BH-LAVA) during the hepatobiliary phase (HBP) of gadoxetic acid liver magnetic resonance imaging (MRI) in patients with limited breath-holding capacity., Materials and Methods: This retrospective study was approved by our institutional review board and the requirement for informed consent was waived. We included 372 patients who underwent liver MRI including both navigated LAVA and BH-LAVA sequences. Overall image quality of the two HBP image sets was compared. In patients with limited breath-holding capacity, diagnostic performances in detecting FLLs on the two HBP images were compared using jackknife-alternative free-response receiver-operating characteristic (JAFROC) analysis by two reviewers., Results: There were 13 cases (13/372; 3.5%) of image acquisition failure using the navigated LAVA sequence due to severe irregular breathing, and 50 of 359 patients had limited breath-holding capacity. In these patients, overall image quality of navigated LAVA (2.78 ± 0.95) was significantly better than that of BH-LAVA (2.42 ± 0.81, P < 0.005), and both readers showed significantly higher JAFROC figure-of-merit values with navigated LAVA compared to BH-LAVA (0.94 and 0.86 in reviewer 1, respectively; 0.89 and 0.83 in reviewer 2, respectively, P < 0.005). Overall image quality of navigated LAVA was also better than that of BH-LAVA in patients with sufficient breath-holding capacity (n = 309, 3.96 ± 0.88, 3.81 ± 0.66, respectively, P < 0.001)., Conclusion: The navigated LAVA sequence could provide better image quality and diagnostic performance in detecting FLLs than BH-LAVA in patients with limited breath-holding capacity during HBP of gadoxetic acid MRI.

Purpose: The purpose of the study is to describe the CT findings of poorly differentiated (PD) colorectal adenocarcinoma (CRAC) compared with those of well- (WD) or moderately differentiated (MD) CRAC., Materials and Methods: One hundred and thirteen patients with pathologically proven PD (n = 26), WD (n = 35), or MD (n = 52) CRACs and who had undergone preoperative, contrast-enhanced multidetector CT (MDCT) imaging were included. Analysis of the CT findings included the morphologic and enhancement features of primary tumors and regional lymph nodes (LNs), and the presence of direct invasion, colonic obstruction, and distant metastasis. The significance of these findings was determined using the χ (2) test., Results: Significant features favoring the diagnosis of PD CRACs over WD or MD CRACs included their bulky shape, heterogeneous enhancement, iso- or hypoattenuation compared with that of muscle, nodular pericolic fat infiltration, regional LNs > 10 mm, and/or with iso- or hypoattenuation compared with that of muscle, and the presence of distant metastasis (P < 0.05). When at least two of these seven imaging features were used in combination, the sensitivity and specificity in the diagnosis of PD CRACs were 88% and 70%, respectively., Conclusion: Using characteristic CT features, one can differentiate PD CRAC from WD or MD CRAC with a high degree of accuracy on contrast-enhanced MDCT.

Purpose: To assess therapeutic efficacy of gemcitabine and HIFU for a mouse model of pancreatic cancer, and the role of DCE-US for predicting early treatment response compared with pathology., Materials and Methods: In 48 PANC-1- nude mice (G1, HIFU&#95;higher power [n = 14]; G2, gemcitabine [n = 12]; G3, combined gemcitabine and HIFU&#95;low power [n = 12]; and G4, control [n = 10]), pulsed HIFU or gemcitabine therapy was used. DCE-US was performed 1 day before and after first treatment. Seven DCE-US perfusion parameters were obtained. Therapeutic efficacy was estimated using necrotic fraction and apoptosis. Correlation between tumour size and US perfusion parameters was analysed., Results: Pathology results showed that combined gemcitabine and HIFU using low-power treatment had a more effective response than other treatments, including in the control group, i.e. necrotic fraction: 40.5 ± 4.9 vs. 16.9 ± 8.0, p = 0.000 and apoptosis: 44.3 ± 29.4 vs. 7.9 ± 4.9, p = 0.002. In this group, US perfusion parameters, including peak intensity (22.6 ± 22.6 vs. 9.6 ± 6.3, p = 0.002), AUC (961.8 ± 96.9 vs. 884.4 ± 91.4, p = 0.000), and AUCout (799.9 ± 75.6 vs. 747.1 ± 77.9, p = 0.000), had significantly decreased 1 day following first treatment (p < 0.05). In addition, peak intensity, AUC, and AUCout showed a tendency to decrease in treated groups. Alternatively, peak intensity, AUC, and AUCout showed a tendency to increase in control group., Conclusion: Gemcitabine and HIFU were more effective and safer than other treatments. US perfusion parameters were useful for predicting early therapeutic response 1 day following treatment., Key Points: Recently, treatment of pancreatic cancer has changed based on a multidisciplinary approach. Combined gemcitabine&#95;HIFU demonstrated more effective therapeutic response than other treatments. DCE-US is useful for predicting early therapeutic response 1 day after treatment. In the combined group, PI, AUC, and AUC (out) decreased 1 day after treatment.

Purpose: To assess diagnostic performance and imaging features of gadoxetic acid-enhanced magnetic resonance (MR) imaging in small (≤1-cm) hepatocellular carcinoma (HCC) detection in patients with chronic liver disease., Materials and Methods: The institutional review board approved this retrospective study and waived informed consent. Sixty patients (56 men, four women; mean age, 60.1 years) with HCC (146 lesions; 70 > 1 cm, 76 ≤ 1 cm) underwent gadoxetic acid-enhanced MR imaging. HCC was confirmed at surgical resection (72 lesions; 30 > 1 cm, 42 ≤ 1 cm) or by showing interval growth with typical enhancement patterns at follow-up dynamic computed tomography or MR imaging (74 lesions; 40 > 1 cm, 34 ≤ 1 cm). Two radiologists assessed MR imaging features and graded likelihood of HCC with a five-point confidence scale. Jackknife alternative free-response receiver operating characteristic (JAFROC) method was used., Results: Mean JAFROC figure of merit for small HCC was 0.717; that for large (>1-cm) HCC was 0.973 with substantial agreement (κ = 0.676). Mean sensitivity and positive predictive value (PPV) were 46.0% (70 of 152) and 48.3% (70 of 145) for small HCC versus 95.0% (133 of 140) and 78.2% (133 of 170) for large HCC, respectively. Eleven of 76 small HCCs (14%) were not seen on MR images, even after careful investigation. MR imaging features of small HCC included arterial enhancement (79%, 60 of 76), hypointensity on hepatobiliary phase (HBP) images (68%, 52 of 76), washout on 3-minute delayed phase images (50%, 38 of 76), hyperintensity on T2-weighted images (43%, 33 of 76), hypointensity on T1-weighted images (32%, 24 of 76), and restriction on diffusion-weighted images (28%, 20 of 72). Arterial enhancement and washout on 3-minute delayed phase images or hypointensity on HBP images occurred in 66% of small HCCs (50 of 76)., Conclusion: Diagnostic performance of gadoxetic acid-enhanced MR imaging for small HCC detection is still low, with mean sensitivity of 46.0% (70 of 152) and mean PPV of 48.3% (70 of 145). By adding hypointensity on HBP images as washout, diagnostic performance for small HCC detection can be improved.

Purpose: To investigate the patterns of imaging appearance of hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance (MR) images and to assess their potential value as prognostic markers of HCC associated with tumor recurrence after surgery., Materials and Methods: The institutional review board approved this retrospective study and informed consent was waived. A total of 216 patients with 304 pathologically proved HCCs underwent gadoxetic acid-enhanced MR imaging prior to surgery and were included in the study. Two reviewers, blinded to the clinical data, evaluated in consensus the imaging patterns of HCC according to enhancement patterns on dynamic phase images and signal intensity on hepatobiliary phase (HBP) images. The association of imaging features with clinical-pathologic findings was evaluated by using the Student t test, χ(2) test, Mann-Whitney U test, and linear-by-linear association. The dependence of time to tumor recurrence (TTR) after surgery was evaluated by using the Kaplan-Meier method, log-rank test, and Cox proportional hazard model., Results: HCCs with atypical enhancement pattern (P = .0167, P = .0450, P < .0001, respectively) and iso- to hyperintensity on HBP images (P = .0001, P = .0002, P < .0001, respectively) had smaller tumor size, lower histologic grade, and worse Child-Pugh class. The log-rank test (P = .0064) and Cox proportional hazards model (hazard ratio, 5.676; P = .0158) revealed that HCCs with iso- to hyperintensity on HBP images had significantly longer TTR than HCCs with hypointensity on HBP images., Conclusion: HCCs can be classified into several imaging patterns on gadoxetic acid-enhanced MR images, which are associated with tumor aggressiveness and outcome. In addition, iso- to hyperintensity on HBP images may be a useful imaging biomarker to indicate longer TTR after surgery. .

Purpose: To assess the feasibility of postprocessing dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging timing bolus data by using a three-dimensional radial gradient-echo technique with k-space-weighted image contrast (KWIC) for the characterization of solid pancreatic diseases., Materials and Methods: This retrospective study was approved by the institutional review board, and informed consent was waived. A total of 45 patients suspected of having biliary or pancreatic disease underwent pancreatic MR examination with a 3.0-T imager with a low-dose (2 mL gadopentetate dimeglumine) timing bolus by using the radial KWIC technique. There were 24 patients with pancreatic cancers, eight with pancreatic neuroendocrine tumors (PNETs), three with chronic pancreatitis, and 10 with a normal pancreas. By using a dedicated postprocessing software program for DCE MR imaging, the following perfusion parameters were measured for tumor and nontumorous parenchyma: volume transfer coefficient (K(trans)) and extracellular extravascular volume fraction; the rate constant (k(ep)) and initial area under the concentration curve in 60 seconds (iAUC) were then generated. The perfusion parameters acquired on DCE MR images were compared among the groups by using the analysis of variance test., Results: K(trans), k(ep), and iAUC values in patients with pancreatic cancer (0.042 min(-1) ± 0.023 [standard deviation], 0.761 min(-1) ± 0.529, and 2.841 mmol/sec ± 1.811, respectively) were significantly lower than in patients with a normal pancreas (0.387 min(-1) ± 0.176, 6.376 min(-1) ± 2.529, and 7.156 mmol/sec ± 3.414, respectively) (P < .05 for all). In addition, k(ep) values of PNETs and normal pancreas also differed (P < .0001), and K(trans), k(ep), and iAUC values of pancreatic cancers and PNETs differed significantly (P < .0001, P = .038, and P < .0001, respectively)., Conclusion: Results of timing bolus DCE MR imaging with the radial KWIC sequence from routine examinations can be postprocessed to yield potentially useful perfusion parameters for the characterization of pancreatic diseases., (RSNA, 2012)

Purpose: To compare the diagnostic performance of a diffusion-weighted imaging (DWI) dataset and a gadofluorine M-enhanced imaging dataset for identifying lymph node (LN) metastases in a rabbit rectal cancer model., Materials and Methods: VX2 carcinomas were injected into the rectum of 26 rabbits. Four weeks later, T2-weighted imaging (T2WI), pre-T1WI, DWI, and post-T1WI were performed. Two radiologists independently reviewed the DWI set (T2WI, pre-T1WI, DWI) and the gadofluorine M set (T2WI, pre- and post-T1WI) and recorded their confidence scores for LN metastasis on a per-LN basis. Receiver operating characteristic (ROC) analysis was performed to compare the area under the ROC curve (A(z) ) of the two imaging sets. Histopathologic results were used as the reference standard., Results: The A(z) and sensitivity of the gadofluorine M set were comparable to those of the DWI set (A(z) , for reader 1, 0.849, 0.829, P = 0.571; for reader 2, 0.923, 0.876, P = 0.212; sensitivity, for reader 1, 97%, 97%; for reader 2, 97%, 92%, P = 0.304). The specificity of the former was greater than that of the latter (for reader 1, 65%, 53%, P = 0.0003; for reader 2, 81%, 68%, P = 0.01)., Conclusion: Gadofluorine M-enhanced images provided greater specificity than DWI for identifying LN metastases, whereas the A(z) and sensitivity of the former were comparable to those of the latter., (Copyright © 2012 Wiley Periodicals, Inc.)

Objective: The purpose of our study was to investigate whether virtual nonenhanced images can replace true nonenhanced images for the evaluation of biliary stones and to compare two virtual nonenhanced images obtained from dual-energy data sets during the late arterial phase (LAP) and portal venous phase (PVP) with true nonenhanced images., Materials and Methods: One hundred patients with gallstones (n = 77) or bile duct stones (n = 23) who had undergone dual-source dual-energy CT (using 80kVp and 140kVp with the ratio of dose-partitioning, 1:1.3), were included. The CT numbers for the stone, liver, and bile; stone size; and image noise were assessed for each image set. The conspicuity and size of the stones, image quality, and acceptability of the virtual nonenhanced images as a replacement for true nonenhanced images were assessed., Results: Virtual nonenhanced images from both LAP (VNE(LAP)) and PVP showed lower CT numbers for the stone and smaller stone size than did true nonenhanced images (p < 0.05). VNE(LAP) images failed to show stones in 16 patients (16%) with relatively radiolucent bile duct stones (< 78 HU) or small gallstones (< 9 mm(2), < 1.7 mm). There was no difference between the two virtual nonenhanced image sets except for the contrast-to-noise ratio of stone to bile and the image noise (CT numbers for the stone, liver, and muscle; stone size; and contrast-to-noise ratio of stone to liver, p = 1; the CT number for the bile, p = 0.1618; and effective dose, p = 0.7478). VNE(LAP) images were considered acceptable as a replacement for true nonenhanced images in 89% and 90% by reviewers 1 and 2, respectively., Conclusion: Virtual nonenhanced images allow the detection of biliary stones with moderate accuracy, irrespective of the dual-energy contrast-enhanced phase. The detection of gallbladder stones of 9 mm(2) or smaller and of relatively radiolucent bile duct stones of 78 HU or lower is limited.

Objective: The purpose of this study was to describe the CT features of gastroduodenal glomus tumors and determine the CT features differentiating glomus tumors from other subepithelial lesions., Materials and Methods: CT images of 89 pathologically proven small (≤ 5 cm) gastroduodenal glomus tumors (n = 11), gastrointestinal stromal tumors (n = 44), schwannomas (n = 15), ectopic pancreata (n = 12), and leiomyomas (n = 7) were retrospectively reviewed. For subjective analysis, location, shape, growth pattern, enhancement pattern, and presence of necrosis, calcification, and surface ulceration were analyzed. For objective analysis, the long and short diameters of the lesion, ratio of long to short diameter, thickness of the overlying layer, CT attenuation of the lesion and aorta, and lesion-to-aorta ratio in the arterial, portal venous, and equilibrium phases were measured. Among these findings, significant CT variables were determined with the chi-square, Fisher exact, and Student t tests. Receiver operating characteristic analysis was used to determine the optimal cutoff values of thickness of the overlying layer and lesion-to-aorta ratio that differentiate glomus tumor from other subepithelial lesions., Results: Typical location (antrum and duodenum), hemangioma-like enhancement pattern, overlying layer thickness 2.6 mm or greater, and portal venous phase lesion-to-aorta ratio 0.86 or greater were found to be significant variables for differentiating glomus tumors from other subepithelial lesions (p < 0.05). Among these CT findings, location and portal venous phase lesion-to-aorta ratio 0.86 or greater were highly sensitive findings for glomus tumor, and a hemangioma-like enhancement pattern was highly specific. All odds ratios were infinity. The odds ratio of overlying layer thickness of 2.6 mm or greater was 12.2 (95% CI, 2.9-51.8)., Conclusion: A subepithelial lesion with a lesion-to-aorta ratio less than 0.86 in the portal venous phase or not in the gastric antrum or duodenum is never a glomus tumor. On the contrary, a subepithelial lesion with hemangioma-like enhancement during dynamic CT is essentially a glomus tumor. On the basis of these CT findings, glomus tumor can be differentiated from other subepithelial lesions with high diagnostic accuracy.

We report a case of an adenoma arising from an ectopic adrenal gland mimicking a hepatocellular carcinoma in a heavy alcohol abuser. A MDCT showed a 2.7 low-attenuating nodule in segment VII of the liver through all CT phases. Compared to a precontrast image, however, a subtle enhancement was noted on the arterial phase CT image. On T1 weighted in- and opposed-phase MR images, an abundant fat component within the lesion was seen. Dynamic contrast-enhanced MR images after administration of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) more clearly depicted hypervascularity and wash-out of the lesion on arterial and portal phases, respectively. On delayed hepatobiliary phase MR images, obtained 20 minutes after Gd-EOB-DTPA administration, subtle uptake or retention of the contrast agent by the lesion was suspected. A tumorectomy was performed and adrenal adenoma from an ectopic adrenal gland within the liver was confirmed.

Purpose: To determine the accuracy of magnetic resonance imaging (MRI) including dynamic imaging using three-dimensional gradient-echo (3D-GRE) sequences and MR cholangiopancreatograpy (MRCP) compared with that of multidetector row CT (MDCT) with regard to resectability in pancreas cancer., Materials and Methods: From February 2004 to July 2008, 54 patients (32 men, 22 women: age range, 28-83 years; mean age, 63.1 years old) with surgically proven pancreatic carcinoma, who had undergone preoperative gadolinium-enhanced 3D-GRE MRI with MRCP and triple-phase MDCT, were included in this retrospective study. Two, clinically experienced attending radiologists independently reviewed the two image sets. These readers evaluated the tumor conspicuity, presence of vascular invasion, choledochal and duodenal invasion, lymph node metastases, distant metastasis, and tumor resectability. The results were compared with the surgical and histopathologic findings using receiver operating characteristic analysis (Az) and kappa statistics., Results: Curative resections were performed on 42 patients. Regarding the tumor conspicuity, MRI had a significantly higher Az value compared with MDCT according to both reviewers (P < 0.05). The accuracy of resectability was Az = 0.753 and 0.768 on MRI and Az = 0.829 and 0.762 on MDCT for each reviewer, and the difference in the accuracy of resectability was not significant between MRI and MDCT for either reviewer (P > 0.05). Two imaging sets showed a similar diagnostic performance in the evaluation of vascular involvement, lymph node metastasis, and distant metastasis., Conclusion: Dynamic 3D-GRE MRI with MRCP shows superior tumor conspicuity and similar diagnostic performance compared with MDCT in evaluating the resectability of pancreatic cancer.

Objective: The purpose of our study is to show the usefulness and safety of sonography transmission gel as an endorectal contrast agent in preoperative rectal MRI for tumor visualization in rectal cancer., Conclusion: Sonography transmission gel is an effective and safe endorectal contrast agent for rectal MRI.

The purpose of this study was to determine whether MR angiography utilizing the time resolved echo-shared angiographic technique (TREAT) can provide an effective assessment of the hepatic artery (HA) and portal vein (PV) in living donor candidates. MR angiography (MRA)was performed in 27 patients (23 men and 4 women; mean age, 31 years) by using TREAT. Two blinded radiologists evaluated HA anatomy, origin of segment IV feeding artery and PV anatomy in consensus. Qualitative evaluations of MRA images were performed using the following criteria: (a) overall image quality, (b) presence of artifacts, and (c) degree of venous contamination of the arterial phase. Using intraoperative findings as a standard of reference, the accuracy for the HA anatomy, origin of segment IV feeding artery and PV anatomy on TREAT-MRA were 93% (25/27), 85% (23/27), and 96% (26/27), respectively. Overall image qualities were as follows: excellent (n=22, 81%), good (n=4, 15%), and fair (n=1, 4%). Significant artifacts or venous contamination of the arterial phase images was not noted in any patient. TREAT-MRA can provide a complete evaluation of HA and PV anatomy during preoperative evaluation of living liver donors. Furthermore, it provides a more detailed anatomy of the HA without venous contamination.

Objective: The purpose of this article is to describe the characteristic findings of intrapancreatic accessory spleen over time on contrast-enhanced sonography., Conclusion: On contrast-enhanced sonography, intrapancreatic accessory spleens showed a characteristic inhomogeneous enhancement on the early vascular phase, enhancement similar to the main spleen during the postvascular phases, and prolonged enhancement on the delayed hepatosplenic phase.

Objective: The objective of our study was to determine whether gadobenate dimeglumine-enhanced MRI is practical as the sole preoperative imaging technique for the examination of living liver donors., Subjects and Methods: Forty-four consecutive living donor candidates underwent liver MRI on a 1.5-T MR unit. The MR examination included in- and opposed-phase T1-weighted gradient-echo imaging, T2-weighted MR cholangiography, MR angiography (MRA) and parenchymal phase imaging after the administration of gadobenate dimeglumine, and 60-minute delayed T1-weighted MR cholangiography. Two abdominal radiologists analyzed the images regarding the depiction of the biliary duct anatomy and the hepatic vascular anatomy and for the presence of focal or diffuse liver disease. The findings were compared with intraoperative cholangiographic and surgical findings in 24 patients who underwent partial hepatectomy., Results: In the 24 patients who underwent liver harvesting, 10 had biliary anatomic variants confirmed by intraoperative cholangiography. T2-weighted MR cholangiography allowed a correct diagnosis in 75% (n = 18/24) and T1-weighted MR cholangiography in 79% (n = 19/24) of these patients. When we evaluated the bile duct anatomy using the combined findings of T2- and T1-weighted MR cholangiographic images, the diagnostic accuracy increased to 92% (n = 22/24), but the difference was not statistically significant (p > 0.05). MRA showed a diagnostic accuracy of 79% (n = 19/24) for the hepatic arterial anatomy, 100% (n = 24/24) for the portal venous anatomy, and 96% (n = 23/24) for the hepatic venous anatomy., Conclusion: Gadobenate dimeglumine-enhanced MRI allows comprehensive assessment of the biliary and hepatic vascular systems and the hepatic parenchyma and can serve as the sole preoperative imaging test for living liver donor candidates.

Rationale and Objectives: To compare enhancement patterns of gadomer-17 with those of gadopentetate dimeglumine in VX2 carcinomas after irradiation on rabbits., Methods: Twelve rabbits with VX2 carcinoma in the thigh underwent dynamic contrast-enhanced magnetic resonance (MR) imaging with gadopentetate dimeglumine and gadomer-17 at 24-hour intervals before (n = 12), 3 days (group 1, n = 12), 1 month (group 2, n = 8) and 2 months (group 3, n = 4) after 30 Gy irradiation. After taking postirradiation MR images, 4 rabbits were killed for histopathologic examination at each time interval. The enhancement characteristics in MR imaging and morphology of tumor vessels in histopathologic specimen were assessed., Results: After gadopentetate dimeglumine injection, the enhancement characteristics were not different among tumors before and after irradiation (P > 0.05). For gadomer-17, the enhancement ratios decreased after irradiation. The shape of the curves for tumor enhancement before irradiation was significantly different from curves of group 1(P < 0.05). The specimens from group 3 showed sclerosis and wall thickening in arterioles., Conclusions: Dynamic contrast-enhanced MR imaging with a gadomer-17 reveals increased capillary permeability at an early phase after irradiation and chronic obliterating vasculopathy at delayed phase.

Objective: To present the sonographic appearance of hepatocellular carcinoma imaged with the intravenous contrast agent Levovist., Methods: We reviewed our experience using Levovist (Schering AG, Berlin, Germany) for the sonographic diagnosis of hepatocellular carcinoma., Results: Contrast-enhanced sonography with Levovist facilitated detailed evaluation of tumor vascularity in hepatocellular carcinoma., Conclusions: Contrast-enhanced sonography with Levovist enhances the role of sonography in the diagnosis of hepatocellular carcinoma. It provides detailed information about tumor vascularity and the contrast enhancement pattern.

Mucosa-associated lymphoid tissue (MALT) is found in the surface epithelium of the stomach. MALT lymphoma is extranodal lymphoma originating from MALT. In the stomach, a strong association with Helicobacter pylori infection has been demonstrated. Low-grade gastric MALT lymphoma has been reported to have variable features at upper gastrointestinal (UGI) examination. Twenty-two patients with low-grade MALT lymphoma had ulcers (n = 11), fold thickening (n = 7), mucosal nodularity (n = 7), masses (n = 6), or prominent areae gastricae (n = 4) at UGI examination. Six patients with high-grade MALT lymphoma had masses (n = 4), fold thickening (n = 3), ulcers (n = 1), or mucosal nodularity (n = 1) at UGI examination. These findings were similar to those in gastric carcinoma or gastritis. Differentiation of low-grade MALT lymphoma from gastritis or gastric carcinoma was more difficult than differentiation of high-grade MALT lymphoma. Lesions of MALT lymphoma associated with H pylori gastritis were diffuse or multiple in 65% of cases; however, lesions of MALT lymphoma without proved H pylori gastritis were focal or solitary in 80% of cases. Therefore, multiplicity of lesions in MALT lymphoma was closely associated with H pylori infection.

Rationale and Objectives: To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom., Methods: While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve., Results: In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction., Conclusions: Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.

Background: The purpose of this study was to make a quantitative comparison between conventional and harmonic power Doppler (PD) ultrasound (US) in depicting vascularity of hepatocellular carcinoma (HCC)., Methods: Ten nodular HCCs in 10 patients were prospectively examined using a 2-4-MHz convex transducer and a standardized examination protocol. Serial US images were obtained before and 20, 30, 40, 50, 60, 90, 120, 150, 180, 240, and 300 s after intravenous injection of 2 g of contrast agent using conventional and harmonic PD US. The percentage of area with Doppler signal within each HCC nodule (%PDA) was calculated in each image with a PC-based image analysis program, and the results with both US techniques were compared., Results: In the majority of cases, %PDA was greater on conventional PD US than on harmonic PD US. Mean %PDA of 10 HCCs was significantly higher on conventional PD US than on harmonic PD US except at 20 s after injection. The highest values of mean %PDA were 34.9% in conventional PD US and 19.5% in harmonic PD US at 60 s after injection., Conclusion: Area with PD signals within the HCC is smaller and the duration of effective enhancement is shorter in harmonic PD US than in conventional PD US.

Objective: To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed., Materials and Methods: In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range., Results: A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2-3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshold and thus the temporal window was narrow and the optimal area decreased., Conclusion: Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.

To investigate the feasibility of delayed pulse-inversion harmonic imaging (PIHI) with the SH U 508A to improve imaging of hepatic metastases, we evaluated 20 patients with known hepatic metastases. Conventional ultrasound (US) was performed before administration, and PIHI was performed 5 min after a bolus injection of 4 G of microbubble contrast agent (300 mg/mL of SH U 508A). Intense, homogeneous enhancement in the liver parenchyma was seen in all patients on delayed PIHI. In 10 patients (50%), 1 or more focal liver lesions that were not seen on unenhanced imaging were detected on delayed PIHI. When comparing 55 lesions that were seen on both techniques, delayed PIHI was superior to unenhanced imaging in terms of lesion conspicuity and lesion-to-liver contrast (p < 0.001, respectively). Delayed PIHI with SH U 508A can improve conspicuity of hepatic metastases and reveal focal liver lesions that are not detected on unenhanced imaging.

The detection of hepatic lesions in computed tomography (CT) is improved when a contrasting material is administered intravenously, but it depends considerably on how this agent is injected. In this study, we constructed a compartment model for a liver containing a hepato-cellular carcinoma (HCC), and simulated the difference in lesion-to-liver contrast enhancement. Using this model, we simulated the effects of various injection factors on the detectability of a lesion and searched for the optimal injection protocol for detecting tumors in contrast-enhanced dynamic hepatic CTs. We found that the mass injection rate, or k-value (in mg/s), (which is the volume injection rate, in ml/s, multiplied by the contrast agent concentration, in mg/ml) plays a critical role in the injection protocol optimized for tumor detection, and has a unique value for a given body weight independent of the total injection dose.

Purpose: To evaluate contrast agent-enhancement patterns in hepatic hemangiomas, hepatic metastases, and hepatocellular carcinomas (HCCs) at pulse-inversion harmonic ultrasonography (US) with a microbubble contrast agent., Materials and Methods: Twenty hepatic hemangiomas in 20 patients and 41 malignant hepatic tumors in 23 patients (33 metastases and eight HCCs) were evaluated with pulse-inversion harmonic US. US images were obtained before injection and every 10-15 seconds after injection of a 4-g bolus (300 mg/mL) of SH U 508A (a microbubble contrast agent) for 5 minutes. The contrast-enhancement patterns of 61 hepatic lesions were assessed., Results: Of 20 hemangiomas, 19 revealed peripheral enhancement, which was globular in 14 (70%) and rimlike in five (25%), with centripetal fill-in; the remaining one (5%) showed homogeneous enhancement. In 33 metastases, the enhancement was rimlike in 16 (48%), homogeneous in seven (21%), and stippled in two (6%); in the remaining eight metastases (24%), no enhancement was seen. Of eight HCCs, four (50%) showed homogeneous enhancement and the remaining four (50%) showed heterogeneous enhancement. Centripetal fill-in of lesions with intratumoral enhancement was not seen in any malignancy., Conclusion: Pulse-inversion harmonic US with a microbubble contrast agent is potentially useful for the specific diagnosis of hemangiomas that demonstrate characteristic enhancement features.

Objective: We determined the enhancement features of experimentally induced malignant tumors on MR imaging with the use of gadolinium mesoporphyrin, a recently developed MR contrast agent that may be necrosis-specific., Materials and Methods: VX2 carcinoma was inoculated into 24 rabbit thighs. T1-weighted contrast-enhanced MR imaging with IV gadopentetate dimeglumine (2-min delay) and gadolinium mesoporphyrin (20-hr delay) was performed 3-4 days (n = 6), 6-7 days (n = 6), 10-11 days (n = 5), and 13-14 days (n = 7) after the implantation of VX2 carcinoma. All tumors were sectioned along the same plane of MR images, and a detailed MR imaging-histopathologic correlation was performed., Results: Pathologically, areas enhanced with gadolinium mesoporphyrin included necrotic tissue, viable tumor, inflammatory granulation tissue, hemorrhage, and fibrosis. On gadopentetate dimeglumine-enhanced MR images, unenhanced areas of the tumor corresponded with intratumoral necrosis and hemorrhage., Conclusion: Gadolinium mesoporphyrin enhances tumor necrosis on delayed phase MR imaging; however, it is impossible to specifically depict necrosis with gadolinium mesoporphyrin because it also enhances other parts of lesions, including viable tumor.

Purpose: The purpose of this work was to evaluate the effects of contrast medium injection parameters on aortic, portal vein, and hepatic enhancement at spiral CT and to assess optimal injection protocol for hepatic CT., Method: Ten 15 kg dogs underwent single level dynamic CT through the hepatic hilum at 5 s intervals just after the injection of contrast medium for 3 min. With use of different volumes (1, 2, and 3 ml/kg), injection rates (0.5, 1, and 2 ml/s), and concentrations (150, 200, and 300 mg/ml), a total of 270 spiral CT scans were performed. In each scan, time-attenuation curves of aorta, portal vein, and liver were obtained. The degree of maximum contrast enhancement (Imax), time to maximum enhancement (Tmax), and time to equilibrium phase (Teq) for to each injection protocol were analyzed., Results: Alterations in contrast material volume, injection rate, and concentration had significant impact on contrast enhancement of the liver. With increasing volume of contrast medium, Imax, Tmax, and Teq of aorta, portal vein, and liver increased (p < 0.005). With increasing rate of injection, on the other hand, Imax of aorta and liver increased (p < 0.05), but Tmax and Teq decreased (p < 0.005). Change of concentration of contrast medium had a significant effect on Imax of vessels (p < 0.05)., Conclusion: Maximum contrast enhancement of liver and vessels was influenced mainly by injection volume of contrast medium and the time to peak enhancement by injection rate of contrast medium. Under given amounts of contrast medium, therefore, the strategy of increasing volume by dilution and faster injection might give better Imax values without penalty for the duration of an optimal temporal window (Tmax and Teq).

Background: To describe the radiologic findings of nonpolypoid gastric adenomas and to correlate them with pathologic findings., Methods: During a 9-year period, we reviewed 49 pure gastric adenomas in 43 patients with positive radiologic findings. Of these adenomas, seven with atypical polypoid appearance were retrospectively included in the study. We reviewed these findings with double-contrast barium study and correlated them with the pathologic findings., Results: Of seven nonpolypoid adenomas, four were depressed and three were flat at pathologic examination. All were diagnosed as early gastric carcinoma (five as type IIc, one as type IIb, one as type IIa + IIc) in upper gastrointestinal series. Three were located in the gastric angle, two in the lower body, and two in the antrum. Size ranged from 10 mm to approximately 25 mm (mean = 15 mm). Six lesions had nodular surface and five had convergency of the mucosal folds. A shallow depressed area was seen in six lesions., Conclusions: A considerable proportion of gastric adenomas presents as a depressed or flat lesion on double-contrast barium study because of histologic characteristics of decreased subjacent mucosa. Because the nonpolypoid adenoma has a greater potentional for malignancy, more precaution is needed during the follow-up of this uncommon lesion.

Purpose: To compare contrast material-enhanced harmonic power Doppler ultrasonography (US) with conventional power Doppler US in depicting the vascularity of hepatocellular carcinoma (HCC)., Materials and Methods: Twenty patients with nodular HCCs (2.6-13.2 cm in diameter; mean diameter, 4.8 cm) were prospectively examined with both conventional and harmonic power Doppler US. US was performed with a 2-4-MHz curved linear-array transducer according to a standard examination protocol (1,000-Hz pulse repetition frequency, medium wall filter, and power gain of 55%-84% for conventional power Doppler US; 700-Hz pulse repetition frequency, low wall filter, and power gain of 95%-98% for harmonic power Doppler US). Serial, dynamic scans were obtained before intravenous injection of the contrast agent (SH U 508A) and at 30, 60, 90, 120, 180, 240, and 300 seconds after injection with both techniques., Results: The number of intratumoral power Doppler US signals was similar with both techniques at 30-90 seconds after contrast agent injection; however, after 90 seconds, conventional power Doppler US depicted significantly more signals than did harmonic power Doppler US. Harmonic power Doppler US was superior to conventional power Doppler US in terms of power Doppler artifacts such as "blooming" or motion-related artifacts., Conclusion: Although the effective enhancement duration is relatively short compared with that for conventional power Doppler US, contrast-enhanced harmonic power Doppler US can be effective in evaluating the vascularity of HCCs because of the advantage of fewer power Doppler artifacts.

Background: To evaluate clinical usefulness of oral contrast agents (gadopentetate dimeglumine and water) and to assess proper magnetic resonance (MR) imaging in evaluating advanced gastric cancer (AGC) by comparing different MR imaging techniques., Methods: Fifteen patients with AGC were imaged with a 1.0-T MR imager and body-array coil. All patients underwent surgery or laparascopic biopsy. Fast low-angle shot (FLASH), half-Fourier single-shot turbo spin-echo (HASTE), and true fast imaging with steady-state precession time (FISP) images were obtained after ingestion of 900 mL tap water in each patient, followed by postcontrast FLASH images after additional ingestion of gadopentetate dimeglumine (Gd-DTPA). Qualitative analysis including T-staging of AGC and scoring of imaging quality and quantitative analysis were performed prospectively., Results: In image quality and diagnostic accuracy of T-staging, FLASH imaging showed results slightly superior to those of other imaging modalities, and there was no great difference between using water and Gd-DTPA as an oral contrast agent. As for cancer-to-gastric lumen contrast-to-noise ratio (CNR), HASTE and true FISP imaging were superior to FLASH imaging with Gd-DTPA (p < 0.0001). In cancer-to-pancreas CNR, FLASH imaging without Gd-DTPA showed the best result., Conclusions: The use of Gd-DTPA as a positive contrast agent may not be imperative, and T1-weighted FLASH imaging in combination with true FISP imaging with ingestion of tap water can be very useful in evaluating AGC with MR imaging.

Power Doppler ultrasonography using a sonographic contrast agent (Levovist) was evaluated in 20 patients with hepatic hemangiomas with a 2-4 MHz convex transducer according to a standardized examination protocol (pulse repetition frequency, 1000 Hz; medium wall filter; power Doppler gain, 50 to 85%). Enhancement patterns were assessed and were compared with those on dynamic magnetic resonance imaging (n = 11) or computed tomography (n = 9). The most common enhancement pattern was dotlike or linear enhancement located predominantly at the periphery of the tumor (15 cases, 75%). Diffuse homogeneous enhancement was seen in one case (5%). No definite contrast enhancement was evident in four cases (20%). The enhanced area on ultrasonograms was smaller than that on dynamic MR images or CT scans in 18 cases (90%). A transient centripetal fill-in pattern was identified in six cases (30%). Persistent enhancement until 300 s was not seen in any case. Therefore, specific diagnosis of hemangioma with power Doppler ultrasonography and contrast agent may not be possible.

The objective of the present study was to evaluate contrast-enhancement patterns of hepatic hemangioma according to size during hepatic arterial (30-s delay) and portal venous (65-s delay) phases of spiral computed tomography (CT). During a 10-month-period, 73 patients with 118 hemangiomas underwent two-phase spiral CT examination. The enhancement patterns of tumors were divided into four types based on the attenuation of surrounding liver parenchyma: peripherally nodular high, uniform high, iso, and low. The diameter of the tumors were <10 mm (n = 39), 11-20 mm (n = 33), and >21 mm (n = 46). Overall, the most common enhancement patterns of hemangioma were peripherally nodular high (66/118, 55. 9%) during the arterial and portal venous phases. The second most common contrast-enhancement patterns of hemangioma were uniform high (15/118, 12.7%) during the arterial and portal venous phases. In tumors smaller than 20 mm, 11 (9.3%) had low-low attenuation and two (1.7%) had iso-low attenuation during the arterial and portal venous phases, respectively. In conclusion, at two-phase spiral CT, the most common contrast-enhancement patterns of hemangioma are peripherally nodular high and/or uniform high during the arterial and portal venous phases. However, hemangiomas smaller than 2 cm may have atypical enhancing patterns including low and iso-attenuation.

Purpose: To investigate the value of contrast material-enhanced power Doppler ultrasonography (US) in the demonstration and characterization of tumor vascularity in hepatocellular carcinoma (HCC)., Materials and Methods: Twenty patients with HCC were prospectively evaluated with power Doppler US before and after injection of the contrast agent SH U 508 A. The grade and pattern of tumor vascularity at power Doppler US were analyzed, along with the degree of tumor staining at angiography., Results: Intra- and peritumoral flow signals were detected in 19 HCCs (95%) at unenhanced power Doppler US. After injection of contrast agent, flow signals increased in 19 lesions (95%). At contrast-enhanced power Doppler US, two tumors demonstrated grade 1 vascularity; four, grade 2; three, grade 3; and 11, grade 4. At angiography, two tumors demonstrated grade 1 staining; four, grade 2; eight, grade 3; and six, grade 4. The correlation between vascularity grades at contrast-enhanced power Doppler US and at angiography was statistically significant (P < .0001). Seventeen HCCs (85%) showed the intratumoral or basket pattern of vascularity at unenhanced power Doppler US; after injection of contrast material, 15 HCCs (75%) showed the mixed pattern., Conclusion: Contrast-enhanced power Doppler US is superior to unenhanced power Doppler US in the demonstration and characterization of tumor vascularity in HCC.