[en] Second shot arterial phase (SSAP) imaging is an additional arterial phase image obtained by re-injecting a small amount of contrast medium after routine dynamic imaging in gadoxetic acid-enhanced liver MRI. We aimed to evaluate the feasibility and additional value of a SSAP image in gadoxetic acid-enhanced liver MRI. One hundred seventy-two patients who underwent SSAP imaging after re-injection of 4 mL of contrast material after routine dynamic imaging (original) in gadoxetic acid-enhanced liver MRIs were included. Motion artifacts on arterial phase (AP) images were rated using a 5-point scale and were compared between the original AP images and SSAP images. We evaluated visual detection rates of arterial hypervascularity on the original AP and SSAP images and their subtraction images in patients with hypervascular hepatocellular carcinoma (HCC). The motion artifact of the SSAP images was significantly lower than that of the original AP images (mean score, 1.76 vs 2.06; p < 0.001). In particular, motion artifacts reduced significantly in the SSAP images of patients with substantial motion artifacts in their original AP images (2.28 vs 3.28; p < 0.001). Among the 30 HCC lesions showing hypervascularity on original AP images, only four (4/30, 13.3%) appeared hyperintense on SSAP images. However, subtraction images of SSAP clearly demonstrated arterial hypervascularity in all HCCs. SSAP images showed significantly fewer motion artifacts than the original AP images. Subtraction images of SSAP maintained the detectability of arterial hypervascularity, although SSAP images showed poor visual detection of arterial hypervascularity of HCC.

[en] To assess the differential points between benign and malignant thyroid nodules, we retrospectively analysed the gray-scale and color Doppler ultrasovograms, radioisotope(RI) scans, and thyroid function tests of lO4 cases. The pathology of the lesion was confirmed as benign in 80 cases and malignant in 24 case, either at operation orby fine needle aspiration biopsy. Gray-scale ultrasonographic findings were analysed in terms of lymphadenopathy,size, and multiplicity. Color Doppler ultrasonography was performed in 40 case, and color singals were graded from type 0 to type III according to color flow distributions. There were no statistically significant differences inperipheral halo, size, multiplicity, color Doppler ultrasonograms, and findings at RI scan and thyriod functiontest between benign and malignant nodules(Chi-square test : P>0.05). However, internal punctate calcification,solid and hypoechoic pattern, cervical lymphadenopathy, irregular and illdefined outer margin, male gender weremore common in malignant thyroid nodules, while smooth and well-defined outer margin, complex echogenicity weremore common in benign nodules(P<0.05). Although color Doppler examination did not contribute to the differentialdiagnosis of benign and malignant nodules, complete halo in grat-scale ultrasonographt and color signal type II (prominent color flow at the periphery of the nodules; color 'halo' sihn) showed statistically significantcorrelation. In conclusion, gray-scale ultrasonography is a useful imaging modality for differential diagnosis of thyroid nodules, and further studies may be requires to clarify the availability of color Doppler ultrasonography

[en] Toxocariasis, a parasitic infection, causes hyper eosinophilia resulting in radiological presentation of eosinophilic infiltrations in the involved organs. In the abdomen, toxocariasis has been reported to manifest as infiltrations in the liver or in the gastrointestinal tract, but it is known to be uncommon to manifest as multiple lymphadenopathy. There have been two case reports of toxocariasis presenting as generalized lymphadenopathy in the chest, neck and inguinal regions. To the best of our knowledge, generalized conglomerated lymphadenopathy occurring mostly in the abdomen from toxocariasis has not been published in the English literature. Herein, we report a rare case of toxocariasis presenting as multiple conglomerated lymphadenopathy mimicking lymphoma on CT

[en] To evaluate the feasibility of simulated abbreviated MRI (AMRI) with second shot arterial phase (SSAP) for HCC surveillance and diagnosis. A total of 129 consecutive patients (age, 58.8 ± 11.4 years; male, 71.3%) underwent gadoxetic acid-enhanced MRI using a modified injection protocol for HCC evaluation from July 2017 to February 2018. The modified injection protocol consisted of routine dynamic imaging (6 mL) and SSAP imaging (4 mL). Two radiologists independently reviewed two AMRI sets: AMRI without SSAP (surveillance set) and AMRI with SSAP (diagnosis set). A modified version of the Liver Imaging Reporting and Data System (LI-RADS) for the diagnosis set was devised by referring to contrast-enhanced ultrasound LI-RADS. Sixty-seven patients with HCC and 62 patients without HCC were included. In the surveillance set, sensitivity and specificity for the detection of patients with HCC were 95.5% and 96.8%, and 94.0% and 96.8% in reviewers 1 and 2, respectively. In the diagnosis set, the scores of most HCCs (76/78, 97.4%) were consistent between LI-RADS of full-protocol and modified LI-RADS of AMRI with SSAP protocol. When the HCC surveillance and diagnosis strategy was changed from strategy 1 (AMRI without SSAP) to strategy 2 (AMRI with SSAP), the recall rate significantly decreased from 52.7 to 3.9% (p < 0.001). The modified LI-RADS score of the AMRI with SSAP protocol showed high agreement with the LI-RADS score of the full protocol. The HCC surveillance and diagnosis strategy using the AMRI with SSAP protocol reduced the recall rate. These results may enable to diagnose HCC simultaneously with surveillance. A modified version of LI-RADS was devised for the diagnostic algorithm using AMRI with the second shot arterial phase (SSAP) by referring to CEUS LI-RADS. The modified LI-RADS scores using AMRI with SSAP showed a high concordance rate with the conventional LI-RADS score using full-protocol MRI. The recall rate significantly decreased when the HCC surveillance and diagnosis strategy was changed from strategy 1 (AMRI without SSAP; surveillance then recall test) to strategy 2 (AMRI with SSAP; simultaneous surveillance and diagnosis).

[en] To evaluate the sensitivity of computer-aided detection(CAD) and dual-energy software('Lung PBV', 'Lung Vessels') for detecting peripheral pulmonary embolism(PE). Between Jan-2007 and Jan-2008, 309 patients underwent dual-energy CT angiography(DECTA) for the evaluation of suspected PE. Among them, 37 patients were retrospectively selected; 21 with PE at segmental-or-below levels and 16 without PE according to clinical reports. A standard computer assisted detection (CAD) package and two new types of software('Lung PBV', 'Lung Vessels') were applied on a dedicated workstation. This resulted in four alternative tests for detecting PE: DECTA alone and DECTA with CAD, 'Lung Vessels' and 'Lung PBV'. Two radiologists independently read all cases at different reading sessions. Two thoracic radiologists set the reference standard by combining all information from DECTA and software. The sensitivity of detection for all, segmental and subsegmental-or-below PE were assessed. The reference standard contained 136 PE(segmental 65, subsegmental-or-below 71). With DECTA alone, the sensitivity of detection for all, segmental and subsegmental-or-below pulmonary arteries was 54.5%/73.7%/34.4%; DECTA with CAD, 57.8%/76.8%/37.9%; DECTA with 'Lung PBV', 61.1%/79.9%/41.4%; DECTA with 'Lung Vessels', 64.0%/78.3%/48.5% respectively. The use of CAD, Lung Vessels and Lung PBV shows improved capability to detect peripheral PE. (orig.)

[en] Objective: To evaluate the value of the fade-out sign in the diagnosis of fatty liver (FL) on hepatic ultrasound (US). Methods: We evaluated 127 patients who underwent hepatic US, including 70 patients with FL and 57 normal control subjects. US images were qualitatively evaluated for the presence of the fade-out sign. This sign was considered present if there was a dark band on the deep portion of the liver on the harmonic image when compound sonography (CS) was converted to tissue harmonic CS mode. The degrees of FL were classified into mild, moderate, and severe. The distribution of lengths of dark bands in three groups was examined, and a multiple comparison of the average dark band length was carried out using one-way ANOVA. Results: The fade-out sign was seen in 55 of 70 FL patients (78.6%) compared to 3 of 57 control subjects (5.3%) (p < 0.001). The sensitivity, specificity, accuracy, and positive predictive value of the fade-out sign for the US diagnosis of FL were 78%, 94%, 85.8%, and 94.8%, respectively. Among the 70 FL, there were 28 mild FL (mean length of dark band; 8.3 mm ± 8.2), 31 moderate FL (mean; 28 mm ± 6.3), and 11 severe FL (mean; 51 mm ± 8.3). There were significant differences in band length according to severity (p < 0.01). Conclusion: The fade-out sign on hepatic harmonic US was frequently present in FL. As fat infiltration increased, the fade-out sign lengthened. The fade-out sign offers a specific and new sign of FL.

[en] To compare the diffusion parameters of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) between the ''reflux'' and the ''non-reflux'' kidneys, and to evaluate the feasibility of using IVIM DWI to predict vesicoureteral reflux (VUR) in children with a urinary tract infection (UTI). Eighty-three kidneys from 57 pediatric patients with a UTI were classified into ''reflux'' and ''non-reflux'' groups according to voiding cystourethrography (VCUG) results. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (PF) were measured and compared in the renal pelvis of both groups. Four indices (D*/ADC, PF/ADC, D*/D, and PF/D) were calculated and receiver operating characteristic (ROC) curve analyses were performed. VURs were detected on VCUG in 21 kidneys. PF and D* were significantly higher in the ''reflux'' group than in the ''non-reflux'' group. The indices were all significantly higher. The PF/D index showed the best diagnostic performance in predicting VUR in children with UTI (A_z = 0.864). PF and D* were significantly higher in the ''reflux'' kidney than in the ''non-reflux'' kidney. Our new index (PF/D) could prove useful for predicting VUR. (orig.)

[en] The occurrence of incidentally detected pancreatic cystic lesions (PCLs) is continuously increasing. Radiologic examinations including computed tomography and magnetic resonance imaging with magnetic resonance cholangiopancreatography have been widely used as the main diagnostic and surveillance methods for patients with incidental PCLs. Although most incidentally detected PCLs are considered benign, they have the potential to become malignant. Currently, we have several guidelines for the management of incidental PCLs. However, there is still debate over proper management, in terms of accurate diagnosis, optimal follow-up interval, and imaging tools. Because imaging studies play a crucial role in the management of incidental PCLs, the 2017 consensus recommendations of the Korean Society of Abdominal Radiology for the diagnosis and surveillance of incidental PCLs approved 11 out of 16 recommendations. Although several challenges remain in terms of optimization and standardization, these consensus recommendations might serve as useful tools to provide a more standardized approach and to optimize care of patients with incidental PCLs

[en] Purpose: To validate the diagnostic performance of quadruple phase low tube voltage liver CT through the comparison with Gd-EOB-DTPA enhanced liver MRI for the detection of HCC. Materials and methods: Non-obese patients (38 men, eight women) with 68 HCCs underwent quadruple-phase CT at 16 MDCT (using low tube voltage, 80 kVp; moderately high tube current, 280 mAs) and Gd-EOB-DTPA-enhanced 3 T MRI. Three observers independently and randomly reviewed the CT and MR images on a tumor-by-tumor basis. The diagnostic accuracy of these techniques for detecting HCC was assessed using alternative free-response receiver operating characteristic analysis. Sensitivity and positive predictive values were evaluated. The mean effective doses for the low dose CT were also evaluated. Results: The areas under the ROC curves were 0.963, 0.959, and 0.941 for low dose CT and 0.981, 0.982, and 0.976 for MRI. Differences in Az of the two techniques for each observer were not statistically significant (P > .05). Differences in sensitivity and positive predictive values between the two techniques for each observer were not also statistically significant: sensitivity (86.8%, 82.4%, 85.3% for CT and 95.6%, 94.1%, 91.2% for MRI) and positive predictive values (92.2%, 90.3%, 89.2% for CT and 92.9%, 92.8%, 92.5% for MRI). Six HCCs (8.8%) in five patients were observed only on hepatobiliary phase of MRI, and all were smaller than 1.5 cm. The mean effective dose for CT was approximately 10.2 mSv. Conclusions: Quadruple-phase low-dose liver CT (80 kVp, 280 mAs) had relatively good diagnostic performance for detecting HCC in non-obese patients. Because no significant difference was observed between low-dose CT and MRI, the use of low-dose liver CT can be justified based on its reduced radiation effects.

[en] Highlights: • HCC_para shows more frequent initial compact lipiodol uptake after TACE than HCC_def. • HCC_para demonstrates less frequent early local recurrence after TACE. • HCC_para has larger mean size, lower AER, and more frequent capsule appearance. - Abstract: Purpose: To compare the response to transcatheter arterial chemoembolization (TACE) between hepatocellular carcinoma (HCC) with paradoxical uptake on the hepatobiliary phase (HBP) (HCC_para) and HCC with defect on the HBP (HCC_def), and to identify some imaging features that can differentiate between two groups. Materials and methods: Ninety-three HCCs from 54 patients who underwent gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) prior to TACE were included. HCCs were classified into two groups according to the signal intensity (SI) on the HBP: HCC_para and HCC_def. Using post-TACE computed tomography (CT) as a reference standard, initial compact lipiodol uptake was assessed and compared between groups. The arterial enhancement ratio (AER), SI ratios of the arterial phase and HBP, and presence of the capsule appearance were compared between groups. After initial response, local tumor recurrence within 6 and 18 months was evaluated based on follow-up CT or MRI. Results: Fifteen HCC_para and 78 HCC_def were included. Compared to HCC_def, HCC_para showed more frequent initial compact lipiodol uptake (p = 0.009), larger mean size (p = 0.019), lower AER (p = 0.005), higher SI ratio of the HBP (p < 0.0001), and more frequent capsule appearance (p < 0.0001). Local tumor recurrence rate within 6 months was also significantly lower in HCC_para than in HCC_def (p = 0.008). Conclusion: Despite larger size and lower AER, HCC_para showed more frequent initial compact lipiodol uptake and lower early local recurrence rate after TACE than did HCC_def.