Fluorescein staining of chloroplast starch granules in living plants.

Chloroplast starch granules (cpSGs) store energy harvested through photosynthesis in plants, and cpSG dynamics have important roles in plant energy metabolism and stress responses. To date, cpSGs have been visualized using several methods, such as iodine staining; however, no method can be used to specifically visualize cpSGs in living cells from various plant species. Here, we report a simple method to visualize cpSGs in living plant cells in various species by staining with fluorescein, a commonly used fluorescent dye. We show that fluorescein is taken up into chloroplasts and interacts with cpSGs similarly to iodine. Fluorescein also interacts with refined starch in vitro. Using a fluorescein derivative for ultrabright cpSG imaging, we produced high-quality 3D reconstructions of cpSGs and evaluated their accumulation in multiple plant species. As fluorescein is well known and readily purchasable, our fluorescein-based staining method should contribute to all research regarding starch.

Magnetic resonance imaging-based risk factors of hepatocellular carcinoma after direct-acting antiviral therapy: A multicenter observational study.

AIM: To determine risk factors associated with hepatocellular carcinoma (HCC) development following direct-acting antiviral (DAA) therapy. METHODS: We enrolled patients with chronic hepatitis C who underwent direct-acting antiviral therapy and achieved sustained virologic response at 12 weeks between 2012 and 2018. Subsequently, patients were followed up. The primary endpoint was the development of HCC or the date of the last follow up when the absence of HCC was confirmed. Uni- and multivariate Cox proportional hazards models were used to identify factors contributing to HCC development, including gadoxetic acid-enhanced magnetic resonance imaging findings. The cumulative incidence rates of HCC development were calculated using the Kaplan-Meier method, and differences between groups were assessed using the log-rank test. RESULTS: The final study cohort comprised 482 patients (median age 70.5 years; 242 men). The median follow-up period was 36.8 months. Among 482 patients, 96 developed HCC (19.9%). The 1-, 3-, and 5-year cumulative rates of HCC development were 4.9%, 18.6%, and 30.5%, respectively. Multivariate analysis revealed that age, male sex, history of HCC, and hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were independent risk factors significantly associated with HCC development (p < 0.001-0.04). The highest risk group included patients with both a history of HCC and the presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement (the 1- and 3-year cumulative HCC development rates were 14.2% and 62.2%, respectively). CONCLUSION: History of HCC and presence of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement were strong risk factors for HCC development following direct-acting antiviral therapy.

Association of the lung immune prognostic index with the survival of patients with idiopathic interstitial pneumonias.

BACKGROUND AND OBJECTIVE: The lung immune prognostic index (LIPI), a simple index calculated from the blood lactate dehydrogenase level and derived neutrophil-to-lymphocyte ratio, is thought to be associated with host immune status. However, the utility of LIPI in patients with idiopathic interstitial pneumonias (IIPs) is unknown. METHODS: In this multicentre, retrospective, observational study, an association between LIPI and the survival of patients with IIPs was evaluated. RESULTS: Exploratory and validation cohorts consisting of 460 and 414 patients with IIPs, respectively, were included (159 and 159 patients had idiopathic pulmonary fibrosis [IPF], and 301 and 255 had non-IPF, respectively). In the exploratory cohort, patients with IPF and a low LIPI had significantly better survival than those with a high LIPI (median of 5.6 years vs. 3.9 years, p = 0.016). The predictive ability of LIPI for the survival of patients with IPF was validated in the validation cohort (median of 8.5 years vs. 4.4 years, p = 0.003). In a multivariate Cox proportional hazard analysis, LIPI was selected as an independent predictive factor for the survival of IPF patients. There was no significant association between LIPI and survival of non-IPF patients in the exploratory and validation cohorts. CONCLUSION: The LIPI was a predictive factor for the survival of patients with IPF and could aid the management of IPF.

A predictive model for acute exacerbation of idiopathic interstitial pneumonias.

BACKGROUND: Acute exacerbation of idiopathic interstitial pneumonias (AE-IIPs) induces permanent pulmonary dysfunction and is potentially lethal. The unpredictable occurrence of AE-IIPs remains an important clinical issue in the management of IIPs. METHODS: In this multicentre, retrospective, observational study, a predictive score for AE-IIPs was designed using clinical factors based on multivariate Fine-Gray analysis in patients with IIPs. RESULTS: Based on multivariate Fine-Gray analysis in an exploratory cohort of 487 patients with IIPs, the predictive score for AE-IIPs was determined as follows: 1 point each was added for honeycombing on high-resolution computed tomography (H), age >75 years (A) and lactate dehydrogenase level >222 U·L-1 (L); the total score ranged from 0 to 3 (HAL score). The HAL score discriminated the risk of AE-IIPs with a C-index of 0.62 (95% CI 0.56-0.67); this discrimination was verified in a validation cohort of 402 patients with IIPs with a C-index of 0.67 (95% CI 0.60-0.73). In a combined cohort, the estimated cumulative risks for AE-IIPs at 1, 2, 3, 5 and 10 years were 1.9%, 3.5%, 5.1%, 7.7% and 12.9%, respectively, in the total score 0 group; 4.7%, 8.3%, 12.0%, 17.7% and 28.4%, respectively, in the total score 1 group; and 8.0%, 14.2%, 19.7%, 28.7% and 43.0%, respectively, in the total score ≥2 group. Subgroup analysis revealed that the HAL score was applicable to patients with and without idiopathic pulmonary fibrosis. CONCLUSIONS: The HAL score discriminated the risk of AE-IIPs and could aid in the management of IIPs.

Diagnostic value of heart-to-mediastinum ratio in 99mTc-pyrophospate SPECT/CT for transthyretin cardiac amyloidosis.

BACKGROUND: In transthyretin cardiac amyloidosis (ATTR-CA), 99mTc-pyrophosphate myocardial scintigraphy (99mTc-PYP) is a diagnostic tool that utilizes visual and quantitative evaluation. However, false positive cases can occur because of tracer accumulation in the blood. We investigated the effectiveness of the heart-to-mediastinum (H/M) ratio of 99mTc-PYP in ATTR-CA diagnosis. METHODS: We retrospectively included 164 patients who underwent 99mTc-PYP single-photon emission computed tomography/computed tomography between March 2019 and January 2022. The diagnostic accuracy of ATTR-CA was examined by the heart-to-contralateral lung (H/CL) and H/M ratio calculated at 3 hours post-tracer administration. RESULTS: After the exclusion of patients who did not undergo endomyocardial biopsy, 30 patients (15 each with ATTR-CA and without ATTR-CA) were included. The receiver operating characteristic curve used to distinguish ATTR-CA from non-ATTR-CA patients revealed an area under the curve of 0.986 and 0.943, respectively. A H/M ratio of > 1.41 identified ATTR-CA patients with a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100, 93.3, 93.3, and 100%, respectively. Conversely, an H/CL ratio of > 1.3 identified ATTR-CA patients with 100% sensitivity, 40.0% specificity, 62.5% PPV, and 100% NPV. CONCLUSION: The H/M ratio obtained at 3 hours post-injection has the potential to be a novel indicator for ATTR-CA.

MRI-based radiomics analysis for differentiating phyllodes tumors of the breast from fibroadenomas.

OBJECTIVES: To evaluate the diagnostic performance of MRI-based radiomics model for differentiating phyllodes tumors of the breast from fibroadenomas. METHODS: This retrospective study included 88 patients (32 with phyllodes tumors and 56 with fibroadenomas) who underwent MRI. Radiomic features were extracted from T2-weighted image, pre-contrast T1-weighted image, and the first-phase and late-phase dynamic contrast-enhanced MRIs. To create stable machine learning models and balanced classes, data augmentation was performed. A least absolute shrinkage and selection operator (LASSO) regression was performed to select features and build the radiomics model. A radiological model was constructed from conventional MRI features evaluated by radiologists. A combined model was constructed using both radiomics features and radiological features. Machine learning classifications were done using support vector machine, extreme gradient boosting, and random forest. The area under the receiver operating characteristic (ROC) curve (AUC) was computed to assess the performance of each model. RESULTS: Among 1070 features, the LASSO logistic regression selected 35 features. Among three machine learning classifiers, support vector machine had the best performance. Compared to the radiological model (AUC: 0.77 ± 0.11), the radiomics model (AUC: 0.96 ± 0.04) and combined model (0.97 ± 0.03) had significantly improved AUC values (both p < 0.01) in the validation set. The combined model had a relatively higher AUC than that of the radiomics model in the validation set, but this was not significantly different (p = 0.391). CONCLUSIONS: Radiomics analysis based on MRI showed promise for discriminating phyllodes tumors from fibroadenomas. KEY POINTS: • The radiomics model and the combined model were superior to the radiological model for differentiating phyllodes tumors from fibroadenomas. • The SVM classifier performed best in the current study. • MRI-based radiomics model could help accurately differentiate phyllodes tumors from fibroadenomas.

Distinction Between Hepatocellular Carcinoma and Hypervascular Liver Metastases in Non-cirrhotic Patients Using Gadoxetate Disodium-Enhanced Magnetic Resonance Imaging.

Purpose: This study aims to identify the hallmarks of gadoxetate disodium-enhanced magnetic resonance imaging distinguishing hepatocellular carcinoma (HCC) from hypervascular liver metastases (HLMs). Methods: Between January 2008 and October 2020, among patients who underwent gadoxetate disodium-enhanced MRI, those who met the following criteria were retrospectively included: without chronic hepatitis or liver stiffness ≤ 2.5 kPa on magnetic resonance elastography or F0/F1 on pathological assessment. Two blinded radiologists reviewed the imaging findings to judge the presence or absence of the enhancing capsule, nonperipheral washout, corona enhancement, hypointensity in the transitional/hepatobiliary phase (HBP), hyperintensity on T2-weighted/diffusion-weighted imaging (DWI), mosaic architecture, and blood products/fat in mass. The lesion-to-liver signal intensity ratios in HBP and DWI were also calculated. Univariate and multivariate analyses were performed to identify the imaging hallmarks distinguishing HCC from HLM. Interobserver agreement was calculated using kappa values and intraclass correlation coefficients (ICCs). Results: The final study cohort comprised 72 lesions in 44 patients (mean age, 65.0±11.9 years). Univariate analysis revealed higher frequencies of the following features in HCC than in HLM (P < .10): nonperipheral washout, corona enhancement, transitional phase hypointensity, mosaic architecture, and fat in mass (P = .002-.073). Multivariate analysis revealed that nonperipheral washout and mosaic architecture favored the diagnosis of HCC over that of HLM with odds ratios of 7.66 and 14.6, respectively (P = .038 and .029, respectively). The interobserver agreement for each item was moderate or substantial (kappa or ICC = .447-.792). Conclusion: Peripheral washout and mosaic architecture may be reliable imaging hallmarks for distinguishing HCC from HLM.

CNN color-coded difference maps accurately display longitudinal changes in liver MRI-PDFF.

OBJECTIVES: To assess the feasibility of a CNN-based liver registration algorithm to generate difference maps for visual display of spatiotemporal changes in liver PDFF, without needing manual annotations. METHODS: This retrospective exploratory study included 25 patients with suspected or confirmed NAFLD, who underwent PDFF-MRI at two time points at our institution. PDFF difference maps were generated by applying a CNN-based liver registration algorithm, then subtracting follow-up from baseline PDFF maps. The difference maps were post-processed by smoothing (5 cm2 round kernel) and applying a categorical color scale. Two fellowship-trained abdominal radiologists and one radiology resident independently reviewed difference maps to visually determine segmental PDFF change. Their visual assessment was compared with manual ROI-based measurements of each Couinaud segment and whole liver PDFF using intraclass correlation (ICC) and Bland-Altman analysis. Inter-reader agreement for visual assessment was calculated (ICC). RESULTS: The mean patient age was 49 years (12 males). Baseline and follow-up PDFF ranged from 2.0 to 35.3% and 3.5 to 32.0%, respectively. PDFF changes ranged from - 20.4 to 14.1%. ICCs against the manual reference exceeded 0.95 for each reader, except for segment 2 (2 readers ICC = 0.86-0.91) and segment 4a (reader 3 ICC = 0.94). Bland-Altman limits of agreement were within 5% across all three readers. Inter-reader agreement for visually assessed PDFF change (whole liver and segmental) was excellent (ICCs > 0.96), except for segment 2 (ICC = 0.93). CONCLUSIONS: Visual assessment of liver segmental PDFF changes using a CNN-generated difference map strongly agreed with manual estimates performed by an expert reader and yielded high inter-reader agreement. KEY POINTS: • Visual assessment of longitudinal changes in quantitative liver MRI can be performed using a CNN-generated difference map and yields strong agreement with manual estimates performed by expert readers.

Multi-arterial phase MRI depicts inconsistent arterial phase hyperenhancement (APHE) subtypes in liver observations of patients at risk for hepatocellular carcinoma.

OBJECTIVES: According to LI-RADS, a major discriminating feature between hepatocellular carcinoma (HCC) and non-HCC malignancies is the subtype of arterial phase hyperenhancement (APHE). The aim of this study was to investigate whether APHE subtypes are consistent across multi-arterial phase (mHAP) MRI acquisitions while evaluating reader agreement. Secondarily, we investigated factors that may affect reader agreement for APHE subtype. METHODS: In this retrospective study, consecutive patients with liver cirrhosis and focal observations who underwent mHAP were included. Five radiologists reviewed MR images in 2 reading sessions. In reading session 1, individual AP series were reviewed and scored for presence of APHE and subtype. In reading session 2, readers scored observations' major and ancillary features and LI-RADS category in the complete MRI examination. Reader agreement was calculated using Fleiss' kappa for binary outcomes and Kendall's coefficient of concordance for LI-RADS categories. Univariate mixed effects logistic regressions were performed to investigate factors affecting agreement. RESULTS: In total, 61 patients with 77 focal observations were analyzed. Of observations unanimously scored as having APHE, 27.7% showed both rim and nonrim subtypes on mHAP. Inter-reader agreement for APHE subtype ranged from 0.49 (95% CI: 0.33, 0.64) to 0.57 (95% CI: 0.40, 0.74) between reading sessions. Observation size had a trend level effect on rim APHE agreement (p = 0.052). CONCLUSION: Approximately 1/3 of observations demonstrated inconsistent APHE subtype during mHAP acquisition. Small lesions were particularly challenging. Further guidance on APHE subtype classification, especially when applied to mHAP, could be a focus of LI-RADS refinement. KEY POINTS: • In a cohort of patients at risk for HCC, 28% of the observations showed inconsistent arterial phase hyperenhancement (APHE) subtypes (rim and nonrim) on multi-arterial phase imaging according to the majority score of 5 independent readers. • Inconsistent APHE subtypes may challenge reliable imaging diagnosis, i.e., LI-RADS categorization, of focal liver observations in patients at risk for HCC.

Preoperative CT Findings for Predicting Acute Exacerbation of Interstitial Pneumonia After Lung Cancer Surgery: A Multicenter Case-Control Study.

BACKGROUND. Acute exacerbation (AE) is a life-threatening complication of inter-stitial pneumonia (IP). Thoracic surgery may trigger AE. OBJECTIVE. The purpose of this study is to explore the role of preoperative CT findings in predicting postoperative AE in patients with IP and lung cancer. METHODS. This retrospective case-control study included patients from 22 institutions who had IP and underwent thoracic surgery for lung cancer. AE was diagnosed on the basis of symptoms and imaging findings noted within 30 days after surgery and the absence of alternate causes. For each patient with AE, two control patients without AE were identified. After exclusions, the study included 92 patients (78 men and 14 women; 31 with AE [the AE group] and 61 without AE [the no-AE group]; mean age, 72 years). Two radiologists independently reviewed preoperative thin-slice CT examinations for pulmonary findings and resolved differences by consensus. The AE and no-AE groups were compared using the Fisher exact and Mann-Whitney U tests. Multivariable logistic regression was performed. Interreader agreement was assessed by kappa coefficients. RESULTS. A total of 94% of patients in the AE group underwent segmentectomy or other surgery that was more extensive than wedge resection versus 75% in the no-AE group (p = .046). The usual IP pattern was present in 58% of the AE group versus 74% of the no-AE group (p = .16). According to subjective visual scoring, the mean (± SD) ground-glass opacity (GGO) extent was 6.3 ± 5.4 in the AE group versus 3.9 ± 3.8 in the no-AE group (p = .03), and the mean consolidation extent was 0.5 ± 1.2 in the AE group versus 0.1 ± 0.3 in the no-AE group (p = .009). Mean pulmonary trunk diameter was 28 ± 4 mm in the AE group versus 26 ± 3 mm in the no-AE group (p = .02). In a model of CT features only, independent predictors of AE (p < .05) were GGO extent (odds ratio [OR], 2.8), consolidation extent (OR, 9.4), and pulmonary trunk diameter (OR, 4.2); this model achieved an AUC of 0.75, a PPV of 71%, and an NPV of 77% for AE. When CT and clinical variables were combined, undergoing segmentectomy or more extensive surgery also independently predicted AE (OR, 8.2; p = .02). CONCLUSION. The presence of GGO, consolidation, and pulmonary trunk enlargement on preoperative CT predicts AE in patients with IP who are undergoing lung cancer surgery. CLINICAL IMPACT. Patients with IP and lung cancer should be carefully managed when predictive CT features are present. Wedge resection, if possible, may help reduce the risk of AE in these patients. TRIAL REGISTRATION. University Hospital Medical Information Clinical Trial Registry UMIN000029661.

Pathologic, Molecular, and Prognostic Radiologic Features of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a malignancy with variable biologic aggressiveness based on the tumor grade, presence or absence of vascular invasion, and pathologic and molecular classification. Knowledge and understanding of the prognostic implications of different pathologic and molecular phenotypes of HCC are emerging, with therapeutics that promise to provide improved outcomes in what otherwise remains a lethal cancer. Imaging has a central role in diagnosis of HCC. However, to date, the imaging algorithms do not incorporate prognostic features or subclassification of HCC according to its biologic aggressiveness. Emerging data suggest that some imaging features and further radiologic, pathologic, or radiologic-molecular phenotypes may allow prediction of the prognosis of patients with HCC. An invited commentary by Bashir is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Computed Tomography Findings of Emergency Cases Resulting From Fish Bone Ingestion.

Fish bones are some of the most commonly ingested foreign bodies. In most cases, fish bone ingestion is asymptomatic, and the bones are expelled from the body spontaneously. Otherwise, patients with fish bone ingestion can present to the emergency department with nonspecific symptoms. Fish bones can become impacted in various part of the body. Even in cases that are initially asymptomatic after ingestion, serious complications may develop at a later stage. Computed tomography (CT) plays an important role in the diagnosis of fish bone ingestion because it is the most sensitive modality for detecting these foreign bodies. It is important to be familiar with CT findings to detect ingested fish bones and the related complications and to direct further management of the condition.

Diffusion-weighted MRI-based Virtual Elastography for the Assessment of Liver Fibrosis.

Background Diffusion-weighted (DW) MRI-based elastography has recently been proposed for noninvasive liver fibrosis staging but requires evaluation in a larger number of patients. Purpose To compare DW MRI and MR elastography for the assessment of liver fibrosis. Materials and Methods In this retrospective study, patients underwent MR elastography and DW MRI between November 2017 and April 2018. Shear modulus measured by MR elastography (µMRE) was obtained in each patient from regions of interest placed on liver stiffness maps by two independent readers. Shifted apparent diffusion coefficient (ADC) was calculated from DW MRI (b = 200 and 1500 sec/mm2) and converted to DW MRI-based virtual shear modulus (µDiff). MRI-based liver fibrosis stages were estimated from µMRE and µDiff values (F0-F4) and serum fibrosis markers were assessed. Statistical analyses included Bland-Altman plots, Bayesian prediction, and receiver operating characteristic analyses. Results Seventy-four patients (mean age, 68 years ± 9 [standard deviation]; 45 men) were evaluated. Interreader coefficient of reproducibility was 0.86 kPa for DW MRI and 1.2 kPa for MR elastography. Strong correlation between shifted ADC and µMRE was observed (r2 = 0.81; P < .001), showing high agreement between µMRE and µDiff values (mean difference, -0.02 kPa ± 0.88; P < .001). DW MRI-based fibrosis staging agreed with MR elastography-based staging in 55% of patients (41 of 74) and within one stage difference in 35% of patients (26 of 74). Binarization into insignificant (F0-F1) and significant fibrosis (F2-F4) showed agreement in 85% of patients (63 of 74; κ = 0.85). Compared with serum markers (area under the receiver operating characteristic curve [AUC], 0.50-0.69), µDiff showed better performance in discriminating fibrosis stages F0-F2 from F3-F4 (AUC, 0.79; 95% confidence interval: 0.69, 0.90), whereas serum markers showed slightly better results for F0-F1 versus F2-F4 differentiation (fibrosis stages were estimated by using MR elastography). Combining DW MRI with serum markers provided a trend toward highest discriminative performance (AUC, µDiff + aspartate aminotransferase-to-platelet radio index: F0-F1 vs F2-F4, 0.81 [95% confidence interval: 0.69, 0.93], P = .17; F0-F2 vs F3-F4, 0.83 [95% confidence interval: 0.74, 0.92], P = .07; and AUC µDiff + Fibrosis 4 score: F0-F1 vs F2-F4, 0.78 [95% confidence interval: 0.64, 0.92], P < .30; F0-F2 vs F3-F4, 0.81 [95% confidence interval: 0.71, 0.91], P = .08). Conclusion MR elastography and diffusion-weighted (DW) MRI-based estimation of liver fibrosis stage showed high agreement. DW MRI shows potential as an alternative to MR elastography for noninvasive fibrosis staging without the need for mechanical vibration setup. © RSNA, 2020 Online supplemental material is available for this article.

Predicting Patients With Insufficient Liver Enhancement in the Hepatobiliary Phase Before the Injection of Gadoxetic Acid: A Practical Approach Using the Bayesian Method.

BACKGROUND: Gadoxetic acid-enhanced hepatobiliary phase (HBP) is useful in liver MRI, but sometimes shows insufficient liver enhancement. There is no established method to predict insufficient liver enhancement before the contrast injection. PURPOSE: To reveal the utility of the Bayesian method for predicting patients with insufficient liver enhancement in the gadoxetic acid-enhanced HBP. STUDY TYPE: Retrospective. SUBJECTS: In all, 576 patients with chronic liver disease. FIELD STRENGTH/SEQUENCE: 3T/3D gradient-echo T1 -weighted imaging and MR elastography (MRE). ASSESSMENT: The patients were divided into two groups: insufficient and sufficient liver enhancement in HBP according to the liver-to-portal vein signal intensity ratio. Various parameters, including liver function tests and liver stiffness by MRE, were evaluated as predictors of insufficient liver enhancement. STATISTICAL TESTS: We used Chi-square/Student's t-test/logistic regression analysis to determine independent associates, and Bayes' theorem to estimate the probability of insufficient (or sufficient) liver enhancement. The feasibility of Bayesian prediction of insufficient liver enhancement was tested by leave-one-out cross-validation to calculate sensitivity and specificity for single variables and combinations of some variables in all patients and in a subpopulation showing a confidence level of >80%. RESULTS: Independent associates of insufficient liver enhancement in HBP included: serum albumin (odds ratio [OR] = 4.82, P < 0.001), total bilirubin (OR = 0.30, P < 0.00), platelet count (OR = 1.54, P < 0.00), and liver stiffness by MRE (OR = 0.59, P < 0.00). The accuracy of Bayesian prediction of insufficient liver enhancement was 80.9% (466/576) for the single parameter of albumin and 79.0% (455/576) for total bilirubin, and was increased to 85.2% (487/576) for a combination of albumin, total bilirubin, and liver stiffness. In patients who showed a confidence level of >80%, the accuracy was 89.0% (439/493) for the above combination. DATA CONCLUSION: Bayesian prediction was useful to predict patients with insufficient enhancement by combining serum liver function tests and liver stiffness by MRE. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:62-69.

MRI-based risk factors of hepatocellular carcinoma in patients with chronic liver disease: A prospective observational study.

BACKGROUND: MR-based metrics, including hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE), and liver stiffness as measured by MR elastography are useful markers to stratify the risk of hepatocellular carcinoma (HCC) development in chronic liver disease patients. However, prospective studies are needed to clarify their utility. PURPOSE: To perform a risk analysis of HCC development in chronic liver disease patients, with a focus on MR-based biomarkers. STUDY TYPE: Prospective. SUBJECTS: Consecutive 110 cirrhotic patients (61 males, 49 females) without a history of HCC who matched the inclusion criteria. FIELD STRENGTH/SEQUENCE: 3T/3D gradient-echo T1 -weighted images and MR elastography. ASSESSMENT: Patients underwent MRI for HCC screening and attended follow-up appointments every 3 months. The primary endpoint was the development of hypervascular HCC. Patients were classified according to the presence of an HBP hypointense nodule without APHE (if present in the liver, the patient was classified in nonclean liver group; if absent, clean liver group), and stiffness value on MR elastography (soft liver, <4.0 kPa; stiff liver, ≥4.0 kPa) at the initial examination. STATISTICAL TESTS: Risk factors were identified in univariate and multivariate Cox regression models. Incidence rates of HCC development were evaluated using the Kaplan-Meier method. RESULTS: Patients were classified into clean-liver (n = 76) and nonclean-liver groups (n = 34), and into soft-liver (n = 53) and stiff-liver groups (n = 45). During the follow-up period (median, 21.0 months), 16 patients developed hypervascular HCC. Patients in the nonclean-liver group showed a higher incidence of hypervascular HCC than those in the clean-liver group (3-year HCC incidence rates: 50.4% and 5.7%, respectively; P < 0.05). A nonclean liver was independently associated with hypervascular HCC development (hazard ratio, 18.75; 95% confidence interval, 4.83-128.63; P < 0.0001), but stiff liver was not (1.91; 0.66-6.23; P = 0.23). DATA CONCLUSION: An HBP hypointense nodule without APHE observed on a gadoxetic acid-enhanced MR image is a strong indicator of subsequent development of hypervascular HCC in patients with chronic liver disease. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:389-396.

Distinguishing intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma by computed tomography and magnetic resonance imaging using the Bayesian method: a bi-center study.

OBJECTIVES: To determine imaging hallmarks for distinguishing intrahepatic mass-forming biliary carcinomas (IMBCs) from hepatocellular carcinoma (HCC) and to validate their diagnostic ability using Bayesian statistics. METHODS: Study 1 retrospectively identified clinical and imaging hallmarks that distinguish IMBCs (n = 41) from HCC (n = 247) using computed tomography (CT) and magnetic resonance imaging (MRI). Study 2 retrospectively assessed the diagnostic ability of these hallmarks to distinguish IMBCs (n = 37) from HCC (n = 111) using Bayesian statistics with images obtained from a different institution. We also assessed the diagnostic ability of the hallmarks in the patient subgroup with high diagnostic confidence (≥ 80% of post-test probability). Two radiologists independently evaluated the imaging findings in studies 1 and 2. RESULTS: In study 1, arterial phase peritumoral parenchymal enhancement on CT/MRI, delayed enhancement on CT/MRI, diffusion-weighted imaging peripheral hyperintensity, and bile duct dilatation were hallmarks indicating IMBCs, whereas chronic liver disease, non-rim arterial phase hyperenhancement on CT/MRI, enhancing capsule on CT/MRI, and opposed-phase signal drop were hallmarks indicating HCC (p = 0.001-0.04). In study 2, Bayesian statistics-based post-test probability combining all hallmark features had a diagnostic accuracy of 89.2% (132/148) in distinguishing IMBCs from HCC for both readers. In the high diagnostic confidence subgroup (n = 120 and n = 124 for readers 1 and 2, respectively), the accuracy improved (95.0% (114/120) and 93.5% (116/124) for readers 1 and 2, respectively). CONCLUSIONS: Combined interpretation of CT and MRI to identify hallmark features is useful in discriminating IMBCs from HCCs. High post-test probability by Bayesian statistics allows for a more reliable non-invasive diagnosis. KEY POINTS: • Combined interpretation of CT and MRI to identify hallmark features was useful in discriminating intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma. • Bayesian method-based post-test probability combining all hallmark features determined in study 1 showed high (> 90%) sensitivity and specificity for distinguishing intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma. • If the post-test probability or the confidence was ≥ 80% when combining the imaging features of CT and MRI, the high specificity of > 95% was achieved without any loss of sensitivity to distinguish hepatocellular carcinoma from intrahepatic mass-forming biliary carcinomas.

Imaging Findings of Acute Abdomen due to Complications of Meckel Diverticulum.

Meckel diverticulum is the most common and well-known congenital anomaly of the digestive system. Although most cases are asymptomatic, Meckel diverticulum can have a variety of complications, including gastrointestinal bleeding as a result of peptic ulceration, diverticulitis, and small bowel obstruction. Although the radiologic findings of these complications have been reported, they are difficult to diagnose preoperatively because Meckel diverticulum is a small entity. Computed tomography and scintigraphy play an important role in the diagnosis of Meckel diverticulum and its complications. It is important to be familiar with the radiologic features of acute abdomen due to complications of Meckel diverticulum to be able to manage the condition appropriately.

Linear gadolinium-based contrast agent (gadodiamide and gadopentetate dimeglumine)-induced high signal intensity on unenhanced T1 -weighted images in pediatric patients.

BACKGROUND: Recent studies of adults have found an association between hyperintensity of the dentate nucleus (DN) and globus pallidus (GP) on T1 -weighted images (T1 WI) and a history of linear gadolinium-based contrast agent (GBCA) administration. Several reports have also focused on this phenomenon in pediatric patients; however, data in the current literature remains limited. PURPOSE/HYPOTHESIS: To evaluate the associations between DN and GP T1 -signal increase and previous administration of linear GBCAs in pediatric patients. STUDY TYPE: Single-center, retrospective, cross-sectional study. POPULATION: We included pediatric patients with histories of ≥5 linear GBCA (gadodiamide and gadopentetate dimeglumine) administrations (the "≥5 Linear GBCA administrations" group), 1-4 administrations (the "1-4 Linear GBCA administrations" group), and no history of GBCA administration (the "No GBCA administration" group). Each group included 42 patients. Therefore, 126 patients (male:female, 72:54; median age, 16 [range, 4-18] years) were included in this study. FIELD STRENGTH/SEQUENCE: 1.5T/ Spin-echo unenhanced T1 -weighted imaging. ASSESSMENT: Unenhanced T1 -weighted images were quantitatively analyzed by two radiologists. The DN-to-pons and GP-to-thalamus signal intensity ratios (DN-to-pons and GP-to-thalamus ratios, respectively) were compared. STATISTICAL TESTS: Wilcoxon test with the Bonferroni correction and intraclass correlation coefficients. RESULTS: The DN-to-pons ratio increased as the number of GBCA administrations increased (P < 0.0063). The GP-to-thalamus ratio of the "≥5 Linear GBCA administrations" group was significantly higher than those of the other two groups (P < 0.0001). The GP-to-thalamus ratio of the "1-4 Linear GBCA administrations" group did not differ significantly from that of the "No GBCA administration" group (P = 1.000). The DN-to-pons and GP-to-thalamus ratios' interobserver intraclass correlation coefficients were excellent (0.8236) and good (0.6738), respectively. DATA CONCLUSION: High signal intensities in the DN and GP on T1 WI were associated with previous linear GBCA administration in pediatric patients. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1046-1052.

Magnetic resonance elastography can predict development of hepatocellular carcinoma with longitudinally acquired two-point data.

OBJECTIVE: To evaluate the usefulness of longitudinal observation of liver stiffness measured using magnetic resonance elastography (MRE) to stratify the risk of hepatocellular carcinoma (HCC) in patients with chronic liver disease. MATERIALS AND METHODS: We retrospectively reviewed data for 161 patients with chronic liver disease using the following inclusion criteria: two MRE examinations separated by at least a 12-month interval, no history of HCC, no development of HCC between the two examinations and availability of laboratory results. Liver stiffness was classified as low (< 3 kPa), moderate (3-4.7 kPa) or high (> 4.7 kPa). The patients were divided into three groups according to sequential changes in liver stiffness as follows: high on the first MRE (group A, n = 60), low on both MRE examinations (group C, n = 36) and other combinations (group B, n = 65). Cox analyses and Kaplan-Meier methods were used to determine the risk of developing HCC. RESULTS: Forty-seven patients (29.2%) developed HCC during follow-up (46.7% [28/60] in group A, 26.2% [17/65] in group B, and 5.6% [2/36] in group C). There was a significant difference in the rate of development of HCC between groups A (45.1%), B (26.1%) and C (12.4%) at 3 years (p = 0.0002). The independent risk factors for development of HCC were group A classification, age and a high alanine aminotransferase level (risk ratio 1.018-6.030; p = 0.0028-0.0268). CONCLUSION: Longitudinal observation of liver stiffness using MRE can stratify the risk of HCC during follow-up of chronic liver disease. KEY POINTS: • The results of MRE can stratify the risk for development of HCC during follow-up in patients with chronic liver disease. • Patients with chronic liver disease and high liver stiffness (> 4.7 kPa) on a previous MRE examination are at high risk for developing HCC, regardless of current liver stiffness. • Management of patients with chronic liver disease becomes more appropriate using longitudinally acquired two-point MRE data.

Dose-dependence of transient respiratory motion artifacts on gadoxetic acid-enhanced arterial phase MR images.

PURPOSE: To compare the occurrence of transient respiratory motion (TM) artifacts between 0.05 mmol/kg and 0.025 mmol/kg gadoxetic-acid on arterial phase MRI intra-individually for evaluating dose-dependence of gadoxetic acid. MATERIALS AND METHODS: This retrospective study involved 91 patients who underwent dynamic MRI at 1.5T at different times, one time with 0.05 mmol/kg and the other 0.025 mmol/kg gadoxetic-acid. Examinations with 0.05 mmol/kg totaled 91 scans, and examinations with 0.025 mmol/kg totaled 375 scans (due to multiple exams for several patients). The scan with 0.025 mmol/kg closest in time to the 0.05 mmol/kg scan was selected to minimize temporal effects. Two radiologists graded TM artifacts in the arterial phase images using a four-point scale: no, mild, moderate, and severe artifacts. Results were compared between the two protocols (0.05 mmol/kg versus all 0.025 mmol/kg and 0.05 mmol/kg versus selected 0.025 mmol/kg), and the odds ratio for moderate-to-severe artifacts was calculated. RESULTS: Significantly more TM artifacts were observed in the double dose (16/91 [17%]) scans compared with either all (17/375 [4%]; P < 0.01) or selected (3/91 [3%]; P = 0.01) standard dose scans. The odds ratio of the moderate-to-severe artifacts with the higher dose was 4.99-5.33. CONCLUSION: There appears to be dose-dependence of gadoxetic-acid and the occurrence of TM artifacts. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:433-438.