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Objectives: To investigate the impact of mesorectal fat area (MFA) on oncologic outcomes in patients with mid-to-lower rectal cancer who received curative-intent surgery.Methods: Patients with mid-to-lower rectal cancer who underwent preoperative abdominopelvic computed tomography (CT) and curative-intent surgery in 2011 were divided into two groups by tumour recurrence (group A) or no recurrence (group B) during a 5-year follow-up. Visceral fat area (VFA) and MFA were measured on preoperative CT and cutoff values were calculated using the Youden index. Univariate and multivariate regression analyses including BMI, VFA, and MFA were performed to investigate meaningful prognostic biomarkers. The Kaplan-Meier method with log-rank testing was used to validate prognostic biomarkers.Results: Group A contained 42 patients and group B had 155 patients. Cutoff values were 25 kg/m2 for BMI, 130 cm2 for VFA, and 10 cm2 for MFA using the Youden index. On multivariate Cox regression analysis, MFA (odds ratio [OR] = 0.426, p = 0.010), TNM stage (p = 0.027), and perioperative complication grade (p = 0.028) were significantly different between groups. BMI and VFA did not show significant differences. By the Kaplan-Meier method with log-rank testing, disease-free survival (DFS) was significantly longer in patients with MFA ≥10 cm2 compared to patients with MFA <10 cm2 (p = 0.021), with no significant difference in overall survival (OS).Conclusions: MFA was an independent biomarker for predicting DFS in patients who underwent curative-intent surgery for mid-to-lower rectal cancer.Key Points: • Mesorectal fat area is associated with the prognosis of rectal cancer patients. • Mesorectal fat area can be calculated easily in pre-operative CT scan. • Predicting prognosis of the cancer patient before operation is important. [ABSTRACT FROM AUTHOR]

Objectives: To assess whether gadoxetic acid-enhanced MRI could be used as a prognostic factor for intrahepatic mass-forming cholangiocarcinomas (IMCCs).Methods: Forty-one patients with pathologically proven IMCCs who underwent preoperative gadoxetic acid-enhanced MRI were included. The signal intensity of the IMCCs on hepatobiliary phase (HBP) MRI was qualitatively analyzed by two radiologists, and categorized into intermediate or hypointense groups. Analysis of clinicopathological prognostic factors and correlations of imaging and histology were also performed. Survival time and time to recurrence (TTR) were analyzed.Results: Of the 41 IMCCs, 23 were in the intermediate group and 18 were in the hypointense group on HBP MRI. IMCCs in the intermediate group were associated with shorter survival time (P = 0.048) and TTR (P = 0.002) than the IMCCs of the hypointense group. Only the intermediate group on HBP MRI had a significantly shorter TTR on multivariate analysis (P = 0.012). The IMCCs of the intermediate group showed a tendency for more abundant tumour fibrous stroma than those of the hypointense group (P = 0.027).Conclusions: The enhancement of IMCCs on HBP gadoxetic acid-enhanced MRI appears to correlate with tumour aggressiveness and outcomes due to the tumour fibrous stromal component. Thus, HBP images could be a useful prognostic factor for IMCCs after surgery.Key Points: • The enhancement of IMCCs on HBP correlates with the tumour fibrous stroma. • The enhancement of IMCCs on HBP MRI appears to correlate with prognosis. • Gadoxetic acid-enhanced MRI is helpful for predicting prognosis of IMCCs after surgery. [ABSTRACT FROM AUTHOR]

Objectives: To compare the ability of diffusion-weighted imaging (DWI) parameters acquired from three different models for the diagnosis of hepatic fibrosis (HF).Methods: Ninety-five patients underwent DWI using nine b values at 3 T magnetic resonance. The hepatic apparent diffusion coefficient (ADC) from a mono-exponential model, the true diffusion coefficient (D t ), pseudo-diffusion coefficient (D p ) and perfusion fraction (f) from a biexponential model, and the distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (α) from a stretched exponential model were compared with the pathological HF stage. For the stretched exponential model, parameters were also obtained using a dataset of six b values (DDC#, α#). The diagnostic performances of the parameters for HF staging were evaluated with Obuchowski measures and receiver operating characteristics (ROC) analysis. The measurement variability of DWI parameters was evaluated using the coefficient of variation (CoV).Results: Diagnostic accuracy for HF staging was highest for DDC# (Obuchowski measures, 0.770 ± 0.03), and it was significantly higher than that of ADC (0.597 ± 0.05, p < 0.001), D t (0.575 ± 0.05, p < 0.001) and f (0.669 ± 0.04, p = 0.035). The parameters from stretched exponential DWI and D p showed higher areas under the ROC curve (AUCs) for determining significant fibrosis (≥F2) and cirrhosis (F = 4) than other parameters. However, D p showed significantly higher measurement variability (CoV, 74.6%) than DDC# (16.1%, p < 0.001) and α# (15.1%, p < 0.001).Conclusions: Stretched exponential DWI is a promising method for HF staging with good diagnostic performance and fewer b-value acquisitions, allowing shorter acquisition time.Key Points: • Stretched exponential DWI provides a precise and accurate model for HF staging. • Stretched exponential DWI parameters are more reliable than D p from bi-exponential DWI model • Acquisition of six b values is sufficient to obtain accurate DDC and α. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the optimal magnetic resonance (MR) imaging protocol in pregnant women suspected of having acute appendicitis.Materials and Methods: One hundred and forty-six pregnant women with suspected appendicitis were included. MR images were reviewed by two radiologists in three separate sessions. In session 1, only axial single-shot turbo spin echo (SSH-TSE) T2-weighted images (WI) were included with other routine sequences. In sessions 2 and 3, coronal and sagittal T2WI were sequentially added. The visibility of the appendix and diagnostic confidence of appendicitis were evaluated in each session using a 5-point grading scale. If diseases other than appendicitis were suspected, specific diagnosis with a 5-point confidence scale was recorded. Diagnostic performance for appendicitis and other diseases were evaluated.Results: Twenty-five patients (17.1%) were diagnosed with appendicitis. Among the patients with normal appendix, 28 were diagnosed with other disease. Diagnostic performance including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the curve values for diagnosing appendicitis and other diseases showed no significant difference among sets for both reviewers (p>0.05).Conclusion: Diagnostic performance of MR in pregnant patients with suspected appendicitis can be preserved with omission of sagittal or both coronal and sagittal SSH-T2WI.Key Points: • Diagnostic performance of appendicitis is preserved with omission of sagittal/coronal T2WIs. • Diagnosis of other disease may be sufficient with axial T2WIs only. • Careful serial omission of sagittal and coronal T2WIs can be considered. [ABSTRACT FROM AUTHOR]

Objectives: To compare the diagnostic performance of the stretched exponential model to those of other DWI models and transient elastography (TE) and to evaluate the influence of confounding factors on the staging of liver fibrosis. Methods: This retrospective study included 78 consecutive patients who underwent both DWI and TE. The distributed diffusion coefficient (DDC) and intravoxel heterogeneity index (α) from the stretched exponential model, apparent diffusion coefficient (ADC), perfusion fraction (f), pseudodiffusion coefficient (Dp), true diffusion coefficient (Dt), and TE were obtained. Associations between imaging parameters and pathological fibrosis, inflammation, and steatosis were evaluated using Spearman's correlation and multiple regression analysis. Diagnostic accuracy of parameters for fibrosis staging was assessed via the Obuchowski measures. Results: DDC was the only parameter to differ between F0–1 and F2–3 (p < 0.001) and between F2–3 and F4 (p = 0.013). DDC showed significant correlation with fibrosis (p < 0.001) and inflammation (p = 0.001), but not with steatosis (p = 0.619), and was independently associated with only fibrosis in multiple regression analysis (β = − 0.114, p < 0.001). ADC, Dp, and Dt showed a significant correlation with steatosis (ps ≤ 0.038). DDC showed the highest diagnostic performance for liver fibrosis (0.717; 95% confidence interval, 0.653–0.765) followed by TE (0.681, 0.623–0.733) without a significant difference between DDC and TE (p > 0.999). Conclusions: DDC from the stretched exponential model is the most accurate DWI parameter with no confounding effect from steatosis and with overall similar diagnostic performance to TE. Key Points: • The distributed diffusion coefficient (DDC) from the stretched exponential model is the most accurate DWI parameter for staging liver fibrosis. • DDC and transient elastography have similar good diagnostic performance for evaluating liver fibrosis. • The stretched exponential DWI model has no confounding effect by steatosis, unlike other DWI models. [ABSTRACT FROM AUTHOR]

Objective: To compare the stretched exponential model of diffusion-weighted imaging (DWI) with monoexponential and biexponential models in terms of the ability to characterize focal liver lesions (FLLs).Methods: This retrospective study included 180 patients with FLLs who underwent magnetic resonance imaging including DWI with nine b values at 3.0 T. The distributed diffusion coefficient (DDC) and intravoxel diffusion heterogeneity index (α) from a stretched exponential model; true diffusion coefficient (Dt), pseudo-diffusion coefficient (Dp), and perfusion fraction (f) from a biexponential model; and apparent diffusion coefficient (ADC) were calculated for each lesion. Diagnostic performances of the parameters were assessed through receiver operating characteristic (ROC) analysis. For 20 patients with treated hepatic metastases, the correlation between the DWI parameters and the percentage of tumor necrosis on pathology was evaluated using the Spearman correlation coefficient.Results: DDC had the highest area under the ROC curve (AUC, 0.905) for differentiating malignant from benign lesions, followed by Dt (0.903) and ADC (0.866), without significant differences among them (DDC vs. Dt, p = 0.946; DDC vs. ADC, p = 0.157). For distinguishing hypovascular from hypervascular lesions, and hepatocellular carcinoma from metastasis, f  had a significantly higher AUC than the other DWI parameters (p < 0.05). The α had the strongest correlation with the degree of tumor necrosis (ρ = 0.655, p = 0.002).Conclusion: The DDC from stretched exponential model of DWI demonstrated excellent diagnostic performance for differentiating malignant from benign FLLs. The α is promising for evaluating the degree of necrosis in treated metastases.Key Points: • The stretched exponential DWI model is valuable for characterizing focal liver lesions. • The DDC from stretched exponential model shows excellent performance for differentiating malignant from benign focal liver lesions. • The α from stretched exponential model is promising for evaluating the degree of necrosis in hepatic metastases after chemotherapy. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the diagnostic value of the T1 bright appendix sign for the diagnosis of acute appendicitis in pregnant women.Material and Methods: This retrospective study included 125 pregnant women with suspected appendicitis who underwent magnetic resonance (MR) imaging. The T1 bright appendix sign was defined as a high intensity signal filling more than half length of the appendix on T1-weighted imaging. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the T1 bright appendix sign for normal appendix identification were calculated in all patients and in those with borderline-sized appendices (6-7 mm).Results: The T1 bright appendix sign was seen in 51% of patients with normal appendices, but only in 4.5% of patients with acute appendicitis. The overall sensitivity, specificity, PPV, and NPV of the T1 bright appendix sign for normal appendix diagnosis were 44.9%, 95.5%, 97.6%, and 30.0%, respectively. All four patients with borderline sized appendix with appendicitis showed negative T1 bright appendix sign.Conclusion: The T1 bright appendix sign is a specific finding for the diagnosis of a normal appendix in pregnant women with suspected acute appendicitis.Key Points: • Magnetic resonance imaging is increasingly used in emergency settings. • Acute appendicitis is the most common cause of acute abdomen. • Magnetic resonance imaging is widely used in pregnant population. • T1 bright appendix sign can be a specific sign representing normal appendix. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to investigate the optimal radiologic method to determine Milan criteria (MC) for the prediction of recurrence in patients who underwent locoregional treatment (LRT) for hepatocellular carcinoma (HCC) and subsequent liver transplantation (LT). Methods: This retrospective study included 121 HCC patients who underwent LRT and had both liver dynamic CT and MRI. They were classified with MC using four cross combinations of two imaging modalities (CT and MRI) and two diagnostic criteria (modified Response Evaluation Criteria in Solid Tumors [mRECIST] and Liver Imaging Reporting and Data System treatment response algorithm [LI-RADS TRA]). Competing risk regression was performed to analyze the time to recurrence after LT. The predictive abilities of the four methods for recurrence were evaluated using the time-dependent area under the curve (AUC). Results: Competing risk regression analyses found that beyond MC determined by MRI with mRECIST was independently associated with recurrence (hazard ratio, 6.926; p = 0.001). With mRECIST, MRI showed significantly higher AUCs than CT at 3 years and 5 years after LT (0.597 vs. 0.756, p = 0.012 at 3 years; and 0.588 vs. 0.733, p = 0.024 at 5 years). Using the pathologic reference standard, MRI with LI-RADS TRA showed higher sensitivity (61.5%) than CT with LI-RADS TRA (30.8%, p < 0.001) or MRI with mRECIST (38.5%, p < 0.001). Conclusions: MRI with mRECIST was the optimal radiologic method to determine MC for the prediction of post-LT recurrence in HCC patients with prior LRT. Key Points: • MRI with modified RECIST (mRECIST) is the optimal preoperative method to determine Milan criteria for the prediction of post-transplant HCC recurrence in patients with prior locoregional treatment. • With mRECIST, MRI was better than CT for the prediction of post-transplant recurrence. [ABSTRACT FROM AUTHOR]

Objectives: We performed a meta-analysis to determine the probability of hepatocellular carcinoma (HCC) and non-HCC malignancies in Liver Imaging Reporting and Data System (LI-RADS) category M (LR-M) observations and the frequency of defined LR-M imaging features on MRI using LI-RADS v2018. Methods: We searched the MEDLINE and EMBASE databases to identify studies published from 1 January 2018 to 16 March 2021 reporting the probability of category LR-M in HCC and non-HCC malignancies on MRI. The pooled percentages of HCC and non-HCC malignancies in the LR-M observations were evaluated. Meta-regression analysis was performed to identify factors for study heterogeneity. The frequencies of defined LR-M imaging features were also calculated. Risk of bias and concerns regarding applicability were evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Results: We identified 18 studies reporting the diagnostic performance of the LR-M category (3,812 observations in 3,615 patients), with nine studies reporting the frequencies of LR-M imaging features. The pooled percentages of HCC and non-HCC malignancies in the LR-M observations were 29% (95% confidence interval [CI], 21–38%) and 67% (95%CI, 57–77%), respectively. The study type and inclusion of benign lesions were significant factors for study heterogeneity. Of the 10 LR-M imaging features, rim arterial phase hyperenhancement (APHE) showed the highest frequency in non-HCC malignancies (68%; 95%CI, 61–75%). Conclusions: The LR-M category was commonly used to characterize non-HCC malignancies, but also included 29% of HCC. The frequencies of the different LR-M imaging features were variable, with rim APHE showing the highest frequency in non-HCC malignancies. Key Points: • In the LR-M category using LI-RADS v2018 for MRI, the pooled percentage of malignancies in general was 96%, with 29% HCC and 67% non-HCC malignancies, while the remaining 4% was benign entity. • The study type and inclusion of benign lesions were significant factors contributing to substantial heterogeneity among included studies. • The frequencies of the different LR-M imaging features were variable, with rim APHE showing the highest frequency in non-HCC malignancies. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate feasibility of radiation dose reduction by optimal phase selection of computed tomography (CT) in patients who visited the emergency department (ED) for abdominal pain.Methods: We included 253 patients who visited the ED for abdominal pain. They underwent multiphasic CT including precontrast, late arterial phase (LAP), and hepatic venous phase (HVP). Three image sets (HVP, precontrast + HVP, and precontrast + LAP + HVP) were reviewed. Two reviewers determined the most appropriate diagnosis with five-point confidence scale. Diagnostic performances were compared among image sets by weighted-least-squares method or DeLong's method. Linear mixed model was used to assess changes of diagnostic confidence and radiation dose.Results: There was no difference in diagnostic performance among three image sets, although diagnostic confidence level was significantly improved after review of triphasic images compared with both HVP images only or HVP with precontrast images (confidence scale, 4.64 ± 0.05, 4.66 ± 0.05, and 4.76 ± 0.04 in the order of the sets; overall P = 0.0008). Similar trends were observed in the subgroup analysis for diagnosis of pelvic inflammatory disease and cholecystitis.Conclusions: There is no difference between HVP-CT alone and multiphasic CT for the diagnosis of causes of abdominal pain in patients admitted to the ED without prior chronic disease or neoplasia.Key Points: • There was no difference in diagnostic performance of HVP CT and multiphasic CT. • The diagnostic confidence level was improved after review of the LAP images. • HVP CT can achieve diagnostic performance similar to that of multiphasic CT, while minimizing radiation. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to assess the detection of hepatocellular carcinoma (HCC) utilizing subtraction AP (arterial phase) imaging only for T1 hyperintense observations compared with the detection of HCC on subtraction AP imaging that included T1 hyper-, iso-, and hypointense lesions on gadoxetate disodium–enhanced MRI. Materials and methods: This retrospective study included 234 patients (311 observations including 239 HCCs) at high risk for HCC who underwent gadoxetate disodium–enhanced MRI with subtraction AP imaging between 2015 and 2017. Arterial phase hyperenhancement (APHE) was divided into two subtypes: conventional APHE, where subtraction AP imaging is used to detect APHE only for T1 hyperintense observations; and modified APHE, where subtraction AP imaging is applied to T1 hyper-, iso-, and hypointense lesions. Two readers independently reviewed all observations and the per-observation diagnostic performances were compared using McNemar's test. Results: Modified nonrim APHE showed significantly higher sensitivity than conventional nonrim APHE (90.0% vs 82.8%; p < 0.001) for diagnosing HCC, without a significant difference in specificity (66.7% vs 68.1%; p > 0.999). The LR-5 category with modified nonrim APHE provided better sensitivity than the LR-5 with conventional nonrim APHE (70.3% vs 63.2%; p < 0.001), without a significant decrease in specificity (94.4% vs 95.8%; p > 0.999). Conclusion: Extended application of subtraction AP imaging for T1 hypo- or isointense observations on gadoxetate disodium–enhanced MRI can improve sensitivity in the diagnosis of HCC without a significant difference in specificity. Key Points: • Modified nonrim arterial phase hyperenhancement (APHE), extended application of subtraction arterial phase imaging for T1 hypo- or isointense observation, outperforms conventional nonrim APHE. • The LR-5 category with modified nonrim APHE provided better sensitivity in diagnosing HCC than the LR-5 with conventional APHE, without a significant decrease in specificity. [ABSTRACT FROM AUTHOR]

Objective: To investigate the feasibility of using amide proton transfer (APT) magnetic resonance imaging (MRI) in the liver and to evaluate its ability to characterize focal liver lesions (FLLs).Methods: A total of 203 patients with suspected FLLs who underwent APT imaging at 3T were included. APT imaging was obtained using a single-slice turbo spin-echo sequence to include FLLs through five breath-holds, and its acquisition time was approximately 1 min. APT signals in the background liver and FLL were measured with magnetization transfer ratio asymmetry (MTRasym) at 3.5 ppm. The technical success rate of APT imaging and the reasons for failure to obtain meaningful MTRasym values were assessed. The Mann Whitney U test was used to compare MTRasym values between different FLLs.Results: The technical success rate of APT imaging in the liver was 62.1% (126/203). The reasons for failure were a too large B0 inhomogeneity (n = 43), significant respiratory motion (n = 12), and these two factors together (n = 22), respectively. Among 59 FLLs with analyzable APT images, MTRasym values were compared between 27 patients with liver metastases and 23 patients with hepatocellular carcinomas (HCCs). The MTRasym values of metastases were significantly higher than those of HCC (0.13 ± 2.15% vs. - 1.41 ± 3.68%, p = 0.027).Conclusions: APT imaging could be an imaging biomarker for the differentiation of FLLs. However, further technical improvement is required before APT imaging can be clinically applied to liver MRI.Key Points: • Liver APT imaging was technically feasible, but with a relatively low success rate (62.1%). • Liver metastases showed higher APT values than hepatocellular carcinomas. [ABSTRACT FROM AUTHOR]

Objectives: Contrast-induced acute kidney injury (CI-AKI) is one of the leading causes of new-onset renal failure in hospitalized patients. Statin has been evaluated for its protective effect against CI-AKI but rarely in patients receiving intravenous (IV) administrations of iodine-based contrast media for enhanced computed tomography (CT).Methods: In total, 12,371 patients who underwent contrast-enhanced abdominopelvic CT were retrospectively reviewed and stratified into statin users and statin nonusers. Subgroup analyses comparing high-intensity statins with low- to moderate-intensity statins were conducted within statin users and similar comparisons were performed within statin users stratified based on baseline eGFR.Results: Overall, CI-AKI events did not occur less in statin users compared with non-statin users (p = 0.342). Within statin users, CI-AKI events did not decrease in high-intensity statin users compared with low- to moderate-intensity statin users (p = 0.355). Moreover, no significant difference in CI-AKI events was found between high-intensity statin users and low- to moderate-intensity statin users even after stratifying the patients with baseline eGFR.Conclusions: Collectively, statin was not significantly associated with the risk of CI-AKI events in patients undergoing contrast-enhanced abdominopelvic CT and high-intensity statins did not show significant association with CI-AKI over low- to moderate-intensity statins in the subgroup analysis.Key Points: • Statin is not associated with risk of CI-AKI events in patients undergoing intravenous administration of contrast-enhanced CT. • CI-AKI incidence among high-intensity statin users was not significantly different from that of low- to moderate-intensity statin users. [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to investigate which feature of the breast-specific gamma imaging (BSGI) uptake in women who were recently diagnosed with breast cancer was associated with malignancy.Methods: Data on 231 newly diagnosed breast cancer patients who underwent preoperative BSGI were retrospectively reviewed. Feature analysis was done by classifying BSGI uptake into mass, non-mass, or focus/foci. Descriptors for mass, non-mass, or focus/foci were shape, distribution, number, and intensity. BSGI features of known malignancies and lesions that were additionally found by BSGI were correlated with mammographic breast density, histology, hormonal status, and clinical follow-up data obtained over at least 2 years.Results: Among 372 breast lesions from 231 patients, 241 malignancies had been pathologically confirmed prior to BSGI and 131 additional lesions were found on BSGI. Irregular shape was more predictive of malignancy than oval shape (p=0.004) in mass uptake. Linear/ductal distribution was more predictive of malignancy than focal, regional, and segmental distribution (p<0.05) in non-mass uptake. Mammographic breast density was not associated with BSGI features. The lesion to normal ratio (LNR) was higher in the postmenopausal patients than that in the premenopausal patients (p=0.003).Conclusions: The feature analysis of radiotracer uptake in BSGI is useful in predicting whether breast lesions are malignant or benign.Key Points: • The feature analysis of BSGI uptake is useful in predicting malignancy. • Irregular shape was predictive of malignancy in mass uptake. • Linear/ductal distribution was predictive of malignancy in non-mass uptake. [ABSTRACT FROM AUTHOR]

Objectives: To assess the value of a CT-based abdominal aortic calcification (AAC) score as a surrogate marker for the presence of asymptomatic coronary artery disease (CAD). Methods: The AAC scores of 373 patients without cardiac symptoms who underwent both screening coronary CT angiography and abdominal CT within one year were calculated according to the Agatston method. Logistic regression was used to derive two multivariate models from traditional cardiovascular risk factors, with and without AAC scores, to predict the presence of CAD. The AAC score and the two multivariate models were compared by calculating the area under the receiver operating characteristic curve (AUC) and the net reclassification improvement (NRI). Results: The AAC score alone showed a marginally higher AUC (0.823 vs. 0.767, P = 0.061) and significantly better risk classification (NRI = 0.158, P = 0.048) than the multivariate model without AAC. The multivariate model using traditional factors and AAC did not show a significantly higher AUC (0.832 vs. 0.823, P = 0.616) or NRI (0.073, P = 0.13) than the AAC score alone. The optimal cutoff value of the AAC score for predicting CAD was 1025.8 (sensitivity, 79.5 %; specificity, 75.9 %). Conclusions: AAC scores may serve as a surrogate marker for the presence or absence of asymptomatic CAD. Key Points: • Severe vascular calcification indicates a high probability of coronary artery disease. • Vascular calcification in the abdominal aorta can be quantified by computed tomography. • Abdominal CT could lead to early detection of asymptomatic coronary artery disease. [ABSTRACT FROM AUTHOR]

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

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

Objective: To retrospectively assess the value of adding gadolinium-enhanced dynamic imaging to standard ununenhanced magnetic resonance imaging (MRI) for characterising hypoattenuating hepatic lesions that are too small to characterise with multi-detector computed tomography (MDCT).Methods: Informed consent was waved, and institutional review board approval was obtained. Three hundred and forty-six small (≤ 2 cm) lesions (63 metastatic, 283 benign) in 183 patients with underlying carcinoma who underwent hepatic MRI after CT were retrospectively analysed. Two radiologists independently reviewed images and diagnoses were graded on an ordinal scale from 1 (definitely benign) to 5 (definitely malignant). Receiver operating characteristic analysis was used. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were also determined.Results: The areas under the curve of the ununenhanced images alone and with dynamic images were 0.837 and 0.850 for reader 1 (p = 0.616) and 0.771 and 0.783 for reader 2 (p = 0.700). Descriptive statistical values demonstrated sensitivities of 76% and 80%, specificities of 93% and 95%, PPVs of 69% and 79%, NPVs of 95% and 95% and accuracies of 90% and 92%, respectively.Conclusion: The value of adding three-phase contrast-enhanced MRI to unenhanced imaging did not reach statistical significance for characterising small hypoattenuating hepatic lesions on MDCT. [ABSTRACT FROM AUTHOR]

We examined 20 prediagnostic CTs from 16 patients for whom the diagnosis of pancreatic cancer was delayed until full diagnostic CT was performed. Three radiologists independently reviewed the prediagnostic CTs along with 50 CTs of control subjects, including patients without pancreatic disease (n = 38) or with chronic pancreatitis without calcification visible on CT (n = 12). The reviewers recorded the presence of biliary or pancreatic ductal dilation, interruption of the pancreatic duct, distal parenchymal atrophy, contour abnormality and focal hypoattenuation. Frequency, sensitivity and specificity of the significant findings were calculated. Logistic regression analysis was performed. Findings indicative of pancreatic cancer were seen on 85% (17/20) of the prediagnostic CTs. Patients with pancreatic cancer were significantly (p < 0.05) more likely to show focal hypoattenuation, pancreatic duct dilation, interruption of the pancreatic duct, and distal parenchymal atrophy, with sensitivities and specificities of 75%/84%, 50%/78%, 45%/82% and 45%/96%, respectively. Focal hypoattenuation and distal parenchymal atrophy were the independent predictors of pancreatic cancer with odds ratios of 20.92 and 11.22, respectively. In conclusion, focal hypoattenuation and pancreatic duct dilation with or without interruption, especially when accompanied by distal parenchymal atrophy, were the most useful findings for avoiding delayed diagnosis of pancreatic cancer. [ABSTRACT FROM AUTHOR]

Gastric submucosal tumors (SMTs) consist of various lesions arising from the deep layers of the stomach. Gastrointestinal stromal tumors (GISTs) are undoubtedly the commonest malignant SMTs of the stomach, and therefore the attitude towards the general diagnostic approach for GISTs defines the extended diagnostic plan for SMTs. Two recent consensus meetings were assembled concerning the classification and therapeutic plans for GISTs. These meetings shed light upon the need for the modification of the current role of imaging modalities, including endoscopic ultrasound (EUS) and computed tomography (CT). According to the revised concepts of GISTs, the most important and plausible current role of imaging for the diagnostic approach of gastric SMTs is to differentiate GISTs from other gastric SMTs. This review discusses the newly established diagnostic role of radiology according to the revised classification of GISTs and provides the differential diagnoses based on EUS and CT findings. [ABSTRACT FROM AUTHOR]

Preoperative staging of extrahepatic cholangiocarcinoma is important in determining the best treatment plan. Several classification systems have been suggested to determine the operability and extent of surgery. Longitudinal tumor extent is especially important in extrahepatic cholangiocarcinoma because operative methods differ depending on the tumor extent. The Bismuth-Corlette classification system provides useful information when planning for surgery. However, this classification system is not adequate for selecting surgical candidates. Anatomic variation of the bile duct and gross morphology of the tumor must be considered simultaneously. Lateral spread of the tumor can be evaluated based on the TNM staging provided by American Joint Committee on Cancer (AJCC). However, there is a potential for ambiguity in the distinction of T1 and T2 cancer from one another. In addition, T stage does not necessarily mean invasiveness. Blumgart T staging is helpful for the assessment of resectability with the consideration of nodal status and distant metastasis as suggested by the AJCC cancer staging system. Computed tomography (CT) and magnetic resonance imaging (MRI) are the primary tools used in the assessment of longitudinal and lateral spread of a tumor when determining respectability. Diagnostic laparoscopy and positron emission tomography (PET) may play additional roles in this regard. [ABSTRACT FROM AUTHOR]

A correction to the article "Comparison of Diagnostic Performance Between Single- and Multiphasic Contrast-Enhanced Abdominopelvic Computed Tomography in Patients Admitted to the Emergency Department With Abdominal Pain: Potential Radiation Dose Reduction," published in a previous issue of "European Radiology," is presented.