Dosimetric effects of small field size, dose grid size, and variable split-arc methods on gamma pass rates in radiation therapy.

This study investigates the influence of calculation accuracy in peripheral low-dose regions on the gamma pass rate (GPR), utilizing the Acuros XB (AXB) algorithm and ArcCHECK™ measurement. The effects of varying small field sizes, dose grid sizes, and split-arc techniques on GPR were analyzed. Various small field sizes were employed. Thirty-two single-arc plans with dose grid sizes of 2 mm and 1 mm and prescribed doses of 2, 5, 10, and 20 Gy were calculated using the AXB algorithm. In total, 128 GPR plans were examined. These plans were categorized into three sub-fields (3SF), four sub-fields (4SF), and six sub-fields (6SF). The GPR results deteriorated with smaller target sizes and a 2 mm dose grid size in a single arc. A similar degradation in GPR was observed with smaller target sizes and a 1 mm dose grid size. However, the 1 mm dose grid size generally resulted in better GPR compared with the 2 mm dose grid size for the same target sizes. The GPR improved with finer split angles and a 2 mm dose grid size in the split-arc method. However, no statistically significant improvement was observed with finer split angles and a 1 mm dose grid size. This study demonstrates that coarser dose grid sizes result in lower GPRs in peripheral low-dose regions as calculated by AXB with ArcCHECK™ measurement. To enhance GPR, employing split-arc methods and finer dose grid sizes could be beneficial.

Deterioration of Performance Status during Palliative Radiotherapy Suggests a Significant Short Survival Duration: Indicating the Necessities for Considering Radiotherapy Discontinuation.

Discontinuation of palliative radiotherapy due to a patient's declining general condition poses a clinical dilemma for palliative care physicians. This study aimed to investigate the survival duration of patients whose performance status (PS) deteriorated during palliative radiotherapy and inform decisions regarding early treatment discontinuation. We retrospectively analyzed data from patients referred from our institute's palliative care department who underwent ≥10 fractions of palliative radiotherapy between March 2017 and December 2021. PS was assessed using the Eastern Cooperative Oncology Group (ECOG) scale. Survival duration was calculated from the final day of palliative radiotherapy to death using the Kaplan-Meier method. A total of 35 patients underwent palliative radiotherapy. Seven (20%) experienced deterioration in ECOG PS during treatment. Their median survival duration was significantly shorter at 22 days (95% confidence interval: 1-94 days) compared to 125 days (95% confidence interval: 82-150 days) for the 28 patients whose PS remained stable (p = 0.0007). Deterioration in ECOG PS during palliative radiotherapy signifies a markedly shorter survival duration. Careful assessment of a patient's condition throughout treatment is crucial, and early discontinuation should be considered if their general health worsens rather than strictly adhering to the initial schedule.

The effect of arterial spin labeling MR angiography (ASL-MRA) in visualizing the branches of external carotid artery.

This study aimed to assess the performance of arterial-spin labeling MRA (ASL-MRA) for visualizing the external carotid artery (ECA) branches in comparison with time-of-flight MRA (TOF-MRA) and CT angiography (CTA). We retrospectively selected 31 consecutive patients, who underwent both MRAs and CTA, prior to the intra-arterial chemoradiotherapy (IACRT) for head and neck cancer. Four patients underwent IACRT bilaterally, so we analyzed 35 ECAs. Pseudo-continuous, three-dimensional ASL using a turbo field echo sequence was acquired. For the TOF-MRA and CTA, clinically used parameters were applied. Two observers evaluated each ECA branch with reference to the angiogram at the IACRT, using five-point scale, in consensus. Friedman test for multiple comparisons was applied. ASL-MRA and CTA better visualized the superior thyroid, lingual, facial, submental, transverse facial, and internal maxillary arteries (IMAs) better than TOF-MRA (p < 0.05). In addition, CTA was superior to ASL-MRA in visualizing only submental artery among these arteries (p = 0.0005). Alternatively, the ASL-MRA was superior for visualizing the middle meningeal artery (MMA) and IMA, compared to the CTA (p = 0.0001 and 0.0007, respectively). ASL-MRA was superior to the TOF-MRA and similar to the CTA in visualizing most of ECA branches. Furthermore, ASL-MRA can better visualize the periphery of MMA and IMA than CTA.

Multiparametric assessment of microvascular invasion in hepatocellular carcinoma using gadoxetic acid-enhanced MRI.

PURPOSE: To elucidate how precisely microvascular invasion (MVI) in hepatocellular carcinoma (HCC) can be predicted using multiparametric assessment of gadoxetic acid-enhanced MRI. METHODS: In this retrospective single-center study, patients who underwent liver resection or transplantation of HCC were evaluated. Data obtained in patients who underwent liver resection were used as the training set. Nine kinds of MR findings for predicting MVI were compared between HCCs with and without MVI by univariate analysis, followed by multiple logistic regression analysis. Using significant findings, a predictive formula for diagnosing MVI was obtained. The diagnostic performance of the formula was investigated in patients who underwent liver resection (validation set 1) and in patients who underwent liver transplantation (validation set 2) using a receiver operating characteristic curve analysis. The area under the curves (AUCs) of these three groups were compared. RESULTS: A total of 345 patients with 356 HCCs were selected for analysis. Tumor diameter (D) (P = 0.021), tumor washout (TW) (P < 0.01), and peritumoral hypointensity in the hepatobiliary phase (PHH) (P < 0.01) were significantly associated with MVI after multivariate analysis. The AUCs for predicting MVI of the predictive formula were as follows: training set, 0.88 (95% confidence interval (CI) 0.82,0.93); validation set 1, 0.81 (95% CI 0.73,0.87); validation set 2, 0.67 (95% CI 0.51,0.80). The AUCs were not significantly different among three groups (training set vs validation set 1; P = 0.15, training set vs validation set 2; P = 0.09, validation set 1 vs validation set 2; P = 0.29, respectively). CONCLUSION: Our multiparametric assessment of gadoxetic acid-enhanced MRI performed quite precisely and with good reproducibility for predicting MVI.

Survey on chest CT findings in COVID-19 patients in Okinawa, Japan: differences between the delta and omicron variants.

To investigate the frequency of pneumonia and chest computed tomography (CT) findings in patients with coronavirus disease 2019 (COVID-19) during the fifth Delta variant-predominant and sixth Omicron variant-predominant waves of the COVID-19 pandemic in Okinawa, Japan. A survey on chest CT examinations for patients with COVID-19 was conducted byhospitals with board-certified radiologists who provided treatment for COVID-19 pneumonia in Okinawa Prefecture. Data from 11 facilities were investigated. Indications for chest CT; number of COVID-19 patients undergoing chest CT; number of patients with late-onset pneumonia, tracheal intubation, and number of deaths; and COVID-19 Reporting and Data System classifications of initial chest CT scans were compared by the chi-squared test between the two pandemic waves (Delta vs. Omicron variants). A total of 1944 CT scans were performed during the fifth wave, and 1178 were performed during the sixth wave. CT implementation rates, which were the number of patients with COVID-19 undergoing CT examinations divided by the total number of COVID-19 cases in Okinawa Prefecture during the waves, were 7.1% for the fifth wave and 2.1% for the sixth wave. The rates of tracheal intubation and mortality were higher in the fifth wave. Differences between the distributions of the CO-RADS classifications were statistically significant for the fifth and sixth waves (p < 0.0001). In the fifth wave, CO-RADS 5 (typical of COVID-19) was most common (65%); in the sixth wave, CO-RADS 1 (no findings of pneumonia) was most common (50%). The finding of "typical for other infection but not COVID-19" was more frequent in the sixth than in the fifth wave (13.6% vs. 1.9%, respectively). The frequencies of pneumonia and typical CT findings were higher in the fifth Delta variant-predominant wave, and nontypical CT findings were more frequent in the sixth Omicron variant-predominant wave of the COVID-19 pandemic in Okinawa, Japan.

Prediction of Early-stage Liver Fibrosis Using FDG-PET/CT.

BACKGROUND/AIM: 18F-fluorodeoxyglucose (FDG) is known to accumulate in the liver. We investigated whether accumulation of FDG was correlated with the degree of liver fibrosis and the grade of necro-inflammatory activity. PATIENTS AND METHODS: This retrospective study included 35 patients who underwent FDG-positron emission tomography (PET)/computed tomography (CT) before liver surgery. On fusion images of CT and PET, by placing regions of interest on the lateral, anterior and posterior segments of the liver and the aorta, the standardized uptake value (SUV) mean, and SUV normalized by lean body mass (SUL) mean of the liver were measured, and the ratio SUVmean liver/SUVmean aorta was calculated. According to the New Inuyama Classification, subjects were classified into three groups based on the grade of liver-fibrosis degree, i.e., F0, F1+F2 and F3+F4, and into three groups based on the grade of necro-inflammatory activity, i.e., A0, A1 and A2. Each of the above parameters was then compared among the groups using a Tukey test. RESULTS: Average SULmean liver values of the F0, F1+F2 and F3+F4 groups were 1.573±0.211, 1.845±0.220 and 1.716±0.119, respectively. The SULmean liver of the F1+F2 group was significantly higher than that of the F0 group (p=0.0296). No significant difference was observed for the other two parameters. None of the parameters exhibited significant difference among the A0, A1, and A2 groups. CONCLUSION: FDG accumulation in the liver may be increased in the early stage of liver fibrosis. SULmean liver could be used to determine the necessity for therapeutic intervention in chronic liver disease.

Chronic thromboembolic pulmonary hypertension is associated with a loss of total lung volume on computed tomography.

BACKGROUND: Although lung volumes are usually normal in individuals with chronic thromboembolic pulmonary hypertension (CTEPH), approximately 20%-29% of patients exhibit a restrictive pattern on pulmonary function testing. AIM: To quantify longitudinal changes in lung volume and cardiac cross-sectional area (CSA) in patients with CTEPH. METHODS: In a retrospective cohort study of patients seen in our hospital between January 2012 and December 2019, we evaluated 15 patients with CTEPH who had chest computed tomography (CT) performed at baseline and after at least 6 mo of therapy. We matched the CTEPH cohort with 45 control patients by age, sex, and observation period. CT-based lung volumes and maximum cardiac CSAs were measured and compared using the Wilcoxon signed-rank test and the Mann-Whitney u test. RESULTS: Total, right lung, and right lower lobe volumes were significantly reduced in the CTEPH cohort at follow-up vs baseline (total, P = 0.004; right lung, P = 0.003; right lower lobe; P = 0.01). In the CTEPH group, the reduction in lung volume and cardiac CSA was significantly greater than the corresponding changes in the control group (total, P = 0.01; right lung, P = 0.007; right lower lobe, P = 0.01; CSA, P = 0.0002). There was a negative correlation between lung volume change and cardiac CSA change in the control group but not in the CTEPH cohort. CONCLUSION: After at least 6 mo of treatment, CT showed an unexpected loss of total lung volume in patients with CTEPH that may reflect continued parenchymal remodeling.

Diagnostic accuracy of percutaneous core biopsy before cryoablation for small-sized renal cell carcinoma.

PURPOSE: To retrospectively determine the diagnostic accuracy of a percutaneous core biopsy performed before cryoablation for small-sized renal cell carcinoma. METHODS: In this study, 216 patients underwent a percutaneous core biopsy for 242 renal lesions suspected to be renal cell carcinoma on image findings before cryoablation at Kyushu University Hospital. We calculated the success rate of the histological diagnosis and investigated factors that may have contributed to the diagnostic success. Complications caused by the biopsy procedure were also evaluated. RESULTS: The histological diagnosis was successful in 203 lesions (82.8%). The success rate of the histological diagnosis was 65.4% (34/52 cases) for tumors with a diameter of ≤15 mm and 88.9% (169/190 cases) for those >15 mm. Therefore, tumor diameter was a factor contributing to the histological diagnosis success rate in both univariate and multivariable analyses (P < 0.001). For lesions with a tumor diameter ≤15 mm, the histological diagnosis success rates increased from 50.0% to 76.2% in the presence of pre-lipiodol marking and to 85.7% when the biopsy procedure was performed separately from cryoablation; the latter was statistically significant (P = 0.039). Major complications that may have been caused by the biopsy procedure were grade 3 bleeding and tract seeding (one case each). CONCLUSION: Percutaneous core biopsy in cryoablation for small-sized renal cell carcinoma had a high diagnostic rate and was safely performed. For lesions with a tumor diameter ≤15 mm, a separate biopsy procedure and pre-lipiodol marking may improve the diagnostic accuracy.

A novel fast kilovoltage switching dual-energy computed tomography technique with deep learning: Utility for non-invasive assessments of liver fibrosis.

PURPOSE: To investigate whether the iodine density of liver parenchyma in the equilibrium phase and extracellular volume fraction (ECV) measured by deep learning-based spectral computed tomography (CT) can enable noninvasive liver fibrosis staging. METHOD: We retrospectively analyzed 63 patients who underwent dynamic CT using deep learning-based spectral CT before a hepatectomy or liver transplantation. The iodine densities of the liver parenchyma (I-liver) and abdominal aorta (I-aorta) were independently measured by two radiologists using iodine density images at the equilibrium phase. The iodine-density ratio (I-ratio: I-liver/I-aorta) and CT-ECV were calculated. Spearman's rank correlation analysis was used to evaluate the relationship between the I-ratio or CT-ECV and liver fibrosis stage, and receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performances of the I-ratio and CT-ECV. RESULTS: The I-ratio and CT-ECV showed significant positive correlations with liver fibrosis stage (ρ = 0.648, p < 0.0001 and ρ = 0.723, p < 0.0001, respectively). The areas under the ROC curve for the CT-ECV were 0.882 (F0 vs ≥ F1), 0.873 (≤F1 vs ≥ F2), 0.848 (≤F2 vs ≥ F3), and 0.891 (≤F3 vs F4). CONCLUSIONS: Deep learning-based spectral CT may be useful for noninvasive assessments of liver fibrosis.

MR Prediction of Malignant Switch With the Cyst Fluid's T2 Value in Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Preliminary Study.

BACKGROUND/AIM: We investigated whether the malignant switch of intraductal papillary mucinous neoplasm (IPMN) of the pancreas can be predicted by using the T1ϱ, T2, and apparent diffusion coefficient (ADC) values of cyst fluid. PATIENTS AND METHODS: We retrospectively analyzed the magnetic resonance (MR) images of 60 patients (26 males, 34 females, mean age 61 years) with branch-duct type and mixed-type IPMNs. The IPMNs were diagnosed clinically in 39 patients and histologically in 21 patients. The malignant potential was classified by MR imaging based on the international consensus guidelines for the management of IPMN established in 2017. Morphologically, 42 patients had "worrisome features" and three had "high-risk stigmata." Histologically, 14 lesions were diagnosed as low-grade dysplasia and seven as intermediate-grade dysplasia. The T1ϱ, T2, and ADC values of cyst fluid in each patient's largest cyst were measured on the same slice, avoiding solid components. Spearman's rank correlation test was used to determine the correlation between the morphological malignancy and the T1ϱ, T2, and ADC values. These values were also compared between the low-grade and intermediate-grade groups by Mann-Whitney U-test. RESULTS: There was a significant rank-correlation between the morphological classification and T2 value (p=0.04). The T2 value of the intermediate-grade group was significantly higher than that of the low-grade group (p=0.03). No significant correlations were morphologically or histologically obtained regarding T1ϱ and ADC. CONCLUSION: The T2 value of cyst fluid together with other MR-signs may be useful for predicting the malignant switch in IPMN of the pancreas.

A deep learning-based approach for the diagnosis of adrenal adenoma: a new trial using CT.

OBJECTIVE: To develop and validate deep convolutional neural network (DCNN) models for the diagnosis of adrenal adenoma (AA) using CT. METHODS: This retrospective study enrolled 112 patients who underwent abdominal CT (non-contrast, early, and delayed phases) with 107 adrenal lesions (83 AAs and 24 non-AAs) confirmed pathologically and with 8 lesions confirmed by follow-up as metastatic carcinomas. Three patients had adrenal lesions on both sides. We constructed six DCNN models from six types of input images for comparison: non-contrast images only (Model A), delayed phase images only (Model B), three phasic images merged into a 3-channel (Model C), relative washout rate (RWR) image maps only (Model D), non-contrast and RWR maps merged into a 2-channel (Model E), and delayed phase and RWR maps merged into a 2-channel (Model F). These input images were prepared manually with cropping and registration of CT images. Each DCNN model with six convolutional layers was trained with data augmentation and hyperparameter tuning. The optimal threshold values for binary classification were determined from the receiver-operating characteristic curve analyses. We adopted the nested cross-validation method, in which the outer fivefold cross-validation was used to assess the diagnostic performance of the models and the inner fivefold cross-validation was used to tune hyperparameters of the models. RESULTS: The areas under the curve with 95% confidence intervals of Models A-F were 0.94 [0.90, 0.98], 0.80 [0.69, 0.89], 0.97 [0.94, 1.00], 0.92 [0.85, 0.97], 0.99 [0.97, 1.00] and 0.94 [0.86, 0.99], respectively. Model E showed high area under the curve greater than 0.95. CONCLUSION: DCNN models may be a useful tool for the diagnosis of AA using CT. ADVANCES IN KNOWLEDGE: The current study demonstrates a deep learning-based approach could differentiate adrenal adenoma from non-adenoma using multiphasic CT.

Efficacy of Pre-operative 18F-FDG PET/CT in Prognostic Prediction in Patients With Renal Cell Carcinoma.

Background/Aim: This study analyzed the parameters provided by preoperative 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for prognostic prediction of renal cell carcinoma (RCC). Patients and Methods: FDG-PET/CT data from 66 clear cell RCC and 19 non-clear cell RCC cases between January 2015 and October 2018 were reviewed retrospectively. We compared the two groups according to recurrence/metastasis to determine prognosis-influencing factors. Multivariate Cox hazard regression models were constructed to evaluate factors potentially predicting disease-free survival (DFS) after adjustment for confounders. DFS was then compared between groups. Results: Standardized uptake values (SUV) of the PET/CT scan were independent predictors of prognosis after adjusting for confounders. RCC cases were divided into two groups by optimal cut-off values. Differences between DFS percentages in high and low SUV groups were significant. Similar results were obtained in clear cell RCC groups. Conclusion: Increased SUV of the PET/CT scan are significant predictors of worse prognoses in patients with surgically resected RCC.

Importance of the heart rate in ultra-high-resolution coronary CT angiography with 0.35 s gantry rotation time.

PURPOSE: We investigated the effects of the heart rate (HR) on the motion artifact in coronary computed tomography angiography (CCTA) with ultra-high-resolution-CT (U-HRCT), and we clarified the upper limit of optimal HR in CCTA with U-HRCT in a comparison with conventional-resolution-CT (CRCT) on a cardiac phantom and in patients with CCTA. MATERIALS AND METHODS: A pulsating cardiac phantom equipped with coronary models was scanned at static and HR simulations of 40-90 beats/min (bpm) at 10-bpm intervals using U-HRCT and CRCT, respectively. The sharpness and lumen diameter of the coronary model were quantitatively compared between U-HRCT and CRCT stratified by HR in the phantom study. We also assessed the visual inspections of clinical images in CCTA with U-HRCT. RESULTS: At the HRs ≤ 60 bpm, the error of the lumen diameter of the U-HRCT tended to be smaller than that of the CRCT. However, at the HRs > 60 bpm, the inverse was shown. For the image sharpness, the U-HRCT was significantly superior to the CRCT (p < 0.05). In the visual assessment, the scores were negatively correlated with HRs in patients (Spearman r = - 0.71, p < 0.01). A receiver-operating characteristic analysis revealed the HR of 61 bpm as the optimal cutoff of the non-diagnostic image quality, with an area under the curve of 0.87, 95% sensitivity, and 71% specificity. CONCLUSION: At HRs ≤ 60 bpm, U-HRCT was more accurate in the imaging of coronary arteries than CRCT. The upper limit of the optimal HR in CCTA with U-HRCT was approx. 60 bpm.

Stratification of prostate cancer patients into low- and high-grade groups using multiparametric magnetic resonance radiomics with dynamic contrast-enhanced image joint histograms.

PURPOSE: This study aimed to investigate the potential of stratification of prostate cancer patients into low- and high-grade groups (GGs) using multiparametric magnetic resonance (mpMR) radiomics in conjunction with two-dimensional (2D) joint histograms computed with dynamic contrast-enhanced (DCE) images. METHODS: A total of 101 prostate cancer regions extracted from the MR images of 44 patients were identified and divided into training (n = 31 with 72 cancer regions) and test datasets (n = 13 with 29 cancer regions). Each dataset included low-grade tumors (International Society of Urological Pathology [ISUP] GG ≤ 2) and high-grade tumors (ISUP GG ≥ 3). A total of 137,970 features consisted of mpMR image (16 types of images in four sequences)-based and joint histogram (DCE images at 10 phases)-based features for each cancer region. Joint histogram features can visualize temporally changing perfusion patterns in prostate cancer based on the joint histograms between different phases or subtraction phases of DCE images. Nine signatures (a set of significant features related to GGs) were determined using the best combinations of features selected using the least absolute shrinkage and selection operator. Further, support vector machine models with the nine signatures were built based on a leave-one-out cross-validation for the training dataset and evaluated with receiver operating characteristic (ROC) curve analysis. RESULTS: The signature showing the best performance was constructed using six features derived from the joint histograms, DCE original images, and apparent diffusion coefficient maps. The areas under the ROC curves for the training and test datasets were 1.00 and 0.985, respectively. CONCLUSION: This study suggests that the proposed approach with mpMR radiomics in conjunction with 2D joint histogram computed with DCE images could have the potential to stratify prostate cancer patients into low- and high-GGs.

Diagnostic potential of T1ρ and T2 relaxations in assessing the severity of liver fibrosis and necro-inflammation.

PURPOSE: To investigate the utility of T1ρ and T2 relaxations for assessing the severity of liver fibrosis (F stage) and necro-inflammation (A stage) in patients with chronic liver disease (CLD). MATERIALS AND METHODS: We calculated T1ρ and T2 relaxations of the liver parenchyma in 82 patients who underwent liver surgery. F and A stages of enrolled patients were assessed by referring to surgically resected specimens. The relationships between T1ρ or T2 relaxation and F or A stage were assessed using one-way analysis of variance followed by Tukey's multiple comparison test, Spearman's rank correlation test and a receiver operating characteristic analysis. RESULTS: The T1ρ and T2 values of the liver parenchyma were significantly increased as the F and A stages progressed. The T1ρ and T2 values showed significant differences between F0 and F4, between F1 and F4, and between F2 and F4. In addition, T1ρ values showed a significant difference between F0 and F3 as well. The highest diagnostic ability for fibrosis was obtained when differentiating ≥F3 from ≤F2 using T1ρ: the sensitivity was 82.8%, the specificity 79.2% and the area under the curve (AUC) 0.87. The sensitivity and AUC of T1ρ relaxation (46.9% and 0.67) were significantly higher than those of T2 relaxation (29.7% and 0.60) for differentiating ≥A1 from A0. CONCLUSION: T1ρ and T2 relaxations have potential as a biochemical marker for assessing the severity of liver fibrosis and necro-inflammation. T1ρ relaxation may be slightly superior to T2 relaxation in terms of diagnostic ability for liver fibrosis and necro-inflammation.

Palliative Radiation Therapy without Chemotherapy for a Patient with Monomorphic Epitheliotropic Intestinal T Cell Lymphoma: A Case Report.

Monomorphic epitheliotropic intestinal T cell lymphoma (MEITL), which used to be known as type 2 enteropathy-associated T cell lymphoma, is a rare lymphoma and is generally treated with chemotherapy. However, the MEITL prognosis is poor, and intestinal lymphoma including MEITL has the risk of bowel perforation not only at presentation but also during chemotherapy. A 67-year-old man was diagnosed with MEITL after presenting in our emergency room with bowel perforation. He and his family did not opt for the administration of anticancer drugs because of the risk of bowel perforation. However, they wanted the patient to receive palliative radiation therapy without chemotherapy. This treatment shrunk the tumor size without causing severe complications or decline in the quality of life, until he accidentally died due to traumatic intracranial hematoma. Considering the potential efficacy and safety of this treatment, it should be studied in more patients with MEITL.

Differentiating Liver Hemangioma from Metastatic Tumor Using T2-enhanced Spin-echo Imaging with a Time-reversed Gradient-echo Sequence in the Hepatobiliary Phase of Gadoxetic Acid-enhanced MR Imaging.

PURPOSE: To evaluate the utility of T2-enhanced spin-echo imaging using the time-reversed gradient echo sequence (T2FFE imaging) in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI (Gd-EOB-MRI) for differentiating hemangiomas from metastatic tumors. METHODS: A total of 61 patients with 133 liver lesions, including 37 hemangiomas and 96 metastatic tumors, were scanned by Gd-EOB-MRI. Four data sets were independently analyzed by two readers: (1) 3D fat-suppressed T2-weighted imaging (FS-T2WI) alone; (2) the combination of 3D FS-T2WI and T2FFE imaging in the HBP of Gd-EOB-MRI; (3) the combination of 3D FS-T2WI, diffusion-weighted imaging (DWI) with the b-value of 1000 s/mm2 and the apparent diffusion coefficient (ADC); and (4) a dynamic study of Gd-EOB-MRI. After classifying the lesion sizes as ≤ 10 mm or > 10 mm, we conducted a receiver-operating characteristic analysis to compare diagnostic accuracies among the four data sets for differentiating hemangiomas from metastatic tumors. RESULTS: The areas under the curves (AUCs) of the four data sets of two readers were: (1) ≤ 10 mm (0.85 and 0.91) and > 10 mm (0.88 and 0.97), (2) ≤ 10 mm (0.94 and 0.94) and > 10 mm (0.96 and 0.95), (3) ≤ 10 mm (0.90 and 0.87) and > 10 mm (0.89 and 0.95), and (4) ≤ 10 mm (0.62 and 0.67) and > 10 mm (0.76 and 0.71), respectively. Data sets (2) and (3) showed no significant differences in AUCs, but both showed significantly higher AUCs compared to that of (4) regardless of the lesion size (P < 0.05). CONCLUSION: The combination of 3D FS-T2WI and T2FFE imaging in the HBP of Gd-EOB-MRI achieved an accuracy equivalent to that of the combination of 3D FS-T2WI, DWI, and ADC and might be helpful in differentiating hemangiomas from metastatic tumors.

Kerley A-lines represent thickened septal plates between lung segments in patients with lymphangitic carcinomatosis: confirmation using 3D-CT lung segmentation analysis.

PURPOSE: Kerley A-lines are generally apparent in patients with pulmonary edema or lymphangitic carcinomatosis. There are two main thoughts regarding the etiology of Kerley A-lines, but no general agreement. Specifically, the lines are caused by thickened interlobular septa or dilated anastomotic lymphatics. Our purpose was to determine the anatomic structure represented as Kerley A-lines using 3D-CT lung segmentation analysis. MATERIALS AND METHODS: We reviewed 139 charts of patients with lymphangitic carcinomatosis of the lung who had CT and X-ray exams with a maximum interval of 7 days. The presence of Kerley A-lines on X-ray was assessed by a radiologist. The A-lines on X-ray were defined as follows: dense; fine (< 1 mm thick); ≥ 2 cm in length, radiating from the hilum; no bifurcation; and not adjacent to the pleura. For cases with Kerley A-lines on X-ray, three radiologists agreed that the lines on CT corresponded with Kerley A-lines. The incidence of A-lines and the characteristics of the lines were investigated. The septal lines between lung segments were identified using a 3D-CT lung segmentation analysis workstation. The percentage of agreement between the A-lines on CT and lung segmental lines was assessed. RESULTS: On chest X-ray, 37 Kerley A-lines (right, 16; left, 21) were identified in the 22 cases (16%). Of these, 4 lungs with 12 lines were excluded from analysis due to technical reasons. Nineteen of the 25 lines (76%) corresponded to the septal lines on CT. Of these, 11 lines matched with automatically segmented lines (intersegmental septa, 4; intersubsegmental septa, 7) by the workstation. Two lines (8%) represented fissures. Four lines corresponded to the bronchial wall/artery (3 lines, 12%) or vein (1 line, 4%). CONCLUSION: Kerley A-lines primarily represented thickened and continued interlobular septal lines that corresponded to the septa between lung segments and subsegments.

Optimization of 4D-MR angiography based on superselective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) for vessel-selective visualization of the internal carotid artery and vertebrobasilar artery systems.

PURPOSE: This study investigated the optimal labeling position and gradient moment for 4D-MR angiography based on superselective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) for vessel-selective flow visualization of the internal carotid artery (ICA) and vertebrobasilar artery (VBA) systems. METHODS: Seven healthy volunteers were scanned with a 3.0 T MR scanner. To visualize the ICA system, the labeling focus was placed in the right ICA at 55, 75 and 95 mm below the imaging slab. To visualize the VBA system, the labeling focus was placed in the basilar artery (BA), upper vertebral artery (VA upper), and lower vertebral artery (VA lower). Two sizes of labeling focus were created using gradient moments of 0.5 and 0.75 mT/m ms. The contrast-to-noise ratio (CNR) was measured in the middle cerebral artery (MCA) and posterior cerebral artery (PCA) branches. RESULTS: CNRs increased as the distance between the center of the imaging slab and the labeling position decreased in all MCA segments. CNRs obtained with VA lower tended to be higher than those obtained with BA and VA upper in all PCA segments. Selective vessel visualization was achieved with the gradient moment of 0.75 mT/m ms for the ICA and VBA system. CONCLUSION: The optimal 4D-S-PACK gradient moment was found to be 0.75 mT/m ms for the ICA and VBA systems. When visualizing the ICA system, the labeling position should be placed as close as possible to the imaging slab. When visualizing the VBA system, the labeling position should be placed at VA lower .

Primary diffuse leptomeningeal atypical teratoid rhabdoid tumor (AT/RT) demonstrating atypical imaging findings in an adolescent patient.

Atypical teratoid rhabdoid tumor (AT/RT) is a highly malignant central nervous system embryonal tumor, which typically affects the posterior fossa of young children. Primary diffuse leptomeningeal AT/RT, affecting the leptomeninges without any intraparenchymal mass in the brain and spinal cord, is an extremely rare form of AT/RT. Only 5 such cases have been reported previously, none of which underwent Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography (FDG-PET). We herein report a case of primary leptomeningeal AT/RT in an adolescent patient who underwent computed tomography, magnetic resonance imaging and FDG-PET. The computed tomography and magnetic resonance imaging indicated diffusely thickened leptomeninges without any intraparenchymal masses in the head and spine. Furthermore, there were multiple nodules on the thickened leptomeninges. On FDG-PET, the thickened leptomeninges and nodules demonstrated a lower standardized uptake value than that of the normal cerebral cortex. Biopsy and histopathological studies confirmed the diagnosis of AT/RT. Despite its rare occurrence, it is important to recognize primary diffuse leptomeningeal AT/RT for correct diagnosis and management of patients.