Characteristic computed tomography features in mesenchymal-epithelial transition exon14 skipping-positive non-small cell lung cancer.

BACKGROUND: Mesenchymal-epithelial transition exon14 (METex14) skipping is one of the therapeutic driver oncogene mutations in non-small cell lung cancer (NSCLC), and can be treated with tepotinib and capmatinib. There is only one report on computed tomography (CT) findings of METex14 skipping-positive NSCLC, which shows that the primary tumor tends to have a large mass in the upper lobe, and extrathoracic metastases are common. This study examined the CT findings of METex14 skipping-positive NSCLC, focusing on the features of the margins and internal structures. METHODS: We consecutively included patients with METex14 skipping-positive NSCLC who were diagnosed between January 2018 and December 2020 at four independent institutions. We retrospectively reviewed the patient demographics and CT findings for tumor margins (invasion into surrounding tissue, lobulation, pleural indentation, spicula, and ground-glass opacity) and internal structures (air bronchograms, cavitation and internal low-density area). RESULTS: Fifteen patients with METex14 skipping-positive NSCLC were identified. Almost half of the patients were men (7/15; 46.7%), and their median age was 75.0 years. More than half were either current or former smokers (9/15; 60.0%). A vast majority of histological subtypes were adenocarcinoma (10/15; 66.7%), followed by pleomorphic carcinoma (3/15; 20.0%) and squamous cell carcinoma (2/15; 13.3%). With regard to CT findings, most primary tumors presented as masses larger than 30 mm (12/15; 80.0%) and were located in the upper lobes (12/15; 80.0%). Invasion into surrounding tissue and presence of internal low-density areas were observed in 60.0% (9/15) and 66.7% (10/15) of the primary tumors, respectively. Additionally, their frequencies increased to 72.7% (8/11) and 90.9% (10/11) in stage III/IV cases, respectively. In lymph node metastasis, internal low-density areas were observed in 8/10 cases (80.0%). Although these two CT features were rarely observed in distant metastases at diagnosis, they became apparent with progression of the metastatic tumor size. CONCLUSIONS: METex14 skipping-positive NSCLC tumors tend to invade surrounding tissue and possess internal low-density areas. These CT findings might be characteristic of METex14 skipping-positive NSCLC.

Tumor contact length of prostate cancer determined by a three-dimensional method on multiparametric magnetic resonance imaging predicts extraprostatic extension and biochemical recurrence.

OBJECTIVE: To evaluate the clinical benefit of tumor contact length as a predictor of pathological extraprostatic extension and biochemical recurrence in patients undergoing prostatectomy. METHODS: A total of 91 patients who underwent 3T multiparametric magnetic resonance imaging before prostatectomy from April 2014 to July 2019 were included. A total of 94 prostate cancer foci were analyzed retrospectively. We evaluated maximum tumor contact length, which was determined to be the maximum value in the three-dimensional directions, as a predictor of pathological extraprostatic extension and biochemical recurrence. RESULTS: A total of 19 lesions (20.2%) had positive pathological extraprostatic extension. Areas under the curves showed maximum tumor contact length to be a significantly better parameter to predict pathological extraprostatic extension than the Prostate Imaging Reporting and Data System (P = 0.002), tumor maximal diameter (P = 0.001), prostate-specific antigen (P = 0.020), Gleason score (P < 0.001), and clinical T stage (P < 0.001). Multivariate analysis showed maximum tumor contact length (P = 0.003) to be an independent risk factor for predicting biochemical recurrence. We classified the patients using preoperative factors (prostate-specific antigen >10, Gleason score >3 + 4 and maximum tumor contact length >10 mm) into three groups: (i) high-risk group (patients having all factors); (ii) intermediate-risk group (patients having two of three factors); and (iii) low-risk group (patients having only one or none of the factors). Kaplan-Meier curves showed that the high-risk group had significantly worse biochemical recurrence than the intermediate-risk group (P = 0.042) and low-risk group (P < 0.001). CONCLUSIONS: Our findings suggest that maximum tumor contact length is an independent predictor of pathological extraprostatic extension and biochemical recurrence. A risk stratification system using prostate-specific antigen, Gleason score and maximum tumor contact length might be useful for preoperative assessment of prostate cancer patients.

Validity of the source term for the Fukushima Dai-ichi Nuclear Power Station accident estimated using local-scale atmospheric dispersion simulations to reproduce the large-scale atmospheric dispersion of 137Cs.

The source term of 137Cs from the Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident was estimated from the results of local-scale atmospheric dispersion simulations and measurements. To confirm the source term's validity for reproducing the large-scale atmospheric dispersion of 137Cs, this study conducted hemispheric-scale atmospheric and oceanic dispersion simulations. In the dispersion simulations, the atmospheric-dispersion database system Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI)-DB and oceanic dispersion model SEA-GEARN-FDM that were developed by the Japan Atomic Energy Agency were used. Compared with the air concentrations of 137Cs measured by the Comprehensive Nuclear-Test-Ban Treaty Organization, overall, the WSPEEDI-DB simulations well reproduced the measurements, whereas the simulation results partly overestimated some measurements. Furthermore, the validity of the deposition of 137Cs by WSPEEDI-DB was investigated using SEA-GEARN-FDM and concentrations of 137Cs in seawater sampled from the North Pacific. Seawater concentrations of 137Cs by the oceanic dispersion simulation, in which the deposition flux of 137Cs by WSPEEDI-DB was used as input from the atmosphere to oceans, were statistically consistent to the measurement. However, the simulated seawater concentrations of 137Cs were underestimated regionally in the North Pacific. Both the overestimation of air concentrations and underestimation of seawater concentrations could be attributed to the less amounts of 137Cs deposition by less precipitation over the North Pacific. The overestimation and underestimation could be improved without contradiction between the air and seawater concentrations of 137Cs using more realistic precipitation in atmospheric dispersion simulations. This shows that the source term validated in this study could reproduce the spatiotemporal distribution of 137Cs from the FDNPS accident in both local and large-scale atmospheric dispersion simulations.

Extent of pulmonary fibrosis on high-resolution computed tomography is a prognostic factor in patients with pleuroparenchymal fibroelastosis.

BACKGROUND: Several prognostic factors for pleuroparenchymal fibroelastosis (PPFE) have recently been reported. However, detailed high-resolution computed tomography (HRCT) findings have not yet been evaluated as prognostic factors. This study retrospectively investigated whether HRCT findings are prognostic factors in patients with PPFE compared to those with idiopathic pulmonary fibrosis (IPF). METHODS: Patients with PPFE and IPF diagnosed at our hospital between January 2008 and December 2016 were enrolled. Clinical and HRCT characteristics were obtained. In addition to our patients, we also analyzed data of PPFE patients whose cause of death had been identified in previous studies. RESULTS: We enrolled 15 patients with PPFE and 75 patients with IPF. Consolidation and maximum pleural thickening were significantly higher in patients with PPFE than in those with IPF (both P < .001). Fibrosis score, honeycomb area, and traction bronchiectasis were not significantly different between these patient groups but were significant prognostic factors in patients with PPFE in univariate analysis (P = .021, P = .017, and P = .014, respectively). The proportions of deaths by acute exacerbation or lung cancer were significantly lower in patients with PPFE than in those with IPF (P < .001 and P = .001, respectively), whereas death by respiratory failure was significantly more frequent in PPFE patients (P < .001). CONCLUSIONS: HRCT findings, such as fibrosis score, honeycomb area, and traction bronchiectasis, were independent prognostic factors in patients with PPFE. Respiratory failure, but not acute exacerbation and lung cancer, was the main cause of death in patients with PPFE.

Refinement of source term and atmospheric dispersion simulations of radionuclides during the Fukushima Daiichi Nuclear Power Station accident.

To assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in Japan, especially for the early phase of the accident when no measured data are available for that purpose, the spatial and temporal distributions of radioactive materials in the environment need to be reconstructed through computer simulations using the atmospheric transport, dispersion, and deposition model (ATDM). For the ATDM simulation, the source term of radioactive materials discharged into the atmosphere is essential and has been estimated in many studies. In the present study, we further refined the source term estimated in our previous study and improved the ATDM simulation with an optimization method based on Bayesian inference, which used various measurements such as air concentration, surface deposition, fallout, and newly released hourly air concentrations of 137Cs derived by analyzing suspended particulate matter (SPM) collected at air pollution monitoring stations. This optimization improved not only the source term but also the wind field in meteorological calculation, which led to the reduction of discrepancies in plume passage time at monitoring points to less than 3 h between calculations and measurements, by feeding back comparison results between the dispersion calculations and measurements of radionuclides. As a result, the total amounts of 137Cs and 131I by the present study became 1.0 × 1016 and 1.2 × 1017 Bq, respectively, and decreased by 29% and 20%, respectively, in comparison with those by previous study. The ATDM simulation successfully reproduced both the air concentrations at SPM monitoring points and surface depositions by airborne monitoring. FA10 for total samples of air concentrations of 137Cs at SPM monitoring points increased from 35.9% by the previous study to 47.3%. The deposition amount on the land decreased from 3.7 × 1015 Bq by the previous study to 2.1 × 1015 Bq, which was close to the measured amount of 2.4 × 1015 Bq. We also constructed the spatiotemporal distribution of some major radionuclides in the air and on the surface (optimized dispersion database) by using the optimized release rates and ATDM simulations. The optimized dispersion database can be used for comprehensive dose assessment in tandem with behavioral patterns of evacuees from the FDNPS accident by collaborating research group in the Japanese dose assessment project. The improvements in the present study lead to the refinement of the dose estimation.

Processes affecting land-surface dynamics of 129I impacted by atmospheric 129I releases from a spent nuclear fuel reprocessing plant.

Terrestrial environments impacted by atmospheric releases of 129I from nuclear plants become contaminated with 129I; however, the relative importance of each land-surface 129I-transfer pathway in the process of the contamination is not well understood. In this study, transfers of 129I in an atmosphere-vegetation-soil system are modeled and incorporated into an existing land-surface model (SOLVEG-II). The model was also applied to the observed transfer of 129I at a vegetated field impacted by atmospheric releases of 129I (as gaseous I2 and CH3I) from the Rokkasho reprocessing plant, Japan, during 2007. Results from the model calculation and inter-comparison of the results with the measured environmental samples provide insights into the relative importance of each 129I-transfer pathway in the processes of 129I contamination of leaves and soil. The model calculation revealed that contamination of leaves of wild bamboo grasses was mostly caused by foliar adsorption of inorganic 129I (81%) following wet deposition of 129I. In contrast, accumulation of 129I in the leaf due to foliar uptake of atmospheric 129I2 (2%) was lesser. Root uptake of soil 129I was low, accounted for 17% of the 129I of the leaf. The low root-uptake of 129I in spite of the 129I contained in the soil was ascribed to the fact that the most fraction (over 90%) of the soil 129I existed in "soil-fixed" (not plant-available) form. Regarding the 129I-transfer to the soil, wet deposition of 129I was ten-fold more effective than dry deposition of atmospheric 129I2; however, the deposition of 129I during the year represented only 2% of the model-assumed 129I that pre-existed in the soil; indicating the importance of long-term accumulation of 129I in terrestrial environments. The model calculation also revealed that root uptake of inorganic 129I can be more influential than volatilization by methylation in exportation of 129I from soil.

Magnetic resonance imaging/transrectal ultrasonography fusion targeted prostate biopsy finds more significant prostate cancer in biopsy-naïve Japanese men compared with the standard biopsy.

OBJECTIVE: To assess the clinical benefits of magnetic resonance imaging/transrectal ultrasound fusion-targeted biopsy for biopsy-naïve Japanese men. METHODS: Between February 2017 and August 2018, 131 biopsy-naïve men who underwent targeted biopsy together with 10-core systematic biopsy at Hiroshima University Hospital were retrospectively investigated. Multiparametric magnetic resonance imaging findings were reported based on Prostate Imaging Reporting and Data System version 2. RESULTS: The overall cancer detection rates per patient were 69.5% in systematic biopsy + targeted biopsy cores, 61.1% in systematic biopsy cores and 61.1% in targeted biopsy cores. The detection rates for clinically significant prostate cancer were 43.5% in targeted biopsy cores and 35.9% in systematic biopsy cores (P = 0.04), whereas the detection rates for clinically insignificant prostate cancer were 17.6% and 25.2% respectively (P = 0.04). Lesions in the peripheral zone were diagnosed more with clinically significant prostate cancer (54.8% vs 20.7%, P < 0.001) and International Society of Urological Pathology grade (3.2 vs 2.7, P = 0.02) than that in the inner gland. Just 4.2% (3/71) of Prostate Imaging Reporting and Data System category 2 and 3 lesions in the middle or base of the inner gland were found to have clinically significant prostate cancer. The cancer detection rate per core was 42.3% in targeted biopsy cores, whereas it was 17.9% in systematic biopsy cores (P < 0.001). CONCLUSIONS: Targeted biopsy is able to improve the diagnostic accuracy of biopsy in detection of clinically significant prostate cancer by reducing the number of clinically insignificant prostate cancer detections compared with 10-core systematic biopsy in biopsy-naïve Japanese men. In addition, the present findings suggest that patients with Prostate Imaging Reporting and Data System category 2 or 3 lesions at the middle or base of the inner gland might avoid biopsies.

Clinical staging of upper urinary tract urothelial carcinoma for T staging: Review and pictorial essay.

Upper urinary tract urothelial carcinoma is staged using the TNM classification of malignant tumors. Preoperative TNM is important for treatment planning. Computed tomography urography is now widely used for clinical survey of upper urinary tract carcinoma because of its diagnostic accuracy. Computed tomography urography is recommended as the first-line imaging procedure in several guidelines. Several reports stated that computed tomography urography is also useful for staging. However, no educational and practical reviews detailing the T staging of upper urinary tract urothelial carcinomas using imaging are available. We discuss the scanning protocol, T staging using computed tomography urography, limitations, magnetic resonance imaging, computed tomography comparison and pitfalls in imaging of upper urinary tract urothelial carcinoma. A recent study reported the high diagnostic accuracy of computed tomography urography with respect to T3 or higher stage tumors. To date, images that show a Tis-T2 stage have not been reported, but various studies are ongoing. Although magnetic resonance imaging has lower spatial resolution than computed tomography urography, magnetic resonance imaging can be carried out without radiation exposure or contrast agents. Magnetic resonance imaging also offers the unique ability of diffusion-weighted imaging without contrast agent use. Some researchers reported that diffusion-weighted imaging is useful not only for detecting lesions, but for predicting the T stage and tumor grade. We recommend the appropriate use of computed tomography and magnetic resonance while considering the limitations of each modality and the pitfalls in upper urinary tract urothelial carcinoma imaging.

Pustules on the back possibly triggering toxic-shock syndrome.

We herein describe an irregular case of toxic-shock syndrome (TSS). A previously healthy 28-year-old Japanese man developed a sudden-onset high fever. The patient was suffering from conjunctival hyperaemia, gastrointestinal symptoms such as vomiting and diarrhoea, and systemically diffused macular erythroderma. Further physical examination detected pustules on his back, which self-destructed over time. Laboratory revealed multiple organ failures. Subsequently, scalded skin on the face and desquamation in the limb extremities emerged by day 10, leading to the diagnosis of TSS, despite his stable circulatory dynamics through the course. Learning points for clinicians include that they should recall TSS as a possible disease concurrently causing high fever, systemic rash and multiple organ dysfunctions, even without being in a state of shock. The characteristic desquamations emerged in the limb extremities after hospitalisation were of help in diagnosing TSS.

Thyroid-associated Orbitopathy: Quantitative Evaluation of the Orbital Fat Volume and Edema Using IDEAL-FSE.

BACKGROUND AND PURPOSE: To compare orbital quantitative data obtained by fast spin-echo iterative decomposition of water and fat with echo asymmetry and least-squares estimation (FSE-IDEAL) in patients with thyroid-associated orbitopathy (TAO) and healthy controls and to investigate the characteristics of these data in TAO patients. MATERIALS AND METHODS: Twenty-two TAO patients (4 males and 18 females; median age 51.0 years) and 22 healthy subjects (5 males and 17 females; median age 50.5 years) underwent orbital T2-weighted FSE-IDEAL. The water fraction in orbital fat was defined as the signal intensity (SI) water / (SI water + SI fat). The orbital fat volume was measured on fat images. The degree of proptosis was evaluated using in-phase imaging. Mann-Whitney U test was used to compare these quantitative data in the two groups. In TAO patients we ascertained the correlation among these values with the Spearman's rank correlation coefficient. RESULTS: In TAO patients, the water fraction (right and left, p = 0.04), fat volume (right and left, p = 0.03) and degree of proptosis (right and left, p < 0.01) were higher than in the controls. In TAO patients, only the water fraction and the fat volume of left orbit showed negative correlation (p = 0.01). CONCLUSION: The water fraction of orbital fat, the orbital fat volume and the degree of proptosis obtained with FSE-IDEAL were higher in TAO patients than in the controls. The water fraction was a new parameter for differentiating between TAO patients and healthy subjects.

Anastomosing haemangioma with fatty changes in the perirenal space: a lesion mimicking liposarcoma.

Anastomosing haemangioma is a rare subtype of capillary haemangioma. Pathologically, anastomosing haemangioma presents with anastomosing sinusoidal capillary-sized vessels in an architecture reminiscent of the splenic parenchyma. Its anastomosing architecture pathologically can lead to concern for angiosarcoma. Many cases of anastomosing haemangioma, which often occurred in the retroperitoneum, were well circumscribed, hyperdense on plain CT, revealed avid contrast enhancement and some of them exhibited fatty changes. In cases of tumours with fat of retroperitoneal occurrence, images frequently do not allow for easy differentiation from liposarcoma. Although anastomosing haemangioma with fatty changes and liposarcoma can be difficult to differentiate, no previous report has addressed this diagnostic difficulty. We have encountered a case of anastomosing haemangioma with fatty changes occurring in the perirenal space that was difficult to differentiate from liposarcoma. With retroperitoneal tumours accompanied by fatty changes and including a strongly enhanced area, the possibility of anastomosing haemangioma-which is a benign tumour-may also be considered. In such cases, biopsy is an effective means of diagnosis.

Tubulocystic renal cell carcinoma: a review of literature focused on radiological findings for differential diagnosis.

Tubulocystic renal cell carcinoma (TC-RCC) has been classified as an independent subtype according to the 2016 World Health Organization (WHO) classification. It is a rare subtype that predominantly affects men. Although few in number, radiological imaging reports have suggested that TC-RCC is characterized by multilocular cystic lesions, which are categorized as the Bosniak classification II-IV, with signature pathological characteristics comprising numerous small cysts or a tubular structure. The Bosniak classification system facilitates patient management; however, the differentiation of cystic tumors exhibiting similar imaging findings remains impossible; in fact, the differentiation of multilocular cystic RCC, adult cystic nephroma, and mixed epithelial and stromal tumor remains challenging. This review aims to discuss TC-RCC with a focus on implications of radiological findings in the differential diagnosis of TC-RCC.

Clinical Indication for Computed Tomography During Hepatic Arteriography (CTHA) in Addition to Dynamic CT Studies to Identify Hypervascularity of Hepatocellular Carcinoma.

PURPOSE: To identify factors benefiting from computed tomography during hepatic arteriography (CTHA) in addition to dynamic CT studies at the preoperative evaluation of the hypervascularity of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: We retrospectively divided 45 patients with HCC, who underwent both dynamic CT (dCT) and CTHA, into two groups based on the number of hypervascular HCCs identified on dCT and CTHA studies. In group A, the number of HCCs identified by dCT and CTHA was the same and additive CTHA had not been indicated. In group B, fewer HCCs were counted on dCT than on CTHA images, indicating that additive CTHA studies had been appropriate. We compared the patient characteristics, the serum alpha-fetoprotein level, and the tumor-liver contrast (TLC) of the main tumor on dCT scans of both groups. To identify factors alerting to the benefit of additional CTHA studies, we performed univariate logistic regression analysis. Statistically significant parameters were subjected to receiver operating characteristic analysis for obtaining the optimal cutoff value indicative of the benefit of CTHA. RESULTS: Univariate analysis identified only the TLC of the main tumor on dCT images as a significant factor for the benefit of CTHA images (P < 0.01). At the optimal cutoff value for the TLC of the main tumor on dCT images (15.9 Hounsfield units), the sensitivity and specificity for the benefit of CTHA were 85.0 and 92.0%, respectively. CONCLUSION: Evaluation of the TLC of the main tumor on dCT scans identifies patients in whom additive CTHA studies are beneficial.

Preliminary Results of High-Precision Computed Diffusion Weighted Imaging for the Diagnosis of Hepatocellular Carcinoma at 3 Tesla.

OBJECTIVE: To compare the utility of high-precision computed diffusion-weighted imaging (hc-DWI) and conventional computed DWI (cc-DWI) for the diagnosis of hepatocellular carcinoma (HCC) at 3 T. METHODS: We subjected 75 HCC patients to DWI (b-value 150 and 600 s/mm). To generate hc-DWI we applied non-rigid image registration to avoid the mis-registration of images obtained with different b-values. We defined c-DWI with a b-value of 1500 s/mm using DWI with b-value 150 and 600 s/mm as cc-DWI, and c-DWI with b-value 1500 s/mm using registered DWI with b-value 150 and 600 s/mm as hc-DWI. A radiologist recorded the contrast ratio (CR) between HCC and the surrounding hepatic parenchyma. RESULTS: The CR for HCC was significantly higher on hc- than cc-DWIs (median 2.0 vs. 1.8, P < 0.01). CONCLUSION: The CR of HCC can be improved with image registration, indicating that hc-DWI is more useful than cc-DWI for the diagnosis of HCC.

Imaging features of papillary renal cell carcinoma with cystic change-dominant appearance in the era of the 2016 WHO classification.

PURPOSE: Papillary renal cell carcinoma (P-RCC) typically exhibits a homogeneous, solid hypovascular mass; P-RCC with a cystic appearance is atypical. Tubulocystic RCC (TC-RCC), a newly proposed entity for renal tumors in the 2016 WHO classification, and cystic papillary RCC, may yield similar imaging findings. Therefore, we investigated the incidence of papillary RCC with cystic changes and compared its CT and pathologic features to differentiate between two entities. METHODS: We retrospectively evaluated 26 consecutive patients diagnosed with P-RCC. Two radiologists consensually identified dominant masses indicative of cystic changes on CT scans and recorded their Bosniak classification. In addition, two pathologists inspected the whole area of tumors macroscopically, labeled them as solid- or cystic change-dominant tumors, determined the pathogenesis of the cystic components (necrosis or hemorrhage), and recorded their inherent cystic characteristics (with/without TC-RCC components). We defined masses with cystic changes involving more than 50% of the entire tumor as cystic change-dominant tumors. RESULTS: Of the 26 tumors, 7 (27%) were diagnosed cystic change-dominant based on imaging and pathologic findings, of these, 2 were classified as Bosniak type III and 5 as Bosniak type IV. The pathologists confirmed that two type IV tumors demonstrated extensive necrosis and one type IV tumor revealed extensive hemorrhage. Four P-RCCs (type III and IV, 2 each) were of a mixed type harboring both solid and cystic components. Only one tumor exhibited a multilocular cystic appearance. All 7 cystic change-dominant P-RCCs were pathologically diagnosed as a pure P-RCC without TC-RCC components. CONCLUSION: While P-RCCs may contain cystic features, the multilocular type of cystic P-RCC is rare.

Utilization of (134)Cs/(137)Cs in the environment to identify the reactor units that caused atmospheric releases during the Fukushima Daiichi accident.

The Fukushima Daiichi nuclear power reactor units that generated large amounts of airborne discharges during the period of March 12-21, 2011 were identified individually by analyzing the combination of measured (134)Cs/(137)Cs depositions on ground surfaces and atmospheric transport and deposition simulations. Because the values of (134)Cs/(137)Cs are different in reactor units owing to fuel burnup differences, the (134)Cs/(137)Cs ratio measured in the environment was used to determine which reactor unit ultimately contaminated a specific area. Atmospheric dispersion model simulations were used for predicting specific areas contaminated by each dominant release. Finally, by comparing the results from both sources, the specific reactor units that yielded the most dominant atmospheric release quantities could be determined. The major source reactor units were Unit 1 in the afternoon of March 12, 2011, Unit 2 during the period from the late night of March 14 to the morning of March 15, 2011. These results corresponded to those assumed in our previous source term estimation studies. Furthermore, new findings suggested that the major source reactors from the evening of March 15, 2011 were Units 2 and 3 and that the dominant source reactor on March 20, 2011 temporally changed from Unit 3 to Unit 2.

Impacts of C-uptake by plants on the spatial distribution of 14C accumulated in vegetation around a nuclear facility-Application of a sophisticated land surface 14C model to the Rokkasho reprocessing plant, Japan.

The impacts of carbon uptake by plants on the spatial distribution of radiocarbon (14C) accumulated in vegetation around a nuclear facility were investigated by numerical simulations using a sophisticated land surface 14C model (SOLVEG-II). In the simulation, SOLVEG-II was combined with a mesoscale meteorological model and an atmospheric dispersion model. The model combination was applied to simulate the transfer of 14CO2 and to assess the radiological impact of 14C accumulation in rice grains during test operations of the Rokkasho reprocessing plant (RRP), Japan, in 2007. The calculated 14C-specific activities in rice grains agreed with the observed activities in paddy fields around the RRP within a factor of four. The annual effective dose delivered from 14C in the rice grain was estimated to be less than 0.7 µSv, only 0.07% of the annual effective dose limit of 1 mSv for the public. Numerical experiments of hypothetical continuous atmospheric 14CO2 release from the RRP showed that the 14C-specific activities of rice plants at harvest differed from the annual mean activities in the air. The difference was attributed to seasonal variations in the atmospheric 14CO2 concentration and the growth of the rice plant. Accumulation of 14C in the rice plant significantly increased when 14CO2 releases were limited during daytime hours, compared with the results observed during the nighttime. These results indicated that plant growth stages and diurnal photosynthesis should be considered in predictions of the ingestion dose of 14C for long-term chronic releases and short-term diurnal releases of 14CO2, respectively.

Diagnostic capability of gadoxetate disodium-enhanced liver MRI for diagnosis of hepatocellular carcinoma: comparison with multi-detector CT.

The purpose of this study was to evaluate the diagnostic capability of gadoxetate disodium (Gd-EOB)-MRI for the detection of hepatocellular carcinoma (HCC) compared with multidetector CT (MDCT). Fifty patients with 57 surgically proven HCCs who underwent Gd-EOB-MRI and MDCT from March 2008 to June 2011 were evaluated. Two observers evaluated MR and CT on a lesion-by-lesion basis. We analyzed sensitivity by grading on a 5-point scale, the degree of arterial enhancement and the differences in histological grades in the diffusion-weighted images (DWI). The results showed that the sensitivity of Gd-EOB-MRI was higher than that of MDCT especially for HCCs that were 1 cm in diameter or smaller. The hepatobiliary phase was useful for the detecting of small HCC. We had few cases in which it was difficult to judge HCC in the arterial enhancement between MRI and MDCT. In the diffusion-weighted image, well differentiated HCC tended to show a low signal intensity, and poorly differentiated HCC tended to show a high signal intensity. In moderately differentiated HCC's, the mean diameter of the high signal intensity group was larger than that of the low signal intensity group (24.5 mm vs. 15.8 mm). In conclusion, Gd-EOB-MRI tended to show higher sensitivity compared to MDCT in the detection of HCC.

[A case of liposarcoma of the abdominal wall complicated by thrombocytpenia as a paraneoplastic syndrome].

A 59-year-old woman was admitted to our hospital because of right chest pain. CT scan showed a mass on the right abdominal wall and bilateral pleural effusion. The histological diagnosis following core needle biopsy was undifferentiated sarcoma. The right pleural effusion gradually increased despite negative cytology. Although we planned chemotherapy for the clinically diagnosed pleural invasion, thrombocytopenia as a paraneoplastic syndrome appeared. The minimum thrombocyte count was 4,000/mm3. While transfusion was not effective, per os dexamethasone at 2.0 mg/day kept the thrombocyte count at around 6×10 4/mm3. Anti-thrombocyte antibody was negative. Tumor resection surgery with partial diaphragm resection and 11th and 12th rib resection, and abdominal wall plasty with mesh was performed. The final histological diagnosis was dedifferentiated liposarcoma. The thrombocyte count returned to the normal range just after the operation. However, she died of pleural dissemination, peritoneal dissemination, and local recurrence 69 days after the operation.

Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part II: verification of the source term and analysis of regional-scale atmospheric dispersion.

Regional-scale atmospheric dispersion simulations were carried out to verify the source term of (131)I and (137)Cs estimated in our previous studies, and to analyze the atmospheric dispersion and surface deposition during the Fukushima Dai-ichi Nuclear Power Plant accident. The accuracy of the source term was evaluated by comparing the simulation results with measurements of daily and monthly surface depositions (fallout) over land in eastern Japan from March 12 to April 30, 2011. The source term was refined using observed air concentrations of radionuclides for periods when there were significant discrepancies between the calculated and measured daily surface deposition, and when environmental monitoring data, which had not been used in our previous studies, were now available. The daily surface deposition using the refined source term was predicted mostly to within a factor of 10, and without any apparent bias. Considering the errors in the model prediction, the estimated source term is reasonably accurate during the period when the plume flowed over land in Japan. The analysis of regional-scale atmospheric dispersion and deposition suggests that the present distribution of a large amount of (137)Cs deposition in eastern Japan was produced primarily by four events that occurred on March 12, 15-16, 20, and 21-23. The ratio of wet deposition to the total varied widely depending on the influence by the particular event.