Effects of a lysophosphatidic acid receptor 1 antagonist on hypertensive renal injury in Dahl-Iwai salt-sensitive rats.

Lysophosphatidic acid (LPA) is a biologically active lysophospholipid, and acts on six types of LPA receptors (LPA1-LPA6). LPA-LPA1 signaling has been suggested as a therapeutic target for inflammatory and fibrotic disorders, including renal fibrosis. In this study, we investigated the effects of AM095, an LPA1 selective antagonist, on hypertensive renal injury in Dahl-Iwai salt-sensitive (DS) rats. We evaluated the preventive as well as therapeutic efficacy of AM095 in reducing proteinuria, and improving impaired renal function and renal fibrosis in the hypertensive DS rat. Preventive administration of AM095 suppressed proteinuria, renal function impairment and renal fibrosis in the hypertensive DS rats. In addition, therapeutic administration of AM095 reduced the levels of proximal tubular injury markers and suppressed renal fibrosis. Furthermore, combined administration of AM095 with an angiotensin-converting enzyme (ACE) inhibitor reduced the levels of proximal tubular injury markers and kidney weight increase, and suppressed renal fibrosis more effectively than administration of either agent alone, independent of the antihypertensive effect of the ACE inhibitor. These results provide the first evidence of the potential efficacy of LPA1 antagonist in suppressing renal injury in hypertensive DS rats, suggesting the promise of LPA1 antagonists as a novel therapeutic option for hypertensive renal injury.

Iodine concentration calculated by dual-energy computed tomography (DECT) as a functional parameter to evaluate thyroid metabolism in patients with hyperthyroidism.

BACKGROUND: Thyroid function in patients with Grave's disease is usually evaluated by thyroid scintigraphy with radioactive iodine. Recently, dual-energy computed tomography (DECT) with two different energy X-rays can calculate iodine concentrations and can be applied for iodine measurements in thyroid glands. This study aimed to assess the potential use of DECT for the functional assessment of the thyroid gland. METHODS: Thirteen patients with Grave's disease treated at our hospital from May to September 2015 were included in this retrospective study. Before treatments, all subjects had undergone both iodine scintigraphy [three and 24 h after oral administration of 123I (20 µCi)] and non-enhanced DECT. The region of interests (ROIs) were placed in both lobes of the thyroid glands, and CT values (HU: Hounsfield unit) and iodine concentrations (mg/mL) calculated from DECT images were measured. The correlation between CT values and iodine concentrations from DECT in the thyroid gland was evaluated and then the iodine concentrations were compared with radioactive iodine uptake ratios by thyroid scintigraphy. RESULTS: Mean (±SD) 123I uptake increased from 46.3 (±22.2) % (range, 11.1-80.1) at 3 h, to 66.5 (±15.2) % (range, 40.0-86.1) at 24 h (p < 0.01). CT values ranged from 34.5 to 98.7 HU [mean: 67.8 (±18.6)], while the iodine concentrations calculated with DECT ranged from 0.0 to 1.3 mg/mL [mean: 0.5 (±0.4)]. A moderate positive correlation between CT values and the calculated iodine concentrations in the thyroid gland was seen (R = 0.429, p < 0.05). A significant negative correlation between 123I uptake at 3 h and iodine concentration by DECT were seen (R = -0.680, p < 0.05), although no correlation was observed between 123I uptake at 3 h and CT values (p = 0.087). No correlation was observed between 123I uptake at 24 h and CT values (p = 0.153) or that between 123I uptake at 24 h and iodine concentration by DECT (p = 0.073). CONCLUSION: The negative correlation of 123I uptake at 3 h with iodine concentration evaluated by DECT was better than that observed with simple CT value. DECT may have a potential role in the evaluation of iodine turnover in hyperthyroid patients.

[Normal database (NDB) of 123I-IMP brain perfusion SPECT examination is affected by statistical image analysis in the presence or absence of scatter correction and attenuation correction].

PURPOSE: The purpose of our study is the establishment of normal database (NDB) from persons (aged 50-80 years) for 3D-SSP analysis of 123I-IMP brain perfusion SPECT image, and we analyzed whether the presence or absence of image correction methods, scatter correction (SC) and attenuation correction (AC), affects the created NDB and 3D-SSP analysis. MATERIALS AND METHODS: We created NDB from 63 healthy volunteers (32 males and 31 females, aged 50-80 years), and calculated the coefficient of variation for each pixel from the mean value and standard deviation. Next, we compared the visual assessments of the standard deviation images by each image correction method, and the coefficient of variation of SEE analysis in each part of the brain. Furthermore, we examined frontotemporal dementia and healthy volunteers by 3D-SSP analysis, and evaluated the differences of Z-score in the presence or absence of image correction methods. RESULTS: In NDB, the coefficient of variation was the minimum when SC and AC were not applied and the maximum in periventricular and cerebellum when SC and AC were applied. In Z-score image of 3D-SSP analysis, Z-score of the low value was the maximum when SC and AC were not applied. CONCLUSION: It was shown that the results from NDB coefficient of variation and 3D-SSP analysis were affected by the differences of image correction methods. It is important to understand the feature of imaging reconstruction conditions in your own facilities, and evaluate 3D-SSP analysis.

Radiation exposure from CT examinations in Japan.

BACKGROUND: Computed tomography (CT) is the largest source of medical radiation exposure to the general population, and is considered a potential source of increased cancer risk. The aim of this study was to assess the current situation of CT use in Japan, and to investigate variations in radiation exposure in CT studies among institutions and scanners. METHODS: Data-sheets were sent to all 126 hospitals and randomly selected 14 (15%) of 94 clinics in Gunma prefecture which had CT scanner(s). Data for patients undergoing CT during a single month (June 2008) were obtained, along with CT scan protocols for each institution surveyed. Age and sex specific patterns of CT examination, the variation in radiation exposure from CT examinations, and factors which were responsible for the variation in radiation exposure were determined. RESULTS: An estimated 235.4 patients per 1,000 population undergo CT examinations each year, and 50% of the patients were scanned in two or more anatomical locations in one CT session. There was a large variation in effective dose among hospitals surveyed, particularly in lower abdominal CT (range, 2.6-19.0 mSv). CT examinations of the chest and upper abdomen contributed to approximately 73.2% of the collective dose from all CT examinations. It was estimated that in Japan, approximately 29.9 million patients undergo CT annually, and the estimated annual collective effective dose in Japan was 277.4 *103 Sv person. The annual effective dose per capita for Japan was estimated to be 2.20 mSv. CONCLUSIONS: There was a very large variation in radiation exposure from CT among institutions surveyed. CT examinations of the chest and upper abdomen were the predominant contributors to the collective dose.

[Evaluation of exposure dose for panoramic radiography].

PURPOSE: There is no established method to determine a diagnostic reference level of panoramic radiology. As the basic principle of the panoramic radiology dose index (PRDI) and CT dose index (CTDI) is almost identical, we evaluated the usefulness of PRDI for this purpose. METHODS: Using the imaging plate (IP) sandwiched between the 160-mm thick acrylic disks, horizontal radiation dose distribution was analyzed by the conventional radiographic technique. Panoramic exposure dose was measured using the CT ionizing chamber that was placed at the tracking focus. Beam height was used as measurement unit, and PRDI was normalized and calculated. RESULTS: There were two foci showing the maximum exposure dose for this panoramic equipment, located symmetrically 45 mm away from the center of the object. The PRDI of medium-sized individuals measured by this method was 0.74 mGy. CONCLUSION: We suggested a method to evaluate a diagnostic reference level, measuring the dose of exposure focus, i.e., maximum dose on panoramic radiology.

Variability of lesion detectability and standardized uptake value according to the acquisition procedure and reconstruction among five PET scanners.

OBJECTIVE: The objective of this study was to assess differences in the semiquantitative values of 18F-fluorodeoxyglucose (18F-FDG) uptake among different positron emission tomographic (PET) systems. METHODS: A phantom study was performed to compare standardized uptake value (SUV) in five PET scanners including a dedicated PET scanner and four PET/computed tomography (CT) scanners. Radioactivity simulating the SUV of 2.5 was filled in the hot spheres (8 mm, 11 mm, 14 mm, 18 mm, 22 mm, and 27 mm) that were set in the cylindrical phantom with the background SUV of 1.0. Data acquisition and reconstruction were performed according to routine and standardized conditions. The standardized condition was as follows: CT acquisition (120 kVp, 50 mA) and PET acquisition (2-min acquisition with a slice thickness of 2 mm); reconstruction was performed by ordered subsets expectation maximization + Fourier rebinning. Detectability of hot spheres and SUV was compared between routine condition and standardized condition with five PET scanners. RESULTS: On routine condition, two cameras could detect a 14-mm sphere clearly. On the other hand, the visualization of hot spheres by the standardized condition was remarkably variable. Semiquantitative evaluation revealed that a maximum of 45.7% error was recognized with the 27-mm sphere by the routine condition, although the standardized condition could reduce the error to 22.6%. CONCLUSIONS: Detectability depends not only on the PET machine but also on the imaging protocol. The results indicate that SUV is variable with PET machines under routine conditions of data acquisition and reconstruction. Standardization of the reconditions can reduce variability and maximum difference in the SUV by half.

[Evaluation of efficiency of a semiconductor gamma camera].

We evaluation basic characteristics of a compact type semiconductor gamma camera (eZ-SCOPE AN) of Cadmium Zinc Telluride (CdZnTe). This new compact gamma camera has 256 semiconductors representing the same number of pixels. Each semiconductor is 2 mm square and is located in 16 lines and rows on the surface of the detector. The specific performance characteristics were evaluated in the study referring to NEMA standards; intrinsic energy resolution, intrinsic count rate performance, integral uniformity, system planar sensitivity, system spatial resolusion, and noise to the neighboring pixels. The intrinsic energy resolution measured 5.7% as FWHM. The intrinsic count rete performance ranging from 17 kcps to 1,285 kcps was evaluated, but the highest intrinsic count rate was not observed. Twenty percents count loss was recognized at 1,021 kcps. The integral uniformity was 1.3% with high sensitivity collimator. The system planar sensitivity was 33,330 cpm/MBq with high resolution collimator and 766,767 cpm/MBq with high sensitivity collimator. The system spatial resolution (FWHM) was 2.0 mm and 2.2 mm when the distance between source and collimator was 0 cm and 3 cm respectively.

Diagnostic reference level of computed tomography (CT) in Japan.

Optimisation of computed tomography (CT) parameters is important in avoiding excess radiation exposure. The aim of this study is to establish the diagnostic reference levels (DRL) of CT in Japan by using dose-length product (DLP). Datasheets were sent to all hospitals/clinics which had CT scanner(s) in Gunma prefecture. Data were obtained for all patients who underwent CT during a single month (June 2010), and the distributions of DLP were evaluated for eight anatomical regions and five patient age groups. The DRL was defined as the 25th and 75th percentiles of DLP. Datasheets were collected from 80 of 192 hospitals/clinics (26 090 patients). DLP for head CT of paediatric patients tended to be higher in Japan compared with DRLs of paediatric head CTs reported from the EU or Syria. Although this study was performed with limited samples, DLP for adult patients were at comparable levels for all anatomical regions.

[Intra-fractional set-up and organ motion errors in intensity-modulated radiation therapy for prostate cancer].

PURPOSE: The aim of this study is to investigate various intra-fractional errors and to determine the appropriate planning target volume (PTV) margins in intensity modulated radiation therapy (IMRT) for prostate cancer. METHODS: Ten patients with prostate cancer treated with IMRT between July 2009 and March 2010 were analyzed. PTV was created by adding 4 mm posterior and 7 mm anterior and lateral margins to the clinical target volume (CTV) including prostate and proximal seminal vesicles. Intra-fractional set-up and organ motion errors were measured using cone beam computed tomography (CBCT) images before and after each irradiation. Systematic and random errors were calculated by van Herk and Stroom's models. RESULTS: Intra-fractional errors of set-up and organ motion were 0.70 ± 0.84 mm and 0.88 ± 0.95 mm in the left-right (L-R), 1.04 ± 0.98 mm and 1.69 ± 1.58 mm in the cranial-coudal (C-C), and 1.08 ± 1.01 mm and 1.91 ± 1.58 mm in the anterior-posterior (A-P) directions, respectively. The errors in the C-C and A-P were significantly larger than those in the L-R (p<0.01). The organ motion errors in the C-C and A-P were significantly larger than the set-up errors (p<0.01). The appropriate PTV margin estimated in this study was 4.73 mm. CONCLUSIONS: Intra-fractional errors in all directions were less than 2 mm and required PTV margin in the study was similar to actual posterior margin in our routine practice. It is important to determine intra-fractional errors as well as inter-fractional errors to deliver successful IMRT for prostate cancers.

Radiation safety management of residual long-lived radioactivity distributed in an inner concrete wall of a medical cyclotron room.

The depth distribution of residual long-lived radioactivity in the inner concrete wall of a medical cyclotron room was measured by assaying concrete cores. Seven long-lived radioactive nuclides ((46)Sc, (60)Co, (65)Zn, (134)Cs, (152)Eu, (22)Na and (54)Mn) were identified by gamma-ray spectrometry of the concrete samples. It was confirmed that the gamma-ray-emitting radionuclides induced by thermal neutrons through the (n, γ) reaction are dominant, and that the activity induced by thermal neutrons is greater at a depth of 10-30 cm, rather than at the surface of the concrete, and decreased exponentially beyond a depth of ~40 cm. Although the specific activity at the surface was greater than the clearance level for radioactive waste indicated in IAEA RS-G-1.7, the mean specific activities in the walls and floor were less than the clearance level.

Use of postmortem computed tomography to reveal an intraoral gunshot injuries in a charred body.

A 53-year-old man was found dead after a fire at his residence had been extinguished. Although a pistol was recovered beside the body, external examination was unable to indicate any gunshot wound because of severe charring of the body. Postmortem computed tomography (CT) scan performed prior to autopsy suggested an entrance gunshot wound in the posterior pharynx with loss of soft tissue and an internal bullet path through the right anterior and posterior parts of the occipital bone. Autopsy revealed an entrance gunshot wound with hemorrhage in the soft tissue of the posterior pharynx, massive contusion of the right occipital lobe, and subarachnoid hemorrhage in the right temporal lobe, both occipital lobes and the superior surface of the left cerebellar hemisphere, thus being consistent with the findings of postmortem CT. A carboxyhemoglobin concentration of 5% in blood from the cadaver was consistent with the lack of soot deposition from the larynx to the bronchus. These observations confirmed that death had been caused by an intraoral gunshot resulting in severe brain damage, before the body had been burned.

A case of fatal drug intoxication showing a high-density duodenal content by postmortem computed tomography.

A 22-year-old woman was found dead in her bed, and subsequent postmortem examination was performed using ordinary methods such as external examination, Triage®, and computed tomography (CT) scan which demonstrated a high-density content of the duodenum. Autopsy and quantitative analysis of drugs present in the GI tract showed that high amounts of radiopaque psychotic agents such as fluvoxamine maleate, carbamazepine, and zolpidem tartrate had been responsible for the high-density profile of the duodenum. Postmortem quantitative analysis of drugs in the blood suggested that death had been caused by fatal intoxication with fluvoxamine maleate. Thus, postmortem CT could offer an opportunity to suspect drug intoxication due to radiopaque psychotic agents such as chloral hydrate, phenothiazine, bromovaleryl urea, fluvoxamine maleate, and probably zolpidem tartrate, although it is neither a specific nor a quantitative test for drugs. Therefore, postmortem CT happened to provide clues to investigation of drug intoxication in the present case.

[Evaluation of Radio-activated Compounds Produced in the Walls and Adjacent Areas of a Small Medical Cyclotron].

According to the (18)O(p, n) (18)F reaction, fast neutrons produced in the target will cause residual radioactivity in a cyclotron itself and in the concrete walls mainly after thermalization of neutrons.As exploratory work prior to decommissioning of a medical cyclotron facility, surface and core samples of the facility's concrete walls were collected after confirming the external radiation was at a low level based on hollow ionization chamber-type survey meter and glass dosimeter measurements. The residual radioactivity in these samples was measured by gamma-spectrometry. Residual radioactivity was detected in all of the components of the cyclotron. In the concrete, eight residual radioactive nuclides were identified. However, radioactivity concentrations of these radionuclides were less than that of (40)K which may exist generally in a natural environment. A clearance level for radioactive solid waste has not been defined nor implemented at present in Japan, and reliable evaluation will be required to minimize radioactive waste at the time of decommissioning. The present results provide basic data for establishment of regulatory guidelines for decommissioning of medical cyclotrons.