Exploring a chemical scaffold for rapid and selective photoaffinity labelling of non-ribosomal peptide synthetases in living bacterial cells

Non-ribosomal peptide synthetases (NRPSs) biosynthesize many pharmaceuticals and virulence factors. The biosynthesis of these natural peptide products from biosynthetic gene clusters depends on complex regulations in bacteria. However, our current knowledge of NRPSs is based on enzymological studies using full NRPS systems and/or a single NRPS domain in heterologous hosts. Chemical and/or biochemical strategies to capture the endogenous activities of NRPSs facilitate studies on NRPS cell biology in bacterial cells. Here, we describe a chemical scaffold for the rapid and selective photoaffinity labelling of NRPSs in purified systems, crude biological samples and living bacterial cells. We synthesized photoaffinity labelling probes coupled with 5'-O-N-(phenylalanyl)sulfamoyladenosine with clickable alkyl diazirine or trifluoromethyl phenyl diazirine. We found that a trifluoromethyl phenyl diazirine-based probe cross-linked the Phe-activating domain of a GrsA-NRPS with high selectivity and sensitivity at shorter ultraviolet (UV) irradiation times (less than 5 min) relative to a prototypical benzophenone-based probe. Our results demonstrated that this quick labelling protocol can prevent damage to proteins and cells caused by long UV irradiation times, providing a mild photoaffinity labelling method for biological samples. This article is part of the theme issue 'Reactivity and mechanism in chemical and synthetic biology'.

Prognostic value of [18F]FDG-PET prior to [131I]MIBG treatment for pheochromocytoma and paraganglioma (PPGL)

OBJECTIVE

Pheochromocytomas and paragangliomas (PPGLs) are rare tumors arising from the neural crest cells that form the sympathetic and parasympathetic nervous systems. Radiotherapy with [¹³¹I]metaiodobenzylguanidine (MIBG) is recommended for unresectable PPGLs. We investigated the usefulness of the metabolic tumor volume (MTV) and total lesion glycolysis (TLG) derived from [¹⁸F]fluorodeoxyglucose-positron emission tomography (FDG-PET) for predicting the prognosis of patients with unresectable PPGL(s) before receiving [¹³¹I]MIBG therapy.

PATIENTS AND METHODS

We retrospectively analyzed the cases of 25 patients with unresectable PPGLs treated with [¹³¹I]MIBG at our hospital between 2001 and 2020. The MTV and TLG were measured in reference to liver accumulation. We divided the patients into two groups based on median values for the maximum standardized uptake value (SUVmax), MTV, and TLG, and evaluated between-group differences using log-rank tests. Cox proportional hazards models were used to determine whether there were significant differences in prognosis with respect to tumor type (pheochromocytoma vs. paraganglioma), site of metastasis, age, past treatment (chemotherapy, external radiation or [¹³¹I]MIBG treatment before the current [¹³¹I]MIBG treatment), urinary catecholamine, SUVmax, MTV, and TLG.

RESULTS

The median follow-up time was 42 months (range 2-136 months). The median overall survival was 63 months. The overall survival (OS) was significantly shorter in the high-MTV group (log-rank test, p = 0.049) and the high-TLG group (p = 0.049), with no significant difference between the high- and low-SUVmax groups (p = 0.19). Likewise, there was no significant difference in prognosis according to pheochromocytoma or paraganglioma, metastasis location, age, or prior chemotherapy. A history of external radiation before [¹³¹I]MIBG treatment was associated with a significantly worse prognosis (hazard ration [HR] = 7.95, p = 0.0018). Urinary adrenaline and noradrenaline were not significant prognostic factors (p = 0.70, p = 0.25, respectively), but urinary dopamine did predict a worse outcome (p = 0.022). There was no increased risk of death for higher SUVmax or TLG (p = 0.63 and 0.057, respectively), but higher MTV did predict a worse outcome (HR = 7.27, p = 0.029).

CONCLUSION

High MTV and high TLG were significantly associated with a poor prognosis after [¹³¹I]MIBG therapy for PPGLs. Other treatment strategies for such patients may need to be explored.

Search for Dark Matter Annihilation Signals in the H.E.S.S. Inner Galaxy Survey

The central region of the Milky Way is one of the foremost locations to look for dark matter (DM) signatures. We report the first results on a search for DM particle annihilation signals using new observations from an unprecedented γ-ray survey of the Galactic Center (GC) region, i.e., the Inner Galaxy Survey, at very high energies (≳100  GeV) performed with the H.E.S.S. array of five ground-based Cherenkov telescopes. No significant γ-ray excess is found in the search region of the 2014-2020 dataset and a profile likelihood ratio analysis is carried out to set exclusion limits on the annihilation cross section ⟨σv⟩. Assuming Einasto and Navarro-Frenk-White (NFW) DM density profiles at the GC, these constraints are the strongest obtained so far in the TeV DM mass range. For the Einasto profile, the constraints reach ⟨σv⟩ values of 3.7×10^{-26}  cm^{3} s^{-1} for 1.5 TeV DM mass in the W^{+}W^{-} annihilation channel, and 1.2×10^{-26}  cm^{3} s^{-1} for 0.7 TeV DM mass in the τ^{+}τ^{-} annihilation channel. With the H.E.S.S. Inner Galaxy Survey, ground-based γ-ray observations thus probe ⟨σv⟩ values expected from thermal-relic annihilating TeV DM particles.

Identification of patients with Graves' disease who benefit from high-dose radioactive iodine therapy

OBJECTIVE

Radioactive iodine (RAI) therapy is a useful treatment for Graves' disease (GD). Most RAI sessions administer ≤ 500 MBq of iodine (I)-131. Sometimes patients require repeated RAI, often for longer periods of remission. We investigated the characteristics of patients for whom high dose (mostly 1110 MBq of I-131) RAI was effective as RAI therapy for GD.

METHODS

We retrospectively analyzed the cases of 79 patients who underwent RAI for GD in a multicenter setting. We divided the patients into two groups based on the I-131 dose administered: the low dose (LD) group who received ≤ 500 MBq (n = 44) and the high dose (HD) group who received > 500 MBq (n = 35). The therapeutic effect was defined as achieving remission and reaching the point of participating in thyroid hormone replacement therapy within 1 year after RAI. We compared the LD and HD groups' remission rates and conducted a multivariate logistic regression analysis of predictive factors for remission. In a simulation, using the formula for predicting the probability of remission obtained from the analysis results, we estimated how much the remission rate would change if the I-131 dose is increased from 500 to 1110 MBq.

RESULTS

The mean ± standard deviation I-131 dose administered in the LD group was 480 ± 6 MBq, and that of the HD group was 1054 ± 265 MBq. Thirty-five patients (80%) in the LD group and 26 patients (74%) in the HD group achieved remission; this difference in the remission rate was not significant. The multivariate analysis results demonstrated that the absorbed dose and thyroid-stimulating antibody (TSAb) were independent predictors of remission. Seven patients (8.9%) showed an increased probability of remission from < 50% to > 50% when the higher RAI dose was applied (1110 MBq instead of 500 MBq). The thyroid volume and TSAb values in these patients were relatively large at 54.7 ± 34.2 mL and 1378.4 ± 586.3%, respectively.

CONCLUSION

Although the overall remission rate was not significantly different between the patients who received high- or low-dose I-131, treatment with high-dose RAI may improve the probability of remission in patients with a massive thyroid volume and/or high-TSAb Graves' disease.

Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi

Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE, [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to a month after its 2021 outburst, observed using the High Energy Stereoscopic System. The VHE emission has a similar temporal profile to lower-energy GeV emission, indicating a common origin, with a two-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic-rays to very high energies.

Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera-electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

Effects of Repeated 131I-Meta-Iodobenzylguanidine Radiotherapy on Tumor Size and Tumor Metabolic Activity in Patients with Metastatic Neuroendocrine Tumors

¹³¹I-meta-iodobenzylguanidine (¹³¹I-MIBG) radiotherapy has shown some survival benefits in metastatic neuroendocrine tumors (NETs). European Association of Nuclear Medicine clinical guidelines for ¹³¹I-MIBG radiotherapy suggest a repeated treatment protocol, although none currently exists. The existing single-high-dose ¹³¹I-MIBG radiotherapy (444 MBq/kg) has been shown to have some benefits for patients with metastatic NETs. However, this protocol increases adverse effects and requires alternative therapeutic approaches. Therefore, the aim of this study was to evaluate the effects of repeated ¹³¹I-MIBG therapy on tumor size and tumor metabolic response in patients with metastatic NETs. Methods: Eleven patients with metastatic NETs (aged 49.2 ± 16.3 y) prospectively received repeated 5,550-MBq doses of ¹³¹I-MIBG therapy at 6-mo intervals. In total, 31 treatments were performed. The mean number of treatments was 2.8 ± 0.4, and the cumulative ¹³¹I-MIBG dose was 15,640.9 ± 2,245.1 MBq (286.01 MBq/kg). Tumor response was observed by CT and ¹⁸F-FDG PET or by ¹⁸F-FDG PET/CT before and 3-6 mo after the final ¹³¹I-MIBG treatment. Results: On the basis of the CT findings with RECIST, 3 patients showed a partial response and 6 patients showed stable disease. The remaining 2 patients showed progressive disease. Although there were 2 progressive-disease patients, analysis of all patients showed no increase in summed length diameter (median, 228.7 mm [interquartile range (IQR), 37.0-336.0 mm] to 171.0 mm [IQR, 38.0-270.0 mm]; P = 0.563). In tumor region-based analysis with partial-response and stable-disease patients (n = 9), ¹³¹I-MIBG therapy significantly reduced tumor diameter (79 lesions; median, 16 mm [IQR, 12-22 mm] to 11 mm [IQR, 6-16 mm]; P < 0.001). Among 5 patients with hypertension, there was a strong trend toward systolic blood pressure reduction (P = 0.058), and diastolic blood pressure was significantly reduced (P = 0.006). Conclusion: Eighty-two percent of metastatic NET patients effectively achieved inhibition of disease progression, with reduced tumor size and reduced metabolic activity, through repeated ¹³¹I-MIBG therapy. Therefore, this relatively short-term repeated ¹³¹I-MIBG treatment may have potential as one option in the therapeutic protocol for metastatic NETs. Larger prospective studies with control groups are warranted.

Search for γ-Ray Line Signals from Dark Matter Annihilations in the Inner Galactic Halo from 10 Years of Observations with H.E.S.S

Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant γ-ray excess above the background is found. We derive upper limits on the annihilation cross section ⟨σv⟩ for monoenergetic DM lines at the level of 4×10^{-28}  cm^{3} s^{-1} at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based γ-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two γ-ray photons at the level expected from the thermal relic density for TeV DM particles.

Detection of copy number variations in epilepsy using exome data

Epilepsies are common neurological disorders and genetic factors contribute to their pathogenesis. Copy number variations (CNVs) are increasingly recognized as an important etiology of many human diseases including epilepsy. Whole-exome sequencing (WES) is becoming a standard tool for detecting pathogenic mutations and has recently been applied to detecting CNVs. Here, we analyzed 294 families with epilepsy using WES, and focused on 168 families with no causative single nucleotide variants in known epilepsy-associated genes to further validate CNVs using 2 different CNV detection tools using WES data. We confirmed 18 pathogenic CNVs, and 2 deletions and 2 duplications at chr15q11.2 of clinically unknown significance. Of note, we were able to identify small CNVs less than 10 kb in size, which might be difficult to detect by conventional microarray. We revealed 2 cases with pathogenic CNVs that one of the 2 CNV detection tools failed to find, suggesting that using different CNV tools is recommended to increase diagnostic yield. Considering a relatively high discovery rate of CNVs (18 out of 168 families, 10.7%) and successful detection of CNV with <10 kb in size, CNV detection by WES may be able to surrogate, or at least complement, conventional microarray analysis.

The utility of FDG-PET for detecting multiple primary cancers in hypopharyngeal cancer patients

Aim: To examine the utility of 2'-[18F]-fluoro-2'-deoxy-D-glucose positron emission tomography (FDG-PET) for detecting multiple primary cancers (MPC) in patients with hypopharyngeal cancer (HPC). Patients, methods: Seventy patients with HPC underwent FDGPET to determine the staging. Routine clinical examinations were carried out, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), and oesophagealgastroduodenoscopy (EGDS). The detection rate of synchronous and metachronous cancer was calculated based on FDG-PET alone or FDG-PET combined with clinical routine examination. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy were used to diagnose oesophageal cancer using FDG-PET. Results: Of the 70 patients, 12 (17.1%) had 15 synchronous tumours, and 2 of the 58 remaining patients (3.4%) had metachronous tumours. Oesophageal cancer was discovered most frequently: superficial type (n = 6), advanced type (n = 4). On a per-patient basis, 11 of 12 patients (91.6%) were diagnosed with synchronous tumours, and on a per-lesion basis, 12 of 15 lesions (80.0%) were detected by FDG-PET. The sensitivity, specificity, accuracy, PPV, and NPV of FDG-PET regarding oesophageal cancer were 70%, 100%, 95.7%, 100%, and 95.2% respectively. Three of the six superficial types were positive on FDG-PET. Both of the metachronous tumour lesions were detected by FDG-PET. Conclusion: FDG-PET is useful for estimating the MPC in HPC patients. Since 3 of 10 synchronous oesophageal cancer were missed with PET alone, a combination with EGDS should be considered to exclude synchronous oesophageal cancer.

18F-fluoromisonidazole (FMISO) PET may have the potential to detect cardiac sarcoidosis

18F-fluoromisonidazole (FMISO) is a positron emission tomography (PET) tracer that accumulates in hypoxic tissues. We here present a case of suspected cardiac sarcoidosis which was detected with increased FMISO uptake.

Search for Spectral Irregularities due to Photon-Axionlike-Particle Oscillations with the Fermi Large Area Telescope

We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the γ-ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above 5×10^{-12}  GeV^{-1} for ALP masses 0.5≲m_{a}≲5  neV at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the γ-ray opacity of the Universe.

Temporomandibular joint articulations on working side during chewing in adult females with cross-bite and mandibular asymmetry

Influence of mandibular asymmetry and cross-bite on temporomandibular joint (TMJ) articulation remained unknown. This study aimed to investigate whether/how the working-side condylar movement irregularity and articular spaces during chewing differ between patients with mandibular asymmetry/cross-bite and control subjects. The cross-bite group and the control group consisted of 10 adult female patients and 10 adult female subjects, respectively. They performed unilateral gum-chewing. The mandibular movements were recorded using a video-based opto-electronic system. The 3D articular surface of the TMJ for each individual was reconstructed using CT/MRI data. For local condylar points, the normalised jerk cost (NJC) towards normal direction to the condylar surface, the angle between tangential velocity vector and condylar long axis and intra-articular space were measured. Three rotatory angles at centre of the condyle were also measured. During closing and intercuspation, (i) movements of posterior portion of the deviated side condyle showed significantly less smoothness as compared with those for the non-deviated side and control subjects, (ii) the rotations of the condyle on the deviated side induced greater intra-articular space at posterior and lateral portions. These findings suggest that chewing on the side of mandibular deviation/cross-bite may cause irregular movement and enlarged intra-articular space at posterior portion of the deviated side condyle.

Using breast radiographers' reports as a second opinion for radiologists' readings of microcalcifications in digital mammography

OBJECTIVE

The aim of this study was to investigate a practical method for incorporating radiographers' reports with radiologists' readings of digital mammograms.

METHODS

This simulation study was conducted using data from a free-response receiver operating characteristic observer study obtained with 75 cases (25 malignant, 25 benign and 25 normal cases) of digital mammograms. Each of the rating scores obtained by six breast radiographers was utilized as a second opinion for four radiologists' readings with the radiographers' reports. A logical "OR" operation with various criteria settings was simulated for deciding an appropriate method to select a radiographer's report in all combinations of radiologists and radiographers. The average figure of merit (FOM) of the radiologists' performances was statistically analysed using a jackknife procedure (JAFROC) to verify the clinical utility of using radiographers' reports.

RESULTS

Potential improvement of the average FOM of the radiologists' performances for identifying malignant microcalcifications could be expected when using radiographers' reports as a second opinion. When the threshold value of 2.6 in Breast Imaging-Reporting and Data System (BI-RADS®) assessment was applied to adopt/reject a radiographer's report, FOMs of radiologists' performances were further improved.

CONCLUSION

When using breast radiographers' reports as a second opinion, radiologists' performances potentially improved when reading digital mammograms. It could be anticipated that radiologists' performances were improved further by setting a threshold value on the BI-RADS assessment provided by the radiographers.

ADVANCES IN KNOWLEDGE

For the effective use of a radiographer's report as a second opinion, radiographers' rating scores and its criteria setting for adoption/rejection would be necessary.

Influence of balancing-side occlusal interference on smoothness of working-side condylar movement and intra-articular space in chewing efforts

Response of temporomandibular joint (TMJ) articulation adapting to occlusal alteration has been sparsely known. For 10 healthy adults with acceptably good occlusion, an artificial occlusal interference (OI) was introduced to the lower molar on the balancing side of unilateral chewing. Subjects were asked to chew a gum on their preferred side. The chewing jaw movements with/without the OI were recorded using a video-based optoelectronic system. The mandibular movements were generated in each individual's TMJ model reconstructed by magnetic resonance images. The smoothness of local condylar point movements towards the normal direction of the condylar surface and interarticular space on the working side was measured. Overall, the smoothness of condylar point movements in the closing phase was impaired immediately after introduction of the OI. In the intercuspal phase, the OI increased the joint space. After about 60 chewing cycles, the movement smoothness and joint space began to recover. These findings suggest that OI on the balancing side induced irregular stress field translation on the working-side condylar surface followed by acute recovery process.

MRI in a case of osteosarcoma in the temporomandibular joint

Osteosarcoma of the temporomandibular joint (TMJ) is rare. We report a case of osteosarcoma in the TMJ of a 62-year-old female, pre-operatively diagnosed to have a benign tumour, and discuss the usefulness and limits of MRI using a TMJ coil as a diagnosis.

New constraint on the existence of the μ+ → e+ γ decay

The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay μ(+) → e(+)γ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of 5.7 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

Computer-Aided Diagnosis Scheme for Detection of Unruptured Intracranial Aneurysms in MR Angiography

The detection of unruptured intracranial aneurysms is a major subject in magnetic resonance angiography (MRA) images. However,it is difficult for radiologists to detect small aneurysms on the maximum intensity projection (MIP) images, because adjacent vessels overlap with the aneurysm. The purpose of this study was to develop an automated computerized detection of aneurysms in order to assist radiologists' interpretation as a "second opinion." The vessels were first segmented from background by use of gray-level thresholding and region growing technique. The gradient concentrate (GC) filter was then applied to the segmented vessels for enhancement of aneurysm. The initial aneurysm candidate was identified in the GC image with a gray level threthold. For removal of false positives (FPs), we determined three features, i.e.,size,sphericity, and mean value of GC image in each of the candidate regions. Finally, the rule-based schemes with these features and quadratic discriminant analysis were applied for distinction between aneurysms and FPs. The sensitivity of our method for detection of aneurysms was 100% (7/7) with 1.85 FPs per patient. With our computerized scheme, all aneurysms were detected correctly with low FP rates, and would be useful in assisting radiologists for identifying correct aneurysms and for reducing the interpretation time.

Measurement of separate cosmic-ray electron and positron spectra with the fermi large area telescope

We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting Earth's shadow, which is offset in opposite directions for opposite charges due to Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 and 200 GeV. We confirm that the fraction rises with energy in the 20-100 GeV range. The three new spectral points between 100 and 200 GeV are consistent with a fraction that is continuing to rise with energy.

Constraining dark matter models from a combined analysis of Milky Way satellites with the Fermi Large Area Telescope

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10(-26)  cm3  s(-1) at 5 GeV to about 5×10(-23)   cm3  s(-1) at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10(-26)  cm3  s(-1) for a purely s-wave cross section), without assuming additional boost factors.

New limit on the lepton-flavor-violating decay μ+→e+γ

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay μ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the μ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.

Radiation Dose Measurement with Newly Developed Head Phantom for Interventional Neuroradiology

Although it is important to measure and record radiation dose to a patient's skin, no standardized measuring method is available to compare the performance of digital subtraction angiography (DSA) systems with those of other institutions. We developed a new bidirectional information exchange system using a web page and, E-mail. Measurements are obtained using an original head phantom with skin dose monitors. This system was sent to institutions ordering it from the web page. The data obtained with this system by each institution were evaluated and displayed anonymously on a graph on the web page for comparison. This method for measuring radiation dose allows the comparison of DSA systems under identical conditions. This system can alert the user that the radiation dose delivered using ordinary parameters differs from that of other institutions or DSA systems. To promote the use of this system, we developed a web page with information about radiation dose measuring and initiated an online lending operation. This head phantom and standardized measuring method allows the accurate comparison of skin radiation dose and DSA performance under the same conditions.

Calcifying cystic odontogenic tumour: CT imaging

OBJECTIVES

Calcifying cystic odontogenic tumour (CCOT) is a rare disorder of the jaw. A comparison between conventional radiographs and CT images in CCOTs has not been reported. The purposes of this study were to analyse conventional radiographs and CT images of CCOTs, establish CT images of CCOTs and assess the utility of CT in the diagnosis of CCOTs.

METHODS

Nine patients with a histopathologically confirmed CCOT who had both conventional radiographs and CT images were enrolled.

RESULTS

CT was superior to conventional radiographs in detecting buccolingual expansion, odontomas and radio-opaque bodies.

CONCLUSION

The characteristic CT appearances of CCOT were that radio-opaque bodies were typically located in the periphery of the lesion and the shape of radio-opaque bodies was linear and/or spotted. CT was useful in diagnosing a CCOT.