Carcinogenicity of radon/radon decay product inhalation in rats – effect of dose,dose rate and unattached fraction

Purpose: The effects of inhalation of radon/radon decay products at different total doses, dose rates and ‘unattached’ fractions were investigated in a life span study in rats.

Materials and methods: 1574 rats inhaled radon/radon decay products in a purpose-built recirculating exposure system that provided stable/reproducible exposure conditions. 501 were maintained as controls.

Results: Lung tumour incidences were significantly elevated in most exposed groups. The study power was insufficient to resolve the shape of the dose and dose rate response curves, but combination of this data with that from other studies demonstrated that for high cumulative exposures, the lifetime excess absolute risk increases with increasing exposure durations and for low cumulative exposures the opposite trend occurs. Exposure did not increase leukaemia incidences. A small number of non-lung tumour types including mammary fibroadenoma showed elevated incidences in some exposed groups, however not consistently across all exposure groups and showed no dose or dose rate relationship.

Conclusions: Radon/radon decay product exposure caused excess lung tumours in rats along with limited non-lung effects. The results are consistent with the findings that at low cumulative exposures decreasing exposure concentrations or protracting the time over which the dose is delivered, reduces lung tumour risk. At higher levels, decreasing exposure concentrations or protracting exposure time increases lung tumour risk.     

Mortality from cancers of the extra-thoracic airways in relation to radon progeny in the Wismut cohort, 1946–2008

Abstract

Purpose: Inhalation of radon progeny can cause high lung and respiratory tract radiation doses. The aim of this paper was to examine the relationship between radon progeny and cancers of the extra-thoracic airways in the German uranium miner cohort for an extended follow-up through 2008.

Methods: The cohort included 58,690 workers employed between 1946 and 1989 at the Wismut company. Exposure to radon progeny in Working Level Months (WLM) was determined from a comprehensive job-exposure matrix. The mean (max) cumulative exposure to radon among exposed cohort members (86%) was 280 WLM (3,224 WLM). Internal Poisson regression models were applied to estimate the linear Excess Relative Risk (ERR) per unit of cumulative exposure to radon.

Results: A small increase in the mortality from all cancers of the extra-thoracic airways combined with increasing cumulative exposure to radon was found (ERR/100 WLM = 0.036, p = 0.12), based on 234 deaths. The estimated ERR per 100 WLM for relevant cancer sub-groups were: 0.017 (p > 0.5) larynx (n = 94); 0.077 (p = 0.20) pharynx (n = 74); and 0.030 (p > 0.5) tongue and mouth (n = 55).

Conclusion: Results indicated a small but not statistically significant increase in mortality from cancers of the extra-thoracic airways in relation to radon. Low statistical power and uncontrolled confounding were limitations of this study.     

Two year evolution of radon emission and tectonic movements in Tuzla Fault,Seferihisar-İzmir

Previous studies showed that tectonic movement and meteorological events are accompanied with radon release. In this study soil gas radon and tectonic movements were investigated with meteorological factors taking into account. Soil gas radon measurements were collected over a-two year period (2008–2010) at the Tuzla Fault in Turkey. The relationship between radon anomalies and seismic activities was evaluated using Dobrovolsky's form. It is shown that not only magnitude of earthquake but also distance from the measurement site should be used for identifying radon anomalies.     

What is the message of a meeting? Analysis and comparison of the 2458 abstracts of the EANM/WCNMB congress in Berlin and the SNM meeting in Toronto in 1998

The abstracts of the joint congress of EANM/ WCNMB in Berlin 1998 and of the 45th Annual Meeting of the Society of Nuclear Medicine in Toronto 1998 have been analysed and compared in terms of comprehensibility, composition, questions at issue, methods, patient/subject number, type of conclusion and duplication of information between the meetings. All 1362 and 1096 abstracts, respectively, were analysed from the abstract books with regard to ten ”hard” and four ”soft” variables. The dominant topics were new radiopharmaceuticals, methods of synthesis, examination methods, evaluation of examinations, investigation algorithms, technical devicesand novel use of radiopharmaceuticals. In addition to these topics, there were numerous reports about established radiopharmaceuticals and techniques, often without a specific merit mentioned. There were also many abstracts with questions outside nuclear medicine, but using such techniques. Few papers reported negative findings or dealt with quality assurance, dosimetry, and cost-effectiveness. Many of the conclusions contained hyperbole. Some abstracts were very extensive and detailed. Sixty-seven contributions conveyed identical information at both meetings. Structured and/or paragraphed abstracts promote clarity and reduce the number of lines that need to be read in order to comprehend the background and aim of the abstract. Such contributions were more frequent at the EANM/WCNMB congress while the SNM meeting covered a wider field with a greater representation of radiophysics, instrumentation, and computer evaluations.     

Do low dose-rate bystander effects influence domestic radon risks?

PURPOSE: Radon risks derive from exposure of bronchio-epithelial cells to high-linear energy transfer (LET) alpha-particles. alpha-particle exposure can result in bystander effects, where irradiated cells emit signals resulting in damage to nearby unirradiated bystander cells. This can result in non-linear dose-response relations, and inverse dose-rate effects. Domestic radon risk estimates are currently extrapolated from miner data, which are at both higher doses and higher dose-rates, so bystander effects on unhit cells could play a large role in the extrapolation of risks from mines to homes. Therefore, we extend an earlier quantitative mechanistic model of bystander effects to include protracted exposure, with the aim of quantifying the significance of the bystander effect for very prolonged exposures. MATERIALS AND METHODS: A model of high-LET bystander effects, originally developed to analyse oncogenic transformation in vitro, is extended to low dose-rates. The model considers radiation response as a superposition of bystander and linear direct e It attributes bystander effects to a small subpopulation of hypersensitive cells, with the bystander contribution dominating the direct contribution at very low acute doses but saturating as the dose increases. Inverse dose-rate effects are attributed to the replenishment of the hypersensitive subpopulation during prolonged irradiation. RESULTS: The model was fitted to dose- and dose-rate-dependent radon-exposed miner data, suggesting that one directly hit target bronchio-epithelial cell can send bystander signals to about 50 neighbouring target cells. The model suggests that a na?ve linear extrapolation of radon miner data to low doses, without accounting for dose-rate, would result in an underestimation of domestic radon risks by about a factor of 4, a value comparable with the empirical estimate applied in the recent BEIR-VI report on radon risk estimation. CONCLUSIONS: Bystander effects represent a plausible quantitative and mechanistic explanation of inverse dose-rate effects by high-LET radiation, resulting in non-linear dose-response relations and a complex interplay between the effects of dose and exposure time. The model presented provides a potential mechanistic underpinning for the empirical exposure-time correction factors applied in the recent BEIR-VI for domestic radon risk estimation.     

Hyoid-laryngeal fractures in hanging: where was the knot in the noose?

The aims of this study were to determine the frequency of hyoid-laryngeal fractures in hanging in relation to the position of the ligature knot, to reconstruct the location of the ligature knot in cases of hanging when the furrow is not detectable on the skin, and to identify the possible mechanism of neck structure injuries. We report a retrospective autopsy study which included 557 cases of suicidal hanging: 413 men and 144 women, with an average age of 52.4 +/- 17.8 years. In 57.3% of them, hyoid-laryngeal fractures were found (average age was 54.3 +/- 16.5 years): 15.1% had only hyoid bone fracture, 26% had only thyroid cartilage fracture and 16.2% had both types of injury at the same time. Hyoid-laryngeal fractures were found more often in persons aged over 30 years. Hyoid bone fracture was a weak predictor of ligature knot position in our sample. Fracture frequencies of the thyroid cartilage show a statistically significant difference in relation to the ligature knot position among persons older than 30 years, which indicated the ipsilateral and posterior position of the knot. Absence or presence of any form of hyoid-laryngeal fracture indicated that knot position was anterior or posterior, respectively. The derived data would be useful for cases where the ligature has been removed from the body of the deceased shortly after hanging, where the noose is unavailable, and in cases where the ligature mark has faded such as with soft ligatures removed promptly or in decomposed bodies.     

Collapse in the Endurance Athlete

KEYPOINTS Mostcasesofcollapsearebenigninnatureandoccurafteranathletecrossesthefinishlineorstopsexercising.Ath leteswhocollapsebeforefinishingaremorelikelytohaveaseriouscondition.Athleteswhoareawakeandalertafterthecollapsearelesslikelytobeseriouslyillthanthosewhohaveadimin ishedlevelofconsciousness.Inevaluatingthecollapsedathlete,itisessentialtocheckvitalsigns(especiallyrectaltemperatureifheatstrokeissuspected),assessfluidstatus(dehydratedvs.fluidoverload),andperformlaboratorytests(bloodsod…     

Pedometer steps/min in physical education: Does the pedometer matter?

ObjectivesThe investigation sought to replicate previous Yamax physical education steps/min findings by quantifying physical activity via pedometry albeit with the Walk4Life (W4L) pedometer. Specifically, the objective was to determine steps/min cut point intervals for the 33% and 50% physical activity (i.e., percent of lesson time engaged in physical activity [%PA]) physical education guidelines via the W4L pedometer.DesignField-based criterion-referenced validation.MethodsData were collected from 75 lessons on 411 fifth- through twelfth-grade (M_age = 13.83 ± 2.17 y) participants who had concurrently measured pedometer and behavioural observation data. The W4L and Yamax pedometer outcome measure was steps/min, and observation measure was %PA. Pearson r correlation and diagnostic (i.e., sensitivity, specificity, and receiver-operating characteristic [ROC] curve) tests were conducted.Results(a) Steps/min and %PA demonstrated a strong relationship (W4L, r = 0.96, p = 0.0001; Yamax, r = 0.96, p = 0.0001), (b) W4L pedometer steps/min accurately discriminated (ROC area under curve ≥ 98%) between achievement or non-achievement of %PA guidelines, (c) the W4L steps/min cut point intervals for the 33%PA guideline (55.0–59.5) were significantly lower than those found for the Yamax pedometer (60.8–65.0), and (d) a borderline overlap was found between W4L (75.7–79.5) and Yamax (79.1–85.8) steps/min cut point intervals for the 50%PA guideline.ConclusionsW4L steps/min demonstrated a strong relationship with %PA, and outstanding accuracy for physical education physical activity guideline discrimination; however, steps/min values indicative of physical education physical activity guideline achievement is pedometer brand dependent, and should be considered for steps/min implementation and surveillance.     

Clinical utility of ¹⁸F FDG-PET/CT in the detection of bone marrow disease in Hodgkin's lymphoma

Objective

The aim of the study was to evaluate the potential role of fludeoxyglucose (FDG)-positron emission tomography (PET)/CT in the detection of bone/bone marrow disease in patients with Hodgkin''s lymphoma (HL).

Methods

We retrospectively reviewed (¹⁸F)-FDG-PET/CT scans of 122 newly diagnosed, biopsy-proven cases of HL performed between November 2009 and June 2010. All the patients were staged before treatment by both PET/CT and bone marrow biopsy (BMB). Patients were subdivided into three groups based on the findings of FDG-PET/CT. Group A consisted of patients showing diffuse FDG uptake, Group B consisted of patients showing unifocal FDG uptake and Group C patients showed multifocal FDG-avid foci on PET/CT scans. Bone marrow results were also reviewed and considered positive if lymphomatous involvement was detected on bone marrow trephine biopsy. BMB results were correlated with FDG-PET/CT findings.

Results

There were 122 patients in total—81 (66.4%) were male and 41 (33.6%) were female. The age range was from 6 years to 78 years (mean 35.70 years). PET/CT was reported as negative for bone/bone marrow involvement in 85 (69.7%) patients, while the remaining 37 showed abnormal FDG uptake. The sensitivity of FDG-PET/CT was calculated to be 100%, the specificity was 76.57%, the negative predictive value was 76.57%, the positive predictive value was 29.72% and the diagnostic accuracy was 78.62%.

Conclusion

¹⁸F-FDG-PET/CT and BMB are complementary in the evaluation of bone marrow disease.Fluorine-18 (¹⁸F)-fludeoxyglucose (FDG) has found widespread use in the diagnosis and staging work-up of lymphomas. One of the most promising applications is in the determination of clinical stage of disease at presentation or recurrence [1]. Accurate staging is essential for planning an effective treatment regimen and minimising side effects and toxicity [2]. Bone marrow infiltration is of prime importance not only in staging the disease but also in the tailoring of treatment protocols [3]. Bone involvement can result from haematogenous spread or by extension from adjacent soft tissues [4,5]. Bone marrow involvement in patients with lymphoma is considered as a sign of generalised disease and with less favourable prognosis. Bone marrow biopsy (BMB) is the established method for the detection of bone marrow infiltration. BMB is generally safe but should not be considered as a risk-free procedure; adverse events (haemorrhage, infection etc) have been reported in about 0.12% of cases [6]. It is an invasive and painful experience for the patients and it sometimes results in only a small sample which may turn out to be inconclusive. Bone marrow involvement is diagnosed in 50–80% of patients with low-grade non-Hodgkin''s lymphoma (NHL), 25–40% of those with high-grade NHL and 5–14% of those with Hodgkin''s lymphoma (HL) [6,7]. Lymphoma staging is based on Ann Arbor classification with Cotswolds modifications [8], which includes CT and BMB. Radiologically, CT may depict cortical bone changes but has low sensitivity for early bone marrow involvement [8,9]. Unilateral or bilateral BMB of the dorsal iliac crest is considered as the standard method for detecting bone marrow involvement complemented by MRI when needed [2,10-12]. The potential role of FDG-positron emission tomography (PET)/CT is yet to be determined for the assessment of bone marrow involvement, as very few systematic studies have been carried out in this regard. Since the advent of FDG-PET/CT, functional imaging has emerged as an important imaging tool in differentiating viable tumour tissue from necrotic and therapy-induced fibrosis [13,14]. The aim of the current study was to correlate BMB and PET/CT results as part of baseline staging work-up and to assess the clinical utility of FDG-PET/CT in the detection of bone/bone marrow disease.     

FDG-PET/CT imaging in the management of HIV-associated multicentric Castleman’s disease

Purpose  To evaluate the role of FDG-PET/CT scanning in the management of HIV-associated multicentric Castleman’s disease (MCD) a rare lymphoproliferative disorder associated with infection by human herpesvirus 8 (HHV8). Materials and methods  Nine patients with histologically confirmed MCD underwent fused FDG-PET/CT scans at initial MCD diagnosis (n = 3), at MCD relapse (n = 4), or during remission (n = 2). All seven patients with active MCD had markedly elevated plasma HHV8 viral loads, but the patients in remission had no HHV8 viraemia. The three patients with newly diagnosed MCD were not on antiretroviral therapy at the time of imaging, but the other six were all on fully suppressive antiretroviral regimens. Results  In the seven patients with active MCD (newly diagnosed or relapse) 33/91 lymph node groups (36%) included radiologically enlarged nodes on the CT scan, whilst 57/91 lymph node groups (63%) showed enhanced FDG uptake on the PET scan. In scans from patients in remission, there were no enlarged lymph nodes on the CT scan but 3 lymph nodes (11%) demonstrated enhanced FDG uptake. The median SUV recorded for the seven patients with active MCD was 4.8 (range 2.6–9.3) which was significantly higher than the median value of 2.5 recorded for the patients in remission (Mann-Whitney U test, p = 0.011). Conclusion  Despite the small number of patients, in HIV-positive individuals with active MCD, FDG-PET scans more frequently detected abnormal uptake than CT scans detected enlarged lymph nodes. FDG-PET scanning has a useful role in the management of HIV-associated MCD in selecting appropriate sites for biopsy, and in staging and monitoring these lymphoproliferations.     

What is the message of a meeting? Analysis and comparison of the 2458 abstracts of the EANM/WCNMB congress in Berlin and the SNM meeting in Toronto in 1998. European Association of Nuclear Medicine/World Federation of Nuclear Medicine and Biology, and the Society of Nuclear Medicine

The abstracts of the joint congress of EANM/WCNMB in Berlin 1998 and of the 45th Annual Meeting of the Society of Nuclear Medicine in Toronto 1998 have been analysed and compared in terms of comprehensibility, composition, questions at issue, methods, patient/subject number, type of conclusion and duplication of information between the meetings. All 1362 and 1096 abstracts, respectively, were analysed from the abstract books with regard to ten "hard" and four "soft" variables. The dominant topics were new radiopharmaceuticals, methods of synthesis, examination methods, evaluation of examinations, investigation algorithms, technical devices and novel use of radiopharmaceuticals. In addition to these topics, there were numerous reports about established radiopharmaceuticals and techniques, often without a specific merit mentioned. There were also many abstracts with questions outside nuclear medicine, but using such techniques. Few papers reported negative findings or dealt with quality assurance, dosimetry, and cost-effectiveness. Many of the conclusions contained hyperbole. Some abstracts were very extensive and detailed. Sixty-seven contributions conveyed identical information at both meetings. Structured and/or paragraphed abstracts promote clarity and reduce the number of lines that need to be read in order to comprehend the background and aim of the abstract. Such contributions were more frequent at the EANM/WCNMB congress while the SNM meeting covered a wider field with a greater representation of radiophysics, instrumentation, and computer evaluations.     

Imaging the heart’s brain: Simultaneous innervation/perfusion analysis in the era of new CZT cameras

Journal of Nuclear Cardiology -     

Which FDG/PET parameters of the primary tumors in colon or sigmoid cancer provide the best correlation with the pathological findings?

Background To compare ¹⁸F-fluoro-2-deoxdeoxyglucose (FDG) positron emission tomography (PET) related parameters of primary colon or sigmoid cancer (CSC) with pathological findings.     

Does chemotherapy influence the quantification of SUV when contrast-enhanced CT is used in PET/CT in lymphoma?

Purpose In patients with lymphoma, we investigated the impact of contrast-enhanced CT on PET attenuation correction in lesions and normal tissues, particularly when PET/CT was performed after chemotherapy. Methods Fifty patients (51±18 years) with Hodgkin’s disease (n=17) or non-Hodgkin lymphomas (n=33) were studied before and after chemotherapy. PET/CT scans were performed 60 min after injection of FDG. Iopamiron 300 (iopamidol, 1.5 cc/kg) was injected immediately afterwards, followed 50 s later by a second craniocaudal CT (CT+). PET images were successively reconstructed using the unenhanced CT (PET−) and the CT+ (PET+) for attenuation correction, using iterative reconstruction (4 iterations, 8 subsets, 5 mm post-filtering). HU_mean, SUV_max and SUV_mean were measured before and after chemotherapy in ten non-tumoural ROIs [aorta, femur, kidney, lung, iliopsoas muscle, occipital cortex, T12 vertebra, liver, spleen and inferior vena cava (IVC)] and in tumoural lymphadenopathies or malignant tissues (n=397 and 51 VOIs respectively before and after chemotherapy) using a 3D-thresholding method (identical threshold for PET− and PET+). ROIs were defined on the PET− and automatically applied on the unenhanced CT (CT−), the CT+ and the PET+. Results In the non-tumoural tissues, HU_mean increased significantly in the CT+ compared with the CT− in the vessels and the highly vascularised organs, and slight increases were observed in the occipital cortex (+11%), the iliopsoas muscle (+6%) and the femur (+3%). SUV_max increased significantly in the PET+ compared with the PET− in the aorta (+14%), the liver (+10%), the spleen (+10%) and the IVC (+12%). SUV_mean increased significantly in the PET+ compared with the PET− in the aorta (+15%), the kidney (+13%), the liver (+11%), the spleen (10%) and the IVC (+12%). In the lesions, HU_mean was not significantly different before and after chemotherapy, whatever the normal region considered. SUV_max increased significantly after treatment in the T12 vertebra (+12%). SUV_mean increased significantly after treatment in the T12 vertebra (+13%) and in the liver (+12%). HU_mean increased significantly in the CT+ compared with the CT− in the lesions (+55%) before chemotherapy. SUV_max and SUV_mean increased significantly in the PET+ compared with the PET− in the lesions (+4%) only before chemotherapy. No significant difference was seen in measurements (HU_mean, SUV_max and SUV_mean) after chemotherapy. Conclusion Our study demonstrates that use of enhanced CT for attenuation correction has a negligible effect on quantification at staging and after chemotherapy. A “single-shot” enhanced PET/CT may thus be performed in the evaluation of patients with lymphoma at staging, during treatment and at follow-up.