Long-term radon-222 (222Rn) and hydroclimatic dataset for a coastal estuary, Corpus Christi Bay, Texas

The dataset features radon-222 (222Rn), a radioactive tracer naturally present and frequently employed to assess submarine groundwater discharge (SGD). This collection is part of a study aimed at refining SGD estimations in shallow estuaries through the prediction of 222Rn variations using accessible hydroclimatic parameters [1]. The dataset includes measurements of 222Rn in water gathered recurringly from Aug. 2019 to June 2021 at half-hour intervals, at a monitoring station near the shore in Corpus Christi Bay, TX, USA (n = 10,660). Additionally, the data set encompasses continuous, accessible hydroclimatic parameters (e.g., wind speed and direction, atmospheric pressure, water temperature, tide height, creek and river discharge rate, n = 35,088). These parameters were integrated into two machine learning models - Random forest (RF) and Deep Neural Network (DNN) - aiming to interpret the variations in 222Rn and forecast during the data gap. A generalized additive model (GAM) was utilized, focusing on interpreting the variability in 222Rn inventory, particularly influenced by windspeed and direction. The tools and data presented herein afford prospects to 1) forecast 222Rn inventories in areas with significant data voids using only publicly accessible hydroclimatic parameters, and 2) refine SGD estimations affected by wind, thereby offering valuable insights for the planning of field expeditions and the development of management strategies for coastal water and solute budgets.

A third of the radiotracer dose: two decades of progress in pediatric [18F]fluorodeoxyglucose PET/CT and PET/MR imaging

OBJECTIVES

To assess the evolution of administered radiotracer activity for F-18-fluorodeoxyglucose (18F-FDG) PET/CT or PET/MR in pediatric patients (0-16 years) between years 2000 and 2021.

METHODS

Pediatric patients (≤ 16 years) referred for 18F-FDG PET/CT or PET/MR imaging of the body during 2000 and 2021 were retrospectively included. The amount of administered radiotracer activity in megabecquerel (MBq) was recorded, and signal-to-noise ratio (SNR) was measured in the right liver lobe with a 4 cm3 volume of interest as an indicator for objective image quality. Descriptive statistics were computed.

RESULTS

Two hundred forty-three children and adolescents underwent a total of 466 examinations. The median injected 18F-FDG activity in MBq decreased significantly from 296 MBq in 2000-2005 to 100 MBq in 2016-2021 (p < 0.001), equaling approximately one-third of the initial amount. The median SNR ratio was stable during all years with 11.7 (interquartile range [IQR] 10.7-12.9, p = 0.133).

CONCLUSIONS

Children have benefited from a massive reduction in the administered 18F-FDG dose over the past 20 years without compromising objective image quality.

CLINICAL RELEVANCE STATEMENT

Radiotracer dose was reduced considerably over the past two decades of pediatric F-18-fluorodeoxyglucose PET/CT and PET/MR imaging highlighting the success of technical innovations in pediatric PET imaging.

KEY POINTS

• The evolution of administered radiotracer activity for F-18-fluorodeoxyglucose (18F-FDG) PET/CT or PET/MR in pediatric patients (0-16 years) between 2000 and 2021 was assessed. • The injected tracer activity decreased by 66% during the study period from 296 megabecquerel (MBq) to 100 MBq (p < 0.001). • The continuous implementation of technical innovations in pediatric hybrid 18F-FDG PET has led to a steady decrease in the amount of applied radiotracer, which is particularly beneficial for children who are more sensitive to radiation.

光生物调节加速脑组织间液引流及其机制

OBJECTIVE

To evaluate the effect of photobiomodulation (PBM) on the drainage of brain interstitial fluid (ISF) and to investigate the possible mechanism of the positive effect of PBM on Alzheimer's disease (AD).

METHODS

Twenty-four SD male rats were randomly divided into PBM group (n=12), sham PBM group (n=6), and negative control group (n=6). According to the injection site of tracer, the PBM group was further divided into PBM-ipsilateral traced group (n=6) and PBM-contralateral traced group (n=6). Rats in the PBM group and the sham PBM group were exposed to the dura minimally invasively on the skull corresponding to the frontal cortical area reached by ISF drainage from caudate nucleus region. The PBM group was irradiated by using 630 nm red light (5-6 mW/cm²), following an irradiation of 5 min with a 2 min pause, and a total of 5 times; the sham PBM group was kept in the same position for the same time using the light without power. The negative control group was kept without any measure. After PBM, tracer was injected into caudate nucleus of each group. The changes of ISF drainage in caudate nucleus were observed according to the diffusion and distribution of tracer molecule by tracer-based magnetic resonance imaging, and the structural changes of brain extracellular space (ECS) were analyzed by diffusion rate in ECS-mapping (D_ECS-mapping) technique. Finally, parameters reflecting the structure of brain ECS and the drainage of ISF were obtained: volume fraction (α), tortuo-sity (λ), half-life (T_1/2), and D_ECS. The differences of parameters among different groups were compared to analyze the effect of PBM on brain ECS and ISF. One-Way ANOVA post hoc tests and independent sample t test were used for statistical analysis.

RESULTS

The parameters including T_1/2, D_ECS, and λ were significantly different among the PBM-ipsilateral traced group, the PBM-contralateral traced group, and the sham PBM group (F=79.286, P < 0.001; F=13.458, P < 0.001; F=10.948, P=0.001), while there was no difference in the parameter α of brain ECS among the three groups (F=1.217, P=0.324). Compared with the sham PBM group and the PBM-contralateral traced group, the PBM-ipsilateral traced group had a significant decrease in the parameter T_1/2 [(45.45±6.76) min vs. (76.01±3.44) min, P < 0.001; (45.45±6.76) min vs. (78.07±4.27) min, P < 0.001], representing a significant acceleration of ISF drainage; the PBM-ipsilateral traced group had a significant increase in the parameter D_ECS [(4.51±0.77)×10^-4 mm²/s vs. (3.15±0.44)×10^-4 mm²/s, P < 0.001; (4.51±0.77)×10^-4 mm²/s vs. (3.01±0.38)×10^-4 mm²/s, P < 0.001], representing a significantly increased molecular diffusion rate of in the brain ECS; the PBM-ipsilateral traced group had a significant decrease in the parameter λ (1.51±0.21 vs. 1.85±0.12, P=0.001; 1.51±0.21 vs. 1.89±0.11, P=0.001), representing a significant decrease in the degree of tortuosity in the brain ECS.

CONCLUSION

PBM can regulate the brain ISF drainage actively, which may be one of the potential mechanisms of the effect of PBM therapy on AD. This study provides a new method for enhancing the brain function via ECS pathway.

[Positron emission tomography with computed tomography/magnetic resonance imaging for primary staging of prostate cancer]

CLINICAL/METHODOLOGICAL ISSUE

Prostate cancer is the most common malignancy and the second leading cause of cancer-related death in men. Accurate imaging diagnosis and staging are crucial for patient management and treatment. The role of nuclear medicine in the diagnosis of prostate cancer has evolved rapidly in recent years due to the availability of hybrid imaging with radiopharmaceuticals targeting the prostate-specific membrane antigen (PSMA).

STANDARD RADIOLOGICAL PROCEDURES

Hybrid imaging provides higher diagnostic accuracy compared to conventional imaging and has a significant impact on clinical management. Numerous radiotracers have been used in clinical applications, with PSMA ligands being the most commonly used.

METHODOLOGICAL INNOVATIONS

Hybrid imaging provides higher diagnostic accuracy for lymph node and bone metastases compared to conventional imaging and has a significant impact on clinical management.

PERFORMANCE

The high accuracy for primary staging in high-risk prostate cancer using PSMA ligands has led to the inclusion of PSMA positron emission tomography (PET)/computed tomography (CT) in the new German S3 guideline for primary staging of prostate cancer.

PURPOSE

The aim of this article is to provide an overview of the use of PET imaging in the primary diagnosis of prostate cancer, to present the most commonly used radiotracers, and to highlight the results of recent studies.

[What actually happens … in hybrid imaging?]

CLINICAL/METHODOLOGICAL ISSUE

The goal of this article is to shed light on innovations in perfusion imaging and the fields of application that have opened up in hybrid imaging of the heart.

STANDARD RADIOLOGICAL METHODS

As before, the most commonly used modalities in hybrid imaging are single photon emission computed tomography (SPECT) and positron emission tomography/computed tomography (PET/CT). Perfusion tracers and the radioactively labeled glucose analog ¹⁸F‑fluorodeoxyglucose (FDG) are commonly used for vitality imaging.

METHODICAL INNOVATIONS

Use of PET/MRI (magnetic resonance imaging) is becoming increasingly widespread. In addition, FDG is also increasingly applied in imaging infectious and inflammatory myocardial diseases. Furthermore, novel tracers are used, such as the amyloid-specific tracers in cardiac amyloidosis.

PERFORMANCE

Overall, this development has led to an increasing use of hybrid imaging techniques. These still include myocardial perfusion imaging, but are also used in inflammatory and infectious diseases such as endocarditis, myocarditis and sarcoidosis, as well as in underestimated diseases such as cardiac amyloidosis. The use of tracers has led to the creation of new fields of application in hybrid imaging.

PRACTICAL RECOMMENDATIONS

Hybrid imaging combining myocardial perfusion and coronary visualization seems to be particularly advantageous in complex cases such as multivessel disease. In infectious and inflammatory myocardial diseases, FDG PET/CT or PET/MRI has clearly demonstrated its added value. New fields of application are very promising, but their significance has yet to be clearly demonstrated.

18F-NaF uptake in dentomaxillofacial bones as a result of oral alterations: a positron emission tomography/computerized tomography scanning study

OBJECTIVES

¹⁸F-NaF is a bone scanning radiotracer that reflects changes in bone metabolism, and it is applied in oncology to scan bone tumors or metastasis. Dentomaxillofacial alterations can lead to ¹⁸F-NaF uptake and could lead to false-positive results in PET/CT examinations. Hence, the objective of this research was to verify if the uptake of ¹⁸F-NaF in the mandible or maxilla is correlated to the presence of odontogenic alterations, which could lead to false-positive results in positron emission tomography/computerized tomography (PET/CT) examinations.

METHODS

42 patients who underwent ¹⁸F-NaF PET/CT examinations and panoramic radiographs to detect bone metastasis and to assess oral conditions before oncologic treatment were included. Edentulous patients and patients with neoplasms in the maxillofacial area, and those whose imaging examinations had technical failures were excluded from the study.

RESULTS

A total of 252 areas from panoramic radiographs and PET/CT examinations were assessed. It was observed that the presence of periodontal bone loss resulted in a higher number of cases with false negatives. Accuracy, sensitivity, and specificity of ¹⁸F-NaF uptake-regardless of the type of odontogenic origin alteration-were 76.2%, 53.3%, and 89.4%, respectively.

CONCLUSION

¹⁸F-NaF uptake in the maxilla or mandible could be influenced by oral alterations in the alveolar bones. The alterations in the oral cavity that lead to ¹⁸F-NaF accumulation should be recognized by medical radiologists to prevent false-positive results in PET/CT examinations using the tracer ¹⁸F-NaF.

Submarine groundwater discharge data at meter scale (223Ra, 224Ra, 226Ra, 228Ra and 222Rn) in Indian River Bay (Delaware, US)

Submarine groundwater discharge (SGD) was sampled at high-spatial resolution in Indian River Bay, DE, USA, in July 2016 to characterize the spatial variability of the activity of the radium and radon isotopes commonly used to estimate SGD. These data were part of an investigation into the methods and challenges of characterizing SGD rates and variability, especially in the coastal aquifer transition from freshwater to saltwater (Hydrogeological processes and near shore spatial variability of radium and radon isotopes for the characterization of submarine groundwater discharge (Duque et al., 2019)). Samples were collected with seepage meters and minipiezometers to obtain sufficient volumes for analytical characterization. Seepage meter samples (for ²²³Ra, ²²⁴Ra, ²²⁶Ra, and ²²⁸Ra) were collected at two-hour intervals over a semi-diurnal tidal cycle from 30 seepage meters. Samples for ²²²Rn characterization were collected with a minipiezometer from 25 cm below the bay bed at each seepage meter location. All samples were analyzed with standard and state of the art procedures.

Pulmonary inhalation-perfusion scintigraphy in the evaluation of bronchoscopic treatment of bronchopleural fistula

Objective

To evaluate the use of pulmonary inhalation-perfusion scintigraphy as an alternative method of investigation and follow-up in patients with bronchopleural fistula (BPF).

Materials and Methods

Nine patients with BPFs were treated through the off-label use of a transcatheter atrial septal defect occluder, placed endoscopically, and were followed with pulmonary inhalation-perfusion scintigraphy, involving inhalation, via a nebulizer, of 900-1300 MBq (25-35 mCi) of technetium-99m-labeled diethylenetriaminepentaacetic acid and single-photon emission computed tomography with a dual-head gamma camera.

Results

In two cases, there was a residual air leak that was not identified by bronchoscopy or the methylene blue test but was detected only by pulmonary inhalation-perfusion scintigraphy. Those results correlated with the evolution of the patients, both of whom showed late signs of air leak, which confirmed the scintigraphy findings. In the patients with complete resolution of symptoms and fistula closure seen on bronchoscopy, the scintigraphy was completely negative. In cases of failure to close the BPF, the scintigraphy confirmed the persistence of the air leak. In two patients, scintigraphy was the only method to show residual BPF, the fistula no longer being seen on bronchoscopy.

Conclusion

We found pulmonary inhalation-perfusion scintigraphy to be a useful tool for identifying a residual BPF, as well as being an alternative method of investigating BPFs and of monitoring the affected patients.

Uptake and distribution of organo-iodine in deep-sea corals

Understanding iodine concentration, transport, and bioavailability is essential in evaluating iodine's impact to the environment and its effectiveness as an environmental biogeotracer. While iodine and its radionuclides have proven to be important tracers in geologic and biologic studies, little is known about transport of this element to the deep sea and subsequent uptake in deep-sea coral habitats. Results presented here on deep-sea black coral iodine speciation and iodine isotope variability provides key information on iodine behavior in natural and anthropogenic environments, and its geochemical pathway in the Gulf of Mexico. Organo-iodine is the dominant iodine species in the black corals, demonstrating that binding of iodine to organic matter plays an important role in the transport and transfer of iodine to the deep-sea corals. The identification of growth bands captured in high-resolution scanning electron images (SEM) with synchronous peaks in iodine variability suggest that riverine delivery of terrestrial-derived organo-iodine is the most plausible explanation to account for annual periodicity in the deep-sea coral geochemistry. Whereas previous studies have suggested the presence of annual growth rings in deep-sea corals, this present study provides a mechanism to explain the formation of annual growth bands. Furthermore, deep-sea coral ages based on iodine peak counts agree well with those ages derived from radiocarbon (¹⁴C) measurements. These results hold promise for developing chronologies independent of ¹⁴C dating, which is an essential component in constraining reservoir ages and using radiocarbon as a tracer of ocean circulation. Furthermore, the presence of enriched ¹²⁹I/¹²⁷I ratios during the most recent period of skeleton growth is linked to nuclear weapons testing during the 1960s. The sensitivity of the coral skeleton to record changes in surface water ¹²⁹I composition provides further evidence that iodine composition and isotope variability captured in proteinaceous deep-sea corals is a promising geochronometer as well as an emerging tracer for continental material flux.

Reconstructing surface ocean circulation with 129I time series records from corals

The long-lived radionuclide ¹²⁹I (half-life: 15.7 × 10⁶ yr) is well-known as a useful environmental tracer. At present, the global ¹²⁹I in surface water is about 1-2 orders of magnitude higher than pre-1960 levels. Since the 1990s, anthropogenic ¹²⁹I produced from industrial nuclear fuels reprocessing plants has been the primary source of ¹²⁹I in marine surface waters of the Atlantic and around the globe. Here we present four coral ¹²⁹I time series records from: 1) Con Dao and 2) Xisha Islands, the South China Sea, 3) Rabaul, Papua New Guinea and 4) Guam. The Con Dao coral ¹²⁹I record features a sudden increase in ¹²⁹I in 1959. The Xisha coral shows similar peak values for ¹²⁹I as the Con Dao coral, punctuated by distinct low values, likely due to the upwelling in the central South China Sea. The Rabaul coral features much more gradual ¹²⁹I increases in the 1970s, similar to a published record from the Solomon Islands. The Guam coral ¹²⁹I record contains the largest measured values for any site, with two large peaks, in 1955 and 1959. Nuclear weapons testing was the primary ¹²⁹I source in the Western Pacific in the latter part of the 20th Century, notably from testing in the Marshall Islands. The Guam 1955 peak and Con Dao 1959 increases are likely from the 1954 Castle Bravo test, and the Operation Hardtack I test is the most likely source of the 1959 peak observed at Guam. Radiogenic iodine found in coral was carried primarily through surface ocean currents. The coral ¹²⁹I time series data provide a broad picture of the surface distribution and depth penetration of ¹²⁹I in the Pacific Ocean over the past 60 years.

[Multiparametric imaging with simultaneous MRI/PET: Methodological aspects and possible clinical applications]

BACKGROUND

Combined MRI/PET enables the acquisition of a variety of imaging parameters during one examination, including anatomical and functional information such as perfusion, diffusion, and metabolism.

OBJECTIVE

The present article summarizes these methods and their applications in multiparametric imaging via MRI/PET.

RESULTS

Numerous studies have shown that the combination of these parameters can improve diagnostic accuracy for many applications, including the imaging of oncological, neurological, and inflammatory conditions. Because of the amount and the complexity of the acquired multiparametric data, there is a need for advanced analysis tools, such as methods of parameter selection and data classification.

DISCUSSION

Currently, the clinical application of this process still has limitations. On the one hand, software for the fast calculation and standardized evaluation of the imaging data acquired is still lacking. On the other hand, there are deficiencies when comparing the results because of a lack of standardization of the assessment and diagnostic procedure.