Incidental Tc-99m MIBI Lung Uptake in Parathyroid Scintigraphy.

Diffuse Tc-99m MIBI uptake in the lungs during parathyroid scintigraphy is exceptional, and only a few cases have described this unusual aspect. The differential diagnostic of this funding is a challenge when interpreting the examination, since it can be a sign of serious pathology. We report the case of unexpected diffusely increased Tc-99m MIBI uptake in bilateral lung fields in a patient with left cardiac dysfunction.

Development and validation of a Medaka fish voxel-based model for internal ionizing radiation dosimetry.

In this paper, we present a voxel-based phantom of Medaka fish that can be used to assess the internal radiation doses that would be absorbed by different organs of this fish species if exposed to radioactive wastewater released into the ocean. The geometric model for fish was generated based on available Wavefront Object files for smooth-bodied Medaka fish organs, whereas due to the lack of Medaka fish material specification, the material model was constructed using material data appropriate to ICRP 110 adult male voxel-based phantom. Absorbed Fractions (AFs) and Specific Absorbed Fractions (SAFs) were calculated for eight organs of major interest as sources and for each organ as target at a set of discrete photon, electron, alpha and neutron energies. To validate the present model the calculated AFs in the studied organs were compared to ones obtained in similar organs in a voxel-based phantom of another teleost fish species called Limanda limanda. The results presented are consistent with the reference dosimetric data. We concluded that the Medaka model can be used in radioecology research to improve marine radiation protection.

Comparison between InterDosi and MCNP in the estimation of photon SAFs on a series of ICRP pediatric voxelized phantoms.

In the present work, a new Monte Carlo Geant4 based code called InterDosi 1.0, was used to simulate specific absorbed fractions (SAFs) in the six reference pediatric voxel-based phantoms developed by the International Commission on Radiological Protection (ICRP). The aim of this study was to assess the ability of this code to estimate SAFs in a variety of voxel-based phantoms. A large number of photon SAFs were calculated for pairs of organs corresponding to three sources and 170 target organs/regions. A total of 108 initial photons were uniformly emitted from the source organs with eight discrete energies. In order to speed up the calculation of SAFs, Monte Carlo multithreaded simulations were started on a workstation with 12 threads, and a Geant4 tracking optimization technique was applied that consists in skipping the voxel boundaries when two adjacent voxels share the same material, which seems to reduce the simulation time by an average of approximately 36%. The results showed good agreement with the reference data produced through the MCNP 2.7 code, with average and maximum absolute discrepancies of 0.5% and 7.68%, respectively. We concluded that these results confirm the feasibility of InterDosi code to perform photon internal dosimetry calculations at a voxel level.

Validation of the DoseCalcs Monte Carlo code for estimating the 18F S-values for ICRP adult and 15-year-old male and female phantoms.

Internal radiation exposure using radiopharmaceuticals, as in nuclear medicine procedures, necessitates the estimation of the S-value to determine and improve the estimates of absorbed doses in at-risk organs and tissues. The S value is defined as the absorbed dose in the target organ per unit of nuclear transformation in the source organ. It is calculated using the specific absorbed fraction, which is an important quantity that connects the deposited energy in the target and emitting source organs. In this study, we applied DoseCalcs, a new Geant4-based tool, to estimate the S values of [Formula: see text]F using nuclear data from ICRP Publication 107. Geometrical data from ICRP Publications 110 and 143 were used to select four models representing male and female phantoms for adults and 15 years old to study the variability in the S-values arising from variations in anatomy and initial energy validations, because we used the [Formula: see text] mean energy instead of the full beta spectrum. The [Formula: see text]F-released photons and [Formula: see text] from 26 source organs were tracked using the Geant4 Livermore package. Accordingly, the S-values were calculated for 141 target organs. The results for the adult male and female phantoms were compared with the OpenDose reference data. These results agreed well with OpenDose, the average ratio for self-absorption S-values was 1.015, and the average ratios for the cross-irradiation were 1.2 and 1.22 for the AM and AF, respectively. This indicates the accuracy of DoseCalcs for subsequent use in estimating [Formula: see text]F S-values using voxelized geometries.

Snow Leopard Appearance of Subcutaneous Panniculitis such as T-cell Lymphoma on 18F-FDG PET/CT.

Subcutaneous panniculitis such as T-cell lymphoma (SPTCL) is a very rare disorder. Patients usually present with multiple subcutaneous nodules on the extremities without visceral disease. Dissemination to extra-cutaneous sites is unusual. Only a few cases of SPTCL have been reported in the literature describing the findings of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Here, we represent an interesting and unusual case of diffuse SPTCL with snow Leopard skin appearance on 18F-FDG PET/computed tomography.

Neurolymphomatosis diagnosed on [18F]FDG PET/CT.

Fluorine-18-deoxyglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) has been shown to be superior to other conventional imaging modalities in the detection of extra-nodal lymphomatous localizations. Especially in neurolymphomatosis which is rarely encountered in high-grade lymphomas. We report a case of a woman diagnosed with non-Hodgkin lymphoma, whose initial staging with [18F]FDG PET/CT showed increased [18F]FDG uptake along the brachial and sacral plexuses. [18F]FDG PET/CT remains the most appropriate diagnostic tool in these cases, whose prognosis is often poor.

COVID-19 Pneumonia was Incidentally Detected on 18F-Fluorocholine PET/CT in a Work-up for Prostate Cancer.

This is a presentation of the case of a patient who underwent 18F-fluorocholine positron emission/computed tomography to stage a prostate cancer with incidentally found bilateral pneumonia. A high prevalence of incidental pneumonia is very probable under the current circumstance of coronavirus disease-2019 (COVID-19) pandemic, and oncological patients are at increased risk of COVID-19 with poorer outcome. The lung inflammatory burden in the case of COVID-19 infection can be demonstrated by 18F-fluorocholine.

Intercomparison of S-Factor values calculated in Zubal voxelized phantom for eleven radionuclides commonly used in targeted prostate cancer therapy.

In this study we aimed at comparing various radionuclides ordinarily used in targeted prostate cancer therapy, thereby evaluating S-Factor parameter in the prostate organs as well as in its surrounding healthy tissues, namely the urinary bladder and rectum. InterDosi code version 1.1 was used to estimate S-Factor values in Zubal voxelized phantom for 11 radionuclides, namely 225Ac, 21At, 67Cu, 125I, 131I, 212Pb, 177Lu, 223Ra, 161 Tb, 227Th and 90Y. The prostate organ was considered the source of different ionizing radiation emitted by the radionuclides cited above. The results showed that among all studied alpha-emitting radionuclides, 225 Ac, 223 Ra and 227 Th provide equidistantly the highest self-irradiation S-Factors whereas, 211At provides the lowest cross-irradiation S-Factors. On the other hand, considering only beta-emitting radionuclides, it is shown that 177Lu and 90Y induce respectively lowest and highest cross-absorption S-Factors on the surrounding healthy organs. We conclude that 177Lu and 211At are more adequate for prostate radionuclide therapy because they can relatively prevent surrounding organs from radiation toxicity and at the same time provide sufficient dose to treat the prostate tumor.

InterDosi Monte Carlo study of radiation exposure of a reference crab phantom due to radioactive wastewater deposited in marine environment following the Fukushima nuclear accident.

S-values are typically used to quantify internal doses of biota internally due to the incorporation of radionuclides. In this study, the InterDosi 1.0 Monte Carlo code was used to estimate S-values in five main organs of a crab phantom as well as in surrounding seawater for eleven radionuclides, namely 3H, 14C, 134Cs, 137Cs, 60Co, 125Sb, 90Sr, 129I, 99Tc, 106Ru, and 238Pu. After the Fukushima accident, these radionuclides have been detected in wastewater by the Japan Nuclear Regulatory Authority. In this work, S-values were calculated for all crab organs and the surrounding seawater. These values can be used in conjunction with any measured activities in water, to determine internal doses absorbed by crab organs. Furthermore, it is shown that for a self-absorption condition the studied radionuclides can be classified into five main categories, with 238Pu showing the highest S-values for any organ. Moreover, the results demonstrate that the obtained S-values decrease with increasing organ mass. In contrast, for a cross-absorption condition, the studied organs can be classified into seven main categories. In addition, by taking seawater as a source of irradiation, 238Pu had the highest cross-absorption S-values in two organs of particular biological relevance, the heart and gonads, when compared to the remaining radionuclides. It is concluded that due to the pre-calculated S-value database of a reference crab, it will become easier to use this organism as a bio indicator to study any radiation-induced effects on the marine environment.

Bleomycin-Induced Lung Toxicity in Hodgkin's Lymphoma: Risk Factors in the Positron Emission Tomography Era.

Introduction Bleomycin is a major antimitotic agent in the first-line treatment for Hodgkin's lymphoma. The main limitation of its use is its pulmonary toxicity. The objectives of this study are to find out the risk factors for the occurrence of bleomycin-induced lung toxicity in patients with Hodgkin's lymphoma and, on the other hand, to determine if positron emission tomography scan is a reliable means of early detection of this toxicity. Methods This is a retrospective study conducted in the clinical Hematology Department of Mohammed V Military Instruction Hospital, Rabat, Morocco. All patients with Hodgkin's lymphoma and treated with a bleomycin-based chemotherapy were included. The impact of different clinical and biological factors on the risk of bleomycin-induced lung toxicity occurrence was assessed using univariate and multivariate logistic regression. The benefit of positron emission tomography, usually performed as part of the re-assessment of Hodgkin's lymphoma after two and four cycles, has been evaluated in the detection of bleomycin-induced lung toxicity. Results Among 124 patients included in the study, 18 (14.5%) patients experienced bleomycin-induced lung toxicity. On multivariate analysis, smoking (p = 0.038) and the use of the ABVD regimen (doxorubicin, bleomycin, vinblastine, and dacarbazine) compared to the escalated BEACOPPe regimen (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone) (p = 0.018) were statistically significant risk factors. After two and four courses of therapy, the positron emission tomography was able to predict the occurrence of bleomycin-induced lung toxicity before the appearance of clinical symptoms only in 36.4 % and 12.5% of patients, respectively. Conclusion Studies to identify risk factors for the development of bleomycin-induced lung toxicity are crucial to reduce toxicity in the treatment of Hodgkin's lymphoma. However, two- and four-cycle positron emission tomography scans cannot be considered as a reliable means of early detection of this toxicity.

Estimation of electron-specific absorbed fractions with the InterDosi code using ICRP adult female voxel-based phantom.

The International Commission on Radiological Protection (ICRP) through its publications recommends the estimation of Specific Absorbed Fractions (SAFs) using voxelized phantoms in order to assess the doses internally absorbed by organs exposed to ionizing radiation. In the present work, we report a large set of SAFs calculated using the ICRP Adult Female (ICRP-AF) phantom. The new Geant4-based code called InterDosi version 1.0 was used to simulate monoenergetic electrons of 20 different energies, ranging from 0.005 to 10 MeV, emitted uniformly from 18 different source organs. In order to estimate SAFs in 169 target organs/regions, 360 Monte Carlo multithreaded simulations were run on 32 CPUs of the HPC-MARWAN-CNRST computing grid. The calculated SAFs were compared to the recent results obtained using GATE 8.1 code and published by the OpenDose collaboration. It is shown that the obtained results are in well-agreement with the reference values, with absolute discrepancies less than 0.6% for a self-absorption condition and less than 5% in almost all energies for a cross-absorption condition. We concluded that InterDosi code might be used for dosimetry of internal electron emitters.

InterDosi Monte Carlo simulations of photon and electron specific absorbed fractions in a voxel-based crab phantom.

InterDosi is a new in-house Monte Carlo code that aims at facilitating the use of the Geant4 toolkit for internal dosimetry using voxel-based phantoms. In the present work the dosimetric capabilities of this code are assessed by calculating self-irradiation specific absorbed fractions (SI-SAFs) in a voxel-based crab phantom. Recent standard human organ compositions and densities taken from ICRP Publication 110 have been used for material specifications of the four organs of a crab, namely, the heart, hepatopancreas, gills, and gonads, whereas the material assigned to the crab shell has been modeled based on literature values. The SI-SAFs were calculated for mono-energetic photons of energies between 10 and 4000 keV, and for mono-energetic electrons of energies between 100 and 4000 keV. The statistical errors corresponding to the calculated SI-SAFs were all less than 0.01%. The results obtained demonstrate that the simulated masses and volumes of the crab organs are in good agreement with those presented in the literature. In addition, the dosimetric results show that the calculated SI-SAFs are generally consistent with those reported in the literature, with some moderate differences due to differences in material specification. It is concluded that the InterDosi code can be successfully employed in internal dose estimations in small organisms, and it is suggested that material specifications specifically relating to crab tissues should be developed to provide more precise SI-SAFs.

Bilateral renal involvement in diffuse large B-cell lymphoma on fluorodeoxyglucose positron emission tomography/computed tomography.

Secondary renal involvement in patients with diffuse large B-cell lymphoma (DLBCL) is rare and associated with poor prognosis. We, hereby, described a case of a patient diagnosed with DLBCL, in whom bilateral renal involvement was detected on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). The patient received 4 courses of chemotherapy, and follow-up 18F-FDG PET/ CT revealed the complete resolution of the diffuse increased renal 18F-FDG uptake. Renal lymphoma is uncommon and 18F-FDG PET/CT is particularly useful for detecting extranodal involvement in DLBLC.

A rare case of pituitary metastasis from breast cancer detected on fluorodeoxyglucose positron emission tomography/computed tomography that presented as insipid diabetes.

Pituitary metastases are rare, are generally asymptomatic, and often remain undiagnosed. Breast cancer is the most common primary cancer metastasizing to hypophysis in women. However, it is difficult to clinically and radiologically differentiate pituitary metastases from pituitary adenomas. We report a case of pituitary metastases diagnosed on magnetic resonance imaging and positron emission tomography/computed tomography, which was the prime manifestation of a breast cancer in a 46-year-old female. This cancer was revealed by insipid diabetes.

InterDosi simulations of photon and alpha specific absorbed fractions in zubal voxelized phantom.

In this work we used the InterDosi code to estimate photon specific absorbed fractions (SAFs) for some organs of the Zubal adult male voxelized phantom. Chemical compositions and densities of ICRP 110 adult male organs were attributed to those of the studied voxelized phantom. The SAFs of monoenergetic photons with energies ranging from 0.01 to 2 MeV, were calculated for three target regions, namely kidneys, liver, and spleen, which were the radiation source regions too. The obtained SAFs were compared to recent results obtained with the GATE code. In the GATE study, chemical compositions and densities of different organs were obtained from the ICRU report number 44. The inter-comparisons between the two studies show reasonably similar results, as 80% of the calculated SAFs are consistent within 2.5% discrepancy. This demonstrates the usefulness and applicability of the InterDosi code for internal dose calculations in a voxel-based phantom. We completed this work by studying the alpha SAFs in some organs for energies emitted by 213Bi used in targeted alpha-therapy and an analytical formula was derived for rapid alpha self-irradiation calculation in soft tissues.

Contribution of radiobiphosphonates bone scan in multifocal tuberculous osteomyelitis.

We share the case of a 86-year-old male patient, followed up for recent left hip pain. Interrogation revealed a fever, nocturnal shivering, and bone pains. Standard radiographs and computed tomography centered on both shoulders and pelvis showed osteoarthritis of the left hip and multiple lytic lesions in both humeral heads and clavicles, suggestive of chronic infectious, metabolic, or secondary disease. Bone scan with radiobiphosphonates showed intense and diffuse uptake in the clavicles, the two humeral heads, and at the cervical and dorsal spine. Biopsy of the left humeral head confirmed the diagnosis of tuberculous osteomyelitis, showing an aspect of caseo-follicular tuberculosis. Bone scan with radiobiphosphonates can be used in our context to search other localizations falling within the framework of a polystotic form, and also to guide nonrisk biopsy in such group of patients.

Peritoneal Super Scan on 18F-FDG PET/CT in two patients with Lymphoma.

  Peritoneal lymphomatosis is an extremely rare presentation of lymphoma. Due to its relative low frequency, it receives much less attention than peritoneal carcinomatosis. The challenge is to differentiate between lymphomatosis and carcinomatosis, as well as peritoneal tuberculosis or other pathologic entities within the peritoneal cavity based essentially on radiologic features. 18F-FDG PET/CT is the main imaging modality for staging and monitoring response to treatment in lymphoma. Peritoneal lymphomatosis is most often associated to aggressive histological subtypes of high-grade lymphoma which are reputed high FDG uptake. We report two cases of Burkitt's lymphoma and diffuse large B cell lymphoma (DLBCL), with intense FDG uptake involving the entire peritoneum and decreased FDG activity of the rest of the body including brain and kidneys, giving it an appearance of "peritoneal super scan", follow up FDG PET/CT showed the disappearance of the peritoneal lymphomatosis and the reappearance of cerebral and urinary activity synonym of complete metabolic response.

Multiple scalp metastases from pulmonary adenocarcinoma seen on fluorodeoxyglucose positron-emission tomography/computed tomography.

Scalp metastasis from a primary visceral malignancy is an uncommon clinical entity. Here, we report a case of scalp metastases from lung cancer seen on fluorodeoxyglucose positron-emission tomography-computed tomography.