COVID-19 in the act: incidental 18F-FDG PET/CT findings in asymptomatic patients and those with symptoms not primarily correlated with COVID-19 during the United Kingdom coronavirus lockdown.

PURPOSE: The emergence of the novel SARS-CoV-2 pathogen and lethal COVID-19 disease pandemic poses major diagnostic challenges. The study aims to describe the spectrum and prevalence of thoracic and extrathoracic incidental findings in patients who have undergone 18F-FDG PET/CT during the first 3 weeks of the COVID-19 UK lockdown. METHODS: This is a single-centre retrospective controlled observational study. 18F-FDG PET/CT scans (n = 160) acquired from 23/3/2020 to 9/4/2020 were retrospectively reviewed for incidental findings in the lungs and extrapulmonary sites (heart, nasal sinuses, parotid and salivary glands, colon, large vessels, renal cortex, brain, spleen and testes). A date-matched control group (n = 205) of patients from 2019 was used for comparison. RESULTS: The total prevalence of suspicious findings was 26/160 (16.25%). Fifteen patients presented with incidental findings in the lungs, while eleven patients had only non-pulmonary incidental findings. There was a significant increase in the appearance of incidental 18F-FDG PET/CT findings during the 2nd week (OR = 3.8) and 3rd week (OR = 7.6) in relation to the 1st week. There was a significant increase in the average maximum standardised uptake values (SUVmax) in the parotid/salivary glands of patients scanned during week 2 in relation to week 1 (p = 0.036). There was no significant difference in the prevalence of incidental findings compared to the control group, but the number of pulmonary vs. extrathoracic findings was different between the two populations. CONCLUSION: The study provides a novel base of evidence to identify asymptomatic patients and those without symptoms strongly associated with COVID-19 with incidental 18F-FDG PET/CT findings suspicious of SARS-CoV-2 infection during the initial stages of the pandemic.

Pattern of Bone Marrow Hypometabolism on 18 F-FDG PET CT in Systemic Lupus Erythematous-Associated Aplastic Anemia.

ABSTRACT: We present the case of a 23-year-old woman with juvenile onset systemic lupus erythematous on a background of thrombotic thrombocytopenic purpura, who was referred for 18 F-FDG PET CT scan due to pyrexia of unknown origin with raised inflammatory markers, severe thrombocytopenia, and anemia. An interesting pattern of predominantly photopenic hypometabolic bone marrow activity was demonstrated on 18 F-FDG PET CT.

[ 18 F] FDG PET/CT Imaging in a Rare Case of Sarcoidosis With Involvement of Epididymis.

ABSTRACT: Genitourinary involvement of sarcoidosis is an uncommon occurrence. In this report, we present [ 18 F] FDG PET/CT of a young adult man with sarcoidosis involving the epididymis, and we discuss the utility of FDG PET imaging in diagnosis and assessment of response to treatment.

68 Ga-PSMA-Avid Intranasal Solitary Fibrous Tumor.

ABSTRACT: The utility of molecular imaging in solitary fibrous tumors has not been fully established. We present a rare case of recurrent intranasal solitary fibrous tumor incidentally localized on 68 Ga-PSMA PET/CT scan, which turned out to be metabolically inactive on 18 F-FDG PET/CT.

Biodistribution of intravenous [99mTc]Tc-phytate in mouse models of chemically and foreign-body induced sterile inflammation.

When injected intravenously, [99mTc]Tc-phytate forms particles in the nanometer range. This size can favor its extravasation into tumor and inflammation through pores of the vasculature. The aim of this work is the evaluation of the use of [99mTc]Tc-phytate to assess sterile inflammation in mouse models. Biodistribution studies of [99mTc]Tc-phytate were performed in two groups of male Swiss Albino mice. Sterile inflammation was induced after intramuscular injection of turpentine in the first group (chemically induced sterile inflammation model) and after implantation of sterile metal bolts in the second group (foreign-body induced sterile inflammation model). [99mTc]Tc-phytate was intravenously injected after the development of inflammation in both groups and ex vivo biodistribution of the radiolabelled complex followed at different time-points. Biodistribution was expressed as percent injected dose per gram (%ID/g). Target-to-background ratios were also recorded. For the chemically induced sterile inflammation model, ex vivo biodistribution evaluation measurements revealed a pronounced uptake in the inflamed muscle when compared to uptake in the control/non-inflamed muscle. Moreover, as expected, there is a high uptake in the liver and spleen. For the foreign-body induced sterile inflammation model, a significantly higher uptake was observed in the inflamed muscle post [99mTc]Tc-phytate injection, both for the 24 hours post-bolt implantation and for the 7 days post-bolt implantation groups. The nanoparticle properties of [99mTc]Tc-phytate are potentially useful in the imaging of different types of sterile inflammation with translational potential clinical SPECT (single photon emission computed tomography) imaging applications in humans.

Renal protection during 177lutetium DOTATATE molecular radiotherapy in children: a proposal for safe amino acid infusional volume during peptide receptor radionuclide therapy.

Peptide receptor radionuclide therapy (PRRT) using radiolabelled somatostatin analogues such as 177-lutetium DOTATATE is an effective treatment modality for neuroendocrine tumours, paragangliomas, and neuroblastomas. However, renal and haematopoietic toxicities are the major limitations of this therapeutic approach. The renal toxicity of PRRT is mediated by renal proximal tubular reabsorption and interstitial retention of the radiolabelled peptides resulting in excessive renal irradiation that can be dose-limiting. To protect the kidneys from PRRT-induced radiation nephropathy, basic amino acids are infused during PRRT as they competitively bind to the proximal tubular cells and prevent uptake of the radionuclide. In adults, 1 L of a basic amino acid solution consisting of arginine and lysine is infused over 4 h commencing 30 min prior to PRRT. However, this volume of amino acids infused over 4 h is excessive in small children and can result in hemodynamic overload. This is all the more relevant in paediatric oncology, as many of the children may have been heavily pretreated and so may have treatment-related renal and or cardiac impairment. We have therefore developed the following guidelines for safe paediatric dosing of renal protective amino acid infusions during PRRT. Our recommendations have been made taking into consideration the renal physiology in small children and the principles of safe fluid management in children.

A Phase II, Open-label study to assess safety and management change using 68Ga-THP PSMA PET/CT in patients with high risk primary prostate cancer or biochemical recurrence after radical treatment: The PRONOUNCED study.

Objectives: To assess the safety and clinical impact of a novel, kit-based formulation of 68Ga-THP PSMA positron emission tomography/computed tomography (PET/CT) when used to guide the management of patients with prostate cancer (PCa). Methods: Patients were prospectively recruited in to one of: Group A: high-risk untreated prostate cancer; Gleason score >4+3, or PSA >20 ng/mL or clinical stage >T2c. Group B: biochemical recurrence (BCR) and eligible for salvage treatment after radical prostatectomy with two consecutive rises in prostate specific antigen (PSA) with a three month interval in between reads and final PSA >0.1 ng/mL or a PSA level >0.5 ng/mL. Group C: BCR with radical curative radiotherapy or brachytherapy at least three months prior to enrolment, and an increase in PSA level >2.0 ng/mL above the nadir level after radiotherapy or brachytherapy. Patients underwent evaluation with PET/CT 60 minutes following intravenous administration of 160±30 MBq of 68Ga-THP PSMA. Safety was assessed by means including vital signs, cardiovascular profile, serum haematology, biochemistry, urinalysis, PSA, and Adverse Events (AEs). A change in management was reported when the predefined clinical management of the patient altered as a result of 68Ga-THP PSMA PET/CT findings. Results: Forty-nine patients were evaluated with PET/CT; 20 in Group A, 21 in Group B and 8 in Group C. No patients experienced serious AEs discontinued the study due to AEs, or died during the study. Two patients had Treatment Emergent AEs attributed to 68Ga-THP-PSMA (pruritus in one patient and intravenous catheter site rash in another). Management change secondary to PET/CT occurred in 42.9% of all patients; 30% in Group A, 42.9% in Group B and 75% in Group C. Conclusion: 68Ga-THP PSMA was safe to use with no serious AE and no AE resulting in withdrawal from the study. 68Ga-THP PSMA PET/CT changed the management of patients in 42.9% of the study population, comparable to studies using other PSMA tracers. These data form the basis of a planned Phase III study of 68Ga-THP PSMA in patients with prostate cancer.

Imaging of Prostate Cancer Recurrence in the Vas Deferens With 68Ga-PSMA PET/CT.

Two cases with Ga-PSMA-avid prostate cancer recurrence in the vas deferens are presented. These cases highlight the clinical importance of imaging the pattern of local prostate cancer recurrence and the potential difficulties that arise due to the altered anatomy in the prostate bed after prostatectomy or radiotherapy.

Before and After Treatment Characterization of Cerebrospinal Disease in Bing-Neel Syndrome Using 18F FDG PET/MRI.

Bing-Neel syndrome is a rare neurological complication of Waldenström macroglobulinemia. We present the case of a 71-year-old man who underwent prechemotherapy and postchemotherapy FDG PET/MRI scan for the evaluation of cerebrospinal disease. In light of limited literature and lack of consensus guidelines on the role of metabolic imaging, we aim to highlight the utility of FDG PET/MRI in the diagnosis and response assessment in Bing-Neel syndrome.

The impact of Ga-68 DOTATATE PET/CT imaging on management of patients with paragangliomas.

OBJECTIVE: Paragangliomas are rare tumours of neural crest origin that express high levels of somatostatin receptor. Ga-68 DOTATATE PET/CT is a widely accepted method for imaging of neuroendocrine tumours. This study was performed to review a Ga-68 DOTATATE PET/CT patient database and to establish the impact of the modality on patient treatment. METHODS: Demographic data, imaging data and change in management after Ga-68 DOTATATE PET/CT were evaluated. RESULTS: Ga-68 DOTATATE PET/CT scans were performed in 21 patients in whom paragangliomas had been confirmed after biopsy or surgery and in one patient with suspected paraganglioma. In most patients, the primary site was the organ of Zuckerkandl (12/22). Of the 22 Ga-68 DOTATATE PET/CT scans completed, 19 (86.4%) were positive and three (13.6%) negative. In 12 of 14 recurrent cases (90.9%), the treatment plan was changed after the Ga-68 DOTATATE PET/CT scan owing to new, unexpected findings, while it remained unchanged in two (9.1%). Regarding the change in treatment plan, in most instances the new treatment comprised peptide receptor radionuclide therapy (PRRT). CONCLUSION: Ga-68 DOTATATE PET/CT findings led to a change in the scheduled treatment plan in 90.9% of patients with suspected recurrence. The most frequent change consisted in initiation of PRRT due to disease recurrence or progression or detection of multiple metastases.

A case of crossed cerebellar diaschisis on follow-up positron emission tomography/computed tomography with (18F) fluoro-D-glucose after treatment for glioblastoma.

Crossed cerebellar diaschisis (CCD) represents the reduction of blood flow, metabolism, and oxygen consumption in the cerebellar hemisphere contralateral to a cerebral focal lesion. This phenomenon is the result of remote metabolic effects of cerebral lesions and it has been described since the first attempts for functional imaging of the brain, almost 40 years ago. Nevertheless, its clinical significance remains uncertain and new ways to use imaging of CCD for prognosis or assessment of novel therapies are being investigated. In this report, we present treatment for glioblastoma as a cause of CCD imaged on positron emission tomography/computed tomography with (18F) fluoro-D-glucose in our department.

Computational study of necrotic areas in rat liver tissue treated with photodynamic therapy.

BACKGROUND: Photodynamic therapy (PDT) is an alternative treatment method for liver metastatic cancer worth exploring. METHODS: This study implements a computational model of metastatic rat liver tissue subjected to superficial irradiation, after administration of 5,10,15,20-Tetrakis(3-hydroxyphenyl)chlorine (mTHPC). Spatial and temporal distributions of fundamental PDT dosimetric parameters are presented, along with calculation of necrotic distance and necrotic area percentage. Moreover, an algorithm able to calculate the minimum irradiation time needed in order to achieve various values of necrotic depth is coded. RESULTS: The intratissue distributions show that light penetration depth is approximately 1.5 mm for all fluence rate (φ) values in direction of z axis. Moreover, necrosis at r axis (horizontal axis) extends outside beam's geometrical edges at distance equal up to 55.3% of its radius. It is also noticed that both φ and concentration of ground-state photosensitizer ([S0]) can increase the necrotic distance, in a steeper manner at lower [S0] values. The irradiation time needed in order to achieve various values of necrotic depth is independent of φ for the upper tumor layers but is greater in orders of magnitude for deeper lying layers and low φ values. CONCLUSIONS: Increasing light fluence rate appears to be a more productive method than increasing photosensitizer concentration for inducing necrosis, especially in larger tumors. Finally, our results show that high φ values are necessary in order to maintain clinically applicable irradiation times.

Nuclear medicine techniques in Merkel cell carcinoma: A case report and review of the literature.

Merkel cell carcinoma (MCC) is a rare and aggressive type of neuroendocrine cancer of the skin. It predominantly affects the elderly, with a predilection for the sun-exposed skin of the head and neck. Risk factors include immune-suppressing diseases, such as human immunodeficiency virus (HIV), chronic lymphocytic leukemia and multiple myeloma, organ transplantation, and the presence of the newly-identified Merkel cell polyomavirus (MCPyV). Diagnosis is based on pathological findings, primarily the immunohistochemical determination of cytokeratin 20 positivity. By contrast, staging relies on conventional imaging methods, such as ultrasonography, computed tomography (CT) and magnetic resonance imaging, and nuclear medicine techniques, such as sentinel lymph node scintigraphy, somatostatin receptor scintigraphy (SRS), and positron emission tomography (PET)/CT with 18F-fluorodeoxyglucose (FDG) or alternative radiopharmaceuticals. The treatment of MCC is primarily surgical, with possible adjuvant radiation, while the use of chemotherapy appears to be an alternative therapeutic option that is used only in specific cases. The present study describes the case of a 43-year-old HIV-positive Caucasian man with MCC located on the posterior surface of the left thigh, which was identified by cytological and histological examination of tissue sampled by fine needle aspiration and biopsy performed under CT. SRS demonstrated a high uptake of 111In-diethylene triamine pentaacetic acid-octreotide at the affected site. Therefore, the lesion was surgically excised, and the patient received chemotherapy and adjuvant radiotherapy. Three months subsequent to treatment, the patient underwent a PET/CT scan with 18F-FDG that demonstrated uptake in the cervical lymph nodes and the area of the excised lesion. These findings indicated that the disease was in remission. The aim of the present study was to highlight the value and contribution of nuclear medicine in the diagnosis, staging and follow-up, using PET/CT, octreoscan and sentinel lymph node scintigraphy, of patients with MCC, as well as the therapeutic strategy of radiolabelled somatostatin analogue scintigraphy.

Neuroendocrine differentiation in castration-resistant prostate cancer: A case report.

The most common type of prostate cancer is acinar adenocarcinoma, which is androgen-dependent and, therefore, treated with chemical or surgical castration and androgen receptor inhibition. However, the disease usually progresses to castration-resistant prostate cancer (CRPC). A neuroendocrine pattern is frequently observed in the cellular composition of CRPC, which is considered to emerge as an effect of androgen deprivation therapy. This is the case report of a 69-year-old patient with prostate adenocarcinoma, who, after an initial period of disease control with radiotherapy and antiandrogens, was diagnosed with CRPC with high levels of prostate-specific antigen (PSA), unresponsive to androgen inhibition, with accompanying lung and osseous metastases. Bronchial biopsy of the lung metastasis revealed infiltration by non-small-cell adenocarcinoma of prostatic origin with neuroendocrine characteristics. On somatostatin receptor scintigraphy with 99mTc-octreotide, there was high uptake by almost all known lung and osseous metastases. The patient was subsequently treated with a combination of docetaxel and octreotide, and a partial response was observed 6 months later, with reduction of the PSA level and the size of the lung metastasis. The aim of the present study was to provide a clinical example of the previously demonstrated, in vitro and in vivo, synergistic antitumor activities of docetaxel and octreotide in cases of CRPC selected by means of histological confirmation of their neuroendocrine nature and somatostatin receptor scintigraphy.