PET/CT Imaging of Infectious Diseases: Overview of Novel Radiopharmaceuticals.

Infectious diseases represent one of the most common causes of hospital admission worldwide. The diagnostic work-up requires a complex clinical approach, including laboratory data, CT and MRI, other imaging tools, and microbiologic cultures. PET/CT with 18F-FDG can support the clinical diagnosis, allowing visualization of increased glucose metabolism in activated macrophages and monocytes; this tracer presents limits in differentiating between aseptic inflammation and infection. Novel PET radiopharmaceuticals have been developed to overcome these limits; 11C/18F-labeled bacterial agents, several 68Ga-labeled molecules, and white blood cells labeled with 18F-FDG are emerging PET tracers under study, showing interesting preliminary results. The best choice among these tracers can be unclear. This overview aims to discuss the most common diagnostic applications of 18F-FDG PET/CT in infectious diseases and, as a counterpoint, to describe and debate the advantages and peculiarities of the latest PET radiopharmaceuticals in the field of infectious diseases, which will probably improve the diagnosis and prognostic stratification of patients with active infectious diseases.

Magnetic resonance-guided focused ultrasound versus percutaneous thermal ablation in local control of bone oligometastases: a systematic review and meta-analysis.

BACKGROUND: The percutaneous thermal ablation techniques (pTA) are radiofrequency ablation, cryoablation, and microwave ablation, suitable for the treatment of bone oligometastases. Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive ablation technique. OBJECTIVES: To compare the effectiveness and safety of MRgFUS and pTA for treating bone oligometastases and their complications. METHODS: Studies were selected with a PICO/PRISMA protocol: pTA or MRgFUS in patients with bone oligometastases; non-exclusive curative treatment. Exclusion criteria were: primary bone tumor; concurrent radiation therapy; palliative therapy; and absence of imaging at follow-up. PubMed, BioMed Central, and Scopus were searched. The modified Newcastle-Ottawa Scale assessed articles quality. For each treatment (pTA and MRgFUS), we conducted two separate random-effects meta-analyses to estimate the pooled effectiveness and safety. The effectiveness was assessed by combining the proportions of treated lesions achieving local tumor control (LTC); the safety by combining the complications rates of treated patients. Meta-regression analyses were performed to identify any outcome predictor. RESULTS: A total of 24 articles were included. Pooled LTC rate for MRgFUS was 84% (N = 7, 95% CI 66-97%, I2 = 74.7%) compared to 65% of pTA (N = 17, 95% CI 51-78%, I2 = 89.3%). Pooled complications rate was similar, respectively, 13% (95% CI 1-32%, I2 = 81.0%) for MRgFUS and 12% (95% CI 8-18%, I2 = 39.9%) for pTA, but major complications were recorded with pTA only. The meta-regression analyses, including technique type, study design, tumor, and follow-up, found no significant predictors. DISCUSSION: The effectiveness and safety of the two techniques were found comparable, even though MRgFUS is a noninvasive treatment that did not cause any major complication. Limited data availability on MRgFUS and the lack of direct comparisons with pTA may affect these findings. CONCLUSIONS: MRgFUS can be a valid, safe, and noninvasive treatment for bone oligometastases. Direct comparison studies are needed to confirm its promising benefits.

COVID-19 vaccine related hypermetabolic lymph nodes on PET/CT: Implications of inflammatory findings in cancer imaging.

We observed several patients presenting 2-[18F]FDG uptake in the reactive axillary lymph node at PET/CT imaging, ipsilateral to the site of the COVID-19 vaccine injection. Analog finding was documented at [18F]Choline PET/CT. The aim of our study was to describe this source of false positive cases. All patients examined by PET/CT were included in the study. Data concerning patient anamnesis, laterality, and time interval from recent COVID-19 vaccination were recorded. SUVmax was measured in all lymph nodes expressing tracer uptake after vaccination. Among 712 PET/CT scans with 2-[18F]FDG, 104 were submitted to vaccination; 89/104 patients (85%) presented axillary and/or deltoid tracer uptake, related to recent COVID-19 vaccine administration (median from injection: 11 days). The mean SUVmax of these findings was 2.1 (range 1.6-3.3). Among 89 patients with false positive axillary uptake, 36 subjects had received chemotherapy due to lymph node metastases from somatic cancer or lymphomas, prior to the scan: 6/36 patients with lymph node metastases showed no response to therapy or progression disease. The mean SUVmax value of lymph nodal localizations of somatic cancers/lymphomas after chemotherapy was 7.8. Only 1/31 prostate cancer patients examined by [18F]Choline PET/CT showed post-vaccine axillary lymph node uptake. These findings were not recorded at PET/CT scans with [18F]-6-FDOPA, [68Ga]Ga-DOTATOC, and [18F]-fluoride. Following COVID-19 mass vaccination, a significant percentage of patients examined by 2-[18F]FDG PET/CT presents axillary, reactive lymph node uptake. Anamnesis, low-dose CT, and ultrasonography facilitated correct diagnosis. Semi-quantitative assessment supported the visual analysis of PET/CT data; SUVmax values of metastatic lymph nodes were considerably higher than post-vaccine lymph nodes. [18F]Choline uptake in reactive lymph node after vaccination was confirmed. After the COVID-19 pandemic, nuclear physicians need to take these potential false positive cases into account in daily clinical practice.

Positron Emission Tomography Molecular Imaging of the Major Neurodegenerative Disorders: Overview and Pictorial Essay, from a Nuclear Medicine Center's Perspective.

Computed tomography (CT) and magnetic resonance imaging (MRI) provide key structural information on brain pathophysiology. Positron emission tomography (PET) measures metabolism in the living brain; it plays an important role in molecular neuroimaging and is rapidly expanding its field of application to the study of neurodegenerative diseases. Different PET radiopharmaceuticals allow in vivo characterization and quantization of biological processes at the molecular and cellular levels, from which many neurodegenerative diseases develop. In addition, hybrid imaging tools such as PET/CT and PET/MRI support the utility of PET, enabling the anatomical mapping of functional data. In this overview, we describe the most commonly used PET tracers in the diagnostic work-up of patients with Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases. We also briefly discuss the pathophysiological processes of tracer uptake in the brain, detailing their specific cellular pathways in clinical cases. This overview is limited to imaging agents already applied in human subjects, with particular emphasis on those tracers used in our department.

Transit time flow measurement guiding the surgical treatment for anomalous origin of the right coronary artery: A case report.

Anomalous origin of a coronary artery from the opposite sinus of Valsalva (ACAOS) in symptomatic patients is a rare but serious finding whose treatment consists of a surgical correction. The surgical treatment has a level of complexity that could vary from unroofing and ostioplasty to coronary artery bypass grafting. We present our management of a 59-year-old woman presenting with chest pain and dyspnea for right ACAOS with an interarterial route. The right coronary artery (RCA) was bypassed with the right internal thoracic artery. An intraoperative transit time flowmetry (TTFM) showed a competitive flow from the native RCA. RCA proximal ligation site was identified intraoperatively, considering the best mean graft flow (MGF) and the absence of ischemic events. The patient was discharged after a week without adverse events. The 1-year follow-up was uneventful. The intraoperative use of TTFM could guide the surgeon's hand making straightforward the surgical treatment for ACAOS.

131I Uptake in Bronchiectasis Detected by Single Photon Emission Computed Tomography/Computed Tomography during Follow-up of Thyroid Cancer.

During follow-up of thyroid cancer, 131I whole-body scan showed intense tracer uptake in the right hemithorax of a patient previously submitted to thyroidectomy and radioiodine therapy for differentiated thyroid cancer. Thyroglobulin was undetectable at the time of the scan. Single-photon emission computed tomography/computed tomography (SPECT/CT) of the thorax correctly identified widespread bronchiectasis 131I-avid in the middle lobe of the right lung. After bronchoalveolar lavage, a bronchial specimen was positive for Mycobacterium avium infection. Hybrid imaging with SPECT/CT allowed to correctly identify a false-positive case of 131I uptake due to inflammation in a single diagnostic session, minimizing patient discomfort or misdiagnoses.

68Ga/64Cu PSMA Bio-Distribution in Prostate Cancer Patients: Potential Pitfalls for Different Tracers.

BACKGROUND: 68Ga-PSMA is a widely useful PET/CT tracer for prostate cancer imaging. Being a transmembrane protein acting as a glutamate carboxypeptidase enzyme, PSMA is highly expressed in prostate cancer cells. PSMA can also be labeled with 64Cu, offering a longer half-life and different resolution imaging. Several studies documented bio-distribution and pitfalls of 68Ga-PSMA as well as of 64Cu- PSMA. No data are reported on differences between these two variants of PSMA. Our aim was to evaluate physiological distribution of these two tracers and to analyze false positive cases. METHODS: We examined tracer bio-distribution in prostate cancer patients with negative 68Ga-PSMA PET/CT (n=20) and negative 64Ga-PSMA PET/CT (n=10). A diagnostic pitfall for each tracer was documented. RESULT: Bio-distribution of both tracers was similar, with some differences due to renal excretion of 68Ga- PSMA and biliary excretion of 64Cu-PSMA. 68Ga-PSMA uptake was observed in sarcoidosis while 64Cu- PSMA uptake was recorded in pneumonitis. DISCUSSION: Both tracers may present similar bio-distribution in the human body, with similar uptake in exocrine glands and high intestinal uptake. Similarly to other tracers, false positive cases cannot be excluded in clinical practice. CONCLUSION: The knowledge of difference in bio-distribution between two tracers may help in interpretation of PET data. Diagnostic pitfalls can be documented, due to the possibility of PSMA uptake in inflammation. Our results are preliminary to future studies comparing diagnostic accuracies of 68Ga-PSMA and 64Cu-PSMA.

Situs Inversus Totalis and Cholangiocarcinoma of the Gallbladder Detected by 18F-FDG PET/CT.

A 72-year-old woman was examined by F-FDG PET/CT, showing pathologic tracer uptake in the gallbladder. PET/CT also depicted condition of situs inversus totalis, with dextrocardia, liver on the left side and spleen on the right side of the body. These findings were essential to plan and develop laparoscopic cholecystectomy, which diagnosed cholangiocarcinoma. The recognition of anatomical variants and abnormalities by means of hybrid PET/CT imaging is essential in order to plan the best therapeutic approach.

Strategies of clopidogrel load and atorvastatin reload to prevent ischemic cerebral events in patients undergoing protected carotid stenting. Results of the randomized ARMYDA-9 CAROTID (Clopidogrel and Atorvastatin Treatment During Carotid Artery Stenting) study.

OBJECTIVES: This study sought to evaluate whether a strategy with a 600-mg clopidogrel load and a short-term, high-dose atorvastatin reload would improve outcomes in clopidogrel-naïve, statin-treated patients undergoing protected carotid stenting. BACKGROUND: Optimal clopidogrel loading dose during carotid stenting has not been investigated; in addition, statin neuroprotection in this setting has not been described. METHODS: A total of 156 patients were randomized using a 2 × 2 factorial design to receive either a 600-mg (n = 78) or 300-mg (n = 78) clopidogrel load given 6 h before intervention and either a atorvastatin reload (n = 76; 80 mg + 40 mg initiating 12 h before the procedure) or no statin reload (n = 80). The primary endpoint was the 30-day incidence of transient ischemic attack/stroke or new ischemic lesions on cerebral diffusion-weighted magnetic resonance imaging performed at 24 to 48 h. RESULTS: Occurrence of the primary outcome measure was significantly lower in the 600-mg clopidogrel arm (18% vs. 35.9% in the 300-mg group; p = 0.019) and in the atorvastatin reload arm (18.4% vs. 35.0% in the no statin reload group; p = 0.031). High-dose clopidogrel also significantly reduced the transient ischemic attack/stroke rate at 30 days (0% vs. 9%, p = 0.02, secondary endpoint), without an increase in bleeding risk. CONCLUSIONS: In patients undergoing carotid stenting, a strategy using both a 600-mg clopidogrel load and a short-term reload with high-dose atorvastatin protects against early ischemic cerebral events. These results, obtained along with routine mechanical neuroprotection, provide new evidence of the optimization of drug therapy before percutaneous carotid intervention. (Clopidogrel and Atorvastatin Treatment During Carotid Artery Stenting [ARMYDA-9 CAROTID]; NCT01572623).

Virtual endoscopy in odontogenic sinus disease. Study technique and main pathological findings.

The use of CT scans in dental pathology is an established technique. The potential applications of Dentascan are further enhanced by the use of virtual navigation software, resulting in endoscopy-like imaging of the maxillary sinus, thus optimising both the diagnostic and therapeutic approach to sinus pathology of dental origin. The aim of this paper is to illustrate the technical-methodological aspects of maxillary sinus virtual endoscopy with Dentascan software and to document the most important and frequent diseases.