Reorganization of a Nuclear Medicine Department in Northern Italy During a 2-Month Lockdown for COVID-19 Pandemic.

Coronavirus disease (COVID-19) outbreak has profoundly changed the organization of hospital activities. We present our experience of reorganization of a nuclear medicine service settled in Northern Italy during the pandemic period of March and April 2020 characterized a government-mandated lockdown. Our service remained open during the whole period, performing approximately 80% of the routine practice, while maintaining it COVID-free despite the geographical context characterized by a high risk of infection. Reorganization involved all aspects of a nuclear medicine department, following local, national, and international guidelines for prioritizing patients, telephone and physical triages, deployment of appropriate personal protective equipment, social distancing, and logistic changes for scheduling examinations and disinfection procedures. All staff remained COVID-19-negative despite the unintentional admission of 4 patients who later turned out to be positive for the severe acute respiratory syndrome coronavirus 2. These adopted measures would serve as the basis for safe nuclear medicine services in the post-lockdown phase.

A new mobile self-dispensing and administering system for 18F-FDG: evaluation of operator dose reduction.

PURPOSE: Recently new mobile systems for dispensing positron emitters have been produced, designed to guarantee dispensing cycles in an aseptic environment. The aim of the present work was to assess the advantage of one of these systems in radiation protection of operators in clinical settings. METHODS: Recently, in our centre the new self-dispensing system named KARL100 by Tema Sinergie was adopted for 18F-FDG radiopharmaceuticals. The system is associated with an automatic Rad-inject infuser. The system that was previously used was a fixed isolator NMC DSI (Tema Sinergie), equipped with a µDDS-An activity fractioning system, together with a pneumatic post for the syringe delivery. The dosimetric evaluations on both systems were carried out through environmental measurements with an ionisation chamber and with the use of personal dosimeters. RESULTS: The operations of preparation and administration of 18F-FDG dose to the patient, with the use of Karl100 + RadInject, involve exposures much lower than those obtained by the fixed isolator. The average body exposure of the technician was reduced by 31%, and for the physician by 77%. On the extremities, the equivalent dose to the hands of the technician was reduced by 78%, and for the physician by 96%. Also the additional dosimeters worn by the technician confirmed the estimated environmental assessments. CONCLUSIONS: The exposures of the working personnel were significantly reduced with the introduction of the new KARL100 system.

How to harmonize SUVs obtained by hybrid PET/CT scanners with and without point spread function correction.

State of the art point-spread function (PSF) corrections implemented in positron emission tomography/computed tomography (PET/CT) reconstruction improved image quality and diagnostic performance but caused an increase in the standardized uptake value (SUV) compared to a conventional OSEM reconstruction system. The EANM suggested one produce two reconstructions, one optimised for maximum lesion detection and one for semi-quantitative analysis. In this work we investigated an alternative methodology, using a single reconstruction data set together with a post-reconstruction algorithm for SUV harmonization. Data acquisition was performed on a Siemens Biograph mCT system equipped with lutetium oxyorthosilicat crystals, PSF and time-of-flight algorithms and on a General Electric Discovery STE system equipped with BGO crystals. Both a EANM double reconstruction method and a dedicated post-reconstruction algorithm (marketed as EQ-filter) were tested to harmonize the quantitative values of the two PET/CT scanners. For phantom measurements we used a NEMA IQ phantom and a Jaszczak cylindrical phantom equipped with small spheres (lesion to background ratios of 8:1 and 4:1). Several different reconstruction settings were tested in order to provide a general methodology. Data obtained by phantom measurements were validated on seven oncologic patients who performed a one-bed extra acquisition on a different scanner. The evaluation regarded 39 small lesions (diameters: 0.3-2.6 cm) and was performed by two experienced nuclear medicine physicians. The SUV recoveries measured with the PSF reconstruction exceeded those obtained by the OSEM reconstruction with deviations ranging from 16% to 150%. These discrepancies resulted below 7% applying the optimized value of the EQ.filter or the double-reconstruction methods. For each reconstruction setting the optimal value of the EQ.filter was identified in order to minimize these discrepancies. Patient data, analyzed by Wilcoxon statistical test, confirmed and validated phantom measurements. EQ.filter can harmonize SUV values between different PET/CT scanners using a single reconstruction optimized to maximum lesion detectability. In this way, the second reconstruction proposed by EANM/EARL is avoided.

False-Positive 18F-FDG PET/CT Due to Filgrastim That Induced Extramedullary Liver Hematopoiesis in a Burkitt Lymphoma.

We report a case of Burkitt lymphoma with largely extranodal disease localizations at staging. Chemotherapy was given, thus obtaining a complete metabolic response in all previous disease sites as shown at a control PET, however associated to the appearance of new focal uptake areas in the liver; these findings were confirmed at US and MRI. Chemotherapy determined also neutropenia that was treated by filgrastim, followed by a prompt and important medullary response. Liver biopsy revealed extramedullary hematopoiesis, probably filgrastim induced. Filgrastim administration may cause false-positive findings in the liver at FDG PET.

18F-FDG PET/CT of Generalized Arteritis.

A 75-year-old man presented with significant weight loss, persistent cough, single episode of frontotemporal pulsatile headache, and leg weakness. A paraneoplastic syndrome was suspected, and F-FDG PET/CT was performed. Diffuse, moderate-to-intense tracer symmetrical uptake of many large and medium arteries was unexpectedly noted. The peculiarity of this case is the extensive involvement of both large and medium head and neck and extremity vessels, whereas the aorta was relatively spared.

18F-FDG PET/CT of Brown Adipose Tissue Hyperactivation Associated With Pregnancy and Paraganglioma.

This 32-year-old woman presented with pregnancy-related arterial hypertension unresponsive to antihypertensive therapy. During cesarean delivery, a lobulated retroperitoneal mass was discovered. F-FDG PET/CT performed 18 days postpartum demonstrated the hyperactive retroperitoneal mass and extensive hyperactivated brown adipose tissue. The mass was surgically removed, revealing a para-aortic multicentric paraganglioma. After surgery, blood pressure normalized, and serum chromogranin A and urinary metanephrines normalized. Brown adipose tissue hypermetabolism disappeared on follow-up FDG PET. Her initial FDG PET demonstrated brown adipose tissue hyperactivation, which may have been caused by the combination of hormonal changes in pregnancy and the paraganglioma.

Epstein-Barr Virus-Positive Mucocutaneous Ulcer Mimicking Rectal Carcinoma at 18F-FDG PET/CT.

We report focally intense F-FDG PET/CT rectal activity (SUVmax = 25) with a horseshoe distribution in an 81-year-old man with B-cell chronic lymphocytic leukemia and suspected Richter transformation. While imaging findings were typical for rectal adenocarcinoma, histology revealed Epstein-Barr virus-positive mucocutaneous ulcer.

FDG PET/CT in Aortic Valve Bioprosthesis Infection.

A 62-year-old man presented with persistent fever, weakness, and retrosternal pain 3 years after aortic valve bioprosthesis (AVR). His white blood cell count was 11,000/µL and C-reactive protein was 13.6 mg/dL. Consecutive blood cultures isolated Staphylococcus epidermidis and capitis. Transesophageal echocardiography demonstrated small aortic valve prosthesis vegetation. F-FDG PET/CT revealed prominent AVR activity, SUVmax = 12.2. He was treated with daptomycin, meropenem, and gentamicin for 1 month and followed by daptomycin and carbapenem for 3 months. Follow-up F-FDG PET/CT at 6 months demonstrated complete clearing of AVR activity associated with full asymptomatic recovery.

Bone edema of the whole vertebral body: an unusual case of spondyloarthritis.

Spondyloarthritis (SpA) is usually characterized by early inflammatory involvement of the sacroiliac joints (SI), which constitutes one of the most important classification criteria according to the SpondyloArthritis International Society (ASAS). These criteria do not include inflammatory spine lesions which can be detected on MRI, although spine involvement is very common in axial SpA. This is because spine MRI lesion often retrieved in SpA are not very specific, and can be found in many other diseases such as malignancy and osteoarthritis. Here we present the case of a 33-year old woman who presented a worsening low back pain, with a thoracic spine MRI showing bone marrow edema (BME) of the whole T8 vertebral body. Owing to this peculiar presentation, together with the unresponsiveness of the pain to nonsteroidal anti inflammatory drugs (NSAIDs) and a slight increase of the biomarker CA19-9, a malignancy was suspected. Therefore, the patient underwent bone scintigraphy, Single positron emission computed tomography (SPET/TC), positron emission tomography and repeated MRI without reaching a diagnosis. Finally, when SI joints MRI was performed, BME of the SI joints emerged: this was fundamental to formulate the diagnosis of axSpA.

Left Main Coronary Artery Atresia in Young Man Examined With 99mTc-Tetrofosmin SPECT: A Rare and Challenging Anomaly.

A young man underwent Tc-tetrofosmin cardiac SPECT/CT for the evaluation of the 8-month history of exertional dyspnea without chest pain. Tc-tetrofosmin SPECT demonstrated absence of perfusion defects and a mildly decreased uptake in post-stress images, consistent with artifact, in the inferior myocardium. Cardiac catheterization showed a large right and a small left coronary artery opacified retrogradely by right collateral vessels without connections between the left main and the left coronary artery. In patients with anomalous coronary arteries, Tc SPECT can shows absence of perfusion defects, in the presence of a collateral circulation.

Role of myocardial perfusion scintigraphy in predicting global cardiovascular risk and differentiating between patients with moderate and high cardiovascular risk.

OBJECTIVE: The usefulness of stress myocardial perfusion scintigraphy (MPS) for cardiovascular (CV) risk stratification in patients at moderate and high CV risk remains controversial. We tested the hypothesis that different clinical risk profiles influence the test and the likelihood of obtaining a positive coronary angiography (CA) in the following 12 months. METHODS: We assessed the prognostic value of MPS in 230 patients classified according to the European Society of Cardiology guidelines. RESULTS: Patients at high and very-high CV risk had a higher prevalence of positive MPS (25.5 vs. 36.7%, P=0.014 and 9.8 vs. 19.5%, P=0.011, respectively), whereas patients at moderate risk had a higher prevalence of negative MPS (45.1 vs. 38.3, P=NS). Multivariate regression analysis showed that positive MPS was an independent predictor of 12-month positive CA only in patients at high CV risk [odds ratio (OR) 8.03, 95% confidence interval (CI) 1.53-42.03, P=0.014] independent of age>60 and coexistence of obesity and previous percutaneous coronary intervention (OR 3.78, 95% CI 1.18-12.78, P=0.032; OR 1.83, 95% CI 1.03-3.26, P=0.039). The C-statistic showed a good discriminatory power of positive MPS in predicting 12-month positive CA (0.68, 95% CI 0.55-0.80, P=0.015). Mantel-Cox analysis showed that after 12 months of follow-up, in patients at high risk, there was a statistically significant difference in the distribution of patients with positive than those without negative CA (log rank P=0.04). CONCLUSION: CV risk stratification on the basis of MPS is useful only in patients at high and very-high CV risk. In these groups, MPS can aid stratification for the risk of CV events.

Differentiation of cardiac thrombus from cardiac tumor combining cardiac MRI and 18F-FDG-PET/CT Imaging.

Radiological differentiation of an unknown cardiac masse is often a challenging issue. 18F-FDG-PET/CT imaging was performed to evaluate a left ventricle mass visualized on transthoracic echocardiogram (TTE) and cardiac magnetic resonance (CMR) in a patient with an history of ischemic heart disease. The metabolically inert area on the PET/CT, corresponding to the relatively homogenous hypodensity in the LV, was thought to represent an old organized LV thrombus. Histopathological examination confirmed the imaging diagnosis.

Optimized protocol for (18)F-choline PET/CT in patients with biochemically relapsed prostate cancer: experiences on 250 consecutive cases.

PURPOSE: We review acquisition F-choline PET/CT methodology, evaluate a new F-choline acquisition protocol for prostate cancer (PC), and propose a standardized acquisition protocol on F-choline in PC patients. MATERIALS: Two hundred fifty consecutive PC patients (mean age 72 years, mean PSA 7.9 ng/mL) were prospectively evaluated with F-choline PET/CT. An early scan of the pelvis (1 bed position of 4 minutes) was followed by a whole-body scan at 1 hour. Early and 1 delayed hour images of the pelvis were compared. RESULTS: Twenty-one percent of patients (n = 57) with positive F-choline demonstrated abnormal local uptake; 18% of patients (n = 45) showed distant localization only; 23% of patients (n = 53) had both local and distant localization; 38% of patients (n = 38) did not show any pathological uptake. All early images showed absence of radioactive urine in ureters, bladder, or urethra with satisfactory visualization of the prostatic region. Considering the group of patients with local uptake only, the prostatic region uptake, confirmed by late images, was better visualized in the early phase in 32/57 cases (SUVmax 12.4 ± 3.2 vs. 7.3 ± 5.2, P <0.01). Instead distant lesions were visualized on both early and late images with similar uptakes values (SUVmax 9.8 ± 4.1 vs. 10.3 ± 4.5, P = N.S.). CONCLUSION: Early F-choline images improve pelvic prostate cancer lesion clarity. All pathologic pelvic deposits (prostate, lymph nodes, bone) were visualized both in the early and late images.

18F-FDG PET/CT lung 'focalities' without coregistered CT findings: an interpretative clinical dilemma.

AIM: The aim of the study was to assess the prevalence of focal fluorine-18 fluorodeoxyglucose (18F-FDG) activity in the lungs using 18F-FDG PET/computed tomography (CT) without matching CT findings. MATERIALS AND METHODS: A total of 10,500 consecutive 18F-FDG PET/CT records over 4 years were reviewed for focal incongruence between PET and CT, potentially indicating an artifact 18F-FDG (2.2 MBq/kg) was injected through a butterfly needle, followed by a 10 ml saline flush. Non-contrast-enhanced low-dose CT (140 kV and 40-80 mA) was coregistrated with PET. RESULTS: Sixteen patients (12 men and four women; mean age 63 years, range 44-83) had focal pulmonary areas of high 18F-FDG activity [mean maximum standardized uptake value (SUV max) 15.8; range 3.5-81.0], typically peripheral, with a mean maximum diameter of 1.3 cm (range 0.5-2.2 cm) on PET. 18F-FDG focality was singular in 14 patients, whereas two patients had two foci each. None had corresponding CT abnormalities. Identification of these 'focalities' during the acquisition phase led to late respiratory gated thoracic PET acquisitions in eight patients at 2 h with no significant changes in the location or size of the 'focalities'. Five PET/CTs repeated at 48 h did not confirm the 'focalities'. Five had negative follow-up contrast-enhanced CT. 18F-FDG-positive 'focalities' at PET/CT without anatomical correlation findings were considered as 'artefactual accumulation' of the tracer. CONCLUSION: In the absence of morphological abnormality, focal pulmonary 18F-FDG activity is very rare (1.5 cases/1000 PET scans) but potentially very 'dangerous'. Artefact identification during acquisition can lead to late respiratory gated images for more confident interpretation, avoiding erroneous reports or further imaging procedures.

Response criteria for malignant lymphoma.

In the last 35 years, many attempts have been made to define criteria for the assessment of treatment response in malignant lymphoma. These systems, with respect to both morphological and molecular imaging, aim to standardize scan results, in order to simplify the interpretation of findings, facilitate multicentric research trials, and compare published data. Unfortunately, there is no consensus among the main international hematological associations on which criteria are the most appropriate. This detailed and comprehensive description of all classifications intends to focus attention on this topic.

Role of 18F-FDG PET/CT in the carcinoma of the uterus: a review of literature.

In the present review we reported the value of 18F-fluorodeoxyglucose (FDG) PET/CT in face of uterine cancer, in terms of sensitivity, specificity and accuracy. Moreover, we made a comparison with the other imaging techniques currently used to evacuate these tumors including contrast-enhanced CT, contrast enhanced-MRI and transvaginal ultrasonography. FDG PET/CT has been reported to be of particular value in detecting occult metastatic lesions, in prediction of response to treatment and as a prognostic factor.

New acquisition protocol of 18F-choline PET/CT in prostate cancer patients: review of the literature about methodology and proposal of standardization.

PURPOSE: (1) To evaluate a new acquisition protocol of (18)F-choline (FCH) PET/CT for prostate cancer patients (PC), (2) to review acquisition (18)F-choline PET/CT methodology, and (3) to propose a standardized acquisition protocol on FCH PET/CT in PC patients. MATERIALS: 100 consecutive PC patients (mean age 70.5 years, mean PSA 21.35 ng/mL) were prospectively evaluated. New protocol consisted of an early scan of the pelvis immediately after the injection of the tracer (1 bed position of 4 min) followed by a whole body scan at one 1 hour. Early and 1 hour images were compared for interfering activity and pathologic findings. RESULTS: The overall detection rate of FCH PET/CT was 64%. The early static images of the pelvis showed absence of radioactive urine in ureters, bladder, or urethra which allowed a clean evaluation of the prostatic fossae. Uptake in the prostatic region was better visualized in the early phase in 26% (7/30) of cases. Other pelvic pathologic findings (bone and lymph nodes) were visualized in both early and late images. CONCLUSION: Early (18)F-choline images improve visualization of abnormal uptake in prostate fossae. All pathologic pelvic deposits (prostate, lymph nodes, and bone) were visualized in both early and late images.

18F-FDG PET/CT in tumefactive multiple sclerosis.

A 35-year-old man underwent contrast-enhanced MRI and F-FDG PET/CT for acute peripheral paresthesia, vision loss, muscle weakness, and difficulty walking. T2-weighted MRI demonstrated multiple bright periventricular supratentorial and infratentorial white matter lesions, including 2 with nodularity. Both nodular lesions showed moderate focal FDG uptake (SUVmax, 6.9 in both cases). Cerebrospinal fluid analysis showed increased levels of immunocytes and oligoclonal antibody bands. A diagnosis of acute onset tumefactive multiple sclerosis was made.

Is the detection rate of 18F-choline PET/CT influenced by androgen-deprivation therapy?

PURPOSE: To evaluate if the detection rate (DR) of (18)F-choline (18F-CH) PET/CT is influenced by androgen-deprivation therapy (ADT) in patients with prostate cancer (PC) already treated with radical intent and presenting biochemical relapse. MATERIALS AND METHODS: We have retrospectively evaluated (18)F-CH PET/CT scans of 325 consecutive PC patients enrolled in the period November 2009 to December 2012 previously treated with radical intent and referred to our centre to perform (18)F-CH PET/CT for biochemical relapse. Two different groups of patients were evaluated. group A included the whole sample of 325 patients (mean age 70 years, range: 49-86) who presented trigger PSA between 0.1 and 80 ng/ml (mean 5.5 ng/ml), and group B included 187 patients (mean age 70 years, range 49-86) with medium-low levels of trigger PSA ranging between 0.5 and 5 ng/ml (mean PSA 2.1 ng/ml); group B was chosen in order to obtain a more homogeneous group of patients in terms of PSA values also excluding both very low and very high PSA levels avoiding the "a priori" higher probability of negative or positive PET scan, respectively. At the time of examination, 139 patients from group A and 72 patients from group B were under ADT: these patients were considered to be hormone-resistant PC patients because from their oncologic history (>18 months) an increase of PSA levels emerged despite the ongoing ADT. The relationship between (18)F-CH PET/CT findings and possible clinical predictors was investigated using both univariate and multivariate binary logistic regression analyses, including trigger PSA and ADT. RESULTS: Considering the whole population, overall DR of (18)F-CH PET was 58.2 % (189/325 patients). In the whole sample of patients (group A), both at the univariate and multivariate logistic regression analysis, trigger PSA and ADT were significantly correlated with the DR of (18)F-CH PET (p < 0.05). Moreover, the DR in patients under ADT (mean PSA 7.8 ng/ml) was higher than in patients not under ADT (mean PSA 3.9 ng/ml), (DR was 70.5 % and 48.9 %, respectively; p < 0.001), therefore, demonstrating the existence of a significant correlation between the DR of (18)F-CH PET and ADT. In group B patients only trigger PSA resulted a reliable predictor of the (18)F-CH positivity, since ADT was not correlated to the DR of (18)F-CH PET (p = 0.061). Also in group B the DR of (18)F-CH PET in patients under ADT was higher than in patients not under ADT (65.3 % and 51.3 %, respectively) but the difference was not significant without a statistically significant correlation in the Mann Whitney test (p = 0.456) therefore, suggesting the lack of correlation between DR (18)F-CH PET/CT and ADT. CONCLUSION: Similarly to previous published studies, in our series the overall DR of (18)F-CH PET/CT was 58 % and was significantly correlated to trigger PSA. The most important finding of the present study is that ADT does not negatively influence DR of (18)F-CH PET/CT in PC patients with biochemical relapse; therefore, it can be suggested that it is not necessary to withdraw ADT before performing (18)F-CH PET/CT.

Management of epithelial ovarian cancer from diagnosis to restaging: an overview of the role of imaging techniques with particular regard to the contribution of 18F-FDG PET/CT.

Epithelial ovarian carcinoma is a major form of cancer affecting women in the western world. The silent nature of this disease results in late presentation at an advanced stage in many patients. It is therefore important to assess the role of imaging techniques in the management of these patients. This article presents a review of the literature on the role of (18)F-FDG-PET/CT in the different stages of management of epithelial ovarian cancer. Moreover, a comparison with other imaging techniques has been made and the relationship between (18)F-PET/CT and the assay of serum CA-125 levels has been discussed.