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Over the last several years, molecular imaging has gained a primary role in the evaluation of patients with brain metastases (BM). Therefore, the “Response Assessment in Neuro-Oncology” (RANO) group recommends amino acid radiotracers for the assessment of BM. Our review summarizes the current use of positron emission tomography (PET) radiotracers in patients with BM, ranging from present to future perspectives with new PET radiotracers, including the role of radiomics and potential theranostics approaches. A comprehensive search of PubMed results was conducted. All studies published in English up to and including December 2022 were reviewed. Current evidence confirms the important role of amino acid PET radiotracers for the delineation of BM extension, for the assessment of response to therapy, and particularly for the differentiation between tumor progression and radionecrosis. The newer radiotracers explore non-invasively different biological tumor processes, although more consistent findings in larger clinical trials are necessary to confirm preliminary results. Our review illustrates the role of molecular imaging in patients with BM. Along with magnetic resonance imaging (MRI), the gold standard for diagnosis of BM, PET is a useful complementary technique for processes that otherwise cannot be obtained from anatomical MRI alone.

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.

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.

At the moment, international guidelines for rectal cancer suggest to consider F-FDG PET/CT scan in a few conditions: (1) at disease presentation in case of suspected or proven metastatic synchronous adenocarcinoma with potentially curable M1 disease; (2) in the recurrence workup for serial carcinoembryonic antigen level elevation; (3) in the recurrence workup with metachronous metastases documented by CT, MRI, or biopsy; (4) in case of strong contraindication to IV contrast agent administration; and (5) to evaluate an equivocal finding on a contrast-enhanced CT or MRI. PET/CT is not indicated in the follow-up or surveillance of rectal cancer. On the other hand, an attentive evaluation of the literature shows that PET/CT may also be used in some circumstances with significant levels of diagnostic accuracy. This review article aims to emphasize differences between current international guidelines and scientific literature in the role of PET/CT in rectal cancer.

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.Recently, in our centre the new self-dispensing system named KARLThe operations of preparation and administration ofThe exposures of the working personnel were significantly reduced with the introduction of the new KARL

OBJECTIVE: Lung nodules can be benign or malignant, reflecting many possible causes, ranging from inflammatory and infectious processes to neoplasms. Incidental detection on chest x-ray or thoracic CT often requires further evaluation by imaging or invasive procedures. CONCLUSION: Currently, 18F-FDG PET/CT offers both anatomic and metabolic characterization of lung nodules. Fluorine-18-thymidine, 11C-methionine, 68Ga-DOTA-somatostatin analogs, and 18F-dihydroxyphenylalanine may offer additional molecular information useful for diagnosis and treatment planning.

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.

Despite recent advances in the development of new therapeutic agents and diagnostic imaging modalities, cancer is still one of the main causes of death worldwide. A better understanding of the molecular signature of cancer has promoted the development of a new generation of anti-cancer drugs and diagnostic agents that specifically target molecular components such as genes, ligands, receptors and signaling pathways. However, intrinsic heterogeneity of tumors has hampered the overall success of target therapies even among patients with similar tumor types but unpredictable different responses to therapy. In this sense, post-treatment response monitoring becomes indispensable and nuclear medicine imaging modalities could provide the tools for an early indication of therapeutic efficacy. Herein, we briefly discuss the current role of PET and SPECT imaging in monitoring cancer therapy together with an update on the current radiolabeled probes that are currently investigated for tumor therapy response assessment.

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.

The first aim of the review (aim 1) was to obtain the diagnostic performance values of 18F-FDG PET for the detection and staging of liver metastases in patients with colorectal cancer (CRC), the second aim (aim 2) was to compare PET and conventional imaging modalities, and the third aim (aim 3) was to evaluate the impact of PET on patient management. The incidence of extrahepatic disease (EHD) detected by PET is also reviewed. A comprehensive search was performed on PubMed/MEDLINE for studies evaluating PET and PET/CT in CRC patients with liver metastases up to June 2014. For inclusion PET had to have been performed prior to surgery, there had to be at least 18 patients in the study, and the reported data had to allow calculation of 2 × 2 contingency tables (for aim 1). A total of 18 studies were eligible for at least one of the three intended subanalyses including a total of 1,059 patients. Pooled sensitivity, specificity and accuracy and the corresponding 95 % confidence intervals were derived from the contingency tables on a patient basis (patient-based analysis, PBA) and a lesion basis (lesion-based analysis, LBA) for eight studies. Pooled sensitivity and specificity of PET on PBA were both 93 %. Corresponding values for LBA were 60 % and 79 %, respectively. Areas under the summary ROC were 0.97 for PBA and 0.67 for LBA. Regarding aim 2, PET had a slightly lower sensitivity than MRI and CT on PBA (93 %, 100 % and 98 %, respectively) and LBA (66 %, 89 % and 79 %, respectively) but appeared to be more specific than MRI and CT (86 %, 81 % and 67 %, respectively). PET findings resulted in changes in the management of a mean of 24 % of patients. The mean incidence of PET-based EHD was 32 %. This meta-analysis suggests that FDG PET/CT is highly accurate for the detection of liver metastases on a patient basis but less accurate on a lesion basis. Compared to MRI, PET is less sensitive but more specific and affects the management of about one-quarter of patients.

Aim To assess the predictive value of fluorine-18-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) in early assessing response during neo-adjuvant chemoradiotherapy (CRT) in patients with locally advanced rectal cancer. Materials and methods A systematic review was performed by search of MEDLINE Library for the following terms: "rectal carcinoma OR rectal cancer", "predictive OR prediction OR response assessment OR response OR assessment", "early OR ad interim ", "therapy", "FDG OR 18 F-FDG", "PET OR PET/CT". Articles performed by the use of stand-alone PET scanners were excluded. Results 10 studies met the inclusion criteria, including 302 patients. PET/CT demonstrated a good early predictive value in the global cohort (mean sensitivity = 79%; mean specificity = 78%). SUV and its percentage decrease (response index = RI) were calculated in all studies. A higher accuracy was demonstrated for RI (mean sensitivity = 82%; pooled specificity = 85%) with a mean cut-off of 42%. The mean time point to perform PET scan during CRT resulted to be at 1.85 weeks. Some PET parameters resulted to be both predictive and not statistical predictive of response, maybe due to the small population and few studies bias. Conclusion PET showed high accuracy in early prediction response during preoperative CRT, increased with the use of RI as parameter. In the era of tailored treatment, the precocious assessment of non-responder patients allows modification of the subsequent strategy especially the timing and the type of surgical approach.

AIM: The aim of our retrospective study was to assess the usefulness of F-FDG PET/CT in the restaging of clear cell renal cell carcinoma (RCC) patients. PATIENTS AND METHODS: Sixty-nine patients (median age = 62 years; range = 36-86 years) affected by clear cell RCC (TNM at staging: T1, 42 patients; T2, 13 patients; T3, 11 patients; T4, 3 patients; Fuhrman grade: G2, 47 patients; G3, 20 patients; G4, 2 patients) underwent whole-body F-FDG PET/CT to restage the disease after nephrectomy for clinical or radiological suspicion of metastases. Areas of abnormal uptake at PET/CT were classified, taking the liver uptake as reference, as follows: 1 = faint uptake, lower than liver; 2 = moderate uptake, equal to liver; and 3 = high uptake, higher than liver. Validation of F-FDG PET/CT results was established by (1) biopsy (23 patients) and (2) other imaging modalities (addressed BS; c.e.CT; MRI; F-fluoride PET/CT; subsequent F-FDG PET/CT), and/or clinical and radiological follow-up of 12 months (46 patients). RESULTS: F-FDG PET/CT was positive in 42 patients and negative in 27 patients. Sixteen patients presented single lesions and 26 patients presented multiple localizations of the disease. On a patient basis, 40 patients resulted true positive, 2 patient false positive, 23 patients true negative, and 4 patients false negative. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 90%, 92%, 91%, 95%, and 85%, respectively. On a lesion basis, PET/CT detected 114 areas of abnormal uptake in 42 positive patients of which 112 resulted to be true positive. FDG uptake of the true positive lesions resulted to be high in 83 cases, moderate in 17 lesions, and finally faint in 12 lesions. CONCLUSIONS: F-FDG PET/CT demonstrated a good sensitivity in the restaging of clear cell RCC. Most of the lesions showed intense activity. According to our results, it seems that the use of F-FDG PET/CT in the restaging of RCC is feasible because the number of false-negative cases is limited.

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.

AIM: The aim of this study was to evaluate the role of C-choline PET/CT in the preoperative evaluation of the nodal involvement of patients with bladder carcinoma (BC) suitable for radical cystectomy and extended pelvic lymph node dissection in comparison with contrast-enhanced CT (CECT) using the pathologic specimen as reference standard. PATIENTS AND METHODS: Twenty-six consecutive patients (69.5 ± 9.3 years; range, 49-84) with histologically proven transitional cell BC were treated with radical cystectomy and pelvic lymph node dissection and were enrolled from April 2011 to January 2013. In all patients, paravesical, internal, eternal, and common iliac nodes as well as obturatory, presacral, preaortic, and precaval lymph nodes (LNs) were dissected up to the origin of the inferior mesentery artery. The areas of the LN dissection were grouped as follow: region A included preaortic and precaval LNs; region B included paravesical, common, internal and external iliac, obturatory, and presacral LNs in the right pelvis; region C included paravesical, common, internal and external iliac, obturatory, and presacral LNs in the left pelvis. C-choline PET/CT and abdominal CECT were used to assess the presence of lymph node metastases on a per patient, region, and lesion analysis using the results of surgical specimens obtained at operation as criterion standard. RESULTS: Seven of 26 patients (26.9%) showed nodal metastases at pathologic analysis. Overall, 844 LNs were evaluated, and 38 of them (4.5%) showed metastatic involvement. On a patient-based analysis, C-choline PET/CT showed a sensitivity of 42% and specificity of 84%, whereas, CECT showed a sensitivity of 14% and specificity of 89%. On a region-based analysis, C-choline PET/CT showed a sensitivity of 11% and specificity of 82%, whereas CECT showed a sensitivity of 5% and specificity of 80%. On a lesion (LN)-based analysis, C-choline PET/CT showed a sensitivity of 10% and specificity of 64%, whereas CECT showed a sensitivity of 2% and specificity of 63%. CONCLUSIONS: C-choline PET/CT could provide additional diagnostic information in preoperative nodal staging of patients with invasive BC in comparison with CECT. A study with a larger population should determine if C-choline PET/CT could be recommended as a routine technique in high-risk patients with BC

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.

Endometriosis is a frequent and clinically relevant problem in young women. Laparoscopy is still the gold standard for the diagnosis of endometriosis, but frequently both morphologic and functional imaging techniques are involved in the diagnostic course before achieving a conclusive diagnosis. We present a case of a patient affected by infiltrating retroperitoneal endometriosis falsely interpreted as a malignant mass by contrast-enhanced magnetic resonance imaging and 18 F-fluorodeoxyglucose positron emission tomography/computed tomography.

PURPOSE FDG PET/CT has a recognized high predictive power to assess the response to neoadjuvant chemoradiation therapy (CRT) in patients affected by locally advanced rectal cancer (LARC), but a relatively high number of false-positive findings decrease its specificity: with the aim to solve this problem, a new method of imaging analysis is here proposed. METHODS The new method here described, named Biological target volume (BTV) Overlapping Segmentation System (BOSS), has been applied on 24 consecutive patients with LARC that were all previously classified as nonresponders to CRT by means of the response index criterion that is adopted in our center. The BOSS method is based on the quantification of the amount of superimposition between pretreatment and posttreatment BTV. All BTVpre was down using a threshold of 60% of SUVmax in the tumor (BTV60). The results (overlap volumes and percentage of overlap volumes) were then matched up with postoperative pathology classified by the Mandard's tumor regression grade (TRG) system. RESULTS Eleven patients were classified as responders (TRG1-2) and 13 as nonresponders (TRG 3-5). Among all the results obtained by BOSS method, only the percentage of overlap volume data between BTV60 and BTVpost (%Over_60) was able to correctly distinguish between responders and nonresponders. In our experience, a cutoff of 56% on the %Over_60 provided the best results in terms of true negative (11 cases), true positive (12 cases), false negative (1 case), and false positive (none). CONCLUSIONS This new method, we developed, appears able to unmask the false-positive cases, improving the specificity of FDG PET/CT to predict the response to CRT patients with LARC.

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

The outcome of head and neck squamous cell cancer depends primarily on its prompt diagnosis and treatment. Unfortunately, in many cases ominous prognostic factors such as lymph node metastases or osteomandibular extension are present at the time of diagnosis. We review the relative efficacy of contrast-enhanced computed tomography (ceCT), MRI, and F-fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) in the early detection of head and neck squamous cell cancer, as well as its impact on treatment management and outcomes. Medline and Web of Knowledge databases, from 2000 to January 2013, were evaluated. Ninety-seven reports were selected, but only 11 studies comparing PET or PET/CT with CT and 11 comparing PET or PET/CT with MRI were found appropriate for analysis. ceCT and MRI continue to be the reference imaging modalities for the study of primary tumors, especially in the evaluation of the extension of disease and its relationship with nearby anatomical structures. There is increasing evidence that F-FDG PET/ceCT can provide accurate anatomical details similar to ceCT alone, as well as accurate information on osteomandibular tumor invasion similar to MRI. The major advantage of PET/CT over other imaging methods is its ability to detect relatively small lymph node metastases located in difficult-to-interpret positions. PET/CT is also highly sensitive for the detection of distant metastases and in assessing the response to chemotherapy or chemoradiation treatment and in predicting outcome. ceCT and MRI are the gold standards for evaluating primary and osteomandibular tumoral infiltration. F-FDG PET/CT plays a major role in the detection of lymph node and distant metastases, in assessing the response to neoadjuvant/adjuvant chemotherapy or chemoradiation therapy, and in predicting outcome.

Novel diagnostic tools and therapies have emerged as a result of the continuous endeavors relating to neuroendocrine tumors (NETs). Nuclear medicine plays a pivotal role in the imaging and treatment of NETs. Somatostatin receptor analogues and metaiodobenzylguanidine remain front-line single-photon emission computed tomography (SPECT) radiotracers in the imaging of NET; their utility has been augmented by the increasing availability of SPECT/CT. Positron emission tomography has been growing rapidly in the imaging of NETs, paralleled by great efforts toward the development of new tracers. Hybrid imaging will play an important role in the future of NETs.

Background Proton Magnetic Resonance Spectroscopy (1H MRS) is used for clinical diagnosis in some tumours. The aim of this study is to explore ex vivo the potential of 1H MRS in identifying malignancy through metabolic markers in the perspective of its application in all cases of difficult diagnosis and after neoadjuvant treatment. Methods Spectroscopy was performed ex vivo on 29 colorectal specimens. All patients were staged with imaging, underwent radical surgery and then followed-up. Spectral quantification analysis of components expressed in colorectal tumours and in healthy mucosa were evaluated. The MRS-tumour marker (MRS-tm) was calculated for each case. The U-test was used to compare MRS-tm in tumours and in healthy mucosa. In order to select a cut-off for MRS-tm in the tumour and healthy mucosa and to distinguish patients who were disease-free or with recurrence-progression, we performed the ROC curve analysis. Results In the 24 subjects without neoadjuvant treatment, it was found that MRS-tm is able to discriminate healthy and neoplastic tissue and can discriminate patients with risk of recurrence/progression Conclusion Our data seem to show that 1H MRS may be successfully applied in vivo non-invasively to differentiate tumours from healthy mucosa and could also distinguish patients with different prognoses.

Purpose The aims of the study were (a) to evaluate the diagnostic role, by means of positive detection rate (PDR), of 18F-choline (CH) positron emission tomography (PET)/CT in patients with prostate cancer treated with radiotherapy, with curative intent, and suspicion of relapse during follow-up, (b) to correlate the PDR with trigger prostate-specific antigen (PSA), (c) to investigate the possible influence of androgen deprivation therapy (ADT) at the time of scan on PDR and (d) to assess distribution of metastatic spread.

The aim of this study was to correlate qualitative visual response and various PET quantification factors with the tumour regression grade (TRG) classification of pathological response to neoadjuvant chemoradiotherapy (CRT) proposed by Mandard.Included in this retrospective study were 69 consecutive patients with locally advanced rectal cancer (LARC). FDG PET/CT scans were performed at staging and after CRT (mean 6.7 weeks). Tumour SUVmax and its related arithmetic and percentage decrease (response index, RI) were calculated. Qualitative analysis was performed by visual response assessment (VRA), PERCIST 1.0 and response cut-off classification based on a new definition of residual disease. Metabolic tumour volume (MTV) was calculated using a 40 % SUVmax threshold, and the total lesion glycolysis (TLG) both before and after CRT and their arithmetic and percentage change were also calculated. We split the patients into responders (TRG 1 or 2) and nonresponders (TRG 3-5).SUVmax MTV and TLG after CRT, RI, ΔMTV% and ΔTLG% parameters were significantly correlated with pathological treatment response (p0.01) with a ROC curve cut-off values of 5.1, 2.1 cm(3), 23.4 cm(3), 61.8 %, 81.4 % and 94.2 %, respectively. SUVmax after CRT had the highest ROC AUC (0.846), with a sensitivity of 86 % and a specificity of 80 %. VRA and response cut-off classification were also significantly predictive of TRG response (VRA with the best accuracy: sensitivity 86 % and specificity 55 %). In contrast, assessment using PERCIST was not significantly correlated with TRG.FDG PET/CT can accurately stratify patients with LARC preoperatively, independently of the method chosen to interpret the images. Among many PET parameters, some of which are not immediately obtainable, the most commonly used in clinical practice (SUVmax after CRT and VRA) showed the best accuracy in predicting TRG.

The recent large use of the Cyclone® Plus Storage Phosphor System, especially in European countries, as imaging system for quantification of radiochemical purity of radiopharmaceuticals raised the problem of setting the periodic controls as required by European Legislation. We described simple, low-cost methods for Cyclone® Plus quality controls, which can be useful to evaluate the performance measurement of this imaging system.

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.

A patient with diffuse osteosclerotic bone metastases from invasive lobular breast carcinoma is presented with both F-FDG PET/CT and bone scans negative for hypermetabolic lesions. Skeletal metastases were documented by CT and bone marrow biopsy, and high increased CA 15-3 level was recorded. This case report points to the potential risk of false-negative FDG PET and bone scans examination in lobular carcinoma type.

Fluorine-18-fluorodeoxyglucose PET/CT is an accurate tool for predicting the response to preoperative chemoradiotherapy in locally advanced rectal cancer patients. The need for standardization has contributed to the development of various criteria for harmonizing PET response. The novel proposed set of criteria called PET Residual Disease in Solid Tumor (PREDIST) seems to better distinguish between responder and nonresponder patients to chemoradiotherapy compared with the PET Response Criteria in Solid Tumors criteria.

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.

Central nervous system (CNS) malignant tumors are usually treated with different combinations of surgery, radiotherapy and chemotherapy to achieve a radical treatment. After therapy, conventional imaging procedures (CT and MR) are useful to detect disease relapse but a correct differential diagnosis in presence post-surgical fibrosis, radionecrosis or oedema (benign conditions) may sometime be difficult. CNS shows physiologically an intense uptake of FDG and consequently, small and/or hypo/isometabolic malignant lesions are very difficult to detect, as they may be masked by the hypermetabolic surrounding tissue. 11C-Methionine is a radiolabeled aminoacid that physiologically do not accumulate into the brain, nor in case of benign conditions such as fibrosis, necrosis or oedema. On the other side, malignant lesions (although low grade) present an increased 11C-Methionine uptake due to an increased proteic metabolism and vascular permeability. Therefore 11CMethionine has optimal tumor-to-background ratio, making this radiotracer very useful to study CNS malignant tumors. The most appropriate indication for 11C-Methionine PET is the presence of non conclusive conventional imaging procedures, not allowing to discriminate between benign conditions and disease relapse. Other applications of 11C-Methionine PET are the definition of the radiotherapy field, the localization of the most metabolic area inside a mass to guide the biopsy and the early evaluation of radiotherapy effect, but all these applications are marginal and not yet validated.

We report the incidental finding of a pituitary macroadenoma on an F-choline PET/CT in a patient with recurrent prostate cancer. The pituitary gland was clearly enlarged and intensely FDG avid (SUVmax, 6.6). The diagnosis was confirmed by a subsequent contrast-enhanced MR evaluation, and the macroadenoma was classified as nonfunctioning on the basis of normality of the specific serum hormonal profile. A follow-up F-choline PET/CT scan performed after 6 months revealed stable dimension, and uptake of the pituitary macroadenoma patient deceased 1 month later. At autopsy, intracytoplasmic vesicles containing growth and prolactin hormones were observed at immunohistochemistry.

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.

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 pro-gnostic factor.

PET/CT with (18)F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal "incidentaloma" FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been 'indeterminately' categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.

Novel diagnostic tools and therapies have emerged as a result of the continuous endeavors relating to neuroendocrine tumors (NETs). Nuclear medicine plays a pivotal role in the imaging and treatment of NETs. Somatostatin receptor analogues and metaiodobenzylguanidine remain front-line single-photon emission computed tomography (SPECT) radiotracers in the imaging of NET; their utility has been augmented by the increasing availability of SPECT/CT. Positron emission tomography has been growing rapidly in the imaging of NETs, paralleled by great efforts toward the development of new tracers. Hybrid imaging will play an important role in the future of NETs.

Among the most interesting applications of ferromagnetic nanoparticles (NPs) in medicine is the potential for localizing pharmacologically or radioactively tagged agents directly to selected tissues selected by an adjustable external magnetic field. This concept is demonstrated by the application external magnetic field on IV Tc-labeled aminosilane-coated iron oxide NPs in a rat model. In a model comparing a rat with a 0.3-T magnet over a hind paw versus a rat without a magnet, a static acquisition at 45 minutes showed that 27% of the administered radioactivity was in the area subtended by the magnet, whereas the liver displays a percentage of binding of 14% in the presence of the magnet and of 16% in the absence of an external magnetic field. These preliminary results suggest that the application of an external magnetic field may be a viable route for the development of methods for the confinement of magnetic NPs labeled with radioactive isotopes targeted for predetermined sites of the body.

Purpose. (1) To evaluate a new acquisition protocol of18F-choline (FCH) PET/CT for prostate cancer patients (PC), (2) to review acquisition18F-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. Early18F-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.

This review article is focused on the role of FDG PET/CT in diagnosing and characterizing hepatic incidentalomas. A large variety of unsuspected lesions can be detected in the liver both with ultrasound and CT performed for other reasons; the prevalence of liver incidentalomas increases in patients with chronic liver disease or preexisting oncologic history. The major challenge is to discriminate benign from malignant lesions. There is a large body of literature indicating that FDG PET/CT is a useful tool to this purpose even if it is unspecific (ie, it cannot differentiate a primary tumor from a secondary lesion). Occasionally, FDG PET/CT can be useful for biopsy guidance.

PURPOSE The aim of this study was to correlate PERCIST criteria and a new criterion developed in our center that we named PREDIST (PET Residual Disease in Solid Tumor) with tumor regression grade (TRG) classification of pathologic response to neoadjuvant chemoradiotherapy (CRT) in patients affected by rectal cancer. METHODS Seventy-three consecutive patients affected by locally advanced rectal cancer (LARC) were retrospectively included. FDG-PET/CT scans were performed at staging time and after the end of CRT (mean time 6.5 weeks). The analysis was performed by PERCIST criteria 1.0 and PREDIST criteria based on a new definition of residual disease. We split the TRG system into responders (TRG1-2) and nonresponders (TRG3-5). Pearson chi-square analysis by cross-tabulations was performed. RESULTS PREDIST classification was statistically predictive of TRG response (P = 0.004, sensitivity 81.8% and specificity 54.9%). On the contrary, PERCIST criteria was not statistically correlated to TRG (P = 0.128) caused by a very low specificity (9.8%). CONCLUSIONS FDG-PET/CT scan is an accurate tool to predict preoperatively the response to CRT in LARC patients. The novel proposed criterion (PREDIST) seems to be helpful to discriminate responder by nonresponder patients.

A 59-year-old man presented with frequent urination. Six months ago, his prostate-specific antigen (PSA) was 1.56 ng/mL; currently it is 3.5 ng/mL (PSA doubling time = 6 months; PSA velocity = 0.19 ng/mL/mo). Biopsy revealed aggressive prostate cancer (Gleason score 5 + 5). Staging with (18)F-fluorocholine PET/CT ((18)F-FCH PET/CT) demonstrated lymph node metastasis. After 6 months of hormonal therapy with goserelin, PSA decreased to 0.38 ng/mL. A (18)F-FCH PET/CT restaging scan demonstrated a global reduction of (18)F-FCH lesion uptake with disappearance of some mediastinal and iliac pelvic lymph node activity.

Limbic encephalitis is one of the most common paraneoplastic neurological syndromes, which is mostly associated with small cell lung cancer, testicular tumors, and breast cancer. F-FDG PET/CT can have an important role both in the identification of limbic encephalitis itself and in the detection of the unknown malignancy that might have caused it. We report a case of a 57-year-old female patient with paraneoplastic limbic encephalitis, confirmed both by MRI and F-FDG PET/CT, and the concurrent identification of an unknown lung malignancy by whole-body PET/CT.