To systematically review published data on the role of positron emission tomography (PET) or PET/computed tomography (PET/CT) using either Carbon-11 ((11)C) or Fluorine-18 ((18)F) choline tracer in tumors other than prostatic cancer. A comprehensive literature search of studies published in PubMed/MEDLINE and Embase databases through January 2012 and regarding (11)C-choline or (18)F-choline PET or PET/CT in patients with tumors other than prostatic cancer was carried out. Fifty-two studies comprising 1800 patients were included and discussed. Brain tumors were evaluated in 15 articles, head and neck tumors in 6, thoracic tumors (including lung and mediastinal neoplasms) in 14, liver tumors (including hepatocellular carcinoma) in 5, gynecologic malignancies (including breast tumors) in 5, bladder and upper urinary tract tumors in 5, and musculoskeletal tumors in 7. Radiolabeled choline PET or PET/CT is useful to differentiate high-grade from low-grade gliomas and malignant from benign brain lesions, to early detect brain tumor recurrences and to guide the stereotactic biopsy sampling. The diagnostic accuracy of radiolabeled choline PET is superior compared to Fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET in this setting. Radiolabeled choline PET or PET/CT seems to be accurate in differential diagnosis between malignant and benign thoracic lesions and in staging lung tumors; nevertheless, a superiority of radiolabeled choline compared to (18)F-FDG has not been demonstrated in this setting, except for the detection of brain metastases. Few but significant studies on radiolabeled choline PET and PET/CT in patients with hepatocellular carcinoma (HCC) and musculoskeletal tumors are reported in the literature. The combination of radiolabeled choline and (18)F-FDG PET increases the detection rate of HCC. The diagnostic accuracy of radiolabeled choline PET or PET/CT seems to be superior compared to (18)F-FDG PET or PET/CT and conventional imaging methods in patients with bone and soft tissue tumors. Limited experience exists about the role of radiolabeled choline PET and PET/CT in patients with head and neck tumors, bladder cancer and gynecologic malignancies including breast cancer.

Background:: The rising incidence rate of prostate cancer (PCa) has promoted the development of new diagnostic and therapeutic radiopharmaceuticals during the last decades. Promising improvements have been achieved in clinical practice using prostate specific membrane antigen (PSMA) labeled agents, including specific antibodies and small molecular weight inhibitors. Focusing on molecular docking studies, this review aims to highlight the progress in the design of PSMA targeted agents for a potential use in nuclear medicine. Results:: Although the first development of radiopharmaceuticals able to specifically recognize PSMA was exclusively oriented to macromolecule protein structure such as radiolabeled monoclonal antibodies and derivatives, the isolation of the crystal structure of PSMA served as the trigger for the synthesis and the further evaluation of a variety of low molecular weight inhibitors. Among the nuclear imaging probes and radiotherapeutics that have been developed and tested till today, labeled Glutamate-ureido inhibitors are the most prevalent PSMA-targeting agents for nuclear medicine applications. Conclusion:: PSMA represents for researchers the most attractive target for the detection and treatment of patients affected by PCa using nuclear medicine modalities. [99mTc]MIP-1404 is considered the tracer of choice for SPECT imaging and [68Ga]PSMA-11 is the leading diagnostic for PET imaging by general consensus. [18F]DCFPyL and [18F]PSMA-1007 are clearly the emerging PET PSMA candidates for their great potential for a widespread commercial distribution. After paving the way with new imaging tools, academic and industrial R&Ds are now focusing on the development of PSMA inhibitors labeled with alpha or beta minus emitters for a theragnostic application.

Thyroid incidental uptake is defined as a thyroid uptake incidentally and newly detected by imaging techniques performed for an unrelated purpose and especially for non-thyroid diseases. Aim of the study was to establish the prevalence and pathological nature of focal thyroid incidentalomas detected at F18-FDG-PET/CT in patients studied for oncological purposes and not for thyroid disease. Secondary end point was to establish a possible maximum standardised uptake value cut-off over which a malignant lesion should be suspected. We have retrospectively evaluated 49519 patients who underwent F18-FDG-PET/CT for oncologic purposes in three Nuclear Medicine Centres (N.1 = 11278, N.2 = 31076, N.3 = 7165). A focal incidental thyroid uptake was diagnosed in 729 (1.5 %) patients (287-39.4 % male and 442-60.6 % female; average age: 65.26). Of 729 thyroid incidentalomas 211 (28.9 %) underwent further investigation to determine the nature of the nodule; 124/211 (58.8 %) incidentalomas were benign, 72/211 (34.1 %) malignant, 4/211 (1.9 %) non-diagnostic at cytological examination in the absence of surgery and histological evaluation and 11/211 (5.2 %) were indeterminate at cytological examination. A centre-based receiver operating curve (ROC) analysis of the patients with a definitive diagnosis was performed to identify a SUVmax cut-off useful in differentiating benign from malignant incidentalomas. In the centre N.1 it was 4.8 (sensitivity = 95.7 %, specificity = 46.4 %, area under the curve = 0.758); 5.3 in the centre N.2 (sensitivity = 76.3 %, specificity = 72.5 %, area under the curve = 0.815); 7 in the centre N.3 (sensitivity = 57.1 %, specificity = 79.3 %, area under the curve = 0.627). F18-FDG-PET/CT thyroid incidentalomas are a relevant diagnostic reality which requires further investigations and clinical management especially considering that, despite mainly benign, approximately one third of focal thyroid uptakes are malignant.

We here aim to provide a comprehensive and critical review of the literature concerning the clinical applications of positron emission tomography/computed tomography (PET/CT) with radiolabeled choline in patients with prostate cancer (PCa). We will initially briefly summarize the historical context that brought to the synthesis of [C]choline, which occurred exactly 20 years ago. We have arbitrarily grouped the clinical studies in three different periods, according to the year in which they were published and according to their relation with their applications in urology, radiotherapy and oncology. Studies at initial staging and, more extensively, studies in patients with biochemical failure, as well as factors predicting positive PET/CT will be reviewed. The capability of PET/CT with radiolabeled choline to provide prognostic information on PCa-specific survival will also be examined. The last sections will be devoted to the use of radiolabeled choline for monitoring the response to androgen deprivation therapy, radiotherapy, and chemotherapy. The accuracy and the limits of the technique will be discussed according to the information available from standard validation processes, including biopsy or histology. The clinical impact of the technique will be discussed on the basis of changes induced in the management of patients and in the evaluation of the response to therapy. Current indications to PET/CT, as officially endorsed by guidelines, or as routinely performed in the clinical practice will be illustrated. Emphasis will be made on methodological factors that might have influenced the results of the studies or their interpretation. Finally, we will briefly highlight the potential role of positron emission tomography/magnetic resonance and of new radiotracers for PCa imaging.

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