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Summary: Background: 68Ga‐labelled prostate‐specific membrane antigen (PSMA) is a promising PET ligand for the detection of prostate cancer. Little attention has been given to the ability of 68Ga‐PSMA PET/CT to detect malignant bone lesions and whether this approach is superior to existing bone imaging modalities. Aim: To review the existing data of 68Ga‐PSMA PET/CT for the diagnosis of bone metastases in prostate cancer. Methods: Systematic review of the peer‐reviewed literature. Results: Among 1858 papers in the original search, 37 papers were included in the analysis (six case reports and 31 case series). The vast majority of the studies were low‐level evidence studies. Most studies presented data on detection rates without a reference standard. All but two studies were of a retrospective nature. Several cohort studies showed bone metastasis in 5–60% of patients with prostate cancer, including in patients with very low‐PSA values. For primary staging, 68Ga‐PSMA PET/CT outperformed bone scans, while the superiority of 68Ga‐PSMA PET/CT compared with bone scans with respect to biochemical recurrence and metastatic castration‐resistant prostate cancer (mCRPC) remains to be demonstrated. Conclusion: 68Ga‐PSMA PET/CT has shown to be a promising technique for use in prostate cancer. 68Ga‐PSMA PET/CT shows more lesions than bone scans, but data on diagnostic performance are very limited and indicate improved diagnostic performance in primary staging but not in mCRPC. Properly designed studies are needed to clarify the diagnostic performance of 68Ga‐PSMA PET/CT as well as its superiority over existing methods before 68Ga‐PSMA PET/CT can be routinely used for bone imaging. [ABSTRACT FROM AUTHOR]

Purpose: To prospectively compare diagnostic accuracies for detection of bone metastases by 68Ga-PSMA PET/CT, 18F-NaF PET/CT and diffusion-weighted MRI (DW600-MRI) in prostate cancer (PCa) patients with biochemical recurrence (BCR).Methods: Sixty-eight PCa patients with BCR participated in this prospective study. The patients underwent 68Ga-PSMA PET/CT, a 18F-NaF PET/CT and a DW600-MRI (performed in accordance with European Society of Urogenital Radiology guidelines, with b values of 0 and 600 s/mm2). Bone lesions were categorized using a three-point scale (benign, malignant or equivocal for metastases) and a dichotomous scale (benign or metastatic) for each imaging modality by at least two experienced observers. A best valuable comparator was defined for each patient based on study-specific imaging, at least 12 months of clinical follow-up and any imaging prior to the study and during follow-up. Diagnostic performance was assessed using a sensitivity analysis where equivocal lesions were handled as non-metastatic and then as metastatic.Results: Ten of the 68 patients were diagnosed with bone metastases. On a patient level, sensitivity, specificity and the area under the curve (AUC) by receiver operating characteristic analysis were, respectively, 0.80, 0.98-1.00 and 0.89-0.90 for 68Ga-PSMA PET/CT (n = 68 patients); 0.90, 0.90-0.98 and 0.90-0.94 for 18NaF PET/CT (n = 67 patients); and 0.25-0.38, 0.87-0.92 and 0.59-0.62 for DW600-MRI (n = 60 patients). The diagnostic performance of DW600-MRI was significantly lower than that of 68Ga-PSMA PET/CT and 18NaF PET/CT for diagnosing bone metastases (p < 0.01), and no significant difference in the AUC was seen between 68Ga-PSMA PET/CT and 18NaF PET/CT (p = 0.65).Conclusion: 68Ga-PSMA PET/CT and 18F-NaF PET/CT showed comparable and high diagnostic accuracies for detecting bone metastases in PCa patients with BCR. Both methods performed significantly better than DW600-MRI, which was inadequate for diagnosing bone metastases when conducted in accordance with European Society of Urogenital Radiology guidelines. [ABSTRACT FROM AUTHOR]

Localization of prostate cancer recurrence, particularly in the bones, is a major challenge with standard of care imaging in patients with biochemical recurrence following curatively intended treatment. Gallium-68-labeled prostate specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) is a novel and promising method for imaging in prostate cancer. The present study reports two cases of patients with prostate cancer with biochemical recurrence, with evidence of bone metastases on 68Ga-PSMA PET/CT images and low prostate specific antigen PSA levels (<2 ng/ml) and PSA doubling time >6 months. The bone metastases were verified by supplementary imaging with 18F-sodium fluoride PET/CT and magnetic resonance imaging as well as biochemical responses to androgen deprivation therapy. Therefore, 68Ga-PSMA PET/CT is promising for the restaging of patients with prostate cancer with biochemical recurrence, including patients with low PSA levels and low PSA kinetics. [ABSTRACT FROM AUTHOR]

Simple Summary: Irreversible electroporation (IRE) is a novel therapy that is being studied for the treatment of nonmetastatic pancreatic cancer. The current methods for evaluating the treatment response after IRE have been adapted from the Response Evaluation Criteria in Solid Tumors (RECIST). However, it is uncertain whether these methods are appropriate, because the methods have not been validated. The aim of the current study was to evaluate the correlation between survival time and the most commonly used imaging assessment methods on FDG-PET/CT scans. We confirmed that the Response Evaluation Criteria in Solid Tumors (RECIST) are correlated with survival, when applied as intended. However, no correlation was found when the often-used lesion-level method was used. FDG-PET-derived data did not provide any benefit over conventional CT data. Several novel methods for lesion-level analysis were explored. (1) Background: Irreversible electroporation (IRE) is a nonthermal ablation technique that is being studied in nonmetastatic pancreatic cancer (PC). Most published studies use imaging outcomes as an efficacy endpoint, but imaging interpretation can be difficult and has yet to be correlated with survival. The aim of this study was to examine the correlation of imaging endpoints with survival in a cohort of IRE-treated PC patients. (2) Methods: Several imaging endpoints were examined before and after IRE on 18F-fluorodeoxyglucose positron emission tomography (PET) with computed tomography. Separate analyses were performed at the patient and lesion levels. Mortality rate (MR) ratios for imaging endpoints after IRE were estimated. (3) Results: Forty-one patients were included. Patient-level analysis revealed that progressive disease (PD), as defined by RECIST 1.1, is correlated with a higher MR at all time intervals, but PD, as defined by EORTC PET response criteria, is only correlated with the MR in the longest interval. No correlation was found between PD, as defined by RECIST, and the MR in the lesion-level analysis. (4) Conclusions: Patient-level PD, as defined by RECIST, was correlated with poorer survival after IRE ablation, whereas no correlations were observed in the lesion-level analyses. Several promising lesion-level outcomes were identified. [ABSTRACT FROM AUTHOR]

Incidental focal uptake of 18F-fluorodeoxyglucose (FDG) in the thyroid on positron emission tomography (PET/CT) is rare but often associated with malignancy. The epidemiology of thyroid incidentalomas has only to some extent been described in countries with iodine deficiency. Here we report data from Denmark, a country with known iodine deficiency and wide access to PET/CT. All FDG PET/CT comprising the head and neck region, during 2014, were retrospectively reviewed, and patients with focal FDG uptake in the thyroid gland were identified. A total of 2451 patients had an FDG PET/CT of which 59 (2.4%) patients presented with FDG-avid focal lesions in the thyroid gland. Among the 59 patients with FDG-avid lesions, 33 patients (56%) received work up with ultrasound, thyroid technetium scintigraphy, fine needle aspiration, and/or histology of which 20 patients had a conclusive pathology report. Ten patients with FDG-avid lesions were identified with thyroid malignancy. The risk of thyroid malignancy was 16.9% among patient with incidental FDG-avid thyroid lesions. Our findings indicated a similar frequency of FDG thyroid incidentalomas and malignancy rates in an iodine deficient population compared to summary data from prior studies, studies mostly performed in geographical areas of normal or excess iodine supplementation. [ABSTRACT FROM AUTHOR]

Background: For decades, planar bone scintigraphy has been the standard practice for detection of bone metastases in prostate cancer and has been endorsed by recent oncology/urology guidelines. It is a sensitive method with modest specificity. (18)F-fluoride positron emission tomography/computed tomography has shown improved sensitivity and specificity over bone scintigraphy, but because of methodological issues such as retrospective design and verification bias, the existing level of evidence with (18)F-fluoride positron emission tomography/computed tomography is limited. The primary objective is to compare the diagnostic properties of (18)F-fluoride positron emission tomography/computed tomography versus bone scintigraphy on an individual patient basis.Methods/design: One hundred forty consecutive, high-risk prostate cancer patients will be recruited from several hospitals in Denmark. Sample size was calculated using Hayen's method for diagnostic comparative studies. This study will be conducted in accordance with recommendations of standards for reporting diagnostic accuracy studies. Eligibility criteria comprise the following: 1) biopsy-proven prostate cancer, 2) PSA ≥ 50 ng/ml (equals a prevalence of bone metastasis of ≈ 50% in the study population on bone scintigraphy), 3) patients must be eligible for androgen deprivation therapy, 4) no current or prior cancer (within the past 5 years), 5) ability to comply with imaging procedures, and 6) patients must not receive any investigational drugs. Planar bone scintigraphy and (18)F-fluoride positron emission tomography/computed tomography will be performed within a window of 14 days at baseline. All scans will be repeated after 26 weeks of androgen deprivation therapy, and response of individual lesions will be used for diagnostic classification of the lesions on baseline imaging among responding patients. A response is defined as PSA normalisation or ≥ 80% reduction compared with baseline levels, testosterone below castration levels, no skeletal related events, and no clinical signs of progression. Images are read by blinded nuclear medicine physicians. The protocol is currently recruiting.Discussion: To the best of our knowledge, this is one of the largest prospective studies comparing (18)F-fluoride positron emission tomography/computed tomography and bone scintigraphy. It is conducted in full accordance with recommendations for diagnostic accuracy trials. It is intended to provide valid documentation for the use of (18)F-fluoride positron emission tomography/computed tomography for examination of bone metastasis in the staging of prostate cancer. [ABSTRACT FROM AUTHOR]