Diagnostic value of [ 68 Ga]Ga-Pentixafor PET/CT in malignant melanoma: a pilot study.

OBJECTIVE: To evaluate the diagnostic value of [ 68 Ga] Ga-Pentixafor in malignant melanoma patients. METHODS: In this prospective study, patients with histology-proven melanoma were included and underwent [ 18 F]fluoro-D-glucose ([ 18 F]FDG) and [ 68 Ga] Ga-Pentixafor PET/computed tomography (CT) within a week. Suspicious lesions were interpreted as benign vs. malignant, and the corresponding semi-quantitative PET/CT parameters were recorded and compared. RESULTS: Twelve consecutive melanoma patients (mean age: 60 ±â€…6) were included. Two patients were referred for initial staging, two for detecting recurrence and eight for evaluating the extent of metastases. Overall, [ 18 F]FDG PET/CT showed 236 tumoral lesions, including two primary tumors, two recurrent lesions, 29 locoregional metastases and 203 distant metastases. In [ 68 Ga]Ga-Pentixafor PET/CT, 101 tumoral lesions were detected, including two primary tumors, one recurrence, 16 locoregional metastases and 82 distant metastases. Notably, a documented brain metastasis was only visualized on [ 68 Ga]Ga-Pentixafor PET/CT images. Compared with [ 18 F]FDG, [ 68 Ga]Ga-Pentixafor PET/CT provided a 42% detection rate. Regarding semi-quantitative measures, the intensity of uptake and tumor-to-background ratios were significantly lower on [ 68 Ga]Ga-Pentixafor PET/CT [average maximum standard uptake value (SUV max ) of 2.72 ±â€…1.33 vs. 11.41 ±â€…14.79; P value <0.001 and 1.17 ±â€…0.53 vs. 5.32 ±â€…7.34; P value <0.001, respectively]. CONCLUSION: When comparing [ 68 Ga]Ga-Pentixafor PET/CT with [ 18 F]FDG PET/CT, not only did [ 68 Ga]Ga-Pentixafor PET/CT detect fewer lesions, but the intensity of uptake and the TBRs were also lower on [ 68 Ga]Ga-Pentixafor PET/CT. Thus, our results may indicate a limited potential of this novel tracer in cutaneous melanoma patients compared to [ 18 F]FDG PET/CT. Given the lower TBRs, applying this radiotracer in radioligand therapies is also questionable.

A convolutional neural network-based system for fully automatic segmentation of whole-body [68Ga]Ga-PSMA PET images in prostate cancer.

PURPOSE: The aim of this study was development and evaluation of a fully automated tool for the detection and segmentation of mPCa lesions in whole-body [68Ga]Ga-PSMA-11 PET scans by using a nnU-Net framework. METHODS: In this multicenter study, a cohort of 412 patients from three different center with all indication of PCa who underwent [68Ga]Ga-PSMA-11 PET/CT were enrolled. Two hundred cases of center 1 dataset were used for training the model. A fully 3D convolutional neural network (CNN) is proposed which is based on the self-configuring nnU-Net framework. A subset of center 1 dataset and cases of center 2 and center 3 were used for testing of model. The performance of the segmentation pipeline that was developed was evaluated by comparing the fully automatic segmentation mask with the manual segmentation of the corresponding internal and external test sets in three levels including patient-level scan classification, lesion-level detection, and voxel-level segmentation. In addition, for comparison of PET-derived quantitative biomarkers between automated and manual segmentation, whole-body PSMA tumor volume (PSMA-TV) and total lesions PSMA uptake (TL-PSMA) were calculated. RESULTS: In terms of patient-level classification, the model achieved an accuracy of 83%, sensitivity of 92%, PPV of 77%, and NPV of 91% for the internal testing set. For lesion-level detection, the model achieved an accuracy of 87-94%, sensitivity of 88-95%, PPV of 98-100%, and F1-score of 93-97% for all testing sets. For voxel-level segmentation, the automated method achieved average values of 65-70% for DSC, 72-79% for PPV, 53-58% for IoU, and 62-73% for sensitivity in all testing sets. In the evaluation of volumetric parameters, there was a strong correlation between the manual and automated measurements of PSMA-TV and TL-PSMA for all centers. CONCLUSIONS: The deep learning networks presented here offer promising solutions for automatically segmenting malignant lesions in prostate cancer patients using [68Ga]Ga-PSMA PET. These networks achieve a high level of accuracy in whole-body segmentation, as measured by the DSC and PPV at the voxel level. The resulting segmentations can be used for extraction of PET-derived quantitative biomarkers and utilized for treatment response assessment and radiomic studies.

A case of ankylosing spondylitis presenting with fever of unknown origin diagnosed as aortitis: A case report.

Key Clinical Message: Clinicians should be aware of rare manifestations of AS, while considering a low threshold for screening vascular involvement in an axial SpA/nrxSpA/AS presenting with unexplained fevers and significant constitutional symptoms and elevated markers. Abstract: Ankylosing spondylitis (AS) is a chronic inflammatory disease from the spondyloarthritis complex, which usually affects young men and primarily involves sacroiliac joints and the spine. It can also present with non-joint involvement, such as cardiovascular manifestations. Aortitis is a rare yet critical cardiovascular complication associated with AS, which can lead to life-threatening outcomes when undiagnosed. Here we report a 34-year-old man with intermittent fevers and significant weight loss, myalgia, and arthralgia for 1 year before being referred to our hospital due to undefinable causes despite multiple diagnostic efforts. The patient presented with elevated inflammatory markers and involvement of sacroiliac joints in favor of the AS. A positron emission tomography scan was also done to rule out underlying malignancy, which led to the detection of inflammation in ascending aorta, compatible with aortitis. The patient was treated with nonsteroidal anti-inflammatory drugs, prednisolone, and infliximab, and his signs and symptoms significantly improved. Our case reports a rare but substantial complication of AS, in a young patient without a history of prolonged disease presenting with unspecific manifestations. The implantation of a thorough examination of AS patients, including cardiac examinations, could contribute to faster and more efficient diagnosis and treatment.

Diagnostic value of [ 68 Ga]Ga-Pentixafor versus [ 18 F]FDG PET/CTs in non-small cell lung cancer: a head-to-head comparative study.

OBJECTIVE: In this study, we aimed to compare the diagnostic value of [ 68 Ga]Ga-Pentixafor and [ 18 F]FDG PET/CT in the evaluation of non-small cell lung cancer (NSCLC) patients. METHODS: Patients with pathology-proven NSCLC were prospectively included. Patients underwent [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT within 1 week. All suspicious lesions were interpreted as benign or malignant, and the corresponding PET/CT semi-quantitative parameters were recorded. A two-sided P -value <0.05 was considered significant. RESULTS: Twelve consecutive NSCLC patients (mean age: 60 ±â€…7) were included. All patients underwent both [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT scans with a median interval of 2 days. Overall, 73 abnormal lesions were detected, from which 58 (79%) were concordant between [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT. All primary tumors were clearly detectable in both scans visually. Also, [ 68 Ga]Ga-Pentixafor PET/CT demonstrated rather comparable results with [ 18 F]FDG PET/CT scan in detecting metastatic lesions. However, malignant lesions demonstrated significantly higher SUVmax and SUVmean in [ 18 F]FDG PET/CT ( P -values <0.05). Regarding the advantages, [ 68 Ga]Ga-Pentixafor depicted two brain metastases that were missed by [ 18 F]FDG PET/CT. Also, a highly suspicious lesion for recurrence on [ 18 F]FDG PET/CT scan was correctly classified as benign by subsequent [ 68 Ga]Ga-Pentixafor PET/CT. CONCLUSION: [ 68 Ga]Ga-Pentixafor PET/CT was concordant with [ 18 F]FDG PET/CT in detecting primary NSCLC tumors and could visualize the majority of metastatic lesions. Moreover, this modality was found to be potentially helpful in excluding tumoural lesions when the [ 18 F]FDG PET/CT was equivocal, as well as in detecting brain metastasis where [ 18 F]FDG PET/CT suffers from poor sensitivity. However, the count statistics were significantly lower.

The Prognostic and therapeutic value and clinical implications of fibroblast activation protein-α as a novel biomarker in colorectal cancer.

The identification of contributing factors leading to the development of Colorectal Cancer (CRC), as the third fatal malignancy, is crucial. Today, the tumor microenvironment has been shown to play a key role in CRC progression. Fibroblast-Activation Protein-α (FAP) is a type II transmembrane cell surface proteinase expressed on the surface of cancer-associated fibroblasts in tumor stroma. As an enzyme, FAP has di- and endoprolylpeptidase, endoprotease, and gelatinase/collagenase activities in the Tumor Microenvironment (TME). According to recent reports, FAP overexpression in CRC contributes to adverse clinical outcomes such as increased lymph node metastasis, tumor recurrence, and angiogenesis, as well as decreased overall survival. In this review, studies about the expression level of FAP and its associations with CRC patients' prognosis are reviewed. High expression levels of FAP and its association with clinicopathological factors have made as a potential target. In many studies, FAP has been evaluated as a therapeutic target and diagnostic factor into which the current review tries to provide a comprehensive insight. Video Abstract.

Predictive and prognostic potential of pretreatment 68Ga-PSMA PET tumor heterogeneity index in patients with metastatic castration-resistant prostate cancer treated with 177Lu-PSMA.

Introduction: This study was conducted to evaluate the predictive values of volumetric parameters and radiomic features (RFs) extracted from pretreatment 68Ga-PSMA PET and baseline clinical parameters in response to 177Lu-PSMA therapy. Materials and methods: In this retrospective multicenter study, mCRPC patients undergoing 177Lu-PSMA therapy were enrolled. According to the outcome of therapy, the patients were classified into two groups including positive biochemical response (BCR) (≥ 50% reduction in the serum PSA value) and negative BCR (< 50%). Sixty-five RFs, eight volumetric parameters, and also seventeen clinical parameters were evaluated for the prediction of BCR. In addition, the impact of such parameters on overall survival (OS) was evaluated. Results: 33 prostate cancer patients with a median age of 69 years (range: 49-89) were enrolled. BCR was observed in 22 cases (66%), and 16 cases (48.5%) died during the follow-up time. The results of Spearman correlation test indicated a significant relationship between BCR and treatment cycle, administered dose, HISTO energy, GLCM entropy, and GLZLM LZLGE (p<0.05). In addition, according to the Mann-Whitney U test, age, cycle, dose, GLCM entropy, and GLZLM LZLGE were significantly different between BCR and non BCR patients (p<0.05). According to the ROC curve analysis for feature selection for prediction of BCR, GLCM entropy, age, treatment cycle, and administered dose showed acceptable results (p<0.05). According to SVM for assessing the best model for prediction of response to therapy, GLCM entropy alone showed the highest predictive performance in treatment planning. For the entire cohort, the Kaplan-Meier test revealed a median OS of 21 months (95% CI: 12.12-29.88). The median OS was estimated at 26 months (95% CI: 17.43-34.56) for BCR patients and 13 months (95% CI: 9.18-16.81) for non BCR patients. Among all variables included in the Kaplan Meier, the only response to therapy was statistically significant (p=0.01). Conclusion: This exploratory study showed that the heterogeneity parameter of pretreatment 68Ga-PSMA PET images might be a potential predictive value for response to 177Lu-PSMA therapy in mCRPC; however, further prospective studies need to be carried out to verify these findings.

ImmunoPET: Antibody-Based PET Imaging in Solid Tumors.

Immuno-positron emission tomography (immunoPET) is a molecular imaging modality combining the high sensitivity of PET with the specific targeting ability of monoclonal antibodies. Various radioimmunotracers have been successfully developed to target a broad spectrum of molecules expressed by malignant cells or tumor microenvironments. Only a few are translated into clinical studies and barely into clinical practices. Some drawbacks include slow radioimmunotracer kinetics, high physiologic uptake in lymphoid organs, and heterogeneous activity in tumoral lesions. Measures are taken to overcome the disadvantages, and new tracers are being developed. In this review, we aim to mention the fundamental components of immunoPET imaging, explore the groundbreaking success achieved using this new technique, and review different radioimmunotracers employed in various solid tumors to elaborate on this relatively new imaging modality.

68 Ga-FAPI-46 PET/CT in a Metastatic Castration-Resistant Prostate Cancer Patient With Low PSMA Expression.

ABSTRACT: A 70-year-old man with mCRPC (metastatic castration-resistant prostate cancer) was referred for 68 Ga-PSMA PET/CT for restaging and the possibility of targeted molecular radioligand therapy with 177 Lu-PSMA. Numerous 68 Ga-PSMA-avid skeletal metastases with low SUVs were noted. Because of low PSMA expression, a 68 Ga-FAPI-46 PET/CT was performed to evaluate the eligibility for FAPI-based radioligand therapy. There were some discordant findings between 68 Ga-PSMA and 68 Ga-FAPI PET/CT scans regarding the detectability of lesions and SUVs. Our case signifies that 68 Ga-FAPI theragnostic may have a potential role in the treatment of mCRPC patients with insignificant PSMA expression or in cases after the failure of 177 Lu-PSMA therapy.

[18F]FDG-PET/CT Radiomics and Artificial Intelligence in Lung Cancer: Technical Aspects and Potential Clinical Applications.

Lung cancer is the second most common cancer and the leading cause of cancer-related death worldwide. Molecular imaging using [18F]fluorodeoxyglucose Positron Emission Tomography and/or Computed Tomography ([18F]FDG-PET/CT) plays an essential role in the diagnosis, evaluation of response to treatment, and prediction of outcomes. The images are evaluated using qualitative and conventional quantitative indices. However, there is far more information embedded in the images, which can be extracted by sophisticated algorithms. Recently, the concept of uncovering and analyzing the invisible data extracted from medical images, called radiomics, is gaining more attention. Currently, [18F]FDG-PET/CT radiomics is growingly evaluated in lung cancer to discover if it enhances the diagnostic performance or implication of [18F]FDG-PET/CT in the management of lung cancer. In this review, we provide a short overview of the technical aspects, as they are discussed in different articles of this special issue. We mainly focus on the diagnostic performance of the [18F]FDG-PET/CT-based radiomics and the role of artificial intelligence in non-small cell lung cancer, impacting the early detection, staging, prediction of tumor subtypes, biomarkers, and patient's outcomes.

Diagnostic value of lacrimal scintigraphy in the evaluation of lacrimal drainage system obstruction: a systematic review and meta-analysis.

PURPOSE: A systematic review and meta-analysis to evaluate the diagnostic performance of lacrimal scintigraphy (LS) versus anatomical methods in the evaluation of the nasolacrimal duct obstruction (NLDO). MATERIALS AND METHODS: A systematic search was performed using electronic bibliographic databases until the end of May 2021. Inclusion criteria: (a) used LS as a diagnostic method to evaluate NLDO; (b) used anatomical studies [including syringing, irrigation, probing, and dacryocystography (DCG)] as reference tests; and (c) provided adequate crude data. A hierarchical method was used to pool the sensitivity and specificity. The hierarchical summary receiver-operating characteristic model was performed. Additionally, the studies' heterogeneity and publication bias were analyzed. All analyses were conducted by the 'Midas' module of STATA 16. RESULTS: Twelve articles (with 14 separate populations) were considered eligible to enter the meta-analysis. They were divided into two groups based on the reference standard method, called irrigation and DCG groups. In the irrigation group, the pooled sensitivity and specificity were 89% [95% confidence interval (CI), 72-96%] and 25% (95% CI, 8-56%), respectively. In DCG group, the pooled sensitivity and specificity were 97% (95% CI, 85-100%) and 27% (95% CI, 0.12-0.49), in turn. CONCLUSION: LS is a sensitive modality to evaluate the anatomical obstruction of NLD. In contrast, it shows low pooled specificity compared with anatomical methods. Thus, LS can be used as the first noninvasive modality for the evaluation of epiphora. However, in case of any abnormality, confirmatory procedures are required.

68Ga-DOTATATE Uptake in an Intraosseous Hemangioma, as a Potential Cause of False-Positive PET/CT Finding, Simulating Tumoral Involvement.

ABSTRACT: We present the case of a 32-year-old man with a history of hypophosphatemia and multiple bone fractures, being evaluated at our center for a potential mesenchymal tumor. 68Ga-DOTATATE PET/CT revealed a highly 68Ga-DOTATATE-avid lesion in the ethmoidal sinus extending to the nasal cavity. Following resection, histologic examination of the specimen confirmed the diagnosis of "intraosseous hemangioma," a potential cause of false-positive finding of 68Ga-DOTATATE PET/CT imaging in patients being evaluated for occult malignancies, especially at the traumatic/fractured sites.

Prognostic value of 2-[18F]FDG PET-CT in metastatic melanoma patients receiving immunotherapy.

PURPOSE: The 2-fluorodeoxyglucose positron emission tomography/computed tomography (2-[18F]FDG PET/CT) is used for the evaluation of response to immunotherapy in malignant melanoma. Here, we evaluated the prognostic value of various metabolic parameters in baseline and different time points after therapy. METHODS: In this retrospective study, 51 metastatic melanoma patients, who had received immunotherapy, were included. Patients with baseline and two follow-up 2-[18F]FDG PET/CT studies (3 and 6 months after therapy) were selected. Multiple metabolic parameters and tumor-to-background ratios (TBRs) were extracted and correlated with OS. RESULTS: The 3- and 5-year OS rates were 49% and 43.1%, respectively. On baseline 2-[18F]FDG PET/CT, only standardized uptake value corrected for lean body mass (SULmax and SULpeak), as well as most of the TBRs were predictive for 3- and 5-year OS rates. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and most of the TBRs were predictive on both follow-up studies. Also, the changes in values of MTV, TLG and most of the TBRs from the baseline to the 3-month and 6- month follow-up studies were prognostic. On multivariate analysis, all of the most predictive parameters for OS were derived from the 3-month follow-up study. The ratio of TBRmean to the mediastinum was the best factor (cutoff value of 2.15, sensitivity of 88.5% and specificity of 68.0% for 3-year survival). CONCLUSION: Metabolic parameters derived from 2-[18F]FDG PET/CT are valuable tools for the prediction of 3- and 5-year OS rates in metastatic melanoma patients undergoing immunotherapy. The 3-month follow-up 2-[18F]FDG PET/CT is of particular importance in this regard.

Molecular Imaging in Primary Staging of Prostate Cancer Patients: Current Aspects and Future Trends.

Accurate primary staging is the cornerstone in all malignancies. Different morphological imaging modalities are employed in the evaluation of prostate cancer (PCa). Regardless of all developments in imaging, invasive histopathologic evaluation is still the standard method for the detection and staging of the primary PCa. Magnetic resonance imaging (MRI) and computed tomography (CT) play crucial roles; however, functional imaging provides additional valuable information, and it is gaining ever-growing acceptance in the management of PCa. Targeted imaging with different radiotracers has remarkably evolved in the past two decades. [111In]In-capromab pendetide scintigraphy was a new approach in the management of PCa. Afterwards, positron emission tomography (PET) tracers such as [11C/18F]choline and [11C]acetate were developed. Nevertheless, none found a role in the primary staging. By introduction of the highly sensitive small molecule prostate-specific membrane antigen (PSMA) PET/CT, as well as recent developments in MRI and hybrid PET/MRI systems, non-invasive staging of PCa is being contemplated. Several studies investigated the role of these sophisticated modalities in the primary staging of PCa, showing promising results. Here, we recapitulate the role of targeted functional imaging. We briefly mention the most popular radiotracers, their diagnostic accuracy in the primary staging of PCa, and impact on patient management.

Factors predicting biochemical response and survival benefits following radioligand therapy with [177Lu]Lu-PSMA in metastatic castrate-resistant prostate cancer: a review.

BACKGROUND: Prostate cancer (PC) is one of the most common cancers in men. Although the overall prognosis is favorable, the management of metastatic castration-resistant prostate cancer (mCRPC) patients is challenging. Usually, mCRPC patients with progressive disease are considered for radioligand therapy (RLT) after exhaustion of other standard treatments. The prostate-specific membrane antigen (PSMA) labeled with Lutetium-177 ([177Lu]Lu-PSMA) has been widely used, showing favorable and successful results in reducing prostate-specific antigen (PSA) levels, increasing quality of life, and decreasing pain, in a multitude of studies. Nevertheless, approximately thirty percent of patients do not respond to [177Lu]Lu-PSMA RLT. Here, we only reviewed and reported the evaluated factors and their impact on survival or biochemical response to treatment to have an overview of the potentialprognostic parameters in [177Lu]Lu-PSMA RLT. METHODS: Studies were retrieved by searching MEDLINE/PubMed and GoogleScholar. The search keywords were as follows: {("177Lu-PSMA") AND ("radioligand") AND ("prognosis") OR ("predict")}. Studies discussing one or more factors which may be prognostic or predictive of response to [177Lu]Lu-PSMA RLT, that is PSA response and survival parameters, were included. RESULTS: Several demographic, histological, biochemical, and imaging factors have been assessed as predictive parameters for the response to thistreatment; however, the evaluated factors were diverse, and the results mostly were divergent, except for the PSA level reduction after treatment, which unanimously predicted prolonged survival. CONCLUSION: Several studies have investigated a multitude of factors to detect those predicting response to [177Lu]Lu-PSMA RLT. The results wereinconsistent regarding some factors, and some were evaluated in only a few studies. Future prospective randomized trials are required to detect theindependent prognostic factors, and to further determine the clinical and survival benefits of [177Lu]Lu-PSMA RLT.

2-[18F]FDG PET/CT radiomics in lung cancer: An overview of the technical aspect and its emerging role in management of the disease.

Lung cancer is the most common cancer, worldwide, and a major health issue with a remarkable mortality rate. 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (2-[18F]FDG PET/CT) plays an indispensable role in the management of lung cancer patients. Long-established quantitative parameters such as size, density, and metabolic activity have been and are being employed in the current practice to enhance interpretation and improve diagnostic and prognostic value. The introduction of radiomics analysis revolutionized the quantitative evaluation of medical imaging, revealing data within images beyond visual interpretation. The "big data" are extracted from high-quality images and are converted into information that correlates to relevant genetic, pathologic, clinical, or prognostic features. Technically advanced, diverse methods have been implemented in different studies. The standardization of image acquisition, segmentation and features analysis is still a debated issue. Importantly, a body of features has been extracted and employed for diagnosis, staging, risk stratification, prognostication, and therapeutic response. 2-[18F]FDG PET/CT-derived features show promising value in non-invasively diagnosing the malignant nature of pulmonary nodules, differentiating lung cancer subtypes, and predicting response to different therapies as well as survival. In this review article, we aimed to provide an overview of the technical aspects used in radiomics analysis in non-small cell lung cancer (NSCLC) and elucidate the role of 2-[18F]FDG PET/CT-derived radiomics in the diagnosis, prognostication, and therapeutic response.

Targeted Palliative Radionuclide Therapy for Metastatic Bone Pain.

Bone metastasis develops in multiple malignancies with a wide range of incidence. The presence of multiple bone metastases, leading to a multitude of complications and poorer prognosis. The corresponding refractory bone pain is still a challenging issue managed through multidisciplinary approaches to enhance the quality of life. Radiopharmaceuticals are mainly used in the latest courses of the disease. Bone-pain palliation with easy-to-administer radionuclides offers advantages, including simultaneous treatment of multiple metastatic foci, the repeatability and also the combination with other therapies. Several ߯- and α-emitters as well as pharmaceuticals, from the very first [89Sr]strontium-dichloride to recently introduced [223Ra]radium-dichloride, are investigated to identify an optimum agent. In addition, the combination of bone-seeking radiopharmaceuticals with chemotherapy or radiotherapy has been employed to enhance the outcome. Radiopharmaceuticals demonstrate an acceptable response rate in pain relief. Nevertheless, survival benefits have been documented in only a limited number of studies. In this review, we provide an overview of bone-seeking radiopharmaceuticals used for bone-pain palliation, their effectiveness and toxicity, as well as the results of the combination with other therapies. Bone-pain palliation with radiopharmaceuticals has been employed for eight decades. However, there are still new aspects yet to be established.

Additional Value of 2-[18F]FDG PET/CT Comparing to MRI in Treatment Approach of Anal Cancer Patients.

Accurate staging and treatment planning are imperative for precise management in Anal Cancer (ACa) patients. We aimed to evaluate the additive and prognostic value of pre-treatment 2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (2-[18F]FDG PET/CT) in the staging and management of ACa compared to magnetic resonance imaging (MRI). This retrospective study was conducted on 54 patients. Pre-treatment 2-[18F]FDG PET/CT studies and MRI reports were compared considering the primary tumor, pelvic lymph nodes, and metastatic lesions. The impact of 2-[18F]FDG PET/CT in the management and its prognostic value, using maximum standardized uptake value (SUVmax), were assessed. Discordant findings were found in 46.3% of patients (5 in T; 1 in T and N; 18 in N; and 1 in M stage). 2-[18F]FDG PET/CT resulted in up-staging in 9.26% and down-staging in 3.7% of patients. Perirectal lymph nodes were metabolically inactive in 12.9% of patients. Moreover, 2-[18F]FDG PET/CT resulted in management change in 24.1% of patients. Finally, SUVmax provided no prognostic value. 2-[18F]FDG PET/CT altered staging and management in a sizable number of patients in this study, and supports a need for a change in guidelines for it to be used as a routine complementary test in the initial management of ACa.

Multiphasic 68Ga-PSMA PET/CT in the Detection of Early Recurrence in Prostate Cancer Patients with a PSA Level of Less Than 1 ng/mL: A Prospective Study of 135 Patients.

The main objective of this prospective study was to determine the impact of multiphasic acquisition of 68Ga-PSMA PET/CT in the detection of recurrent prostate cancer in the early stage of biochemical recurrence with a prostate-specific antigen (PSA) level of less than 1 ng/mL. Also, 68Ga-PSMA PET/CT positivity was correlated with clinical parameters for the assessment of predictive markers. Methods: A prospective monocentric study was conducted on 135 prostate cancer patients with biochemical recurrence and a PSA level of less than 1 ng/mL. All patients had undergone initial prostatectomy, with additional radiation therapy in 19.3% of patients and androgen-deprivation therapy in 7.4%. The patients underwent dynamic acquisitions from the prostate bed (1-8 min after injection), standard whole-body acquisitions (60 min after injection), and limited-bed-position delayed acquisitions (120-150 min after injection). The studies were reviewed by 2 board-certified nuclear medicine specialists, independently. A combination of visual and semiquantitative analyses and correlation with morphologic (e.g., MRI) or clinical follow-up findings was used for the final interpretation of lesions as benign or malignant. 68Ga-prostate-specific membrane antigen (PSMA) PET/CT positivity was also correlated with primary clinical findings. Results: Incorporating the information from all phases, we were able to detect 116 lesions in 49.6% of patients (22 local recurrences, 63 lymph nodes, and 31 distant metastases). The detection rates were 31.8%, 44.9%, and 71.4% for PSA < 0.2 ng/mL, 0.2 ≤ PSA < 0.5, and 0.5 ≤ PSA < 1, respectively. Additional dynamic or delayed phases resulted in better determination of equivocal lesions and a higher diagnostic performance in 25.9% of patients. Stand-alone dynamic and delayed images led to better interpretation of equivocal findings in the prostate bed (31.4%) and in other lesions (lymph node or bone) (20%), respectively. Conclusion:68Ga-PSMA PET/CT showed promise for early detection of recurrent disease in patients with a PSA level of 0.5-1.0 ng/mL. However, it showed limited value in patients with a PSA level of less than 0.5 ng/mL. Multiphasic 68Ga-PSMA PET/CT led to a better determination of equivocal findings. Although dynamic images may provide helpful information for assessment of the prostate bed, delayed acquisitions seem to have a greater impact in clarifying equivocal findings.

Diagnostic fficiency of 68Ga-DOTATATE PET/CT as ompared to 99mTc-Octreotide SPECT/CT andonventional orphologic odalities in euroendocrine umors.

OBJECTIVES: In view of somatostatin receptor (SSR) expression on cell membranes of the majority of neuroendocrine tumors (NETs), functional imaging exploiting analogs of SSR alongside the anatomical imaging is the mainstay of this diagnostic modality. In this prospective study, we assessed and directly compared the diagnostic parameters of 68Ga-DOTATATE PET/CT and 99mTc-Octreotide SPECT/CT, as well as CT/MRI. METHODS: Twenty-five NET patients, either histologically proven or highly suspicious for NET, who were referred for Octreotide Scan were enrolled in this prospective study. They all underwent 99mTc-Octreotide SPECT/CT and then 68Ga-DOTATATE PET/CT. A blind interpretation was conducted for each imaging as well as for the previously obtained conventional imaging (CT or MRI). The patient-based and lesion-based analysis were conducted and the results of the three modalities were compared. The histopathologic confirmation or follow-up data were considered as the gold standard. Also, the impact of 68Ga-DOTATATE PET/CT on the patient's management was assessed. RESULTS: Overall, 77 lesions in 14 patients, 135 in 19 and 86 in 16 were detected on 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. On patient-based analysis, the sensitivity was 65%, 90% and 71% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. Also, the specificity was 80%, 80% and 75% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. The correlation between 68Ga-DOTATATE PET/CT and 99mTc-Octreotide SPECT/CT results was significant (=0.02; kappa value=0.57), no correlation, however, was depicted with CI (=0.07; kappa value=0.35). On lesion-based analysis, 68Ga-DOTATATE PET/CT found more organs (=0.02) and lesions (=0.001) in comparison with 99mTc-Octreotide SPECT/CT and also more lesions in comparison with CT/MRI (=0.003). In addition, comparing with 99mTc-Octreotide SPECT/CT and CT/MRI, 68Ga-DOTATATE PET/CT revealed more data in 44% and 36% of the patients, resulting in management modification in 24% and 20%, respectively. CONCLUSION: Comparing with 99mTc-Octreotide SPECT/CT and CT/MRI, 68Ga-DOTATATE PET/CT provided more sensitivity and specificity in patients with NETs showing more involved organs as well as tumoral lesions. Also, 68Ga-DOTATATE PET/CT led to change of management in up to one-fourth of the patients, especially in a sub-group re-evaluated for recurrence.

Molecular imaging of bone metastases using tumor-targeted tracers.

Bone metastasis is a disastrous manifestation of most malignancies, especially in breast, prostate and lung cancers. Since asymptomatic bone metastases are not uncommon, early detection, precise assessment, and localization of them are very important. Various imaging modalities have been employed in the setting of diagnosis of bone metastasis, from plain radiography and bone scintigraphy to SPECT, SPECT/CT, PET/CT, MRI. However, each modality showed its own limitation providing accurate diagnostic performance. In this regard, various tumor-targeted radiotracers have been introduced for molecular imaging of bone metastases using modern hybrid modalities. In this article we review the strength of different cancer-specific radiopharmaceuticals in the detection of bone metastases. As shown in the literature, among various tumor-targeted tracers, 68Ga DOTA-conjugated-peptides, 68Ga PSMA, 18F DOPA, 18F galacto-RGD integrin, 18F FDG, 11C/18F acetate, 11C/18F choline, 111In octreotide, 123/131I MIBG, 99mTc MIBI, and 201Tl have acceptable capabilities in detecting bone metastases depending on the cancer type. However, different study designs and gold standards among reviewed articles should be taken into consideration.