Journal of nuclear medicine : official publication, Society of Nuclear Medicine最新文献

This analysis aimed to identify clinical factors associated with positivity on repeat ⁶⁸Ga-PSMA-11 PET/CT after a negative scan in patients with recurrent prostate cancer (PCa) under observation. Methods: This single-center, retrospective analysis included patients who underwent at least 2 ⁶⁸Ga-PSMA-11 PET/CT scans (PET1 and PET2) at UCLA between October 2016 and June 2021 for recurrent PCa with negative PET1 and no PCa-related treatments between the 2 scans. Using Prostate Cancer Molecular Imaging Standardized Evaluation criteria to define negative and positive scans, the final cohort was divided into PET2-negative (PET2-Neg) and PET2-positive (PET2-Pos). The same PET1 was used twice in the more than 2 PET cases with inclusion criteria fulfilled. Patient characteristics and clinical parameters were compared between the 2 cohorts using Mann-Whitney U test and Fisher exact test. Areas under the curve (AUCs) of the receiver operating characteristic and the Youden index were computed to determine the discrimination ability of statistically significant factors and specific cut points that maximized sensitivity and specificity, respectively. Results: The final analysis included 83 sets of 2 PET/CT scans from 70 patients. Thirty-nine of 83 (47%) sets were PET2-Neg, and 44 of 83 (53%) sets were PET2-Pos. Prostate-specific antigen (PSA) increased from PET1 to PET2 for all 83 (100%) sets of scans. Median PSA at PET1 was 0.4 ng/mL (interquartile range, 0.2-1.0) and at PET2 was 1.6 ng/mL (interquartile range, 0.9-3.8). We found higher serum PSA at PET2 (median, 1.8 vs. 1.1 ng/mL; P = 0.015), absolute PSA difference (median, 1.4 vs. 0.7 ng/mL; P = 0.006), percentage of PSA change (median, +270.4% vs. +150.0%: P = 0.031), and median PSA velocity (0.044 vs. 0.017 ng/mL/wk, P = 0.002) and shorter PSA doubling time (DT; median, 5.1 vs. 8.3 mo; P = 0.006) in the PET2-Pos cohort than in the PET2-Neg cohort. Receiver operating characteristic curves showed cutoffs for PSA at PET2 of 4.80 ng/mL (sensitivity, 34%; specificity, 92%; AUC, 0.66), absolute PSA difference of 0.95 ng/mL (sensitivity, 62%; specificity, 71%; AUC, 0.68), percentage of PSA change of a positive 289.50% (sensitivity, 48%; specificity, 82%; AUC, 0.64), PSA velocity of 0.033 ng/mL/wk (sensitivity, 57%; specificity, 80%; AUC, 0.70), and PSA DT of 7.91 mo (sensitivity, 71%; specificity, 62%; AUC, 0.67). Conclusion: Patients with recurrent PCa under observation after a negative ⁶⁸Ga-PSMA-11 PET/CT scan with markedly elevated serum PSA levels and shorter PSA DT are more likely to have positive findings on repeat ⁶⁸Ga-PSMA-11 PET/CT.

Cancer of unknown primary (CUP) represents a heterogeneous group of metastatic tumors for which standardized diagnostic work-up fails to identify the primary site. We aimed to describe the Peter MacCallum Cancer Centre experience with ¹⁸F-FDG PET/CT in extracervical CUP with respect to detection of a primary site and its impact on management. A secondary aim was to compare overall survival (OS) in patients with and without a detected primary site. Methods: CUP patients treated between 2014 and 2020 were identified from medical oncology clinics and ¹⁸F-FDG PET/CT records. Information collated from electronic medical records included the suspected primary site and treatment details before and after ¹⁸F-FDG PET/CT. Clinicopathologic details and genomic analysis were used to determine the clinically suspected primary site and compared against 2 independent masked reads of ¹⁸F-FDG PET/CT images by nuclear medicine specialists to determine sensitivity, specificity, accuracy, and the rate of detection of the primary site. Results: We identified 147 patients, 65% of whom had undergone molecular profiling. The median age at diagnosis was 61 y (range, 20-84 y), and the median follow-up time was 74 mo (range, 26-83 mo). Eighty-two percent were classified as having an unfavorable CUP subtype as per international guidelines.¹⁸F-FDG PET/CT demonstrated a primary site detection rate of 41%, resulted in a change in management in 22%, and identified previously occult disease sites in 37%. Median OS was 16.8 mo for all patients and 104.7 and 12.1 mo for favorable and unfavorable CUP subtypes, respectively (P < 0.0001). Median OS in CUP patients when using ¹⁸F-FDG PET/CT, clinicopathologic, and genomic information was 19.8 and 8.5 mo when a primary site was detected and not detected, respectively (P = 0.016). Multivariable analysis of survival adjusted for age and sex remained significant for identification of a potential primary site (P < 0.001), a favorable CUP (P < 0.001), and an Eastern Cooperative Oncology Group status of 1 or less (P < 0.001). Conclusion: ¹⁸F-FDG PET/CT plays a complementary role in CUP diagnostic work-up and was able to determine the likely primary site in 41% of cases. OS is improved with primary site identification, demonstrating the value of access to diagnostic ¹⁸F-FDG PET/CT for CUP patients.

Following early acceptance by urologists, the use of surgical robotic platforms is rapidly spreading to other surgical fields. This empowerment of surgical perception via robotic advances occurs in parallel to developments in intraoperative molecular imaging. Convergence of these efforts creates a logical incentive to advance the decades-old image-guided robotics paradigm. This yields new radioguided surgery strategies set to optimally exploit the symbiosis between the growing clinical translation of robotics and molecular imaging. These strategies intend to advance surgical precision by increasing dexterity and optimizing surgical decision-making. In this state-of-the-art review, topic-related developments in chemistry (tracer development) and engineering (medical device development) are discussed, and future scientific robotic growth markets for molecular imaging are presented.

Here we describe an anti-prostate-specific membrane antigen (PSMA) minibody (IAB2MA) conjugated to an octadentate, macrocyclic chelator based on four 1-hydroxypyridin-2-one coordinating units (Lumi804 [L804]) labeled with ⁸⁹Zr (PET imaging) and ¹⁷⁷Lu (radiopharmaceutical therapy), with the goal of developing safer and more efficacious treatment options for prostate cancer. Methods: L804 was compared with the current gold standard chelators, DOTA and deferoxamine (DFO), conjugated to IAB2MA for radiolabeling with ¹⁷⁷Lu and ⁸⁹Zr in cell binding, preclinical biodistribution, imaging, dosimetry, and efficacy studies in the PSMA-positive PC3-PIP tumor-bearing mouse model of prostate cancer. Results: Quantitative radiolabeling (>99% radiochemical yield) of L804-IAB2MA with ¹⁷⁷Lu or ⁸⁹Zr was achieved at ambient temperature in under 30 min, comparable to ⁸⁹Zr labeling of DFO-IAB2MA. In contrast, DOTA-IAB2MA was radiolabeled with ¹⁷⁷Lu for 30 min at 37°C in approximately 90% radiochemical yield, requiring further purification. Using europium(III) as a luminescent surrogate, high binding affinity of Eu-L804-IAB2MA to PSMA was demonstrated in PC3-PIP cells (dissociation constant, 4.6 ± 0.6 nM). All 4 radiolabeled constructs showed significantly higher levels of internalization after 30 min in the PC3-PIP cells than in PSMA-negative PC3-FLU cells. The accumulation of ¹⁷⁷Lu- and ⁸⁹Zr-L804-IAB2MA in PC3-PIP tumors and all organs examined (i.e., heart, liver, spleen, kidney, muscle, salivary glands, lacrimal glands, carcass, and bone) was significantly lower than that of ¹⁷⁷Lu-DOTA-IAB2MA and ⁸⁹Zr-DFO-IAB2MA at 96 and 72 h after injection, respectively. Generally, SPECT/CT and PET/CT imaging data showed no significant difference in the SUV_mean of the tumors or muscle between the radiotracers. Dosimetry analysis via both organ-level and voxel-level dose calculation methods indicated significantly higher absorbed doses of ¹⁷⁷Lu-DOTA-IAB2MA in tumors, kidney, liver, muscle, and spleen than of ¹⁷⁷Lu-L804-IAB2MA. PC3-PIP tumor-bearing mice treated with single doses of ¹⁷⁷Lu-L804-IAB2MA (18.4 or 22.2 MBq) exhibited significantly prolonged survival and reduced tumor volume compared with unlabeled minibody control. No significant difference in survival was observed between groups of mice treated with ¹⁷⁷Lu-L804-IAB2MA or ¹⁷⁷Lu-DOTA-IAB2MA (18.4 or 22.2 MBq). Treatment with ¹⁷⁷Lu-L804-IAB2MA resulted in lower absorbed doses in tumors and less toxicity than that of ¹⁷⁷Lu-DOTA-IAB2MA. Conclusion: ⁸⁹Zr- and ¹⁷⁷Lu-L804-IAB2MA may be a promising theranostic pair for imaging and therapy of prostate cancer.

Molecular imaging of muscle-invasive bladder cancer (MBC) is restricted to its locoregional and distant metastases, since most radiopharmaceuticals have a urinary excretion that limits the visualization of the primary tumor. ⁶⁴CuCl_{2 ,} a positron-emitting radiotracer with nearly exclusive biliary elimination, could be well suited to exploring urinary tract neoplasms. In this study, we evaluated the feasibility of ⁶⁴CuCl₂-based staging of patients with MBC; furthermore, we compared the diagnostic capability of this method with those of the current gold standards, that is, contrast-enhanced CT (ceCT) and ¹⁸F-FDG PET/CT. Methods: We prospectively enrolled patients referred to our institution for pathology-confirmed MBC staging/restaging between September 2021 and January 2023. All patients underwent ceCT, ¹⁸F-FDG, and ⁶⁴CuCl₂ PET/CT within 2 wk. Patient-based analysis and lesion-based analysis were performed for all of the potentially affected districts (overall, bladder wall, lymph nodes, skeleton, liver, lung, and pelvic soft tissue). Results: Forty-two patients (9 women) were enrolled. Thirty-six (86%) had evidence of disease, with a total of 353 disease sites. On patient-based analysis, ceCT and ⁶⁴CuCl₂ PET/CT showed higher sensitivity than ¹⁸F-FDG PET/CT in detecting the primary tumor (P < 0.001); moreover, ⁶⁴CuCl₂ PET/CT was slightly more sensitive than ¹⁸F-FDG PET/CT in disclosing soft-tissue lesions (P < 0.05). Both PET methods were more specific and accurate than ceCT in classifying nodal lesions (P < 0.05). On lesion-based analysis, ⁶⁴CuCl₂ PET/CT outperformed ¹⁸F-FDG PET/CT and ceCT in detecting disease localizations overall (P < 0.001), in the lymph nodes (P < 0.01), in the skeleton (P < 0.001), and in the soft tissue (P < 0.05). Conclusion: ⁶⁴CuCl₂ PET/CT appears to be a sensitive modality for staging/restaging of MBC and might represent a "one-stop shop" diagnostic method in these scenarios.

Immunotherapies, especially checkpoint inhibitors such as anti-programmed cell death protein 1 (anti-PD-1) antibodies, have transformed cancer treatment by enhancing the immune system's capability to target and kill cancer cells. However, predicting immunotherapy response remains challenging. ¹⁸F-arabinosyl guanine ([¹⁸F]F-AraG) is a molecular imaging tracer targeting activated T cells, which may facilitate therapy response assessment by noninvasive quantification of immune cell activity within the tumor microenvironment and elsewhere in the body. The aim of this study was to obtain preliminary data on total-body pharmacokinetics of [¹⁸F]F-AraG as a potential quantitative biomarker for immune response evaluation. Methods: The study consisted of 90-min total-body dynamic scans of 4 healthy subjects and 1 non-small cell lung cancer patient who was scanned before and after anti-PD-1 immunotherapy. Compartmental modeling with Akaike information criterion model selection was used to analyze tracer kinetics in various organs. Additionally, 7 subregions of the primary lung tumor and 4 mediastinal lymph nodes were analyzed. Practical identifiability analysis was performed to assess the reliability of kinetic parameter estimation. Correlations of the SUV_mean, the tissue-to-blood SUV ratio (SUVR), and the Logan plot slope (K _Logan) with the total volume of distribution (V _T) were calculated to identify potential surrogates for kinetic modeling. Results: Strong correlations were observed between K _Logan and SUVR with V _T, suggesting that they can be used as promising surrogates for V _T, especially in organs with a low blood-volume fraction. Moreover, practical identifiability analysis suggested that dynamic [¹⁸F]F-AraG PET scans could potentially be shortened to 60 min, while maintaining quantification accuracy for all organs of interest. The study suggests that although [¹⁸F]F-AraG SUV images can provide insights on immune cell distribution, kinetic modeling or graphical analysis methods may be required for accurate quantification of immune response after therapy. Although SUV_mean showed variable changes in different subregions of the tumor after therapy, the SUVR, K _Logan, and V _T showed consistent increasing trends in all analyzed subregions of the tumor with high practical identifiability. Conclusion: Our findings highlight the promise of [¹⁸F]F-AraG dynamic imaging as a noninvasive biomarker for quantifying the immune response to immunotherapy in cancer patients. Promising total-body kinetic modeling results also suggest potentially wider applications of the tracer in investigating the role of T cells in the immunopathogenesis of diseases.