Search

This review focuses on the pivotal role of radiotracers in breast cancer imaging, emphasizing their importance in accurate detection, staging, and treatment monitoring. Radiotracers, labeled with radioactive isotopes, are integral to various nuclear imaging techniques, including positron emission tomography (PET) and positron emission mammography (PEM). The most widely used radiotracer in breast cancer imaging is 18F-fluorodeoxyglucose (18F-FDG), which highlights areas of increased glucose metabolism, a hallmark of many cancer cells. This allows for the identification of primary tumors and metastatic sites and the assessment of tumor response to therapy. In addition to 18F-FDG, this review will explore newer radiotracers targeting specific receptors, such as estrogen receptors or HER2, which offer more personalized imaging options. These tracers provide valuable insights into the molecular characteristics of tumors, aiding in tailored treatment strategies. By integrating radiotracers into breast cancer management, clinicians can enhance early disease detection, monitor therapeutic efficacy, and guide interventions, ultimately improving patient outcomes. Ongoing research aimed at developing more specific and sensitive tracers will also be highlighted, underscoring their potential to advance precision medicine in breast cancer care. [ABSTRACT FROM AUTHOR]

Introduction This study aims to evaluate the correlation between serum PSA levels and Gleason score of prostate tumors with the findings of Ga68-PSMA PET/CT scans in primary staging. Methods In this cross-sectional study, patients with newly diagnosed prostate cancer referred for Ga68-PSMA PET/CT whole-body scans were enrolled. The scans were performed at three time points (early, whole-body, and late). The standardized uptake value of Ga68-PSMA in the primary tumor and its association with serum PSA levels, tumor Gleason score, and presence of tumor metastasis were evaluated and analyzed. A P-value<0.05 was considered statistically significant in all statistical analyses. Results A total of 49 male patients with a median age of 65 years (Interquartile range: 59-69) were included in the study. Of these patients, 43.9% were classified as high-risk based on their Gleason score. The median serum PSA level was 17 ng/mL (Interquartile range: 8.02-42.10). PSA levels correlated with the SUVmax of the tumor in the whole-body stage of the scan (P-value<0.05; r=+0.392), but not in the early or late stages (P-value>0.05). Gleason scores showed a positive correlation with tumor SUVmax in all three scan stages (P-value<0.05). Conclusions Our results indicate that the Gleason score significantly correlates with the SUVmax of the prostate tumor in all three time points of the scan. However, serum PSA levels only correlate with the tumor SUVmax in the whole-body stage of the scan, not in the early and late stages. In the whole-body stage, a higher SUVmax is significantly associated with higher Gleason scores, bladder wall and seminal vesicle invasion, and lymph node metastasis (P-value<0.05 in all cases). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: Image artefacts continue to pose challenges in clinical molecular imaging, resulting in misdiagnoses, additional radiation doses to patients and financial costs. Mismatch and halo artefacts occur frequently in gallium-68 (68Ga)-labelled compounds whole-body PET/CT imaging. Correcting for these artefacts is not straightforward and requires algorithmic developments, given that conventional techniques have failed to address them adequately. In the current study, we employed differential privacy-preserving federated transfer learning (FTL) to manage clinical data sharing and tackle privacy issues for building centre-specific models that detect and correct artefacts present in PET images. Methods: Altogether, 1413 patients with 68Ga prostate-specific membrane antigen (PSMA)/DOTA-TATE (TOC) PET/CT scans from 3 countries, including 8 different centres, were enrolled in this study. CT-based attenuation and scatter correction (CT-ASC) was used in all centres for quantitative PET reconstruction. Prior to model training, an experienced nuclear medicine physician reviewed all images to ensure the use of high-quality, artefact-free PET images (421 patients' images). A deep neural network (modified U2Net) was trained on 80% of the artefact-free PET images to utilize centre-based (CeBa), centralized (CeZe) and the proposed differential privacy FTL frameworks. Quantitative analysis was performed in 20% of the clean data (with no artefacts) in each centre. A panel of two nuclear medicine physicians conducted qualitative assessment of image quality, diagnostic confidence and image artefacts in 128 patients with artefacts (256 images for CT-ASC and FTL-ASC). Results: The three approaches investigated in this study for 68Ga-PET imaging (CeBa, CeZe and FTL) resulted in a mean absolute error (MAE) of 0.42 ± 0.21 (CI 95%: 0.38 to 0.47), 0.32 ± 0.23 (CI 95%: 0.27 to 0.37) and 0.28 ± 0.15 (CI 95%: 0.25 to 0.31), respectively. Statistical analysis using the Wilcoxon test revealed significant differences between the three approaches, with FTL outperforming CeBa and CeZe (p-value < 0.05) in the clean test set. The qualitative assessment demonstrated that FTL-ASC significantly improved image quality and diagnostic confidence and decreased image artefacts, compared to CT-ASC in 68Ga-PET imaging. In addition, mismatch and halo artefacts were successfully detected and disentangled in the chest, abdomen and pelvic regions in 68Ga-PET imaging. Conclusion: The proposed approach benefits from using large datasets from multiple centres while preserving patient privacy. Qualitative assessment by nuclear medicine physicians showed that the proposed model correctly addressed two main challenging artefacts in 68Ga-PET imaging. This technique could be integrated in the clinic for 68Ga-PET imaging artefact detection and disentanglement using multicentric heterogeneous datasets. [ABSTRACT FROM AUTHOR]

Background An accurate monitoring technique is crucial in brain tumors to choose the best treatment approach after surgery and/or chemoradiation. Radiological assessment of brain tumors is widely based on the magnetic resonance imaging (MRI) modality in this regard; however, MRI criteria are unable to precisely differentiate tumoral tissue from treatment-related changes. This study was conducted to evaluate whether fused MRI and O-(2- 18 F-fluoroethyl)-L-tyrosine (18 F-FET) positron emission tomography (PET) can improve the diagnostic accuracy of the practitioners to discriminate treatment-related changes from true recurrence of brain tumor. Methods We retrospectively analyzed 18 F-FET PET/computed tomography (CT) of 11 patients with histopathologically proven brain tumors that were suspicious for recurrence changes after 3 to 4 months of surgery. All the patients underwent MRI and 18 F-FET PET/CT. As a third assessment, fused 18 F-FET PET/MRI was also acquired. Finally, the diagnostic accuracy of the applied modalities was compared. Results Eleven patients aged 27 to 73 years with a mean age of 47 ± 13 years were enrolled. According to the results, 9/11 cases (82%) showed positive MRI and 6 cases (55%) showed positive PET/CT and PET/MRI. Tumoral recurrence was observed in six patients (55%) in the follow-up period. Based on the follow-up results, accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 64, 85, 25, 67, and 50%, respectively, for MRI alone and 91, 85, 100, 100, and 80%, respectively, for both PET/CT and PET/MRI. Conclusion This study found that 18 F-FET PET-MR image fusion in the management of brain tumors might improve recurrence detection; however, further well-designed studies are needed to verify these preliminary data. [ABSTRACT FROM AUTHOR]

[68Ga]Ga-PSMA-11 PET/CT scan is an important whole-body imaging tool in oncology and is specifically used for staging and re-staging of prostate cancer, in recent years. Findings of significant focal accumulation of PSMA in the lung parenchyma without corresponding CT abnormalities are challenging and may be a cause for false positive interpretation of metastasis, caused by pulmonary microembolism due to hot-clot artifacts, as previously described in 2-[18F]FDG PET/CT studies. Here we present an unusual case of focal PSMA uptake in lung parenchyma without structural lesions on CT scan, which we believe is due to hot clot because of faulty injection techniques. [ABSTRACT FROM AUTHOR]

Background This study was conducted to evaluate the clinical efficacy and safety of peptide receptor radionuclide therapy (PRRT) using 177 Lu-DOTA0-Tyr3-octreotate (DOTATATE) in patients with neuroendocrine tumors (NETs). Methods Sixteen patients with pathologically verified NETs including eight females and eight males were enrolled in this study. Before PRRT, the patients underwent 68 Ga-DOTATATE positron emission tomography/computed tomography or 99m Tc-octreotide scintigraphy for evaluation of somatostatin receptor expression. Response to treatment was assessed according to the Response Evaluation Criteria In Solid Tumors (RECIST) classified as complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD). In addition, for evaluation of toxicity, monthly blood analysis was performed including hematology, renal function (creatinine) test, and liver function test. The Eastern Cooperative Oncology Group (ECOG) status performance was applied to estimate the patients' general condition in a scale of 0 (fully active) to 5 (dead). In addition, overall survival (OS) was calculated as the time interval from the start of PRRT to death from any reason. Results Sixteen patients including eight females and eight males with a median age of 60.5 years (range: 24–74) were enrolled in this study. The patients underwent PRRT with a median cycle of 3.5 (range: 1–7) and a median dose of 20.35 (range: 7.4–49.95 GBq). At the end of data collection, PR, CR, SD, and PD were seen in 11, 2, 1, and 2 patients according to the RECIST, respectively. Three patients expired during or after the PRRT period. The median ECOG and Karnofsky Performance Scale was 1.5 and 75 before PRRT, which improved significantly to 1 and 80 after PRRT, respectively (p < 0.05). According to the Kaplan–Meier test, the median OS was 23 months (95% confidence interval: 7.90–38.09). According to the National Cancer Institute's Common Terminology Criteria for Adverse Events, three patients showed grade I and three patients showed grade II leucopenia. Furthermore, three and seven patients had grade II and grade I anemia, respectively. Conclusion Since PRRT using 177 Lu-DOTATATE has a favorable response rate and few adverse effects and improves the quality of life in NETs, it can be used as an effective therapeutic option, especially in nonoperative, metastatic, and progressive NETs. [ABSTRACT FROM AUTHOR]

Bone is a common metastasis site in several malignancies, most importantly prostate and breast cancers. Given the significance of the early and accurate diagnosis of bone metastases for preliminary staging, treatment planning and monitoring, restaging, and survival prediction in patients with malignancy, it is critical to compare and contrast the strengths and weaknesses of imaging modalities. Although technetium-99m-labeled diphosphonates [ 99m Tc-MDP] scintigraphy has been used for assessing skeletal involvement, there is a renewed interest in fluorine-18-labeled sodium fluoride [ 18 F-NaF] bone imaging with positron emission tomography or positron emission tomography/computed tomography, since this approach provides essential advantages in bone metastases evaluation. This review study aimed to discuss the basic and technical aspects of 18 F-NaF imaging and its mechanism of action, and compare this modality with the 99m Tc-MDP bone scan and 18F-fluorodeoxyglucose using current evidence from the pertinent literature and case examples of the center in the study. [ABSTRACT FROM AUTHOR]

Objective(s): The purpose of this study was to investigate regional cerebral blood flow (rCBF) reduction in patients with dizziness and perfusion-related clinical impairment using brain perfusion single photon emission tomography (SPECT). Methods: Thirty-four patients with subjective dizziness and 13 age- and sexmatched healthy controls were studied. Dizziness-related impairments were assessed using the Dizziness Handicap Inventory (DHI) and Short Physical Performance Battery (SPPB). Brain perfusion SPECT scan was acquired from all participants. The carotid intima-media thickness (CIMT) was also measured. Brain perfusion data were qualitatively interpreted in all cases. Voxel-wise analysis was also conducted in 11 patients compared to healthy controls. Results: Thirty-four patients (mean age=53.8±13.4 years, m/f: 19/15) and 13 ageand sex-matched controls (mean age=51.5±13.1, m/f: 7/6) were included. The dizziness severity was mild in 58.8% (n=20), moderate in 26.5% (n=9), and severe in 14.7% (n=5). Qualitative interpretation of SPECT images showed normal scans in 4 (11.2%) patients and abnormal scans in 30 (88.2%) patients. Patients with dizziness showed a significantly decreased brain perfusion in the precuneus, cuneus, occipital lobe (superior and inferior parts), frontal lobe (inferior and middle parts), temporal lobe, parietal lobe (inferior and superior parts), cerebellum, insula, and putamen nucleus. Based on both qualitative SPECT interpretation and voxel-wise analysis, perfusion defect had a significant association with the total SPPB score and the scores of two sub-domains (p<0.05), but not with the DHI (p>0.05) score . Conclusion: The perfusion- and atherosclerosis-related impairments of gait and balance were largely independent of subjective dizziness and dizziness severity. Moreover, this study provided support for contribution of perfusion impairment to the disturbance of gait and balance in older populations along with other pathologic processes. [ABSTRACT FROM AUTHOR]

Purpose: The early and accurate diagnosis of locoregional recurrence or metastasis in prostate cancer (PC) has a significant impact on treatment options. Prostatic-specific membrane antigen (PSMA) positron emission tomography (PET)/x-ray computed tomograph (CT) imaging has recently been introduced as a novel procedure in managing PC. The aim of this study was to evaluate the efficacy of [68Ga]PSMA PET/CT in managing PC patients and to compare the detection rate of PET/CT and bone scans (BSs) in detecting bone metastasis.Procedures: We evaluated 415 patients with PC who underwent [68Ga]PSMA PET/CT between March 2015 and September 2018. The patients were classified into three groups: staging, biomedical recurrence (BCR), and follow-up or monitoring, based on the intent to perform PET/CT.Results: We evaluated 415 patients aged 41-99 (68.25 ± 9.59). Of these patients, 344 (82.9 %) had at least one localized lesion. The detection rates were 48.3 %, 52.6 %, 74.4 %, 79.6 %, and 93.9 % for a PSA value of < 0.2 ng/ml, ≥ 0.2-< 0.5 ng/ml, ≥ 0.5-< 1 ng/ml, ≥ 1-< 2 ng/ml, and ≥ 2 ng/ml, respectively (p < 0.05). The detection rates increased significantly with higher GSs; the rates were 68.3 % (28/41), 74.5 % (73/98), 93.9 % (46/49), and 91 % (61/67) for a GS of < 7, 7, 8, and > 8, respectively (p < 0.05). An ideal cut-off value of > 1.16 ng/ml was obtained for PSA value, which equates to specificity of 75 % and sensitivity of 77 %. In comparing BSs and PET/CT, a region-based analysis showed the superiority of PET/CT over BSs for all regions expect the skull (p < 0.05). PET/CT detected 258 suspicious regions, 255 of which were metastatic and three of which were equivocal. BSs detected only 223 suspicious regions, 203 of which were metastatic and 20 of which were equivocal.Conclusions: [68Ga]PSMA PET/CT showed a high detection rate for lesions in PC patients. PSA level, GS, and a PSA doubling time of less than 6 months were shown to be the affective variables. In addition, 68Ga-PSMA PET/CT showed better performance in detecting bone lesions than BSs. [ABSTRACT FROM AUTHOR]