Search

Objective(s): To compare the diagnostic performance of [68Ga]-Ga-FAPI-46 and [18F]-FDG PET/CT imaging for the detection of lesions and disease staging in breast cancer. Methods: Twelve female patients with breast cancer (mean age= 49.2±13.29 years) and previous [18F]-FDG PET/CT were recruited in the study. [68Ga]Ga-FAPI-46 imaging performed in all patients within one month after [18F]-FDG PET/CT imaging. The acquired PET/CT data with both tracers were reconstructed. Tracer avid lesions with each PET tracer were identified and the semi-quantitative parameters i.e. SUVmax, lesion counts and target-to-background ratio (TBRmax) were analyzed. Results: Physiologic distribution of [68Ga]-Ga-FAPI-46 was observed in the liver, blood pool and kidneys, whereas no tracer uptake was noted in the brain and heart. The mean liver SUVmax for [68Ga] Ga-FAPI-46 was 1.5±0.1 which was lower than that noted for [18F]-FDG PET/CT (2.9±0.2). Likewise, the mean blood pool SUVmax value for [68Ga]-Ga-FAPI-46 was lower than [18F]-FDG PET/CT (1.7±0.1 versus 2.0±0.1). [68Ga]-Ga-FAPI-46 PET/CT demonstrated higher tracer uptake in the lesions detected in the brain, bone, internal mammary and lymph nodes in 4/12 patients. The overall lesions detections and the mean SUVmax values did not differ significantly between the two techniques. On the other hand, [68Ga]-Ga-FAPI-46 demonstrated higher mean TBRmax than [18F] FDG PET/CT particularly for lesions detected in kidneys, chest wall, mediastinum, and musculoskeletal lesions. However, both techniques offered identical TNM staging. Conclusion: The findings of this preliminary study demonstrated that [68Ga]-Ga-FAPI-46 and [18F]-FDG PET/CT offered identical disease staging in the breast cancer patients. [68Ga]-Ga-FAPI-46 showed lower liver and blood pool uptake and an enhanced tumor-to-background ratio, thereby suggesting its potential for improved lesions detection. This may open opportunity for emerging FAP based radioligand for therapeutic applications in advanced stage breast cancers. However, this needs validation in a larger number of patients. [ABSTRACT FROM AUTHOR]

Introduction: Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) is revolutionizing the treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) patients. This study aimed to establish patient-specific radiation dosimetry for [177Lu]Lu-PSMA-617 RLT in Iranian patients with mCRPC. Method: Twelve biopsy-proven prostate cancer patients (aged 68.73 ± 5.26 yr) underwent 6.62 ± 0.36 GBq [177Lu]Lu-PSMA-617 RLT. Post-therapy whole-body planar scans were acquired approximately at 4, 48, and 72 h post-administration, alongside a single SPECT/CT around 48 h using Siemens Symbia T2 to obtain cumulated activity. An imaging protocol and dosimetry approach were designed to balance between time efficacy and accuracy in post-therapeutic dosimetry. Using accurate activity calibration, S-values were calculated by importing SPECT/CT images as the source/geometry into the Geant4 application for the tomographic emission (GATE) Monte Carlo (MC) toolkit. The Medical Internal Radiation Dose (MIRD) scheme was followed for subsequent absorbed dose (AD) calculations in organs at risk (OAR) and tumoral lesions using the dose actor and accumulated activities for precise dose estimations. Results: Using the MC approach, the mean ADs to the liver, spleen, right and left kidneys, and tumor lesions were 0.11 ± 0.04 Gy/GBq, 0.08 ± 0.03 Gy/GBq, 0.34 ± 0.09 Gy/GBq, 0.34 ± 0.10 Gy/GBq, and 0.83 ± 0.54 Gy/GBq, respectively. Notably, tumoral lesions demonstrated significantly higher ADs, indicating enhanced uptake of radiopharmaceuticals by malignant cells. Conclusions: This study indicates that the ADs of OARs and tumoral lesions from [177Lu]Lu-PSMA-617 RLT in patients with mCRPC are consistent with existing literature. The dosimetry findings suggest that increasing the administered activity of [177Lu]Lu-PSMA-617 RLT is feasible and does not pose a significant risk of adverse effects on OARs, as supported by our data. However, to validate the safety and efficacy of higher doses, further clinical follow-up studies are recommended. [ABSTRACT FROM AUTHOR]

Introduction: Large Vessel Vasculitis (LVV) is a chronic inflammatory process that affects the aorta and its main branches. LVV include Takayasu's Arteritis (TA) and Giant Cell Arteritis (GCA). The diagnosis of TA is made according to clinical criteria and based on the criteria of the American College of Rheumatology (ACR). Monitoring of disease progression and response to treatment is also done using the National Institutes of Health (NIH) criteria. Despite these criteria, diagnosing and evaluating TA activity is a challenging issue and usually occurs in the advanced stages of the disease. The lack of a comprehensive and non-invasive diagnostic method for diagnosing and monitoring the course of TA is obvious. The aim of this study was to evaluate the diagnostic agreement between 2- [18F]FDG PET-CT scan and clinical criteria for assessing TA disease activity. Methods: Twenty-four known cases of TA, who met the inclusion criteria, were enrolled in this study. The disease-related constitutional signs and symptoms, as well as laboratory and imaging findings were recorded. Patients underwent 2-[18F]FDG PETCT imaging with standard protocol. Fused PET-CT images were reviewed and, if necessary, images without attenuation correction were visualized as well. Also, 24 control patients of the same age and sex, among the patients who were referred to the imaging center for oncological indications were examined to compare the uptake of different vascular territories. Results: Out of 15 active patients (according to the NIH criteria), 2-[18F]FDG PET-CT scan was able to correctly identify 14 patients. Also, out of 9 inactive patients, PET scan was negative in eight patients showing that 2-[18F]FDG PET-CT scan could well differentiate between active and inactive status of the disease (p-value < 0.0001). Sensitivity, specificity, positive predictive value and negative predictive value of scan in this study were 93.3%, 88.9%, 93.3% and 88.9%, respectively. The study also showed that the severity of vascular lesion uptake was not affected by immunosuppressive drugs, including corticosteroids and methotrexate. Scan findings were comparable with the results of anatomical imaging in terms of disease activity and the number of vascular lesions with p-value = 0.1 and 0.304, respectively. Conclusion: In this study we showed that 2-[18F]FDG PET-CT has comparable results with other imaging modalities and NIH criteria; therefore, it can play an important role in assessing the severity of TA, even when patients are on immunosuppressive drugs. [ABSTRACT FROM AUTHOR]

Introduction: 2-[18F]fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (2-[18F]FDG-PET/CT) is implemented in papillary thyroid cancer (PTC) patients with elevated Thyroglobulin (Tg) and negative Iodine-131 wholebody scan (131I-WBS). Here, we evaluated the impact of TSH stimulation after levothyroxine withdrawal on the detection rate of 2-[18F]FDG-PET/CT. Methods: A prospective study was performed on 60 PTC patients, presented with negative 131I-WBS and elevated or unjustifiably high Tg. 2-[18F]FDG-PET/CT was performed in 30 patients while they were on levothyroxine therapy (unstimulated-TSH [uns-TSH]) and after Levothyroxine withdrawal in the other 30 patients (stimulated-TSH [s-TSH]). Results of the two groups were compared using nonparametric tests. Receiver operating characteristic curve was used to find Tg cutoff values for predicting positive scan results. Results: Overall, 2-[18F]FDG-PET/CT was positive in 63.3% of the patients, 80% (24/30) in s-TSH and 46.7% (14/30) in uns-TSH group. The detection rate was higher in s-TSH group (p=0.007). It was still significant in multiple regression analysis (p=0.041). In uns-TSH group, 2-[18F]FDG-PET/CT was more often positive in patients with higher uns-Tg level (p=0.002). An uns-Tg level of =19.00 ng/mL predicted positive results with the sensitivity of 0.786 and specificity of 0.750 (area under curve=0.819). Although statistically insignificant (p=0.055), s-Tg was higher in patients with positive 2-[18F]FDG-PET/CT studies in the s-TSH group. No relation was demonstrated between TSH and anti-Tg-antibody levels and 2-[18F]FDG-PET/CT positivity. Conclusion: TSH-stimulation after levothyroxine withdrawal might enhance the detection rate of 2-[18F]FDG-PET/CT in PTC patients. Additionally, 2-[18F]FDG-PET/CT is more often positive in patients with higher Tg levels. [ABSTRACT FROM AUTHOR]

Primary cardiac osteosarcoma is a very rare malignancy with a high incidence of local recurrence and systemic metastasis, contributing to the poor prognosis. Radiological modalities are commonly used for the evaluation of cardiac masses. 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography/computed tomography is a valuable whole-body imaging modality in the evaluation of most subtypes of sarcomas. The value of [18F]FDG PET/CT is not well-established in primary cardiac osteosarcoma, and it has rarely been documented in the literature. Here, we report the findings of [18F]FDG PET/CT in a case of a 38-year-old man with primary cardiac osteosarcoma, which clearly demonstrates the recurrent lesions in the myocardium. [ABSTRACT FROM AUTHOR]

Objective(s): Prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography (PET/CT) is an emerging modality to detect metastatic disease in patients with prostate cancer (PCa). This prospective study aimed to evaluate the role of [68Ga]-PSMA PET/CT in the initial workup of intermediate and high-risk PCa . Methods: Twenty-five patients with newly transrectal ultrasound biopsy-proven, untreated intermediate- and high-risk PCa (mean age, 68.5±6.2 years; range 55–83 years) were enrolled in this prospective study between September 2018 and June 2020 and underwent a [68Ga]-PSMA PET/CT examination. All images were analyzed both visually and semiquantitatively by measuring the maximum standardized uptake value (SUVmax) of the primary prostatic tumor and metastatic lesions. The diagnostic sensitivity of [68Ga]-PSMA PET/CT for the diagnosis of PCa was established by histopathology as the reference standard. The associations between SUVmax of the primary tumors and prostate-specific antigen (PSA) levels, Gleason scores (GSs), and metastatic extent of the disease were studied. Results: All patients had a positive [68Ga]-PSMA PET/CT exam. Seventeen patients (58%) showed [68Ga]-PSMA avidity in both prostate lobes and 8 (32%) had unilateral uptake. SUVmax in the primary tumor significantly correlated with serum PSA values (r=0.57, P=0.003). PSMA PET/CT depicted regional lymph node metastases in 32% of patients, distant lymph node metastases in 20%, osseous metastases in 16% and pulmonary metastases in 8% of patients. Sixty percent of PSMA-positive bone metastases and 21.4% of intraprostatic tumoral lesions were missed on the contemporaneous bone scintigraphy and magnetic resonance imaging, respectively. Conclusion: [68Ga]-PSMA PET/CT shows promise as a valuable imaging modality with high diagnostic sensitivity in the setting of intermediate and high-risk PCa. Moreover, the SUVmax of the primary tumor has a positive correlation with PSA levels at the time of the scan. [ABSTRACT FROM AUTHOR]

Management of locally advanced colon cancer metastases is challenging and operation carries an increased risk of morbidity and mortality. The knowledge of exact sites of involvement can aid the surgeon to make a decision regarding complete resection or palliative therapy. PET/CT scan is an advantage in this setting because metabolic alterations often precede the anatomic changes; moreover, it can show unexpected metastases. In addition, PET/CT scan can differentiate adhesions and scar from local invasion of tumor. We report a rare case of locally advanced colon cancer metastases to mesentery with extension to liver, chest wall and mediastinum depicted on PET/CT scan. The patient was treated with resection of the involved sites. The pathology report confirmed a poorly differentiated adenocarcinoma mainly involving the mesentery with extension to surrounding organs including the liver. Unfortunately, the patient's condition deteriorated following surgical intervention. Although there is a trend toward complete resection of primary tumor and involved sites in patients with metastatic colon carcinoma to improve overall patient survival by eliminating any residual disease, in more advanced stages of the disease, palliative therapy might be the preferred approach. PET/CT has invaluable complimentary role to improve surgical planning in advanced oncological situations. [ABSTRACT FROM AUTHOR]

Background: Thyroid cancer patients need to be followed up for life. However, the long course of the disease sometimes makes patients to not follow up regularly and face with complications and recurrence of the disease. Having a self-care mobile application with telemedicine services can play an important role in improving patient follow-up, increasing survival and patient satisfaction. Objectives: Our goal is to design a self-care cellphone application with the ability to consult a doctor, as well as artificial intelligence (AI) based patient's prognosis using the data collected in the application. Material and Methods: The application was designed using Django web framework in python programming language. American Thyroid Association (ATA) guidelines were used for defining the algorithms. The Delphi method including ten nuclear medicine specialists was used to determine the application pitfalls. A pilot was performed to assess the limitations according to the patients' opinions. Patients are followed up by the application and data will be used for (AI) based patient's prognosis. Results: The application was designed in two versions: patient version and physician version including AI assistant; Patients can ask pre/post treatment questions and upload the medical documents, while ATA algorithms, direct physician consult with AI prognosis and alarms in the follow up will help. Conclusion: The ATA+ AI based application warns the patient to start/ stop the proposed treatments and necessary lab tests. Physicians can observe the patients' questions, medical records and estimate the prognosis of patients using AI. [ABSTRACT FROM AUTHOR]

Objectives: 68 Ga-DOTATATE positron emission tomography (PET)/computed tomography (CT) has shown promising results in imaging of neural crest tumors (NCT). Herein, we compared the performance of 68 Ga-DOTATATE PET/CT and 131 I-MIBG single photon emission computed tomography (SPECT)/CT in the initial diagnosis, staging and follow-up of patients with NCTs., Methods: Twenty-five patients (males:females=8:17; age range=2-71 years) with clinically proven or suspicious neuroblastoma, pheochromocytoma (PCC) or paraganglioma (PGL) were enrolled in this prospective study and underwent both 68 Ga-DOTATATE PET/CT and 131 I-MIBG SPECT/CT. A composite reference standard derived from histopathological information, together with anatomical and functional imaging findings, was used to validate the results. Imaging findings were assessed on a per-patient and on a per-lesion basis. Sensitivity and accuracy were assessed using McNemar's test., Results: Referring to radiological imaging and histopathological findings as reference standard, 68 Ga-DOTATATE and 131 I-MIBG scans showed a sensitivity and accuracy of (100%, 96%) and (86.7%, 88%), respectively, on a per-patient basis. In PCC/PGL patients, on a per-patient basis, the sensitivity of 68 Ga-DOTATATE was 100% and that of 131 I-MIBG was 77.8%. In neuroblastoma patients, on a per-patient basis, the sensitivities of both 68 Ga-DOTATATE and 131 I-MIBG were 100%. Overall, in this patient cohort, 68 Ga-DOTATATE PET/CT identified 52 lesions and 131 I-MIBG SPECT/CT identified only 30 lesions. On a per-lesion analysis, 68 Ga-DOTATATE was found to be superior to 131 I-MIBG in detecting lesions in all anatomical locations, particularly osseous lesions. According to the McNemar test results, differences were not statistically significant., Conclusion: This relatively small patient cohort suggests 68 Ga-DOTATATE PET/CT be superior to 131 I-MIBG SPECT/CT in providing particularly valuable information for both primary staging and follow-up in patients with NCT., (© 2020 mums.ac.ir All rights reserved.)