Tumor Microenvironment Features as Predictive Biomarkers in Metastatic Differentiated Thyroid Cancer and Their Relationship With 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F-FDG PET/CT) Metabolic Parameters.

OBJECTIVE: The role of the tumor microenvironment in tumor progression and treatment response is being investigated for different types of cancer. This study aimed to determine the relationships between tumor microenvironment, histopathology, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT)-based metabolic parameters, treatment response, and overall survival (OS) in metastatic differentiated thyroid cancer (DTC).  Methods: Metastatic DTC patients who underwent 18F-FDG PET/CT between 2015-2019 were evaluated. Clinicopathological, histopathological features and PET/CT parameters of patients were recorded. Microenvironmental characteristics of the primary tumor, such as mitosis, intratumoral and peritumoral lymphocytosis, intratumoral and peritumoral fibrosis, were evaluated from the tissue samples. The relationships between these factors were statistically analyzed. RESULTS:  Sixty-five patients (38 females, 27 males, age: 49±15 years) were included. Mitosis, intra/peritumoral lymphocytosis, and intra/peritumoral fibrosis were frequent; however, none of them had a statistically significant association with PET-positive metastases, treatment response, or OS. Univariate analysis showed that gender, size, thyroglobulin values, residual thyroid tissue, PET-positive metastases, and maximum standardized uptake value (SUVmax) were significant predictors of OS. At multivariate analysis, PET-positive metastases (HR=-2.65, 95%CI 0.007-0.707, p=0.024) and SUVmax (HR=-2.74, 95%CI 0.006-0.687, p=0.023) were the only independent predictors for OS.  Conclusion: Our study revealed that microenvironmental characteristics of the primary tumor did not show prognostic significance in metastatic DTC. PET-positive metastases and SUVmax levels were the only significant factors that predicted overall survival in DTC. Supporting the results of our study with further studies with a larger sample size may be necessary to determine the relationship between the tumor microenvironment and prognosis in DTC.

Contribution of Metabolic Parameters and Pericolic Fat Stranding on Preoperative 18F-FDG PET/CT in Predicting Post-operative Histopathology and Outcome in Colorectal Cancer.

Purpose: We aimed to investigate the additional value of preoperative PET/CT and reveal relationships between metabolic parameters, pericolic fat stranding finding, postoperative histopathology, and overall survival in colorectal cancer (CRC). Methods: CRC patients who underwent preoperative PET/CT between January 2017-December 2021 were analyzed. Lymph nodes, organ metastases, and metabolic parameters were evaluated from PET/CT. The pericolic fat stranding was evaluated from CT component. Relationships between these factors and postoperative histopathological findings were statistically analyzed. Survival analyses were performed. Results: Ninety-one patients (59 males, 32 females) were included in the study. All tumors showed high FDG uptake (mean SUVmax 19.5 ± 9.9). SUVmax of the tumor differed significantly at T3 and T4 stages (p = 0.041). A significant correlation was found between MTV, TLG values and the differentiation degree (p = 0.005, 0.003, respectively). PET/CT predicted the N stage with a high accuracy rate (80%). PET/CT found additional metastases that changed treatment decisions in one-third of patients. A relationship was found between tumor length, surgical margin, lymphovascular invasion and pericolic fat stranding. In multivariate analysis, differentiation degree (HR = 26.1, 95%CI 1.672-408.467), MTV (HR = 0.3, 95%CI 0.071-0.841), TLG (HR = 3.5, 95%CI 1.065-11.193), and lymphovascular invasion (HR = 0.2, 95%CI 0.026-0.853, p = 0.033) were independent factors affecting overall survival. Conclusion: Preoperative PET/CT contributes to CRC management by detecting additional metastases as well as predicting prognosis and postoperative findings such as T stage, N stage and tumor differentiation. The SUVmax may differentiate between T3 and T4 tumor. Reporting of pericolic fat stranding may contribute to the estimation of lymphatic invasion and positive surgical margin.

Assessment of three different radioiodine doses for ablation therapy of thyroid remnants: Efficiency, complications and patient comfort.

I-131 radioiodine (RAI) ablation removes postoperative residual tissue and facilitates follow-up in low- and intermediate-risk differentiated thyroid cancer (DTC). Although low doses have been reported to be as effective as higher doses for ablation, the doses administered still vary depending on the patient and the practitioner. We aimed to evaluate the ablation efficiency, complications, and length of stay (LOS) of patients with DTC treated with 3 different doses for ablation. Patients with DTC who received RAI therapy were retrospectively reviewed. One hundred thirty patients with low-intermediate-risk, according to American Thyroid Association classification, without known lymph nodes or distant metastases were included. Patients were divided into 3 groups as 30 to 50 mCi, 75 mCi, and 100 mCi. Residue thyroid and salivary glands were evaluated from 9 to 12 months post-RAI I-131 scans. No significant difference was found between groups regarding ablation success (P = .795). In multivariable analyses, pretreatment thyroglobulin (hazard ratio = 0.8, 95% confidence interval 0.601-0.952, P = .017) and anti- thyroglobulin antibody (hazard ratio = 1.0, 95% confidence interval 0.967-0.998, P = .024) were 2 independent predictors of ablation success. The mean LOS was 2.1 ±â€…0.3, 2.6 ±â€…0.6, and 2.9 ±â€…0.4 days, respectively, (P = .001). LOS rates of ≥ 3 days were 13.2%, 54.3%, and 84.8%, respectively. Mild decreases in hemoglobin, white blood cell (WBC), and platelet counts were observed in all groups after 6 weeks without any clinically significant findings. A lower rate of change in WBC counts was observed in the 30 to 50 mCi group compared to others. There was no dose-dependent difference regarding the early complaints questioned. Ablation with 30 to 50 mCi provides benefits such as shorter LOS, better patient comfort, less salivary gland dysfunction, and less WBC suppression, thus reducing costs without decreasing efficacy.

Radionuclide Therapy Videos on YouTube as An Educational Material: Has the COVID-19 Pandemic Changed the Quality, Usefulness, and Interaction Features.

Introduction: Current treatment approach aims to achieve greater efficacy with fewer side effects, by targeted cancer therapy as much as possible. Radionuclide therapy is a modality that uses cancer theranostics and is increasingly applied for various cancers as a targeted therapy. YouTube is a preferred tool for obtaining medical information from the internet. This study aims to determine the content quality, level of interaction and usefulness as education material of radionuclide therapy YouTube videos and to reveal the impact of the COVID-19 process on these parameters. Materials and Methods: The keywords were searched on YouTube on August 25, 2018, and May 10, 2021. After removing duplicate and excluded videos, all remaining videos were scored and coded. Results: Majority of the videos were useful educational material. Most of them were high quality. Popularity markers were unrelated to quality level. After COVID, the power index of videos with high JAMA scores increased. The COVID-19 pandemic did not have a negative effect on video features; the quality of the content increased even more after the pandemic. Conclusion: Radionuclide therapy YouTube videos have high-quality content and provide useful education material. The popularity is independent of the content quality. During the pandemic, video quality and usefulness characteristics did not change, while the visibility is increased. We consider YouTube to be an appropriate educational material for patients and healthcare professionals to gain basic knowledge of radionuclide therapy. The Covid-19 pandemic highlighted the power of radionuclide therapy YouTube videos as an educational material.

68Ga-PSMA-I&T-PET/CT interobserver and intraobserver agreement for prostate cancer: a lesion based and subregional comparison study among observers with different levels of experience.

OBJECTIVE: 68Ga-PSMA-PET/CT is a relatively new technique, that is rapidly becoming widespread. We aimed to contribute interobserver-intraobserver agreement of 68Ga-PSMA-PET/CT, among low/high-experienced interpreters. METHODS: 68Ga-PSMA-PET/CT of 56 patients with prostate cancer were evaluated blindly by four observers. Visual interpretation of malignant disease and SUVmax for lymph node (LN) regions, local tumor, bones and visceral organs were recorded. Cohen's Kappa and Fleiss' Kappa analyses were used to measure agreement between low/high/all-experienced observers. Variations were compared for regions, and the effect of prostate-specific antigen or Gleason score on the results was investigated. RESULTS: Interobserver agreement was almost perfect for all LN regions (LN1 low-experienced κ: 0.84/0.84, high-experienced 0.89/0.96; LN2 low-experienced κ: 0.88/0.79, high-experienced 0.95/0.95; LN3 low-experienced κ: 0.84/0.89, high-experienced 0.87/0.94, first/second readings, respectively) and bone lesions (low-experienced κ: 0.88/0.88, high-experienced 0.92/0.92, first/second readings, respectively). For local tumor, interobserver agreement was substantially-almost perfect among a high-experienced group (κ: 0.74/0.89, first/second readings, respectively), and was moderate-substantial among a low-experienced group (κ: 0.62/0.56, first/second readings, respectively). Intraobserver agreement was almost perfect for three observers for all regions and substantial for the observer with the lowest experience in LN3, local and visceral lesions (κ: 0.74/0.79/0.62, respectively). CONCLUSION: Interpretation of prostate-specific membrane antigen (PSMA) for prostate cancer is acceptably consistent among observers, but some details are noteworthy. The evaluation should be done more algorithmically for local tumors, since all observers showed relatively lower agreement. The agreement increased as prostate-specific antigen and Gleason score increased. The observer with PSMA experience <30 readings showed lower reliability, distinct from the others. This indicates that although a reader may be familiar with other PET agents, a more consistent interpretation of 68Ga-PSMA-PET/CT requires training with a small number of identified cases.

The Diagnostic Contribution of SPECT/CT Imaging in the Assessment of Gastrointestinal Bleeding: Especially for Previously Operated Patients.

OBJECTIVES: Gastrointestinal bleeding (GIB) is a life-threatening problem that requires a multidisciplinary approach for successful treatment. This study aims to emphasize the clinical contribution of single photon emission computed tomography/computed tomography (SPECT/CT) for the diagnosis of acute bleeding. METHODS: All 14 patients referred to the nuclear medicine department in 3 years with suspicion of acute GIB were evaluated retrospectively. Clinical records were analyzed to assess the scintigraphic findings, emphasizing the correlative contribution of the CT portion on SPECT/CT studies. RESULTS: Five patients were negative on dynamic and static planar images. SPECT/CT was performed in 9 patients who had positive findings on planar imaging. SPECT/CT could identify the same bleeding site originating from the anastomosis in four patients with a history of abdominal surgery. SPECT/CT confirmed bleeding from the cecum in a patient with cervical cancer. SPECT/CT showed the bleeding focus in the bladder neck of a patient with bladder cancer and the bleeding from peritoneal metastases of a patient with gastric cancer. In 1 patient, the right upper quadrant activity accumulation, which may cause false positives, was found to be the gallbladder on SPECT/CT. Delayed images showed the true bleeding focus in the cecum. In 1 patient, suspicious activity accumulation in the midline of the abdomen was found to be due to a previously unknown aortic aneurysm on SPECT/CT. CONCLUSION: SPECT/CT imaging is a feasible technique to facilitate image interpretation in patients with GIB. SPECT/CT imaging can guide the surgeon through more accurate localization. Therefore, for proper patient management, SPECT/CT should be applied to detect the bleeding focus, if present, especially in patients who had undergone a previous operation.

Animal Models for the Evaluation of Theranostic Radiopharmaceuticals.

BACKGROUND: Theranostic is a new field of medicine that combines diagnosis and patient- specific targeted treatment. In the theranostic approach, it is aimed to detect diseased cells by using targeted molecules using disease-specific biological pathways and then destroy them by cellular irradiation without damaging other tissues. Diagnostic tests guide the use of specific therapeutic agents by demonstrating the presence of the receptor/molecule on the target tissue. As the therapeutic agent is administered to patients who have a positive diagnostic test, the efficacy of treatment in these patients is largely guaranteed. As therapeutic efficacy can be predicted by therapeutic agents, it is also possible to monitor the response to treatment. Many diagnostic and therapeutic procedures in nuclear medicine are classified as theranostic. 131I treatment and scintigraphy are the best examples of the theranostic application. Likewise, 177Lu / 90Y octreotate for neuroendocrine tumors, 177Lu PSMA for metastatic or treatment-resistant prostate cancer, 90Y SIRT for metastatic liver cancer, and 223Ra for bone metastasis of prostate cancer are widely used. Moreover, nanoparticles are one of the most rapidly developing subjects of theranostics. Diagnostic and therapeutic agents that show fluorescent, ultrasonic, magnetic, radioactive, contrast, pharmacological drug or antibody properties are loaded into the nanoparticle to provide theranostic use. METHODS: This article reviewed general aspects of preclinical models for theranostic research, and presented examples from the literature. CONCLUSION: To achieve successful results in rapidly accelerating personalized treatment research of today, the first step is to conduct appropriate preclinical studies.