Radiation Therapy-Induced Fibrous Histiocytoma, Mimicking Local Recurrence and Detected by 18 F-FDG PET/CT in a Patient With Breast Cancer.

ABSTRACT: A 76-year-old woman was diagnosed breast carcinoma and treated with breast-conserving surgery and chemoradiotherapy. A year after the treatment completion, restaging 18 F-FDG PET/CT scan detected no any pathological finding. However, due to a lesion detected during physical examination on the right thoracic wall adjacent to the primary tumor bed, 18 F-FDG PET/CT imaging was performed 9 months later for restaging. Highly intense FDG uptake was detected in an approximately 1-cm nodular lesion, and metastasis was reported as suspicious, and histopathological confirmation was recommended. Excision was performed and pathological examination diagnosed benign cellular fibrous histiocytoma.

68 Ga-PSMA PET/CT Found Lower Respiratory Tract Inflammation Due to Inhaler Use.

ABSTRACT: Prostate-specific membrane antigen (PSMA) is a transmembrane protein physiologically expressed in nonprostatic tissues. Inflammation and infectious diseases could show false-positive PSMA uptake. Herein, we present a 55-year-old patient's findings of inflammation in the lower respiratory tract due to inhaler use in 68 Ga-PSMA PET/CT in a patient with prostate cancer.

Contribution of 68 Ga-DOTA-FAPI-04 PET/CT to Prostate Cancer Imaging : Complementary Role in PSMA-Negative Cases.

PURPOSE: Prostate-specific membrane antigen (PSMA)-targeted PET/CT is a well-established imaging method in prostate cancer (PC) for both staging and restaging, and also for theranostic applications. An alternative imaging method is crucial for 15% PSMA-negative cases. We aimed to investigate the contribution of 68 Ga-DOTA-FAPI-04 PET/CT to PC imaging. PATIENTS AND METHODS: Thirty-six patients diagnosed with PC were included. Patients underwent both 68 Ga-PSMA PET/CT and 68 Ga-DOTA-FAPI-04 PET/CT imaging within 1 week. In staging group, primary tumor uptake values were compared, and also correlations were done with histopathological findings, MRI findings, and total PSA levels. In biochemical recurrence group, the uptake values in prostatic region and metastases were evaluated to define the local recurrence or metastatic disease. RESULTS: In staging group, PSMA PET showed increased uptake in the primary lesion area in 14/27 (52%) patients, whereas 20/27 (74%) patients were positive in FAPI-04 PET. FAPI-04 positivity was found to be quite high, such as 54%, in PSMA-negative patients. A significant difference was observed between ISUP grade 1-3 patients and ISUP grade 4-5 patients in FAPI-04 PET ( P = 0.03). Local recurrence was detected in 3 patients, pelvic lymph node metastasis in 1 patient, and sacrum metastasis in 1 patient in biochemical recurrence group, and all of the lesions had more intense uptake in PSMA PET than FAPI-04 PET. CONCLUSIONS: FAPI PET imaging seems to have a potential to contribute PSMA PET imaging with FAPI positivity in more than half of PSMA-negative cases. Also, FAPI-targeted radionuclide therapy may be a promising method in patients resistant to PSMA-targeted therapy.

Treatment prediction with machine learning in prostate cancer patients.

There are various treatment modalities for prostate cancer, which has a high incidence. In this study, it is aimed to make predictions with machine learning in order to determine the optimal treatment option for prostate cancer patients. The study included 88 male patients diagnosed with prostate cancer. Independent variables were determined as Gleason scores, biopsy, PSA, SUVmax, and age. Prostate cancer treatments, which are dependent variables, were determined as hormone therapy(n = 30), radiotherapy(n = 28) and radiotherapy + hormone therapy(n = 30). Machine learning was carried out in the Python with SVM, RF, DT, ETC and XGBoost. Metrics such as accuracy, ROC curve, and AUC were used to evaluate the performance of multi-class predictions. The model with the highest number of successful predictions was the XGBoost. False negative rates for hormone therapy, radiotherapy, and radiotherapy + hormone therapy treatments were, respectively, 12.5, 33.3, and 0%. The accuracy values were computed as 0.61, 0.83, 0.83, 0.72 and 0.89 for SVM, RF, DT, ETC and XGBoost, respectively. The three features that had the greatest influence on the treatment model prediction for prostate cancer with XGBoost were biopsy, Gleason score (3 + 3), and PSA level, respectively. According to the AUC, ROC and accuracy, it was determined that the XGBoost was the model that made the best estimation of prostate cancer treatment. Among the variables biopsy, Gleason score, and PSA level are identified as key variables in prediction of treatment.

Formulation and In-vivo Characterization of 177Lu-tin-colloid as a Radiosynovectomy Agent.

INTRODUCTION: Arthritis is an inflammatory disorder that affects one or more joints of the body for various reasons, including autoimmune disorders, trauma, or infection. In many cases, traditional long-term treatment with various drug combinations (NSAIDs, diseasemodifying antirheumatic drugs, systemic corticosteroids, etc.) can provide relief, but many joints require additional local treatment. Radiosynovectomy (RSV) is an alternative method to current treatment options. Both the global supply shortage of 90Y in recent years and the increasing use of 177Lu-labeled radiopharmaceuticals in the field of nuclear medicine have made it possible to develop 177Lu-labeled microparticles and test them in small groups as RSV agents. This study aimed to develop the 177Lu labeled tin colloid formulation and demonstrate its invivo characterization. MATERIAL AND METHODS: Particle size, shape, and labelling efficiency of the four formulations developed were determined. The formula with the highest labelling efficiency was selected for further studies. The quality of the formulation was evaluated based on radionuclidic, radiochemical, and microbial purity. In-vitro stability was evaluated by determining the labelling efficiency. In-vitro stability was tested in PBS and synovial fluid. The biological characterization was assessed using SPECT/CT after injecting the formulation into the normal knee joints of the rabbits. RESULTS: Aggregated colloidal particles were spherical with a particle size of <5µm. Labelling efficiency and radiochemical purity were >95 and 97.65% (Rf=0.2), respectively. The formulation was stable in vitro for up to 72 hours, both in PBS and synovial fluid. The formulation was homogeneously distributed in the joint at 0 and 1 hour after injection, and radioactivity- related involvement and inguinal lymph node involvement due to possible leakage were not detected in the late period. No pyrogenic/allergic side effects were observed during this period. CONCLUSION: 177Lu-tin-colloid was successfully prepared under optimized reaction conditions with high binding efficiency and radiochemical purity. The radiolabeled colloid was found to be stable in-vitro both in PBS and synovial fluid at room temperature. Serial PCET/CT images revealed that the activity was completely retained within the synovial cavity, with no activity leakage out of the joint until 48 hours after the injection. With the support of the results from further clinical studies, it may be possible for the formulation to enter clinical use.

Investigation of Clinical Histopathologic Features and Metabolic Parameters of 18F-FDG PET/CT in Invasive Breast Carcinoma with a Micropapillary Component.

Objectives: The aim of this study was to evaluate the correlation between clinical histopathologic features and micropapillary (MP) ratio with the maximum standardized uptake value (SUVmax) derived from 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in treatment naïve breast cancer. Methods: Twenty-nine patients diagnosed with breast cancer with a MP component who underwent PET/CT imaging before any local and/or systemic treatment were included in this retrospective study. All clinical histopathological features were recorded. SUVmax values were measured from 18F-FDG PET images for primary tumors and metastatic axillary lymph nodes. Results: MP component percentage did not correlate with any clinical histopathological features except age. At early ages, the MP component ratio was significantly higher. Our results showed that there is no significant correlation between the SUVmax value and MP component percentage. Conclusion: A high SUVmax value is generally expected in aggressive malignancies. However, this assumption may not be valid for the MP subgroup, which has an aggressive course compared to other subgroups in breast cancer.

68 Ga-DOTA-FAPI-04 Imaging of Bilateral Phyllodes Tumor.

ABSTRACT: We present a case of bilateral Phyllodes tumor located in both breasts in a 41-year-old woman who was detected with increased uptake on 68 Ga-FAPI-04 (fibroblast activation protein inhibitor) and 18 F-FDG PET/CT imaging. The tumor filling up the right breast was identified as borderline Phyllodes. The tumor with mild uptake in the left breast was reported as a benign Phyllodes tumor.

68 Ga-FAPI-04 PET/CT in Selected Breast Cancer Patients With Low FDG Affinity : A Head-to-Head Comparative Study.

PURPOSE: In this prospective study, PET findings of 18 F-FDG PET/CT in breast cancer staging were compared with 68 Ga-FAP inhibitor (FAPI) 04 PET/CT findings in selected cases with relatively low 18 F-FDG uptake in the primary tumor or with suspected nodal or distant metastases. PATIENTS AND METHODS: Twenty-four women with a median age of 45 years (range, 36-67 years) who underwent initial staging 18 F-FDG PET/CT for breast cancer underwent 68 Ga-FAPI-04 PET/CT imaging within the same week. SUV max and quantities of primary tumors and locoregional and distant metastatic lesions were recorded from both images, and these data were compared statistically. RESULTS: The histological subtypes of primary tumors were 11 invasive lobular, 8 invasive ductal, and 5 mucinous subtypes. More intense 68 Ga-FAPI-04 uptake (mean, 17.1 ± 7.9; 7.4-38.5) was detected in all primary tumoral lesions compared with 18 F-FDG (mean, 6.3 ± 3.9; 1.5-20.5) ( P = <0.001, Z = 4.107). Additional lesions showing 68 Ga-FAPI-04 uptake in the breast were detected in 29.2% (n = 7) of patients. In 8.3% (n = 2) of the patients, the primary lesion showed only 68 Ga-FAPI-04 uptake. In 68 Ga-FAPI-04 PET/CT, 25% (n = 6) of the patients showed more lymph node involvement and more intense uptake in the ipsilateral axilla. In addition, infraclavicular (level 3) lymph nodes in 4 patients (16.7%), supraclavicular lymph nodes in 1 patient, and internal mammary lymph nodes in 1 patient were detected only on 68 Ga-FAPI-04 PET/CT. In a patient with lung and bone metastases, 68 Ga-FAPI-04 uptake was higher, and the lung nodule showed only 68 Ga-FAPI-04 uptake. CONCLUSIONS: In selected low-FDG-affinity breast cancer patients, 68 Ga-FAPI-04 PET/CT showed the primary tumor with higher sensitivity and higher SUV max values compared with 18 F-FDG PET/CT. In addition, it is believed that this method may contribute to the management of patients' treatment by increasing the nodal stage.

Complex Fibroadenoma Mimicking Breast Cancer on 68Ga-FAPI-04 and 18F-FDG PET/CT.

ABSTRACT: A 47-year-old woman had complaint of palpable swelling in the left breast for the last 3 weeks. 18F-FDG PET/CT for staging of concomitant invasive carcinoma in the right breast and 68Ga-labeled fibroblast activation protein inhibitor 04 PET/CT imaging in an ongoing study were performed. Increased radiopharmaceutical uptake was observed in both PET/CT imaging in complex fibroadenoma located in the left breast.

Findings of I-131 SPECT/CT, 18F-FDG, and 68Ga-FAPI-04 PET/CT Imaging in a Patient Treated with Radioiodine Therapy for Metastatic Papillary Thyroid Carcinoma.

A 50-year-old man undergone total thyroidectomy and histopathology revealed papillary thyroid carcinoma with a tumor size of 4.5 cm. The patient was referred to a nuclear medicine clinic for radioiodine therapy. Since the thyroglobulin level before the treatment was 495 ug/L, low-dose (185 MBq) I-131 scan was performed. In addition to multiple liver metastases, bone metastases were detected in the sacrum and right 7th rib in I-131 whole body scanning and single photon emission computed tomography/computed tomography (CT) imaging at the time of initial staging. We present a case of multiple metastatic papillary thyroid carcinoma whose radioiodine treatment response and clinical outcome were evaluated with 18F-fluorodeoxyglucose and Gallium-68 FAPI-04 positron emission tomography/CT.

Diagnostic impact of F-FDG PET/CT imaging on the detection of immune-related adverse events in patients treated with immunotherapy

Introduction: Immunotherapy is an effective treatment method for cancer cells with humoral and cellular immune mechanisms of action but triggers an inflammatory response and disrupts standard protective immune tolerance. Early detection of immune-related adverse events (irAEs) on PET/CT is crucial for patient management and subsequent therapy decisions. In this study, we aimed to evaluate the impact of 18F-FDG PET/CT on detecting of irAEs in patients receiving immunotherapy.Patients and methodsForty-six patients with advanced RCC (n: 32), malign melanoma (n: 9), lung cancer (n: 4), and laryngeal carcinoma (n: 1), who underwent 18F-FDG PET/CT imaging for response assessment after immunotherapy, were enrolled in the study. Newly detected findings associated with irAEs on posttreatment PET/CT images were compared with the pretreatment PET/CT, both qualitatively and semi-quantitatively.ResultsTwenty-eight (61%) patients developed irAEs as observed on PET/CT. Enteritis/colitis was the most frequent irAE visualized on PET/CT with 13 patients (28.2%), followed by gastritis (17.3%), thyroiditis (13%), and myositis/arthritis (13%). Hepatitis (6.5%), pneumonitis (6.5%), sarcoid-like reaction (4.3%), and hypophysitis (4.3%) were observed to a lesser extent. The median time between the appearance of irAEs on PET/CT and the initiation of immunotherapy was 4.3 months. There were no significant differences in age, sex, and treatment response status of patients with and without irAEs.Conclusion18F-FDG PET/CT plays a fundamental role in cancer immunotherapy with the potential to show significant irAEs both in the diagnosis and in follow-up of irAEs. IrAEs were present on PET/CT images of more than half of the patients who received immunotherapy in our study. (AU)

The Value of 18F-FDG PET/CT Imaging in the Evaluation of Interim Neoadjuvant Chemotherapy Response in Locally Advanced Breast Cancer.

Objectives: Neoadjuvant chemotherapy (NAC) is the frequently used treatment option for locally advanced breast cancer (LABC). This study investigated the potential value of 18fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to estimate the pathological complete response (pCR) using maximum standardized uptake value (SUVmax) and change (ΔSUVmax) after 3-4 cycles of NAC. Additionally, it was established the relationship between PET/CT imaging findings and histopathological features in LABC patients whose treatment response was evaluated with interim PET/CT. Methods: Patients were evaluated with pretreatment and interim PET/CT scans and operated after on NAC. Data on the age of patients, menopausal status, tumor placement, histopathological and molecular subgroups were noted. SUVmax and ΔSUVmax of the primary tumor and axillary lymph node (ALN) were calculated from PET/CT review. Results: Pretherapy mean SUVmax of the primary tumor and ALNs were 8.13±4.25 and 7.22±3.58, respectively. The highest mean primary tumor ΔSUVmax and ALN ΔSUVmax values were observed to be human epidermal growth factor receptor 2 positivity (p<0.001). SUVmax-T, SUVmax-N, ΔSUVmax-T, and ΔSUVmax-N values were significantly correlated with the ki-67 index (p<0.001). ΔSUVmax-T and ΔSUVmax-N values of pCR (+) patients were statistically higher than the ΔSUVmax-T and ΔSUVmax-N values of pCR (-) patients (p<0.001). Conclusion: An earlier and more accurate response to NAC can be performed using interim 18F-FDG PET/CT imaging. ΔSUVmax levels of the breast tumor and ALNs may act as predictive for pCR in LABC patients receiving NAC.

Diagnostic impact of 18F-FDG PET/CT imaging on the detection of immune-related adverse events in patients treated with immunotherapy.

INTRODUCTION: Immunotherapy is an effective treatment method for cancer cells with humoral and cellular immune mechanisms of action but triggers an inflammatory response and disrupts standard protective immune tolerance. Early detection of immune-related adverse events (irAEs) on PET/CT is crucial for patient management and subsequent therapy decisions. In this study, we aimed to evaluate the impact of 18F-FDG PET/CT on detecting of irAEs in patients receiving immunotherapy. PATIENTS AND METHODS: Forty-six patients with advanced RCC (n: 32), malign melanoma (n: 9), lung cancer (n: 4), and laryngeal carcinoma (n: 1), who underwent 18F-FDG PET/CT imaging for response assessment after immunotherapy, were enrolled in the study. Newly detected findings associated with irAEs on posttreatment PET/CT images were compared with the pretreatment PET/CT, both qualitatively and semi-quantitatively. RESULTS: Twenty-eight (61%) patients developed irAEs as observed on PET/CT. Enteritis/colitis was the most frequent irAE visualized on PET/CT with 13 patients (28.2%), followed by gastritis (17.3%), thyroiditis (13%), and myositis/arthritis (13%). Hepatitis (6.5%), pneumonitis (6.5%), sarcoid-like reaction (4.3%), and hypophysitis (4.3%) were observed to a lesser extent. The median time between the appearance of irAEs on PET/CT and the initiation of immunotherapy was 4.3 months. There were no significant differences in age, sex, and treatment response status of patients with and without irAEs. CONCLUSION: 18F-FDG PET/CT plays a fundamental role in cancer immunotherapy with the potential to show significant irAEs both in the diagnosis and in follow-up of irAEs. IrAEs were present on PET/CT images of more than half of the patients who received immunotherapy in our study.

Vas Deferens and Inguinal Canal Metastasis of Prostate Cancer Revealed by 68 Ga-Prostate-Specific Membrane Antigen PET/CT.

ABSTRACT: A 71-year-old man with prostate adenocarcinoma underwent 68 Ga-prostate-specific membrane antigen (PSMA) PET/CT for staging. 68 Ga-PSMA PET/CT showed the primary lesion along with bladder, rectum, bilateral seminal vesicle invasion, and metastatic pelvic lymph nodes with intense 68 Ga-PSMA uptake. Also, PET/CT showed rarely seen bilateral vas deferens invasion and metastasis to the inguinal canal. These rare metastases may be indicative of poor biological behavior and prognosis.

Role of 18F-FDG PET/CT in the assessment of therapy response and clinical outcome in metastatic renal cell carcinoma treated with tyrosine kinase inhibitors or immunotherapy.

OBJECTIVE: This study aimed to determine the role and prognostic significance of 18F-FDG PET/CT on treatment response and survival outcomes in metastatic renal cell carcinoma patients treated with immunotherapy or tyrosine kinase inhibitors (TKIs). PATIENTS AND METHODS: Forty patients scheduled for a standard treatment protocol with TKIs (n = 17; group-1) or PD-1 inhibitors (nivolumab, n = 23; group-2) were evaluated by 18F-FDG PET/CT. Peak standardized uptake value corrected for lean body mass (SULpeak) and maximum standardized uptake value (SUVmax) were calculated, and their relationship to treatment response was evaluated. RESULTS: Complete response (CR) in three patients, partial response (PR) in two patients and stable disease (SD) in eight patients were observed in group-1, and the results were as follows for group-2: PR in seven and SD in five patients. At a mean of 17.5-month observation period (range, 7-47), 35.2% of patients progressed, and 23.5% achieved a CR, and no recurrence was observed on PET/CT scans during follow-up. Among all patients enrolled in the study, the 5-year OS in patients with progressive disease (PD) was significantly shorter than patients with clinical benefit (CB = CR and PR and SD) (P = 0.016). Significant differences in both ΔSULpeak and ΔSUVmax were found between PD versus CB (P = 0.001 and P < 0.001, respectively). CONCLUSION: 18F-FDG-PET/CT can accurately assess therapy response and predict patient outcome in metastatic RCC. 18F-FDG PET/CT may facilitate patient management by evaluating the biological and immunological responses to treatment in patients treated with TKIs or ICIs.

Peritoneal Tuberculosis Mimicking Peritoneal Carcinomatosis on 68 Ga-FAPI-04 and 18 F-FDG PET/CT.

ABSTRACT: We report a case of tuberculosis peritonitis in a 26-year-old woman who presented with abdominal pain, fatigue, and weight loss for the last 4 months. Abdominal US and CT demonstrated intra-abdominal massive ascites, misty mesentery, and diffuse peritoneal thickening. In addition, 3 nodular lesions were detected in the right lung. 18 F-FDG PET/CT showed hypermetabolism in lung nodules, mesenteric area, peritoneal thickening, and ascites. 68 Ga-FAPI-04 (fibroblast activation protein-specific inhibitor) PET/CT imaging was also performed; high uptakes were detected in the same regions of 18 F-FDG PET/CT. Tuberculosis diagnosis was made after histopathological examination of wedge resection of the right lung.

Diffuse Large B-Cell Non-Hodgkin Lymphoma Involving Multiple Different Organs in a Young Adult with 18F-FDG PET/CT.

Extranodal-multiorgan involvement is rarely presented in diffuse large B-cell non-Hodgkin lymphoma. 18Fluorine-fluorodeoxyglucose positron emission tomography/computed tomography findings of a 22-year-old female patient with supra/infra-diaphragmatic nodal and skeletal involvements and thyroid, pancreas, right breast, bilateral renal, and ovarian involvements were presented.