FAPI Uptake in Gallbladder Is It Normal Biodistribution?

ABSTRACT: Radiolabeled fibroblast activation protein inhibitors (FAPIs) have been extensively used in different types of cancers, although not yet FDA approved. Normal patterns of FAPI biodistribution have been investigated, and it is known that FAPI is expressed in nonmalignant pathophysiological lesions, characterized by tissue remodeling such as atherosclerosis, arthritis, and scar/fibrotic tissues. In this interesting image, we are presenting the accumulation of 68 Ga-FAPI in the gallbladder. This finding could be related to a normal distribution of the radiotracer as a physiologic finding. This is a potentially important finding as FAPI may be used as theragnostic agent in the future.

68 Ga-PSMA-Avid Liver Metastases From Colon Cancer, Not Visualized on FDG PET Scan.

ABSTRACT: 18 F-FDG PET/CT scan is a well-known modality to assess distant metastases and treatment response in the patients with primary colon cancer. We are presenting an interesting case of 68 Ga-PSMA-avid liver metastases in a 74-year-old man with colon cancer and recently diagnosed prostate cancer. The liver metastases were positive on initial FDG PET but lost FDG avidity on subsequent posttreatment FDG PET scans. Biopsy from the PSMA-avid liver lesions confirmed metastasis from colon origin. PSMA is expressed in various forms of tumor neovasculature other than prostate cancer with potential new applications as a theranostic agent in the future.

FDG PET/CT in Immune-Related Arthritis in a Patient Treated With Nivolumab.

ABSTRACT: Immune checkpoint inhibitors are a new and different treatment option in many of solid tumors, but with many recognized immune-related adverse side effects. In this interesting image, we are presenting a 56-year-old woman with primary malignant melanoma who underwent nivolumab therapy for 5 months, and a posttreatment whole-body FDG PET/CT scan for treatment response evaluation demonstrated increased metabolic activity in the entire major joints of the upper and lower extremities. This was a new finding compared with previous FDG PET/CT scan and was interpreted as an immune-related arthritis complication.

Steatotic Hepatitis Presenting as a Huge Hypermetabolic Liver Mass.

ABSTRACT: FDG PET/CT scan is a diagnostic imaging modality for oncologic patients, but with false-positive findings in inflammatory diseases. In this interesting case, we present a 24-year-old woman with history of giant cell tumor of the bone (lumbar vertebrae) who underwent whole-body FDG PET/CT scan for treatment response evaluation. FDG PET/CT scan demonstrated a large hypermetabolic tumoral mass lesion in segment VI/VII of the right hepatic lobe. A range of malignant versus benign lesions should be considered as differential diagnoses, including metastasis, primary cholangiocarcinoma, hepatocellular carcinoma, focal nodular hyperplasia, and infection. Final diagnosis of "steatotic hepatitis" after CT-guided biopsy was established.

Rare Presentation of Inflammatory Lung Disease and Subcutaneous Nodules on FDG PET/CT Scan: Brief Discussion of Differential Diagnoses.

ABSTRACT: We present a 37-year-old man with cough and progressive dyspnea for the past 3 years. According to inconclusive chest CT scan and lung biopsy histopathology findings, the patient referred for 18F-FDG PET/CT scan for further evaluation. Classic pulmonary manifestations of Langerhans cell histiocytosis were seen on CT images with intense FDG uptake on PET scan. Moreover, PET/CT revealed multiple hypermetabolic subcutaneous foci throughout his body. Finally, the patient was treated with corticosteroids. Follow-up chest CT images demonstrated improvement of lung lesions in accordance with improvement in the patient's symptoms. We are briefly discussing differential diagnoses in this patient.

68Ga-DOTATATE Radioisotope scan to detect neuroendocrine tumors; A Cross-Sectional Study.

OBJEVTIVES: Neuroendocrine tumors are a heterogeneous group of neoplasms that arise from the peptide-producing cells of the neuroendocrine system. Different functional imaging methods have been suggested to diagnose NETs. There is still not enough evidence to recommend 68Ga-DOTATATE as a standard diagnostic tool in NETs. Therefore, the aim of this study was to assess the value of 68Ga-DOTATATE scan in detecting NETs. METHODS: This was a cross-sectional study. All patients with a pathologically confirmed NET tumor referred to Masih Daneshvari Hospital affiliated to Shahid Beheshti University of Medical Sciences entered the study. Patients underwent a 68Ga-DOTATATE PET/CT. All statistical analysis were performed by SPSS software version 18. RESULTS: Forty patients with a mean age of 48.1±15.80 years entered the study. Twenty-one (52.5%) were male and 19 (47.5%) female. In the studied patients, neuroendocrine tumor was present in 19 cases (47.5%) in pancreas and gastrointestinal tract, 9 (22.5%) in lung, 3 (7.5%) in mediastinum and adrenal gland, 6 cases (5%) in liver and 3 other sites. There was no significant association between mean age and gender with primary location of the tumor. The mean SUVmax was 11.62±20.02 and the the mean tumor size was 38.25±31.35 mm. The mean size of the metastasis was 40.55±24.53 mm. The mean percentage of ki-67 was 12.54±18.40. There was no significant correlation between SUVmax of the lesion and age (r=0.063, P=0.701), tumor size (r=-0.63, P=0.067) or Ki-67 (r=0.011, P=0.960). In 20 cases, metastases were reported, of which 14 were (70%) in the liver, 3 in the lungs (15%), 2 in the gastrointestinal and cervical lymph nodes, and 1 in the bones and pancreas(%5). CONCLUSION: 68Ga-DOTA-peptide PET/CT could find the primary or metastasis sites of NETs with good quality images. In general, this modality can enhance the management in patients with NETs.

Interesting Manifestation of Autoimmune Encephalitis on FDG PET Scan.

ABSTRACT: We are presenting a 22-year-old man with intractable seizures. Autoimmune epilepsy, vasculitis, and paraneoplastic disorder were among initial differential diagnoses. His initial laboratory tests and toxicology screen were unremarkable. His initial brain MRI demonstrated generalized cortical atrophy. Features such as progressive encephalopathy, neuropsychiatric symptoms, personality change, and autonomic dysfunction were in favor of autoimmune encephalitis. Autoantibody evaluations including anti-NMDA receptor (NR1) IgG were negative in both serum and CSF samples. FDG PET scan demonstrated intense FDG uptake in the basal ganglia, more prominent in the caudate nuclei and putamina, which is one of the known autoimmune encephalitis imaging features.

Comparison of non-invasive imaging modalities in presurgical evaluation of temporal lobe epilepsy patients: a multicenter study.

Intractable drug-resistant magnetic resonance imaging (MRI) negative epilepsy in one of the complicated issues in neurology. Epilepsy surgery is beneficial treatment of intractable seizures, but precise localization of epileptogenic zone is a major concern. Thirty-four MRI negative drug-resistant epilepsy patients underwent video electroencephalography (EEG), positron emission tomography (PET) scan, and voxel-based morphometry (VBM) MRI from 2014 to 2019. Then, the findings of PET scan and VBM were compared with semiology and long-term electrophysiology. Cohen's kappa-coefficient (k) test was utilized to measure the agreement between our modalities. Among 34 patients with age ranging from 8 to 49 (mean: 29.00 ± standard deviation: 10.35), 19 were male (55.9%) and 15 were female (44.1%). Twenty-one patients (61.76%) had right temporal, 12 patients (35.3%) had left and one patient had bilateral temporal ictal focus according to video EEG. Inter-rater agreement analysis showed that the kappa index between video EEG and PET scan was of almost acceptable (more than 0.4) and there was poor agreement between video EEG and VBM (kappa index = 0.099). PET is highly concordant with video EEG in temporal lobe epilepsy (TLE) and has a considerable agreement in localizing epileptogenic zone while VBM is less.

Diffuse Subcutaneous Metabolic Activity in Post Bone Marrow Transplant Hodgkin Lymphoma.

ABSTRACT: We present a 14-year-old adolescent boy with Hodgkin lymphoma. He had prior completed chemotherapy with ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) regimen followed by bone marrow transplantation 6 months ago. Currently, he has neither specific clinical complaint nor receiving any specific medication. Follow-up FDG PET/CT scan demonstrated diffuse increased metabolic activity in the entire body subcutaneous tissue. This finding is rarely reported in the literature and may represent an underlying active inflammatory process, most likely attributed to the received treatments. This could impair the diagnostic quality of the scan, affecting the image interpretation, and should be recognized when present.

Hypersensitivity Pneumonitis High-resolution Computed Tomography Findings, and Their Correlation with the Etiology and the Disease Duration.

Hypersensitivity pneumonitis (HP) is an immune-mediated diffuse parenchymal lung disease induced by inhaled antigens. High-resolution computed tomography (HRCT) is widely used in the diagnosis and follow-up of patients and determining the progression and prognosis of the disease. In this retrospective study, 45 consecutive patients with the final diagnosis of HP, seen at a large tertiary care center during a period of 4 years, were included and their HRCT findings were evaluated. The most common HRCT findings were ground glass opacity and reticulation. Some HRCT patterns were detected more severely in bird fanciers in comparison with other etiologies. There is no "gold standard" for the diagnosis of HP. HRCT findings play an important role in hypersensitivity pneumonitis diagnosis and CT scan also help to define the severity of hypersensitivity pneumonitis injuries. In our study, reticulation and ground glass opacity were the most common findings in HRCT of patients with HP. We also find that patients with avian contacts had a significantly higher rate of fibrosis.

A Case of Coronavirus Infection Incidentally Found on FDG PET/CT Scan.

We present a highly suspicious case of COVID-19 infection, incidentally found on F-FDG PET/CT images. Patient was scanned on February, 25, 2020, when COVID-19 outbreak was unrecognized in our country. She admitted having recent occasional dry cough and fever. A retrospective review of her clinical and laboratory data was strongly suggestive for diagnosis of COVID-19 infection. PET/CT images demonstrated hypermetabolic diffuse ground glass opacities in both lungs with bilateral nodules. There was no evidence of pleural effusion or prominent mediastinal or hilar lymphadenopathy. Radiologists must be aware of COVID-19 presentations on PET/CT scan images during COVID-19 outbreak.

Clinical Significance of Quantitative FDG PET/CT Parameters in Non-Small Cell Lung Cancer Patients.

BACKGROUND: An initial evaluation of non-small cell lung cancer (NSCLC) patients with 18F- fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan can modify treatment planning. We investigated the clinical significance of FDG PET/CT quantitative parameters (QPs) in NSCLC patients. MATERIALS AND METHODS: We included 125 NSCLC patients for initial staging FDG PET/CT scan. The primary tumor (T), regional lymph node metastases (N), and distant metastases (M) were evaluated on FDG PET/CT images. QPs, including standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated separately for each T, N, and M lesion and also for the whole body. Statistical analysis through SPSS version 22 was used to evaluate the clinical significance of PET/CT QPs concerning primary tumor pathology characteristics, initial tumor stage, and patient's prognosis. RESULTS: We followed the patients for 19.28 (±11.42) months. Considering primary tumor pathology, there was a significant difference in FDG PET/CT QPs, including primary tumor SUVmax (p=0.00), metastases SUVmax (p=0.014), whole-body MTV (p=0.045), and whole-body TLG (p=0.002). There was also a significant difference in QPs, including primary tumor SUVmax (p=0.00) and regional lymph node metastases SUVmax (p=0.048) when accounting for tumor initial stage. There was a significant prognostic value for the whole-body TLG (p=0.01) and a cut-off point of 568 was reached to differentiate better versus worse survival outcome. CONCLUSION: We demonstrated a statistically significant difference in FDG PET/CT QPs when accounting for primary NSCLC pathology characteristics and initial stage, as well as patient's prognosis, and recommend incorporating QP values into clinical PET/CT reports.

Primary Ewing sarcoma of the kidney.

Primary Ewing sarcoma (ES) or primitive neuroectodermal tumour (PNET) is a rare tumour in adults and primary renal involvement is extremely rare. Patients with renal ES or PNET respond to and would benefit from conventional ES treatment according to ES study protocols. Here, we report a case of a young woman, presenting with right flank pain and haematuria. After ultrasound and CT evaluation, a right middle pole renal mass was detected. The patient underwent radical right nephrectomy, and a grade 4 ES with peritoneal involvement was documented. Subsequently, the patient underwent adjuvant chemotherapy for 5 months. Follow-up 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scan demonstrated bilateral cervical, hilar, mediastinal and retroperitoneal FDG-avid adenopathies associated with mild right-sided pleural effusion with no metabolic activity, signifying the role of PET/CT scan in tumour restaging.

Rectal adenocarcinoma presenting with thigh muscle metastasis as the only metastatic site.

Rectal carcinoma with metastasis to skeletal muscle is a rare finding. According to literature review, 17 cases of skeletal muscle metastasis from colorectal carcinoma have been documented where only six cases were rectal carcinomas.We discuss a case of a middle-aged man with a known history of high-grade mucinous adenocarcinoma of the rectum, status post abdominoperineal resection followed by adjuvant radiotherapy and chemotherapy. During the planned chemotherapy course, a right proximal thigh subcutaneous mass was incidentally found which on subsequent biopsy proved to be metastatic from rectal primary site. On subsequent 18F-FDG (Fluorodeoxyglucose) positron emission tomography (PET)/CT scan after completion of chemotherapy for the purpose of treatment response evaluation, only FDG-avid lesion was residual right proximal thigh metastatic mass without involvement of other common sites, such as liver and lung. In this case, the 18F-FDG-PET/CT scan was able to exclude additional metastatic sites and also evaluate the patient's treatment response.

Distribution and Characteristics of Intrathoracic Lymphadenopathy in TB/HIV Co-Infection.

BACKGROUND: Intrathoracic Lymphadenopathy (ITLN) in Human Immunodeficiency Virus (HIV) infected patients may have various etiologies and prognoses. Etiologies of ITLN can be distinguished based on the distribution of enlarged lymph nodes. Sometimes tuberculosis (TB) is the first sign of underlying HIV infection. OBJECTIVES: We sought to determine ITLN distribution and associated pulmonary findings in TB/HIV co-infection using Computed Tomography (CT) scan. METHODS: In this retrospective, observational, cross-sectional study, chest CT scans of 52 patients with TB/HIV co-infection were assessed for enlarged intrathoracic lymph nodes (>10 mm in short axis diameter), lymphadenopathy (LAP) distribution, calcification, conglomeration, the presence of hypodense center and associated pulmonary abnormalities. LAP distribution was compared in TB/HIV co-infection with isolated TB infection. RESULTS: Mediastinal and/or hilar LAP were seen in 53.8% of TB/HIV co-infection patients. In all cases, LAP was multistational. The most frequent stations were right lower paratracheal and subcarinal stations. Lymph node conglomeration, hypodense center and calcification were noted in 25%, 21.4% and 3.5% of patients, respectively. LAP distribution was the same as that in patients with isolated TB infection except for the right hilar, right upper paratracheal and prevascular stations. All patients with mediastinal and/or hilar adenopathy had associated pulmonary abnormalities. CONCLUSION: All patients with TB/HIV co-infection and mediastinal and/or hilar adenopathy had associated pulmonary abnormalities. Superior mediastinal lymph nodes were less commonly affected in TB/HIV co-infection than isolated TB.

Correlation of quantified metabolic activity in nonsmall cell lung cancer with tumor size and tumor pathological characteristics.

The aim of this study was to evaluate the relationship between maximum standardized uptake value (SUVmax) with tumor size and tumor pathological characteristics as well as suggesting equations between SUVmax and tumor size in patients with nonsmall cell lung cancer (NSCLC) to help differentiate between pathology types.We retrospectively analyzed the fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) findings of 98 patients with NSCLC. Statistical differences were considered significant when P < .05. Correlation between SUVmax and other variables was determined by Pearson and Spearman correlation. Both linear and nonlinear regression analysis were used to determine equations between SUVmax and tumor size to help differentiate between pathology types.The mean SUVmax in patients with squamous cell carcinoma was significantly higher than that of adenocarcinoma (21.35 ±â€Š1.73 vs 13.75 ±â€Š0.89, P = .000). The results of regression analysis indicated that among all equations determined with relative accuracy, the "cubic equation" has the highest accuracy when considering the relationship between SUVmax and tumor size in patients with adenocarcinoma. In patients with squamous cell carcinoma, the most accurate equation was obtained using the "quadratic equation."There was a significant correlation between SUVmax and tumor differentiation and tumor size in patients with adenocarcinoma. SUVmax of patients with squamous cell carcinoma also had a significant correlation with tumor size. Overall SUVmax of patients with NSCLC could be predicted by tumor size value. In patients with squamous cell carcinoma compared with those with adenocarcinoma, SUVmax with less accuracy can be determined by tumor size. Linear regression analysis line slope can be used as an index for distinguishing adenocarcinoma from squamous cell carcinoma.

Recurrent inflammatory myofibroblastic tumour of the lung: FDG PET/CT scan findings.

Inflammatory myofibroblastic tumour (IMT) is a rare neoplasm, occurring most often in children and young adults. IMTs have intermediate biological behaviour with the chance of local invasion, recurrence and even distant metastasis. Wide range of clinical presentations makes the precise diagnosis of IMT more challenging. The best method for definitive diagnosis is tissue biopsy and newer imaging modalities including fleurodeoxyglucose (FDG) positron emission tomography (PET)/CT are useful tools in detection of disease recurrence or distant metastasis. Complete surgical resection is the best-known treatment for this tumour. Here we are presenting an IMT case in a 12-year-old girl in which her recurrent pulmonary IMT was diagnosed based on FDG PET/CT findings and referred for further salvage treatment. Overall imaging modalities are not specific, but PET/CT scan can be useful tool for evaluation of IMT regarding initial staging and restaging to assess treatment response and recurrence.

Mantle cell lymphoma presenting as bilateral adrenal huge masses.

We present a middle-aged woman complaining of weakness, lethargy and weight loss for 6 months. Positron emission tomography (PET)/CT scan revealed huge bilateral adrenal masses with intense 18F-fluorodeoxyglucose avidity. Biopsy and immunohistochemical staining were compatible with mantle cell lymphoma (MCL). The patient received six cycles of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) followed by four cycles of intrathechal methotrexate chemotherapy. Bone marrow aspiration biopsy was performed for initial staging and also before bone marrow transplantation. Follow-up PET/CT scan after completion of chemotherapy and before bone marrow transplantation demonstrated complete metabolic response with no evidence of abnormal metabolic activity in either adrenal gland or bone marrow. MCL has an aggressive nature and is usually considered incurable; however, there have been a few reports indicating favourable treatment response when MCL is rarely arising from the adrenal glands. Dramatic response of a primary adrenal MCL to R-CHOP is documented in this case.

Hypermetabolic Thyroid Incidentaloma on Positron Emission Tomography: Review of Laboratory, Radiologic, and Pathologic Characteristics.

INTRODUCTION: Incidental hypermetabolic thyroid lesions on Positron Emission Tomography have significant clinical value and may harbor malignancy. In this study we evaluated laboratory, radiologic, and pathologic characteristics of incidental hypermetabolic thyroid lesions. MATERIALS AND METHODS: We evaluated 18 patients prospectively with various malignancies and hypermetabolic thyroid incidentaloma. The thyroid function tests, ultrasound assessment, and guided FNA biopsy were performed on all cases. RESULTS: We included 9 male and 9 female patients with mean age of 51 years. Most common malignancy was colon cancer. Metabolic activity quantification using maximum standard uptake value demonstrated range between 1.4 and 65.4 with mean value of 9.4. We found highest metabolic activity in patients with lung adenocarcinoma, B-cell lymphoma, and colon adenocarcinoma. On ultrasound exam most thyroid lesions were of solid, hypoechoic, noncalcified nature with either normal or peripheral increased vascularity. FNA biopsy report was benign in 15 cases and malignant or highly suggestive for malignancy in 3 other cases. Two of the three malignant cases demonstrated metabolic activity higher than average SUV max. CONCLUSION: Most thyroid hypermetabolic incidentalomas are benign lesions, while higher values of SUV max are in favor of malignancy. This mandates further evaluation of incidentally found thyroid hypermetabolic lesions on routine PET/CT scans.

Role of FDG PET/CT Scan in Head and Neck Cancer Patients.

INTRODUCTION: PET/CT scan has an emerging role in head and neck oncology with a few well-established indications, including: detection of unknown primary tumor site, tumor staging, radiotherapy planning, treatment response assessment and detection of recurrent disease. The purpose of this study is reporting PET/CT findings in head and neck cancer patients to emphasize its role in head and neck oncology. MATERIALS AND METHODS: In a retrospective study, we reviewed our PET/CT database and found 94 patients with primary head and neck cancer. This is a descriptive report of PET/CT scan findings in head and neck cancer patients referred to Masih Daneshvari hospital, Tehran, Iran between 2013 and 2016. RESULTS: The most common primary tumor sites were oral cavity (27%) and nasopharynx (22%). The most common indication for referral was tumor restaging (76%) including treatment response evaluation and differentiation between recurrence and post-treatment fibrosis. In 60% of patients with negative primary tumor site, PET/CT was able to detect evidence of regional or distant metastasis. PET/CT was able to localize the primary tumor site in 66% of patients with unknown primary tumor site. We also had 19 patients with primary head and neck cancer referred for initial staging, demonstrating evidence of metastasis in 66% of all cases. CONCLUSION: Most patients are referred for restaging and demonstrate evidence of regional or distant metastasis with significant value for further treatment planning. Providing insurance coverage and familiarizing referring physicians about correct indications of this relatively new diagnostic modality will be to the best interest of head and neck cancer patients in the long run.