Anti-programmed-death-receptor-1 (PD-1) antibody (Pembrolizumab) induced pancreatitis diagnosed on 18F-FDG PET/CT.

Immunotherapy related adverse events are commonly seen with immune check point inhibitors therapy. We report the case of a 40-year-old female diagnosed with stage IVB endometroid grade III endometrial cancer, on pembrolizumab immunotherapy, an anti-programmed-death-receptor-1 (PD-1) antibody. Patient was referred for 18F-FDG PET/CT for restaging. 18F-FDG PET/CT demonstrated diffuse increased FDG uptake throughout the body of the pancreas associated with fat stranding in the peripancreatic region, suggestive of pembrolizumab-induced pancreatitis. The diagnosis was confirmed by elevated amylase and lipase levels. immune-related adverse events (irAE) are frequently identified on 18F-FDG PET-CT, which may lead to early diagnosis, close clinical follow-up, and appropriate clinical management of immune-related adverse events.

Super Mario sign at somatostatin receptor PET/CT.

68Ga-DOTA NOC PET-CT imaging has been shown to have high accuracy for the evaluation of neuroendocrine tumours. We present the case of a 59-year-old male with well differentiated gastric neuroendocrine tumour (grade II) treated with surgery. 68Ga-DOTA NOC PET/CT was performed to rule out metastasis. 68Ga-DOTA NOC showed physiological uptake in the bilateral adrenal and horseshoe kidney appearing as the famous character Super Mario. There is no evidence of any abnormal somatostatin avid lesion.

Krukenburg tumour: Role of 18F-FDG PET/CT in identifying the primary site.

Krukenberg tumours are a rare form of metastatic tumours of the ovary. They primary site is usually the gastro-intestinal system with the most common being gastric cancer. We present the case of a 35-year-old female coming in with a large pelvi-abdominal mass for investigation. This pelvic mass showed mild to moderate metabolic activity. 18F-FDG PET-CT was able to identify the primary gastric carcinoma. Subsequent histopathology confirmed this to be gastric adenocarcinoma with metastases to the ovary.

The role of 18F-FDG PET/CT in Neurolymphomatosis: A Comprehensive Imaging Approach.

Neurolymphomatosis (NL) is an uncommon and rare neurologic disorder characterised by extranodal lymphoma, where the tumour cells invade the cranial nerves, nerve plexus, nerve root, spinal nerve roots, trunk nerves or peripheral nerves. MRI is the modality of choice, but is often challenging in detection of early recurrence, assessing residual disease and response evaluation. 18FFDG PET/CT has superior diagnostic performance compared with body CT in the evaluation of NL. 18F-FDG PET-CT is helpful in evaluation of disease extent and potential to guide biopsy. 18F-FDG PETCT is a highly sensitive technique for early localisation of NL than MRI or CT alone. Besides diagnostic and prognostic value in NL, it might be very helpful in response assessment.

Initial clinical experience using 68Ga-FAPI-46 PET/CT for detecting various cancer types.

OBJECTIVE: Numerous studies have shown that gallium-68-labeled fibroblast activation protein inhibitor (68Ga-FAPI) positron emission tomography/computed tomography (PET/CT) scans would yield high intra-tumoral tracer uptake and low uptake in normal tissues as background, thus allowing for excellent visualization of lesions in the cancer microenvironment. This study set out to compare the suitability of novel 68Ga-FAPI-46 PET versus routine fluorine-18-fluorodeoxyglucose (18F-FDG) PET and other few cases of 68Ga-DOTATATE/68Ga-Pentixafor PET/CT for the assessment of different types of cancer. SUBJECTS AND METHODS: A retrospective analysis of 11 patients (6 males, 5 females; average age: 53 years, range: 10-58 years) with histopathologically confirmed, well-differentiated adenocarcinoma, medullar thyroid cancer (MTC), papillary thyroid carcinoma (PTC), cervical, gastric, glioblastoma multiform (GBM), colon, Ewing's sarcoma, and breast cancer was performed. These patients underwent PET/CT scans using four different radiotracers (9 18F-FDG, 11 68Ga- FAPI, 3 68Ga-DOTATATE, and 1 68Ga-Pentixafor). The patients' PET/CT images were visually evaluated for cancer detection, and analyzed semi-quantitatively through image- derived metrics, such as target-to-background ratio (TBR) and maximum standardized uptake value (SUVmax), for recurrence and metastasis. RESULTS: The study of 11 patients revealed that 68Ga-FAPI-46 was more effective than other tracers for detecting metastases, with 55 vs. 49 metastases in the lymph nodes, 4 vs. 3 in the liver, and 4 vs. 3 in the bones detected in comparison to 18F-FDG. No significant differences were observed in 68Ga-DOTATATE and 68Ga-Pentixafor PET images. In addition, in five patients, the SUVmax and TBR values in 68Ga-FAPI-46 PET images were significantly higher than those in 18F-FDG PET images for lymph nodes and bone metastases. Although the SUVmax in 68Ga-FAPI-46 and 18F-FDG PET images for liver metastases was comparable, 68Ga-FAPI- 46 had a significantly higher TBR than 18F-FDG. CONCLUSION: Our findings suggest that FAPI PET/CT is not suitable for evaluating GBM and Ewing sarcoma but generally outperforms 18F-FDG PET/CT in various types of breast cancer, gastrointestinal, gynecological, PTC and MTC. However, larger trials are needed to validate these preliminary findings.

Accumulation of 131Iodine in the nasolacrimal sac/duct after radioiodine therapy for papillary thyroid cancer.

SPECT/CT is a powerful tool for assessing unexpected concentrations of radioiodine resulting from benign uptake in organs with sodium-iodide symporter (NIS) expression. We report a case of accumulation of 131Iodine in the nasolacrimal sac/duct after radioiodine therapy for papillary thyroid cancer. A whole-body scan was taken 3 days after the administration of 5.5 GBq of 131Iodine. SPECT/CT images localized the focal tracer uptake in the nasolacrimal sac/duct likely due to nasolacrimal duct obstruction secondary to prior radioiodine or iodine therapies. Hybrid SPECT/CT allows precise anatomical localization and help differentiate benign mimics of disease, which can alter patient management.

Paediatric metastatic ganglioneuroblastoma on 68Ga-DOTA NOC PET-CT.

68Ga-DOTA NOC PET-CT imaging has been shown to have high accuracy for the evaluation of neuroendocrine tumours. We report a case of a 3-year-old boy who presented with a right paravertebral soft tissue mass. Biopsy showed ganglioneuroblastoma. The patient was referred for 68Ga-DOTA NOC for staging. 68Ga-DOTA NOC PET/CT images showed somatostatin-avid large right paravertebral soft tissue mass representing the primary lesion, along with increased radiotracer localization at multiple metastatic lytic bone lesions in the axial and appendicular skeleton. 68Ga-DOTA NOC PET-CT is helpful in the evaluation of the disease extent of neuroendocrine tumours including ganglioneuroblastoma.

Tumour sink effect on 68Ga-PMSA PET/CT: A case of diffuse metastatic disease of prostate cancer.

68Ga-PMSA imaging has revolutionized both diagnosis and radioligand therapy selection in patients with metastatic prostate cancer. We report a case of a 59-year-old recently diagnosed prostate cancer with high PSA level pf >2000ng/ml referred for 68Ga-PSMA PET/CT. 68Ga-PSMA PET/CT showed diffuse intense tracer uptake throughout the axial and appendicular skeleton with significantly lower uptake of 68Ga-PSMA in normal organs in a configuration of "tumour sink effect". Findings are in keeping with diffuse skeletal infiltration and suspected marrow infiltration. Given the extensive nature of bone disease and pattern, 177Lu-PSMA-targetted radioligand therapy was thought to be more appropriate in a given situation with a favourable toxicity profile.

68Ga-DOTA-peptide PET/CT for radiotherapy planning and evaluating treatment response in the management of meningiomas.

Meningiomas overexpress somatostatin receptors (SSTR). PET imaging with SSTR ligands such as 68Ga-DOTA-peptide has recently shown high diagnostic accuracy in identification of meningiomas due to lack of normal bone and brain activity. PET-derived parameters, especially gross tumour volume (GTV) delineation improves inter-observer variability and appears to be particularly promising for RT planning. The potential strength of 68Ga-DOTA in the ongoing assessment of treatment response and disease progression in meningioma, particularly in the post-surgical and post-radiation settings is encouraging. More prospective randomized studies with large cohorts of patients are required to define the effective role of this modality.

Prospective study of Na[18F]F PET/CT for cancer staging in morbidly obese patients compared with [99mTc]Tc-MDP whole-body planar, SPECT and SPECT/CT.

PURPOSE: This prospective study aims to assess the diagnostic test characteristics of Na[18F]F PET/CT for the skeletal staging of cancer in morbidly obese patients compared with 99mTc-methylene diphosphonate (MDP), whole-body planar (WBS), SPECT, and SPECT/CT acquisitions. MATERIAL AND METHODS: One hundred seventeen obese patients (BMI 46.5 ± 6.1 kg/m2 and mean age, 59.0 years; range 32-89 years) with BMI > 40 kg/m2 were prospectively enrolled and underwent [99mTc]Tc-MDP WBS, SPECT, SPECT/CT, and Na[18F]F PET/CT within two weeks for the osseous staging of a malignancy. Images were assessed qualitatively using a 3-point scale. Patient and lesion-based diagnostic test characteristics were estimated using an optimistic and pessimistic dichotomization method. RESULTS: Bone metastases were confirmed in 44 patients. Patient-based optimistic diagnostic test characteristics were (sensitivity, specificity, overall accuracy): Na[18F]F PET/CT (95.5%, 95.9%, 95.7%), [99mTc]Tc-MDP WBS (52.3%, 71.2%, 64.1%), SPECT (61.4%, 80.8%, 73.5%) and SPECT/CT (65.9%, 91.8%, 82.1%). Lesion-based optimistic diagnostic test characteristics were: Na[18F]F PET/CT (97.7%, 97.9%, 97.7%), [99mTc]Tc-MDP WBS (39%, 67%, 48.9%), SPECT (52.9%, 93.6%, 67.3%) and SPECT/CT (65.9%, 91.8%, 82.1%). There was no significant difference in the specificity of Na[18F]F and SPECT/CT. All other pairwise comparisons were significant (p<.001). ROC curve analysis showed a high overall accuracy of Na[18F]F with significantly higher AUCs for Na[18F]F PET/CT compared to [99mTc]Tc-MDP WBS, SPECT, and SPECT/CT on both patient and lesion-based analysis (p<.001). Moreover, Na[18F]F PET/CT changed patient management in 38% of patients. CONCLUSIONS: Na[18F]F PET/CT may be the preferred imaging modality for skeletal staging in morbidly obese patients. The technique provides excellent diagnostic test characteristics superior to [99mTc]Tc-MDP bone scan (including SPECT/CT), impacts patient management, has an acceptable radiation exposure profile, and is well-tolerated. Further cost-effectiveness evaluations are warranted.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging.

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. 18F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, 18F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as 18F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

Primary Breast Lymphoma Mimicking Metastatic Breast Cancer on 18F-FDG PET-CT.

18F-Fluorodeoxyglucose (FDG) PET-CT is an excellent imaging modality for the evaluation of non-Hodgkin lymphoma (NHL). We report a case of a 45-year-old woman presented with a large right breast mass and suspicious right axillary lymph nodes referred for 18F-FDG PET-CT for staging. 18F-FDG PET-CT images show large hypermetabolic right breast mass infiltrating the skin, multiple hypermetabolic right axillary and subpectoral lymph nodes, along with multiple hypermetabolic bone lesions at axial and appendicular skeleton. Findings are mimicking primary breast cancer with nodal and bone metastases. Biopsy revealed diffuse large B cell lymphoma. 18F-FDG PETCT is helpful in evaluation of disease extent and response evaluation of primary breast lymphoma.

Rosai-Dorman disease mimicking lymphoma on 18F-FDG PET/CT.

Rosai-Dorman Disease (RDD) is an uncommon benign disorder of proliferative histiocytes. RDD is usually self-remitting yet has been shown to mimic lympho-proliferative disorders clinically as well as on imaging studies. We report a-47-year-old female who was referred to our department with the presenting complaint of bulky abdominopelvic nodal masses suspicious of lymphoma where 18F-FDG PET/CT played a role in the evaluation and staging.

Symptomatic Os Navicular on 99mTc-MDP SPECT/CT.

Os navicular bone is an accessory bone of the foot, which is mainly found on the medial side of the proximal navicular bone. Os navicular bone may be symptomatic and cause medial foot pain. We report a case of a 42-year-old athlete male having right foot pain diagnosed with os navicular syndrome on 99mTc-MDP bone scintigraphy SPECT/CT. We emphasize on the use of SPECT/CT in not only allocating the ossicle anatomically, but also for the purpose of evaluating an active source of pain in a region of multiple complex small bones.

Thyroid Cancer Detected on 68Ga-PMSA PET/CT.

Ga-68 PSMA is a promising radiotracer for both staging and detection of biochemical recurrence in prostate cancer. PSMA is also expressed in the endothelium of tumour-associated neo vasculature of various solid malignancies possibly due to tumour-associated angiogenic factors and endothelial cell sprouting. We report a case of 72-yearold male with known prostate cancer on follow-up with mild increase in serum PSA level. 68Ga-PSMA PET-CT showed large PSMA avid mass in the left thyroid lobe, histopathology revealed papillary carcinoma. 68Ga-PSMA expression in the thyroid carcinoma potentially guide to radionuclide legend therapy with α/ß- emitters specially in iodine refractory cases.

A rare case of Diffuse Large B-Cell Lymphoma of the Prostate on 18F-FDG PET-CT.

18F-Fluorodeoxyglucose (FDG) PET-CT is an excellent imaging modality for the evaluation of Non-Hodgkin lymphoma. We report a case of 65-year-old man with haematuria; rectal examination and ultrasonography revealed prostate mass. Staging 18F-FDG PET-CT images showed a large hypermetabolic, infiltrative prostate mass. Subsequent contrast enhanced CT images showed ill-defined heterogeneously enhancing fungiform mass with irregular outline involving the prostate, base of urinary bladder as well as the seminal vesicles. Biopsy showed diffuse large B cell lymphoma. 18F-FDG PET-CT is helpful in evaluation of disease extent and therapy response.

Incidental brain metastasis of breast cancer detected on 18F-Sodium Fluoride (NaF) PET-CT.

18F- Sodium Fluoride (NaF) is an excellent bone imaging agent used for skeletal staging but can also be localized in extra osseous calcifying lesions. We report a case of a 38-year-old woman with breast carcinoma referred for 18F-NaF PET-CT to evaluate possible metastatic lesions. 18F-NaF PET-CT detected incidental focal soft tissue tracer uptake in the right cerebellum with no sign of calcification seen on CT images. Subsequent MRI show high intensity signal lesion confirming brain metastasis. Extra osseous 18F-NaF uptake may provide important diagnostic information that might alter patient management.

Spectrum of false positive 18F-sodium fluoride (NaF) bone PET/CT findings in Oncology imaging; A narrative pictorial review of cases from a single institution.

Fluorine-18-sodium fluoride (18F-NaF) is a positron emission tomography (PET) bone imaging agent mainly used for oncology staging but may also be used in the evaluation of benign bone and joint pathology conditions. Fluorine-18-NaF is an excellent bone-seeking agent with high bone uptake owing to favorable biodistribution with rapid single-pass extraction, limited plasma protein binding and prompt renal clearance. Fluorine-18-NaF PET/computed tomography (CT) is highly sensitive in identifying both sclerotic and lytic bone metastatic lesions. Occasionally 18F-NaF uptake in benign bone lesions can mimic malignantpathology. In these cases, the pattern of 18F-NaF uptake may elicit a specific diagnosis and correlation with clinical information and morphological information from correlative CT is essential for a correct diagnosis. In the present article, we present a series of clinical cases demonstrating examples of 18F-NaF uptake in benign lesions which can simulate malignant pathology in patients undergoing cancer staging.

Molecular imaging of bone metastases using bone targeted tracers.

Molecular imaging using bone targeted tracers has been used in clinical practice for almost fifty years and still plays an essential role in the diagnosis and follow-up of bone metastases. It includes both [99mTc]bisphosphonates for bone scan and [18F]NaF for positron emission tomography/computed tomography (PET/CT) which are very sensitive to detect osteoblastic activity, but it is important to consider several aspects to increase the specificity of reported findings (such as specific tracer characteristics and mechanism of action, patient's clinical history, common metastatic patterns, changes after treatment, limitations of the technique, variations and pitfalls). This will enable useful information for clinical management being provided in the report. Furthermore, iatrogenic skeletal adverse events are common and they should also be identified, as they have impact on patient's quality of life. This review makes a brief summary of the mechanism of action of bone targeted tracers, followed by a discussion of classic patterns of bone metastasis, treatment response assessment and iatrogenic skeletal complications. The value of hybrid imaging techniques with bone targeted tracers, including single photon emission computed tomography and PET/CT is also explored. The final part summarizes new bone targeted tracers with superior imaging characteristics that are being developed, and which may further enhance the applications of radionuclide bone imaging.

Assessment of regional and total skeletal metabolism using 18F-NaF PET/CT in patients with chronic kidney disease.

OBJECTIVE: The study aims to assess regional and total bone metabolic activity in patients with chronic kidney disease using Na[18F]F PET and correlation between semi-quantitative indices and blood parameters. METHODS: Seventy-two subjects (mean age 61.8 ± 13.8 years) were included. Of these 24/72 patients had end-stage renal disease (ESRD) (GFR < 15 mL/min/1.73 m2), 38/72 had chronic kidney disease (CKD) (GFR between 60 and 15 mL/min/1.73 m2), and 10/72 were controls with normal renal function. All subjects underwent Na[18F]F PET-CT with a dose activity of 0.06 mCi/Kg. Regional and total skeletal metabolism were assessed with mean SUVs in a skeletal volume of interest (VOI), bone to soft tissue index (B/S), global SUV mean (GSUV mean) of the whole bone, and uptake in the femoral neck. RESULTS: Statistically significant differences were observed in a number of 18F-NaF metrics like femoral neck metabolism in CKD and ERSD groups in comparison to control in right (P = 0.003) and left femur (P = 0.006), bone to soft tissue index in the femur (P = 0.016) and GSUV5 (P = 0.006). There is also a significant difference in SUV mean in lumbar vertebrae (L1-L4) among CKD, ESRD, and controls. There was a moderate correlation between 18F-NaF PET scan uptake and blood parameters such as ALP and PTH. Na[18F]F uptake parameters were significantly different in low versus high bone turnover state. CONCLUSIONS: The assessment of total skeleton and regional metabolism and bone turnover in CKD patients is feasible with Na[18F]F PET. Na[18F]F can help to detect early changes in bone metabolism and assess the progression of bone disease in this complex condition. Quantification with Na[18F]F PET might provide better assessment of the bone turnover. The difference in Na[18F]F uptake in CKD compared to controls is likely related to a change in bone turnover which, however, requires further validation.