BACKGROUND: There is growing interest in the development and application of standardized imaging criteria (SIC), to minimize variability and improve the reproducibility of image interpretation in head and neck squamous cell carcinoma (HNSCC).
METHODS: \"Squamous cell carcinoma\" AND \"standardized interpretation criteria\" OR \"radiographic response assessment\" were searched using PubMed and Google Scholar for articles published between 2009 and 2024, returning 56 publications. After abstract review, 18 were selected for further evaluation, and 6 different SICs (i.e., PERCIST, Porceddu, Hopkins, NI-RADS, modified Deauville, and Cuneo) were included in this review. Each SIC is evaluated in the context of 8 desired traits of a standardized reporting system.
RESULTS: Two SICs have societal endorsements (i.e., PERCIST, NI-RADS); four can be used in the evaluation of locoregional and systemic disease (i.e., PERCIST, Hopkins, NI-RADS, Cuneo), and four have specific categories for equivocal imaging results (i.e., Porceddu, NI-RADS, modified Deauville, and Cuneo). All demonstrated areas for future improvement in the context of the 8 desired traits.
CONCLUSIONS: Multiple SICs have been developed for and demonstrated value in HNSCC post-treatment imaging; however, these systems remain underutilized. Selecting an SIC with features that best match the needs of one\'s practice is expected to maximize the likelihood of successful implementation.

This case report details a rare instance of rapid iris metastasis from esophageal cancer in a 59-year-old man. A literature review was conducted to explore recent advances in detecting, diagnosing, and treating intraocular metastatic malignancies. Positron emission tomography-computed tomography played a crucial role in identifying primary sites and systemic metastases. Local treatment combined with systemic therapy effectively reduced tumor size, preserved useful vision, and improved the patient\'s survival rate. A comparison was made of the characteristics of iris metastases from esophageal cancer and lung cancer, including age, gender, tumor characteristics, and treatment. The challenges associated with diagnosis and treatment are discussed, highlighting the implications for clinical practice.

Prostate-specific membrane antigen (PSMA) targeted tracers show increased uptake in several malignancies, indicating a potential for peptide radioligand therapy. Intra-arterial injection of radiotracers can increase the therapeutic window. This study aimed to evaluate the feasibility of intra-arterial injection of [68Ga]Ga-PSMA-11 for intrahepatic cholangiocarcinoma and compare tracer uptake after intrahepatic arterial injection and intravenous injection. Three patients with intrahepatic cholangiocarcinoma received [68Ga]Ga-PSMA-11 through a hepatic arterial infusion pump, followed by positron emission tomography/computed tomography (PET/CT). Two-three days later, patients underwent PET/CT after intravenous [68Ga]Ga-PSMA-11 injection. All tumours showed higher uptake on the intra-arterial scan compared with the intravenous scan: the intra-arterial / intravenous standardised uptake value normalised by lean body mass ratios were 1.40, 1.46, and 1.54. Local intra-arterial PSMA injection is possible in patients with intrahepatic cholangiocarcinoma. Local injection increases tumour-to-normal tissue ratios, increasing the therapeutic window for theranostic applications. RELEVANCE STATEMENT: Intra-arterial Prostate specific membrane antigen (PSMA) injection increases the therapeutic window for potential theranostic application in intrahepatic cholangiocarcinoma. KEY POINTS: Three patients with intrahepatic cholangiocarcinoma underwent PET/CT after intra-arterial and intravenous injection of [68Ga]Ga-PSMA-11. Intra-arterial injection showed higher uptake than intravenous injection. PSMA-targeted imaging could be valuable for a subset of intrahepatic cholangiocarcinoma patients.

OBJECTIVE: [18F]Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a non-invasive imaging modality used in the differential diagnosis of splenic lesions, although ideal parameters and thresholds remain unclear. The present study evaluated the ability of [18F]FDG PET/CT, including its visual and quantitative parameters, to differentiate between benign and malignant splenic lesions.
METHODS: Patients who underwent [18F]FDG PET/CT following the detection of splenic lesions on contrast-enhanced CT were retrospectively analysed. Visual parameters assessed on [18F]FDG PET/CT included whole spleen uptake intensity, lesion multiplicity, and lesion uptake, and quantitative parameters included maximum standardised uptake value (SUVmax), lesion-to-background ratio (LBR), metabolic tumour volume (MTV), total lesion glycolysis (TLG), and lesion size. Parameters differentiating between benign and malignant lesions were evaluated by Pearson\'s chi-square test, Mann-Whitney U-test, and receiver operating characteristics (ROC) curve analysis.
RESULTS: Splenic lesion uptake (p = 0.001) was the only visual parameter significantly distinguishing between benign and malignant lesions. ROC curve analysis demonstrated that SUVmax had the largest area under the ROC, 0.91 (p < 0.001), with an optimal cut-off > 5.3 having a sensitivity of 90.3% and a specificity of 80.6%. Subgroup analysis of malignant lesions showed that SUVmax (p = 0.013), LBR (p = 0.012), and TLG (p  = 0.034) were significantly higher in splenic lymphomas than in splenic metastases.
CONCLUSIONS: Of the [18F]FDG PET/CT parameters investigated, SUVmax had the highest accuracy in diagnosing malignant splenic lesions and was significantly higher in splenic lymphomas than in splenic metastases. Visual determination of [18F]FDG uptake by splenic lesions may be an easily evaluated parameter.
CONCLUSIONS: SUVmax and visual grade of [18F]FDG PET/CT help to differentiate spleen lesions. [18F]FDG PET/CT is useful for discriminating between benign and malignant spleen lesions.
CONCLUSIONS: Many splenic lesions are difficult to diagnose on anatomical imaging, with histopathologic analyses are required. SUVmax of PET/CT provided the diagnostic ability to differentiate between benign and malignant splenic lesions. More than normal spleen uptake can be a convenient parameter to diagnose malignant spleen lesions.

The metastatic lesions to pancreas are reported in various malignancies. However, pancreatic metastasis from breast cancer is rare and difficult to diagnose due to nonspecific symptoms and imaging findings. At the time of diagnosis, there may already be an associated widespread metastasis. In this case report, a woman in her forties with a history of breast cancer was found to have widespread metastases, including in the pancreas. The patient was treated with chemotherapy and hormonal therapy.

A 75-year-old male with head-and-neck squamous cell cancer received a staging f-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) scan which showed additional focal abnormal uptake in the right hepatic lobe. The patient was treated for probable metastatic disease. Restaging FDG PET/CT scan revealed resolution of uptake in the head-and-neck and persistent focal uptake in the presumed liver metastasis. An abdominal CT with intravenous contrast revealed an enhancing mass in the gallbladder, without extension into the liver. Cholecystectomy revealed an intracholecystic papillary neoplasm of the gallbladder. The initial appearance of hepatic metastasis was due to a misregistration artifact.

BACKGROUND: Giant cell tumor of bone is a locally aggressive and rarely metastasizing tumor, and also a potential malignant tumor that may develop into a primary malignant giant cell tumor.
OBJECTIVE: To evaluate the role of multimodal imaging in the diagnosis of giant cell tumors of bone.
METHODS: The data of 32 patients with giant cell tumor of bone confirmed by core-needle biopsy or surgical pathology at our hospital between March 2018 and March 2023 were retrospectively selected. All the patients with giant cell tumors of the bone were examined by X-ray, computed tomography (CT) and magnetic resonance imaging (MRI), and 7 of them were examined by positron emission tomography (PET)-CT.
RESULTS: X-ray imaging can provide overall information on giant cell tumor lesions. CT and MRI can reveal the characteristics of the internal structure of the tumor as well as the adjacent relationships of the tumor, and these methods have unique advantages for diagnosing tumors and determining the scope of surgery. PET-CT can detect small lesions and is highly valuable for identifying benign and malignant tumors to aid in the early diagnosis of metastasis.
CONCLUSIONS: Multimodal imaging plays an important role in the diagnosis of giant cell tumor of bone and can provide a reference for the treatment of giant cell tumors.

OBJECTIVE: To investigate the potential utility of [18F]fibroblast activation protein inhibitor (FAPI) positron emission tomography/computed tomography (PET/CT) for evaluating pulmonary artery (PA) masses, and compare it with [18F]fluorodeoxyglucose (FDG) PET/CT.
METHODS: Participants with clinically suspected PA malignancy were prospectively enrolled and underwent dual-tracer PET/CT ([18F]FAPI-42 and [18F]FDG) imaging. Visual analysis and semi-quantitative parameters were compared between the two types of radiotracers. The tissue specimen underwent immunohistochemical staining to verify FAP expression in the tissue.
RESULTS: Thirty-three patients (18 males/15 females; mean age 53.1 ± 15.4 years) were enrolled. All 21 patients with malignant PA masses were FDG-positive (100%), whereas 20 out of 21 patients were FAPI-positive (95.2%). All 12 patients with benign PA masses were both negative in FDG and FAPI PET. The mean maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR) of FAPI and FDG in malignant PA masses were significantly higher than those of benign masses. Although there was no significant difference in SUVmax between FDG and FAPI in malignant PA masses (11.36 vs. 9.18, p = 0.175), the TBR (liver) and TBR (left ventricle) were more favorable for FAPI than for FDG (13.04 vs. 5.17, p < 0.001); (median: 7.75 vs. 2.75, p = 0.007). Immunohistochemical analysis (n = 16) validated that the level of FAP expression corresponded strongly to the uptake of FAPI in PET/CT scans (rs = 0.712, p = 0.002). For clinical management, FAPI PET found more metastatic lesions than FDG PET in 4 patients, with 2 patients upgrading and 1 patient changing treatment decisions.
CONCLUSIONS: FAPI PET/CT is feasible in the diagnosis of PA masses. Although not superior to FDG PET/CT, FAPI PET/CT showed better target-to-background contrast.
CONCLUSIONS: This study found that FAPI PET/CT is not superior to FDG PET/CT in diagnosing PA masses, but FAPI PET/CT displays better target-to-background contrast and more positive lesions, which may help improve disease management.
CONCLUSIONS: Pulmonary malignancies lack specificity in clinical manifestations, laboratory tests, and routine imaging examinations. FAPI PET/CT is not diagnostically better than FDG PET/CT but displays better target-to-background contrast and more positive lesions. Dual-tracer PET/CT ([18F]FAPI-42 and [18F]FDG) imaging improves clinical management of pulmonary artery masses.

Artifacts in nuclear medicine imaging are not uncommon. We are aware of some of these, for which we follow necessary protocols to avoid them. However, there are some unusual and unavoidable artifacts that we come across in daily imaging, which may be of concern and need to be detected and corrected on time. Hence, sharing a few such unusual artifacts we encountered while performing routine studies on positron emission tomography-computed tomography and gamma cameras, evaluating the cause and possible precautions.

OBJECTIVE: Somatostatin receptor positron emission tomography/computed tomography (SSTR-PET/CT) using [68Ga]-labeled tracers is a widely used imaging modality for neuroendocrine tumors (NET). Recently, [18F]SiTATE, a SiFAlin tagged [Tyr3]-octreotate (TATE) PET tracer, has shown great potential due to favorable clinical characteristics. We aimed to evaluate the reproducibility of Somatostatin Receptor-Reporting and Data System 1.0 (SSTR-RADS 1.0) for structured interpretation and treatment planning of NET using [18F]SiTATE.
METHODS: Four readers assessed [18F]SiTATE-PET/CT of 95 patients according to the SSTR-RADS 1.0 criteria at two different time points. Each reader evaluated up to five target lesions per scan. The overall scan score and the decision on peptide receptor radionuclide therapy (PRRT) were considered. Inter- and intra-reader agreement was determined using the intraclass correlation coefficient (ICC).
RESULTS: The ICC analysis on the inter-reader agreement using SSTR-RADS 1.0 for identical target lesions (ICC ≥ 85%), overall scan score (ICC ≥ 90%), and the decision to recommend PRRT (ICC ≥ 85%) showed excellent agreement. However, significant differences were observed in recommending PRRT among experienced readers (ER) (p = 0.020) and inexperienced readers (IR) (p = 0.004). Compartment-based analysis demonstrated good to excellent inter-reader agreement for most organs (ICC ≥ 74%), except for lymph nodes (ICC ≥ 53%).
CONCLUSIONS: SSTR-RADS 1.0 represents a highly reproducible and consistent framework system for stratifying SSTR-targeted PET/CT scans, even using the novel SSTR-ligand [18F]SiTATE. Some inter-reader variability was observed regarding the evaluation of uptake intensity prior to PRRT as well as compartment scoring of lymph nodes, indicating that those categories require special attention during further clinical validation and might be refined in a future SSTR-RADS version 1.1.
CONCLUSIONS: SSTR-RADS 1.0 is a consistent framework for categorizing somatostatin receptor-targeted PET/CT scans when using [18F]SiTATE. The framework serves as a valuable tool for facilitating and improving the management of patients with NET.
CONCLUSIONS: SSTR-RADS 1.0 is a valuable tool for managing patients with NET. SSTR-RADS 1.0 categorizes patients with showing strong agreement across diverse reader expertise. As an alternative to [68Ga]-labeled PET/CT in neuroendocrine tumor imaging, SSTR-RADS 1.0 reliably classifies [18F]SiTATE-PET/CT.