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RATIONALE AND OBJECTIVES: PET-CT is extensively used in the diagnosis of pheochromocytoma (PHEO). However, various PET-CT tracers are recommended for the diagnosis of PHEO. Therefore, this study evaluated the diagnostic performance of all tracers currently used in the PET-CT detection of PHEO. METHODS: Studies were retrieved from PubMed, Web of Science, Embase, and Cochrane Library from inception to Feb. 7, 2024. The studies were screened according to the eligibility criteria and the data were extracted. Quality of the included studies was evaluated by the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic (sROC) curve (AUC) were pooled in Stata 15, and diagnostic accuracy was pooled in R 4.3.3. RESULTS: Sixteen studies were included in the meta-analysis. The sensitivity and specificity of [18 F]FDOPA PET/CT for initial PHEO diagnosis were 97% (95% CI: 91%-99%, I2 = 46.14%, p > 0.01) and 94% (95% CI: 86%-98%, I2 = 87.90%, p < 0.01), respectively. The AUC was 0.99 (95% CI: 0.98-1.00). The diagnostic accuracy of [18 F]FDOPA PET/CT was 98.9% (95% CI: 95%-100%) for PHEO patients and 89.7% (95% CI: 85.4%-92.8%) for PHEO lesions. [68Ga]DOTATATE PET/CT had a diagnostic accuracy of 86.9% (95% CI: 78.2%-93.9%) for PHEO and 87.5% (95% CI: 70.3%-95.4%) for PHEO lesions. FDG PET/CT had a diagnostic accuracy of 85.2% (95% CI: 73.6%-94.1%) for PHEO and 86.8% (95% CI: 73%-94.2%) for PHEO lesions. [68Ga]DOTANOC PET/CT had a diagnostic accuracy of 79.3% (95% CI: 49.2%-98.3%) for PHEO. CONCLUSIONS: In general, PET/CT demonstrates superior performance in the diagnosis of PHEO. In addition, [18 F]FDOPA PET/CT has the best diagnostic performance in PHEO compared with other tracers. Given the limited research on other PET/CT tracers and the potential constraints on their widespread use, additional multicenter and multiregional studies are warranted to further evaluate their diagnostic performance and provide recommendations for clinical use.

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OBJECTIVES: To develop and identify machine learning (ML) models using pretreatment 2-deoxy-2-[18F]fluoro-D-glucose ([18F]-FDG)-positron emission tomography (PET)-based radiomic features to differentiate benign from malignant parotid gland diseases (PGDs). MATERIALS AND METHODS: This retrospective study included 62 patients with 63 PGDs who underwent pretreatment [18F]-FDG-PET/computed tomography (CT). The lesions were assigned to the training (n = 44) and testing (n = 19) cohorts. In total, 49 [18F]-FDG-PET-based radiomic features were utilized to differentiate benign from malignant PGDs using five different conventional ML algorithmic models (random forest, neural network, k-nearest neighbors, logistic regression, and support vector machine) and the deep learning (DL)-based ensemble ML model. In the training cohort, each conventional ML model was constructed using the five most important features selected by the recursive feature elimination method with the tenfold cross-validation and synthetic minority oversampling technique. The DL-based ensemble ML model was constructed using the five most important features of the bagging and multilayer stacking methods. The area under the receiver operating characteristic curves (AUCs) and accuracies were used to compare predictive performances. RESULTS: In total, 24 benign and 39 malignant PGDs were identified. Metabolic tumor volume and four GLSZM features (GLSZM_ZSE, GLSZM_SZE, GLSZM_GLNU, and GLSZM_ZSNU) were the five most important radiomic features. All five features except GLSZM_SZE were significantly higher in malignant PGDs than in benign ones (each p < 0.05). The DL-based ensemble ML model had the best performing classifier in the training and testing cohorts (AUC = 1.000, accuracy = 1.000 vs AUC = 0.976, accuracy = 0.947). CONCLUSIONS: The DL-based ensemble ML model using [18F]-FDG-PET-based radiomic features can be useful for differentiating benign from malignant PGDs. The DL-based ensemble ML model using [18F]-FDG-PET-based radiomic features can overcome the previously reported limitation of [18F]-FDG-PET/CT scan for differentiating benign from malignant PGDs. The DL-based ensemble ML approach using [18F]-FDG-PET-based radiomic features can provide useful information for managing PGD.

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PURPOSE: The objective of this study is to assess the prognostic efficacy of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET-CT) parameters in nasopharyngeal carcinoma (NPC) and identify the best machine learning (ML) prognostic model for NPC patients based on these 18F-FDG PET/CT parameters and clinical variables. METHOD: A cohort of 678 patients diagnosed with NPC between 2016 and 2020 was analyzed in this study. The model was constructed using four advanced ML algorithms, namely Random Forest (RF), Extreme Gradient Boosting (XGBoost), Least Absolute Shrinkage and Selection Operator (LASSO), and multifactor COX step-up regression. Statistical significance of the models was assessed using Kaplan-Meier (K-M) curves, with a significance level established at P < 0.05. The prognostic efficacy of the models was evaluated through the analysis of receiver operating characteristic (ROC) curves, with the area under the ROC curve (AUC) serving as a criterion for model selection. The decision curve analysis (DCA) and concordance index (C-index) were employed to assess the precision of the optimal model. RESULTS: Multivariate analysis revealed age, T stage, and metabolic tumor volume (MTV) for the primary nasopharyngeal tumor (MTVT) as significant independent prognostic factors for overall survival (OS) in NPC patients. Additionally, the LASSO model identified six key variables, including peak standardized uptake value (SUV-peak) for the primary nasopharyngeal tumor (SUV-peak(T)), MTVT, heterogeneity index for neck lymph nodes (HIN), age, pathological type, and T stage. Remarkably, the LASSO model demonstrated superior performance with a 5-year AUC of 0.849 compared to other models. Further assessment using the C-index and DCA confirmed the accuracy of the LASSO model. Subgroup analysis revealed notable risk factors, such as a high heterogeneity index (HI) for the primary nasopharyngeal tumor (HIT), MTV values for neck lymph nodes (MTVN), and HIN. CONCLUSIONS: We developed a novel prognostic machine learning model that integrates 18F-FDG PET-CT parameters and clinical characteristics, significantly enhancing prognosis prediction in NPC.

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Purpose: PET/CT-based Deauville scoring (DS) is routinely used for lymphoma response assessment. However, pathological correlation of DS is not yet precisely documented. In the present study we aimed to pathological confirm the PET/CT-based Deauville scoring (DS) in lymphoma after first-line chemotherapy. Materials and methods: Participants undergoing PET/CT for response assessment following first-line treatment were recruited prospectively. DS ≥ 4 lesions were interpreted as PET-positive, while DS ≤ 3 as PET-negative. Participants with a PET-positive lesion or suspicious of inadequate response (DS ≤ 3) were recruited for metabolic core-needle biopsy. True-negative and benign histopathology were kept on follow-up for three months. Histopathological, clinical and imaging findings were assessed for diagnostic performance. Procedure-related complications were also noted. Results: In all, 148/480 participants were PET-positive, and 332/480 were PET-negative. 138/148 PET-positive and 12/332 PET-negative lesions were recruited for biopsy. Biopsy was performed in 147/150 participants (PET-positive 135; PET-negative 12). Three patients with inaccessible lesions were excluded. The diagnostic yield of the procedure was 97.3% (143/147). Histology revealed lymphoma in 106 participants (including 70% of total DS-4, 100% of DS-5a and 73.9% of DS-5b lesions), with three false-negative lesions. DS ≤ 3 lesions were true-negative except one diagnosed with lymphoma (8.3%) on follow-up. Non-lymphomatous malignancies (n = 5), granulomas (n = 12), non-specific inflammation (n = 9) and no residual disease (n = 11) were diagnosed in the rest. No major procedure-related adverse event was noted. Conclusion: A DS-5a lesion suggests residual disease; hence, a biopsy can be prevented unless Richter's transformation is suspected. DS-4 and DS-5b lesions require a biopsy before changing the treatment plan, as a certain number of participants had non-lymphomatous F-18 FDG-avid lesions.

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Objectives: This study aimed to evaluate the performance of prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) in comparison to multiparametric magnetic resonance imaging (mpMRI) for detecting biochemical recurrence of prostate cancer (PCa). Materials and methods: We conducted a comprehensive search for articles published in PubMed, Web of Science, Embase, and the Cochrane Library, spanning the inception of the database until October 26, 2022, which included head-to-head comparisons of PSMA PET/CT and mpMRI for assessing the biochemical recurrence of PCa. Results: A total of 5 studies including 228 patients were analyzed. The overall positivity rates of PSMA PET/CT and mpMRI for detecting biochemical recurrence of PCa after final treatment were 0.68 (95% confidence interval [CI], 0.52-0.89) and 0.56 (95% CI, 0.36-0.88), respectively. The positivity rates of PSMA PET/CT and mpMRI for detecting local recurrence, lymph node metastasis, and bone metastases were 0.37 (95% CI, 0.30-0.47) and 0.38 (95% CI, 0.22-0.67), 0.44 (95% CI, 0.35-0.56) and 0.25 (95% CI, 0.17-0.35), and 0.19 (95% CI, 0.11-0.31) and 0.12 (95% CI, 0.05-0.25), respectively. Compared with mpMRI, PSMA PET/CT exhibited a higher positivity rate for detecting biochemical recurrence and lymph node metastases, and no significant difference in the positivity rate of local recurrence was observed between these 2 imaging modalities. Conclusions: Compared with mpMRI, PSMA PET/CT appears to have a higher positivity rate for detecting biochemical recurrence of PCa. Although both imaging methods showed similar positivity rates of detecting local recurrence, PSMA PET/CT outperformed PSMA PET/CT in detecting lymph node involvement and overall recurrence.

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We present the imaging findings of a 44-year-old female patient who was diagnosed with nasopharyngeal carcinoma (NPC) extending from the nasopharynx to the external auditory canal (EAC) through the Eustachian tube (ET). The patient presented with a left neck submandibular lump on initial presentation that showed NPC upon fine needle aspiration, leading to chemoradiotherapy. Despite treatment, the patient experienced multiple relapses and later presented with aural symptoms, including left ear pain, foul-smelling drainage, and trismus on recurrence, and was subsequently diagnosed through biopsy. CT, MRI, and PET-CT scans revealed an extensive infiltrative nasopharyngeal mass extending into the left ET, involving the EAC. This rare case highlights the importance of considering the extension of NPC into the EAC as a potential etiology in patients who present with aural symptoms.

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Skull base metastases, including those from small-cell lung carcinoma (SCLC), can present with various syndromes depending on the site of involvement, such as orbital syndrome, parasellar syndrome, middle fossa syndrome, jugular foramen syndrome, and occipital condyle syndrome (OCS). One such example is OCS, which consists of unilateral occipital headache accompanied with ipsilateral hypoglossal palsy. This case report describes a 51-year-old man initially diagnosed with OCS, which led to the discovery of systemic bone metastases from SCLC. Magnetic resonance imaging showed lesions in the occipital condyle and hypoglossal canal, while positron emission tomography-computed tomography identified a lung mass and widespread metastases. SCLC is highly aggressive and metastatic, with the bone being a common site of spread. In this case, the OCS preceded the diagnosis of the underlying malignancy. Prompt diagnosis and treatment are crucial, as patients with OCS often have advanced disease. This case highlights the importance of considering SCLC as a potential etiology for OCS, given the propensity for bone metastases. Early recognition and evaluation of OCS is essential to initiate appropriate management.

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Objective: To compare costs between treatment strategies employed prior to and after prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) via the Brazilian Unified Health Care System and their impact on the therapeutic management of biochemical recurrence of prostate cancer. Materials and Methods: The referring physicians were surveyed on their treatment intentions (strategies) at two different time points: prior to and after PSMA PET/CT. Cost comparison results are presented as median (IQR) for each of the two strategies. The shift in therapeutic management after PSMA PET/CT was also analyzed. Results: The study sample included 59 patients (mean age: 65.9 years). The PSMA PET/CT result was considered positive in 38 patients (64.4%) and was found to have an impact on the treatment strategy in for 36 patients (61.0%). Prior to PSMA PET/CT, salvage therapy (i.e., treatment with curative intent) was the intended treatment for most patients, and that was significantly less so after the examination (76.3% vs. 45.8%; p < 0.001). Conversely, a strategy involving systemic (i.e., palliative) therapy became more common after PSMA PET/CT (23.7% vs. 54.2%; p < 0.001). The after-PSMA PET/CT strategy presented higher overall costs than did the before-PSMA PET/CT strategy, in all scenarios evaluated. In all scenarios, nearly half of this cost difference was related to the cost of the PSMA PET/CT itself, the remainder being related to the new treatment choices that stemmed from knowledge of the PSMA PET/CT findings. Conclusion: For patients treated within the Brazilian Unified Health Care System, PSMA PET/CT presented higher costs in comparison with conventional imaging methods. Adding PSMA PET/CT to the workflow had an impact on therapeutic management, mainly representing a shift from futile curative treatments to systemic palliative ones. The amount of funds that could potentially be saved by not providing such futile treatments would suffice to evaluate roughly two patients with PSMA PET/CT scans for each futile treatment strategy avoided.

Objetivo: Comparar custos entre estratégias antes e após o exame de PET/CT-PSMA da perspectiva do Sistema Único de Saúde e seu impacto no manejo terapêutico para pacientes com recidiva bioquímica de câncer de próstata. Materiais e Métodos: Os médicos solicitantes informaram a intenção terapêutica em dois momentos: antes e após o exame. Os resultados de comparação de custo estão apresentados como medianas de custo (p25; p75). A mudança na intenção terapêutica também foi analisada. Resultados: O estudo envolveu 59 pacientes (idade média: 65,9 anos). A PET/CT-PSMA foi considerada positiva em 38 dos 59 pacientes (64.4%). O exame impactou a estratégia de tratamento para 36 pacientes (61%). Antes da obtenção das informações da PET/CT-PSMA, a terapia de resgate (i.e., com intenção curativa) era o tratamento sugerido para a maioria dos pacientes, e após o exame, reduziu significativamente (76,3% vs 45,8%; p < 0,001). Em contrapartida, a terapia sistêmica (i.e., paliativa) aumentou como intenção de tratamento após o exame (23,7% vs 54,2%; p < 0,001). A estratégia "após PET/CT-PSMA" apresentou maiores custos em relação à estratégia "antes da PET/CT-PSMA" nos cenários comparados. Cerca de metade da diferença de custos entre as duas estratégias foi relacionada aos custos do exame propriamente ditos, enquanto a outra metade foi relacionada às novas escolhas de tratamento a partir do exame. Conclusão: Oferecer a PET/CT-PSMA no Sistema Único de Saúde apresentou maiores custos em relação à estratégia com métodos de imagem convencionais e impactou o manejo terapêutico, pelo favorecimento de tratamentos sistêmicos paliativos no lugar de tratamentos curativos fúteis. A quantidade de recursos que poderiam ser poupados ao evitar tratamentos fúteis seria suficiente para avaliar aproximadamente dois pacientes com exames de PET/CT-PSMA para cada estratégia de tratamento fútil evitada.

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We present a rare case of mediastinal capillary hemangioma in a 54-year-old female. She presented with back pain in the left suprascapular region, and the chest radiograph revealed left pleural effusion. On further workup with high-resolution computed tomography (CT) chest, a hypervascular pleural-based neoplastic lesion in the left upper hemithorax with gross left pleural effusion and subtotal collapse of the left lung was identified. 18F-fluorodeoxyglucose positron emission tomography/CT was suggestive of a weakly metabolic well-defined pleural-based soft tissue lesion in the left upper hemithorax along the mediastinal side. Neuroendocrine tumor was suspected. 68Ga-DOTATATE PET/CT was advised, which showed intense uptake in the lesion. The mass was resected completely. Histopathological examination established the final diagnosis as benign vascular tumor consistent with a capillary hemangioma.

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Neuroblastoma presenting with multiple muscles and subcutaneous tissue metastases is rarely reported in the literature. We would like to highlight such infrequent occurrences for increasing the clinical acumen of the medical fraternity with an aim to deliver proper therapy to patients.

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Objective: Biochemical recurrence (BCR) after initial management of Prostate Carcinoma (PC) is frequent. Subsequent interventions rely on disease burden and metastasis distribution. 68Ga prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) is an excellent imaging modality in BCR. However, 68Ga is radionuclide generator produced and has restricted availability. 99mTc-labeled PSMA could be a potential cost-effective alternative. We compared the performance of 99mTc-PSMA single-photon emission CT (SPECT)/CT and 68Ga-PSMA PET/CT in BCR with a serum prostate surface antigen (PSA) level of <20 ng/mL. Materials and Methods: The prospective study included 25 patients with BCR and at least one lesion on a 68Ga-PSMA PET/CT. All patients underwent 99 mTc-PSMA SPECT/CT, and disease distribution and metastatic burden were compared with 68Ga-PSMA PET/CT. The maximum standard uptake value (SUVmax) and the tumor-to-background ratio (TBR) were computed and analyzed. Results: The mean age and serum PSA (SPSA) were 69.72 ± 6.69 years and 5.65 ± 6.07 ng/mL. Eleven patients (44%) had SPSA ≤2 ng/mL. Recurrent sites were noted in the prostate (19, 76%), prostatic bed (3, 12%), and pelvis lymph nodes (LNs) (13, 52%). Distant metastasis to bones (13, 52%), lungs (5, 20%), and retroperitoneal LNs (2, 8%) were noted. Both modalities were concordant for the recurrent disease at the prostate, prostatic bed, bone, and lung lesions. 99mTc-PSMA could localize pelvis LNs in most patients (10/13, 76.9%). The site-specific sensitivity and specificity between the two modalities were not significantly different (P > 0.05). TBR shows excellent correlation with SUVmax (0.783, P < 0.001). Four (16%) patients were understaged with 99mTc-PSMA due to the nonvisualization of the subcentimeter size LNs. No patient with systemic metastases was understaged. Conclusions: 99mTc-PSMA SPECT/CT has good concordance with 68Ga-PSMA PET/CT in BCR, even at low PSA levels. However, it may miss a few subcentimeter LNs due to lower resolution. 99mTc-PSMA SPECT/CT could be a simple, cost-effective, and readily available imaging alternative to PET/CT.

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Thyroid gland metastases from nonthyroidal malignancies are extremely rare. The most common primary malignancies associated with metastasis to thyroid gland include renal cell carcinoma, colorectal carcinoma, lung cancer, and breast cancer. Metastasis to thyroid rarely arises from primary laryngeal cancer. The presence of metastasis to thyroid gland is invariable and associated with poor prognosis and thus, should be differentiated from primary thyroid malignancy. Hereby, we have one such case of metastasis to thyroid gland from laryngeal cancer diagnosed on 18F-fluorodeoxyglucose positron emission tomography/computed tomography scan.

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Primary central nervous system lymphoma (PCNSL) is a rare, aggressive variant of extranodal non-Hodgkin's lymphoma. Although gadolinium-enhanced magnetic resonance imaging remains the initial imaging modality of choice, a whole-body F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography is imperative to exclude systemic lymphomatous involvement. Furthermore, the metabolic parameter, maximum standardized uptake value (SUVmax) of the lesion, tumor-to-normal cerebral tissue SUVmax ratio, and FDG uptake patterns help in differentiating intracranial lymphomas from High-grade Glioblastoma Multiforme (HGM) and infectious lesions, and hence, consolidating the diagnosis. In this pictorial essay, we present a series of PCNSL cases, representing the different imaging characteristics and metabolic uptake patterns.

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Extracranial metastasis from high-grade glial tumors is an extremely rare condition with its reported incidence being <1%. The most common sites reported in the literature are leptomeninges and spinal cord, followed by the liver, lung, and skeletal system. Its low incidence is thought to be related to the intrinsic aggressive biology of the tumor, thus reducing median overall survival in patients. As there is lack of knowledge about the mechanism of extracranial spread of glioma cells, its diagnosis and management remain a major challenge. We report two cases of extracranial metastases from glial tumors to cervical nodes and postoperative site involving preauricular region detected on F18 Fluoro ethyl tyrosine (FET) positron emission tomography-computed tomography and later on confirmed with histopathology Fluoro ethyl tyrosine.

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A diverticulum is an outpouching of a hollow (or fluid-filled) structure in the body. They are most commonly seen in the urinary bladder, intestine, and pharyngeal region and are rarely seen in renal calyces. They are usually benign, asymptomatic, and are coincidentally detected. Due to their nonspecific clinical and radiological picture, sometimes they mimic malignant tumors, leading to misdiagnosis and treatment. We are presenting a case of 60-year-old female with right breast carcinoma, on whole body 18-fluorodeoxyglucose positron emission tomography-computed tomography; we observed an interesting finding in the right renal region mimicking renal metastasis.

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Purpose: The blur introduced by breathing motion degrades the diagnostic accuracy of whole-body F-18 fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) in lesions adjacent to the diaphragm by increasing the apparent size and by decreasing their metabolic activity. This study aims to evaluate the efficacy of motion correction by four-dimensional phase-based respiratory-gated (RG) 18F-FDG PET-CT in improving metabolic parameters of lesions adjacent to the diaphragm (especially in the lungs or liver). Materials and Methods: Eighteen patients with known lung or liver lesions underwent conventional 18F-FDG PET-CT and respiratory-gated PET-CT acquisition of the desired region using a pressure-sensing, phase-based respiratory-gating system. Maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were obtained for these lesions from gated and nongated PET-CT images for analysis. Furthermore, a visual analysis of lesions was done. Statistics: Statistical significance of the RG image parameters was assessed by the two-tailed paired Student's t test and confirmed with the robust nonparametric Wilcoxon's signed-rank test (two-tailed asymptotic). Results: There was an overall significant increase in SUVmax (P 0.001) in all gating methods with a percentage increase maximum of about 18.13%. On gating methods, MTV decreased significantly (P = 0.001) than that of nongating method (maximum reduction of about 32.9%). There was a significant difference (P = 0.02) in TLG between gated and nongated methods. Conclusion: Motion correction with phase-based respiratory gating improves the diagnostic value of 18F-FDG PET-CT imaging for lung and liver lesions by more accurate delineation of the lesion volume and quantitation of SUV and can thus impact staging, diagnosis as well as management in selected patients.

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Ga-68 labeled prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT) is increasingly recognized as the best imaging modality for disease staging and detection of recurrent prostate cancer. Despite its name, PSMA expression has been reported in the neovasculature of several nonprostatic benign and malignant pathologies. Docetaxel, a taxane antineoplastic agent, is the mainstay of treatment in castration-resistant prostate cancer and high-volume hormone-sensitive prostate cancer. Although the occurrence of docetaxel-related interstitial lung disease is rare, it may lead to respiratory failure if treatment is delayed. We present a case of metastatic castration-resistant prostate cancer, wherein docetaxel-induced interstitial pneumonitis was detected on Ga-68 PSMA PET/CT after docetaxel administration.

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Background: As constituents of the reticuloendothelial system, the spleen and bone marrow (BM) have been recognized as integral components of the systemic inflammatory response in cancer contexts, thereby serving as predictive indicators for assessing cancer prognosis. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has attained widespread utilization for staging, assessing treatment response, and prognostication in lymphoma patients. Several investigations have proposed that focal increased 18F-FDG uptake in the BM or spleen may correlate with malignant involvement in lymphoma. However, scant data exist regarding the implications of diffuse BM and splenic uptake. This study aimed to explore the relationships between metabolic parameters of the spleen and BM on 18F-FDG PET/CT and inflammatory markers, and to assess their prognostic value in patients with lymphoma. Methods: A retrospective analysis was conducted on 118 patients newly diagnosed with malignant lymphoma, who underwent 18F-FDG PET/CT and exhibited diffuse increased splenic or BM uptake in 18F-FDG PET/CT imaging. The mean standardized uptake value (SUV) of the spleen, BM, and liver was calculated. The association between metabolic variables and systemic inflammatory markers was investigated, and the prognostic significance of clinicopathological and PET parameters was assessed using overall survival (OS) and progression-free survival (PFS). Results: A statistically significant correlation was found between the spleen-to-liver SUV ratio (SLR) and inflammatory markers such as C-reactive protein (r=0.264, P=0.007) and platelet-to-lymphocyte ratio (r=0.227, P=0.021). No significant correlation was observed between BM-to-liver SUV ratio (BLR) and hematologic parameters, while concordance analysis revealed a fair agreement between BLR and bone marrow biopsy (BMB) (Cohen's Kappa-κ =0.271, P=0.002). In patients with aggressive non-Hodgkin lymphoma, both SLR [P=0.017, HR 2.715, 95% confidence interval (CI): 0.875-8.428] and BLR (P=0.044, HR 0.795, 95% CI: 0.348-1.813) were significantly linked to OS, while SLR (P=0.019, HR 2.223, 95% CI: 1.139-4.342) emerged as a significant prognostic factor for PFS. Conclusions: This study highlighted that diffuse increased splenic 18F-FDG uptake in lymphoma patients was closely associated with inflammation, whereas diffuse BM uptake was likely attributable to BM infiltration rather than inflammatory changes. Furthermore, both parameters held promise as prognostic indicators for patients with aggressive lymphoma.

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Background: The extent of skull base invasion (SBI) in nasopharyngeal carcinoma (NPC) directly impacts tumor staging, treatment strategies, and prognosis assessment for NPC patients, emphasizing the critical need for prompt diagnosis and precise assessment of invasion. Thus, we aimed to integrate the advantages of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and conventional magnetic resonance imaging (cMRI), and assess their combined diagnostic efficacy versus that of 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) for detecting SBI in NPC patients. Methods: The study prospectively and randomly recruited 62 patients newly diagnosed with NPC by pathological biopsy at the Cancer Center of Affiliated Hospital of Guangdong Medical University from January 2021 to September 2022. All patients underwent baseline cMRI, IVIM-DWI, and PET/CT scans. The IVIM-DWI analysis included 3 primary parameters: true diffusion coefficient (D), pseudodiffusion coefficient (D*), and pseudodiffusion fraction (f). SBI was defined as the involvement of any substructure confirmed by follow-up MRI and clinical symptoms. Inter-observer agreement was evaluated utilizing the intraclass correlation coefficients (ICC) and kappa coefficients. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of cMRI, IVIM-DWI plus cMRI, and PET/CT. DeLong test was used to compare the areas under the curve (AUC) of the 3 modalities. Results: Excellent inter-observer reliability was observed (range, 0.841-0.946). Among the IVIM-DWI parameters, D* + f demonstrated comparable accuracy to D + D* + f (AUC 0.906 vs. 0.904; sensitivity 88.9% vs. 89.8%; specificity 92.3% vs. 91.0%). IVIM-DWI plus cMRI yielded an overall AUC of 0.947, sensitivity of 92.6%, and specificity of 96.8%, surpassing cMRI alone with an AUC of 0.914 (P=0.025), sensitivity of 91.2%, and specificity of 91.7%, as well as 18F-NaF PET/CT with an AUC of 0.852 (P<0.001), sensitivity of 80.1%, and specificity of 90.4%. In detecting substructures of SBI, IVIM-DWI plus cMRI showed superior performance compared to 18F-NaF PET/CT within the petrous part of the temporal bone (AUC 0.968 vs. 0.871, P=0.011; sensitivity 93.5% vs. 87.1%, specificity 100% vs. 87.1%), pterygopalatine fossa (AUC 0.935 vs. 0.831, P=0.032; sensitivity 93.9% vs. 69.7%, specificity 93.1% vs. 96.6%), and foramen ovale (AUC 0.885 vs. 0.710, P=0.019; sensitivity 76.9% vs. 61.5%, specificity 100% vs. 80.6%). Conclusions: IVIM-DWI plus cMRI can accurately detect SBI and the substructures in NPC, providing a valuable reference for personalized treatment strategies and precise prognosis assessment.

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The high incidence and heavy disease burden of prostate cancer (PC) require accurate and comprehensive assessment for appropriate disease management. Prostate-specific membrane antigen (PSMA) positron emission tomography (PET) cannot detect PSMA-negative lesions, despite its key role in PC disease management. The overexpression of gastrin-releasing peptide receptor (GRPR) in PC lesions reportedly performs as a complementary target for the diagnosis and therapy of PC. Radiopharmaceuticals derived from the natural ligands of GRPR have been developed. These radiopharmaceuticals enable the visualization and quantification of GRPR within the body, which can be used for disease assessment and therapeutic guidance. Recently developed radiopharmaceuticals exhibit improved pharmacokinetic parameters without deterioration in affinity. Several heterodimers targeting GRPR have been constructed as alternatives because of their potential to detect tumor lesions with a low diagnostic efficiency of single target detection. Moreover, some GRPR-targeted radiopharmaceuticals have entered clinical trials for the initial staging or biochemical recurrence detection of PC to guide disease stratification and therapy, indicating considerable potential in PC disease management. Herein, we comprehensively summarize the progress of radiopharmaceuticals targeting GRPR. In particular, we discuss the impact of ligands, chelators, and linkers on the distribution of radiopharmaceuticals. Furthermore, we summarize a potential design scheme to facilitate the advancement of radiopharmaceuticals and, thus, prompt clinical translation.

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