Annals of Nuclear Medicine最新文献

Objective: Somatostatin receptors (SSTRs) are G protein-coupled transmembrane receptors that serve as a specific molecular target for a number of radiopharmaceuticals utilized for the imaging of neuroendocrine tumors (NETs). ⁶⁸Ga-DOTA-TATE is a somatostatin analog that demonstrates a high affinity for SSTR2. Pediatric malignancies, such as neuroblastoma, pheochromocytoma, and paraganglioma, have been shown to express SSTR2, and ⁶⁸Ga-DOTA-TATE is currently being used to evaluate these pediatric neoplasms. We aimed to analyze the distribution pattern of ⁶⁸Ga-DOTA-TATE based on age and location in pediatric patients.

Methods: We retrospectively analyzed 247 consecutive ⁶⁸Ga-DOTA-TATE whole-body PET/CT scans performed in our department from May 2015 to April 2024 in pediatric patients with known or suspected neuroblastoma, neuroendocrine malignancy, pheochromocytoma, and paraganglioma. 93 subjects were included in this study who were disease-free at the time of imaging and had no tracer-avid lesion on ⁶⁸Ga-DOTA-TATE PET/CT. The patients were divided into four groups according to age: infant (0-2 years), pre-school (3-6 years), school (7-12 years), and adolescent (13-18 years). A comparison of the SUV values of each organ across age groups was performed.

Results: The highest levels of physiological uptake were observed in the spleen across all age groups, except for infants, who demonstrated the highest SUV values in the kidneys. ⁶⁸Ga-DOTA-TATE uptake in the parotid glands, submandibular glands, thyroid gland, thymus, liver, spleen, adrenal glands, stomach, intestines, uterus, prostate, and testes demonstrated a statistically significant increase in the adolescent age group. In contrast to all internal organs, the lowest SUV max values were observed for all growth plates within the adolescent age group.

Conclusion: This study presents the bio-distribution pattern of ⁶⁸Ga-DOTA-TATE in pediatric patients, according to age and location. The ranges of the SUVmax and SUVmean values of ⁶⁸Ga-DOTA-TATE obtained in the various organs are of paramount importance for accurately diagnosing malignancy in ⁶⁸Ga-DOTA-TATE PET/CT studies.

Objective: To provide fully automatic scanner-independent 5-level categorization of the [¹²³I]FP-CIT uptake in striatal subregions in dopamine transporter SPECT.

Methods: A total of 3500 [¹²³I]FP-CIT SPECT scans from two in house (n = 1740, n = 640) and two external (n = 645, n = 475) datasets were used for this study. A convolutional neural network (CNN) was trained for the categorization of the [¹²³I]FP-CIT uptake in unilateral caudate and putamen in both hemispheres according to 5 levels: normal, borderline, moderate reduction, strong reduction, almost missing. Reference standard labels for the network training were created automatically by fitting a Gaussian mixture model to histograms of the specific [¹²³I]FP-CIT binding ratio, separately for caudate and putamen and separately for each dataset. The CNN was trained on a mixed-scanner subsample (n = 1957) and tested on one independent identically distributed (IID, n = 1068) and one out-of-distribution (OOD, n = 475) test dataset.

Results: The accuracy of the CNN for the 5-level prediction of the [¹²³I]FP-CIT uptake in caudate/putamen was 80.1/78.0% in the IID test dataset and 78.1/76.5% in the OOD test dataset. All 4 regional 5-level predictions were correct in 54.3/52.6% of the cases in the IID/OOD test dataset. A global binary score automatically derived from the regional 5-scores achieved 97.4/96.2% accuracy for automatic classification of the scans as normal or reduced relative to visual expert read as reference standard.

Conclusions: Automatic scanner-independent 5-level categorization of the [¹²³I]FP-CIT uptake in striatal subregions by a CNN model is feasible with clinically useful accuracy.

Objective: This study aimed to comprehensively evaluate the performance of fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and investigate the association between metabolic parameters, programmed cell death ligand 1 (PD-L1) expression, and prognosis in patients with fumarate hydratase-deficient renal cell carcinoma (FHRCC).

Methods: Twenty-nine patients with FHRCC were prospectively enrolled from May 2020 to February 2023 for ¹⁸F-FDG PET/CT. The maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of primary/recurrent tumors were analyzed. The relationship between PET metabolic parameters, clinicopathological features and prognosis were evaluated.

Results: Primary/recurrent and metastatic lesions showed FDG avidity, without metabolic differences between them. In our analysis, SUVmax of whole body (WB-SUVmax), SUVpeak of whole body (WB-SUVpeak), MTV of whole body (WB-MTV), and TLG of whole body (WB-TLG) were associated with the expression of PD-L1. The optimal cut-off values of WB-SUVmax, WB-SUVpeak, WB-MTV, and WB-TLG for predicting positive PD-L1 expression were 9.86 (AUC 0.814), 6.92 (AUC 0.848), 19.61 cm³ (AUC 0.803), and 58.39 g (AUC 0.841), respectively. Survival analysis further demonstrated that patients with WB-SUVpeak ≥ 8.92 had shorter time to progression than those with WB-SUVpeak < 8.92 (11.0 mo vs. 21.0 mo, P = 0.047).

Conclusions: ¹⁸F-FDG PET/CT is effective in detecting FHRCC lesions due to their hypermetabolic nature. PET metabolic parameters can serve as predictors of positive PD-L1 expression, with higher values observed in FHRCC patients with positive PD-L1 expression. Additionally, WB-SUVpeak is a significant predictor of prognosis in patients with FHRCC.

Purpose: Dynamic positron emission tomography (PET) imaging has commonly been applied to study blood perfusion in the human brain and heart, but there is a very limited amount of existing research about the suitability of this method for many other organs of interest. Here, we focus on the quantification of pulmonary blood flow (PBF) in human lungs. We evaluate both the potential of the $_{}^{15}$ O-water PET imaging via compartmental modeling with automatic volume of interest (VOI) selection for PBF quantification and study the possible differences in PBF caused by different patient characteristics such as age or sex.

Procedures: We systematically fit the one-tissue compartment model to the mean time-activity curves derived from the $_{}^{15}$ O-water PET data of 103 patients. The machine learning-based segmentation tool TotalSegmentator is utilized to find segmentation masks for different lung lobes and right ventricle of the heart. Additionally, we automatically remove the majority of the air inside the lung lobe VOIs and the areas surrounding subclavian arteries and brachiocephalic veins with the help of binary erosion and dilatation operations. After the model fitting, we evaluate possible differences in the results caused by age, sex, weight, and body mass index (BMI) by performing Mann-Whitney U tests between different patient subgroups and computing Spearman's correlations coefficients.

Results: The estimated PBF within all the lung lobes had a mean of1.21±0.825 mL/min/cm $_{}^3$ and a median of 1.03 mL/min/cm $_{}^3$ , but this value was notably lower in right lower lung lobe and much higher in the upper lung lobes. The PBF was higher in both the female patients and in the patients under 65 years but not statistically significantly so. The individual variation was very high.

Conclusions: The PBF quantification based on $_{}^{15}$ O-water PET imaging combined with our automatic VOI selection method is an effective method to produce relatively realistic results. In case of upper lung lobes, the results are likely overestimated if pulmonary vessels are not removed from the VOI. The accurate estimation of the air volume within the lung lobe VOIs is also a non-trivial problem. More research on this topic is warranted to find whether there is a decreasing trend between PBF and age or significant differences between the sexes.

Background: Deep learning, a leading technology in artificial intelligence (AI), has shown remarkable potential in revolutionizing nuclear medicine.

Objective: This review presents recent advancements in deep learning applications, particularly in nuclear medicine imaging, lesion detection, and radiopharmaceutical therapy.

Results: Leveraging various neural network architectures, deep learning has significantly enhanced the accuracy of image reconstruction, lesion segmentation, and diagnosis, improving the efficiency of disease detection and treatment planning. The integration of deep learning with functional imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) enable more precise diagnostics, while facilitating the development of personalized treatment strategies. Despite its promising outlook, there are still some limitations and challenges, particularly in model interpretability, generalization across diverse datasets, multimodal data fusion, and the ethical and legal issues faced in its application.

Conclusion: As technological advancements continue, deep learning is poised to drive substantial changes in nuclear medicine, particularly in the areas of precision healthcare, real-time treatment monitoring, and clinical decision-making. Future research will likely focus on overcoming these challenges and further enhancing model transparency, thus improving clinical applicability.

Objective: The aim of this study was to compare the diagnostic accuracy of ⁶⁸Ga-PSMA-11 PET/CT and multiparametric MRI (mpMRI) in detecting unilateral and bilateral intra-glandular prostate cancer lesions.

Methods: A retrospective analysis was conducted on 73 prostate cancer patients diagnosed via biopsy, all of whom underwent both ⁶⁸Ga-PSMA-11 PET/CT and mpMRI prior to surgery. Two independent readers, blinded to each other's results and to pathology findings, evaluated the imaging modalities to make a diagnosis of unilateral (left or right) or bilateral lesions for suspected prostate lesions. Histopathological findings from a 12-core transrectal ultrasound-guided biopsy and radical prostatectomy served as reference standards. The accuracy of both imaging modalities in determining unilateral and bilateral intra-glandular prostate cancer was assessed through receiver operating characteristic curve analysis. Additionally, factors influencing diagnostic discordance between the two modalities were evaluated.

Results: A total of 73 patients were included in the final analysis, comprising 34 with unilateral lesions and 39 with bilateral lesions. Among these, 35 patients underwent radical prostatectomy, revealing 22 cases of bilateral lesions and 13 cases of unilateral lesions [Kappa = 0.76 (P < 0.001)]. The lateral diagnostic accuracy of ⁶⁸Ga-PSMA-11 PET/CT, based on pathological results from biopsy or prostatectomy, was 80.82% (59/73) and 82.86% (29/35), respectively. These values were significantly higher than those of mpMRI, which demonstrated an accuracy of 54.79% (40/73, P < 0.001) and 40% (14/35, P < 0.001), respectively. Concordance between ⁶⁸Ga-PSMA-11 PET/CT and mpMRI for the lateralization accuracy was poor (kappa = 0.015, P < 0.05). When both imaging modalities provided consistent lateralization results (39/73), concordance with pathological findings reached 87.18% (34/39). However, concordance with pathological results was significantly higher for ⁶⁸Ga-PSMA-11 PET/CT (76.47%, 26/34) compared to mpMRI (20.59%, 7/34). Further analysis revealed that an SUVmax > 3.95 for ⁶⁸Ga-PSMA-11 PET/CT and a PI-RADS score ≥ 4 for mpMRI were independent factors influencing lateral diagnostic concordance.

Conclusion: The ⁶⁸Ga-PSMA-11 PET/CT demonstrated significantly higher lateralization accuracy than mpMRI in intra-glandular prostate cancer. There was considerable inconsistency in the diagnostic outcomes between ⁶⁸Ga-PSMA-11 PET/CT and mpMRI, and in cases of discordance, ⁶⁸Ga-PSMA-11 PET/CT was notably more accurate. SUVmax > 3.95 and PI-RADS score ≥ 4 were critical factors influencing the correct lateralization accuracy when the results from ⁶⁸Ga-PSMA-11 PET/CT and mpMRI were inconsistent.

[¹⁸F]FDG PET/CT is the most widely used PET radiopharmaceutical in oncology, but it is not exempt of diagnostic limitations. FAPI have emerged as a great tool in the management of several different solid tumours in which [¹⁸F]FDG is not able to provide enough information. The aim of this work was to evaluate the available evidence on diagnostic and therapeutic applications of PET/CT with FAPI radiopharmaceuticals. We underwent a non-systematic review focusing in the utility of FAPI radiopharmaceuticals in PET/CT diagnosis and in the treatment of several malignancies. FAPI radiopharmaceuticals present characteristics that can potentially overcome some known diagnostic limitations of [¹⁸F]FDG. FAPI radiopharmaceuticals present a high target-to-background ratio (TBR) in many solid tumours such as oesophageal cancer, gastric cancer, pancreatic cancer, hepatic cancer, colorectal cancer, breast cancer, ovarian, cervical cancer, and head and neck cancer. Available evidence suggests the high TBR improves sensitivity and specificity compared to [¹⁸F]FDG, especially for the detection of lymphadenopathies and peritoneal metastases, and may improve patient management and radiation treatment planning. Moreover, it is important to underline the potential theranostic application of FAPI radiopharmaceuticals.

Purpose: Accurate diagnosis and staging of lung cancer are critical for optimal clinical management. Fibroblast activation protein inhibitor (FAPI) imaging has emerged as a promising modality with superior detection capabilities for lung cancer. We hypothesized that [¹⁸F]FAPI-42 PET/CT would enhance diagnosis, TNM staging, and influence oncologic management in patients with suspected or confirmed lung cancer.

Methods: In this retrospective study, 155 patients with clinically suspected or confirmed lung cancer underwent both conventional imaging and [¹⁸F]FAPI-42 PET/CT scans within a one-week interval, without any intervening treatment. Lesions were visually assessed and categorized to evaluate the diagnostic capability of [¹⁸F]FAPI-42 PET/CT. Tracer activity was quantified using maximum standardized uptake values (SUV_max) and tumor-to-background ratios. TNM staging was independently determined by a board-certified radiologist or nuclear medicine physician using both imaging modalities, and discrepancies were assessed. Changes in TNM staging were documented and evaluated for their impact on clinical management.

Results: Of the 155 patients, 99 were evaluated for primary lesion diagnosis and staging. Pathological examination confirmed malignant tumors in 87 patients and benign tumors in 12. The diagnostic sensitivity and positive predictive value of [¹⁸F]FAPI-42 PET/CT for detecting primary lung tumors were 96.77% and 92.78%, respectively. Malignant lesions exhibited significantly higher SUV_max compared to benign lesions (5.2 vs. 1.5, P = 0.0002), with an area under the ROC curve of 0.87. In total, 1,556 malignant lesions were identified among patients with lung cancer, and [¹⁸F]FAPI-42 PET/CT demonstrated a diagnostic accuracy of 95.50%. However, its sensitivity for detecting adrenal metastases was lower at 33.33%, with a specificity of 100% and an accuracy of 53.85%. The use of [¹⁸F]FAPI-42 PET/CT resulted in changes in TNM staging for 46% of patients, leading to upstaging in 58 patients and downstaging in 5. These staging adjustments directly impacted clinical management in 34 patients, prompting modifications in treatment plans.

Conclusion: [¹⁸F]FAPI-42 PET/CT is a promising modality for lung cancer diagnosis and staging, demonstrating high sensitivity and specificity. Its use significantly altered TNM staging in nearly half of the patients, directly impacting oncologic management and treatment planning. However, its limited sensitivity for detecting adrenal metastases underscores the need for additional imaging techniques.

Objective: This study evaluates the role of Ga-68 Pentixafor PET/CT in staging and follow-up of multiple myeloma (MM) and its correlation with clinical parameters.

Methods: Thirteen participants (9 males, 4 females; median age: 65 years) with MM were recruited in this prospective observational study. Six participants were included for staging evaluation, seven were included for follow-up evaluation, and underwent Ga-68 Pentixafor PET/CT. Focal PET-positive bone marrow lesions or diffuse bone marrow uptake (uptake more than liver) was considered a positive scan. The quantitative variables like SUVmax, SUVmean, total bone marrow volume and uptake (TBMV & TBMU) and tumor to background ratio (TBRmax) were obtained. Durie Salmon Plus Staging (DSPS) was used for MM staging by PET/CT and was compared with the International Staging System (ISS). Statistical comparison was performed between PET/CT quantitative variables and laboratory parameters.

Results: Twelve participants (12/13) had positive Ga-68 Pentixafor PET/CT, among which one was diagnosed to have anemia of chronic disease. One participant (1/13) who was clinically negative on follow-up had negative Ga-68 Pentixafor PET/CT. The sensitivity, specificity, PPV and NPV of Ga-68 Pentixafor PET/CT in MM (95% CI) were observed to be 100%, 50%, 91.6% and 100%, respectively. The correlation between DSPS and ISS in the patients who came for staging scans was found to be statistically significant (p-value 0.02). In quantitative analysis, either of the quantitative variables in Ga-68 Pentixafor PET/CT was positively correlated with clinical parameters related to tumor burden like CRAB score, serum protein electrophoresis M-protein, beta 2 microglobulin, LDH, percentage of plasma cells infiltrates in bone marrow aspiration, ISS, serum free light chain and negatively correlated with hemoglobin, albumin (p < 0.5).

Conclusion: Ga-68 Pentixafor PET/CT is a promising tracer and the only available non-invasive tool to assess the whole-body disease burden of CXCR4 receptors in staging and follow-up of MM. In addition, it has a vital role in the development of CXCR4-targeted theranostics. Dual tracer imaging using F-18 FDG and Ga-68 Pentixafor PET/CT may help in evaluating tumor heterogeneity in MM and add prognostic value at diagnosis and follow-up.

Introduction: Liver fibrosis is a chronic fibrosing hepatic disorder following recurrent injury, characterized by the excessive accumulation of extracellular matrix. Early detection has a great clinical impact because 80-90% of hepatocellular carcinomas are known to develop in fibrotic or cirrhotic (end-stage fibrotic) livers. PET imaging with FAP ligands exhibited highly promising results in recent years to visualize fibrosis in various organs due to the crucial role of activated fibroblasts in fibrosing processes. However, still little is known about the efficacy of FAP imaging in liver fibrosis. Thus, we sought to investigate the potential of FAPI-PET in a cohort of oncological and non-oncological patients.

Methods: 199 patients who underwent FAPI-PET/CT at the University Hospital of Heidelberg between July 2017 and July 2020 were retrospectively analyzed. The tracer uptake of the liver was analyzed and correlated with radiological and clinical parameters.

Results: We observed a weak but significant negative correlation between the hepatic FAPI uptake and CT density (r = - 0.273, P < 0.001***). A positive correlation was observed between hepatic FAPI uptake and the aspartate aminotransferase (AST)-to-platelet ratio index (APRI) (r = 0.183, P = 0.009**), an established surrogate for liver fibrosis. The liver SUV (standardized uptake value) mean and SUVmax of FAPI showed significant differences between groups of patients with low (< 0.5), middle (0.5-1.0) and higher (> 1.0) levels of APRI (both P < 0.001***).

Conclusion: These preliminary observational results suggest that FAPI-PET may be a viable non-invasive method to asses liver fibrosis.