Annals of Nuclear Medicine最新文献

Objective: In peptide receptor radionuclide therapy (PRRT) using lutetium-177-labeled DOTA-Tyr3-octreotate ([¹⁷⁷Lu] DOTATATE), isolation is required until the external dose rate at 1 m (EDR-1 m) from the body surface falls below the regulatory standards of each country. While it is known that renal function influences EDR-1 m reduction within 180 min post-administration, the factors affecting EDR-1 m on the day following administration (Late EDR-1 m) remain unclear. This study aimed to identify factors influencing Late EDR-1 m after PRRT using [¹⁷⁷Lu] DOTATATE for neuroendocrine tumors and to predict Late EDR-1 m using pretreatment [¹¹¹In] pentetreotide single-photon emission computed tomography/computed tomography (SPECT/CT) data.

Methods: This study analyzed 111 PRRT cycles administered to 36 patients between September 2021 and August 2024. Late EDR-1 m was set as the dependent variable, whereas total radiopharmaceutical uptake (LUTtotal), dose per body weight, creatinine clearance (CCr), and albumin-bilirubin (ALBI) score were set as the independent variables in the multiple regression analysis. LUTtotal was calculated using SPECT/CT data acquired after the patient left the radiation therapy room, defining the volume of interest (VOI) as the area with SUVmean + 2SD or higher in the skeletal muscle. The VOI volume multiplied by the SUVmean was used to define LUTtotal. In addition, using [¹¹¹In] pentetreotide SPECT/CT data, the total radiopharmaceutical uptake (OCTtotal) was calculated in a manner similar to LUTtotal, and its correlation with LUTtotal was examined. A predictive equation for Late EDR-1 m was developed using the results of the multivariate analysis, and its performance was tested using subsequent cases between August 2024 and January 2025.

Results: The median measured Late EDR-1 m was 8.0 (range, 4.0-26.0) μSv/h. LUTtotal and dose per body weight were significantly correlated with Late EDR-1 m, whereas CCr and ALBI scores were not. Based on the results of the multivariate analysis, the predictive equation using the dose per body weight, assuming a dosage of 7400 MBq and OCTtotal, achieved a root mean square error (RMSE) of 2.24 μSv/h. In subsequent test cases, the RMSE was 3.47 μSv/h.

Conclusions: Late EDR-1 m is significantly correlated with LUTtotal and dose per body weight. It can be accurately predicted using [¹¹¹In] pentetreotide SPECT/CT data.

Purpose: Radioiodine (¹³¹I) dosimetry is used to maximise tumour dose while reducing the chances of toxicity. High thyroid-stimulating-hormone (TSH) levels are required for ¹³¹I treatment, achieved through hormone withdrawal or intramuscular injection of recombinant human TSH (rhTSH). Both approaches have shown equivalent results, with the rhTSH approach reported to reduce morbidity and avoid hypothyroidism. There are established differences in ¹³¹I biokinetics using each method. This clinical cohort study investigated if pretherapy iodine biokinetics as measured using a dosimetry protocol without a dose of rhTSH are predictive of post therapy biokinetics in patients prepared with rhTSH injection.

Methods: Thirteen patients with differentiated thyroid cancer (DTC) were recruited. An adaptation of the European Association of Nuclear Medicine (EANM) dosimetry protocol was conducted at St James's Hospital, Ireland. The maximum tolerable activity (MTA) was calculated using the EANM, Association of Physics in Medicine (AIFM) and Traino models, after administering ¹³¹I, and subsequent whole-body (WB) dose-rate measurements and blood-sampling were carried out. The MTA estimated from pre-therapeutic (PT) ¹³¹I tracer administration (6.07 ± 2.46 MBq) was compared to during therapy (DT) administration (3.88 ± 0.16 GBq).

Results: The PT WB residence-time overestimated the DT with a difference of - 7.72 ± 8.13% (p = 0.007), while no significant difference is reported between the blood residence-time (1.13 ± 6.49%, p = 0.559). The EANM model reported the lowest difference of 1.73 ± 4.83% (p = 0.241) in MTA.

Conclusion: This study validated the feasibility of using dosimetry in euthyroid patients to predict therapeutic ¹³¹I biokinetics in DTC patients prepared with rhTSH.

Objective: This study analyzes the role of positron emission tomography/computed tomography (PET/CT) in the diagnosis of small (< 10 mm) colorectal cancer liver metastasis (CRLM) lesions in patients with hypothyroidism. In particular, the impact of the best time for delayed imaging on improving diagnostic efficacy.

Methods: We retrospectively analyzed 231 patients with small CRLM lesions with hypothyroidism who underwent dual time-point 18F-FDG PET/CT imaging. Based on the previous studies and clinical practice experience, 120-190 min was selected as the time range for delayed imaging, divided into eight teams in 10-min groups. The delayed images of the eight time periods were first analyzed and compared for diagnostic efficacy, and second analyzed and compared for standardized uptake value (SUV) and of PET/CT images to observe the trend of SUV values over time.

Results: The results of diagnostic efficacy analysis indicated that the 180-min delay group had the highest diagnostic efficacy (sensitivity, specificity, and accuracy). Comparison of the SUV values with the delay time analysis showed that maximum standardized uptake value (SUVmax) increased with the delay time, and the normal liver tissue (SUVmean) decreased with the delay time, which resulted in the gradual increase in the ratio of the lesion to the normal liver tissue (TNR). By selecting the time-point with the highest TNR ratio and stable SUV value, and combining the results of diagnostic efficacy, this study successfully verified the best imaging time-point. After comprehensive consideration, 180 min was determined as the best imaging time-point, when the TNR reached the highest, the SUV value was stable, and the diagnostic efficacy was best.

Conclusions: In this study, the impact of delayed imaging on the diagnostic efficacy and SUV value of PET/CT images in patients of small CRLM with hypothyroidism was shown intuitively, and the changing pattern of SUV at different time points was also observed. The best time-point for PET/CT delayed imaging was determined to be 180 min, which provides a new scanning program for the diagnosis in patients of small CRLM with hypothyroidism.

Objective: This study aimed to develop and validate a nomogram combining ¹⁸F-FDG PET radiomics and clinical factors to non-invasively predict bone marrow involvement (BMI) in patients with lymphoma.

Methods: A radiomics nomogram was developed using monocentric data, randomly divided into a training set (70%) and a test set (30%). Bone marrow biopsy (BMB) served as the gold standard for BMI diagnosis. Independent clinical risk factors were identified through univariate and multivariate logistic regression analyses to construct a clinical model. Radiomics features were extracted from PET and CT images and selected using least absolute shrinkage and selection operator (LASSO) regression, yielding a radiomics score (Rad_score) for each patient. Models based on clinical factors, CT Rad_score, and PET Rad_score were established and evaluated using eight machine learning algorithms to identify the optimal prediction model. A combined model was constructed and presented as a nomogram. Model performance was assessed using the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA).

Results: A total of 160 patients were included, of whom 70 had BMI based on BMB results. The training group comprised 112 patients (BMI: 56, without BMI: 56), while the test group included 48 patients (BMI: 14, without BMI: 34). Independent risk factors, including the number of extranodal involvements and B symptoms, were incorporated into the clinical model. In the clinical model, CT Rad_score, and PET Rad_score, the AUCs in the test set were 0.820 (95% CI: 0.705-0.935), 0.538 (95% CI: 0.351-0.723), and 0.836 (95% CI: 0.686-0.986). Due to the limited diagnostic performance of CT Rad_score, the nomogram was constructed using PET Rad_score and the clinical model. The radiomics nomogram achieved AUCs of 0.916 (95% CI: 0.865-0.967) in the training set and 0.863 (95% CI: 0.763-0.964) in the test set. Calibration curves and DCA confirmed the nomogram's discrimination, calibration, and clinical utility in both sets.

Conclusion: By integrating PET Rad_score, the number of extranodal involvements, and B symptoms, this ¹⁸F-FDG PET radiomics-based nomogram offers a non-invasive method to predict bone marrow status in lymphoma patients, providing nuclear medicine physicians with valuable decision support for pre-treatment evaluation.

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.

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.