Annals of Nuclear Medicine最新文献

Objective

Accurate and real-time evaluation of tumor ER and HER2 status is essential for improving the clinical management of patients with metastatic breast cancer (MBC). The purpose of this pilot study was to investigate the value of PET imaging with ¹⁸F-FES and ⁶⁸ Ga-HER2 affibody for the noninvasive evaluation of the ER and HER2 status in MBC patients.

Methods

From January 2021 to September 2023, 17 metastatic breast cancer (MBC) patients underwent ¹⁸F-FES and ⁶⁸Ga-HER2-affibody PET/CT within one month, with concurrent ¹⁸F-FDG PET/CT for tumor glycolytic activity evaluation. The imaging data were integrated to detect lesions and analyze intra-patient heterogeneity. The efficacy of lesion detection across different modalities was evaluated, along with an assessment of their potential impact on clinical decision-making.

Results

A total of 174 metastatic lesions were detected: 163 (93.7%) showed high ¹⁸F-FDG uptake, 91 (52.3%) exhibited ¹⁸F-FES positivity, and 104 (59.8%) demonstrated ⁶⁸Ga-HER2-affibody binding. The biopsy correlation revealed significantly higher ¹⁸F-FES and ⁶⁸Ga-HER2-affibody uptake in ER-positive (P < 0.05) and HER2-positive (P < 0.05) lesions, respectively, compared to their negative counterparts. In clinical decision-making influenced by PET findings, 12 of 17 patients (70.6%) had treatment strategies concordant with ¹⁸F-FES and ⁶⁸Ga-HER2-affibody PET results. Among nine dual-positive patients (both tracers positive), 55.6% (5/9) were administered combined endocrine therapy and anti-HER2 targeted regimens, thereby obviating chemotherapy. In single-tracer-positive subgroups, 100% (2/2) of ¹⁸F-FES + /⁶⁸Ga-HER2 − cases received endocrine therapy (with or without CDK4/6 inhibitors), whereas 66.7% (2/3) of ⁶⁸Ga-HER2 + /¹⁸F-FES − patients were treated with anti-HER2 therapy (with or without chemotherapy). Notably, three dual-negative patients were not prescribed antihormonal or anti-HER2 agents; instead, they received chemotherapy (with or without immunotherapy), avoiding inappropriate targeted interventions.

Conclusion

Dual-tracer PET imaging enables noninvasive assessment of ER/HER2 status and intratumoral heterogeneity, providing critical insights for personalized treatment strategies in MBC.

Background

Total knee and hip arthroplasty are common procedures for patients with osteoarthritis when conservative therapy fails. Aseptic loosening and periprosthetic joint infection are major complications, with periprosthetic joint infection being a leading cause of pain post-surgery. This study aims to assess the accuracy of a novel semi-quantitative parameter, the Blood Pool-To-Delayed Ratio (BPrDr) variation index, for assessing suspected periprosthetic joint infection in the hip and knee.

Methods

A retrospective analysis was conducted using data from the Nuclear Medicine department at Hospital Clínico Universitario de Valladolid, between October 2018 and December 2020, including patients who underwent surgery for suspected prosthetic joint infection. The Blood Pool ratio (BPr) was calculated by comparing the affected and contralateral joint areas during the blood-pool phase. The Delayed Ratio (Dr) was determined similarly in the delayed phase, and the BPrDr variation index was calculated as [(Dr–BPr)/BPr] × 100. Findings were compared with microbiological culture and intraoperative joint fluid analysis.

Results

Sixty-four patients were included; microbiological examination was positive for infection in 17. The BPrDr variation index showed an area under the ROC curve (AUC) of 0.71 (95% CI 0.57–0.85; P = 0.009). The optimal cut-off for differentiating infection from aseptic loosening was 14.73%, with sensitivity of 88.2%, specificity of 55.3%, positive predictive value of 41.6%, and negative predictive value of 92.8%.

Conclusion

The BPrDr variation index may be a useful screening tool for ruling out periprosthetic joint infection in the hip and knee after joint replacement.

Objective

¹⁵O-gas PET allows for the quantitative measurement of cerebral circulation and metabolism. However, the administration of high radioactivity doses raises concerns about count losses, particularly when using high-sensitivity whole-body PET/CT scanners equipped with BGO detectors. Therefore, optimizing the administration dose is crucial. This study aims to evaluate the validity of ¹⁵O-gas PET performed with such scanners.

Methods

A 3D-PET/CT scanner, Discovery IQ, which has a 5-ring configuration with a 26 cm axial field of view, was used. A 100 mL saline pack containing ¹¹C at 460 MBq was placed on a 3D Hoffman brain phantom (HBP) filled with ¹⁸F at 5.0 kBq/mL, and dynamic scans were performed. The quantitative capability of measured radioactivity in the HBP was evaluated. Subsequently, the HBP filled with ¹⁸F at 5.0 kBq/mL was equipped with a gas mask system, and ¹⁵O-gas was administered at flow rates ranging from 3000 MBq/min, decreasing in 500 MBq/min increments, while dynamic scans were performed. The quantitative accuracy of radioactivity in HBP and count rate characteristics were evaluated. To confirm the feasibility of the ¹⁵O-gas PET method in the clinical situations both practically and quantitatively, cerebral blood-flow (CBF) values obtained via PET and SPECT were compared in 10 patients with cerebrovascular diseases. CBF was calculated by the autoradiography method. Analyses included standard brain transformation and alignment, followed by averaging CBF values from 26 brain regions for comparison.

Results

The measured radioactivity in the HBP approached the true value as the radioactivity of ¹¹C in the saline pack decreased. To achieve a quantitative error within ± 5%, the radioactivity of ¹¹C needed to be below 40 MBq. Similarly, for ¹⁵O-gas PET, an administration rate below 1000 MBq/min was needed to maintain quantitative accuracy within ± 5%. When exceeding 1500 MBq/min, random events surpassed 50%, compromising reliability. The correlation coefficient between PET and SPECT-derived CBF was 0.39 (p < 0.001). After excluding two outliers, it improved to 0.71 (p < 0.001), indicating a strong correlation. PET-measured CBF tended to be higher than SPECT.

Conclusions

These findings suggest that an administration rate of 800 MBq/min for ¹⁵O-gas provides acceptable quantitative parameters for cerebral circulation and metabolism.

Clinical component of this study was registered at the UMIN Clinical Trials Registry (www.umin.ac.jp/ctr/) as # UMIN000046761.

Objective

¹⁷⁷Lu-DOTATATE and ¹⁷⁷Lu-PSMA-617 used as therapeutic radiopharmaceuticals are primarily excreted in urine and may cause relatively high levels of contamination in toilets and sink areas. This study aimed to comprehensively evaluate a novel fluorine-coated film as a practical solution for the management of ¹⁷⁷Lu-DOTATATE contamination by (1) quantifying its decontamination efficiency, (2) assessing its effectiveness in clinical settings, and (3) identifying optimal applications in nuclear medicine facilities.

Methods

The developed hydrophobic films [fluorine-coated film (F-film) and fluorine-urethane resin-coated film (FU-film)] were prepared along with a commercial hydrophobic film (Aquaglide), stainless-steel plate, sink, and urine bag were used as the test materials. Contact angles were measured using the sessile-drop method. The relationship between the contact angle of each test material (excluding the sink) and the count reduction rate after applying ¹⁷⁷Lu-DOTATATE (4.93 Bq/ml, 0.1 ml) was investigated. Each measurement was performed three times. To confirm the effectiveness in a clinical setting, the FU-film was applied to a toilet bowl, and the contamination after urination by patients who were administered ¹⁷⁷Lu-DOTATATE was evaluated.

Results

A strong positive correlation (r = 0.84, p = 0.001) was observed between the contact angle of the test material surface and the reduction rate of the count after wiping with a wet paper towel. Specifically, the counts of the F-film, FU-film, and Aquaglide, which had contact angles greater than 90°, decreased by 92.1%, 96.8%, and 97.4%, respectively, and the counts on the sink and the stainless-steel plate decreased by 71.9% and 69.2%, respectively. The count of the FU-film was 23.3% lower than that of the urine bag. The density of surface contamination of the FU-film after flushing was 62.2% lower than that of the toilet bowl and was lower than the background level.

Conclusion

The developed FU-film effectively prevents and reduces ¹⁷⁷Lu-DOTATATE contamination, with a reduction rate as high as 96.8%. This is particularly useful for protecting areas where water flows directly, such as sinks and toilet bowls, and also for protecting other medical materials that may be contaminated with urine.

Objective

Targeted alpha-particle therapy (TAT) is promising with a greater therapeutic effect than conventional beta radionuclide therapy. To develop human clinical trials of [²¹¹At]meta-astatobenzylguanidine ([²¹¹At]MABG), we have conducted an extended single-dose toxicity study of [²¹¹At]MABG in normal mice in consultation with the Pharmaceuticals and Medical Devices Agency (PMDA). We are currently working for human clinical trials of [²¹¹At]MABG. After consultation with the Pharmaceuticals and Medical Devices Agency, we conducted a single-dose toxicity study of [²¹¹At]MABG in normal mice in preparation for a human clinical trial of [²¹¹At]MABG.

Methods

[²¹¹At]MABG was manufactured at Fukushima Medical University, where doses of 16, 48, and 80 MBq/kg were administered to BALB/cCrSlc mice (90 males and 90 females, 9 weeks old). The mice were observed and weighed every day for 14 days after [²¹¹At]MABG administration, as well as at any time between 14 and 35 days after [²¹¹At]MABG administration. At the end of the observation period, necropsy, blood examination, organ weighing, and histopathological examinations were performed. Statistical analyses of body weight, blood test results, and organ weights were performed to compare the data between the control and treatment groups.

Results

In the 80-MBq/kg-administered group of females, two mice were emergently euthanized on day 8 because of the deterioration of their general condition. One mouse died spontaneously on day 9. Except for the two emergently euthanized mice and one mouse that died, both males and females showed volume-dependent deterioration in body weight, general condition, necropsy findings, blood test results, organ weights, and histopathological findings, but all except for genital organ weights showed a recovery trend after 35 days.

Conclusions

The extended single-dose toxicity study of [²¹¹At]MABG conducted under the reliability criteria showed the toxicity of [²¹¹At]MABG to hematopoietic cells, gastrointestinal mucosa, adrenal glands, and genital organs, especially at the dose of 80 MBq/kg. Under the conditions of this study, the approximate lethal dose of [²¹¹At]MABG exceeds 80 MBq/kg, so the severely toxic dose in 10% of the animals was estimated to be 80 MBq/kg or greater.

Purpose

This study aimed to explore the feasibility of reduced ¹⁸F-FDG dosage in pediatric PET/MR imaging through randomized down-sampling.

Methods

Forty-four pediatric patients (26 males, 18 females; median: 11 years [range, 1–17]) underwent ¹⁸F-FDG PET/MR examinations were retrospectively enrolled. PET data were reconstructed into 6 groups with different simulated doses using randomly down-sampling: full dose (2.96 MBq/kg), 1/2 dose, 1/3 dose, 1/4 dose, 1/10 dose, and 1/20 dose. Subjective visual analysis of image quality was evaluated using a 5-point Likert scale. Quantitative parameters of lesions and blood pool and liver background were analyzed. The full dose group was served as a reference.

Results

Subjective image quality of 1/2 dose, 1/3 dose and 1/4 dose images was clinically acceptable (score ≥ 3), and all FDG–avid lesions could be identified in these three groups like full-dose group. SUVmax and standard deviation (SD) of blood pool and liver increased as the dose reduced, while no significant difference in SUVmean of blood pool and liver was found in 1/2–1/20 dose groups when compared to the full dose group. Besides, a significant difference was observed in SUVmax and SD of lesion and lesion-to-background ratio between 1/2–1/20 dose and full dose groups (p < 0.05).

Conclusion

Further reduction in administered ¹⁸F-FDG activities is feasible in pediatric PET/MR scan. Clinically acceptable image quality could be achieved using a low dose of 0.74 MBq/kg.

Objective

To compare the diagnostic efficacy of dual-layer spectral computed tomography (DSCT) and 18-F fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in preoperative identification of metastatic sentinel lymph nodes (SLNs) in patients with breast cancer.

Methods

This retrospective study analyzed 97 patients who underwent DSCT and 107 patients who underwent 18F-FDG-PET/CT, classified by pathology into SLN-positive group and SLN-negative group. Quantitative measurements included: (1) DSCT parameters (normalized iodine concentration[nIC], effective atomic number [Zeff], the slope of the spectral Hounsfield unit curve [λHU] in both arterial and venous phases) and (2) the maximum standardized uptake value (SUVmax) of 18F-FDG PET/CT. Statistical analysis involved group comparisons, logistic regression for independent predictors, and receiver-operating characteristic (ROC) curve analysis (area under the curve [AUC], sensitivity, and specificity).

Results

The results showed that SUVmax and spectral parameters, including Zeff in the venous phase, nIC in both arterial and venous phases, and λHU in both arterial and venous phases, were significantly higher in metastatic SLNs compared to non-metastatic SLNs. Logistic regression analysis identified both λHU in the venous phase and SUVmax as independent risk factors for predicting metastatic SLNs. ROC curve analysis indicated that SUVmax had a higher diagnostic efficiency (AUC: 0.905) than the combined spectral parameters (AUC: 0.834). Specifically, SUVmax demonstrated higher specificity (97 vs. 53%) but lower sensitivity (77 vs. 98%) than the spectral parameters.

Conclusions

Compared with DSCT, 18F-FDG-PET/CT demonstrated higher specificity in identifying metastatic SLNs in breast cancer patients, but was less sensitive than spectral parameters. Spectral parameters can serve as a noninvasive tool for preoperative identification of metastatic SLNs in breast cancer.

Objective

Owing to the revision of the Medical Care Act in 2020, managing and recording radiation doses in PET-CT examinations have become mandatory. In this study, we investigated unsupervised anomaly detection methods as a potential solution to minimize input errors in dose recordings.

Methods

We analyzed data extracted from our database, including patient body weight, positron emission tomography (PET) dose, and dose length product (DLP). Several anomaly detection models, such as one-class support vector machine (OCSVM), Hotelling's T2 method, multivariate statistical process control (MSPC), isolation forest, and local outlier factor (LOF), were applied and compared. The dataset included 3509 entries for model training and 499 entries for evaluation. Anomalies that could be potential input errors were evaluated using metrics, such as precision, recall, F1 score, receiver operating characteristics-area under the curve (ROC-AUC), and precision–recall-AUC (PR-AUC).

Results

We demonstrated that Hotelling's T2 method and MSPC's T² statistic outperformed other models, achieving a recall of 1.0 and AUCs of 1.0, effectively detecting input errors in radiation dose records. Furthermore, our findings suggest that unsupervised anomaly detection can not only identify input errors but also detect excessively high or low radiation doses, contributing to improved dose management in PET-CT examinations.

Conclusion

These findings suggest that unsupervised anomaly detection is a promising approach to improve the accuracy of dose management in PET-CT examinations, enhancing patient safety and compliance with regulatory standards.

Purpose

Radionuclide brain perfusion studies using a lipophilic radiopharmaceutical are recognized as reliable ancillary tests for brain death determination in various clinical guidelines. We aim to share our experience with the SPECT-CT protocol.

Materials and methods

All studies performed between 2010 and 2023 were included. Planar, SPECT, and SPECT-CT images were analyzed and categorized as showing normal intracranial perfusion, residual cerebellar activity, definitive absence of intracranial perfusion, or residual intracranial activity. These findings were compared with the final diagnosis for each study, which was based on available clinical information, radiologic, and nuclear medicine images.

Results

A total of 117 brain perfusion studies for brain death determination were performed. Of these, 106 (91%) were reported as definitive for the absence of intracranial perfusion and were concordant with the clinical diagnosis of brain death. In the remaining 11 cases, 5 (4%) showed normal brain perfusion, and 6 (5%) demonstrated residual intracranial activity.

Among the 5 studies with normal perfusion, all (100%) were correctly identified on planar-only images. Of the 106 patients with a definitive diagnosis of absent brain perfusion, 56.6% (60/106) showed a definitive planar result, 36.8% (39/106) had a probable result, 3.8% (4/106) showed possible intracranial activity, and in 2.8% (3/106), planar images were not performed.

A total of 105 studies with tomographic images were analyzed. Of the 4 studies showing residual cerebellar activity, all (100%) were correctly identified on SPECT images. Of the 98 studies with definitive absence of intracranial perfusion, 91.8% (90/98) showed no cerebral activity on tomographic images. The remaining 8.2% (8/98) showed mild cerebral activity. Notably, 5 of these patients underwent SPECT-CT imaging, and were correctly reclassified as having intracranial bleeding, which led to a final diagnosis of absent brain perfusion.

For the 53 SPECT-CT studies analyzed, all patients were correctly categorized as either having absent brain perfusion or residual cerebellar perfusion, with no cases of normal perfusion or residual cerebral perfusion observed. Challenging cases are also discussed, including 3 patients who underwent repeat brain perfusion studies after an initial normal or inconclusive report.

Conclusions

In this article, we share our experience with brain perfusion studies in brain death determination and the evolution of our protocol over the past decade. SPECT-CT has become our standard protocol, allowing us to confidently categorize patients as having either normal brain perfusion, absent brain perfusion, or residual partial brain perfusion. This approach reflects the clinical need for an unbiased and accurate test of intracranial perfusion.

Objective

¹⁸F-Fludeoxyglucose (FDG) PET/CT is an effective tool for detecting active cardiac sarcoidosis (CS), but often has difficulty distinguishing CS lesions from physiological myocardial accumulation. We investigated the potential of the glucose metabolic rate (MR_glc, mg/min/100mL) from four-dimensional FDG PET/CT in distinguishing between CS and physiological accumulation. Additionally, we compared CS delineation between MR_glc and standardized uptake value (SUV).

Methods

A total of 192 individuals with CS or suspected CS who underwent four-dimensional FDG PET/CT after 18 h fasting was enrolled. Ultimately, 45 individuals with CS and 14 patients with physiological accumulation, with SUV_mean ≥ 2.7 accumulation in the left ventricular myocardium, were analyzed. The SUV, MR_glc, and the ratio of MR_glc to SUV (MR_glc/SUV) were calculated for each lesion with SUV_mean ≥ 2.7 using data acquired between 30 and 50 min on four-dimensional FDG PET/CT. In the CS group, lesion-to-normal myocardium contrast ratios on MR_glc and SUV images were compared.

Results

A total of 127 lesions from 45 individuals with CS and 43 physiological accumulations from 14 individuals were analyzed. The SUV, MR_glc, and MR_glc/SUV for CS lesions were significantly lower than those for physiological accumulations (SUV, 4.26±1.35 vs. 6.06±3.28; MR_glc, 1.91 ± 1.02 vs. 3.78 ± 2.11; MR_glc/SUV, 0.43 ± 0.14 vs. 0.63 ± 0.14; p < 0.0001). Receiver operating characteristic analysis revealed that the ability to discriminate CS lesions from physiological accumulations yielded areas under the curves of 0.656, 0.808, and 0.849; sensitivities of 68, 76, and 73%; and specificities of 61, 72, and 84%, for SUV 4.525, MR_glc 2.41, and MR_glc/SUV 0.518. In the CS group, the contrast ratio of lesions was significantly greater on MR_glc images than on SUV images (6.36 ± 6.17 vs. 2.54 ± 1.03, p < 0.0001).

Conclusions

MR_glc from four-dimensional FDG PET/CT is a useful quantitative measure to distinguish CS lesions from physiological accumulation and enables better visualization of CS lesion contrast than SUV.