EJNMMI Research最新文献

Background: Device-based respiratory gating improves diagnostic and quantification accuracy in positron emission tomography (PET), but requires additional time to setup the device and the failure rate can be significant. Our aim was to internally validate the quantification performance of data-driven respiratory-gated PET imaging against the gold standard, the device-based method, in clinical oncological practice. We retrospectively analysed [18F]FDG PET/CT scans of patients from our centre with at least one measurable [18F]FDG-avid malignant lesion. All PET/CT acquisitions were performed on a Siemens Biograph 64 Vision 600 system with respiratory gating by belt and also by adding the data-driven gating with OncoFreeze AI™. We recorded the SUVmax and SUVpeak for up to a maximum of 5 lesions per patient. We computed the mean absolute bias between the two gating methods and the 95% confidence intervals (CI) at the cohort level and in subgroups.

Results: Of the 692 consecutive patients screened for inclusion, 196 patients were analysed, from whom 536 lesions were measured. The mean absolute biases in the SUVmax and SUVpeak of lesions in the whole cohort were 3.8% (CI 3.4-4.2) and 2.1% (CI 1.9-2.4), respectively. At patient-level, 21% of them had at least one lesion with a SUVmax bias above 10%, while for SUVpeak this proportion was 5%. In the subgroup analysis by PERCIST criteria, only 2% of patients had significant bias in the SUVmax, and 0.5% in SUVpeak. There was no clinically significant effect of lesion size or anatomical site on SUV measurements between the two respiratory gating methods.

Conclusion: Quantitative comparison of data-driven and device-based respiratory-gated PET scans revealed negligible differences, proving that data-driven respiratory gating is a reliable and accurate alternative to the device-based gating method in routine [18F]FDG-PET/CT oncological evaluation.

Background: ¹²³I-MIBG scintigraphy plays a significant role in diagnosing Parkinson's disease (PD), with most studies primarily targeting cardiac uptake and relying on traditional ratio-based parameters for assessment. However, due to variations in scanning conditions and image processing methodologies, the clinical utility of different parameters remains a subject of debate. This study aims to evaluate the diagnostic accuracy of multi-parameter ¹²³I-3-Iodobenzylguanidine (MIBG) scintigraphy and to identify the most reliable metrics for distinguishing PD from Parkinson-plus syndromes.

Result: We recruited 56 PD patients and 44 non-PD controls, who underwent ¹²³I-MIBG scintigraphy and clinical evaluation. MIBG uptake and washout rates (WR) for the heart, salivary glands, and thyroid were assessed, with semi-quantitative methods used to calculate heart-to-mediastinum (H/M) and gland-to-background (P/B, S/B, T/B) ratios. Diagnostic efficacy was evaluated using receiver operating characteristic (ROC) curves. The H/M ratio and cardiac WR parameters scintigraphy exhibited excellent diagnostic efficacy for PD and PPS. The 4 h H/M ratio showed superior diagnostic performance with an area under the ROC curve (AUC) of 0.980. Background and time decay correction improved cardiac WR diagnostic performance (AUC = 0.963). Although P/B, S/B, and T/B ratios showed no significant differences for differential diagnosis, the WR values of the parotid and thyroid glands exhibited moderate diagnostic efficacy with AUCs of 0.648 and 0.638, respectively.

Conclusion: The heart H/M ratio and cardiac WR in ¹²³I-MIBG scintigraphy show high diagnostic efficacy for both diagnosing and differentiating PD. Including cardiac WR in routine assessments is recommended. The diagnostic potential of WR in the parotid and thyroid glands also holds promise for PD diagnosis. Incorporating these parameters could enhance the accuracy of PD diagnosis, particularly in clinical scenarios where concurrent cardiac disease may confound the diagnosis.

Background: Gliomas are the most common malignant primary tumors of the central nervous system. There is an urgent need for new convenient, targeted and specific imaging agents for gliomas. This study aimed to firstly evaluate the feasibility of ⁶⁸Ga-NOTA-RM26 PET/CT imaging in glioma and analyze the relationship between the imaging characteristics and glioma grade, classification and molecular alterations.

Results: Twenty-two patients were confirmed as glioma by surgery or biopsy. All patients exhibited ⁶⁸Ga-NOTA-RM26 uptake. SUV_max was chosen as the imaging marker for analysis. For all glioma patients, there were significant differences between grades (P = 0.047). For primary gliomas, SUV_max had good discrimination for both tumor classifications (P = 0.045) and grades (P = 0.03). There was a positive correlation (P < 0.01) between GRPR expression level and SUV_max. P53 mutations caused significant differences in SUV_max (P = 0.03).

Conclusions: This study is the first application of ⁶⁸Ga-NOTA-RM26 in glioma patients and confirmed the safety and efficacy in glioma patients. ⁶⁸Ga-NOTA-RM26 PET/CT has potential value in tumor grade, classification, and molecular alterations.

Trial registration: ClinicalTrials.gov: NCT06412952. Registered 26 April 2024, https://clinicaltrials.gov/study/NCT06412952.

Background: Superselective adrenal artery embolization (SAAE) represents a novel therapeutic strategy for managing primary aldosteronism (PA). Currently, the evaluation of its efficacy is primarily restricted to clinical indicators, with a notable deficiency in imaging evaluation methodologies. In recent years, several studies have investigated the application of ⁶⁸Ga-Pentixafor PET/CT for the classification of PA. However, there is a scarcity of specific research investigating the role of PET/CT in the evaluation of efficacy of this condition. Consequently, this study aims to evaluate the therapeutic efficacy of SAAE in patients with PA using ⁶⁸Ga-Pentixafor PET/CT, with the objective of establishing imaging evaluation methodologies for assessing PA patients post-SAAE treatment.

Results: Of the 27 patients, 2 achieved complete clinical remission, while 25 experienced partial remission. Biochemically, 13 patients attained complete remission, 13 had partial remission, and 1 did not. For patients with aldosterone-producing adenoma, both visual and semi-quantitative analyses of PET/CT effectively assessed changes in radioactive uptake of the lesion. For idiopathic hyperaldosteronism patients, PET/CT parameters were more effective than visual analysis in evaluating SAAE efficacy. A significant difference in the ΔTLR-40 min parameter was observed across biochemical outcomes (P = 0.041), with patients having ΔTLR-40 min ≥ 0.07 showing better outcomes (AUC = 0.789, P = 0.041).

Conclusions: ⁶⁸Ga-Pentixafor PET/CT enables timely assessment of therapeutic outcomes in patients with PA following SAAE, thereby improving clinical decision-making and patient management.

Background: In clinical practice, several radiopharmaceuticals are used for PSMA-PET imaging, each with distinct biodistribution patterns. This may impact treatment decisions and outcomes, as eligibility for PSMA-directed radioligand therapy is usually assessed by comparing tumoral uptake to normal liver uptake as a reference. In this study, we aimed to compare tracer uptake intraindividually in various reference regions including liver, parotid gland and spleen as well as the respective tumor-to-background ratios (TBR) of different ¹⁸F-labeled PSMA ligands to today's standard radiopharmaceutical ⁶⁸Ga-PSMA-11 in a series of patients with biochemical recurrence of prostate cancer who underwent a dual PSMA-PET examination as part of an individualized diagnostic approach.

Results: Differences in background activity among different PSMA-PET tracers lead to variations in tumor-to-background ratios (TBR). In [¹⁸F]F-DCFPyL-PET, TBR with the liver as the reference organ (TBR_liver) was comparable to [⁶⁸Ga]Ga-PSMA-11-PET, while [¹⁸F]F-PSMA-1007-PET and [¹⁸F]F-JK-PSMA-7-PET showed significantly lower values. Using the parotid gland as the reference (TBR_parotidgland), [¹⁸F]F-DCFPyL-PET exhibited significantly higher values, whereas [¹⁸F]F-PSMA-1007-PET and [¹⁸F]F-JK-PSMA-7-PET were comparable. For the spleen (TBR_spleen), [¹⁸F]F-JK-PSMA-7-PET was comparable, but [¹⁸F]F-DCFPyL-PET and [¹⁸F]F-PSMA-1007-PET showed significantly higher and lower values, respectively. An additional Bland-Altman analyses revealed low bias for [¹⁸F]F-DCFPyL-PET in TBR_parotidgland, whereas significant differences in TBR_liver and TBR_spleen for the other tracers resulted in higher bias.

Conclusion: Different PSMA-PET tracers exhibit distinct biodistribution patterns, leading to variations in tumor-to-background ratios (TBR) in reference organs such as the liver, parotid gland, and spleen. Patient selection for PSMA-directed radioligand therapy is currently based on a semiquantitative approach using the liver as a reference region in [⁶⁸Ga]Ga-PSMA-11-PET. Thus, the use of alternative [¹⁸F]-labeled tracers may result in under- or overestimation of a patient's suitability for therapy. This highlights the importance of a comprehensive understanding of the differences in tracer-specific uptake behavior for accurate decisions regarding PSMA-expression levels. However, as the patient cohort in this study is at earlier disease stages, the generalizability of these findings to later-stage patients remains unclear and requires further investigation.

Background: To study the feasibility of hepatobiliary scintigraphy (HBS) to improve selection and planning of patients with hepatocellular carcinoma (HCC) treated with holmium-166 (¹⁶⁶Ho)-microspheres radioembolization.

Results: Thirty-one patients with HCC were included and treated with ¹⁶⁶Ho- radioembolization as part of a prospective phase 2 study. Twenty-seven patients were eligible for analysis, 67% had a cirrhotic liver morphology on imaging, 70% had multifocal disease and 51% had bilobar disease. None of the patients had clinical signs of liver decompensation (Child Pugh ≤ B7, median MELD 9 or ALBI - 2.55). Global and regional hepatic function was based on manual delineation of HBS using 200 MBq ^99mTc-mebrofenine, acquired during screening and approximately three months after ¹⁶⁶Ho-radioembolization, referred to as liver clearance rate (LCR). In line with LCR at baseline, a significant correlation was found between LCR and lab results, including bilirubin, albumin, ALT, MELD-score, and ALBI-score (p < 0.05) during follow-up. HBS showed a significant decrease in median LCR (-16%; p = 0.0017) and volume (-17%; p = 0.0027) in the treated liver, without a significant increase in the non-treated liver. Median relative change in overall LCR in non-cirrhotics was 0% (range - 23-33%), in cirrhotics - 10% (range - 40 - 19%; p = 0.40).

Conclusion: HBS showed that hepatic function and volume significantly decreased in parts of the liver treated with ¹⁶⁶Ho-microspheres radioembolization in patients with HCC. Cirrhotic patients do not seem to have the capacity to increase hepatic function in the treated part of the liver.

Trial registration: Registry name: Clinicaltrials.gov.

Trial number: NCT03379844. Date of registration: 21 November 2017. Trial URL: https://clinicaltrials.gov/study/NCT03379844?cond=hcc&term=hepar primary&rank=1#study-overview .

Background: This study aimed to establish the optimal cutoff values for visual amyloid positivity using standardized uptake value ratios (SUVRs) in [¹⁸F]flutemetamol (FMM) positron emission tomography (PET) imaging. Given the variability in amyloid assessment, our goal was to determine cutoff values that enhance diagnostic accuracy and assist clinicians in reliably identifying amyloid positivity.

Results: The identified cutoff values for visual amyloid positivity were > 1.6 for the cerebellar gray matter, > 1.38 for the whole cerebellum, and > 0.63 for the pons, yielding high sensitivity (95.5%, 94.5%, and 95.8%, respectively) and specificity (91.2%, 94.3%, and 95.2%, respectively).

Conclusions: The SUVR cutoff values demonstrated excellent diagnostic performance, supporting their clinical use in assessing visual amyloid positivity in [¹⁸F]FMM PET imaging.

Background: Huntington's disease (HD) is a rare neurodegenerative disorder caused by an expansion of the CAG trinucleotide repeat in the huntingtin gene which encodes the mutant huntingtin protein (mHTT) that is associated with HD-related neuropathophysiology. Noninvasive visualization of mHTT aggregates in the brain, with positron emission tomography (PET), will allow to reliably evaluate the efficacy of therapeutic interventions in HD. This study aimed to assess the radiation burden of [¹⁸F]CHDI-650, a novel fluorinated mHTT radioligand, in humans based on both in vivo and ex vivo biodistribution in mice and subsequent determination of dosimetry for dosing in humans.

Results: Wild-type male and female CD-1 Swiss mice (n = 15/sex) were used to assess in vivo PET imaging-based and ex vivo biodistribution-based tracer distribution of [¹⁸F]CHDI-650 at 30-, 60-, 120-, 240- and 360-min post-injection. Three-dimensional volumes of interest of the organs were drawn on the co-registered PET/CT image and organs were collected after dissection. Organ radioactivity levels were determined using both modalities. The residence time was calculated and extrapolated to human phantoms. The absorbed and effective doses were computed with OLINDA/EXM 2.2 and IDAC-Dose2.1. Ex vivo and PET-imaging biodistribution of [¹⁸F]CHDI-650 showed rapid washout after 30 min in most of the organs with the highest uptake in the gallbladder and urine in mice. Extrapolation of the data to human phantoms with OLINDA showed a total mean in vivo based effective dose of 21.7 μSv/MBq with the highest equivalent organ dose in the urinary bladder wall (4.52 μSv/MBq). The total mean ex vivo based effective dose was calculated to be 20.6 μSv/MBq. The highest equivalent organ dose ex vivo in the urinary bladder wall was estimated to be 4.22 μSv/MBq. The predicted exposure in humans using IDAC-Dose correlated well to those obtained with OLINDA for both in vivo and ex vivo measurements (r = 0.9320 and r = 0.9368, respectively).

Conclusions: Dosimetry analysis indicated absorbed and effective doses of [¹⁸F]CHDI-650 are well below the recommended limits, suggesting that the radioligand is suitable for clinical assessment. Based on the highest effective dose estimates, an injection of 370 MBq in humans would result in a radiation dose of 8.03 mSv.