Annals of Nuclear Medicine最新文献

Introduction

¹²³I-FP-CIT (¹²³I-Ioflupane) SPECT shows strong accumulation in the striatum, but morphological standardization is challenging due to low accumulation outside the striatum, particularly in subjects with marked striatal decline. In this study, morphological standardization without MRI was achieved using the adaptive template registration (ATR) method to create a subject-specific optimized template with weighted images of normal-type and egg-shape-type templates. The accuracy of a quantitative method for calculating the ratio with nonspecific accumulation in the occipital lobe was evaluated by placing voxels-of-interest (VOI) on standardized images, particularly targeting the striatum.

Methods

The average images of eight subjects, demonstrating normal-type and egg-shape-type tracer accumulation in ¹²³I-Ioflupane SPECT, were utilized as normal and disease templates, respectively. The study included 300 subjects that underwent both ¹²³I-Ioflupane SPECT and MRI for the diagnosis of suspected Parkinson's disease or for exclusion diagnosis. Morphological standardization of SPECT images using structural MRI (MRI-based method) was considered the standard of truth (SOT). Three morphological standardizations without MRI were conducted. The first involved conventional morphological standardization using a normal template (fixed template method), the second employed the ATR method, with a weighted template, and the third used the split-ATR method, processing the left and right striatum separately to address asymmetrical accumulation. VOIs were set on the striatum, caudate, putamen as regions of specific accumulation, and on the occipital lobe as a reference region for nonspecific accumulation.

Results

Results showed significant and robust linearity in the striatal accumulation ratios for all templates when compared with the occipital lobe accumulation ratio when using the MRI-based method. Comparing intra-class correlations for different linearities, the ATR method and split-ATR method demonstrated higher linearity in the striatum, caudate, and putamen. The split-ATR method showed similar improvements, although more linearity than some of the ATR methods; the effectiveness of the Split-ATR method may vary by image quality, and further validation of its effectiveness in diverse asymmetric accumulation cases seemed warranted.

Conclusion

The use of optimized templates, such as the ATR and split-ATR methods, improved reproducibility in fully automated processing and demonstrated superior linearity compared to that of MRI-based method, in the ratio to the occipital lobe. The ATR method, which enables morphological standardization when using SPECT images only, proved highly reproducible for clinical quantitative analysis of striatal accumulation, facilitating its clinical use.

Objective

This study aimed to identify a relatively robust SUV for guiding clinical practice through quantitative measurement and comparison of various normalization methods based on the SUV of ^99mTc-MDP in the normal spine and pelvis using an integrated SPECT/CT scanner.

Methods

Between June 2017 and September 2019, a total of 500 oncology patients (mean age, 60.9; men, 66.0%) who underwent bone SPECT/CT scans with ^99mTc-MDP were enrolled in this retrospective study. The mean SUV (SUV_mean) of 4962 spinal and pelvic bones was calculated based on the patients’ body weight (BW), lean body mass (LBM), bone mineral content (BMC), body surface area (BSA), and body mass index (BMI), defined as SUV_bw, SUV_lbm, SUV_bmc, SUV_bsa, and SUV_bmi, respectively. The coefficients of variation (CoVs) of the aforementioned parameters were compared, and the correlation and multiple linear regression analyses were used to compare the extent to which these parameters were affected by sex, age, height, weight, BMI, and CT values.

Results

The average SUVs in the normal spine and pelvis displayed a relatively wide variability: 4.573 ± 1.972 for SUV_bw, 3.555 ± 1.517 for SUV_lbm, 0.163 ± 0.071 for SUV_bmc, 0.124 ± 0.052 for SUV_bsa, and 1.668 ± 0.732 for SUV_bmi. In general, SUV_bsa had relatively lowest CoV (42.1%) in all vertebrae and pelvis compared with other SUVs. For correlation analyses, all SUVs displayed weak but significant correlations with age and CT values. For regression analyses, SUV_bsa was influenced only by age, BMI, and CT values independently. The effects of these variables on SUV_bsa were all smaller than those on conventional SUV_bw.

Conclusions

The SUVs of ^99mTc-MDP in normal bone derived from quantitative bone SPECT/CT could serve as a reference for evaluating tumor bone metastasis, but it should be assessed on a site-specific basis. SUV_bsa exhibited superior robustness among all the SUV normalization variations, indicating potential clinical applications.

Objectives

This study aims to evaluate the value of the dynamic and static quantitative metabolic parameters derived from ¹⁸F-fluorodeoxyglucose (FDG)–positron emission tomography/CT (PET/CT) in the differential diagnosis of metastatic from non-metastatic lymph nodes (LNs) in lung cancer and to validate them based on the results of a previous study.

Methods

One hundred and twenty-one patients with lung nodules or masses detected on chest CT scan underwent ¹⁸F-FDG PET/CT dynamic + static imaging with informed consent. A retrospective collection of 126 LNs in 37 patients with lung cancer was pathologically confirmed. Static image analysis parameters include LN-SUV_max and LN-SUV_max/primary tumor SUV_max (LN-SUV_max/PT-SUV_max). Dynamic metabolic parameters including the net influx rate (K_i) and the surrogate of perfusion (K₁) and of each LN were obtained by applying the irreversible two-tissue compartment model using in-house Matlab software. K_i/K₁ was then calculated as a separate marker. Based on the pathological findings, we divided into a metastatic group and a non-metastatic group. The χ² test was used to evaluate the agreement of the individual and combined diagnosis of each metabolic parameter with the gold standard. The receiver-operating characteristic (ROC) analysis was performed for each parameter to determine the diagnostic efficacy in differentiating non-metastatic from metastatic LNs with high FDG-avid. P < 0.05 was considered statistically significant.

Results

Among the 126 FDG-avid LNs confirmed by pathology, 70 LNs were metastatic, and 56 LNs were non-metastatic. For ROC analysis, in separate assays, the dynamic metabolic parameter K_i [sensitivity (SEN) of 84.30%, specificity (SPE) of 94.60%, accuracy of 88.89%, and AUC of 0.895] had a better diagnostic value than the static metabolic parameter SUV_max (SEN of 82.90%, SPE of 62.50%, accuracy of 74.60%, and AUC of 0.727) in differentiating between metastatic from non-metastatic LNs groups, respectively. In the combined diagnosis group, the combined SUV_max + K_i diagnosis had a better diagnostic value in the differential diagnosis of metastatic from non-metastatic LNs, with SEN, SPE, accuracy, and AUC of 84.3%, 94.6%, 88.89%, and 0.907, respectively.

Conclusions

When the cutoff value of K_i was 0.022 ml/g/min, it had a high diagnostic value in the differential diagnosis between metastasis and non-metastasis in FDG-avid LNs of lung cancer, especially in improving the specificity. The combination of SUV_max and K_i is expected to be a reliable metabolic parameter for N-staging of lung cancer.

Objective

When patients administered ¹⁷⁷Lu-DOTATATE are released or discharged from rooms where radiopharmaceuticals are used, the time required for release or discharge varies across patients. This study investigated whether the amount of radioactivity accumulated on ¹¹¹In-somatostatine receptor scintigraphy (¹¹¹In-SRS) performed prior to treatment can predict the 1 cm dose-equivalent rate at a distance of 1 m from the patient on the day after ¹⁷⁷Lu-DOTATATE administration.

Methods

Whole-body planar ¹¹¹In-SRS images were acquired for 21 patients. Pixel values within whole-body and abdominal (35 × 25 cm) regions of interest (ROIs) were converted to radioactivity dose (MBq). The 1 cm dose-equivalent rate (µSv/h) at a distance of 1 m from the patient 18.3 ± 0.5 h after administration of ¹⁷⁷Lu-DOTATATE was measured using an ionization survey meter.

Results

The following relationships were observed between the radioactivity on ¹¹¹In-SRS and the 1 cm dose-equivalent rate on the day after administration of ¹⁷⁷Lu-DOTATATE: whole-body ROI: y = 0.16x + 5.01 (r = 0.56, p = 0.009), abdominal ROI: y = 0.27x + 5.13 (r = 0.63, p = 0.002). The regression equations indicate that patients cannot be released or discharged from the radiopharmaceutical room the day after ¹⁷⁷Lu-DOTATATE administration if the whole-body and abdominal ROI doses are greater than 81 and 48 MBq, respectively, on ¹¹¹In-SRS.

Conclusions

The amount of radioactivity accumulated on ¹¹¹In-SRS may be a predictor of release criteria for patients receiving ¹⁷⁷Lu-DOTATATE.

Background

In 2021, the tubarial salivary glands (TSGs) were newly identified on prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) as macroscopic glands in the nasopharyngeal wall. However, the relative contribution of the TSGs to the total salivary gland function, and consequently on the development of xerostomia after external beam radiotherapy (EBRT) or PSMA-targeted radionuclide therapy (RNT) is not known. Therefore, we aimed to determine the presence of the TSGs and to quantify uptake in the TSGs on PSMA PET.

Methods

Qualitative and quantitative analyses were performed on ⁶⁸Ga-PSMA-11 PET/CT scans of 100 patients with prostate cancer. The mean and maximum standardized uptake value (SUVmean and SUVmax) in the TSGs were measured and compared to the parotid, submandibular and sublingual salivary glands (PSGs, SMSGs and SLSGs, respectively). Furthermore, proportional function of the TSGs was compared to the PSGs, SMSGs and SLSGs based on the total organ PSMA (TO-PSMA).

Results

The TSGs were visible on 95% of the ⁶⁸Ga-PSMA-11 PET/CT scans. The normalized median SUVmean and SUVmax was significantly higher for the PSGs (p < 0.001) and SMSGs (p < 0.001) compared to the TSGs, but not for the SLSGs (p = 0.242 and p = 0.300, respectively). The normalized median TO-PSMA was significantly higher for the PSGs (p < 0.001) and SMSGs (p < 0.001), and significant lower for the SLSGs (p < 0.001) compared the TSGs.

Conclusions

The SUVmean, SUVmax and TO-PSMA of the TSGs were most comparable to the SLSGs. However, the measured PSMA uptake may be disproportional towards the saliva production. Therefore, future studies should focus on the relation between PSMA uptake and salivary function before and after PSMA therapy.

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy. Patients who receive systematic care typically have a better prognosis. RAI treatment plays a key role in eradicating any remaining thyroid lesions in DTC patients, hence decreasing the risk of distant metastases and cancer recurrence. As research continues to advance, RAI treatment is becoming more and more individualized. Because of the excellent prognosis for DTC patients, there is a relatively broad window for RAI treatment, making it easy to overlook when to receive RAI treatment. However, research on this issue can help patients with varying recurrence risk stratification make better decisions about when to begin RAI treatment following surgery, and physicians can schedule patients based on the severity of their disease. This will improve patient prognosis and lessen needless anxiety in addition to helping solve the problems of unjust healthcare resource distribution. In this review, we will mainly discuss the target population of RAI treatment as well as studies that examine the impact of RAI treatment timing on patient outcomes. In an effort to discourage DTC patients and physicians from selecting RAI therapy at random, we also review the possible negative effects of this treatment.

Primary progressive aphasia (PPA) is a disease known to affect the frontal and temporal regions of the left hemisphere. PPA is often an indication of future development of dementia, specifically semantic dementia (SD) for frontotemporal dementia (FTD) and logopenic progressive aphasia (LPA) as an atypical presentation of Alzheimer’s disease (AD). The purpose of this review is to clarify the value of 2-deoxy-2-[18F]fluoro-D-glucose (FDG)-positron emission tomography (PET) in the detection and diagnosis of PPA. A comprehensive review of literature was conducted using Web of Science, PubMed, and Google Scholar. The three PPA subtypes show distinct regions of hypometabolism in FDG-PET imaging with SD in the anterior temporal lobes, LPA in the left temporo-parietal junction, and nonfluent/agrammatic Variant PPA (nfvPPA) in the left inferior frontal gyrus and insula. Despite the distinct patterns, overlapping hypometabolic areas can complicate differential diagnosis, especially in patients with SD who are frequently diagnosed with AD. Integration with other diagnostic tools could refine the diagnostic process and lead to improved patient outcomes. Future research should focus on validating these findings in larger populations and exploring the therapeutic implications of early, accurate PPA diagnosis with more targeted therapeutic interventions.

Purpose

This study aims to compare the calculated absorbed dose in target organs and tumors obtained using the different imaging protocols and the calculation methodologies implemented by HERMES HybridViewer dosimetry software for ¹⁷⁷Lu-PSMA I&T and ¹⁷⁷Lu-DOTATATE therapy.

Methods

Multiple time-point whole-body planar images and one SPECT/CT image were acquired from 18 patients including ¹⁷⁷Lu-PSMA I&T (13 patients) and ¹⁷⁷Lu-DOTATATE treatment (5 patients) after administration of 3.80–8.58 GBq injected activity. The regions of interest were drawn in the whole body, kidneys, liver, urinary bladder, salivary glands, and tumors to determine the time-integrated activity (TIA) in source organs. Absorbed doses in target organs were calculated according to the Medical Internal Radiation Dose (MIRD) scheme using the HERMES HybridViewer dosimetry integrated with OLINDA/EXM V.2.1 that utilizes the non-uniform rational B-splines (NURBS) for computational digital phantom.

Results

The planar-based dosimetry showed a higher dose per injected activity compared to the hybrid-based dosimetry, primarily due to organ overlap. The highest difference in absorbed dose between the imaging scenarios was observed in the spleen with a variation of up to 51.6%, while the difference for other target organs and tumors was less than 40%.

Conclusion

The dosimetry calculation derived from the 2D planar-based method consistently demonstrates a significantly higher absorbed dose in organs and tumors compared with the hybrid-based method. However, the hybrid method outperforms the planar method in terms of tumor visualization and overlap-free organ delineation.

Aim

The study aims to determine the physiological and pathophysiological distribution of the radiopharmaceutical (Ga⁶⁸-PSMA-617) and investigate whether there are differences in distribution according to the laboratory, histopathological and clinical findings that can affect image evaluation. Also, we aimed to determine cut-off values to distinguish physiological and pathological uptake in prostate, bone, and lymph nodes.

Materials and Methods

229 prostate cancer patients who underwent Ga⁶⁸-PSMA PET/CT at our department were retrospectively analyzed. The patients were grouped according to PET/CT results, Gleason scores, PSA values, received treatments, metastatic status and other laboratory values. The SUV values of the organs, tissues, and pathological lesions of the patients in these subgroups were compared among themselves.

Results

No significant difference was detected in the physiological uptake of lymph nodes and bone between the groups. In the group with patients that received androgen deprivation therapy (ADT), the bone metastasis SUV values were found to be higher and the SUV values of the submandibular gland and renal cortex were found to be lower (Mann–Whitney U, p = 0.043; 0.004; 0.01, respectively). In the group with patients who received radiotherapy, the normal prostate tissue SUV values were determined to be higher (Mann–Whitney U, p = 0.009). The SUV values of the submandibular gland, muscle, liver, and blood pool were found to be lower in the group of patients with high serum LDH values. The cut-off SUVmax value was determined to be 6.945 (sensitivity 89.6%, specificity 98.1%) for primary prostate lesion; 4.72 for lymph node metastasis; 4.25 for bone metastasis. The serum PSA cut-off value to distinguish the negative/positive groups was found to be 1,505 (sensitivity 79.7%, specificity 77.3%).

Conclusion

In conclusion, PSMA-617 demonstrates a similar biodistribution with other PSMA ligands. The physiological uptake of lymph nodes and bone which are mostly metastasized in prostate cancer, are not affected by the factors we examined. It should be kept in mind that the normal prostate tissue uptake may increase in patients receiving radiotherapy, and the physiological/pathological uptake of the organs may differ due to the changes in PSMA expression in patients receiving ADT, tumor burden, and kidney function may affect the biodistribution.