Value SUVmax Research Articles

Optimizing SUV Analysis: A Multicenter Study on Preclinical FDG-PET/CT Highlights the Impact of Standardization

PurposePreclinical imaging, with translational potential, lacks a standardized method for defining volumes of interest (VOIs), impacting data reproducibility. The aim of this study was to determine the interobserver variability of VOI sizes and standard uptake values (SUVmean and SUVmax) of different organs using the same [18F]FDG-PET and PET/CT datasets analyzed by multiple observers. In addition, the effect of a standardized analysis approach was evaluated.ProceduresIn total, 12 observers (4 beginners and 8 experts) analyzed identical preclinical [18F]FDG-PET-only and PET/CT datasets according to their local default image analysis protocols for multiple organs. Furthermore, a standardized protocol was defined, including detailed information on the respective VOI size and position for multiple organs, and all observers reanalyzed the PET/CT datasets following this protocol.ResultsWithout standardization, significant differences in the SUVmean and SUVmax were found among the observers. Coregistering CT images with PET images improved the comparability to a limited extent. The introduction of a standardized protocol that details the VOI size and position for multiple organs reduced interobserver variability and enhanced comparability.ConclusionsThe protocol offered clear guidelines and was particularly beneficial for beginners, resulting in improved comparability of SUVmean and SUVmax values for various organs. The study suggested that incorporating an additional VOI template could further enhance the comparability of the findings in preclinical imaging analyses.

Baseline Ga-68 PSMA PET-Derived Primary Tumor Parameters in Patients with Prostate Cancer and Their Association with Clinical Risk Stratification and Clinicopathologic Features

Abstract Aim This article evaluates whether parameters derived from the gallium-68-labeled prostate-specific membrane antigen (68Ga-PSMA) positron emission tomography/computed tomography (PET/CT) imaging studies of primary prostate cancer (PCa) lesions were associated with Gleason score (GS), D'Amico risk class, Candiolo nomograms, and the metastatic status of the disease. Methods We retrospectively evaluated newly diagnosed PCa patients who underwent 68Ga-PSMA PET/CT before therapy. Age, baseline serum prostate-specific antigen (PSA), and metastatic status were recorded. Maximal standardized uptake value (SUVmax), mean SUV (SUVmean), total lesion PSMA (TL-PSMA), and PSMA-derived tumor volume (PSMA-TV) were analyzed. The patients were grouped according to GS (GS ≤ 7 and GS ≥ 8), D'Amico risk classes (low intermediate and high-risk), and also based on their results with the Candiolo nomogram which normally creates five risk classes. For Candiolo classes, very-low risk and low-risk patients were pooled into the low-risk Candiolo (LRC) group, high and very high-risk patients were pooled into the high-risk Candiolo (HRC) group. The intermediate-risk Candiolo group was utilized as-is (IRC). Results Mean age was 67 ± 8 years, median PSA value was 14.3 (3–211). There were 82 patients with GS ≤ 7 and 38 patients with GS ≥ 8; intermediate D'Amico class comprised 32 patients, while the high D'Amico class comprised 88 patients. For Candiolo, there were 23 LRC, 40 IRC, and 57 HRC patients. PSMA-positive metastases were detected in 44 (36.7%) patients. The SUVmean, SUVmax, PSMA-TV, and TL-PSMA values of the primary tumor demonstrated significant differences when compared according to classifications for GS, D'Amico, LRC versus HRC, and metastatic versus nonmetastatic patients. Of note, TL-PSMA was the only parameter that varied significantly among all risk groups. Conclusion Primary tumor parameters obtained from baseline 68Ga-PSMA PET/CT are useful to distinguish PCa patients in terms of GS, D'Amico, Candiolo nomogram, and metastatic states. TL-PSMA appears to be the best parameter as it is the only parameter that can distinguish all risk groups from each other.

Quantitative Analysis of 99mTc-MDP SPECT-CT Data in Diagnosing Bone Metastases in Breast Cancer Patients

Background: In patients with advanced breast cancer (BC), distant metastases happen mainly in the skeleton. This study aimed to investigate the role of 99mTc-MDP SPECT/CT in the differential diagnosis of malignant bone lesions from degenerative benign bone diseases in female BC patients. Methods and Results: The study included 39 female BC patients who underwent a baseline 99mTc-MDP SPECT/CT bone scans. After lesion detection, a quantitative radiotracer uptake analysis was conducted, and the standardized uptake value (SUVmax) was identified in each patient, and the data were then statistically analyzed. SUVmax values were significantly higher in BC patients with malignant metastasis than in patients with degenerative changes (33.04±15.3 vs. 13.25±5.46 g/mL, P<0.05). The SUVmax cut-off value of 22.75 g/mL (25th percentile) obtained through box plot analysis can help to discriminate metastatic from degenerative lesions. The logistic regression analysis indicated that the SUVmax was a significant predictor of metastatic BL (P<0.001, OR = 159.90, B=5.07). Conclusion: Our results suggested that quantitative analysis of the 99mTc-MDP SPECT-CT data can improve diagnostic accuracy in differentiating malignant metastatic bone lesions from degenerative bone lesions in high-risk BC patients.

The Prognostic Significance of Tumor SUVmax Value in Pre- and Post-Chemoradiotherapy 18F-FDG PET/CT Imaging in Patients with Localized and Advanced Head and Neck Squamous Cell Carcinoma

Background: Some parameters of 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) can predict tumor chemosensitivity and survival in patients with head and neck squamous cell carcinoma (HNSCC). Aim: The aim of the study was to investigate the prognostic value of pre- and post-treatment maximum standardized uptake values (SUVmax) in 18F-FDG PET/CT imaging for predicting mortality in patients with HNSCC, as well as its prognostic value in terms of disease progression, overall survival (OS), and progression-free survival (PFS). Methods: This retrospective study included 37 patients with a histopathological diagnosis of HNSCCs between 2015 and 2018. In patients with HNSCC, the first 18F-FDG PET/CT imaging was performed for pre-treatment staging, and the second imaging was performed to evaluate post-treatment response. In these imaging studies, SUVmax values of the primary tumor before and after treatment were determined. After the second imaging, patients were re-evaluated and followed up. ROC analysis was used to determine the predictive value of 18F-FDG PET/CT SUVmax parameters in terms of death and progression, and Cox regression analysis was used to investigate the prognostic value in terms of OS and PFS. Results: Cut-off value 15 for SUVmax1 (pre-treatment) had a significant predictive value for mortality (P = 0.02). Cut-off value 3.1 for SUVmax2 (post-treatment) had a significant predictive value for progression (P = 0.024). In univariate analysis, both SUVmax1 and SUVmax2 values were significant prognostic factors for OS (P = 0.047, P = 0.004). However, for PFS, only the SUVmax2 value was a significant prognostic factor (P = 0.001). Conclusion: SUVmax1 value of the primary tumor at diagnosis in HNSCC patients has a predictive value for mortality and a prognostic value for OS. However, the SUVmax2 value in the primary tumor after treatment is a predictive factor for progression and a prognostic factor for both OS and PFS.

Comparison of an Affibody-based Molecular Probe and 18F-FDG for Detecting HER2-Positive Breast Cancer at PET/CT.

Background Human epidermal growth factor receptor 2 (HER2) affibody-based tracers could be an alternative to nonspecific radiotracers for noninvasive detection of HER2 expression in breast cancer lesions at PET/CT. Purpose To compare an affibody-based tracer, Al18F-NOTA-HER2-BCH, and fluorine 18 (18F) fluorodeoxyglucose (FDG) for detecting HER2-positive breast cancer lesions on PET/CT images. Materials and Methods In this prospective study conducted from June 2020 to July 2023, participants with HER2-positive breast cancer underwent both Al18F-NOTA-HER2-BCH and 18F-FDG PET/CT. HER2 positivity was confirmed with pathologic assessment (immunohistochemistry test results of 3+, or 2+ followed by fluorescence in situ hybridization, indicated HER2 amplification). Two independent readers visually assessed the uptake of tracers on images. Lesion uptake was quantified using the maximum standardized uptake value (SUVmax) and target to background ratio (TBR) and compared using a general linear mixed model. Results A total of 42 participants (mean age, 56.3 years ± 10.1 [SD]; 41 female) with HER2-positive breast cancer were included; 42 (100%) had tumors that were detected with Al18F-NOTA-HER2-BCH PET/CT and 40 (95.2%) had tumors detected with 18F-FDG PET/CT. Primary tumors in two of 21 participants, lymph node metastases in four of 21 participants, bone metastases in four of 15 participants, and liver metastases in three of nine participants were visualized only with Al18F-NOTA-HER2-BCH. Lung metastasis in one of nine participants was visualized only with 18F-FDG. Al18F-NOTA-HER2-BCH enabled depiction of more suspected HER2-positive primary tumors (26 vs 21) and lymph node (170 vs 130), bone (92 vs 66), and liver (55 vs 27) metastases than 18F-FDG. The SUVmax and TBR values of primary tumors and lymph node, bone, and liver metastases were all higher on Al18F-NOTA-HER2-BCH images than on 18F-FDG images (median SUVmax range, 10.4-13.5 vs 3.4-6.2; P value range, <.001 to .02; median TBR range, 2.7-17.6 vs 1.2-7.8; P value range, <.001 to .001). No evidence of differences in the SUVmax and TBR for chest wall or lung metastases was observed between Al18F-NOTA-HER2-BCH and 18F-FDG (P value range, .06 to .53). Conclusion PET/CT with the affibody-based tracer Al18F-NOTA-HER2-BCH enabled detection of more primary lesions and lymph node, bone, and liver metastases than PET/CT using 18F-FDG. ClinicalTrials.gov Identifier: NCT04547309 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Ulaner in this issue.

Effect of Epidermal Growth Factor Receptor Mutation on Positron Emission Tomography/Computed Tomography in Lung Cancer.

This study analyzed the effect of epidermal growth factor receptor (EGFR) mutations on fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) results in lung cancer and the pathological findings in patients subjected to surgery. A total of 210 patients diagnosed with lung cancer by F-18 FDG PET/CT at Inje University Busan Paik Hospital between January 2018 and December 2023 were recruited. EGFR mutation tests were performed on biopsy specimens. Overall, 78 patients (37.1%) with EGFR mutations were included in this study. Twenty-seven patients (12.9%) had distant metastases at the time of diagnosis. Of all patients, 69 (32.9%) underwent surgery at our hospital, and their pathological findings were analyzed. The maximum standardized uptake value (SUVmax) of F-18 FDG PET/CT was <10 in patients with EGFR mutations. Patients with EGFR mutations were not commonly diagnosed with diabetes. When analyzing the pathological findings after surgery in the 69 patients, adenocarcinoma was more common in those with EGFR mutations. In contrast, perineural invasion was more common in patients without EGFR mutations. When analyzing the results of 69 patients with postoperative pathology, 25 relapsed during the median follow-up of 21.7 months (range=0.9-58.4 months). Patients who underwent surgery and had EGFR mutations (n=26) exhibited lower recurrence rates compared to those without EGFR mutations. Disease-free survival was longer in patients with EGFR mutations. In non-small-cell lung cancer with an EGFR mutation, the F-18 FDG PET/CT SUVmax value and the probability of recurrence were lower. EGFR mutations are associated with low-glucose metabolism.

Expression of fibroblast activation protein in intrathoracic solitary fibrous tumor

PurposeFibroblast activation protein (FAP) is a serine integral membrane protease, the expression of which has been confirmed in various cancer types. Solitary fibrous tumors of the pleura (SFTP) are rare mesenchymal fibroblastic neoplasms. We present a case of 18F-labeled FAP inhibitor ([18F]FAPI-74) PET imaging and its correlation with histological FAP expression and review an SFTP series at our institution in relation to the extent of FAP expression. MethodsThis retrospective study included 13 patients who underwent surgery between March 2011 and December 2022 at our institute. One of the patients also underwent [18F]FAPI-74 PET imaging. We semi-quantitatively evaluated FAP expression in SFTPs using immunohistochemical staining and H-scores. ResultsNine of the 13 patients were male, with a median age of 64 years (range, 28–79 years). The median tumor size was 6.6 cm (1.1, 16 cm). In the pathological findings, expression levels of Ki67 were 1–5% in 12 of 13 cases. Furthermore, FAP expression was observed in all patients, and the median H-score was 160 (range, 10–280). The H-score of FAP expression in two of the 13 patients was low (10 in both), and that in two of the 13 patients was high (240 and 280). The SUVmax value of [18F]FAPI-74 PET was 3.57 in a patient in whom the H-score of FAP expression was 180. ConclusionsSFTPs expressed FAP to varying degrees in different patients and the [18F]FAPI-74 PET results in one patient reflected FAP expression in the tumor tissue.

The relationship between the uptake of alveolar bone inflammation and of cervical lymph nodes on fluoro-2-deoxy-D-glucose positron emission tomography.

To elucidate the relationships between the maximum standardized uptake value (SUVmax) of alveolar bone and those of lymph nodes (LNs) around the neck on 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET). The SUVmax values of alveolar bone and of level IA, level IB, and level IIA LNs of 174 patients, including those with and without active odontogenic inflammation, on PET/CT performed for a health check were retrospectively evaluated. The upper and lower jaws were divided into four blocks (right maxilla, left maxilla, right mandible, and left mandible). The SUVmax values of each block and of the LNs were calculated. The differences in the SUVmax of each LN level between patients with and without odontogenic inflammation, and the relationship between the SUVmax values of alveolar bone and of the LNs were analysed statistically. Significant differences in SUVmax values of bilateral level IB and IIA LNs were found between patients with and without odontogenic inflammation (Mann-Whitney U test: right level IB, P = .008; left level IB, P = .006; right level IIA, P < .001; left level IIA, P = .002), but not in bilateral level IA LNs (Mann-Whitney U test: right level IA, P = .432; left level IA, P = .549). The inflammatory site with the highest SUVmax in level IB LNs was the ipsilateral mandible (multivariate analysis: right, beta = 0.398, P < .001; left, beta = 0.472, P < .001), and the highest SUVmax in level IIA LNs was the ipsilateral maxilla (multivariate analysis: right, beta = 0.223, P = .002; left, beta = 0.391, P < .001). The SUVmax values of level IB and IIA LNs were associated with a tendency towards a higher SUVmax value of alveolar bone on 18F-FDG-PET.

Clinical significance of 18F-FDG-PET/CT for detection of incidental pre-malignant and malignant colonic lesions: correlation with colonoscopic and histopathological results

BackgroundIncidental colorectal fluorodeoxyglucose (FDG) uptake, observed during positron emission tomography/computed tomography (PET/CT) scans, attracts particular attention due to its potential to represent both benign and pre-malignant/malignant lesions. Early detection and excision of these lesions are crucial for preventing cancer development and reducing mortality. This research aims to evaluate the correlation between incidental colorectal FDG uptake on PET/CT with colonoscopic and histopathological results.MethodsRetrospective analysis was performed on data from all patients who underwent PET/CT between December 2019 and December 2023 in our hospital. The study included 79 patients with incidental colonic FDG uptake who underwent endoscopy. Patient characteristics, imaging parameters, and the corresponding colonoscopy and histopathological results were studied. A comparative analysis was performed among the findings from each of these modalities. The optimal cut-off value of SUVmax for 18F-FDG PET/CT diagnosis of premalignant and malignant lesions was determined by receiver operating characteristic (ROC) curves. The area under the curve (AUC) of SUVmax and the combined parameters of SUVmax and colonic wall thickening (CWT) were analyzed.ResultsAmong the 79 patients with incidental colorectal FDG uptake, histopathology revealed malignancy in 22 (27.9%) patients and premalignant polyps in 22 (27.9%) patients. Compared to patients with benign lesions, patients with premalignant and malignant lesions were more likely to undergo a PET/CT scan for primary evaluation (p = 0.013), and more likely to have focal GIT uptake (p = 0.001) and CWT (p = 0.001). A ROC curve analysis was made and assesed a cut-off value of 7.66 SUVmax (sensitivity: 64.9% and specificity: 82.4%) to distinguish premalignant and malignant lesions from benign lesions. The AUCs of the SUVmax and the combined parameters of SUVmax and CWT were 0.758 and 0.832 respectively.ConclusionFor patients undergo PET/CT for primary evaluation, imaging features of colorectal focal FDG uptake and CWT were more closely associated with premalignant and malignant lesions. The SUVmax helps determine benign and premalignant/malignant lesions of the colorectum. Moreover, the combination of SUVmax and CWT parameters have higher accuracy in estimating premalignant and malignant lesions than SUVmax.

Clinical value of semi-quantitative parameters in 68Ga-DOTANOC PET/CT in treatment and diagnostics of cranial meningioma in a single-center retrospective analysis

BackgroundThe value of somatostatin-analogon PET tracers in theranostics in cranial meningioma has been demonstrated in several studies however, the value of semi-quantitative parameters for therapy and patient outcome is still unclear.MethodsA retrospective study was performed comparing measured semi-quantitative 68Ga-DOTANOC PET/CT parameters (maximum standardized uptake value = SUVmax, mean standardized uptake value = SUVmean, and metabolic tumor volume = MTV) and calculated ratios (SUVmax tumor/to pituitary gland, SUVmax tumor to superior sinus sagittalis), versus WHO grades and overall outcome. Patients with histological confirmed meningioma or high probability for meningioma in previous cranial MRI were eligible.ResultsThirty-two patients from January 2018 to February 2023 were retrospectively included. WHO grade I meningioma was confirmed in 17 patients, WHO grade II in five patients, WHO grade III in two patients, while in eight patients diagnosis was solely based on MRI and 68Ga-DOTANOC PET/CT findings. In 12 cases stable disease was present, in 15 cases radiation therapy was chosen, in three cases neurosurgery was preferred while in two cases palliative care was chosen. Median SUVmax values increased with WHO grade (15.84, 17.22, and 28.4, p = 0.134, Kruskal–Wallis-test) and no statistically significant difference was present for MTV, SUVmax, and calculated ratios, although the ratio for SUVmax tumor to superior sinus sagittalis had the lowest value of p = 0.067.ConclusionIncreased SUVmax values in the tumor in 68Ga-DOTANOC PET/CT are associated with higher WHO grade, although further studies including larger patient collectives are needed to solidify this hypothesis.

Diagnostic performance of F-18 FDG PET/CT in differentiating autoimmune pancreatitis from pancreatic cancer: a systemic review and meta-analysis.

This study aims to evaluate the utility of F-18 FDG PET/CT in the non-invasive diagnosis of autoimmune pancreatitis (AIP) and differentiating it from pancreatic cancer (CaP) based on the amount and pattern of FDG uptake, as well as involvement of extra-pancreatic sites. A systematic search was conducted using PubMed, Scopus, Cochrane Library and Google Scholar. Only those studies that compared the findings of F-18 FDG PET/CT in terms of SUVmax, pattern of FDG uptake and presence of FDG-avid extra-pancreatic sites in both AIP and CaP were included. Studies were qualitatively assessed for risk of bias and publication bias. The diagnostic performance of parameters on PET/CT was examined through pooled sensitivity, specificity, diagnostic odd's ratio (DOR) and summary receiver operator characteristic (SROC) curve analysis. Six studies were included with a total of 580 patients. 178 patients had AIP (Age 18-90years, male, M: female, F ratio-8.4:1) and 402 patients had CaP (Age 22-88years, M:F ratio-1.5:1). Type of AIP was reported in only 3 studies, with the included cases predominantly being type 1 AIP. All studies were retrospective with heterogeneity and a risk on patient selection and index test. The FDG uptake, expressed as SUVmax, was lower in AIP with a weighted mean difference of -3.11 (95% confidence interval, CI: -5.28 to -0.94). To diagnose AIP, the pooled sensitivity, specificity and DOR of diffuse pattern of FDG uptake were 0.59 (95% CI: 0.51-0.66), 0.89 (95% CI: 0.86-0.92) and 21.07 (95% CI: 5.07-88.32), respectively, with an area under curve (AUC) of 0.717 on SROC analysis. The pooled sensitivity, specificity and DOR of FDG-avid extra pancreatic sites were 0.55 (95% CI: 0.45-0.65), 0.58 (95% CI: 0.52-0.64) and 2.33 (95% CI: 1.40-3.89), respectively, with an AUC of 0.632. On F-18 FDG PET/CT, a pancreatic lesion of AIP has a lower SUVmax value than CaP. A diffuse pattern of FDG uptake and presence of an extra-pancreatic FDG-avid site are nearly 21 times and twice more likely in AIP than CaP, respectively.

Retrospective analysis of thyroid incidentalomas detected by [68Ga]Ga-PSMA-11 PET/CT.

Prostate cancer patients, undergo imaging procedures, with [68Ga]Ga-PSMA-11 PET/CT (prostate-specific membrane antigen based positron emission tomography/computed tomography) utilized for primary and secondary staging. PSMA thyroid incidentalomas (PTI) are discovered in the thyroid gland while imaging prostate cancer patients with [68Ga]Ga-PSMA-11 PET/CT. The aim of the study was to determine the clinical significance of PTIs detected on [68Ga]Ga-PSMA-11 PET/CT. Another goal was to identify a possible threshold for the maximum standardized uptake value (SUVmax), above which a malignant growth could be suspected. A retrospective cross-sectional study. 769 patients with prostat cancer who underwent [68Ga]Ga-PSMA-11 PET/CT scans in the nuclear medicine department of a tertiary care hospital between January 2020 and December 2022 were retrospectively screened in this study. We analyzed 67 patients in whom PTI was detected. Patients who exceeded the inclusion criteria had their thyroid ultrasonography and ultrasonography -guided fine needle aspiration findings analyzed. PTI was discovered in 67 patients (8%). 42 patients who met the inclusion and exclusion criteria were included in the study. Of the 4 malignant patients (9.5%) in the study population, 2 were classified as TIRADS 3 and 2 were classified as TIRADS 4. The cut-off SUVmax value was found to be 5.6. With 100% sensitivity and 47.37% specificity, a cutoff SUVmax of 5.3 was determined through receiver-operator characteristic analysis in order to predict malignant cytology. PTI is a significant clinical finding; most of diffuse and focal uptakes are frequently related to benign diseases. Each center should establish its own a possible SUVmax cut-off over which a malignant lesion should be suspected.

Time-of-Flight PET/CT Imaging of Ga-68-Dotatate: Normal Pattern, SUV Quantification, and Differences from Non-Time-of-Flight Imaging

Purpose The biodistribution of gallium-68-dotatate (Ga-68-dotatate) and standardized uptake values (SUVs) using non-time-of-flight (TOF) positron emission tomography/computed tomography (PET/CT) cameras is well established. However, with the eventual retirement of older PET cameras and their replacement with newer, highly sensitive TOF PET/CT cameras, where SUVmax measurements are reportedly higher, updated knowledge of normal SUVmax range is needed and, to our knowledge, not previously reported. Our objectives are as follows: Methods Fifty consecutive patients referred routinely to our nuclear medicine service (20 men, 30 women; median age 55 years) with presumed neuroendocrine tumors underwent Ga-68-dotatate scans on a PET-CT camera having capability of reconstructing both TOF/non-TOF images. Region of interests (ROIs) were drawn around 24 normal structures as well as the primary lesion with abnormal radiotracer uptake and SUVmax was measured. The same ROI was analyzed using both algorithms simultaneously and both TOF and non-TOF SUVmax values were compared. Results Twelve hundred ROIs were evaluated. Non-TOF Ga-68-dotatate uptake in normal structures was in alignment with previously published studies. As compared to non-TOF, TOF images had better target to background ratios visually. TOF SUVmax was higher for all structures except for lung and brain. TOF SUVmax was more than double in adrenals/uncinate process of the pancreas; approximately 1.8 times in abnormal lesions, lymph nodes, pineal gland; and greater than 1.5 times in thyroid, breast, and pancreatic head. Conclusion Normal database of Ga-68-dotatate TOF SUVmax is provided for common structures to aid visual detection of abnormalities objectively. Overall, TOF SUVmax measures higher in identical ROIs, with abnormal lesions measuring approximately 1.8 times higher versus non-TOF technology. These findings need to be taken in consideration when comparing patient scans imaged on different PET/CT technologies.

Comparison of quantitative whole body PET parameters on [68Ga]Ga-PSMA-11 PET/CT using ordered Subset Expectation Maximization (OSEM) vs. bayesian penalized likelihood (BPL) reconstruction algorithms in men with metastatic castration-resistant prostate cancer

BackgroundPSMA PET/CT is a predictive and prognostic biomarker for determining response to [177Lu]Lu-PSMA-617 in patients with metastatic castration resistant prostate cancer (mCRPC). Thresholds defined to date may not be generalizable to newer image reconstruction algorithms. Bayesian penalized likelihood (BPL) reconstruction algorithm is a novel reconstruction algorithm that may improve contrast whilst preventing introduction of image noise. The aim of this study is to compare the quantitative parameters obtained using BPL and the Ordered Subset Expectation Maximization (OSEM) reconstruction algorithms.MethodsFifty consecutive patients with mCRPC who underwent [68Ga]Ga-PSMA-11 PET/CT using OSEM reconstruction to assess suitability for [177Lu]Lu-PSMA-617 therapy were selected. BPL algorithm was then used retrospectively to reconstruct the same PET raw data. Quantitative and volumetric measurements such as tumour standardised uptake value (SUV)max, SUVmean and Molecular Tumour Volume (MTV-PSMA) were calculated on both reconstruction methods. Results were compared (Bland-Altman, Pearson correlation coefficient) including subgroups with low and high-volume disease burdens (MTV-PSMA cut-off 40 mL).ResultsThe SUVmax and SUVmean were higher, and MTV-PSMA was lower in the BPL reconstructed images compared to the OSEM group, with a mean difference of 8.4 (17.5%), 0.7 (8.2%) and − 21.5 mL (-3.4%), respectively. There was a strong correlation between the calculated SUVmax, SUVmean, and MTV-PSMA values in the OSEM and BPL reconstructed images (Pearson r values of 0.98, 0.99, and 1.0, respectively). No patients were reclassified from low to high volume disease or vice versa when switching from OSEM to BPL reconstruction.Conclusions[68Ga]Ga-PSMA-11 PET/CT quantitative and volumetric parameters produced by BPL and OSEM reconstruction methods are strongly correlated. Differences are proportional and small for SUVmean, which is used as a predictive biomarker. Our study suggests that both reconstruction methods are acceptable without clinical impact on quantitative or volumetric findings. For longitudinal comparison, committing to the same reconstruction method would be preferred to ensure consistency.

Abstract PO3-27-01: Prediction of pathological complete response to neoadjuvant treatment in loco-regional advancedbreast cancer by using advanced PET/CT metabolic parameters

Abstract Prediction of pathological complete response to neoadjuvant treatment in loco-regional advanced breast cancer by using advanced PET/CT metabolic parameters. Abstract: Background: The standard treatment for locally advanced breast cancer (LABC) is neoadjuvant systemic therapy followed by surgery. The usefulness of FDG PET/CT for evaluating the treatment efficacy in breast cancer is well established; however, the role of quantitative functional PET/CT parameters, such as the metabolic tumor volume (MTV) and total lesion glycolysis (TLG), remains inconclusive. The aim of this study was to determine the correlation between quantitative functional parameters derived from PET/CT in LABC patients at staging and the response to neoadjuvant therapy. Methods: Seventy-eight consecutive patients (aged 25-82 y) with confirmed LABC (stages II-III) who underwent PET/CT as a part of their staging assessment and received neoadjuvant therapy followed by surgery were retrospectively included in this study. All patients underwent an FDG PET/CT at staging; and values of SUV max, SUV mean, MTV, and TLG were determined from the PET/CT studies. The patients were divided into two groups, based on the completeness of histopathologic response to neoadjuvant therapy, both in the primary tumor and axillary lymph nodes. Clinical, imaging and demographic data were collected from patient’s medical record. Results: A complete pathologic response (pCR) was achieved in 33/78 (42%) patients. Among patients with ER/PR positive, Her2-neu negative tumors, in 23/27 (85%) patients only partial pathologic response was reached; 91% of patients with ER/PR negative, Her2-neu positive and 43% of Triple-negative patients had complete pathological? response. For the primary breast tumor response, a higher SUV max, 10.7±5.34 for pCR vs. 7.24±4.62 for non-pCR group was measured, p-value=0.003; threshold value of 6.625. A higher SUV mean in the primary tumor resulted in a significantly higher rate of pCR, 5.95±2.36 vs 4,4±2.16, p=0.004, with a threshold value of 5.795. Neither MTV, not TLG were predictive parameters of the primary tumor response. For lymph nodes response, SUV max and SUV mean had no role in the prediction of pCR. Statistically significant difference however, was found between pCR and non-pCR in MTV values in the involved lymph nodes, with a median =2.13 cm³ [0-7.85] in pCR group vs 5.43 cm³ [3.11-15.3] in non-pCR, p=0.01 (threshold value 2.375) as well as in TLG measurements, with a median of 4.64 [0-19.8] vs. 12.7 [3.21-23.1], p=0.047, (25-75 IQR). Conclusion: Primary breast tumor SUV max/mean values have a significant correlation with the treatment response and threshold values were found. Low MTV and TLG measurements in lymph nodes may predict pCR. Neither MTV nor TLG had were found to have a significant role in the prediction of the primary tumor response. Citation Format: Maisun Shamya, Olga Kagna, Zohar Keidar, Tala Palchan-Hazan, Salem Billan, Roxolyana Abdah-Bortnyak. Prediction of pathological complete response to neoadjuvant treatment in loco-regional advancedbreast cancer by using advanced PET/CT metabolic parameters [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-27-01.

A PSMA PET/CT-based risk model for prediction of concordance between targeted biopsy and combined biopsy in detecting prostate cancer.

This study is to investigate the diagnostic value of 68Ga-PSMA-11 in improving the concordance between mpMRI-TB and combined biopsy (CB) in detecting PCa. 115 consecutive men with 68Ga-PSMA-11 PET/CT prior to prostate biopsy were included for analysis. PSMA intensity, quantified as maximum standard uptake value (SUVmax), minimum apparent diffusion coefficient (ADCmin) and other clinical characteristics were evaluated relative to biopsy concordance using univariate and multivariate logistic regression analyses. A prediction model was developed based on the identified parameters, and a dynamic online diagnostic nomogram was constructed, with its discrimination evaluated through the area under the ROC curve (AUC) and consistency assessed using calibration plots. To assess its clinical applicability, a decision curve analysis (DCA) was performed, while internal validation was conducted using bootstrapping methods. Concordance between mpMRI-TB and CB occurred in 76.5% (88/115) of the patients. Multivariate logistic regression analyses performed that SUVmax (OR= 0.952; 95% CI 0.917-0.988; P= 0.010) and ADCmin (OR= 1.006; 95% CI 1.003-1.010; P= 0.001) were independent risk factors for biopsy concordance. The developed model showed a sensitivity, specificity, accuracy and AUC of 0.67, 0.78, 0.81 and 0.78 in the full sample. The calibration curve demonstrated that the nomogram's predicted outcomes closely resembled the ideal curve, indicating consistency between predicted and actual outcomes. Furthermore, the decision curve analysis (DCA) highlighted the clinical net benefit achievable across various risk thresholds. These findings were reinforced by internal validation. The developed prediction model based on SUVmax and ADCmin showed practical value in guiding the optimization of prostate biopsy pattern. Lower SUVmax and Higher ADCmin values are associated with greater confidence in implementing mono-TB and safely avoiding SB, effectively balancing benefits and risks.

Abstract PO5-01-05: An Open-label, Single-center Study Assessing the Efficacy of PH-based Regimen as Neoadjuvant Therapy for HER2-positive Early-stage Breast Cancer: Integrating Genomic Features and Functional Imaging

Abstract Background: Pathological complete response (pCR) has been demonstrated as a surrogate endpoint for disease-free and overall survival in HER2-positive early-stage breast cancer (EBC). Trastuzumab (H) plus pertuzumab (P) improved pCR rates in patients with HER2-positive early-stage breast cancer. Nevertheless, biomarkers to assess the effectiveness of this treatment in the neoadjuvant setting are still unclear. This study aims to evaluate the effectiveness of fluorodeoxyglucose positron emission tomography (18F-FDG-PET) and 68 Ga-Affibody HER2 Imaging PET (HER2-PET) in HER2 EBC neoadjuvant therapy, and to identify novel biomarkers for this regimen. Methods: HER2-positive EBC patients were prospectively recruited at Fudan University Shanghai Cancer Center between April 2020 and March 2022. All patients received the 1 dose of HP, followed by 6 cycles of docetaxel (T), carboplatin (Cb), and HP. We use FoundationOne to evaluate the genomic alterations before treatment. In addition, 18F-FDG-PET and HER2 PET were performed at baseline, after 1 cycle of HP, and after 6 cycles of TCbHP, to assess the effectiveness of these examinations in the prediction of pCR and correlation to disease burden. All patients were received surgery and completed 1 year of HP-based regimen in the adjuvant setting. Results: A total of 61 patients with a median age of 49 years were included. Among them, 93.5% of patients are node positive. 75.8% of the patients reported adverse events (AEs), primarily grade 1 and 2. The incidence of serious AEs was 6.6%. Patients exhibiting a greater than 40% reduction in SUVmax of 18-FDG-PET or HER2-PET scans from baseline to the fifth day after the initial HP treatment were classified as the treatment-sensitive group. The pCR rate for the 18-FDG-PET-sensitive group was 79.3%, while for the insensitive group was 48.1%. For HER2-PET scans, the pCR rate was 70.0% in the sensitive group and 59.3% in the non-sensitive group. To evaluate the potential biomarkers, 25 patients (13 pCR and 12 non-pCR) were evaluated with FoundationOne, with the identification of 1,321 somatic alterations. The most frequently altered genes were ERBB2 (100%), TP53 (96%), CDK12 (76%), MYC (56%), CCND1 (44%), PIK3CA (40%), and SRSF2 (36%). In the pCR group, we found PPM1D (38.5%) and RAD21 (38.5%) were altered more frequently than the non-pCR group. PIK3CA alterations were significantly reduced in pCR group, only 23% of cases are affected compared to 58.3% in non-pCR group. Patients were non-pCR had more MDM4 (41.7%) and ZNF217 (41.7%) alterations than pCR patients. Conclusion: The SUVmax value of 18-FDG-PET and HER2-PET scans are correlated well with the tumor burden and the residual disease in the HER2 EBCs. The reduction of SUVmax could predict pCR but need further exploration. Patients with alterations in PPM1D and RAD21 have a favorable response to the TCbHP regimen. Conversely, alterations in PIK3CA, MDM4, and ZNF217 are associated with treatment resistance. These results indicate the significance of 18-FDG-PET and HER2-PET in monitoring treatment effectiveness. The biomarker analysis in this study will help us understand the mechanism of HER2 positive breast cancer treatment resistance and assisting in tailoring personalized therapy. Clinical trial information: NCT04281641. Citation Format: Ming Chen, Benlong Yang, Sun Yuyun, Linxiaoxi Ma, Song Shaoli, Min He, Zhi-Ming Shao, Bingqiu Xiu, Jiong Wu. An Open-label, Single-center Study Assessing the Efficacy of PH-based Regimen as Neoadjuvant Therapy for HER2-positive Early-stage Breast Cancer: Integrating Genomic Features and Functional Imaging [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-01-05.

Prognostic significance of 68Ga-FAPI PET/CT in patients with bone metastases in various cancers.

This study aimed to compare 18FDGPET/CT in patients who develop bone metastases due to various cancers and to investigate the prognostic significance of the 68FAPI-PET/CT SUVmax value for survival. Patients with bone metastases who underwent both 68Ga-FAPI PET/CTand18FDGPET/CT within a 1week period were included in this retrospective study. The effect of the SUVmax value of bone lesions on overall survival was analyzed. A total of 75 eligible patients with 139 bone lesions were included in this study. The median age of the patients was 55 (30-83) and 48(64%) patients were newly diagnosed. The primary lesion median 68Ga-FAPI PET/CT SUVmax value was higher than the median 18FDGPET/CT SUVmax (10.75 versus 6.7). Bone lesions 68Ga-FAPI PET/CT SUVmax median (IQR) were 7.8 (4.6-13.2), and 18FDGPET/CT SUVmax of bone lesions were 5.9 (3.8-8.2). More bone lesions were detected on 68Ga-FAPI PET/CT than on 18FDGPET/CT(median IQR 4 [1-9] versus 2 [1-6] (p = 0.014). The extra lesions observed on 68Ga-FAPI PET/CT were mostly sclerotic bone lesions (p = 0.001).68Ga-FAPI PET/CT SUVmax was significantly higher in vertebra and thorax lesions (p = 0.011 and p = 0.018, respectively). While the bone lesion 68Ga-FAPI PET/CT SUVmax affected the OS, the 18FDGPET/CT SUVmax value did not affect the OS (p < 0.001 and p = 0.079, respectively). In ROC analysis, a cut-off-off value of 68Ga-FAPI PET/CT SUVmax > 7.7 was found for OS (AUC: 0.619). The median OS in the group above the cut-off value was worse than that in the group below the cut-off value (32 versus 45) months (p = 0.002). In the multivariate analysis for OS, the 68Ga-FAPI PET/CT SUVmax of bone lesions was an important parameter, as well as cancer subtype, ALP level, and disease occurrence. 68Ga-FAPI PET/CT detected more bone lesions and higher SUVmax values than 18FDGPET/CT in various cancers. The prognostic value of the SUVmax value of 68Ga-FAPI PET/CT bone lesions was observed regardless of disease subtype.

Can 18 F FDG PET/CT metabolic parameters be used to noninvasively differentiate between different histopathological subtypes and Fuhrman grades of renal cell cancer?

To evaluate relationship between metabolic PET metabolic parameters and size of the primary tumor, various histopathological subtypes of renal cell carcinoma (RCC) and Fuhrman grade of the tumors. Retrospective analysis of 93 biopsy-proven RCC patients who underwent pretreatment flourine 18 flourodeoxyglucose PET/computed tomography ( 18 F FDG PET/CT) was performed. Quantitative PET parameters, size of the primary tumor, histopathological subtypes and Fuhrman grades of the tumor were extracted. We tried to assess if there was any significant difference in the metabolic patterns of various histopathological subtypes of RCCs, Fuhrman grade of the tumors and size of the primary tumor. A significant correlation was noted between the size of primary tumor and maximum standardized uptake value (SUV max ), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) ( P < 0.01, P < 0.001 and P < 0.001, respectively). SUV max values correlated significantly with the histopathological subtype ( P < 0.001). Further sub-analyses was also done by segregating the patients into Low grade (Fuhrman grade 1 and 2) vs. High grade (Fuhrman grade 3 and 4). SUV max , MTV and TLG were significantly different between high grade vs. low grade tumors. ROC analysis yielded cut off values for SUV max , MTV and TLG to differentiate between high grade from low grade tumors. FDG PET/CT with the use of metabolic PET parameters can differentiate between different histopathological subtypes of RCC. Incorporation of metabolic parameters into clinical practice can potentially noninvasively identify patients with low-grade vs. high-grade RCC.

Evaluation of metabolic parameters of microsatellites stable and instable colorectal cancer patients via PET/CT

Aims: Microsatellite instability has been determined as an important indicator in selecting chemotherapy drugs in colorectal cancer. Within the scope of this research, we aimed to elucidate the pathology reports and determine whether the metabolic parameters detected by PET/CT differ in MSI-positive and negative patients. Methods: A total of 35 patients were analyzed retrospectively. The patient population consisted of patients who applied to the Nuclear Medicine Department with a diagnosis of colon or rectum cancer, underwent PET/CT imaging for staging purposes, and were operated on. Results: A total of 35 colon or rectum cancer patients were included in this retrospective analysis. When microsatellite instability was analyzed among the patients, it was found that female patients comprised 4 microsatellite instability-positive and 16 microsatellite instability-negative individuals. On the other hand, 5 of the males were microsatellite instability positive, and 10 were microsatellite instability negative. The mean SUVmax value was 16.4±8.2, SUVmean was 8.1±1.9, TLG was 392.4±520.8, and MTV was 26.5±25.4 in the microsatellite instability-positive individuals. On the other hand, the mean SUVmax value was 22.7±9.7, SUVmean was 5.2±2.2, TLG was 316.4±325.7, and MTV was 21.7±21.7 in the microsatellite instability-negative individuals. Conclusion: With the advancement of image analysis technology, MTV, and TLG, volumetric indexes derived from 18F-FDG PET have been proposed for risk stratification of cancer patients. Regarding the outcomes of this research, the semiquantitative and metabolic parameters obtained by PET/CT are not different in colorectal cancer cases with instable and stable microsatellites.