SUVmax Of Lesions Research Articles

Role of 68Ga-PSMA PET/CT in Initial Staging of Prostate Cancer and Correlation with PSA and Gleason Score

Background Prostate cancer is the second most common male malignancy. Its prognosis depends on the tumor stage as well as its aggressiveness; expressed histopathologically by Gleason scores. Furthermore, optimal patient management depends on the tumor stage. 68Ga PSMA PET/CT has a wide spectrum of uses in prostate malignancy, some of them are comprehensively studied while others are still under investigation. The most widely accepted use is the accurate initial staging of cancer prostate as well as predicting the long-term outcome, with SUVmax being a promising prognostic parameter correlating significantly with other established prognostic parameters, including the Gleason score and the PSA levels. Objective To evaluate the role of 68GA- PSMA PET/CT in initial staging of prostate cancer and correlate with PSA level and Gleason score. Methods A prospective descriptive study over the course of 6 months. It included patients with pathologically proven prostate cancer referred for a PSMA PET/CT scan for initial staging without any treatment or interventions. Results 68Ga-PSMA PET/CT scans of 36 patients were evaluated for local staging (primary prostatic lesions, extra-prostatic spread, and seminal vesicle invasion), regional nodal staging, and metastatic spread (extra-regional lymph nodes, osseous lesions, and visceral lesions). PET/CT findings as well as the SUVmax of the most avid lesions were correlated with PSA level, Gleason scores, as well as Gleason grade risk groups. A statistically significant relationship was found between PSA level and SUVmax of prostatic lesion as well as that of the most avid metastatic regional lymph node, the presence of extra-regional lymph nodal spread, the presence of osseous metastatic lesions, the presence of seminal vesicle invasion, extra-prostatic extension, and the presence of PSMA-avid regional lymph nodal spread. On the other hand, a statistically significant relationship was found between Gleason scores and the presence of regional lymph nodal spread and osseous metastatic lesions. Lastly, a statistically significant relationship was found between Gleason grading risk groups and the presence of regional lymph nodal spread and osseous metastatic lesions. Conclusion 68Ga-PSMA PET/CT is a powerful staging and stratifying tool for the majority of prostate cancer patients, being significantly correlated with PSA level and Gleason scores. However, patients with low PSA scores still pose a dilemma as they showed significantly low PSMA uptake, rendering the use of 68Ga-PSMA PET/CT for staging in such patients controversial. 68Ga-PSMA PET/CT based imaging findings should ideally be supported with histopathological documentation and/or follow-up imaging results in order to confirm the nature of detected lesions and help establish accurate sensitivity and specificity of 68Ga-PSMA PET/CT.

Total-body [68Ga]Ga-PSMA-11 PET/CT improves detection rate compared with conventional [68Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer.

The purpose of this study was to assess whether total-body [68Ga]Ga-PSMA-11 PET/CT could improve the detection rate compared with conventional [68Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer. Two hundred biochemical recurrent prostate cancer patients with similar clinicopathological characteristics were included, of whom 100 patients underwent early total-body [68Ga]Ga-PSMA-11 PET/CT and diuretic-delayed total-body [68Ga]Ga-PSMA-11 PET/CT, and the other 100 patients received early conventional [68Ga]Ga-PSMA-11 PET/CT and diuretic-delayed conventional [68Ga]Ga-PSMA-11 PET/CT. The detection rates of total-body [68Ga]Ga-PSMA-11 PET/CT and conventional [68Ga]Ga-PSMA-11 PET/CT were compared using a chi-square test and stratified analysis. The image quality of total-body [68Ga]Ga-PSMA PET/CT and conventional [68Ga]Ga-PSMA-11 PET/CT was compared based on subjective scoring and objective parameters. Subjective scoring was conducted from background noise and lesion prominence using a 5-point scale. Objective parameters were evaluated by SUVmax, SUVmean, the standard deviation (SD) of SUV, and the signal-to-noise ratio (SNR) of liver and gluteus maximus. The SUVmax of the recurrent lesions was also measured. The liver SD of the total-body [68Ga]Ga-PSMA-11 PET/CT was significantly lower than that of conventional [68Ga]Ga-PSMA-11 PET/CT, the SNR was significantly higher than that of conventional [68Ga]Ga-PSMA-11 PET/CT, and the subjective evaluation was significantly better than that of conventional [68Ga]Ga-PSMA-11 PET/CT. The detection rate of total-body [68Ga]Ga-PSMA PET/CT for biochemical recurrence of prostate cancer was significantly higher than that of conventional [68Ga]Ga-PSMA-11 PET/CT (91.0% vs. 74.0%, P = 0.003). Total-body [68Ga]Ga-PSMA-11 PET/CT had better detection efficiency for patients with a Gleason score ≤ 8 or PSA ≤ 2ng/ml. The advantages of diuretic-delayed total-body [68Ga]Ga-PSMA-11 PET/CT were more obvious. Total-body [68Ga]Ga-PSMA-11 PET/CT could significantly improve the detection rate compared with conventional [68Ga]Ga-PSMA-11 PET/CT in patients with biochemical recurrent prostate cancer.

Predictive value of 18F-FDG PET/CT multi-metabolic parameters and tumor metabolic heterogeneity in the prognosis of gastric cancer.

We aimed to investigate the predictive value of pre-treatment 18F-FDG PET/CT multi-metabolic parameters and tumor metabolic heterogeneity for gastric cancer prognosis. Seventy-one patients with gastric cancer were included. All patients underwent 18F-FDG PET/CT whole-body scans prior to treatment and had pathologically confirmed gastric adenocarcinomas. Each metabolic parameter, including SUVmax, SUVmean, MTV, and TLG, was collected from the primary lesions of gastric cancer in all patients, and the slope of the linear regression between the MTV corresponding to different SUVmax thresholds (40% × SUVmax, 80% × SUVmax) of the primary lesions was calculated. The absolute value of the slope was regarded as the metabolic heterogeneity of the primary lesions, expressed as the heterogeneity index HI-1, and the coefficient of variance of the SUVmean of the primary lesions was regarded as HI-2. Patient prognosis was assessed by PFS and OS, and a nomogram of the prognostic prediction model was constructed, after which the clinical utility of the model was assessed using DCA. A total of 71 patients with gastric cancer, including 57 (80.3%) males and 14 (19.7%) females, had a mean age of 61 ± 10 years; disease progression occurred in 27 (38.0%) patients and death occurred in 24 (33.8%) patients. Multivariate Cox regression analysis showed that HI-1 alone was a common independent risk factor for PFS (HR: 1.183; 95% CI: 1.010-1.387, P < 0.05) and OS (HR: 1.214; 95% CI: 1.016-1.450, P < 0.05) in patients with gastric cancer. A nomogram created based on the results of Cox regression analysis increased the net clinical benefit for patients. Considering disease progression as a positive event, patients were divided into low-, intermediate-, and high-risk groups, and Kaplan-Meier survival analysis showed that there were significant differences in PFS among the three groups. When death was considered a positive event and patients were included in the low- and high-risk groups, there were significant differences in OS between the two groups. The heterogeneity index HI-1 of primary gastric cancer lesions is an independent risk factor for patient prognosis. A nomogram of prognostic prediction models constructed for each independent factor can increase the net clinical benefit and stratify the risk level of patients, providing a reference for guiding individualized patient treatment.

Performance of 18F-FDG PET/MR on TNM staging of pancreatic cancer compared with 18F-FDG PET/CT: A retrospective cohort study

PurposeThis study aimed to evaluate the TNM staging accuracy of 18F-FDG PET/MR compared with 18F-FDG PET/CT in patients with pancreatic cancer. Materials and methodsIn this retrospective cohort study, a total of 88 patients (53 men, 35 women, mean age 64.56±10.77 years) with pathologically confirmed pancreatic cancer who underwent 18F-FDG PET/CT and 18F-FDG PET/MR successively on the same day were enrolled. The maximal and peak standardized uptake values (SUVmax and SUVpeak) of pancreatic cancer lesions on PET/MR and PET/CT imaging were measured respectively. According to the 8th edition AJCC staging system of pancreatic adenocarcinoma, two experienced readers reviewed and assessed the PET/CT and PET/MR images independently for TNM staging. Using the diagnosis of enhanced CT, histopathological diagnosis and/or the clinical follow-up as the reference, the diagnostic performance of PET/CT and PET/MR were compared using the McNemar test. ResultsCompared with 18F-FDG PET/CT (63.64%), 18F-FDG PET/MR (85.23%) exhibited significantly higher diagnostic accuracy of T staging (P<0.05). In N staging, the diagnostic accuracy of PET/MR (81.4%) was higher than that of PET/CT (74.42%) but the difference was not statistically significant. In M staging, no significant difference was found between the diagnostic performance of PET/MR (96.59%) and PET/CT (92.05%). However, PET/MR detected more liver metastases in 11/18 patients and the clinical staging was upstaged in four patients compared to PET/CT. Both SUVmax and SUVpeak of pancreatic tumors showed strong correlations between PET/MR and PET/CT imaging (r=0.901 and 0.923, respectively; P<0.05). ConclusionsCompared with 18FFDG PET/CT, 18FFDG PET/MR showed better performance in the TNM staging of pancreatic cancer, especially in T staging and detection of liver metastases.

Performance of 68Ga-Labeled Fibroblast Activation Protein Inhibitor PET/CT in Evaluation of Erdheim-Chester Disease: A Comparison with 18F-FDG PET/CT.

Erdheim-Chester disease (ECD) involves multiple organs and tissues and has diverse manifestations, which makes it difficult to distinguish lesions caused by ECD from those caused by other diseases. Variable degrees of fibrosis are present in ECD. Therefore, we conducted a prospective cohort study to explore the ability of 68Ga fibroblast activation protein inhibitor (68Ga-FAPI) PET/CT to detect lesions in ECD patients. Methods: Fourteen patients diagnosed with ECD, as confirmed by histology, were included in this study. For every patient, 68Ga-FAPI PET/CT and 18F-FDG PET/CT were conducted within 1 wk. The positive rate and SUVmax of the lesions in the involved organs were compared between the examinations. Results: The most commonly involved organs were bone (100%), heart (57.1%), lung (57.1%), kidney (42.9%), and peritoneum or omentum (35.7%); other common manifestations were intracranial infiltration (50%) and cutaneous infiltration (35.7%). 68Ga-FAPI PET/CT detected 64 of 67 lesions in 14 patients, whereas 18F-FDG PET/CT detected 51 of 67 lesions (P = 0.004). The SUVmax for 68Ga-FAPI PET/CT was significantly higher than the SUVmax for 18F-FDG PET/CT of the heart (4.9 ± 2.4 vs. 2.8 ± 1.2, respectively; P = 0.050), lung or pleura (6.8 ± 4.9 vs. 3.1 ± 1.3, respectively; P = 0.025), peritoneum or omentum (5.7 ± 3.6 vs. 2.8 ± 1.7, respectively; P = 0.032), and kidney or perinephric infiltration (4.9 ± 1.2 vs. 2.9 ± 1.1, respectively; P = 0.009). Conclusion: The detectivity of 68Ga-FAPI PET/CT is superior to that of 18F-FDG PET/CT. Moreover, 68Ga-FAPI PET/CT has a better image contrast and higher SUVmax for lesions in multiple organs including the heart, lungs, peritoneum, and kidneys. 68Ga-FAPI PET/CT is a promising tool to assess pathologic features and disease extent in ECD patients.

CT radiomics analysis of primary colon cancer patients with or without liver metastases: a correlative study with [18F]FDG PET uptake values.

Utilizing [18F]Fluoro-2-deoxy-D-glucose Positron Emission Tomography/Computed Tomography ([18F]FDG PET/CT) scans on primary colon cancer (CC) patients including with liver metastases (LM), we aimed to determine the relationship between structural CT radiomic features and metabolic PET standard uptake value (SUV) in these patients. A retrospective analysis was performed on 60 patients with primary CC, of which 40 had liver metastases that were more than 2 cm in diameter. [18F]FDG PET/CT was used to calculate SUVmax, and 42 CT radiomic characteristics were extracted from non-enhanced CT images. Tumors were manually segmented on fused PET/CT scans by two experienced nuclear medicine physicians. Sixty primary CC and forty LM lesions were segmented accordingly. In the cases of multiple LM lesions, the lesion with the largest diameter was chosen for segmentation. In a univariate analysis approach, we used Spearman correlation with multiple testing correction (Benjamini-Hutchberg false discovery rate (FDR), α=0.05) to ascertain the relationship between SUVmax and CT radiomic features. Twenty-two (52.3%) and twenty-six (61.9%) CT radiomic features were found to be significantly correlated with SUVmax values of primary CC (n=60) and LM (n=40) lesions, respectively (FDR-corrected p value <0.05 and 0.6 < |ρ| < 1). GLCM_homogeneity (ρ = 0.839), GLCM_dissimilarity (ρ = -0.832), GLZLM_ZLNU (ρ = 0.827), and GLCM_contrast (ρ = -0.815) were the 4 features most correlated with SUVmax in CC. On the other hand, in LM, the 4 features most correlated with SUVmax were GLRLM_LRHGE (ρ = 0.859), GLRLM_LRE (ρ = 0.859), GLRLM_LRLGE (ρ = 0.857), and GLRLM_RP (ρ = -0.820). We investigated the relationship between SUVmax of preoperative primary CC lesions and their LM with CT radiomic features. We found some CT radiomic features having relationships with the metabolic characteristics of lesions. This work suggests that non-invasive predictive imaging biomarkers for precision medicine can be derived from CT radiomic.

The potential role of 68Ga-FAPI-04 PET/CT for screening malignancy in suspected colonic lesions.

Benign colonic lesions like tubular adenoma may show intense uptake on F-18-FDG PET/CT and can be mistaken for malignancy. In this study, we evaluated the role of 68Ga-FAPI-04 PET/CT for discriminating the benign and malignant colonic lesions. Forty patients with diagnosis of colorectal cancer who had undergone 18F-FDG-PET/CT and 68Ga-FAPI-04 PET/CT for initial staging were retrospectively analyzed. The unexpected foci of uptake in colon on 18F-FDG PET/CT were compared with 68Ga-FAPI-04 PET/CT with lesion and background SUVmax. The primary colorectal lesion SUVmax on both PET/CTs was similar. A total of 9 incidental colon lesions in 7 patients were detected showing intense 18F-FDG uptake and no 68Ga-FAPI-04 uptake. All of the lesions were consistent with tubular adenoma histopathologically. 68Ga-FAPI PET/CT may have a crucial role for discrimination of benign and malignant colonic lesions and avoid the unnecessary interventions and extended surgeries in patients with colorectal cancer.

Higher Preoperative Maximum Standardised Uptake Values (SUVmax) Are Associated with Higher Biochemical Recurrence Rates after Robot-Assisted Radical Prostatectomy for [68Ga]Ga-PSMA-11 and [18F]DCFPyL Positron Emission Tomography/Computed Tomography.

This study aimed to investigate the association between the 68Ga- or 18F-radiolabeled prostate-specific membrane antigen (PSMA) tracer expression, represented by the maximum standardised uptake value (SUVmax) of the dominant intraprostatic lesion, and biochemical recurrence (BCR) in primary prostate cancer (PCa) patients prior to robot-assisted radical prostatectomy (RARP). This was a retrospective, multi-centre cohort study of 446 patients who underwent [68Ga]Ga-PSMA-11 (n = 238) or [18F]DCFPyL (n = 206) Positron Emission Tomography/Computed Tomography (PET/CT) imaging prior to RARP. SUVmax was measured in the dominant intraprostatic PCa lesions. [18F]DCFPyL patients were scanned 60 ([18F]DCFPyL-60; n = 106) or 120 ([18F]DCFPyL-120; n = 120) minutes post-injection of a radiotracer and were analysed separately. To normalise the data, SUVmax was log transformed for further analyses. During a median follow-up of 24 months, 141 (30.4%) patients experienced BCR. Log2SUVmax was a significant predictor for BCR (p < 0.001). In the multivariable analysis accounting for these preoperative variables: initial prostate-specific antigen (PSA), radiologic tumour stage (mT), the biopsy International Society of Urological Pathology grade group (bISUP) and the prostate imaging and reporting data system (PI-RADS), Log2SUVmax was found to be an independent predictor for BCR in [68Ga]Ga-PSMA-11 (HR 1.32, p = 0.04) and [18F]DCFPyL-120 PET/CT scans (HR 1.55, p = 0.04), but not in [18F]DCFPyL-60 ones (HR 0.92, p = 0.72). The PSMA expression of the dominant intraprostatic lesion proved to be an independent predictor for BCR in patients with primary PCa who underwent [68Ga]Ga-PSMA-11 or [18F]DCFPyL-120 PET/CT scans, but not in those who underwent [18F]DCFPyL-60 PET/CT scans.

Diagnostic values of delayed additional FDG PET/CT scan in the evaluation of cardiac sarcoidosis.

This study aimed to compare the contribution of 18F-fluorodepxyglucose (FDG) positron (PET)/ computed tomography (CT) acquisition of early and delayed scans in patients with cardiac sarcoidosis (CS). Twenty-three patients with CS (median age: 69years; 11 women) were retrospectively evaluated using dual-phase FDG PET/CT. All patients were instructed to consume a low-carbohydrate diet followed by fasting for 18h before FDG injection to reduce physiological myocardial uptake. PET/CT was acquired at 60min (early) and 100min (delayed) after FDG administration. Focal and focal on diffuse uptake on visual analysis was considered positive for CS. A semi-quantitative analysis was performed using the maximum standardized uptake value (SUVmax) of the cardiac lesion and the mean SUV (SUVmean) of the blood pool. Significant myocardial FDG uptake was observed in 21 patients (91.3%) in the early acquisition group and in 23 patients in the delayed scan group (100%). Compared to the early scan, the delayed scan showed a significantly higher SUVmax of the cardiac lesion [median, 4.0; IQR (interquartile range, 2.9 to 7.0) vs. 5.8 (IQR 3.7 to 10.1); P = 0.0030] and a significantly lower SUVmean of blood pool [median, 1.3 (IQR, 1.2 to 1.4) vs. 1.1 (IQR, 0.9 to 1.2); P < 0.0001]. Delayed FDG PET/CT acquisition improves detection accuracy in patients with CS compared to early scans with washout of the blood pool activity. Therefore, it can contribute to a more accurate assessment of CS.

68Ga-DOTANOC PET/CT for Screening and Surveillance of Von Hippel-Lindau (VHL) disease.

Hereditary tumor syndrome Von Hippel-Lindau (VHL) disease is characterized by various benign and malignant tumors that are known to express somatostatin receptors (SSTR). We evaluated the role of 68Ga-DOTANOC PET/CT scan in patients with positive germline mutation of the VHL gene, presented initially or on follow-up, for the detection of recurrent or synchronous/metachronous lesions. Fourteen patients (8 males; 6 females) with mean age 30 ± 9.86years were retrospectively analyzed, were tested positive for VHL on gene dosage analysis, and underwent 68Ga-DOTANOC PET/CT scan for disease evaluation. The number and site of lesions were determined. The tracer uptake was analyzed semi-quantitatively by calculating the maximum standardized uptake values (SUVmax) of lesion. Four of the 14 patients underwent scan for initial diagnosis as baseline, 6 patients for post-therapy disease status, and 4 patients for initial diagnosis as well as follow-up evaluation of the disease. A total of 67 lesions were detected in 14 patients. The sites of lesions were cerebellar/vertebral/spinal (17; mean SUVmax = 7.85); pancreatic neuroendocrine tumor (NET) (11; mean SUVmax = 20.64); retina (3; mean SUVmax = 10.46); pheochromocytoma (10; mean SUVmax = 16.32); paragangliomas (3; mean SUVmax = 10.65); pancreatic cyst (9; mean SUVmax = 2.54); and renal cyst (8; mean SUVmax = 1.56) and miscellaneous lesions constituted 6 lesions. Our results show that 68Ga-DOTANOC PET/CT may be a useful modality for screening and follow-up of associated tumors in patients with germline gene mutation for VHL. It can be used as a one-stop imaging modality for VHL patients and may substitute for separate radiological investigations, making it more convenient for patients in terms of time and cost.

Standardised Uptake Value in Organ Confined Prostate Cancer in 68-Ga- Prostate-Specific Membrane Antigen Positron Emission Tomography-Computed Tomography Scan and its Correlation with Prostate Specific Antigen Level and Gleason Score.

A positron emission tomography (PET) scan and a computed tomography (CT) scan are an integral part of oncological imaging and other modalities such as magnetic resonance imaging, CT or bone scintigraphy have some limitations in staging the workup of prostate carcinoma. Combined with tissue-specific markers like prostate-specific membrane antigen (PSMA), positron emitter-based functional imaging results have improved. Our study aimed to determine the Standardised Uptake Value (SUVmax) in prostate adenocarcinoma that is confined to the organ in Ga-68-PSMA PET-CT scans and how it correlates with prostate-specific antigen (PSA) levels and Gleason score (GS). This cross-sectional study was conducted at Sindh Institute of Urology and Transplantation (SIUT), Karachi, and includes subjects referred for a Ga68-PSMA PET-CT scan from September 2017 to January 2022. Histopathologic-proven adenocarcinoma prostate patients with organ-confined disease and PSA levels obtained within 6 weeks before the PSMA-PET-CT scan were included in the study. PET-CT images were semi-quantitatively analysed by measuring SUVmax and the result was interpreted using statistical software SPSS version 22.0. A total of 154 patients were analysed. The mean age of patients was 66.57 ± 8.86 years. The GS of all patients ranges from 6 to 10. The mean and median PSA levels were 32.33 ng/mL (range: 0.004-306.00) and 14.20 ng/mL, respectively. The mean SUVmax of all prostatic lesions was 14.67 ± 12.58 and the median value was 10.76. SUVmax was higher in patients with a PSA level of more than ten than those with a <10. The correlation of SUVmax with PSA and GS showed a significant correlation. The SUVmax of organ-confined prostate cancer correlates well with PSA level and GS Median SUVmax and PSA directly relate to GS.

Relationship between SUVmax on 18F-FDG PET and PD-L1 expression in liver metastasis lesions after colon radical operation

PurposeOur study was to investigate the correlation correlation between FDG uptake and PD-L1 expression of liver metastasis in patients with colon cancer, and to determine the value of FDG-PET in predicting PD-L1 expression in liver metastasis of colon cancer.MethodsA total of 72 patients with confirmed liver metastasis of colon cancer were included in this retrospective study. The PD-L1 expression and immune cell infiltrating of tumors were determined through immunohistochemistry staining. The SUVmax of liver metastasis lesions were assessed using 18 F-FDG PET/CT. The correlation between PD-L1 expression and the clinicopathological were evaluated by the Cox proportional hazards model and the Kaplan-Meier survival analysis.ResultsPD-L1 expression was significantly correlated with FDG uptake (SUVmax), tumor size, differentiation, survival and cytotoxic T cells infiltration in liver metastasis of colon cancer (P < 0.05). And liver metastases with high counts of infiltrating cytotoxic T cells showed greater FDG uptake than those with low counts of infiltrating cytotoxic T cells. The SUVmax of liver metastases and the degree of differentiation of metastases were closely related to PD-L1 expression, and were independent risk factors.The combined assessment of SUVmax values and tthe degree of differentiation of metastase can help determine PD-L1 expression in liver metastasis of colon cancer.ConclusionsFDG uptake in liver metastasis of colon cancer was positively correlated with the PD-L1 expression and the number of cytotoxic T cells infiltration. The joint evaluation of two parameters, SUVmax and degree of differentiation, can predict PD-L1 expression in liver metastases.

Correlation of Quantitative Diffusion-Weighted MR Parameters and SUVmax from 18-FDG PET-CT in Lung Cancer: A Prospective Observational Study

Abstract Background Diffusion-weighted magnetic resonance imaging (DW-MRI) sequences report the cellularity in tissues and 18-fluorodeoxyglucose (18-FDG) positron emission tomography–computed tomography (PET-CT) provides information on glucose metabolism in cells, associated to tumor aggressiveness. The aim of this study was to assess the correlation between quantitative diffusion-weighted magnetic resonance parameters and maximum standardized uptake value (SUVmax) using 18-FDG PET-CT in lung cancer and metastatic lymph nodes. Methods Histologically proven 29 patients of lung cancers were subjected to 18-FDG PET-CT and DW-MRI (parameters: repetition time/time to echo [TR/TE] = 4,000/76 ms; b-values = 0, 400, and 800 s/mm2) between June 2018 and June 2019. SUVmax was calculated on the PET-CT images representing region of interest (ROI) in the tumor. The apparent diffusion coefficient (ADC) values were quantified by placing an ROI over the tumor at a high b-value of 800 mm2/s. Statistical analyses for correlation between SUVmax and ADC were done using Pearson's correlation coefficient (r). Results Significant negative correlation was observed between analyses of ADC and SUVmax for primary lesions of all nonsmall-cell lung cancers (NSCLCs; p &lt; 0.05) and its histological subtype adenocarcinoma (p &lt; 0.05) but not squamous cell carcinomas (p = 0.35). Significant negative correlation was also observed for metastatic lymph nodes of adenocarcinoma (p &lt; 0.05) but not for metastatic lymph nodes of all NSCLCs (p = 0.05) or squamous cell carcinomas (p = 0.55). Conclusions Diffusion-weighted imaging (DWI) with ADC may represent a new prognostic marker due to a significant negative correlation between ADC determined by DWI and SUVmax by PET-CT in NSCLCs. Furthermore, DWI-MRI of the thorax can be added to routine 18-FDG PET-CT for staging and response assessment in lung cancer in prospects.

A Novel Risk Calculator Incorporating Clinical Parameters, Multiparametric Magnetic Resonance Imaging, and Prostate-Specific Membrane Antigen Positron Emission Tomography for Prostate Cancer Risk Stratification Before Transperineal Prostate Biopsy

BackgroundProstate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) can detect multiparametric magnetic resonance imaging (mpMRI)-invisible prostate tumours and improve the sensitivity of detection of prostate cancer (PCa) in comparison to mpMRI alone. Numerous risk calculators have been validated as tools for stratification of men at risk of being diagnosed with clinically significant (cs)PCa. ObjectiveTo develop a novel risk calculator using clinical parameters and imaging parameters from mpMRI and PSMA PET/CT in a cohort of patients undergoing mpMRI and PSMA PET/CT before biopsy. Design, setting, and participantsA total of 291 men from the PRIMARY prospective trial underwent mpMRI and PSMA PET/CT before transperineal prostate biopsy with sampling of systematic and targeted cores. Outcome measurements and statistical analysisNovel risk calculators were developed using multivariable logistic regression analysis to predict detection of overall PCa (International Society of Urological Pathology grade group [GG] ≥1) and csPCa (GG ≥2). The risk calculators were then compared with the European Randomised Study of Screening for Prostate Cancer risk calculator incorporating mpMRI (ERSPC-MRI). Resampling methods were used to evaluate the discrimination and calibration of the risk calculators and to perform decision curve analysis. Results and limitationsAge, prostate-specific antigen, prostate volume, and mpMRI Prostate Imaging-Reporting and Data System scores were included in the MRI risk calculator, resulting in area under the receiver operating characteristic curve (AUC) values of 0.791 for overall PCa (GG ≥1) and 0.812 for csPCa (GG ≥2). Addition of the maximum standardised uptake value (SUVmax) on PSMA PET/CT for the prostate lesion, and of SUVmax for the mpMRI lesions for the MRI-PSMA risk calculator resulted in AUCs of 0.831 for overall PCa and 0.876 for csPCa (≥ISUP2).The ERSPC-MRI risk calculator had AUCs of 0.758 (p = 0.02) for overall PCa and 0.805 (p = 0.001) for csPCa. Both the MRI and MRI-PSMA risk calculators were superior to the ERSPC-MRI for both overall PCa and csPCa. ConclusionsThese novel risk calculators incorporate clinical and radiological parameters for stratification of men at risk of csPCa. The risk calculator including PSMA PET/CT data is superior to a calculator incorporating mpMRI data alone. Patient summaryWe evaluated a new risk calculator that uses clinical information and results from two types of scan to predict the risk of clinically significant prostate cancer on prostate biopsy. This risk model can guide patients and clinicians in shared decision-making and may help in avoiding unnecessary prostate biopsies.

CD8 cell PET imaging with 89-Zr-crefmirlimab berdoxam (crefmirlimab) in patients with metastatic renal cell carcinoma (mRCC) receiving checkpoint inhibitors (CPIs): Association with response and tissue CD8 expression.

4551 Background: Novel imaging modalities using frequently expressed RCC antigens, such as CAIX, have shown promise in early-stage disease (Shuch B et al ASCO GU 2023). In advanced RCC, no tissue-based biomarkers have been well established to predict outcome with contemporary regimens, e.g., checkpoint inhibitors (CPIs) or targeted therapy (TT). We hypothesize that functional imaging of CD8 T-cells (CD8s) with crefmirlimab (a ~80 kDA 89Zr-labelled minibody with high affinity for CD8) may predict response given the essential role of CD8 T-cells (CD8s) in mediating CPI response. Methods: Eligible pts had pathologically verified RCC, metastatic disease and an intent to initiate standard of care CPI therapy. Patients received crefmirlimab PET/CT within 1 wk of CPI infusion and 4-6 weeks after initiating therapy. Baseline biopsy was mandated, along with repeat biopsy 0-2 weeks following the second PET/CT scan. PET signal was characterized as SUVmax, SUVpeak and SUVmean of the biopsied lesions, up to 5 index lesions and representative CD8 avid lymph nodes. Mean SUVmax in responders and non-responders were compared using students t-test (1-sided). CD8 expression in tissue was characterized as the number of positive cells per mm2; PET avidity and CD8 expression were compared using the Spearman correlation coefficient. Results: 17 pts (9 M: 8 F) were enrolled; most pts had clear cell histology (12; 71%) followed by unclassified (3; 17%) and papillary (2; 12%). The most commonly rendered CPI-based regimens were nivolumab alone (6 pts; 35%) and cabozantinib/nivolumab (3 pts; 17%). Follow-up data was available in 15 of the patients. By RECIST v1.1, 3 of 15 patients were classified as responders (best overall response [BOR] of complete response or partial response) and 12 patients were classified as non-responders (BOR of stable disease or progressive disease). Average SUVmax, SUVpeak and SUVmean per patient among all quantified index lesions and representative lymph nodes were 10.02, 6.95 and 6.11 for baseline and 8.82, 6.23 and 5.39 during treatment, respectively. Average SUVmax at baseline was 14.68 in responders to CPI and 8.28 in non-responders (P=0.006). On treatment SUVmax was 10.93 in responders to CPI and 8.22 in non-responders (P=0.19). A strong correlation between CD8 expression in baseline tissue and normalized SUVmean was observed (r=0.77; 95%CI 0.53-0.91). Conclusions: To our knowledge, this is the first series in RCC to demonstrate that functional imaging of immune cells (here, CD8s) may segregate response to CPIs, with responders having a higher baseline SUV and a larger decrement in SUV with therapy. Our results are bolstered by a significant correlation between tissue and imaging CD8 expression. Larger studies are underway to validate this noninvasive strategy. Clinical trial information: NCT03802123 .

Comparative study of the quantitative accuracy of oncological PET imaging based on deep learning methods.

[18F] Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is an important tool for tumor assessment. Shortening scanning time and reducing the amount of radioactive tracer remain the most difficult challenges. Deep learning methods have provided powerful solutions, thus making it important to choose an appropriate neural network architecture. A total of 311 tumor patients who underwent 18F-FDG PET/CT were retrospectively collected. The PET collection time was 3 min/bed. The first 15 and 30 s of each bed collection time were selected to simulate low-dose collection, and the pre-90s was used as the clinical standard protocol. Low-dose PET was used as input, convolutional neural network (CNN, 3D Unet as representative) and generative adversarial network (GAN, P2P as representative) were used to predict the full-dose images. The image visual scores, noise levels and quantitative parameters of tumor tissue were compared. There was high consistency in image quality scores among all groups [Kappa =0.719, 95% confidence interval (CI): 0.697-0.741, P<0.001]. There were 264 cases (3D Unet-15s), 311 cases (3D Unet-30s), 89 cases (P2P-15s) and 247 cases (P2P-30s) with image quality score ≥3, respectively. There was significant difference in the score composition among all groups (χ2=1,325.46, P<0.001). Both deep learning models reduced the standard deviation (SD) of background, and increased the signal-to-noise ratio (SNR). When 8%PET images were used as input, P2P and 3D Unet had similar enhancement effect on SNR of tumor lesions, but 3D Unet could significantly improve the contrast-noise ratio (CNR) (P<0.05). There was no significant difference in SUVmean of tumor lesions compared with s-PET group (P>0.05). When 17%PET image was used as input, SNR, CNR and SUVmax of tumor lesion of 3D Unet group had no statistical difference with those of s-PET group (P>0.05). Both GAN and CNN can suppress image noise to varying degrees and improve image quality. However, when 3D Unet reduces the noise of tumor lesions, it can improve the CNR of tumor lesions. Moreover, quantitative parameters of tumor tissue are similar to those under the standard acquisition protocol, which can meet the needs of clinical diagnosis.

18F-FDG PET and CT identifiers of high-risk lesions in the stomach and esophagus.

e16036 Background: Assessing the significance of incidentally found increased 18F-FDG uptake in the stomach and esophagus on PET/CT has long been a challenge. Currently, there is no clear guideline to assist clinicians with distinguishing malignant from benign uptake. This study aims to compare various PET and CT characteristics used separately and collectively, to identify high-risk foci of uptake. Methods: 18F-FDG PET/CT images from August 2018 to October 2022 were reviewed and patients who completed a follow up EGD due to incidentally found increased gastroesophageal uptake were included in this study. To identify high-risk foci, the following PET and CT characteristics were used: 1) uptake intensity, using lesion SUVmax relative to mediastinal blood pool and liver SUVmean values (≤ blood pool = 0, &gt; blood pool but &lt; liver = 1, ≥ liver = 2); 2) uptake pattern (diffuse = 0, segmental = 1, focal = 2); 3) eccentricity (circumferential= 0, eccentric = 1); and CT correlation score (normal = 0, thickening = 1, mass = 2). Cut-off values were determined using receiver operating characteristic (ROC) curves. Benign and malignant uptake were compared to histological findings using Pearson’s chi-square test. Results: Incidental uptake in the stomach and/or esophagus were noted in 473/7805 (6.1%) patients of which 89 (18.8%) had a follow up EGD and were included in this study. Uptake intensity did not differentiate benign and malignant as SUVmax was greater than background tissues in all cases (Score =2). Uptake pattern, eccentricity, and CT-correlation of PET were significantly different between benign and malignant foci ( p &lt; 0.001, p &lt; 0.001, and p &lt; 0.001, Chi-square). Using cut-off scores from ROC curves, the predictive value of different PET/CT characteristics in identifying high-risk foci was reviewed. Conclusions: PET eccentricity along with anatomic CT correlative findings, offer similar value in predicting high-risk uptake foci to uptake pattern, eccentricity, and CT correlation combined. These are both, however, superior to other PET/CT characteristics used alone or in combination. [Table: see text]

Inter-rater and intra-rater agreement of [99mTc]-labelled NM-01, a single-domain programmed death-ligand 1 (PD-L1) antibody, using quantitative SPECT/CT in non-small cell lung cancer

BackgroundImmune checkpoint inhibitors, including those against programmed cell death protein-1 (PD-1) or its ligand (PD-L1), are routinely used to treat non-small cell lung cancer (NSCLC). PD-L1 is a validated prognostic and predictive immunohistochemical biomarker of anti-PD-1/PD-L1 therapy but displays temporospatial heterogeneity of expression. Non-invasive radiopharmaceutical techniques, including technetium-99m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT, have the potential to improve the predictive value of PD-L1 assessment. This study aims to determine the inter- and intra-rater agreement of the quantitative measurement of [99mTc]NM-01 SPECT/CT in NSCLC.MethodsParticipants (n = 14) with untreated advanced NSCLC underwent [99mTc]NM-01 SPECT/CT at baseline (n = 3) or at baseline plus 9-week follow-up (n = 11). [99mTc]NM-01 uptake (of primary lung, lymph node, thoracic and distant metastases, and healthy reference tissues) was measured using SUVmax and malignant lesion-to-blood pool ratios with Siemens xSPECT Broad Quantification software by three independent raters. Intraclass correlation coefficients (ICC) were calculated and Bland–Altman plot analysis performed to determine inter- and intra-rater agreement.ResultsThere was excellent inter-rater agreement of manual freehand SUVmax scores of primary lung tumour (T; n = 25; ICC 1.00; 95% CI 0.99–1.00), individual lymph node metastases (LN; n = 56; ICC 0.97; 95% CI 0.95–0.98), thoracic metastases (ThMet; n = 9; ICC 0.94; 95% CI 0.83–0.99) and distant metastases (DisMet; n = 21; ICC 0.91; 95% CI 0.83–0.96). The inter-rater ICCs of tumour-to-blood pool (T:BP), LN:BP, ThMet:BP and DisMet:BP measures of [99mTc]NM-01 uptake also demonstrated good or excellent agreement. Manual freehand scoring of T, LN, ThMet, DisMet and their ratios using [99mTc]NM-01 SPECT/CT following a 28-day interval was consistent for all raters with good or excellent intra-rater agreement demonstrated (ICCs range 0.86–1.00).ConclusionQuantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC, using SUVmax of malignant primary or metastatic lesions and their ratios with healthy reference tissues, demonstrated good or excellent inter- and intra-rater agreement in this study. Further validation with ongoing and future larger cohort studies is now warranted.Clinical trial registrationClinicalTrials.gov identifier no. NCT04436406 (registered 18th June 2020; available at https://clinicaltrials.gov/ct2/show/NCT04436406) and NCT04992715 (registered 5th August 2021; available at https://clinicaltrials.gov/ct2/show/NCT04992715).

Head-to-Head Intra-Individual Comparison of Biodistribution and Tumor Uptake of [18F]FAPI-74 with [18F]FDG in Patients with PDAC: A Prospective Exploratory Study.

Radiolabeled fibroblast activation protein (FAP) ligands, a novel class of tracers for PET/CT imaging, have demonstrated very promising results in various oncological, as well as in some benign, diseases with long-term potential to supplant the current pan-cancer agent [18F]FDG in some cancer types. Pancreatic ductal carcinoma (PDAC) belongs to the group of epithelial malignancies with a strong so-called "desmoplastic reaction", leading to a prominent tumor stroma with cancer-associated fibroblasts that exhibit a marked overexpression of fibroblast activation protein (FAP). The first clinical experiences in PDAC with 68Ga-labeled FAP ligands suggested superior sensitivity to [18F]FDG. However, there is limited data with 18F-labeled FAP derivatives, i.e. [18F]FAPI-74, yet prospective single- and multicenter trials are already ongoing. In this proof-of-concept study, we sought to evaluate the biodistribution, tumor uptake, and lesion detectability in patients with PDAC using [18F]FAPI-74 PET/CT as compared to [18F]FDG PET/CT scans for staging. This study includes 7 patients (median age 69) who underwent both [18F]FDG PET/CT with contrast-enhancement and [18F]FAPI-74 PET with low-dose CT for primary staging (n = 3) and therapy response control after neoadjuvant (n = 1) or re-staging after palliative therapy (n = 3). The mean interval between PET scans was 11 ± 4 days (range 1-15 days). The [18F]FDG and [18F]FAPI-74 PET/CT scans were acquired at 64 ± 4.1 min (range 61-91 min) and 66.4 ± 6.3 min (range 60-76 min), respectively, after administration of 200 ± 94 MBq (range 79-318 MBq) and 235 ± 88 MBq (range 90-321 MBq), respectively. Quantification of tracer uptake was determined with SUVmax and SUVmean. Furthermore, the tumor-to-background ratio (TBR) was derived by dividing the SUVmax of tumor lesions by the SUVmax of adipose tissue, skeletal muscle, and blood pool. Overall, 32 lesions were detected in 7 patients including primary (n = 7), lung (n = 7), bone (n = 3), lymph node (n = 13), and peritoneal metastases (n = 2). [18F]FAPI-74 detected 22% more lesions compared with [18F]FDG with a better TBR and visual lesion delineation. In one patient the primary lesion could be detected unequivocally with [18F]FAPI-74 but was missed by [18F]FDG imaging. Altogether, most of the lesions demonstrated markedly elevated uptake of [18F]FAPI-74 with a simultaneous lower uptake in the background, providing a very high visual contrast. To the best of our knowledge, this is the first, prospective, intra-individual investigation comparing [18F]FAPI-74 with [18F]FDG imaging in PDAC with encouraging results. These pivotalresults supporta larger, multicentric, prospective study to determine the value of [18F]FAPI-74 in detecting and staging PDAC in comparison with current standard of care imaging.

Relationship between SUVmax on 18F-FDG PET and PD-L1 expression in hepatocellular carcinoma.

Our study was to investigate the correlation between 18F-FDG uptake in HCC and tumor PD-L1 expression in HCC, and assess the value of 18F-FDG PET/CT imaging for predicting PD-L1 expression in HCC. A total of 102 patients with confirmed HCC were included in this retrospective study. The PD-L1 expression and immune cell infiltrating of tumors were determined through immunohistochemistry staining. The SUVmax of HCC lesions were assessed using 18F-FDG PET/CT. The correlation between PD-L1 expression and the clinicopathological were evaluated by the Cox proportional hazards model and the Kaplan-Meier survival analysis. The SUVmax of HCC primary tumors was higher in patients with poorly differentiated HCC, large tumor size, portal vein tumor thrombus, lymph node and distant metastases, and death. The SUVmax of HCC are correlated with the PD-L1 expression and the number of cytotoxic T cells and M2 macrophage infiltration. PD-L1 expression was significantly correlated with tumor SUVmax, tumor differentiation, tumor size, portal vein tumor thrombosis, and patient survival status and infiltrating M2 macrophages. Further, our results confirmed that SUVmax, portal vein tumor thrombosis, and the number of infiltrating M2 macrophages were closely related to PD-L1 expression and were independent risk factors by multivariate analysis. The combined assessment of SUVmax values and the presence of portal vein tumor thrombosis by 18F-FDG PET/CT imaging can help determine PD-L1 expression in HCC. FDG uptake in HCC was positively correlated with the PD-L1 expression and the number of cytotoxic T cells and M2 macrophage infiltration. The combined use of SUVmax and portal vein tumor thrombosis by PET/CT imaging assess the PD-L1 expression better in HCC. These findings also provide a basis for clinical studies to assess the immune status of tumors by PET/CT.