Change In SUVmax Research Articles

Pre-operative dual-time-point [18F]FET PET differentiates CDKN2A/B loss and PIK3CA mutation status in adult-type diffuse glioma: a single-center prospective study.

While [18F]FET PET plays a complementary role in glioma imaging, it needs to be more comprehensively understood for improved characterization of glioma prior to surgery given the evolving landscape of molecular neuropathology. Thus, we investigated the utility of pre-operative dual-time-point [18F]FET PET in correlation with next-generation sequencing (NGS) data in patients with adult-type diffuse glioma (ADG). Adult patients who were suspected to have primary glioma were prospectively recruited between June 2021 and January 2024. They underwent pre-operative dual-time-point static PET/CT at 20min (early) and 80min (delay) after [18F]FET injection. Semi-quantitative parameters of the hottest lesion (SUVmax) of tumour and the hottest lesion-to-normal brain ratio (TBRmax) were assessed from each summed image. Furthermore, the percentage changes (△) of SUVmax and TBRmax between two images were calculated. Histopathology of glioma was determined according to the 2021 WHO classification and NGS data. This study investigated a dozen genes in 76 patients, of whom 51 had isocitrate dehydrogenase (IDH)-wild-type glioblastoma, 13 had IDH-mutant astrocytoma, and 12 had IDH-mutant oligodendroglioma. Every tumour was [18F]FET-avid having TBRmax more than 1.6. Patients with CDKN2A/B loss had significantly higher values of SUVmax (5.7 ± 1.6 vs. 4.7 ± 1.3, p = 0.004; 5.0 ± 1.4 vs. 4.4 ± 1.2, p = 0.026) and TBRmax (6.5 ± 1.8 vs. 5.1 ± 1.7, p = 0.001; 5.3 ± 1.5 vs. 4.3 ± 1.3, p = 0.004) in both scans than patients without CDKN2A/B loss, even after adjustment for age, MRI enhancement, tumor grade and type of pathology. Furthermore, patients with PIK3CA mutation (16.2 ± 11.8 vs. 6.7 ± 11.6, p = 0.007) had significantly higher △SUVmax than patients without PIK3CA mutation, even after adjustment for age, MRI enhancement, tumor grade, and type of pathology. Among the dozen genes investigated in this prospective study in patients with ADG, we found out that CDKN2A/B loss and PIK3CA mutation status could be differentiated by pre-operative dual-time-point [18F]FET PET/CT.

18F]AlF-NOTA-FAPI-04 PET/CT for Predicting Pathologic Response of Resectable Esophageal Squamous Cell Carcinoma to Neoadjuvant Camrelizumab and Chemotherapy: A Phase II Clinical Trial.

This single-center, single-arm, phase II trial (ChiCTR2100050057) investigated the ability of 18F-labeled fibroblast activation protein inhibitor ([18F]AlF-NOTA-FAPI-04, denoted as 18F-FAPI) PET/CT to predict the response to neoadjuvant camrelizumab plus chemotherapy (nCC) in locally advanced esophageal squamous cell carcinoma (LA-ESCC). Methods: This study included 32 newly diagnosed LA-ESCC participants who underwent 18F-FAPI PET/CT at baseline, of whom 23 also underwent scanning after 2 cycles of nCC. The participants underwent surgery after 2 cycles of nCC. Recorded PET parameters included maximum, peak, and mean SUVs and tumor-to-background ratios (TBRs), metabolic tumor volume, and total lesion FAP expression. PET parameters were compared between patient groups with good and poor pathologic responses, and the predictive performance for treatment response was analyzed. Results: The good and poor response groups each included 16 participants (16/32, 50.0%). On 18F-FAPI PET/CT, the posttreatment SUVs were significantly lower in good responders than in poor responders, whereas the changes in SUVs with treatment were significantly higher (all P < 0.05). SUVmax (area under the curve [AUC], 0.87; P = 0.0026), SUVpeak (AUC, 0.89; P = 0.0017), SUVmean (AUC, 0.88; P = 0.0021), TBRmax (AUC, 0.86; P = 0.0031), and TBRmean (AUC, 0.88; P = 0.0021) after nCC were significant predictors of pathologic response to nCC, with sensitivities of 63.64%-81.82% and specificities of 83.33%-100%. Changes in SUVmax (AUC, 0.81; P = 0.0116), SUVpeak (AUC, 0.82; P = 0.0097), SUVmean (AUC, 0.81; P = 0.0116), and TBRmean (AUC, 0.74; P = 0.0489) also were significant predictors of the pathologic response to nCC, with sensitivities and specificities in similar ranges. Conclusion: 18F-FAPI PET/CT parameters after treatment and their changes from baseline can predict the pathologic response to nCC in LA-ESCC participants.

Prediction of biochemical recurrence after radical prostatectomy from primary tumour characteristics.

To construct and externally calibrate a predictive model for early biochemical recurrence (BCR) after radical prostatectomy (RP) incorporating clinical and modern imaging characteristics of the primary tumour. Patients who underwent RP following multiparametric magnetic resonance imaging, prostate biopsy and prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT), from two centres in Australia and the Netherlands. The primary outcome was biochemical recurrence-free survival (BRFS), where BCR was defined as a rising PSA level of ≥0.2 ng/mL or initiation of postoperative treatment per clinician discretion. Proportional hazards models to predict time to event were developed in the Australian sample using relevant pre- and post-surgical parameters and primary tumour maximum standardised uptake value (SUVmax) on diagnostic PSMA-PET/CT. Calibration was assessed in an external dataset from the Netherlands with the same inclusion criteria. Data from 846 patients were used to develop the models. Tumour SUVmax was associated with worse predicted 3-year BRFS for both pre- and post-surgical models. SUVmax change from 4 to 16 lessened the predicted 3-year BRFS from 66% to 42% for a patient aged 65 years with typical pre-surgical parameters (PSA level 8 ng/mL, Prostate Imaging-Reporting and Data System score 4/5 and biopsy Gleason score ≥4 + 5). Considering post-surgical variables, a patient with the same age and PSA level but pathological stage pT3a, RP Gleason score ≥4 + 5 and negative margins, SUVmax change from 4 to 16 lessened the predicted 3-year BRFS from 76% to 61%. Calibration on an external sample (n = 464) showed reasonable performance; however, a tendency to overestimate survival in patients with good prognostic factors was observed. Tumour SUVmax on diagnostic PSMA-PET/CT has utility additional to commonly recognised variables for prediction of BRFS after RP.

PSMA-PET/CT response after metastasis-directed radiotherapy of bone oligometastases in prostate cancer

ObjectiveBone metastases are very common in advanced prostate cancer and can sensitively be detected utilizing PSMA-PET/CT. Therefore, our goal was to evaluate the suitability of PSMA-PET/CT-guided metastasis-directed external beam radiotherapy (MDT) as treatment option for patients with biochemical recurrence and oligometastatic bone lesions.Materials & methodsWe retrospectively examined 32 prostate cancer patients with biochemical recurrence and PSMA-positive oligometastatic disease limited to the bone (n = 1–3). A total of 49 bone lesions were treated with MDT. All patients received a post-radiotherapy PSMA-PET/CT-Scan. Changes in SUVmax, PSMA-positive tumor volume per lesion and PSA, as well as the correlation between the PET/CT-interval and SUVmax response were calculated.ResultsMDT lead to a SUVmax decrease in 46/49 (94%) of the lesions. The median relative decline of SUVmax was 60.4%, respectively. Based on PSMA-positive lesion volume with a SUV cut-off of 4, 46/49 (94%) of lesions showed complete response, two (4%) partial response and one lesion (2%) was stable on PSMA-PET/CT after MDT. Most of the treated patients (56.3%) showed an initial PSA decline at three months and a PSA nadir of median 0.14 ng/ml after a median time of 3.6 months after MDT. The median relative PSA change at three months after MDT was 3.9%.ConclusionMDT is a very effective treatment modality for prostate cancer bone oligometastases and lesion response to MDT can be assessed using the (semi-)quantitative parameters SUVmax and PSMA-positive lesion volume with established SUV cut-offs.

Meta-analysis of [18F]FDG-PET/CT in pulmonary sarcoidosis.

18F-Fluorodeoxyglucose (FDG) PET/CT is emerging as a tool in the diagnosis and evaluation of pulmonary sarcoidosis, however, there is limited consensus regarding its diagnostic performance and prognostic value. A meta-analysis was conducted with PubMed, Science Direct, MEDLINE, Scopus, and CENTRAL databases searched up to and including September 2023. 1355 studies were screened, with seventeen (n = 708 patients) suitable based on their assessment of the diagnostic performance or prognostic value of FDG-PET/CT. Study quality was assessed using the QUADAS-2 tool. Forest plots of pooled sensitivity and specificity were generated to assess diagnostic performance. Pooled changes in SUVmax were correlated with changes in pulmonary function tests (PFT). FDG-PET/CT in diagnosing suspected pulmonary sarcoidosis (six studies, n = 400) had a pooled sensitivity of 0.971 (95%CI 0.909-1.000, p = < 0.001) and specificity of 0.873 (95%CI 0.845-0.920)(one study, n = 169). Eleven studies for prognostic analysis (n = 308) indicated a pooled reduction in pulmonary SUVmax of 4.538 (95%CI 5.653-3.453, p = < 0.001) post-treatment. PFTs displayed improvement post-treatment with a percentage increase in predicted forced vital capacity (FVC) and diffusion capacity of the lung for carbon monoxide (DLCO) of 7.346% (95%CI 2.257-12.436, p = 0.005) and 3.464% (95%CI -0.205-7.132, p = 0.064), respectively. Reduction in SUVmax correlated significantly with FVC (r = 0.644, p < 0.001) and DLCO (r = 0.582, p < 0.001) improvement. In cases of suspected pulmonary sarcoidosis, FDG-PET/CT demonstrated good diagnostic performance and correlated with functional health scores. FDG-PET/CT may help to guide immunosuppression in cases of complex sarcoidosis or where treatment rationalisation is needed. FDG-PET/CT has demonstrated a high diagnostic performance in the evaluation of suspected pulmonary sarcoidosis with radiologically assessed disease activity correlating strongly with clinically derived pulmonary function tests. In diagnosing pulmonary sarcoidosis, FDG-PET/CT had a sensitivity and specificity of 0.971 and 0.873, respectively. Disease activity, as determined by SUVmax, reduced following treatment in all the included studies. Reduction in SUVmax correlated with an improvement in functional vital capacity, Diffusion Capacity of the Lungs for Carbon Monoxide, and subjective health scoring systems.

Narrow interval dual phase 18F-FDG PET/CT: A practical approach for distinguishing tumor recurrence from radiation necrosis in brain metastasis.

Purpose of our research is to demonstrate efficacy of narrow interval dual phase [18F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging in distinguishing tumor recurrence (TR) from radiation necrosis (RN) in patients treated for brain metastases. 35 consecutive patients (22 female, 13 male) with various cancer subtypes, lesion size > 1.0 cm3, and suspected recurrence on brain magnetic resonance imaging (MRI) underwent narrow interval dual phase FDG-PET/CT (30 and 90 min after tracer injection). Clinical outcome was determined via sequential MRIs or pathology reports. Maximum standard uptake value (SUVmax) of lesion (L), gray matter (GM), and white matter (WM) was measured on early (1) and delayed (2) imaging. Analyzed variables include % change, late phase, and early phase for L uptake, L/GM uptake, and L/WM uptake. Statistical analysis (P < .01), receiver operator characteristic (ROC) curve and area under curve (AUC) cutoff values were obtained. Change in L/GM ratio of > -2% was 95% sensitive, 91% specific, and 93% accurate (P < .001, AUC = 0.99) in distinguishing TR from RN. Change in SUVmax of lesion alone was the second-best indicator (P < .001, AUC = 0.94) with an ROC cutoff > 30.5% yielding 86% sensitivity, 83% specificity, and 84% accuracy. Other variables (L alone or L/GM ratios in early or late phase, all L/WM ratios) were significantly less accurate. Utilizing narrow interval dual phase FDG-PET/CT in patients with brain metastasis treated with radiation therapy provides a practical approach to distinguish TR from RN. Narrow time interval allows for better patient comfort, greater efficiency of PET/CT scanner, and lower disruption of workflow.

Predictive significance of intraprostatic volumetric parameters derived from early and standard time 68Ga-PSMA PET/CT images in newly diagnosed prostate cancer patients.

To investigate the relationship between intraprostatic 68Ga-prostate-specific membrane antigen (PSMA) uptake values and volumetric parameters derived from early pelvic and standard-time whole-body 68Ga-PSMA PET/computed tomography (CT) images in untreated prostate cancer (PCa) patients, and to assess the predictive significance of these data in relation to disease prognosis, comparing them with the Gleason score, clinical risk classification and the presence of metastatic disease detected in 68Ga-PSMA PET/CT imaging. Eighty-one newly diagnosed PCa patients underwent early phase pelvic imaging at the 5th minute and standard time whole-body imaging at the 60th minute. Various threshold values were used in intraprostatic delineations to compute maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), intraprostatic PSMA tumor volume and intraprostatic total lesion PSMA uptake. Correlations between early and standard time measurements, as well as changes in SUV parameters over time, were examined. The association of these values with Gleason score, clinical risk status (National Comprehensive Cancer Network), and metastatic disease was explored. SUVmax measurements from both early and standard time images distinguished all three groups (clinical risk scores, Gleason score and metastatic group), with standard imaging demonstrating statistical superiority in receiver operating characteristic analyses. Strong correlations were observed between early and standard-time PET parameters. Changes in intraprostatic SUVmax and SUVmean values over time did not exhibit predictive value. Although intraprostatic PSMA PET parameters generally aligned at both early and standard times, parameters obtained from standard time images showed more robust correlations with clinical risk scores, Gleason score and metastasis status in newly diagnosed, untreated PCa patients.

Same-day post-therapy imaging with a new generation whole-body digital SPECT/CT in assessing treatment response to [177Lu]Lu-PSMA-617 in metastatic castration-resistant prostate cancer.

Lutetium-177 [177Lu]Lu-PSMA-617 radioligand therapy (RLT) represents a significant advancement for metastatic castration-resistant prostate cancer (mCRPC), demonstrating improvements in radiographic progression free survival (rPFS) and overall survival (OS) with a low rate of associated side effects. Currently, most post-therapy SPECT/CT is conducted at 24h after infusion. This study examines the clinical utility of a next-generation multi-detector Cadmium-Zinc-Telluride (CZT) SPECT/CT system (StarGuide) in same-day post-infusion assessment and early treatment response to [177Lu]Lu-PSMA-617. In this retrospective study, 68 men with progressive mCRPC treated with [177Lu]Lu-PSMA-617 at our center from June 2022 to June 2023 were evaluated. Digital whole-body SPECT/CT imaging was performed after [177Lu]Lu-PSMA-617infusion (mean ± SD: 1.8 ± 0.6h, range 1.1-4.9h). Quantitative analysis of [177Lu]Lu-PSMA-617 positive lesions was performed in patients who underwent at least 2 post-therapy SPECT/CT, using liver parenchyma uptake as reference. Metrics including [177Lu]Lu-PSMA-617 positive total tumor volume (Lu-TTV), SUVmax and SUVmean were calculated. These quantitative metrics on post-infusion SPECT/CT images after cycles 1, 2 and 3 were correlated with overall survival (OS), prostate specific antigen-progression free survival (PSA-PFS) as defined by prostate cancer working group 3 (PCWG3), and PSA decrease over 50% (PSA50) response rates. 56 patients (means age 76.2 ± 8.1 years, range: 60-93) who underwent at least 2 post-therapy SPECT/CT were included in the image analysis. The whole-body SPECT/CT scans (~ 12min per scan) were well tolerated, with 221 same-day scans performed (89%). At a median of 10-months follow-up, 33 (58.9%) patients achieved PSA50 after [177Lu]Lu-PSMA-617 treatment and median PSA-PFS was 5.0 months (range: 1.0-15 months) while median OS was not reached. Quantitative analysis of SPECT/CT images showed that 37 patients (66%) had > 30% reduction in Lu-TTV, associated with significantly improved overall survival (median not reached vs. 6 months, P = 0.008) and PSA-PFS (median 6 months vs. 1 months, P < 0.001). However, changes in SUVmax or SUVmean did not correlate with PSA-PFS or OS. We successfully implemented same-day post-therapy SPECT/CT after [177Lu]Lu-PSMA-617 infusions. Quantitation of 1-2h post-therapy SPECT/CT images is a promising method for assessing treatment response. However, the approach is currently limited by its suboptimal detection of small tumor lesions and the necessity of incorporating a third-cycle SPECT/CT to mitigate the effects of any potential treatment-related flare-up. Further investigation in a larger patient cohort and prospective validation is essential to confirm these findings and to explore the role of SPECT/CT as a potential adjunct to PSMA PET/CT in managing mCRPC.

Prostate-Specific Membrane Antigen PET Response Associates with Metastasis-Free Survival After Stereotactic Ablative Radiation in Oligometastatic Prostate Cancer

PurposeEmerging data suggest metastasis-directed therapy (MDT) improves outcomes in patients with oligometastatic castration-sensitive prostate cancer (omCSPC). Prostate-specific membrane antigen positron emission tomography (PSMA-PET) can detect occult metastatic disease and has been proposed as a biomarker for treatment response. Herein we identify and validate a PSMA-PET biomarker for metastasis-free survival (MFS) following MDT in omCSPC. Methods and materialsWe performed an international multi-institutional retrospective study of patients with omCSPC, defined as ≤3 lesions, treated with metastasis-directed stereotactic ablative radiation therapy who underwent PSMA-PET/CT prior to and after (median 6.2 months, range 2.4-10.9 months) treatment. Pre- and post-MDT PSMA-PET/CT SUVmax was measured for all lesions and PSMA response was defined as percent change in SUVmax of the least responsive lesion. PSMA response was evaluated as both a continuous variable and dichotomized as PSMA responders with a complete/partial response (at least 30% reduction in SUVmax) and PSMA non-responders with stable/progressive disease (less than a 30% reduction in SUVmax). PSMA response was correlated conventional imaging defined metastasis-free survival (MFS) with Kaplan-Meier and cox regression. ResultsA total of 131 patients with 261 treated metastases were included in the analysis, with median follow-up of 29 months (IQR 18.5-41.3). Following SABR, 70.2% of patients were classified as PSMA responders. Multivariable analysis demonstrated PSMA response as a continuous variable was associated with significantly worse MFS (HR=1.003, 95%CI 1.001-1.006; p=0.016). Patients classified as PSMA responders were found to have significantly improved median MFS of 39.9 vs 12 months (p=0.001) compared to PSMA non-responders. Our study is limited as it is a retrospective review of a heterogenous population. ConclusionsFollowing SABR, PSMA-PET response appears to be a radiographic biomarker that correlates with MFS in omCSPC. This approach holds promise for guiding clinical management of omCSPC and should be validated in a prospective setting.

Role of serial 18F-fludeoxyglucose positron emission tomography in determining the therapeutic efficacy of immunosuppression and clinical outcome in patients with cardiac sarcoidosis

BackgroundMyocardial inflammation and perfusion defects detected by 18F-fludeoxyglucose (FDG) and Rubidium-82 positron emission tomography (PET) may be associated with ventricular arrhythmias (VAs) in cardiac sarcoidosis (CS). The role of serial quantitative PET in determining the effect of treatment on myocardial inflammation and clinical outcomes is yet to be defined. MethodsNewly diagnosed CS patients with active myocardial inflammation (maximum standardised uptake value (SUVmax) ≥ 2.5) were treated with immunosuppression, then underwent repeat FDG-PET, Rubidium-82, and echocardiographic imaging 6–12 months later. Serial changes in SUVmax, SUVmean, inflammatory extent, perfusion defect (PD) extent, metabolism/perfusion mismatch extent, global cardiac metabolic activity, and left ventricular ejection fraction (LVEF) were assessed. The primary endpoint was a composite of all-cause mortality, serious VA and heart-failure (HF) hospitalisation. Event data were recorded from the date of the second FDG-PET. ResultsThe study population consisted of 113 patients (66% male, age: 55 ± 11 years, LVEF: 54 ± 13%). SUVmax reduced from 4.5 (interquartile range: 3.3–7.1) to 2.7 (2.2–3.6). Overall, 94 (83%) patients saw serial reduction in SUVmax, with 42 (37%) demonstrating complete response (SUVmax <2.5).Following a median of 46 (25–57) months, 28 (25%) patients reached the endpoint (8 deaths, 17 VAs, and 3 HF hospitalisations). PD extent (Hazard ratio 1.03, 95% confidence interval: 1.01–1.05; p = 0.035) was a significant predictor of outcome following treatment, even after accounting for LVEF and change in SUVmean. The risk of adverse events was the greatest in those with a pre-treatment or post-treatment PD extent of >10%. ConclusionIn our cohort with active CS, following a treatment-induced reduction in myocardial inflammation, PD extent was the main predictor of adverse events.

18F-FDG Dedicated Breast PET Complementary to Breast MRI for Evaluating Early Response to Neoadjuvant Chemotherapy.

Purpose To compare quantitative measures of tumor metabolism and perfusion using fluorine 18 (18F) fluorodeoxyglucose (FDG) dedicated breast PET (dbPET) and breast dynamic contrast-enhanced (DCE) MRI during early treatment with neoadjuvant chemotherapy (NAC). Materials and Methods Prospectively collected DCE MRI and 18F-FDG dbPET examinations were analyzed at baseline (T0) and after 3 weeks (T1) of NAC in 20 participants with 22 invasive breast cancers. FDG dbPET-derived standardized uptake value (SUV), metabolic tumor volume, and total lesion glycolysis (TLG) and MRI-derived percent enhancement (PE), signal enhancement ratio (SER), and functional tumor volume (FTV) were calculated at both time points. Differences between FDG dbPET and MRI parameters were evaluated after stratifying by receptor status, Ki-67 index, and residual cancer burden. Parameters were compared using Wilcoxon signed rank and Mann-Whitney U tests. Results High Ki-67 tumors had higher baseline SUVmean (difference, 5.1; P = .01) and SUVpeak (difference, 5.5; P = .04). At T1, decreases were observed in FDG dbPET measures (pseudo-median difference T0 minus T1 value [95% CI]) of SUVmax (-6.2 [-10.2, -2.6]; P < .001), SUVmean (-2.6 [-4.9, -1.3]; P < .001), SUVpeak (-4.2 [-6.9, -2.3]; P < .001), and TLG (-29.1 mL3 [-71.4, -6.8]; P = .005) and MRI measures of SERpeak (-1.0 [-1.3, -0.2]; P = .02) and FTV (-11.6 mL3 [-22.2, -1.7]; P = .009). Relative to nonresponsive tumors, responsive tumors showed a difference (95% CI) in percent change in SUVmax of -34.3% (-55.9%, 1.5%; P = .06) and in PEpeak of -42.4% (95% CI: -110.5%, 8.5%; P = .08). Conclusion 18F-FDG dbPET was sensitive to early changes during NAC and provided complementary information to DCE MRI that may be useful for treatment response evaluation. Keywords: Breast, PET, Dynamic Contrast-enhanced MRI Clinical trial registration no. NCT01042379 Supplemental material is available for this article. © RSNA, 2024.

The efficacy of short acquisition time using 18F-FDG total-body PET/CT for the identification of pediatric epileptic foci

Background18F-FDG positron emission tomography (PET) plays a crucial part in the evaluation for pediatric epileptic patients prior to therapy. Short-term scanning holds significant importance, especially for pediatrics epileptic individuals who exhibited involuntary movements. The aim was to evaluate the effects of short acquisition time on image quality and lesion detectability in pediatric epileptic patients using total-body (TB) PET/CT. A total of 25 pediatric patients who underwent TB PET/CT using uEXPLORER scanner with an 18F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Short acquisition times (60 s, 150 and 300 s) were simulated by truncating PET data in list mode to reduce count density. Subjective image quality was scored on a 5-point scale. Regions of interest analysis of suspected epileptogenic zones (EZs), corresponding locations contralateral to EZs, and healthy cerebellar cortex were used to compare the semi-quantitative uptake indices of short-time images and then were compared with 600 s images. The comparison of EZs detectability based on time-dependent PET images was performed.ResultsOur study demonstrated that a short acquisition time of 150 s is sufficient to maintain subjective image quality and lesion significance. Statistical analysis revealed no significant difference in subjective PET image quality between imaging at 300 s and 150 s (P > 0.05). The overall impression scores of image quality and lesion conspicuity in G60s were both greater than 3 (overall quality, 3.21 ± 0.46; lesion conspicuity, 4.08 ± 0.74). As acquisition time decreased, the changes of SUVmax and SD in the cerebellar cortex gradually increased (P < 0.01). There was no significant difference in asymmetry index (AI) difference between the groups and the AIs of EZs were > 15% in all groups. In 26 EZs of 25 patients, the lesion detection rate was still 100% when the time was reduced to 60 s.ConclusionsThis study proposed that TB PET/CT acquisition time could be reduced to 60 s with acceptable lesion detectability. Furthermore, it was suggested that a 150 s acquisition time would be sufficient to achieve diagnostic performance and image quality for children with epilepsy.

Prognostic significance of 18F-Fluorodeoxyglucose positron-emission tomography parameters in patients with biliary tract cancers: a meta-analysis.

Numerous previous studies have assessed the prognostic role of 18F-fluorodeoxyglucose positron-emission tomography (18F FDG PET) in patients with biliary tract cancer (BTC), but those results were inconsistent. The present study aims to determine the predictive value of 18F FDG PET in BTC patients via a meta-analysis. The underlying studies related to 18F FDG PET and BTC patients` outcomes were searched and identified in the online databases. The interested parameters include total lesion glycolysis (TLG), metabolic tumor volume (MTV), primary tumor and metastatic lymph node (LN) maximum standardized uptake value (SUVmax), as well as change of SUVmax (ΔSUVmax) during treatment. Overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS) were considered as the primary endpoints. Hazard ratio (HR) and corresponding 95% confidence intervals (CIs) were defined as the effective measure and calculated by a pooled analysis. Publication bias was assessed by funnel plot, Bagg's and Egger's tests. Totally, 23 studies involving 1478 patients were included in the present meta-analysis. After a pooled analysis, it revealed that a high SUVmax was significantly associated with a poor OS (HR:2.07, 95%CI: 1.74-2.46, P = 0.000) and DFS (HR: 2.28, 95%CI: 1.53-3.41, P = 0.000). In addition, an increased TLG level contributed to a shorter OS (HR:1.91, 95%CI: 1.26-2.90, P = 0.002) and DFS (HR: 4.34, 95%CI: 1.42-13.27, P = 0.01). Moreover, we confirmed that an elevated MTV was significantly associated with increased mortality (HR:2.04, 95%CI:1.26-3.31, P = 0.004) and disease relapse (HR: 3.88, 95%CI:1.25-12.09, P = 0.019) risks. Besides, the present study uncovered that increased ΔSUVmax could predict poor OS (HR:1.26, 95%CI:1.06-1.50, P = 0.008) instead of PFS (HR: 1.96, 95%CI: 0.82-4.72, P = 0.280). Lastly, we found that LN SUVmax did not link to OS (HR: 1.49, 95%CI: 0.83-2.68, P = 0.178). No obvious publication bias was detected in the present study. 18F FDG PET parameters, including SUVmax, TLG, MTV, and ΔSUVmax, could be applied as convenient and reliable factors for predicting BTC patients` outcomes.

Early response monitoring during [177Lu]Lu-PSMA I&T therapy with quantitated SPECT/CT predicts overall survival of mCRPC patients: subgroup analysis of a Swiss-wide prospective registry study

PurposeTo assess early tumor response with quantitated SPECT/CT and to correlate it with clinical outcome in metastatic castration–resistant prostate cancer (mCRPC) patients treated with 177Lutetium-PSMA I&T therapy.MethodsSingle-center, observational study, part of the prospective Swiss national cancer registry study investigating the safety and efficacy of [177Lu]Lu-PSMA I&T (EKNZ: 2021–01271) in mCRPC patients treated with at least two cycles of [177Lu]Lu-PSMA I&T 6-weekly. After the first and second cycle quantitated SPECT/CT (Symbia Intevo, Siemens) was acquired 48 h after injection (three fields of view from head to thigh, 5 s/frame) and reconstructed using xQuant® (48i, 1 s, 10-mm Gauss). Image analysis: The PSMA-positive total tumor volumes (TTV) were semi-automatically delineated using a SUV threshold of 3 with MIMencore® (version 7.1.3, Medical Image Merge Software Inc.). Changes in TTV, highest tumor SUVmax, and total tumor SUVmean between cycles 1 and 2 were calculated and grouped into a) stable or decrease and b) increase. Serum PSA levels were assessed at each therapy cycle and at follow-up until progression or death. Changes in TTV, PSA, SUVmax, and SUVmean were correlated with PSA-progression-free survival (PSA-PFS) and the overall survival (OS) using the Kaplan–Meier methodology (log-rank test).ResultsBetween 07/2020 and 04/2022, 111 patients were screened and 73 finally included in the data analysis. The median follow-up was 8.9 months (range 1.4–26.6 months). Stable or decreased TTV at cycle 2 was associated with longer OS (hazard ratio (HR) 0.28, 95% confidence interval (CI) 0.09–0.86, p < 0.01). Similar, stable, or decreased PSA was associated with longer OS (HR 0.21; CI 0.07–0.62, p < 0.01) and PSA-PFS (HR 0.34; 95% CI 0.16–0.72, p < 0.01). Combining TTV and PSA will result in an augmented prognostic value for OS (HR 0.09; CI 0.01–0.63; p < 0.01) and for PSA-PFS (HR 0.11; CI 0.02–0.68; p < 0.01). A reduction of SUVmax or SUVmean was not prognostically relevant, neither for OS (p 0.88 and 0.7) nor for PSA-PFS (p 0.73 and 0.62, respectively).ConclusionSix weeks after initiating [177Lu]Lu-PSMA I&T, TTV and serum PSA appear to be good prognosticators for OS. Combined together, TTV + PSA change demonstrates augmented prognostic value and can better predict PSA-PFS. Larger studies using TTV change prospectively as an early-response biomarker are warranted for implementing management change towards a more personalized clinical practice.

Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study.

Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3months of MTX therapy correlate with response to treatment. We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship betweenchanges in the SUVmax andMTXPG(n) concentrations. We included 42 sarcoidosis patients treated with MTX (15mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax. These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

Predictive value of Dmax and %ΔSUVmax of 18F-FDG PET/CT for the prognosis of patients with diffuse large B-cell lymphoma

PurposeTo investigate the prognosis value of a combined model based on 18F-fluoro-deoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) baseline and interim parameters in patients with diffuse large B-cell lymphoma (DLBCL).MethodsWe retrospectively analyzed the PET metabolic parameters and clinical data of 154 DLBCL patients between December 2015 and October 2020. All of these patients underwent 18F-FDG PET/CT scan before treatment and after three or four courses of chemotherapy. The optimal cut-off values for quantitative variables were determined by the receiver operating characteristic (ROC) curve. The baseline and interim PET/CT parameters, which respectively included maximum standardized uptake value (SUVmax0), total metabolic tumor volume (TMTV0), standardized total metabolic tumor volume (STMTV0), and the distance between the two furthest lesions (Dmax) and total tumor lesion glycolysis (TTLG1), SUVmax1, TMTV1, and the rate of change of SUVmax (%ΔSUVmax), and clinical characteristics were analyzed by chi-squared test, Kaplan-Meier survival curve, and Cox regression analysis.ResultsOf 154 patients, 35 exhibited disease progression or recurrence. ROC analysis revealed that baseline 18F-FDG PET/CT metabolic parameters, including maximum standardized uptake value (SUVmax0), total metabolic tumor volume (TMTV0), standardized total metabolic tumor volume (STMTV0), and the distance between the two furthest lesions (Dmax), along with interim 18F-FDG PET/CT metabolic parameters such as total tumor lesion glycolysis (TTLG1), SUVmax1, TMTV1, and the rate of change of SUVmax (%ΔSUVmax), were predictive of relapse or progression in DLBCL patients (P < 0.05). The chi-squared test showed that TMTV0, STMTV0, Dmax, SUVmax1, TMTV1, TTLG1, %ΔSUVmax, Deauville score, IPI, Ann Arbor stage, and LDH were associated with patient prognosis (P < 0.05). Multivariate Cox regression analysis showed that Dmax (P = 0.021) and %ΔSUVmax (P = 0.030) were independent predictors of prognosis in DLBCL patients. There were statistically significant differences in PFS among the three groups with high, intermediate, and low risk according to the combination model (P < 0.001). The combination model presented higher predictive efficacy than single indicators.ConclusionThe combined model of baseline parameter Dmax and intermediate parameter %ΔSUVmax of 18F-FDG PET/CT improved the predictive efficacy of PFS and contributed to the risk stratification of patients, providing a reference for clinical individualization and precision treatment.

The prognostic value of F18 Fluorothymidine positron emission tomography for assessing the response of malignant pleural mesothelioma to chemotherapy - A prospective cohort study.

Malignant pleural mesothelioma is difficult to prognosticate. F18-Fluorodeoxyglucose positron emission tomography (FDG PET) shows promise for response assessment but is confounded by talc pleurodesis. F18-Fluorothymidine (FLT) PET is an alternative tracer specific for proliferation. We compared the prognostic value of FDG and FLT PET and determined the influence of talc pleurodesis on these parameters. Overall, 29 prospectively recruited patients had FLT PET, FDG PET and CT-scans performed prior to and post one chemotherapy cycle; 10 had prior talc pleurodesis. Patients were followed for overall survival. CT response was assessed using mRECIST. Radiomic features were extracted using the MiM software platform. Changes in maximum SUV (SUVmax), mean SUV (SUVmean), FDG total lesion glycolysis (TLG), FLT total lesion proliferation (TLP) and metabolic tumour volume (MTV) after one chemotherapy cycle. Cox univariate analysis demonstrated FDG PET radiomics were confounded by talc pleurodesis, and that percentage change in FLT MTV was predictive of overall survival. Cox multivariate analysis showed a 10% increase in FLT tumour volume corresponded with 9.5% worsened odds for overall survival (P = 0.028, HR = 1.095, 95% CI [1.010, 1.187]). No other variables were significant on multivariate analysis. This is the first prospective study showing the statistical significance of FLT PET tumour volumes for measuring mesothelioma treatment response. FLT may be better than FDG for monitoring mesothelioma treatment response, which could help optimise mesothelioma treatment regimes.

18F]NaF PET/CT imaging of response to single fraction SABR to bone metastases from breast cancer.

Breast cancer commonly metastasises to the skeleton, and stereotactic ablative body radiation therapy (SABR) is an emerging treatment for oligometastatic disease. Accurately imaging bone metastases and their response to treatment is challenging. [18F]NaF-PET has a higher sensitivity and specificity than conventional bone scans for detecting breast cancer bone metastases. In this pre-defined secondary analysis of a prospective trial, we evaluated the change in [18F]NaF uptake after SABR. Patients with oligometastatic breast cancer received a single fraction of 20 Gy to up to three bone metastases. [18F]NaF-PET was acquired before and 12 months after SABR. Pre- and post-treatment [18F]NaF-PET images were registered to the treatment planning CT. The relative change in tumour SUVmax and SUVmean was quantified. The intersection of each of the radiation therapy isodose contours with a non-tumour bone was created. The change in SUVmean in sub-volumes of non-tumour bone receiving doses of 0-20 Gy was quantified. In total, 14 patients, with 17 bone metastases, were available for analysis. A total of 15 metastases exhibited a reduction in SUVmax; the median reduction was 42% and the maximum reduction 82%. An increased absolute reduction in SUVmax was observed with higher pre-treatment SUVmax. One patient exhibited increased SUVmax after treatment, which was attributed to normal peri-tumoural bone regeneration in the context of a bone metastasis. There was a median reduction of 15%-34% for non-tumour bone in each dose level.

Correlation of Post-Treatment Biopsy and Fluorodeoxyglucose PET/CT Findings Following Definitive Chemotherapy and Radiation for Cervical Cancer

Concurrent chemotherapy and external beam radiation with brachytherapy boost is considered standard of care for treatment of locally advanced cervical cancer. Post treatment surveillance fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) imaging is recommended 3-6 months after completion of therapy. Persistent FDG avidity is commonly observed at the cervix on surveillance scans, indeterminate for residual malignancy versus post treatment inflammatory change. To better understand the clinical significance of residual hypermetabolic activity, we performed an analysis of surveillance FDG-PET/CT images, correlating findings with post treatment cervical biopsy results after completion of therapy. The medical records of all patients treated with definitive chemotherapy and radiation for locally advanced (FIGO IB3 to IVA) cervical cancer at a single academic medical center between 2017 and 2022 were reviewed. Patients were treated with curative intent using a combination of pelvic external beam radiation with concurrent cisplatin chemotherapy followed by intracavitary or combined intracavitary/interstitial brachytherapy boost. Patients underwent FDG-PET/CT imaging at 3-6 months upon completion of therapy, followed by biopsy either for suspected residual disease or equivocal findings on physical exam or FDG-PET/CT scans. Biopsies were obtained within 100 days of FDG-PET/CT imaging (median, 14 days). Twenty-three patients met inclusion criteria. One patient was excluded from analysis due to lack of FDG avidity on her pre-treatment FDG-PET/CT. Among the 22 evaluable scans, median pre-treatment FDG- PET/CT SUVmax of the cervix was 16.3 (range, 4.9-55). Median post-treatment SUVmax was 4.4 (range, 2.1-7.4). Median change in SUVmax from pre-treatment to post-treatment was 11.8 (range, 1.1 to 50.6). Twenty patients had a post-treatment SUVmax of greater than 3. Among post treatment scans, eight showed no residual uptake; two showed uptakes equal to the liver; eleven showed uptakes moderately higher than liver; and one showed uptake markedly increased relative to liver. None of the biopsy specimens showed evidence of residual malignancy, instead showing fibroinflammatory necrosis and reactive changes. None of the patients developed clinical evidence of disease progression at the cervix within one year of treatment completion. Residual hypermetabolic activity at the cervix is common following definitive chemotherapy and radiation for cervical cancer. This is unlikely to represent residual viable malignancy. Post treatment FDG-PET/CT imaging remains valuable for detecting locoregional or distant disease progression/persistence following therapy.

Automatic Prediction of Metastasis-Free Survival (MFS) Using Prostate-Specific Membrane Antigen (PSMA) PET for Oligometastatic Castration-Sensitive Prostate Cancer (omCSPC)

Recent data have shown the promise of metastasis-directed therapy (MDT) to improve outcomes in omCSPC patients. Response biomarkers are still needed to identify patients at an early time point who will not respond to the treatment. We have shown that PSMA PET-CT SUVmax changes over time may be a useful response biomarker that correlates with MFS, an important endpoint in these omCSPC patients. This study investigated radiomic imaging biomarkers derived from PSMA-PET acquired pre- and post-MDT for MFS prediction, which may provide better features to discriminate response in the future to improve the outcome of these patients. We accrued an international multi-institutional cohort of omCSPC patients treated with stereotactic ablative radiation therapy (SABR) MDT. The cohort includes 32 patients from Institution 1 (USA) and 38 patients from Institution 2 (Europe). Both pre- and 6-month post-treatment PSMA-PET/CT were acquired. Combat was used for data harmonization in the image domain to minimize imaging variations across institutions. We defined the GTV volume as zone 1 and a 3-5 mm expansion ring area outside the GTV as zone 2 for radiomics analysis. 874 radiomics features (214 original and 660 wavelet filtered features) were extracted from both zones using open-source software and used together for MFS prediction. Function Chi2 was used to select the most significant five features. Several machine learning models (Random Forest, Logistic regression, Support Vector Machine, Naïve Bayesian) were implemented to predict MFS. The models were tested using both a leave-one-out strategy and cross-validation across the two institutions. In the leave-one-out biomarker using 70 patients, random forest achieved the best accuracy, with MFS predicted correctly for 56 (80% of 70) patients. The five radiomic features identified based on their ability to predict MFS included Entropy, Skewness, and Compactness from zone 1, Skewness, and Mesh volume from zone 2. In the cross-institution tests, random forest predicted MFS correctly for 24 (75% of 32) patients when being trained using 38 Institution 2 patients and validated against 32 Institution 1 patients. Vice versa, the model predicted MFS correctly for 28 (74% of 38) patients when being trained using Institution 1 patients and validation using Institution 2 patients. The five features identified for prediction included Entropy and Skewness from both zones and Flatness from zone 1. Our study demonstrated the promise of using pre- and post-MDT PSMA-PET-based imaging radiomic biomarkers for MFS prediction for omCSPC patients. Imaging biomarkers predictive of MFS were identified in both GTV and the ring area outside GTV. Over 74% prediction accuracy was achieved in the cross-institution validation test. The model provides a valuable tool for prognosis prediction early following MDT, which opens up a unique opportunity for monitoring or treatment interventions for patients identified with poor prognoses to improve outcomes.