Agreement between PSMA-RADS and E-PSMA systems in classifying [18F]PSMA-1007 PET/CT lesions among prostate cancer patients: exploring the correlation between lesion size and uptake.

Purpose: To determine the agreement between the PSMA-RADS and E-PSMA standardized reporting systems in the classification of [18F]PSMA-1007-uptaking lesions identified on PET/CT scan in patients with prostate cancer (PCa) and post-prostatectomy with suspected recurrent disease (local recurrence, regional nodal involvement and distant metastases), based on biochemical recurrence, while also exploring the correlation between lesion size and tracer uptake. Materials and methods: A retrospective cross-sectional study of 32 post-prostatectomy PCa patients who had suspected recurrent disease based on biochemical recurrence post-prostatectomy (prostate-specific antigen values that are 0.2 ng/mL or higher) underwent [18F]PSMA-1007 PET/CT scan. The recurrent disease PCa lesions were characterized and subsequently classified using two standardized reporting systems (PSMA-RADS and E-PSMA). The lesions were grouped based on anatomical site, their size and SUVmax were compared using Kruskal-Wallis test with Dunn-Bonferroni post hoc tests. Spearman correlation coefficients were calculated between the size of the lesions and their SUVmax of the radiotracer [18F]PSMA-1007 for all the lesions and when grouped by anatomical site. Additionally, the agreement between lesion classifications was assessed using Cohen's kappa index. Results: Only 32 (69.98 ± 8.27, men) patients met the inclusion criteria, a total of 149 lesions with avid uptake of [18F]PSMA-1007 were identified. Positive correlation (r = 0.516, p < 0.001) was observed between the size of the metastatic prostate cancer lymph node lesions and their [18F]PSMA-1007 uptake. Substantial agreement was noted between the PSMA-RADS and E-PSMA classification system scores among all lesions (κ = 0.70, p < 0.001), with notable discrepancies primarily among lymph node lesions. Conclusion: Our findings revealed a positive correlation between the size of the metastatic prostate cancer lymph node lesions and [18F]PSMA-1007 uptake, and although there was substantial agreement between the PSMA-RADS and E-PSMA classification systems, there were discrepancies mainly among the lymph node lesions.

Differences on metabolic behavior between intra and extrahepatic cholangiocarcinomas at 18F-FDG-PET/CT: prognostic implication of metabolic parameters and tumor markers.

BACKGROUND AND PURPOSE: Cholangiocarcinoma is an infrequent neoplasm barely studied with 18F-FDG-PET/CT. We evaluated the metabolic behavior of cholangiocarcinoma in PET/CT according to its location (intra or extrahepatic) and analyzed the relationship between metabolic parameters of the primary tumor and tumor markers (CA19-9 and CEA), determining their prognostic significance. METHODS: Retrospective study of PET/CT of 60 patients with untreated cholangiocarcinoma, divided into two groups according to tumor location. FDG uptake was evaluated visually and semiquantitatively [SUVmax and tumor-to-liver ratio (TLR)], and differences between intra and extrahepatic cholangiocarcinomas were tested, both for FDG uptake in the primary tumor and for the presence of regional or distant disease (per-patient), as well as regarding tumor marker levels. A correlation between metabolic parameters and tumor markers was performed, and prognostic value of these factors was determined (univariate and multivariate analyses). RESULTS: Intrahepatic cholangiocarcinomas were significantly more FDG-avid than extrahepatic ones (p = 0.006 for SUVmax; p = 0.002 for TLR). There were differences neither between both groups considering the capacity of PET/CT to detect regional (p = 0.261) and distant involvement (p = 0.876), nor regarding the levels of tumor markers (p = 0.160 for CA19-9; p = 0.708 for CEA). Metabolic parameters and tumor markers showed a weak positive correlation (R2 0.22-0.27). At the multivariate analysis, advanced stage (p = 0.024), increased CEA (p = 0.022), and higher TLR (p = 0.003) were significantly related with shorter overall survival. CONCLUSIONS: Intra and extrahepatic cholangiocarcinomas behave differently on PET/CT, though no differences between both groups exist in its capacity to detect regional or distant disease. Metabolic parameters and levels of tumor markers seem to relate with tumor burden, impacting in prognosis.

Effect of PET/CT standardized uptake values on complete response to treatment before definitive chemoradiotherapy in stage III non-small cell lung cancer.

PURPOSE: The standard treatment for patients with stage III non-small cell lung cancer (NSCLC), unsuitable for resection and with good performance, is definitive radiotherapy with cisplatin-based chemotherapy. Our aim is to evaluate the effect of the maximum value of standardized uptake values (SUVmax) of the primary tumor in positron emission tomography-computed tomography (PET/CT) before treatment on complete response (CR) and overall survival. METHODS: The data of 73 stage III NSCLC patients treated with concurrent definitive chemoradiotherapy (CRT) between 2008 and 2017 and had PET/CT staging in the pretreatment period were evaluated. ROC curve analysis was performed to determine the ideal cut-off value of pretreatment SUVmax to predict CR. RESULTS: Median age was 58 years (range 27-83 years) and 66 patients were male (90.4%). Median follow-up time was 18 months (range 3-98 months); median survival was 23 months. 1-year overall survival (OS) rate and 5-year OS rate were 72 and 19%, respectively. Median progression-free survival (PFS) was 9 months; 1-year PFS rate and 5-year PFS rate were 38 and 19%, respectively. The ideal cut-off value of pretreatment SUVmax that predicted the complete response of CRT was 12 in the ROC analysis [AUC 0.699 (0.550-0.833)/P < 0.01] with a sensitivity of 83%, and specificity of 55%. In patients with SUVmax < 12, CR rate was 60%, while, in patients with SUV ≥ 12, it was only 19% (P = 0.002). Median OS was 26 months in patients with pretreatment SUVmax < 12, and 21 months in patients with SUVmax ≥ 12 (HR = 2.93; 95% CI 17.24-28.75; P = 0.087). CR rate of the whole patient population was 26%, and it was the only factor that showed a significant benefit on survival in both univariate and multivariate analyses. CONCLUSION: Pretreatment SUVmax of the primary tumor in PET/CT may predict CR in stage III NSCLC patients who were treated with definitive CRT. Having clinical CR is the only positive predictive factor for prolonged survival.

Hounsfield unit value has null effect on thyroid nodules at 18F-FDG PET/CT scans

ABSTRACT Objectives: Detection rate of thyroid nodules is increasing with the use of new imaging modalities, especially in screening for malignancies. Positron emission tomography/computed tomography (PET/ CT)-positive thyroid nodules should be differentiated for malignancy to avoid unnecessary operations and further follow-up. Most trials evaluate the role of SUVmax, but there is no definitive information about the utility of Hounsfield unit (HU) values for prediction of malignancy. This study aimed to evaluate the HU values beside SUVmax for detecting malignancy risk of PET/CT-positive thyroid nodules. Subjects and methods: Results of 98 cancer patients who had fine needle aspiration biopsy (FNAB) for thyroid nodules detected on PET/CT between January 2011 and December 2015 were assessed. The FNABs and surgical pathological results were recorded. Results: FNABs revealed benign results in 32 patients (32.7%), malignant in 18 (18.4%), non-diagnostic in 20 (20.4%), and indeterminate in 28 (28.5%). Twenty-four patients underwent thyroidectomy. The mean HU values were not significantly different in benign and malignant nodules (p = 0.73). However, the mean SUVmax was significantly higher (p < 0.001) in malignant ones. Area under curve (AUC) was 0.824 for SUVmax; the cut-off value was over 5.55 (p < 0.001), with 80% sensitivity, 84.5% specificity. Conclusions: Our current study demonstrated that HU value does not add any additional valuable information for discriminating between malignant and benign thyroid nodules. We also defined a SUV cut-off value of 5.55 for malignant potential of thyroid nodules detected on PET/CT Arch Endocrinol Metab. 2018;62(4):460-5

Reproducibility of standardized uptake values of same-day randomized 68Ga-PSMA-11 PET/CT and PET/MR scans in recurrent prostate cancer patients.

OBJECTIVE: Positron emission tomography in association with magnetic resonance imaging (PET/MR) and 68Ga-PSMA-11 has shown superior detection in recurrent prostate cancer patients as compared to PET/computed tomography (PET/CT). There are, however, several technological differences between PET/CT and PET/MR systems which affect the PET image quality. The objective of this study was to assess the reproducibility of PET/CT and PET/MR SUV's in recurrent prostate cancer patients. We randomized the patients regarding the order of the PET/CT and PET/MR scans to reduce the influence of tracer uptake as a function of time. METHODS: Thirty patients, all with biochemical recurrence after radical prostatectomy, underwent whole-body PET/CT and PET/MR scans after intravenous injection of a single dose of 68Ga-PSMA-11. Fifteen patients underwent PET/CT first and 15 patients underwent PET/MR first. Volumes of interest on tumor lesions were outlined and maximum standardized uptake value (SUVmax) corrected for lean body mass was calculated. Correlation and agreement between scans were assessed by generalized linear mixed-effects models and Bland-Altman analysis. The association between SUV, patient characteristics and imaging parameters was assessed. RESULTS: Eighteen of the 30 evaluated patients had at least one positive lesion, giving an overall detection rate of 60%. In total, there were 34 visible lesions: 5 local recurrences, 22 lymph node metastases and 7 bone metastases. One group acquired PET/CT and PET/MR at median time points of 63.0 and 159.0 min, while the other group acquired PET/MR and PET/CT at median time points of 92.0 and 149.0 min. SUVmax between scans was linearly correlated, described by the equation Y(PET/CT SUVmax) = 0.75 + 1.00 × (PET/MR SUVmax), on average 20% higher on PET/CT than on PET/MR. SUV associated significantly only with type of lesion, scan time post-injection and acquisition time per bed position. CONCLUSIONS: SUVmax from PET/CT and PET/MR are linearly correlated, on average 20% higher on PET/CT than on PET/MR and should, therefore, not be used interchangeably in patient follow-up.

Metabolic and molecular relative percentage coreduction in patients with locally advanced rectal cancer treated with neoadjuvant therapy.

PURPOSE: Vascular endothelial growth factor receptor-2 (VEGFR-2), epidermal growth factor receptor-1 (EGFR) and cyclooxygenase-2 (COX-2) stimulate key processes involved in tumour progression and are important targets for cancer therapeutics. (18)F-FDG maximum standardized uptake value (SUVmax) on PET/CT is a marker of tumour metabolic activity. The purpose of this study was to measure percentage reductions in SUVmax (∆SUVmax%), VEGFR-2 (∆VEGFR-2%), EGFR (∆EGFR%) and COX-2 (∆COX-2%) in patients with locally advanced rectal cancer (LARC) after preoperative treatment, and to correlate the changes in these markers of response with pathological response in terms of tumour regression grade (TRG) using Rödel's scale and long-term clinical outcome. METHODS: VEGFR-2, EGFR and COX-2 were measured using a quantitative and qualitative compound immunohistochemistry analysis (immunoreactive score) of the pretreatment endoscopic biopsy and definitive surgical specimens. Composite indexes using ∆SUVmax% and the three molecules were developed to differentiate patients with metabolic and molecular responses from nonresponders. Cox proportional hazards model was used to explore associations between the tumour markers, disease-free survival (DFS) and overall survival (OS). RESULTS: The analysis included 38 patients with a median follow-up of 86 months (range 5 - 113 months). The ∆VEGFR-2%/∆SUVmax% index correctly identified 13 of 19 pathological responders (TRG 3 and 4) and 17 of 19 nonresponders (TRG 0 - 2) (sensitivity 68 %, specificity 89 %, accuracy 79 %, positive predictive value 87 %, negative predictive value 74 %). In multivariate analysis, only the ∆VEGFR-2%/∆SUVmax% index was associated with DFS (HR 0.11, p = 0.001) and OS (HR 0.15, p = 0.02). CONCLUSION: In patients with LARC the ∆VEGFR-2%/∆SUVmax% response index is associated with outcome. Determination of the optimal diagnostic cut-off level for this novel biomarker association should be explored. Evaluation in a clinical trial is required to determine whether selected patients could benefit from treatment with a VEGFR-targeted therapeutic agent.

PET-CT: tumores de cabeza y cuello. Ensayo pictórico y revisión de la literatura / PET-CT: Head and Neck Tumors. Picture essay and literature review

La PET-CT como modalidad diagnóstica es muy útil en la evaluación anatomofisiológica de la cabeza y el cuello. Proporciona una alta sensibilidad y especificidad en la estadificación de neoplasias primarias, la respuesta al tratamiento médico o quirúrgico y la detección de recurrencias. Dichas enfermedades representan un alto impacto sobre la mortalidad y morbilidad de los pacientes. El principal objetivo de esta publicación es hacer una revisión de los hallazgos en la PET-CT de los tumores más frecuentes de cabeza y cuello, con énfasis en los procesos malignos, estudiados en nuestra institución.

PET-CT as a diagnostic modality which is very useful in the anatomical-physiological assessment of the head and neck. It provides high sensitivity and specificity in the staging of primary tumors, the response to medical or surgical treatment and the detection of recurrences. These diseases represent a high impact on the mortality and morbidity in our patients. Our main objective is to review the findings on PET-CT of the most common head and neck tumors with an emphasis on malignancy which are studied in our institution.