Clinical predictors of negative/equivocal SPECT imaging outcomes in primary hyperparathyroidism: Factors calling for 18F-choline-PET.

PURPOSE: For minimally invasive surgery of parathyroid adenomas, exact localization diagnostics are essential. Main imaging modalities used for diagnostics are sonography, SPECT with/without CT (traditional imaging) and 18F-choline-PET. The aim of our study was to identify predictors for inconclusive SPECT imaging and subsequently determine in which cases 18F-choline-PET is needed. METHODS: Retrospective analysis of 138 patients with histologically confirmed primary hyperparathyroidism (pHPT). After sonography, patients underwent SPECT or SPECT/CT imaging, with subsequent 18F-choline-PET in cases of disconcordant results. Logistic regression analysis was used to identify clinical and laboratory factors predictive for negative SPECT results. RESULTS: Sensitivity rates for sonography, SPECT, SPECT/CT, and choline-PET were 47 %, 49 %, 71.7 %, and 97 %, respectively. Logistic regression revealed lower PTH levels (p < 0.001), presence of structural thyroid disease (p = 0.018), and negative sonography (p < 0.001) as predictive of negative/equivocal SPECT outcome. An additional traditional imaging CT scan to a SPECT enhanced detection odds, as did greater adenoma weight. Urolithiasis, osteoporosis, and calcium values as measurement of activity and duration of disease showed no significant association with the detection rate. Furthermore, our study demonstrated that 18F-choline-PET exhibited remarkable sensitivity in detecting adenomas among patients with negative/equivocal SPECT results. CONCLUSION: Our study reveals potential predictive factors for a negative/equivocal SPECT outcome in pHPT. Identifying these factors might allow minimizing futile SPECT examinations and perhaps encourage timely utilization of 18F-choline-PET imaging. Our study reinforces the clinical significance of 18F-choline-PET, especially in complex cases with disconcordant results by conventional parathyroid imaging methods.

Additional value of integrated 18F-choline PET/4D contrast-enhanced CT in the localization of hyperfunctioning parathyroid glands and correlation with molecular profile.

PURPOSE: The localization of hyperfunctioning parathyroid gland(s) (HPTG) in patients with primary hyperparathyroidism (PHPT) with negative or inconclusive first-line imaging is a significant challenge. This study aimed to evaluate the role of integrated 18F-choline PET/4D contrast-enhanced computed tomography (4DCeCT) in these patients, compare its detection rate and sensitivity with those of 18F-choline PET/CT and (4DCeCT), and analyse the association between choline metabolism and morphological, biochemical and molecular parameters of HPTG. METHODS: We prospectively enrolled 44 PHPT patients with negative or inconclusive first-line imaging. 18F-Choline PET/CT and 4DCeCT were performed at the same time, and integrated 18F-choline PET/4DCeCT images were obtained after coregistration. Experienced physicians examined the images. The SUVratio and degree of contrast enhancement were recorded for each positive finding. Histopathology, laboratory and multidisciplinary follow-up were used as the standard of reference. Both the detection rates and sensitivities of the three imaging modalities were calculated retrospectively. Immunohistochemistry was performed to evaluate the molecular profile of HPTGs. RESULTS: 18F-Choline PET/4DCeCT was positive in 32 of 44 patients with PHPT (detection rate 72.7%), and 31 of 31 surgically treated patients (sensitivity 100%). These results were significantly (p < 0.05) better than those of 18F-choline PET/CT (56.8% and 80%, respectively) and those of 4DCeCT (54.5 and 74%, respectively). A significant correlation between SUV and calcium level was found. In a multivariate analysis, only calcium level was significantly associated with 18F-choline PET/4DCeCT findings. SUVratio and Ki67 expression were significantly correlated. CONCLUSION: Integrated 18F-choline PET/4DCeCT should be considered as an effective tool to detect PHPT in patients with negative or inconclusive first-line imaging. Choline metabolism is correlated with both calcium level and Ki67 expression in HPTG.

PETC/CT with 18F-Choline localizes hyperfunctioning parathyroid adenomas equally well in normocalcemic hyperparathyroidism as in overt hyperparathyroidism.

PURPOSE: Identification of pathologic parathyroid glands in primary hyperparathyroidism, traditionally based on neck ultrasound (US) and/or 99mTc-Sestamibi scintigraphy, can be challenging. PET/CT with 18F-Fluorocholine (18F-FCH) might improve the detection of pathologic parathyroid glands. We aimed at comparing the diagnostic performance of 18F-FCH-PET/CT with that of dual-phase dual-isotope parathyroid scintigraphy and neck US. METHODS: Thirty-four consecutive patients with primary hyperparathyroidism were prospectively enrolled, 7 had normocalcemic hyperparathyroidism, and 27 had classic hypercalcemic hyperparathyroidism. All patients underwent high-resolution neck US, dual-phase dual-isotope 99mTc-Pertechnetate/99mTc-Sestamibi scintigraphy, and 18F-FCH-PET/CT. RESULTS: In the whole patients' group, the detection rates of the abnormal parathyroid gland were 68% for neck US, 71% for 18F-FCH-PET/CT, and only 15% for 99mTc-Sestamibi scintigraphy. The corresponding figures in normocalcemic and hypercalcemic hyperparathyroidism were 57 and 70% for neck US, 70 and 71% for 18F-FCH-PET/CT, and 0 and 18% for 99mTc-Sestamibi scintigraphy, respectively. In the 17 patients in whom the abnormal parathyroid gland was identified, either at surgery or at fine needle aspiration cytology/biochemistry, the correct detection rate was 82% for neck US, 89% for 18F-FCH-PET/CT, and only 17% for 99mTc-Sestamibi scintigraphy. CONCLUSIONS: 18F-FCH-PET/CT can be considered a first-line imaging technique for the identification of pathologic parathyroid glands in patients with normocalcemic and hypercalcemic hyperparathyroidism, even when the parathyroid volume is small.

Fortuitous discovery of non-fluorocholine-fixing papillary carcinoma of vesicular variant of the thyroid.

PURPOSE: Characterization of thyroid nodules is crucial to propose surgical intervention for histological verification. Cervical ultrasound potentially combined with fine needle aspiration is recommended, and fluorocholine positron emission tomography (FCH-PET), commonly used in prostatic cancers, has been evaluated in the diagnosis of thyroid cancers in recent publications. METHODS: We present two cases of patients with multinodular thyroid and primary hyperparathyroidism. The preoperative assessment consisted of an ultrasound, a MIBI scintigraphy and an FCH-PET in favor of a parathyroid adenoma. RESULTS: The imaging examinations pointed to a diagnosis of a parathyroid adenoma. In both cases, papillary thyroid carcinoma, missed by FCH-PET, was discovered incidentally at a distance from the parathyroid adenoma during the surgical procedure. CONCLUSIONS: These are the first descriptions of thyroid papillary carcinoma without preoperative FCH-PET identification. These clinical cases are contrary to recent publications showing a benefit of this examination in the diagnosis of thyroid cancers.

Intensity-modulated radiotherapy of prostate cancer with simultaneous integrated boost after molecular imaging with 18F-choline-PET/CT : Clinical results and quality of life.

PURPOSE: To analyze clinical results and quality of life of patients with localized prostate cancer after irradiation of the prostate with an 18F-choline-PET/CT-based simultaneous integrated boost (SIB) in comparison to a control group without SIB. METHODS: A total of 134 patients underwent intensity-modulated radiotherapy from 2007-2010. All patients received a total dose of 76 Gy with 2 Gy fractions to the prostate; 67 patients received an additional SIB of 80 Gy. The median follow-up was 65 months. Quality of life was evaluated with the EPIC (Expanded Prostate Cancer Index Composite) questionnaire. RESULTS: Baseline characteristics were similar in both groups (prostate-specific antigen 11 ng/ml vs. 8 ng/ml, p = 0.20, Gleason score <6 in 36% vs. 46%, p = 0.22, with vs. without SIB). No prostate cancer-related death was observed. No significant difference of quality of life scores was found. The largest difference after 5-6 years in comparison to baseline was reported for sexual bother (mean 15 vs. 17 points with vs. without SIB). Mean urinary scores did not decrease. Bowel bother scores changes were larger in the SIB group (mean 5 vs. 2 points, dependent on SIB volume), with increased bowel problems (15 vs. 2% big/moderate problem with bowel movements, p = 0.03). However, a trend towards higher efficacy with SIB resulted (biochemical recurrence-free survival of 92% vs. 85%, p = 0.17). CONCLUSIONS: The first long-term analysis of patients treated with SIB based on molecular imaging with 18-F-choline-PET/CT showed an excellent biochemical recurrence-free survival, but a larger percentage of bowel problems in comparison to the control group.

Serial 18F-choline-PET imaging in patients receiving enzalutamide for metastatic castration-resistant prostate cancer: response assessment and imaging biomarkers.

AIM: High rate of non-target lesions in metastatic castration-resistant prostate cancer usually limits applicability of Response Evaluation Criteria in Solid Tumors (RECIST) criteria, and this has led to a growing interest in using PET/computed tomography (CT). We prospectively investigated the role of (18)F-choline (FCH)-PET/CT in patients receiving enzalutamide after docetaxel. PATIENTS & METHODS: 30 patients were monitored by means of FCH-PET/CT before and during the treatment. A Cox proportional hazards regression model was used to assess the associations between metabolic parameters and clinical outcomes. RESULTS: Univariate analysis showed no significant correlation between biochemical and FCH-PET responses. Multivariate analysis showed that only baseline maximum standardized uptake value (SUVmax) significantly correlated with biochemical progression-free survival, radiological progression-free survival and overall survival. CONCLUSION: Our findings suggest that FCH-PET/CT may play a role in defining prognosis of patients receiving enzalutamide because baseline SUVmax proved to be an independent prognostic factor.

Prostate Cancer Imaging with Novel PET Tracers.

Molecular imaging of prostate cancer is in a dynamic phase of development. Currently approved techniques are limited and researchers have been working on novel agents to improve accuracy in targeting and detecting prostate tumors. In addition, the complexity of various prostate cancer states also contributes to the challenges in evaluating suitable radiotracer candidates. We have highlighted nuclear medicine tracers that focus on mechanisms involved in bone metastasis, prostate cancer cell membrane synthesis, amino acid analogs, androgen analogs, and the prostate specific membrane antigen. Encouraging results with many of these innovative radiotracer compounds will not only advance diagnostic capabilities for prostate cancer but open opportunities for theranostic applications to treat this worldwide malignancy.

Prognostic value of metabolic parameters and clinical impact of ¹8F-fluorocholine PET/CT in biochemical recurrent prostate cancer.

PURPOSE: To evaluate the therapeutic impact of (18)F-fluorocholine (FCH) PET/CT in biochemical recurrent prostate cancer (PC) and to investigate the value of quantitative FCH PET/CT parameters in predicting progression-free survival (PFS). METHODS: This retrospective study included 172 consecutive patients with PC who underwent FCH PET/CT for biochemical recurrence. Mean rising PSA was 10.7 ± 35.0 ng/ml. Patients with positive FCH PET were classified into three groups: those with uptake only in the prostatic bed, those with locoregional disease, and those with distant metastases. Referring physicians were asked to indicate the hypothetical therapeutic strategy with and without the FCH PET/CT results. Clinical variables and PET parameters including SUVmax, SUVpeak, SUVmean, total lesion choline kinase activity (TLCKA) and standardized added metabolic activity (SAM) were recorded and a multivariate analysis was performed to determine the factors independently predicting PFS. RESULTS: In 137 of the 172 patients, the FCH PET/CT scan was positive, and of these, 29.9 % (41/137) had prostatic recurrence, 42.3 % (58/137) had pelvic lymph node recurrence with or without prostatic recurrence, and 27.7 % (38/137) had distant metastases. The FCH PET/CT result led to a change in treatment plan in 43.6 % (75/172) of the 172 patients. Treatment was changed in 49.6 % (68/137) of those with a positive FCH PET/CT scan and in 20 % (7/35) of those with a negative FCH PET/CT scan. After a median follow-up of 29.3 months (95 % CI 18.9 - 45.9 months), according to multivariate analysis age <70 years, SAM ≥23 and SUVmean ≥3 were parameters independently predicting PFS. A nomogram constructed using the three parameters showed 49 months of PFS in patients with the best scores (0 or 1) and only 11 months in patients with a poor score (score 3). CONCLUSION: This study indicates that a positive FCH PET result in PC patients with biochemical recurrence predicts a shorter PFS and confirms the major impact of the FCH PET result on the management of biochemical recurrent PC.

The ability of 18F-choline PET/CT to identify local recurrence of prostate cancer.

PURPOSE: To determine when 18F-choline PET/CT can truly identify local recurrence of prostate cancer. METHODS: 1031 patients from 3 European centers underwent (18)F-choline PET/CT (FCH PET/CT) for recurrent disease; 131 subjects (12.7%) showed a positive FCH uptake in the prostatic gland or prostatic fossa. Median age was 72 years (range 48-87 years), and the median PSA level at the time of FCH PET/CT scan was 4.41 ng/mL (0.22-18.13 ng/mL). 45 patients (34.4%) had a Gleason score (GS) >7, and the residual subjects had a GS ≤ 7. The assessment of true or false-positive FCH PET/CT findings was made by magnetic resonance imaging (n = 34) and/or biopsy in 75/131 cases. A χ (2) test and a Z Kolmogorov-Smirnov test were used to assess the correlation between clinical variables (age, PSA, GS, type of therapy) and FCH PET/CT findings. RESULTS: FCH PET/CT resulted truly positive (TP) for recurrent disease in the prostatic gland/fossa in 59/75 patients (79%) and falsely positive (FP) in 16 subjects (21%). The median value of PSA at the time of FCH PET/CT scan was higher in TP as compared to FP, although not statistically significant (4.76 vs. 3.04 ng/mL p > 0.05). Similarly, median age, GS categories, and the type of therapy were similar between the two groups (p > 0.05). However, when matching GS categories and PSA values, we found that the number of patients with TP findings were higher in the case of a PSA > 2 ng/mL, independently from the GS (ranging between 74% and 92%). Conversely, FP rate ranged between 50% and 65% in patients with a PSA ≤ 2 ng/mL, especially in the case of GS ≤ 7, whereas FP was around 25% in those with a GS >7 and PSA > 2 ng/mL. CONCLUSIONS: FCH PET/CT has a limited role in evaluation of prostatic gland/fossa recurrence, due to the physiological biodistribution of the radiopharmaceutical agent. However, in 70-90% of patients with a PSA >2 ng/mL, independently from GS, a focal FCH uptake is compatible with a true local recurrence.

Update on positron emission tomography for imaging of prostate cancer.

Prostate cancer is the most common non-cutaneous malignancy among men in the Western world, and continues to be a major health problem. Imaging has recently become more important in the clinical management of prostate cancer patients, including diagnosis, staging, choice of optimal treatment strategy, treatment follow up and restaging. Positron emission tomography, a functional and molecular imaging technique, has opened a new field in clinical oncological imaging. The most common positron emission tomography radiotracer, 18F-fluorodeoxyglucose, has been limited in imaging of prostate cancer. Recently, however, other positron emission tomography tracers, such as 11C-acetate and 11C- or (18) F-choline, have shown promising results. In the present review article, we overview the potential and current use of positron emission tomography or positron emission tomography/computed tomography imaging employing the four most commonly used positron emission tomography radiotracers, 18F-fluorodeoxyglucose, 11C-acetate and 11C- or 18F-choline, for imaging evaluation of prostate cancer.

ML Models Built Using Clinical Parameters and Radiomic Features Extracted from 18F-Choline PET/CT for the Prediction of Biochemical Recurrence after Metastasis-Directed Therapy in Patients with Oligometastatic Prostate Cancer.

Oligometastatic patients at [18F]F-Fluorocholine (18F-choline) PET/CT may be treated with metastasis-directed therapy (MDT). The aim of this study was to combine radiomic parameters extracted from 18F-choline PET/CT and clinical data to build machine learning (ML) models able to predict MDT efficacy. METHODS: Oligorecurrent patients (≤5 lesions) at 18F-choline PET/CT and treated with MDT were collected. A per-patient and per-lesion analysis was performed, using 2-year biochemical recurrence (BCR) after MDT as the standard of reference. Clinical parameters and radiomic features (RFts) extracted from 18F-choline PET/CT were used for training five ML Models for both CT and PET images. The performance metrics were calculated (i.e., Area Under the Curve-AUC; Classification Accuracy-CA). RESULTS: A total of 46 metastases were selected and segmented in 29 patients. BCR after MDT occurred in 20 (69%) patients after 2 years of follow-up. In total, 73 and 33 robust RFTs were selected from CT and PET datasets, respectively. PET ML Models showed better performances than CT Models for discriminating BCR after MDT, with Stochastic Gradient Descent (SGD) being the best model (AUC = 0.95; CA = 0.90). CONCLUSION: ML Models built using clinical parameters and CT and PET RFts extracted via 18F-choline PET/CT can accurately predict BCR after MDT in oligorecurrent PCa patients. If validated externally, ML Models could improve the selection of oligorecurrent PCa patients for treatment with MDT.

Update in imaging tests used for the localization of parathyroid pathology.

Preoperative localization of parathyroid pathology, generally a parathyroid adenoma, can be difficult in some cases due to the anatomical variants that these glands present. The objective of this review is to analyse the different imaging techniques used for preoperative localization of parathyroid pathology (scintigraphy, ultrasound, CT, MRI and PET). There is great variability between the different tests for the preoperative localization of parathyroid pathology. The importance of knowing the different diagnostic options lies in the need to choose the most suitable test at each moment and for each patient for an adequate management of primary hyperparathyroidism (PHP) with surgical criteria.

Influence of key histological characteristics on 18F-fluorodeoxyglucose /18F-choline positron emission tomography positivity in hepatocellular carcinoma: A machine learning study.

Purpose: To determine the characteristics influence of key histological on 18F-fluorodeoxyglucose (18F-FDG) and 18F-choline positron emission tomography (PET) positivity in hepatocellular carcinoma (HCC). Materials and methods: The 18F-FDG/18F-choline PET imaging findings of 103 histologically proven HCCs (from 62 patients, of which 47 underwent hepatectomy and 15 received liver transplantation) were retrospectively examined to assess the following key histological parameters: Grade, capsule, microvascular invasion (mVI), macrovascular invasion (MVI), and necrosis. Using a ratio of 70/30 for training and testing sets, respectively, a penalized classification model (Elastic Net) was trained using 100 repeated cross-validation procedures (10-fold cross-validation for hyperparameter optimization). The contribution of each histological parameter to the PET positivity was determined using the Shapley Additive Explanations method. Receiver operating characteristic curves with and without dimensionality reduction were finally estimated and compared. Results: Among the five key histological characteristics of HCC (Grade, capsule, mVI, MVI, and necrosis), mVI and tumor Grade (I-III) showed the highest relevance and robustness in explaining HCC uptake of 18F-FDG and 18F-choline. MVI and necrosis status both showed high instability in outcome predictions. Tumor capsule had a minimal influence on the model predictions. On retaining only mVI and Grades I-III for the final analysis, the area under the receiver operating characteristic (ROC) curve values were maintained (0.68 vs. 0.63, 0.65 vs. 0.64, and 0.65 vs. 0.64 for 18F-FDG, 18F-choline, and their combination, respectively). Conclusion: 18F-FDG/18F-choline PET positivity appears driven by both the Grade and mVI components in HCC. Consideration of the tumor microenvironment will likely be necessary to improve our understanding of multitracer PET positivity.

Role of 18F-choline and 18F-fluorodeoxyglucose positron emission tomography in combination with magnetic resonance imaging in brachytherapy planning for locally advanced cervical cancer: A pilot study.

Background and purpose: This pilot study aims to describe the advantages of combining metabolic and anatomic imaging modalities in brachytherapy (BT) planning for locally advanced cervical cancer (LACC) and to evaluate the supplementary value of Fluoro(F)-Choline positron emission tomography/computed tomography (PET/CT) in comparison to 18F-fluorodeoxyglucose (FDG) in this setting. Materials and methods: A prospective cohort of six patients with LACC was included in this study. Each patient underwent BT planning CT scan, magnetic resonance imaging (MRI), and both FDG and F-Choline PET/CT scans on the same day, with BT applicators in place. Patients were treated according to the standard of care. Metabolic target volumes (TV) were generated retrospectively and compared with the anatomic volumes using Dice coefficients and absolute volume comparison. Results: The threshold at which the metabolic and anatomic volumes were the most concordant was found to be 35% maximum standardized uptake value (SUV max) for both PET/CT scans. Amongst the six patients in this cohort, three in the FDG cohort and four in the F-Choline cohort were found to have more than ten percent ratio of excess (increase) in their MRI gross tumor volumes (GTV) when incorporating the metabolic information from the PET/CT scans. However, no significant changes were needed in the high risk-clinical target volumes (CTVHR) for both PET tracers. Conclusions: FDG and F-Choline PET/CT scans can substantially modify the BT GTV on MRI, without affecting the CTVHR. F-Choline is potentially more informative than FDG in assessing residual TV, particularly in cases with significant post-radiation inflammatory changes.

Cavernous Hepatic Hemangioma at 18F-Choline Positron Emission Tomography-Computed Tomography: Be Aware of the Pitfall.

We report a case of a patient performing a positron emission tomography-computed tomography (PET-CT) scan with [18F]F-Choline for biochemical relapse (Prostate specific antigen (PSA) 1.2 ng/ml) of prostate cancer. Two large areas of focal uptake with a cold core within the liver were observed. A contrast-enhanced ultrasound scan performed after the PET scan characterized these lesions as cavernous hepatic hemangiomas, and therefore, a biopsy was not performed; 3 years of follow-up and PET and MRI finding stability confirmed the benignity of their nature.

COVID-19 vaccine related hypermetabolic lymph nodes on PET/CT: Implications of inflammatory findings in cancer imaging.

We observed several patients presenting 2-[18F]FDG uptake in the reactive axillary lymph node at PET/CT imaging, ipsilateral to the site of the COVID-19 vaccine injection. Analog finding was documented at [18F]Choline PET/CT. The aim of our study was to describe this source of false positive cases. All patients examined by PET/CT were included in the study. Data concerning patient anamnesis, laterality, and time interval from recent COVID-19 vaccination were recorded. SUVmax was measured in all lymph nodes expressing tracer uptake after vaccination. Among 712 PET/CT scans with 2-[18F]FDG, 104 were submitted to vaccination; 89/104 patients (85%) presented axillary and/or deltoid tracer uptake, related to recent COVID-19 vaccine administration (median from injection: 11 days). The mean SUVmax of these findings was 2.1 (range 1.6-3.3). Among 89 patients with false positive axillary uptake, 36 subjects had received chemotherapy due to lymph node metastases from somatic cancer or lymphomas, prior to the scan: 6/36 patients with lymph node metastases showed no response to therapy or progression disease. The mean SUVmax value of lymph nodal localizations of somatic cancers/lymphomas after chemotherapy was 7.8. Only 1/31 prostate cancer patients examined by [18F]Choline PET/CT showed post-vaccine axillary lymph node uptake. These findings were not recorded at PET/CT scans with [18F]-6-FDOPA, [68Ga]Ga-DOTATOC, and [18F]-fluoride. Following COVID-19 mass vaccination, a significant percentage of patients examined by 2-[18F]FDG PET/CT presents axillary, reactive lymph node uptake. Anamnesis, low-dose CT, and ultrasonography facilitated correct diagnosis. Semi-quantitative assessment supported the visual analysis of PET/CT data; SUVmax values of metastatic lymph nodes were considerably higher than post-vaccine lymph nodes. [18F]Choline uptake in reactive lymph node after vaccination was confirmed. After the COVID-19 pandemic, nuclear physicians need to take these potential false positive cases into account in daily clinical practice.

PSMA-11 PET/CT for Detection of Recurrent Prostate Cancer in Patients With Negative Choline PET/CT.

INTRODUCTION: Prostate adenocarcinoma (CaP) is the leading cancer in men. After curative treatment, from 27% to 53% of patients will experience biochemical recurrence (BR). With the development of focal therapies, precise early identification of recurrence's sites is of utmost importance in order to deliver individualized treatment on positive lesions. The aim of this study was to assess the detection rate (DR) of 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in selected patients with prostate cancer BR and recent negative 18F-choline PET/CT. PATIENTS AND METHODS: We performed a retrospective analysis including all patients with CaP referred for BR with a negative 18F-choline PET/CT, and who underwent 68Ga-PSMA-11 PET/CT between October, 2018 and December, 2019. The overall DR of 68Ga-PSMA-11 PET/CT was calculated, and described according to BR characteristics especially PSA levels and velocity. Patients were followed up for at least 1 year. Patient management following 68Ga-PSMA-11 PET/CT and PSA levels evolution after treatment were also recorded. RESULTS: One hundred fifty-nine patients comprising 164 examinations were analyzed. The overall DR of 68Ga-PSMA-11 PET/CT for BR was 65.9% (95CI, 58.6-73.1). The DR was 52.5% (95CI, 39.9-65.0), 70.6% (95CI, 55.3-85.9), 70.4% (95CI, 53.1-87.6), and 78.6% (95CI, 66.2-91.0) for PSA levels between 0.2 and 0.49 ng/mL, 0.5 to 0.99 ng/mL, 1 to 1.99 ng/mL and PSA ≥ 2 ng/mL, respectively. The DR was 70.7% (95CI, 59.0-82.4) with a PSA doubling time (PSA-DT) ≤6 months and 65.2% (95CI, 55.5-74.9) with a PSA-DT >6 months. Around 3/4 of patients (75.9%) with a positive 68Ga-PSMA-11 PET/CT initiated treatment, including surgery (2.4%), stereotactic radiotherapy ± androgen deprivation therapy (ADT) (22%) or external conformational radiotherapy ± ADT (46.3%). Patient management changed in 43 cases (39.8%). CONCLUSION: Our study confirmed the ability of 68Ga-PSMA-11 PET/CT to detect occult biochemical recurrence, even in a selected population of CaP patients with negative 18F-choline PET/CT, even at low PSA levels.

Choline PET/CT in recurrent prostate cancer.

Purpose: Biochemical recurrence (BR) occurs in up to 40% of patients with prostate cancer (PCa) treated with primary radical prostatectomy (RP). Choline PET/CT may show, in a single-step examination, the site of tumor recurrence earlier than traditional imaging methods, particularly at low prostate-specific antigen (PSA) levels, thus influencing subsequent treatment. Methods/patients: Patients with recurrent and non-metastatic prostate cancer (nmPCa), who were assessed with choline PET/CT, were included in the analysis. Based on imaging results, the following therapeutic strategies were chosen: radiotherapy to the prostatic bed, androgen deprivation therapy (ADT), and chemotherapy or stereotactic body radiotherapy (SBRT) to either the pelvic lymph nodes or distant metastases. We assessed the impact of age, PSA levels, Gleason score (GS), and adjuvant therapy on oncological outcomes. Results: Data from 410 consecutive nmPCa patients with BR who underwent RP as primary treatment were analyzed. One hundred seventy-six (42.9%) patients had a negative choline PET/CT, and 234 (57.1%) patients resulted positive. In the multivariate analysis, only chemotherapy and PSA at recurrence were significant independent prognostic factors on overall survival (OS). In the PET-positive subgroup, the number of relapses, PSA post-prostatectomy, and chemotherapy impacted on OS. PSA (post-surgery and at recurrence) affected progression-free survival (PFS) in the univariate analysis. In the multivariate analysis, GS, the number of relapse sites, and PSA (post-surgery and at recurrence) were significant prognostic factors for disease-free survival (DFS). Conclusion: Choline PET/CT provides better accuracy than conventional imaging for the assessment of nmPCa with BR after prostatectomy, thereby enabling salvage strategies and improving quality of life.

PET/CT with 18F-choline or 18F-FDG in Hepatocellular Carcinoma Submitted to 90Y-TARE: A Real-World Study.

Our aim was to assess the role of positron emission computed tomography (PET/CT) with 18F-choline (18F-FCH) or 18F-fluorodeoxyglucose (18F-FDG) in hepatocellular carcinoma (HCC) submitted to 90Y-radioembolization (90Y-TARE). We retrospectively analyzed clinical records of 21 HCC patients submitted to PET/CT with 18F-fluorocholine (18F-FCH) or 18F-fluodeoxyglucose (18F-FDG) before and 8 weeks after 90Y-TARE. On pre-treatment PET/CT, 13 subjects (61.9%) were 18F-FCH-positive, while 8 (38.1%) resulted 18F-FCH-negative and 18F-FDG-positive. At 8-weeks post 90Y-TARE PET/CT, 13 subjects showed partial metabolic response and 8 resulted non-responders, with a higher response rate among 18F-FCH-positive with respect to 18F-FDG-positive patients (i.e., 76.9% vs. 37.5%, p = 0.46). Post-treatment PET/CT influenced patients' clinical management in 10 cases (47.6%); in 8 subjects it provided indication for a second 90Y-TARE targeting metabolically active HCC remnant, while in 2 patients it led to a PET-guided radiotherapy on metastatic nodes. By Kaplan−Meier analysis, patients' age (≤69 y) and post 90Y-TARE PET/CT's impact on clinical management significantly correlated with overall survival (OS). In Cox multivariate analysis, PET/CT's impact on clinical management remained the only predictor of patients' OS (p < 0.001). In our real-world study, PET/CT with 18F-FCH or 18F-FDG influenced clinical management and affected the final outcome for HCC patients treated with 90Y-TARE.

Diagnostic Performance of 18F-Choline Positron Emission Tomography/Contrast-Enhanced Computed Tomography in Adenoma Detection in Primary Hyperparathyroidism after Inconclusive Imaging: A Retrospective Study of 215 Patients.

This large, retrospective, single-centre study evaluated the diagnostic performance of 18F-choline positron emission tomography/contrast-enhanced computed tomography (PET/ceCT) in preoperative parathyroid adenoma detection in primary hyperparathyroidism cases after negative/inconclusive ultrasound or other imaging findings. We included patients who underwent surgery and 18F-choline PET/ceCT for inconclusive imaging results between 2015 and 2020. We compared the 18F-choline PET/ceCT results with surgical and histopathological findings and identified the variables influencing the correlation between 18F-choline PET/ceCT and surgical findings. Of 215 enrolled patients, 269 glands (mean lesion size, 10.9 ± 8.0 mm) were analysed. There were 165 unilocular and 50 multilocular lesions; the mean preoperative calcium level was 2.18 ± 0.19 mmol/L. Among 860 estimated lesions, 219 were classified as true positive, 21 as false positive, and 28 as false negative. The per-lesion sensitivity was 88.66%; specificity, 96.57%; positive predictive value, 91.40%; and negative predictive value, 95.39%. The detection and cure rates were 82.0% and 95.0%, respectively. On univariate and multivariate analyses, the maximum standardised uptake value (SUVmax), lesion size, and unilocularity correlated with the pathologic findings of hyperfunctioning glands. 18F-choline PET/ceCT presents favourable diagnostic performance as a second-line imaging method, with SUVmax, lesion size, and unilocularity predicting a high correlation between the 18F-choline PET/ceCT and surgical findings.