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PurposeTo 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 methodsThe 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.ResultsAmong 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).Conclusion18F-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.

Purpose: This study aims to establish whether metabolic parameters obtainable from FCH PET/CT can predict long-term response to radical radiotherapy (rRT) in patients with localized prostate cancer (PCa). Methods: Drawing on a single-center database, we retrospectively reviewed the pre-treatment FCH PET/CT scans of 50 patients who underwent rRT between 2012 and 2017. Patients were enrolled if they had a follow-up of at least 3 years after rRT. Various metabolic parameters were considered for each PET/CT, including FCH multifocality. rRT was administered to all patients for a total equivalent dose of 76–80 Gy, using a standard or hypofractionated schedule. Patients were classified as disease-free (DF) if their PSA levels after rRT rose by

A 69-year-old male patient who had a history of well-differentiated hepatocellular carcinoma (HCC) post right hepatectomy presented a year later with iron-deficiency anemia. His anemia work-up included upper endoscopy that revealed multiple gastric polyp a biopsy from the largest demonstrated metastatic hepatocellular carcinoma. His magnetic resonance imaging (MRI) showed a gastric ''polyp'' without evidence of local HCC recurrence within the liver. His subsequent dual imaging with Choline/fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) confirmed the gastric metastases and in addition revealed other sites of unexpected metastatic disease in the right adrenal and the bone that was asymptomatic.Patient was started on sorafenib and currently he is alive one-and-half-year postdetection of his metastatic disease under palliative care.This case showed that the possibility of gastric metastases should be kept in mind when confronted with anemia in HCC patient and also highlight the complementary role of molecular imaging modality along with MRI in the metastatic work-up for hepatocellular carcinoma postcurative resection.

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.

Evaluar el impacto terapéutico de la estadificación inicial de pacientes con cáncer de próstata mediante la exploración integrada usando PET/RM con 18F-colina. Estudio prospectivo de 31 pacientes diagnosticados de cáncer de próstata: Gleason > 7; PSA 13,6 ng/mL (6,3-20,6). Adquisición simultánea en cámara PET/RM tras la administración de 185 ± 18,5 MBq de 18F-colina: - Fase precoz/prostática (1-bed): emisión PET + RM multiparamétrica: DIXON-T1-T2- difusión-gadolinio. - Fase tardía/cuerpo completo: emisión PET + RM: DIXON-T1-T2-difusión-STIR. Interpretación visual y cálculo de SUV, ADC y texturas. Selección del tratamiento en comité oncológico. Todos los pacientes toleraron la exploración, sin artefactos. En ocho pacientes (25,8%) la RM fue superior en la estadificación T (Likert: 2-3), mientras que la PET aumentó la sensibilidad de la RM en tres pacientes (9,7%) (PIRADS: 3). Zona periférica 91,4%, transicional 8,6%. Umbral SUV máx 2,95: sensibilidad 92,9%, especificidad 66,7%. Sin correlación SUV vs. ADC. Mejor distinción estadio T2 vs. T3 mediante el modelo DiscrLin con NG = 16 (AUC 0,7767 ± 0,3386). La PET fue superior a la T2 en el análisis de texturas (0,588 vs. 0,412). En 17 pacientes (54,8%) la estadificación T fue ≥ T3, contraindicando la opción quirúrgica. Quince pacientes (48,4%) presentaron enfermedad extra-prostática: oligometástasis (8/31), multimetástasis (7/31). La decisión terapéutica tras PET/RM fue: 77,4% tratamiento radical (24/31), prostatectomía en 14 y radioterapia radioguiada en 10; el 22,6% recibió tratamiento sistémico (7/31). La PET/RM con 18F-colina muestra un carácter complementario en la estadificación T, con elevada tasa de detección de la infiltración NM. Los hallazgos de la exploración permiten la selección de los candidatos a prostatectomía o radioterapia radioguiada, evitando una terapia radical en un 22,6% de los pacientes. Evaluate the therapy impact of initial staging in patients diagnosed with prostate cancer by 18 F-choline PET/MRI hybrid technique. A prospective study which included 31 patients diagnosed with prostate cancer; Gleason > 7; mean PSA 13.6 ng/mL (range 6.3-20.6). PET/MRI studies were acquired simultaneously with hybrid equipment (SIGNA.3T, GE) following intravenous injection of 185 ± 18.5MBq of 18F-choline: - Early/prostate imaging: PET emission + multiparametric MR: DIXON-T1-T2-diffusion-gadolinium. - Late/whole-body imaging: PET emission + MR: DIXON-T1-T2-diffusion-STIR sequences. Images were visually evaluated. SUV & ADC & textures were also calculated. Treatment selection was based upon Oncology Committee consensus decision. Procedure was well tolerated in all patients, and no artifacts were reported. MRI was superior in T staging in eight patients (25.8%) (Likert: 2-3), whereas PET increased MRI sensitivity in three patients (9.7%) (PIRADS: 3). Peripheral 91.4%, transitional 8.6%. SUVmax threshold: 2.95: sensitivity 92.9%, specificity 66.7%. No correlation SUV vs. ADC. Better distinction between stage T2 vs. T3 using the DiscrLin model with NG = 16 (AUC 0.7767 ± 0.3386). PET was superior to T2 in textures analysis (0.588 vs. 0.412). Seventeen patients (54.8%) were staged ≥ T3, with surgical treatment being contraindicated. Fifteen patients (48.4%) presented with extra-prostatic disease: 8/31 oligometastatic and 7/31 multiple metastasis. Therapy approach following PET/MRI was: radical treatment in 24/31 patients (77.4%), 14 radical prostatectomy and 10 MRI-guided radiotherapy; systemic treatment in 7/31 patients (22.6%). 18F-choline PET/MRI had a complementary role for the T staging, with a high detection rate for NM infiltration. PET/MRI findings allowed patients to be directed either to prostatectomy or MRI-guided radiotherapy, and thus avoiding radicaltreatment in 22.6% of patients. [ABSTRACT FROM AUTHOR]

The aims of the present systematic review were to: (1) assess the role of 18F-fluorocholine (FCH) positron emission tomography (PET) with computed tomography (CT) and PET with magnetic resonance imaging (MRI) in patients with biochemically known hyperparathyroidism; (2) compare the diagnostic performance of FCH PET/CT or PET/MRI with conventional morphological and functional imaging. A literature search until December 2019 was performed in the PubMed, Scopus and Web of Science databases, using the terms "choline" AND "PET" AND "hyperparathyroidism". The search was conducted with and without the addition of filters (e.g., language: English only; type of article: original article; subjects: humans only) and selecting only articles published in the last 5 years. Twenty-three articles and 1112 patients were considered. Different FCH PET/CT acquisition protocols were adopted across the studies, using dynamic, early or delayed scans. FCH PET/CT proved more accurate than ultrasonography (US) or 99mTc-sestamibi single-photon emission tomography (SPET). PET/MRI also seemed to be more accurate than MRI alone in detecting benign parathyroid lesions. FCH PET/CT is more accurate than conventional morphological and functional imaging modalities (US or SPET) for the detection of benign parathyroid lesions. It could, therefore, be a reliable tool in both primary and recurrent hyperparathyroidism. [ABSTRACT FROM AUTHOR]

A 57-year-old male with history of thalassemia intermedia and hepatocellular carcinoma underwent a positron emission tomography/computed tomography (PET/CT) scan with 18F-choline before radioembolization procedure with 90Y-microspheres. The PET/CT scan with 18F-choline demonstrated highly increased tracer incorporation within a gross lesion in the hepatic dome coupled with diffuse activity in bone marrow, this latter aspect was probably due to the compensatory hematopoiesis stimulation induced by chronic hemolysis. This pattern of skeletal 18F-choline uptake should be considered as a peculiar PET/CT finding in thalassemic patients. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the role of 18F-choline (18F-FCH) positron emission tomography (PET)/computed tomography (CT) in high-risk differentiated thyroid cancer (DTC) patients with suspected relapse. It also compared 18F-FCH-PET/CT results with those of fludeoxyglucose (18F-FDG)-PET/CT and evaluated the additional diagnostic value and clinical impact of the combined use of these two tracers. Finally, it assessed the association between the clinical, biochemical, and histological parameters and 18F-FCH-PET/CT and 18F-FDG-PET/CT results. Methods: The study prospectively enrolled high-risk DTC patients treated with thyroidectomy and radioactive iodine therapy and presenting high/increasing thyroglobulin levels under thyrotropin suppression, negative/inconclusive neck ultrasound, and negative 131I whole-body scan. All patients underwent 18F-FDG-PET/CT and 18F-FCH-PET/CT within 30 days of each other. Experienced nuclear medicine physicians examined the images of both procedures, and an integrated analysis of the two PET/CT modalities was also conducted. For each modality, a patient-based analysis (PBA) and lesion-based-analysis (LBA) was performed. On PBA, sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were calculated. On LBA, only sensitivity was calculated. The standard of reference was based on clinical, imaging, and histological data. Results: Twenty-five high-risk DTC patients were included; DTC relapse/persistence was confirmed in 23 patients. On PBA, 18F-FDG-PET/CT, 18F-FCH-PET/CT, and the integrated evaluation of the two imaging modalities showed the following rates: sensitivity, specificity, negative predictive value, positive predictive value, and accuracy were 69.6%, 100%, 22.2%, 100%, and 72% versus 56.5%, 100%, 16.7%, 100%, and 60% versus 82.6%, 100%, 33.3%, 100%, and 84%, respectively. When compared with 18F-FDG-PET/CT, the integrated analysis of these two imaging procedures changed the clinical management in 4/23 (17%) patients. On LBA, the sensitivity rates of 18F-FDG-PET/CT, 18F-FCH-PET/CT, and the combined evaluation of the two modalities were 58.7%, 38.1%, and 66.7%, respectively; when only lymph node involvement was considered, the rates were 56.3%, 53.1%, and 68.8%, respectively. Serum thyroglobulin doubling time (Tg-DT) <12 months was significantly associated with positive 18F-FCH-PET/CT. A trend toward a significant association was also found between positive 18F-FDG-PET/CT and both Tg-DT <12 months and DTC aggressive subtypes. Conclusion:18F-FCH-PET/CT may add important information during the follow-up of high-risk DTC patients. 18F-FCH-PET/CT may be considered a useful complementary tool in patients affected by non-aggressive DTC subtypes, with Tg-DT <12 months, high risk of lymph node spreading, and negative or doubtful 18F-FDG-PET/CT. [ABSTRACT FROM AUTHOR]

Summary: Nuclear medicine has been implicated in the diagnosis and treatment of endocrine disorders for several decades. With recent development of PET tracers, functional imaging now plays a major role in endocrine tumors enabling with high performance to their localization, characterization, and staging. Besides 18F-FDG, which may be used in the management and follow-up of endocrine tumors, new tracers have emerged, such as 18F-DOPA for neuroendocrine tumors (NETs) (medullary thyroid carcinoma, pheochromocytomas and paragangliomas and well-differentiated NETs originating from the midgut) and 18F-Choline in the field of primary hyperparathyroidism. Moreover, some peptides such as somatostatin analogs can also be used for peptide receptor radionuclide therapy. In this context, Gallium-68 labeled somatostatin analogs (68Ga-SSA) can help to tailor therapeutic choices and follow the response to treatment in the so-called "theranostic" approach. This review emphasizes the usefulness of these three novel PET tracers (18F-Choline, 18F-FDOPA, and 68Ga-SSA) for primary hyperparathyroidism and neuroendocrine tumors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: Thyroid incidental uptake is defined as a thyroid uptake incidentally detected by imaging examinations performed for non-thyroid disease. The aim of this study was to establish the prevalence and the pathological nature of focal thyroid incidental uptake (FTIU) among patients studied with 18F-choline-PET/CT.Materials and methods: We retrospectively evaluated 368 patients who performed 18F-choline-PET/CT between June 2016 and August 2018. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax) and the mean SUV (SUVmean) of the thyroid gland and of the FTIU; every focal thyroid uptake deviating from physiological distribution and background was considered FTIU. Final diagnosis of FTIU was obtained by cytological or histological examination after surgery.Results: The average SUVmax and SUVmean of thyroid gland in population were 3 and 1.8. Among 368 patients, FTIU was identified in nine cases (2.4%) and eight underwent further investigations to determine the nature. Two FTIU were classified as malignant (thyroid carcinoma), whereas five were benign (three nodular hyperplasia, one follicular adenoma, one Hurtle cell adenoma) and one indeterminate at cytological examination. In malignant lesions, average SUVmax was 9.6 and 4.5, respectively, while average SUVmean was 5.3 and 2.9, respectively. Average SUVmax and SUVmean of benign lesions were 4.9 and 3.2 and of the indeterminate lesion 5 and 3, respectively.Conclusions: 18F-choline-PET/CT FTIU may be a relevant diagnostic reality, which requires further investigations and affects management, especially considering that, despite being mainly benign, also malignancy is possible. [ABSTRACT FROM AUTHOR]

Aim: 18F-Choline (FCH) uptake parameters are strong indicators of aggressive disease in prostate cancer. Functional parameters derived by magnetic resonance imaging (MRI) are also correlated to aggressive disease. The aim of this work was to evaluate the relationship between metabolic parameters derived by FCH PET/CT and functional parameters derived by MRI.Materials and Methods: Fourteen patients with proven prostate cancer who underwent FCH PET/CT and multiparametric MRI were enrolled. FCH PET/CT consisted in a dual phase: early pelvic list-mode acquisition and late whole-body acquisition. FCH PET/CT and multiparametric MRI examinations were registered and tumoral volume-of-interest were drawn on the largest lesion visualized on the apparent diffusion coefficient (ADC) map and projected onto the different multiparametric MR images and FCH PET/CT images. Concerning the FCH uptake, kinetic parameters were extracted with the best model selected using the Akaike information criterion between the one- and two-tissue compartment models with an imaging-derived plasma input function. Other FCH uptake parameters (early SUVmean and late SUVmean) were extracted. Concerning functional parameters derived by MRI scan, cell density (ADC from diffusion weighting imaging) and vessel permeability (Ktrans and Ve using the Tofts pharmakinetic model from dynamic contrast-enhanced imaging) parameters were extracted. Spearman's correlation coefficients were calculated to compare parameters.Results: The one-tissue compartment model for kinetic analysis of PET images was selected. Concerning correlation analysis between PET parameters, K1 was highly correlated with early SUVmean (r = 0.83, p < 0.001) and moderately correlated with late SUVmean (r = 0.66, p = 0.010) and early SUVmean was highly correlated with late SUVmean (r = 0.90, p < 0.001). No significant correlation was found between functional MRI parameters. Concerning correlation analysis between PET and functional MRI parameters, K1 (from FCH PET/CT imaging) was moderately correlated with Ktrans (from perfusion MR imaging) (r = 0.55, p = 0.041).Conclusions: No significant correlation was found between FCH PET/CT and multiparametric MRI metrics except FCH influx which is moderately linked to the vessel permeability in prostate cancer. [ABSTRACT FROM AUTHOR]

We aimed to investigate the role of positron emission computed tomography (PET/CT) with 18F-choline for predicting the outcome of metastatic castration-resistant prostate cancer (mCRPC) submitted to treatment with Radium-223 (223Ra-therapy). Clinical records of 20 mCRPC patients submitted to PET/CT with 18F-choline before 223Ra-therapy were retrospectively evaluated. The following PET-derived parameters were calculated: number of lesions, maximum and mean standardized uptake values (SUVmax, SUVmean), lean body mass corrected SUV peak (SULpeak), metabolic tumor volume (MATV), and total lesion activity (TLA). After 223Ra-therapy, all patients underwent regular follow-up until death. The predictive power of clinical and PET-derived parameters on overall survival (OS) was assessed by Kaplan–Meier analysis and the Cox proportional hazard method. All the patients showed 18F-choline-avid lesions at baseline PET/CT. Among the enrolled subjects, eleven (55%) completed all the six scheduled cycles of 223Ra-therapy; seven (35%) were responders according to imaging and biochemical parameters. Mean OS was 12.7 ± 1.4 months: by Kaplan–Meier analysis, number of lesions, PSA level and TLA were significantly correlated with OS. In multivariate Cox analysis, TLA remained the only significant predictor of survival (p = 0.003; hazard ratio = 7.6, 95% confidence interval = 1.9–29.5 months). 18F-choline PET may be useful for patients’ stratification before 223Ra-therapy. In particular, high metabolically active tumor burden (i.e., TLA) was predictive of poor outcome.

Aim: The aim of the study was to compare the kinetic analysis of 18F-labeled choline (FCH) uptake with static analysis and clinicopathological parameters in patients with newly diagnosed prostate cancer (PC).Materials and Methods: Sixty-one patients were included. PSA was performed few days before FCH PET/CT. Gleason scoring (GS) was collected from systematic sextant biopsies. FCH PET/CT consisted in a dual phase: early pelvic list-mode acquisition (from 0 to10 min post-injection) and late whole-body acquisition (60 min post-injection). PC volume of interest was drawn using an adaptative thresholding (40% of the maximal uptake) on the late acquisition and projected onto an early static frame of 10 min and each of the 20 reconstructed frames of 30 s. Kinetic analysis was performed using an imaging-derived plasma input function. Early kinetic parameter (K1 as influx) and static parameters (early SUVmean, late SUVmean, and retention index) were extracted and compared to clinicopathological parameters.Results: K1 was significantly, but moderately correlated with early SUVmean (r = 0.57, p < 0.001) and late SUVmean (r = 0.43, p < 0.001). K1, early SUVmean, and late SUVmean were moderately correlated with PSA level (respectively, r = 0.36, p = 0.004; r = 0.67, p < 0.001; r = 0.51, p < 0.001). Concerning GS, K1 was higher for patients with GS ≥ 4 + 3 than for patients with GS < 4 + 3 (median value 0.409 vs 0.272 min- 1, p < 0.001). No significant difference was observed for static parameters.Conclusions: FCH influx index K1 seems to be related to GS and could be a non-invasive tool to gain further information concerning tumor aggressiveness. [ABSTRACT FROM AUTHOR]

Introduction: Dynamic image acquisition with 18F-Choline (FCH) PET/CT in prostate cancer is mostly used to overcome the bladder repletion which could obstruct the loco-regional analysis. The aim was to analyze early dynamic FCH acquisitions to define pelvic lymph node or prostate pathological status. Material and methods: Retrospective analysis was performed on 39 patients for initial staging (n=18), or after initial treatment (n=21). Patients underwent ten-minute dynamic acquisitions centered on the pelvis, after injection of 3-4 MBq/kg of FCH. Whole body images were acquired about one hour after injection using a PET/CT GE Discovery LS (GE-LS) or Siemens Biograph mCT (mCT). Maximum and mean SUV according to time were measured on nodal and prostatic lesions. SUVmean was corrected for partial volume effect (PVEC) with suitable recovery coefficients. The status of each lesion was based on histological results or patient follow-up (>6 months). A Mann-Whitney test and ANOVA were used to compare mean and receiver operating characteristic curve analysis.Results: The median PSA was 8.46 ng/mL and the median Gleason score was 3+4. Ninety-two lesions (43 lymph nodes and 49 prostate lesions) were analyzed, including 63 malignant lesions. In early dynamic acquisitions, the maximum and mean SUV were significantly higher, respectively on mCT and GE-LS, in malignant versus benign lesions (p

Introduction: 18F-Choline PET-CT is an increasingly used technique in patients with prostate cancer. The main indication is to localise the disease in patients with biochemical recurrence. To accurately interpret 18F-Choline PET, knowledge of normal tracer distribution is paramount. The aim of this study was to describe the normal distribution pattern of 18F-Choline by measuring the maximum standardized uptake values (SUVs) of various organs. Methods: 18F-Choline PET was performed in ten consecutive patients. Approximately 370 MBq of tracer was injected intravenously and a low amperage CT scan was performed for attenuation correction of PET images.Maximum SUVs were calculated on the reconstructed images for various organs. These SUVmax values depend on multiple factors and could be variable depending on the reconstruction CT methods, acquisition time and region of interest (ROI) parameters. Results: Physiologic symmetric increased tracer uptake was noted in the salivary glands and parotid glands. Intense physiological uptake was present in the liver, pancreas, duodenum, stomach, kidneys and urinary bladder and moderate to intense uptake in the sublingual glands, lacrimal glands, nasal mucosa, thyroid gland, tonsils, adrenal glands, large bowel, bone marrow and spleen. Low-grade-to-moderate uptake was present in the choroid plexus, pituitary gland, soft palate, pharynx, left myocardium, lungs, mediastinal blood pool, testicles and muscles. Prostate and prostatic beds were excluded from the volumes of interest. Conclusion: This study is the first one to describe a normal range of SUVmax values for 18F-Choline PET in various organs. [ABSTRACT FROM AUTHOR]

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Ghidaglia, Laurent, Sebagh, Pascale, Durand, Golse and Besson.)

BACKGROUND: The aim of this study was to observe and characterize the nonspecific 18F-choline lymph node uptake in patients with prostate cancer. MATERIAL AND METHODS: In this single center, prospective observational study which was done in University Hospital Center Zagreb between December 2012 and October 2014, 69 patients (median age 71 years; range 50-92) with prostate cancer were included. Patients underwent 18F-choline PET/CT for staging or restaging of prostate cancer. The mean follow-up period was 11.5 months. Kruskal-Wallis test was used to find out if the differences between SUV values of specific and nonspecific accumulation of the tracer are statistically significant. RESULTS: Nonspecific accumulation of 18F-choline in lymph nodes was found in 36 patients (52.7%). Most of these findings (n = 24) were nonspecific accumulation of the tracer in mediastinal lymph nodes. Other sites of nonspecific tracer uptake were pulmonary hila (n = 20), inguinal lymph nodes (n = 15), and axillary lymph nodes (n = 10). Mean SUV values for mediastinal lymph nodes, pulmonary hila, axillary and inguinal lymph nodes were 4.8, 4.3, 3.1 and 4.1, respectively. Mean SUV value of nonspecific sites of tracer accumulation was lower (not significantly; (p = 0.2) than tracer uptake values measured in metastases sites (bone metastases mean SUVmax value — 13.2, metastatic lymph nodes mean SUVmax value — 9.2). CONCLUSIONS: 18F-choline PET/CT is a valuable and an established functional diagnostic imaging method for staging and restaging prostate cancer. However, nonspecific uptake of the tracer can often be seen in lymph nodes not related to primary disease. Patient history, clinical examination, laboratory tests and correlation with other imaging methods, must be taken into consideration when interpreting 18F-choline PET/CT findings. [ABSTRACT FROM AUTHOR]