18F-FDG gallbladder uptake: observation from a total-body PET/CT scanner.

BACKGROUND: Total-body positron emission tomography/computed tomography (PET/CT) scanners are characterized by higher signal collection efficiency and greater spatial resolution compared to conventional scanners, allowing for delayed imaging and improved image quality. These advantages may also lead to better detection of physiological processes that diagnostic imaging professionals should be aware of. The gallbladder (GB) is not usually visualized as an 18F-2-fluorodeoxyglucose (18F-FDG)-avid structure in routine clinical PET/CT studies; however, with the total-body PET/CT, we have been increasingly visualizing GB activity without it being involved in an inflammatory or neoplastic process. The aim of this study was to report visualization rates and characteristics of GB 18F-FDG uptake observed in both healthy and oncological subjects scanned on a total-body PET/CT system. MATERIALS AND METHODS: Scans from 73 participants (48 healthy and 25 with newly diagnosed lymphoma) who underwent 18F-FDG total-body PET/CT were retrospectively reviewed. Subjects were scanned at multiple timepoints up to 3 h post-injection. Gallbladder 18F-FDG activity was graded using liver uptake as a reference, and the pattern was qualified as present in the wall, lumen, or both. Participants' characteristics, such as age, sex, body-mass index, blood glucose, and other clinical parameters, were collected to assess for any significant correlation with GB 18F-FDG uptake. RESULTS: All 73 subjects showed GB uptake at one or more imaging timepoints. An increase in uptake intensity overtime was observed up until the 180-min scan, and the visualization rate of GB 18F-FDG uptake was 100% in the 120- and 180-min post-injection scans. GB wall uptake was detected in a significant number of patients (44/73, 60%), especially at early timepoint scans, whereas luminal activity was detected in 71/73 (97%) subjects, especially at later timepoint scans. No significant correlation was found between GB uptake intensity/pattern and subjects' characteristics. CONCLUSION: The consistent observation of GB 18F-FDG uptake recorded in this study in healthy participants and subjects with a new oncological diagnosis indicates that this is a normal physiologic finding rather than representing an exception.

Prevalence of gastrointestinal disorders in individuals with RASopathies: May RAS/MAP/ERK pathway dysfunctions be a model of neuropathic pain and visceral hypersensitivity?

RASopathies are a group of neurodevelopmental syndromes caused by germline variants in genes of the Ras/MAP/ERK pathway. Growth failure, neurological involvement, and pain represent the main features of these conditions. ERK signaling cascade plays a crucial role in nociception and visceral pain and it is likely implicated in the genesis of neuropathic pain and maintenance of altered pain states. We studied the prevalence of abdominal pain and functional gastrointestinal (GI) disorders in a large sample of individuals with RASopathies. A brief pain inventory questionnaire and semi-structured dedicated interview were used to investigate presence and localization of pain. A Rome IV questionnaire was used to screen for functional GI disorders. Eighty patients with clinical and molecular diagnoses of RASopathy were recruited (42 with Noonan syndrome; 17 with Costello Syndrome and 21 with cardio-facio-cutaneous syndrome). Overall, the prevalence of abdominal pain was 44% and prevalence of functional GI disorders was 78% with constipation, abdominal pain, and aerophagia being the most frequently detected ones. A significant association was found between pain and irritable bowel syndrome, functional constipation and aerophagia. Children with RASopathies have a high prevalence of functional gastrointestinal disorders. These children could represent a good in vivo model to study neuropathic pain, visceral hypersensitivity and gut-brain axis disorders.

18F-FDG PET and 18F-FDG PET/CT in Vulvar Cancer: A Systematic Review and Meta-analysis.

AIM: The aims of this study were to determine the role of 18F-FDG PET/CT in vulvar cancer patients and to extract summary estimates of its diagnostic performance for preoperative lymph node staging. PATIENTS AND METHODS: PubMed/Medline and Embase databases were searched to identify studies evaluating 18F-FDG PET/CT in vulvar cancer patients. The assessment of methodological quality of the included articles was performed. Per-patient and per-groin pooled estimates, with 95% confidence intervals (CIs), of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic odds ratio (DOR) were calculated. RESULTS: Ten articles were included in the systematic review, 7 among which evaluated the diagnostic performance of preoperative 18F-FDG PET/CT for lymph node staging. Qualitative per-patient analysis (72 patients from 4 studies) resulted in estimated pooled sensitivity, specificity, PPV, NPV, and DOR of 0.70 (95% CI, 0.44-0.95), 0.90 (95% CI, 0.76-1.04), 0.86 (95% CI, 0.66-1.06), 0.77 (95% CI, 0.56-0.97), and 10.49 (95% CI, 1.68-65.50), respectively. Qualitative per-groin analysis (245 groins from 5 studies) resulted in estimated pooled sensitivity, specificity, PPV, NPV, and DOR of 0.76 (95% CI, 0.57-0.94), 0.88 (95% CI, 0.82-0.94), 0.70 (95% CI, 0.55-0.85), 0.92 (95% CI, 0.86-0.97), and 19.43 (95% CI, 6.40-58.95), respectively. CONCLUSIONS: Despite limited literature data, this systematic review and meta-analysis revealed that a negative preoperative PET/CT scan may exclude groin metastases in at least early-stage vulvar cancer patients currently unfit for sentinel node biopsy and select those eligible for a less invasive surgical treatment. A positive PET/CT result should otherwise be interpreted with caution. Larger prospective studies are needed to confirm these results and to evaluate the diagnostic value of standardized semiquantitative analysis compared with the qualitative one.

A Bio-Imaging Signature as a Predictor of Clinical Outcomes in Locally Advanced Pancreatic Cancer.

Purpose: To evaluate the predictive value of 18F-FDG PET/CT semiquantitative parameters of the primary tumour and CA 19-9 levels assessed before treatment in patients with locally advanced pancreatic cancer (LAPC). Methods: Among one-hundred twenty patients with LAPC treated at our institution with initial chemotherapy followed by curative chemoradiotherapy (CRT) from July 2013 to January 2019, a secondary analysis with baseline 18F-FDG PET/CT was conducted in fifty-eight patients. Pre-treatment CA 19-9 level and the maximum standardized uptake value (SUVmax), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) of primary tumour were measured. The receiving operating characteristics (ROC) analysis was performed to define the cut-off point of SUVmax, MTV, TLG and CA 19-9 values to use in prediction of early progression (EP), local progression (LP) and overall survival (OS). Areas under the curve (AUCs) were assessed for all variables. Post-test probability was calculated to evaluate the advantage for parameters combination. Results: For EP, CA 19-9 level > 698 U/mL resulted the best marker to identify patient at higher risk with OR of 5.96 (95% CI, 1.66-19.47; p = 0.005) and a Positive Predictive Value (PPV) of 61%. For LP, the most significant parameter was TLG (OR 9.75, 95% CI, 1.64-57.87, p = 0.012), with PPV of 83%. For OS, the most significant parameter was MTV (OR 3.12, 95% CI, 0.9-10.83, p = 0.07) with PPV of 88%. Adding consecutively each of the other parameters, PPV to identify patients at risk resulted further increased (>90%). Conclusions: Pre-treatment CA 19-9 level, as well as MTV and TLG values of primary tumour at baseline 18F-FDG PET/CT and their combination, may represent significant predictors of EP, LP and OS in LAPC patients.

Is 18F-fluorodeoxyglucose positron emission tomography/computed tomography useful to discriminate metachronous lung cancer from metastasis in patients with oncological history?

BACKGROUND: Solitary pulmonary nodules detected during follow-up in patients with previous cancer history have a high probability of malignancy being either a metachronous lung cancer or a metastasis. This distinction represents a crucial issue in the perspective of "personalized medicine," implying different treatments and prognosis. Aim, to evaluate the role of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in distinguishing whether solitary pulmonary nodules are metachronous cancers or metastases and the relationship between the nodule's characteristics and their nature. METHODS: From a single-institution database, we retrospectively selected all patients with a previous cancer history who performed 18F-FDG PET/CT to evaluate pulmonary nodules detected during follow-up, ranging from 5 mm to 40 mm, and histologically diagnosed as malignant. RESULTS: Between September 2009 and August 2017, 127 patients (80 males; mean age=70.2±8.5years) with 127 malignant nodules were included: 103/127 (81%) metachronous cancers, 24/127 (19%) metastases. In both groups, PET/CT provided good and equivalent detection rate of malignancy (81% vs. 83%). No differences between metachronous cancers and metastases were found in: patient's age (70.3±8.1 years vs. 69.5±9.7years), gender (males=63.1% vs. 62.5%), interval between previous cancer diagnosis and nodules' detection (median time=4years vs. 4.5years), location (right-lung=55% vs. 54%; upper-lobes=64% vs. 67%; central-site=31% vs. 25%), size (median size=17mm vs. 19.5mm), 18F-FDG standardized uptake value (median SUVmax=5.2 vs. 5.9). CONCLUSIONS: In oncological patients, despite its high detection rate, 18F-FDG PET/CT, as well as any other clinico-anatomical features, cannot distinguish whether a malignant solitary pulmonary nodule is a metachronous lung cancer or a metastasis, supporting the need of histological differential diagnosis.