Positron Emission Tomography-computed Tomography Scan Research Articles

Anaplastic Thyroid Carcinoma versus Metastatic SCC: A Diagnostic Dilemma in a Rare Presentation of Post-Radiation Thyroid Swelling

AbstractA 71-year-old male with type 2 diabetes and hypertension was diagnosed with carcinoma of the pyriform fossa in 2019. The biopsy was reported as a moderately differentiated squamous cell carcinoma, and positron emission tomography-computed tomography (PET-CT) scan showed an fluorodeoxyglucose (FDG)-avid lesion in the pyriform fossa and the aryepiglottic fold with few nodes in level II and level III. The paitent was treated with radical chemoradiotherapy. A follow-up PET-CT scan done in 2022 revealed an FDG-avid soft tissue thickening in the left palatine tonsillar region and an uptake in the thyroid that was reported as not significant. A punch biopsy from the tonsillar fossa lesion revealed squamous cell carcinoma. The lesion was treated as a second primary and treated with radiotherapy with curative intent. The patient was complaining of dysphagia, difficulty in breathing, and weight loss around 6 months after treatment that were addressed medically. There was a significant reduction in size and FDG activity of the ill-defined thickening in the left tonsillar region which was seen in the response-assessment PET done 6 months after RT. A heterogeneously enhancing nodules were seen in both lobes of the thyroid in which the largest one measured 3.5 × 3.1 cm seen in the right lobe. The patient underwent a biopsy from the thyroid that revealed a benign thyroid gland infiltrated by clusters and nests of poorly differentiated malignant cells. The histomorphology was suggestive of a poorly differentiated carcinoma, likely anaplastic carcinoma thyroid, or metastasis of the squamous cell carcinoma. Curative treatment was ruled out in this case due to his comorbidities, pulmonary symptoms, and radiation delivered to the neck.

The Contribution of 18F FDG PET-CT for the Investigation of Fever of Unknown Origin and Inflammation of Unknown Origin

BackgroundFever of unknown origin and inflammation of unknown origin are highly challenging diagnostic conditions. The current practice for evaluating patients is to conduct a positron emission tomography-computed tomography (PET-CT) scan as either a first- or a second-line modality. We aimed to assess the contributory effect of PET-CT to the diagnosis and compare it with the contributory effect of CT alone. MethodsWe performed a systematic review and meta-analysis. We included all cohorts that examined the contribution of PET-CT to the investigation of classical fever of unknown origin and inflammation of unknown origin. The primary outcome was the contribution of PET-CT to the final diagnosis. Secondary outcomes were sensitivity and specificity of PET-CT and CT scans, and contribution of a CT scan. We pooled the results of all studies and calculated the pooled contributory effect of PET-CT. ResultThirty-six studies (3516 patients) were included in the systematic review. The pooled contribution of PET-CT was 75.4%. The compiled sensitivity and specificity values for all studies were 85.9% and 59.5%, respectively. Five studies (405 patients) compared between the PET-CT component and the total body CT component. The pooled contribution of a CT scan was 68%. The summed sensitivity and specificity values of a CT scan for all studies were 63.1% and 84.4%, respectively. ConclusionsPET-CT has a contributory effect of 75% for the diagnosis of fever of unknown origin and inflammation of unknown origin. PET-CT had superior sensitivity and inferior specificity vs the CT scan.

Evaluating Prognosis of Gastrointestinal Metastatic Neuroendocrine Tumors: Constructing a Novel Prognostic Nomogram Based on NETPET Score and Metabolic Parameters from PET/CT Imaging.

The goal of this study is to compare the prognostic performance of NETPET scores, based on gallium-68 DOTANOC (68Ga-DOTANOC) and fluorine-18 fluorodeoxyglucose (18F-FDG) Positron Emission Tomography-Computed Tomography (PET-CT), and PET-CT metabolic parameters in metastatic gastrointestinal neuroendocrine tumors (GI-NET), while constructing and validating a nomogram derived from dual-scan PET-CT. In this retrospective study, G1-G3 GI-NET patients who underwent 68Ga-DOTANOC and 18F-FDG PET scans were enrolled and divided into training and internal validation cohorts. Three grading systems were constructed based on NETPET scores and standardized uptake value maximum (SUVmax). LASSO regression selected variables for a multivariable Cox model, and nomograms predicting progression-free survival (PFS) and overall survival (OS) were created. The prognostic performance of these systems was assessed using time-dependent receiver-operating characteristic (ROC) curves, concordance index (C-index), and other methods. Nomogram evaluation involved calibration curves, decision curve analysis (DCA), and the aforementioned methods in both cohorts. In this study, 223 patients (130 males; mean age ± SD: 52.6 ± 12 years) were divided into training (148) and internal validation (75) cohorts. Dual scans were classified based on NETPET scores (D1-D3). Single 68Ga-DOTANOC and 18F-FDG PET-CT scans were stratified into S1-S3 and F1-F3 based on SUVmax. The NETPET score-based grading system demonstrated the best OS and PFS prediction (C-index, 0.763 vs. 0.727 vs. 0.566). Nomograms for OS and PFS exhibited superior prognostic performance in both cohorts (all AUCs > 0.8). New classification based on NETPET score predicts patient OS/PFS best. PET-CT-based nomograms show accurate OS/PFS forecasts.

FDG Avid Intracholecystic Papillary Neoplasm Mimicking Hepatic Metastasis in a Patient with Head-and-neck Cancer.

A 75-year-old male with head-and-neck squamous cell cancer received a staging f-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) scan which showed additional focal abnormal uptake in the right hepatic lobe. The patient was treated for probable metastatic disease. Restaging FDG PET/CT scan revealed resolution of uptake in the head-and-neck and persistent focal uptake in the presumed liver metastasis. An abdominal CT with intravenous contrast revealed an enhancing mass in the gallbladder, without extension into the liver. Cholecystectomy revealed an intracholecystic papillary neoplasm of the gallbladder. The initial appearance of hepatic metastasis was due to a misregistration artifact.

Cold exposure modulates potential brown adipokines in humans, but only FGF21 is associated with brown adipose tissue volume.

The study objective was to investigate the effect of cold exposure on the plasma levels of five potential human brown adipokines (chemokine ligand 14 [CXCL14], growth differentiation factor 15 [GDF15], fibroblast growth factor 21 [FGF21], interleukin 6 [IL6], and bone morphogenic protein 8b [BMP8b])and to study whether such cold-induced effects are related to brown adipose tissue (BAT) volume, activity, or radiodensityin young humans. Plasma levels of brown adipokines were measured before and 1 h and 2 h after starting an individualized cold exposure in 30 young adults (60% women, 21.9 ± 2.3 y; 24.9 ± 5.1 kg/m2 ). BAT volume, 18 F-fluorodeoxyglucose uptake, and radiodensity were assessed by a static positron emission tomography-computerized tomography scan after cold exposure. Cold exposure increased the concentration of CXCL14 (Δ2h = 0.58 ± 0.98 ng/mL; p = 0.007), GDF15 (Δ2h = 19.63 ± 46.2 pg/mL; p = 0.013), FGF21 (Δ2h = 33.72 ± 55.13 pg/mL; p = 0.003), and IL6 (Δ1h = 1.98 ± 3.56 pg/mL; p = 0.048) and reduced BMP8b (Δ2h = -37.12 ± 83.53 pg/mL; p = 0.022). The cold-induced increase in plasma FGF21 was positively associated with BAT volume (Δ2h: β = 0.456; R2 = 0.307; p = 0.001), but not with 18 F-fluorodeoxyglucose uptake or radiodensity. None of the changes in the other studied brown adipokines was related to BAT volume, activity, or radiodensity. Cold exposure modulates plasma levels of several potential brown adipokines in humans, whereas only cold-induced changes in FGF21 levels are associated with BAT volume. These findings suggest that human BAT might contribute to the circulatory pool of FGF21.

Prognostic value of hypermetabolic bone sarcoidosis observed by 18F-fluorodeoxyglucose positron emission tomography.

Sarcoidosis is a multisystemic granulomatosis diagnosed mainly in young adults.18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) is useful in sarcoidosis cases to search for a biopsiable site or assess disease activity.18F-FDG PET-CT can reveal bone hypermetabolism in sarcoidosis patients, even in the absence of osteoarticular symptoms. The aim of this study was to describe metabolic bone involvement in sarcoidosis patients and to evaluate its prognostic impact. This was an observational, comparative, retrospective, monocentric study. Inclusion criteria were a confirmed diagnosis of sarcoidosis according to the World Association of Sarcoidosis and Other Granulomatous Diseases (WASOG) criteria and at least one 18F-FDG PET-CT scan during follow-up. Metabolic bone involvement of sarcoidosis was defined as focal bone hypermetabolism with no argument for a differential diagnosis of bone 18F-FDG uptake. Patients with and without bone involvement were compared. Among the 175 included patients, 32 (18%) had metabolic bone involvement of sarcoidosis. The metabolic bone involvement was mainly axial and mostly without bone abnormalities on CT. Metabolic bone involvement was associated with intrathoracic and extrathoracic lymph node involvement and with a higher number of organs involved. Patients with metabolic bone involvement more frequently received corticosteroids, methotrexate and tumor necrosis factor (TNF)-α inhibitors and a higher number of treatments. Relapse of sarcoidosis occurred sooner in patients with metabolic bone involvement. These results suggest that metabolic bone involvement is associated with more diffuse and more severe sarcoidosis.

Coexistence of Colorectal Cancer and Immunoglobulin G4-Related Disease in the Same Lesion: A Rare Case with Molecular Classification.

Immunoglobulin G4-related disease (IgG4-RD) is a novel fibroinflammatory disorder characterized by enlargement of the involved organs, elevated IgG4 levels, and abundant infiltration of IgG4-positive plasma cells. Indeed, primary colon cancers arising from IgG4-RD are rare. This case report describes a rare occurrence of simultaneous colorectal cancer and IgG4-RD in the same lesion in a 62-year-old male patient. The patient underwent a right hemicolectomy under the suspicion of primary colon cancer. The mass was grossly well-defined and yellowish tan, and the background colon was fibrotic. Microscopically, the tumor cells showed glandular differentiation characteristic of adenocarcinoma in a background of dense lymphoplasmacytic infiltration with fibrosis and obliterative phlebitis in the pericolic fat tissue. IgG4 immunohistochemical staining showed diffuse positivity in infiltrating plasma cells. The patient was administered adjuvant chemotherapy and prednisolone therapy. The patient's serum IgG4 levels gradually decreased, and a follow-up positron emission tomography-computed tomography scan 1 year after surgery showed no evidence of local or distant recurrence of colorectal cancer. IgG4-RD occurring concurrently with primary colon adenocarcinoma has not been reported. Increased awareness of this rare coexistence can guide clinicians in navigating diagnostic complexities and selecting optimal therapeutic strategies.

Detection of Primary Hepatocellular Carcinoma on 18F-Fluorodeoxyglucose Positron Emission Tomography-computed Tomography.

Hepatocellular carcinoma (HCC), ranks as the third most prevalent malignancy contributing to cancer-related death on a global scale. Hepatocellular carcinoma is known to be the fifth most frequently diagnosed malignancy of the males while among females, it is ranked as the seventh most common malignancy. The study was conducted to detect the sensitivity of primary HCC using 18F-flourodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) scan. This prospective study was conducted to identify the primary HCC in a sample size of 51 patients, in whom FDG PET-CT scan was performed between May 2022 and December 2022. Among the cohort of 51 patients, primary HCC was detected on FDG PET-CT in 43 individuals representing true-positive cases. Conversely, FDG PET-CT was unable to detect HCC in 8 cases, representing false-negative. Out of 51 patients, 74.5% of HCC cases exhibited multifocal pattern. The maximum standardized uptake value (SUV max) of the primary malignant site ranged from 1.9 to 16.1, with a mean of 3.7 ± 2.8. The FDG PET-CT revealed abnormal sites of the uptake outside liver in 23 individuals. The research confirmed the tumor recurrence in four previously treated patients. In the conducted investigation, FDG PET-CT showed 84.3% sensitivity for the diagnosis of HCC. The study demonstrates that FDG PET-CT is a viable option for the detection of HCC. The sensitivity of FDG PET-CT in our population is comparable and in agreement with international data for diagnosis of HCC thereby favoring its reproducibility among geographical and ethnic groups. However, owing to the reduced ability of FDG PET-CT scan to identify well-differentiated/low-grade HCC, the routine use of FDG PET-CT scan may not be considered in cases requiring evaluation of primary disease only. Arshad K, Hanan SD, Younis MN, et al. Detection of Primary Hepatocellular Carcinoma on 18F-Fluorodeoxyglucose Positron Emission Tomography-computed Tomography. Euroasian J Hepato-Gastroenterol 2023;13(2):66-72.

An unusual case of sarcoidosis presenting as calf pain.

Sarcoidosis is a multisystem chronic inflammatory disease predominantly affecting the lungs. Myositis as a presenting manifestation of sarcoidosis is extremely uncommon and seldom reported. Here we report a 20-year-old male who presented with bilateral calf pain for six months. On evaluation magnetic resonance imaging showed features of myositis, and muscle biopsy was suggestive of sarcoidosis with granulomatous vasculitis. Positron emission tomography-computed tomography scan revealed involvement of spleen in addition to the muscles. Patient was managed with corticosteroids and azathioprine, and showed good treatment response.

Report of Incidental Vulvar Malignant Melanoma Upon Dermatologic Evaluation for Vaginal Cyst

BACKGROUND: Vulvar malignant melanoma is a rare, often aggressive and recurring disease with a poorly understood prognosis. Here, we describe a patient with a longstanding vaginal cyst who was diagnosed with vulvar malignant melanoma upon a dermatologic evaluation. THE CASE: Our patient, a 53-year-old female, with a family history of a father with malignant melanoma presented for evaluation of a vaginal cyst present for over 20 years on her right labia that had become painful and began draining over the past year. She was seen twice at urgent care and was treated with oral antibiotics (unspecified) and referred to dermatology. A comprehensive dermatologic evaluation of the epidermal inclusion cyst in the right labia majora incidentally revealed a neoplasm of uncertain behavior in the right labia minora suspected for vulvar malignant melanoma (Figure 1). Shave biopsy of her right labia minora revealed a Stage 1B malignant melanoma, superficial spreading type, with a 1.1 mm depth of invasion (Breslow thickness) and 11 per 1mm2 mitotic count. Right partial radical vulvectomy and bilateral inguinal sentinel lymph node biopsies were performed. Pathology showed malignant melanoma with negative margins and negative nodes. Treatment and excision for her vaginal cyst was not initiated as her symptoms were not bothersome at the time of visit. She presented with a post-operative infection after 2 weeks which was suggestive of bilateral inguinal vulval acute cellulitis with no definitive abscess upon computed tomography (CT) scan. She was initially treated with vancomycin with additional piperacillin/tazobactam for a total of three days. Trimethoprim/sulfamethoxazole was later initiated for 14 days. Medical oncology referral for evaluation of metastasis revealed normal positron emission tomography-computed tomography scan. Notably, the patient had extensive confluent/atypical lentiginous basal melanocytic hyperplasia at the periphery which could not be distinguished from melanoma in situ. Upon tumor board consultation, scouting biopsies of her left labia majora were performed. Pathology showed melanocytic hyperplasia instead of residual malignant melanoma at the periphery. The patient now follows up every few months with dermatology and medical oncology. CONCLUSION: Given the often fast, aggressive spread of vulvar malignant melanoma, timely dermatologic evaluations are necessary. Among those at higher risk due to a personal or family history of malignant melanoma, regular total body skin cancer screenings are indicated. Further, the sensitive and typically sun-protected location of a vulvar malignant melanoma might preclude a dermatologic evaluation in this area and highlights the need for more comprehensive vaginal screenings and better communication between dermatologic and gynecologic medical care teams.

Correlation analysis of positron emission tomography/computed tomography-magnetic resonance imaging of cannabinoid type 1 receptor in the lumbar spine and brain of aged osteoporosis female cynomolgus monkeys.

Although cannabinoid receptor 1 (CB1R) antagonists can inhibit bone loss in osteoporosis mouse models, different strains of mice show different bone mass phenotypes after knock out the CB1R gene. The relationship between CB1R and bone metabolism is complex, and its regulatory role in bone metabolism and as a therapeutic target for osteoporosis requires further investigation. Based on lumbar spine volumetric bone mineral density (vBMD) data of healthy female cynomolgus monkeys aged 1-25 years, naturally aged postmenopausal female osteoporotic monkeys and normal young monkeys were screened by detecting lumbar vertebrae vBMD and estradiol levels in this study. Positron emission tomography-computed tomography (PET/CT) and magnetic resonance imaging (MRI) scans were performed on the lumbar spine and brain of the two groups of monkeys using the probe [11C]OMAR, which specifically targets CB1R, and the difference in the CB1R expression of osteoporotic monkeys was evaluated. The vBMD values of two standard deviations (SDs) below the peak bone value (428.1±53.8 g/cm3) were set as the reference standard for osteoporosis vBMD. Of the 49 healthy female cynomolgus monkeys, 4 postmenopausal older osteoporotic monkeys (18-26 years) and 5 young control monkeys (6-7 years) were selected, and the mean vBMD of the lumbar spine of the two groups was 295.07±19.11 and 419.72±16.14 g/cm3, respectively (P<0.0001). Radioactive uptake in the lumbar spine was linearly and negatively correlated with vBMD (r=-0.7977; P=0.01). Dynamic PET/MR imaging of the brains showed that CB1R was upregulated in the osteoporosis group, and there was a negative linear correlation between the vBMD and area under the time-radioactivity curve (AUC) of the thalamus (r=-0.8506; P=0.0153) and prefrontal cortex (r=-0.8306; P=0.0207). In this study, PET/CT-MRI molecular imaging technology revealed that CB1R was upregulated in the lumbar spine and brain of the osteoporosis monkeys and that CB1R may be regulated by the brain-bone axis. CB1R antagonist may be a potential drug for the treatment of osteoporosis.

The effect of hepatic steatosis on 18F-FDG uptake in PET-CT examinations of cancer Egyptian patients

BackgroundHepatic steatosis is the most common chronic hepatic disease. Imaging diagnosis of hepatic steatosis has been evaluated as an alternative to invasive histological diagnosis.Study aimsThe study aimed to assess the effect of hepatic steatosis on Flourine-18 fluorodeoxyglucose (18F-FDG) uptakes in cancer patients.Patients and MethodsBlood samples were collected from 50 cancer patients and analyzed to calculate fatty liver index and Hepatic steatosis index (HIS). Hepatic steatosis examined using high-resolution ultrasound and positron emission tomography—computed tomography (PET-CT). Linear attenuation coefficient, standardized-uptake value (SUV) mean (SUV mean), and SUV maximum (SUVmax) were measured. Accordingly, patients were divided equally into non-fatty liver, and fatty liver groups.ResultsA significant increase in SUVmax and SUV mean was observed in the fatty liver group more than in the non-fatty liver group. HSI significantly increased in the fatty liver group compared to the non-fatty liver group. Liver tissue uptake FDG was significantly correlated with HSI values. SUV max significantly correlated with body mass index (BMI) in the non-fatty group only.ConclusionHepatic changes in cancer patients affect the liver metabolic activity and thus the 18 F-FDG uptake. Therefore, further corrections should be considered when the liver is used as a comparator for PET-CT scans of cancer patients.

An unusual presentation of ossified spinal meningioma: case report and literature review.

Spinal meningioma is a common intraspinal tumor, which mainly occurs in the thoracic spine. Ossified meningioma (OSM) is an extremely rare histological variant. Our article reports a rare patient with dorsal complete OSM and reviews this subject. A 68-year-old woman presented with a one-year history of progressive weakness in both lower limbs with gait disturbance. Physical examination revealed hypoesthesia with a sensory level below T10. Babinski and pathological signs on both sides were weakly positive. Magnetic resonance imaging (MRI) showed a mass at the T10 to T11 level causing severe compression of the spinal cord. Computed tomography (CT) showed complete ossification of the mass. 18F-Fluoro-deoxy-glucose positron emission tomography CT (18F-FDG PET/CT) scan combined with MRI revealed that the mass was an intradural extramedullary high-density ossified nodule. The patient underwent a gross total resection of the mass and pathologic examination indicated that the mass was a meningioma with diffused psammomatous bodies. We identified a rare case of dorsal complete OSM occurring in a 68-year-old woman. After complete surgical resection, although there were complications such as cerebral fluid leakage and fever, the patient finally recovered with a satisfactory result.

Brain Death Confirmation by 18F-FDG PET/CT: A Case Series.

Brain death is a state of irreversible loss of brain function in the cortex and brainstem. Diagnosis of brain death is established by clinical assessments of cranial nerves and apnea tests. Different conditions can mimic brain death. In addition, confirmatory tests may be falsely positive in some cases. In this study, we aimed to evaluate the role of positron emission tomography-computed tomography scan with 2-deoxy-2[18F]fluoro-D-glucose (18F-FDG-PET/CT) as an ancillary test in diagnosing brain death. We analyzed 6 potential brain death donors for the confirmatory diagnosis of brain death using FDG-PET/CT. All 6 donors were brain dead by clinical criteria. All patients had electroencephalogram and brain computed tomography. Other than FDG-PET/CT, transcranial Doppler was performed in 1 patient, with other patients having no confirmatory ancillary imaging tests. Patients had nothing by mouth for 6 hours before imaging. Patients were supine in a semi-dark, noiseless, and odorless room with closed eyes. After 60 minutes of uptake,the brain PET/CT scan was performed with sequential time-of-flight-PET/CT (Discovery 690 PET/CT with 64 slices, GE Healthcare). The PET scan consisted of LYSO (Lu1.8Y0.2 SiO5) crystals with dimensions of 4.2 × 6.3 × 25 mm3. Three-dimension images were with scan duration of 10 minutes. The PET scan confirmed brain death in 5 of the 6 cases. However, we ruled out brain death using PET/CT in a 3-year-old child, although all clinical tests confirmed brain death. A PET scan illustrates a hollow skull phenomenon suggestive of brain death. It can be a powerful diagnostic tool to assess brain death.

Surgery for Rectal Cancer With Mixed Reality of 3D Model During Operation: A Case Report.

Recently, robotic surgery for rectal cancer has become a common minimally invasive surgery. In addition, the technology of augmented and mixed reality is applied in various living environments, including medicine. We successfully performed robotic surgery for rectal cancer with three-dimensional (3D) images as mixed reality (MR) using HoloLens2. The patient was diagnosed with rectal cancer by colonoscopy and a positron-emission computed-tomography scan, and we performed robot-assisted anterior resection. The operator used HoloLens2 and performed the surgery while visualizing 3D images of pelvic anatomy with the location of the rectal cancer as hologram. The operation was performed completely and safely, and she was discharged 11 days after surgery with no postoperative complications. This case presents the usefulness of a MR system offering organ visualization as hologram during surgery.

Dynamic 68Ga-DOTA0-Tyr3-octreotate positron emission tomography-computed tomography for the evaluation of pancreatic neuroendocrine tumors: a pilot study.

68Ga-DOTA0-Tyr3-octreotate (68Ga-DOTATATE) is a radiolabeled somatostatin analog used for the diagnosis of pancreatic neuroendocrine tumors (pNETs), and standardized uptake value (SUV) measurements for therapeutic monitoring is recommended. However, changes in net influx rate (Ki) may better reflect treatment effects than may those of the SUV. The aim of this study was to investigate the value of dynamic 68Ga-DOTATATE positron emission tomography-computed tomography (PET-CT) in the evaluation of pNETs. Dynamic PET-CT scans over 60 min were acquired for 7 patients with localized pancreatic mass before surgery. Maximal and mean SUV (SUVmax and SUVmean) were measured in tumors and normal pancreatic body as reference tissue (RT). Time-activity curves (TACs) were extracted from tumors and RT. A 2-tissue compartment model was used to calculate the rate constants K1, k2, and k3 (min-1); Ki (mL/g/min); and K1:k2 ratio. The following statistical tests were used to evaluate the results: the Shapiro-Wilk, Student t test, Mann-Whitney, Spearman, and Pearson rank correlation tests. Among 6 patients, 8 primary tumors were histopathologically proven to be pNETs. Moreover, 6 lesions with high uptake of 68Ga-DOTATATE showed an ascending TAC pattern, while 2 lesions with no or low uptake showed a descending TAC pattern. The mean SUVmax and SUVmean of pNETs were 46.4±40.2 (range, 3.9-109.9) and 21.9±16.0 (range, 0.5-42.8), respectively, which were significantly higher than the SUVmax of 4.2±0.6 (range, 3.1-4.9) and the SUVmean of 2.7±1.0 (range, 1.4-3.6) for the RT (P=0.021 and P=0.036), respectively. The Ki of pNETs was statistically higher than that of the RT [pNET: 0.366±0.372 (range, 0.019-0.992); RT: 0.060±0.017 (range, 0.04-0.08); P=0.036]. The mean K1:k2 ratio in pNETs was 12-fold higher than that of RT (6.06 vs. 0.50). In pNETs, there was a positive correlation between SUVmax and Ki (r=0.952; P<0.001) and between SUVmean and Ki (r=0.905; P=0.002). Another patient was diagnosed with intrapancreatic accessory spleen. The uptake of 68Ga-DOTATATE by pNETs can be explained by its high Ki value and K1:k2 ratio. Dynamic 68Ga-DOTATATE PET-CT can serve as a potential tool for evaluating pNETs and support the further assessment of a larger cohort of patients.

55 Outcomes of FDG PET-CT in Surveillance of Residual Nodal Metastases Following Non-Surgical Management of Head and Neck Squamous Cell Carcinoma: A Retrospective Review

Abstract Aim Assessing the role of positron emission tomography-computed tomography (PET-CT) surveillance in detecting residual disease in nodal metastasis, following non-surgical treatment of Head and neck squamous cell carcinoma (HNSCC), such as chemoradiotherapy or radical radiotherapy. To analyse differences in outcomes between HPV positive and HPV negative cancers. Method Retrospective analysis of 327 patients in South Wales, with histologically proven HNSCC was conducted. All patients were treated non-surgically and post-treatment PET-CT scans were obtained. Patients with PET-CT showing incomplete responses had further analysis of outcomes assessed via surgical histology of the nodes. Outcomes in patients with p16 positive disease were recorded to determine outcomes in HPV positive individuals. Results 64 individuals had residual nodal tumours according to PET-CT. 18 out of 43 patients had a negative histology for malignancy, of which 12 showed p16 positive disease. PET-CT showed a false positive in 41.8% of patients, with a positive predictive value of 58%. 225 patients in total were p16 positive, and 38 out of the 64 residual patients had p16 positive disease. There was no significant difference in outcomes between p16 positive and negative patients. Conclusions Our study concurs with similar literature, that primary CRT in N2 and N3 nodal metastasis followed by PET-CT surveillance minimises unnecessary neck dissections and triple modality treatment. Further research needs to be conducted however, to determine the efficacy of PET-CT surveillance compared to planned neck dissections. Furthermore, outcomes in p16 positive patients requires additional ongoing research to best determine surveillance techniques and long-term health outcomes.

Understanding the bacillary load and host interaction to design a point-of-care test to diagnose tuberculosis

Designing of a Point-of-care test to diagnose tuberculosis (TB) is not an easy task. This viewpoint stems from the dichotomous diagnostic approach, based on the bacillary load estimated in latent tuberculosis infection (LTBI), thanks to the isoniazid chemoprophylaxis strategy, as well as the importance of imaging to differentiate between LTBI and TB. It integrates the “TB spectrum” elucidated through positron emission tomography-computed tomography scan (PET-CT) to highlight the dynamic nature of TB lesions. Additionally, it emphasizes the relevance of animal models that support this perspective, including the drainage of bacilli through foamy macrophages, which aids in understanding LTBI and its chemoprophylaxis, and the significance of lung anatomy in TB induction. Especially the role of interlobular septa and the encapsulation process and its role in lung lobe predilection impact disease progression. Moreover, it acknowledges the gender bias in TB, as its incidence is significantly higher in men across various socioeconomic circumstances, suggesting an unidentified biological mechanism. For a comprehensive approach, the impact of stress and cortisol levels is suggested as a new parameter to be considered, given their association with poverty, and social inequity, and their tendency to be higher in men. All this information has to be contemplated when designing an accurate point-of-care test. The test should encompass the complexity of TB and necessarily integrate both bacillary and host response parameters. It also should cover the diagnosis of extrapulmonary TB, and pay attention to immunosuppressed and pediatric population.

Low-dose CT radiomics features-based neural networks predict lymphoma types

BackgroundFluorodeoxyglucose positron emission tomography (PET)–computed tomography (CT) is preferred for pretreatment staging and treatment planning in patients with lymphoma. This study aims to train and validate the neural networks (NN) for predicting lymphoma types using low-dose CT radiomics.ResultsFew radiomics features were stable in intraclass correlation coefficient and coefficient of variation analysis (n = 119). High collinear ones with variance inflation factor were eliminated (n = 56). Twenty-four features were selected with the least absolute shrinkage and selection operator regression for network training. NN had 75.76% predictive accuracy in the validation set and has 0.73 (95% CI 0.55–0.91) area under the curve (AUC) to differentiate Hodgkin lymphoma from non-Hodgkin lymphoma. NN which was used to differentiate B-cell lymphoma from T-cell lymphoma had 78.79% predictive accuracy and has 0.81 (95% CI 0.63–0.99) AUC.ConclusionsIn this study, in which we used low-dose CT images of PET–CT scans, predictions of the neural network were near acceptable lower bound for Hodgkin and non-Hodgkin lymphoma discrimination, and B-cell and T-cell lymphoma differentiation.

Detection of Axillary Lymph Node Involvement in Early-Stage Breast Cancer: Comparison between Staging 18F-2-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography-Computed Tomography Scans, Mammography, and Sentinel Lymph Node Biopsy.

The aim of this study was to evaluate the role of 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) scan in the detection of axillary lymph node (ALN) involvement and comparison with sentinel lymph node biopsy (SLNB) in operable early-stage breast cancer (EBC). It is a retrospective analysis of staging PET-CT scan of EBC. A total of 128 patients with histopathologically proven breast cancer (BC) were included in the study. Preoperative mammography supplemented with ultrasonography and staging 18F-FDG PET-CT scan was done for all patients. Surgery was done within 30 (mean ± standard deviation = 13.8 ± 10.5) days of staging. SLNB was performed in patients without PET-positive ALNs. All patients with positive sentinel nodes and PET-positive ALNs underwent axillary lymph node dissection (ALND). The comparison between categorical variables was made by Chi-square/Fisher's exact test as applicable. For continuous variables comparisons, Student's t-test and one-way analysis of variance tests were used. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET-CT scan for detection of ALN involvement were 41.7%, 93.2%, 92.1%, and 45.6%, respectively. Sensitivity, specificity, PPV, and NPV of mammography were 84.5%, 54.5%, 78.0%, and 68.6%, respectively. Sixteen out of 46 (34.7%) patients with negative ALNs in PET-CT scan finally showed involvement in histopathology report after SLNB resulting in upstage of the disease. The size of tumor deposits in sentinel nodes was significantly smaller than PET-positive ALNs (P = 0.01). Our observations correlate with the results of earlier studies published in the literature. 18F-FDG PET-CT scan cannot substitute SLNB for ALN screening in EBC. The limitations are most marked in smaller and micrometastatic tumor deposits in ALNs and may be attributed to limitations of PET resolution. However, PET-positive nodes showed good specificity for disease involvement in our study. Therefore, ALND can safely be performed by omitting SLNB in such cases.