PTPRH promotes the progression of non-small cell lung cancer via glycolysis mediated by the PI3K/AKT/mTOR signaling pathway.

BACKGROUND: The protein tyrosine phosphatase H receptor (PTPRH) is known to regulate the occurrence and development of pancreatic and colorectal cancer. However, its association with glycolysis in non-small cell lung cancer (NSCLC) is still unclear. In this study, we aimed to investigate the relationship between PTPRH expression and glucose metabolism and the underlying mechanism of action. METHODS: The expression of PTPRH in NSCLC cells was evaluated by IHC staining, qRT‒PCR and Western blotting. The effect of PTPRH on cell biological behavior was evaluated by colony assays, EdU experiments, Transwell assays, wound healing assays and flow cytometry. Changes in F-18-fluorodeoxyglucose (18F-FDG) uptake and glucose metabolite levels after altering PTPRH expression were detected via a gamma counter and lactic acid tests. The expression of glycolysis-related proteins in NSCLC cells was detected by Western blotting after altering PTPRH expression. RESULTS: The results showed that PTPRH was highly expressed in clinical patient tissue samples and closely related to tumor diameter and clinical stage. In addition, PTPRH expression was associated with glycometabolism indexes on 18F-FDG positron emission tomography/computed tomography (PET/CT) imaging, the expression level of Ki67 and the expression levels of glycolysis-related proteins. PTPRH altered cell behavior, inhibited apoptosis, and promoted 18F-FDG uptake, lactate production, and the expression of glycolysis-related proteins. In addition, PTPRH modulated the glycometabolism of NSCLC cells via the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway, as assessed using LY294002 and 740Y-P (an inhibitor and agonist of PI3K, respectively). The same results were validated in vivo using a xenograft tumor model in nude mice. Protein expression levels of PTPRH, glycolysis-related proteins, p-PI3K/PI3K and p-AKT/AKT were measured by IHC staining using a subcutaneous xenograft model in nude mice. CONCLUSIONS: In summary, we report that PTPRH promotes glycolysis, proliferation, migration, and invasion via the PI3K/AKT/mTOR signaling pathway in NSCLC and ultimately promotes tumor progression, which can be regulated by LY294002 and 740Y-P. These results suggest that PTPRH is a potential therapeutic target for NSCLC.

Intravenous regular insulin is an efficient and safe procedure for obtaining high-quality cardiac 18F-FDG PET images: an open-label, single-center, randomized controlled prospective trial.

BACKGROUND: An open-label, single-center, randomized controlled prospective trial was performed to assess the efficiency and safety of an insulin loading procedure to obtain high-quality cardiac 18F-FDG PET/CT images for patients with coronary artery disease (CAD). METHODS: Between November 22, 2018 and August 15, 2019, 60 patients with CAD scheduled for cardiac 18F-FDG PET/CT imaging in our department were randomly allocated in a 1:1 ratio to receive an insulin or standardized glucose loading procedure for cardiac 18F-FDG imaging. The primary outcome was the ratio of interpretable images (high-quality images defined as myocardium-to-liver ratios ≥ 1). The secondary outcome was the patient preparation time (time interval between administration of insulin/glucose and 18F-FDG injection). Hypoglycemia events were recorded. RESULTS: The ratio of interpretable cardiac PET images in the insulin loading group surpassed the glucose loading group (30/30 vs. 25/30, P = 0.026). Preparation time was 71±2 min shorter for the insulin loading group than for the glucose loading group (P < 0.01). Two and six hypoglycemia cases occurred in the insulin and glucose loading groups, respectively. CONCLUSION: The insulin loading protocol was a quicker, more efficient, and safer preparation for gaining high-quality cardiac 18F-FDG images.

Semi-automated histogram analysis of normal bone marrow using 18F-FDG PET/CT: correlation with clinical indicators.

BACKGROUND: 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly applied to the diagnosis of bone marrow failure such as myeloproliferative neoplasm, aplastic anemia, and myelodysplastic syndrome, as well as malignant lymphoma and multiple myeloma. However, few studies have shown a normal FDG uptake pattern. This study aimed to establish a standard of bone marrow FDG uptake by a reproducible quantitative method with fewer steps using deep learning-based organ segmentation. METHODS: Bone marrow PET images were obtained using segmented whole-spine and pelvic bone marrow cavity CT as mask images using a commercially available imaging workstation that implemented an automatic organ segmentation algorithm based on deep learning. The correlation between clinical indicators and quantitative PET parameters, including histogram features, was evaluated. RESULTS: A total of 98 healthy adults were analyzed. The volume of bone marrow PET extracted in men was significantly higher than that in women (p < 0.0001). Univariate and multivariate regression analyses showed that mean of standardized uptake value corrected by lean body mass (SULmean) and entropy in both men and women were inversely correlated with age (all p < 0.0001), and SULmax in women were also inversely correlated with age (p = 0.011). CONCLUSION: A normal FDG uptake pattern was demonstrated by simplified FDG PET/CT bone marrow quantification.

Predicting the Recurrence of Gastric Cancer Using the Textural Features of Perigastric Adipose Tissue on [18F]FDG PET/CT.

This study aimed to assess the relationship between the histopathological and textural features of perigastric adipose tissue (AT) on 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) and to evaluate the prognostic significance of perigastric AT textural features in predicting recurrence-free survival (RFS) in patients with gastric cancer. Sixty-nine patients with gastric cancer who underwent staging [18F]FDG PET/CT and subsequent curative surgery were retrospectively reviewed. Textural features of perigastric AT were extracted from PET images. On histopathological analysis, CD4, CD8, and CD163 cell infiltration and matrix metalloproteinase-11 and interleukin-6 (IL-6) expression in perigastric AT were graded. The degree of CD163 cell infiltration in perigastric AT was significantly correlated with the mean standardized uptake value (SUV), SUV histogram entropy, grey-level co-occurrence matrix (GLCM) energy, and GLCM entropy of perigastric AT. The degree of IL-6 expression in the perigastric AT was significantly correlated with the mean and median SUVs of perigastric AT. In multivariate survival analysis, GLCM entropy, GLCM dissimilarity, and GLCM homogeneity of perigastric AT were significant predictors of RFS. The textural features of perigastric AT on [18F]FDG PET/CT significantly correlated with inflammatory response in perigastric AT and were significant prognostic factors for predicting RFS in patients with gastric cancer.

"Superscan" on F18­fluorodeoxyglucose Positron Emission Tomography - Computed Tomography [18­F] FDG PET-CT.

"Superscan" features have been described in 18F FDG PET-CT (F18 fluorodeoxyglucose Positron Emission Tomography­Computed Tomography) scan; characterized by significantly increased uptake in one or more organ systems resulting in absent or decreased uptake in the organs which normally show physiological uptake. The importance of the awareness has evolved over the years in order to avoid false interpretation of scan findings as well as in determination of a high tumour burden. We present images of three patients who underwent 18F FDG PET-CT scan showing findings consistent with FDG PET-CT superscan.

Evaluation of brain FDG PET images in temporal lobe epilepsy for lateralization of epileptogenic focus using data mining methods

Background/aim: In temporal lobe epilepsy (TLE), brain positron emission tomography (PET) performed with F-18 fluorodeoxyglucose (FDG) is commonly used for lateralization of the epileptogenic temporal lobe. In this study, we aimed to evaluate the success of quantitative analysis of brain FDG PET images using data mining methods in the lateralization of the epileptogenic temporal lobe. Materials and methods: Presurgical interictal brain FDG PET images of 49 adult mesial TLE patients with a minimum of 2 years of postsurgical follow-up and Engel I outcomes were retrospectively analyzed. Asymmetry indices were calculated from PET images from the mesial temporal lobe and its contiguous structures. The J48 and the logistic model tree (LMT) data mining algorithms were used to find classification rules for the lateralization of the epileptogenic temporal lobe. The classification results obtained by these rules were compared with the physicians' visual readings and the findings of single-patient statistical parametric mapping (SPM) analyses in a test set of 18 patients. An additional 5-fold cross-validation was applied to the data to overcome the limitation of a relatively small sample size. Results: In the lateralization of 18 patients in the test set, J48 and LMT methods were successful in 16 (89%) and 17 (94%) patients, respectively. The visual consensus readings were correct in all patients and SPM results were correct in 16 patients. The 5-fold cross- validation method resulted in a mean correct lateralization ratio of 96% (47/49) for the LMT algorithm. This ratio was 88% (43 / 49) for the J48 algorithm. Conclusion: Lateralization of the epileptogenic temporal lobe with data mining methods using regional metabolic asymmetry values obtained from interictal brain FDG PET images in mesial TLE patients is highly accurate. The application of data mining can contribute to the reader in the process of visual evaluation of FDG PET images of the brain.

F-18 FDG PET for assessment of disease activity of large vessel vasculitis: A systematic review and meta-analysis.

BACKGROUND: The aim of this study is to investigate the performance of F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) or positron emission tomography/computed tomography (PET/CT) for the assessment of disease activity in patients with large vessel vasculitis (LVV) through a meta-analysis. METHODS: The MEDLINE via PubMed and EMBASE were searched for the studies evaluating the performance of F-18 FDG PET or PET/CT in the assessment of disease activity in patients with LVV. Pooled sensitivity, specificity, diagnostic odds ratios (DORs), and summary receiver-operating characteristic (sROC) curve were estimated across the included studies. Possible publication bias was assessed by Deek's funnel plot asymmetry tests. RESULTS: A total of 439 PET images from 298 patients pooled from nine studies showed that the pooled sensitivity was 0.88 [95% confidence interval (CI) 0.79-0.93] without heterogeneity (χ2 = 14.42, P = .07) and the pooled specificity was 0.81 (95% CI 0.64-0.91) with heterogeneity (χ2 = 63.72, P = .00) for the detection of active LVV. The pooled DOR was 30 (95% CI 8-107). Hierarchical sROC curve indicates that the area under the curve was 0.91 (95% CI 0.89-0.94). There was no significant publication bias (P = .42), and meta-regression analysis revealed that none of the variables was the source of the study heterogeneity. CONCLUSIONS: F-18 FDG PET has a good performance for the detection of active disease status in patients with LVV. Revised criteria for the assessment of disease activity incorporated with F-18 FDG PET or PET/CT should be introduced and validated. Further studies are warranted to determine if PET-based treatment of LVV can improve outcomes.

Advanced cardiovascular imaging for the evaluation of cardiac sarcoidosis.

Cardiac sarcoidosis (CS) remains an intriguing infiltrating disorder and one of the most important forms of inflammatory cardiomyopathy. Identification of patients with CS is of extreme importance because they are at higher risk of sudden death, and heart-failure progression. And while it remains a diagnostic conundrum, a great amount of experience has been accumulated over the last decade with the advent of fluorine-18 fluorodeoxyglucose positron emission tomography and cardiac magnetic resonance with late gadolinium enhancement imaging. They have both proven to be advanced imaging techniques that provide important, and often complementary, diagnostic and prognostic information for the management of CS. However, they have also shown to have limitations, and, thus, there is a continued need for developing more specific imaging probes for identifying cardiac inflammation. The aim of the present manuscript is to provide the reader with a better understanding of the histopathology of the disease, how this potentially relates to noninvasive imaging detection, and the best strategies available for the diagnosis and management of patients with CS.

Diagnostic Accuracy of F-18 FDG PET/CT for Preoperative Lymph Node Staging in Newly Diagnosed Bladder Cancer Patients: A Systematic Review and Meta-Analysis.

AIMS: We aimed to assess the diagnostic accuracy of F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for preoperative lymph node (LN) staging in newly diagnosed bladder cancer (BC) patients through a systematic review and meta-analysis. PATIENTS AND METHODS: MEDLINE, Embase, and the Cochrane Library database, from the earliest available date of indexing through June 30, 2017, were searched for studies evaluating the diagnostic performance of F-18 FDG PET/CT for preoperative LN staging in newly diagnosed BC. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves. RESULTS: Across 14 studies (785 patients), the pooled sensitivity was 0.57 (95% CI: 0.49-0.64) and the pooled specificity was 0.92 (95% CI: 0.87-0.95). The LR syntheses gave an overall LR+ of 7.4 (95% CI: 4.4-12.3) and an LR- of 0.47 (95% CI: 0.39-0.56). The pooled diagnostic odds ratio was 16 (95% CI: 9-28). CONCLUSIONS: F-18 FDG PET/CT shows a low sensitivity and high specificity for the detection of metastatic LNs in patients with newly diagnosed BC.

A surgical strategy using a fusion image constructed from 11C-methionine PET, 18F-FDG-PET and MRI for glioma with no or minimum contrast enhancement.

The objective of this study was to investigate the distribution of 11C-methionine (MET) and F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) imaging and the hyperintense area in T2 weighted imaging (T2WI) in glioma with no or poor gadolinium enhancement in magnetic resonance imaging (GdMRI). Cases were also analyzed pathologically. We prospectively investigated 16 patients with non- or minimally enhancing (< 10% volume) glioma. All patients underwent MET-PET and FDG-PET scans preoperatively. After delineating the tumor based on MET uptake, integrated 3D images from FDG-PET and MRI (GdMRI, T2WI or FLAIR) were generated and the final resection plane was planned. This resection plane was determined intraoperatively using the navigation-guided fencepost method. The delineation obtained by MET-PET imaging was larger than that with GdMRI in all cases with an enhanced effect. In contrast, the T2WI-abnormal signal area (T2WI+) tended to be larger than the MET uptake area (MET+). Tumor resection was > 95% in the non-eloquent area in 4/5 cases (80%), whereas 10 of 11 cases (90.9%) had partial resection in the eloquent area. In a case including the language area, 92% resection was achieved based on the MET-uptake area, in contrast to T2WI-based partial resection (65%), because the T2WI+/MET- area defined the language area. Pathological findings showed that the T2WI+/MET+ area is glioma, whereas 6 of 9 T2WI+/MET- lesions included normal tissues. Tissue from T2W1+/MET+/FDG+/GdMRI+ lesions gave an accurate diagnosis of grade in six cases. Non- or minimally enhancing gliomas were classified as having a MET uptake area that totally or partially overlapped with the T2WI hyperintense area. Resection planning with or without a metabolically active area in non- or minimally enhancing gliomas may be useful for accurate diagnosis, malignancy grading, and particularly for eloquent area although further study is needed to analyze the T2WI+/MET- area.

Neuroimaging in Parkinsonian Disorders.

Neuroimaging (NI) in Parkinson's disease (PD) includes functional techniques like positron emission tomography (PET) and single photon emission computed tomography (SPECT), and morphological imaging using magnetic resonance imaging (MRI) and transcranial sonography to probe different aspects of the neurobiology of PD. Changes in neurotransmitters in various regions of the brain and their influence on brain networks is the basis for the motor symptoms of PD which are interrogated by NI. The recent Movement Disorders Society Clinical Diagnostic Criteria for PD (MDS-PD) have included the results of a few of these neuroimaging techniques to serve as single supportive criteria or absolute exclusion criteria for the diagnosis of PD. While dopaminergic imaging is useful in the early stages of disease to differentiate the neurodegenerative versus non-degenerative causes of parkinsonism like essential tremors, it has also been used for the differential diagnosis of dementia with Lewy bodies (DLB) from Alzheimer's disease (AD), for inclusion of PD patients into clinical trials and for evaluating response to cell-replacement therapies in PD. Metabolic patterns on F-18 fluorodeoxyglucose positron emission tomography have been used effectively for the classification and differential diagnosis of the parkinsonian syndromes using visual and quantitative approaches. Disease related network-patterns have been used for a completely automated approach to differential diagnosis of parkinsonian syndromes on a single case basis. Structural MRI and advanced MR techniques have been used for the classification of PD and the atypical parkinsonian syndromes. Thus, multimodal imaging in PD may aid in an early, accurate and objective diagnostic classification by highlighting the underlying neurochemical and neuroanatomical changes that underlie this spectrum of disorders. The present challenge in PD is to develop radioligands which could bind selectively to alphasynuclein in-vivo.

F-18 sodium fluoride PET/CT does not effectively image myocardial inflammation due to suspected cardiac sarcoidosis.

BACKGROUND: Sarcoidosis is an inflammatory disorder of unknown etiology that can involve the heart. While effective in imaging cardiac sarcoidosis, F-18 fluorodeoxyglucose (FDG) PET/CT often shows non-specific myocardial uptake. F-18 sodium fluoride (NaF) has been used to image inflammation in coronary artery plaques and has low background myocardial uptake. Here, we evaluated whether F-18 NaF can image myocardial inflammation due to clinically suspected cardiac sarcoidosis. PATIENTS AND METHODS: We performed a single institution pilot study testing if F-18 NaF PET/CT can detect myocardial inflammation in patients with suspected cardiac sarcoidosis. Patients underwent cardiac PET/CT with F-18 FDG as part of their routine care and subsequently received an F-18 NaF PET/CT scan. RESULTS: Three patients underwent F-18 FDG and F-18 NaF imaging. In all patients, there was F-18 FDG uptake consistent with cardiac sarcoidosis. The F-18 NaF PET/CT scans showed no myocardial uptake. CONCLUSIONS: In this small preliminary study, PET/CT scan using F-18 NaF does not appear to detect myocardial inflammation caused by suspected cardiac sarcoidosis.

Thalamic abnormalities in children with continuous spike-wave during slow-wave sleep: An F-18-fluorodeoxyglucose positron emission tomography perspective.

OBJECTIVE: Thalamic injury has been implicated in the development of continuous spike-wave during slow-wave sleep (CSWS) in children with epilepsy. We studied thalamic abnormalities in children with CSWS using F-18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) imaging. METHODS: Twenty-three patients (12 male; mean age 9 years) with CSWS and normal thalami on brain magnetic resonance imaging (MRI) underwent FDG-PET. Thalamic glucose metabolism, represented by standardized uptake value normalized to whole brain (nSUV, RT for right thalamus and LT for left thalamus), and its asymmetry--absolute asymmetry index (AAI): ¦(RT-LT)¦*100/[(RT+LT)/2]--was calculated. These values were compared with those from 10 normal healthy controls (five female; mean age 11.1 years). RESULTS: Thalamic glucose metabolism was abnormal in 18 patients (78.3%). Thalamic nSUV was decreased (n = 6) or increased (n = 1) bilaterally in seven children without any asymmetry. Abnormal thalamic symmetry [AAI = 3.7-31.5% (0.8-3.3% in controls)] was seen in 11 children. Of these, six children had a unilateral thalamic metabolic abnormality (increased metabolism, n = 3 and decreased metabolism, n = 3), whereas 5 of 14 children had abnormal asymmetry index with bilaterally normal (n = 4) or increased (n = 1) thalamic metabolism. No clear association of thalamic metabolic abnormalities was seen with the stage of evolution of CSWS (prodromal, acute, or residual) or with the cortical FDG abnormalities. SIGNIFICANCE: Functional thalamic abnormalities, both unilateral and bilateral, are frequently seen in patients with CSWS. FDG-PET is a sensitive and quantifiable modality to detect these changes.

Clinical significance of post-treatment 18F-fluorodeoxyglucose uptake in cervical lymph nodes in patients with diffuse large B-cell lymphoma.

OBJECTIVES: We assessed the clinical significance of FDG uptake in cervical lymph nodes after treatment of patients with DLBCL. METHODS: In total, 87 patients with DLBCL were enrolled. All patients had newly appeared FDG uptake in cervical lymph nodes on PET/CT during follow-up after cessation of therapy. Cervical lymph nodes were finally diagnosed as benign or malignant according to histopathological findings or follow-up PET. Clinical characteristics and PET findings were compared between groups and factors associated with malignant lesions were evaluated. RESULTS: Only 8 (9.2 %) patients with cervical lymph nodes with FDG uptake ultimately had malignancy. FDG uptake lymph nodes appeared significantly earlier in the malignant group than in patients with benign FDG uptake (p = 0.013). Primary nodal lymphoma was more frequent in patients with cancer spread than in those with benign FDG uptake in lymph nodes (p < 0.001). CONCLUSION: Most cervical lymph nodes with FDG uptake (about 91 %) appearing after treatment of malignant DLBCL were ultimately benign. The elapsed time between the end of therapy and the appearance of cervical lymph nodes with FDG uptake and the primary sites of lymphomas are helpful clues in determining which cases are malignant. KEY POINTS: • About 91 % appearing after treatment of DLBCL were benign. • Elapsed time between therapy and FDG uptake was associated with malignancy. • Primary sites of lymphoma are helpful clues to determine malignancy.

FDG-PET parameters predicting mediastinal malignancy in lung cancer.

BACKGROUND: Staging of mediastinal lymph nodes in non-small cell lung cancer (NSCLC) is mandatory. The maximum Standard Uptake Value (SUVmax) obtained using F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is the best non-invasive technique available for this evaluation, but its performance varies from center to center. The aim of the present study was to identify FDG-PET predictors of mediastinal malignancy that are able to minimize intercenter variability and improve the selection of subsequent staging procedures. METHOD: A multicenter study of NSCLC patients staged through FDG-PET and endobronchial ultrasonography with needle aspiration (EBUS-NA) was performed using therapeutic surgery with systematic nodal dissection as gold standard. Intercenter variability and predictive power for mediastinal malignancy of different FDG-PET measures were assessed, as well as the role of these measures for selecting additional staging procedures. RESULTS: One hundred and twenty-one NSCLC patients, of whom 94 (72%) had ≥1 hypermetabolic spots in the mediastinum, were included in the study. Mean SUVmax of the primary tumor was 12.3 (SD 6.3), and median SUVmax of the highest hypermetabolic spots in the mediastinum was 3.9 (IQR 2.4-7). Variability of FDG-PET measures between hospitals was statistically significant (p = 0.016 and p < 0.001 respectively), but lost significance when SUVmax in the mediastinum was expressed as a ratio or a subtraction from the primary tumor (SUVmax mediastinum/tumor, p = 0.083; and SUVmax mediastinum - tumor, p = 0.428 respectively). SUVmax mediastinum/tumor showed higher accuracy in the ROC analysis (AUC 0.77 CI 0.68-0.85, p < 0.001), and showed predictive power for mediastinal malignancy when using a 0.4 cutoff (OR 6.62, 95%CI 2.98-14.69). Sensitivities and negative predictive values of clinical staging through EBUS-NA attained values ranging between 57% and 92% after FDG-PET, which improved with additional techniques when the tumor had a diameter >3 cm and/or a SUVmax mediastinum/tumor ratio >0.4. CONCLUSION: The SUVmax mediastinum/tumor ratio is a good predictor of regional tumor extension in NSCLC. This measure is not influenced by intercenter variability and has an accuracy of over 70% for the identification of malignancy when using a 0.4 cutoff.

Prognostic significance of metabolic tumor burden by positron emission tomography/computed tomography in patients with relapsed/refractory diffuse large B-cell lymphoma.

The aim of the present study was to investigate the feasibility of measuring metabolic tumor burden using [F-18] fluorodeoxyglucose ((18) F-FDG) positron emission tomography/computed tomography (PET/CT) in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) treated with bendamustine-rituximab. Because the standardized uptake value is a critical parameter of tumor characterization, we carried out a phantom study of (18) F-FDG PET/CT to ensure quality control for 28 machines in the 24 institutions (Japan, 17 institutions; Korea, 7 institutions) participating in our clinical study. Fifty-five patients with relapsed or refractory DLBCL were enrolled. The (18) F-FDG PET/CT was acquired before treatment, after two cycles, and after the last treatment cycle. Treatment response was assessed after two cycles and after the last cycle using the Lugano classification. Using this classification, remission was complete in 15 patients (27%) and incomplete in 40 patients (73%) after two cycles of therapy, and remission was complete in 32 patients (58%) and incomplete in 23 patients (42%) after the last treatment cycle. The percentage change in all PET/CT parameters except for the area under the curve of the cumulative standardized uptake value-volume histogram was significantly greater in complete response patients than in non-complete response patients after two cycles and the last cycle. The Cox proportional hazard model and best subset selection method revealed that the percentage change of the sum of total lesion glycolysis after the last cycle (relative risk, 5.24; P = 0.003) was an independent predictor of progression-free survival. The percent change of sum of total lesion glycolysis, calculated from PET/CT, can be used to quantify the response to treatment and can predict progression-free survival after the last treatment cycle in patients with relapsed or refractory DLBCL treated with bendamustine-rituximab.

Isolated thymic Langerhans cell histiocytosis discovered on F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT).

The thymic infiltration in young patients with multisystemic Langerhans cell histiocytosis and its radiologic features are well known. However, isolated thymic disease has seldom been reported in the literature. We report the case of a 10-month-old child admitted for fever of unknown origin. Whole-body F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) was performed to identify a focus of infection. It demonstrated an unusual aspect of the thymus, which led to further investigation and revealed isolated infiltration of the thymus by Langerhans cell histiocytosis. The patient was treated accordingly and is now disease free. As evaluation of Langerhans cell histiocytosis patients with F-18 FDG PET/CT is becoming more frequent, it is important to be aware of the scintigraphical characteristics of thymic Langerhans cell histiocytosis.

Positron Emission Tomography Computed Tomography: A Guide for the General Radiologist.

Cancer remains a leading cause of death in Canada and worldwide. Whilst advances in anatomical imaging to detect and monitor malignant disease have continued over the last few decades, limitations remain. Functional imaging, such as positron emission tomography (PET), has improved the sensitivity and specificity in detecting malignant disease. In combination with computed tomography (CT), PET is now commonly used in the oncology setting and is an integral part of many cancer patients' pathways. Although initially the CT component of the study was purely for attenuation of the PET imaging and to provide anatomical coregistration, many centers now combine the PET study with a diagnostic quality contrast enhanced CT to provide one stop staging, thus refining the patient's pathway. The commonest tracer used in everyday practice is FDG (F18-fluorodeoxyglucose). There are many more tracers in routine clinical practice and those with emerging roles, such as 11C-choline, useful in the imaging of prostate cancer; 11C-methionine, useful in imaging brain tumours; C11-acetate, used in imaging hepatocellular carcinomas; 18F-FLT, which can be used as a marker of cellular proliferation in various malignancies; and F18-DOPA and various 68Ga-somatostatin analogues, used in patients with neuroendocrine tumours. In this article we concentrate on FDG PETCT as this is the most commonly available and widely utilised tracer now used to routinely stage a number of cancers. PETCT alters the stage in approximately one-third of patients compared to anatomical imaging alone. Increasingly, PETCT is being used to assess early metabolic response to treatment. Metabolic response can be seen much earlier than a change in the size/volume of the disease which is measured by standard CT imaging. This can aid treatment decisions in both in terms of modifying therapy and in addition to providing important prognostic information. Furthermore, it is helpful in patients with distorted anatomy from surgery or radiotherapy when there is suspicion of recurrent or residual disease. FDG PETCT is not specific for malignancy and can also be used for diagnosing and monitoring a number of inflammatory and infectious conditions that can be difficult to diagnose on anatomical imaging, some of which carry significant morbidity. FDG PETCT is increasingly used in patients with pyrexia of unknown origin and in patients with metastatic malignancies of unidentified primary on conventional imaging. This article reviews the uses of PETCT including an overview of the more common incidental lesions and conditions. It also provides guidance of how to approach a PETCT as a nonradionuclide radiologist and how to interpret a study in the multidisciplinary team setting.

Tuberculous scar tumour detected by dual tracer positron emission-computerised tomography in a tuberculous endemic area.

Tuberculous scar tumour is difficult to diagnose as it does not present with any respiratory symptoms and has a negative chest X-ray. This is a case report on the use of dual tracer 11C-acetate and 18F-fluorodeoxyglucose (18FDG) whole body positron emission tomography-computerised tomography (PET-CT) for detection of tuberculous scar tumour. A 44-year-old Chinese female was incidentally found to have a raised serum Ca 19.9. Magnetic resonance imaging of the whole abdomen, upper endoscopy, and colonoscopy were all unremarkable. A low-dose computed tomography (CT) of the thorax showed bilateral upper lobe fibrosis. Bronchoalveolar lavage for culture and cytology was negative. A dual tracer 11C-acetate and 18FDG whole body PET-CT showed that the left upper lobe fibrosis was hypermetabolic in nature. It was more avid for 11C-acetate than for 18FDG. The left upper lobe lesion was subsequently confirmed on open lung biopsy to be a moderately differentiated adenocarcinoma. Therefore, in a tuberculous endemic region, dual tracer whole body PET-CT with 11C-acetate and 18FDG may have a role in the early detection of tuberculous scar tumour in the lung.

Relationship of FDG PET/CT imaging features with tumor immune microenvironment and prognosis in colorectal cancer: a retrospective study.

BACKGROUND: Imaging features of colorectal cancers on 2-deoxy-2-[18F]fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT) have been considered to be affected by tumor characteristics and tumor immune microenvironment. However, the relationship between PET/CT imaging features and immune reactions in tumor tissue has not yet been fully evaluated. This study investigated the association of FDG PET/CT imaging features in the tumor, bone marrow, and spleen with immunohistochemical results of cancer tissue and recurrence-free survival (RFS) in patients with colorectal cancer. METHODS: A total of 119 patients with colorectal cancer who underwent FDG PET/CT for staging work-up and received curative surgical resection were retrospectively enrolled. From PET/CT images, 10 first-order imaging features of primary tumors, including intensity of FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity parameters, as well as FDG uptake in the bone marrow and spleen were measured. The degrees of CD4+, CD8+, and CD163 + cell infiltration and interleukin-6 (IL-6) and matrix metalloproteinase-11 (MMP-11) expression were graded through immunohistochemical analysis of surgical specimens. The relationship between FDG PET/CT imaging features and immunohistochemical results was assessed, and prognostic significance of PET/CT imaging features in predicting RFS was evaluated. RESULTS: Correlation analysis with immunohistochemistry findings showed that the degrees of CD4 + and CD163 + cell infiltration and IL-6 and MMP-11 expression were correlated with cancer imaging features on PET/CT. Patients with enhanced inflammatory response in cancer tissue demonstrated increased FDG uptake, volumetric metabolic parameters, and metabolic heterogeneity. FDG uptake in the bone marrow and spleen was positively correlated with the degree of CD163 + cell infiltration and IL-6 expression, respectively. In multivariate survival analysis, the coefficient of variation of FDG uptake in the tumor (p = 0.019; hazard ratio, 0.484 for 0.10 increase) and spleen-to-liver uptake ratio (p = 0.020; hazard ratio, 24.901 for 1.0 increase) were significant independent predictors of RFS. CONCLUSIONS: The metabolic heterogeneity of tumors and FDG uptake in the spleen were correlated with tumor immune microenvironment and showed prognostic significance in predicting RFS in patients with colorectal cancer.