F-18 Flurodeoxyglucose Research Articles

Positron Emission Tomography-Based Immunoimaging for Cancer Patient Stratification: Toward a More Holistic Approach

Immunotherapy with immune checkpoint inhibitors (ICIs) changed the treatment management in several solid metastatic tumors with very poor prognosis, in particular in melanoma stage IV since its introduction in 2011. However, it is not yet fully understood why some patients respond to ICIs and others not, and it is also unclear why melanomas are the most sensitive tumors to ICI treatment. Selection criteria for patient stratification are needed and several approaches are under evaluation. These include the PD-L1 expression in the tumor samples, assessment of the tumor mutational burden as well as radiological and molecular imaging techniques, such as positron emission tomography (PET)-CT and PET-MRI with F-18-flurodeoxyglucose (FDG) or novel radiopharmaceuticals. In the near future, a more holistic approach based on the combination of imaging data and sequencing data and the development of radiogenomic signatures will be needed for a better characterization of immunotherapy response and selection of patients who will benefit from ICI therapy alone or in combination with chemotherapy.

Prognostic significance of standardized uptake value on F18-FDG PET/CT in patients with extranodal nasal type NK/T cell lymphoma: A multicenter, retrospective analysis

ObjectivesThe purpose of this study was to evaluate the value of parameters assessed with F18-flurodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in predicting relapse free survival and overall survival in patients with extranodal nasal type NK/T cell lymphoma. MethodsThirty-six patients with extranodal nasal type NK/T cell lymphoma, and who underwent PET/CT prior to curative treatment, were enrolled at five institutions. Volumes of interest covering the entire tumor volume were delineated on PET/CT images, and the maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured using thresholds of 40% of SUVmax. Furthermore, we compared the difference in F18-FDG avidity according to Epstein-Barr virus (EBV) infection status. ResultsThe SUVmax (p=0.041) and SUVmean (p=0.049) in patients who died were higher than the respective values of those who survived. A higher TLG (>45.8) was associated with relapse free survival (HR 7.856, p=0.034). Ann Arbor stage (III–IV, HR 14.12, p=0.004), and a higher SUVmax (>12.6, p=0.024) and SUVmean (>6.4, p=0.024) were associated with poor survival. However, neither the MTV nor the TLG (volumetric parameters) were significant predictors of death. The PET parameters SUVmax (p=0.181), SUVmean (p=0.237), MTV (p=0.636), and TLG (p=0.469) did not differ significantly between patients with and without EBV infections. ConclusionsHigh TLG was the only significant predictive factor on relapse free survival. The SUVmax and SUVmean measured by F18-FDG PET/CT could be significant prognostic factors in patients with extranodal nasal type NK/T cell lymphoma.

Inferior Vena Cava Tumour Thrombus from Nonseminomatous Germ Cell Tumour Detected with F-18 FDG PET/CT

21-year-old male presented with recently diagnosed metastatic nonseminomatous germ cell tumour and left orchidectomy. CT demonstrated mixed density in the inferior vena cava (IVC) extending from the union of the common iliac veins to the level of the liver just below the confluence of the hepatic veins. Retroperitoneal nodal disease and deposits in the left lung were suspicious for metastatic deposits. F-18Flurodeoxyglucose (FDG) PET/CT images demonstrated avid FDG uptake within the lumen of the IVC from the level of the renal veins, with extension into both renal veins, to the level of T10. While benign and malignant thrombi have previously been demonstrated on F18-FDG PET imaging, this case highlights the use of F-18 FDG PET/CT when identifying tumour thrombosis in patients with nonseminomatous germ cell tumour.

Positron‐emission tomography pitfalls related to oral prosthesis

This case report describes false-positive positron-emission tomography/computed tomography (PET/CT) findings related to oral prostheses and its implications in cancer surveillance. In head and neck cancer management, F18-flurodeoxyglucose (FDG) PET/CT is widely accepted for evaluating treatment response and detecting recurrence. Interpretation of FDG PET/CT images in this setting is often challenging due to various prostheses and reconstruction methods. Following surgery for squamous cell carcinoma of the maxillary alveolus, a 61-year-old female had a FDG PET/CT scan on a 7-month follow-up that showed high FDG uptake along the resection site. Clinical examination showed no signs of inflammation or recurrence. Repeat FDG PET/CT without the prosthesis was normal. The PET/CT attenuation-corrected images demonstrated high FDG uptake (standardized uptake value: 11.6) along the resection site corresponding to contrast-enhanced CT images of the lesion. PET/CT nonattenuation-corrected images also confirmed increased activity. Repeat PET/CT without the prosthesis was normal. FDG is not tumor specific; it can accumulate in inflammation, infection, and post-therapy settings. Metallic and high-density prostheses show radial artifacts on CT and falsely elevated FDG uptake on PET/ CT in adjacent areas. Salivary pooling may concentrate FDG. The presence of oral prostheses has not been described as a cause of this high level of activity. PET/CT images that demonstrate intense activity corresponding to dense structures should be viewed with caution. A detailed history and physical exam as well as knowledge of artifacts are pertinent for the managing physician. Laryngoscope, 2012.

Factors Associated with Positive F-18 Flurodeoxyglucose Positron Emission Tomography Before Thyroidectomy in Patients with Papillary Thyroid Carcinoma

The role for pre-thyroidectomy (pre-Tx) imaging with F-18 flurodeoxyglucose (FDG) positron emission tomography (PET), FDG PET-computed tomography (CT), in differentiated thyroid cancer is controversial as is the significance of positive and negative FDG uptake in this setting. We reviewed the records of patients with papillary thyroid carcinoma (PTC) who had pre-Tx FDG PET-CT to determine whether FDG uptake was associated with features noted on pre-Tx ultrasonography (US) and parameters determined after post-Tx. Patients were selected for a retrospective review of their records if they had a total Tx with central lymph node dissection for PTC and pre-Tx FDG PET-CT and US between 2006 and 2009. Sixty patients who met these criteria were studied. Patients who had a history of head and neck irradiation, surgery, or sclerotherapy with ethanol in the last 3 months were excluded. The clinicopathologic factors-age, sex, size, tumor-node-metastasis (TNM) staging, the presence of extrathyroidal extention, multifocality, cervical lymph node metastases (CLNM), Hashimoto thyroiditis, and US characteristics-were evaluated to determine whether they were associated with positive pre-Tx FDG uptake. Forty-three (71.6%) of patients in the study had positive FDG uptake. Larger tumors and the presence of CLNM were associated with a greater likelihood of positive FDG uptake. The sensitivity, specificity, positive predictive value, and negative predictive value for CLNM detection by FDG PET-CT showed low statistical values. When considering the excellence of US for evaluating a thyroid nodule size and the presence of CLNM, the clinical value of pre-Tx FDG PET-CT is comparatively limited. Pre-Tx FDG PET is not recommended for routine use in patients with PTC.

Comparison of F-18 FDG and C-11 Methionine PET/CT for the Evaluation of Recurrent Primary Brain Tumors

With the availability of multiple positron emission tomography (PET) tracers for neurooncology, there is a need to define the appropriate tracer in a given clinical setting, and it is in this regard that we undertook this study to directly compare F-18 flurodeoxyglucose (FDG) PET and C-11 methionine (MET) PET for the evaluation of recurrence in primary brain tumors. Thirty-seven patients with a history of treated primary brain tumors referred for evaluation of recurrent disease were initially included in the study. Two patients had to be excluded because of insufficient follow-up. There were 23 males and 12 females, mean age: 33.7 ± 16.4 years; range: 5 to 65 years. All patients underwent the MET and FDG study on the same day. Visual image interpretation was performed independently by 2 PET physicians for each tracer using the plain PET and fused PET/CT images; the FDG images were evaluated first. Images were analyzed semiquantitatively using tumor to normal contralateral cortex ratios (T/N). Each patient was followed up for a minimum of 18 months. Imaging results were compared with histopathology on tumor excision or biopsy in 14 patients and with clinical follow-up and MRI/MRS at the end of 18 months in 21 patients. The final diagnosis was tumor recurrence in 24 patients and no recurrence/stable disease in 11 patients. On FDG, findings in 15/35 (42%) were suggestive of recurrent tumors. On MET, findings in 24/34 (70.5%) cases were suggestive of recurrent tumors. Spatially separated secondary lesions including intraventricular deposits were clearly delineated in 5 cases, 3 were glioblastoma multiforme (GBM) and 2 were anaplastic astrocytomas. One of the secondary lesions was missed on FDG PET. Using a cutoff for T/N ratio on FDG of >0.75 to differentiate recurrence from no recurrence, sensitivity of FDG was 81.2% (confidence interval [CI] = 54.4%-96%), whereas specificity was 88.9% (CI = 51.8%-99.7%). Area under the curve was 0.819 (CI = 0.615-0.943), P = 0.0003. Using a cutoff for T/N ratio of >1.9 to differentiate recurrence from no recurrence, sensitivity of MET was 94.7% (CI = 74.0%-99.9%), whereas specificity was 88.89% (CI = 51.8%-99.7%). Area under the curve was 0.942 (CI = 0.785-0.995), P < 0.0001. Interobserver agreement, κ coefficient, for MET was 0.93, suggesting good interobserver agreement, whereas for FDG, it was fair (0.23). MET should be the radiotracer of choice in the evaluation of recurrence of primary brain tumors because the sensitivity for detection and delineation of the possible recurrent tumor, as well as secondary deposits, is higher with MET. MET-PET is an easier technique to interpret, irrespective of the glioma grade, with less interobserver variability and straightforward localization of tumorous accumulation.

Utility of F-18 Fluorothymidine PET Over F-18 Fluorodeoxyglucose PET/CT in Detection of a Recurrent Glioma

ABSTRACT Differentiation of postsurgical or postradiation necrosis from tumor recurrence is a clinical dilemma. Magnetic resonance imaging does not always perform well in this setting. Several nuclear medicine techniques are available that offer a solution in such a clinical situation. We report a case where F-18 flurodeoxyglucose (FDG) and F-18 fluorothymidine (FLT) PET/CT were used to identify recurrence of a glioma. How to cite this article Kashyap R, Tiwari MK, Senthil R, Bhattacharya A, Gupta V, Mittal BR. Utility of F-18 Fluorothymidine PET Over F-18 Fluorodeoxyglucose PET/CT in Detection of a Recurrent Glioma. J Postgrad Med Edu Res 2012;46(4):202-203.

Spectrum of brain abnormalities detected on whole body F-18 FDG PET/CT in patients undergoing evaluation for non-CNS malignancies

We present the pattern of metabolic brain abnormalities detected in patients undergoing whole body (WB) F-18 flurodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) examination for non-central nervous system (CNS) malignancies. Knowledge of the PET/CT appearance of various intracranial metabolic abnormalities enables correct interpretation of PET scans in oncological patients where differentiation of metastasis from benign intracranial pathologies is important and improves specificity of the PET study. A complete clinical history and correlation with CT and MRI greatly helps in arriving at a correct imaging diagnosis.

F-18 Flurodeoxyglucose Negative, F-18 Fluoride Accumulating in a Brain Metastasis in a Treated Case of Carcinoma of the Breast

A 52-year-old woman undergoing treatment for carcinoma of the left breast with brain and bone metastases was referred for F-18 fluoride positron emission tomography-computed tomography (PET/CT) bone scan (FBS) to evaluate the status of a bone metastasis. Review of the plain fluoride-PET images section-wise revealed an intracranial focus of abnormal fluoride accumulation, which was localized to the right medial temporal lobe on the fused fluoride-PET/CT image, with no evidence of calcification corresponding to this lesion on CT. The pretreatment F-18 flurodeoxyglucose (FDG)-PET/CT study showed this lesion to correspond to the site of FDG accumulating in a brain metastasis. The patient had undergone radiation therapy (RT) for her brain metastasis. Brain FDG-PET/CT was then done, which failed to reveal FDG accumulation in the lesion. Magnetic resonance imaging and magnetic resonance spectroscopy of this lesion revealed features suggestive of radiation damage. The probable mechanism of fluoride accumulation in the metastatic brain lesion was related to cell membrane damage and protein denaturation post-RT. Thus, while reporting FBS the possibility of extraosseous accumulation in an intracranial metastasis must be kept in mind.