Increased Fludeoxyglucose Uptake Research Articles

"Bilateral Hot Forearm Sign": Ingeminating the Pattern of Physiological Uptake of 18F-Fludeoxyglucose.

Exertion and exercise increase glucose metabolism within the skeletal muscles causing increased fludeoxyglucose (FDG) uptake on 18F-FDG positron emission tomography/computed tomography (PET/CT). Here, we present findings of 18F-FDG PET/CT in a patient with acute viral hepatitis A-induced liver failure with multiple foci of pyoderma and incessant itching resulting in increased FDG uptake in the muscles of the bilateral forearm, producing the "bilateral hot forearm sign."

CT-guided percutaneous core biopsy for assessment of morphologically normal adrenal glands showing high FDG uptake in patients with lung cancer.

Increased fludeoxyglucose(FDG) uptake in morphologically normal adrenal glands on positron emission tomography-CT (PET-CT) is a diagnostic challenge with major implications on treatment. The purpose of this retrospective study was to report our experience of CT-guided percutaneous core biopsy of morphologically normal adrenal glands showing increased FDG uptake in a context of lung cancer. Biopsies for non-enlarged adrenal glands showing increased FDG uptake in lung cancer patients performed at our institution from December 2014 to December 2016 were retrospectively analyzed. Six biopsies were performed in five patients during the study period. All procedures were performed with the patients in the prone position, using a posterior approach and coaxial 17-gauge needles with 18-gauge automated cutting needles. Patient characteristics, procedural details and final pathological diagnosis were analyzed, as well as the duration of hospitalization. Five of the six biopsies (83.3%) confirmed adrenal metastasis from the primary lung cancer. No complications were reported and the patients were discharged the day after the procedure. The high confirmation rate of metastasis and lack of complications support performing CT-guided percutaneous biopsy of non-enlarged adrenal glands showing increased FDG uptake, for optimal management in lung cancer patients. Morphologically normal adrenal glands showing high FDG uptake in patients with lung cancer are metastasis. This manuscript shows that CT-guided percutaneous biopsy should be proposed. Increased FDG uptake in morphologically normal adrenal glands may indicate metastasis.

Imaging Inflammation in Cerebrovascular Disease.

Imaging inflammation in large intracranial artery pathology may play an important role in the diagnosis of and risk stratification for a variety of cerebrovascular diseases. Looking beyond the lumen has already generated widespread excitement in the stroke community, and the potential to unveil molecular processes in the vessel wall is a natural evolution to develop a more comprehensive understanding of the pathogenesis of diseases, such as ICAD and brain aneurysms.

Outcome of FDG‐Avid Areas on PET‐CT Scans Organized for Investigation of Head and Neck Malignancy

Objectives:Positron emission tomography (PET) scans may highlight areas of increased fludeoxyglucose (FDG) uptake outside the head and neck (HN) region. These may represent a synchronous malignancy or an area of inflammation or infection. Our study aims to investigate the rate of increased FDG uptake PET scans organized for the investigation of head and neck squamous cell carcinoma (HNSCC) and report on the outcome of these FDG‐avid areas.Methods:A prospective database of PET scans maintained by the West of Scotland PET Centre was reviewed to identify all scans organized by the head and neck teams between January 2008 and December 2011. Areas with high FDG uptake, above the normal limits for different body tissues at which the radiologists advised further investigation, were noted. Case notes were reviewed and relevant head and neck consultants were contacted to identify further investigations and outcome of these “hot spots.”Results:Of 299 PET scans during the study period, 40 FDG‐avid areas outside the HN and lung were identified, the majority originating in the colon (56%), followed by the prostate and pelvic region. There were 9 confirmed second primary tumors (22.5%), which is a significant proportion of the group, and half of the group had an incidental high standardized uptake value (SUV; negative investigation). Eleven patients were not investigated due to poor health and palliative management.Conclusions:All increased SUV areas outside the head and neck region should be investigated to identify a synchronous primary which may determine a patient's overall management and long‐term outcome.

Effect of MRI Acoustic Noise on Cerebral Fludeoxyglucose Uptake in Simultaneous MR-PET Imaging

Integrated scanners capable of simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) data acquisition are now available for human use. Although the scanners' manufacturers have made substantial efforts to understand and minimize the mutual electromagnetic interference between the 2 modalities, the potential physiological inference has not been evaluated. In this study, we have studied the influence of the acoustic noise produced by the magnetic resonance (MR) gradients on brain fludeoxyglucose (FDG) uptake in the Siemens MR-BrainPET prototype. Although particular attention was paid to the primary auditory cortex (PAC), a brain-wide analysis was also performed. The effects of the MR on the PET count rate and image quantification were first investigated in phantoms. Next, 10 healthy volunteers underwent 2 simultaneous FDG-PET/MR scans in the supine position with the FDG injection occurring inside the MR-BrainPET, alternating between a "quiet" (control) environment in which no MR sequences were run during the FDG uptake phase (the first 40 minutes after radiotracer administration) and a "noisy" (test) environment in which MR sequences were run for the entire time. Cortical and subcortical regions of interest were derived from the high-resolution morphological MR data using FreeSurfer. The changes in the FDG uptake in the FreeSurfer-derived regions of interest between the 2 conditions were analyzed from parametric and static PET images, and on a voxel-by-voxel basis using SPM8 and FreeSurfer. Only minimal to no electromagnetic interference was observed for most of the MR sequences tested, with a maximum drop in count rate of 1.5% and a maximum change in the measured activity of 1.1% in the corresponding images. The region of interest-based analysis showed statistically significant increases in the right PAC in both the parametric (9.13% [4.73%]) and static (4.18% [2.87%]) images. The SPM8 analysis showed no statistically significant clusters in any images when a P < 0.05 (corrected) was used; however, a P < 0.001 (uncorrected) resolved bilateral statistically significant clusters of increased FDG uptake in the area of the PAC for the parametric image (left, 8.37% [1.55%]; right, 8.20% [1.17%]) but only unilateral increase in the static image (left, 8.68% [3.89%]). Although the operation of the BrainPET prototype is virtually unaffected by the MR scanner, the acoustic noise produced by the MR gradients causes a focal increase in the FDG uptake in the PAC, which could affect the interpretation of pathological (or brain-activation-related) changes in the FDG uptake in this region if the expected effects are of comparable amplitude.

Hounsfield units upon PET/CT are useful in evaluating metastatic regional lymph nodes in patients with oesophageal squamous cell carcinoma

This study evaluated the usefulness of measurements of X-ray attenuation (in Hounsfield units) obtained from unenhanced CT images for attenuation correction of the positron emission tomography (PET) data from PET/CT in the assessment of regional lymph node metastasis in oesophageal squamous cell carcinoma. 17 patients with oesophageal squamous cell carcinoma underwent surgery after evaluation with PET/CT. After the excised lymph nodes were reviewed, we compared the histopathology and PET/CT findings, and analysed the lymph node metastasis. When 18-F fludeoxyglucose (FDG) uptake in the lymph nodes was focally prominent in comparison with background mediastinal activity (regardless of lymph node size), the lymph nodes were considered to be positive for malignancy by PET/CT. The mean Hounsfield units of mediastinal lymph nodes showing abnormally increased FDG uptake in PET/CT was retrospectively evaluated using images from the unenhanced CT component of PET/CT. Receiver operating characteristic (ROC) curve analysis was applied to determine the optimal cut-off value of mean Hounsfield units for detecting individual lymph node metastases. For depiction of malignant nodal groups in each lymph node group, the sensitivity, specificity and accuracy of PET/CT based on increased FDG uptake were 58.8%, 74.5% and 70.8%, respectively. For patients with nodal groups that were positive for uptake by PET/CT, the mean attenuation in lymph nodes as measured by CT was 48 ± 13 HU for malignant nodes and 75 ± 18 HU for benign nodes. This difference was statistically significant (p<0.001). Using ROC curve analysis, we determined the cut-off as 71 HU. When we excluded lymph nodes with attenuation higher than 71 HU from the nodes determined as malignant by PET/CT, the specificity and accuracy for detecting metastatic lymph nodes improved to 90.9% and 83.3%, respectively. When interpreting lymph node metastasis in oesophageal squamous cell carcinoma using PET/CT, the assumption that any lymph node with mean HU>71 is benign can improve diagnostic accuracy.