Fludeoxyglucose Research Articles

A 66-year-old patient with progressive left hemiparesis: answer

High grade astrocytomas and glioblastoma are the most aggressive and frequent type of primary central nervous system tumor [1]. In adults, 70% of tumors are located supratentorially, while tumors of the brainstem and cerebellum are less common. Spinal cord astrocytic tumors, of all grades, are relatively rare [2] and comprise about 35% of all intramedullary tumors [3]. The minority of these tumors are high grade astrocytomas that constitute about 3% of all intramedullary tumors [3]. The presence of synchronous non-congruent cerebral and spinal cord lesions is extremely uncommon, and the disparity of imaging characteristics of the lesions is even more misleading. The use of positron emission tomography (PET)-CT scanning in the evaluation of these lesions pointed toward a diagnosis of primary central nervous system tumors and indicated that the spinal area had a highly active metabolic level indicative of a malignant etiology. Considering the differential diagnosis in this patient the fludeoxyglucose (FDG) PET scan (Fig. 1) proved valuable as a diagnostic clue and as an indicator of the biopsy site that would most likely render an informative tissue sample. This kind of targeting is highly important in lesions like those found in our patient where tissue diagnosis is particularly risky [4–7]. The disparity in the imaging characteristics of the brainstem and spinal cord tumors as well as the fact that only the spinal lesion showed high FDG uptake indicates that the tumor grade may differ in the two lesions and that the brainstem tumor may be of a lower grade. Yet, following treatment with concurrent radiotherapy and temozolomide the brainstem lesion showed clear response on the first follow-up imaging still suggestive of a high grade glioma.

Single-Incision Laparoscopic Sigmoidectomy

Introduction: Laparoscopic surgery has been accepted to be safe and efficacious for the management of colorectal cancer.1,2 The superiority of laparoscopy over open surgery in terms of reduced postoperative pain, shorter hospital stay, early return of bowel activity, and cosmesis has been documented as advantageous in various studies.3,4 In an attempt to reduce the potential complications such as port site bleeding, hernia, infection, and improved cosmesis, minimally invasive colorectal surgery is trending toward single-incision laparoscopic surgery. Bucher et al.5 and Remzi et al.6 described the first single-incision laparoscopic colectomy (SILC) in 2008. But SILC has disadvantages of prolonged operative time, limited applicability, and long learning curve.7 We successfully report the technique of single-incision laparoscopic sigmoidectomy (SILS) for a case of sigmoid colon cancer. Materials and Methods: A 62-year-old man was diagnosed with sigmoid colon adenocarcinoma in the routine screening colonoscopy in June 2013. On clinical examination, bilateral hernioplasty scars were present. His body mass index was 22.7 kg/cm2 and carcinoembryonic antigen (CEA) was 0.62 ng/mL. Colonoscopy showed encircling mass in the sigmoid colon (27–31 cm above anal verge). CT (abdomen+pelvis) showed sigmoid colon cancer stage cT2N0M0. PET CT showed fludeoxyglucose (FDG) avid malignant tumor in sigmoid colon. OCTOTM port (Dalim surginet), model 504V2-A and Olympus camera size–10 mm, LTF type VH with Deflectable Tip were used. Operative Technique: Patient's position was supine with legs abducted and minimally elevated. A 3-cm vertical incision was made through the umbilicus, and the OCTO port was inserted. The pressure was set at 11 mm Hg. SILS was performed from medial to lateral approach. Tumor was identified. Distal margin of 10 cm was marked with the help of black silk. Mesenteric dissection was done with monopolar cautery along the embryological fusion plane. Inferior mesenteric artery (IMA) was identified, dissected, clipped, and cut near the origin. Inferior mesenteric vein (IMV) was also identified, dissected, and severed. Lateral mobilization of sigmoid and descending colon was done to achieve adequate length. Sigmoid colon of 10 cm distal to the tumor was denuded. Laparoscopic bulldog was applied above the distal transection site, and the distal colorectum was irrigated through the anus. Distal colon was transected with Endo GIA stapler. Tumor was exteriorized through the OCTO port. Colon was transected 10 cm proximal to the tumor. Anvil of directional stapling technology end to end anastomosis ( DST EEA) stapler was fixed at the proximal cut end. Colon was reposited back into the abdominal cavity through the OCTO port. DST EEA stapler was inserted through anus. DST EEA trocar was introduced through the distal stump. Anvil was joined to the cartridge fork of the stapler. Stapler was then slowly approximated. Approximation was checked circumferentially for proper. Proximal colon was checked to avoid torsion. Stapler was fired and slowly withdrawn through the anus. End-to-end colo-colo anastomosis using double stapling technique was accomplished. Operative time was 4 hours and 40 minutes, the estimated blood loss was 100 mL, and the length of stay was 6 days. Pathological staging was pT3N0Mx. The postoperative recovery of patient was uneventful. Conclusion: In patients with small tumor, SILS is technically feasible and safe oncological procedure with short-term results similar to conventional laparoscopic colectomy (CLC). No competing financial interests exist. Runtime of video: 9 mins 6 secs

Subglottic Extramedullary Plasmacytoma With Light Chain Multiple Myeloma Masquerading as Adult-Onset Asthma

Extramedullary plasmacytoma (EMP) arises outside the bone marrow and can be associated with multiple myeloma (MM). A 55-year-old gentleman, who presented with dyspnea and expiratory wheeze, was diagnosed and treated for asthma. A subsequent relapse 6 months later prompted an Otolaryngology consult. Preliminary findings showed a benign-looking nodular lesion at the subglottis. Work-up at our institution revealed an Fludeoxyglucose (FDG) avid left subglottic lesion with multiple bone metastases on a Positron Emission Tomography / Computed Tomography (PET/CT). The patient underwent a panendoscopy and laser excision of the subglottic lesion with subglottic jet ventilation. Histology showed an EMP. Further work-up revealed the presence of kappa light chain MM with adverse cytogenetics. Patient was treated systemically with lenalidomide, bortezomib, and dexamethasone for four cycles with rapid improvement in his symptoms. We review the literature about EMP of the subglottis with MM. We present the first case of subglottic laryngeal EMP with MM managed via CO2 laser excision.

The role of FDG-PET/CT in detecting unsuspected and unknown distant metastasis in the initial staging of NSCLC.

Our purpose in this retrospective study was to determine the ratio of unexpected [metastases within the coverage area of thorax computed tomography (CT)] and unknown (metastases out of the coverage area of thorax CT) metastases by positron emission tomography/CT (PET/CT) in patients with newly diagnosed non-small cell lung cancer (NSCLC) who had no defined metastatic lesion, and to investigate the contribution of fludeoxyglucose (FDG)-PET/CT in metastasis staging. A total of 567 patients (489 males and 78 females, mean age 60.9 ± 10.7 years) were enrolled in this study. Among the 567 patients, a total of 156 patients who underwent PET/CT for metabolic characterization (group 1) and had solitary pulmonary nodules (group la, n = 39) or solitary pulmonary masses (group lb, n = 117) and the remaining 411 patients (group 2) with NSCLC who had PET/CT performed for staging formed the basis of this study In group 1, 5/39 (12.8%) patients with a solitary pulmonary nodule and 29/117 (24.8%) patients with a solitary pulmonary mass had distant metastases. In group 2, 129 patients of 411 (31.4%) had distant metastasis. FDG-PET/CT is proven to be an effective method in detection of unsuspected-unknown metastasis, either in patients with solitary pulmonary lesion or in the initial staging of patients with NSCLC.

An 18-year-old with nephrotic syndrome and chest pain: Answers

A two-view chest radiograph showed bilateral hilar lymphadenopathy, a normal heart silhouette, and no pleural effusions or focal pulmonary consolidations. Abdominal ultrasound and computed tomography (CT) with radiocontrast revealed lymphadenopathy throughout his chest and abdomen. These findings were confirmed by whole-body positron emission tomography (PET) /CT, which showed mul t ip le fludeoxyglucose (FDG)-avid lesions above and below the diaphragm and a hypermetabolic lesion in the femoral neck. Nodular sclerosis-type classical Hodgkin’s lymphoma (HL) was diagnosed by excisional lymph node biopsy. A bone marrow biopsy was positive for HL, and he was diagnosed with stage IV HL with B symptoms (night sweats and fevers). Serum and tissue in situ hybridization testing for the EpsteinBarr virus (EBV) was negative, ruling out any association of the virus with his lymphoma. He was treated with four cycles of BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone). There was no sign of persistent disease at the end of chemotherapy. He remains on tacrolimus for his previous diagnosis of nephrotic syndrome (NS), which has remained in remission.

A Prospective Study to Determine Inter-observer Variability of Gross Tumor Volume with [18F] Fludeoxyglucose-PET/CT Compared to CT Alone in Stage III Non-Small Cell Lung Cancer Using Three-Dimensional Analysis

Purpose: This study determined the interobserver variability of Gross Tumor Volume (GTV) with [18F] Fludeoxyglucose (FDG)-PET/CT compared to CT alone in Stage III Non-Small Cell Lung Cancer (NSCLC) using 3D analysis. Materials and Methods: Twenty-nine patients underwent simultaneous co-registered CT and FDG-PET/CT for radiotherapy planning. GTV for lung tumor and mediastinal lymphadenopathy contoured by three different radiation oncologists was compared for changes in volume and position. Interobserver variability was determined with vector displacement and Dice Similarity Coefficient (DSC). Concordance for the number of lymph nodes was determined. Results: Mean GTV for lung tumor with FDG-PET/CT and CT alone was 62.0 cm3 and 74.64 cm3, (p=0.0005) with 17% reduction in GTV by FDG-PET/CT. Mean GTV for mediastinal lymphadenopathy was 15.72 cm3 and 19.02 cm3 (p=0.084) with 17% reduction in GTV. Mean vector displacement of lung tumor was 2.0 mm with FDG-PET/CT versus 7.1 mm with CT alone (p = 0.0016) with 3.6 fold reduction in interobserver variability. Mean vector displacement of mediastinal lymphadenopathy was 1.53 mm with FDG-PET versus 10.2 mm for CT alone (p= 0.0005) with 6.7 fold reduction in interobserver variability. Median DSC for the primary GTV was 0.87 for FDG-PET/CT and 0.74 for CT alone. Median DSC for nodal GTV was 0.79 and 0.59 respectively. All physicians agreed on the number of lymph nodes on CT alone in 15/29 vs. 27/29 patients on PET/CT. Only two of the three physicians agreed on the number of lymph nodes contoured for CT alone in 12/29 versus only 2/29 patients for FDG-PET/CT (p=0.0018). Conclusion: FDG-PET/CT compared to CT alone is more precise, reduces mean lung tumor and mediastinal nodal GTV and interobserver variability. There was greater agreement for the number of lymph nodes contoured on FDG-PET/CT compared to CT alone.

Fludeoxyglucose F-18

Fludeoxyglucose F-18

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.

Utility of positron emission tomography/CT in the evaluation of small bowel pathology

We describe the management principles and different roles of positron emission tomography (PET)/CT in the evaluation of patients with small bowel tumours (adenocarcinoma, gastrointestinal stromal tumour, lymphoma, metastases) from initial staging, monitoring response to treatment, to detection of recurrent disease. We also discuss the various non-malignant aetiologies of small bowel fludeoxyglucose (FDG) PET uptake, and other pitfalls in FDG PET/CT interpretation. Awareness of the imaging appearances of small bowel tumours, patterns of disease spread and potential PET/CT interpretation pitfalls are of paramount importance to optimise diagnostic accuracy.

Clinical utility of 18F FDG-PET/CT in the detection of bone marrow disease in Hodgkin's lymphoma

The aim of the study was to evaluate the potential role of fludeoxyglucose (FDG)-positron emission tomography (PET)/CT in the detection of bone/bone marrow disease in patients with Hodgkin's lymphoma (HL). We retrospectively reviewed ((18)F)-FDG-PET/CT scans of 122 newly diagnosed, biopsy-proven cases of HL performed between November 2009 and June 2010. All the patients were staged before treatment by both PET/CT and bone marrow biopsy (BMB). Patients were subdivided into three groups based on the findings of FDG-PET/CT. Group A consisted of patients showing diffuse FDG uptake, Group B consisted of patients showing unifocal FDG uptake and Group C patients showed multifocal FDG-avid foci on PET/CT scans. Bone marrow results were also reviewed and considered positive if lymphomatous involvement was detected on bone marrow trephine biopsy. BMB results were correlated with FDG-PET/CT findings. There were 122 patients in total-81 (66.4%) were male and 41 (33.6%) were female. The age range was from 6 years to 78 years (mean 35.70 years). PET/CT was reported as negative for bone/bone marrow involvement in 85 (69.7%) patients, while the remaining 37 showed abnormal FDG uptake. The sensitivity of FDG-PET/CT was calculated to be 100%, the specificity was 76.57%, the negative predictive value was 76.57%, the positive predictive value was 29.72% and the diagnostic accuracy was 78.62%. (18)F-FDG-PET/CT and BMB are complementary in the evaluation of bone marrow disease.

Overexpression of extracellular superoxide dismutase has a protective role against hyperoxia‐induced brain injury in neonatal mice

There is increasing evidence that hyperoxia, particularly at the time of birth, may result in neurological injury, in particular to the susceptible vasculature of these tissues. This study was aimed at determining whether overexpression of extracellular superoxide dismutase (EC-SOD) is protective against brain injury induced by hyperoxia. Transgenic (TG) mice (with an extra copy of the human extracellular superoxide dismutase gene) and wild-type (WT) neonate mice were exposed to hyperoxia (95% of F(i) o(2) ) for 7 days after birth versus the control group in room air. Brain positron emission tomography (PET) scanning with fludeoxyglucose (FDG) isotope uptake was performed after exposure. To assess apoptosis induced by hyperoxia exposure, caspase 3 ELISA and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were performed. Quantitative western blot for the following inflammatory markers was performed: glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, macrophage-inhibiting factor, and phospho-AMP-activated protein kinase. PET scanning with FDG isotope uptake showed significantly higher uptake in the WT hyperoxia neonate brain group (0.14 ± 0.03) than in both the TG group (0.09 ± 0.01) and the control group (0.08 ± 0.02) (P< 0.05). Histopathological investigation showed more apoptosis and dead neurons in hippocampus and cerebellum brain sections of WT neonate mice after exposure to hyperoxia than in TG mice; this finding was also confirmed by TUNEL staining. The caspase 3 assay confirmed the finding of more apoptosis in WT hyperoxia neonates (0.814 ± 0.112) than in the TG hyperoxic group (0.579 ± 0.144) (P < 0.05); this finding was also confirmed by TUNEL staining. Quantitative western blotting for the inflammatory and metabolic markers showed significantly higher expression in the WT group than in the TG and control groups. Thus, overexpression of EC-SOD in the neonate brain offers significant protection against hyperoxia-induced brain damage.

Coexisting iodine avid and iodine nonconcentrating lesions with multiple distant soft tissue metastasis in papillary thyroid cancer

Distant soft tissue metastasis and the simultaneous presence of iodine concentrating and nonconcentrating lesions in papillary thyroid cancer are extremely rare. The concerned patient, a histopathologically proven case of papillary thyroid cancer with nodal metastases treated with total thyroidectomy, bilateral cervical nodal dissection, and radioablation, subsequently developed lung, muscle, and liver metastasis. Triggered by increased thyroglobulin, the iodine-131 whole body scan and 200 mci iodine-131 post-therapy scan showed a left gluteus maximus lesion and a liver lesion. Fludeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan intended to find additional lesions revealed iodine and FDG nonconcentrating bilateral pulmonary nodules and a single FDG avid hepatic and two muscle metastases. Although FDG concentration in metastatic pulmonary nodules is generally low, the CT characteristics were classical for metastatic lesion. A follow-up FDG PET-CT study six months after 200 mci iodine-131 radioablation showed treatment response in muscle and liver lesions but not lungs.

Reversible high blood CEA and CA19-9 concentrations in a diabetic patient

We observed a 31-year-old male suffering from general malaise and body weight loss for almost 6 months. He came to our hospital for examination, and the reports showed recently diagnosed diabetes (fasting plasma glucose 309 mg/dl, HbA1C 14.9%) with elevated carcinoembryonic antigen (CEA) 8.9 ng/ml (normal range 0-5 ng/ml) and carbohydrate antigen 19-9 (CA19-9) 123 U/ml (normal range 0-37 U/ml). Abdominal computed tomography (CT) revealed faint hypodensity at pancreatic head with mild dilatation of the main pancreatic duct. Positron emission tomography (PET) scan was then arranged to rule out malignancy and the report showed no abnormal fludeoxyglucose (FDG) uptake over the pancreatic head. After 3 months of anti-diabetic drugs treatment with lifestyle modification, his HbA1C fell to 6.8%. At the same time, the tumor markers also declined to normal (CEA 3.8 ng/ml, CA19-9 26.58 U/ml). (Published: 24 October 2012) Citation: Libyan J Med 2012, 7 : 19572 - http://dx.doi.org/10.3402/ljm.v7i0.19572

CSF Biomarker and PIB-PET-Derived Beta-Amyloid Signature Predicts Metabolic, Gray Matter, and Cognitive Changes in Nondemented Subjects

Beta-amyloid (Aβ) is a histopathological hallmark of Alzheimer's disease dementia, but high levels of Aβ in the brain can also be found in a substantial proportion of nondemented subjects. Here we investigated which 2-year rate of brain and cognitive changes are present in nondemented subjects with high and low Aβ levels, as assessed with cerebrospinal fluid and molecular positron emission tomography (PET)-based biomarkers of Aβ. In subjects with mild cognitive impairment, increased brain Aβ levels were associated with significantly faster cognitive decline, progression of gray matter atrophy within temporal and parietal brain regions, and a trend for a faster decline in parietal Fludeoxyglucose (FDG)-PET metabolism. Changes in gray matter and FDG-PET mediated the association between Aβ and cognitive decline. In contrast, elderly cognitively healthy controls (HC) with high Aβ levels showed only a faster medial temporal lobe and precuneus volume decline compared with HC with low Aβ. In conclusion, the current results suggest not only that both functional and volumetric brain changes are associated with high Aβ years before the onset of dementia but also that HC with substantial Aβ levels show higher Aβ pathology resistance, lack other pathologies that condition neurotoxic effects of Aβ, or accumulated Aβ for a shorter time period.

Systemic administration of 3-bromopyruvate in treating disseminated aggressive lymphoma

The Warburg hypothesis states that aggressive cancers obtain much of their adenosine triphosphate (ATP) by metabolizing glucose directly to lactic acid. As a result of its high tumor selectivity, 3-bromopyruvic acid (3-BrPA), a well-known inhibitor of energy metabolism, has been proposed as a specific anticancer agent. We investigated the effect of 3-BrPA in a mouse model of aggressive metastatic lymphoma. Epstein-Barr-virus-infected human Raji lymphoma cells with lentivirally transfected green fluorescent protein and luciferase were incubated with RPMI/fetal bovine serum, and various concentrations of 3-BrPA were used to determine the LD50 in vitro. In total, 18 severely combined immunodeficient mice were injected with 1 million human Raji lymphoma cells via the tail vein. Using bioluminescent imaging, tumor growth was measured daily for 12 days to determine the tumor burden. At day 0 (start of treatment), the mice were randomized. Six mice received 10 mg/kg 3-BrPA i.p. daily for 7 days, 6 mice received 1 treatment at day 0, and 6 mice received the control buffer. Tumor growth was assessed daily from day 0 until day 7 using bioluminescent imaging. All data were normalized to acquisition time (luminescence/second; L/s). Body weight was measured daily to determine the toxicity of 3-BrPA. The LD50 for Raji lymphoma cells exposed to 3-BrPA in vitro was 11 μM with an extremely steep dose response curve. At day 0, tumor activity medians in the group with daily treatment was 2131 L/s (244-12,725), with a 1-day dose of 3095 L/s (523-9650) and in the nontreated control group, 2997 L/s (1521-6911). In mice treated with a daily dose of 10 mg/kg 3-BrPa for 7 days, a significant reduction in tumor activity was found during the whole treatment period compared with the control mice (P = 0.0043 at day 7). In mice with a single treatment at day 0, growth delay was only evident at day 2 (P = 0.0152 at day 2) but not for the rest of the observation period. The only manifestation of toxicity of the daily administration of 10 mg/kg 3-BrPA was a reduction in body weight. Body weight at day 0 was 17.22 g ± 0.84 g in the treatment group and 17.58 g ± 0.86 g in the control group. Body weight at day +6 was 15.02 g ± 2.04 g in the treated group and 19.4 g ± 0.63 g in the control group. 3-BrPA demonstrated a significant positive tumor response both in vitro and in vivo. This, to our knowledge, is the first report of the use of 3-BrPA in a systemic tumor model. Based on these data, 3-BrPA holds promise for treatment of systemic metastatic cancers.

Visual Vignette

Case Presentation: A 50-year-old woman presented with chief complaints of night sweats and fatigue. During a previous evaluation, an elevated level of cancer antigen 125 (CA 125) of unclear cause had been detected. Her medical history was notable for transverse myelitis. Her medications included duloxetine. Findings on physical examination were within normal limits, with no evidence of lymphadenopathy, rash, or palpable masses. Laboratory evaluation revealed a persistently elevated CA 125 level at 101 U/mL (reference range, less than 35). Positron emission tomography (PET) was performed, which showed evidence of increased fludeoxyglucose (FDG) uptake bilaterally in the subcutaneous tissues of the face anterolateral to the maxillary teeth (Fig. 1), and dense calcification was seen on a fused computed tomographic scan (Fig. 2). What is the diagnosis? Fig. 2 View Large Image Figure Viewer

CSF biomarker and PIB-PET–derived beta-amyloid signature predicts metabolic, grey matter and cognitive changes in nondemented subjects

Beta-amyloid (Ab) is a histopathological hallmark of Alzheimer’s disease dementia, but high levels of Ab in the brain can also be found in a substantial proportion of nondemented subjects. Here we investigated which 2-year rate of brain and cognitive changes are present in nondemented subjects with high and low Ab levels, as assessed with cerebrospinal fluid and molecular positron emission tomography (PET)--based biomarkers of Ab. In subjects with mild cognitive impairment, increased brain Ab levels were associated with significantly faster cognitive decline, progression of gray matter atrophy within temporal and parietal brain regions, and a trend for a faster decline in parietal Fludeoxyglucose (FDG)PET metabolism. Changes in gray matter and FDG-PET mediated the association between Ab and cognitive decline. In contrast, elderly cognitively healthy controls (HC) with high Ab levels showed only a faster medial temporal lobe and precuneus volume decline compared with HC with low Ab. In conclusion, the current results suggest not only that both functional and volumetric brain changes are associated with high Ab years before the onset of dementia but also that HC with substantial Ab levels show higher Ab pathology resistance, lack other pathologies that condition neurotoxic effects of Ab, or accumulated Ab for a shorter time period.

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.

Fludeoxyglucose F-18

Fludeoxyglucose F-18

Fludeoxyglucose F-18

Fludeoxyglucose F-18