Positron Emission Tomography

Tissue hypoxia results from an inadequate supply of oxygen (O2) that compromises biological functions. Structural and functional abnormalities of the tumour vasculature together with altered diffusion conditions inside the tumour seem to be the main causes of tumour hypoxia. Evidence from experimental and clinical studies points to a role for tumour hypoxia in tumour propagation, resistance to therapy and malignant

BACKGROUND AND OBJECTIVE Incidental head and neck abnormalities are increasingly detected with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). Incidental thyroid lesions on PET are described in many studies; however, no reports have definitively identified incidental findings in multiple head and neck sites. The aim of this study was to (1) review the related literature, (2) identify the incidence and significance of head and neck incidentalomas on PET/computed tomography (CT) scanning, and (3) attempt to establish management recommendations for head and neck PET incidentalomas. STUDY DESIGN Retrospective study. SETTING Tertiary care centre. METHODS Head and neck incidentaloma cases from whole-body 18F-FDG PET/CT scans were reviewed based on specific inclusion criteria from January 2009 to January 2010 at the Jewish General Hospital. The patients had been scanned for known or suspected malignant lesions in non-head and neck sites. Patients with incidental head and nec...

This study explored microdosing methods for evaluating the distribution and pharmacokinetics (PK) of a central nervous system (CNS) drug candidate. We used sertraline as a model drug. In this open-label, one-arm, three-period, multiple-dosing study, 10 healthy male volunteers received 6-day administrations of sertraline at doses of 5, 25 or 50 mg/d in three different periods. Before the first dose of Period 1, and 24 h after the last dose of each period, an intravenous bolus of [11C]sertraline was injected for positron emission tomography (PET) scanning. After the sixth dose in each period, serial blood samples were collected at scheduled intervals over 48 h; then serum sertraline concentrations were determined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Sertraline was distributed in the brain within 20 min, and it was highly distributed in the putamen, cingulate, and thalamus. Linearity in steady-state Cmax and AUClast were observed in the 5 - 50 mg dose range. ...

In a patient with severe sepsis, we sometimes observe immediate decrease of the counts of white blood cells (WBCs) and neutrophils, which is known as an indicator for poor prognosis. We observed marked decrease of white blood cells and neutrophils on blood examination and interesting findings on dynamic CT. Here, we present the case of a patient with severe postoperative sepsis occurring after major abdominal surgery and we discuss the mechanism of such clinical presentations. A 60-year-old man received pancreatoduodenectomy with colectomy for pancreatic cancer. He developed a high fever on postoperative day 3. We observed marked decrease of WBCs and neutrophils on blood examination. We also observed slight swelling of the liver, inhomogeneous enhancement of liver parenchyma in arterial phase, and periportal low density in the Glisson capsule in portal phase, without any findings indicating infectious complications on dynamic CT. WBCs and neutrophils increased above normal range in ...

Neurolymphomatosis (NL) is a rare syndrome of lymphoma and leukemic infiltration of cranial or peripheral nerves. We report a case of non-Hodgkin Lymphoma (NHL) in a 24-year-old man presented with difficulty in swallowing, hypersalivation, hoarseness, ptosis, facial paralysis, and facial hypoesthesia associated with NL. NL was diagnosed based upon cranial magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) examination. The patient was treated with intrathecal methotreaxate (12.5 mg) and cytosine arabinoside (70 mg), systemic high-dose methotrexate therapy, and cranial radiotherapy. Due to the deterioration of general condition of the patient, he was admitted to intensive care unit, but died 22 days after the onset of symptoms in spite of aggressive treatment. In this case, we present a patient with T cell lymphoma and multineuritis of NL diagnosed by MRI and as far as we know, this is the first reported case in which so many cranial nerves (3, 5, 7, 8, 9, and 10 th) were ...

In this study, we used a micro-ultrasound (microUS) system that we developed in-house as an alternative method for tumor growth calipers. In addition, microUS was combined with small-animal positron-emission tomography (microPET) for tumor metastatic assessment. MicroUS provides anatomical information that can be used for tumor volume measurements while microPET is a functional imaging method with positron-emitting radiophamaceuticals, such as 18F-labeled deoxyglucose, [18F]FDG. In this study, microUS and microPET were performed in a mouse tumor longitudinal study (2–8 weeks), both with 3D tumor segmentation and volume measurements. Compared with vernier calipers, microPET generally overestimated tumor volumes during weeks 2–4 due to its inadequate spatial resolution. During weeks 5–8, standard deviations of microPET results were large due to tumor hypoxia or necrosis. On the contrary, microUS tumor volume measurements were more reliable as they were less affected by these factors. ...

To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiation therapy (CRT) planning for patients with esophageal carcinoma. Thirty-four patients with esophageal carcinoma were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. PET-images were coregistered using five fiducial markers. Target delineation was initially performed on CT images and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. FDG-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative CRT. The Gross Tumor Volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and was increased in 7 patients (20.5%). The GTV reduction was >or=25% in 4 patients due ...

Neuroimaging plays a major role in the evaluation of patients with neurologic disorders. The utility of various neuroimaging studies is rapidly increasing in both clinical and research settings. Neurologists should learn about the technical aspects, indications, and ...