Impact of the Arterial Input Function Recording Method on Kinetic Parameters in Small-Animal PET.

The goal of this study was to validate the use of an MR-compatible blood sampler (BS) with a detector system based on a lutetium oxyorthosilicate scintillator and avalanche photodiodes for small-animal PET. Five rats underwent a 60-min F-FDG study. For each animal, the arterial input function (AIF) was derived from the BS recording, from manual sampling (MS), and from the PET image.

Shine-Through in PET/MR Imaging: Effects of the Magnetic Field on Positron Range and Subsequent Image Artifacts.

Unlabelled: Simultaneous PET/MR imaging is an emerging hybrid modality for clinical and preclinical imaging. The static magnetic field of the MR imaging device affects the trajectory of the positrons emitted by the PET radioisotopes. This effect translates into an improvement of the spatial resolution in transaxial images.

Principles of PET/MR Imaging.

Hybrid PET/MR systems have rapidly progressed from the prototype stage to systems that are increasingly being used in the clinics. This review provides an overview of developments in hybrid PET/MR systems and summarizes the current state of the art in PET/MR instrumentation, correction techniques, and data analysis. The strong magnetic field requires considerable changes in the manner by which PET images are acquired and has led, among others, to the development of new PET detectors, such as silicon photomultipliers.

Evaluation of positron emission tomographic tracers for imaging of papillomavirus-induced tumors in rabbits.

In this study, simultaneous positron emission tomography (PET)/magnetic resonance (MR) imaging was employed to evaluate the feasibility of the PET tracers 2-deoxy-2-18F-fluoro-d-glucose (18F-FDG), 11C-choline, and 18F-fluorothymidine (18F-FLT) to detect papillomavirus-induced tumors in an established rabbit model system. The combined PET/MR allowed the analysis of tracer uptake of the tumors using the morphologic information acquired by MR. New Zealand White rabbits were infected with cottontail rabbit papillomavirus genomes and were imaged for up to 10 months with a simultaneous PET/MR system during the course of infection.

On the quantification accuracy, homogeneity, and stability of simultaneous positron emission tomography/magnetic resonance imaging systems.

Objective: A potential major application of simultaneous avalanche photodiode-based positron emission tomography (PET)/magnetic resonance imaging (MRI) systems are quantitative brain studies for cerebral blood flow measurements in combination with blood-oxygen-level-dependent or perfusion MRI, requiring a high performance for both modalities. Thus, we evaluated PET quantification accuracy and homogeneity for 2 different simultaneous PET/MRI systems (whole-body and brain scanner) compared with those of a state-of-the-art PET detector (PET/computed tomography) using phantom studies. In addition, we investigated the long-term stability of PET and quality of functional MRI measurements of a clinical whole-body PET/MRI scanner.

Navigation system for minimally invasive esophagectomy: experimental study in a porcine model.

Background: Navigation systems potentially facilitate minimally invasive esophagectomy and improve patient outcome by improving intraoperative orientation, position estimation of instruments, and identification of lymph nodes and resection margins. The authors' self-developed navigation system is highly accurate in static environments. This study aimed to test the overall accuracy of the navigation system in a realistic operating room scenario and to identify the different sources of error altering accuracy.

Imaging findings and therapy response monitoring in chronic sclerodermatous graft-versus-host disease: preliminary data of a simultaneous PET/MRI approach.

Purpose: Our objective was a multifunctional imaging approach of chronic sclerodermatous graft-versus-host disease (ScGVHD) and its course during therapy using PET/MRI.

Methods: We performed partial-body PET/CT and PET/MRI of the calf in 6 consecutively recruited patients presenting with severe ScGVHD. The patients were treated with different immunosuppressive regimens and supportive therapies.

Physics and applications of positron beams in an integrated PET/MR.

In PET/MR systems having the PET component within the uniform magnetic field interior to the MR, positron beams can be injected into the PET field of view (FOV) from unshielded emission sources external to it, as a consequence of the action of the Lorentz force on the transverse components of the positron's velocity. Such beams may be as small as a few millimeters in diameter, but extend 50 cm or more axially without appreciable divergence. Larger beams form 'phantoms' of annihilations in air that can be easily imaged, and that are essentially free of γ-ray attenuation and scatter effects, providing a unique tool for characterizing PET systems and reconstruction algorithms.

Simultaneous PET/MR imaging of the brain: feasibility of cerebral blood flow measurements with FAIR-TrueFISP arterial spin labeling MRI.

Background: Hybrid positron emission tomography/magnetic resonance imaging (PET/MRI) with simultaneous data acquisition promises a comprehensive evaluation of cerebral pathophysiology on a molecular, anatomical, and functional level. Considering the necessary changes to the MR scanner design the feasibility of arterial spin labeling (ASL) is unclear.

Purpose: To evaluate whether cerebral blood flow imaging with ASL is feasible using a prototype PET/MRI device.

Technical performance evaluation of a human brain PET/MRI system.

Objectives: Technical performance evaluation of a human brain PET/MRI system.

Methods: The magnetic field compatible positron emission tomography (PET) insert is based on avalanche photodiode (APD) arrays coupled with lutetium oxyorthosilicate (LSO) crystals and slip-fits into a slightly modified clinical 3-T MRI system. The mutual interference between the two imaging techniques was minimised by the careful design of the hardware to maintain the quality of the B (0) and B (1) field homogeneity.

Feasibility of simultaneous PET/MR imaging in the head and upper neck area.

Objective: The aim of this pilot study was to test and demonstrate the feasibility of simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) of the head and upper neck area using a new hybrid PET/MRI system.

Methods: Eight patients with malignant head and neck tumours were included in the pilot study. Directly after routine PET/CT imaging with a whole-body system using the glucose derivative 2-[¹⁸F]fluoro-2deoxy-D-glucose (FDG) as a radiotracer additional measurements were performed with a prototype PET/MRI system for simultaneous PET and MR imaging.

Simultaneous 68Ga-DOTATOC-PET/MRI for IMRT treatment planning for meningioma: first experience.

Purpose: To evaluate intensity-modulated radiotherapy (IMRT) treatment planning based on simultaneous positron-emission tomography and magnetic resonance imaging (PET/MRI) of meningioma.

Methods And Materials: A meningioma patient was examined prior to radiotherapy with dedicated planning computed tomography (CT), MRI, PET/CT with gallium-68-labeled DOTATOC (68Ga-DOTATOC), and simultaneous 68Ga-DOTATOC-PET/MRI. The first gross target volume (GTV) was defined based on a combination of separate MR and 68Ga-DOTATOC-PET/CT imaging (GTVPET/CT+MR).

Combined PET/MRI: one step further in multimodality imaging.

Given the need for sophisticated in vivo detection techniques to better characterize the cellular and subcellular processes in animals and humans, molecular imaging has become an important discipline. Techniques in molecular imaging have developed from stand alone modalities to multimodality methods. Among these, the combination of positron emission tomography (PET) and computed tomography (CT) is a successful imaging method and has become an important tool in clinical practice.

Hybrid PET/MRI of intracranial masses: initial experiences and comparison to PET/CT.

Unlabelled: Simultaneous PET and MRI using new hybrid PET/MRI systems promises optimal spatial and temporal coregistration of structural, functional, and molecular image data. In a pilot study of 10 patients with intracranial masses, the feasibility of tumor assessment using a PET/MRI system comprising lutetium oxyorthosilicate scintillators coupled to avalanche photodiodes was evaluated, and quantification accuracy was compared with conventional PET/CT datasets.

Methods: All measurements were performed with a hybrid PET/MRI scanner consisting of a conventional 3-T MRI scanner in combination with an inserted MRI-compatible PET system.

Osteopontin but not osteonectin favors the metastatic growth of pancreatic cancer cell lines.

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death in western countries and among the malignancies with the worst prognosis. Osteonectin and osteopontin, two proteins of the extracellular matrix, have been found to be upregulated in PDAC. In the present study the expression of osteopontin mRNA as determined in a panel of 14 human pancreatic cancer cell lines was significantly related to the growth of these cell lines in the liver of nude rats (p = 0.

Diffusion tensor imaging in a human PET/MR hybrid system.

Purpose: The aim of this study was to test and demonstrate the feasibility of diffusion tensor imaging (DTI) with a hybrid positron emission tomography (PET)/magnetic resonance imaging system for simultaneous PET and magnetic resonance (MR) data acquisition.

Materials And Methods: All measurements were performed with a prototype hybrid PET/MR scanner dedicated for brain and head imaging. The PET scanner, which is inserted into a conventional 3.

Evaluation of Geiger-mode APDs for PET block detector designs.

This paper presents an evaluation of two types of Geiger-mode avalanche photodiodes (G-APDs) for their potential to be used in a positron emission tomography (PET) detector. While the MPPC G-APD had only 3600 cells, the solid state photomultiplier (SSPM)-type G-APD had 8100 cells. In a single-channel G-APD/LSO setup, the energy resolution (DeltaEpsilon/Epsilon) of the SSPM at 511 keV was 25%, while the (DeltaEpsilon/Epsilon) of the MPPC was 13.

PET/MRI: paving the way for the next generation of clinical multimodality imaging applications.

Multimodality imaging and, more specifically, the combination of PET and CT has matured into an important diagnostic tool. During the same period, concepts for PET scanners integrated into an MR tomograph have emerged. The excellent soft-tissue contrast of MRI and the multifunctional imaging options it offers, such as spectroscopy, functional MRI, and arterial spin labeling, complement the molecular information of PET.

Glucagon/insulin ratio as a potential biomarker for pancreatic cancer in patients with new-onset diabetes mellitus.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies, with an overall 5-year survival rate of less than 5%. This dismal prognosis is largely due to the advanced stage of the disease at presentation, i.e.

Resection of the intrapancreatic bile duct preserving the pancreas.

Benign neoplasms of the distal bile duct are rare, but pose a therapeutic challenge. Usually, these lesions are resected by means of ampullectomy if located in close proximity to the ampulla of Vateri or by partial pancreaticoduodenectomy if located intrapancreatic and distant from the ampulla. Here, we present a case of an intrapancreatic benign neuroendocrine tumor that was resected by performing a pancreas-preserving distal bile duct resection.

The activated stroma index is a novel and independent prognostic marker in pancreatic ductal adenocarcinoma.

Background And Aims: Pancreatic ductal adenocarcinoma (PDAC) is a highly desmoplastic tumor with an innate resistance to therapy. Pancreatic stellate cells (PSCs) produce this excessively desmoplastic microenvironment. The impact of PSC activity on PDAC behavior in vivo is analyzed.

No role of matrixmetalloproteinase-3 genetic promoter polymorphism 1171 as a risk factor for cirrhosis in alcoholic liver disease.

Background: As only a minority of alcoholics develop cirrhosis, polymorphic genes, whose products are involved in fibrosis development were suggested to confer individual susceptibility. We tested whether a functional promoter polymorphism in the gene encoding matrix metalloproteinase-3 (MMP-3; 1171 5A/6A) was associated liver cirrhosis in alcoholics.

Methods: Independent cohorts from the UK and Germany were studied.

Positron emission tomography/magnetic resonance imaging: the next generation of multimodality imaging?

Multimodal imaging is now well-established in routine clinical practice. Especially in the field of nuclear medicine, new positron emission tomography (PET) installations comprise almost exclusively combined PET/computed tomography (CT) scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT.

Integrin alphavbeta6 is a marker of the progression of biliary and portal liver fibrosis and a novel target for antifibrotic therapies.

Background/aims: The integrin alphavbeta6 promotes proliferation of specialized epithelia and acts as a receptor for the activation of latent TGFbeta1. We studied alphavbeta6 expression in experimental and human liver fibrosis and the potential of its pharmacological inhibition for treatment of hepatic fibrosis.

Methods: alphavbeta6 expression was studied by quantitative PCR and immunohistochemistry in rats with cirrhosis due to bile duct ligation (BDL), administration of thioacetamide (TAA), in Mdr2(Abcb4)(-/-) mice with spontaneous biliary fibrosis, and in livers of patients with chronic hepatitis C (n=79) and end-stage liver disease due to various etiologies (n=18).