Variability in PET image quality and quantification measured with a permanently filled Ge-phantom: a multi-center study.

Background: This study evaluated, as a snapshot, the variability in quantification and image quality (IQ) of the clinically utilized PET [F]FDG whole-body protocols in Finland using a NEMA/IEC IQ phantom permanently filled with Ge.

Methods: The phantom was imaged on 14 PET-CT scanners, including a variety of models from two major vendors. The variability of the recovery coefficients (RC, RC and RC) of the hot spheres as well as percent background variability (PBV), coefficient of variation of the background (COV) and accuracy of corrections (AOC) were studied using images from clinical and standardized protocols with 20 repeated measurements.

Decreased Gray-White Matter Contrast of [11C]-PiB Uptake in Cognitively Unimpaired Subjects with Severe Obstructive Sleep Apnea.

Background: Very recently, cognitively normal, middle-aged adults with severe obstructive sleep apnea (OSA) were shown to have regional cortical amyloid-β deposits. In the normal brain, amyloid tracer (e.g.

AAV2-VEGF-B gene therapy failed to induce angiogenesis in ischemic porcine myocardium due to inflammatory responses.

Therapeutic angiogenesis induced by gene therapy is a promising approach to treat patients suffering from severe coronary artery disease. In small experimental animals, adeno-associated viruses (AAVs) have shown good transduction efficacy and long-term transgene expression in heart muscle and other tissues. However, it has been difficult to achieve cardiac-specific angiogenic effects with AAV vectors.

Adenoviral VEGF-B186R127S gene transfer induces angiogenesis and improves perfusion in ischemic heart.

Vascular endothelial growth factor B (VEGF-B) is an interesting therapeutic candidate for coronary artery disease. However, it can also cause ventricular arrhythmias, potentially preventing its use in clinics. We cloned VEGF-B isoforms with different receptor binding profiles to clarify the roles of VEGFR-1 and Nrp-1 in angiogenesis and to see if angiogenic properties can be maintained while avoiding side effects.

Ex Vivo Porcine Models Are Valid for Testing and Training Microsurgical Lumbar Decompression Techniques.

Background: Spinal surgeries are the leading causes for patient settlement issues. Recent European Medical Device Regulations aims to reduce complications by enforcing that surgical tools are validated before clinical use. Human cadavers are favored in preclinical use, but due to anatomic variance, decay, and scarce supply, alternative synthetic and animal models are used.

Effect of data conserving respiratory motion compensation on left ventricular functional parameters assessed in gated myocardial perfusion SPECT.

Background: Respiratory motion compromises image quality in myocardial perfusion (MP) single-photon emission computed tomography (SPECT) imaging and may affect analysis of left ventricular (LV) functional parameters, including phase analysis-quantified mechanical dyssynchrony parameters. In this paper, we investigate the performance of two algorithms, respiratory blur modeling (RBM) and joint motion-compensated (JMC) ordered-subsets expectation maximization (OSEM), and the effects of motion compensation on cardiac-gated MP-SPECT studies.

Methods: Image acquisitions were carried out with a dual-detector SPECT/CT system in list-mode format.

Severe Obstructive Sleep Apnea and Increased Cortical Amyloid-β Deposition.

Background: The suggested association between severe obstructive sleep apnea (OSA) and risk of Alzheimer's disease (AD) needs further study. Only few recent reports exist on associations between brain amyloid-β (Aβ) burden and severe OSA in middle-aged patients.

Objective: Examine the possible presence of cortical Aβ accumulation in middle-aged patients with severe OSA.

Time-modified OSEM algorithm for more robust assessment of left ventricular dyssynchrony with phase analysis in ECG-gated myocardial perfusion SPECT.

Background: In ordered subsets expectation maximization (OSEM) reconstruction of electrocardiography (ECG)-gated myocardial perfusion single-photon emission computed tomography (SPECT), it is often assumed that the image acquisition time is constant for each projection angle and ECG bin. Due to heart rate variability (HRV), this assumption may lead to errors in quantification of left ventricular mechanical dyssynchrony with phase analysis. We hypothesize that a time-modified OSEM (TOSEM) algorithm provides more robust results.

Effect of respiratory motion on cardiac defect contrast in myocardial perfusion SPECT: a physical phantom study.

Objective: Correction for respiratory motion in myocardial perfusion imaging requires sorting of emission data into respiratory windows where the intra-window motion is assumed to be negligible. However, it is unclear how much intra-window motion is acceptable. The aim of this study was to determine an optimal value of intra-window residual motion.

Respiratory motion reduction with a dual gating approach in myocardial perfusion SPECT: Effect on left ventricular functional parameters.

Background: Respiratory motion (RM) complicates the analysis of myocardial perfusion (MP) single-photon emission computed tomography (SPECT) images. The effects of RM on left ventricular (LV) functional variables have not been thoroughly investigated.

Methods And Results: Thoracic electrical bioimpedance and electrocardiographic signals were recorded from eighteen patients undergoing the rest phase of a 1-day stress/rest cardiac-gated MP-SPECT examination.

Inclusion of Regional Body Composition Parameters Improves Bone Mineral Density Cross-Calibration Between GE Lunar Prodigy and iDXA Densitometers.

Since 1989, the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE, n = 14220) Study has followed long-term changes of bone mineral density (BMD) and body composition in women with GE Lunar devices. During the course of OSTPRE, the dual-energy X-ray absorptiometry device had to be replaced by a newer model. Then, it was essential to determine whether systematic measurement differences in BMD and body composition will occur.

Cross-Calibration of GE Healthcare Lunar Prodigy and iDXA Dual-Energy X-Ray Densitometers for Bone Mineral Measurements.

In long-term prospective studies, dual-energy X-ray absorptiometry (DXA) devices need to be inevitably changed. It is essential to assess whether systematic differences will exist between measurements with the new and old device. A group of female volunteers (21-72 years) underwent anteroposterior lumbar spine L2-L4 (n = 72), proximal femur (n = 72), and total body (n = 62) measurements with the Prodigy and the iDXA scanners at the same visit.

BMI influence on the reproducibility of ECG-gated myocardial perfusion imaging phase analysis in comparison with novel echocardiographic dyssynchrony estimation methods.

Aim: Cardiac resynchronization therapy (CRT) is a treatment for patients with end-stage heart failure. However, two-thirds of the patients are nonresponders. Evaluation of left ventricular mechanical dyssynchrony may help in finding patients who will benefit from CRT.

Dependence of left ventricular functional parameters on image acquisition time in cardiac-gated myocardial perfusion SPECT.

Background: Reduction of image acquisition time in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) examinations has been considered. However, association between left ventricular (LV) functional parameters and acquisition time is unclear.

Methods: Twenty-four patients referred to one-day stress/rest SPECT MPI examinations were imaged at rest with dual-headed gamma camera.

A novel respiratory gating method for oncologic positron emission tomography based on bioimpedance approach.

Objective: Respiratory motion causes loss of image quality and inaccuracy of quantification in oncologic positron emission tomography (PET) imaging. This study introduces a bioimpedance-based gating method for compensation of respiratory motion artefacts.

Methods: The bioimpedance-based respiratory gating method was studied parallel to a clinically used respiratory gating method [Real-time Position Management by Varian Medical Systems] in 4D PET/CT acquisition of 9 oncologic patients.

An integrated bioimpedance--ECG gating technique for respiratory and cardiac motion compensation in cardiac PET.

Respiratory motion may degrade image quality in cardiac PET imaging. Since cardiac PET studies often involve cardiac gating by ECG, a separate respiratory monitoring system is required increasing the logistic complexity of the examination, in case respiratory gating is also needed. Thus, we investigated the simultaneous acquisition of both respiratory and cardiac gating signals using II limb lead mimicking electrode configuration during cardiac PET scans of 11 patients.

Cardiorespiratory fitness, respiratory function and hemodynamic responses to maximal cycle ergometer exercise test in girls and boys aged 9-11 years: the PANIC Study.

Purpose: We aimed to provide comprehensive data on and reference values for cardiorespiratory fitness, respiratory function and hemodynamic responses during and after maximal cycle ergometer test in children.

Methods: The participants were a population sample of 140 children (69 girls) aged 9-11 years. Heart rate (HR) and systolic blood pressure (SBP) were measured from pre-exercise rest to the end of recovery.

Assessment of body composition by dual-energy X-ray absorptiometry, bioimpedance analysis and anthropometrics in children: the Physical Activity and Nutrition in Children study.

Objective And Methods: We compared InBody720 segmental multifrequency bioimpedance analysis (SMF-BIA) with Lunar Prodigy Advance dual-energy X-ray absorptiometry (DXA) in assessment of body composition among 178 predominantly prepubertal children. Segmental agreement analysis of body compartments was carried out, and inter-relationships of anthropometric and other measures of body composition were defined. Moreover, the relations of different reference criteria for excess body fat were evaluated.

Real-time tablet formation monitoring with ultrasound measurements in eccentric single station tablet press.

A real-time ultrasound measurement system for tablet compression monitoring is introduced. The measurement system was tested in actual manufacturing environment and found to be capable of measuring the ultrasound response of the tabletting process from bulk to tablet. The tablet sets were compressed and the ultrasound measurements were conducted as implemented in eccentric single station tabletting apparatus in through transmission geometry.

Bioimpedance-based measurement method for simultaneous acquisition of respiratory and cardiac gating signals.

Respiratory and cardiac motion artefacts impair the quality and reliability of medical imaging, particularly in nuclear medicine. At worst, the interpretation of distorted images may lead to inadequate or unnecessary treatment. Image artefacts can be minimized by gating the image acquisition according to respiratory phase and cardiac contractions.

Influence of different DXA acquisition modes on monitoring the changes in bone mineral density after hip resurfacing arthroplasty.

Dual-energy X-ray absorptiometry (DXA) is a technique enabling the measurement of bone mineral density (BMD) around prostheses after hip resurfacing arthroplasty (HRA). In this study, we evaluated the consistency of different DXA acquisition modes with 33 patients who had undergone HRA. Patients were scanned with DXA immediately after surgery and at 3-, 6-, and 12-mo time points.

Multi-site bone ultrasound measurements in elderly women with and without previous hip fractures.

Unlabelled: About 75% of patients suffering from osteoporosis are not diagnosed. This study describes a multi-site bone ultrasound method for osteoporosis diagnostics. In comparison with axial dual energy X-ray absorptiometry (DXA), the ultrasound method showed good diagnostic performance and could discriminate fracture subjects among elderly females.

Optimizing bioimpedance measurement configuration for dual-gated nuclear medicine imaging: a sensitivity study.

Motion artefacts due to respiration and cardiac contractions may deteriorate the quality of nuclear medicine imaging leading to incorrect diagnosis and inadequate treatment. Motion artefacts can be minimized by simultaneous respiratory and cardiac gating, dual-gating. Currently, only cardiac gating is often performed.

Bone mineral density of the proximal femur after hip resurfacing arthroplasty: 1-year follow-up study.

Background: Hip resurfacing arthroplasty (HRA) is considered a bone-preserving procedure and may eliminate proximal femoral stress shielding and osteolysis. However, in addition to implant-related stress-shielding factors, various patient-related factors may also have an effect on bone mineral density (BMD) of the proximal femur in patients with HRA. Thus, we studied the effects of stem-neck angle, demographic variables, and physical functioning on the BMD of the proximal femur in a one-year follow-up.