Endogenous Technology Adoption and Medical Costs.

Despite the claim that technology has been one of the most important drivers of healthcare spending growth over the past decades, technology variables are rarely introduced explicitly in cost equations. Furthermore, technology is often considered exogenous. Using 1996-2007 panel data on Swiss geographical areas, we assessed the impact of technology availability on per capita healthcare spending covered by basic health insurance whilst controlling for the endogeneity of health technology availability variables. Our results suggest that medical research, patent intensity and the density of employees working in the medical device industry are influential factors for the adoption of technology and can be used as instruments for technology availability variables in the cost equation. These results are similar to previous findings: CT and PET scanner adoption is associated with increased healthcare spending, whilst increased availability of percutaneous transluminal coronary angioplasty facilities is associated with reductions in per capita spending. However, our results suggest that the magnitude of these relationships is much greater in absolute value than that suggested by previous studies that did not control for the possible endogeneity of the availability of technologies. Copyright © 2016 John Wiley & Sons, Ltd.

[ECONOMIC EFFICIENCY TECHNOLOGIES DIAGNOSIS OF ISCHEMIC HEART DISEASE BY MAHNITOTOKARDIOHRAFIYI].

The article is devoted to clinical--economic analysis of modern diagnostic technology--magnetocardiography by analyzing the "cost-effectiveness". Economic effectiveness of diagnosis of coronary artery disease using magnetocardiography in terms of cost/effectivness is shown. The economicaly optimal sequence of several noninvasive methods for diagnosis of coronary artery disease is defined.

A macroquantification approach for region-of-interest assessment in emission tomography.

In this article, we propose a quantification methodology for estimating the statistical parameters of the activity inside regions of interest (ROIs). Macroquantification implies a rearrangement of the emission projection data into macroprojections and a redefinition of the system matrix based either on an image reconstruction involving iterative ROI-wise regularization or on an ROI uniformity assumption. The technique allows a very fast computation of the ROI activities and covariance matrix in the least squares sense using a low-dimensional model of the tomographic problem. The macroquantification approach is evaluated through Monte Carlo simulations using a numerical thorax phantom, without taking into account the measurement artifacts and assuming a perfect a priori ROI definition. Various tumor ROI configurations and count rates are considered to reflect clinical situations. The results show that our technique yields low-bias ROI estimations that turn out to be more accurate than classical estimates relying on pixel summation. Macroquantification also provides an approximation for the ROI variance that describes the effective variance obtained through the simulations fairly well. The technique is then validated using single photon emission computed tomography (SPECT) data from a physical phantom composed of cylinders filled with different Tc concentrations for the task of ROI comparison. Here again, the study shows excellent agreement between the measured and predicted values of the ROI variance resulting in efficient estimations of ROI ratios and highly accurate ROI comparisons. In its simplest formulation, macroquantification has a short computation time, making it an ideal technique for quantitative ROI assessment that is compatible with a wide range of routine clinical applications.

Scaling down imaging: molecular mapping of cancer in mice.

The development of miniaturized imaging equipment and reporter probes has improved our ability to study animal models of disease, such as transgenic and knockout mice. These technologies can now be used to continuously monitor in vivo tumour development, the effects of therapeutics on individual populations of cells, or even specific molecules. If these techniques prove effective in mice, they might be translated into the clinic in the future, where they could be used to non-invasively detect and monitor treatment of human cancers.

An integrated MR/PET system: prospective applications.

Radiology is strongly depending on medical imaging technology and consequently directing technological progress. A novel technology can only be established, however, if improved diagnostic accuracy influence on therapeutic management and/or overall reduced cost can be evidenced. It has been demonstrated recently that Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) can technologically be integrated into one single hybrid system. Some scientific arguments on the benefits are obvious, e.g., that simultaneous imaging of morphological and functional information will improve tissue characterization. However, crossfire of questions still remains: what unmet radiological needs are addressed by the novel system? What level of hardware integration is reasonable, or would software-based image co-registration be sufficient? Will MR/PET achieve higher diagnostic accuracy compared to separate imaging? What is the added value compared to other hybrid imaging modalities like PET/CT? And finally, is the system economically reasonable and has the potential to reduce overall costs for therapy planning and monitoring? This article tries to highlight some perspectives of applying an integrated MR/PET system for simultaneous morphologic and functional imaging.

(90)Y bremsstrahlung emission computed tomography using gamma cameras.

OBJECTIVE: This study demonstrates images obtained by (90)Y bremsstrahlung emission computed tomography (BECT), and characterizes the system performance of gamma cameras. METHODS: (90)Y BECT images of phantoms were acquired using a gamma camera equipped with a medium energy general purpose parallel-hole collimator. Three energy window widths of 50% (57-94 keV) centered at 75 keV, 30% (102-138 keV) at 120 keV, and 50% (139-232 keV) at 185 keV were set on a (90)Y bremsstrahlung spectrum. The images obtained with three energy windows were reconstructed using filtered back projection (FBP) and ordered subsets expectation maximization (OSEM) methods. The images of the sum window were obtained by fusing the images of the 75, 120, and 185 keV windows. RESULTS: The OSEM method improved the full width at half maximum by 20% and the standard deviation by 9% compared with the FBP method. BECT displayed (90)Y biodistribution and quantified (90)Y activity. BECT images obtained with OSEM method using the 120 keV window showed the highest resolution and lowest uncertainty. The sum window showed the highest sensitivity, while its resolution was 10% inferior to that of the 120 keV window. One whole-body image can be taken over 100 min using the sum window. An absorber to cover the body surface reduced background by 30%. CONCLUSIONS: (90)Y BECT imaging can be used for patient assessment without modifying current treatment procedures.

State of the art and challenges of time-of-flight PET.

After a brief review of the history of time-of-flight (TOF) positron emission tomography (PET) instrumentation from the 1980s to present, the principles of TOF PET are introduced, the concept of time resolution and its effect on TOF gain in signal-to-noise ratio (SNR) are discussed. The factors influencing the time resolution of a TOF PET scanner are presented, with focus on the intrinsic properties of scintillators of particular interest for TOF PET. Finally, some open issues, challenges and achievements of today's TOF PET reconstruction are reviewed: the structure of the data organization, the choice of analytical or iterative method, the recent experimental assessment of TOF image quality, and the most promising applications of TOF PET.

Automated quantitation of pericardiac fat from noncontrast CT.

INTRODUCTION: Increased abdominal visceral fat has been shown to be a cardiovascular risk factor. Preliminary studies indicate that pericardiac fat (PF) may provide similar information. We aimed to develop new software (QFAT) for automatic quantitation of PF from noncontrast cardiac CT and compare PF measures to other cardiovascular risk factors. METHODS: QFAT accepts user-defined range of noncontrast transverse cardiac CT slices, automatically segments the heart, and determines PF volume (PFV) as contiguous pericardial fat voxels. PFV normalized to cardiac volume defines PF ratio (PFR). QFAT and manual processing (MAN) was performed in 105 patients (mean BMI, 27; range, 17-41) by 2 observers. RESULTS: Mean processing time was 20 +/- 4 seconds for QFAT, and 9 +/- 6 minutes for MAN. There was excellent agreement between QFAT and MAN for PFV (R = 0.98) and PFR (R = 0.98). MAN and QFAT interobserver variability were comparable. Interscan and interscanner variability for PFV and PFR were comparable to corresponding interobserver variability. PFV (R = 0.88, P < 0.0001) and PFR (R = 0.81, P < 0.0001) correlated strongly with abdominal visceral fat area, moderately with BMI (R = 0.58, P < 0.0001 and R = 0.48, P < 0.0001), and weakly with abdominal subcutaneous fat area (R = 0.33, P < 0.0001 and R = 0.32, P = 0.001). CONCLUSIONS: PFV and PFR can be accurately and automatically quantified from noncontrast CT acquired for coronary calcium screening and may provide complementary information regarding cardiovascular risk.

Contrast media: procedural capacities and potential risks.

Contrast media are known to have transient hemodynamic properties that can influence a patient's clinical status, including heart rate variability and blood pressure. These changes have the potential to impact the diagnostic quality of CT scans. Although most patients are able to receive contrast media without significant adverse reactions, events occur in a minority of cases. These reactions range from mild discomfort (injection-associated pain and heat sensation) to more significant cardiac, renal, and hypersensitivity reactions. The incidence of adverse reactions varies with the type of contrast media used, and several randomized trials have elucidated the cardiac and renal differences among agents. Risk factors for contrast-induced acute kidney injury (CIAKI) have been established, with baseline kidney disease amplified by the presence of diabetes constituting the highest-risk patient group. Strategies for preventing CIAKI include antioxidant therapy, hydration regimens, and choice of contrast agents. Enhanced knowledge on the part of physicians and medical personnel regarding the properties and potential side effects of iodinated contrast agents should lead to improved patient safety and efficacy when performing radiologic examinations.

Priceless clinical pearls in the performance of cardiac CT.

Cardiovascular CT represents an important innovation in cardiac imaging as a noninvasive modality for the diagnosis of coronary artery disease. As a screening examination, coronary CT has the ability to identify the presence, extent, location, and severity of coronary artery disease in patients at risk. As a diagnostic examination in patients with chest discomfort and dyspnea, it can not only evaluate for the presence of coronary artery disease but also evaluate the pulmonary vasculature and aorta. The ability to perform high-quality cardiac CT requires a combination of technical expertise and knowledge of cardiac anatomy. From our experience having performed over 6000 cardiac CTs, we provide the reader with a number of clinical and technical pearls that will enhance his or her ability to perform high-quality studies even in the more challenging patient.

Neutron-stimulated emission computed tomography of a multi-element phantom.

This paper describes the implementation of neutron-stimulated emission computed tomography (NSECT) for non-invasive imaging and reconstruction of a multi-element phantom. The experimental apparatus and process for acquisition of multi-spectral projection data are described along with the reconstruction algorithm and images of the two elements in the phantom. Independent tomographic reconstruction of each element of the multi-element phantom was performed successfully. This reconstruction result is the first of its kind and provides encouraging proof of concept for proposed subsequent spectroscopic tomography of biological samples using NSECT.

Impact of the lower energy threshold on the NEMA NU2-2001 count-rate performance of a LSO based PET-CT scanner.

UNLABELLED: The aim of this study was to investigate the impact of the lower energy threshold (LET) on the NEMA NU2-2001 count-rate performance of a LSO-based PET scanner (Siemens PET-CT Biograph Sensation 16). The quantitative measurements were focused on three different aspects: noise equivalent count rate (NEC), scatter fraction, and absolute sensitivity. METHODS: According to the NEMA-NU2-2001 protocol count-rate-performance (NEC-2R, scatter fraction) and sensitivity were evaluated performing serial measurements at LETs of 350, 375, 400, 410, 420, 430, 440, and 450 keV (the upper energy threshold was fixed to 650 keV). NEMA protocols were adapted to account for the intrinsic radioactivity of (176)Lu in the LSO crystals. RESULTS: Up to a radioactivity concentration of 8 kBq/ml the highest NEC-rates were obtained at an LET of 410 keV, between 8 and 20 kBq/ml at an LET of 420 keV and above 20 kBq/ml at an LET of 430 keV. The overall NEC maximum was 67 kcps at 430 keV (at 28 kBq/ml). The minimum scatter fraction was measured at a radioactivity concentration of approximately 0.5 kBq/ml. The scatter fraction decreased continuously from 45% at an energy threshold of 350 keV to 24% at 450 keV. The maximum sensitivity of 5.8 kcps/MBq, was obtained at an LET of 350 keV and the minimum sensitivity of 4.2 kcps/MBq at an LET of 450 keV. At the LET with the maximum NEC-rate (430 keV) the sensitivity was 4.8 kcps/MBq. CONCLUSION: The optimal count-rate performance of the LSO-based PET system was found at LETs between 410 keV and 430 keV depending on the actual radioactivity concentration placed in the scanner. A global maximum in NEC count rate was obtained at an LET of 430 keV.

A review of spinal arachnoid cysts.

The symptoms of spinal arachnoid cysts are variable and nonspecific, so they are commonly misdiagnosed. Often the cysts are discovered incidentally on magnetic resonance imaging (MRI). If they cause no symptoms, no treatment is warranted regardless of the size of the cyst. Cysts that cause symptoms from mechanical compression of the spinal cord are best evaluated with MRI and surgically excised if possible.

CT-based planning of a single-radius femoral component in total knee arthroplasty using the ROBODOC system.

OBJECTIVE: The purpose of this study was to propose our CT-based planning approach for knee arthroplasty on the basis of the femoral flexion-extension (FE) axis, and to evaluate whether this approach was valid by comparing the results with those obtained using conventional anterior-referenced planning. MATERIALS AND METHODS: Virtual implantation of a sagittal single-radius component was performed in 34 normal knees. The transepicondylar axis (TEA) was identified as the FE axis, and was modified in the coronal plane to intersect the femoral mechanical axis at a right angle, if necessary. The implant was then selected that had a radius closest to the distance between the modified TEA and the distal condyle end. The implant position and size were compared for the two plans. RESULTS: In almost all cases, slight modification of the TEA was required. However, there was no significant change in the distance from the TEA to the posterior and distal condyles. In comparison to the results obtained with our planning approach, the conventional plan resulted in antero-superior deviation of the implant sagittal center to the FE axis and/or selection of a larger size of prosthesis. CONCLUSION: Although the TEA must be modified slightly when referencing it as the FE axis, our planning approach may be valid for femoral single-radius components because the single axis of the component could be matched with the FE axis.

Positron emission tomography/computed tomography (PET/CT) in children.

Although PET imaging has been available for more than two decades, its use has greatly increased lately due to the advent of PET/CT, readily available sources of commercially supplied FDG, and mobile scanners. These features have enabled PET scanning to expand beyond select major university medical centers, with on-site cyclotron facilities to smaller institutions including free- standing children's hospitals. In these settings, imaging is generally limited to FDG, which suffices for most applications, with the majority of studies performed for tumor imaging. FDGI is being used for evaluation of many tumors in children, with its use in lymphoma being the most established. In lymphoma, it has proven quite useful in determining whether active tumor is present in residual masses following treatment, which may otherwise contain only residual fibrous tissue. For brain tumors, FDGI has some relation to tumor grade, although its more important role is distinguishing recurrent or residual tumor from the effects of treatment, particularly radiation necrosis. For neurological evaluation, interictal FDGI is helpful in localizing potential seizure foci for subsequent subdural EEG monitoring. Because of the relatively long uptake time of FDG, true ictal studies cannot be performed with FDG, and these remain within the domain of SPECT imaging of tracers such as Tc-99m HMPAO. Examinations utilizing radiopharmaceuticals other than FDG are significantly more limited in their availability and are limited to PET centers with on-site cyclotrons. However, these additional agents open the door to many additional studies, including more specific tumor-imaging agents of certain tumors such as neuroblastoma. Another neurotransmitter, F-18-fluoro-L-dopa, is of benefit outside of the central nervous system for evaluating infantile hyperinsulism. The use of PET/CT in children is increasing quickly, particularly FDGI imaging of tumors. It is expected that over the next few years, its role will become increasingly better defined.

Imaging of tissue structures and mechanical analysis.

The anatomical structure of biological tissues and their mechanical function are closely related. Forces have a decisive influence on growth and remodeling of tissues; furthermore, intra- and extravascular transport processes are mostly controlled mechanically and the metabolism of many cells is influenced by flow-induced shear stresses. In order to facilitate a mechanical analysis of biological systems, the anatomical tissue structure has to be determined with the aid of 3D imaging methods. In particular, the anisotropic fibrous architecture of the organs involved along with appropriate constitutive relations have to be considered. Examples of structure-(mechanical) function relationships are discussed in an exemplary fashion for bone, the heart and the uterus. The behavior of biological structures under unphysiological loading situations, such as they may occur in accidents, is addressed.

Micro-PET imaging and small animal models of disease.

Positron emission tomography (PET) has been used clinically to measure enzyme reactions, ligand-receptor interactions, cellular metabolism and cell proliferation. Until recently, however, PET has not been suitable for small animal models because of resolution limitations. Development of micro-PET instrumentation for small animal imaging and the availability of positron-emitting tracers has made this technology accessible for the non-invasive, quantitative and repetitive imaging of biological function in living animals. The development of new probes and positron-imaging based reporter genes has extended micro-PET applications to investigations of metabolism, enzyme activity, receptor-ligand interactions, protein-protein interactions, gene expression, adoptive cell therapy and somatic gene therapy. Because small animal PET is immediately extrapolatable to the clinic, laboratory advances should rapidly be translated to clinical practice.

Diagnostic accuracy of dual-source computed tomography in the diagnosis of coronary artery disease.

PURPOSE: The aim of this study was to evaluate the diagnostic accuracy of dual-source computed tomography (DSCT) with reference to invasive coronary angiography in the diagnosis of coronary artery disease (CAD) on a per-patient as well as on a per-segment basis. MATERIALS AND METHODS: Thirty-five patients with known or suspected CAD underwent both DSCT (Somatom Definition, Siemens Medical Solutions) and quantitative x-ray coronary angiography (QCA). Parameters of CT acquisition were gantry rotation time 0.330 seconds (ie, temporal resolution 83 milliseconds), tube voltage 120 kV, tube current 560 mA with ECG-triggered tube current modulation and full current at 70% of the cardiac cycle for heart rates below 70 beats per minute or full current between 30% and 80% for higher and arrhythmic heart rates. The pitch was also adapted to the heart rate, ranging from 0.2 to 0.43. Volume and flow rate of contrast material (Ultravist 370, Schering AG) were adapted to the patient's body weight. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DSCT in the detection or exclusion of significant CAD (ie, stenoses >50%) were evaluated on a per-patient and per-segment basis. RESULTS: All 35 CT angiograms were of diagnostic image quality. QCA demonstrated significant CAD in 48% (n = 17) and nonsignificant disease or normal coronary angiograms in 52% (n = 18) of the patients. Sensitivity, specificity, PPV, and NPV of DSCT on a per-patient basis were 100%, 89%, 89%, and 100%, respectively. On a per-segment basis, 473 of 481 coronary artery segments were assessable (98%). QCA demonstrated stenoses >50% in 32 segments (7%), and no disease or nonsignificant disease in 433 segments (93%). For the detection of stenoses >50% on a per-segment basis, DSCT showed a sensitivity, specificity, PPV, and NPV of 88%, 98%, 78%, and 99%, respectively. CONCLUSIONS: The comparison of coronary DSCT with QCA shows a very robust image quality and a high diagnostic accuracy in a patient-based as well as a per-segment analysis. Maximal sensitivity and NPV in the per-patient analysis show the strength of the technique in ruling out significant CAD.

Retrospective motion gating in small animal CT of mice and rats.

OBJECTIVES: Implementation and evaluation of retrospective respiratory and cardiac gating of mice and rats using a flat-panel volume-CT prototype (fpVCT). MATERIALS AND METHODS: Respiratory and cardiac gating was implemented by equipping a fpVCT with a small animal monitoring unit. ECG and breathing excursions were recorded and 2 binary gating signals derived. Mice and rats were scanned continuously over 80 seconds after administration of blood-pool contrast media. Projections were chosen to reconstruct volumes that fall within defined phases of the cardiac/respiratory cycle. RESULTS: Multireader analysis indicated that in gated still images motion artifacts were strongly reduced and diaphragm, tracheobronchial tract, heart, and vessels sharply delineated. From 4D series, functional data such as respiratory tidal volume and cardiac ejection fraction were calculated and matched well with values known from literature. DISCUSSION: Implementation of retrospective gating in fpVCT improves image quality and opens new perspectives for functional cardiac and lung imaging in small animals.

Assessment of morphological MRI for pulmonary changes in cystic fibrosis (CF) patients: comparison to thin-section CT and chest x-ray.

OBJECTIVES: As pulmonary complications are life limiting in patients with cystic fibrosis (CF), repeated chest imaging [chest x-ray, computed tomography (CT)] is needed for follow up. With the continuously rising life expectancy of CF patients, magnetic resonance imaging (MRI) as a radiation-free imaging modality might become more and more attractive. The goal of this study was to prospectively assess the value of MRI for evaluation of morphologic pulmonary CF-changes in comparison to established imaging modalities. MATERIALS AND METHODS: Thirty-one CF patients (19 female, 12 male; mean age 16.7 years) with stable lung disease were examined by MRI: HASTE, coronal/transversal (TR/TE/alpha/TA: infinite/28 ms/180 degrees /18 s), multi-detector computed tomography (MDCT) (30 patients): 120 kV, dose modulated mAs, and chest x-ray (21 patients). Image evaluation: random order, 4 chest radiologists in consensus; chest x-ray: modified Chrispin-Norman score; CT and MRI: modified Helbich score. The maximal attainable score for chest x-ray was 34, for MRI and CT 25. Median scores, Pearson correlation coefficients, Bland-Altman plots, and concordance of MRI to CT on a lobar and segmental basis were calculated. RESULTS: The median MRI and MDCT scores were 13 (min 3, max 20) respectively 13.5 (min 0, max 20). The median chest x-ray score was 14 (min 5, max 32). Pearson correlation coefficients: MRI/CT = 0.80, P < 0.0001; MRI/chest x-ray = 0.63, P < 0.0018; chest x-ray/CT = 0.75, P < 0.0001. The median lobe related concordance was 80% for bronchiectasis, 77% for mucus plugging, 93%, for sacculation/abscesses, and 100% for collapse/consolidation. CONCLUSIONS: Morphologic MRI of the lung in CF patients demonstrates comparable results to MDCT and chest x-ray. Because radiation exposure is an issue in CF patients, MRI might have the ability to be used as an appropriate alternative method for pulmonary imaging.