X-ray detection of structural orientation in human articular cartilage

OBJECTIVE: To determine the feasibility of detecting the structural orientation in cartilage with Diffraction Enhanced X-Ray Imaging.DESIGN: Human tali and femoral head specimens were Diffraction Enhanced X-Ray Imaged (DEI) at the SYRMEP beamline at Elettra at various energy levels to detect the architectural arrangement of collagen within cartilage. DEI utilizes a monochromatic and highly collimated beam, with an analyzer crystal that selectively weights out photons according to the angle they have been deviated with respect to the original direction. This provides images of very high contrast, and with the rejection of X-ray scatter.RESULTS: DEI allowed the visualization of articular cartilage and a structural orientation, resembling arcades, within.CONCLUSION: Our diffraction enhanced images represent the first radiographic detection of the structural orientation in cartilage. Our data are in line with previous studies on the structural organization of joint cartilage. They confirm the model of a vaulting system of collagen fiber bundles interrupted by proteoglycan aggregates.     

Blood transfers infectious immunologic tolerance in MHC-incompatible heart transplantation in rats.

"Infectious tolerance" or inducing immunologic tolerance of infection in allografts is still poorly understood. We investigated whether transfusing blood from LEW.1A rats tolerant of LEW.1W hearts could transmit tolerance to naive LEW.1A rats. In 4 of 6 cases, transfusing blood from tolerant animals was followed by immunologic tolerance of heart transplants from LEW.1W donor rats in LEW.1A recipient animals, whereas transplanting heart grafts that were tolerated in previous transplantations across MHC barriers did not transfer tolerance in major histocompatibility complex (MHC)-incompatible animals. We conclude that in rat heart transplantation, the transfer of immunologic tolerance can be enhanced by transfusing blood from tolerant animals to naive animals before transplantation across MHC barriers.     

Accelerated point spread function mapping using signal modeling for accurate echo‐planar imaging geometric distortion correction

Echo‐planar imaging is a fast and commonly used magnetic resonance imaging technique with applications in diffusion weighted and functional MRI. Fast data acquisition in echo‐planar imaging is accomplished by the extended readout, which also introduces sensitivity to off‐resonance effects such as amplitude of static (polarizing) field inhomogeneities and eddy‐currents. These off‐resonance effects produce geometric distortions in the corresponding echo‐planar images. To correct for these distortions, an acceleration of point spread function (PSF) acquisition using a special sampling pattern is presented in this work. The proposed technique allows for reliable and fully automated distortion correction of echo‐planar images at a field strength of 3 T. Additionally, a new approach to visualize and determine the distortions in a hybrid (x, y, k_PSF) three‐dimensional space is proposed. The accuracy and robustness of the proposed technique is demonstrated in phantom and in vivo experiments. The accuracy of the presented method here is compared to previous techniques for echo‐planar imaging distortion correction such as PLACE. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

Proton MRI in the evaluation of pulmonary sarcoidosis: Comparison to chest CT

Purpose

The purpose of this study was to determine the feasibility of proton MRI of the lung in sarcoidosis patients and the agreement between the imaging appearance of pulmonary sarcoidosis on MRI and CT.

Materials and methods

Chest CT scans and dedicated pulmonary MRI scans (including HASTE, VIBE, and TrueFISP sequences) were performed within 90 days of each other in 29 patients. The scans were scored for gross parenchymal opacification, reticulation, nodules, and masses using a 3-point lobar scale. Total and subset scores for corresponding MRI and CT scans were compared using the Spearman correlation test, Bland–Altman plots, and Cohen's quadratic-weighted kappa analysis. MRI scores were compared to CT by lobe and disease category, using percentage agreement, Spearman rank correlation, and Cohen's quadratic-weighted kappa.

Results

The mean (±s.d.) time between MRI and CT scans was 33 ± 32 days. There was substantial correlation and agreement between total disease scoring on MRI and CT with a Spearman correlation coefficient of 0.774 (p < 0.0001) and a Cohen's weighted kappa score of 0.646. Correlation and agreement were highest for gross parenchymal opacification (0.695, 0.528) and reticulation (0.609, 0.445), and lowest in the setting of nodules (0.501, 0.305). Agreement testing was not performed for mass scores due to low prevalence. Upper lobe scoring on MRI and CT demonstrated greater agreement compared to the lower lobes (average difference in Cohen's weighted kappa score of 0.112).

Conclusion

There is substantial correlation and agreement between MRI and CT in the scoring of pulmonary sarcoidosis, though MRI evaluation in the upper lobes may be more accurate than in the lower lobes.     

Comparison of ventricular tachyarrhythmia characteristics in patients with idiopathic dilated or ischemic cardiomyopathy and defibrillators implanted for primary prevention

Background:

Implantable cardioverter‐defibrillator (ICD) therapy for primary prevention is well established in ischemic cardiomyopathy (ICM). Data on the role of ICDs in patients with dilated cardiomyopathy (DCM) and no history of ventricular tachyarrhythmia (VT/VF) are more limited.

Hypothesis:

DCM patients with an impaired left ventricular ejection fraction (LVEF) still represent a low arrhythmic risk subgroup in clinical practice.

Methods:

ICD stored data of DCM patients with an LVEF ≤35% was compared to data of ICM patients meeting Multicenter Automatic Defibrillator Implantation Trial (MADIT) eligibility criteria. VT/VF occurrences and electrical storm (ES) events were analyzed.

Results:

There were 652 patients followed for 50.9 ± 33.9 months. There were 1978 VT and 241 VF episodes analyzed in 66 out of 203 patients (32.5%) with DCM and in 118 out of 449 patients (26.3%, P = 0.209) with ICM. Freedom of appropriate ICD treatment due to VT/VF or ES events did not differ in both patient populations (log‐rank, P>0.05). In patients presenting with VT/VF episodes, mean event rates were comparable in both patient populations (3.2 ± 14.1 for DCM and VT vs 3 ± 13.9 for ICM and VT [P = 0.855], 0.4 ± 1.3 for DCM and VF vs 0.4 ± 1.8 for ICM and VF [P = 0.763], and 0.2 ± 0.7 for DCM and ES vs 0.2 ± 1 for ICM and ES [P = 0.666]).

Conclusions:

DCM patients with prophylactic ICDs implanted due to heart failure and patients fulfilling MADIT criteria reveal comparable patterns of VT/VF/ES events during long‐term follow‐up. Incidence, mean number of events, and time to first event did not differ significantly. Findings support the current guidelines for prophylactic ICD therapy in DCM patients with heart failure. © 2011 Wiley Periodicals, Inc. The authors have no funding, financial relationships, or conflicts of interest to disclose.