A simple apparatus for safety assessment of magnetically induced torque on active implantable medical devices (AIMDs) under 1.5 T and 3.0 T MRI.

OBJECTIVE: Our goal is to design and validate a simple apparatus for the safety assessments of magnetically induced torques by four active implantable medical devices (AIMDs) in 1.5 T and 3.0 T magnetic resonance imaging (MRI) environments. MATERIALS AND METHODS: A simple apparatus was designed to measure the magnetically induced torque. Before testing the apparatus, its effectiveness was first evaluated with a commercially available weights. The torque values of the four AIMDs, namely implantable cardioverter defibrillator (ICD), pacemaker, bone conduction implant, and cochlear implant, under 1.5 T and 3.0 T MRI environments were measured and compared with established international standard. RESULTS: The ICD, pacemaker, bone conduction implant, and cochlear implant had average torques of 1.405, 0.255, 9.460, and 5.490 N·cm under 1.5 T MRI and 2.950, 0.668, 14.618, and 11.484 N·cm under 3.0 T MRI, respectively. DISCUSSION: The apparatus developed in this study was verified to be feasible for measuring magnetically induced torques, with tests on four types of AIMDs under 1.5 T and 3.0 T MRI environments. Although the designed structure is simple, the apparatus was shown to measure torque values of AIMDs under MRI accurately.

Comparison of a novel algorithm quantitatively estimating epifascial fibrosis in three-dimensional computed tomography images to other clinical lymphedema grading methods.

No method has yet been approved for detecting lymphedema fibrosis before its progression. This study assessed the feasibility of computed tomography-based estimation of fibrosis. This observational, cross-sectional study included patients with lymphedema affecting one limb. Three types (maximum, mean, minimum) of computed tomography reticulation indexes were digitally calculated from trans-axial images using absorptive values, and the computed tomography reticulation indexes compared with clinical scales and measurements. Of 326 patients evaluated by at least one of lymphoscintigraphy, bio-electrical impedance, and computed tomography, 24 were evaluated by all three. The mean number of computed tomography scans in these patients was 109. Sixteen patients had breast cancer, seven had gynecologic cancers, and one had primary lymphedema. Mean computed tomography reticulation index (r = 0.52, p < 0.01) and maximal computed tomography reticulation index (r = 0.45, p < 0.05) were significantly associated with time from initial limb swelling to computed tomography. Mean computed tomography reticulation index (r = 0.86, p < 0.01), minimal computed tomography reticulation index (r = 0.79, p < 0.01), and maximal computed tomography reticulation index (r = 0.68, p < 0.01) were significantly associated with International Society of Lymphedema substage. Minimal computed tomography reticulation index correlated with 1-kHz-based bio-electrical impedance ratio (r = -0.46, p < 0.05) and with standardized proximal limb circumference difference ratio (r = 0.45, p < 0.05) of both limbs. Maximal computed tomography reticulation index had a sensitivity of 0.78, specificity of 0.60, and areas under the curve of 0.66 in detecting lymphoscintigraphic stage IV. The algorithm utilizing three-dimensional computed tomography images of epifascial fibrosis may be used as a marker for lymphedema duration, limb swelling, International Society of Lymphedema substage, and interstitial lymphatic fluids of lymphedema. The current approach shows promise in providing an additional method to assist in characterizing and monitoring lymphedema patients.

A voice coil actuator driven active vibration isolation system with the consideration of flexible modes.

We develop a four-mount active vibration isolation system (AVIS) using voice coil actuators. The flexible body modes in the upper plate of the AVIS can cause an instability problem due to control signal whose frequency is close to the resonant frequency of the flexible modes. The loop shaping technique is applied to reduce the amplitude of the control signal. We investigate the performances of the active vibration isolation system proposed in the word in the time domain and frequency domain by comparing to the passive isolation system.

Cell Attachment on Inside-Outside Surface and Cell Encapsulation in Wall of Microscopic Tubular Scaffolds for Vascular Tissue-Like Formation.

By using the microfluidic spinning technology we generated tiny hydrogel tubular scaffolds. Fibroblast (NIH/3T3) cell cultures were performed for seventeen days to demonstrate the potential of cell attachment on surfaces and encapsulation in the wall of he microscopic scaffolds for blood vessel-like structure forming. Over theculture period, the NIH/3T3 confluence reached around 80\%, and 100\% on the inside and outside scaffolds' surface respectively while cells proliferated and coalesced in cell group in the hydrogel wall. These results could further be applied to endothelial co-culturing for forming engineered blood vessel.