Purpose To investigate the effects of distortion and inhomogeneity correction on brain morphometry with 3T MRI. Materials and Methods The subjects were 16 normal male volunteer (29.4 ± 4.0, 24-38 years old). MRI data were obtained using a 3T scanner (Signa HDx3.0T, GE Healthcare) at the University of Tokyo Hospital. 3D fast spoiled-gradient recalled acquisition in the steady state (3D-FSPGR) wa...

The dynamics and homogeneity of the QT interval have been used as indicators of susceptibility to ventricular arrhythmias. We determined the relationship between QT intervals and heart rate during exercise testing and subsequent recovery in 18 healthy children. The QT intervals were measured to the apex (early QT), to the end (total QT), and from the apex to the end of the T wave (late QT) (inh...

The article examines: (i) the reasons of error due to thermoelectric inhomogeneity of electrodes of thermocouples acquired during prolonged use; (ii) the neural network method of error correction based on a generalization of verification results in several temperature fields; (iii) the method of investigating the impact of changing the speed of the conversion characteristic drift of thermocoupl...

Accurate quantification of R₂(*) (=1/T₂(*)) is important for many applications in neuroimaging. However, R₂(*) measurements made using conventional multi-echo gradient echo imaging are hampered by macroscopic field inhomogeneities. Several methods for compensation of macroscopic field inhomogeneities have been introduced, most of them requiring increased scan time. In this paper, an R₂(*) estim...

MR images usually present grey level inhomogeneities which are a problem of significant importance. Eliminating these inhomogeneities is not an easy problem and has been studied and discussed in several previous publications. Most of those approaches are based on segmentation processes. The algorithm presented in this paper has the advantage that it does not involve any segmentation step. Inste...

We present a technique for model-independent estimation of the inhomogeneity effect across multiple different acquisitions of the same subject, on the assumption of equal inhomogeneities in each image. The technique operates by integration of smoothed estimates of the local derivative of the bias field. Combination of evidence from multiple images is achieved at the derivative estimation stage ...

Head motion is the major source of error in measuring intensity changes related to given stimuli in fMRI. The effects of head motion are image shifts and field inhomogeneity variations which cause local changes in geometric distortions. The previously developed motion correction method, mapping slice-to-volume (MSV), retrospectively remaps slices that are shifted by head motion to their spatial...