Multimodality Non-rigid Image Registration for Planning, Targeting and Monitoring During CT-Guided Percutaneous Liver Tumor Cryoablation

Rationale and Objectives: To develop non-rigid image registration between pre-procedure contrast enhanced MR images and intra-procedure unenhanced CT images, to enhance tumor visualization and localization during CT-guided liver tumor cryoablation procedures. Materials and Methods: After IRB approval, a non-rigid registration (NRR) technique was evaluated with different pre-processing steps and algorithm parameters and compared to a standard rigid registration (RR) approach. The Dice Similarity Coefficient (DSC), Target Registration Error (TRE), 95% Hausdorff distance (HD) and total registration time (minutes) were compared using a two-sided Student’s t-test. The entire registration method was then applied during five CT-guided liver cryoablation cases with the intra-procedural CT data transmitted directly from the CT scanner, with both accuracy and registration time evaluated. Results: Selected optimal parameters for registration were section thickness of 5mm, cropping the field of view to 66% of its original size, manual segmentation of the liver, B-spline control grid of 5×5×5 and spatial sampling of 50,000 pixels. Mean 95% HD of 3.3mm (2.5x improvement compared to RR, p<0.05); mean DSC metric of 0.97 (13% increase); and mean TRE of 4.1mm (2.7x reduction) were measured. During the cryoablation procedure registration between the pre-procedure MR and the planning intra-procedure CT took a mean time of 10.6 minutes, the MR to targeting CT image took 4 minutes and MR to monitoring CT took 4.3 minutes. Mean registration accuracy was under 3.4mm. Conclusion: Non-rigid registration allowed improved visualization of the tumor during interventional planning, targeting and evaluation of tumor coverage by the ice ball. Future work is focused on reducing segmentation time to make the method more clinically acceptable

Controlled Hahn–Mazurkiewicz Theorem and some new dimension functions of Peano continua

AbstractGiven a metric Peano continuum X we introduce and study the Hölder Dimension Hö-dim(X)=inf{d: there is a 1d-Hölder onto map f:[0,1]→X} of X as well as its topological counterpart Hö-dim(X)=inf{Hö-dim(X,d):d is an admissible metric for X}. We show that for each convex metric continuum X the dimension Hö-dim(X) equals the fractal dimension of X. The topological Hölder dimension Hö-dim(Mn) of the n-dimensional universal Menger cube Mn equals n. On the other hand, there are 1-dimensional rim-finite Peano continua X with arbitrary prescribed Hö-dim(X)⩾1

COMPARISON OF INNOCENT CARDIAC MURMURS OF CHILDHOOD WITH CARDIAC MURMURS IN HIGH OUTPUT STATES

Cardiac murmurs have been recorded in patients in a number of clinical states which give rise to systolic cardiac murmurs, in which no abnormalities of the intracardiac pathway or direction of blood flow are known to exist: uncomplicated congenital heart block, chronic anemia, pregnancy, arteriovenous fistula, and hyperthyroidism. These recordings have been examined in the cathode-ray oscillograph and sound spectrograph. The oscillograms of murmurs of each of these groups have been found to be of the same general category, a basic wave of relatively low frequency (90-130 c.p.s.) with a variable amount of distortion by higher-frequency transient vibrations. The spectrograms of the murmurs of each of these groups have again been found to have the same general pattern: a relatively dense spectrogram limited to a fairly well-defined area, largely below the 250-c.p.s. level. Thus both the oscillograms and spectrograms of these murmurs showed the characteristics found in earlier studies of the innocent cardiac murmurs of childhood in contrast to the characteristics which have been found in murmurs of a number of lesions of rheumatic and congenital heart disease. Since the clinical states included in the present study have in common an increased stroke volume, this has been taken as supporting evidence of the thesis that the common innocent murmurs of childhood are caused by the vibration, at its natural period, of some structure in the cardiac wall or great vessels, arising from the ejection of an unusual volume of blood from the heart in systole or the greater velocity of ejected blood under these circumstances.</jats:p