A radiomics pipeline dedicated to Breast MRI: validation on a multi-scanner phantom study

Magnetic Resonance Materials in Physics, Biology and Medicine - Quantitative analysis in MRI is challenging due to variabilities in intensity distributions across patients, acquisitions and...     

Statistical distribution of factors and factor images in factor analysis of medical image sequences

From a time or energy image sequence, factor analysis of medical image sequences (FAMIS) estimates factors, representing kinetics or spectra in a given physiological compartment, and associated factor images, showing the compartments corresponding to each curve. In this paper, we show that the statistical properties of factor images and associated factors can be determined using a well known result from elementary probability theory. Numerical experiments are conducted to demonstrate that the variance observed in factor images can be predicted when the statistical properties of the original data are known. It is shown how these theoretical results can be used to relax the non-negativity constraints during FAMIS oblique analysis and to improve the quantitative interpretation of the factor images by associating a confidence interval with each pixel value.     

Erectile response to intracavernous injection of linsidomine in 38 impotent patients. Comparison with prostaglandin E1

OBJECTIVE: To test the effects of intracavernous injection of Linsidomine, an NO donor, and to compare the results to those obtained after injection of PGE1. MATERIAL AND METHODS: 38 subjects with erectile insufficiency received an intracavernous injection of 10 micrograms of PGE1, followed by an intracavernous injection of 1 mg of linsidomine at least 3 days later. The erectile response after linsidomine was compared to that obtained after PGE1. 21 patients were investigated by Duplex ultrasound after each injection. RESULTS: Linsidomine induced complete rigidity in 4 subjects considered to suffer from psychogenic impotence (versus 11 subjects with PGE1) and 1 subject considered to suffer from arterial disease (versus 8 subjects with PGE1). The maximal systolic velocities recorded after linsidomine were significantly correlated with those measured in the same subject after PGE1. The resistance index was not modified after linsidomine injection. CONCLUSION: Our study confirms the impact of linsidomine on the local mechanisms of erection. It shows that linsidomine is much less effective than PGE1, but nevertheless has a place in the therapeutic armamentarium of impotence.     

Nonsupervised ranking of different segmentation approaches: application to the estimation of the left ventricular ejection fraction from cardiac cine MRI sequences

A statistical methodology is proposed to rank several estimation methods of a relevant clinical parameter when no gold standard is available. Based on a regression without truth method, the proposed approach was applied to rank eight methods without using any a priori information regarding the reliability of each method and its degree of automation. It was only based on a prior concerning the statistical distribution of the parameter of interest in the database. The ranking of the methods relies on figures of merit derived from the regression and computed using a bootstrap process. The methodology was applied to the estimation of the left ventricular ejection fraction derived from cardiac magnetic resonance images segmented using eight approaches with different degrees of automation: three segmentations were entirely manually performed and the others were variously automated. The ranking of methods was consistent with the expected performance of the estimation methods: the most accurate estimates of the ejection fraction were obtained using manual segmentations. The robustness of the ranking was demonstrated when at least three methods were compared. These results suggest that the proposed statistical approach might be helpful to assess the performance of estimation methods on clinical data for which no gold standard is available.