Apathy in depression: An arterial spin labeling perfusion MRI study

INTRODUCTION

Apathy, as defined as a deficit in goal-directed behaviors, is a critical clinical dimension in depression associated with chronic impairment. Little is known about its cerebral perfusion specificities in depression. To explore neurovascular mechanisms underpinning apathy in depression by pseudo-continuous arterial spin labeling (pCASL) magnetic resonance imaging (MRI).

METHODS

Perfusion imaging analysis was performed on 90 depressed patients included in a prospective study between November 2014 and February 2017. Imaging data included anatomical 3D T1-weighted and perfusion pCASL sequences. A multiple regression analysis relating the quantified cerebral blood flow (CBF) in different regions of interest defined from the FreeSurfer atlas, to the Apathy Evaluation Scale (AES) total score was conducted.

RESULTS

After confound adjustment (demographics, disease and clinical characteristics) and correction for multiple comparisons, we observed a strong negative relationship between the CBF in the left anterior cingulate cortex (ACC) and the AES score (standardized beta = -0.74, corrected p value = 0.0008).

CONCLUSION

Our results emphasized the left ACC as a key region involved in apathy severity in a population of depressed participants. Perfusion correlates of apathy in depression evidenced in this study may contribute to characterize different phenotypes of depression.

DWI-Based Algorithm to Predict Disability in Patients Treated with Thrombectomy for Acute Stroke

BACKGROUND AND PURPOSE

The reasons for poor clinical outcome after thrombectomy for acute stroke, concerning around half of all patients, are misunderstood. We developed a hierarchic algorithm based on DWI to better identify patients at high risk of disability.

MATERIALS AND METHODS

Our single-center, retrospective study included consecutive patients with acute ischemic stroke who underwent thrombectomy for large anterior artery occlusion and underwent pretreatment DWI. The primary outcome was the mRS at 3 months after stroke onset. Multivariable regression was used to identify independent clinical and imaging predictors of poor prognosis (mRS > 2) at 3 months, and a hierarchic algorithm predictive of disability was developed.

RESULTS

A total of 149 patients were analyzed. In decreasing importance, DWI lesion volume of >80 mL, baseline NIHSS score of >14, age older than 75 years, and time from stroke onset to groin puncture of >4 hours were independent predictors of poor prognosis. The predictive hierarchic algorithm developed from the multivariate analysis predicted the risk of disability at 3 months for up to 100% of patients with a high predictive value. The area under the receiver operating characteristic curve was 0.87.

CONCLUSIONS

The DWI-based hierarchic algorithm we developed is highly predictive of disability at 3 months after thrombectomy and is easy to use in routine practice.

[Calculation of optimized and individualized hip prosthesis. A study of feasibility]

As logical consequence of a series of basic research studies on human femoral bones with unipodal support and under static stress, performed with physicomathematic modelling methods (finite-elements method) then confirmed by direct visualization of deformations resulting from such stress using holographic interferometry, the authors have worked on the definition of an optimized and individualized hip prosthesis. Thick CT sections digitized with a table and entered into a specially programmed computer allowed three-dimensional modelling of the femur as a volume, i.e. with its external contour and its medullary canal, and therefore of the implantable space. The prosthesis was then defined taking a number of hypotheses into account: necessity to regularize cortical bone spicules inside spongious bone, which are so often present opposite the rough line, partial machining at the level of the calcar, reduced tail length, presence or absence of collar. Thus an optimized and individualized prosthesis was defined. A prototype corresponding to a given femoral bone could then have been produced. However, the authors found it preferable to use simulation with computer synthetic images to check easy insertion and removal.

[Application of a 3-dimensional model using computer technology in the study of the structure of the mandible]

Previous studies employing a plane "model" on the hemi-mandible confirmed the concept of a "bees-nest" structure of the mandible. As this plane model did not permit demonstration of maximal zones of iso-stress in the horizontal rami, the whole mandible was examined by means of a three-dimensional model. This gave more precise information, and thus produced more realistic results confirming previous findings. This new reliable type of model can be employed for any such exploratory procedure, and in studies totally different from those for which it was developed.

[Plea for the application of statistical methods by computer to stomatological research]

In face of the double reflex of fascination and defiance which is right away created by statistical methods by computers, the authors have attempted by means of precise examples to demystify these methods by recalling: 1) That computer statistics can be defined as the association of a service and a machine, the combination should be considered as an instrument and only an instrument. 2) That the application of computer statistics to odonto-stomatological research of course evidently enables the resolution of problems which would be otherwise insoluble, but above all considerably enlarges the field of research by rendering visible phenomena which would otherwise remain hidden. In this way, statistical methods by computer can be compared with the microscope; a low magnification with the optical microscope justifies only an overall view of the section while changing to higher magnifications permits the demonstration of details which would remain unsuspected. Use of the electromicroscope opens up another world for research. 3) In the same way as the biologist who uses the microscope, if he knows the principle of it is not in so far a specialist in optics, neither does the research woker who uses statistics necessarily have to be a trained statistician, on the one condition that evidently he disposes of professional computer logistics. This is the case of the ACB (Nantes) rush technical units, who cosigned this work, where the engineers who pose the problems to be resolved and emit the working hypotheses from the results supplied by the statistical studies are not the same people who carry out these very studies. 4) An essential fact, the research worker's independance is complete, only he can pose the problems and emit the hypothesis from the correlation, i. e. point of fact concomitance between the various isolated parameters. It therefore does not seem that weighty statistical techniques presently occupy the place of choice which should be theirs in stomatological research and more particularly in research concerning growth and development of the face where their use seems to be electively implied in face of the number and complexity of the parameters looked at.