HF-rTMS treatment in medication-resistant melancholic depression: results from 18FDG-PET brain imaging.

INTRODUCTION: High frequency repetitive transcranial magnetic stimulation (HF-rTMS) of the left dorsolateral prefrontal cortex (DLPFC) might be a promising strategy to treat depression, but not all patients show a positive outcome. OBJECTIVE: In this open study, we evaluate whether a favorable HF-rTMS treatment outcome could be predicted by baseline prefrontal brain glucose metabolism (CMRglc), measured by 18fluorodeoxyglucose positron emission tomography (18FDG-PET). METHODS: A sample of 21 antidepressant-free, treatment-resistant depression (TRD) patients of the melancholic subtype received 10 sessions of HF-rTMS delivered on the left DLPFC. Patients underwent a static 18FDG-PET before and after HF-rTMS treatment. RESULTS: Forty-three percent of the patients showed a reduction of at least 50% on their Hamilton Rating Scale for Depression scores. Higher baseline metabolic activities in the DLPFC and the anterior cingulate cortex (ACC) were associated with better clinical outcome. Successful HF-rTMS treatment was related to metabolic changes in subdivisions of the ACC (Brodmann areas 24 and 32). CONCLUSION: This biological impact of HF-rTMS on regional brain CMRglc explains to some extent how HF-rTMS may improve moods in TRD patients. Larger sham-controlled HF-rTMS treatment studies are needed to confirm these results.

Typetesting of physical characteristics of digital mammography systems for screening within the Flemish breast cancer screening programme.

To investigate compliance with the acceptance criteria of the European guidelines for quality assurance in breast cancer screening, a typetesting programme of the physical characteristics of digital mammography systems based on direct readout (DR) technology or computed radiography (CR) was organised and executed within the Flemish breast cancer screening programme. While in general image quality/dose characteristics of flat panel DR systems passed the acceptance criteria more easily than CR systems, the slit-scanning direct photon counting system included in present study was outstanding in combining a very low dose with a good image quality. The data obtained up to now indicate the necessity of retuning the AEC for DR systems according to constant contrast to noise ratio (CNR) over the whole range of PMMA thicknesses (20-70 mm) to improve image quality in imaging breasts of large thickness at the cost of higher doses. For the two CR systems which passed the typetesting procedure dose levels do not allow a similar improvement of CNR for thick objects for these systems. The obtained results highlight the importance of the use of high Z target/filter combinations in X-ray generating systems for imaging thick objects to meet the image quality/dose criteria. With respect to image display aspects high-quality 3-megapixel LCD monitors succeeded also in the typetesting procedure in addition to 5-megapixel monitors. However, as zooming and scrolling are necessary for 3-megapixel monitors to get the full resolution capabilities of the image capture system, 5-megapixel monitors are preferred in a busy screening environment.

Double-dosimetry algorithm for workers in interventional radiology.

Based on double-dosemeter readings, a conservative effective dose (E) estimation algorithm for lead apron workers in interventional radiology is proposed. Typical radiation conditions for various exposure geometries were simulated using the MCNPX 2.4.0 code. The simulation model consisted of an X-ray source and image intensifier, a patient phantom and a voxelised staff member phantom with lead apron. The effective staff dose and dosemeter readings for several positions of the worker were calculated. The effective dose to a physician, positioned in close proximity to the primary beam, can be estimated within a 10% underestimation margin by E = 1.64 H(p)(10)thorax,under + 0.075 H(p)(10)neck,over. The dose to the eye lens can be estimated by a dosemeter reading at collar level (R2 = 0.98).

The influence of rTMS over the right dorsolateral prefrontal cortex on top-down attentional processes.

Repetitive Transcranial Magnetic Stimulation (rTMS) provides a unique opportunity to study causal relationships between activity in the dorsolateral prefrontal cortex (DLPFC) and executive functioning, by modulating brain activity in SHAM controlled designs. We devised a new Stroop task paradigm in which subjects must engage in both strategic and automatic attentional processes. In the current experiment, we manipulated subjects' expectancies for incongruent stimuli. Previous research demonstrated that when subjects have a high level of expectancy that a stimulus will be incongruent, they are able to strategically adjust the relative influence of word reading on color naming. The effect of high frequency (HF) rTMS on Stroop performance of 20 right-handed healthy female volunteers was tested using a double blind within subjects design by counterbalanced crossover sham (placebo) and active rTMS over the right DLPFC. Since mood remained unchanged after rTMS, the Stroop data could be evaluated independent of mood changes. Only in the high expectancy condition, we found a decreased response time to both congruent and incongruent trials on the Stroop task performance after HF rTMS. The SHAM placebo condition yielded no effects. We conclude that high frequency stimulation over the right DLPFC has an effect on top-down attentional processes by modulating the attentional set.