Ultra high spatial and temporal resolution breast imaging at 7T.

There is a need to obtain higher specificity in the detection of breast lesions using MRI. To address this need, Dynamic Contrast-Enhanced (DCE) MRI has been combined with other structural and functional MRI techniques. Unfortunately, owing to time constraints structural images at ultra-high spatial resolution can generally not be obtained during contrast uptake, whereas the relatively low spatial resolution of functional imaging (e.g. diffusion and perfusion) limits the detection of small lesions. To be able to increase spatial as well as temporal resolution simultaneously, the sensitivity of MR detection needs to increase as well as the ability to effectively accelerate the acquisition. The required gain in signal-to-noise ratio (SNR) can be obtained at 7T, whereas acceleration can be obtained with high-density receiver coil arrays. In this case, morphological imaging can be merged with DCE-MRI, and other functional techniques can be obtained at higher spatial resolution, and with less distortion [e.g. Diffusion Weighted Imaging (DWI)]. To test the feasibility of this concept, we developed a unilateral breast coil for 7T. It comprises a volume optimized dual-channel transmit coil combined with a 30-channel receive array coil. The high density of small coil elements enabled efficient acceleration in any direction to acquire ultra high spatial resolution MRI of close to 0.6 mm isotropic detail within a temporal resolution of 69 s, high spatial resolution MRI of 1.5 mm isotropic within an ultra high temporal resolution of 6.7 s and low distortion DWI at 7T, all validated in phantoms, healthy volunteers and a patient with a lesion in the right breast classified as Breast Imaging Reporting and Data System (BI-RADS) IV.

Pushing the limits of high-resolution functional MRI using a simple high-density multi-element coil design.

Recent studies have shown that functional MRI (fMRI) can be sensitive to the laminar and columnar organization of the cortex based on differences in the spatial and temporal characteristics of the blood oxygenation level-dependent (BOLD) signal originating from the macrovasculature and the neuronal-specific microvasculature. Human fMRI studies at this scale of the cortical architecture, however, are very rare because the high spatial/temporal resolution required to explore these properties of the BOLD signal are limited by the signal-to-noise ratio. Here, we show that it is possible to detect BOLD signal changes at an isotropic spatial resolution as high as 0.55 mm at 7 T using a high-density multi-element surface coil with minimal electronics, which allows close proximity to the head. The coil comprises of very small, 1 × 2-cm(2) , elements arranged in four flexible modules of four elements each (16-channel) that can be positioned within 1 mm from the head. As a result of this proximity, tissue losses were five-fold greater than coil losses and sufficient to exclude preamplifier decoupling. When compared with a standard 16-channel head coil, the BOLD sensitivity was approximately 2.2-fold higher for a high spatial/temporal resolution (1 mm isotropic/0.4 s), multi-slice, echo planar acquisition, and approximately three- and six-fold higher for three-dimensional echo planar images acquired with isotropic resolutions of 0.7 and 0.55 mm, respectively. Improvements in parallel imaging performance (geometry factor) were up to around 1.5-fold with increasing acceleration factor, and improvements in fMRI detectability (temporal signal-to-noise ratio) were up to around four-fold depending on the distance to the coil. Although deeper lying structures may not benefit from the design, most fMRI questions pertain to the neocortex which lies within approximately 4 cm from the surface. These results suggest that the resolution of fMRI (at 7 T) can approximate levels that are closer to the spatial/temporal scale of the fundamental functional organization of the human cortex using a simple high-density coil design for high sensitivity.

Novel approach to combined defaecation and micturition disorders with rectovaginovesicopexy.

BACKGROUND: This study was conducted to investigate the results of rectovaginovesicopexy (RVVP) in patients with combined defaecation and micturition disorders. RVVP was developed from a standard procedure for different forms of defaecation disorders (the rectovaginopexy (RVP)). It is only a limited extension to the RVP and results in elevation of all three pelvic compartments. METHODS: In a consecutive series of 25 patients the effects or RVVP were evaluated prospectively. Information about the clinical history and results was obtained by a standard questionnaire filled out before and 3 and 12 months after operation. Dynamic defaecography was performed before and 3 months after RVVP. Before operation urodynamic studies were conducted. RESULTS: RVVP improved constipation (14 of 18 patients improved, P = 0.001), faecal incontinence (11 of 16 patients improved, P = 0.005) and dysfunctional voiding (ten of 16 patients improved, P = 0.07) without induction of these disorders. Overall urinary incontinence improved in 11 of 22 patients (P = 0.18), with deterioration of urinary incontinence in three and induction of urinary incontinence in two of the patients. Patients with isolated urinary stress incontinence fared better (eight of 13 patients improved) than those with mixed urinary incontinence. CONCLUSION: RVVP provides satisfactory improvement of combined defaecation and micturition disorders. The benefits of a limited extension of the RVP seem to outweigh potential side-effects such as deterioration or de novo defaecation or micturition disorders.