Sodium MR Neuroimaging.

Sodium MR imaging has the potential to complement routine proton MR imaging examinations with the goal of improving diagnosis, disease characterization, and clinical monitoring in neurologic diseases. In the past, the utility and exploration of sodium MR imaging as a valuable clinical tool have been limited due to the extremely low MR signal, but with recent improvements in imaging techniques and hardware, sodium MR imaging is on the verge of becoming clinically realistic for conditions that include brain tumors, ischemic stroke, and epilepsy. In this review, we briefly describe the fundamental physics of sodium MR imaging tailored to the neuroradiologist, focusing on the basics necessary to understand factors that play into making sodium MR imaging feasible for clinical settings and describing current controversies in the field. We will also discuss the current state of the field and the potential future clinical uses of sodium MR imaging in the diagnosis, phenotyping, and therapeutic monitoring in neurologic diseases.

A national survey exploring UK trainees' perceptions, core training experience, and decisions to pursue advanced training in breast radiology.

AIM: To investigate UK radiology trainees' perceptions of breast radiology and the factors that influenced their decision whether or not to choose breast radiology as an area of special interest. MATERIALS & METHODS: An online survey was compiled and distributed to all UK specialty trainees in clinical radiology via the Royal College of Radiologists Junior Radiologists' Forum (JRF) regional representatives. RESULTS: There were 275 respondents, representing 22% of all UK radiology trainees. Responses were received from all regions. A significant factor identified in influencing whether or not trainees decide to pursue advanced training in breast radiology is the timing and quality of their initial core training experience. Specific positive aspects of breast radiology that were repeatedly identified included the high level of patient contact and frequent use of interventional procedures. Recurring negative aspects of breast radiology included isolation from general radiology and finding the subject matter boring. CONCLUSION: Breast radiology faces a significant workforce shortfall that is predicted to worsen in the coming years. There has never been a greater need to recruit specialty trainees into this field, and action is urgently needed to help ensure the sustainability of breast services and drive further improvements to patient care. The findings from this survey should be regarded as a challenge to all breast radiologists to engage with trainees from an early stage in their training and to enthuse them with the many positive aspects of a career in breast radiology.

SMASH navigators.

The additional data acquired when using multiple receiver coils is commonly used to improve SNR or reduce acquisition times. It may also be used to remove image artifacts by selectively replacing corrupt data. In the present study, a correction scheme is presented based on simultaneous acquisition of spatial harmonics (SMASH) that enables detection and correction of motion artifacts caused by 2D translations. Newly measured data is compared with predictions from previously measured data by making negative and positive spatial harmonics. Differences are attributed to motion occurring in the interval between the acquisition of separate phase encode lines and correction parameters are determined. Two types of rigid body motion are considered: 1) object and coil array move, and 2) object only moves, since each causes different phase errors in k-space. Simulation, phantom, and volunteer experiments demonstrate the validity of the technique.

Detection and elimination of motion artifacts by regeneration of k-space.

A method has been developed using techniques from partially parallel imaging (PPI) to detect localized inconsistencies in k-space that are caused by certain types of motion. The inconsistent data are discarded and consistent data regenerated from the remaining data using PPI techniques. The price is a small decrease in signal-to-noise ratio (SNR) and additional postprocessing. An iterative scheme is presented which does not require separately acquired coil sensitivity information for the PPI reconstructions. This method has been found to reduce artifact levels in phantom and in vivo test studies.

Combination of signals from array coils using image-based estimation of coil sensitivity profiles.

It is well established that the optimal unbiased way to combine image data from array coils is a pixel-by-pixel sum of coil signals, with each signal weighted by the individual coil sensitivity at the location of the pixel. A pragmatic alternative combines the images from the coils as the square root of the sum of squares (SOS), which can reduce the signal-to-noise ratio (SNR) and introduce bias. This work describes how to replace coil sensitivity by an image-derived quantity that enables close to optimal signal combination up to a global intensity scaling. Typical scaling is by an individual coil sensitivity or a linear or SOS combination of the sensitivities of some or all of the coils in the array. The method decreases signal bias, improves SNR when coils have unequal noise levels, and can reduce image artifacts. It can produce phase-corrected data, which eliminates bias completely. In addition, the method allows images from arrays that include highly localized coils, such as a prostate coil and external pelvic array, to be combined with near-optimal SNR and an intensity modulation that makes them easier to view.

An investigation into the use of sensitivity-encoded techniques to increase temporal resolution in dynamic contrast-enhanced breast imaging.

Gadolinium-enhanced dynamic magnetic resonance (MR) imaging is playing an increasingly important diagnostic role in patients with breast cancer. Because of the multi-focal nature of the disease, it is mandatory to cover all of both breasts, not only in the initial scan, but also at subsequent follow-up. This requires volume acquisitions with a temporal resolution limited to 60-80 seconds, which is insufficient to clearly discriminate malignant from benign rates of contrast uptake. In this work, we performed sensitivity-encoded imaging using a commercially available four-channel breast coil (MRI Devices Corporation) on a commercial 0.5-T scanner with moderate gradient performance to give increased temporal resolution in these dynamic contrast-enhanced scans. A two-fold increase in temporal resolution was readily achievable with this coil. Image reconstruction was robust and image quality was assessed qualitatively to be good. We also investigated higher speed-up factors using two directions of sensitivity-encoded reduction and discussed some of the potential artifacts associated with such imaging.