Purpose A technique is described for simultaneous multi-slice (SMS) excitation using radiofrequency (RF) parallel transmission (pTX). Methods Spatially distinct slices are simultaneously excited by applying different RF frequencies on groups of elements of a multi-channel transmit array. The localized transmit sensitivities of the coil geometry are thereby exploited to reduce RF power. The method is capable of achieving SMS-excitation using single-slice RF pulses, or multi-band pulses. SMS-pTX is demonstrated using eight-channel parallel RF transmission on a dual-ring pTX coil at 3 T. The effect on B1+ homogeneity and SAR is evaluated experimentally and by simulations. Slice-GRAPPA reconstruction was used for separation of the collapsed slice signals. Results Phantom and in vivo brain data acquired with FLASH and blipped-CAIPIRINHA EPI are presented at SMS excitation factors of two, four and six. We also show that with our pTX coil design, slice placement and binary division of transmitters, SMS-pTX excitations can achieve the same mean flip angles excitations at approximately 30% lower RF power than a conventional SMS approach with multi-band RF pulses. Conclusion The proposed SMS-pTX allows simultaneous multi-slice excitations at reduced RF power by exploiting the local B1+ sensitivities of suitable multi-element pTX arrays.

An examination is made of the reproductive anatomy and the morphology of branched, ligulate members of the genus Desmarestia from worldwide localities. Entities from southern Africa, New Zealand, South America, Gough Island, northwestern America, and Europe show varying degrees of morphological overlap, but all possess sporangia similar in size and shape to, and scattered among, the vegetative cortical cells. Specimens from Signy Island (South Orkneys) have sporangia subtended by stalk cells, interspersed with sterile paraphyses, and arranged in a palisadelike sorus (Antarctic type). The taxonomic implications of these findings are discussed. The New Zealand and Gough entities are referred to D. ligulata (Stackhouse) Lamouroux and the name D. firma (C.Ag.) Skottsb. is retained for the southern African entity.

Purpose Simultaneous Multi-Slice (SMS) imaging can significantly increase image acquisition rates and improve temporal resolution and contrast in gradient-echo BOLD fMRI experiments. Through-plane signal loss due to B0 inhomogeneities at air-tissue interfaces limit fMRI of structures near the nasal cavity and ear canals. This work implements spectral-spatial (SPSP) RF pulses for reduced through-plane signal loss across multiple simultaneously excited slices. Theory and Methods Multi-Band (MB) and Power Independent of Number of Slices (PINS) methods are combined with SPSP excitation for signal loss compensation in slice-accelerated human brain imaging. Nine simultaneous slices of 5 mm thickness and 20 mm apart were excited using standard MB RF pulses and the proposed SPSP-SMS pulses, yielding coverage of 36 slices in four shots with 350 ms volume TR. The pulses were compared in breath-hold fMRI at 3 T. Results The SPSP-SMS pulses recovered approximately 45% of voxels with signal loss in standard SMS images. Activation in areas of signal recovery increased by 26.4% using a 12.6 ms SPSP-MB pulse and 20.3% using a 12.1 ms SPSP-PINS pulse. Conclusions It is demonstrated that SPSP-SMS pulses can improve BOLD sensitivity in areas of signal loss across simultaneous multiple slices.