Pre-clinical MRI systems (animal scanners or spectroscopy systems) can be used to examine small human brain tissue samples post mortem and investigate fundamental neuroanatomy questions at the mesoscale^1-4. These studies benefit from the advantages of high field strength and gradient performance, but are limited to relatively small tissue samples. The investigation of whole human brains post mortem with large bore systems can achieve a resolution considerably superior to that achievable in-vivo^5-7. However, the achievable resolutions and contrast are limited, compared to small sample studies, by gradient performance, non-optimized RF-coils, and RF-field inhomogeneity over the brain at high main field strengths (≥7T). For diffusion MRI (dMRI), in particular, gradient strength, decreasing T2 with increasing B₀ and the limited SNR per unit time achievable with 3D segmented pulsed gradient spin echo (PGSE) sequences hinder truly high resolution whole brain diffusion MRI acquisitions. Here the aim is to use a specialized 9.4T 8Ch parallel transmit (pTx), 24Ch receive RF-coil for whole post mortem human brains and a diffusion weighted steady state free precession (dwSSFP) sequence to enable high time-efficiency in ultrahigh resolution diffusion imaging of the whole human brain.One human post-mortem hemisphere from a subject without neurological or psychiatric disease was used for the present study. The hemisphere was enclosed in a 3D conformal container model suitable for post mortem human brains (Figure 1A) together with a second hemisphere. It was inserted into the specialized 9.4T 8Ch parallel transmit (pTx), 24Ch receive RF-coil built onto a conformal receive former modeled as a precise fit around the container (Figure 1B&C). Experiments were performed with a 9.4T 820cm bore human MR scanner (Magnetom 9.4T, Siemens Medical Solutions, Erlangen, Germany) with an 80mT/m, 330T/m/s head gradient system using 8-channels of its 16-channel parallel transmit system. For the pTx pulse design, transmit profile (B1+) maps from each of the transmit channels were acquired with a T2* compensated version of DREAM⁸. For reference, the transmit coil's default circularly polarized (CP) mode RF phase setting was used. Diffusion MRI was performed with an optimized dwSSFP sequence⁹ modified to use a kt-points composite excitation pulse¹⁰ in order to optimize for B1+ homogeneity. A kt-points pulse with 6 subpulses was calculated using the MLS approach¹¹. Other imaging parameters were TE/TR = 18ms/28ms, BW = 80Hz/Px, EPI-factor = 1, q = 80 (effective b = 240 s/mm², 6 directions), 220 (effective b = 2000 s/mm²,12 directions) and 300 (effective b = 4000 s/mm², 48 directions), acquired at ~48min/volume. Analysis was performed with the standard spin-echo DTI model using FSL v4.0.1¹².Transmit B1+ maps for the CP mode (Figure 2A, top) show the necessity for pTx at 9.4T for whole human brain samples. Large bands of (near) signal dropout can be seen which translate to dwSSFP results (2B, top). Homogenized B1+ by the kt-points technique vastly improves the transmit profile (2A, bottom) and achieves homogeneous signal and high contrast in 450μm resolution whole brain dwSSFP (2B, bottom). Figure 3 shows the exquisite spatial definition in DTI maps at this resolution.Ultra-high field strengths, a specialized whole brain ex-vivo RF-coil and high efficiency pTx enabled dwSSFP help to achieve 450μm resolution diffusion imaging of the whole human brain. With further developments in data analysis and modeling this data can play an important role in mesoscale human connectomics and microstructure studies help to bridge the gap between in-vivo MRI studies and post-mortem histology.