Publications by Year: 2023


Paul E Neumann, Michael W Halle, Jian Kong, and Ron Kikinis. 2023. West Meets East: Taking a Stab at Acupuncture Point Names. Clin Anat.

Acupuncture point names written in Chinese Han characters often provide clinically useful information in both their literal and figurative meanings about location and therapeutic use. The World Health Organization (WHO) standard acupuncture nomenclature includes these names in Han characters in an unusual array that includes both "original" forms and, in parentheses, simplified forms. Construction of a multilingual table of acupuncture point names during development of a database revealed that the assumption that the "original" form in the WHO nomenclature was the traditional Chinese character was frequently false. The Han character forms in the pdf of the 2009 reprint of WHO Standard Acupuncture Point Locations were carefully compared with Han characters used in traditional and simplified Chinese, Japanese and Korean writing systems. This work utilized three online tools: UnicodePlus, Unihan Database Lookup, and Wiktionary. Only 48% of the "original" character forms were traditional Chinese characters. The Unicode number was correct in 99%, but in most cases the East Asian font used was not a traditional Chinese one. The issue about Han character forms was also found in all earlier versions of the WHO standard acupuncture nomenclature. Other detected problems included the use of wrong characters for an "original" character form in one name and for a simplified character form in another name. The WHO standard acupuncture nomenclature should be revised with a focus on accuracy in the usage of Han characters.

Arthur Chakwizira, Carl-Fredrik Westin, Jan Brabec, Samo Lasič, Linda Knutsson, Filip Szczepankiewicz, and Markus Nilsson. 2023. Diffusion MRI With Pulsed and Free Gradient Waveforms: Effects of Restricted Diffusion and Exchange. NMR Biomed, 36, 1, Pp. e4827.
Monitoring time dependence with diffusion MRI yields observables sensitive to compartment sizes (restricted diffusion) and membrane permeability (water exchange). However, restricted diffusion and exchange have opposite effects on the diffusion-weighted signal, which can lead to errors in parameter estimates. In this work, we propose a signal representation that incorporates the effects of both restricted diffusion and exchange up to second order in b-value and is compatible with gradient waveforms of arbitrary shape. The representation features mappings from a gradient waveform to two scalars that separately control the sensitivity to restriction and exchange. We demonstrate that these scalars span a two-dimensional space that can be used to choose waveforms that selectively probe restricted diffusion or exchange, eliminating the correlation between the two phenomena. We found that waveforms with specific but unconventional shapes provide an advantage over conventional pulsed and oscillating gradient acquisitions. We also show that parametrization of waveforms into a two-dimensional space can be used to understand protocols from other approaches that probe restricted diffusion and exchange. For example, we found that the variation of mixing time in filter-exchange imaging corresponds to variation of our exchange-weighting scalar at a fixed value of the restriction-weighting scalar. The proposed signal representation was evaluated using Monte Carlo simulations in identical parallel cylinders with hexagonal and random packing as well as parallel cylinders with gamma-distributed radii. Results showed that the approach is sensitive to sizes in the interval 4-12 μm $$ \upmu \mathrmm $$ and exchange rates in the simulated range of 0 to 20 s - 1 $$ \mathrms^-1 $$ , but also that there is a sensitivity to the extracellular geometry. The presented theory constitutes a simple and intuitive description of how restricted diffusion and exchange influence the signal as well as a guide to protocol design capable of separating the two effects.
Hanneke M Keijzer, Marco Duering, Ofer Pasternak, Frederick J A Meijer, Marlous M L H Verhulst, Bart A R Tonino, Michiel J Blans, Cornelia W E Hoedemaekers, Catharina J M Klijn, and Jeannette Hofmeijer. 2023. Free Water Corrected Diffusion Tensor Imaging Discriminates Between Good and Poor Outcomes of Comatose Patients After Cardiac Arrest. Eur Radiol, 33, 3, Pp. 2139-48.
OBJECTIVES: Approximately 50% of comatose patients after cardiac arrest never regain consciousness. Cerebral ischaemia may lead to cytotoxic and/or vasogenic oedema, which can be detected by diffusion tensor imaging (DTI). Here, we evaluate the potential value of free water corrected mean diffusivity (MD) and fractional anisotropy (FA) based on DTI, for the prediction of neurological recovery of comatose patients after cardiac arrest. METHODS: A total of 50 patients after cardiac arrest were included in this prospective cohort study in two Dutch hospitals. DTI was obtained 2-4 days after cardiac arrest. Outcome was assessed at 6 months, dichotomised as poor (cerebral performance category 3-5; n = 20) or good (n = 30) neurological outcome. We calculated the whole brain mean MD and FA and compared between patients with good and poor outcomes. In addition, we compared a preliminary prediction model based on clinical parameters with or without the addition of MD and FA. RESULTS: We found significant differences between patients with good and poor outcome of mean MD (good: 726 [702-740] × 10-6 mm2/s vs. poor: 663 [575-736] × 10-6 mm2/s; p = 0.01) and mean FA (0.30 ± 0.03 vs. 0.28 ± 0.03; p = 0.03). An exploratory prediction model combining clinical parameters, MD and FA increased the sensitivity for reliable prediction of poor outcome from 60 to 85%, compared to the model containing clinical parameters only, but confidence intervals are overlapping. CONCLUSIONS: Free water-corrected MD and FA discriminate between patients with good and poor outcomes after cardiac arrest and hold the potential to add to multimodal outcome prediction. KEY POINTS: • Whole brain mean MD and FA differ between patients with good and poor outcome after cardiac arrest. • Free water-corrected MD can better discriminate between patients with good and poor outcome than uncorrected MD. • A combination of free water-corrected MD (sensitive to grey matter abnormalities) and FA (sensitive to white matter abnormalities) holds potential to add to the prediction of outcome.