Scheme 5. Ir-catalyzed CÀH borylation of arenes. mtbe = methyl tert-butyl ether [IUPAC: 2-methoxy-2-methylpropane]. Scheme 4. Catalytic cycles of the Ir-catalysed CÀH borylation depicting catalyst regeneration using B 2 pin 2 (blue) and HBpin (red). coe = cyclooctene.

No abstract

It is a growing concern that outcomes of neuroimaging studies often cannot be replicated. To counteract this, the magnetic resonance (MR) neuroimaging community has promoted acquisition standards and created data sharing platforms, based on a consensus on how to organize and share MR neuroimaging data. Here, we take a similar approach to positron emission tomography (PET) data. To facilitate comparison of findings across studies, we first recommend publication standards for tracer characteristics, image acquisition, image preprocessing, and outcome estimation for PET neuroimaging data. The co-authors of this paper, representing more than 25 PET centers worldwide, voted to classify information as mandatory, recommended, or optional. Second, we describe a framework to facilitate data archiving and data sharing within and across centers. Because of the high cost of PET neuroimaging studies, sample sizes tend to be small and relatively few sites worldwide have the required multidisciplinary expertise to properly conduct and analyze PET studies. Data sharing will make it easier to combine datasets from different centers to achieve larger sample sizes and stronger statistical power to test hypotheses. The combining of datasets from different centers may be enhanced by adoption of a common set of best practices in data acquisition and analysis.

The nuclear medicine field has seen a rapid expansion of academic and commercial interest in developing artificial intelligence (AI) algorithms. Users and developers can avoid some of the pitfalls of AI by recognizing and following best practices in AI algorithm development.In this article, recommendations on technical best practices for developing AI algorithms in nuclear medicine are provided, beginning with general recommendations and then continuing with descriptions of how one might practice these principles for specific topics within nuclear medicine. This report was produced by the AI Task Force of the Society of Nuclear Medicine and Molecular Imaging.

Clinical effects of anti-cholinergic drugs implicate cholinergic systems alterations in the pathophysiology of some cardinal motor impairments in Parkinson's disease. The topography of affected cholinergic systems deficits and motor domain specificity are poorly understood. Parkinson's disease patients (n = 108) underwent clinical and motor assessment and vesicular acetylcholine transporter [18F]-fluoroethoxybenzovesamicol PET imaging. Volumes-of-interest-based analyses included detailed thalamic and cerebellar parcellations. Successful PET sampling for most of the small-sized parcellations was available in 88 patients. A data-driven approach, stepwise regression using the forward selection method, was used to identify cholinergic brain regions with cardinal domain-specific motor ratings. Regressions with motor domain scores for model-selected regions followed by confounder analysis for effects of age of onset, duration of motor disease and levodopa equivalent dose. Among 7 model-derived regions associating with postural instability and gait difficulties domain scores three retained significance in confounder variable analysis: medial geniculate nucleus (standardized β = -0.34, t = -3.78, P = 0.0003), lateral geniculate nucleus (β = -0.32, t = -3.4, P = 0.001) and entorhinal cortex (β = -0.23, t = -2.6, P = 0.011). A sub-analysis of non-episodic postural instability and gait difficulties scores demonstrated significant effects of the medial geniculate nucleus, entorhinal cortex and globus pallidus pars interna. Among 6 tremor domain model-selected regions two regions retained significance in confounder variable analysis: cerebellar vermis section of lobule VIIIb (β = -0.22, t = -2.4, P = 0.021) and the putamen (β = -0.23, t = -2.3, P = 0.024). None of the three model-selected variables for the rigidity domain survived confounder analysis. Two out of the four model-selected regions for the distal limb bradykinesia domain survived confounder analysis: globus pallidus pars externa (β  =  0.36, t = 3.9, P = 0.0097) and the paracentral lobule β  =  0.26, t = 2.5, P = 0.013. Emphasizing the utility of a systems-network conception of the pathophysiology of Parkinson's disease cardinal motor features, our results are consistent with specific deficits in basal forebrain corticopetal, peduncupontine-laterodorsal tegmental complex, and medial vestibular nucleus cholinergic pathways, against the background of nigrostriatal dopaminergic deficits, contributing significantly to postural instability, gait difficulties, tremor and distal limb bradykinesia cardinal motor features of Parkinson's disease. Our results suggest significant and distinct consequences of degeneration of cholinergic peduncupontine-laterodorsal tegmental complex afferents to both segments of the globus pallidus. Non-specific regional cholinergic nerve terminal associations with rigidity scores likely reflect more complex multifactorial signaling mechanisms with smaller contributions from cholinergic pathways.