Connecting Solution-Phase to Single-Molecule Properties of Ni(Salophen).

We present a strong correlation of the Ni(salophen) structure and properties measured in single-molecule vs bulk quantities and in ultra high vacuum vs solution phase. Under a scanning tunneling microscope (STM), Ni(salophen) forms a self-assembled monolayer (SAM) on Au(111) at 23 °C with molecular structure identical to that of the X-ray crystallographic measurement. The HOMO and LUMO levels are determined using elastic tunneling spectroscopy at the single-molecule level with confirmation by monolayer-quantity ultraviolet photoelectron spectroscopy (UPS) and by cyclic voltammetry (CV) measurements. The STM-determined HOMO-LUMO gap of 3.28 eV and (HOMO-1)-HOMO gap of 0.36 eV form a new foundation for the selection of hybrid functionals with a simple basis set to be effective in accurately calculating single-molecule Ni(salophen) frontier MO levels. Our results suggest that microscopy-based experiments on a surface, along with free-molecule gas-phase calculations, can provide useful insights into the physical properties of metal(salen) complexes, especially when such direct measurements are not available in solution.

Intercalating Single-Atom Metal Centers into an Organic Monolayer with a Full-Sample Coverage.

Thiolate self-assembled monolayers (SAMs) have been widely used as a straightforward method to functionalize the surface of a common substrate with selective organic functional groups. Here we describe a process that further introduces isolated metal centers into an organic SAM using solutions of metallic porphyrin so that different organic groups and metal single-atoms can be simultaneously exposed on top of the surface. The entire process employs only common laboratory equipment and mild-temperature (<100 °C) incubation to create a full-sample (>cm2) SAM coverage. Each step in this process is closely monitored and discussed using nm-scale scanning tunneling microscopy (STM) images. This work can be straightforwardly adopted by research groups interested in such a diversely customizable surface but without access to a vacuum-based deposition technology. The porphyrin molecules are shown to intercalate among closely packed thiolate SAM domains, and STM characterization shows that the entire mixed monolayer is stable in an ambient condition. This process also does not involve any tip-assisted desorption or lithography procedure and can thus be applied toward substrates of other shapes beyond a flat surface.

Radiology education in Europe: Analysis of results from 22 European countries.

AIM: To assess the state of radiology education across Europe by means of a survey study. METHODS: A comprehensive 23-item radiology survey was distributed via email to the International Society of Radiology members, national radiological societies, radiologists and medical physicists. Reminders to complete the survey were sent and the results were analyzed over a period of 4 mo (January-April 2016). Survey questions include length of medical school and residency training; availability of fellowship and subspecialty training; number of residency programs in each country; accreditation pathways; research training; and medical physics education. Descriptive statistics were used to analyze and summarize data. RESULTS: Radiology residency training ranges from 2-6 years with a median of 5 years, and follows 1 year of internship training in 55% (12 out of 22) European countries. Subspecialty fellowship training is offered in 55% (12 out of 22) European countries. Availability for specialization training by national societies is limited to eight countries. For nearly all respondents, less than fifty percent of radiologists travel abroad for specialization. Nine of 22 (41%) European countries have research requirements during residency. The types of certifying exam show variation where 64% (14 out of 22) European countries require both written and oral boards, 23% (5 out of 22) require oral examinations only, and 5% (1 out of 22) require written examinations only. A degree in medical physics is offered in 59% (13 out of 22) European countries and is predominantly taught by medical physicists. Nearly all respondents report that formal examinations in medical physics are required. CONCLUSION: Comparative learning experiences across the continent will help guide the development of comprehensive yet pragmatic infrastructures for radiology education and collaborations in radiology education worldwide.

Machine Learning Interface for Medical Image Analysis.

TensorFlow is a second-generation open-source machine learning software library with a built-in framework for implementing neural networks in wide variety of perceptual tasks. Although TensorFlow usage is well established with computer vision datasets, the TensorFlow interface with DICOM formats for medical imaging remains to be established. Our goal is to extend the TensorFlow API to accept raw DICOM images as input; 1513 DaTscan DICOM images were obtained from the Parkinson's Progression Markers Initiative (PPMI) database. DICOM pixel intensities were extracted and shaped into tensors, or n-dimensional arrays, to populate the training, validation, and test input datasets for machine learning. A simple neural network was constructed in TensorFlow to classify images into normal or Parkinson's disease groups. Training was executed over 1000 iterations for each cross-validation set. The gradient descent optimization and Adagrad optimization algorithms were used to minimize cross-entropy between the predicted and ground-truth labels. Cross-validation was performed ten times to produce a mean accuracy of 0.938 ± 0.047 (95 % CI 0.908-0.967). The mean sensitivity was 0.974 ± 0.043 (95 % CI 0.947-1.00) and mean specificity was 0.822 ± 0.207 (95 % CI 0.694-0.950). We extended the TensorFlow API to enable DICOM compatibility in the context of DaTscan image analysis. We implemented a neural network classifier that produces diagnostic accuracies on par with excellent results from previous machine learning models. These results indicate the potential role of TensorFlow as a useful adjunct diagnostic tool in the clinical setting.

Moderately elevated intracranial pressure produces greater cross-filling of the anterior communicating artery.

This study aimed to investigate whether moderately elevated intracranial pressure is associated with greater cross-filling of the anterior communicating artery on diagnostic cerebral angiography. A retrospective study of 12 patients with subarachnoid hemorrhage was performed. Data on sequential cerebral angiograms and clinical data were used to indirectly estimate intracranial pressure (ICP). Cross-filling of the anterior communicating artery (ACom) was recorded according to our scoring system. Our study included 12 patients with mean age 43 ± 11 yrs. Six patients demonstrated greater ICP associated with greater cross-filling of the ACom on initial angiogram. One patient had greater ICP with greater cross-filling on follow-up angiogram secondary to infarction and midline shift. Two patients had lower ICP yet greater cross-filling on follow-up angiogram due to higher injection rate and volume. One patient with no change in ICP demonstrated the same degree of cross-filling. A markedly elevated ICP is traditionally associated with no cross-filling across the ACom. We propose a counter-intuitive model in which moderately elevated ICP produces greater cross-filling of the ACom. This diagnostic angiographic finding should make the angiographer consider that the patient has moderately elevated ICP, and facilitate more timely clinical management.

Technical compliance to standard guidelines for lumbar puncture and myelography: survey of academic neuroradiology attendings and fellows.

RATIONALE AND OBJECTIVES: To assess technical compliance among neuroradiology attendings and fellows to standard guidelines for lumbar puncture and myelography to minimize procedural complications such as iatrogenic meningitis and spinal headache. MATERIALS AND METHODS: We surveyed academic neuroradiology attendings and fellows in the e-mail directory of the Association of Program Directors in Radiology. We queried use of face masks, use of noncutting needles, and dural puncture practices. All data were collected anonymously. RESULTS: A total of 110 survey responses were received: 75 from neuroradiology attendings and 34 from fellows, which represents a 14% response rate from a total of 239 fellows. Forty-seven out of 101 (47%) neuroradiologists do not always wear a face mask during myelograms, and 50 out of 105(48%) neuroradiologists do not always wear a face mask during lumbar punctures, placing patients at risk for iatrogenic meningitis. Ninety-six out of 106 neuroradiologists (91%) use the Quincke cutting needle by default, compared to only 17 out of 109 neuroradiologists (16%) who have ever used noncutting needles proven to reduce spinal headache. Duration of postprocedure bed rest does not influence incidence of spinal headache and may subject patients to unnecessary monitoring. Only 15 out of 109 (14%) neuroradiologists in our study do not prescribe bed rest. There was no statistically significant difference in practice between attendings and fellows. CONCLUSIONS: Iatrogenic meningitis and spinal headache are preventable complications of dural puncture that neuroradiologists can minimize by conforming to procedural guidelines. Wearing face masks and using noncutting spinal needles will reduce patient morbidity and lower hospitalization costs associated with procedural complications.