Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM.

Transmission spectroscopy1-3 of exoplanets has revealed signatures of water vapour, aerosols and alkali metals in a few dozen exoplanet atmospheres4,5. However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations' relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species-in particular the primary carbon-bearing molecules6,7. Here we report a broad-wavelength 0.5-5.5 µm atmospheric transmission spectrum of WASP-39b8, a 1,200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with the JWST NIRSpec's PRISM mode9 as part of the JWST Transiting Exoplanet Community Early Release Science Team Program10-12. We robustly detect several chemical species at high significance, including Na (19σ), H2O (33σ), CO2 (28σ) and CO (7σ). The non-detection of CH4, combined with a strong CO2 feature, favours atmospheric models with a super-solar atmospheric metallicity. An unanticipated absorption feature at 4 µm is best explained by SO2 (2.7σ), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST's sensitivity to a rich diversity of exoplanet compositions and chemical processes.

Diffusion-weighted signal patterns of intracranial haemorrhage.

The signal pattern of intracranial haemorrhage on diffusion-weighted imaging (DWI) as it evolves over time is rarely discussed due to the sensitivity of T2*-weighted sequences and the specificity of classic signal patterns on T1 and T2-weighted sequences. The DWI signal is strongly affected by the magnetic susceptibility of paramagnetic blood products and, therefore, is markedly hypointense in the same phases that demonstrate hypointensity on T2*-weighted sequences; however, hyperacute haemorrhage (oxyhaemoglobin-predominant clot) and late subacute haemorrhage (extracellular methaemoglobin) do not demonstrate T2* hypointensity. Moreover, T2*-weighted sequences are less sensitive to the presence of extra-axial haemorrhage than to intraparenchymal haemorrhage. At these stages of evolution, haemorrhage demonstrates high DWI signal in association with low ADC values, which may be more pronounced than even its corresponding fluid-attenuated inversion recovery (FLAIR) signal. DWI is useful for identifying hyperacute subarachnoid haemorrhage and as a problem-solving tool in challenging cases.

Peeking into the Black Box of Coregistration in Clinical fMRI: Which Registration Methods Are Used and How Well Do They Perform?

BACKGROUND AND PURPOSE: Interpretation of fMRI depends on accurate functional-to-structural alignment. This study explores registration methods used by FDA-approved software for clinical fMRI and aims to answer the following question: What is the degree of misalignment when registration is not performed, and how well do current registration methods perform? MATERIALS AND METHODS: This retrospective study of presurgical fMRI for brain tumors compares nonregistered images and 5 registration cost functions: Hellinger, mutual information, normalized mutual information, correlation ratio, and local Pearson correlation. To adjudicate the accuracy of coregistration, we edge-enhanced echo-planar maps and rated them for alignment with structural anatomy. Lesion-to-activation distances were measured to evaluate the effects of different cost functions. RESULTS: Transformation parameters were congruent among Hellinger, mutual information, normalized mutual information, and the correlation ratio but divergent from the local Pearson correlation. Edge-enhanced images validated the local Pearson correlation as the most accurate. Hellinger worsened misalignment in 59% of cases, primarily exaggerating the inferior translation; no cases were worsened by the local Pearson correlation. Three hundred twenty lesion-to-activation distances from 25 patients were analyzed among nonregistered images, Hellinger, and the local Pearson correlation. ANOVA analysis revealed significant differences in the coronal (P < .001) and sagittal (P = .04) planes. If registration is not performed, 8% of cases may have a >3-mm discrepancy and up to a 5.6-mm lesion-to-activation distance difference. If a poor registration method is used, 23% of cases may have a >3-mm discrepancy and up to a 6.9-mm difference. CONCLUSIONS: The local Pearson correlation is a special-purpose cost function specifically designed for T2*-T1 coregistration and should be more widely incorporated into software tools as a better method for coregistration in clinical fMRI.

Scapular free flap harvest site: recognising the spectrum of radiographic post-operative appearance.

OBJECTIVE: Scapular free flap harvesting for oral cavity cancer reconstruction is an increasingly used and versatile option. We aim to describe the appearance of the scapula harvest site on chest radiograph and CT. METHODS: We retrospectively reviewed a surgical database of 82 patients who underwent scapular osteocutaneous flap harvesting for oral cavity cancer reconstruction and had imaging performed at our institution. We searched the picture archiving and communications system for all associated imaging. RESULTS: Characteristic radiographic appearance in the immediate post-operative period as well as in the remote post-operative period is described, including an upside-down V-shaped paraglenoid notch, rectangular (or triangular) lateral border defects and a sharply pointed inferior scapular body. Additionally, common CT appearances are discussed, including an abrupt gleno-scapular interval, an absent axillary rim bulge and a Z-shaped scapula. CONCLUSION: The altered appearance of the scapular defect following surgical harvest is easily recognised. Although the description of this defect may not alter management and may reasonably be omitted, a radiologist's comfort with these appearances may potentially enhance the understanding of patient management and recognition of superimposed complications, such as infection. ADVANCES IN KNOWLEDGE: Scapular osteocutaneous free flap reconstruction is an increasingly used technique after oral cavity surgery. Very few radiologists reported in our review the surgical scapular defects, and there is apparent ignorance of their appearance. We described characteristic radiographic and CT signs of scapular free flap harvesting to increase radiologists' familiarity with these defects, which may provide clinical information and possibly contribute to detection of complications.

Detection of platelet-bound and serum antibodies in autoimmune thrombocytopenia by enzyme-linked assay.

Platelet antibodies were looked for in 47 patients with autoimmune thrombocytopenia using a modification of the enzyme-linked assay previously described. Surface-bound antibodies measured as increased platelet-associated IgG were found in 32 (68%) of the patients. After incubation in test sera, the platelet-associated IgG of normal donor platelets was significantly increased in 27 of the 47 patients (57%), thus demonstrating the presence of platelet antibodies free in their sera. 6 patients had antibodies only in the serum without any elevation of their platelet-associated IgG. When both tests are evaluated together no antibody was detected by either the direct or the indirect test in 9 of the 47 patients (29%) studied. The technique used is described and the interpretation of our results discussed.

Enzyme linked immunoassay for the detection of platelet associated IgG.

An enzyme linked immunoassay incorporating antihuman globulin coupled with alkaline phosphatase has been developed to measure platelet associated IgG (PAIgG). Using a method in which platelet IgG is extracted into the fluid phase after appropriate procedures, we were able to bind the 'solubilized' PAIgG to commercially obtained antihuman IgG (AHG) which had previously been coated onto polystyrene. The amount of PAIgG thus bound was subsequently measured by the addition of the enzyme reagent using p-nitro phenyl phosphate as substrate. With this technique platelets from normal donors were found to have 2.6-17.4 ng/10(6) platelets (mean +/-2 SD). These values are higher than those obtained when assay systems using intact platelets are employed. Platelets from patients with immune thrombocytopenia had PAIgG values of 8.2-98.0 ng/10(6) platelets. In a few patients with disorders other than autoimmune thrombocytopenia (AITP) increased levels of PAIgG were also demonstrated. The assumption that increased PAIgG always represents platelet autoantibody may not be valid. The relevance of PAIgG as a parameter in the diagnosis and clinical management of patients with AITP is discussed.