Overview of Interventional Pulmonology for Radiologists.

Interventional pulmonology is a growing field specializing in minimally invasive procedures of the mediastinum, lungs, airways, and pleura. These procedures have both diagnostic and therapeutic indications and are performed for benign and malignant diseases. Endobronchial US has been combined with transbronchial needle aspiration to extend tissue sampling beyond the airways and into the lungs and mediastinum. Recent innovations extending the peripheral access of bronchoscopy include electromagnetic navigational bronchoscopy and thinner bronchoscopes. An important indication for therapeutic bronchoscopy is the relief of central airway obstruction, which may be severe and life threatening. Techniques for restoring patency of the central airways include mechanical debulking and multiple modalities for ablation, stent placement, and balloon bronchoplasty. Bronchoscopic lung volume reduction improves quality of life in certain patients with severe emphysema and is an important less invasive alternative to lung volume reduction surgery. Bronchial thermoplasty is likewise a nonpharmacologic treatment in patients with severe uncontrolled asthma. Many of these procedures have unique selection criteria that require precise evaluations at preprocedure imaging. Postprocedure imaging is also essential in determining outcome success and the presence of complications. Radiologists should be familiar with these procedures as well as the relevant imaging features in both planning and later surveillance. Evolving techniques that may become more widely available in the near future include robotic-assisted bronchoscopy, bronchoscopic transparenchymal nodule access, transbronchial cryobiopsy, ablation of early-stage cancers, and endobronchial intratumoral chemotherapy. An invited commentary by Wayne et al is available online. ©RSNA, 2021.

A transgenic wnt8a:PAC reporter reveals biphasic regulation of vertebrate mesoderm development.

Vertebrate wnt8a links anteroposterior and dorsoventral axis patterning, but the regulation of wnt8a expression and its relationship to mesoderm induction and maintenance pathways is unclear. To address this, we have generated zebrafish transgenic for a modified genomic PAC clone that expresses EGFP from the wnt8a locus. The EGFP reporter transgene is expressed in a pattern nearly identical to wnt8a, including maternal deposition, expression in the ventrolateral mesoderm and in the yolk syncytial layer. Loss of function studies show that wnt8a expression is under biphasic control by Nodal and No Tail/Brachyury, whereby early phase expression is Nodal-dependent but late phase expression is Ntl/Bra dependent. EGFP fluorescence persists in cells that transcribe the reporter, thus comprising a tracer for ventrolaterally derived mesodermal lineages. We use this property to show that wnt8a expression marks Nodal-independent tail mesoderm formation and that Ntl/Bra predominantly regulates wnt8a in paraxial mesoderm progenitors.