sinusitis , mucocysts , tumors , infections , hearing disorders , choanal atresia , fractures and other disorders of the paranasal sinuses , eustachian tubes , lachrymal ducts and other ear , nose , throat and mouth structures are diagnosed and / or treated using minimally invasive approaches and , in many cases , flexible catheters as opposed to instruments having rigid shafts . various diagnostic procedures and devices are used to perform imaging studies , mucus flow studies , air / gas flow studies , anatomic dimension studies and endoscopic studies . access and occluding devices may be used to facilitate insertion of working devices such asendoscopes , wires , probes , needles , catheters , balloon catheters , dilation catheters , dilators , balloons , tissue cutting or remodeling devices , suction or irrigation devices , imaging devices , sizing devices , biopsy devices , image - guided devices containing sensors or transmitters , electrosurgical devices , energy emitting devices , devices for injecting diagnostic or therapeutic agents , devices for implanting devices such as stents , substance eluting or delivering devices and implants , etc .