Devices, systems, and methods configured to assess the severity of a blockage in a vessel and, in particular, a stenosis in a blood vessel, provide visual depictions of vessel that allow assessment of the vessel and, in particular, any stenosis or lesion of the vessel, simulate one or more treatment options for the vessel, and perform treatment on any stenosis or lesion of the vessel, including guiding placement of one or more treatment devices are provided. The method can include obtaining pressure measurements from first and second instruments positioned within a vessel of a patient during a diagnostic procedure where the second instrument is moved longitudinally through the vessel； identifying a treatment option based on the obtained pressure measurements； and performing the identified treatment option, wherein a user display guides placement of one or more treatment devices associated with the identified treatment option.
