The Qualifier None is identified by letter "Z" and occupies the 6th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to C21GYZ
Planar Nucl Med Imag of Myocardium using Thallium 201
Planar Nucl Med Imag of Myocardium using Oth Radionuclide
Planar Nuclear Medicine Imaging of Myocardium
Planar Nucl Med Imag of Myocardium using Indium 111
Planar Nucl Med Imag of Myocardium using Technetium 99m