The Contrast None is identified by letter "Z" and occupies the 5th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to BY31Z
MRI of Fetal Heart using Oth Contrast
MRI of Fetal Heart using Oth Contrast, Unenh, Enhance
Magnetic Resonance Imaging (MRI) of Fetal Heart