Final answer:
DICOM is the universal standard for communicating images between PACS and imaging modalities.
Step-by-step explanation:
The universal standard regarding how images are communicated between PACS, and imaging modalities is DICOM (Digital Imaging and Communications in Medicine). DICOM is a protocol used in medical imaging that defines the format and communication methods for transmitting medical images. It allows different imaging devices, such as X-ray machines and MRI scanners, to communicate with Picture Archiving and Communication Systems (PACS) by standardizing how images are stored and exchanged.