This document summarizes a market research report about Picture Archiving and Communication Systems (PACS). It describes how medical imaging has transitioned from analog films to digital files. PACS systems were developed for digital image storage and viewing. The report analyzes the different market segments for PACS, which mostly handle images from ultrasound, MRI, PET, CT and other modalities. PACS penetration in the US healthcare system is almost 90%. PACS networks connect imaging devices to clients via local or wide area networks for remote viewing. Interconnections with radiology information systems are also examined.