For most of the world a pearl is a thing of beauty especially when expertly strung into a necklace. For the Radiologist a "Pearl" is a fact or bit of knowledge that can help them make the correct diagnosis or better understand an image. Pearls have been a classic part of Radiology just like the teaching file or lecture series. Pearls have always been a big part of www.CTISUS.com and we post 40-100 or so pearls a month. In this app we present 26 of the most popular topics filled with pearls from the literature or our imaging experiences. We look forward to sharing them with you on version 4.0 where we present literally thousands of pearls. We hope you find this useful and appreciate any thoughts or suggestions to improve the learning experience.