A Gastric Calcifying Fibrous Pseudotumor Detected by Transabdominal Ultrasound after Oral Administration of an Echoic Cellulose-Based Gastrointestinal Ultrasound Contrast Agent - Liu, Z.; Guo, J.; Ren, W.; Sun, S.; Tang, S.; Xie, L. (Ultraschall in der Medizin - European Journal of Ultrasound, 2014)