Current Clinical Concerns in CT: Results : Protocols
Gastric CT
1. What is your protocol for oral contrast in bariatric surgery patients (i.e. gastric bypass) who are undergoing abdominal CT?
| Answer: These are really tough patients. I use oral beginning 90-120 minutes before the study, with an additional 500-750 cc just before the study. This helps detect complications. |
2. Any suggestions on getting good oral contrast on patients that are having follow up studies after having gastric bypass surgery?
| Answer: Administer 750 cc oral contrast at 5 minute intervals and 250 cc at time of study is all you can do. Positive contrast is probably ideal. |
3. We use sensation 16. I am trying to find an optimal protocol for preoperative staging of gastric cancer. Can you give me any suggestions?
| Answer: We distend the stomach with 1000 cc of water, and do a dual phase study at 25 and 70 seconds. We scan with .75 mm detectors, reconstructed with .75 mm thick scans at .5 mm intervals. We then do InSpace, and look at images in coronal and 3D VRT. See www.insideinspace.com for case examples. |
4. Do you use any parasympathicolytics (eg butylscopalomine) to prevent movement artifacts when scanning for preoperative staging of gastric cancer? Or is it unnecessary due to quick data acquisition afforded by 16 slice MDCT?
| Answer: We do not. 16 slice is fast enough. |
References
Ba-Ssalamah A, Prokop M, Uffmann M, Pokieser P, Teleky B and Lechner G. Dedicated multidetector CT of the stomach: Spectrum of diseases. Radiographics 2003; 23: 625-644.
- Summary: This article provides recommendations for a MDCT protocol to detect and stage known or suspected gastric neoplasms. Patients are asked to fast at least 6 hours prior to the CT. Oral contrast is 1000-1500 ml of water or flavored methylcelluose. For hypotonia, IV scopolamine was administered. If the stomach lesion has been localized to antrum or pylorus, patients are positioned prone; otherwise, positioning is supine. IV contrast volume is 120 ml or 1.5 ml/kg body weight, with a 60 ml saline flush, infused at 4 ml/second. Arterial phase is acquired at 30 seconds (or 10 seconds after aortic arrival time with bolus tracking) for tumor staging. Portal venous phase is acquired at 60 seconds (or 40 seconds after aortic arrival time with bolus tracking). The collimation is .75 to 1.25 mm (for 4, 8 or 16 slice scanners). Reconstructions are 1 to 1.5 mm thick with a .7 mm increment. For MPR, section thickness is 3-6 mm, typically 4 mm. A variety of benign and malignant tumors are discussed, as well as a number of other benign conditions. This article provides CME credit.
Desser TS, Sommer FG, Jeffrey RB. Curved planar reformations in MDCT of abdominal pathology. AJR 2004; 182: 1477-1484.
- Summary: Gastric pathology is one of the clinical indications addressed in this pictoral essay demonstrating the utility of curved planar reformations. The acquisition protocol for 8 or 16 slice MDCT included 2.5 mm collimation, 1.25 mm reconstruction thickness, 50% overlap. In patients with gastrointestinal disease, 800 to 1000 ml of water was administered. IV contrast was administered. The authors discuss how curved planar reformations are helpful for imaging antrum, pylorus and duodenum.
Yu J, Turner MA, Cho S-R et al. Normal anatomy and complications after gastric bypass surgery: Helical CT findings. Radiology 2004; 231: 753-760.
- Summary: In this study of 72 patients, single or multidetector row CT was conducted to evaluate for complications following bypass surgery. The 4 slice MDCT protocol included 2.5 mm collimation and 5 mm section thickness. Most patients received 150 ml of 300 mgI/ml contrast medium infused at 2-3 mL/second. The majority of studies were conducted with oral contrast-either 900 mL of barium sulfate, or 450 ml of 2% diatrizoate meglumine and sodium, administered 1-2 hours prior to the study and immediately before scanning, with the patient on the CT scanner.