==Technique==
Fibrin sheaths are usually detected by fluoroscopic catheter contrast angiography.<ref name="KnutstadHager2016">{{cite journal|last1=Knutstad|first1=K.|last2=Hager|first2=B.|last3=Hauser|first3=M.|title=Radiologic diagnosis and management of complications related to central venous access|journal=Acta Radiologica|volume=44|issue=5|year=2016|pages=508–516|issn=0284-1851|doi=10.1080/j.1600-0455.2003.00115.x}}</ref> Non-ionic contrast with a high iodine concentration (for example 300 mg/ml) is injected by hand using a 10 ml or 20 ml<ref name="KnutstadHager2016"/> syringe. A precontrast view is followed by a series of images at a small field-of-view.<ref name="KnutstadHager2016"/> It can be done at 2-4 images per second,<ref name="KnutstadHager2016"/> but also up to 15 images per second and a short exposure time of 3-4 seconds.
==Evaluation==
In the presence of fibrin sheaths, the contrast flows backwards around the catheter.
==Report==