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A precontrast view Precontrast imaging*Including lateral projection of the port to confirm that the needle is followed by a series of images during in proper place before contrast infusion, at a .<ref name=Helsingborg/> Contrast imaging*A small field-of-view.<ref name="KnutstadHager2016"/> It can be done at 2-4 images per second*Posteroanterior projection,or slightly oblique to avoid superimposing the spine.<ref name="KnutstadHager2016"Helsingborg/> but also up *First image the contrast filling of the port chamber and the catheter to exclude malfunction.<ref name=Helsingborg/>*Imaging of the outflow from the catheter is imaged at 10-15 images per second and a short exposure time of 3-4 seconds.<ref name=Helsingborg/>
Expanded
Fibrin sheaths of ports can be suspected when it is possible to infuse into it but not to aspirate.
==TechniqueChoice of investigation==
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>
A suspicion of a thrombotic occlusion of the vein passed by the catheter indicates a [[CT angiography]].<ref name=Helsingborg/>
===Preparation===
*Contrast should be non-ionic, <ref name="KnutstadHager2016"/> with a high an iodine concentration (for example 300 of at least 270 mg/ml).<ref name="KnutstadHager2016"Helsingborg/>
*Syringe can be for example 10 ml or 20 ml, for injection by hand.<ref name="KnutstadHager2016"/> For pumps, the pressure should not exceed >40psi (275kPa or 2,75bar).<ref name=Helsingborg/>
*The needle should be at least 20G (0.9mm), and needs to be designed for port use (to avoid fragmentation of the port membrane).<ref name=Helsingborg>{{cite web|url=http://www.rontgen.com/metod/lungor-cvkport-a-cath|title=Porta-a-cath control|website=Röntgen Metodbok, Radiology Department of Helsingborg|accessdate=2018-07-25}}</ref> It should be connected by luer taper.<ref name=Helsingborg/>
*The system needs to be closed to air at all times.<ref name=Helsingborg/>
==Image taking==
After the procedure, the system should be flushed with 20 - 30 ml normal saline.<ref name=Helsingborg/>
==Evaluation==
[[File:Central venous catheter with a fibrin sheath.jpg|thumb|The fibrin sheath is indirectly seen in these images before and after radiocontrast infusion, as the radiocontrast collects around the catheter.]]
In the presence of fibrin sheathsa normal case, the contrast flows straight out from the catheter.<ref name=Helsingborg/> Contrast flowing at a skewed angle compared to the catheter means a suspected fibrin sheath.<ref name=Helsingborg/> A definite fibrin sheath is visualized as contrast flowing backwards around the catheter, looking like a thickening of the distal part, before exiting a bit proximal on the catheter.
==Report==
