title: Pulmonary MRA: differentiation of pulmonary embolism from truncation artefact.
abstract: OBJECTIVE
  Truncation artefact (Gibbs ringing) causes central signal drop within vessels in pulmonary magnetic resonance angiography (MRA) that can be mistaken for emboli, reducing diagnostic accuracy for pulmonary embolism (PE). We propose a quantitative approach to differentiate truncation artefact from PE.
  
  
  METHODS
  Twenty-eight patients who underwent pulmonary computed tomography angiography (CTA) for suspected PE were recruited for pulmonary MRA. Signal intensity drops within pulmonary arteries that persisted on both arterial-phase and delayed-phase MRA were identified. The percent signal loss between the vessel lumen and central drop was measured. CTA served as the reference standard for presence of pulmonary emboli.
  
  
  RESULTS
  A total of 65 signal intensity drops were identified on MRA. Of these, 48 (74%) were artefacts and 17 (26%) were PE, as confirmed by CTA. Truncation artefacts had a significantly lower median signal drop than PE on both arterial-phase (26% [range 12-58%] vs. 85% [range 53-91%]) and delayed-phase MRA (26% [range 11-55%] vs. 77% [range 47-89%]), p < 0.0001 for both. Receiver operating characteristic (ROC) analyses revealed a threshold value of 51% (arterial phase) and 47% signal drop (delayed phase) to differentiate between truncation artefact and PE with 100% sensitivity and greater than 90% specificity.
  
  
  CONCLUSIONS
  Quantitative signal drop is an objective tool to help differentiate truncation artefact and pulmonary embolism in pulmonary MRA.
  
  
  CONCLUSIONS
  • Inexperienced readers may mistake truncation artefacts for emboli on pulmonary MRA • Pulmonary emboli have non-uniform signal drop • 51% (arterial phase) and 47% (delayed phase) cut-off differentiates truncation artefact from PE • Quantitative signal drop measurement enables more accurate pulmonary embolism diagnosis with MRA.
authors.affiliation: Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Room E1/372, Madison, WI, 53792-3252, USA, pbannas@uwhealth.org.
authors.forename: Peter
authors.initials: P
authors.lastname: Bannas
authors.forename: Mark L
authors.initials: ML
authors.lastname: Schiebler
authors.forename: Utaroh
authors.initials: U
authors.lastname: Motosugi
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: François
authors.forename: Scott B
authors.initials: SB
authors.lastname: Reeder
authors.forename: Scott K
authors.initials: SK
authors.lastname: Nagle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D011655:Pulmonary Embolism / Q000175:diagnosis*; D012372:ROC Curve; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D003287:Contrast Media