title: The value of tomographic ventilation/perfusion scintigraphy (V/PSPECT) for follow-up and prediction of recurrence in pulmonary embolism.
abstract: BACKGROUND
  Pulmonary embolism (PE) is diagnosed with imaging techniques such as ventilation/perfusion (V/P) lung scintigraphy or multidetector computed tomography of the pulmonary arteries (MDCT). Lung scintigraphy can be performed with planar (V/P PLANAR) and tomographic (V/P SPECT) techniques. V/P SPECT has higher sensitivity and specificity than V/P PLANAR. As nephrotoxic contrast media are not used during V/P SPECT, examinations can be repeated for evaluation of resolution of perfusion defects after PE. However, the value of residual perfusion defects identified using V/P SPECT for the prediction of recurrent PE has not been thoroughly evaluated.
  
  
  METHODS
  We evaluated resolution and recurrence of PE in 227 patients (mean age 63 ± 17 years, 134[59%] women) with PE undergoing ≥ 2 SPECT examinations in 2005-2007. PE was defined as minor (<20% perfusion defect on SPECT, n=86), medium (20-50% perfusion defect on SPECT, n=99), or major (>50% perfusion defect on SPECT, n=42).
  
  
  RESULTS
  At second V/P SPECT examination, complete resolution of perfusion defects had occurred in 45 (52%) patients with minor PE after 8.2 ± 7.4 months, in 29 (29%) of patients with medium PE after 6.2 ± 5.9 months, and in 2(5%) of patients with major PE after 6.5 ± 0.7 months. During 47 ± 24 months of follow up, 37(16 %) patients suffered recurrent PE. Of these 37, 34 (92%) showed residual perfusion defects at the second V/P SPECT examination. Recurrence of PE was also predicted by advanced age and female gender. However, in multivariate regression analysis, recurrence was only predicted by age (p=0.0013) and residual perfusion defect on V/P SPECT (p=0.0039).
  
  
  CONCLUSIONS
  In conclusion, complete resolution of PE was common in patients with minor PE, whereas residual perfusion defects were widespread in patients with medium and major PE. PE patients identified with persistent perfusion defects at follow-up SPECT have a high risk of PE recurrence.
authors.affiliation: Department of Vascular Diseases, Skåne University Hospital, S-205 02 Malmö, Sweden. alaa.alhadad@gmail.com
authors.forename: Alaa
authors.initials: A
authors.lastname: Alhadad
authors.forename: Massimo
authors.initials: M
authors.lastname: Miniati
authors.forename: Hussein
authors.initials: H
authors.lastname: Alhadad
authors.forename: Anders
authors.initials: A
authors.lastname: Gottsäter
authors.forename: Marika
authors.initials: M
authors.lastname: Bajc
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000503:physiopathology; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014692:Ventilation-Perfusion Ratio / Q000502:physiology