title: May-Thurner syndrome: correlation between digital subtraction and computed tomography venography.
abstract: OBJECTIVE
  Digital subtraction venography (DSV) and computed tomography venography (CTV) are both recommended for diagnosing May-Thurner syndrome. The literature contains little information on the correlation between these imaging tools. We performed a retrospective case-series study to investigate this correlation.
  
  
  METHODS
  From August 2009 to August 2010, 42 patients with May-Thurner syndrome (34 women, 8 men; mean age: 52.8 ± 13.5 years) received DSV followed by CTV. The DSV was used to evaluate the degree of venous reflux, reflux start-up time, and flow time. By CTV, the ratio of cross-sectional area and the ratio of diameter between the narrowest region to that of the caudal part of the left common iliac vein were calculated. The correlation between these variables for DSV versus CTV was calculated using Spearman's rank correlation coefficients.
  
  
  RESULTS
  In DSV evaluation of the extent of reflux, 19.0% of cases were classified as Grade 0, 11.9% as Grade I, 28.6% as Grade II, and 40.5% as Grade III. The mean ± standard deviation flow times for these groups were 2.00 ± 0.38 seconds, 1.75 ± 0.29 seconds, 1.67 ± 0.72 seconds, and 1.81 ± 0.68 seconds, the mean time for total patients was 1.76 ± 0.78 seconds. The reflux start-up times for Grades I-III were 2.00 ± 1.00 seconds, 1.80 ± 1.23 seconds, and 1.40 ± 0.49 seconds, and the mean time was 1.6 ± 0.8 seconds. In CTV, the mean area ratio and diameter ratio were 0.78 ± 0.22 (range, 0.22-1.27) and 0.75 ± 0.24 (range, 0.33-1.25). The reflux start-up time showed a positive correlation with the cross-sectional area ratio (r = 0.518; p = 0.002) and diameter ratio (r = 0.413; p = 0.019).
  
  
  CONCLUSIONS
  The cross-sectional area ratio and diameter ratio in CTV correlate with the reflux start-up time in DSV. For May-Thurner syndrome, both CTV and DSV provide essential information for diagnosis and evaluation of the disease. The positive correlation between anatomical and hemodynamic properties corresponds with the underlying pathophysiology.
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Kuo
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Chi-Jen
authors.initials: CJ
authors.lastname: Chen
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Jiann-Jy
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Cheng-Hong
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Jan-Wen
authors.initials: JW
authors.lastname: Ku
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Hsu
authors.affiliation: Department of Medical Imaging, Shuang-Ho Hospital, Taipei Medical University, New Taipei City, Taiwan. Electronic address: x2mickey@yahoo.com.tw.
authors.forename: Ying-Chi
authors.initials: YC
authors.lastname: Tseng
mesh_terms: D000328:Adult; D000368:Aged; D015901:Angiography, Digital Subtraction; D005260:Female; D006801:Humans; D007084:Iliac Vein / Q000000981:diagnostic imaging; D008297:Male; D062108:May-Thurner Syndrome / Q000175:diagnosis*; D008875:Middle Aged; D010690:Phlebography; D012189:Retrospective Studies; D013624:Taiwan; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: May–Thurner syndrome; computed tomography; digital subtraction venography