title: Dural sinus thrombosis: frequency and imaging diagnosis.
abstract: OBJECTIVE
  To determine the frequency of dural sinus thrombosis (DST) and highlight diagnostic importance of its subtle imaging findings in patients presenting for workup of their varied neurologic complaints and symptoms.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  June 2002- May 2005.
  
  
  METHODS
  All new patients undergoing cranial computed tomography (CT) and magnetic resonance (MR) imaging were included in this study which consisted of 1676 consecutive subjects with 1780 examinations. These were reviewed in real time on monitors (as they were being performed) for evidence of DST before printing of hard copies prior to disposition of patients. CT studies were performed on Toshiba Auklet scanner with 5 mm thick axial slices and 1 cm inter slice gap. MR imaging was performed on 1.5 Tesla Toshiba Visart scanner with T1 and T2 weighted (T1 and T2W), spin echo, FLAIR and post contrast T1 weighted (T1W) imaging in multiple planes. Subjects with inconclusive but suspicious conventional imaging (CT, MR) were evaluated by magnetic resonance venography (MRV). Patients presenting for follow-up of established diagnoses including neoplasia, arterial infarcts, hypertensive parenchymal haemorrhages and postsurgical status were excluded.
  
  
  RESULTS
  Delta and empty delta were the most commonly observed CT and MR signs diagnostic of DST on pre and postcontrast images and were present in 43 patients. Thrombus was also directly visible within lumen of superior sagittal, transverse and sigmoid sinuses on T1W MR images in 21 individuals. In 12 patients, these signs were either absent or too subtle to be conclusive. However, presence of venous haemorrhagic or non-haemorrhagic brain parenchymal edematous lesions prompted further evaluation by MRV, which confirmed presence of DST in these subjects as well. As a result, a total of 55 patients with a frequency of 3.3% were diagnosed and treated for DST.
  
  
  CONCLUSIONS
  Frequency of DST in patients with neurological complaints and symptoms is 3.3%, which is significantly higher than has been clinically suspected or recognized. On routine CT and MR studies, diagnostic imaging signs, while highly specific for DST, can be absent or may be masked due to technical factors or associated complications. Presence of brain parenchymal venous haemorrhagic or non-haemorrhagic edematous lesions should prompt judicious and close scrutiny of images on monitors by changing viewing parameters to detect subtle signs of DST. If still in doubt, MRV must be pursued for definitive diagnosis.
authors.affiliation: Department of Diagnostic Radiology, Al- Shifa International Hospital (SIH), Islamabad.
authors.forename: M Yousuf
authors.initials: MY
authors.lastname: Chaudhary
authors.forename: Ibrar
authors.initials: I
authors.lastname: Ahmed
authors.forename: Bilqees
authors.initials: B
authors.lastname: Afzal
authors.forename: Mujahid
authors.initials: M
authors.lastname: Raza
authors.forename: Rashid
authors.initials: R
authors.lastname: Nazir
authors.forename: Nasir
authors.initials: N
authors.lastname: Khan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012851:Sinus Thrombosis, Intracranial / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed