title: Ultra-low-dose, time-resolved contrast-enhanced magnetic resonance angiography of the carotid arteries at 3.0 tesla.
abstract: OBJECTIVE
  To determine whether time-resolved magnetic resonance angiography (TR-MRA) with ultra-low-dose gadolinium chelate (1.5-3.0 mL) can reliably detect or rule out hemodynamically significant disease in the carotid-vertebral artery territory.
  
  
  METHODS
  Hundred consecutive patients (62 women, 38 men, mean age = 56.6 years) underwent both TR-MRA and standard high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA), having been randomized to 1 of 2 groups; group A receiving a contrast dose of 1.5 mL for TR-MRA and group B receiving 3.0 mL. For scoring purposes the arterial system was divided into 21 segments. All TR-MRA and CE-MRA studies were blindly assessed by 2 radiologists for overall image quality, segmental arterial visualization, grading of arterial stenosis/occlusion, and incidence and severity of artifact. TR-MRA findings were directly compared with those of the corresponding CE-MRA examinations.
  
  
  RESULTS
  Group A TR-MRA studies were of significantly inferior overall image quality compared with those of the corresponding CE-MRA examinations (P = 0.01 for both observers). In group B, overall image quality was similar for TR-MRA and single-phase CE-MRA examinations. On a segmental basis, a higher number of "insufficient quality" segments were identified in group A TR-MRA studies than in group B. A similar reduction in the incidence of artifacts was observed for group B relative to group A TR-MRA studies. Both groups A and B TR-MRA studies were of high specificity, negative predictive values, and accuracy (>97%).
  
  
  CONCLUSIONS
  Ultra-low dose TR-MRA may be performed with 3 mL of gadolinium chelate with preservation of overall image quality and arterial segmental visualization relative to single phase CE-MRA, whereas a 1.5 mL contrast dose is associated with more suboptimal studies. Nonetheless, even at doses as low as 1.5 mL, TR-MRA can exclude arterial stenosis or occlusion.
authors.affiliation: David Geffen School of Medicine at UCLA, Department of Radiological Sciences, Diagnostic Cardiovascular Imaging Section, Los Angeles, CA 90095-7206, USA. derek.lohan@gmail.com
authors.forename: Derek G
authors.initials: DG
authors.lastname: Lohan
authors.forename: Anderanik
authors.initials: A
authors.lastname: Tomasian
authors.forename: Roya S
authors.initials: RS
authors.lastname: Saleh
authors.forename: Aparna
authors.initials: A
authors.lastname: Singhal
authors.forename: Mayil S
authors.initials: MS
authors.lastname: Krishnam
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002339:Carotid Arteries; D016893:Carotid Stenosis / Q000175:diagnosis*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA