title: Rate of successful recording of blood flow signals in the middle cerebral artery using transcranial Doppler sonography.
abstract: OBJECTIVE
  To assess the usefulness of transcranial Doppler sonography, we investigated the rate of blood flow signal recording failure in the middle cerebral artery in Japanese subjects. Furthermore, we studied the effect of increased emitted power on the rate of successful recording in some of the patients in whom recording failure had been detected at the standard transducer power of 100 mW/cm2.
  
  
  METHODS
  To evaluate the rate of successful recording, we measured blood flow signals in 597 patients (age range, 16 to 89 years) for screening of cerebrovascular disease by using a 2-MHz range-gated, pulsed-wave Doppler instrument at the standard transducer power. In 18 elderly patients with recording failure at the standard power, we assessed the effect of increased emitted power of 400 mW/cm2 on flow signal recording.
  
  
  RESULTS
  Blood flow signals were recorded in 920 (77.1%) of the 1194 middle cerebral arteries of the 597 patients studied. The rate of successful recording of bilateral middle cerebral artery flow signals (70.9%; 423 of 597 patients) decreased with age, especially in females (17.0% in women aged 70 years or older). In 12 of 18 elderly patients with recording failure at the standard power, blood flow signals could be detected at the increased emitted power of 400 mW/cm2.
  
  
  CONCLUSIONS
  The rate of successful recording of blood flow signals in Japanese subjects decreases with advancing age, especially in females. Increasing the emitted power markedly improves the successful recording rate.
authors.affiliation: First Department of Internal Medicine, Osaka University Medical School, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto
authors.forename: N
authors.initials: N
authors.lastname: Handa
authors.forename: H
authors.initials: H
authors.lastname: Maeda
authors.forename: H
authors.initials: H
authors.lastname: Hougaku
authors.forename: H
authors.initials: H
authors.lastname: Hashimoto
authors.forename: H
authors.initials: H
authors.lastname: Etani
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukamoto
authors.forename: T
authors.initials: T
authors.lastname: Kamada
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D002536:Cerebral Arteries / Q000000981:diagnostic imaging*; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D014463:Ultrasonography