title: Differentiation of renal cell carcinomas from angiomyolipomas by ultrasonic frequency dependent attenuation.
abstract: OBJECTIVE
  We determined the usefulness of ultrasonic frequency dependent attenuation in differentiating hyperechoic renal cell carcinoma from angiomyolipoma.
  
  
  METHODS
  Frequency dependent attenuation values were determined in 29 renal cell carcinomas and 13 angiomyolipomas.
  
  
  RESULTS
  Frequency dependent attenuation values were significantly lower in renal cell carcinomas than in angiomyolipomas (0.42 versus 0.76 dB./cm./MHz.). Two of the renal cell carcinomas were as hyperechoic as the angiomyolipomas but they were clearly differentiated by the low frequency dependent attenuation. Two other renal cell carcinomas exhibited high values because of the abundance of fibrous tissue. However, they were readily diagnosed by the typical low echoic B-mode images. Frequency dependent attenuation did not differ between histological types of renal cell carcinoma. One angiomyolipoma that was poor in fat and rich in muscle components had an exceptionally low frequency dependent attenuation. Therefore, frequency dependent attenuation values can be regarded as an inversion of computerized tomography numbers.
  
  
  CONCLUSIONS
  Frequency dependent attenuation measurement is a promising diagnostic aid in differentiating hyperechoic renal cell carcinomas from angiomyolipomas.
authors.affiliation: Department of Clinical Pathology, Jichi Medical School, Tochigi, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Taniguchi
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Obayashi
authors.forename: F
authors.initials: F
authors.lastname: Kawai
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018207:Angiomyolipoma / Q000000981:diagnostic imaging*; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography