title: CT detection of retroperitoneal gas associated with gas in intervertebral disks.
abstract: Three cases are presented with computed tomographic evidence of gas in retroperitoneal soft tissues in association with the so-called "vacuum phenomenon" (Knutsson sign) in lumbar disks. We review the explanations of Knutsson sign and offer an explanation of how extradiscal gas can occur in association with it.
mesh_terms: D000368:Aged; D004646:Emphysema / Q000000981:diagnostic imaging*; D005260:Female; D005740:Gases; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012187:Retroperitoneal Space / Q000000981:diagnostic imaging; D013115:Spinal Canal / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
chemical_list: D005740:Gases