title: Can tissue dielectric constant measurement aid in differentiating lymphoedema from lipoedema in women with swollen legs?
abstract: BACKGROUND
  Distinguishing lymphoedema from lipoedema in women with swollen legs can be difficult. Local tissue water content can be quantified using tissue dielectric constant (TDC) measurements.
  
  
  OBJECTIVE
  To examine whether TDC measurements can differentiate untreated lower extremity lymphoedema from lipoedema, and to test interobserver agreement.
  
  
  METHODS
  Thirty-nine women participated in the study; 10 patients with lipoedema (LipP), nine patients with untreated lymphoedema (U-LP), 10 patients with lymphoedema treated with compression bandaging for ≥ 4 weeks (T-LP) and 10 healthy controls. All subjects were measured at three predefined sites (foot, ankle and lower leg). All groups except U-LP were measured by three blinded investigators. Using a handheld device, a 300-MHz electromagnetic wave is transmitted into the skin via a 2.5-mm depth probe. TDC calculated from the reflected wave is directly proportional to tissue water content ranging from 1 (vacuum) to 78.5 (pure water).
  
  
  RESULTS
  Mean ± SD TDC values for U-LP were 48.8 ± 5.2. TDC values of T-LP, LipP and controls were 34.0 ± 6.6, 29.5 ± 6.2 and 32.3 ± 5.7, respectively. U-LP had significantly higher TDC values in all measurement sites compared with all other groups (P < 0.001). A cut-off value of 40 for ankle and lower-leg measurements correctly differentiated all U-LP from LipP and controls. Intraclass correlation coefficients were 0.94 for the ankle and the lower leg and 0.63 for the foot.
  
  
  CONCLUSIONS
  TDC values of U-LP were significantly higher than those of T-LP, LipP and controls and may aid in differentiating lymphoedema from lipoedema. Interobserver agreement was high in ankle and lower-leg measurements but low in foot measurements.
authors.affiliation: Department of Dermatology and Copenhagen Wound Healing Centre, Copenhagen Lymphoedema Centre, Bispebjerg University Hospital, Bispebjerg bakke 23, DK-2400, Copenhagen NV, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Birkballe
authors.forename: M R
authors.initials: MR
authors.lastname: Jensen
authors.forename: S
authors.initials: S
authors.lastname: Noerregaard
authors.forename: F
authors.initials: F
authors.lastname: Gottrup
authors.forename: T
authors.initials: T
authors.lastname: Karlsmark
mesh_terms: D000328:Adult; D000368:Aged; D000842:Ankle; D001834:Body Water / Q000502:physiology*; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004487:Edema / Q000209:etiology*; D004568:Electrodiagnosis / Q000379:methods*; D005260:Female; D005528:Foot; D006801:Humans; D007866:Leg; D065134:Lipedema / Q000175:diagnosis*; D008209:Lymphedema / Q000175:diagnosis*; D008875:Middle Aged; D015588:Observer Variation; D055815:Young Adult