A longitudinal study using tibial ultrasonometry as a bone assessment technique in children with acute lymphoblastic leukaemia

Background: Several longitudinal studies have shown contradictory results regarding the change in bone status in children with acute lymphoblastic leukaemia (ALL) using dual-energy X-ray absorptiometry as the bone assessment technique. Objective: To determine whether a more recently developed bone assessment technique which does not use radiation, tibial ultrasonometry, can be used for the detection of short-term changes. Patients and methods: From January 1997 to February 2001, 37 patients (25 boys, 12 girls, mean age 9.0 years, range 3.0-16.8 years) were included in a longitudinal study to assess changes in bone status induced by the disease itself and/or treatment. Of these 37 patients, 35 had a measurement at the start of therapy (t0), 26 at 6 months (t6), 24 at 12 months (t12), 11 at 24 months (t24) and 9 at 36 months (t36). For assessment of bone mass, the tibial ultrasound (US) device SoundScan Compact was used, which measures the speed of sound (SOS) along the cortex of the tibia over a fixed length of 5 cm at the mid-tibial point. Results: The SOS standard deviation (SD) scores were significantly lower at t6, t12, t24 and t36 than at baseline (t0). The biggest change was found between t0 and t6. During follow-up, no significant correlation was found between changes from baseline of height SD scores and SOS SD scores, indicating that tibial ultrasonometry was not measuring growth. After ending therapy (t36), no further growth retardation was found. Conclusions: Short-term changes of SOS SD scores in children with ALL can be detected by tibial ultrasonometry. Tibial ultrasonometry measures a change in bone status, not growth.