Factors affecting the sensitivity and specificity of the three-phase technetium bone scan in the diagnosis of reflex sympathetic dystrophy syndrome in the upper extremity.

The three-phase technetium bone scan has been recommended for use in the diagnosis of the reflex sympathetic dystrophy syndrome with a sensitivity and specificity of greater than 90%. A retrospective chart review was conducted of 63 patients who had three-phase technetium bone scan as part of a work-up for unexplained upper extremity pain, to determine the predictive value of the three-phase technetium bone scan in reflex sympathetic dystrophy syndrome, and what factors might affect it. The prevalence of definite or probable reflex sympathetic dystrophy syndrome, as assessed by Kozin's criteria, was 26% in this sample. The 3-hour delayed image demonstrated a sensitivity = 50%; specificity = 92%; positive predictive value = 67%, and negative predictive value = 84%. This was not improved using the data from the blood flow or pool phase. The sensitivity of 50% is lower than previous reports. The predictive value of the three-phase technetium bone scan was affected by the duration of symptoms and the age of the patient. Duration of symptoms less than 6 months, or ages more than 50 years substantially increased the sensitivity and positive predictive value of the three-phase technetium bone scan.

Predictive value of the three-phase technetium bone scan in diagnosis of reflex sympathetic dystrophy syndrome.

Reflex sympathetic dystrophy syndrome (RSDS) is a painful and disabling problem, the diagnosis of which can be difficult to confirm by objective measures. The three-phase technetium bone scan (TPBS), with a combined sensitivity and specificity of greater than 90%, has been recommended for use in the diagnosis of RSDS. The purpose of this study was to determine the predictive value and usefulness of the TPBS in the diagnosis of RSDS and to discover how the predictive value might be influenced by demographic and medical factors (eg, duration of symptoms). A retrospective chart review was conducted of 119 patients who underwent a TPBS as part of a workup for unexplained limb pain. Twenty-five patients met the Kozin criteria for definite or probable RSDS. All patients were injected with technetium-99m methylene diphosphonate and scanned using established criteria. The three-hour delayed image demonstrated a sensitivity of 44%, a specificity of 92%, a positive predictive value of 61%, and a negative predictive value of 86%. The blood-flow and pool-imaging phases added no further sensitivity or specificity to that achieved by the uptake scan in patients with upper-extremity involvement. Blood-flow and pool-imaging did improve the predictive value of the TPBS in patients with involvement of the lower extremities. We conclude that a more cost-effective approach to diagnosis of upper-extremity RSDS is to use the uptake scan alone.