Jp. Odonoghue et al., 3-PHASE BONE-SCINTIGRAPHY - ASYMMETRIC PATTERNS IN THE UPPER EXTREMITIES OF ASYMPTOMATIC NORMALS AND REFLEX SYMPATHETIC DYSTROPHY PATIENTS, Clinical nuclear medicine, 18(10), 1993, pp. 829-836
Three-phase Tc-99m MDP scans of 61 patients with asymptomatic upper ex
tremities randomly mixed with 17 studies of patients previously diagno
sed with reflex sympathetic dystrophy were blindly interpreted by thre
e observers. Asymmetry in any of the phases was recorded and a final d
iagnostic impression made. Thirteen of 17 reflux sympathetic dystrophy
studies were rated abnormal by at least two observers. Mild to striki
ng asymmetry was occasionally seen in all three phases in asymptomatic
upper extremities. Twenty of 61 asymptomatic patients (33%) were rate
d abnormal by at least one observer, and 5 of 61 studies (8%) were rat
ed abnormal by all observers. Asymmetries in normal patients occurred
more commonly in the earlier phases, while asymmetry in the delayed im
ages was mild in all but one. Tightening the criteria to exclude mild
asymmetry in delayed images resulted in unacceptably low sensitivity f
or reflex sympathetic dystrophy (29%). Interobserver variability was m
ost prominent in the flow and immediate images. In the diagnosis of re
flex sympathetic dystrophy a greater reliance should be placed on the
delayed images, which in themselves have an overall sensitivity of 94%
. It is important, however, to recognize that occasional mild and rare
moderate asymmetries in even the delayed images of normal individuals
result in an overall lower specificity of 77%.