Utility of Delayed Whole-Body Bone Scintigraphy After Directed Three-Phase Scintigraphy

OBJECTIVE. The purpose of this study was to determine the diagnostic yield and clinical importance of delayed whole-body bone scintigraphy in directed three-phase examinations. MATERIALS AND METHODS. The records of 400 consecutively registered patients who underwent combined three-phase and delayed whole-body Tc-99m-methylene diphosphonate bone scintigraphy for a variety of indications were reviewed. Clinical indications, findings, recommendations, and outcome were assessed. RESULTS. Three-phase bone scintigraphy was performed on 156 men and boys and 244 women and girls (61%). Fifty-two patients (13%) were 17 years old or younger, and 236 patients (59%) were older than 40 years. The mean increase in study duration due to whole-body imaging was 25 minutes (range, 21-31 minutes). Excluding the three-phase area of interest, the whole-body examination had a normal tracer distribution in 131 examinations (33%), showed solely degenerative changes in 103 (26%), and showed findings unrelated to the area of interest in 166 patients (41%). In no case did the findings outside the area of interest alter the diagnosis or diagnostic certainty in the three-phase study, but those findings did generate 82 recommendations for additional diagnostic investigation. As a direct result of the recommendations, clinicians requested 18 radiographic, two CT, one MRI, and one ultrasound examinations, one additional bone scan, and two referrals to a consultant. Recommendations based on findings outside the three-phase area of interest affected treatment in one case: Temporomandibular joint uptake resulted in a referral for physical therapy. CONCLUSION. For most indications, delayed whole-body imaging after directed three-phase bone scintigraphy does not improve diagnostic yield, does not alter patient care, and may be an unnecessary use of medical resources.