deviation from optimal positioning for Tc99m-MDP bone scan in pediatric patients

Pediatric bone imaging is one of the most important and commonly requested procedures in nuclear medicine. Handling pediatric patients is not an easy task and requires additional care and experience. Proper patient positioning as well as modifications of the technique are crucial for adequate scanning and proper interpretation. Objectives: The aim of this study 'is to prove the effect of deviation from optimal position of pediatric on the accuracy of the study. Methods: Retrospective analyses of 55 pediatric patients (27 male, 28 female) with age (15 day to 16 years) old with positioning problems of bone scan were studied. Whole body image was obtained using 256 X 1024 matrix size with a speed of 8 min/ meter three hours after I.V injection of 2.5 mci/Kg of the child body weight of Tc99m-MDP. Spots views were performed using 256 X 256 matrix size, collecting 1000 Kcounts per view for the pelvic, sternum, rib cage and chest, 500 Kcounts for the extremities. The acquisition time was 5 minutes, 15 minutes when using the parallel hole and pinhole collimators respectively. Results: Improper positioning of skull was either due to tilting in 6 patients (1 male, 5 females) or moving in 3 patients (1 male, 2 females). There was cut of head only in 1 female. Chest was tilted in 9 patients (2 males, 7 females). Pelvic also was tilted in 9 patients (2 males, 7 females). Upper limp miss positioning was due to raised hand or shoulder in 25 patients (11 male, 14 female), or due to movement only in 1 patient. The major cause of lower limp abnormality position was not putting the feet in proper fixed position of internal rotation of feet in 39 patients (21 male, 16 female). Also because of moving legs in 1 female and cutting in 2 females. As patients age increasing as improper positioning is minimized. Improper positions of skull, chest, pelvic, and extremities due to asymmetry lead to false positive findings especially in sacroiliac joints in the case of pelvic because of increased uptake in the tilted organ. Conclusion: Improper positioning of the skull, chest, pelvic, and extremities are the most common on bone scans of our pediatric patients. Additional care must be taken in positioning pediatric patients for bone scanning to avoid diagnostic pitfalls. (authors)