BACKGROUND - The prevalence and cost of unnecessary advanced imaging studies (AIS) in the evaluation of long bone cartilaginous lesions have not been studied previously.
METHODS - A total of 105 enchondromas and 19 chondrosarcomas arising in long bones from July 2008 until April 2012 in 121 patients were reviewed. Advanced imaging was defined as MRI, CT, bone scan, skeletal survey, or CT biopsy. Two blinded radiologists independently reviewed the initial imaging study and determined if further imaging was indicated based on that imaging study alone. The cost of imaging was taken from our institution's global charge list. Imaging was deemed unnecessary if it was not recommended by our radiologists after review of the initial imaging study. The difference in cost was calculated by subtracting the cost of imaging recommended by each radiologist from the cost of unnecessary imaging. The sensitivity and specificity for distinguishing enchondromas from chondrosarcomas was calculated. A minimum of 2 years from diagnosis of an enchondroma was required to monitor for malignant transformation.
RESULTS - Of patients diagnosed with an enchondroma, 85 % presented with AIS. The average enchondroma patient presented with one unnecessary AIS. The radiologists' interpretations agreed 85 % of the time for enchondromas and 100 % for chondrosarcomas. The sensitivity and specificity for distinguishing enchondromas from chondrosarcomas was 95 % for one radiologist and 87 and 95 % for the other. The average unnecessary cost per enchondroma patient was $1,346.18.
CONCLUSIONS - Unnecessary AIS are frequently performed and are a significant source of expense. The imaging algorithms outlined in this study may reduce unnecessary AIS.