A routine clinical x-ray may provide the first indication that a child has low bone mineral density if radiotranslucency of bones is observed. But if these images were digitally acquired, they may be misleading, according to an article published online March 8 in Academic Radiology.
A study evaluating the reliability of an osteopenia diagnosis based on digital radiography images of the appendicular skeleton compared to dual-energy x-ray absorptiometry (DEXA) suggests that digital images do not offer the diagnostic accuracy of a DEXA exam for pediatric patients. This additional exam should be performed when osteopenia is suspected.
The study involved a cohort of 58 patients, ranging in age from 4 to 18 years, who had both an x-ray exam and a DEXA exam performed within a six-month time period. DEXA scores were normal for 34 patients (59%). Sixteen children (28%) had severe osteopenia, and the remainder (13%) had mild osteopenia.
Digital radiographs included images of the knee, forearm, femur, foot, lower leg, ankle, hand, finger, elbow, and humerus. Two musculoskeletal radiologists, blinded to the diagnosis, read the images twice, once independently and once by consensus.
Independently, the radiologists were only able to identify 31% and 25% of patients with severe osteopenia, and 25% each of patients with mild osteopenia. Their interobserver agreement for the correct diagnosis of bone mineral density ranged from 71% for normal patients to 25% for patients with severe osteopenia and 0% for mild cases.
Co-author Dr. Martin Jordanov, assistant professor of radiology at Vanderbilt University Medical Center, and colleagues cited prior comparative studies of adult patients that produced similar results and were published in peer-review journals. The authors hypothesized that digital image postprocessing may confound a radiologist's ability to apply objective and subjective criteria to image analysis based on past experience with analog x-rays.
