Imaging tools transform diagnosis of osteoporosis

The incidence of osteoporotic fractures increases with age. Osteoporosis could, consequently, become a significant social/healthcare problem in developed countries where the population is aging. An early diagnosis of osteoporosis is fundamental to preventing complications and unnecessary suffering. This is now possible using precise imaging methods. The two main aims of imaging are to identify the presence of osteoporosis, and to calculate bone mass using semiquantitative or quantitative methods. Conventional radiography is typically used for the former, densitometric techniques for the latter. The radiological appearance of osteoporosis is essentially always the same, irrespective of the cause. Osteoporosis is still most commonly diagnosed on conventional radiography, a modality that is widely available. This is despite the advent of newer, highly accurate and precise quantitative diagnostic imaging techniques, such as dual x-ray absorptiometry (DXA) and quantitative CT (QCT). Conventional radiography is useful, both alone and in conjunction with CT or MRI, when detecting complications of osteopenia (e.g., fractures), for the differential diagnosis of osteopenia, or for follow-up examinations in specific clinical settings, such as progression of soft tissue calcifications, or signs of secondary hyperparathyroidism and osteomalacia in renal osteodystrophy. It is relatively insensitive to the detection of early disease, though. A substantial amount of bone loss (~30%) must occur before it can be detected on x-ray images. Variations in radiographic exposure factors, film development, and patients’ soft tissue thickness can also make it difficult to diagnose early signs of osteoporosis.