CPT® Code 77078

Computed tomography (CT) for bone mineral density study, also referred to as quantitative computed tomography (QCT) densitometry, is a specialized imaging procedure that assesses bone mineral density (BMD) at one or more sites within the axial skeleton, which includes the pelvis, hips, and spine. This procedure is essential for diagnosing various bone diseases, evaluating the progression of these diseases, and monitoring treatment outcomes, particularly in patients with osteoporosis—a condition that significantly increases the risk of fractures. The CT technique utilizes multiple narrow X-ray beams that rotate around a single axis, capturing a series of two-dimensional images from various angles. These images are then digitally reconstructed by a computer to create a three-dimensional representation of the bone structure, allowing for the production of thin, cross-sectional images (slices) that provide detailed insights into bone density. QCT is recognized for its superior accuracy compared to traditional dual-energy X-ray absorptiometry (DEXA) scanning, as it offers a three-dimensional perspective that enables more precise calculations of bone density by considering both mass and volume. In contrast, DEXA measures BMD based on the attenuation of X-rays by the bone and does not account for depth, which can lead to less accurate assessments. Therefore, QCT densitometry is a valuable tool in the clinical evaluation of bone health.