Alternatives to DEXA for the assessment of bone density: a systematic review of the literature and future recommendations

Abstract

OBJECTIVE Osteoporosis has significant implications in spine fusion surgery, for which reduced spinal bone mineral density (BMD) can result in complications and poorer outcomes. Currently, dual-energy x-ray absorptiometry (DEXA) is the gold standard for radiographic diagnosis of osteoporosis, although DEXA accuracy may be limited by the presence of degenerative spinal pathology. In recent years, there has been an evolving interest in using alternative imaging, including CT and MRI, to assess BMD. In this systematic review of the literature, the authors assessed the use and effectiveness of MRI, opportunistic CT (oCT), and quantitative CT (qCT) to measure BMD. METHODS In accordance with the PRISMA guidelines, the authors conducted a systematic search for articles posted on PubMed between the years 2000 and 2022 by using the keywords "opportunistic CT, quantitative CT, MRI" AND "bone density" AND "spine." Inclusion criteria consisted of articles written in English that reported studies pertaining to human or cadaveric subjects, and studies including a measure of spinal BMD. Articles not related to spinal BMD, osteoporosis, or spinal surgery or reports of studies that did not include the use of spinal MRI or CT were excluded. Key study outcomes were extracted from included articles, and qualitative analysis was subsequently performed. RESULTS The literature search yielded 302 articles. Forty-two articles reported studies that met the final inclusion criteria. Eighteen studies utilized MRI protocols to correlate spinal BMD with vertebral bone quality scores, M-scores, and quantitative perfusion markers. Eight studies correlated oCT with spinal BMD, and 16 studies correlated qCT with spinal BMD. With oCT and qCT imaging, there was consensus that Hounsfield unit (HU) values > 160 demonstrated significant reduction in risk of osteoporosis, whereas HU values < 110 were significantly correlated with osteoporosis. CONCLUSIONS Osteoporosis is increasingly recognized as a significant risk factor for complications after spinal fusion surgery. Consequently, preoperative assessment of BMD is a critical factor to consider in planning surgical treatment. Although DEXA has been the gold standard for BMD measurement, other imaging modalities, including MRI, oCT, and qCT, appear to be viable alternatives and may offer cost and time savings.

Preoperative abnormal bone mineral density as a prognostic indicator in patients undergoing gastrectomy for gastric cancer: A cohort study

“…Low BMD poses a significant risk for fractures and falls, leading to considerable financial, physical, and psychosocial burdens on patients and impacting overall prognosis. While DXA remains the gold standard for BMD assessment, [9] there has been growing interest in alternative imaging modalities such as CT. CT scans offer the advantage of indirectly estimating BMD from HU measured on opportunistic scans of the abdomen, providing a preliminary screening tool to evaluate the necessity for a DXA scan in the clinical diagnosis of osteoporosis. For example, Cohen et al demonstrated in their study that an HU ≤ 110 indicates a high likelihood of abnormal BMD (osteoporosis or osteopenia), prompting further DXA examination.…”

“…Using a cutoff point of 110 HU, as defined by Cohen et al, HU values were dichotomized into abnormal BMD (≤110 HU) and normal BMD (>110 HU) categories. [9,14] Among the patient cohort, 114 (23.8%) individuals were categorized in the abnormal BMD group, while 364 (76.2%) individuals were classified in the normal BMD group. Although our cohort was dichotomized using the well-known cutoff point of 110 HU, it is noteworthy that this value is very close to the 25th percentile (113 HU) of the entire cohort, which is one of the recommended cutoff values for dichotomizing cohorts in clinical studies.…”

“…Dual-energy X-ray absorptiometry (DXA) is the gold standard for quantitatively measuring BMD [9] ; it categorizes BMD on a T-score scale where values ≤−2.5 indicate osteoporosis and values between <-1 and >-2.5 suggest osteopenia. [10] Despite the prominence of DXA, computed tomography (CT), which correlates strongly with DXA, [11] has garnered attention for estimating BMD from Hounsfield units (HU).…”

Long-Term Comparison of Two- and Three-Dimensional Computed Tomography Analyses of Cranial Bone Defects in Severe Parietal Thinning

“…While CT is ideal for evaluating the extent and severity of bone loss, it exposes the patient to ionizing radiation and is more expensive than conventional radiography. MRI, however, does not expose the patient to ionizing radiation and is better suited for evaluating soft tissues and bone marrow, but it has limited spatial resolution and may not provide sufficient details for assessing bone density [13]. Quantitative measures of bone density, such as bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA) or other specialized techniques, are certainly not sensitive enough for the skull.…”

Low Hounsfield unit values on computed tomography as a potential predictor of vertebral fracture in patients with rheumatoid arthritis: The KURAMA cohort study

“…One issue is that it can produce artifacts from implants or degenerative changes, such as subchondral sclerosis, osteophyte formation, vertebral compression fractures, and soft tissue calcification, which often coexist in elderly patients with low bone mass. 6,7 Additionally, DEXA is a two-dimensional evaluation method that cannot differentiate between cancellous and cortical bones. This distinction is important because the cancellous bone may be more indicative of vertebral fracture risk than the cortical bone.…”