Management of Diffuse Idiopathic Skeletal Hyperostosis (DISH) on Lumbar Spine X-ray in Adults Over 50

Introduction to DISH Management

The European Journal of Nuclear Medicine and Molecular Imaging and the Journal of the American College of Radiology recommend obtaining DXA scanning of both the lumbar spine and bilateral hips to accurately assess bone mineral density when DISH is identified on lumbar spine x-ray in an older adult, because DISH causes spuriously elevated BMD readings on lumbar spine DXA that can mask underlying osteoporosis 1, 2

DISH is a recognized artifact that falsely elevates lumbar spine BMD measurements on DXA, making it one of the most common causes (>81%) of spuriously elevated readings in older adults, according to the European Journal of Nuclear Medicine and Molecular Imaging and the Journal of the American College of Radiology 1, 2
The projectional nature of DXA means that ossification of the anterior longitudinal ligament and extraspinal ligaments in DISH will artificially increase bone density measurements, potentially masking true osteoporosis that requires treatment, as stated by the European Journal of Nuclear Medicine and Molecular Imaging and the Journal of the American College of Radiology 1, 2

Quantitative CT (QCT) of the lumbar spine and hip is rated as "usually appropriate" (rating 8/9) for initial osteoporosis assessment in patients with advanced degenerative changes like DISH, while standard DXA lumbar spine and hip receives a rating of 7/9 in this specific population, according to the Journal of the American College of Radiology 3, 2
The Journal of the American College of Radiology recommends ordering QCT of the lumbar spine and hips as the preferred modality when DISH is present, as it measures true volumetric trabecular bone density without interference from anterior ligamentous ossification 3, 2
If QCT is unavailable, the Journal of the American College of Radiology suggests obtaining DXA of bilateral hips and distal forearm (both rated 7/9), deliberately excluding the lumbar spine from diagnostic interpretation due to the DISH artifact 3, 2

The Journal of the American College of Radiology recommends adding vertebral fracture assessment (VFA) during the same DXA session if the patient has a T-score <-1.0 at any measurable site and meets any of these criteria: age ≥70 years (women) or ≥80 years (men), historical height loss >4 cm, self-reported prior vertebral fracture, or glucocorticoid use ≥5 mg prednisone daily for ≥3 months 4, 2

The European Journal of Nuclear Medicine and Molecular Imaging and the Journal of the American College of Radiology advise against relying solely on lumbar spine DXA T-scores in patients with DISH – the readings will be falsely reassuring and may delay diagnosis and treatment of true osteoporosis 1, 2
The European Journal of Nuclear Medicine and Molecular Imaging recommends not excluding vertebrae from DXA analysis based solely on a T-score difference ≥1.0 between adjacent vertebrae without visual inspection, as this may represent DISH affecting one level more than another 1
The European Journal of Nuclear Medicine and Molecular Imaging and the Journal of the American College of Radiology note that DISH patients may have both spuriously elevated lumbar BMD AND true osteoporosis at other skeletal sites, requiring hip and/or forearm assessment for accurate diagnosis 1, 2