Bone Scintigraphy for Guidance of Targeted Treatment of Vertebral Compression Fractures

Abstract

Background: Vertebral compression fractures (VCFs) are prevalent in the elderly population and might be the source of back pain if they are fresh and yet unhealed. In many cases, it is a diagnostic challenge to differentiate fresh VCFs from healed united fractures, which retain similar radiographic characteristics but no longer generate pain. This information is crucial for appropriate management. The aim of this study was to evaluate the role of bone scintigraphy (BS) in identifying fresh VCFs appropriate for targeted treatment when compared to the findings of Computerized Tomography (CT). Methods: We retrospectively reviewed 190 patients with back pain suspected to stem from a recent VCF that underwent both a CT and a BS and compared the imaging patterns per vertebra. Results: The studies were concordant in the majority of cases (95.5%), diagnosing 84.4% normal vertebrae, 6.4% acute VCFs, and 4.7% chronic VCFs. However, in 37 patients, 45 occult acute VCFs were only detected on BS and not on CT. Multivariate logistic regression analysis revealed that these patients were older and had lower bone density compared to the rest of the study population. Additionally, 40 patients had acute VCFs visible on CT, but with no increased or low intensity uptake on BS. These cases were associated with a shorter time period between trauma and BS, a higher prevalence of male patients, and a higher bone density. Acute VCFs with no increased uptake or low levels of uptake were found only within the first six days of the trauma. Conclusions: BS detects radiologically occult fractures and can differentiate if a radiographically evident VCF is indeed clinically active, guiding possible treatment options. To avoid missing acute VCFs, BS should be performed six days or more after the injury.

Keywords: bone scintigraphy; computed tomography; occult fracture; osteoporosis; vertebral compression fracture.

Figure 1

Patterns of vertebrae appearance on sagittal spine CT. (A) Normal vertebra—retained height and continuous cortex. (B) Acute VCF showing a “step defect” in the anterior border and a “zone of impaction” caused by impaction of the trabeculae. (C) Non-union fracture—a non-healed fracture with an intervertebral cleft (white arrow). (D) Ankylotic fracture—a transverse fracture below an ankylotic spine segment. (E) Chronic fracture showing loss of height and smooth cortical borders. (F) State after percutaneous vertebroplasty (Post VP)—chronic fracture with loss of height and hyperdense cement in the vertebral body.

Figure 2

Distribution of VCFs according to type and location on CT.

Figure 3

Distribution of VCFs according to uptake intensity and location on bone scintigraphy.

Figure 4

Radiotracer uptake intensity according to time after trauma.

Figure 5

Occult fractures. A 78-year-old female complaining of back pain, without known trauma. CT was acquired on the day of admission and bone scintigraphy was performed 2 days after the CT. (A)—Sagittal spine CT shows a non-union fracture in L4. No other fractures are demonstrated. Bone density measured in L3 was 7 HUs, consistent with severe osteoporosis. (B)—Planar anterior and posterior bone scintigraphy shows high-intensity uptake in L2 and L3, suggestive of acute fractures. (C)—Axial, coronal, and sagittal SPECT show high-intensity uptake in L2 and L3.

Figure 6

High-intensity uptake in an acute fracture, no uptake in chronic fractures post-vertebroplasty. A 77-year-old female after trauma. CT was acquired on the day of injury and bone scintigraphy was performed 3 days after the injury. (A,B)—Sagittal spine CT (enlarged in B) show an acute fracture in T11 (white arrow) and chronic fractures after vertebroplasty in T12 and L3. (C)—Planar anterior and posterior bone scintigraphy show high-intensity uptake in T11 (black arrow), indicating an acute fracture and no increased uptake in T12 and L3, consistent with chronic fractures. Note also, high-intensity uptake is seen in the anterior aspect of the left acetabulum (black arrow head), consistent with an acute fracture.

Figure 7

Low-intensity uptake in an acute ankylotic VCF. A 72-year-old male. CT was acquired on the day of injury and bone scintigraphy was performed 3 days after the injury. (A)—Coronal, axial, and sagittal spine CT show an acute ankylotic fracture in L2 and a fracture involving an osteophyte in L1 (white arrow). (B)—Planar anterior and posterior bone scintigraphy do not show any increased uptake in L2. (C)—Coronal, sagittal, axial, and MIP SPECT show only low-intensity uptake in L2 (black arrow).

Figure 8

VCF diagnostic flow-chart. When MRI is unavailable or contraindicated. ** Bone scan should be obtained at least 48 h after injury or onset of pain.