Bone mineral density assessment using iterative reconstruction compared with quantitative computed tomography as the standard of reference

Constanze Mann,Jürgen Mews,Martina Plaschke,Ahi Sema Issever,Katharina Ziegeler

doi:10.1038/s41598-018-33444-5

Constanze Mann, Jürgen Mews + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-33444-5

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Abstract

This study examines the influence of iterative reconstruction on bone mineral density (BMD) measurement by comparison with standard quantitative computed tomography (QCT; reference) and two other protocols based on filtered back projection. Ten human cadaver specimens of the lumbar spine with a hydroxyapatite calibration phantom underneath, were scanned with 4 protocols: 1. standard QCT, 2. volume scan with FBP, 3. helical scan with FBP, and 4. helical scan with IR (Adaptive Iterative Dose Reduction 3D (AIDR3D)). Radiation doses were recorded as CT dose index (CTDIvol) and BMD, signal-to-noise and contrast-to-noise ratio were calculated. Mean hydroxyapatite concentration (HOA) did not differ significantly between protocols, ranging from 98.58 ± 31.09 mg cm3 (protocol 4) to 100.47 ± 30.82 mg cm3 (protocol 2). Paired sample correlations of HOA values for protocol 4 and protocols 1, 2 and 3 were nearly perfect with coefficients of 0.980, 0.979 and 0.982, respectively (p < 0.004). CTDIvol were 7.50, 5.00, 6.82 (±2.03) and 1.72 (±0.50) mGy for protocols 1, 2, 3 and 4 respectively. Objective image quality was highest for protocol 4. The use of IR for BMD assessment significantly lowers radiation exposure compared to standard QCT and protocols with FBP while not degrading BMD measurement.

Highlights

Osteoporosis is a systemic skeletal disease characterized by a low bone mineral density (BMD) and an associated increase in the risk of fracture[1]
The aim of our study was to evaluate the effect of iterative reconstruction (IR) on bone mineral density assessment and its different scan mode acquisition in comparison to standard quantitative computed tomography (QCT) and protocols reconstructed with filtered back projection (FBP)
Our results show that the use of IR for bone mineral density assessment significantly increases objective image quality and significantly decreases radiation dose compared to standard QCT and protocols with FBP while, most importantly in the context of our current study, the measured BMD remains the same

Summary

Introduction

Osteoporosis is a systemic skeletal disease characterized by a low bone mineral density (BMD) and an associated increase in the risk of fracture[1]. The only reference method accepted by the WHO to measure BMD is dual energy X-ray absorptiometry (DXA), a two-dimensional method which indirectly quantifies calcium from specific absorption values. DXA measures BMD by projection, including cortical bone, spondylophytes or even aortic calcifications, which can lead to false negative results and is one of the main reasons why osteoporosis is underdiagnosed[7,8,9]. A well-established alternative to DXA is quantitative computed tomography (QCT), a three-dimensional method which measures trabecular BMD in milligrams per cubic centimeter by indirectly quantifying hydroxyapatite in comparison to a reference phantom. Hip) compared to DXA, but doses are comparable to other x-ray-based imaging methods that might be performed in this patient group (e.g., spinal radiographs)[10]

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