CT-based evaluation of volumetric bone density in fragility fractures of the pelvis-a matched case-control analysis

This matched case-control study compared the computed tomography (CT)-based regional bone density of patients with fragility fractures of the sacrum to a control without fracture. Patients with a sacral fracture demonstrated a significantly lower regional bone density of the sacrum, the sacral bone density not being correlated with the BMD by DXA of the spine.

INTRODUCTION

The aim of this study is to compare the computed tomography-based regional bone density measured by Hounsfield units (HUs) in patients with and without fragility fractures of the sacrum.

METHODS

Patients aged ≥ 50 years with a fragility fracture of the sacrum were compared to patients of similar age and gender who had a fall from standing height without fracture (n = 46). A matched case-control analysis was conducted by retrospective chart review and assessment of areal bone mineral density by lumbar DXA and by volumetric regional HU measurements in uncalibrated CT scans of the sacrum.

RESULTS

Patients with a sacral fracture (age 74 ± 11 years) showed a lower bone density in the body of S1 (HU 85 ± 22) when compared to the matched control group without fracture (age 73 ± 10 years, HU 125 ± 37, p < 0.001). The CT-based bone density of S1 did not correlate with the DXA values of the lumbar spine (r = 0.223, p = 0.136), and lumbar spine T-scores did not differ between the groups (- 2.0 ± 1.3 vs. - 1.9 ± 1.2, p = 0.786). All measurements are based on uncalibrated scans, and absolute HU values are restricted to scans made on Siemens SOMATOM Force or SOMATOM Edge scanners.

CONCLUSIONS

Patients with fragility fractures of the sacrum demonstrated a lower regional volumetric bone density of the sacrum when compared to a cohort without a fracture. Local sacral volumetric bone density as measured by CT seems to be independent from the areal BMD as measured by DXA of the lumbar spine.

LEVEL OF EVIDENCE

level III.

Quantitative cerebral perfusion imaging in children and young adults with Moyamoya disease: comparison of arterial spin-labeling-MRI and H(2)[(15)O]-PET

BACKGROUND AND PURPOSE

Cerebral perfusion assessment is important in the preoperative evaluation and postoperative follow-up of patients with Moyamoya disease. The objective of this study was to evaluate the correlation of quantitative CBF measurements performed with arterial spin-labeling-MR imaging and H2[(15)O]-PET in children and young adults with Moyamoya disease.

MATERIALS AND METHODS

Thirteen children and young adults (8 female patients; age, 9.7 ± 7.1 years; range, 1-23 years) with Moyamoya disease underwent cerebral perfusion imaging with H2[(15)O]-PET (Discovery STE PET/CT, 3D Fourier rebinning filtered back-projection, 128 × 128 × 47 matrix, 2.34 × 2.34 × 3.27 mm(3) voxel spacing) and arterial spin-labeling (3T scanner, 3D pulsed continuous arterial spin-labeling sequence, 32 axial sections, TR = 5.5 seconds, TE = 25 ms, FOV = 24 cm, 128 × 128 matrix, 1.875 × 1.875 × 5 mm(3) voxel spacing) within less than 2 weeks of each other. Perfusion of left and right anterior cerebral artery, MCA, and posterior cerebral artery territories was qualitatively assessed for arterial spin-labeling-MR imaging and H2[(15)O]-PET by 2 independent readers by use of a 3-point-Likert scale. Quantitative correlation of relative CBF with cerebellar normalization between arterial spin-labeling-MR imaging and H2[(15)O]-PET was evaluated in a volume-based approach for each vascular territory after 3D image coregistration.

RESULTS

Interreader agreement was good (κ = 0.67-0.69), and strong and significant correlations were found between arterial spin-labeling-MR imaging and H2[(15)O]-PET for both qualitative perfusion scoring (ρ = 0.77; P < .001) and quantitative perfusion assessment of relative CBF with cerebellar normalization (r = 0.67, P < .001).

CONCLUSIONS

In children and young adults with Moyamoya disease, quantitative evaluation of CBF is possible with the use of arterial spin-labeling-MR imaging without ionizing radiation or contrast injection with a good correlation to H2[(15)O]-PET after cerebellar normalization.

Incorporating New Materials and Techniques into Clinical Practice

This article outlines the subjects presented and discussed at the December 2012 IADR Dental Materials Innovation Workshop held at King’s College London. Incorporating new materials and techniques into clinical practice was considered from 4 perspectives: (1) Accelerating the “research to regulatory approval” process was presented with current developments in the United States, with the National Institutes of Health/Food and Drug Administration process as a working example; (2) intellectual property and regulatory requirements were discussed across the well-established US and EU frameworks, as well as the more recently developed procedures across Brazil, Russia, India, and China; (3) the challenges and opportunities of incorporating innovations into dental education were considered with reference to the future needs of both students and faculty; and (4) the key but difficult and unpredictable step of translating such innovations into routine dental practice was then explored. Constructive and far-ranging discussion among the broadly based Workshop participants (from dental research, education, practice, and industry, as well as environmental organizations and the World Health Organization) mapped out key issues for the future. The focus was on facilitating the more timely adoption of improvements in both materials and techniques to improve patient health and health systems, while minimizing environmental impact.

Bisphosphonate-induced osteonecrosis of the jaw: comparison of disease extent on contrast-enhanced MR imaging, [18F] fluoride PET/CT, and conebeam CT imaging

BACKGROUND AND PURPOSE

Imaging of bisphosphonate-induced osteonecrosis of the jaw is essential for surgical planning. We compared the extent of BONJ on contrast-enhanced MR imaging, [(18)F] fluoride PET/CT, and panoramic views derived from standard conebeam CT with clinical pre- and intraoperative examinations.

MATERIALS AND METHODS

Between February 2011 and January 2012, ten subjects with written informed consent (9 women; mean, 69.6 years; range, 53-88 years) were included in this prospective ethics-board-approved study. Patients underwent CEMR imaging, [(18)F] fluoride PET/CT, and CBCT and were clinically examined pre- and intraoperatively. Surgery was performed, and BONJ was histologically confirmed in 9 patients. Location and extent of BONJ on different modalities/examinations were graphically compared (0 = no pathologic finding, 1 = smallest, 5 = largest extent of BONJ). Rank tests were used to assess overall and paired differences of ratings in 9 patients. A P value <.05 was considered statistically significant.

RESULTS

Significant differences in BONJ extent among different modalities and examinations were found (P < .001). The highest median rank was seen in PET/CT (4 ± 1.12) and CEMR imaging (4 ± 1.01), followed by intraoperative examinations (3 ± 0.71), CBCT (2 ± 0.33), and preoperative examinations (1 ± 0). No significant differences were found between PET/CT and CEMR imaging (P = .23), except when comparing PET/CT to either CBCT, pre- and intraoperative examinations (all P < .05). Preoperative examinations showed significantly less extensive disease than all other modalities/examinations (all P < .05).

CONCLUSIONS

[(18)F] fluoride PET/CT and CEMR imaging revealed more extensive involvement of BONJ compared with panoramic views from CBCT and clinical examinations.

Metallic artefact reduction with monoenergetic dual-energy CT: systematic ex vivo evaluation of posterior spinal fusion implants from various vendors and different spine levels

OBJECTIVES

To evaluate optimal monoenergetic dual-energy computed tomography (DECT) settings for artefact reduction of posterior spinal fusion implants of various vendors and spine levels.

METHODS

Posterior spinal fusion implants of five vendors for cervical, thoracic and lumbar spine were examined ex vivo with single-energy (SE) CT (120 kVp) and DECT (140/100 kVp). Extrapolated monoenergetic DECT images at 64, 69, 88, 105 keV and individually adjusted monoenergy for optimised image quality (OPTkeV) were generated. Two independent radiologists assessed quantitative and qualitative image parameters for each device and spine level.

RESULTS

Inter-reader agreements of quantitative and qualitative parameters were high (ICC = 0.81-1.00, κ = 0.54-0.77). HU values of spinal fusion implants were significantly different among vendors (P < 0.001), spine levels (P < 0.01) and among SECT, monoenergetic DECT of 64, 69, 88, 105 keV and OPTkeV (P < 0.01). Image quality was significantly (P < 0.001) different between datasets and improved with higher monoenergies of DECT compared with SECT (V = 0.58, P < 0.001). Artefacts decreased significantly (V = 0.51, P < 0.001) at higher monoenergies. OPTkeV values ranged from 123-141 keV. OPTkeV according to vendor and spine level are presented herein.

CONCLUSIONS

Monoenergetic DECT provides significantly better image quality and less metallic artefacts from implants than SECT. Use of individual keV values for vendor and spine level is recommended.

KEY POINTS

• Artefacts pose problems for CT following posterior spinal fusion implants. • CT images are interpreted better with monoenergetic extrapolation using dual-energy (DE) CT. • DECT extrapolation improves image quality and reduces metallic artefacts over SECT. • There were considerable differences in monoenergy values among vendors and spine levels. • Use of individualised monoenergy values is indicated for different metallic hardware devices.

[Diagnostic reference levels for X-ray examinations: update 2010]

The diagnostic reference levels (DRLs) for diagnostic and interventional X-ray procedures established in 2003 were updated in July 2010 by the German Federal Office for Radiation Protection on the basis of mean patient doses in X-ray facilities surveyed by the so-called competent medical expert offices. The new DRLs are immediately in force and in most cases markedly below the respective old levels. Moreover DRLs for pediatric CT examinations have been newly introduced. This article briefly summarizes the concept of DRLs and the essential changes.

[MR-imaging of joints]

Magnetic resonance (MR) imaging is a well established, non-invasive method in the evaluation of joint pathologies. Basically four different MR imaging techniques are used in the clinical routine: (1) conventional MR imaging of joints, (2) intravenously contrast-enhanced MR imaging of joints, (3) direct MR arthrography with intraarticular injection of contrast medium and (4) indirect MR arthrography after intravenous application of contrast medium. Additionally, a variety of new MR imaging techniques are available and currently used for clinical research. These techniques have a great potential for clinical use in the future.

Exploring beyond methacrylates

PURPOSE

This article focuses on the polymerization shrinkage of current dental composites as their major disadvantage and to find new routes for a solution.

MATERIALS AND METHODS

A brief introduction describes selected methods for the shrinkage determination as well as some principal solutions to overcome the shrinkage problem.

RESULTS

Siloranes, a new class of ring opening monomers, are presented as a promising resin matrix for dental composites. The synthesis of these monomers, and further consequences of the new chemistry for the formulation are discussed. Two selected silorane composites are presented with their mechanical data and their volume shrinkage.

New trends in glass-ionomer chemistry

This paper surveys the different routes to develop glass-ionomer cements (GICs) (glass polyalkenoate cements). Using a new commercially available material, Ketac-Molar, the particular ways of improving conventional GICs are described (mainly optimizing the concentration and molecular weight of the polyacid as well as the particle size distribution of the glass). High cross-linkage in the GIC matrix is the key issue to achieve superior physical properties (three- body wear resistance, compressive and flexural strength, surface hardness and solubility). This is proven by differential scanning calorimetry and infrared spectroscopy.

[Rocatec system--adhesion by tribochemical coating]

The Rocatec procedure as a novel acrylic/metal bonding system is presented. This procedure is based on the tribochemical application of a layer of a ceramic bonding agent by sand blasting, followed by the application of a silane solution. Its particular advantages are the speed and accuracy of coating, the fact that the adhesive layer can be visually checked, and that thermal stresses to the metallic framework are avoided. Shear/compression and tensile tests reveal increased bonding strength values with the Rocatec bonding system than with mechanical bead retention, even after thermocycling and storage in water for one year.