Pulmonary nodule size evaluation with chest tomosynthesis and CT: a phantom study

Objective:

We compared digital tomosynthesis (TOMO) and chest CT in terms of assessing the sizes of nodules located in zones where evaluation by simple radiography is limited.

Methods:

A total of 48 images comprising phantom nodules of four sizes in six different locations were used. Nodule size measurement errors for measurements using TOMO and CT images compared with the actual size from each observer were calculated. The inter- and intraobserver repeatability of the measured values and the agreement between the two techniques were assessed using the method described by Bland and Altman.

Results:

The mean measurement errors for all of the nodules and four observers were −0.84 mm [standard deviation (SD), 0.60 mm] on TOMO and −0.18 mm (SD, 0.71 mm) on CT images. The mean measurement errors for the different observers ranged from −1.11 to −0.55 mm for TOMO and from −0.39 to 0.08 mm for CT. Assessing the agreement between nodule size measurements using TOMO and CT resulted in mean measurement errors of −0.65 mm, with a 95% limit of agreement of −2.53 to 1.22 mm for comparison of TOMO with CT.

Conclusion:

Our results suggest that nodule sizes obtained using TOMO and chest CT are comparable, even for nodules located in areas where the size measurement is limited on simple radiography.

Advances in knowledge:

TOMO and CT can be used interchangeably, even for nodules located in a blind area on simple radiography.Solitary lung nodule detection has increased owing to the widespread use of CT imaging. Nevertheless, the most commonly used routine examination for lung nodules continues to be chest radiography, because it uses low radiation doses, is economical and is easy to use. Because chest radiographic images are two-dimensional projections of three-dimensional structures, early lung cancer detection on chest radiographs is often challenging. The projection of pulmonary vessels, bones and part of the mediastinum on lung fields often partially or completely obscures the pulmonary nodules, resulting in failure by the radiologist to detect lung nodules.^1,2Digital tomosynthesis (TOMO) has recently been applied to chest imaging for the detection of subtle nodules on simple radiography, with promising results.^3,4 It has been introduced as a modality with the potential to provide images similar to CT but at a comparably reduced cost and radiation exposure.⁴ James et al⁵ reported that 74% of lung nodules ≥4 mm in diameter that can be identified on CT can also be detected using TOMO. Vikgren et al⁶ also reported that 92% of nodules ≥4 mm in diameter are detectable using TOMO. In 2012, Johnsson et al⁷ compared the ability of TOMO and CT to detect nodule size in 20 patients and found that both methods could be used interchangeably for these measurements. This result calls for caution, however, because the limit of agreement (LOA) between the modalities is wider than for the intraobserver variability of each modality.Based on these studies, we hypothesized that TOMO is comparable to CT imaging for the detection of nodules located in areas where size measurement is limited using simple chest radiography because of overlapping structures. The purpose of this study was to assess the size determination of nodules located in these zones by TOMO and chest CT.     

Evaluation of Engraftment of Superparamagnetic Iron Oxide-Labeled Mesenchymal Stem Cells Using Three-Dimensional Reconstruction of Magnetic Resonance Imaging in Photothrombotic Cerebral Infarction Models of Rats

Objective

To evaluate engraftment by visualizing the location of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) three-dimensionally in photothrombotic cerebral infarction (PTCI) models of rats.

Materials and Methods

Magnetic resonance imaging (MRI) of an agarose block containing superparamagnetic iron oxide (SPIO)-labeled hBM-MSCs was performed using a 3.0-T MRI, T2-(T2WI), T2^*-(T2^*WI), and susceptibility-weighted images (SWI). PTCI was induced in 6 rats, and 2.5 × 10⁵ SPIO-labeled hBM-MSCs were infused through the ipsilateral internal carotid artery (ICA group) or tail vein (IV group). MRI was performed on days 1, 3, 7, and 14 after stem cell injection. Dark signal regions were confirmed using histology. Three-dimensional MRI reconstruction was performed using the clinical workflow solution to evaluate the engraftment of hBM-MSCs. Volumetric analysis of the engraftment was also performed.

Results

The volumes of SPIO-labeled hBM-MSCs in the phantom MRI were 129.3, 68.4, and 25.9 µL using SWI, T2^*WI, and T2WI, respectively. SPIO-labeled hBM-MSCs appeared on day 1 after injection, encircling the cerebral infarction from the ventral side. Dark signal regions matched iron positive cells and human origin (positive) cells. The volume of the engraftment was larger in the ICA group on days 1, 3, and 7, after stem cell injection (p < 0.05 on SWI). SWI was the most sensitive MRI pulse sequence (p < 0.05). The volume of infarction decreased until day 14.

Conclusion

The engraftment of SPIO-labeled hBM-MSCs can be visualized and evaluated three-dimensionally in PTCI models of rats. The engraftment volume was larger in the ICA group than IV group on early stage within one week.     

Outcomes of Combined Shelf Acetabuloplasty with Femoral Varus Osteotomy in Severe Legg-Calve-Perthes (LCP) Disease: Advanced Containment Method for Severe LCP Disease

Background

Standard treatments may provide adequate containment in mild to moderate Legg-Calve-Perthes disease (LCPD), but they can be problematic in more severe cases. The purpose of this study was to report the results of combined shelf acetabuloplasty with femoral varus osteotomy in severe LCPD.

Methods

We reviewed 12 patients who had undergone combined shelf acetabuloplasty with femoral varus osteotomy. The indications for this type of operation were: (1) above 8 years of age at clinical onset; (2) massive femoral epiphysis involvement (Catterall group 4, lateral pillar C); (3) femoral head lateral subluxation on the anteroposterior radiograph; and (4) impending hinged abduction on preoperative magnetic resonance imaging or arthrography. The mean age was 9.3 years (range, 8 to 10.8 years). The patients were clinically evaluated with Iowa hip score and leg length discrepancy at the final follow-up. Radiographic outcome was assessed using the Stulberg classification to evaluate femoral head sphericity. The presence of osteoarthritis was evaluated by the Tonnis classification. Correlation analysis was conducted to analyze the preoperative factors that were strongly associated with patients'' outcomes.

Results

The mean follow-up period was 10.1 years (range, 7.1 to 13.2 years). Functional grade was excellent in all patients at last follow-up (mean, 92; range, 82 to 99). The mean leg length discrepancy after skeletal maturity was 0.9 cm (range, 0 to 1.7 cm). There were no significant complications or need for additional surgery. Radiographically, 92% of patients reached satisfactory outcomes: Stulberg grade I, 0 cases; Stulberg grade II, 4 cases (34%); Stulberg III, 7 cases (58%), Stulberg IV, 1 case (8%); and Stulberg V, 0 cases. There was no osteoarthritis by Tonnis classification.

Conclusions

The surgical outcomes for combined shelf acetabuloplasty with femoral varus osteotomy in severe LCPD patients over 8 years old are comparable with other advanced surgical methods. In the cases of severe disease that match our inclusion criteria, our containment method could be another treatment option.     

Feasibility and safety of same-day discharge and shortened bedrest after atrial fibrillation ablation

Journal of Interventional Cardiac Electrophysiology - While initial studies suggest that same-day discharge or shortened bedrest may be feasible for some patients following atrial fibrillation (AF)...     

Endoscopic Bilateral Stent-in-Stent Versus Stent-by-Stent Deployment in Advanced Malignant Hilar Obstruction: A Meta-Analysis and Systematic Review

Digestive Diseases and Sciences - There is no clear data to compare the effectiveness and safety of bilateral stent-in-stent (SIS) or stent-by-stent (SBS) deployment for advanced malignant hilar...     

A Comparison of Accuracy of Different Dental Restorative Materials between Intraoral Scanning and Conventional Impression-Taking: An In Vitro Study

The properties of underlying substrates influence the quality of an intraoral scan, but few studies have compared the outcomes using common restorative materials. In this study, we aimed to compare the accuracy of digital and conventional impressions recorded for four different dental materials as the substrates. Experimental crowns were produced with a metallic surface (gold or cobalt-chromium alloy (Co-Cr)) or without a metallic surface (zirconia or PMMA (polymethyl methacrylate)). A conventional impression was made in the conventional group (CON group), and gypsum models were subsequently scanned with a tabletop scanner. An intraoral scanner was used to scan the crowns either after applying a powder spray to reduce the surface reflectivity (IOS-P group) or without the powder spray (IOS group). The scans were assessed in three dimensions for precision and trueness. The accuracy did not differ between the CON and IOS groups for the non-metallic crowns. However, it was statistically different for the Co-Cr metallic crown, reducing trueness observed between groups as CON > IOS > IOS-P. The study evidences the differences in outer surface accuracy observed with a change in the substrate material to be imaged using an oral scanner and with the impression method. These findings suggest that the restoration material present in the oral cavity should be considered when selecting an impression-taking method.