New Evaluation Method for Bone Formation around a Fully Hydroxyapatite-Coated Stem Using Digital Tomosynthesis: A Retrospective Cross-Sectional Study

Digital tomosynthesis (DTS) is a new imaging technique derived from radiography, and its usefulness has been gradually reported in the field of orthopedic diagnosis in recent years. A fully hydroxyapatite (HA)-coated stem, which is used for total hip arthroplasty (THA), is a type of cementless stem that has been widely used recently and reported to have good results. However, stem loosening on plain radiographs is difficult to determine in some cases due to cancellous condensation around the stem. In this retrospective cross-sectional study, we compared the results of plain radiography versus DTS to evaluate the imaging findings after THA using a fully HA-coated stem. Twenty joints each in the 3 y and 1 y postoperative groups underwent plain radiography and DTS. On DTS, bone formation around the stem was confirmed in all cases; however, this formation was not reproducible on plain radiography, and there were cases in which the reaction could not be confirmed or cases with cancellous condensation resembling reactive lines. This reaction was not reproducible on plain radiographs, and in some cases, the reaction could not be confirmed, or there were cases with cancellous condensation that resembled reactive lines. Therefore, DTS was useful in the diagnosis of bone formation around the implant.

3D chest tomosynthesis using a stationary flat panel source array and a stationary detector: A Monte Carlo proof of concept.

3D imaging modalities such as computed tomography and digital tomosynthesis typically scan the patient from different angles with a lengthy mechanical movement of a single X-ray tube. Therefore, millions of 3D scans per year require expensive mechanisms to support a heavy X-ray source and have to compensate for machine vibrations and patient movements. However, recent developments in cold-cathode field emission technology allow the creation of compact, stationary arrays of emitters. Adaptix Ltd. has developed a novel, low-cost, square array of such emitters and demonstrated 3D digital tomosynthesis of human extremities and small animals. The use of cold-cathode field emitters also makes the system compact and lightweight. This paper presents Monte Carlo simulations of a concept upgrade of the Adaptix system from the current 60 kVp to 90 kVp and 120 kVp which are better suited for chest imaging. Between 90 kVp and 120 kVp, 3D image quality appears insensitive to voltage and at 90 kVp the photon yield is reduced by 40-50% while effective dose declines by 14%. A square array of emitters can adequately illuminate a subject for tomosynthesis from a shorter source-to-image distance, thereby reducing the required input power, and offsetting the 28-50% more input power that is required for operation at 90 kVp. This modelling suggests that lightweight, stationary cold-cathode X-ray source arrays could be used for chest tomosynthesis at a lower voltage, with less dose and without sacrificing image quality. This will reduce weight, size and cost, enabling 3D imaging to be brought to the bedside.

Usefulness of a Metal Artifact Reduction Algorithm in Digital Tomosynthesis Using a Combination of Hybrid Generative Adversarial Networks

In this study, a novel combination of hybrid generative adversarial networks (GANs) comprising cycle-consistent GAN, pix2pix, and (mask pyramid network) MPN (CGpM-metal artifact reduction [MAR]), was developed using projection data to reduce metal artifacts and the radiation dose during digital tomosynthesis. The CGpM-MAR algorithm was compared with the conventional filtered back projection (FBP) without MAR, FBP with MAR, and convolutional neural network MAR. The MAR rates were compared using the artifact index (AI) and Gumbel distribution of the largest variation analysis using a prosthesis phantom at various radiation doses. The novel CGpM-MAR yielded an adequately effective overall performance in terms of AI. The resulting images yielded good results independently of the type of metal used in the prosthesis phantom (p < 0.05) and good artifact removal at 55% radiation-dose reduction. Furthermore, the CGpM-MAR represented the minimum in the model with the largest variation at 55% radiation-dose reduction. Regarding the AI and Gumbel distribution analysis, the novel CGpM-MAR yielded superior MAR when compared with the conventional reconstruction algorithms with and without MAR at 55% radiation-dose reduction and presented features most similar to the reference FBP. CGpM-MAR presents a promising method for metal artifact and radiation-dose reduction in clinical practice.

Sight Unseen: Diagnostic Yield and Safety Outcomes of a Novel Multimodality Navigation Bronchoscopy Platform with Real-Time Target Acquisition

<b><i>Background:</i></b> Several advanced bronchoscopy platforms are currently available, but the clinical data supporting their use vary. Electromagnetic navigation bronchoscopy (ENB) remains the dominant technology; it is limited by its reliance on preoperative computed tomography, which only approximates patient anatomy during the procedure. Recently, ENB was enhanced with the (1) addition of digital tomosynthesis-based navigation correction, (2) improvements in planning algorithms, and (3) continuous real-time guidance (Illumisite™; Medtronic, Minneapolis, MN, USA). There are currently no clinical data on the diagnostic yield and safety profile of this system. <b><i>Objectives:</i></b> The primary objective of this study is to describe the diagnostic yield of the first 100 pulmonary parenchymal lesions sampled using the multimodality navigation bronchoscopy (MNB) platform. The secondary objective is to describe safety. <b><i>Methods:</i></b> In this single-center prospective observational study, a database was maintained to track patient, procedural, and outcome data for the first 100 consecutive lesions sampled using the MNB platform at an academic quaternary referral center. Descriptive statistics and univariate and multivariate analyses are reported. <b><i>Results:</i></b> The overall diagnostic yield of samples acquired was 79% (79/100). In the cohort where digital tomosynthesis was used, the diagnostic yield was 83% (69/83). Sensitivity for malignancy was 71% (52/73). Overall complication rates were low: pneumothorax (<i>n</i> = 3, 3%) and bleeding requiring intervention (<i>n</i> = 2, 2%). There were no procedural-related hospital admissions. <b><i>Conclusions:</i></b> The MNB system performed favorably. Platform superiority cannot be established without future prospective and comparative studies.

Development of a Quantitative Method to Evaluate Pedicle Screw Loosening After Spinal Instrumentation Using Digital Tomosynthesis

BackgroundIn general, the diagnosis of pedicle screw (PS) loosening is evaluated qualitatively based on the presence of a radiolucent area around the implant wider than 1 mm on plain radiographs and computed tomography (CT). Digital tomosynthesis is a novel imaging technology that can acquire reconstructed tomographic images of patients in different postures with relatively low radiation. In this study, PS loosening is evaluated quantitatively by measuring the PS displacement angle in the vertebrae using digital tomosynthesis. MethodsWe evaluated 41 patients who underwent posterior spinal fusion surgery using PS. The 72 pedicle screws at the cranial end of the fused segments were evaluated. The patients were divided in two groups, one with PS loosening (7 patients, 12 screws) and the other without PS loosening (34 patients, 60 screws), based on conventional CT findings. All patients underwent tomosynthesis in two different postures during a single CT session. ResultsThe displacement angles of the PS in patients in a lying position and in a standing position were measured using selected slices of the same cross-sectional view from digital tomosynthesis. The displacement angle was significantly greater in the PS loosening group (5.7°) than in the group without PS loosening (0.6°) (p＜0.01). Based on the ROC analysis, the optimal cut-off value of the PS displacement angle for identification of loosened screws was 1.7° with a sensitivity of 100% and specificity of 93% (AUC=0.98). ConclusionsThis new method using digital tomosynthesis has the potential to aid diagnosis of PS loosening quantitatively and more accurately than conventional evaluations.