P. M. A. van Ooijen

Comparison of analog and digital preoperative planning in total hip and knee arthroplasties. A prospective study of 173 hips and 65 total knees.

Introduction Digital correction of the magnification factor is expected to yield more accurate and reliable preoperative plans. We hypothesized that digital templating would be more accurate than manual templating for total hip and knee arthroplasties. Patients and methods Firstly, we established the interobserver and intraobserver reliability of the templating procedure. The accuracy and reliability of digital and analog plans were measured in a series of 238 interventions, which were all planned using both techniques. Results Interobserver reliability was good for the planning of knee arthroplasties (κ-values 0.63–0.75), but not more than moderate for the planning of hip arthroplasties (κ-values 0.22–0.54). Analog plans of knee arthroplasties systematically underestimated the component sizes (1.1 size on average), while the digital procedure proved to be accurate (0.1–0.4 size too small on average). The following figures show percentage of cases receiving a correct implant, allowing an error of one size. Digital templating of the hip arthroplasty was less frequently correct (cemented cup and stem: 72% and 79%; uncemented cup and stem: 52% and 66%) than analog planning (cemented cup and stem: 73% and 89%; uncemented cup and stem: 64% and 52%). Interpretation Planning of component sizes for total knee arthroplasties is an accurate procedure when performed digitally. Our digital preoperative plans which were performed by someone other than the surgeon were less accurate than the analog plans prepared by the surgeon.

Digital correction of magnification in pelvic x rays for preoperative planning of hip joint replacements: Theoretical development and clinical results of a new protocol

The introduction of digital radiological facilities leads to the necessity of digital preoperative planning, which is an essential part of joint replacement surgery. To avoid errors in the preparation and execution of hip surgery, reliable correction of the magnification of the projected hip is a prerequisite. So far, no validated method exists to accomplish this. We present validated geometrical models of the x-ray projection of spheres, relevant for the calibration procedure to correct for the radiographic magnification. With help of these models a new calibration protocol was developed. The validity and precision of this procedure was determined in clinical practice. Magnification factors could be predicted with a maximal margin of error of 1.5%. The new calibration protocol is valid and reliable. The clinical tests revealed that correction of magnification has a 95% margin of error of -3% to +3%. Future research might clarify if a strict calibration protocol, as presented in this study, results in more accurate preoperative planning of hip joint replacements.

A new approach to the assessment of lumen visibility of coronary artery stent at various heart rates using 64-slice MDCT

Coronary artery stent lumen visibility was assessed as a function of cardiac movement and temporal resolution with an automated objective method using an anthropomorphic moving heart phantom. Nine different coronary stents filled with contrast fluid and surrounded by fat were scanned using 64-slice multi-detector computed tomography (MDCT) at 50–100 beats/min with the moving heart phantom. Image quality was assessed by measuring in-stent CT attenuation and by a dedicated tool in the longitudinal and axial plane. Images were scored by CT attenuation and lumen visibility and compared with theoretical scoring to analyse the effect of multi-segment reconstruction (MSR). An average increase in CT attenuation of 144 ± 59 HU and average diminished lumen visibility of 29 ± 12% was observed at higher heart rates in both planes. A negative correlation between image quality and heart rate was non-significant for the majority of measurements (P > 0.06). No improvement of image quality was observed in using MSR. In conclusion, in-stent CT attenuation increases and lumen visibility decreases at increasing heart rate. Results obtained with the automated tool show similar behaviour compared with attenuation measurements. Cardiac movement during data acquisition causes approximately twice as much blurring compared with the influence of temporal resolution on image quality.

Social media for radiologists: an introduction

AbstractSocial media, which can be defined as dynamic and interactive online communication forums, are becoming increasingly popular, not only for the general public but also for radiologists. In addition to assisting radiologists in finding useful profession-related information and interactive educational material in all kinds of formats, they can also contribute towards improving communication with peers, clinicians, and patients. The growing use of social networking in healthcare also has an impact on the visibility and engagement of radiologists in the online virtual community. Although many radiologists are already using social media, a large number of our colleagues are still unaware of the wide spectrum of useful information and interaction available via social media and of the added value these platforms can bring to daily practice. For many, the risk of mixing professional and private data by using social media creates a feeling of insecurity, which still keeps radiologists from using them. In this overview we aim to provide information on the potential benefits, challenges, and inherent risks of social media for radiologists. We will provide a summary of the different types of social media that can be of value for radiologists, including useful tips on how to use them safely and efficiently.Main Messages• Online social networking enhances communication and collaboration between peers • Social media facilitate access to educational and scientific information • Recommendations and guidelines from policymakers and professional organisations are needed • Applications are desired for efficient and secure exchange of medical images in social media

3D ultrasound reconstruction of spinal images using an improved Olympic Hole-filling method

We propose a new Hole-filling algorithm by improving the Olympic operator, and we also apply it to generate the volume in our freehand 3D ultrasound reconstruction of the spine. First, the ultrasound frames and position information are compounded into a 3D volume using the Bin-filling method. Then, the Hole-filling method is used to repair gaps in the volume. The conventional Olympic operator defines the empty voxels by sorting the neighboring voxels, removing the n% of the upper and lower values, and averaging them to attain the value to fill the empty voxels. The empty voxel estimation can be improved by thresholding the range width of its neighboring voxels and adjusting it to the average values. The method is tested on a hole-manipulated volume derived from a cropped 3D ultrasound volume of a part of the spine. Our MAE calculation on the proposed technique shows improved result compared to all tested existing methods.

Spinal Curvature Determination from an X-Ray Image Using a Deformable Model

This paper presents a spinal curvature determination from frontal X-ray images of scoliotic patients. A new deformable model, Modified CPM (Charged Particles Model), has been developed and used to determine the spinal curvature. The Modified CPM is a new approach of a deformable model based on CPM, which was introduced in 2004. The X-ray image is charged negatively according to the edge-map or gradient-magnitude image. The particles are attracted towards the contour of the object of interest, because this contour is very dark, thus charged very negatively. We modified the CPM by putting springs between the particles to prevent the particles from moving away and keep the movement of the particles in the appropriate distance without reducing the flexibility to follow the curvature. The results of the implementation show the effectiveness of the modified charged-particle model for spinal curvature determination on X-ray images.

Use of a thin-section archive and enterprise 3-dimensional software for long-term storage of thin-slice CT data sets-a reviewers' response.

Current developments in storage solutions, PACS, and client-server systems allow for 3D imaging at the desktop. This can be achieved together with full storage into PACS of all slices, including the very large thin-section CT datasets. This paper describes a possible setup, which has been in operation for several years now, in response to an article by Meenan et al. previously published in this journal (1).

Non-invasive assessment of coronary artery geometry using coronary CTA

AIM To assess the association of coronary artery geometry with the severity of coronary artery disease (CAD). METHODS 73 asymptomatic individuals at increased risk of CAD due to peripheral vascular disease (18 women, mean age 63.5 ± 8.2 years) underwent coronary computed tomography angiography (coronary CTA) using first generation dual-source CT. Curvature and tortuosity of the coronary arteries were quantified using semi-automatically generated centerlines. Measurements were performed for individual segments and for the entire artery. Coronary segments were labeled according to the presence of significant stenosis, defined as >70% luminal narrowing, and the presence of plaque. Comparisons were made by segment and by artery, using linear mixed models. RESULTS Overall, median curvature and tortuosity were, respectively, 0.094 [0.071; 0.120] and 1.080 [1.040; 1.120] on a per-segment level, and 0.096 [0.078; 0.118] and 1.175 [1.090; 1.420] on a per-artery level. Curvature was associated with significant stenosis at a per-segment (p < 0.001) and per-artery level (p = 0.002). Curvature was 16.7% higher for segments with stenosis, and 13.8% higher for arteries with stenosis. Tortuosity was associated with significant stenosis only at the per-segment level (p = 0.002). Curvature was related to the presence of plaque at the per-segment (p < 0.001) and per-artery level (p < 0.001), tortuosity was only related to plaque at the per-segment level (p < 0.001). CONCLUSION Coronary artery geometry as derived from coronary CTA is related to the presence of plaque and significant stenosis.

Improvement of radiology reporting in a clinical cancer network: impact of an optimised multidisciplinary workflow

PurposeTo assess the effectiveness of implementing a quality improvement project in a clinical cancer network directed at the response assessment of oncology patients according to RECIST-criteria.MethodsRequests and reports of computed tomography (CT) studies from before (n = 103) and after (n = 112) implementation of interventions were compared. The interventions consisted of: a multidisciplinary working agreement with a clearly described workflow; subspecialisation of radiologists; adaptation of the Picture Archiving and Communication System (PACS); structured reporting.ResultsThe essential information included in the requests and the reports improved significantly after implementation of the interventions. In the requests, mentioning start date increased from 2% to 49%; date of baseline CT from 7% to 64%; nadir date from 1% to 41%. In the reports, structured layout increased from 14% to 86%; mentioning target lesions from 18% to 80% and non-target lesions from 11% to 80%; measurements stored in PACS increased from 76% to 97%; labelled key images from 38% to 95%; all p values < 0.001.ConclusionThe combination of implementation of an optimised workflow, subspecialisation and structured reporting led to significantly better quality radiology reporting for oncology patients receiving chemotherapy. The applied multifactorial approach can be used within other radiology subspeciality areas as well.Key points• Undeveloped subspecialisation makes adherence to RECIST guidelines difficult in general hospitals.• A clinical cancer network provides opportunities to improve healthcare.• Optimised workflow, subspecialisation and structured reporting substantially improve request and report quality.• Good interdisciplinary communication between oncologists, radiologists and others contributes to quality improvement.

Semiautomatic, Quantitative Measurement of Aortic Valve Area Using CTA: Validation and Comparison with Transthoracic Echocardiography

Objective. The aim of this work was to develop a fast and robust (semi)automatic segmentation technique of the aortic valve area (AVA) MDCT datasets. Methods. The algorithm starts with detection and cropping of Sinus of Valsalva on MPR image. The cropped image is then binarized and seed points are manually selected to create an initial contour. The contour moves automatically towards the edge of aortic AVA to obtain a segmentation of the AVA. AVA was segmented semiautomatically and manually by two observers in multiphase cardiac CT scans of 25 patients. Validation of the algorithm was obtained by comparing to Transthoracic Echocardiography (TTE). Intra- and interobserver variability were calculated by relative differences. Differences between TTE and MDCT manual and semiautomatic measurements were assessed by Bland-Altman analysis. Time required for manual and semiautomatic segmentations was recorded. Results. Mean differences from TTE were −0.19 (95% CI: −0.74 to 0.34) cm2 for manual and −0.10 (95% CI: −0.45 to 0.25) cm2 for semiautomatic measurements. Intra- and interobserver variability were 8.4 ± 7.1% and 27.6 ± 16.0% for manual, and 5.8 ± 4.5% and 16.8 ± 12.7% for semiautomatic measurements, respectively. Conclusion. Newly developed semiautomatic segmentation provides an accurate, more reproducible, and faster AVA segmentation result.