Peter M. A. van Ooijen

Coronary artery calcium screening: current status and recommendations from the European Society of Cardiac Radiology and North American Society for Cardiovascular Imaging

Current guidelines and literature on screening for coronary artery calcium for cardiac risk assessment are reviewed for both general and special populations. It is shown that for both general and special populations a zero score excludes most clinically relevant coronary artery disease. The importance of standardization of coronary artery calcium measurements by multidetector CT is discussed.

Detection, visualization and evaluation of anomalous coronary anatomy on 16-slice multidetector-row CT

Early identification and evaluation of relatively frequent anomalous coronary anatomy is quite relevant because of the occurrence of sudden cardiac death or related symptoms of myocardial ischemia. Selective coronary angiography (CAG) is invasive, expensive and cannot always provide the required information adequately. Recently, non-invasive imaging techniques such as magnetic resonance imaging and multidetector-row computed tomography (MDCT) have been shown to provide a good anatomical view of the coronary artery tree. This study aims to demonstrate the value of 16-MDCT for evaluation of anomalous coronary anatomy. In 13 patients scanned using 16-MDCT, six different coronary anomalies were diagnosed [two absent left main, one single vessel left coronary artery (LCA), three LCA originating from the right (two with interarterial course), six right coronary artery originating from the left, one double left anterior descending (LAD)]. Mean diagnostic quality, recorded by two observers using a 5-point scale (1= non-diagnostic to 5= excellent diagnostic quality), resulted in a mean score of 3.73 (SD 1.19) without any non-diagnostic result. MDCT offers an accurate diagnostic modality to visualize the origin and course of anomalous coronary arteries by a three-dimensional display of anatomy. Shortcomings in CAG can be overcome by the use of contrast-enhanced MDCT.

Influence of scoring parameter settings on Agatston and volume scores for coronary calcification

Current multi-detector CT and electron beam tomography (EBT) technology enables the evaluation of coronary calcification. Multiple software packages are available to quantify calcification using several scoring algorithms implementing user-definable scoring parameters. We investigated the effect of scoring parameters on the calcium score outcome. Three parameters (four-connected or eight-connected, lesion size threshold and interpolation) are evaluated. Their theoretical influence on the scoring outcome is shown using simplified examples. To evaluate the effect in real data, we performed calcium scoring on randomly chosen EBT scans from 50 participants in an epidemiological study. Both the Agatston and volume scores were calculated. Changing from eight-connected to four-connected connectivity decreased both Agatston and volume scores (mean variability Agatston 3.15% and volume score −3.52%). Decreasing the threshold from 4 to 2 pixels increased the calcium scores because smaller lesions were also selected as calcified plaques (mean variability Agatston 16.23% and volume score 18.66%). Finally, the use of interpolation had a large negative effect on the volume score (mean variability −29.67%) and almost no effect on the Agatston score. Parameter settings in software for quantification for coronary calcification affect the calcium score outcome. Therefore, parameter settings for calcium scoring should be standardized.

Automatic Cobb angle determination from radiographic images.

Study Design. Automatic measurement of Cobb angle in patients with scoliosis. Objective. To test the accuracy of an automatic Cobb angle determination method from frontal radiographical images. Summary of Background Data. Thirty-six frontal radiographical images of patients with scoliosis. Methods. A modified charged particle model is used to determine the curvature on radiographical spinal images. Three curve fitting methods, piece-wise linear, splines, and polynomials, each with 3 variants were used and evaluated for the best fit. The Cobb angle was calculated out of these curve fit lines and compared with a manually determined Cobb angle. The best-automated method is determined on the basis of the lowest mean absolute error and standard deviation, and the highest R2. Results. The error of the manual Cobb angle determination among the 3 observers, determined as the mean of the standard deviations of all sets of measurements, was 3.37°. For the automatic method, the best piece-wise linear method is the 3-segments method. The best spline method is the 10-steps method. The best polynomial method is poly 6. Overall, the best automatic methods are the piece-wise linear method using 3 segments and the polynomial method using poly 6, with a mean absolute error of 4,26° and 3,91° a standard deviation of 3,44° and 3,60°, and a R2 of 0.9124 and 0.9175. The standard measurement error is significantly lower than the upper bound found in the literature (11.8°). Conclusion. The automatic Cobb angle method seemed to be better than the manual methods described in the literature. The piece-wise linear method using 3 segments and the polynomial method using poly 6 yield the 2 best results because the mean absolute error, standard deviation, and R2 are the best of all methods. Level of Evidence: 3

A model including sarcopenia surpasses the MELD score in predicting waiting list mortality in cirrhotic liver transplant candidates: A competing risk analysis in a national cohort

BACKGROUND & AIMS Frail patients with low model for end-stage liver disease (MELD) scores may be under-prioritised. Low skeletal muscle mass, namely sarcopenia, has been identified as a risk factor for waiting list mortality. A recent study proposed incorporating sarcopenia in the MELD score (MELD-Sarcopenia score). We aimed to investigate the association between sarcopenia and waiting list mortality, and to validate the MELD-Sarcopenia score (i.e. MELD + 10.35 * Sarcopenia). METHODS We identified consecutive patients with cirrhosis listed for liver transplantation in the Eurotransplant registry between 2007-2014 and measured skeletal muscle mass on computed tomography. A competing risk analysis was used to compare survival of patients with and without sarcopenia, and concordance (c) indices were calculated to assess performance of the MELD and MELD-Sarcopenia score. We created a nomogram of the best predictive model. RESULTS We included 585 patients with a median MELD score of 14 (interquartile range 9-19), of which 254 (43.4%) were identified as having sarcopenia. Median waiting list survival was shorter in patients with sarcopenia than those without (p <0.001). This effect was even more pronounced in patients with MELD ≤15. The discriminative performance of the MELD-Sarcopenia score (c-index 0.820) for three-month mortality was lower than MELD score alone (c-index 0.839). Apart from sarcopenia and MELD score, other predictive variables were occurrence of hepatic encephalopathy before listing and recipient age. A model including all these variables yielded a c-index of 0.851. CONCLUSIONS Sarcopenia was associated with waiting list mortality in liver transplant candidates with cirrhosis, particularly in patients with lower MELD scores. The MELD-Sarcopenia score was successfully validated in this cohort. However, incorporating sarcopenia in the MELD score had limited added value in predicting waiting list mortality. LAY SUMMARY In this study among patients with liver cirrhosis listed for liver transplantation, low skeletal muscle mass was associated with mortality on the waiting list, particularly in patients who were listed with low priority based on a low MELD score. However, adding these measurements to the currently used system for donor and organ allocation showed no added value.

Reproducibility of Standing Posture for X-Ray Radiography: A Feasibility Study of the BalancAid with Healthy Young Subjects

Unreliable spinal X-ray radiography measurement due to standing postural variability can be minimized by using positional supports. In this study, we introduce a balancing device, named BalancAid, to position the patients in a reproducible position during spinal X-ray radiography. This study aimed to investigate the performance of healthy young subjects’ standing posture on the BalancAid compared to standing on the ground mimicking the standard X-rays posture in producing a reproducible posture for the spinal X-ray radiography. A study on the posture reproducibility measurement was performed by taking photographs of 20 healthy young subjects with good balance control standing on the BalancAid and the ground repeatedly within two consecutive days. We analyzed nine posterior–anterior (PA) and three lateral (LA) angles between lines through body marks placed in the positions of T3, T7, T12, L4 of the spine to confirm any translocations and movements between the first and second day measurements. No body marks repositioning was performed to avoid any error. Lin’s CCC test on all angles comparing both standing postures demonstrated that seven out of nine angles in PA view, and two out of three angles in LA view gave better reproducibility for standing on the BalancAid compared to standing on the ground. The PA angles concordance is on average better than that of the LA angles.

DICOM data migration for PACS transition: procedure and pitfalls

PurposeTransition from one Picture Archiving and Communication System (PACS) to the other is costly and disruptive. Especially the migration of the DICOM data from the legacy to the new PACS is a very challenging task, and although such a migration will happen in every hospital, literature on methodologies to follow and possible problems and pitfalls is scarce. The objective of this work is to provide insight in the prerequisites for the legacy PACS before starting the migration with respect to vendor and DICOM considerations.MethodsThe steps involved in migration, possible methodologies, and areas of specific interest when planning migration are given. Possible challenges and problems are defined as well as issues that are often overlooked.ResultsA step-wise approach should be implemented for data migration. Careful planning and testing, continuous observation of the process, and involvement of all stakeholders including the old and new vendors are crucial for a successful transition from one PACS to the other.ConclusionA proper test migration is a crucial step in the PACS transition process, which can eliminate many of the problems in the actual migration. However, with any migration, there has to be a willingness to take a limited amount of risk since not all problems can nor will be identified in the test migration.

Multi-Dimensional Computed Coronary Visualization

Contemporary medical imaging modalities such as magnetic resonance imaging (MRI), electron beam computed tomography (EBCT), and multi-detector computed tomography (MDCT) are able to provide the clinician with a wealth of information. To be able to evaluate and diagnose the (projection and volumetric) data from modern non-invasive and invasive imaging modalities, new visualization techniques (both for image rendering and image processing) are increasingly used. These visualization techniques have been described frequently both for coronary imaging (Nakanishi et al. 1997; Chen and Carroll 1998; Oijen et al. 1997) and for other applications in medicine (Rankin 1999; Kirchgeorg and Prokop 1998; Calhoun et al. 1999).

Multi-detector CT and 3D imaging in a multi-vendor PACS environment

Abstract Introduction of new hard- and software techniques like Multi-Dectector Computed Tomography (MDCT) and 3D imaging has put new demands on the Picture Archiving and Communications System (PACS) environment within the radiology department. The daily use of these new techniques requires a good integration of these techniques within the PACS environment. Requirements should be made for the accessibility (ease and speed) of the large amounts of data and for the availability of 3D imaging. We feel that with good system integration of a multi-vendor environment these requirements can be met. This resulted in the environment proposed in this paper, which is installed at our institution.

Magnetic resonance and electron beam tomography coronary angiography

Recently, two non-invasive techniques Magnetic Resonance (MR) and Electron Beam Tomography (EBT) have been developed that are able to visualize the proximal and mid segments of the coronary arteries.