Papers by Simon Wildermuth
BMC Pediatrics, 2021
Background Organ size is influenced by a number of factors. Age, height, weight, and ethnicity ar... more Background Organ size is influenced by a number of factors. Age, height, weight, and ethnicity are known influencing factors. Pediatric populations have changed over time, puberty beginning earlier resulting in a changing growth pattern of their organs. Hence, contemporary charts using local data are considered the most appropriate for a given population. Sonographic charts for liver size for a predominantly Caucasian population are limited, which has implications for clinical practice. The aim of this study was to define a contemporary normative range of liver and spleen sizes for a healthy, predominantly Caucasian population and for all pediatric age groups (0–18 years) and to investigate whether there is a size difference between genders and ethnicities. Methods Retrospective study including children with normal sonographic findings and no evidence of liver or splenic disease clinically. Craniocaudal and anteroposterior dimensions are measured for the right and left lobe of the l...
Skeletal Radiology, 2020
Objective To determine diagnostic confidence and inter-observer/intra-observer agreement in diffe... more Objective To determine diagnostic confidence and inter-observer/intra-observer agreement in differentiating epidural fibrosis from disc herniation and lumbar spinal stenosis parameters on magnetic resonance images (MRI) in postoperative lumbar spines with (Gad-MRI) and without (unenhanced MRI) intravenous gadolinium-based contrast agent. Subjects and methods N = 124 lumbar spine MRI examinations of four groups were included: 1-6 months, 7-18 months, 19-36 months, more than 37 months between lumbar spine surgery and imaging. Two radiologists evaluated Gad-MRI and unenhanced MRI: diagnostic confidence was determined as confident or unconfident. Inter-observer and intra-observer agreement were assessed in differentiating epidural fibrosis from disc herniation and for lumbar spinal stenosis parameters on MRI. Fisher's exact test and Cohen's kappa served for statistics. Results Diagnostic confidence in differentiating epidural fibrosis from disc herniation was significantly higher on Gad-MR images compared with unenhanced MRI at 1-18 months for observer 1 and at 1-6 months postoperatively for observer 2 (p values: 0.01-0.025). Inter-observer agreement at 1-6 months postoperatively for identification of epidural fibrosis was higher on Gad-MRI (kappa values: 0.53 versus 0.24). Inter-observer and intra-observer agreement for identification of disc herniation and for assessment of lumbar spinal stenosis parameters revealed inconsistent data, without a trend for higher inter-observer or intra-observer agreement on Gad-MRI compared with unenhanced MRI (kappa values: 0.17-0.75). Conclusion Gad-MR images compared with unenhanced MRI improved diagnostic confidence and agreement in differentiating epidural fibrosis from disc herniation for both observers in the first 6 months and for one observer in the first 18 months after lumbar spine surgery. After 18 months, Gad-MR images compared with unenhanced MRI did neither improve confidence nor agreement.
The Analyst, 2019
This study reveals distinct characteristics of minerals formed during gestational ageing using na... more This study reveals distinct characteristics of minerals formed during gestational ageing using nano-analytical characterization, and paves the way for the identification of markers for disease risks based on atypical placental mineral fingerprints.
Academic Radiology, 2019
CTDIvol volume CT dose index DLP dose length product Rationale and Objectives: To determine the v... more CTDIvol volume CT dose index DLP dose length product Rationale and Objectives: To determine the value of chest CT with tin filtration applying a dose equivalent to chest x-ray for the assessment of the Haller index for evaluation of pectus excavatum. Materials and Methods: Two hundred seventy-two patients from a prospective single center study were included and underwent a clinical standard dose chest CT (effective dose 1.8 § 0.7 mSv) followed by a low-dose CT (0.13 § 0.01 mSv) in the same session. Two blinded readers independently evaluated all data sets. Image quality for bony chest wall assessment was noted. Radiologists further assessed (a) transverse thoracic diameter, (b) anteroposterior thoracic diameter, and calculated (c) Haller index by dividing transverse diameter by anteroposterior diameter. The agreement of both readers in standard dose and low-dose CT was assessed using Lin's concordance correlation coefficient (p c). Results: Subjective image quality was lower for low dose compared to standard dose CT images by both readers (p < 0.001). In total, 99% (n = 540) of low-dose CT scans were rated as diagnostic for bony chest wall assessment by both readers. There was a high agreement for assessment of transverse diameter, anteroposterior diameter and Haller index comparing both readers in standard dose and lowdose CT with p c values indicating substantial agreement (i.e., 0.95> and 0.99) in 12/18 (67%) and almost perfect agreement (i.e., >0.99) in 6/18 (33%). Conclusion: Our study suggests that low-dose CT with tin filtration applying a radiation dose equivalent to a plain chest X-ray is excellent for assessing the Haller index.
Clinical imaging
To determine the value of ultra-low dose chest CT with tin filtration for ordinal coronary artery... more To determine the value of ultra-low dose chest CT with tin filtration for ordinal coronary artery calcium (CAC) risk scoring. 50 patients were prospectively included and underwent clinical standard dose chest CT (1.8±0.7mSv) and ultra-low dose CT (0.13±0.01mSv). Four radiologists estimated presence and extent of CAC. Weighted kappa values for CAC were 0.76-0.97 in standard dose and 0.75-0.95 in ultra-low dose CT (p<0.001). Good to excellent agreement was observed for CAC ordinal risk assessment, with readers reporting identical risk in 81% of cases. CAC risk can be qualitatively assessed from X-ray dose equivalent ungated chest CT.
European radiology, 2018
To investigate the impact of an adaptive detector collimation on the dose parameters and accurate... more To investigate the impact of an adaptive detector collimation on the dose parameters and accurateness of scan length adaption at prospectively ECG-triggered sequential cardiac CT with a wide-detector third-generation dual-source CT. Ideal scan lengths for human hearts were retrospectively derived from 103 triple-rule-out examinations. These measures were entered into the new scanner operated in prospectively ECG-triggered sequential cardiac scan mode with three different detector settings: (1) adaptive collimation, (2) fixed 64 × 0.6-mm collimation, and (3) fixed 96 × 0.6-mm collimation. Differences in effective scan length and deviation from the ideal scan length and dose parameters (CTDIvol, DLP) were documented. The ideal cardiac scan length could be matched by the adaptive collimation in every case while the mean scanned length was longer by 15.4% with the 64 × 0.6 mm and by 27.2% with the fixed 96 × 0.6-mm collimation. While the DLP was almost identical between the adaptive and...
European radiology, 2018
We investigated the potential reduction of patient exposure during invasive coronary angiography ... more We investigated the potential reduction of patient exposure during invasive coronary angiography (ICA) if the procedure had only been directed to the vessel with at least one ≥ 50% stenosis as described in the CT report. Dose reports of 61 patients referred to ICA because of at least one ≥ 50% stenosis on coronary CT angiography (CCTA) were included. Dose-area product (DAP) was documented separately for left (LCA) and right coronary arteries (RCA) by summing up the single DAP for each angiographic projection. The study population was subdivided as follows: coronary intervention of LCA (group 1) or RCA (group 2) only, or of both vessels (group 3), or further bypass grafting (group 4), or no further intervention (group 5). 57.4% of the study population could have benefitted from reduced exposure if catheterization had been directly guided to the vessel of interest as described on CCTA. Mean relative DAP reductions were as follows: group 1 (n = 18), 11.2%; group 2 (n = 2), 40.3%; group...
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2004
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2004
Die initiale Diagnostik bei polytraumatisierten Patienten im Schockraum ist derzeit eine Kombinat... more Die initiale Diagnostik bei polytraumatisierten Patienten im Schockraum ist derzeit eine Kombination aus konventioneller Röntgendiagnostik, Sonographie und Computertomographie. Die vorliegende Arbeit liefert eine Übersicht über den Stellenwert und die diagnostische Qualität der einzelnen Methoden hinsichtlich der Detektion von Verletzungsfolgen. Die Computertomographie ist dem Ultraschall im Nachweis von Organläsionen deutlich überlegen. Zudem sind therapierelevante Befunde am Thorax und am Stammskelett genauer diagnostizierbar als mit dem konventionellen Röntgen. Die Computertomographie kann als alleinige Methode zum Einsatz kommen, wenn sie die Befunde im Vergleich zur konventionellen Diagnostik und Sonographie in gleicher oder kürzerer Zeit zur Verfügung stellt. Hierzu sind technische und infrastrukturelle Voraussetzungen, wie die räumliche Integration eines MSCT-Scanners in den Schockraum, sowie ¾nderungen im CT-Protokoll und im Arbeitsablauf des Radiologen und der anderen beteiligten klinischen Fachrichtungen notwendig. Es werden ein optimiertes MSCT-Protokoll für die Untersuchung polytraumatisierter Patienten und ein Befundungsalgorithmus vorgestellt, bei dem im Rahmen eines Stufenschemas CT-Befunde gewichtet nach ihrer notfalltherapeutischen Relevanz erfasst und sofort dem behandelnden ¾rzteteam mitgeteilt werden.
European Journal of Radiology, 2017
Obesity Surgery, 2017
This study aims to determine the long-term prognostic value of coronary CT angiography (CCTA) pri... more This study aims to determine the long-term prognostic value of coronary CT angiography (CCTA) prior to bariatric surgery in severely obese patients with a body mass index (BMI) ≥35 kg/m. Seventy consecutive patients undergoing cardiac CT for coronary assessment prior to bariatric surgery were prospectively included. Images were analysed for the presence of coronary calcification and for non-obstructive (&lt;50%) or obstructive (&gt;50% stenosis) coronary artery disease (CAD). A median clinical follow-up of 6.1 years in 54 patients was obtained for major adverse cardiovascular events (MACEs), defined as death, non-fatal myocardial infarction or coronary revascularisation. Weight loss and BMI decrease following bariatric surgery were recorded. The median BMI prior to surgery was 46.9 kg/m. The median percentage of excess BMI loss after surgery was 75%. CT showed coronary calcification in 26 (48%) patients, whereas 28 (52%) patients had no calcification. CCTA revealed normal coronaries in 47 (87%) and non-obstructive CAD in 7 (13%) patients. No obstructive CAD was found. All patients successfully underwent bariatric surgery, and no MACE occurred neither perioperatively nor in the follow-up period. The negative predictive value of CCTA was 100% (95% confidence interval of 90.1-100.0%). In severely obese patients, the absence of obstructive CAD in cardiac CT prior to bariatric surgery with subsequently marked weight reduction has strong long-term prognostic implications for ruling out major adverse cardiac events in the postoperative period.
European Radiology, 2017
Purpose To prospectively evaluate the accuracy of ultralow radiation dose CT of the chest with ti... more Purpose To prospectively evaluate the accuracy of ultralow radiation dose CT of the chest with tin filtration at 100 kV for pulmonary nodule detection. Materials and methods 202 consecutive patients undergoing clinically indicated chest CT (standard dose, 1.8 ± 0.7 mSv) were prospectively included and additionally scanned with an ultralow dose protocol (0.13 ± 0.01 mSv). Standard dose CT was read in consensus by two board-certified radiologists to determine the presence of lung nodules and served as standard of reference (SOR). Two radiologists assessed the presence of lung nodules and their locations on ultralow dose CT. Sensitivity and specificity of the ultralow dose protocol was compared against the SOR, including subgroup analyses of different nodule sizes and types. A mixed effects logistic regression was used to test for independent predictors for sensitivity of pulmonary nodule detection. Results 425 nodules (mean diameter 3.7 ± 2.9 mm) were found on SOR. Overall sensitivity for nodule detection by ultralow dose CT was 91%. In multivariate analysis, nodule type, size and patients BMI were independent predictors for sensitivity (p < 0.001). Conclusions Ultralow dose chest CT at 100 kV with spectral shaping enables a high sensitivity for the detection of pulmonary nodules at exposure levels comparable to plain film chest X-ray. Keypoints • 91% of all lung nodules were detected with ultralow dose CT • Sensitivity for subsolid nodule detection is lower in ultralow dose CT (77.5%) • The mean effective radiation dose in 202 patients was 0.13 mSv • Ultralow dose CT seems to be feasible for lung cancer screening
European Journal of Radiology, 2016
Computer-aided detection (CAD) of solid pulmonary nodules in chest x-ray equivalent ultralow dose... more Computer-aided detection (CAD) of solid pulmonary nodules in chest x-ray equivalent ultralow dose chest CT-first in-vivo results at dose levels of 0.13 mSv
Rofo Fortschr Rontgenstrahl, 2005
Rofo Fortschr Rontgenstrahl, 2008
Rofo Fortschr Rontgenstrahl, 2004
Radiology, 2001
See also the editorial by Levine (pp 313-315) in this issue.
Lecture Notes in Computer Science, 2002
We present a system that opens the way to apply virtual endoscopy on the small intestines. A high... more We present a system that opens the way to apply virtual endoscopy on the small intestines. A high-quality image acquisition technique based on MR as well as a haptically assisted interactive segmentation tool was developed. The system was used to generate a topologically correct model of the small intestines. The influence of haptic interaction on the efficiency of centerline definition has been demonstrated by a user study.
Uploads
Papers by Simon Wildermuth