Purpose
Generation of graspable three-dimensional objects applied for surgical planning, prosthetics and related applications using 3D printing or rapid prototyping is summarized and evaluated.
...Materials and methods
Graspable 3D objects overcome the limitations of 3D visualizations which can only be displayed on flat screens. 3D objects can be produced based on CT or MRI volumetric medical images. Using dedicated post-processing algorithms, a spatial model can be extracted from image data sets and exported to machine-readable data. That spatial model data is utilized by special printers for generating the final rapid prototype model.
Results
Patient–clinician interaction, surgical training, medical research and education may require graspable 3D objects. The limitations of rapid prototyping include cost and complexity, as well as the need for specialized equipment and consumables such as photoresist resins.
Conclusions
Medical application of rapid prototyping is feasible for specialized surgical planning and prosthetics applications and has significant potential for development of new medical applications.
The German Lung Cancer Screening Intervention Trial (LUSI) is one of the European randomized trials investigating the efficacy of low-dose multislice computed tomography (MSCT) as a screening tool ...for lung cancer. In the evaluation of the first (prevalence) screening round, we observed exceptionally high early recall rates, which made the routine application of MSCT screening questionable. Because screening may behave differently in subsequent (incidence) screening rounds, we analyzed (a) basic characteristics for the annual rounds 2 to 4, which have now also been completed, and (b) the first 3 years with complete follow-up since time of randomization.
Data material was the data record of LUSI after the fourth screening round and the 3-year follow-up had been completed. Basic characteristics of screening, e.g., early recall rate, detection rate, and interval cancers as well of proportion of advanced cancers, were descriptively evaluated and, if informative, group differences were tested for statistical significance.
Early recall rates were significantly lower in the subsequent screening rounds than in the first one if the MSCT information from the previous screening rounds was available. Detection and biopsy rates were approximately 1% or lower, ratio of benign:malignant biopsies: 1:1.6 to 1:3.
Our recent data may not only settle one concern regarding high recall rates in routine MSCT screening but also indicate that screening must be strictly organized to be effective. Performance indicators are similar to those in mammography screening. Nevertheless, possible consequences for the participants (diagnostic workup of suspicious findings, biopsies) are more invasive than in mammography screening.
The onset and spontaneous development of cystic fibrosis (CF) lung disease remain poorly understood. In the present study, we used volumetric computed tomography (VCT) as a new method for ...longitudinal in vivo monitoring of early lesions and disease progression in CF-like lung disease in β-epithelial Na(+) channel (ENaC)-transgenic (TG) mice. Using a VCT scanner prototype (80 kV, 50 mA·s, scan time 19 s and spatial resolution 200 μm), βENaC-TG mice and wild-type (WT) littermates were examined longitudinally at 10 time-points from neonatal to adult ages, and VCT images were assessed by qualitative and quantitative morphological parameters. We demonstrate that VCT detected early-onset airway mucus obstruction, diffuse infiltrates, atelectasis and air trapping as characteristic abnormalities in βENaC-TG mice. Furthermore, we show that early tracheal mucus obstruction predicted mortality in βENaC-TG mice and that the density of lung parenchyma was significantly reduced at all time-points in βENaC-TG compared with WT mice (median ± sem -558 ± 8 HU in WT versus -686 ± 16 HU in βENaC-TG at 6 weeks of age; p < 0.005). Our study demonstrates that VCT is a sensitive, noninvasive technique for early detection and longitudinal monitoring of morphological abnormalities of CF-like lung disease in mice, and may thus provide a useful tool for pre-clinical in vivo evaluation of novel treatment strategies for CF.
To compare image quality and metal artifact reduction between virtual monochromatic spectral imaging (VMSI), linearly blended dual-energy (DE) and single-energy (SE) images, each with and without ...dedicated iterative metal artifact reduction (iMAR) for CT-guided biopsy.
A biopsy trocar was positioned in the liver of six pigs. DE (Sn140/100kVp) and SE (120kVp/200mAs) acquisitions were performed with equivalent dose. From dual-energy datasets DE Q30-3 images and VMSI between 40-180 keV in steps of 20 keV were generated. From SE datasets I30-3 images were reconstructed. All images were reconstructed with and without iMAR. Objective image quality was analyzed applying density measurements at standardized positions (e.g. trocar tip and liver parenchyma adjacent to the trocar tip) and semi-automated threshold based segmentation. Subjective image quality was performed using semi-quantitative scores. Analyses were performed by two observers.
At the trocar tip quantitative image analysis revealed significant difference in CT numbers between reconstructions with iMAR compared to reconstructions without iMAR for VMSI at lower keV levels (80 and 100 keV; p = 0.03) and DE (p = 0.03). For liver parenchyma CT numbers were significantly higher in VMSI at high keV compared to low keV (p≤0.01). VMSI at high keV also showed higher CT numbers compared to DE and SE images, though not the level of statistical significance. The best signal-to-noise ratio for VMSI was at 80 keV and comparable to DE and SE. Noise was lowest at 80 keV and lower than in DE and SE. Subjective image quality was best with VMSI at 80 keV regardless of the application of iMAR. iMAR significantly improved image quality at levels of 140 keV and 160 keV. Interreader-agreement was good for quantitative and qualitative analysis.
iMAR improved image quality in all settings. VMSI with iMAR provided metal artifact reduction and better image quality at 80 keV and thus could improve the accurate positioning in CT-guided needle biopsy. In comparison, DE imaging did not improve image quality compared to SE.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary Objective To prospectively compare chemical-exchange saturation-transfer (CEST) with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping to assess the biochemical cartilage ...properties of the knee. Method Sixty-nine subjects were prospectively included (median age, 42 years; male/female = 32/37) in three cohorts: 10 healthy volunteers, 40 patients with clinically suspected cartilage lesions, and 19 patients about 1 year after microfracture therapy. T2 mapping, dGEMRIC, and CEST were performed at a 3 T MRI unit using a 15-channel knee coil. Parameter maps were evaluated using region-of-interest analysis of healthy cartilage, areas of chondromalacia and repair tissue. Differentiation of damaged from healthy cartilage was assessed using receiver-operating characteristic (ROC) analysis. Results Chondromalacia grade 2–3 had significantly higher CEST values ( P = 0.001), lower dGEMRIC (T1-) values ( P < 0.001) and higher T2 values ( P < 0.001) when compared to the normal appearing cartilage. dGEMRIC and T2 mapping correlated moderately negative (Spearman coefficient r = −0.56, P = 0.0018) and T2 mapping and CEST moderately positive ( r = 0.5, P = 0.007), while dGEMRIC and CEST did not significantly correlate ( r = −0.311, P = 0.07). The repair tissue revealed lower dGEMRIC values ( P < 0.001) and higher CEST values ( P < 0.001) with a significant negative correlation ( r = −0.589, P = 0.01), whereas T2 values were not different ( P = 0.54). In healthy volunteers' cartilage, CEST and dGEMRIC showed moderate positive correlation ( r = 0.56), however not reaching significance ( P = 0.09). ROC-analysis demonstrated non-significant differences of T2 mapping vs CEST ( P = 0.14), CEST vs dGEMRIC ( P = 0.89), and T2 mapping vs dGEMRIC ( P = 0.12). Conclusion CEST is able to detect normal and damaged cartilage and is non-inferior in distinguishing both when compared to dGEMRIC and T2 mapping.
During the past decade significant developments have been achieved in the field of magnetic resonance imaging (MRI), enabling MRI to enter the clinical arena of chest imaging. Standard protocols can ...now be implemented on up-to-date scanners, allowing MRI to be used as a first-line imaging modality for various lung diseases, including cystic fibrosis, pulmonary hypertension and even lung cancer. The diagnostic benefits stem from the ability of MRI to visualize changes in lung structure while simultaneously imaging different aspects of lung function, such as perfusion, respiratory motion, ventilation and gas exchange. On this basis, novel quantitative surrogates for lung function can be obtained. This book provides a comprehensive overview of how to use MRI for imaging of lung disease. Special emphasis is placed on benign diseases requiring regular monitoring, given that it is patients with these diseases who derive the greatest benefit from the avoidance of ionizing radiation.
Abstract Objective To assess with dynamic contrast-enhanced ultrasound (CEUS) and transient arterial occlusion whether the muscular micro-perfusion in patients with peripheral arterial disease (PAD) ...is improved after angioplasty or surgery. Materials and methods This study had local institutional review board approval. Written informed consent was obtained from all 20 patients with PAD, Fontaine stage IIb (mean age, 64 years), who participated in the study. Low-MI CEUS (7 MHz; MI, 0.28) was applied to the mainly affected lower leg after start of a continuous automatic intravenous injection of 4.8 mL SonoVue® . Muscle-perfusion was monitored by CEUS before, during, and after provocation by arterial occlusion at the thigh level lasting for 60 s. CEUS examination was performed a second time within 14 days after angioplasty ( n = 15), thrombendarterectomy ( n = 2), angioplasty and thrombendarterectomy ( n = 1), or bypass ( n = 2). Clinical amelioration was re-evaluated within 6 months after the intervention using a 4-point scale. Results Ankle-brachial-index (ABI) increased from 0.8 ± 0.2 to 0.9 ± 0.3 after treatment ( p = 0.01). Time to maximum CEUS signal ( tmax ) shortened from 26 ± 14 s to 14 ± 4 s ( p = 0.004). The slope to maximum after transient occlusion ( m2 ) changed to steeper values (6.4 ± 5.8 ∼mL/s versus 10.2 ± 5.0 ∼mL/s; p = 0.04). Shortened tmax predicted improvement in the patients’ intermittent leg pain and therefore successful therapy outcome. Conclusion Dynamic CEUS with transient arterial occlusion can visualize the treatment-induced improvement of muscular micro-perfusion in patients with PAD.
Objectives This study aims to test whether inter-observer variability and time of diameter measurements for thoracic endovascular aortic repair (TEVAR) are improved by semiautomatic centerline ...analysis compared to manual assessment. Methods Preoperative computed tomography (CT) angiographies of 30 patients with thoracic aortic disease (mean age 66.8 ± 11.6 years, 23 males) were retrospectively analysed by two blinded experts in vascular radiology. Maximum aortic diameters at three positions relevant to TEVAR were assessed (P1, distal to left common carotid artery; P2, distal to left subclavian artery; and P3, proximal to coeliac trunk) using three measurement techniques: manual axial slices (axial), manual double-oblique multiplanar reformations (MPRs) and semiautomatic centerline analysis. Results Diameter measurements by both centerline analysis and the axial technique did not significantly differ from MPR ( p = 0.17 and p = 0.37). Total deviation index for 0.9 was for P1 2.7 mm (axial), 3.7 mm (MPR), 1.8 mm (centerline); for P2 2.0 mm (axial), 3.6 mm (MPR), 1.8 mm (centerline); and for P3 3.0 mm (axial), 3.5 mm (MPR), 2.5 mm (centerline). Measurement time using centerline analysis was significantly shorter than for assessment by MPR. Conclusions Centerline analysis provides the least variable and fast diameter measurements in TEVAR patients with the same accuracy as the current reference standard MPR.
We studied whether in patients with stable COPD blood gases (BG), especially oxygenated hemoglobin (OxyHem) as a novel biomarker confer information on disease burden and prognosis and how this adds ...to the information provided by the comorbidity pattern and systemic inflammation. Data from 2137 patients (GOLD grades 1-4) of the baseline dataset of the COSYCONET COPD cohort were used. The associations with dyspnea, exacerbation history, BODE-Index (cut-off ≤2) and all-cause mortality over 3 years of follow-up were determined by logistic and Cox regression analyses, with sex, age, BMI and pack years as covariates. Predictive values were evaluated by ROC curves. Capillary blood gases included SaO
, PaO
, PaCO
, pH, BE and the concentration of OxyHem haemoglobin (Hb) x fractional SaO
, g/dL as a simple-to-measure correlate of oxygen content. Inflammatory markers were WBC, CRP, IL-6 and -8, TNF-alpha and fibrinogen, and comorbidities comprised a broad panel including cardiac and metabolic disorders. Among BG, OxyHem was associated with dyspnoea, exacerbation history, BODE-Index and mortality. Among inflammatory markers and comorbidities, only WBC and heart failure were consistently related to all outcomes. ROC analyses indicated that OxyHem provided information of a magnitude comparable to that of WBC, with optimal cut-off values of 12.5 g/dL and 8000/µL, respectively. Regarding mortality, OxyHem also carried independent, additional information, showing a hazard ratio of 2.77 (95% CI: 1.85-4.15, p < 0.0001) for values <12.5 g/dL. For comparison, the hazard ratio for WBC > 8000/µL was 2.33 (95% CI: 1.60-3.39, p < 0.0001). In stable COPD, the concentration of oxygenated hemoglobin provided additional information on disease state, especially mortality risk. OxyHem can be calculated from hemoglobin concentration and oxygen saturation without the need for the measurement of PaO
. It thus appears well suited for clinical use with minimal equipment, especially for GPs.
The European Society of Radiology (ESR) and European Respiratory Society (ERS) published their joint statement paper on lung cancer screening (LCS), on 12 February 2020. This document joins and ...completes previous recommendations on LCS with specific emphasis on the analysis of issues encountered in the practical implementation of LCS in the community. Major milestones to enable the most efficient and equal dissemination of LCS are recognised as engagement of all stakeholders (e.g. candidate/participant, general practitioners, up to the specialised LCS facility), quality assurance, and primary prevention in the form of provision of counselling for smoking cessation.
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