Hynek Mirka

Pulmonary imaging using dual-energy CT, a role of the assessment of iodine and air distribution.

AIM The aim of the study is to present the feasibility of using dual-energy CT and the evaluation of iodine and air distribution in differentiation of pathological conditions. MATERIAL AND METHOD We used the data of 50 CT examinations performed due to suspected pulmonary embolism with any pathological finding except consolidation of the parenchyma. The patients underwent CT angiography of the pulmonary arteries on a dual-source CT (DSCT), with the two tubes independently operated at 140 and 80 kV. By exploiting the dual-energy information, iodine distribution maps were obtained in addition to the conventional CT images which served as a marker of pulmonary perfusion. Minimum intensity projections (MinIP) were used as a marker of air content. RESULTS By comparing the iodine distribution maps and MinIP images, it was possible to differentiate between the following templates of lung parenchyma: A--normal iodine and air distribution; B--iodine content deficit with minimal or with no redistribution of air; C--reduced iodine content and increased content of air; D--deficit of iodine content and increased content of air; E--increased iodine content and normal content of air; F--increased iodine content and reduced content of air; G--reduced perfusion and reduced content of air. The type A (five cases) was typical for the pulmonary embolism with preserved normal conditions of perfusion and ventilation. Type B (18 cases) occurred in pulmonary embolism; type C was found in case of inflammation of small respiratory airways (five cases); emphysema was typical for type D (nine cases); increased perfusion was observed in the parenchyma preserved from emphysema or preserved from embolism in cases of emphysema or pulmonary embolism; type F occurred in pulmonary interstitial edema (four cases) both with pulmonary infection; finally type G was found in interstitial lung diseases (five cases). CONCLUSION Imaging of the pulmonary circulation by means of dual-energy CT opens the potential to study pathological changes of circulatory and pulmonary perfusion impairments, our presented work signs the important relations between iodine and air distribution which have to be thought in the interpretation of dual-energy perfusion imaging of the lungs.

Multidetector computed tomography of chest trauma: indications, technique and interpretation

BackgroundChest traumas are a significant cause of mortality and morbidity, especially in the younger population.MethodsDiagnostic imaging plays a key role in their management. Multidetector computed tomography (MDCT) is the most important imaging method in this field. Its advantages include especially high speed and high geometric resolution in any plane.ResultsThe method allows us to view large parts of the body with minimal motion artifacts and to create accurate multiplanar and three-dimensional (3D) reformations, which make the diagnosis significantly more accurate. Because of its advantages MDCT has become the first-choice method in high-energy traumas.ConclusionThis article summarises the position of MDCT in the diagnostic algorithm of chest injuries, technical aspects of the examination and imaging findings in traumas of the individual chest compartments.Teaching Points• Diagnostic imaging plays a key role in the management of high-energy chest trauma.• MDCT is the most important imaging method in this kind of injury, as detailed information can be acquired in a short acquisition time.• Multiplanar and three-dimensional (3D) reformattings make the diagnosis significantly more accurate.

Porcine liver vascular bed in Biodur E20 corrosion casts

BACKGROUND Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting. MATERIALS AND METHODS Mercox II® (Ladd Research, Williston, Vermont, USA) and Biodur E20® Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy. RESULTS For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20® epoxy resin. CONCLUSIONS Only Biodur E20®Plus appeared to be suitable for high-volume vascular corrosion casting due to its optimal permeability, sufficient processing time and minimum fragility. Biodur E20® Plus is slightly elastic, radio-opaque and alcohol-resistant. These properties make this acrylic resin suitable for not only vascular research but also teaching purposes.

Correlating Micro-CT Imaging with Quantitative Histology

Advanced biomechanical models of biological tissues should be based on statistical morphometry of tissue architecture. A quantitative description of the microscopic properties of real tissue samples is an advantage when devising computer models that are statistically similar to biological tissues in physiological or pathological conditions. The recent development of X-ray microtomography (micro-CT) has introduced resolution similar to that of routine histology. The aim of this chapter is to review and discuss both automatic image processing and interactive, unbiased stereological tools available for micro-CT scans and histological micrographs. We will demonstrate the practical usability of micro-CT in two different types of three-dimensional (3-D) ex vivo samples: (i) bone scaffolds used in tissue engineering and (ii) microvascular corrosion casts.

The use of porcine corrosion casts for teaching human anatomy

In teaching and learning human anatomy, anatomical autopsy and prosected specimens have always been indispensable. However, alternative methods must often be used to demonstrate particularly delicate structures. Corrosion casting of porcine organs with Biodur E20® Plus is valuable for teaching and learning both gross anatomy and, uniquely, the micromorphology of cardiovascular, respiratory, digestive, and urogenital systems. Assessments of casts with a stereomicroscope and/or scanning electron microscope as well as highlighting cast structures using color coding help students to better understand how the structures that they have observed as two-dimensional images actually exist in three dimensions, and students found using the casts to be highly effective in their learning. Reconstructions of cast hollow structures from (micro-)computed tomography scans and videos facilitate detailed analyses of branching patterns and spatial arrangements in cast structures, aid in the understanding of clinically relevant structures and provide innovative visual aids. The casting protocol and teaching manual we offer can be adjusted to different technical capabilities and might also be found useful for veterinary or other biological science classes.

Cystic Appearance on Imaging Methods (Bosniak III-IV) in Histologically Confirmed Papillary Renal Cell Carcinoma is Mainly Characteristic of Papillary Renal Cell Carcinoma Type 1 and Might Predict a Relatively Indolent Behavior of Papillary Renal Cell Carcinoma

Aim: The aim of this study was to determine the proportion of cystic tumors according to preoperative CT (Bosniak III, IV) among surgically treated patients with histologically confirmed papillary renal cell carcinoma (pRCC) and to assess progression rates among patients with and without cystic appearance on imaging. Methods: A total of 138 patients with pRCC histology surgically treated in the period of January 2007–March 2017 were included. Clinical and radiological characteristics, type of surgery, histopathology results, and follow-up data were recorded and statistically evaluated. Results: Forty-one cases (29.7%) of cystic lesions (10× BIIF, 14× BIII, 17× BIV) were detected by CT. Patients with pRCC1 significantly more frequently presented with cystic appearance on CT (33/78; 42.3%) in comparison to other papillary types (8/60; 13.3%; p = 0.0002). During a median follow-up time of 49.4 months, only 2 patients with cystic lesions progressed after surgery. Conclusions: Cystic appearance on imaging methods is mainly a characteristic of pRCC1 (42.3%). Cystic morphology on imaging might predict a relatively indolent behavior of all pRCC types. Preoperative scoring systems including tumor growth patterns (cystic vs. solid) are needed for further classification.

Monitoring after radiofrequency ablation of liver tumors: contrast-enhanced ultrasound (CEUS) vs. contrast-enhanced computer tomography (CECT), two days after procedure

AIM Our research evaluated the ability of contrast-enhanced ultrasound (CEUS) and contrast enhanced computer tomography (CECT), performed 48 h after radiofrequency ablation (RFA), to detect residual tumor tissue. As recently published studies have evaluated periprocedural CEUS performed within 24 h after procedure and their results were not satisfactory, it seems that postponing the control test by one day could increase the sensitivity of both methods. PATIENTS AND METHODS We evaluated 33 patients with 37 lesions, who met the criteria for our study. The criteria were 1) the treated lesion is sonographically viewable and 2) the patient underwent both CEUS and CECT control 48 h after treatment and additional follow-up 3 months later by CECT. Presence of residual tumor tissue and the size of necrosis were recorded and compared to the results of 3-months CECT. RESULTS Nine residues were present in our group. CEUS and CECT showed similar sensitivity (66.7% and 77.8%, respectively) and identical specificity (both 96.4%) for detection of residual tumor tissue. CEUS significantly underestimated the size of necrosis in comparison to CECT (on average by 2.4 mm, P=0.0005). Over the 3-months follow-up period the size of necrosis decreased in all patients (on average by 7.2 mm, P<0.0001). CONCLUSION The quality of tumor residue detection in 48-h CEUS was comparable to that of 48-h CECT. This finding suggests the CEUS being a feasible substitute for CECT. Both methods show reasonable sensitivity; therefore this timing seems to be appropriate for the first post-treatment control while also allowing for early retreatment if residual tumor tissue is found.

Contribution of Computed Tomographic Angiography to Pretreatment Planning of Radio-embolization of Liver Tumors

Transarterial radio-embolization (TARE) using yttrium-90 microspheres is a promising method based on the brachytherapeutic effect of radionuclide with beta-minus decay dissolved in solid microparticles applied directly to tumor-supplying arteries. This treatment is complex, as well as logistically and technically extremely demanding and must be planned in detail. The visualization of the vascular supply of the liver and the possible parasitic supply of the tumor is essential not only for indication of the procedure and correct identification of the arteries to which the microspheres will be applied, but also for prevention of non-target deposition of radioactive material. This review addresses the use of computed tomographic angiography in the preparatory phase of TARE.

Tumor-related Perfusion Changes in White Matter Adjacent to Brain Tumors: Pharmacodynamic Analysis of Dynamic 3T Magnetic Resonance Imaging

Background/Aim: To verify perfusion differences in white matter adjacent to glioblastomas and metastatic tumors in dynamic contrast-enhanced (DCE) 3T-magnetic resonance imaging (MRI) using gradient echo (GRE) T1 techniques. Materials and Methods: A retrospective comparative study was carried out on adults with glioblastoma (n=67) and brain metastases (n=31). In each patient, conventional 3T-MRI and DCE-MRI with 25 acquisitions of GRE-T1 were performed. The initial area under the contrast-uptake curve (iAUC) and transfer constant (Ktrans) in peritumoral regions of the white matter were evaluated using T1 pharmacodynamic modeling software. Results: Statistically significantly higher relative iAUC (p<0.001) and Ktrans (p<0.01) values were recorded for peritumoral white matter near glioblastomas compared to that near metastases: 2.29 (SD=1.11) and 2.12 (SD=1.05) vs. 0.96 (SD=0.31) and 1.18 (SD=0.35), respectively. Conclusion: In comparison to Ktrans, the iAUC obtained by DCE-MRI is more suitable for assessing glioblastomas because it better reflects pharmacokinetic peritumoral changes. Increased iAUC in white matter near to tumor generally indicates glioblastoma, however, a low level does not exclude it.

Assessment of myocardial enhancement during coronary CT angiography in critically ill patients

There are still challenges and unmet needs for the imaging techniques, such as conditions of uncertain origin in patients with clinically serious, life-threatening conditions with unknown cause that are not associated with dominant chest pain, ECG changes or other symptoms indicating a possible primarily cardiac or coronary cause. The contribution of the myocardial enhancement evaluation of urgent cardiac CTA scans significantly improves to determining the diagnosis of acute myocardial injury and choosing appropriate treatment. When incorporating the myocardial enhancement assessment into the imaging algorithm of an emergency department, emphasis is placed on a uniform imaging procedure and a uniform evaluation approach. The color coded images of the myocardial enhancement in emergency situations helps identify the most serious pathologies and shorten the time to adequate targeted therapy in patients.