Mechanism of generation of the flexural vibrations in an ultrasonic waveguide

This article deals with the problem of transfer of ultrasonic vibrations on flexible hub-waveguide system and is a continuation of research in this field [1-3]. The main field of application of flexible hub-waveguides-minimally invasive surgery for treatment of vascular diseases, where they are used to restore patency of blood vessels by destroying blood clots and tromboèmbolov. Thanks to the possibility of elastic deformation of flexible hub-waveguides, they can be delivered through a catheter system to the most remote places of the blood vessels, producing ultrasonic processing of affected sites with minimal surgical intervention. It should be borne in mind that during the work of the PA system can change its own hub-frequency waveguides and frequency generator, and this can lead to beating frequencies, formation of flexural vibrations of a working part, etc. This article therefore tasked to define the conditions of formation of low-frequency oscillations of a bend when passing ultrasonic vibrations of flexible waveguide system

Artifacts in magnetic resonance imaging: how it can really affect diagnostic image quality and confuse clinical diagnosis?

Different kinds of artifacts can occur during a magnetic resonance imaging (MRI) scans due to hardware or software related problems, human physiologic phenomenon or physical restrictions. Some of them can seriously affecting diagnostic image quality, while others may simulate or be confused with different pathology. On another word artifact as an artificial feature appearing in an image that is not present in the original investigative object. It is important to recognize these artifacts according to a basic understanding of their origin, especially those mimicking pathology, as they can lead to incorrect diagnosis and cause serious after-effects on patient’s health and outcomes. We presented an overview of the most common MRI artifacts and methods to fix or rectify them. We also provide the original artifacts images and statistics from the Lithuanian University of Health Sciences Kaunas Clinical Hospital, Dept of Radiology, mainly obtained from image databases and some images from data base of other Lithuanian hospitals

IVUS-VH relation to the extent and composition of atherosclerotic plaque and clinical outcome prognosis

Background and aim: Most frequent and generally unpredictable coronary plaque rupture impacts the burden of coronary artery disease but features or signs related to plaque remodeling into the high risk structure are not clearly detectable by using ordinary visualization methods. Till yet there are no evident criteria for additional using IVUS. The aim of the study was to determinate intravascular ultrasound virtual histology (IVUS-VH) importance in identifying high risk plaques, which can contribute to increased rupture hazard. Methods: We selected 30 patients with stabile angina pectoris. 50 plaques were analyzed with coronary angiography digital assessment tool and IVUS similarly. Differences of stenoses measured by both methods, then were calculated and compared to composition of plaques evaluated by IVUS-VH. Results: Plaques were mostly formed of fibrous tissue (FI) (2.6 mm2; 57.89 %). Necrosis was found to make in average one-fifth of analyzed plaques (0.75 mm2, 19.60 %). Calcification made up the smallest part of plaques (0.3 mm2, 8.58 %). Plaques with higher necrosis component appeared to be significantly greater in IVUS compared to coronary angiography. In group A necrosis made up 1.40±1.05 mm2; group B – 0.87±0.52 mm2, and group C – 0.62 ±0.45 mm2 (p= 0.020). The same tendency was observed with FI: group A – 3.38±3.20 mm2; group B – 2.90±2.6 mm2 and group C – 2.04±165 mm2 (p= 0.082). Correlation analysis revealed negative moderate relationship between groups and necrosis percentage (r= –0.40, p= 0.004), and FI (r= –0.29, p= 0.039) components of the plaques. Conclusion: IVUS-VH provides new insight into the evaluation of different composition of plaques. However, despite the advantages, IVUS-VH remains costly and not always technically adaptive procedure, so it is necessary to pursue for new methods or technologies to identify atherosclerotic plaques at risk

Artifacts in computer tomography imaging: how it can really affect diagnostic image quality and confuse clinical diagnosis?

Different kinds of artifacts can occur during a computer tomography (CT) scans due to hardware or software related problems, human physiologic phenomenon or physical restrictions. Some of them can seriously affecting diagnostic image quality, while others may simulate or be confused with different pathology. On another words artifact is an artificial feature appearing in an image that is not present in the original investigative object. It is important to recognize these artifacts according to a basic understanding of their origin, especially those mimicking pathology, as they can lead to incorrect diagnosis and cause serious after-effects on patient’s health. We presented an overview of the most common CT artifacts and methods to fix or rectify them. We also provide the original artifacts images and statistics from the Lithuanian University of Health Sciences Kaunas Clinical Hospital obtained from image databases

Signal intensity dynamics of malignant lymphoma in diffusion-weighted magnetic resonance imaging compared to positron emission tomography

This article discusses a study performed with an aim to determine the usefulness of diffusion-weighted MRI in pre-treatment assessment and evaluation of chemotherapy response of mediastinal lesions of malignant lymphoma by analysing signal intensity, accumulation of contrast agent and changes in values of ADC. Comparing the results of PET/CT and DW-MRI was another goal of this study. We reviewed data of 21 patients that underwent treatment during years 2013-2014 at the Hospital of Lithuanian University of Health Sciences Kaunas Clinics and had DW-MRI and PET/CT scans carried out. For all patients the diagnosis of malignant lymphoma in mediastinal lymph nodes was confirmed histological. Whether the lymphoma was in active state was determined by PET/CT or histological data. In MRI scans, signal intensity and ADC values were evaluated, while in PET/CT maximum and average standardized uptake values were assessed. Patients underwent chemotherapy and follow up scans were performed to evaluate response. In total, 25 PET/CT and 50 DW-MRI scans were analysed. We found statistically significant difference of values of ADC in active and inactive states of malignant lymphoma of mediastinal lymph nodes. In follow up tests, performed during 2 years after treatment, a tendency of decreasing ADC values over time was seen when chemotherapy was successful and no relapse was observed. Among the reviewed cases, DW-MRI had slightly worse specificity than PET/CT in differentiation of malignant and benign changes in lymph nodes

Evaluation of complexity of induced necrosis zone shape by means of principal component analysis

Radiofrequency ablation (RFA) is medical procedure that causes coagulation necrosis in the ablative tissue. Experts using descriptive and morphometric methods usually assess the shape of necrosis zone. However, a precise and objective assessment of necrosis zone shape requires quantitative evaluation methodology that includes computerized mathematical algorithms. One of such methods is presented in the program package “SHAPE ver.1.3”, in which quantitative evaluation of various biological contour shapes is based on principal component analysis of elliptic Fourier descriptors (EFDs). Aim of present study was elaboration of quantitative measure for complexity of the necrosis zone shape after radiofrequency ablation. We performed assessment of suitability of computer program package “SHAPE ver. 1.3” to produce valuable estimates of necrosis zone shape. Minimal yet sufficient number of principal components for optimal representation of necrosis area shape could be a quantitative measure of the shape complexity. Program package “SHAPE ver.1.3” together with proposed procedure for determination of this measure could be used for optimization of radiofrequency ablation procedures

Thermography based inflammation monitoring of udder state in dairy cows: sensitivity and diagnostic priorities comparing with routine California mastitis test

Objectives of this study is to evaluate possibilities for early detection of udder’s diseases of Lithuanian Black and White cows and compare thermography and routine California mastitis test (CMT) results. Cows were examined in the negative and at positive ambient temperature. Infrared thermography (IRT) applied skin surface thermograms of teats in the area of Furstenberg’s rosette analyzed as posing evidence based signs of subclinical mastitis coincide with the CMT. It is shown, that subclinical inflammatory processes of cow’s mammary gland can be simply and successfully identified at an early stage of pathology development applying the thermal imaging method. IRT results measuring the skin surface temperature of teat sphincters of healthy dairy cows and cows with subclinical mastitis were completely similar to the CMT findings. Effectiveness of IRT does not depend from ambient conditions: inflammation can be easily detected both in positive and negative ambient temperatures. We confirm IRT being as alternative, noninvasive, high sensitive, rapid and portable method for subclinical various origins inflammatory processes of cow’s udder, which can be certified for practical subclinical mastitis screening and subsequent detection

New mathematical model for examination of cervical cancer by using diffusion–weighted magnetic resonance imaging

We compare the mean value of apparent diffusion coefficient (ADC) in a healthy cervix, cancer affected cervix and the cervix after chemoradiation therapy and evaluate the correlation of the value of ADC with the various clinical and histological findings. Prospective clinical study accomplished in Lithuanian University of Health Sciences University Clinical Hospital. Magnetic resonance imaging (MRI) examinations performed on 117 women with and 49 women without cervical cancer by using a 1.5 Tesla scanner. Diffusion–weighted (DW) imaging was performing by using b values of 50, 400 and 800 s/mm2. ADC measured in a healthy cervix, cancer affected cervix and the cervix 6 months after chemoradiation therapy. The mean ADC of the patients of the study group – 0.658±0.120×10-3 mm2/s was considerably lower than the mean of the control group – 1.169±0.134×10-3 mm2/s (t= 24.123, p= 0.02). There was no correlation between mean ADC and the stage of the disease, the histological type or grade of the tumor. A weak negative correlation was detected between ADC and the age of the subjects (r= –0,337, p= 0,000). The mean ADC of responders increased to 1.111±0.138×10-3 mm2/s, the mean ADC of non-responders remained lower – 0.733±0.073×10-3 mm2/s (t= 9.158, p= 0.04). The ADC value in the case of cervical cancer is significantly lower than in the non-affected cervical tissue. It increases after effective chemoradiation therapy and becomes closer to the coefficient value of non-affected cervical tissue but remains lower. We cannot credibly consider about the stage of the disease, the histological type and grade of the tumor, according to the ADC value of cervical cancer. Slight decreasing of ADC value closely relate with elderly of patients

Artifacts in magnetic resonance imaging: how it can really affect diagnostic image quality and confuse clinical diagnosis?

Different kinds of artifacts can occur during a magnetic resonance imaging (MRI) scans due to hardware or software related problems, human physiologic phenomenon or physical restrictions. Some of them can seriously affecting diagnostic image quality, while others may simulate or be confused with different pathology. On another word artifact as an artificial feature appearing in an image that is not present in the original investigative object. It is important to recognize these artifacts according to a basic understanding of their origin, especially those mimicking pathology, as they can lead to incorrect diagnosis and cause serious after-effects on patient’s health and outcomes. We presented an overview of the most common MRI artifacts and methods to fix or rectify them. We also provide the original artifacts images and statistics from the Lithuanian University of Health Sciences Kaunas Clinical Hospital, Dept of Radiology, mainly obtained from image databases and some images from data base of other Lithuanian hospitals

Artifacts in computer tomography imaging: how it can really affect diagnostic image quality and confuse clinical diagnosis?

Different kinds of artifacts can occur during a computer tomography (CT) scans due to hardware or software related problems, human physiologic phenomenon or physical restrictions. Some of them can seriously affecting diagnostic image quality, while others may simulate or be confused with different pathology. On another words artifact is an artificial feature appearing in an image that is not present in the original investigative object. It is important to recognize these artifacts according to a basic understanding of their origin, especially those mimicking pathology, as they can lead to incorrect diagnosis and cause serious after-effects on patient’s health. We presented an overview of the most common CT artifacts and methods to fix or rectify them. We also provide the original artifacts images and statistics from the Lithuanian University of Health Sciences Kaunas Clinical Hospital obtained from image databases