Search results for "Computer-Assisted"
showing 10 items of 1186 documents
Realignment of myocardial first-pass MR perfusion images using an automatic detection of the heart-lung interface
2004
International audience; Abstract: Magnetic resonance first-pass imaging of a bolus of contrast agent is well adapted to distinguish normal and hypoperfused areas of the myocardium. In most cases, the signal intensity-time curves in user defined regions of interest (ROI) are studied. As image acquisition is ECG-gated, the images are acquired at the same moment in the cardiac cycle, and the basic shape of the heart is similar from one view to the next. However, superficial respiratory motion can displace the heart in the short-axis plane. The aim of this study is to correct for the respiratory motion of the heart by performing an automatic realignment of the myocardial ROI based on a method t…
Value of texture analysis on gadoxetic acid–enhanced MRI for differentiating hepatocellular adenoma from focal nodular hyperplasia
2019
OBJECTIVE. The objective of our study was to assess the diagnostic performance of texture analysis (TA) on gadoxetic acid-enhanced MR images for differentiation of hepatocellular adenoma (HCA) from focal nodular hyperplasia (FNH).MATERIALS AND METHODS. This study included 40 patients (39 women and one man) with 51 HCAs and 28 patients (27 women and one man) with 32 FNH lesions. All lesions were histologically proven with preoperative MRI performed with gadoxetic acid. Two readers reviewed all the imaging sequences to assess the qualitative MRI characteristics. The T2-weighted fast spin-echo, hepatic arterial phase (HAP), and hepatobiliary phase (HBP) sequences were used for TA. Textural fea…
Gadoxetic acid-enhanced MRI of transient hepatic enhancement differences: Another cause of hypointense observation on hepatobiliary phase
2018
Purpose: To retrospectively determine the frequency, natural history and factors associated with the presence of transient hepatic enhancement difference showing hypointensity on hepatobiliary phase images of gadoxetic acid-enhanced MRI. Materials and methods: Gadoxetic acid-enhanced MRI of 125 patients (91 men; 34 women) with transient hepatic enhancement difference were retrospectively reviewed. Three readers qualitatively and quantitatively evaluated MR imaging features and evolution at follow up. The Chi-square test, Fisher's exact test and Kruskall-Wallis rank test were used for statistical analysis. Results: Transient hepatic enhancement difference were hypointense on hepatobiliary ph…
Assessment of tumor microcirculation with dynamic contrast-enhanced MRI in patients with esophageal cancer: initial experience.
2008
PURPOSE: To investigate the feasibility and impact of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) on tumor characterization and response to radiochemotherapy (RCT) in patients with esophageal cancer. MATERIALS AND METHODS: A total of 48 patients underwent DCE-MRI to assess tumor microcirculation based on a two-compartment model function. Effects of RCT on kinetic parameters were studied in 12 patients with squamous cell carcinoma. RESULTS: Tumor microcirculation differs with respect to histological subtype: squamous cell carcinomas showed lower values of amplitude A (leakage space, P = 0.015) and higher contrast agent exchange rates (k(21), P = 0.225) compared with adenoc…
Chronic Thromboembolic Pulmonary Hypertension: Pre- and Postoperative Assessment with Breath-hold MR Imaging Techniques
2004
To evaluate the potential of breath-hold magnetic resonance (MR) imaging techniques in morphologic and functional assessment of patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and after surgery.Thirty-four patients with CTEPH were examined before and after pulmonary thromboendarterectomy (PTE). For morphologic assessment, contrast material-enhanced MR angiography was used; for assessment of hemodynamics, velocity-encoded gradient-echo sequences and cine gradient-echo sequences along the short axis of the heart were performed. Contrast-enhanced MR angiography was compared with selective digital subtraction angiography (DSA) for depiction of central thromboembolic m…
Solitary necrotic nodules of the liver: cross-sectional imaging findings and follow-up in nine patients.
2008
OBJECTIVE. The purpose of our study was to retrospectively evaluate the sonographic, CT, and MRI findings (number, diameter, lobar location, depth from the hepatic capsule, and appearance of lesions) in a series of nine patients with pathologically proven solitary necrotic nodules of the liver and the natural evolution at follow-up in four of the nine patients.CONCLUSION. Solitary necrotic nodules are usually small, solitary lesions, mainly located under the liver capsule of the right lobe. They are hypoechoic on sonography, hypoattenuating on CT, have low signal intensity on both T1- and T2-weighted MRI with lack of enhancement after IV contrast administration, and at follow-up have a tend…
Kardiale MRT : Änderungen der normalisierten myokardialen Gadolinium-Anreicherung über die Zeit nach Kontrastmittelinjektion in Patienten mit akuter …
2011
PURPOSE An increased normalized gadolinium accumulation (NGA) in the myocardium during early washout has been used for the diagnosis of acute myocarditis (AM). Due to the fact that the pharmacokinetics of contrast agents are complex, time-related changes in NGA after contrast injection are likely. Because knowledge about time-related changes of NGA may improve the diagnostic accuracy of MR, our study aimed to estimate the time course of NGA after contrast injection in patients as well as in healthy volunteers. MATERIALS AND METHODS An ECG-triggered inversion recovery SSFP sequence with incrementally increasing inversion times was repetitively acquired over the 15 minutes after injection of …
Dynamic contrast-enhanced myocardial perfusion imaging using saturation-prepared TrueFISP.
2002
Purpose To develop and test a saturation-recovery TrueFISP (SR-TrueFISP) pulse sequence for first-pass myocardial perfusion imaging. Materials and Methods First-pass magnetic resonance imaging (MRI) of Gd-DTPA (2 mL) kinetics in the heart was performed using an SR-TrueFISP pulse sequence (TR/TE/α = 2.6 msec/1.4 msec/55°) with saturation preparation TD = 30 msec before the TrueFISP readout. Measurements were also performed with a conventional saturation-recovery TurboFLASH (SRTF) pulse sequence for comparison. Results SR-TrueFISP images were of excellent quality and demonstrated contrast agent wash-in more clearly than SRTF images. The signal increase in myocardium was higher in SR-TrueFISP …
Intra- and Interhemispheric Electroencephalogram Coherence in Siblings Discordant for Schizophrenia and Healthy Volunteers
1997
Former studies had pointed to an increased electroencephalogram (EEG) coherence in schizophrenics, but it remained unsolved whether this deviation represents the premorbid state or is only a consequence of the current or previous schizophrenic episodes. To clarify this question, we tested the hypothesis that subjects at elevated risk also reveal higher coherences compared to healthy controls. For that, intra- and interhemispheric EEG coherences were investigated in untreated schizophrenics, their healthy siblings, and healthy controls. Differences were only found regarding the intrahemispheric coherences. Both in schizophrenics and, even though to a lesser degree, in their siblings signific…
Congenital Müllerian anomalies: diagnostic accuracy of three-dimensional ultrasound
1996
Objective To determine whether it is possible to identify and diagnose accurately Mullerian anomalies with three-dimensional (3-D) ultrasound (US). Design Controlled blinded clinical study. Setting Normal human volunteers undergoing infertility evaluation in a university hospital. Patients Forty-two patients who underwent laparoscopy and hysterosalpingography as part of their work up for infertility and were found to have either a normal uterus (30 patients) or a Mullerian abnormality (12 patients) consented to be evaluated with 3-D US by sonographers who were unaware of their infertility history or of their laparoscopy and hysterosalpingography diagnoses. Interventions Transvaginal 3-D US …