To propose and evaluate a novel nonrigid image registration approach for improved myocardial T1 mapping.
Myocardial motion is estimated as global affine motion refined by a novel local nonrigid motion estimation algorithm. A variational framework is proposed, which simultaneously estimates motion field and intensity variations, and uses an additional regularization term to constrain the deformation field using automatic feature tracking. The method was evaluated in 29 patients by measuring the DICE similarity coefficient and the myocardial boundary error in short axis and four chamber data. Each image series was visually assessed as "no motion" or "with motion." Overall T1 map quality and motion artifacts were assessed in the 85 T1 maps acquired in short axis view using a 4-point scale (1-nondiagnostic/severe motion artifact, 4-excellent/no motion artifact).
Increased DICE similarity coefficient (0.78 ± 0.14 to 0.87 ± 0.03, P
Measures assessing resting-state brain activity with blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) can reveal cognitive disorders at an early stage. Analysis of regional homogeneity (ReHo) measures the local synchronization of spontaneous fMRI signals and has been successfully utilized in detecting alterations in subjects with attention-deficit hyperactivity disorder (ADHD), depression, schizophrenia, Parkinson's disease and Alzheimer's dementia. Resting-state brain activity was investigated in 28 adolescents with autism spectrum disorders (ASD) and 27 typically developing controls being imaged with BOLD fMRI and analyzed with the ReHo method. The hypothesis was that ReHo of resting-state brain activity would be different between ASD subjects and controls in brain areas previously shown to display functional alterations in stimulus or task based fMRI studies. Compared with the controls, the subjects with ASD had significantly decreased ReHo in right superior temporal sulcus region, right inferior and middle frontal gyri, bilateral cerebellar crus I, right insula and right postcentral gyrus. Significantly increased ReHo was discovered in right thalamus, left inferior frontal and anterior subcallosal gyrus and bilateral cerebellar lobule VIII. We conclude that subjects with ASD have right dominant ReHo alterations of resting-state brain activity, i.e., areas known to exhibit abnormal stimulus or task related functionality. Our results demonstrate that there is potential in utilizing the ReHo method in fMRI analyses of ASD.
The omnibus Tei index, the sum of isovolumic contraction and relaxation times divided by the ejection time, is a good indicator of global cardiac function. However, these time intervals can be influenced by valvular heart disease and the role of the Tei index among patients with aortic stenosis (AS) and left ventricular systolic dysfunction remains incompletely defined.
Doppler time intervals were measured retrospectively by two observers, and the Tei index were calculated on 80 patients with various degrees of left ventricular systolic dysfunction and severity of AS. Differences between observers were resolved by consensus. Ejection fraction (EF) was visually estimated, and the aortic valve area (AVA) was calculated using the continuity equation.
The mean AVA was 1.1+/-0.5 cm(2) and the mean EF was 0.39+/-0.15. Although correlation (r = 0.61, P
This paper presents an automated procedure developed to extract quantitative information from video recordings of neonatal seizures in the form of motor activity signals. This procedure relies on optical flow computation to select anatomical sites located on the infants' body parts. Motor activity signals are extracted by tracking selected anatomical sites during the seizure using adaptive block matching. A block of pixels is tracked throughout a sequence of frames by searching for the most similar block of pixels in subsequent frames; this search is facilitated by employing various update strategies to account for the changing appearance of the block. The proposed procedure is used to extract temporal motor activity signals from video recordings of neonatal seizures and other events not associated with seizures.
The Sectra MicroDose Mammography system is based on direct photon counting (with a solid-state detector), and a substantially lower dose to the breast than when using conventional systems can be expected. In this work absorbed dose measurements have been performed for the first unit used in routine mammography screening (at the Hospital of Helsingborg, Sweden). Two European protocols on dosimetry in mammography have been followed. Measurement of half value layer (HVL) cannot be performed as prescribed, but this study has demonstrated that non-invasive measurements of HVL can be performed accurately with a sensitive and well collimated solid-state detector with simultaneous correction for the energy dependence. The average glandular dose for a 50 mm standard breast with 50% glandularity, simulated by 45 mm polymethylmethacrylate, was found to be 0.21 and 0.28 mGy in March and December 2004, respectively. These values are much lower than for any other mammography system on the market today. It has to be stressed that the measurements were made using the current clinical settings and that no systematic optimisation of the relationship between absorbed dose and diagnostic image quality has been performed within the present study. In order to further increase the accuracy of absorbed dose measurements for this unit, the existing dose protocols should be revised to account also for the tungsten/aluminium anode/filter combination, the multi-slit pre-collimator device and the occurrence of a dose profile in the scanning direction.
OBJECTIVES: To investigate the influence of drug-eluting stent (DES) implantation on clinical and angiographic restenosis. DESIGN: Registry study of data from the Swedish Coronary Angiography and Angioplasty Registry with a coronary angiographic substudy. SETTING: Multi-centre study. SUBJECTS: During October 2002 to May 2004 a total of 23 590 percutaneous coronary intervention (PCI) procedures were performed at 25 hospitals. After selection, to achieve comparable groups, a total of 5068 patients of whom 4111 had a bare metal stent (BMS) implanted and 957 had a DES implanted, remained. End-point in the registry follow-up was >50% diameter restenosis at clinically driven reangiography within 12 months after index PCI. The primary end-point in the angiographic substudy was late loss in patients' DES at 6-month angiographic follow-up. RESULTS: The rate of clinically driven restenosis, within 12 months, in patients receiving DES was less (3.9%) compared with those who received BMS (7.0%). In multivariate analysis the risk of clinical restenosis was one-third for DES compared with BMS (HR 0.36, 95% CI 0.25-0.52). In the angiographic substudy late loss was 0.07+/-0.53 mm (range -0.88 to 1.62). The amount of late loss was related to the presence of diabetes mellitus or not (0.19+/-0.45 mm vs. -0.12+/-0.58 mm), and lack of postdilatation of the stent or not (0.23+/-0.51 mm vs. -0.09+/-0.50 mm). CONCLUSIONS: The use of DES in the Swedish 'real world' is effective in reducing the clinically driven restenosis rate, when compared with patients with BMS treatment. In the angiographic follow-up the average late loss was as low as observed in recent randomized multi-centre trials.
We hypothesised that myocardial deformation determined with magnetic resonance imaging (MRI) will detect myocardial scar.
Displacement Encoding with Stimulated Echoes (DENSE) was used to calculate left ventricular strain in 125 patients (29 women and 96 men) with suspected coronary artery disease. The patients also underwent cine imaging and late gadolinium enhancement. 57 patients had a scar area >1% in at least one segment, 23 were considered free from coronary artery disease (control group) and 45 had pathological findings but no scar (mixed group). Peak strain was calculated in eight combinations: radial and circumferential strain in transmural, subendocardial and epicardial layers derived from short axis acquisition, and transmural longitudinal and radial strain derived from long axis acquisitions. In addition, the difference between strain in affected segments and reference segments, "differential strain", from the control group was analysed.
In receiver-operator-characteristic analysis for the detection of 50% transmurality, circumferential strain performed best with area-under-curve (AUC) of 0.94. Using a cut-off value of -17%, sensitivity was 95% at a specificity of 80%. AUC did not further improve with differential strain. There were significant differences between the control group and global strain circumferential direction (-17% versus -12%) and in the longitudinal direction (-13% versus -10%). Interobserver and scan-rescan reproducibility was high with an intraclass correlation coefficient (ICC) >0.93.
DENSE-derived circumferential strain may be used for the detection of myocardial segments with >50 % scar area. The repeatability of strain is satisfactory. DENSE-derived global strain agrees with other global measures of left ventricular ejection fraction.
The study aim was to compare European Organization for Research and Treatment of Cancer (EORTC) criteria with PET Response Criteria in Solid Tumors (PERCIST) for response evaluation of patients with metastatic colorectal cancer treated with a combination of the chemotherapeutic drug irinotecan and the monoclonal antibody cetuximab.
From 2006 to 2009, patients with metastatic colorectal cancer were prospectively included in a phase II trial evaluating the combination of irinotecan and cetuximab every second week, as third-line treatment. (18)F-FDG PET/CT was performed between 1 and 14 d before the first treatment and after every fourth treatment cycle until progression was identified by CT with Response Evaluation Criteria in Solid Tumors (RECIST). Response evaluation with (18)F-FDG PET/CT was retrospectively performed according to both EORTC criteria and PERCIST, classifying the patients into 4 response categories: complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD), and progressive metabolic disease (PMD). Individual best overall metabolic response (BOmR) was registered with both sets of criteria, as well as survival within response categories, and compared.
A total of 61 patients and 203 PET/CT scans were eligible for response evaluation. With EORTC criteria, 38 had PMR, 16 had SMD, and 7 had PMD as their BOmR. With PERCIST, 34 had PMR, 20 had SMD, and 7 had PMD as their BOmR. None of the patients had CMR. There was agreement between EORTC criteria and PERCIST in 87% of the patients, and the corresponding ?-coefficient was 0.76. Disagreements were confined to PMR and SMD. Median overall survival (OS) in months with EORTC criteria was 14.2 in the PMR group and 7.2 in the combined SMD + PMD group. With PERCIST, it was 14.5 in the PMR group and 7.9 in the SMD + PMD group.
Response evaluation with EORTC criteria and PERCIST gave similar responses and OS outcomes with good agreement on BOmR (?-coefficient, 0.76) and similar significant differences in median OS between response groups. Compared with EORTC criteria, we find PERCIST unambiguous because of clear definitions and therefore more straightforward to use.