Image, Netherlands
Image, Netherlands

Time filter

Source Type

Conijn M.M.A.,University Utrecht | Conijn M.M.A.,Julius Center for Health science and Primary Care | Kloppenborg R.P.,Julius Center for Health science and Primary Care | Algra A.,Julius Center for Health science and Primary Care | And 6 more authors.
Stroke | Year: 2011

BACKGROUND AND PURPOSE-: Cerebral small vessel disease may be related to vascular and nonvascular pathology. We assessed whether lacunar infarcts and white matter lesions on MRI increased the risk of vascular and nonvascular death and future vascular events in patients with atherosclerotic disease. METHODS-: Brain MRI was performed in 1309 patients with atherosclerotic disease from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study. Infarcts were scored visually and volumetric assessment of white matter lesion was performed. Patients were followed for a median of 4.5 years (range, 0.2 to 7.1 years) for death, ischemic stroke, and ischemic cardiac complications. RESULTS-: Cox regression models showed that presence of lacunar infarcts (n=229) increased the risk of vascular (hazard ratio, 2.6; 95% CI, 1.4 to 4.9) and nonvascular death (hazard ratio, 2.7; 95% CI, 1.3 to 5.3), adjusted for age, sex, vascular risk factors, nonlacunar infarcts, and white matter lesion. These risks were similar for patients with silent lacunar infarcts. White matter lesion volume (relative to total intracranial volume) increased the risk of vascular death (hazard ratio per milliliter increase, 1.03; 95% CI, 1.01 to 1.05) and white matter lesions in the upper quintile compared with lower quintiles increased risk of ischemic stroke (hazard ratio, 2.6; 95% CI, 1.3 to 4.9). CONCLUSIONS-: Cerebral small vessel disease, with or without a history of cerebrovascular disease, is associated with increased risk of death and ischemic stroke in patients with atherosclerotic disease. © 2011 American Heart Association, Inc.

Tiebosch I.A.C.W.,Image science Institute | Van Den Bergh W.M.,University Utrecht | Van Den Bergh W.M.,University of Groningen | Bouts M.J.R.J.,Image science Institute | And 3 more authors.
Cerebrovascular Diseases | Year: 2013

Background: The pathogenesis of delayed cerebral injury after aneurysmal subarachnoid hemorrhage (SAH) is largely unresolved. In particular, the progression and interplay of tissue and perfusion changes, which can significantly affect the outcome, remain unclear. Only a few studies have assessed pathophysiological developments between subacute and chronic time points after SAH, which may be ideally studied with noninvasive methods in standardized animal models. Therefore, our objective was to characterize the pattern and correlation of brain perfusion and lesion status with serial multiparametric magnetic resonance imaging (MRI) from subacute to chronical after experimental SAH in rats. Methods: SAH was induced by endovascular puncture of the intracranial bifurcation of the right internal carotid artery in adult male Wistar rats (n = 30). Diffusion-, T2-, perfusion- and contrast-enhanced T1-weighted MRI were performed on a 4.7-tesla animal MR system to measure cytotoxic and vasogenic edema, hemodynamic parameters and blood-brain barrier permeability, respectively, at days 2 and 7 after SAH. The neurological status was repeatedly monitored with different behavioral tests between days -1 and 7 after SAH. Lesioned tissue - identified by edema-associated T2 prolongation - and unaffected tissue were outlined on multislice images and further characterized based on tissue and perfusion indices. Correlation analyses were performed to evaluate relationships between different MRI-based parameters and between MRI-based parameters and neurological scores. Results: Similar to clinical SAH and previous studies in this experimental SAH model, mortality up to day 2 was high (43%). In surviving animals, neurological function was significantly impaired subacutely, and tissue damage (characterized by T2 prolongation and diffusion reduction) and blood-brain barrier leakage (characterized by contrast agent extravasation) were apparent in ipsilateral cortical and subcortical tissue as well as in contralateral cortical tissue. Notably, ipsilateral cortical areas revealed increased cerebral blood flow and volume. Animals that subsequently died between days 2 and 7 after SAH had markedly elevated ipsilateral perfusion levels at day 2. After a week, neurological function had improved in surviving animals, and brain edema was partially resolved, while blood-brain barrier permeability and hyperperfusion persisted. The degree of brain damage correlated significantly with the level of perfusion elevation (r = 0.78 and 0.85 at days 2 and 7, respectively; p < 0.05). Furthermore, chronic (day 7 after SAH) blood-brain barrier permeability and vasogenic edema formation were associated with subacute (day 2 after SAH) hyperperfusion (r = 0.53 and 0.66, respectively; p < 0.05). Conclusion: Our imaging findings indicate that SAH-induced brain injury at later stages is associated with progressive changes in tissue perfusion and that chronic hyperperfusion may contribute or point to delayed cerebral damage. Furthermore, multiparametric MRI may significantly aid in diagnosing the brain's status after SAH. Copyright © 2013 S. Karger AG, Basel.

Turkbey B.,U.S. National Cancer Institute | Merino M.J.,U.S. National Institutes of Health | Gallardo E.C.,U.S. National Institutes of Health | Gallardo E.C.,Image science Institute | And 11 more authors.
Journal of Magnetic Resonance Imaging | Year: 2014

Purpose To compare utility of T2-weighted (T2W) MRI and diffusion-weighted MRI (DWI-MRI) obtained with and without an endorectal coil at 3 Tesla (T) for localizing prostate cancer. Materials and Methods This Institutional Review Board-approved study included 20 patients (median prostate-specific antigen, 8.4 ng/mL). Patients underwent consecutive prostate MRIs at 3T, first with a surface coil alone, then with combination of surface, endorectal coils (dual coil) followed by robotic assisted radical prostatectomy. Lesions were mapped at time of acquisition on dual-coil T2W, DWI-MRI. To avoid bias, 6 months later nonendorectal coil T2W, DWI-MRI were mapped. Both MRI evaluations were performed by two readers blinded to pathology with differences resolved by consensus. A lesion-based correlation with whole-mount histopathology was performed. Results At histopathology 51 cancer foci were present ranging in size from 2 to 60 mm the sensitivity of the endorectal dual-coil, nonendorectal coil MRIs were 0.76, 0.45, respectively. PPVs for endorectal dual-coil, nonendorectal coil MRI were 0.80, 0.64, respectively. Mean size of detected lesions with nonendorectal coil MRI were larger than those detected by dual-coil MRI (22 mm versus 17.4 mm). Conclusion Dual-coil prostate MRI detected more cancer foci than nonendorectal coil MRI. While nonendorectal coil MRI is an attractive alternative, physicians performing prostate MRI should be aware of its limitations. Copyright © 2013 Wiley Periodicals, Inc.

Smeets P.A.M.,Image science Institute | Smeets P.A.M.,Wageningen University | Kroese F.M.,University Utrecht | Evers C.,University Utrecht | De Ridder D.T.D.,University Utrecht
Behavioural Brain Research | Year: 2013

Typically, it is believed that palatable, high caloric foods signal reward and trigger indulgent responses. However, Counteractive Control Theory suggests that, to the extent that people are concerned about their weight, a confrontation with palatable foods should also trigger 'alarm bell responses' which promote successful self-control. Our study is the first to investigate such counteractive control processes in the brain employing functional magnetic resonance imaging (fMRI) in a sample of successful self-regulators. Indeed, besides the traditional finding that foods elicit heightened attention as witnessed by greater activation of primary visual cortex, we found that viewing palatable foods elicited brain activation in areas associated with self-regulation. Crucially, brain activation in self-regulation areas was related to diet importance. Thus, our results are the first to show that food cues not only evoke hedonic brain responses; in successful self-regulators they also trigger alarm bell responses, which may reflect the neural processes underlying successful self-control. © 2013 Elsevier B.V.

Zijlstra F.,Image science Institute | Viergever M.A.,Image science Institute | Seevinck P.R.,Image science Institute
Investigative Radiology | Year: 2016

Objectives The aim of this study was to investigate the influence of variable density and data-driven k-space undersampling patterns on reconstruction quality for compressed sensing (CS) magnetic resonance imaging to provide recommendations on how to avoid suboptimal CS reconstructions. Materials and Methods First, we investigated the influence of randomness and sampling density on the reconstruction quality when using random variable density and variable density Poisson disk undersampling. Compressed sensing reconstructions on 1 knee and 2 brain data sets were compared with fully sampled data sets and reconstruction errors were measured. Sampling coherence was evaluated on the undersampling patterns to investigate whether there was a relation between this coherence measure and reconstruction error. Second, we investigated whether data-driven undersampling methods could improve reconstruction quality when 1 or more fully sampled scans are available as a training set. We implemented 3 different data-driven undersampling methods: (1) Monte Carlo optimization of variable density and variable density Poisson disk undersampling, (2) calculating sampling probabilities directly from the k-space power spectra of the training data, and (3) iterative design of undersampling patterns based on CS reconstruction errors in k-space. Two cross-validation experiments were set up using retrospective undersampling to evaluate the 3 data-driven methods and the influence of the size of the training set. Furthermore, in an experiment that included prospective under sampling, we show the practical applicability of 2 of the data-driven methods. Compressed sensing reconstruction quality was measured with both the normalized root-mean-square error metric and the mean structural similarity index measure. Results Different optimal variable sampling densities were found for each of the data sets, showing that the optimal sampling density is data dependent. Choosing a sampling density other than the optimal density decreased reconstruction quality. These results suggest that choosing a sampling density without having any reference scans is likely suboptimal. Furthermore, no meaningful correlation was found between sampling coherence and reconstruction error. For the data-driven methods, the iterative method yielded statistically significantly higher reconstruction quality in both retrospective and prospective experiments. In retrospective experiments, the power spectrum method yielded a reconstruction quality that was comparable with the data-driven variable density method. The size of the training set had only a minor influence on the reconstruction quality. Conclusions Data-driven undersampling methods can be used to avoid suboptimal reconstruction quality in CS magnetic resonance imaging, provided that at least 1 fully sampled scan is available to train the data-driven method. The iterative design method resulted in the highest reconstruction quality. © 2015 Wolters Kluwer Health, Inc.

Benders M.J.,Wilhelmina Childrens Hospital | Van Der Aa N.E.,Wilhelmina Childrens Hospital | Roks M.,Wilhelmina Childrens Hospital | Van Straaten H.L.,Isala Hospital Zwolle | And 6 more authors.
Journal of Pediatrics | Year: 2014

Objective To perform a feasibility and safety study with recombinant human erythropoietin (rhEPO) in neonates with perinatal arterial ischemic stroke. Study design Neonates with a magnetic resonance imaging-confirmed perinatal arterial ischemic stroke (n = 21) were treated with 1000 IU/kg rhEPO immediately after diagnosis and at 24 and 48 hours after the first dose. Repeat magnetic resonance imaging was performed when the patients were 3 months of age. Coagulation and hematologic variables (red blood cells, white blood cells, platelet counts) were performed in the first week after initiation of treatment. We also compared 10 patients who were treated with rhEPO with 10 historic infants with perinatal arterial ischemic stroke matched for the involved arterial branch to investigate whether rhEPO reduces the residual size of the infarction and subsequent brain growth between first and second scan. Results Seizures were a first symptom in 20 of 21 neonates. Heart rate, blood pressure, and coagulation function were in the normal range, as were red blood cells, white blood cells, and platelet counts. In a subgroup of 10 rhEPO-treated neonates, no differences were detected in residual infarction volumes or neurodevelopmental outcome compared with their historical nontreated counterparts. Conclusions rhEPO in neonates with perinatal arterial ischemic stroke had no adverse effects on red blood cells, white blood cells, platelets counts, or coagulation. rhEPO, 3000 IU/kg in total, given during a 3-day period, appears to be a safe therapy. The beneficial effects remains to be demonstrated in a larger, randomized, double-blind, placebo-controlled trial. © 2014 Mosby Inc.

Van Der Aa N.E.,Wilhelmina Childrens Hospital | Leemans A.,Image science Institute | Northington F.J.,Johns Hopkins Hospital | Van Straaten H.L.,Isala Clinics | And 4 more authors.
Stroke | Year: 2011

Background and Purpose: After perinatal arterial ischemic stroke, diffusion-weighted imaging (DWI) and early evaluation of spontaneous motor behavior can be used to predict the development of unilateral motor deficits. The aim of this study was to investigate whether diffusion tensor imaging-based tractography at 3 months of age contributes to this prediction. Methods: Twenty-two infants with unilateral perinatal arterial ischemic stroke were included and scanned during the neonatal period. DWI was used to assess restricted diffusion in the cerebral peduncle. At the age of 3 months, diffusion tensor imaging-based tractography of the corticospinal tracts was performed along with assessment of the movement repertoire. The role of DWI, diffusion tensor imaging, and motor assessment in predicting unilateral motor deficits were compared by calculating the positive and negative predictive values for each assessment. Results: Eleven infants (50%) showed abnormal motor behavior at 3 months with subsequent development of unilateral motor deficits in 8 as determined at follow-up (9-48 months, positive predictive value 73%). Diffusion tensor imaging-based tractography correctly predicted the development of unilateral motor deficits in all 8 infants (positive predictive value 100%). A diagnostic neonatal DWI was available in 20 of 22 (91%) infants. Seven infants showed an abnormal DWI, resulting in unilateral motor deficits in 6 infants (positive predictive value 86%). All assessments had a negative predictive value of 100%. Conclusions: Diffusion tensor imaging-based tractography at 3 months can be used to predict neurodevelopmental outcome after perinatal arterial ischemic stroke. It has a similar predictive value as DWI in the neonatal period and can especially be of additional value in case of an indecisive neonatal DWI or unexpected abnormal early motor development. © 2011 American Heart Association, Inc.

Wisse L.E.M.,Brain Center Rudolf Magnus | Wisse L.E.M.,Julius Center for Health science and Primary Care | Biessels G.J.,Brain Center Rudolf Magnus | Heringa S.M.,Brain Center Rudolf Magnus | And 4 more authors.
Neurobiology of Aging | Year: 2014

We compared hippocampal subfield and entorhinal cortex (ERC) volumes between patients with mild cognitive impairment (MCI), Alzheimer's disease (AD), and controls without cognitive impairment. Additionally, we investigated the relation between age and hippocampal subfields and ERC in controls. We performed ultra-high field 0.7 mm3 7Tesla magnetic resonance imaging in 16 patients with amnestic MCI, 9 with AD, and 29 controls. ERC, subiculum, cornu ammonis (CA)1, CA2, CA3, and dentate gyrus (DG)&CA4 were traced on T2-weighted images. Analyses of covariance, adjusted for age, sex, and intracranial volume showed that compared with controls and patients with MCI, patients with AD had significantly smaller ERC, subiculum, CA1, CA3, and DG&CA4 volumes. Trend analyses revealed similar associations between ERC and hippocampal subfields and diagnostic group. Older age was significantly associated with smaller CA1 and DG&CA4 volumes. In conclusion, almost all hippocampal subfields and ERC show volume reductions in patients with AD compared with controls and patients with MCI. Future, larger studies should determine which subfields are affected earliest in the disease process and what mechanisms underlie the volume loss. © 2014 Elsevier Inc.

Noorda Y.H.,Image science Institute | Bartels L.W.,Image science Institute | Pluim J.P.W.,Image science Institute
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Interventional non-invasive MR-guided techniques for treatment of liver tumors, such as HIFU, could benefit greatly from automatic cartilage detection. In this paper, segmentation of the cartilage in the rib cage is performed in 3D MR images. This is a challenging task, due to the poor contrast between cartilage and muscle, and the non-uniform intensity of the cartilage. Our segmentation algorithm is based on feature selection by analyzing orientation and vesselness, automatic sternum localization using anatomical knowledge, skeletonization and ridge finding, and level set evolution. We show that our algorithm is capable of detecting all visible cartilage structures in the scans. Gaps and false positives may occur, due to lack of contrast or the presence of non-cartilage structures with similar features. However, the segmentation is accurate, even for regions with low contrast, with an average error of the boundary of 1.1 mm. © 2012 Springer-Verlag.

Wijlemans J.W.,University Utrecht | Deckers R.,Image science Institute | Van Den Bosch M.A.A.J.,University Utrecht | Seinstra B.A.,University Utrecht | And 4 more authors.
Investigative Radiology | Year: 2013

OBJECTIVES: Volumetric magnetic resonance (MR)-guided high-intensity focused ultrasound (HIFU) is a completely noninvasive image-guided thermal ablation technique. Recently, there has been growing interest in the use of MR-HIFU for noninvasive ablation of malignant tumors. Of particular interest for noninvasive ablation of malignant tumors is reliable treatment monitoring and evaluation of response. At this point, there is limited evidence on the evolution of the ablation region after MR-HIFU treatment. The purpose of the present study was to comprehensively characterize the evolution of the ablation region after volumetric MR-HIFU ablation in a Vx2 tumor model using MR imaging, MR temperature data, and histological data. MATERIALS AND METHODS: Vx2 tumors in the hind limb muscle of New Zealand White rabbits (n = 30) were ablated using a clinical MR-HIFU system. Twenty-four animals were available for analyses. Magnetic resonance imaging was performed before and immediately after ablation; MR temperature mapping was performed during the ablation. The animals were distributed over 7 groups with different follow-up lengths. Depending on the group, animals were reimaged and then killed on day 0, 1, 3, 7, 14, 21, or 28 after ablation. For all time points, the size of nonperfused areas (NPAs) on contrast-enhanced T1-weighted (CE-T1-w) images was compared with lethal thermal dose areas (ie, the tissue area that received a thermal dose of 240 equivalent minutes or greater [EM] at 43 C) and with the necrotic tissue areas on histology sections. RESULTS: The NPA on CE-T1-w imaging showed an increase in median size from 266 ± 148 to 392 ± 178 mm during the first day and to 343 ± 170 mm on day 3, followed by a gradual decrease to 113 ± 103 mm on day 28. Immediately after ablation, the NPA was 1.6 ± 1.4 times larger than the area that received a thermal dose of 240 EM or greater in all animals. The median size of the necrotic area on histology was 1.7 ± 0.4 times larger than the NPA immediately after ablation. After 7 days, the size of the NPA was in agreement with the necrotic tissue area on histology (ratio, 1.0 ± 0.2). CONCLUSIONS: During the first 3 days after MR-HIFU ablation, the ablation region increases in size, after which it gradually decreases in size. The NPA on CE-T1-w imaging underestimates the extent of tissue necrosis on histology in the initial few days, but after 1 week, the NPA is reliable in delineating the necrotic tissue area. The 240-EM thermal dose limit underestimates the necrotic tissue area immediately after MR-HIFU ablation. Reliable treatment evaluation techniques are particularly important for noninvasive, image-guided tumor ablation. Our results indicate that CE-T1-w imaging is reliable for MR-HIFU treatment evaluation after 1 week. Copyright © 2013 Lippincott Williams & Wilkins.

Loading Image science Institute collaborators
Loading Image science Institute collaborators