638 research outputs found
Prediction of final infarct volume from native CT perfusion and treatment parameters using deep learning
CT Perfusion (CTP) imaging has gained importance in the diagnosis of acute
stroke. Conventional perfusion analysis performs a deconvolution of the
measurements and thresholds the perfusion parameters to determine the tissue
status. We pursue a data-driven and deconvolution-free approach, where a deep
neural network learns to predict the final infarct volume directly from the
native CTP images and metadata such as the time parameters and treatment. This
would allow clinicians to simulate various treatments and gain insight into
predicted tissue status over time. We demonstrate on a multicenter dataset that
our approach is able to predict the final infarct and effectively uses the
metadata. An ablation study shows that using the native CTP measurements
instead of the deconvolved measurements improves the prediction.Comment: Accepted for publication in Medical Image Analysi
n- ΠΈΡΡΠΈΡΠ»Π΅Π½ΠΈΠ΅ β ΡΠ΅Π°Π»ΠΈΡΡΠΈΡΠ½Π°Ρ ΡΠΎΡΠΌΠ°Π»ΠΈΠ·Π°ΡΠΈΡ ΠΊΠ»Π°ΡΡΠ° ΠΏΠ΅ΡΠ΅ΠΏΠΈΡΡΠ²Π°ΡΡΠΈΡ ΡΠΈΡΡΠ΅ΠΌ
ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ Π½ΠΎΠ²ΡΠΉ ΡΠΎΡΠΌΠ°Π»ΠΈΠ·ΠΌ ΡΠΈΠΏΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Ξ·-ΠΈΡΡΠΈΡΠ»Π΅Π½ΠΈΡ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΎΡΠ½ΠΎΠ²Ρ Π΄Π»Ρ ΠΏΠΎ-ΡΡΡΠΎΠ΅Π½ΠΈΡ ΡΠΏΠ΅ΡΠΈΠ°Π»ΡΠ½ΡΡ
ΠΊΠ»Π°ΡΡΠΎΠ² ΡΠΈΡΡΠ΅ΠΌ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΏΠ΅ΡΠ΅ΠΏΠΈΡΡΠ²Π°ΡΡΠΈΡ
ΠΏΡΠ°Π²ΠΈΠ». Π€ΠΎΡΠΌΠ°-Π»ΠΈΠ·ΠΌ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅Ρ ΡΠΏΠΎΡΡΠ΄ΠΎΡΠ΅Π½Π½ΡΠ΅ Π½Π΅ΠΊΠΎΠ½ΡΠ»ΡΡΠ½ΡΠ½ΡΠ΅ ΠΌΠ½ΠΎΠΆΠ΅ΡΡΠ²Π° ΠΏΡΠ°Π²ΠΈΠ» ΠΏΠ΅ΡΠ΅ΠΏΠΈΡΡΠ²Π°Π½ΠΈΡ ΠΈ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ Ρ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠ½ΡΠΌ ΠΎΠΊΡΡΠΆΠ΅Π½ΠΈΠ΅ΠΌ, ΡΡΠΎ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΡΠ°ΡΡΠΈΡΠΈΡΡ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠΈΠ»ΠΎΠΆΠ΅Π½ΠΈΠΉ
Acquisition time and reproducibility of continuous arterial spin-labeling perfusion imaging at 3 T
SUMMARY: Arterial spin-labeling (ASL) is a relatively new and noninvasive MR imaging technique, used to measure cerebral blood flow (CBF). Scanning time and reproducibility remain important issues in the clinical applicability of ASL. We expected both to benefit from higher field strengths. We describe that when performing ASL at 3T, 20 averages suffice to obtain steady and reproducible CBF values. Scanning time can be as short as 3 minutes. A rterial spin labeling (ASL) is a noninvasive MR imaging technique, used for visualization and quantification of cerebral perfusion. Cerebral blood flow (CBF) values measured by ASL are comparable with CBF values measured by conventional techniques (eg, positron-emission tomography or susceptibility-weighted MR imaging). ASL is based on magnetic labeling of arterial blood water protons, which are used as an endogenous tracer of flow. Magnetic inversion takes place in a plane proximal to the brain. The decay rate of the labeled spins is sufficiently long to visualize perfusion of brain vasculature and microvasculature. Perfusion images are obtained by subtraction of successively acquired labeled and nonlabeled control images. In general, 40 to 60 paired acquisitions are averaged to improve perfusion signal intensity. ASL sequences differ in the way magnetic labeling is applied and are commonly classified as continuous or pulsed ASL (CASL or PASL, respectively). In CASL, continuous adiabatic inversion of spins is applied. In PASL, labeling is performed at once over a wide spatial range. Pseudocontinuous ASL (pCASL) has been introduced recently and uses a series of discrete labeling pulses. 1-8 Despite its advantages, scanning time and reproducibility remain important issues in the clinical applicability of ASL. The use of higher-field strengths could overcome these issues because of increased signal-to-noise ratio, prolonged T1-weighted relaxation time of labeled blood, and better spatial and temporal resolution. Also, we hypothesized that acquisition-related reproducibility of ASL will improve at higher-field strengths, whereas physiology-related reproducibility will not change. Previous CASL reproducibility studies were performed at 1.5T with test-retest timeframes of at least 1 hour. Technique After approval of the local ethics committee and written informed consent from all volunteers, we scanned 10 volunteers (5 men; age range, 25-33 years) without known cerebrovascular disease during 3 different sessions within 3 weeks. Each session protocol consisted of 2 CASL sequences preceded by MR angiography. All scans were performed on a 3T Intera MR scanner with a transmit-receive head coil from the manufacturer (Philips Medical Systems, Best, the Netherlands). The 3D time-of-flight MR angiography was obtained to allow for careful planning of the labeling plane perpendicular to the distal ascending portion of the internal carotid and basilar arteries, 10 -20 mm below the circle of Willis. For the ASL sequences, we implemented the amplitude-modulated CASL approach described by Alsop and Detre 5 , without compromising clinical specific absorption rate levels. We used spin-echo single-shot echo-planar imaging. The imaging volume was positioned parallel to the labeling plane with its center 60 mm above the labeling plane. ASL parameters were TR, 4500 ms; TE, 32ms; flip angle, 90Β°; FOV, 210 Ο« 210; section thickness, 7 mm with 1-mm gap; matrix size, 64 Ο« 45 (reconstructed to 64 Ο« 64); 50 averages; labeling duration, 2.0 s; radiofrequency pulse amplitude, 3.5 T; gradient strength, 2.5 mT/m; modulation frequency, 250 Hz; and postlabeling delay, 1.2 to 2.2 s. FSL (FMRIB-Software-Library, Functional Magnetic Resonance Imaging of the Brain Centre, Department of Clinical Neurology, University of Oxford, Oxford, UK) was used for off-line data processing. f Ο β¬MR 1a 2β£M con {e ΟͺwR1a Οͺ e Οͺ(Ο©W)R1a } in which f is CBF (mL/g/s), β£ is the labeling efficiency at 3T (0.68), 7 is the blood-brain partition coefficient (0.98 mL/g), β¬M is the difference between labeled image and control image intensity, R 1a is the longitudinal relaxation time of blood (0.67 s Οͺ1 ), M con is the average control image intensity, β» is the labeling duration (2 s), and w is the postlabeling delay (1.2-2.2 s)
Prevention of large-vessel stenoses in atypical hemolytic uremic syndrome associated with complement dysregulation
Fatal human rabies due to Duvenhage virus from a bat in Kenya: failure of treatment with coma-induction, ketamine, and antiviral drugs
Aortic valve calcification volumes and chronic brain infarctions in patients undergoing transcatheter aortic valve implantation
Stroke Etiology and Thrombus Computed Tomography Characteristics in Patients With Acute Ischemic Stroke:A MR CLEAN Registry Substudy
Background and Purpose - If a relationship between stroke etiology and thrombus computed tomography characteristics exists, assessing these characteristics in clinical practice could serve as a useful additional diagnostic tool for the identification of stroke subtype. Our purpose was to study the association of stroke etiology and thrombus computed tomography characteristics in patients with acute ischemic stroke due to a large vessel occlusion. Methods - For 1429 consecutive patients enrolled in the MR CLEAN Registry, we determined stroke cause as defined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) criteria. The association of stroke etiology with the hyperdense artery sign, clot burden score, and thrombus location was estimated with univariable and multivariable binary and ordinal logistic regression. Additionally, for 367 patients with available thin-section imaging, we assessed the association of stroke etiology with absolute and relative thrombus attenuation, distance from internal carotid artery-terminus to thrombus, thrombus length, and thrombus attenuation increase with univariable and multivariable linear regression. Results - Compared with cardioembolic strokes, noncardioembolic strokes were associated with presence of hyperdense artery sign (odds ratio, 2.2 [95% CI, 1.6-3.0]), lower clot burden score (common odds ratio, 0.4 [95% CI, 0.3-0.6]), shift towards a more proximal thrombus location (common odds ratio, 0.2 [95% CI, 0.2-0.3]), higher absolute thrombus attenuation (Ξ², 3.6 [95% CI, 0.9-6.4]), decrease in distance from the ICA-terminus (Ξ², -5.7 [95% CI, -8.3 to -3.0]), and longer thrombi (Ξ², 8.6 [95% CI, 6.5-10.7]), based on univariable analysis. Thrombus characteristics of strokes with undetermined cause were similar to those of cardioembolic strokes. Conclusions - Thrombus computed tomography characteristics of cardioembolic stroke are distinct from those of noncardioembolic stroke. Additionally, our study supports the general hypothesis that many cryptogenic strokes have a cardioembolic cause. Further research should focus on the use of thrombus computed tomography characteristics as a diagnostic tool for stroke cause in clinical practice
Cardiac output, cerebral blood flow and cognition in patients with severe aortic valve stenosis undergoing transcatheter aortic valve implantation:design and rationale of the CAPITA study
Background :Β Approximately one-third of patients with symptomatic severe aortic valve stenosis who are scheduled for transcatheter aortic valve implantation (TAVI) have some degree of cognitive impairment. TAVI may have negative cognitive effects due to periprocedural micro-emboli inducing cerebral infarction. On the contrary, TAVI may also have positive cognitive effects due to increases in cardiac output and cerebral blood flow (CBF). However, studies that systematically assess these effects are scarce. Therefore, the main aim of this study is to assess cerebral and cognitive outcomes in patients with severe aortic valve stenosis undergoing TAVI.Β Study design :Β In the prospective CAPITA (CArdiac OutPut, Cerebral Blood Flow and Cognition In Patients With Severe Aortic Valve Stenosis Undergoing Transcatheter Aortic Valve Implantation) study, cerebral and cognitive outcomes are assessed in patients undergoing TAVI. One day before and 3Β months after TAVI, patients will undergo echocardiography (cardiac output, valve function), brain magnetic resonance imaging (CBF, structural lesions) and extensive neuropsychological assessment. To assess longer-term effects of TAVI, patients will again undergo echocardiography and neuropsychological assessment 1Β year after the procedure. The co-primary outcome measures are change in CBF (in ml/100β―g per min) and change in global cognitive functioning (Z-score) between baseline and 3βmonth follow-up. Secondary objectives include change in cardiac output, white matter hyperintensities and other structural brain lesions. (ClinicalTrials.gov identifier NCT05481008)Β Conclusion :Β The CAPITA study is the first study designed to systematically assess positive and negative cerebral and cognitive outcomes after TAVI. We hypothesise that TAVI improves cardiac output, CBF and cognitive functioning.</p
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