526 research outputs found
Placental Flattening via Volumetric Parameterization
We present a volumetric mesh-based algorithm for flattening the placenta to a
canonical template to enable effective visualization of local anatomy and
function. Monitoring placental function in vivo promises to support pregnancy
assessment and to improve care outcomes. We aim to alleviate visualization and
interpretation challenges presented by the shape of the placenta when it is
attached to the curved uterine wall. To do so, we flatten the volumetric mesh
that captures placental shape to resemble the well-studied ex vivo shape. We
formulate our method as a map from the in vivo shape to a flattened template
that minimizes the symmetric Dirichlet energy to control distortion throughout
the volume. Local injectivity is enforced via constrained line search during
gradient descent. We evaluate the proposed method on 28 placenta shapes
extracted from MRI images in a clinical study of placental function. We achieve
sub-voxel accuracy in mapping the boundary of the placenta to the template
while successfully controlling distortion throughout the volume. We illustrate
how the resulting mapping of the placenta enhances visualization of placental
anatomy and function. Our code is freely available at
https://github.com/mabulnaga/placenta-flattening .Comment: MICCAI 201
Rule Out (R/O) Intracranial Aneurysm
When imaging patients for intracranial aneurysm, the goals are: (1) to assess the contour of the intracranial arteries, particularly in he regions of the ACOM (anterior communicating artery), PCOM (posterior communicating artery), ICA (internal carotid artery) bifurcation, MCA (middle cerebral artery) trifurcation, basilar tip, and PICA (posterior inferior cerebellar artery); (2) to assess the anatomy of the Circle of Willis and direction of flow, and; (3) to determine if there is evidence of a recent subarachnoid bleed. This unit describes a that can be used for standard imaging of aneurysm in stable patients. An is described for situations when there is concern for vasospasm and infarction.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145398/1/cpmia0102.pd
Cerebral Infarct/Intracranial Cerebrovascular Disease
Imaging goals for intracranial cerebral vascular disease are (1) to assess the degree of parenchymal injury and identify intraparenchymal hemorrhage; (2) to determine if there are areas of altered perfusion that may be at risk for future injury; and (3) to assess the intracranial arteries (patency as well as direction of flow). This unit describes a that can be used to evaluate stable patients with acute, subacute, or chronic cerebrovascular symptoms. An is also given for cases of hyperacute strokes or cerebrovascular symptoms in an unstable patient.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145276/1/cpmia0101.pd
Accuracy of Segment-Anything Model (SAM) in medical image segmentation tasks
The segment-anything model (SAM), was introduced as a fundamental model for
segmenting images. It was trained using over 1 billion masks from 11 million
natural images. The model can perform zero-shot segmentation of images by using
various prompts such as masks, boxes, and points. In this report, we explored
(1) the accuracy of SAM on 12 public medical image segmentation datasets which
cover various organs (brain, breast, chest, lung, skin, liver, bowel, pancreas,
and prostate), image modalities (2D X-ray, histology, endoscropy, and 3D MRI
and CT), and health conditions (normal, lesioned). (2) if the computer vision
foundational segmentation model SAM can provide promising research directions
for medical image segmentation. We found that SAM without re-training on
medical images does not perform as accurately as U-Net or other deep learning
models trained on medical images.Comment: Technical Repor
Transient and Persistent Pain Induced Connectivity Alterations in Pediatric Complex Regional Pain Syndrome
Evaluation of pain-induced changes in functional connectivity was performed in pediatric complex regional pain syndrome (CRPS) patients. High field functional magnetic resonance imaging was done in the symptomatic painful state and at follow up in the asymptomatic pain free/recovered state. Two types of connectivity alterations were defined: (1) Transient increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb vs. unaffected limb in the CRPS state, but with normalized connectivity patterns in the recovered state; and (2) Persistent increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb as compared to the unaffected limb that persisted also in the recovered state (recovered affected limb versus recovered unaffected limb). The data support the notion that even after symptomatic recovery, alterations in brain systems persist, particularly in amygdala and basal ganglia systems. Connectivity analysis may provide a measure of temporal normalization of different circuits/regions when evaluating therapeutic interventions for this condition. The results add emphasis to the importance of early recognition and management in improving outcome of pediatric CRPS
SSL-QALAS: Self-Supervised Learning for Rapid Multiparameter Estimation in Quantitative MRI Using 3D-QALAS
Purpose: To develop and evaluate a method for rapid estimation of
multiparametric T1, T2, proton density (PD), and inversion efficiency (IE) maps
from 3D-quantification using an interleaved Look-Locker acquisition sequence
with T2 preparation pulse (3D-QALAS) measurements using self-supervised
learning (SSL) without the need for an external dictionary. Methods: A
SSL-based QALAS mapping method (SSL-QALAS) was developed for rapid and
dictionary-free estimation of multiparametric maps from 3D-QALAS measurements.
The accuracy of the reconstructed quantitative maps using dictionary matching
and SSL-QALAS was evaluated by comparing the estimated T1 and T2 values with
those obtained from the reference methods on an ISMRM/NIST phantom. The
SSL-QALAS and the dictionary matching methods were also compared in vivo, and
generalizability was evaluated by comparing the scan-specific, pre-trained, and
transfer learning models. Results: Phantom experiments showed that both the
dictionary matching and SSL-QALAS methods produced T1 and T2 estimates that had
a strong linear agreement with the reference values in the ISMRM/NIST phantom.
Further, SSL-QALAS showed similar performance with dictionary matching in
reconstructing the T1, T2, PD, and IE maps on in vivo data. Rapid
reconstruction of multiparametric maps was enabled by inferring the data using
a pre-trained SSL-QALAS model within 10 s. Fast scan-specific tuning was also
demonstrated by fine-tuning the pre-trained model with the target subject's
data within 15 min. Conclusion: The proposed SSL-QALAS method enabled rapid
reconstruction of multiparametric maps from 3D-QALAS measurements without an
external dictionary or labeled ground-truth training data.Comment: 18 figures, 4 table
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