21 research outputs found
Retrieval and Registration of Long-Range Overlapping Frames for Scalable Mosaicking of In Vivo Fetoscopy
Purpose: The standard clinical treatment of Twin-to-Twin Transfusion Syndrome
consists in the photo-coagulation of undesired anastomoses located on the
placenta which are responsible to a blood transfer between the two twins. While
being the standard of care procedure, fetoscopy suffers from a limited
field-of-view of the placenta resulting in missed anastomoses. To facilitate
the task of the clinician, building a global map of the placenta providing a
larger overview of the vascular network is highly desired. Methods: To overcome
the challenging visual conditions inherent to in vivo sequences (low contrast,
obstructions or presence of artifacts, among others), we propose the following
contributions: (i) robust pairwise registration is achieved by aligning the
orientation of the image gradients, and (ii) difficulties regarding long-range
consistency (e.g. due to the presence of outliers) is tackled via a bag-of-word
strategy, which identifies overlapping frames of the sequence to be registered
regardless of their respective location in time. Results: In addition to visual
difficulties, in vivo sequences are characterised by the intrinsic absence of
gold standard. We present mosaics motivating qualitatively our methodological
choices and demonstrating their promising aspect. We also demonstrate
semi-quantitatively, via visual inspection of registration results, the
efficacy of our registration approach in comparison to two standard baselines.
Conclusion: This paper proposes the first approach for the construction of
mosaics of placenta in in vivo fetoscopy sequences. Robustness to visual
challenges during registration and long-range temporal consistency are
proposed, offering first positive results on in vivo data for which standard
mosaicking techniques are not applicable.Comment: Accepted for publication in International Journal of Computer
Assisted Radiology and Surgery (IJCARS
A double dilemma: treatment of stage IV fetal twin-twin transfusion syndrome in the setting of maternal recurrent venous thromoembolism: a case report
Background: Fetal conditions can pose significant challenges in the management of pregnancies complicated by pre-existing maternal medical conditions. Case presentation: We report a case of a 34-year-old woman with Stage IV Twin Twin Transfusion syndrome in the presence of maternal recurrent complex venous thromboembolic disease. Following a previous pregnancy loss, complicated by a third episode of thromboembolic disease, an inferior vena cava filter was placed. One month later, a pregnancy was confirmed and subsequently identified as a monochorionic twin pregnancy. Twin-Twin Transfusion syndrome was identified at 18 weeks’ gestation and progressed rapidly to Quintero Stage IV. In consultation with a multi-disciplinary international team, fetoscopic laser photocoagulation was performed. The pregnancy progressed to delivery of female infants at 33 weeks gestation, who have achieved all developmental milestones at 2 years of age. Conclusions: We describe the multi-disciplinary effort to optimise the maternal condition to allow fetoscopic laser photocoagulation and continued management of the maternal and fetal conditions to a successful pregnancy outcome
FetReg: Placental Vessel Segmentation and Registration in Fetoscopy Challenge Dataset
Fetoscopy laser photocoagulation is a widely used procedure for the treatment
of Twin-to-Twin Transfusion Syndrome (TTTS), that occur in mono-chorionic
multiple pregnancies due to placental vascular anastomoses. This procedure is
particularly challenging due to limited field of view, poor manoeuvrability of
the fetoscope, poor visibility due to fluid turbidity, variability in light
source, and unusual position of the placenta. This may lead to increased
procedural time and incomplete ablation, resulting in persistent TTTS.
Computer-assisted intervention may help overcome these challenges by expanding
the fetoscopic field of view through video mosaicking and providing better
visualization of the vessel network. However, the research and development in
this domain remain limited due to unavailability of high-quality data to encode
the intra- and inter-procedure variability. Through the \textit{Fetoscopic
Placental Vessel Segmentation and Registration (FetReg)} challenge, we present
a large-scale multi-centre dataset for the development of generalized and
robust semantic segmentation and video mosaicking algorithms for the fetal
environment with a focus on creating drift-free mosaics from long duration
fetoscopy videos. In this paper, we provide an overview of the FetReg dataset,
challenge tasks, evaluation metrics and baseline methods for both segmentation
and registration. Baseline methods results on the FetReg dataset shows that our
dataset poses interesting challenges, offering large opportunity for the
creation of novel methods and models through a community effort initiative
guided by the FetReg challenge
The Effect of Polyhydramnios on Cervical Length in Twins: A Controlled Intervention Study in Complicated Monochorionic Pregnancies
Objective: To test the hypothesis that cervical shortening in polyhydramnios reflects the degree of excess amniotic fluid, and increases with normalisation of amniotic fluid volume. Study Design: Prospective cohort study of 40 women with monochorionic twins undergoing interventional procedures between 16-26 weeks. Cervical length was assessed via transvaginal sonography pre-procedure, 1 and 24 hours postprocedure, and results compared between amnioreduction and control procedures. Amniotic fluid index (AFI) was measured pre- and post-procedure. Results: Pre-procedural cervical length correlated with AFI (linear fit = 5.07 -0.04x, R2 = 0.17, P = 0.03) in patients with polyhydramnios (n = 28). Drainage of 2000ml fluid (range 700-3500ml), reduced AFI from 42cm to 21cm (P>0.001). Their pre-procedural cervical length did not change at one (mean Δ:-0.1cm, 95%CI, -0.4 to 0.2) or 24 hours (0.2cm, -0.1 to 0.6) after amnioreduction. There was no change in cervical length at control procedures. Conclusion: Cervical shortening in twins with polyhydramnios does not appear to be an acute process; cervical length can be measured before or after therapeutic procedures. © 2008 Engineer et al
Vascular regulation in pre-eclampsia
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Inverse linear relationship between pre-procedural cervical length (y) and pre-procedural AFI (x) in group B.
<p>y = 5.07 -0.04x, R<sup>2</sup> = 0.17, <i>P</i> = 0.03.</p
Mean cervical length was unchanged in the two groups over three time periods: pre-procedure, 1 hour post procedure and 24 hour post procedure.
<p><i>Error</i> bars represent standard deviation.</p
Cervical length measurements with mean Δ 1 hour and 24 hour post procedure
<p>Cervical length measurements with mean Δ 1 hour and 24 hour post procedure</p