The role of MR venography with time-resolved imaging in diagnosis of pelvic congestion syndrome

Background Pelvic congestion syndrome (PCS) represents a diagnostic challenge due to its variable clinical presentation, complex anatomy, and pathophysiology. Accurate delineation of the venous anatomy, detection of venous reflux or obstruction, its extent will enable interventional radiologists to successfully treat such patients and to avoid recurrence. Magnetic resonance imaging (MRI) allows a noninvasive examination of the anatomy and flow inside the pelvic veins in addition to its excellent soft-tissue contrast allowing evaluation of the pelvic organs. Our study is aiming to investigate the role and accuracy of MR venography with time-resolved imaging (TR-MRV) as a diagnostic tool for pretreatment planning of PCS. Results Our study included 25 female patients with mean age 48 ± 12.34, who were referred to the radiology department in the period from April/2019 to April/2020 with clinical and ultrasound features suggesting PCS. TR-MRV was performed and interpreted in a blind fashion evaluating the vascular anatomy, venous dilatation, and reflux. The results were compared to conventional venography as a reference. The sensitivity, specificity, and accuracy of TR-MRV in the detection of ovarian vein reflux were 87%, 80%, and 84%, respectively, versus 75%, 53%, and 72% in internal iliac vein reflux and 92%, 69%, and 64% for pelvic venous plexus reflux. Demonstration of the venous anatomy was excellent in 68% of the patients and was sufficient in 32%. Ovarian vein dilatation was detected in 16 patients by venography and in 10 patients by TR-MRV. The weighted k-values (Cohen's Kappa coefficient statistics) indicated excellent agreement between the two observers for identifying all the refluxing veins by TRI in each patient (k = 0.78). Conclusion MRI with TR imaging has shown high diagnostic accuracy when compared to conventional venography in evaluating pelvic congestion syndrome before endovascular treatment and thus facilitating treatment planning.

Two-Photon Time-Gated In Vivo Imaging of Dihydrolipoic-Acid-Decorated Gold Nanoclusters

Due to the unique advantages of two-photon technology and time-resolved imaging technology in the biomedical field, attention has been paid to them. Gold clusters possess excellent physicochemical properties and low biotoxicity, which make them greatly advantageous in biological imaging, especially for in vivo animal imaging. A gold nanocluster was coupled with dihydrolipoic acid to obtain a functionalized nanoprobe; the material displayed significant features, including a large two-photon absorption cross-section (up to 1.59 × 105 GM) and prolonged fluorescence lifetime (>300 ns). The two-photon and time-resolution techniques were used to perform cell imaging and in vivo imaging.

Analysis of Molecular Disordering Processes in the Phase Transition of Liquid Crystals Observed by Patterned-Illumination Time-Resolved Phase Microscopy

The initial processes of the phase transition dynamics of liquid crystals (LCs) subject to UV pulse irradiation were clarified using a nanosecond time-resolved imaging technique called pattern-illumination time-resolved phase microscopy (PI-PM). Two types of LCs were studied: a photo-responsive LC and dye-doped LCs. We found two steps of molecular disordering processes in the phase transition, namely local disordering proceeding anisotropically, followed by the spreading of the isotropic phase. These two processes were separated for a photo-responsive LC while being simultaneously observed for the dye-doped LCs. It was found that the photomechanical dyes induced the phase transition process faster than the photothermal dyes.

Dynamic, Time-Resolved Computed Tomography Angiography Technique to Characterize Aortic Endoleak Type, Inflow and Provide Guidance for Targeted Treatment

Purpose: To illustrate dynamic, time-resolved CTA (d-CTA) imaging technique in characterizing aortic endoleak type/inflow using quantitative parameters and its value in providing image guidance for targeted treatment approach. Technique: Dedicated endoleak protocol involved acquiring multiple time-resolved contrast enhanced scans using third-generation CT scanner (Somatom Force®, Siemens Healthineers). Parameters such as scan field of view (FOV), kV, number/timing of scans were customized based on patient’s body-mass-index, timing bolus, and prior imaging findings. D-CTA image datasets were evaluated qualitatively and quantitatively using time-attenuation curves (TAC) analysis after motion correction using a dedicated software ( syngo.via®, Siemens). D-CTA findings from 4 illustrative cases demonstrating type I, type II (inferior mesenteric and lumbar artery inflow), and type III endoleak were illustrated. TAC analysis with time to peak parameter enabled better characterization of endoleak type and inflow. During endoleak intervention, target vessels from d-CTA images were electronically annotated and overlaid on fluoroscopy using 2D−3D image fusion to provide image guidance for targeted treatment. Conclusion: D-CTA imaging with TAC analysis characterizes aortic endoleak type and inflow, in addition to providing image guidance for targeted endoleak treatment. Such dynamic, time-resolved imaging techniques may provide further insights into understanding aortic endoleak that remains an Achilles heel for endovascular aortic aneurysm repair.