Capillary stall quantification from optical coherence tomography angiogram maximum intensity projections

Optical coherence tomography (OCT) is applicable to the study of cerebral microvasculature in vivo. Optimised acquisition schemes enable the generation of three-dimensional OCT angiograms, i.e., volumetric images of red blood cell flux in capillary networks, currently at a repetition rate of up to 1/10 seconds. This makes testable a new class of hypotheses that strive to bridge the gap between microscopic phenomena occurring at the spatial scale of neurons, and less invasive but crude techniques to measure macroscopic blood flow dynamics. Here we present a method for quantifying the occurrence of transient capillary stalls in OCT angiograms, i.e., events during which blood flow through a capillary branch is temporarily occluded. By making the assumption that information on such events is present predominantly in the imaging plane, we implemented a pipeline that automatically segments a network of interconnected capillaries from the maximum intensity projections (MIP) of a series of 3D angiograms. We then developed tools enabling rapid manual assessment of the binary flow status (open/stalled) of hundreds of capillary segments based on the intensity profile of each segment across time. The entire pipeline is optimized to run on a standard laptop computer, requiring no high-performance, low-availability resources, despite very large data volumes. To further reduce the threshold of adoption, and ultimately to support the development of reproducible research methods in the young field, we provide the documented code for scrutiny and re-use under a permissive open-source license.

Postprocessing Imaging Techniques of the Computed Tomography Angiography in Trauma Patients for Preprocedural Planning

Computed tomography provides a wealth of diagnostic information in the trauma patient including the presence of organ, bone, and vasculature injuries for the rapid triage of trauma patients. In the context of interventional radiology, appropriately protocoled studies can be reviewed for vascular injury and help focus the angiographic assessment of bleeding patients to ideally achieve earlier hemostasis. This article outlines various image-processing techniques such as multiplanar reformats, curved planar reformats, maximum intensity projections, and volume rendering to identify and more thoroughly characterize vascular injuries as a preprocedural planning tool to expedite endovascular hemostasis in a case-based format.

Visualizing the autonomic and somatic innervation of the female pelvis with 3D MR neurography: a feasibility study

Background Treatment of female pelvic malignancies often causes pelvic nerve damage. Magnetic resonance (MR) neurography mapping the female pelvic innervation could aid in treatment planning. Purpose To depict female autonomic and somatic pelvic innervation using a modified 3D NerveVIEW sequence. Material and Methods Prospective study in 20 female volunteers (n = 6 normal, n = 14 cervical pathology) who underwent a modified 3D short TI inversion recovery (STIR) turbo spin-echo (TSE) scan with a motion-sensitive driven equilibrium (MSDE) preparation radiofrequency pulse and flow compensation. Modifications included offset independent trapezoid (OIT) pulses for inversion and MSDE refocusing. Maximum intensity projections (MIP) were evaluated by two observers (Observer 1, Observer 2); image quality was scored as 2 = high, 1 = medium, or 0 = low with the sciatic nerve serving as a reference. Conspicuity of autonomic superior (SHP) and bilateral inferior hypogastric plexuses (IHP), hypogastric nerves, and somatic pelvic nerves (sciatic, pudendal) was scored as 2 = well-defined, 1 = poorly defined, or 0 = not seen, and inter-observer agreement was determined. Results Images were of medium to high quality according to both observers agreeing in 15/20 (75%) of individuals. SHP and bilateral hypogastric nerves were seen in 30/60 (50%) of cases by both observers. Bilateral IHP was seen in 85% (34/40) by Observer 1 and in 75% (30/40) by Observer 2. Sciatic nerves were well identified in all cases, while pudendal nerves were seen bilaterally by Observer 1 in 65% (26/40) and by Observer 2 in 72.5% (29/40). Agreement between observers for scoring nerve conspicuity was in the range of 60%–100%. Conclusion Modified 3D NerveVIEW renders high-quality images of the female autonomic and pudendal nerves.

Evaluation of diagnostic accuracy of intracranial aneurysm detection using medical-grade versus commercial consumer-grade displays and different image reconstructions against the background of process optimization for telemedicine

Background Process optimization in computed tomography (CT) and telemedicine. Purpose To compare image quality and objective diagnostic accuracy of medical-grade and consumer-grade digital displays/computer terminals for detection of intracranial aneurysms. Material and Methods Four radiologists with different levels of experience retrospectively read a total of 60 patients including 30 cases of proven therapy-naïve intracranial aneurysm detectable on a medical-grade grayscale calibrated display. They had 5 min per case reading the first 20 datasets using only axial slices, the next 20 patients using axial slices and multiplanar reconstructions (MPRs), and the last 20 patients using axial slices, MPRs, and maximum intensity projections (MIPs). Three months after the first reading session on a medical-grade display, they read all datasets again under the same standardized conditions but on a consumer-grade display. Diagnostic performance, subjective diagnostic confidence, and reading speed were analyzed and compared. Readers rated image quality on a five-point Likert scale. Results Diagnostic accuracy did not differ significantly with areas under the curve of 0.717–0.809 for all readers on both display devices. Sensitivity and specificity did not increase significantly when adding MPRs and/or MIPs. Reading speed was similar with both devices. There were no significant differences in subjective image quality scores, and overall inter-reader variability of all subjective parameters correlated positively between the two devices ( P <0.001–0.011). Conclusion Diagnostic accuracy and readers’ diagnostic confidence in detecting and ruling out intracranial aneurysm were similar on commercial-grade and medical-grade displays. Additional reconstructions did not increase sensitivity/specificity or reduce the time needed for diagnosis.