The ICA MRA includes original segment labels. The DSA examples are unannotated reference images; the reading prompts are teaching guidance, not verified pixel annotations.
AN INTERACTIVE GUIDE TO CEREBRAL ANGIOGRAPHY
Understand the projection.
One patient's vascular tree, from real CTA. Move the C-arm and watch anatomy become an angiogram.
PATIENT-MATCHED CTA 02 / ARTERIAL & VENOUS
01 3D anatomy
PATIENT AXES
Drag to orbit · Scroll to zoom · Click a vessel
ICA / MCAACA / communicatingPCA / vertebrobasilarCerebellarVeins
02 Angiographic projection
AP · 0°
RLSUBTRACTED
LEFT CAROTID TREE · SEGMENTS & ORIGINS
Middle cerebral artery
About this model · Patient-matched CTA.
FROM THE MODEL TO THE IMAGE
Real angiography. Real variation.
The CTA MIP · real mode in the projection panel already shows this patient's actual CTA, projected at the current C-arm angle and restricted to the intracranial space. Below, compare with published catheter angiograms. These are independent reference cases, not images of either CTA patient, and their acquisition angles are not calibrated to the simulator.
Image delivery is unavailable. Open the original teaching image using the source link below.
PATIENT-MATCHED ANATOMY
Every view comes from one real scan.
For each case, the vessels, brain, skull, slices and the CTA projections derive from the same TopCoW/TopBrain CTA, in one coordinate frame. Named segments are the TopBrain expert labels. Branches beyond those labels are traced from the CTA's own contrast and assigned to their labelled parent.
TopBrain release ↗ · TopCoW scans & masks ↗ · Centreline graphs ↗FIELD GUIDE
Read the anatomy before the image.
Name the detector side
LAO and RAO name the side of the patient nearest the detector. Cranial and caudal name where the detector is tilted. In the Table & C-arm panel the patient and table stay fixed; only the arm rotates about the isocentre. The projection is displayed as seen from the detector, so in AP the patient's right is on your left.
Depth becomes overlap
A projection collapses three-dimensional anatomy onto a plane, magnified by the beam's divergence from the source. AP separates left from right; lateral separates anterior from posterior. Oblique and angulated views open branch origins hidden by overlap and foreshortening.
Subtracted, unsubtracted, real
Subtracted shows contrast path length through the segmented vessels, like a road-map of DSA. Unsubtracted adds a radiograph computed through the real CTA, so the skull base and calvarium overlie the vessels. CTA MIP is the patient's actual CTA, projected at the same angle.
Choose an injection
Compare each internal carotid tree with the vertebrobasilar tree, then show all arteries to inspect the communicating connections. The venous option shows labelled sinuses, deep veins and CTA-traced cortical veins. Filters select anatomy; they do not model flow, collateral filling or timing.
Where labels end
Expert labels stop at M3, A3 and P3–P4. Beyond them, branches visible on the CTA are traced and grouped by parent: “MCA cortical branches”, “ACA distal branches” and so on. Their completeness depends on the scan's contrast. Case 002 shows many; case 008 shows fewer.
Brain and skull
Brain structures follow this patient's CTA brain envelope, divided by a registered atlas. Turn on Skull and Brain, then use “Look along imaging axis” to see what the beam passes through at the current angle.
ABOUT & REFERENCES
Real anatomy, built for neurovascular learning.
Learn Cerebral is an independent educational project that pairs a patient's 3D cerebral vessels with the angiogram a C-arm would produce from any angle. It is inspired by the anatomy–projection–C-arm teaching approach of LearnCoronary; all code, models and imagery here are original or openly licensed.
Created by Sam Bogdanov · Built with Claude Opus 5.5 and GPT Sol-6.1 / Astra-6
How the models are built
Vessels: per-label surfaces of the TopBrain v2 (36-class) arterial and v1 venous annotations for TopCoW CTA cases 002 and 008, extracted at native resolution. Distal branches: CTA voxels above a case-specific threshold inside the brain, connected to the labelled tree and assigned to the nearest labelled parent by geodesic propagation; ICA-adjacent cavernous enhancement is excluded. Brain: the patient's CTA brain envelope, parcellated by the Harvard–Oxford subcortical and Diedrichsen cerebellar atlases after a 12-parameter affine registration (Dice 0.93 for case 002, 0.91 for case 008). Projections: perspective C-arm geometry (SID 1100 mm, SOD 750 mm, illustrative), Beer–Lambert path length through vessel surfaces, and ray-marched DRR/MIP through the 1 mm CTA.
About the simulation
Every view is generated from real CT angiography, so vessel courses, overlap and foreshortening reflect a real patient rather than an idealized drawing. The projection is a teaching simulation designed to build intuition for how acquisition angles shape the image: it shows where contrast-filled vessels project, not the full physics of an X-ray system, blood flow or contrast timing. Distal branches are traced directly from the scan's contrast, and preset angles are common starting points for exploring each circulation. Learn Cerebral is intended for education, not for clinical decision-making.
What's next
Planned additions include review of the anatomy and segment naming with neurointerventional colleagues, additional patient cases from the TopBrain collection, timed arterial-to-venous contrast phases, more physically realistic image contrast for bone and iodine, and finer brain-structure registration for territory teaching.
Data sources & licences
- CTA scans and TopCoW Circle of Willis masks: Yang et al., TopCoW 2024 MICCAI Challenge Data Release, University Hospital Zurich / University of Zurich. Dataset · Terms. Open use with source attribution; commercial use requires data-owner permission.
- Whole-brain vessel labels: TopBrain Challenge Data Release (Yang K, Shi P, Huang H, et al. TopBrain segmentation challenge for whole brain vessel anatomy. medRxiv 2026). Dataset · Terms. Same terms as TopCoW.
- Centreline graphs: Musio et al., Circle of Willis Centerline Graphs and Morphometric Features. Dataset, CC BY-NC as supplied. Supplied licence.
- Harvard–Oxford subcortical atlas (FSL; via the neurodata/neuroparc collection), FSL licence, non-commercial. Diedrichsen 2009 probabilistic cerebellar atlas (via DiedrichsenLab/cerebellar_atlases), CC BY. See atlas sources.
- Rendering uses Three.js 0.180.0 (MIT).