Bscan

B-scan, or brightness mode, is a two-dimensional ultrasound imaging modality that displays tissue interfaces as a grayscale cross-section. Echo strength is mapped to brightness, producing real-time images of anatomical structures. It is one of the foundational ultrasound modes, complementing A-scan (one-dimensional depth information) and M-mode (motion over time).

In ophthalmology, B-scan ultrasonography is essential when the ocular media are opaque, enabling visualization of the posterior segment and orbit. It can reveal retinal detachment, vitreous detachment or hemorrhage, tumors, foreign bodies, and lens dislocations. In obstetrics and gynecology, B-scan provides two-dimensional images of the fetus, placenta, uterus, and adnexa. In abdominal, urogenital, and vascular imaging, B-scan is used to evaluate organs and guide procedures, often as part of standard ultrasound studies.

Technical notes: B-scan uses a transducer to emit short ultrasound pulses and decode returning echoes into a grayscale image with depth information along one axis. Resolution and penetration depend on frequency: higher frequencies yield crisper images with shallower penetration (common in orbital and ocular imaging), while lower frequencies allow deeper visualization. In ophthalmology, B-scan can be performed with contact or immersion techniques; immobilization and proper coupling improve image quality. Potential artifacts include shadowing, glare, and multipath echoes; operator skill and patient factors influence the diagnostic value.