B32G1ZZ
Computerized Tomography (CT Scan) Vertebral Arteries, Bilateral to None with None, Low Osmolar Approach
Procedural Specifications
| Clinical Axis | Detail Definition |
|---|---|
| Section | B Imaging |
| Body System | 3 Upper Arteries |
| Operation | 2 Computerized Tomography (CT Scan) |
| Body Part | G Vertebral Arteries, Bilateral |
| Approach | 1 Low Osmolar |
| Device | Z None |
| Qualifier | Z None |
Operation Definition
Computer reformatted digital display of multiplanar images developed from the capture of multiple exposures of external ionizing radiation
Procedure Overview
CT scanning of the upper arteries uses a rotating x-ray source to collect many thin cross-sectional exposures of the arm's vessels, which a computer then reassembles into detailed two- and three-dimensional images. When paired with an intravenous contrast injection, the technique, often called CT angiography, sharply outlines the artery's inner wall and lumen, allowing detection of narrowing, blockage, aneurysm, or vessel wall irregularity with more anatomic detail than a standard x-ray and without the need to thread a catheter into the vessel itself.
It is commonly ordered when a physician needs a fast, non-invasive look at arterial anatomy before surgery or an interventional procedure, or to evaluate trauma, suspected clot, or unexplained arm symptoms when catheter-based imaging is not immediately necessary. The scan itself takes only a few minutes, though the patient may need to hold still and receive contrast dye through an intravenous line beforehand.
Anatomy & Axis Detail
Vertebral Arteries, Bilateral
The vertebral arteries arise from the subclavian arteries and travel through the transverse foramina of the cervical vertebrae before joining to form the basilar artery, supplying the posterior circulation of the brainstem and cerebellum. Because of their tortuous, bony-encased course, they are prone to dissection, particularly after trauma or neck manipulation, as well as to osteophyte-related compression and atherosclerotic disease at their origins. Bilateral CT angiography is ordered when posterior circulation stroke, vertigo, or drop attacks raise suspicion for vertebrobasilar insufficiency, and it lets the radiologist assess for asymmetry, hypoplasia, or occlusion between the two sides. The segmented, bony canal these vessels pass through can create streak artifact, so image reconstruction and windowing are tailored to separate vessel wall from adjacent osseous structures.
Contrast: Low Osmolar
Low Osmolar denotes use of a low-osmolar iodinated contrast agent during an imaging study, the class most commonly used in modern radiographic and CT imaging because it better approximates the osmolality of blood and carries a lower risk of reaction than High Osmolar media. This value distinguishes studies performed with this now-standard contrast type from those using older high-osmolar agents or no contrast at all.
Coding & Documentation
The report needs to identify CT as the modality and specify the artery or arterial segment studied, along with whether contrast was used, since the qualifier for unenhanced, enhanced, or both must reflect exactly what the protocol describes. Coders should confirm the exam was diagnostic imaging of the artery itself and not a CT performed to guide a separate interventional procedure, which is captured differently. A recurring mistake is coding a CT angiogram of the upper extremity under a general chest or thorax body part because the scan field extended into that region, when the artery actually examined should drive the code selection instead.
Commonly Confused With
CT angiography of the upper arteries is frequently confused with fluoroscopic arteriography of the same vessels, since both rely on injected contrast to outline the artery; the difference is that CT builds a reconstructed image from a series of exposures taken as the patient passes through the scanner, while fluoroscopy shows contrast moving in real time on a continuously viewed screen. It should also be distinguished from plain radiography, which lacks both contrast enhancement and cross-sectional reconstruction, and from magnetic resonance angiography of the same region, which achieves a similar vascular image using a magnetic field rather than ionizing radiation.