8.4 Image Acquisition & Interpretation

8.4 Image Acquisition & Interpretation

Quick Answer: Cardiac imaging uses standard RAO/LAO ± cranial/caudal views to profile each coronary artery. Peripheral imaging follows aorto-iliac-femoral-tibial runoff with timed contrast injections. Acquire with adequate opacification, minimal motion, collimation, and appropriate cine frame rate—then interpret dominance, lesion location, TIMI flow, and runoff quality.

Image acquisition is where RCIS technical skill meets clinical anatomy. You run the injectors, drive table and C-arm moves, collimate, trigger cine at the right moment, and often are first to notice dissection, missing runoff, or inadequate fill. The CCI RCIS exam tests both how to obtain diagnostic images and what basic patterns mean on the screen.

Cardiac Angiographic Projections

Coronary arteries are three-dimensional structures imaged in two-dimensional projections. Standard views foreshorten some segments while opening others. The RCIS must anticipate projection sequences and prepare equipment before the physician calls each move.

Left Coronary System

Typical left main / LAD / LCx sequence:

RCIS tips:

• Pre-set C-arm angles on systems that store favorites
• Raise/lower table so detector stays close without hitting the patient during cranial/caudal pivots
• Collimate before cine; include the entire coronary tree requested without irradiating the entire chest
• Watch for ventricularization of pressure traces if imaging coincides with wire manipulations

Right Coronary Artery (RCA)

Dominance (right, left, or codominant) determines which artery supplies the PDA and posterolateral branches—critical for planning PCI and graft surgery. Identify dominance on the first aortic root injection or dedicated RCA/LCA runs.

Peripheral Vascular Image Acquisition

Peripheral angiography evaluates inflow, conduit, and runoff for claudication, critical limb ischemia, aneurysm, or pre-intervention planning.

Aorto-Iliac and Femoral Segments

• AP projection of the abdominal aorta and iliac bifurcation with large-field collimation adjusted to iliac crests
• Oblique views (e.g., 30° RAO/LAO) to unfold external iliac and common femoral arteries and avoid pelvic overlap
• Pigtail or multi-sidehole catheter at L1–L2 for aortography; move to selective hypogastric or internal iliac if needed

RCIS role: Prepare high-volume contrast syringes (power injector or hand injection per protocol), monitor BP and sheath access, and archive runoff before the physician advances into superficial femoral artery (SFA).

Lower Extremity Runoff

Classic runoff from femoral to tibial vessels:

1. Catheter positioned at common femoral or distal external iliac
2. Contrast injection timed to opacify SFA → popliteal → tibial trifurcation
3. AP and lateral views of the knee and ankle; plantar arch in feet when assessing CLI
4. Long-leg acquisition or step-table imaging on biplane or angiographic suites for continuous runoff

Bolus timing separates diagnostic runoff from useless fills. The RCIS triggers cine as contrast enters the target segment—early for long fields, slightly delayed for selective shots.

Acquisition Technique: Cardiac and Peripheral

Shared principles apply across territories:

Contrast and Flow

• Injection rate and volume matched to vessel size (root vs selective RCA vs tibial)
• Saline chase on power injectors reduces contrast load and streak artifact
• Monitor allergies, renal function, and contrast volume limits; communicate cumulative volume

Frame Rate and Motion

• Cine typically 15–30 fps for coronary work; lower rates acceptable for peripheral runoff when dose is a concern
• Breath-hold instructions for abdominal aortography when patient able
• Immobilize the limb for peripheral shots; motion mimics stenosis

Collimation and Dose

• Tight collimators to vessels of interest; adjust with each projection change
• Use fluoro roadmap before cine to confirm position
• Track DAP and RAK; peripheral long-leg runs can accumulate skin dose at one entry point—vary angulation when repeating

Hemodynamic Monitoring During Cine

Contrast injections transiently affect hemodynamics. The RCIS watches ECG, pressure, and SpO₂ during root injections (risk of bradycardia, hypotension, ventricular arrhythmia) and notifies the physician of ST changes or pressure drift on the wire.

Foundational Image Interpretation

RCIS scope includes recognizing patterns, not issuing final diagnoses. Still, you must interpret enough to anticipate needs.

Coronary Interpretation Basics

• Stenosis severity: Angiographic percent diameter reduction (visual estimate vs quantitative analysis)
• Lesion morphology: Calcification, thrombus, ulceration, bifurcation involvement
• TIMI flow grade (0–3): Antegrade perfusion after intervention—exam favorite
• Complications: Dissection flap, no-reflow, air embolism (dark filling defect), catheter-induced spasm

Dominance and anomalies: Circumflex or RCA origin anomalies change projection strategy; alert the team if an injection fills an unexpected course.

Peripheral Interpretation Basics

• Stenosis vs occlusion: Length, calcification, collateral filling
• Inflow disease: Aorto-iliac disease limits femoral intervention success
• Runoff vessels: Single-vessel vs no-vessel runoff predicts wound healing and CLI outcomes
• Aneurysm: Sac diameter, neck, thrombus, endoleak after EVAR (post-procedure surveillance imaging)

Tibioperoneal trunk disease and infrapopliteal occlusions require high-quality lateral and AP views; if runoff is poor, the physician may need additional oblique angles—the RCIS prepares before contrast is wasted.

Artifacts and Troubleshooting

When images are nondiagnostic, state clearly why (motion, timing, field) so the physician can correct—not simply "bad picture."

Documentation and Communication

Archive key projections per lab protocol (diagnostic and post-PCI). Note contrast volume, fluoro time, and RAK in the record. Verbal closed-loop communication examples:

• "Cine started—RAO cranial, LAD mid in field."
• "Runoff to ankles complete; mild SFA disease, tibials patent."
• "Possible edge dissection at 3 o'clock on stent; storing loop for review."

Structured communication prevents repeated doses and speeds intervention.

Exam Focus Checklist

• Cardiac views: RAO/LAO ± cranial/caudal; know what each opens
• Peripheral runoff: aorto-iliac → femoral → tibials; timing and field length
• Acquisition: collimation, frame rate, contrast volume, detector proximity
• Interpret basics: dominance, TIMI flow, inflow/runoff, dissection
• Artifacts: motion, dilution, venous overlay, bubbles

Strong acquisition technique produces images physicians can trust. Foundational interpretation lets the RCIS stay one step ahead—safer cases, lower dose, and smoother lab flow.