Protocolling Imaging Studies

Protocolling Imaging Studies

Selects appropriate imaging protocols based on clinical indication and patient factors.

Why This Skill Exists

Protocol selection is one of the most impactful decisions in radiology — an incorrectly protocolled study can miss the diagnosis entirely, requiring repeat imaging with additional radiation exposure, contrast administration, and cost. The ACR Appropriateness Criteria provide evidence-based guidelines for selecting the right imaging modality and protocol for over 200 clinical scenarios. Radiologists are responsible for reviewing orders, verifying clinical indications, selecting contrast type and phase timing, and ensuring patient safety considerations (allergy history, renal function, pregnancy) are addressed before the study is performed.

Protocol errors — wrong phase, wrong contrast agent, wrong body region — are among the most common "never events" in radiology departments. CMS reimbursement increasingly ties to appropriate-use criteria (AUC) through the Protecting Access to Medicare Act (PAMA), requiring clinical decision support consultation for advanced imaging. This skill ensures that every protocol decision is evidence-based, patient-safe, and clinically optimized.

Checkpoint A: Pre-Draft Intake (Mandatory)

1. What is the clinical indication and specific clinical question? (Default: Obtain from requisition — never protocol without this)
2. What modality was ordered? (Default: Verify modality matches indication per ACR Appropriateness Criteria)
3. Does the patient have a contrast allergy? (Default: No — verify in EMR)
4. What is the patient's renal function (eGFR)? (Default: Check within 30 days for IV contrast)
5. Is the patient pregnant or possibly pregnant? (Default: No — verify per institutional policy)
6. Does the patient have implantable devices (pacemaker, stimulator, metallic implant)? (Default: No — verify for MRI)
7. Patient weight and body habitus? (Default: Standard — adjust if >300 lbs or pediatric)
8. Are there prior studies that should inform protocol selection? (Default: Review prior imaging)

Documents to Request

• Requisition with clinical indication and ICD-10 codes
• ACR Appropriateness Criteria for the clinical scenario
• Patient allergy history (contrast-specific)
• Recent lab values: eGFR/creatinine, TSH (if thyroid-related), coagulation (if intervention)
• MRI safety screening form (for MRI studies)
• Prior imaging reports to determine appropriate comparison protocol
• Institutional protocol library for scanner-specific parameters

Step 1: Verify Modality Appropriateness

Before protocolling, confirm the ordered modality is appropriate per ACR Appropriateness Criteria.

If the ordered modality is rated "Usually NOT Appropriate," contact the ordering provider to discuss alternatives.

Step 2: Contrast Decision Matrix

IV Iodinated Contrast (CT)

IV Gadolinium Contrast (MRI)

Oral Contrast

Step 3: Phase Selection and Timing

CT Phase Timing (Post-Injection)

MRI Sequences by Clinical Question

Step 4: Patient-Specific Protocol Modifications

Step 5: Document the Protocol Decision

The protocol order must include:

1. Modality and body region — e.g., "CT abdomen and pelvis"
2. Contrast — type, dose, route, timing, premedication if applicable
3. Phases — specific acquisitions with timing
4. Special instructions — reformats, thin-slice reconstructions, breath-hold coaching
5. Safety clearance — allergy status, renal function, pregnancy status, MRI safety screening
6. Clinical justification — per ACR Appropriateness Criteria rating
7. Protocol modification rationale — if deviation from standard

Checkpoint B: Post-Draft Alignment (Mandatory)

1. Does the protocol match the clinical question per ACR Appropriateness Criteria?
2. Is contrast safety verified (allergy, renal function, pregnancy)?
3. Are the correct phases included for the clinical indication?
4. Are patient-specific modifications documented?
5. Will the protocol detect the suspected pathology if present?

Quality Audit

• Clinical indication is confirmed and documented before protocolling
• Modality selection aligns with ACR Appropriateness Criteria
• Contrast allergy history is verified and premedication ordered if needed
• Renal function (eGFR) is documented within acceptable time window
• Pregnancy status is verified per institutional policy
• MRI safety screening is completed for MRI studies
• Phase timing matches the clinical question
• Contrast dose is weight-appropriate (especially pediatric)
• Oral contrast type and timing are specified when applicable
• Protocol modifications for body habitus, hardware, or devices are documented
• Prior imaging is reviewed to ensure protocol consistency for comparison
• Radiation dose optimization (kVp, mAs reduction) is applied per ALARA
• Protocol is recorded in the institutional protocol tracking system

Guidelines

1. Never protocol a study without reviewing the clinical indication — the indication determines the protocol, not the ordered CPT code.
2. Apply ACR Appropriateness Criteria to validate modality selection; contact the ordering provider if the ordered study is rated "Usually NOT Appropriate."
3. Use the lowest radiation dose that answers the clinical question (ALARA principle); reduce kVp from 120 to 100 for thin patients on CT.
4. For liver mass characterization in cirrhosis, ensure late arterial phase timing (35–40 seconds) — standard portal venous timing will miss arterial-phase hyperenhancement.
5. Premedication for contrast allergy requires 13 hours lead time; if emergent, use the accelerated protocol (methylprednisolone 40 mg IV q4h × 2 doses + diphenhydramine 50 mg IV).
6. Gadolinium in pregnancy requires documented risk-benefit discussion and should only be administered if the information is critical to maternal/fetal care.
7. When the ordered study does not match the clinical question, recommend the appropriate study — this is a core radiologist responsibility under PAMA/AUC requirements.