reporting-ct-scans

# Reporting CT Scans

Structures CT scan interpretation by body region with standardized measurement and comparison techniques.

## Why This Skill Exists

CT is the workhorse of cross-sectional imaging, with over 80 million scans performed annually in the United States alone. CT reports drive critical clinical decisions—surgery timing, chemotherapy response, trauma triage, and emergency management. Inconsistent reporting leads to missed findings, unnecessary repeat imaging, and delayed diagnoses. The ACR Practice Parameter for Communication of Diagnostic Imaging Findings requires that CT reports be clear, actionable, and structured to minimize ambiguity. RADLEX-standardized terminology and structured reporting templates endorsed by the RSNA reduce inter-reader variability and improve downstream care coordination.

Failure to compare with prior studies, omission of incidental findings, and vague language (e.g., "cannot exclude") are among the top drivers of radiology malpractice claims. This skill enforces systematic body-region review, standardized measurement techniques, and explicit follow-up recommendations aligned with ACR Incidental Findings Committee white papers.

---

## Checkpoint A: Pre-Draft Intake (Mandatory)

1. **What body region is being evaluated?** (Default: Chest/Abdomen/Pelvis — specify exact order)
2. **Was IV contrast administered? If yes, what phase(s)?** (Default: With contrast, portal venous phase)
3. **Was oral contrast administered?** (Default: No)
4. **What is the clinical indication?** (Default: Replace with actual ICD-10 and clinical question)
5. **Are prior CT or cross-sectional studies available for comparison?** (Default: No priors)
6. **Is the patient on an oncologic treatment protocol requiring RECIST measurement?** (Default: No)
7. **Is there a known contrast allergy or renal impairment?** (Default: No — verify if contrast was given)
8. **Is this a trauma/stroke protocol requiring specialized reporting?** (Default: Routine diagnostic)

### Documents to Request

- CT images in all acquired phases (axial source, coronal/sagittal reformats)
- Requisition with clinical indication and relevant ICD-10 codes
- Prior cross-sectional imaging (CT, MRI) for comparison
- Relevant lab values (creatinine/eGFR if contrast administered)
- Surgical/procedural history pertinent to anatomy
- Oncology staging notes if tumor measurement is requested

---

## Step 1: Technical Assessment

Document acquisition parameters and any limitations affecting interpretation.

| Parameter | Standard | Action if Suboptimal |
|-----------|----------|---------------------|
| **Contrast timing** | Arterial (25–35s), portal venous (60–70s), delayed (3–5 min) | Note phase and whether timing was adequate |
| **Slice thickness** | ≤3 mm for chest; ≤5 mm for abdomen | Note if thick slices limit small-lesion detection |
| **Coverage** | Full anatomy per ordered region | Document excluded regions |
| **Motion artifact** | Minimal | Note "respiratory/cardiac motion artifact limits evaluation of [region]" |
| **Oral contrast** | Opacified bowel loops (abdomen/pelvis) | Note "non-opacified bowel limits mucosal evaluation" |
| **Reformats** | Coronal, sagittal available | Note if reformats are missing |

---

## Step 2: Systematic Review by Body Region

### CT Chest
- **Lungs**: Evaluate each lobe; nodules by Fleischner 2017 or Lung-RADS; ground-glass opacity, consolidation, interstitial disease pattern
- **Airways**: Trachea, mainstem bronchi, segmental patency
- **Mediastinum**: Lymph nodes by station (measure short axis; >10 mm = enlarged); thymic pathology; esophagus
- **Pleura**: Effusion (measure depth), pneumothorax, thickening, calcification
- **Heart/Pericardium**: Cardiomegaly, pericardial effusion, coronary calcification
- **Chest wall**: Rib fractures, soft-tissue masses, breast tissue
- **Upper abdomen** (included in chest CT): Liver dome, adrenals, upper kidneys

### CT Abdomen/Pelvis
- **Liver**: Size, attenuation, focal lesions (measure and characterize per LI-RADS if cirrhosis), vascular patency
- **Gallbladder/Biliary**: Wall thickness, stones, duct dilatation (CBD >7 mm, >10 mm post-cholecystectomy)
- **Pancreas**: Size, duct dilatation (>3 mm), masses, peripancreatic fat stranding
- **Spleen**: Size (<13 cm craniocaudal), focal lesions
- **Adrenals**: Nodules (<10 HU = lipid-rich adenoma; >10 HU requires washout study)
- **Kidneys**: Size, cortical thickness, stones (measure), hydronephrosis grade, masses (Bosniak classification for cysts)
- **GI tract**: Wall thickening, diverticulitis, appendicitis, obstruction (transition point)
- **Mesentery/Retroperitoneum**: Lymph nodes (short axis >10 mm), fluid, fat stranding
- **Pelvis**: Bladder, uterus/ovaries or prostate/seminal vesicles, pelvic lymph nodes
- **Vascular**: Aortic diameter, aneurysm, dissection, PE (if CT angiography)
- **Bones**: Lytic/blastic lesions, fractures, degenerative changes
- **Soft tissues**: Abdominal wall hernias, subcutaneous findings

---

## Step 3: Measurement Standards

All measurements must be reproducible and follow standardized techniques.

| Structure | How to Measure | Normal Reference |
|-----------|---------------|-----------------|
| Lymph nodes | Short-axis diameter | <10 mm (most stations) |
| Aorta | Outer wall to outer wall, perpendicular to flow | <3.0 cm infrarenal; <3.5 cm suprarenal |
| Common bile duct | Internal diameter | ≤7 mm (<10 mm post-cholecystectomy) |
| Pancreatic duct | Internal diameter | ≤3 mm body; ≤1.5 mm tail |
| Renal mass | Three dimensions (L × W × H) | Per Bosniak classification |
| Adrenal nodule | Long-axis diameter + attenuation (HU) | Per ACR Incidental Findings recs |
| Pulmonary nodule | Average of long and short axis | Per Fleischner 2017 |

For oncologic studies requiring RECIST 1.1, document target lesion measurements in a dedicated table (see measuring-tumor-response skill).

---

## Step 4: Report Structure — ACR-Compliant Format

### Header
- Patient demographics, study date/time, accession number
- Examination: specific CPT description (e.g., "CT abdomen and pelvis with IV contrast")
- Clinical indication with ICD-10

### Comparison
- List all prior relevant studies with dates and modality

### Technique
- Scanner type (if relevant), slice thickness, contrast agent/dose/rate, phases acquired
- Oral contrast administration (type, timing)
- Dose information (CTDIvol, DLP) if available

### Findings
- Organize by organ system within the body region
- Each finding: location → description → measurement → comparison to prior → significance
- Use specific attenuation values (HU) when characterizing lesions

### Impression
- Numbered, prioritized by clinical significance
- Address the clinical question directly in item #1
- Include ACR Incidental Findings Committee recommendations for incidentalomas
- Specify follow-up modality, timing, and contrast requirement

---

## Step 5: Incidental Findings Management

Apply ACR Incidental Findings Committee white paper recommendations:

| Finding | Size Threshold | Recommendation |
|---------|---------------|----------------|
| Adrenal nodule | >4 cm or suspicious features | Surgical consultation |
| Adrenal nodule | 1–4 cm, >10 HU | Dedicated adrenal CT washout or MRI |
| Renal cyst (Bosniak I/II) | Any | No follow-up |
| Renal cyst (Bosniak IIF) | Any | Follow-up at 6, 12, 24 months |
| Hepatic cyst (simple) | Any | No follow-up |
| Thyroid nodule on CT | >1.5 cm or suspicious | Dedicated thyroid ultrasound |
| Pulmonary nodule | Per Fleischner | See chest radiograph skill |
| Pancreatic cyst | >1.5 cm or duct communication | GI/surgical consult + MRI |

---

## Checkpoint B: Post-Draft Alignment (Mandatory)

1. Does the report address the specific clinical question in the impression?
2. Are all incidental findings managed per ACR white paper recommendations?
3. Are measurements reproducible and in the correct axis?
4. Is comparison with prior studies documented with specific dates?
5. Are critical findings communicated and documented per Joint Commission?

---

## Quality Audit

- [ ] Technique section includes contrast type, dose, and phases
- [ ] Each organ system is explicitly evaluated (no region skipped)
- [ ] All measurable lesions include dimensions in millimeters
- [ ] Lymph nodes are measured by short-axis diameter
- [ ] Incidental findings include specific follow-up per ACR recommendations
- [ ] Aortic measurements use outer-wall-to-outer-wall technique
- [ ] Adrenal nodules include attenuation values
- [ ] Prior comparison studies are listed with exact dates
- [ ] Impression items are numbered with most significant first
- [ ] Critical findings include communication documentation
- [ ] Bosniak classification is applied to renal cystic lesions when appropriate
- [ ] Report avoids vague phrases like "clinical correlation recommended" without specific guidance
- [ ] Dose information (DLP) is documented when available
- [ ] Laterality is explicit for every finding

---

## Guidelines

1. Always specify contrast phase(s) — findings differ dramatically between arterial, venous, and delayed phases.
2. Apply the ACR Incidental Findings Committee recommendations for every incidentaloma; never leave an incidental finding without a management plan.
3. Use Hounsfield unit values when characterizing adrenal, renal, and hepatic lesions — qualitative descriptors alone are insufficient.
4. Measure lymph nodes by short-axis diameter; long-axis measurements overestimate pathologic enlargement.
5. For oncologic patients, state whether RECIST 1.1 measurements are included and reference the dedicated tumor-measurement report.
6. Document dose metrics (CTDIvol and DLP) to support institutional dose-tracking and ALARA compliance.
7. When findings are equivocal, recommend a specific next step (e.g., "dedicated MRI with hepatocyte-specific contrast") rather than "clinical correlation."