Structures CT scan interpretation by body region with standardized measurement and comparison techniques. Use when interpreting CT studies, creating CT reports, or documenting cross-sectional findings.
Structures CT scan interpretation by body region with standardized measurement and comparison techniques.
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.
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 |
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).
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 |