Adrenal Incidentaloma
Adrenal incidentalomas are found in up to 5% of abdominal CTs. The two key questions are: is it benign (lipid-rich adenoma) and is it functional? RadCall covers the Hounsfield unit thresholds, washout protocol, and endocrine workup indications.
- ≤10 HU unenhanced — lipid-rich adenoma, no follow-up
- 11–20 HU — adrenal washout protocol CT
- Absolute washout ≥60% — adenoma
- Relative washout ≥40% — adenoma
- Size criteria — >4 cm warrants resection consideration
- Functional workup — pheochromocytoma, Conn, Cushing
- Pheochromocytoma — biochemical screening before any procedure
- Malignant features — irregular, heterogeneous, >4 cm
Pulmonary Nodule — Fleischner Guidelines
The Fleischner Society 2017 guidelines stratify solid pulmonary nodule follow-up by size and risk. The ACR Lung-RADS system applies to lung cancer screening CT (low-dose CT). RadCall covers both systems including subsolid (ground-glass and part-solid) nodule pathways.
- Solid nodule <6 mm — no follow-up (low risk) or optional 12 mo
- Solid nodule 6–8 mm — 6–12 month CT follow-up
- Solid nodule >8 mm — 3-month CT, PET-CT, or biopsy
- Ground-glass nodule — 5-year follow-up if persistent >6 mm
- Part-solid nodule — solid component size determines risk
- Lung-RADS 1 — negative screen; Lung-RADS 4 — suspicious
- High-risk factors — smoking, prior malignancy, upper lobe
- Multiple nodules — most suspicious nodule drives management
Renal Mass — Bosniak Classification
The updated Bosniak 2019 classification categorizes renal cystic masses by CT and MRI features. Solid renal masses use separate ACR white paper criteria. RadCall covers each Bosniak category's malignancy risk and follow-up recommendations.
- Bosniak I — simple cyst, benign, no follow-up
- Bosniak II — few thin septa, benign, no follow-up
- Bosniak IIF — multiple thin septa, surveillance at 6 mo then annual
- Bosniak III — thickened/irregular septa, ~50% malignant, surgical
- Bosniak IV — solid enhancing component, >80% malignant
- Solid renal mass — clear cell vs papillary vs chromophobe
- Angiomyolipoma — macroscopic fat, HU threshold
- Oncocytoma vs RCC — MRI features, spoke-wheel pattern
Liver Lesion — LI-RADS
LI-RADS (Liver Imaging Reporting and Data System) applies to patients at risk for hepatocellular carcinoma (cirrhosis, chronic HBV). Categories range from LR-1 (definitely benign) to LR-5 (definitely HCC) with specific imaging criteria for arterial phase hyperenhancement, washout, and capsule appearance.
- LR-1 — definitely benign (cyst, hemangioma)
- LR-3 — intermediate probability HCC
- LR-4 — probably HCC, biopsy or treatment discussion
- LR-5 — definitely HCC, treatment without biopsy
- APHE — arterial phase hyperenhancement, key HCC feature
- Washout appearance — portal/delayed phase
- Enhancing capsule — LR-5 ancillary feature
- LR-M — probably or definitely malignant, not HCC-specific
Thyroid Nodule — TI-RADS
- ACR TI-RADS — point-based scoring system
- Composition — cystic, mixed, solid (higher points)
- Echogenicity — hyperechoic to very hypoechoic
- Shape — wider-than-tall vs taller-than-wide (suspicious)
- Margin — smooth vs lobulated vs irregular vs extrathyroidal
- Echogenic foci — comet tail vs macrocalcification vs microcalcification
- FNA thresholds — by TI-RADS category and size
- TR5 — highly suspicious, FNA ≥1 cm