Toronto Notes

Reticular patterns: Thin, well-defined linear densities, often in net-like or “honeycomb” arrangement.

Reticulonodular patterns: A combination of reticular and nodular patterns.

No image available

Nodular patterns: Multiple, discrete, nodular densities, <5 mm diameter.
Right image depicts a close up of the pathology.

Kerly lines result fomr thickened connective tissue planes occurring as a result of pulmonary edema or carcinomatosis.

Kerly A Lines: Radiate towards hila in mid- and upper-lung zones, 3-4 cm long, smaller than vascular markings (not useful)
Kerly B Lines: Horizontal, <2 cm long an d1 mm thick, at periphery of lung, reach lung edge (very useful)
Kerly C Lines: Thickened interlobular septa

Interstitial disease is a pathological process involving the interlobular connective tissue (i.e. scaffolding of the lung).

Differential diagnosis of interstitial disease includes:

1. Pulmonary edema (which can move into the alveoli)
2. Collagen disease (fibrosis)
3. Sarcoidosis
4. Pneumoconiosis
5. Metastatic disease (from the lymphatics)
6. Inflammatory conditions (viral/interstitial pneumonia)

Airspace disease (i.e. consolidation) refers to a pathological process primarily in the alveoli. Differential diagnosis of consolidation includes:

1. Pus (pneumonia)
2. Blood hemorrhage
3. Cells (lung cancer or lymphoma)
4. Protein (alveolar proteinosis)
5. Fluid (pulmonary edema from interstitium)

Airways are not normally seen in a normal chest radiograph because they are an air structure within an aerated lung. When the aerated lung opacifies, the bronchii become visualized because of the surrounding contrast effect. These are called air bronchograms and are virtually diagnostic of consolidation.