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Radiografía de Tórax: Evaluación Básica Inicial

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Four-Pattern Approach

Robin Smithuis

Radiology Department of the Rijnland Hospital, Leiderdorp, the Netherlands

Publicationdate
On a chest x-ray lung abnormalities will either present as areas of increased density or as areas of decreased density.

Lung abnormalities with an increased density - also called opacities - are the most common.
A practical approach is to divide these into four patterns:

1. Consolidation

2. Interstitial

3. Nodules or masses

4. Atelectasis

In this article we will focus on this four-pattern approach.
At the end we will also discuss diseases that present as areas of decreased density.

Whenever you see an area of increased density within the lung, it must be the result of one of these four patterns.

1. Consolidation - any pathologic process that fills the alveoli with fluid, pus, blood, cells (including tumor cells) or other substances resulting in lobar, diffuse or multifocal ill-defined opacities.

2. Interstitial - involvement of the supporting tissue of the lung parenchyma resulting in fine or coarse reticular opacities or small nodules.

3. Nodule or mass - any space occupying lesion either solitary or multiple.

4. Atelectasis - collapse of a part of the lung due to a decrease in the amount of air in the alveoli resulting in volume loss and increased density.

Here are the most common examples of these four patterns on a chest x-ray (click image to enlarge).

Consolidation

Lobar consolidation

Diffuse consolidation

Multifocal ill-defined consolidations

Interstitial

Reticular interstitial opacities

Fine Nodular interstitial opacities

Nodule or mass

Solitary Pulmonary Nodule

Multiple Masses

Atelectasis

You have to realize that it is not always possible to divide lung abnormalities into one of these four patterns, but that should not be a problem.

Sometimes you are confronted with an abnormality that looks like a mass, but it could also be a consolidation.
Just do the work-up of both the differential diagnosis of masses and consolidation.

In such a case information from clinical data, old films or follow-up films and CT-scan will usually solve the problem.
Finally in some cases only biopsy will provide a diagnosis.

Solitary Pulmonary Nodule

Click here for more detailed information about Solitary Pulmonary Nodule

A solitary pulmonary nodule or SPN is defined as a discrete, well-marginated, rounded opacity less than or equal to 3 cm in diameter.
It has to be completely surrounded by lung parenchyma, does not touch the hilum or mediastinum and is not associated with adenopathy, atelectasis or pleural effusion.

The differential diagnosis of SPN is basically the same as of a mass except that the chance of malignancy increases with the size of the lesion.
Lesions smaller than 3 cm, i.e. SPN's are most commonly benign granulomas, while lesions larger than 3 cm are treated as malignancies until proven otherwise and are called masses.

The tabel is adapted from chest x-ray - a survival guide.

In lesions that do not respond to antibiotics, probably the most important non-invasive diagnostic tool is nowadays the PET-CT.

PET-CT can detect malignancy in focal pulmonary lesions of greater than 1 cm with a sensitivity of about 97% and a specificity of 78%.
False-positive findings in the lung are seen in granulomatous disease and rheumatoid disease.
False negatives are seen in low grade malignant tumors like carcinoid and alveolar cell carcinoma and lesions of less than 1 cm.

Fleischner Society recommendations for follow-up of nodules

Previous chest radiographs should be reviewed to determine if the lesion has been stable over 2 years.
If so, no further follow up is necessary, with the exception of pure ground-glass lesions on CT scans, which can be slower growing.

For lesions with a benign pattern of calcification, further testing is not necessary.

Management of indeterminate lesions greater than 8-10 mm depends on clinical probability of malignancy, as follows:

Low probability: Serial CT scanning at 3, 6, 12, and 24 months

Intermediate probability: PET-CT, contrast-enhanced CT, transthoracic needle aspiration and/or transbronchial needle aspiration (TBNA)

High probability: Surgical resection

Any unequivocal growth noted during follow up means that a definitive tissue diagnosis is needed.

Multiple masses

The differential diagnostic list of multiple masses is very long.
The most important diagnoses are listed in the table.

Sometimes it is difficult to differentiate multifocal consolidations from masses.

Metastases
Metastases are the most common cause of multiple pulmonary masses.
Usually they vary in size and are well-defined.
They predominate in the lower lobes and in the subpleural region.

HRCT will demonstrate the random distribution unlike other diseases that have a perilymphatic or centrilobular distribution.

The images show a renal cell carcinoma that has invaded the inferior vena cava with subsequent spread of disease to the lungs.

Here another patient with widespread pulmonary metastases of a cancer, that was located in the tongue.

Mucoid impaction

Mucus plugs or mucoid impaction can mimick the appearance of lung nodules or a mass.
Sometimes differentiating mucus impaction from a lungcancer can be difficult.

Mucoid impaction is commonly seen in patients with bronchiectasis, as in cystic fibrosis (CF) and allergic bronchopulmonary aspergillosis (ABPA).
ABPA is a hypersensitivity disorder induced by Aspergillus, that occurs in patients with asthma or CF.
It is also seen in bronchial obstruction caused by an obstructing tumor or bronchial atresia.

In this case there are some mass-like structures in the right lung.
CT demonstrated bronchiectasis with mucoid impaction.

A more common presentation of mucoid impaction in seen here.

This is the typical 'finger-in-glove' appearance of mucoid impaction.

The mucus in the dilated bronchi looks like the fingers in a glove.

Bronchial atresia

Bronchial atresia is a congenital abnormality resulting from interruption of a bronchus with associated peripheral mucus impaction and associated hyperinflation of the obstructed lung (10).
The hyperinflation of the affected lungsegment is caused by collateral ventilation through the pores of Kohn.

The characteristic finding is a hyperlucent area of the lung surrounding a branching or nodular opacity that extends from the hilum.

Notice the central mass surrounded by hyperlucent lung (blue arrow).

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Radiology Department of the Rijnland Hospital, Leiderdorp, the Netherlands Publicationdate On a chest x-ray lung abnormalities will either present as areas of increased density or as areas of decreased density. Lung abnormalities with an increased density - also called opacities - are the most common.

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Es el estudio radiologico mas comunmente solicitado que permite evaluar las estructuras del torax(corazon, pulmones, vias respiratorias y esqueleto axial) a traves del estudio de las imagenes.

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INTRODUCCION AL DIAGNOSTICO POR IMAGENES - TORAX

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INTRODUCCION AL DIAGNOSTICO POR IMAGENES - TORAX

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INTRODUCCION AL DIAGNOSTICO POR IMAGENES

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INTRODUCCION AL DIAGNOSTICO POR IMAGENES

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Introducción en Imágenes de Tórax y cardiovascular I

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Radiografía de Tórax: Evaluación Básica Inicial

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Patrones Radiológicos Básicos de la Radiografía de Tórax I

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Clase 1:  Semiología Radiológica del Tórax

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5 casos clínicos de radiografía de tórax

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A partir del minuto 20