A chest radiograph is frequently used in diagnosis.
In people with mild disease, imaging is needed only in those with potential complications, those not having improved with treatment, or those in which the cause is uncertain.
If a person is sufficiently sick to require hospitalization, a chest radiograph is recommended.
Findings do not always match the severity of disease and do not reliably separate between bacterial infection and viral infection.

X-ray presentations of pneumonia may be classified as lobar pneumonia, bronchopneumonia, lobular pneumonia, and interstitial pneumonia.
Bacterial, community-acquired pneumonia classically show lung consolidation of one lung segmental lobe, which is known as lobar pneumonia.
However, findings may vary, and other patterns are common in other types of pneumonia.
Aspiration pneumonia may present with bilateral opacities primarily in the bases of the lungs and on the right side.
Radiographs of viral pneumonia may appear normal, appear hyper-inflated, have bilateral patchy areas, or present similar to bacterial pneumonia with lobar consolidation.
Radiologic findings may not be present in the early stages of the disease, especially in the presence of dehydration, or may be difficult to be interpreted in the obese or those with a history of lung disease.
Complications such as pleural effusion may also be found on chest radiographs.
Laterolateral chest radiograph can increase the diagnostic accuracy of lung consolidation and pleural effusion.

A CT scan can give additional information in indeterminate cases.
CT scan can also provide more details in those with an unclear chest radiograph (for example occult pneumonia in chronic obstructive pulmonary disease) and is able to exclude pulmonary embolism and fungal pneumonia and detecting lung abscess in those who are not responding to treatments.
However, CT scan is more expensive, has a higher dose of radiation, and cannot be done at bedside.

Lung ultrasound may also be useful in helping to make the diagnosis.
Ultrasound is radiation free and can be done at bedside.
However, ultrasound requires specific skills to operate the machine and interpret the findings.
It may be more accurate than chest X-ray.
A chest radiograph is frequently used in diagnosis. In people with mild disease, imaging is needed only in those with potential complications, those not having improved with treatment, or those in which the cause is uncertain. If a person is sufficiently sick to require hospitalization, a chest radiograph is recommended. Findings do not always match the severity of disease and do not reliably separate between bacterial infection and viral infection.
X-ray presentations of pneumonia may be classified as lobar pneumonia, bronchopneumonia, lobular pneumonia, and interstitial pneumonia. Bacterial, community-acquired pneumonia classically show lung consolidation of one lung segmental lobe, which is known as lobar pneumonia. However, findings may vary, and other patterns are common in other types of pneumonia. Aspiration pneumonia may present with bilateral opacities primarily in the bases of the lungs and on the right side. Radiographs of viral pneumonia may appear normal, appear hyper-inflated, have bilateral patchy areas, or present similar to bacterial pneumonia with lobar consolidation. Radiologic findings may not be present in the early stages of the disease, especially in the presence of dehydration, or may be difficult to be interpreted in the obese or those with a history of lung disease. Complications such as pleural effusion may also be found on chest radiographs. Laterolateral chest radiograph can increase the diagnostic accuracy of lung consolidation and pleural effusion.
A CT scan can give additional information in indeterminate cases. CT scan can also provide more details in those with an unclear chest radiograph (for example occult pneumonia in chronic obstructive pulmonary disease) and is able to exclude pulmonary embolism and fungal pneumonia and detecting lung abscess in those who are not responding to treatments. However, CT scan is more expensive, has a higher dose of radiation, and cannot be done at bedside.
Lung ultrasound may also be useful in helping to make the diagnosis. Ultrasound is radiation free and can be done at bedside. However, ultrasound requires specific skills to operate the machine and interpret the findings. It may be more accurate than chest X-ray.
Pneumonia