The Normal CXRThe Normal CXRByBy

Dr. Hayam YousifDr. Hayam YousifRadiologistRadiologist

Muhammad Jalal Muhammad Jalal AbdulsamadAbdulsamad

The Plain FilmThe Plain Film

• The PA viewThe PA view

• Exposure is made on full inspirationExposure is made on full inspiration

PA filmPA film

PA viewPA view

• The neural arches are The neural arches are visualisedvisualised

AP viewAP view

• The posterior chest wall The posterior chest wall is well shownis well shown

• The scapulae overlie the The scapulae overlie the upper lungs and the upper lungs and the clavicles are projected clavicles are projected more cranially over the more cranially over the apicesapices

• The disc spaces of the The disc spaces of the lower cervical spine are lower cervical spine are more clearly seenmore clearly seen

AP film PA filmAP film PA film

AP & LATERALAP & LATERAL

PA

Viewing the PA FilmViewing the PA Film

Request formRequest formNameName

AgeAge

DateDate

SexSex

Clinical informationClinical information

Viewing the PA FilmViewing the PA Film

Technical aspectsTechnical aspectsCenteringCentering

PenetrationPenetration the vertebral body and spaces the vertebral body and spaces should be just visible through the cardiac should be just visible through the cardiac shadow.shadow.

Degree of inspirationDegree of inspiration on full inspiration the on full inspiration the anterior ends of 6anterior ends of 6thth ribs or the posterior ends of ribs or the posterior ends of 1010thth are above the right hemidiaphragm. are above the right hemidiaphragm.

Trachea Trachea it is in the midline then deviates it is in the midline then deviates slightly to the right side at level of aortic slightly to the right side at level of aortic knuckleknuckle

NarrowingNarrowing

DisplacementDisplacement

Intraluminal lesionIntraluminal lesion

The mediastinum and heartThe mediastinum and heartThe central dense shadow seen on PA CXRThe central dense shadow seen on PA CXRcomprises the mediastinum, heart, spine and comprises the mediastinum, heart, spine and

sternumsternumThe cardiac shadow lies to the left of the midline The cardiac shadow lies to the left of the midline

and 1/3 to the right although it is quite variable and 1/3 to the right although it is quite variable The transverse cardiac diameter normal for female The transverse cardiac diameter normal for female

< 14.5 cm and for males < 15.5 cm.< 14.5 cm and for males < 15.5 cm.The normal cardiothoracic ratio is < 50% on PA The normal cardiothoracic ratio is < 50% on PA

film and < 60% in AP film.film and < 60% in AP film.An increase in excess of 1.5 cm in the transverse An increase in excess of 1.5 cm in the transverse

diameter on comparable serial films is diameter on comparable serial films is significant.significant.

All borders of the heart and mediastinum All borders of the heart and mediastinum should be clearly definedshould be clearly defined

In babies and young children the normal In babies and young children the normal thymus is a triangular sail shaped thymus is a triangular sail shaped structure with well defined borders which structure with well defined borders which may be wavy.may be wavy.

Vessels

Aortic Arch

Pulmonary Artery

Left Atrium

Left Ventricle

Inferior Vena Cava

Right Atrium

Ascending Aorta

Superior Vena Cava

Descending Aorta

Aortic Knob/Arch

Ascending Aorta

Right Ventricle

Inferior Vena Cava

Left Ventricle

Left Atrium

DiaphragmDiaphragmIn most patients the right hemidiaphragm is In most patients the right hemidiaphragm is

higher than the left. May lie at the same higher than the left. May lie at the same level, and in small percentage the left side level, and in small percentage the left side is higher.is higher.

A difference of > 3 cm in height is significantA difference of > 3 cm in height is significant

Loss of outline indicates that the adjacent Loss of outline indicates that the adjacent tissue does not contain air.tissue does not contain air.

The fissuresThe fissuresThe main fissuresThe main fissuresThe horizontal fissure is seen often incompletely The horizontal fissure is seen often incompletely

on PA filmon PA filmThe oblique fissures are seen on lateral film The oblique fissures are seen on lateral film

commence posteriorly at the level of T4 or T5 commence posteriorly at the level of T4 or T5 passing through the hilum. The left is steeper passing through the hilum. The left is steeper and finishes 5cm behind the anterior and finishes 5cm behind the anterior costophrenic angle, where as the right ends just costophrenic angle, where as the right ends just behind the angle.behind the angle.

Accessory fissuresAccessory fissures, the azygos fissure is , the azygos fissure is comma shaped and nearly always right sided. comma shaped and nearly always right sided.

Horizontal Fissure

Right Oblique Fissure

Left Oblique Fissure

LUL

LLL

RUL

RML

RLL

Azygos Azygos fissurefissure

Costophrenic anglesCostophrenic angles

The normal costophrenic angles are acuteThe normal costophrenic angles are acute

The lungsThe lungsBy comparing the lungs, areas of abnormal By comparing the lungs, areas of abnormal

translucency or uneven distribution of lung translucency or uneven distribution of lung markings are more easily detected.markings are more easily detected.

The hilaThe hilaIn 97% of subjects the left hilum is higher In 97% of subjects the left hilum is higher

than the right. The hila should be of equal than the right. The hila should be of equal density and similar size with clearly density and similar size with clearly defined concave lateral borders.defined concave lateral borders.

The lower lobe vessels are larger than those The lower lobe vessels are larger than those of the upper lobes in erect position.of the upper lobes in erect position.

The right main bronchus is shorter, steeper The right main bronchus is shorter, steeper and wider than the left.and wider than the left.

Below the diaghragmBelow the diaghragm

PneumoperitoneumPneumoperitoneum

Dilated bowelDilated bowel

AbscessAbscess

Calcified lesion Calcified lesion

Chilaiditi’s syndromeChilaiditi’s syndrome

Soft tissueSoft tissue

Chest wallChest wall: breast shadow, skin folds, : breast shadow, skin folds, shadow of sternomastoid muscleshadow of sternomastoid muscle

ShouldersShoulders

Lower neckLower neck

The bonesThe bones

SternumSternum

ClaviclesClavicles

ScapulaeScapulae

RibsRibs

SpineSpine

Image credit: Curry International Tuberculosis Center, University of California, San Francisco 22

Viewing the lateral filmViewing the lateral film

• Routinely the left side is adjacent to the Routinely the left side is adjacent to the filmfilm

laterallateral

• Aortic arch• Right pulmonary

artery• Left pulmonary

artery• Trachea & bronchi

Image credit: Curry International Tuberculosis Center, University of California, San Francisco 23

• The clear spacesThe clear spacesRetrosternal spaceRetrosternal space normally this space is less than 3 cm normally this space is less than 3 cm

deepdeep

Retrocardiac spaceRetrocardiac space

• Vertebral translucencyVertebral translucency

The vertebral bodies become more The vertebral bodies become more translucent caudallytranslucent caudally

• Diaphragm outlineDiaphragm outline

Both diaphragms are visible Both diaphragms are visible

The posterior costophrenic angles are acute The posterior costophrenic angles are acute and small amounts of pleural fluid may be and small amounts of pleural fluid may be detected. detected.

• The fissuresThe fissures

Loculated interlobar effusionsLoculated interlobar effusions

DisplacementDisplacement

Thickening Thickening

• The tracheaThe tracheaThis passes down in a slightly posterior This passes down in a slightly posterior

direction.direction.

• The sternumThe sternum should be studied carefully in cases of malignancy or should be studied carefully in cases of malignancy or when there is a history of trauma.when there is a history of trauma.

Interpretation of abnormal filmInterpretation of abnormal film

• Radiological signsRadiological signsThe silhouette sign is the loss of an interface The silhouette sign is the loss of an interface

by adjacent disease, when air in the by adjacent disease, when air in the alveolar space is replaced by fluid or soft alveolar space is replaced by fluid or soft tissue, there is no longer a difference in tissue, there is no longer a difference in radiodensity between that part of the lung radiodensity between that part of the lung and the adjacent structures. Therfore the and the adjacent structures. Therfore the silhouette is lost and the silhouette sign is silhouette is lost and the silhouette sign is present.present.

Silhouette Silhouette signsign

• The air bronchogram The air bronchogram is an important sign is an important sign showing that the lesion is intrapulmonary. showing that the lesion is intrapulmonary. The bronchus , if air filled but not fluid, The bronchus , if air filled but not fluid, become visible when air is displaced from become visible when air is displaced from the surrounding parenchyma. The air the surrounding parenchyma. The air bronchogram is seen as scattered linear bronchogram is seen as scattered linear translucencies.translucencies.

Air bronchogramAir bronchogram