Crash course in CHEST XRAY INTERPRETATION Presented by: Marc Caballero, MD Today, we will learn interpreting chest x-rays. This will just be a short presentation. It will be interactive, you can interrupt me any time for questions. But at the same time, I will also be asking you questions during this lecture. I will present this in the most simplest way so that we can gain a clear understanding. There will be lots of images and we will go back and forth when it is necessary.

Learning Objectives So why are we here? Our aim is to learn and … To be able to identify the structures or your radio anatomy… To know how a normal chest x-ray appears… To interpret radio pathologic lesion… To put it in practice!

Learning Objectives Can anyone in here interpret this chest x-ray for me? (pause) What disease entity is this? Where is this lesion located? front? back? Is this a mass lesion? Consolidation? An atelectasis? How can I interpret this image? I am sure these are some of the few questions which you have in your head right now. Now lets move on to our first case.

This is a chest x-ray in PA view taken from a 36 year old male due to on and off non-productive cough. As you notice in the right paracardiac region, it shows some form of haziness. This was read as a mild inflammatory process. Patient was told take medications but did not complete the regimen.

Patient came back now with a follow-up x-ray done 3 weeks later showed an area of consolidation with air-bronchogram pattern in the right lower lung and right middle lung. Some infiltrates are also seen in the left upper. There is also beginning right pleural effusion. This time, patient took the medication seriously, but refused admission.

Somehow the patient agreed to be admitted Somehow the patient agreed to be admitted. But now presenting with this x-ray! Now we know that effusion progressed. It appears to have a well demarcated borders. We need to know is this fluid free or loculated? Supposing we did not have a previous film for comparison and just be presented with a film that is almost completely opacified hemithorax. It will be hard to know if there is a concomitant mass. Right? So we need to manipulate in order to determine if there is a underlying mass prior to doing a CTT.

A right lateral decubitus film was taken showing a free flow of fluid.

Ultrasound showed a 257.23 ml of non loculated pleural effusion.

A lead-lined CTT was inserted with its tip at 5th left posterior rib and its sentinel eye at 6th rib. Now, the radiologist was able to help in the decision making of the AP whether it was safe to proceed with CTT. And was able to give an approximate amount of volume that could be drained.

As a follow-up 2 months after As a follow-up 2 months after. An impressive clearing of the lungs were seen. So kudos to the clinician and radiologist!

BASIC CONCEPTS DENSITIES SOFT TISSUES BONE WATER FAT AIR Lets go back a little on basics. As you can see, bone or metal appears the most opacified or radioopaque; while air appears the most radiolucent or black. Water and soft tissues for most part, appears as an intermediate density.

BASIC CONCEPTS Here is a schematic of an xray tube. The cathode end which carries the negative charge is accelerated under a vacuum towards the tungsten anode end which is the positive side causing the release of Xray beam. It was named x-ray because during the time of Wilhelm Roentgen in the late 1800’s, such energy form was still unknown, thus the letter “X” in xray. This energy is known to penetrate materials which eventually then made its way in medicine. X-rays

BASIC CONCEPTS PA View In posterior-anterior view, the xray beam enters in the back of the patient and exits the body anteriorly. In practice, it is taken while the patient takes a deep inspiration and in the position seen above. This position allows the flaring out of the clavicles away from the lungs. This also allows expansion of the lungs and eliminating the crowding of bronchovascular structures. With good inspiration, the diaphragm is seen at the level between 8th- 10th ribs. The silhouette of the vertebral body should also be seen in order to have good xray penetration. The medial ends of the clavicle should be equidistant from the midline.

BASIC CONCEPTS AP VIEW Anterior-posterior view is taken in supine position with the xray entering anteriorly and exiting the patients body posteriorly. A good inspiration would show the diaphragm at the 5th-6th rib level. Other views include, upright lateral with xray entering on 1-side and exiting on the other side. Lateral view is important for pediatric patients since most of its lung parenchyma is obscured by the mediastinal shadow. A decubitus view, as you recall, helps elucidate fluid that was hidden in the posterior recess of the diaphragm. A lordotic view is taken in order to display the lung apices which are normally obscurred in ordinary PA or AP view. It is taken with the patient arching its back and standing at least a foot away from the cassette.

BASIC CONCEPTS PA VS. AP VIEW No magnification On the right side is the PA view; while the left side is AP view. Firstly, AP view has magnification of the mediastinal structures. This is brought about by the inherent wider gap between the heart shadow and cassette. While in the PA view, the heart is closer to the cassette since the heart is located more anteriorly. In PA view, there is very little superimposition of the scapula; while the scapula obscures about ¼ of the lungs in AP view. No magnification no obscuration by the scapula Consider magnification scapula obscures the lung parenchyma

BASIC CONCEPTS Criteria for an Ideal Chest Radiograph Upright Posteroanterior View Full / Midinspiration Six Feet Target Film Distance

RADIOANATOMY (Point and name the structures) The pulmonary vascular structures are prominent inferiorly and it tapers gradually as it approaches the lateral chest wall.

As a follow-up 2 months after As a follow-up 2 months after. An impressive clearing of the lungs were seen. So kudos to the clinician and radiologist! Now, lets go back a little on basic chest x-ray.