Congestive heart failure chest x ray

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

A chest X-ray, commonly abbreviated CXR, is a projection radiograph (X-ray), taken by a radiographer, of the thorax which is used to diagnose problems with that area.

Examples of such problems include but are not limited to:

• Pneumothorax, sometimes tension pneumothorax (though this is usually diagnosed clinically because of its acute nature)
• Rib fracture
• Air space disease/consolidation (e.g. pneumonia)
• Interstitial lung disease (e.g. idiopathic pulmonary fibrosis (IPF), lung cancer, active tuberculosis)
• Cardiac silhouette enlargement – congestive heart failure, pericardial effusion, hypertrophic cardiomyopathies
• Pleural effusion
• Peritonitis
• Hiatal hernia
• Emphysema
• Pulmonary embolism (rarely) – usually CXR is normal
• Dissecting aortic aneurysm (due to trauma, advanced/untreated syphilis, connective tissue disorders)

Chest X-Rays are among the most common films taken, being diagnostic of so many important problems.

Every doctor will have a different approach to examining chest X-rays. A commonly used mnemonic for what to look for on a chest X-ray is: It May Prove Quite Right (but) Stop And Be Certain How Lungs Appear:

• I = Identification (name, age, sex, indication for X-ray)
• M = Markers (differentiate left from right – diagnose dextrocardia)
• P = Position – the spinous process of T4 should be between the heads of the clavicle (if it isn’t the body is rotated)
• Q = Quality – is the film penetrated properly. In a properly penetrated film the vertebral interspaces should be visible behind the central (cardiac) shadow
• R = Respiration – chest X-rays are typically done with full inspiration
• (but)
• S = Soft tissue – look for subcutaneous emphysema (suggestive of trauma), soft tissue swelling
• A = Abdomen – look for free abdominal air (suggests penetrating trauma, peritonitis, or recent surgery)
• B = Bone – look for fractures (these tend to be at the lateral aspects because of the mechanics – bending moment largest at lateral aspect)
• C = Central shadow (cardiac silhouette) – greater than 50% of lateral distance in frontal view at the diaphragm suggests cardiac enlargement (usually secondary to heart failure) or a pericardial effusion). A widened mediastinum may suggest aortic dissection.
• H = Hila (of the lungs) – can be affected in lung disease, malignant processes and infection (hilar lymphadenopathy).
• L = Lungs – for consolidation, interstitial lung disease (reticular, nodular or reticulonodular), honeycombing, miliary pattern, granulomas, lung masses
• A = Absent structures/Apices of the lung (for pneumothorax)

Another approach is to examine first any major abnormality, and then “review areas”:

• the apices,
• the hila,
• behind the heart (it must be remembered that lung can be seen through the heart),
• the cardiophrenic angles,
• the costophrenic angles,
• beneath the diaphragm, and then
• bone and soft tissues.

A third approach is:

• Inspection of chest
  • Centralized – Check whether the Xray is centralized. In a well centralized film the clavicle is equidistant from the spines of the vertebral body. It is important when we are commenting on the comparative radiolucency of the lung field, cardiomegaly and mediastenal shift.
  • Compare the lung field on upper, middle, and lower zone to check for radiolucency on both side of lungs at equal levels.
  • Check the apical area (just behind the clavicle) for the changes due to tuberculosis.
  • Check for any cervical rib in cases of bony deformities
  • Check for cardiophrenic and costophrenic angles. These are sharp and curved in healthy individuals. The right diaphragm is .5 – 1.5 cm higher than the left diaphragm.
  • Check the hila for any hilar lymphadenopathy. The left hilum is slightly higher than the right
  • Trace trachea up to the carina to check for any deviation.
• Inspection of the cardiac silhouette
  • Check the cardiac borders. Left cardiac border is formed by aorta, pulmonary conus, left atrium, and right atrium from top to bottom. The right border is formed by superior vena cava and right atrium
  • Measure the cardio-thoracic ratio to rule out any cardiomegaly. To measure the cardiothoracic ratio draw a vertical line through the spine of the vertebrae. Draw lines perpendicular from this line to the maximum width of the left (say for e.g. a) and right heart borders (say for e.g. b). The summation of a and b should be less than half of the maximum transverse diameter of the chest (say for e.g. c). Thus a+b = or < C/2
• Inspection of bones
• Check ribs for crowding, spreading and bony lesions
• Check clavicle, scapula, and shoulder joints
• Inspection of soft tissue
  • Check chest muscles, subcutaneous tissue, and breast in females

• Frontal (view)
  • PA (posterior-anterior)
  • AP (anterior-posterior) – these are typically done in the ICU
• Lateral (view)

The most common view is the PA (posterior-anterior) and is frequently done with a left lateral view (so one can identify the location of abnormalities in 3-D space). PA views are generally preferred to AP views (which are often done with mobile/portable X-ray equipment), but much less convenient in the ICU setting or when a patient cannot otherwise leave their bed. PA views are preferred because the central shadow is better defined, the magnification of the heart is reduced, and less of the lungs obscured by the heart/pericardial sac.

• Decubitus – useful for differentiating pleural effusions from consolidation (e.g. pneumonia). In effusions, the fluid layers out (by comparison to an up-right view, when it often accumulates in the costophrenic angles).
• Lordotic view – used to visualize the apex of the lung, to pick-up abnormalities such as a Pancoast tumour.
• Expiratory view – helpful for the diagnosis of pneumothorax
• Obliques

A nodule is a discrete opacity in the lung which may be caused by:

• Neoplasm: benign or malignant
• Granuloma: tuberculosis
• Infection: round pneumonia
• Vascular: infarction, varix, Wegener’s granulomatosis, rheumatoid arthritis

There are a number of features that are helpful in suggesting the diagnosis:

• rate of growth
  • Doubling time of less than one month: sarcoma/infection/infarction/vascular
  • Doubling time of six to 18 months: benign tumour/malignant granuloma
  • Doubling time of more than 24 months: benign nodule
• calcification
• margin
  • smooth
  • lobulated
  • presence of a corona radiata
• shape
• site

If the nodules are multiple, the differential is then smaller:

• infection: tuberculosis, fungal infection, septic emboli
• neoplasm: e.g., metastases, lymphoma, harmatoma
• sarcoidosis
• alveolitis
• auto-immune disease: e.g., Wegener’s granulomatosis, rheumatoid arthritis
• inhalation (e.g., pneumoconiosis)

A cavity is a walled hollow structure within the lungs. Diagnosis is aided by noting:

• wall thickness
• wall outline
• changes in the surrounding lung

The causes include:

• cancer (usually malignant)
• infarction (usually from a pulmonary embolus)
• infection: e.g., Staphylococcus aureus, tuberculosis, Gram negative bacteria (especially Klebsiella pneumoniae), and anaerobic bacteria.

Fluid in space between the lung and the chest wall is termed a pleural effusion. There needs to be at least 75ml of pleural fluid in order to blunt the costophrenic angle on the lateral chest X-ray, and 200ml on the posteroanterior chest X-ray. On a lateral decubitus, amounts as small as 5ml of fluid are possible. Pleural effusions typically have a meniscus visible on an erect chest X-ray, but loculated effusions (as occur with an empyema) may have a lenticular shape (the fluid making an obtuse angle with the chest wall).

Pleural thickening may cause blunting of the costophrenic angle, but is distinguished from pleural fluid by the fact that is occurs as a linear shadow ascending vertically and clinging to the ribs.

The differential for diffuse shadowing is very broad and can defeat even the most experienced radiologist. It is seldom possible to reach a diagnosis on the basis of the chest X-ray alone: high-resolution CT of the chest is usually required and sometimes a lung biopsy. The following features should be noted:

• type of shadowing (lines, dots or rings)
  • reticular (crisscrossing lines)
  • nodular (lots of small dots)
  • rings or cysts
  • ground glass
  • consolidation (diffuse opacity with air bronchograms)
• location (where is the lesion worst?)
  • upper zone (e.g., sarcoid, tuberculosis, silicosis/pneumoconiosis, ankylosing spondylitis, Langerhans cell histiocytosis)
  • lower zone (e.g., cryptogenic fibrosing alveolitis, connective tissue disease, asbestosis, drug reactions)
  • central (e.g., pulmonary oedema, alveolar proteinosis, lymphoma, Kaposi’s sarcoma, PCP)
  • peripheral (e.g., cryptogenic fibrosing alveolitis, connective tissue disease,chronic eosinophilic pneumonia, bronchiolitis obliterans organizing pneumonia)
• lung volume
  • increased (e.g., Langerhans cell histiocytosis, lymphangioleiomyomatosis, cystic fibrosis, allergic bronchopulmonary aspergillosis)
  • decreased (e.g., fibrotic lung disease, chronic sarcoidosis, chronic extrinsic allergic alveolitis)

Pleural effusions may occur with cancer, sarcoid, connective tissue diseases and lymphangioleiomyomatosis. The presence of a pleural effusion argues against pneumocystis pneumonia.

Reticular (linear) pattern

(sometimes called “reticulonodular” because of the appearance of nodules at the intesection of the lines, even though there are no true nodule present)

• cryptogenic fibrosing alveolitis
• connective tissue disease
• sarcoidosis
• radiation fibrosis
• asbestosis
• lymphangitis carcinomatosis

Nodular pattern

• sarcoidosis
• silicosis/pneumoconiosis
• extrinsic allergic alveolitis
• Langerhans cell histiocytosis
• lymphangitis carcinomatosis
• miliary tuberculosis
• metastases

Cystic

• cryptogenic fibrosing alveolitis (late stage “honeycomb lung”)
• cystic bronchiectasis
• Langerhans cell histocytosis
• lymphangioleiomyomatosis

Ground glass

• Extrinsic allergic alveolitis
• Diffuse interstitial pneumonitis
• Alveolar proteinosis

Consolidation

• Alveolar haemorrhage
• Alveolar cell carcinoma
• vasculitis
• chronic eosinophilic pneumonia

It must be remembered that while the chest X-ray is a cheap and safe method of investigating diseases of the chest, there are a number of serious chest conditions that may be associated with a normal chest X-ray and other means of assessment may be necessary to make the diagnosis:

• Asthma
• Chronic obstructive pulmonary disease
• Pneumocystis jiroveci pneumonia (PCP)
• Pulmonary embolism
• Smoke inhalation
• Foreign body inhalation

• The silhouette sign is especially helpful in localizing lung lesions. (e.g., loss of right heart border in right middle lobe pneumonia),^[1]

• The air bronchogram sign, where branching radiolucent columns of air corresponding to bronchi is seen, usually indicates air-space (alveolar) disease, as from blood, pus, mucus, cells, protein surrounding the air bronchograms. This is seen in Respiratory distress syndrome^[1]

• The “bean” sign first described by Professor Keval Pandya is the appearance of a sharply circumscribed bean shaped nodule on chest X-ray which has a high sensitivity and specificity (92% and 88%) for the presence of miliary TB.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; David E. Winchester M.D. M.S.

This chapter presents a brief overview of cardiac imaging techniques. For a detailed discussion of each of the imaging technoloies, please view the chapter on that imaging technology.

• Least expensive, most versatile.
• Portable, immediately available
• Preferred initial technique to diagnose heart muscle disease of unknown etiology.
• Regional thickening can be assessed on ECHO and not other techniques and this is a better marker of regional function than is regional wall motion (cant be seen on nuclear or angio studies, MRI can assess though)
• ECHO is not as good at assessing quantitative ejection fraction (SPECT, angio, RVG are better at this).
• More sensitive than EKG in diagnosis of LVH.
• Excellent in estimating LV mass

• Good for quantitating LV and RV EFs. Excellent for following the wall motion in patients treated with chemotherapeutic agents.
• Good for wall motion.
• In MI does not tell you about infarct expansion, MR, LV thrombus, regional thickening abnormalities.

• Permits evaluation of regional thickening, global LV function and myocardial perfusion.

• Good regional and global cardiac function.
• With contrast agents, good perfusion data
• Superior for congenital, aortic disease, anomalous coronary arteries, and RV dysplasia
• Cost benefit ratios of echo and nuclear make them superior for LV function assessment
• May be best technique for quantitating LV mass
• As a research tool may be useful in the assessment of LV remodeling

• Gold standard in the assessment of wall motion but not in the assessment of wall thickening.
• LVEF and absolute volumes are highly reproducible
• LVH and LV mass are better quantitated with echo and MRI
• Left to right shunts are most accurately quantitated with cardiac cath over echo and MRI

• Strengths

  • Low cost
  • Short duration
  • Functional status evaluation
  • High sensitivity in 3 VD or left main disease
  • Useful prognostic information

• Limitations
• Suboptimal sensitivity in the detection of single vessel disease (50%), 85% in the presence of three vessel disease
• In all patients, overall sensitivity 68%, specificity 77%
• Beta blocker use is associated with a higher rate of false negatives (fail to achieve rate pressure product)
• Non diagnostic in patients with abnormal baseline EKG (dig, LVH, WPW)
• Poor specificity in certain patient populations: premenopausal women, LVH, dig, IVCD, hypokalemia, hyperventilation, severe hypertension, resting ST abnormalities
• The negative predictive value in women of low to intermediate risk is high, the positive predictive value in men is high
• Need to achieve > 85% of maximum heart rate for maximizing accuracy
• Its main values lies in excluding CAD in patients with a low pre test probability of CAD based on gender and age.

• Strengths

  • Simultaneous evaluation of perfusion and function with gated SPECT
  • Higher sensitivity and specificity than exercise EKG: For exercise or pharmacologic SPECT imaging with Tl or Tc, in patients with chest pain the sensitivity for the detection of CAD is 85% to 90%. Specificity for excluding CAD is in the 90% range. Good in patients with LVH, dig, IVCD etc. ST depression response higher rate pressure product than does a perfusion abnormality with tracers. Therefore they are more sensitive. Adding stress perfusion imaging to the exercise ECG stress test greatly assists in differentiating true positive from false positive ETT ST segment depression. For single vessel disease, the sensitivity is 25% higher with SPECT imaging compared with exercise testing. The sensitivity for detecting 3VD with exercise SPECT is 95% to 100%.
  • High specificity with Tc labeled agents: Half life is shorter than Tl, therefore dose is higher, therefore image is brighter and better. Also allows gated assessment of LV thickening.
  • Studies can be performed in almost all patients
  • Significant additional prognostic information, can quantitate LV function
  • Comparable accuracy with pharmacologic stress testing
  • Viability and ischemia when assessed simultaneously
  • Quantitative image analysis

• Limitations

  • Suboptimal specificity with thallium imaging, with a high false positive rate in many labs, particularly among women and obese patients.
  • Long procedure time with Tc agents, higher costs than ETT
  • Radiation exposure
  • Poor images in obese patients
  • Pharmacologic stress testing: sensitivity and specificity are similar for persantine and adenosine. Dobutamine is used in those patients with a history of bronchospasm, or for those patients who have consumed coffee before the procedure. Pharmacologic testing is the preferred method in patients with LBBB.
  • Women with chest pain who are referred for exercise or pharmacologic stress testing benefit the most from the enhanced accuracy of Tc imaging. Both Tl and Tc had a sensitivity of about 70%, but the specificity rose to 92% with Tc. Most labs now use Tc because of its improved specificity, the ability to gait the images and assess regional wall thickening. Mild non reversible defects that show preserved systolic thickening usually represent attenuation artifacts, however, if there is abnormal wall thickening, then this is most likely scar.

• Strengths

  • Higher sensitivity and specificity than exercise EKG: Metanalysis showed sensitivity of 84%, specificity 86%. Marked variation across trials though, highly operator dependent. If the max heart rate is < 85% of age predicted, then sensitivity drops to 42%. Sensitivity is 10% lower in women than in men, specificity is the same across genders. In women with single vessel disease the sensitivity was only 40%, if there was 2 or 3 vessel disease, this number increased to 60%.
  • Additional prognostic value over exercise EKG
  • Dobutamine stress has higher sensitivity than does pharmacologic stress
  • Time to complete examination is short
  • Identification of co-existent structural cardiac abnormalities (valvular disease)
  • Simultaneous evaluation of perfusion with contrast agents
  • Relatively lower costs than with other techniques
  • No radiation

• Limitations

  • Decreased sensitivity for the detection of single vessel disease or mild stenosis with post exercise imaging
  • Inability to image the entire ventricle in some patients
  • Highly operator dependent in the analysis of images
  • No quantitative image analysis
  • Poor windows in patients with COPD
  • Infarct zone ischemia less well detected

• Both have a higher sensitivity and specificity than regular exercise EKG testing
• Both provide functional information that EKG testing does not
• Both provide information about myocardial viability, which the angiogram does not

• Noninvasive, safe and repeatable, no radiation exposure, quick, little sophisticated equipment and portable, low costs, can identify co-existing valvular heart disease

• Images are difficult to obtain at peak exercise, an ischemic response is required to observe wall motion abnormalities, wall motion can recover quickly in the presence of mild ischemia, detection of residual ischemia is difficult in an akinetic wall zone, the technique is highly operator dependent, good quality images were only acquired in 70% of cases.

• Does not require an ischemic response to be abnormal, just requires an abnormality in flow reserve, sensitivity is slightly higher by about 8-10 percentage points (mostly because the ability to detect single vessel disease or mild stenoses of 50-70% is not as good with stress Echo), can see defects in areas that contain scar and viable myocardium, acquisition of images is not operator dependent, in virtually 100% of patients diagnostic images are obtained, with Tc simultaneous assessment of perfusion and function is obtained, resting LV ejection fraction can be obtained, vasodilator SPECT has significantly higher sensitivity than vasodilator stress ECHO, dobutamine ECHO is associated with higher sensitivity and specificity than vasodilator ECHO.

• Longer imaging protocols, greater expense of equipment, must inject and store radiopharmaceuticals, inability to visualize the heart in real time, lower spatial resolution than ECHO, higher costs to patients.

In general, the sensitivity is lower for stress ECHO while the specificity is higher.

• 1 mm or more of horizontal or downsloping ST depression is associated with a poor prognosis
• Failure to achieve 6 METS is associated with an elevated mortality rate over the next 2.5 years.
• Failure of heart rate to rise is associated with higher mortality, even after adjusting for perfusion defects.
• Failure to reach 85% of age adjusted max HR is associated with a RR of 1.85 in mortality.
• Limitation of ETT is the fact that the magnitude of ST depression is not strongly associated with the extent of CAD
• Exercise testing alone has excellent prognostic ability among patients with atypical chest pain or non anginal pain who have a normal EKG at baseline. If these patients have a normal ETT, the prognosis is excellent.

• Nuclear Stress Myocardial Perfusion Imaging, often abbreviated MPI or MPS, is a technique for measuring perfusion of myocardial tissue using externally injected radioactive tracers. Photons, or positrons emitted from these tracers are then detected with specialized imaging equipment and software. The most common methods are single photon emission computed tomography (SPECT) and positron emission tomography (PET). SPECT can be performed with radiotracers based on thallium or technetium 99-m. PET is commonly performed with rubidium-82, although some centers use ammonia (NH3) or radiolabeled oxygen in water. Cardiac PET with fluorodeoxyglucose (FDG) is useful for other investigations such as evaluation of infections, sarcoidosis activity, and viability/hibernation. Flurpiridaz, is a PET tracer based on fluorine-18 (F-18) and was approved for use by the FDA in 2025.
• The following are associated with a poor prognosis:

  • 20% of the LV is a perfusion defect
  • Defects in more than one distribution suggestive of multivessel CAD
  • A large number of non reversible defects
  • Transient LV cavitary dilation
  • Increased lung uptake
  • Resting LVEF of < 40%

• Normal thallium: Mortality 1% per year
• Normal Tc: annual mortality 0.6%, 12 fold higher if there is a Tc defect
• The positive predictive value of stress myocardial perfusion imaging and stress ECHO is low: That is the percentage of people who die or sustain an MI is low among patients with abnormal findings. On the other hand the negative predictive value is high and exceeds 95%.

• Tl Imaging

  • Rest and delayed redistribution is the most common radionuclide method used to assess viability. Uptake of Tl is related not only to blood flow, but also to membrane integrity. Myocardial stunning or hibernation does not result in a reduction in Tl extraction as long as the sarcolemmal membrane does not sustain irreversible ischemic damage. 60 to 70% of asynergistic segments will show > a 50% improvement after revascularization.

• Tc Imaging

  • Same as above, as usual a better signal with Tc, can also assess regional wall thickening. If thickening is present, then viability is likely.

• PET

  • Considered by many to be the gold standard. Can be used to assess perfusion and metabolism simultaneously. If there is mismatch in perfusion and metabolism, then the tissue is viable. If there is a match, then there is scar.

Dobutamine: Enhanced systolic contractility with low dose dobutamine is associated with recovery.

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