Showing posts sorted by relevance for query BASICS OF HRCT INTERPRETATION-PART 2- RETICULAR PATTERN. Sort by date Show all posts
Showing posts sorted by relevance for query BASICS OF HRCT INTERPRETATION-PART 2- RETICULAR PATTERN. Sort by date Show all posts

BASICS OF HRCT INTERPRETATION-PART 3- NODULAR PATTERN

Nodular pattern

The distribution of nodules shown on HRCT is the most important factor in making an accurate diagnosis in the nodular pattern.
In most cases small nodules can be placed into one of three categories: perilymphatic, centrilobular or random distribution.
Random refers to no preference for a specific location in the secondary lobule.

Perilymphatic distribution
In patients with a perilymphatic distribution, nodules are seen in relation to pleural surfaces, interlobular septa and the peribronchovascular interstitium.
Nodules are almost always visible in a subpleural location, particularly in relation to the fissures.

Centrilobular distribution
In certain diseases, nodules are limited to the centrilobular region.
Unlike perilymphatic and random nodules, centrilobular nodules spare the pleural surfaces. 
The most peripheral nodules are centered 5-10mm from fissures or the pleural surface.

Random distribution
Nodules are randomly distributed relative to structures of the lung and secondary lobule. 
Nodules can usually be seen to involve the pleural surfaces and fissures, but lack the subpleural predominance often seen in patients with a perilymphatic distribution.

Algorithm for nodular pattern

The algorithm to distinguish perilymphatic, random and centrilobular nodules is the following:
  • Look for the presence of pleural nodules.
    These are often easiest to see along the fissures.
    If pleural nodules are absent or few in number, the distribution is likely centrilobular.
  • If pleural nodules are visible, the pattern is either random (miliary) or perilymphatic.
  • If there are pleural nodules and also nodules along the central bronchovascular interstitium and along interlobular septa, you are dealing with a periplymphatic distribution.
  • If the nodules are diffuse and uniformly distributed, it is likely a random distribution.
Perilymphatic distribution

Perilymphatic nodules are most commonly seen in sarcoidosis.
They also occur in silicosis, coal-worker's pneumoconiosis and lymphangitic spread of carcinoma.
Notice the overlap in differential diagnosis of perilymphatic nodules and the nodular septal thickening in the reticular pattern.
Sometimes the term reticulonodular is used.
Here a typical case of perilymphatic distribution of nodules in a patient with sarcoidosis.

Notice the nodules along the fissures indicating a perilymphatic distribution (red arrows).
Always look carefully for these nodules in the subpleural region and along the fissures, because this finding is very specific for sarcoidosis.
Typically in sarcoidosis is an upper lobe and perihilar predominance and in this case we see the majority of nodules located along the bronchovascular bundle (yellow arrow).
Another typical case of sarcoidosis.

In addition to the perilymphatic nodules, there are multiple enlarged lymph nodes, which is also typical for sarcoidosis.
In end stage sarcoidosis we will see fibrosis, which is also predominantly located in the upper lobes and perihilar.

Centrilobular distribution

Centrilobular nodules are seen in:
  • Hypersensitivity pneumonitis
  • Respiratory bronchiolitis in smokers
  • infectious airways diseases (endobronchial spread of tuberculosis or nontuberculous mycobacteria, bronchopneumonia)
  • Uncommon in bronchioloalveolar carcinoma, pulmonary edema, vasculitis


In many cases centrilobular nodules are of ground glass density and ill defined (figure).
They are called acinair nodules.

Tree-in-bud

In centrilobular nodules the recognition of 'tree-in-bud' is of value for narrowing the differential diagnosis.
Tree-in-bud describes the appearance of an irregular and often nodular branching structure, most easily identified in the lung periphery. 
It represents dilated and impacted (mucus or pus-filled) centrilobular bronchioles.

Tree-in-bud almost always indicates the presence of:

  • Endobronchial spread of infection (TB, MAC, any bacterial bronchopneumonia)
  • Airway disease associated with infection (cystic fibrosis, bronchiectasis)
  • less often, an airway disease associated primarily with mucus retention (allergic bronchopulmonary aspergillosis, asthma).
Here a tree-in-bud is seen.

In the proper clinical setting suspect active endobronchial spread of TB.

In most patients with active tuberculosis, the HRCT shows evidence of bronchogenic spread of disease even before bacteriologic results are available (6).
Random distribution

HRCT of a patient with random nodules as a result of miliary TB.
The random distribution is a result of the hematogenous spread of the infection.
Small random nodules are seen in:

  • Hematogenous metastases
  • Miliary tuberculosis
  • Miliary fungal infections
  • Sarcoidosis may mimick this pattern, when very extensive
  • Langerhans cell histiocytosis (early nodular stage)
Sarcoidosis usually has a perilymphatic distribution, but when it is very extensive, it spreads along the bronchovascular bundle to the periphery of the lung and may reach the centrilobular area.

Langerhans cell histiocytosis is an uncommon disease characterised by multiple cysts in patients with nicotine abuse.
In a very early stage, these patients show only nodules, that later on cavitate and become cysts (figure).


As in all smoking related diseases, there is an upper lobe predominance.




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Air Bronchogram Sign.

Pulmonary Medicine Blog By Dr Deepu

Air bronchogram

An air bronchogram is a tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammatory exudates. It is almost always caused by a pathologic airspace/alveolar process, in which something other than air fills the alveoli.

 Six causes of air bronchograms are
Lung consolidation
Pulmonary edema
Nonobstructive pulmonary atelectasis
Severe interstitial disease
Neoplasm
Normal expiration.
In The Image Air Bronchogram is seen.
The Magnified Image Showing Air Bronchogram On CXR and Confirmed With HRCT


The phenomenon is Characterised by  air-filled bronchi (dark) being made visible by the opacification of surrounding alveoli (grey/white). It is almost always caused by a pathologic airspace/alveolar process, in which something other than air fills the alveoli.
 Air bronchograms will not be visible if the bronchi themselves are opacified (e.g. by fluid) and thus indicate patent proximal airways.
Air bronchograms that persist for weeks despite appropriate antimicrobial therapy should raise the suspicion of a neoplastic process. CT may be planned in such cases.

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The ‘Dark Bronchus’ Sign: For diagnosis of PCP

Pulmonary Medicine Blog By Dr Deepu

Today I will discuss the importance of the ‘dark bronchus’ sign in the diagnosis of uniform, diffuse ground glass opacification on high resolution computerized tomography (HRCT). This sign is useful to identify diffuse ground glass opacity on HRCT in cases of Pneumocystis carinii pneumonia who may present with a normal or equivocal chest radiograph in the early course of disease.

Chest radiograph is the initial investigation in HIV patients with chest symptoms. But even in patients with proven PCP, radiographic findings may be normal in up to 20-40%. Low incidence of PCP in patients with normal or equivocal findings on chest radiograph despite high clinical suspicion emphasizes the need for a noninvasive and widely available investigation in such cases.

Various modalities to investigate symptomatic HIV patients with normal, equivocal or nonspecific radiographic findings include carbon monoxide diffusion in lung (DLCO), gallium citrate lung scanning and HRCT. A DLCO of less than 80% of the predicted value has a sensitivity of up to 98% for PCP, but the specificity is less than 50% and the measurement is not always available. Although gallium scanning has a sensitivity of up to 100% for PCP in patients with abnormal radiographs, it has never been prospectively studied in patients with normal or equivocal radiographic findings. In addition, this investigation requires a 48- to 72-hour delay in imaging, is not readily available and has a high cost.



    On the other hand, HRCT is a widely available and noninvasive investigation for PCP. Patchy or diffuse ground glass opacity is the most frequent finding. Other findings include cystic changes (33%), centrilobular nodules (25%), lymphadenopathy (25%) and pleural effusion (17%). HRCT has been found to be especially important in the assessment of symptomatic patients with normal, equivocal or nonspecific radiographs. In such cases, it shows high sensitivity (100%), specificity (86%) and accuracy (90%) for PCP, using only the presence or absence of ground glass opacity as the criterion for positivity.
The Arrow Shows The Dark Bronchus Relative to The Surrounding Lungs

Patchy ground opacity or mosaic attenuation, which is observed in up to 92% of the patients, can be easily identified on HRCT. However, subtle ground glass opacification, especially when bilateral and diffuse, may be difficult to diagnose. This is because of bilateral uniform increase in lung attenuation with absence of normal lung parenchyma for comparison. In such cases, the ‘dark bronchus’ appearance is a useful sign to identify diffuse ground glass opacity. This finding refers to the presence of air-filled bronchi appearing ‘too black’ relative to the surrounding lung parenchyma, which is filled with inflammatory alveolar exudates. This subtle finding may help in identification of patients with ‘possible PCP’ despite a normal or equivocal chest radiograph. Subsequently direct test for PCP (i.e., broncho-alveolar lavage) may be initiated for definitive diagnosis and treatment.
Hence the importance of the ‘dark bronchus’ sign in the diagnosis of uniform, diffuse ground glass opacification on HRCT. This is especially useful in the presence of a normal chest radiograph and ‘near normal’ HRCT. HRCT offers an accurate and early diagnosis in patients with normal chest radiographs; it alters patient management and facilitates early therapy.



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BASICS OF CHEST X RAY- PART 2 , EASY WAY TO INTERPRET CXR.

Welcome to basics of CXR, this is part two of this series, read my previous post part 1, in the next post we will be exploring about the silhouette sign and Hidden areas of the lung. You can print this page by clicking on the print option on right side, at the end of this post.

  Chest X-Rays (CXR) are routine investigation in clinical practice and consequently it is important for medical students and clinician’s alike to know how to interpret them. There are many approaches to CXR interpretation, each trying to ensure that key abnormalities are identified and no area is overlooked.
Many people would be familiar with the ABC method to interpreting CXRs.
  • Airways
  • Breathing & Bones
  • Circulation
This is a simple way of approaching CXR, and it works for many people, however some people still struggle using this approach. 
Normal CXR Labelled
DRSABCD is a familiar acronym for those who have undertaken First Aid/Basic Life Support courses. NowDRSABCDE can used as a simple, yet comprehensive, approach to CXR interpretation.

D – Details

Before you even begin interpreting a CXR you should have the correct details. This includes;
  • Patient name, age / DOB, sex
  • Type of film – PA or AP, erect or supine, correct L/R marker, inspiratory/expiratory series
  • Date and time of study

R – RIPE (assessing the image quality)

Next up, how “ripe” is the image. That is, what is the technical quality of the film?
  • Rotation – medial clavicle ends equidistant from spinous process
  • Inspiration – 5-6 anterior ribs in MCL or 8-10 posterior ribs above diaphragm, poor inspiration?, hyperexpanded?
  • Picture – straight vs oblique, entire lung fields, scapulae outside lung fields, angulation (ie ’tilt’ in vertical plane)
  • Exposure (Penetration) – IV disc spaces, spinous processes to ~T4, L) hemidiaphragm visible through cardiac shadow.

S – Soft tissues and bones

In CXR interpretation it is common to leave soft tissues until the end.
  • Ribs, sternum, spine, clavicles – symmetry, fractures, dislocations, lytic lesions, density
  • Soft tissues – looking for symmetry, swelling, loss of tissue planes, subcutaneous air, masses
  • Breast shadows
  • Calcification – great vessels, carotids

A – Airway & mediastinum

  • Trachea – central or slightly to right lung as crosses aortic arch
  • Paratracheal/mediastinal masses or adenopathy
  • Carina & RMB/LMB
  • Mediastinal width <8cm on PA film
  • Aortic knob
  • Hilum – T6-7 IV disc level, left hilum is usually higher (2cm) and squarer than the V-shaped right hilum.
  • Check vessels, calcification.

B – Breathing

  • Lung fields
    • Vascularity – to ~2cm of pleural surface (~3cm in apices), vessels in bases > apices
    • Pneumothorax – don’t forget apices
    • Lung field outlines – abnormal opacity/lucency, atelectasis, collapse, consolidation, bullae
    • Horizontal fissure on Right Lung
    • Pulmonary infiltrates – interstitial vs alveolar pattern
    • Coin lesions
    • Cavitary lesions
  • Pleura
    • Pleural reflections
    • Pleural thickening

C – Circulation

  • Heart position –⅔ to left, ⅓ to right
  • Heart size – measure cardiothoracic ratio on PA film (normal <0.5)
  • Heart borders – R) border is R) atrium, L) border is L) ventricle & atrium
  • Heart shape
  • Aortic stripe

D – Diaphragm

  • Hemidiaphragm levels – Right Lung higher than Left Lung (~2.5cm / 1 intercostal space)
  • Diaphragm shape/contour
  • Cardiophrenic and costophrenic angles – clear and sharp
  • Gastric bubble / colonic air
  • Subdiaphragmatic air (pneumoperitoneum)

E – Extras

  • ETT, CVP line, NG tube, PA catheters, ECG electrodes, PICC line, chest tube
  • PPM, AIDC, metalwork

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The Rings !!!The Trams!!!, Chest X Ray Findings in Bronchiectasis

Pulmonary Medicine Blog By Dr Deepu

  
Bronchiectasis is  an abnormal and permanent distortion of one or more of the conducting bronchi or airways.
In 1950, Reid characterized bronchiectasis as cylindrical, cystic, or varicose types.







Types of bronchiectasis


Cylindrical Bronchiectasis
Mild Form shows Tram Track Appearance

Varicose Bronchiectasis
Moderate Form appears as string of pearls

Cystic/ Saccular Bronchiectasis
Severe Form appears like Bunch of Grapes


       Chest radiography Chest radiography (CXR) is usually the initial study performed in both suspected bronchiectasis and the evaluation of nonspecific respiratory symptoms, such as dyspnoea and haemoptysis, when bronchiectasis may be identified incidentally.

Signs on CXR are the identification of
Read This X Ray Before Proceeding Further


1.     Parallel linear densities, tram-track opacities.

what was seen on the chest X ray, it is nothing but the tram line appearance, unable to spot it, here comes the Modified image
Now Compare the previous X Ray with the one above , Here are few examples of tram line shadows
The black arrows points towards tram line and the white to shadows which will be discussed below
Read this X ray before proceeding
What Can we see here
if you have got it proceed further
What we see here is the ring shadows, there are many other ring shadows in the x ray , only a few are  marked
One More X ray below showing the ring shadows in Cystic Fibrosis Patient 


2.     Ring shadows reflecting thickened and abnormally dilated bronchial walls. These bronchial abnormalities  may vary from subtle or barely perceptible 5-mm ring shadows to obvious cysts.
3.      Fluid or mucous filling of bronchi is seen and leads to Tubular branching opacities conforming to the expected bronchial branching pattern.
                                            


4.     The Definition of vessel walls is lost due to  peribronchial fibrosis.
5.     Signs of complications/exacerbations, such as patchy densities due to mucoid impaction and consolidation
6.      Volume loss secondary to bronchial mucoid obstruction or chronic cicatrisation, are also seen.
7.     In the more diffuse forms , such as cystic fibrosis (CF), generalised hyperinflation and oligaemia are often present, consistent with severe small airways obstruction.
The radiograph may raise the initial suspicion of bronchiectasis, triggering more definitive imaging. 
CXR also plays a role in the follow-up of bronchiectasis and management of exacerbations.Although CXR has limitations in specificity in diagnosing bronchiectasis and in detecting early or subtle changes, it is useful for assessing more florid cases of bronchiectasis, in CF and in follow-up of bronchiectatic patients. Computed tomography.

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