IMAGE OF THE WEEK 2013

WEEK 10

 

LUNG BIOPSY TECHNIQUES

 

Figure 1a: CT chest showing a left upper lobe lung nodule with a co-axial needle inserted into the nodule for fine needle aspiration cytology (FNAC).

(Click on image to enlarge)

Figure 1b: Annotated CT chest showing fine needle aspiration of the lung nodule using co-axial needle.  

(Click on image to enlarge)

   

 

 

Lung lesions are common.  Biopsy is frequently required for management purposes.

Biopsy may be performed to determine a histological diagnosis ( i.e TB v malignancy ) for a lung lesion or to ascertain the specific histology of a lung cancer to determine treatment.

Lesions may be accessed in 3 ways:

1.    Bronchoscopically

2.    Via image guidance the vast majority of which require CT guidance

3.    Surgical biopsy/excision

Each patient should be assessed on a case by case basis, ideally with a MDT meeting discussion.

 

Bronchoscopic Biopsies

 

In the presence of either a central lung mass or peripheral lesions (nodules), bronchoscopy is generally performed to evaluate the status of the endobronchial epithelium for lesions and resectability. If endobronchial lesions are seen, then a direct bronchoscopic biopsies of the lesion may be performed under direct vision. If the lesion is peripheral, then a biopsy forceps can be inserted into the segmental bronchii where the nodule or mass is located, determined using CT scan of the lungs, and a blind transbronchial biopsies is performed, although the yield for this sort of procedure is very low with sensitivity as low as 30% and specificity as high as 100%. In combination, bronchial brushings and lavage can also be performed at the culprit bronchus to increase yield of cellular materials.

 

In the presence of peri or pre-tracheal or subcarinal enlarged mediastinal lymph nodes, a transtracheal or transbronchial biopsies of this lymph nodes is possible using endobronchial ultrasound (EBUS) guidance to locate the lymph nodes.  EBUS-TBNA (EndoBronchial UltraSound TransBronchial Node Aspiration) has been shown to have a sensitivity and specificity of 92% and 100% respectively.

 

CT guided Fine Needle Aspiration Cytology (FNAC)

 

There are a number of relative contraindications to CT guided biopsy, which include:

Several issues should also be assessed in planning the procedure

1.    Size of lesion ( sub 12mm can be challenging to access )

2.    Pleural to lesion distance.  The longer route the more risky

3.    Whether a fissure must be crossed in path to lesion.  Pneumothorax more likely.

 

The main risk factors are pneumothorax and haemoptysis.  The former is much commoner, a percentage of which will be large enough to require a pleural drain.

CT lung biopsy is normally performed with a co-axial needle (typically 18G).

Skin surface markers are sited (Figure x) and a small range of images taken to determine the access point.  Local anaesthetic is applied and a small skin incision (4-5mm) made.

With the patient breathing normally (no breath hold) the access needle is angulated and advanced to just prior to the lesion edge (Figures 1 and 2).  The biopsy needle is then passed through the access needle to acquire one or more samples.  Biopsy needle throw is typically 20mm. 

After the biopsy is complete a check image is taken to assess for a pneumothorax.  A chest x-ray should then be taken 4 hours after the procedure to check for a pneumothorax.

 

Video Assisted Thoracoscopic Biopsies

 

When the above techniques, bronchoscopic transbronchial or EBUS-TBNA and CT guided biopsies, failed to confirm a positive diagnosis, then patients are generally referred to the thoracic surgeon for VATS biopsies of the lung lesions. 

VATS biopsies can be performed through 2 or 3 ports and is generally helpful in periperal lesion larger than 1cm. Subcentimetre lesions may be difficult to detect on VATS unless they are near the surface. Likewise, central lesions are impossible to detect if they are small.

A wedge segment containing the nodule or lung lesion is removed using endostapler to excise the lung wedge. VATS lung biopsy has a reported sensitivity, specificity and diagnostic accuracy of 95%, 100% and 97% respectively.

 

Images and text contributed and prepared by

Dr Ian Bickle, Department of Radiology,RIPAS Hospital

Dr Chong Chee Fui, Thoracic Unit, Department of Surgery, RIPAS Hospital

All images are copyrighted and property of RIPAS Hospital.

 

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