21
Imaging Techniques
C
Fig. 21.2 US-guided FNA. (A) Transverse US image of the left thyroid lobe reveals a predominately solid nodule. The tip of the 25-G biopsy needle (>) is clearly
seen within the nodule. Cytology revealed Hurthle cell nodule in a background of chronic lymphocytic thyroiditis. (B) Subcostal transverse US image of the
right lobe of the liver shows a 1.2-cm hypoechoic mass suspicious for metastatic disease in a patient with a pancreatic mass. The projected needle path for
biopsy is indicated by the dotted line through the lesion. (C) FNAB of liver nodule with 22-G Chiba needle. the needle is seen (>) with its tip within the lesion.
Cytology confirmed metastatic adenocarcinoma, likely of pancreatic origin.
Image-guided FNAB of Specific Organs *
1
2
3
Selection of the best imaging method for biopsy guidance in a
specific clinical setting is influenced by many factors. These will
vary in accord with the availability of appropriate imaging tech-
nology, the size and location of the lesion selected for biopsy,
the clinical condition of the patient and, most importantly, the
skill and experience of the physician who performs the biopsy.
Table 21.3 summarizes preferred and alternate image guidance
methods for common biopsy indications.
Regardless of the imaging approach selected for guidance, con-
sideration of contraindications to biopsy is necessary, especially
when deep biopsy is performed. Although there are no absolute
contraindications to FNAB, relative contraindications include:
1. Coagulopathy that cannot be adequately corrected;
2. Inability of the patient to cooperate with, or to be
positioned for, the procedure;
3. Known adverse reaction to contrast media when
contrast media administration is critical for the
performance of the procedure;
4. Hemodynamic instability; and
5. Lack of a safe pathway to the lesion.
Prior to the biopsy informed consent is necessary. The proce-
dure should be described in detail, including the need for breath-
holding, if needed. Possible complications including bleeding,
infection, injury to adjacent structures, and other potential
complications specific to the procedure being performed (e.g.
pneumothorax) and their likelihood are also discussed and the
patient's questions answered.
An important step in preparation for any image-guided
biopsy is the planning of the approach to the lesion to be sam-
pled. Scans prior to biopsy are performed to determine the safest
and easiest approach to the tissue of interest. Patient positioning
will often need to be adjusted to provide the best access to the
lesion. In the case of superficial biopsies this is usually a trivial
exercise, although care must be made to consider the presence of
superficial vessels that may overlie the target. When US guidance
is used, transducer pressure during scanning will completely
occlude these vessels so that they are not seen during biopsy.
Often it is necessary to perform the biopsy through these vessels.
603
previous page 595 ComprehensiveCytopathology 1104p 2008 read online next page 597 ComprehensiveCytopathology 1104p 2008 read online Home Toggle text on/off