ON
C
Fine-Needle Aspiration of
Various Organs and Body Sites
chapter
21
Imaging Techniques
Christopher R B Merritt
Contents
In tro d u c tio n
T h y r o id , p e r ip h e r a l L y m p h N o d e s , S a liv a r y G la n d , a n d S u p e rfic ia l S o ft T is s u e M a s s e s
Im a g in g m e th o d s
C o n v e n tio n a l R a d io g ra p h y a n d F lu o r o s c o p y
M e d ia s t in u m
C o m p u t e d T o m o g r a p h y
A b d o m in a l a n d p e lv ic O r g a n s
M a g n e t ic r e s o n a n c e
C o n c lu d in g R e m a rk s
U lt r a s o u n d
C o m p lic a tio n s o f im a g e -g u id e d F N A B
Im a g e -g u id e d F N A B o f S p e c ific O r g a ns
Introduction
Although modern imaging and laboratory methods permit
precise identification of the presence and location of disease
throughout the body, cytologic or histologic examination of
tissue remains an essential step in establishing a definitive
diagnosis and in planning patient management. Tissue sam-
pling by excision or biopsy coupled with modern methods of
tissue processing and examination for specific immunohisto-
chemical markers plays an important role in differentiation
of benign and malignant disease, and in optimizing therapy
for malignancy. The widespread availability of modern imag-
ing equipment capable of imaging abnormalities throughout
the body has given rise to the adoption of minimally invasive
diagnosis of pathology using the combined skills of the imager,
interventionalist,
and
cytopathologist.
Image-guided
fine-
needle aspiration biopsy (FNAB) can be quickly accomplished
in almost all body locations with minimal risk and discomfort,
avoiding more invasive, risky, and costly procedures for defini-
tive diagnosis.
Image-guided FNAB ideally involves the active participation
of a cytopathologist to evaluate the adequacy of specimens as
they are obtained. This assures that sufficient cells for diagnosis
are obtained with the minimum number of samples, thereby
reducing patient risk and discomfort and the inconvenience
and anxiety of returning for additional samples if the initial
attempts are unsuccessful. Having a cytopathologist in attend-
ance may also permit the use of smaller needles for initial
samples, reserving larger bore needles or core biopsy only for
those instances in which the smaller needles do not provide
adequate samples.
Indications for image-guided percutaneous needle biopsy
include, but are not limited to, the following:1
1. To establish the benign or malignant nature of a
lesion;
2. To obtain material for microbiologic analysis in
patients with known or suspected infections;
3. To stage patients with known or suspected malignancy
when local spread or distant metastasis is suspected;
and
4. To determine the nature and extent of certain diffuse
parenchymal diseases.
FNAB may play a role in each of these indications, though
most often biopsy is performed to establish the nature of a lesion
as benign or malignant and to aid in the staging of malignant
disease. Diffuse parenchymal diseases are more often evaluated
with core biopsy techniques.
An ideal method for obtaining tissue samples for analysis
should provide high sensitivity and specificity, while minimiz-
ing patient risk and discomfort. Modern fine-needle aspiration
biopsy, when performed with expert sampling technique and
cytological evaluation, provides these benefits. For masses that
are superficial and easily palpable, FNAB may be performed
without the need for image guidance. Lesions not readily
palpated require imaging guidance by fluoroscopy, ultrasound
(US), computed tomography (CT), or magnetic resonance imag-
ing (MRI). In addition, image guidance is often beneficial in the
biopsy of palpable superficial masses.2 Table 21.1 lists advan-
tages of image guidance for fine-needle aspiration biopsy.
As the availability and capability of CT, US, MRI, positron
emission tomography (PET), and PET-CT have grown, particu-
larly in North American and Europe, lesions previously undetect-
able are routinely being imaged, creating a need for confirming
diagnosis by tissue sampling. Most lesions not visible or palpable,
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