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104 T. J. DiBartholomeo and C. W. Bakal
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sh
sh
age of urine while better maintaining structural integrity
and rigidity of the catheter tip and pigtail. Unlike side
holes of standard angiographic catheters, the side holes
on a drainage catheter are larger than standard 0.038inch guidewires, which can exit the catheter during wire
advancement. Usually, this can be avoided by using
straight-tipped rather than “J”-tipped guidwires or by using angled wires, which can be torqued away from the
side holes during wire passage. The drainage holes are
relatively widely spaced to maximize catheter body and
pushing strength when inserting the catheter through
tissue. The catheter typically has a slippery or low resistance coating to ease its passage through the skin
tracks and deeper tissues. Typical drainage catheters are
designed to be inserted over a 0.038-inch guidewire. Stiff
guidewires generally should be used. Rarely, a sump
catheter is utilized for drainage of purulent, thick material. The second lumen of a sump permits the catheter
to be placed to suction rather than for gravity drainage
6
only.
Aspiration of fluid may be used for diagnostic purposes
and may be therapeutic for small collections. The needle
is removed after aspiration. Drainage catheters are left in
place to conduct fluid retrograde to an external collection device, typically a bag. These are placed in a cavity or
above an obstructing lesion. Stent catheters cross the obstruction and conduct fluid in an antegrade fashion, typi-
FIGURE 9-2. Drainage catheters. Drainage
catheters can be placed over a guidewire via the
Seldinger technique or primarily over a stiff trocar
(
left
). After trocar or guidewire removal, the pigtail
can reform. Note the placement of drainage side
holes near the tip only, on the inside of the pigtail
(
left, center:
pulled to lock the tip. The pigtail locking loop
center
(
room lock (
targets, such as nondilated intrarenal collecting
systems (CR Bard Inc., Covington GA; Boston
Scientific Co., Watertown MA, U.S.A.; Cook, Inc.
Bloomington, IN, U.S.A.).
sh). A self-retaining suture can be
) is compared with an Amplatz-type mush-
right
), which can be used in small
cally toward the anatomic recipient, such as duodenum
(biliary stent) or urinar y bladder (ureteral stent) (Fig. 9-3).
Stents can be entirely internal (double-J pigtail plastic
ureteral stent, biliary metallic stent, biliary Carey–Coons
plastic stent) (Fig. 9-4). Plastic stents must be exchanged
for new ones at regular intervals (usually 3 to 5 months).
If entirely internal, they are best changed from below
(endoscopically for biliary stents, cystocopically for
ureteral double-J stents) (Fig. 9-4). Metallic stents, which
are permanent, occlude from tumor progression or debris. They usually can be salvaged by balloon dilatation or
through–lumen placement of an internal–external plastic stent. Internal–external designs (e.g., nephroureteral
stents, internal–external biliar y stent) have an externalized portion that is easy to access for flushing and overthe-wire exchange; one typical use of such a device is
during a multistage procedure during which initial catheter placement encountered infected material or periprocedural bleeding and catheter flushing are necessary for
patency (Fig. 9-5).
Guidewires
Guidewires are used in three ways: The first is for access,
with the guidewire typically passed through the puncture
needle into the target. An angiographic catheter for directed manipulation or a drainage catheter then may be
sh
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Organ Access Techniques 105
sh
FIGURE 9-3. Placement of side holes. A partially opened 8Fr
left
external drainage catheter (
inner aspect of the pigtail. The 10Fr biliary drain (
strates side holes in the pigtail and for a distance down the
shaft to allow antegrade drainage through an obstructed segment. The self-locking suture is seen in the drainage pigtail
left, curved arrow
(
)
) has side holes (sh) on the
right
) demon-
placed after exchanging out the needle over the wire.
Typical access wires are 0.018 inches in diameter, allowing passage through a skinny needle or 0.035-inch to
0.038-inch stiff guidewires, such as the Rosen or Amplatz,
which are used with 18- and 19-gauge needles. Second,
various angiographic guidewires may be used with directional catheters for negotiation of the path to the target
site. Angled and straight-tipped 0.035-inch to 0.038-inch
hydrophilic and coil-spring guidewires (e.g., Bentson,
Cook, Bloomington, IN, U.S.A.) typically are used for
this purpose. Third, after the final site has been reached,
a stiff guidewire is used to exchange the angiographic
catheter for the drainage or stent catheter. The essential
properties of this wire are (1) sufficient length to accommodate removal of the catheter while positioned
and (2) sufficient stiffness to support the advance of the
large-bore drainage catheter. Typically, 0.035-inch Amplatz-type stiffwires or 0.038-inch Rosen guidewires are
used for this purpose.
FIGURE 9-4. Internal stents. Metallic flexible stent (
used for malignant biliary obstruction. Double-J pigtail stent
right
) used for internal uereteral drainage (Flexstent CR Bard,
(
Inc., Covington GA, U.S.A.; ureteral double-J stent, Boston
Scientific Corp., Watertown, MA, U.S.A.).
left
) often
■ General Procedural Principles: A
Summary
Preprocedural review of any relevant imaging study is
essential to planning the best potential approach. We
prefer retrograde endoscopic/cystoscopic stenting to
percutaneous drainage or stenting, if possible, because of
the lower risk of hemorrhage.
Visualization of the target organ may be accomplished
under CT, real-time US, or fluoroscopy. If fluoroscopy is
used, the approach is best made using a skinny needle to
enter and opacify the target organ. Residual infrarenal
contrast from a CT, intravenous urogram, or previous
retrograde stent attempt may be helpful. Multiple views
are obtained during contrast opacification for an adequate diagnostic study, if necessary. This may be the optimal time to delineate the nature of a stricture because
further manipulation (with possible bleeding or edema)
or passage of a stent may subsequently obscure the lesion.
Aspiration of diagnostic samples (e.g., for culture and
sensitivity) may be done at this time.
The passage of a drainage catheter with dilation of the
106 T. J. DiBartholomeo and C. W. Bakal
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sh
sh
FIGURE 9-5. Internal/external stent. Biliary stent (
side holes in pigtail and on shaft (sh). The nephroureteral stent
(
right
) has a self-locking loop pigtail for in the renal pelvis and
a distal pigtail for the bladder, with a long length of side holes.
For maximum bidirectional drainage, the external hubs may be
kept open to a bag; closing them allows antegrade internal
drainage, which, if successful, obviates the need for a collection bag. The external hubs allow exchange over a guidewire
or access for flushing.
left
) with
tract to 8Fr, 10Fr, or larger French sizes is best done
through a vascular parenchymal tract away from the central hilus, minimizing the likelihood of major bleeding.
Parenchymal tracts also help to hold catheters in place
and tamponade leaks. Posterolateral approaches through
Brodel’s avascular area into a renal calyx or peripheral
puncture of a biliary radicle are thus safest and optimal
for device placement.
It is also desirable for the organ entrance site to be at
some distance from the obstruction to allow for both
catheter manipulation and stent placement. Good stent
“purchase” well above the obstruction will allow a sufficient number of proximal side holes for drainage and will
allow for continued patency if there is subsequent retrograde malignant encroachment.
If the initial puncture is well positioned, it can be used
for placement of the drainage catheter or stent. A “onestick” system may be used to convert the skinny needle to
the drainage catheter. If the initial puncture is not optimal, the skinny needle is left in place and can be used to
opacify the target to optimize the second puncture under
fluoroscopy. A working wire is passed into the target to
allow dilation of the tract and placement of the drainage
catheter or stent.
During a drainage procedure, care must be taken to
minimize the risk of procedure-related septicemia.
7
Preprocedure antibiotics are usually appropriate (e.g., before biliary drainage). Overdistention of the target with
contrast should be avoided. Achieving rapid external
drainage is preferable to prolonged attempts at crossing
an obstruction for stenting, which increases the risk of
8
sepsis.
Stenting can be done at a second session. A 24- to
72-hour period of decompression usually allows better
delineation of the stricture, with easier cannulation and
stent passage. Conversion of an external drain to an internal stent is often straightforward. The drainage catheter is exchanged out over a stiff guidewire for a steerable
angiographic catheter. This catheter, in combination with
a standard or hydrophilic guidewire, can be advanced
through the obstructing lesion. The guidewire is replaced
by a stiff one, and the angiographic catheter is exchanged
for the stent, which is passed antegrade through the
lesion; predilation with a balloon is often needed before
stent passage.
In the biliary tree and urinary tract, stent placement is
usually preferable to external drainage for several reasons. First, it is more physiologic; for example, biliary-enteric circulation is preserved. Second, with internal stents
or internal–external stents that have long internal purchase, the problem of accidental catheter dislodgement
is alleviated. Third, the presence of an external appliance
and drainage bag may present a physical and psychological problem for the patient. Choice of a particular stent
type depends on clinical circumstances. Wholly internal
stents are generally preferred to internal–external devices; however, at initial placement, consideration must
be given to future maintenance. New biocompatible copolymers have increased plastic stent durability, but occlusion usually still occurs within 5 to 6 months, and all
stents eventually occlude.
9–11
In malignant biliary tract
disease with limited patient prognosis, inter ventional radiologists typically place a permanent metal stent because
the predicted stent durability is long relative to predicted
life span [e.g., Wallstent (Schneider, Inc.), Boston Scientific (Watertown, MA), Memotherm stent, (CR Bard Covington, GA, U.S.A.)]. Techniques have been devised to
recanalize occluded internal stents, but these typically
require repeat percutaneous puncture, especially with
nonampullary lesions.
12
Plastic internal stents, such as
double-J ureteral stents or Carey–Coons biliary stents,
typically are exchanged endoscopically from the bladder
Organ Access Techniques
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107
or duodenum; however, if anatomy precludes this, it may
be preferable to place an internal–external device, which
is amenable to flushing and exchange over a guidewire.
Covered metallic biliary prostheses may prove to enhance
durability and management of selected biliary lesions,
but their use is not yet widespread.
13
If the target site is small, or if careful positioning
through a narrow tract is necessary, a purposeful localizing puncture can be used. In this case, the target is
punctured directly with a 21- or 22-gauge needle, and
BD
contrast is administered to distend and opacify the system
gently or to elucidate a safer access point. Many interventionalists use this technique for percutaneous nephrostomy. The renal pelvis can be punctured directly from a
posterior approach and opacified. A sample of urine may
be aspirated for culture and sensitivity. The collecting
system may be opacified with contrast, and a suitable
peripheral puncture site is localized. In the kidney, this is
most frequently a lower pole, posterior calyx. Puncture
into a calyx provides an excellent track through renal
st
A
C D
FIGURE 9-6. A: External biliary drain (BD) in a patient with malignant obstruction of the biliary tree, left in place temporarily until
antegrade function of a metallic (st) stent could be confirmed. B: After removal of the drain, the patient developed hematochezia
arrow
and hyperbilirubinemia. Arteriogram demonstrates pseudoaneurysm of a right hepatic artery branch (
catheterization and embolization. D: The pseudoaneurysm is occluded by a sandwich of microcoils in the arterial branch distal
and proximal to the lesion (
arrows
). Symptoms and signs resolved.
). C: Superselective
B
108 T. J. DiBartholomeo and C. W. Bakal
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parenchyma, which is essential for catheter retention.
Access by a lower pole tract ensures that the relatively
large French drainage catheters or stents (8Fr or 10Fr)
are kept away from the renal vascular pedicle. Although
puncture of these structures is tolerated well when performed with the small, 21-gauge needle, passage of an 8Fr
or 10Fr catheter through the renal vessels will result in
significant hemorrhage.
The localizing puncture during percutaneous transhepatic cholangiogram and drainage likewise starts with
aspiration of bile and injection of contrast to select accurately a peripheral bile duct for puncture anticipating
drainage. Again, selecting a peripheral duct ensures a
parenchymal tract. Placement of a drainage catheter
through solid-organ parenchyma provides an anchor that
helps to hold the catheter in position. A localizing puncture is almost exclusively used with fluoroscopically
guided procedures, especially percutaneous transhepatic
drainage of the biliary tree and percutaneous nephrostomy placement. CT guidance and US guidance often
allow good visualization of the peripheral ducts or calyses,
obviating a preliminar y stick. Some interventional radiologists use US guidance for puncture of the bile ducts
for biliary drainage; with this technology, a single puncture of a peripheral duct can suffice both to obtain a
diagnostic cholangiogram and to place a drainage catheter.
After a wire is in adequate position, an external drainage catheter, internal–external stent, or internal stent is
chosen for placement. As stated, the choice of catheter is
based on the individual patient’s needs, the stage of the
procedure (i.e., awaiting definitive diagnosis and management), and the type of fluid to be drained. Typically,
infected fluid is first drained externally. An unresectable
pancreatic head tumor with symptomatic biliary duct obstruction may be stented primarily. Tenacious, purulent
material may require placement of a sump catheter or a
large 14F drainage.
Hypotension or other signs of procedure-related hemorrhage must be evaluated urgently. A CT may be obtained to confirm hematoma around the track or catheter site. Urgent selective or subselective arteriography
may be needed to assess whether there is an arterial
source of bleeding (extravasation, arteriovenous fistula,
or pseudoaneurysm) that can be treated by percutaneous
embolization.
14,15
The drainage catheter itself may obscure or tamponade such a lesion; a repeat arteriogram
with the catheter pulled back over a wire then should be
performed (Fig. 9-6). Other complications include sepsis
and pneumothorax. The interventional radiologist is obligated to be an active participant in the management of
these appliances.
7,8
Gentle for ward flushing with 5 to 10
mL of sterile saline every 8 to 24 hours will help maintain
catheter patency.
■ Conclusion
Percutaneous access to organs and body cavities is a mainstay of interventional radiology practice. These techniques permit safe, minimally invasive procedures for the
diagnosis and management of collections and obstructed
organ systems.
REFERENCES
1. Millward SF. Percutaneous nephrostomy: a practical approach. J
Vasc Inter v Radiol 2000;1:955–964.
2. Gerzof SG, Robbins AH, Johnson WC, et al. Percutaneous catheter
drainage of abdominal abscesses: a five-year experience. N Engl J
Med 1981;305:653–657.
3. VanSonnenberg E, Ferruci JT Jr, Mueller PR, et al. Percutaneous
drainage of abscesses and fluid collections: technique, results, and
applications. Radiology 1982;142:1–10.
4. Lang EK. Antegrade ureteral stenting for dehiscence, strictures,
and fistulae. AJR Am J Roentgenol 1984;143:795–801.
5. Cope C. Improved anchoring of nephrostomy catheters: loop technique. AJR Am J Roentgenol 1980;135:402–403.
6. Van Sonnenberg E, Mueller PR, Ferrucci JT Jr, et al. Sump catheter
for percutaneous abscess and fluid drainage by trocar or Seldinger
technique. AJR Am J Roentgenol 1982;139:6134.
7. SCVIR Standards of Practice Committee. Quality Improvement
guidelines for adult percutaneous abscess fluid drainage. J Vasc
Interv Radiol 1995;6:68–70.
8. Burke DR, Lewis CA, Cardella JF (SCVIR Standards of Practice
Committee). Quality improvement guidelines for percutaneous
transhepatic cholangiography and biliar y drainage. J Vasc Interv
Radiol 1997;8:677–681.
9. Cardella JF, Castaneda-Zuniga WR, Hunter DW, et al. Urine-compatible polymer for long-term ureteral stenting. Radiology
1986;161:313–318.
10. Mitty HA, Dan SJ, Train JS. Antegrade ureteral stents: technical and
catheter-related problems with polyethylene and polyurethane. Ra-
diology 1987;165:439–443.
11. Mitty HA, Rackson ME, Dan SJ, et al. Experience with a new
ureteral stent made of a biocompatible copolymer. Radiology
1988;168:557–559.
12. Cwikiel W. Percutaneous management of occluded biliary duct
endoprostheses. Acta Radiol 2000;1:338–342.
13. Petersen BD, Timmermans HA, Uchida BT, et al. Treatment of
refractory benign stenoses in liver transplant patients by placement
and retrieval of a temporary stent-graft: work in progress. J Vasc
Interv Radiol 2000;1:919–929.
14. Cope C, Zeit RM. Pseudoaneurysms after nephrostomy. AJR Am J
Roentgenol 1982;139:255–261.
15. Gardiner MF, Long WB, Haskal ZJ, et al. Upper gastrointestinal
hemorrhage secondary to erosion of a biliary Wallstent in a woman
with pancreatic cancer. Endoscopy 2000;32:661–663.
A.Rozenblit and S. I. WahlPercutaneous NeedleBiopsy and Drainage
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10
■■■
Percutaneous Needle Biopsy and Drainage
ALLA ROZENBLIT AND SAMUEL I. WAHL
The use of needle biopsy for nonoperative diagnosis became an acceptable diagnostic procedure in the 1930s,
but it gained wide popularity in the 1970s, when computed tomography (CT) and sonography became available to guide interventional procedures.
needles were large (16- or 14-gauge) and often placed
blindly for tissue diagnosis of diffuse liver disease and
palpable masses. With recent innovations in imaging techniques, instruments, and cytopathology, percutaneous biopsy now plays a significant role in patient care. Today,
needle biopsy is the most frequently performed interventional procedure in radiology practice.
the last two decades, percutaneous drainage (PD) has
become a widely accepted treatment for intraabdominal
abscesses.
The advantages of percutaneous procedures include
lower morbidity rates, the use of local rather than general
anesthesia, the elimination of surgical stress, shorter hospitalization, and decreased cost.
and some complicated abscesses can be completely and
permanently cured by PD. Other lesions can be treated
temporarily with resolved infection, but a curative surgical procedure still would be necessary to eliminate any
underlying cause. PD may render palliation, achieving
symptomatic relief and defervescene in patients with limited life expectancy who are not candidates for curative
surgery because of underlying comorbid conditions.
■ Procedure Planning
Because most biopsies and drainages are done under CT,
the following discussion concentrates on CT approaches.
4
1
The original
2,3
Similarly, in
Many uncomplicated
5
Many of these concepts also apply to ultrasound. Percutaneous biopsy and abscess drainage should be planned
on the basis of a recent high-quality diagnostic CT performed with intravenous (IV) contrast, which helps to
assess the vascularity of the lesion and to identify adjacent
vascular structures. Based on the available information,
diagnostic possibilities should be discussed with the referring physician to plan an appropriate procedure. If a vascular lesion, such as hemangioma, arteriovenous malformation, or aneurysm, is suspected, additional noninvasive
studies may be necessary for confirmation. All other lesions can be safely biopsied using at least a fine needle.
At the time of the procedure, a needle trajectory is
drawn on the chosen section, and the level is marked on
the scout view. In general, the shortest distance between
the skin and the lesion should be traversed. This rule,
however, is not always feasible because the shortest
distance to the lesion may cross anatomic structures
that should be avoided. Obviously, major vascular structures should be avoided, as should large nerves. The lung
should not be intentionally traversed for investigation of
subdiaphragmatic abnormalities. It is advisable not to
cross large muscle groups because they are vascular, and a
spontaneous muscle contraction may deflect the needle.
Unnecessary puncture of parenchymal organs, particularly the spleen, should be avoided. Liver parenchyma,
however, often is traversed with a fine needle for sampling
of porta hepatic lymph nodes and adrenal, pancreatic, or
biliary lesions as well as for gaining access to intrahepatic
collections. We avoid penetration of the large bowel, even
with fine needles, because of the possibility of infection.
Although the risk of infectious complications is low in the
immunocompetent population, a higher risk may exist
6
109
110 A. Rozenblit and S. I. Wahl
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for immunocompromised patients.
6,7
Small bowel, stomach, and duodenum can be traversed with relative impunity using a fine needle.
6,8
However, penetration of a hollow viscous with a large needle is inappropriate for tissue
sampling. Small bowel and transverse and sigmoid colon
often may be moved out of the path of the needle simply
by repositioning the patient from a supine to a lateral
decubitus position.
6
■ Preprocedure Patient Evaluation
Referring physicians and careful chart review by the radiologist usually provide patient history and determine the
presence or absence of serious concomitant conditions,
such as cardiovascular, pulmonary, or neurologic disorders, as well as the ability of the patient to cooperate. We
do not perform biopsies or drainages in an uncooperative
patient without general anesthesia. Aspirin and other
medications that potentially could alter coagulation and
platelets should be discontinued one week prior to the
scheduled procedure. Percutaneous procedures can be
performed safely at any hematocrit level when coagulation is normal. When the hematocrit is below 32% or
coagulation is abnormal, the risk of bleeding has more
serious consequences. Patients with a history of abnormal
bleeding and those with known clotting abnormalities
also pose a higher risk. Most radiologists screen all patients for prothrombin time (PT), partial prothrombin
time (PTT) and a platelet count. An acceptable PT is
within 2 seconds of normal, PTT within 25%, and a platelet count above 70,000. When these parameters deviate
from the acceptable levels, hematology consultation and
appropriate corrective measures are mandated.
The patient is required to fast after midnight before
the procedure. When the patient arrives in the radiology
department, the procedure, alternatives, possible complications, and benefits are discussed, and the patient signs
an informed consent form. A brief medical histor y is
obtained, and vital signs are recorded. Prior to the procedure a peripheral IV line is placed. Anxious patients are
premedicated according to the institutional conscious
sedation protocol; however, this is rarely required for
biopsies and actually may alter the patient’s ability to
cooperate. During the procedure, the patient’s pulse rate
and oxygenation are monitored by means of a pulse
oximeter. Prior to percutaneous abscess drainage, patients should intravenously receive broad-spectrum antibiotics.
■ Percutaneous Needle Biopsy
Indications for percutaneous needle biopsy include (1)
diagnosis of primary or metastatic malignancy in a newly
discovered mass, (2) diagnosis of tumor recurrence in
patients with known malignancy, (3) diagnosis of infection, and (4) diagnosis of benign disease. Common contraindications include (1) uncorrectable coagulopathy,
(2) inability of the patient to cooperate, (3) a patient with
uncontrollable cough (lung biopsy), and (4) lack of a
safe needle path (with large–gauge needles).
Procedures and instruments
Percutaneous needle biopsy requires the accurate positioning of a needle into a lesion to obtain an adequate
sample representative of the lesion. A sample can be
obtained by either aspiration of pathologic material or by
the mechanical cutting of tissues without suction. Typically, aspiration biopsy is performed with fine needles,
most commonly 20- to 22-gauge, and is referred to as
fine-needle aspiration biopsy (FNAB). A nonaspiration fineneedle technique (i.e., cutting tissue without the use of
suction) may play a role in the diagnosis of extremely
vascular lesions; otherwise, the aspiration technique is
preferred for abdominal biopsies.
FNAB is performed using needles with a variety of tip
and stylet designs intended to improve diagnostic yield
(Fig. 10-1). Some needles have blunt or beveled tips without cutting edges (aspiration needles) and are suitable
for sampling practically any lesion.
have sharpened tips that can be hooked, notched, spiraled, or trephined, and they often are better for recovering diagnostic material from firm hypovascular masses.
Needles with a beveled tip tend to recover better samples, because the small angle of the bevel allows superior
diagnostic material to be obtained.
ever, tend to deviate along the direction of the slant.
Chiba and spinal needles appear to be a viable compromise.
The aspirated material then undergoes cytologic
evaluation and occasionally is sent for histologic analysis
when tissue fragments are present. Histologic material is
more commonly obtained by using end-cutting rather
than aspiration needles. Generally, the larger the needle,
the greater the yield of diagnostic material.
investigators reported higher diagnostic yields, without
additional complications, using 20-gauge needles rather
than 22- or 23-gauge needles.
tures, such as liver, stomach, small bowel, and small vessels, are unavoidable, fine needles can be safely directed
into the target lesion through these structures.
choice of a specific needle depends on the size, location,
and vascularity of the lesion; the presence of intervening
structures along the needle path; the amount of tissue
required to satisfy diagnostic considerations; and the experience and preference of the operator. The Franseen
and Westcott needles have the best overall performance,
closely followed by the spinal needle.
9
2
End-cutting needles
10
Such needles, how-
12,13
When overlying struc-
15
6,11
Several
8,14
The
Percutaneous Needle Biopsy and Drainage 111
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FIGURE 10-1. Various 22-gauge needles used for cytologic biopsies. (A) Chiba. (B) Spinal. (C)
Turner. (D) Franseen. (E) Madayag. (F) Westcott.
Usually, FNAB is sufficient for the diagnosis of carcinoma and recurrent malignancies as well as sampling of
fluid. For the diagnosis of lymphoma, unusual tumors, or
benign disease, however, large-bore cutting needle biopsies (LNB) are considered more accurate.
16–18
This technique provides a sufficient histologic specimen while preserving the architecture of the lesion; however, the
potential risks to the patient increase in quadratic proportion to the diameter of the needle.
19
A variety of
needles ranging from 14 to 19 gauge can be used for
cutting biopsy and frequently are divided into end-cutting and side-cutting types. The former requires application of suction either by a syringe or a self-aspirating
device, and the latter cuts along a gap in the inner stylet
while an outer needle slides over the stylet, similar to a
Tru-cut needle. Both the stylet and the outer needle can
be moved manually or by using automated spring-loaded
biopsy gun devices. In general, a superior specimen can
be obtained by using side-cutting needles compared with
end-cutting needles.
Automated biopsy devices consistently provide highquality diagnostic tissue with minimal patient discomfort
and no significant increase in the complication rate compared with FNAB.
16,17,20
There is a variety of commercially available automated biopsy devices with different
loading and safety mechanisms and with different throw
lengths. Some devices have an adjustable throw ranging
from 1 to 2 cm that can be tailored to the lesion size.
Many automated biopsy gun devices are packaged with
guiding cannulas for coaxial insertion of the needle. Instructions should be studied carefully before any new
device is used. Some of these devices are unacceptably
bulky and cumbersome, but overall automated devices
are easy to use and consistently provide good-quality histologic specimens. We prefer an 18-gauge biopsy gun,
which has a strong spring mechanism and is light weight,
requiring no added support, with an optional feature of
coaxial insertion and suitable for lesions of variable
depths (Fig. 10-2).
Imaging guidance
FIGURE 10-2. An example of a spring-loaded 18-gauge core
biopsy needle.
Percutaneous biopsy can be performed with fluoroscopic, sonographic, CT or occasionally magnetic resonance imaging (MRI) guidance.
21
The choice of imaging
depends on the ability of the modality to visualize both
the lesion and the needle with adequate depiction of the
surrounding anatomy as well as the experience and per-
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sonal preference of the radiologist and the availability of
the equipment.
Fluoroscopy is a simple, fast, cost-effective, real-time
technique used primarily for lung lesions that are well
visualized in the frontal and lateral views. For small, difficult, ill-defined, or anatomically challenging lesions near
the hilum or mediastinum, CT is the method of choice.
Most abdominal biopsies are best performed with ultrasound or CT because these lesions cannot be visualized
by fluoroscopy.
Previously limited to the liver and superficial lesion
sampling, ultrasound guidance is currently being used
with considerable success to biopsy lesions throughout
22,23
the abdominal cavity and certain chest lesions.
Ultrasound is less expensive and often less time-consuming
than CT, and its multiplanar capability allows for needle
passage in any plane in real time.
The procedure can be performed by using a freehand
technique, a dedicated biopsy transducer, or biopsy
24
guides attachable to a regular transducer.
Motion and
high-level echoes from the needle tip indenting adjacent
tissues should be observed during the needle placement.
A number of technical innovations and needle designs
that improve visualization of the needle have been re-
25–27
ported.
Despite recent advances in ultrasonographic
(US) guidance, the basic limitations still are related to
difficulties in visualization of the needle tip, poor acoustic windows, interposed bowel gas, and large patient size.
6,28
In our experience and that of others,
CT is the most
effective modality for accurate needle biopsy, allowing
visualization of most lesions and surrounding anatomy,
therefore providing a safe biopsy route. The entire needle is readily visible on CT, allowing precise sampling of
small and difficult lesions in complex anatomic regions
such as the pelvis and retroperitoneum or near major
vessels in the chest and abdomen. Repeat of previously
failed biopsy should be performed with CT guidance to
ensure the accuracy of needle placement. The disadvantages of CT guidance include high cost, often long procedure time, inability to scan in real time, and the limitation
of a single scanning plane.
Biopsy techniques
Localization
The patient is placed on the CT table in a comfortable
predetermined position that is appropriate for the
planned needle insertion. Several axial sections are obtained that include the lesion. The proper level is marked
on the skin with the gantry laser light, and the lesion’s
projection on the skin is marked with a radioopaque
marker (e.g., a paper clip or a commercially available,
thin radioopaque grid). The position of the marker is
verified on subsequent images and corrected if necessary
to obtain the optimal entry point (Fig. 10-3). After sterile
skin preparation, the entry site is infiltrated with 2%
lidocaine to the level of the peritoneum, organ capsule,
or pleura. All subsequent needle manipulations within
the thoracic and abdominal cavity should be performed
with suspended respiration to prevent a tearing effect of
the needle tip.
A biopsy needle then is inserted into the lesion either
by a single pass for superficial lesions or with incremental
adjustment of depth and angulation for more difficult
masses. To correct for inaccurate angulation, the needle
should be withdrawn completely before any adjustment is
made. After each adjustment, the position of the needle
tip is radiographically verified. In-plane biopsies include
A B
FIGURE 10-3. Single axial computed tomography image through the liver. (A) Radioopaque markers in preparation for percu-
taneous needle biopsy of a low-attenuation liver lesion. Note the mass in the pancreatic tail. (B) Needle tip is positioned well
within the liver lesion.
Percutaneous Needle Biopsy and Drainage 113
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lesions located at the same axial level as the skin entry
plane. The procedure is simple; if any angulation is required, it is easily achieved in the same axial plane. In
general, three 5- or 10-mm sections are obtained to verify
the needle position.
Out-of-plane (angled) biopsies involve the sampling of
lesions located above or below the skin entr y point; thus,
angulation in the longitudinal plane is required to reach
the target. Often, additional angulation in the axial plane
is also necessary. This procedure is more demanding and
often lengthy because multiple adjustments of the needle
are often required. Angulation of the scanning gantry
may help to bring both the lesion and the needle in the
same oblique plane, avoiding intervening structures.
29,30
A longitudinal angle can be calculated using a “triangulation method”; however, it is difficult to implement
precisely; therefore, this calculation is not practical.
Commercially available needle-guiding devices can be
used for proper angulation. Increased accuracy and safety
with these devices have been reported.
31–33
Stereotactic
devices for abdominalbiopsy have shown a decreasein the
number of needle manipulations by 75% and procedure
time by 50% compared with hand guidance,
34
but stereo-
tactic systems are expensive and may be difficult to use.
Hand guidance, most commonly used for out of plane
procedures, requires experience.
6
We simply estimate the
longitudinal angle evaluating sequential images. Once
the angulation in the axial plane is correct, the needle is
angled longitudinally and then moved incrementally toward the lesion. To verify the needle tip position, sequential images should be obtained from the needle entr y
point to at least 10 mm past the lesion. Sometimes four
or more sections are needed to visualize the needle in its
entirety. Sonographic guidance is often a better alternative for angled procedures.
To improve the efficiency and accuracy of multiple needle placements, a coaxial technique can be used for both
FNAB and LNB, including automated devices.
6,7
First, a
short guiding cannula is inserted in the body wall and
adjusted to achieve the proper direction. Then a biopsy
needle is placed through the cannula to the desired depth.
FNAB sample
With the needle tip in satisfactory position, the stylet is
removed, and a 20-mL syringe is attached to the needle;
5 to 10 mL of suction is applied while 1- to 2-cm quick,
vigorous excursions are made through the lesion with
some rotation of the needle. Suction can be maintained
or slowly released during withdrawal of the needle. The
aspirated material is expelled from the needle onto glass
slides for cytologic smears and immersed in 95% alcohol
for fixation prior to staining. The specimen should be
examined by a cytopathologist in the biopsy suite. The
aspirated syringe content is rinsed for cell-block preparation that is processed as a histologic specimen. Any tissue
fragments are immersed in a 10% buffered formalin solution for histologic processing.
Multiple passes are often necessar y to obtain diagnos-
tic material.
35,36
We limit the total number of passes to
four. Regardless of the needle tip configuration, four
passes with a 20-gauge needle yield diagnostic material in
95% of cases.
15
Large-needle biopsy sample
At least one fine needle pass usually precedes LNB for
obtaining cytology and as a test for lesion vascularity.
Extremely vascular lesions are not sampled with large
needles.
Once a large end-cutting needle is passed into the lesion, aspiration techniques are applied in a similar manner as FNAB. A side-cutting needle is placed at the margin
of the lesion, and the position is checked. In some automated devices, the instrument is ready to fire at that time,
and so the position of the cutting portion of the needle
within the lesion cannot be verified. In other devices, the
position of the inner stylet can be documented (and repositioned if necessary) after it is manually moved into the
lesion. The obtained material is processed histologically.
Diagnostic yield
Image-guided percutaneous biopsy is an accurate procedure. The diagnostic accuracy varies because of differences in technique, the needles used, and the organ and
lesions sampled. The range of sensitivities and specificities of CT-guided biopsies in general is 73 to 93% and 81
to 100%, respectively.
37,38
Complications
The overall reported complication rates for abdominal
6,39
needle biopsy range from 0 to 3%,
with minor bleeding the most frequent and common complication; infection, pancreatitis, and pneumothorax are less common.
Fatalities and needle-tract tumor seeding have been reported only rarely. One multiinstitutional survey of
16,381 biopsies reported 33 deaths related to FNAB,
including 21 liver, 6 pancreatic, 2 adrenal, and 4 miscellaneous biopsies; the mean mortality rate was 0.031%.
For cutting needles, serious complications are more
common; however, a similar mortality rate of 0.027% was
reported in more than 11,000 abdominal procedures.
Seeding of malignant cells via the needle tract has been
reported in 0.003 to 0.009% of FNAB, more commonly
with renal cell carcinoma and pancreatic and musculoskeletal masses.
40
Specific biopsy sites
Chest
Patient cooperation is absolutely essential when obtaining a chest biopsy because the patient must suspend res-
40
41
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