Interventional Wolfgang F. D#{228}hnert, MD #{149}Melissa Heller Yener S. Erozan, MD #{149}John C. Peirce, MD

Fine-Needle

Lesions: Needle

Hoagland,

Aspiration

Yield

N

Radiology

770.126

MATERIALS

An abdominal biopsy 133 patients; 551 needles

the Departments of Radiology (W.F.D.) and Medical Education and Research (J.C.P.), Good Samaritan Regional Medical Center, 1111 E McDowell Rd, Phoenix, AZ 85006; the Division of Anatomic Pathology, Milton S. Medical

Center,

Hershey,

Pa (M.H.H.);

METHODS

and

adrenal

was performed on were used. There

glands

in six. Among

lesions, 101 (80.8%) were malignant. Table 1 summarizes the distribution of bi125

specimens of lesion.

according

to organ

and

and

Number

of Passes

(PercuCut;

E-Z-Em,

an interior

diameter a 20-gauge

Westbury,

NY)

of 0.03025 Franseen

inch

with ±

trephine

and the Departments of Radiology (U.M.H.) and Pathology (Y.S.E.), The Johns Hopkins Medical Institutions, Baltimore. Received October 18, 1991; revision requested December 26; final revision received April 24, 1992; accepted May 12.

± 0.00075 (2), a 20-gauge spinal needle with an interior diameter of 0.02625 inch ± 0.00075, and a 20-gauge

Address reprint C RSNA, 1992

Westcott diameter

requests

to W.F.D.

0.02375

with inch

type

to the

in a manner

number

an interior

diameter

sheets were assigned a

of needle

pass

that all needles had an equal of being used for the first, sec-

probability

ond, third, and fourth passes. The work sheets were mixed and selected randomly, dictating

the

needles

sequence

were

to be

All physicians

in which used

the

in each

agreed

four

patient.

to follow

the Se-

quence of needles established by the protocol without preferential use of any one needle

type.

However,

violated

to react

interpreted

tient’s

at the

the biopsy

discretion,

on

to the site,

compliance,

technical

physician’s

protocol results

could

to respond

such

difficulties

to the

to account

and

be

of smears pa-

for

as intestinal

gas

moving between the transducer and the target, thus obscuring the lesion for subsequent needle passes. These circumstances changed the number of total passes made per patient

(Table

2). The

median

and

modal number of passes was 4, with a mean of 3.93 passes per patient. In 29 passes, 21-, 22-, or 23-gauge neewere

used

because

smears

made

from

samples obtained with the protocol needles were assessed on site as blood only. Some physicians thought that smaller needie gauges might improve the ratio of tissue elements to blood. smaller needle gauge

that was not already passes

made

with

In retrospect,

added present

the

information in previous

the protocol

needles

in

only one biopsy. We offer the following explanation: When blood appears in the needle hub, it will have flushed tissue elements already in the syringe. Because material aspirated at the end of a needle pass onto the slide, blood, whereas

of

slotted needle with an interior of 0.02625 inch ± 0.00075 (3). At

the

the diagnostic material ends up in the solution from the syringe. Passes with smaller caliber needles were excluded from the analysis. Table 3 lists the frequency of the 522 protocol needles used in a given pass. The relative frequency in each needle category rinse

four passes per lesion. These needles included a 19.5-gauge cut biopsy needle

needle

needle

of this project, work that systematically

is the first to be expelled smear may only contain

Four types of needles were designated to be used in every patient for a total of

0.00075,

the onset developed

dles

were 75 women and 58 men ranging in age from 18 to 86 years (mean, 61 years). Organs involved were the liver in 49 patients, pancreas in 40, lymph nodes in 21, kidneys in eight, gastrointestinal tract in

type

1992; 185:263-268

AND

Population

opsy

From

Hershey

for Different

aspiration biopsies of solid tissue lesions are part of the expected capability of cross-sectional imagers. For this task, the radiologist has to select an appropriate needle to provide tissue that is representative of the lesion and is adequate to establish its nature. There are a number of biopsy needles with different lip configurations. Fresh cadaver liver tissue has been used to show that certain cutting tips yield the best overall biopsy samples in the laboratory (1). However, we were not convinced that these laboratory results could be transferred directly to the clinical setting. We, therefore, selected four needles with different lips but similar gauge to assess the effect of tip configuration on the diagnostic yield in patients undergoing needle aspiralion biopsies of abdominal masses.

Needles

I

MD

of Abdominal

EEDLE

nine, Index terms: Abdomen, biopsy, 70.126 #{149}Biopsies, technology #{149} Liver, biopsy, 761.126 biopsy,

M. Hamper,

Configurations’

Four fine-needle aspiration biopsy needles with different tip configurations were used in 133 patients with abdominal lesions. The 20-gauge needies were used in random sequence by several physicians. The specimen from each of the 522 needle passes was evaluated by two cytopathologists for adequacy to render a diagnosis and for the presence of cell block material. The Franseen needle produced a 16% and 9% better yield for diagnostic material than did the cut biopsy and spinal needles (P < .05), respectively. The Westcott needle was better than the cut biopsy needle by 13%, and the spinal needle produced an 11% better yield than did the cut biopsy needle. Differences did not exist in liver biopsies but were present in pancreatic biopsies. The spinal needle was the least successful in yielding cell block material. Use of the cut biopsy needle restilted in the largest proportion of inadequate specimens, except its yield in cell blocks in the liver was 25% higher than that of the Westcott needle. The authors conclude that not all unusual designs for 20-gauge needle tips render results superior to those of the simple spinal needle.

Pancreas,

#{149}Ulrike

Biopsy

Diagnostic Tip

MD

Radiology

deviates

slightly

from

the

of 25% but does cal significance. quency

expected

fre-

not reach

statisti-

Technique Biopsies cians

with

were varying

performed by 16 physilevels of expertise (ie,

Table

Table 1 Distribution

of Biopsies

by Diagnostic

Category

and

Organ

Lymph Liver

Diagnosis

Primary

neoplasm

9

Metastasis

lesion

13

Patients

without

Gastrointestinal

Adrenal

Tract

Gland

Kidney

9 11 1

7 1 0

5 2 1

2 2 1

3

0

0

1

1

8

40

21

8

9

6

133

or follow-up

to establish

specimens

dles. All physicians

were

instructed

Total No.

Passes

Patients

of Passes

1 2 3 4

4 3 22 83

4 6 66 332

5 6

12 9

60 54

Total

133

Note-Needle needles

passes (n were used

a final diagnosis.

of our 133 patients

opsy

with

ance.

The needle

vanced

to the edge of the the patient suspended

computed

underwent tomography

and stylet

and

Needle

1 2

25 (4.8) 29 (5.6)

34 (6.5) 36 (6.9)

3

43 (8.2)

17 (3.3)

5

24 (4.6) 30 (5.7) 5 (1.0)

31 (5.9) 37 (7.1) 30 (5.7) 29 (5.6)

11 (2.1)

2 (0.4)

3 (0.6)

6

3 (0.6)

5 (1.0)

1 (0.2)

0

116 (22.3)

146 (28.0)

130 (24.9)

Total

W 43 27 29 28

21-

Total

(8.2) (5.2) (5.6) (5.4)

133(25.4) 129(24.8) 126(24.1) 104(20.0) 21 (4.1)

9(1.8)

130 (25.0)

Note-Numbers in parentheses are percentages. C = 19.5-gauge cut biopsy Franseen needle, S = 20-gauge spinal needle, W = 20-gauge Westcott needle. *Numbe do not add to 100.0 because of rounding.

ad-

for which are excluded.

= 29)

Type

S

the

guid-

were

Pass F

4

bi-

by Needle

C

vast majority of patients underwent with ultrasound (US) guidance.

Nine

of Needles

Pass

technique.

The biopsy

522

3

Distribution

in the

use of a standardized biopsy technique and acquainted with the manufacturer’s instructions when these altered from

standard

Table

per Patient

s

No. of

23-gauge

sonography staff, as well as fellows and residents with supervision). The purpose of this approach was to obtain data for the “average radiologist” and to eliminate the effect of any single physician who had particular experience with one of the nee-

Passe

No. of

58 43 24

3

adequate

eedle

of

Total

49

Unknown* Total

Node

26 3 8

24

Benign

*

Pancreas

2

Number

Site

522 (100.2)*

needle,

F = 20-gauge

target lesion respiration.

while The patient was asked to resume shallow breathing while the stylet was removed and a 20-mL syringe was attached to the hub of the needle. Suction was applied by withdrawing the plunger of a pistolgripped syringe holder (Precision Dynamics, San Fernando, Calif) all the way. Again, while the patient suspended respi-

immediate

ration,

rinsed with Hank’s balanced salt solution (Gibko, Grand Island, NY). The rinse solution was processed in the cytopathology laboratory according to the protocol for fluids, which included the Millipore (Miffipore Products, Bedford, Mass) and Gelman ifiters (Gelman Sciences, Ann Arbor, Mich), cytospin, and cell block (if there was adequate sediment) preparations. Cell blocks were also fixed in buffered formalin. Both cell blocks and tissue fragments that had been obtained previously were processed as small tissue biopsy specimens (ie, embedded in paraffin, sectioned, and stained with hematoxylin-eosin) and are

the needle

lesion

while

with

was advanced

a drilling

the pistol

grip

motion by

simply

into the was

exerted

moving

the

hand from pronation to supination. Needle advancement was judged according to the predetermined size of the lesion but was usually not monitored with real-time imaging. The needle was then retracted approximately to the initial position while rotating the hand from supination back to pronation. This rotatory “in-

and-out” motion was rapidly repeated three times or, alternatively, aborted when blood

or tissue

needle.

Each

advancement proximately was

appeared

drilling

in the hub

motion

and retraction I second. Before

completely

withdrawn

with

of the

needle

from

the

body,

suction was the plunger

released by slowly releasing to the point of equilibrium.

Specimen

Preparation

needle

hub.

Some

were

Diff-Quik

264

(Baxter

Radiology

#{149}

air

dried

Healthcare,

stained

Miami)

and needle

to in this study

samples were marked rately for each needle

All material

and

(Y.S.E.),

from

with

for

and

a consensus

was

diagnosis, marginal (suboptimal preservation or quantity of material nonetheless sufficient to render a diagnosis), or madequate. Second, the presence or absence of a cell block was noted on each pass, because, from the pathologist’s viewpoint, the presence of a cell block with diagnostic

in the syringe

Cytopathologic

the needle and syringe was expelled onto four glass slides, and cellular spreads ( smears) were made. Two of the cellular spreads

pathologist

specimen

pendently

of the material

evaluation

was

as cell blocks. and handled pass.

All sepa-

adequacy

material

from evaluated,

each first

pass by

was an

inde-

(additional

stains,

as to specimen

the followspecimen

as adequate

since

it allows

tissue

levels,

was graded

present

that

abled

a correct

tissue

Each

as diagnostic

provided

was

that

en-

for that pass),

(quantitatively

adequate

but not contributory

diagnosis), consisted fragments

cell

(tissue

material

diagnosis

nondiagnostic

ancillary

special

immunohistochemistry).

block

for

to the correct

or no tissue present (cell block only of fresh blood or no tissue were present). Finally, each then

graded

“yes”

definitive

material from diagnosis.

Statistical

Analysis

that

or “no”

pass

as to

enabled

a

experi-

enced cytotechnologist and then by a cytopathologist (M.H.H.). In all cases in which there was disagreement with the cytotechnologist

in each case, were evaluated:

is helpful,

studies

pass

Evaluation

pass

was assessed

whether

After each pass, the syringe was detached, filled with air, and reattached to the

microscopic

reached. With each ing parameters

referred

lasted apthe needle

on-site

for adequacy of the specimen. The other two slides were fixed in 95% ethyl alcohol and later stained with modified Papanicolaou stain in the laboratory. The remaining

adequacy,

evaluation of preparations (smears, filters, cytospin, cell blocks), or diagnosis, the matenal was reviewed by the first cytopathologist (M.H.H.) and then a second cyto-

Specimen adequacy of each needle was matched with that of each of the other

three needles adequacy was adequate, the marginal but matched

pairs

for each patient. Specimen assessed as inadequate and latter category containing interpretable results. The were compared by calculat-

ing the differences

(Y

-

Y2) in the proporOctober

1992

of patients who underwent a nondiagnostic pass i - I and a diagnostic pass i/number of patients who underwent a nondiagnoslic pass i - I and who underwent pass i, where D = diagnostic pass and N =

Table 4 of Diagnostic

Distribution

Yield by Needle

C(n=116) Pass

a

Type

F(n=146)

m

i

a

and Number

of Pass

S(n=130)

m

i

a

W(n=130)

m

I

a

m

i

Total

nondiagnostic

pass.

The cumulative 1 2 3

12 11 15

7 8 4

6 10 5

18 21 20

11 12 14

5 3 9

22 19 15

3 7 8

6 11 7

24 16 12

14 6 10

5 5 7

4

13

5

12

9

2

6

18

7

4

15

8

5

5

2

1

2

5

5

1

1

1

0

1

2

0

132 128 126 104 23

6

0

1

2

2

2

1

0

1

0

0

0

0

9

53

26

37

75

46

25

75

27

28

68

40

22

Total Note-a

= adequate

specimen,

i = inadequate

specimen,

m = marginal

522

See Table 3 for

specimen.

other abbreviations.

pass

(the

ith

Data Comparing

Needles 1 vs 2 F vs C

w

vs C S vs C F vs S

w vs S F vs W

Specimen

Adequacy

of Needles

ii

Yl

Y2

105 105 103 105

0.85 0.83 0.80 0.89

0.69 0.70 0.69 0.80

0.16 0.13 0.11 0.09

105 105

0.84 0.88

0.79 0.86

0.05 0.02

(Y1

-

in All Biopsies

calculated

number diagnostic

as fol-

of patients specimen

=

on

pass 1 through i/number of patients who underwent at least i passes. We calculated

the mean of the conditional probabilities on the six passes and used this mean as the expected probability for each of the probabilities.

Y2)

95% CI (0.06, (0.03, (0.00, (0.00,

P

0.26) 0.24)

pass is listed of adequate

.002

.013 .048

0.21) 0.17) 0.15) 0.11)

(-0.05, (-0.07,

The diagnostic yield of each different needle type as adequate, marginal, or inadequate for each separate

.050

.353 .683

Note.95% Cl = estimate of the 95% confidence interval of the difference in the yield of needle 2 minus needle 1, first needle listed = high-yield needle, n = number of patients who underwent biopsies with both needles, P = P value of the McNemar test for equality of the needles’ yield, Y1 = observed yield of needle 1 in the matched sample, Y2 = observed yield of needle 2 in the matched sample, (Y1 - Y2) = observed difference in the yield of needle 2 minus needle 1 in the matched sample. See Ta-

ble 3 for other abbreviations.

of patients,

Data

Cell Block

Comparing

Yield of Needles

in All Biopsies

was was

Needles I vs 2

n

Y1

Y2

(Y1 - Y2)

F vs S F vs W vs S F vs C C vs S C vs W

105 105 105 105 103 105

0.52 0.51 0.44 0.50 0.47 0.49

0.38 0.46 0.39 0.47 0.44

0.14

w

Note-See

tions of adequate biopsy tween needle 1 O’) and

the following

equations:

specimens

be-

Needle 1 always has the greater proportion of adequate biopsy specimens. Y2 = (a + c)/n and (Y - Y2) = (b - c)/n, where a = the number of concordant pairs with an adequate yield, b = the number of dis-

cordant pairs when needle 1 had an adequate specimen and needle 2 had an madequate specimen, c = the number of

of pairs.

Ninety-five

percent

confidence

intervals

for the difference in proportions was calculated with the following equation (4): (Y1 - Y2) ± 1.96 \/n[(b + c) - (b - c)2]/

185

Number

#{149}

1

(0.02, 0.27) 0.17) (-0.08, 0.18) (-0.08, 0.16) (-0.09, 0.15) (-0.12, 0.13)

0.04

0.03 0.01

that

.475 .537 .639 .881

(n\/n). The null value for the confidence interval (ie, the value corresponding to the null hypothesis that the needles have identical tion)

diagnostic is .00.

The

yields probability

in

the

popula-

of falsely

re-

jecting this null hypothesis (the P value) was calculated with a McNemar x2 test (5). Results were considered statistically significant if P was less than .05. In addition, we analyzed our data to determine whether the number of the pass

made

a difference

in

the

probability

of obtaining a definite diagnosis. We calculated P(D1 IN1), the conditional probability of a specified pass (the ith pass) being diagnostically successful given that the previous pass (the i - 1 pass) had not yielded

following

diagnostic

equation:

material,

by

16%,

in Tables

5 and

Westcott, and spinal attain significantly of adequate speci13%,

and

by

using

P(D11N11) =

no difference compared

with

11%,

when the

and the Franseen with needle. The significant

.032 .343

and explanations.

needle 2 (Y2) with Y1 = (a + b)/n.

pairs when needle 2 had an specimen and needle I had an specimen, and n = the total

P

(-0.06,

0.05

0.48

Tables 3 and 5 for abbreviations

95% Cl

0.06

as shown

6. The Franseen, needles helped larger proportions

respec-

lively, compared with the cut biopsy needle. The Franseen needle was superior to the spinal needle by 9%, just reaching statistical significance. There

Table 6 Matched

in Table 4. The categories and marginal designate

that there were diagnostic results, whereas the category of inadequate indicates that there was insufficient material for evaluation. There were 103-105 matched pairs

mens

Volume

was

Cum

for a specified

RESULTS

Table 5 Matched

number

result

pass)

lows: Cum P(D,) with at least one

cumulative

discordant adequate inadequate

probability,

P(D1), of a diagnostic

the

number

existed

for

the Westcott spinal needle

the Westcott differences

specimen

adequacy

were not duplicated in the subset of cell block yield (Table 6), except that the Franseen needle was superior to the spinal needle by 14%. Among the abdominal organ sites, liver and pancreatic biopsy specimens were sufficient in number to allow for a separate evaluation. There were 37-44 matched pairs of liver biopsy specimens (Table 7) available for analysis.

No

than

the others. matched

32-39 opsy

needle

specimens

was

clearly

better

In contrast, in the pairs of pancreatic bi(Table

8), the

West-

cott and Franseen needles were significantly superior to the cut biopsy needle by 29% and 24%, respectively, and the Westcott needle was superior to the spinal needle by 19%. With the pancreatic specimens, the proportion of adequate specimens was of a lower magnitude than that seen with all specimens when comparing the spinal needle to the cut biopsy needle (16%) and the Franseen to the spinal Radiology

#{149} 265

needles (10%); however, because of the low number of matched pairs, there was insufficient power to detect a significant difference. With regard to cell block yields, the Franseen needle was superior to the spinal needle (Table 9) in pancreatic biopsy specimens (by 28%), as it had been in all of the biopsy specimens. This was not imens (Table

true 10):

in liver The cut

biopsy biopsy

Table 7 Matched

specnee-

with

the

first

needle

pass,

with

marginal increases of 21 % with the second needle pass, 8% with the third needle pass, 6% with the fourth needle pass, 2% with the fifth needle pass, and 1 % with the sixth needle pass.

Two

specimens diagnosis probability rial

was

percent

.61,

.56,

translates

tional

.67,

one into

probability

pass

.46,

passes

.75,

and

through

an

in Liver Biopsies

C vs W S vs W F vs C

40 44 37

0.83 0.84 0.86

0.75

0.08

(-0.07,

0.22)

0.77

0.07

(-0.08,

0.81

0.05

(-0.07,

0.21) 0.18)

.317 .366 .414

S vs C

38

0.87

0.82

0.05

(-0.11,

0.21)

.527

F vs W F vs S

42 42

0.86 0.82

0.81 0.82

0.05

(-0.10, (-0.13,

0.19) 0.13)

.527 1.000

w

Tables 3 and 5 for abbreviations

Data

Comparing

and

Specimen

n

Y1

95%CI

(Y1-Y2)

0.00

P

explanations.

Adequacy

of Needles

in Pancreatic

Biop sies P

Y2

(Y1 - Y2)

95% CI

vs C

34

0.88

0.59

0.29

(0.10, 0.49)

F vs C w vs S

33 37

0.82 0.92

0.58

0.24

(0.04,

0.73

0.19

S vs C vs F

w

32 38

0.72 0.92

0.56 0.82

0.16 0.10

F vs S

39

0.82

0.72

0.10

(0.02, 0.35) 0.35)

.008 .033 .035 .157

0.26) 0.24)

.206 .549

(-0.04, (-0.05, (-0.04,

0.45)

.33

six.

average

of Needles

Y2

Needles 1 vs 2

had

Adequacy

Y1

TableS Matched

that were inadequate for a (Figure). The conditional to yield diagnostic mate-

for needle This

of patients

Specimen

n

Note-See

dle was superior to the Westcott fleedle by a yield difference of 25%. Material adequate to enable a definite diagnosis was obtained in 61 % of cases

Data Comparing

Needles lvs2

Note-See

Tables

3 and

5 for abbreviations

and

explanations.

condi-

of .56 for a needle

to render

diagnostic material. six (4.5%) complications,

We had of which four were related to hemorrhage. In two cases, intravenous volume replacement was necessary. One patient developed a spontaneously resolving

small

patient

died

pneumothorax.

of sepsis

undergoing topsy revealed

with perforation lon and multiple from an unknown

Data Comparing

Cell Block

Yield of Needles

in Pancreatic

Biopsies

Needles

One

14 days

a pancreatic a pancreatic

Table 9 Matched

after

biopsy. Auabscess

of the transverse coliver metastases primary neoplasm.

1 vs 2

n

Y1

Y2

w

F vs S vs S

39 37

0.51 0.41

C vs S F vs C F vs W vs C

32 33 38 33

0.38 0.52 0.53 0.42

0.23 0.24 0.25

w

Note.-See

(Y1

and

95% CI

0.28

(0.08, (-0.06, (-0.04,

0.17 0.13 0.13 0.11 0.03

0.39 0.42 0.39

Tables 3 and 5 for abbreviations

Y2)

-

(-0.11, (-0.11, (-0.20,

P

0.32)

.012 .157 .157 .317 .346

0.26)

.796

0.48) 0.38) 0.29) 0.36)

explanations.

DISCUSSION Needle aspiration biopsies have become accepted by physicians for their accuracy and safety. Accuracy rates

are

known

to vary

according

to

the organ involved, expertise of the physician, patient cooperation, number of samples obtained, and close cooperation with the pathologist (6). It is surprising that needle configuration is not mentioned, and its contribution among the listed variables that affect the result of a biopsy procedure remains enigmatic. A fine needle that could be used with uniform success would be widely accepted and would gradually replace any

other biopsy needle needle

needles. The variety of available needles indicates that such a does not exist. Even if such a were available, it might not be recognized as such because of occasional unsatisfactory results that might lead the physician to implicate 266

Radiology

#{149}

the needle as the cause, when, in fact, other circumstances were responsible. There is a considerable difference in expense for various needles. The price for

our

protocol

pending spinal

needles

on supplier needle

varied

(range,

at 100%,

was

de-

with

types a laboratory. that results

obtained under controlled laboratory conditions do not necessarily predict those obtainable in vivo. Hence, we

opted

for a needle

vivo and constant

performance

out

type

might

effect that a given needle have. We theorize that specimen adequacy is a function of biopsy technique, needle type and size, and tissue

Westcott

needle, 92%-156%; Franseen needle, 140%-175%; cut biopsy needle, 214%243%). Is the difference in cost for biopsy needles justified by their results? The complex interplay of the variables given above makes an assessment of the yield of diagnostic material with various needle difficult task outside the Nonetheless, we believe

filter

test in

tried to keep those variables or similar for all needles to

the

property.

When

the

same

phy-

sician obtains biopsy specimens from the same lesion with different needles of similar size, needle type remains the only variable. We realize, however, that variations in the physician’s performance

from

pass

to pass

may

yield specimens of differing adequacy even if the same needle was used. In addition, the physician’s sensitivity to a patient’s reaction may affect specimen adequacy adversely when needle advancement is painful despite the administration of premedicalion and local anesthetics. We selected 20-gauge fine needles for our protocol as an acceptable compromise between tissue yield and risk. October

1992

Table

[%) I 00

10

Matched

Data

Cell Block

Comparing

Yield

of Needles

in Liver Biopsies 80

Needles 1 vs 2

C vs S vs C vs F vs C vs S vs

W W F W S F

Note-See

Table

n

Y1

Y2

(Y1 - Y2)

40 44 37 42 38 42

0.65 0.57 0.62

0.40 0.41 0.51

0.25 0.16 0.11

(0.06, (-0.04,

0.50 0.66

0.43

0.07

0.61 0.52

0.05 0.05

0.57

Tables 3 and 5 for abbreviations

and

95% CI

P

0.44) 0.36)

.018

(-0.07,

0.29)

.248

(-0.10,

0.24)

.405

(-0.17, (-0.16,

0.27) 0.26)

.637 .655

60 -

.127 pass

explanations.

11 Specimen

Adequacy

of Different

C No.ofpasses

Note.-Prob

liver pancreas

adequate

specimens,

and total number

W 86

99

0.82 0.74 .3690

0.87

0.78

0.77 .2003

0.90 .1413

comes

= quotient

adequate

of pancreatic

of adequate plus marginal liver specimens and total number = quotient of adequate plus marginal pancreatic specimens specimens. See Table 3 for other abbreviations. pancreas

smaller

the

use

We

Fine needles are those with diameter of less than 1 mm, 0.39

risk

inches

to the

quadratic

the

patient

hit

of

needle,

by

an

inexpe-

rienced physician will remain a mishap without consequences (9). Fine needles smaller than 20 gauge have a tendency

to deviate

from

the

slightly

dle types

in

caliber

a fine

target

varied

(7).

increases to the

(8). With

a wrong

an outer which

or 19.5-gauge

proportion

cannula

even

among

but

not

different

biopsies were performed with US guidance, acoustic reflectivity of biopsy needles was a concern. Twenty-

more

than

0.008

inch. On the basis of the criteria of specimen adequacy, the needle with the largest inner diameter yielded worse results than did needles with smaller bore. Therefore, the small variations in needle wall thickness

did

not influence In this study,

the test results. all aspiration biopsies

gauge needles are more easily seen than thinner needles because of size and because they tend to remain straight within the section thickness

pathologist

of the

sis. This information was provided to ensure that the biopsy was successful and conclusive, but, occasionally, it served to allow the physician to alter the protocol. Twenty-nine patients

sonic

needle

beam.

purpose

a sufficient

of a biopsy

quantity

is to obtain

of tissue

to en-

able diagnosis with a minimal risk to the patient, as opposed to the maximal possible quantity of tissue (8). Accordingly, our evaluation of needle performance

of tissue nostic

was

retrieved yield,

not

but

based

arbitrary

rates

both

that

quantity

and

weight

on diag-

and

criterion

the

on

rather

a subjective

what

some-

incorpoquality

of

the specimen, as well as the expertise of the pathologist. We were not concerned with the needle bore, which determines the maximal retrievable amount of tissue, but rather with the needle gauge, which is responsible for the

extent

Volume

pass

5

6

with

of tissue

185

Number

#{149}

injury.

1

The

bore

of the pass,

the

smear physician

formed

as to whether

peared

adequate

underwent

biopsy

from was the

tissue

to render

with

each inap-

a diagno-

fewer

than

four needle passes because the patient’s tolerance was breached, the patient’s level of cooperation dedined, or the target could no longer be adequately visualized. Twenty-one patients had five or six needle passes because smears quacy

on-site evaluation of the caused doubt as to the adeof the previous samples.

In our protocol, needle passes per able number rience and

we settled on four patient as a reason-

based on recommendations

our

past

expein the

each

added

nee-

of four

needle

passes

on

for fine-needle

agree

that

a

aspira-

physician

experience

is extremely important for successful needle aspiration biopsies. This includes all aspects of the procedure,

nee-

were performed in the presence of a cytopathologist and an experienced laboratory technician to guarantee immediate and proper handling of the samples. After immediate, on-site microscopic evaluation by a cyto-

in-

tended needle path, as they bend more easily (6). Because most of our

The

pass

4

die pass. A diagnostic result could be obtained in 95% of biopsies with four needle passes. These findings support routine basis lion biopsies.

The

pass

(7,10). The histogram correlating cumulative diagnostic yield with needle pass resembles an exponential function (Figure). As expected from the law of diminishing returns, the incremental diagnostic yield be-

for Liver F

91

0.81 0.56 .0180

liver

Prob

Needles

S

76

Prob adequate Prob adequate Pvalue

equals

3

pass

2

literature

x2 Results Comparing and Pancreatic Tissue

of liver

pass

1

Cumulative diagnostic yield in comparison to needle pass. The ordinate reflects the relative number of patients (100% = 133 patients). Dashed line = average conditional probability of .56 for a pass to be diagnostic.

such a

as the

physician’s

display

of

competency for optimal patient cornpliance, targeting of the lesion, preparation of the skin entry site, handling of the

equipment,

and

sampling

tech-

nique (11,12). Because the study was performed in a teaching institute with trainees of different levels of experience, results may not be as good as those obtained by a single skilled physician. the biopsy

and

were

All personnel were properly

allowed

cedure only after riod. In addition,

performing instructed

to perform an observation

the

supervising

staff

prope-

interfered when mistakes became apparent. The protocol, not the physician, controlled the sequence of needies type

to be used could not

so that any be favored

one over

needle an-

other. The

primary

goal

of all needle

aspi-

ration biopsies in our study was to establish a tissue diagnosis for an abdominal lesion. Our intention to test a small

assortment

of needles

prove our diagnostic ture clearly remained goal. Thus, deviations

to im-

yield in the fua secondary from our proto-

col occurred if the care for our patients mandated such changes. Violations of our protocol are reflected in the number of needle passes per pa-

tient,

which

do not

equal four in all frequency of

cases, as well as in the the four needles used,

which

does

Radiology

not

267

#{149}

equal exactly 25%. These variations are not important, and our numbers show that all four protocol needles had a fair chance to show trends of superiority if such existed. The accuracy of needle aspiration biopsy for diagnosing pancreatic le-

formance in other organs. Neither the results of in vivo nor those of in vitro experiments have suggested a superiority in the tissue

sions

retrieval

is known

to be less

than

that

for

other abdominal masses (10,13-15). We therefore compared our results from 49 liver biopsies with those from 40 pancreatic

biopsies.

The

success

rates of retrieving adequate spedmens for liver tissue seem higher than those for pancreatic tissue with three of the four needles, even though it was not statistically significant (Table 11). The cut biopsy needle did substantially poorer with pancreatic lesions than it did with liver lesions. As seen in the comparison of matched pairs of needles in the same patient, there was no significant difference in the performance among the four needles in liver biopsies (Table 7). Conversely, in pancreatic biopsies, differences among needles reached statistical significance (Table 8). This phenomenon is difficult to interpret and may be a reflection of the low statistical power due to the small number of patients in these organ subgroups.

Alternatively,

there

may

be a true disparity in the retrieval rate of diagnosable specimens for lesions found in different organs. Differences in tissue composition must then be implicated to explain those results, either caused by differences in tumor histology or by dissimilar reactions of the host organ to the neoplasm. Our results question the practice of testing

different

needles

ers and sults

in vitro

inferring

are

that

representative

rate

for

of needle

different

Radiology

per-

22-gauge

4.

Fleiss

JL.

proportions. 1981; 117. 5.

Woolson analysis

Statistical methods for rates 2nd ed. New York: Wiley,

RF. Statistical methods of biomedical data. New

6.

Wiley, 1987. Bernardino ME. Percutaneous AJR 1984; 142:41-45.

7.

Livraghi

T, Damasceffi

and

for the Yorlc

biopsy.

B, Lombardi

Spagnoli I. Risk in fine-needle biopsy. JCU 1983; 11:77-81.

Percutaneous tumors using observations.

References 1.

Andriole

C.

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CC. Aspiration biopsy of needle. N EnglJMed

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those

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Mindell

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HJ, Korson

R.

Comparison

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aspira-

Radi-

October

1992