DOI:10.2214/AJR.06.1123
AJR 2007; 189:152-154
© American Roentgen Ray Society
CT-Guided Core Needle Biopsy of Breast Lesions Visible Only on MRI
Jeffrey B. Mendel1,
Michelle Long1 and
Priscilla J. Slanetz2
1 Department of Radiology, Caritas St. Elizabeth's Medical Center, 736 Cambridge
St., Boston, MA 02135.
2 Department of Radiology, Boston Medical Center, Boston, MA.
Received August 22, 2006;
accepted after revision January 26, 2007.
Address correspondence to J. B. Mendel
(jeffrey.mendel{at}caritaschristi.org).
Abstract
OBJECTIVE. As breast MRI has become more widely used, the need to
biopsy suspicious lesions visible only on MRI has increased. A small
percentage of these lesions are not amenable to MR-guided biopsy. We report
our technique of CT-guided core needle biopsy of breast lesions.
CONCLUSION. CT-guided core needle biopsy is a safe and effective
method for sampling breast lesions visible only on MRI when MR-guided biopsy
is not feasible.
Keywords: breast • breast biopsy • breast cancer • interventional radiology • MDCT • MRI • women's imaging
Introduction
MRI of the breast has emerged as a powerful imaging tool for the detection
of clinically, sonographically, and mammographically occult breast cancers
[1]. The indications for breast
MRI continue to expand [2].
Although contrast-enhanced MRI has a high sensitivity for detecting breast
carcinoma, the specificity is comparatively lower and the need to correlate
MRI findings with histopathology exists
[3].
With the increasing use of breast MRI, there is a need to accurately biopsy
suspicious lesions that are mammographically and sonographically occult.
Although various MR-guided core needle biopsy techniques have been developed,
a small percentage of cases, because of lesion location, the presence of
implants, or coexistent medical problems, are not amenable to MR-guided
biopsy. Commonly, MR- or CT-guided needle localization procedures followed by
excisional biopsy are used to sample these lesions
[4].
Needle biopsy techniques have well-established advantages over surgical
biopsies [5]. They are less
invasive, less deforming to the breast, more cost effective, and quicker to
perform than surgical biopsies and leave minimal visible scarring on
subsequent mammograms. By adapting the techniques used for MR-guided biopsy,
we can use CT-guided core needle biopsy to access these lesions, thereby
avoiding the need for a surgical biopsy. In this report, we describe a
technique that uses CT guidance to biopsy lesions detected on MRI when
MR-guided biopsy is not practical.
Subjects and Methods
Institutional review board approval was waived because all CT-guided core
needle biopsies were performed in the course of routine patient care. Informed
consent was obtained from the patients, and data collection was compliant with
the Health Insurance Portability and Accountability Act. Since December 2003,
we have performed nine CT-guided breast biopsies in eight women. The mean age
of these patients at biopsy was 56.7 years (range, 45-71 years). During the
same time period at our institution, we performed 97 MR-guided breast
biopsies, so CT-guided biopsy represented 9% of our overall cross-sectional
imaging-guided breast biopsies.
Before biopsy, each patient underwent bilateral breast MRI using a 1.5-T
system (Excite, GE Healthcare) and a dedicated breast coil (Breast Array Coil,
InVivo). Our examination protocol consisted of unenhanced axial T1-weighted
and STIR sequences; after the injection of 20 mL of nonionic contrast material
(gadodiamide [Omniscan, GE Healthcare]) at a rate of 2 mL/s with a 20-mL
saline flush using a dual syringe injector (Spectris, Medrad), dynamic
contrast-enhanced axial fast acquisition with multiphase Efgre3D (enhanced
fast gradient-echo 3D) (FAME) and contrast-enhanced sagittal FAME sequences
were performed.
The areas of abnormal enhancement on MRI were identified using a dedicated
workstation (DynaCAD, Invivo). Lesions ranged from 4 to 34 mm in the longest
dimension, with a median size of 12 mm. Two lesions were 
5 mm, two were
5-10 mm, and five were > 10 mm. All of the lesions were clinically,
mammographically, and sonographically occult except one 34-mm lesion that was
palpable. This lesion had previously undergone a biopsy without imaging
guidance, but that biopsy yielded inconclusive results. MRI showed a localized
area of suspicious enhancement that was occult on repeat mammography and
sonography.
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Fig. 1A —70-year-old woman with history of treated ipsilateral breast
cancer and suspicious enhancement in lateral aspect of breast. Biopsy revealed
intracystic papilloma. MR image shows suspicious lesion (arrowhead)
and MRI skin marker (arrow). Posterior margin of biopsy grid is
indicated by thin white line.
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Fig. 1B —70-year-old woman with history of treated ipsilateral breast
cancer and suspicious enhancement in lateral aspect of breast. Biopsy revealed
intracystic papilloma. CT image obtained immediately after MRI shows lesion
(arrowhead) is close to MRI skin marker (arrow).
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Fig. 2A —45-year-old woman with suspicious enhancement adjacent to
breast implant. Pathology revealed benign breast tissue. MR image of
suspicious lesion (arrowhead) and retropectoral breast implant
(asterisk). MR-guided core needle biopsy could not be performed
safely because projected path of biopsy needle (dotted line) would
likely have ruptured implant. This image is rotated for comparison with
B.
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Fig. 2B —45-year-old woman with suspicious enhancement adjacent to
breast implant. Pathology revealed benign breast tissue. CT image shows lesion
(arrowhead) and retropectoral breast implant (asterisk) with
minimally radiopaque obturator in place (arrow).
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MR-guided biopsy was attempted in two cases but was cancelled after the
areas of enhancement were visualized posterior to the portion of the breast
that is accessible using the biopsy grid
(Fig. 1A). In these cases, an
MRI marker was placed on the skin directly over the suspicious lesion and the
position of the marker was confirmed using repeat MRI
(Fig. 1A). The patient was then
transferred to the CT scanner for a CT-guided biopsy
(Fig. 1B). For the remaining
seven lesions, MR-guided biopsy was not attempted for the following reasons:
the lesion either was too superficial or could not be accessed using the
biopsy grid, concomitant medical conditions precluded the patient from being
prone for a prolonged period, or the projected biopsy path intersected with a
saline implant (Fig. 2A).
For CT-guided biopsy, the patient was positioned supine with varying
degrees of obliquity to optimize access to the lesion. A skin fiducial or
paper grid (Fast Find Grid, E-Z-EM) was applied on the basis of the location
of the lesion on MRI. The region of breast containing the abnormally enhancing
tissue was scanned with 3-mm-thick CT slices obtained before and 150 seconds
after the administration of 100 mL of nonionic contrast material (iohexol
[Omnipaque 350, GE Healthcare]) injected at a rate of 2 mL/s with a 30-mL
saline flush using a dual syringe injector (Stellant, Medrad) on a 16-MDCT
scanner (Brilliance 16, Philips Medical Systems).
Scanning was originally performed using our standard chest CT technique
(120 kVp, 300 mA). For later cases, patients were scanned with a
lower-kilovoltage technique (90 kVp, 360 mA). Once the target was identified,
the breast was prepared and draped in the usual sterile fashion and local
anesthesia with 1% lidocaine hydrochloride was administered. A 3- to 4-mm skin
incision was made with a number 11 blade at the entry site.
For large lesions that were unlikely to be obscured by the introducer
sheath, the metal trocar needle and introducer sheath were inserted directly
into the lesion. For artifact to be minimized, the trocar needle was then
removed and a minimally radiopaque plastic obturator was inserted
(Fig. 2B). Depending on the
size and location of the lesion, between one and three CT series were needed
to guide the trocar needle to its final position. Once correct positioning of
the trocar needle was confirmed on CT, the obturator was removed and a
vacuum-assisted biopsy device (ATEC, Suros Surgical Systems) was inserted into
the sheath. Multiple samples were obtained with the device directed to ensure
sampling of the region of interest. One biopsy was performed with an 18-gauge
automated core biopsy needle (Temno, Cardinal Health) using a 17-gauge coaxial
introducer needle. In this case, multiple passes were made to ensure adequate
sampling.
For small lesions, a 25-gauge needle was inserted adjacent to the enhancing
lesion (Fig. 3A). Given the
inherent mobility of the breast, the small-gauge needle provided additional
guidance during placement of the larger-gauge biopsy device.
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Fig. 3A —54-year-old woman with suspicious enhancement adjacent to
chest wall. Pathology revealed invasive ductal carcinoma and ductal carcinoma
in situ. CT image shows lesion (arrowhead) with 25-gauge guide needle
(arrow) in place.
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In four cases, by using a small-gauge needle as a guide, sonography was
able to show lesions that had previously been occult on targeted breast
sonography, allowing the use of adjunctive sonography during the biopsy
(Fig. 3B). In the five cases in
which sonography was used, a sonography unit equipped for breast imaging
(Model 5000, Philips Medical Systems) was placed in the CT suite at the start
of the CT procedure. Scanning was performed with 12- and 15-MHz linear
transducers. All the lesions were nonspecific in sonographic appearance and
were identified only after the small-gauge needle was inserted under CT
guidance.
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Fig. 3B —54-year-old woman with suspicious enhancement adjacent to
chest wall. Pathology revealed invasive ductal carcinoma and ductal carcinoma
in situ. After CT-guided placement of guide needle (arrow), lesion
(arrowhead) is faintly visible on sonography.
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In all cases, a titanium marker (ATEC TriMark, Suros Surgical Systems) was
deployed and CT was performed after the biopsy to ensure that the lesion was
successfully sampled and the clip was correctly positioned. After the
procedure, hemostasis was achieved with direct compression.
Results
Of nine lesions sampled using CT guidance, two were invasive ductal
carcinoma, two showed atypical ductal hyperplasia (ADH), and the remaining
five lesions were benign. For the two patients whose lesions were ADH at
CT-guided biopsy, the final pathology results at surgical excision were ADH in
one and chronic focal inflammation in the other. Follow-up MRI performed in
three of the patients with benign biopsy results revealed no evidence of
malignancy at a minimum of 18 months after biopsy. In all cases, the metallic
marker was visualized on follow-up MRI. In one case, the marker had migrated
slightly from the biopsy bed, but no residual enhancement was noted at the
site of the original lesion. One patient died from unrelated causes 3 months
after biopsy and one patient was lost to follow-up.
Discussion
CT-guided percutaneous biopsy is a well-established technique in the chest,
abdomen, and pelvis [6]. By
adapting this technique and specific features from MR-guided breast biopsy, we
have found a technique that offers a safe and effective way to sample those
lesions for which MR-guided biopsy is not technically feasible. CT guidance is
possible because the enhancement patterns seen with iodinated contrast
material are similar to those observed with the use of gadolinium contrast
material [4]. CT does not
require the use of a breast coil or biopsy grid, so CT permits direct access
to lesions anywhere within the breast. The biopsy path can be further tailored
by adjusting the patient's position. CT facilitates patient monitoring and
sedation, particularly when compared with MRI, which requires that patients be
in the prone position. We performed most of our biopsies with a
vacuum-assisted device to maximize the likelihood of successfully sampling
small lesions. For large lesions, our technique was and can be used with an
automated core biopsy device.
One challenge to our approach was breast mobility, a factor that is less
problematic when using stereotactic, sonographic, or MRI guidance because each
has an inherent ability to restrict motion. The initial placement of a thin
needle helped by serving as a point of reference as the trocar needle was
inserted. CT can potentially expose the breast to substantial radiation
[7]. To minimize radiation
dose, we limited the scans to the portion of the breast containing the lesion
and did not obtain scout images. In later cases, we reduced the kilovoltage
setting; this change yielded a fourfold radiation dose reduction with no
apparent change in lesion conspicuity. Finally, the use of adjunctive
sonography allowed the number of series per biopsy to be reduced by
eliminating those series necessary to monitor both the insertion of the trocar
needle and sheath and the successful sampling of the lesion.
In conclusion, CT-guided core needle biopsy can replace needle localization
and surgical biopsy for a subset of MRI-detected, mammographically and
sonographically occult lesions that are not amenable to conventional MR-guided
biopsy due to lesion location or to other technical or patient factors.
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Abstract
Introduction
