Published online before print March 18, 2008, 10.1148/radiol.2472071039
(Radiology 2008;247:535-542.)
© RSNA, 2008
Real-time MR-guided Wire Localization of Breast Lesions by Using an Open 1.0-T Imager: Initial Experience1
Axel Gossmann, MD,
Christopher Bangard, MD,
Mathias Warm, MD,
Rita K. Schmutzler, MD,
Peter Mallmann, MD, and
Klaus-Jürgen Lackner, MD
1 From the Departments of Radiology (A.G., C.B., K.J.L.) and Obstetrics and Gynecology (M.W., R.K.S., P.M.), University of Cologne, Joseph-Stelzmann-Strasse 9, D-50924 Cologne, Germany. Received June 14, 2007; revision requested August 23; revision received August 31; accepted September 28; final version accepted Octo-ber 16.).
Address correspondence to A.G. (e-mail: GossmannA{at}kliniken-koeln.de).
 |
ABSTRACT
|
|---|
The purpose of this study was to prospectively evaluate technique and time factors for real-time magnetic resonance (MR) imaging–guided wire localization of suspicious breast lesions by using an open 1.0-T MR imager. It was conducted with institutional review board approval; informed consent was given by patients. Needle placement was monitored in 30 women (mean age, 50.5 years; range, 28–70 years) by using a dynamic balanced gradient-echo (single-shot turbo field-echo [TFE]) sequence with a temporal resolution of 0.5 second. In all patients, the tip of the needle was clearly identified during placement. Consistent with balanced TFE (BTFE) imaging, diagnostic MR imaging after the interventional procedure confirmed that the hookwires were placed 0–6 mm (mean, 3.3 mm) from the target lesions. The total procedure time ranged from 16–36 minutes. Results show that real-time MR-guided wire localization permits correction of the needle position during placement and reduces the interventional procedure time.
Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/2472071039/DC1
© RSNA, 2008
|
INTRODUCTION
|
|---|
Magnetic resonance (MR) imaging of the breast can demonstrate lesions that are occult at mammography, ultrasonography (US), and clinical examination (1). Therefore, for lesions detected with MR that cannot be visualized with other methods, an MR-guided intervention is necessary if tissue diagnosis is required. MR-guided wire localization followed by excisional biopsy is still the mainstay of MR-guided intervention, although an increasing number of investigators use MR-guided vacuum-assisted core-needle biopsy of the breast to yield tissue diagnosis (2–6).
Several technical challenges are known for MR-guided wire localization. The limited accessibility to the patient by using closed MR units requires a repeated transfer of the patient in and out of the imager during the interventional procedure, leading to increased examination times. Moreover, owing to the long examination time, the possibility of contrast material washout during the procedure has been described, leading to a limited visibility of the lesion relative to the guide wire (3).
Another limitation of MR-guided wire localization by using closed MR units is that the insertion of the needle has to be performed outside the magnet. A shift of breast tissue as well as a deviation of the needle are therefore not visible during the insertion and cannot be corrected at that moment. In addition, breast lesions close to the chest wall, within the axillary tail, or close to implants are difficult to localize or may even be inaccessible by using standard techniques.
A recently developed open MR imager with a field strength of 1.0 T offers substantially improved access to the patient while the patient remains in the isocenter of the magnet. Hence, a repeated transfer of the patient in and out, as happens with closed-bore MR imaging units, is not necessary. Further, owing to the field strength of 1.0 T, this open MR imager should allow fast dynamic imaging with near–real-time conditions in combination with good spatial resolution. Visualization of the needle during the interventional procedure would therefore be possible. Thus, the purpose of our study was to prospectively evaluate technique and time factors for real-time MR-guided wire localization of suspicious breast lesions by using an open 1.0-T MR imager.
|
MATERIALS AND METHODS
|
|---|
The study was conducted with the approval of our local institutional review board. Written informed consent was obtained from all patients.
Study Group and Clinical Indications
From January 2006 to July 2006, we performed 531 MR imaging examinations of the breast, including 131 women with breast cancer. Of this group, 30 women (mean age, 50.5 years; range, 28–70 years) with a total of 31 MR-detected suspicious contrast material–enhanced lesions underwent MR-guided wire localization, with subsequent surgical procedure and histologic analysis.
The clinical indications for MR imaging were ipsilateral or contralateral breast cancer staging (n = 14), follow-up examinations in women with a history of breast cancer after breast-conserving or reconstructive surgery (n = 9), screening in high-risk patients (identified as a BRCA1 or BRCA2 carrier, 
20% heterozygote risk or 30% lifetime risk; n = 5), follow-up examination after presurgical chemotherapy (n = 1), and axillary lymph node malignancy with unknown site of primary tumor (n = 1). In all patients, diagnostic MR helped detect suspicious contrast-enhanced lesions that were not visible at mammography (Selenia; Lorad/Hologic, Bedford, Mass) and high-frequency (12 MHz) transducer-directed breast US (Voluson 730 Expert; GE Healthcare, Milwaukee, Wis), including second-look US. Therefore, in all women, MR-guided wire localization was performed to yield tissue diagnosis. Wire localization was used instead of core-needle biopsy because breast-conserving surgery was planned; the target lesion was not accessible with MR-guided core-needle biopsy, or on request of the surgeon or patient. Follow-up MR examination of the breast 1–3 months after surgery was performed in patients with benign histopathologic findings to verify complete lesion removal.
MR-guided Wire Localization
All interventional procedures were performed by the same radiologist (A.G., with 11 years experience in breast MR and 8 years experience in MR-guided breast intervention). Interventional imaging was performed with a 1.0-T open MR system (Panorama; Philips Medical Systems, Best, the Netherlands) in all patients 1–10 days after the diagnostic examination. This MR imager has a patient aperture of 160 cm so that procedures can be performed while the patient remains in the magnet (Fig 1a, 1b).
View larger version (82K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1a: (a) View of patient positioned for real-time MR-guided wire localization of left breast, which was placed in magnet isocenter. (b) Needle insertion and guide wire release during intervention are visible on monitor beside magnet. (c) Breast placed in dedicated breast array coil with immobilization and positioning device. Coordinate pillar system was used to reach chest wall and axillary tail to allow needle angulations.
|
|
View larger version (126K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1b: (a) View of patient positioned for real-time MR-guided wire localization of left breast, which was placed in magnet isocenter. (b) Needle insertion and guide wire release during intervention are visible on monitor beside magnet. (c) Breast placed in dedicated breast array coil with immobilization and positioning device. Coordinate pillar system was used to reach chest wall and axillary tail to allow needle angulations.
|
|
View larger version (95K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1c: (a) View of patient positioned for real-time MR-guided wire localization of left breast, which was placed in magnet isocenter. (b) Needle insertion and guide wire release during intervention are visible on monitor beside magnet. (c) Breast placed in dedicated breast array coil with immobilization and positioning device. Coordinate pillar system was used to reach chest wall and axillary tail to allow needle angulations.
|
|
MR imaging was performed in patients while prone by using a dedicated breast array coil (In Vivo, Orlando, Fla). A lateral table position was chosen for all patients so that the side of the breast on which the procedure was performed was placed in the isocenter of the magnet (Fig 1a, 1b). An immobilization and positioning device (Noras, Höchberg, Germany) with the coordinate pillar system (Fig 1c) was used to reduce motion artifacts of the breast and allow accurate needle guidance. The positioning device allowed a horizontal pathway of the needle or 15° or 30° angulation toward the chest wall or the nipple. Owing to the accessibility to the patient by using the open MR system, the preinterventional imaging for the reidentification of the suspicious lesions and the subsequent procedures were carried out while the patient remained in the same table position in the imager.
After the breast was cleaned with povidone iodine solution, the medial immobilization plate and the lateral coordinate pillar system were placed by using gentle compression. Contrast material–containing reference marker was placed in the needle holder of the breast coil. The imaging protocol was started with initial scout imaging and followed by a transverse dynamic T1-weighted, three-dimensional gradient-echo (fast field-echo [FFE]) sequence with the following parameters: repetition time msec/echo time msec, 11/6; one acquisition; flip angle, 25°; matrix, 352 x 256; section thickness, 1.5 mm; field of view, 360 mm; sensitivity encoding reduction factor of two; acquisition time, 1 minute per 100 sections. One nonenhanced and three dynamic contrast-enhanced studies (a bolus of 0.1 mmol/kg of gadodiamide [Omniscan; Amersham Health, Princeton, NJ], followed by a bolus of 15 mL of saline) were obtained to help visualize and reidentify the suspicious contrast-enhanced lesions according to the previous MR image of the breast.
The reidentification of the diagnosed lesions was performed according to their morphology, enhancement pattern, and location in the breast. If the contrast-enhanced target lesions were clearly identifiable after the first contrast-enhanced dynamic scan, no further dynamic studies were performed. Image subtraction was used for all patients to suppress the fat signal. In three patients, the known contrast-enhanced lesions could be reidentified at interventional MR without the application of contrast material owing to anatomic landmarks seen on the preinterventional MR image. In these women, only the nonenhanced FFE sequence was performed for reidentification.
Given the findings of the FFE sequence, the coordinates of the suspicious lesions (superior to inferior, anterior to posterior, and right to left) were identified and the distance to the reference marker was calculated by using the distance function of the console software. The right-to-left distance corresponded to the depth of the needle pathway. After repositioning the reference marker to the coordinates of the suspicious lesion, the FFE sequence was repeated to verify the correct position of the needle holder according to the target lesion. The reference marker was then replaced by a sterile bushing through which the needle was inserted. During the insertion of the MR-compatible
18-gauge needle and the release of an MR-compatible guide wire (MRI-DUO-SYSTEM; Somatex Medical Technologies, Teltow, Germany), dynamic real-time MR imaging was performed to help visualize the placement of the needle and the release of the guide wire. The MR-compatible needle has 1-cm marks on the shaft that can be used to adjust the needle's position.
For dynamic real-time MR imaging, we used a transverse single-section balanced gradient-echo (single-shot turbo field-echo [TFE]) sequence with the following parameters: 3.6/1.8; one acquisition; flip angle, 60°; TFE factor, 133; matrix, 224 x 256; section thickness, 8 mm; field of view, 375 mm; acquisition time, 0.5 second per section. The center of the balanced TFE (BTFE) sequence was set to the table position at which the suspicious lesion was detected according to the FFE sequence. The BTFE sequence was started immediately before the interventional procedure and stopped when the release of the guide wire was finished. A monitor (Philips Medical Systems) close to the magnet in the imaging room displayed the MR images during the procedure. Thus, the radiologist remained in the imaging room with the patient and could see the placement of the needle and the release of the guide wire on the monitor during the intervention (Fig 1b).
A shift of the breast tissue, as well as a deviation of the needle, were visible, and the position of the needle could be immediately corrected if necessary. The insertion of the needle was stopped when the position and the calculated depth were satisfactory according to the corresponding BTFE images on the monitor and the marks on the needle shaft. Finally, the guide wire was released under control of real-time MR imaging. In patients without a lesion that was visible as a mass at on BFTE images, needle placement was performed according to adjacent landmarks, as described by Morris et al (7) and van den Bosch et al (8).
In women who had suspicious lesions that could not be reached sufficiently by using the stereotactic approach, a freehand technique for MR-guided wire localization was used instead. For the freehand technique, the reference marker was used to verify the correct position of the needle holder, as in the stereotactic approach. The entry site of the needle was marked on the skin according to the position of the reference marker and the needle holder was then removed. The needle was subsequently inserted without a needle holder and bushing while the BTFE sequence was running. The orientation of the tip of the needle during the placement was determined by using real-time MR. The depth of the needle within the breast was controlled by using the MR images and the marks on the needle shaft. When the tip of the needle reached the target lesion, the insertion was stopped and the guide wire was released under guidance of the BTFE images.
Finally, the high-spatial-resolution FFE sequence was performed again for both the stereotactic and the freehand approaches to verify the position of the guide wire and to confirm the findings of the BTFE image. The postinterventional FFE image was subtracted from the nonenhanced FFE image to suppress the fat signal and to help visualize the contrast-enhanced lesion. In 15 women, the FFE sequence was also performed after the placement of the needle but before the guide wire was released. After a learning curve and becoming more experienced with the BTFE sequence, the high-spatial-resolution FFE sequence was not performed anymore before the release of the guide wire.
All patients tolerated the wire localization well and no complications occurred. After the interventional procedure, the guide wire was tightly fixed with tape on the patient's skin to prevent migration and covered with sterile dressings. All subsequent surgical procedures were performed 20–150 minutes after MR-guided wire localization.
Image Analysis and Procedure Time
The BTFE and FFE images obtained after the release of the guide wires were evaluated by two radiologists (A.G. and C.B.) in consensus to determine whether the guide wires and the target lesions were clearly identifiable with good soft-tissue contrast (defined as a clear demarcation between the target lesion and the surrounding tissue) and whether needle artifacts hampered the visibility of the target lesions. The distance between the target lesion and the tip of the released guide wire was measured for all women for the BTFE and FFE images by using the distance software of the imager.
For each patient and guide wire placement, the following times were respectively assessed by using the integrated watch of the MR imager: (a) total preoperative case time (started when the patient entered the MR suite and ended when the patient left the MR suite after placement of the guide wire); (b) time after contrast material injection until the release of the guide wire (started when the contrast agent was injected and ended when the guide wire was released); and (c) interventional procedure time (started with the insertion of the needle and ended when the guide wire was released).
|
RESULTS
|
|---|
Histologic Findings
MR-guided needle localization yielded malignancy in 12 lesions (eight invasive ductal cancers, three invasive lobular cancers, and one invasive neuroendocrine cancer), two high-risk lesions (lobular carcinoma in situ and radial scar), and 17 benign findings (eight fibrocystic changes, four fibroadenomas, two intramammary lymph nodes, one siliconoma, one fat necrosis, and one papilloma without atypia). Surgical histologic and imaging findings were considered concordant in all women.
In all women with benign findings, postoperative MR imaging obtained 4–12 weeks after surgery helped verify that the target lesions were removed.
Real-time MR-guided Wire Localization
All lesions were clearly reidentified on the preinterventional FFE image according to the previous diagnostic MR examination of the breast (Figs 2, 3). The BTFE image offered a good soft-tissue contrast so that in 19 (61.3%) of 31 lesions, the suspicious lesion could be identified as a mass at MR (Fig 2). In the remaining patients, when the lesion was not visible as a mass at dynamic real-time imaging, needle placement was performed according to adjacent landmarks (Fig 3).
View larger version (104K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2a: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (69K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2b: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (66K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2c: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (60K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2d: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (64K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2e: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (68K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2f: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (70K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2g: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (109K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2h: Real-time MR-guided preoperative wire localization of right breast with freehand technique in 69-year-old woman with history of breast cancer after mastectomy and insertion of prosthesis. (a) FFE (11/6) image shows 5-mm target lesion (arrow) in axillary tail lateral to single-lumen silicone implant (Im). Needle trajectory had to be tangential to implant surface to prevent puncture. (b–g) BTFE (3.6/1.8; acquisition time, 0.5 second per section) images show silicone implant, suspicious lesion (open arrow), and needle tip (solid arrow) approaching target lesion. Time after needle insertion shown in seconds. Guide wire placement was performed within 14 seconds. This angled freehand approach is impossible with lateral grid-compression plate devices. Comparison of (g) BTFE with (h) FFE image after guide wire release shows identical findings with guide wire tip at target lesion (arrow) close to chest wall. Histopathologic analysis revealed benign lymph node.
|
|
View larger version (115K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (124K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3c: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3d: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3e: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (124K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3f: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (105K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3g: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
View larger version (119K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3h: Real-time MR-guided preoperative wire localization of right breast in 32-year-old woman with angled stereotactic approach. (a) Contrast-enhanced FFE study (11/6) with image subtraction to suppress fat signal shows 18-mm suspicious contrast-enhanced lesion (arrow) in axillary tail. (b–f) In BTFE study (3.6/1.8; 0.5 second per section), suspicious lesion (solid arrow) could be identified according to adjacent landmarks. Lesion could not be reached with horizontal approach owing to its location in axillary tail near chest wall. (b–d) Needle approaches target lesion from lateral side (open arrow) and (e,f) subsequent release of guide wire is shown. Time after needle insertion shown in seconds. Comparison of (f) BTFE with (g) high-spatial-resolution FFE image after guide wire release shows identical findings with guide wire tip near chest wall in target lesion. (h) Image subtraction to suppress fat signal of postinterventional FFE study shows contrast-enhanced lesion with guide wire tip in lesion. Short procedure time allows image subtraction that shows contrast-enhanced lesion without decreasing visibility. Surgical excision of lesion revealed fibrocystic changes.
|
|
The tips of the needles and the guide wires were clearly identifiable on the BTFE image during needle placement in all patients (Figs 2, 3; Movies E1, E2, [http://radiology.rsnajnls.org/cgi/content/full/2472071039/DC1]). Needle artifacts hampered the visibility of the target lesions in none of the patients (Figs 2, 3; Movies E1, E2
[http://radiology.rsnajnls.org/cgi/content/full/2472071039/DC1]). The BTFE and high-spatial-resolution FFE images confirmed concordantly that the guide wires were placed 0–6 mm (mean, 3.3 mm) from the target lesion (Figs 2, 3). None of the women experienced a misplacement of the needle, so no repositioning of the needle was necessary after dynamic real-time imaging.
A stereotactic lateral approach with a horizontal pathway of the needle was used to reach 27 of 31 lesions. A stereotactic lateral approach with 15° and 30° angulations of the needle was used in two patients where the suspicious lesions were located in the axillary tail close to the chest wall (Fig 3). In two patients, the freehand technique instead of the stereotactic approach to reach the lesions was used. One patient had a lesion in the upper medial quadrant of a large breast. The needle (12 cm) was not long enough to reach this lesion by using a stereotactic lateral approach. The localization was therefore performed without the sterile bushing to get closer to the skin entry site. The second patient had a suspicious contrast-enhanced lesion in the axillary tail close to an implant not reachable with the stereotactic approach (Fig 2).
Times
The total preoperative case time ranged from 16 to 36 minutes (mean, 21 minutes). The time after contrast agent injection until the release of the guide wire ranged from 5 to 14 minutes (mean, 7 minutes). Owing to the relatively short interval between the contrast agent injection and the release of the guide wire, all lesions could be reidentified according to their enhancement on the postinterventional subtracted MR images relative to the guide wire (Fig 3). The interventional procedure time—as monitored by using dynamic MR imaging—ranged from 8 to 38 seconds (mean, 16 seconds).
|
DISCUSSION
|
|---|
The advantages of real-time MR-guided wire localization are a simplified work flow characterized by ease of operation for the radiologist and efficiency for the patient. Even lesions that are difficult to localize or not approachable with other techniques—such as lesions within the axillary tail or close to an implant—are amenable to this technique.
For MR-guided wire localization in a conventional closed-bore imager, different techniques are used. Besides stereotactic approaches for closed-bore imagers (3,7,9–12), freehand interactive MR-guided techniques for closed-bore imagers and 0.5-T open-bore imagers are also described (13,14). Unlike these techniques, real-time MR-guided wire localization permits a correction of the needle position during placement since the radiologist can see the insertion of the needle and the release of the guide wire. Daniel et al (13,15,16) used a freehand technique for MR-guided lesion localization and large-gauge core-needle biopsy but did not use dynamic real-time imaging to monitor the interventional procedure. To overcome this technical problem, the authors recommended that, to minimize the risk of pneumothorax, direct chest wall approaches should be performed cautiously, with use of frequent imaging to monitor each incremental advance of the needle. However, our technique allows safe localization of all lesions within seconds, regardless of their location.
The BTFE sequence that was used in our study offered a good soft-tissue contrast and needle artifacts did not hamper image quality. However, dynamic MR imaging is always a compromise between temporal and spatial resolution. The BTFE sequence had a temporal resolution of 0.5 second per image. This high temporal resolution permitted near–real-time conditions during the procedure, with good control over the tip of the needle during placement. Interventional procedures can therefore be safely performed, even in anatomic regions that are difficult to approach.
We used a coordinate pillar system instead of a grid-hole device because a full range of needle angulations is possible. The coordinate pillar system also allows a freehand technique where the needle is inserted without a bushing. This technique requires more skill from the radiologist, since the needle trajectory has to be within the plane of the BTFE image and the correct needle angulation has to be obeyed without a supporting bushing. Although the freehand technique is technically more demanding than a stereotactic approach, it enables localization of lesions that would not be reachable with other techniques. Real-time MR imaging is therefore extremely useful in helping visualize the tip of the needle for a freehand technique.
Our mean total magnet time was 21 minutes, which is approximately one-third of the 62 and 64 minutes, respectively, reported by Causer et al (17) and Daniel et al (13), and approximately two-thirds of the 31 minutes reported by Morris et al (7). This fast procedure time permitted short periods between the injection of the contrast agent and the release of the guide wire. Consequently, the targeted contrast-enhanced lesions were still visible after the release of the guide wire by using an image subtraction technique. Another advantage of short interventional procedure times is that the MR imager is not used for a long time, which helps to increase the number of examinations that can be performed.
This study had limitations. Although the patient aperture of the open 1.0-T MR imager has a size of 160 cm, working in a confined space may be awkward for some radiologists. Another limitation of dynamic real-time MR imaging was the single-section technique. To visualize the tip of the needle, the trajectory had to be within the plane of the BTFE image. In patients who experienced a deviation of the needle out of the imaging plane, the tip of the needle was no longer visible at MR.
In cases of uncertainty, dynamic MR had to be interrupted and the location of the tip of the needle had to be determined with a multisection sequence. However, none of our patients required an interruption of their imaging since the tip of the needle was always clearly visible. As in any breast MR localization study, real-time MR-guided wire localization lacks to verify lesion removal. We did not perform radiograph of the specimen because only lesions that were not visible with other imaging techniques were localized. Further, at short-term follow-up MR, no persisting suspicious contrast-enhanced lesions were visible and surgical histologic and imaging findings were considered concordant in all patients.
Consistent with other working groups (3,7), the geometry of the breast coil used in our study permitted needle placement from only the lateral side. The lateral approach was not always the shortest distance to the lesion and it required that the needle traverse a longer distance in some patients. Consequently, the surgery cannot be performed along the trajectory of the guide wire if the surgeon wants to offer the best cosmetic result to the patient. Thus, dedicated breast biopsy coils that also allow a medial approach to the breast—as already used by other working groups (9,17,18)—would be desirable for use with open MR.
Notwithstanding these limitations, the results of our study showed that real-time MR-guided wire localization of suspicious breast lesions by using an open 1.0-T MR imager permits a correction of the needle position during placement and reduces the interventional procedure time. Hence, the contrast-enhanced target lesion shows only a minimal decrease in visibility during the procedure.
|
ADVANCES IN KNOWLEDGE
|
|---|
- Real-time MR imaging allows correction of the needle during insertion when a deviation occurs.
- Real-time MR-guided wire localization reduces the length of the interventional procedure time.
- Even lesions that are inaccessible with standard-grid techniques, such as lesions close to the chest wall, within the axillary tail, or close to implants, can be local-ized.
|
IMPLICATION FOR PATIENT CARE
|
|---|
- Real-time MR-guided wire localization of breast lesions by using an open 1.0-T imager reduces the interventional procedure time for the patient.
|
FOOTNOTES
|
|---|
Abbreviations: BTFE = balanced TFE • FFE = fast field echo • TFE = turbo field echo
Author contributions: Guarantors of integrity of entire study, A.G., K.J.L.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, A.G., C.B.; clinical studies, all authors; and manuscript editing, A.G.
Authors stated no financial relationship to disclose.
|
References
|
|---|
- Orel SG, Schnall MD. MR imaging of the breast for the detection, diagnosis, and staging of breast cancer. Radiology 2001;220:13–30.[Abstract/Free Full Text]
- Fischer U, Kopka L, Grabbe E. Magnetic resonance guided localization and biopsy of suspicious breast lesions. Top Magn Reson Imaging 1998;9:44–59.[Medline]
- Kuhl CK, Elevelt A, Leutner CC, Gieseke J, Pakos E, Schild HH. Interventional breast MR imaging: clinical use of a stereotactic localization and biopsy device. Radiology 1997;204:667–675.[Abstract/Free Full Text]
- Liberman L, Bracero N, Morris E, Thornton C, Dershaw DD. MRI-guided 9-gauge vacuum-assisted breast biopsy: initial clinical experience. AJR Am J Roentgenol 2005;185:183–193.[Abstract/Free Full Text]
- Orel SG, Rosen M, Mies C, Schnall MD. MR imaging-guided 9-gauge vacuum-assisted core-needle breast biopsy: initial experience. Radiology 2006;238:54–61.[CrossRef][Medline]
- Floery D, Helbich TH. MRI-Guided percutaneous biopsy of breast lesions: materials, techniques, success rates, and management in patients with suspected radiologic-pathologic mismatch. Magn Reson Imaging Clin N Am 2006;14:411–425.[CrossRef][Medline]
- Morris EA, Liberman L, Dershaw DD, et al. Preoperative MR imaging-guided needle localization of breast lesions. AJR Am J Roentgenol 2002;178:1211–1220.[Abstract/Free Full Text]
- van den Bosch MA, Daniel BL, Pal S, et al. MRI-guided needle localization of suspicious breast lesions: results of a freehand technique. Eur Radiol 2006;16:1811–1817.[CrossRef][Medline]
- Heywang-Kobrunner SH, Huynh AT, Viehweg P, Hanke W, Requardt H, Paprosch I. Prototype breast coil for MR-guided needle localization. J Comput Assist Tomogr 1994;18:876–881.[Medline]
- Orel SG, Schnall MD, Newman RW, Powell CM, Torosian MH, Rosato EF. MR imaging-guided localization and biopsy of breast lesions: initial experience. Radiology 1994;193:97–102.[Abstract/Free Full Text]
- Fischer U, Vosshenrich R, Keating D, et al. MR-guided biopsy of suspect breast lesions with a simple stereotaxic add-on-device for surface coils. Radiology 1994;192:272–273.[Abstract/Free Full Text]
- Fischer U, Vosshenrich R, Doler W, Hamadeh A, Oestmann JW, Grabbe E. MR imaging-guided breast intervention: experience with two systems. Radiology 1995;195:533–538.[Abstract/Free Full Text]
- Daniel BL, Birdwell RL, Ikeda DM, et al. Breast lesion localization: a freehand, interactive MR imaging-guided technique. Radiology 1998;207:455–463.[Abstract/Free Full Text]
- Brenner RJ, Shellock FG, Rothman BJ, Giuliano A. Technical note: magnetic resonance imaging-guided pre-operative breast localization using "freehand technique". Br J Radiol 1995;68:1095–1098.[Abstract/Free Full Text]
- Daniel BL, Birdwell RL, Black JW, Ikeda DM, Glover GH, Herfkens RJ. Interactive MR-guided, 14-gauge core-needle biopsy of enhancing lesions in a breast phantom mode. Acad Radiol 1997;4:508–512.[CrossRef][Medline]
- Daniel BL, Birdwell RL, Butts K, et al. Freehand iMRI-guided large-gauge core needle biopsy: a new minimally invasive technique for diagnosis of enhancing breast lesions. J Magn Reson Imaging 2001;13:896–902.[CrossRef][Medline]
- Causer PA, Piron CA, Jong RA, et al. MR imaging-guided breast localization system with medial or lateral access. Radiology 2006;240:369–379.[Abstract/Free Full Text]
- Lampe D, Hefler L, Alberich T, et al. The clinical value of preoperative wire localization of breast lesions by magnetic resonance imaging: a multicenter study. Breast Cancer Res Treat 2002;75:175–179.[CrossRef][Medline]
TOP
ABSTRACT
INTRODUCTION
