Published online before print June 20, 2003, 10.1148/radiol.2282020640
(Radiology 2003;228:589-592.)
© RSNA, 2003
MR Fluoroscopy–guided Transthoracic Fine-Needle Aspiration Biopsy: Feasibility1
Mehmet Emin Sakarya, MD,
Ozkan Unal, MD,
Bulent Ozbay, MD,
Kursat Uzun, MD,
Ismail Kati, MD,
Suleyman Ozen, MD and
Omer Etlik, MD
1 From the Departments of Radiology (M.E.S., O.U., O.E.), Pulmonary Disease (B.O., K.U.), Anesthesiology (I.K.), and Pathology (S.O.), Yuzuncu Yil University Faculty of Medicine, Mara YYU Tip Fakultesi Hastanesi, Radyoloji AD, 65200 Van, Turkey. Received May 28, 2002; revision requested August 1; revision received September 7; accepted November 18. Address correspondence to M.E.S. (e-mail: drsakarya@yahoo.com).
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ABSTRACT
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The purpose of this study was to evaluate the feasibility of using an open-configuration magnetic resonance (MR) imaging system with MR fluoroscopic guidance to perform percutaneous transthoracic fine-needle aspiration biopsy in patients with lung masses. Percutaneous transthoracic aspiration biopsies were performed with MR fluoroscopic guidance in 14 patients. The masses were 2–7 cm in diameter (mean, 4.1 cm). The needle was positioned by using a free-hand technique with MR fluoroscopic guidance. The needle tip reached the target lesion, and biopsy was performed. Analysis of the biopsy specimens facilitated a specific diagnosis in all patients. Pneumothorax was noted in two patients (14%) with chronic obstructive pulmonary disease. Study results showed that the described MR fluoroscopy–guided transthoracic biopsy technique can be used safely and successfully for lung masses. MR fluoroscopy can be used to reach the target lesion easily and accurately.
© RSNA, 2003
Index terms: Lung, biopsy, 60.126 • Lung neoplasms, 60.30 • Lung neoplasms, MR, 60.121412, 60.12149 • Magnetic resonance (MR), guidance, 60.121411, 60.121412, 60.12149
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INTRODUCTION
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Computed tomography (CT) has been both a standard imaging modality and a guidance technique for percutaneous interventions for 25 years (1,2). In contrast to conventional fluoroscopy, ultrasonography (US), and magnetic resonance (MR) fluoroscopy as interventional guidance tools, CT is limited by a lack of real-time capability. Although CT enables determination of appropriate puncture sites, a time-consuming acquisition of multiple images is required to determine the direction of the needle insertion and evaluate the needle placement after insertion. Also, CT does not allow real-time evaluation during the puncture procedure. CT guidance may be particularly limited in regions of the body that are associated with physiologic motion, especially regions in the chest (3).
To overcome these limitations, CT fluoroscopic systems that enable real-time image reconstruction and display of CT images on a monitor were developed. These applications are possible owing to synergistic and dynamic advances in CT technology and computer hardware (4). Since the introduction of the first CT fluoroscopic scanner in 1993, a variety of these systems have been installed worldwide, and many reports on the clinical use of these devices have been published (5–7). However, the use of this technology to guide interventional radiologic procedures, such as percutaneous biopsy and drainage, is not uniformly accepted by interventional radiologists. Concerns about the radiation exposure and procedural outcomes with fluoroscopic CT, as compared with those with sequential CT guidance and other guidance modalities, have been reported (8–11). On the other hand, the ability to perform interventional procedures with a nonionizing imaging source is of great interest.
MR imaging is an established alternative to CT for evaluation of the thoracic vasculature and mediastinal, hilar, and chest wall abnormalities because it facilitates good soft-tissue contrast, has multiplanar capability and intrinsic flow sensitivity, and involves no ionizing radiation (12–15). More recently, interventional MR imaging with several magnet configurations was developed (16). Also, MR fluoroscopy enables cross-sectional imaging in near real time. The purpose of the present study was to evaluate the feasibility of using an open-configuration MR imaging system with MR fluoroscopic guidance to perform percutaneous transthoracic fine-needle aspiration biopsy in patients with lung masses.
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Materials and Methods
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Patients and Lesions
In this study, 25 consecutive patients with lung masses larger than 2 cm in diameter were scheduled to undergo MR fluoroscopy–guided transthoracic fine-needle aspiration biopsy during the years 2000–2001. The inclusion criteria required for the chest department physicians to refer patients to the radiology department were as follows: presence of a lung mass that could not be diagnosed with bronchoscopic interventions such as transbronchial biopsy or bronchoalveolar lavage and/or refusal to undergo bronchoscopy. Among the patients who met these criteria, however, those with severe chronic obstructive pulmonary disease, as determined with spirometric (Fukuda Sangyo ST-250 dry spirometer; Fukuda, Tokyo, Japan) measurement of a forced expiratory volume in 1 second of less than 30% of the predictive value (five patients); cardiac pacemakers (two patients); and/or a cerebral aneurysm clip that would render MR imaging unsafe (one patient) were excluded from the study. In addition, although three patients had lung masses and no contraindications to MR imaging, they also were excluded, because informed consent could not be obtained.
Thus, a total of 14 patients (nine men, five women; mean age, 58.4 years; age range, 21–69 years) were included in the study. Institutional review board approval for the study was obtained, and informed consent was obtained from all patients. During biopsy, an anesthesiologist (I.K.) was present to administer sedatives to and monitor the vital signs of the patients.
The masses were 2–7 cm in diameter (mean, 4.1 cm). Eight lesions (in eight patients) had diameters of 2–4 cm, and six lesions (in six patients) had diameters of 5–7 cm. Nine lesions were located in the upper lobes of the lungs (five in right lobes, four in left lobes), four were located in the lower lobes (two in right lobes, two in left lobes), and one was located in the right middle lobe.
MR Fluoroscopy–guided Biopsy
The open MR imaging system (Airis I; Hitachi, Tokyo, Japan) consists of a 0.3-T permanent magnet with an open configuration that allows access to the interventional field. The system is structured with disk-type magnets arranged at the upper and lower positions of the gantry frame and a 38-cm-tall open space of 210° in the front and 70° in the back. Once the patient was positioned within the body coil, the lesion was visualized on transverse T1-weighted (750/25 [repetition time msec/echo time msec]) and T2-weighted (2,100–2,500/90) MR images and on coronal T1-weighted MR images (750/25). To obtain MR fluoroscopic images, a surface coil was used. On the basis of the MR image findings, a superficial standard ring coil was placed on the area of the skin that was estimated to be nearest to the location of the lung lesion. The surface coil used in this study had a hole suitable for biopsy (Fig 1).
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Figure 1a. (a) Placement of a patient in the gap of the open MR imaging system and placement of the surface coil in a location on the skin estimated to be nearest to the lung lesion. (b) The surface coil has a hole suitable for biopsy, which was performed with MR fluoroscopic guidance.
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Figure 1b. (a) Placement of a patient in the gap of the open MR imaging system and placement of the surface coil in a location on the skin estimated to be nearest to the lung lesion. (b) The surface coil has a hole suitable for biopsy, which was performed with MR fluoroscopic guidance.
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A surface localizer made of fish oil capsules was used to determine the needle entry point. The capsules were taped to the skin linearly in the sagittal plane in the hole of the surface coil. Multiple T1-weighted transverse MR images were obtained, and the ones that best depicted both the lesion and a fish oil capsule were chosen. The location of the visualized capsule on the skin was designated as the needle entry point. The fish oil capsules were then removed from the skin.
After routine skin preparation and sterilization with 10% povidone-iodine (Batticon; Adeka, Samsun, Turkey) and administration of a local anesthetic agent (lidocaine hydrochloride, Aritmal; Biosel, Istanbul, Turkey), a small (3–4-mm) incision was created to allow passage of the needle. MR fluoroscopy was initiated at the assigned entry point. MR fluoroscopic images were obtained continuously during the biopsy. The needle trajectory was parallel to the oblique coronal plane in only one patient. In the other patients, the trajectory was parallel to the transverse or coronal plane. This technique allowed the entire needle to be seen on the image section and thus the needle tip to be traced during the biopsy.
The biopsy needle was inserted with MR fluoroscopic guidance. The direction of the needle in the thorax was maintained by two radiologists working simultaneously. While one radiologist (M.E.S.) advanced the needle, the other (O.U.) helped to direct the needle by monitoring its movement from the console. With the radiologist monitoring the advancing needle by using MR fluoroscopy, the needle tip reached the target lesion and aspiration biopsy was performed. The same two radiologists (M.E.S., O.U.) performed biopsy in all 14 patients. Twenty-gauge, 15–20-cm-long MR-compatible titanium Chiba needles (Cook, Bloomington, Ind) were used.
In cases of an insufficient amount of biopsy material, biopsy sampling was repeated. Consequently, a sufficient amount of biopsy material was obtained during one sampling in nine patients, during a second sampling in four patients, and during a third sampling in one patient. Biopsy duration was defined as the time during which the patient was on the table.
MR fluoroscopy was performed with a spoiled gradient-echo sequence, which enables image acquisition in near real time because images are generated, reconstructed, and displayed continuously. MR fluoroscopy was performed with 16/4, a 30° flip angle, a 256 x 92-pixel matrix, a 350-mm field of view, a 10-mm section thickness, one signal acquired, an imaging time of 1 second, and a reconstruction time of 1 second.
Postintervention Evaluations
Spirometric evaluations were performed by two authors (B.O., K.U.). After the biopsies, these two authors observed all of the patients for possible clinical complications, such as hemoptysis and syncope. Four and 8 hours later, chest radiographs were obtained and evaluated for pneumothorax by two other authors (M.E.S., O.U.). After the sufficiency of the biopsy materials was evaluated, pathologic diagnostic examinations were performed by a pathologist (S.O.).
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Results
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All 14 patients tolerated the MR fluoroscopy–guided biopsy well. Mean biopsy duration was 19 minutes (range, 15–28 minutes). Mean total MR imaging room time, including the time it took to perform biopsy, was approximately 26 minutes (20–38 minutes). Vital structures, including the heart and main vessels, were visualized at MR fluoroscopy without contrast agent enhancement. This property of MR imaging enabled the radiologists to distinguish these vital structures and avoid them during biopsy (Figs 2, 3). The biopsy needles were clearly depicted with low signal intensity in all of the lung masses on the MR fluoroscopic images. Respiratory motion was not a problem because MR fluoroscopic guidance yielded near-real-time images.
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Figure 2a. Infection and fibrosis in the left upper lung lobe of a 21-year-old man. Transverse (a) T1-weighted (750/25) and (b) T2-weighted (2,120/90) MR images show a lesion (arrow) adjacent to the left side of the heart and an enlarged lymph node (arrowhead in a) in the left hilum. (c) Transverse MR fluoroscopic image (20/4) shows a finger at the needle entry site on the skin. The arrow is pointing to the paracardiac lesion. (d) MR fluoroscopic image (20/4) obtained during aspiration biopsy shows the MR imaging-compatible biopsy needle (arrow) inside the lesion.
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Figure 2b. Infection and fibrosis in the left upper lung lobe of a 21-year-old man. Transverse (a) T1-weighted (750/25) and (b) T2-weighted (2,120/90) MR images show a lesion (arrow) adjacent to the left side of the heart and an enlarged lymph node (arrowhead in a) in the left hilum. (c) Transverse MR fluoroscopic image (20/4) shows a finger at the needle entry site on the skin. The arrow is pointing to the paracardiac lesion. (d) MR fluoroscopic image (20/4) obtained during aspiration biopsy shows the MR imaging-compatible biopsy needle (arrow) inside the lesion.
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Figure 2c. Infection and fibrosis in the left upper lung lobe of a 21-year-old man. Transverse (a) T1-weighted (750/25) and (b) T2-weighted (2,120/90) MR images show a lesion (arrow) adjacent to the left side of the heart and an enlarged lymph node (arrowhead in a) in the left hilum. (c) Transverse MR fluoroscopic image (20/4) shows a finger at the needle entry site on the skin. The arrow is pointing to the paracardiac lesion. (d) MR fluoroscopic image (20/4) obtained during aspiration biopsy shows the MR imaging-compatible biopsy needle (arrow) inside the lesion.
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Figure 2d. Infection and fibrosis in the left upper lung lobe of a 21-year-old man. Transverse (a) T1-weighted (750/25) and (b) T2-weighted (2,120/90) MR images show a lesion (arrow) adjacent to the left side of the heart and an enlarged lymph node (arrowhead in a) in the left hilum. (c) Transverse MR fluoroscopic image (20/4) shows a finger at the needle entry site on the skin. The arrow is pointing to the paracardiac lesion. (d) MR fluoroscopic image (20/4) obtained during aspiration biopsy shows the MR imaging-compatible biopsy needle (arrow) inside the lesion.
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Figure 3a. Squamous cell carcinoma in a 57-year-old man. (a) Coronal T1-weighted MR image (750/25) shows a large right hilar mass (*) and multiple enlarged mediastinal lymph nodes. (b) Coronal T1-weighted MR image (200/25) shows a localizer made of fish oil capsules (arrowheads) that is used to determine the biopsy needle entry site on the patient’s skin. (c) Coronal MR fluoroscopic image (16/4) obtained during transthoracic needle aspiration biopsy shows the biopsy needle (arrow) inside the lesion.
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Figure 3b. Squamous cell carcinoma in a 57-year-old man. (a) Coronal T1-weighted MR image (750/25) shows a large right hilar mass (*) and multiple enlarged mediastinal lymph nodes. (b) Coronal T1-weighted MR image (200/25) shows a localizer made of fish oil capsules (arrowheads) that is used to determine the biopsy needle entry site on the patient’s skin. (c) Coronal MR fluoroscopic image (16/4) obtained during transthoracic needle aspiration biopsy shows the biopsy needle (arrow) inside the lesion.
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Figure 3c. Squamous cell carcinoma in a 57-year-old man. (a) Coronal T1-weighted MR image (750/25) shows a large right hilar mass (*) and multiple enlarged mediastinal lymph nodes. (b) Coronal T1-weighted MR image (200/25) shows a localizer made of fish oil capsules (arrowheads) that is used to determine the biopsy needle entry site on the patient’s skin. (c) Coronal MR fluoroscopic image (16/4) obtained during transthoracic needle aspiration biopsy shows the biopsy needle (arrow) inside the lesion.
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Biopsy tissue that was sufficient to facilitate a diagnosis was retrieved from all patients. The diagnoses that resulted from the 14 lung biopsies were metastatic osteosarcoma (n = 1), metastatic adenocarcinoma from unknown primary cancer (n = 2), squamous cell carcinoma of the lung (n = 4), small cell bronchogenic carcinoma (n = 1), adenocarcinoma (n = 3), abscess (n = 2), and fibrosis (n = 1). The distances between the needle entry site and the target lesion were 4.0–15.0 cm (mean, 7.5 cm).
On the chest radiographs obtained 4 hours after biopsy, pneumothorax was noted in two patients (14%) with chronic obstructive pulmonary disease. One patient had asymptomatic pneumothorax, and the other had symptomatic pneumothorax that was treated with chest tube insertion. The findings in the asymptomatic patient at chest radiography performed 8 hours after biopsy had not changed, and the patient’s condition was stable. During biopsy, one patient experienced mild bradycardia and hypotension, both of which resolved in response to intravenous administration of atropine. Hemoptysis occurred in two patients but required no intervention.
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Discussion
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Since the initial report on the development of CT fluoroscopy by Katada et al (17), several studies have been performed to evaluate the applicability of and feasibility of using this imaging guidance modality for a variety of nonvascular and vascular interventions. With the increasing clinical applications of CT fluoroscopy, there have been controversial reports of the advantages and disadvantages of this guidance modality—especially those concerning radiation exposure, procedural times, and patient outcomes (9,10).
MR fluoroscopy offers guidance and monitoring advantages that enable one to perform biopsy and cross-sectional imaging in near real time. The advent of MR fluoroscopy has made it possible to obtain images at a rate that can be considered real time in terms of effectiveness. Image rates can be as low as 1 second, which is fast enough to facilitate MR imaging guidance of biopsy procedures. Such procedures include the localization of biopsy needles within a tumor and the localization of surgical tools for administering therapeutic drugs (18).
With percutaneous biopsy and most image-guided interventions, targeting the lesion is the most difficult task technically because if the needle is not correctly directed toward the target, a separate pass with a different trajectory will be required. Distance is less important: If the needle trajectory is correct but the needle is beyond the target, the needle can be withdrawn. If the needle is just before the target, it can be advanced. This is why selecting the correct angle or trajectory to aim the needle is the most difficult technical task. The technique that we used in the present study enables one to combine the advantages of MR tissue characterization, depiction of anatomic features, and multiplanar imaging with the ability to perform near-real-time MR fluoroscopy. Near-real-time images are acquired because new images are generated every 1 second.
The described MR fluoroscopic guidance technique is based on the nearly immediate feedback of images to depict the needle, target, and surrounding structures while the needle is advancing. In this study, the positions of the lesions were affected by respiratory motion, but we were able to easily approach the target with near-real-time MR fluoroscopy. Therefore, we can say that in this study, MR fluoroscopy–guided biopsy was performed safely and accurately.
Our purpose was not to compare the MR fluoroscopic guidance technique with conventional guidance systems; however, relative to x-ray fluoroscopy, US, CT, and CT fluoroscopy, MR fluoroscopy theoretically offers advantages and disadvantages. A potential disadvantage of MR fluoroscopy is that the image feedback with this system is not as immediate as that with US, CT fluoroscopy, or x-ray fluoroscopy. However, the lack of true real-time imaging did not hinder our ability to guide biopsy in this study. With CT imaging, it is possible to identify fissures, focal areas of emphysema, or bulla and thereby avoid these areas during biopsy. MR imaging does not offer this advantage. MR imaging is not routinely used for evaluation of the lungs, mediastinum, or pleura in practice, but it is an established tool for evaluation of the thoracic vasculature and chest wall and is used as an alternative to CT for evaluation of the mediastinum in patients who are allergic to intravenous contrast agents.
The advantages of MR fluoroscopy are near-real-time imaging and the absence of radiation hazards. Real-time imaging is possible with US, x-ray fluoroscopy, and CT fluoroscopy but not with CT or conventional MR imaging. US assists in guidance, but this guidance is very limited in the biopsy of lung lesions. X-ray fluoroscopy introduces radiation hazards and requires changing the projection to achieve three-dimensional localization. With x-ray fluoroscopy, all tissues in the path of the x-ray beam are displayed, and the examination does not have any specific plane. CT fluoroscopy also involves radiation exposure.
The results of this study demonstrate the feasibility of performing percutaneous transthoracic fine-needle aspiration biopsy with an open MR imaging system and MR fluoroscopic guidance in patients with lung masses. This technique enables interventions to be performed with image feedback in near real time. The described open low-field-strength interventional MR fluoroscopic technique seems to be potentially useful for interventional procedures. We expect interventional imaging procedures performed with an open MR imaging system and MR fluoroscopy to be useful in interventional thoracic radiology in the future because of the following advantages: no irradiation, easy accessibility to the target lesion from any direction, and excellent soft-tissue contrast. We used this technical application safely and successfully in patients with lung masses larger than 2 cm in diameter. Whether this technique is useful for patients with lung masses smaller than 2 cm in diameter warrants further evaluation.
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FOOTNOTES
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Author contributions: Guarantors of integrity of entire study, M.E.S., O.U.; study concepts, M.E.S., O.U.; study design, O.U.; literature research, O.E., M.E.S.; clinical studies, I.K., B.O., K.U.; data acquisition and analysis/interpretation, S.O., O.U.; statistical analysis, M.E.S.; manuscript preparation, B.O., O.E., M.E.S.; manuscript definition of intellectual content, editing, revision/review, and final version approval, M.E.S., B.O.
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ABSTRACT
INTRODUCTION
