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Original Research |
1 Department of Radiology and Medical Informatics, Geneva University Hospitals,
Rue Micheli-du-Crest, CH 1211 Genève 14, Switzerland.
2 Division of Oncology, Geneva University Hospitals, Genève 14,
Switzerland.
Received August 26, 2004;
accepted after revision December 6, 2004.
Address correspondence to P. Loubeyre.
Abstract
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MATERIALS AND METHODS. The records of 75 consecutive patients (29 women, 46 men; age range, 33-92 years) who underwent percutaneous CT-guided adjustable coaxial 18-gauge multisampling (five samples) CNB of a suspected thoracic lesion (eight mediastinal lesions, two chest wall lesions, two pleural lesions, and 63 intrapulmonary lesions) were reviewed.
RESULTS. Ninety-seven percent (73/75) of CNB specimens were considered adequate for a specific diagnosis by the histopathology staff. Diagnostic yield was 97% (95% confidence interval, 91-99%) (72/74) (number of correct diagnoses obtained at CNB / number of definitive diagnoses). There were 61 malignant lesions and 11 benign lesions. There was no false-negative result when CNB was considered adequate for a specific diagnosis by the histopathology staff. Pneumothorax occurred in 19% (12/63 intrapulmonary lesions). One patient required placement of a chest tube. Minor postbiopsy hemoptysis occurred and resolved spontaneously in 11% (7/63) of patients.
CONCLUSION. Percutaneous CT-guided coaxial multisampling large CNB of suspected thoracic lesions, in a mainly cancer-based population, is an accurate procedure for a specific histologic diagnosis and has a low rate of complications.
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FNAB usually requires an on-site cytopathologist to evaluate the adequacy of the aspirates. The role of FNAB is predominantly to separate clearly benign from clearly malignant processes. A negative result for malignancy without a specific diagnosis of a benign lesion does not exclude the possibility of malignancy. The specific diagnosis of benign lesion or metastatic malignant lesion usually requires histologic specimens, which are inconsistently obtained via aspiration needles [3].
CNB with large needles usually provides cores of good quality that allow tumor architecture evaluation, numerous immunohistochemical stainings, and the performance of molecular biology in some circumstances [13]. A coaxial biopsy system allows a multisampling procedure.
Easy-to-use coaxial automated CNB systems are now available. A cannula is first inserted through the skin and toward the lesion with a single pleural passage (CNB of intrapulmonary lesions), and then the CNB system is passed through the cannula. The cannula remains in position during the sampling procedure, thus decreasing the potential risk of complications. When the direction of the cannula is slightly modified, multiple representative samples can be obtained in different portions of the lesion.
A trend in oncologic diagnosis workup has been clearly initiated in breast imaging toward performing multisampling large CNB to obtain samples of good quality and quantity to increase diagnostic accuracy [14]. In our hospital, the oncology and the pathology staffs have a pressing need for multiple large CNB specimens of thoracic nodules.
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During this period, 76 patients (29 women, 47 men; mean age, 65 years; age range, 33-92 years) were consecutively referred for multisampling CNB (two pleural lesions, two chest wall lesions, eight mediastinal lesions, and 63 intrapulmonary lesions). Informed consent for the procedure was obtained from each patient. Of the patients undergoing CNB, 60% did so as outpatients.
Materials
An adjustable coaxial 17-gauge automated CNB system (Temno Biopsy System,
Allegiance Health Care) was used. The system consists of a 17-gauge (1.48-mm
diameter) outer cannula with an introducer stylet that is used for positioning
the outer cannula. Once its tip is on the surface of the lesion, the stylet is
taken out and an 18-gauge (1.25-mm diameter) central cutting biopsy needle is
passed through the cannula for biopsy sample. The biopsy system is passed
through the cannula as many times as the desired number of samples. The sample
notch size can be selected from a minimum of 9 mm long to a maximum of 24 mm
long—and thus adapted to the size of small lesions—by turning a
coaxial bolt (Fig. 1). For
lesions greater than 25 mm, the maximum sample notch size is selected.
Procedure
Coagulation screening was performed before all procedures (exclusion
criteria for the biopsy were a prothrombin time < 60% or a platelet count
< 50 x 103/µL). Premedication was generally not
given.
Before the biopsy procedure, all available thoracic images were reviewed to localize the lesion and to plan the optimal patient position that allowed the best access route to avoid ribs, vessels, bullae, and fissures. The biopsy procedure was standardized and performed only by an experienced staff interventional radiologist.
All biopsies were performed with MDCT guidance (Mx 8000 scanner; Philips Medical Systems). The patient was positioned in a prone (n = 30), supine (n = 28), or lateral decubitus (n = 17) position, depending on the location of the lesion. Selected images were obtained in the area of interest (1.5-mm beam collimation, 3-mm reconstruction thickness, 3-mm reconstruction interval, 1.25 pitch, 0.75-sec rotation time, 120 kVp, and 180 mAs).
Patients were told to breathe in a slow, regular, and shallow manner during the duration of the biopsy procedure and during acquisition of images. It is our personal experience that breathing instructions, such as suspended inspiration or expiration, raise the difficulty of the procedure because they are not always reproducible.
The selected entry site was prepared and draped in a sterile fashion. For mediastinal lesions, extrapleural access was achieved in all patients with the injection of 10 mL of saline and 10 mL of 2% lidocaine hydrochloride (Xylocaine, AstraZeneca) into the paravertebral or substernal extrapleural space to create or expand an extrapleural window for a direct mediastinal approach [15]. A ventral parasternal access route was used in seven patients, and a dorsal paravertebral access route, in one patient.
Chest wall lesions were biopsied after administration of local anesthesia using 5 mL of Xylocaine. For pleural and pulmonary lesions, a local anesthesia using 5 mL of Xylocaine was carefully administered in small increments into the chest wall. The injection was stopped before the needle crossed the pleura. An additional 5 mL of Xylocaine was injected under the pleura. CT was used to check the position of the needle tip after each increment. Biopsy was begun 5 min after completion of local anesthesia.
Biopsy of Pulmonary Lesions
The introducer needle (17-gauge) was carefully aligned in small increments
in the chest wall before crossing the pleura. Repeated CT was performed during
the advancement of the needle to assess whether the needle trajectory was
satisfactory. Once the introducer needle was correctly aligned, a single
puncture of the pleura was made and the needle was advanced beyond the pleura.
If the needle was misaligned, the introducer was repositioned in small
increments without exiting the lung. Once CT confirmed satisfactory needle
position, the introducer needle was advanced into the edge of the lesion, and
a CT control image was obtained to ensure accurate positioning of the
introducer needle at its contact with the lesion. Then the stylet was taken
out and the cannula remained in position during the sampling procedure. The
biopsy system was passed through the cannula.
For each biopsy procedure, five cores considered macroscopically adequate by the radiologist were obtained by slightly modifying the direction of the cannula. The criterion for macroscopically adequate core was extraction of a sharply cut tissue core. No CT control was obtained between each sample harvesting. Duration of sample harvesting was less than 2 min.
Biopsy samples were preserved with formalin, or placed in saline when there was a suspicion of lymphoma, and immediately sent to the pathology department along with a sheet summarizing the clinical history of the patient. The histopathology staff of our hospital reviewed all biopsies. Histopathology reports were retrospectively reviewed for evaluation of the diagnostic yield of CNB.
Search for Complications
After removal of the biopsy system, CT was immediately used to search
around the puncture site for postbiopsy complications, pneumothorax, or
parenchyma hemorrhage. Parenchyma hemorrhage was seen on CT as an area of
air-space attenuation in the region of the lesion or along the tract of the
cannula.
When immediate pneumothorax developed, the distance between the pleura visceralis and the parietalis was measured on CT. If a small, asymptomatic, immediate pneumothorax developed, the patient was treated conservatively with monitoring of vital signs and administration of oxygen by nasal cannula (2 L/sec). The placement of a chest tube was reserved for patients with signs of respiratory distress or shortness of breath.
After the Procedure
All patients were placed in a puncture-side-down position and transferred
to a holding unit. Immediate or delayed hemoptysis was recorded.
A posteroanterior expiratory chest radiograph with the patient erect was systematically obtained 4 hr after the patient underwent biopsy. If parenchymal hemorrhage was local or pneumothorax was asymptomatic and there was less than 1 cm between the pleura visceralis and the parietalis, the outpatient was discharged with postdischarge instructions. Outpatients were instructed to return to the nearest emergency department if they developed symptoms (substantial pain, shortness of breath) after leaving our hospital.
Statistical Analysis
A CNB specimen was considered adequate when histopathology made a specific
malignant or an unequivocal specific benign diagnosis. A CNB specimen was
considered inadequate when histopathology could not make a specific
diagnosis.
The histologic finding of an adequate CNB specimen was taken as the true nature of the lesion. Nevertheless, CNB findings of specific benign nonneoplastic conditions were correlated with findings at surgery, response to relevant therapy, or findings at the 12-month clinical follow-up.
The "true nature" of the lesion that was taken as the criterion standard for evaluation of the diagnostic yield of CNB was therefore established according to the histologic finding of typical features of a benign or malignant tumor in the CNB specimen, or according to surgical findings, response to relevant therapy, or findings at the 12-month clinical follow-up for lesions with a histologic finding of a benign nonneoplastic condition.
A patient in whom the histologic finding of the CNB specimen was a specific benign nonneoplastic condition and in whom a final diagnosis was unavailable, was not included in statistical analysis for diagnostic yield. Patients in the false-negative group included those in whom the histologic finding of the CNB specimen was a specific benign nonneoplastic condition and subsequent surgery or follow-up did not support that finding.
Correlation of the rate of pneumothorax with the diameter of the intrapulmonary lesions and with the distance of the intrapulmonary lesion from the pleural surface was performed using Fisher's exact test. Statistical significance was set at p < 0.05.
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Nineteen percent of patients (12/63 intrapulmonary lesions) had a small pneumothorax at the site of the puncture. Ten pneumothoraces were less than 1 cm from the pleura visceralis and parietalis. Two pneumothoraces were more than 1 but less than 2 cm. All pneumothoraces were initially managed conservatively. In one case (2%) (95% confidence interval [CI], 0.3-8.5%), 5 days after the biopsy procedure the placement of a chest tube was decided on for a patient with signs of shortness of breath. Chest radiography revealed that the pneumothorax was greater than 4 cm.
Table 2 summarizes the rate of pneumothorax according to the diameter of intrapulmonary lesions and the distance of the lesions from the pleural surface. No significant correlation was found (p > 0.05). Parenchymal local hemorrhage around the lesion was noted on postbiopsy CT in 22% (14/63) of intrapulmonary lesions. Six patients had minor postbiopsy hemoptysis that resolved spontaneously within 2 hr in all patients.
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CNB specimens were considered adequate for specific diagnosis by the histopathology staff in 97% (73/75) of lesions (Table 3). Diagnostic yield (72/74 lesions) (number of correct diagnoses obtained at CNB / number of definitive diagnoses) was 97% (95% CI, 91-99%). In one case, the histologic result of CNB (chronic pneumonia with fibrosis) could not be confirmed (Table 3).
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No false-negative results occurred when CNB was considered adequate for specific diagnosis (Table 3). CNB specimens considered inadequate for a specific diagnosis by the histopathology staff occurred in 3% (2/75) of lesions (Table 4).
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In our hospital, physicians have a pressing need for histopathologic analysis of percutaneously biopsied thoracic nodules. With a coaxial CNB system, it is possible to obtain multiple cores of a lesion through a cannula. In our series, the complication rate of coaxial large-gauge multisampling CNB is not higher than that of other percutaneous thoracic biopsy techniques, including FNAB. Our rate of pneumothorax (19%) is in the range of those reported for other percutaneous thoracic biopsy techniques, which vary from 9% to 62% [1, 4, 6, 8-12, 16-18].
Most of our complications were small asymptomatic pneumothoraces and minor pulmonary bleeding that remained subclinical and was detected only on immediate postprocedure scans. Chest tube placement was only 2%.
Percutaneous CNB of thoracic lesions with a large (18-gauge) automated coaxial CNB system is an emerging procedure with an overall diagnostic yield reported to be as high as 88%, which is the highest overall diagnostic yield of all percutaneous thoracic biopsy techniques reported in the literature [6]. Until now, to our knowledge, the number of samples harvested has been limited (mean number of needle passes, 2.5) [6]. In our series, when increasing the number of samples and adapting the sample notch size to the size of the lesion, the diagnoses of various types of primary and secondary malignant tumors and benign conditions were obtained with an even higher diagnostic yield, without increasing the complication rate.
Our results have some limitations. Only experienced operators performed all biopsies. There was a low percentage of small lesions (29%) and a high percentage of intrapulmonary lesions with pleural contact (47%). This may have created a bias that might have led to an overestimation of the diagnostic yield and an underestimation of the complication rate. Our series contained a high prevalence of patients with malignancies, which reflects our specific recruitment of oncologic patients. No evaluation of possible false-positive biopsy results was performed because the true nature of the lesion, which was taken as the criterion for evaluation of the diagnostic yield of CNB, was established according to the histologic finding of typical features of a benign or malignant tumor in the core needle biopsy specimen. However, the probability of a false-positive result appears to be low.
We did not study correlation of the diagnostic yield with the number of samples harvested. Perhaps four or even three CNB samples would be enough to achieve the same diagnostic yield. We did not compare, for each patient, the diagnostic yield of cytologic analysis and histopathologic analysis. That was not the goal of our study and to do so would have complicated the procedure.
In conclusion, percutaneous CT-guided coaxial large-gauge multisampling CNB of suspected thoracic lesions is a safe procedure and an accurate tool for a specific histologic diagnosis. We think this message is important for physicians involved in oncologic diagnostic workup because of the pressing need to increase the quantity and quality of material sent to analysis. An on-site cytopathologist to evaluate adequacy of sampling may be not be necessary when this procedure is performed.
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1-cm) pulmonary
lesions. Radiology 2002;225
: 823-828
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