Effectiveness and Safety of Image-Directed Biopsies: Coaxial Technique Versus Conventional Fine Needle Aspiration

Alan H. Appelbaum, MB, BCh, BAO, Thompson T. Kamba, MB, ChB, Ari S. Cohen, MD, Waleed G. Qaisi, MD, Robin H. Amirkhan, MD


South Med J. 2002;95(2) 

In This Article


In this study, all but one of the conventional biopsies was done with smaller gauge needles than the smallest gauge coaxial guide used. In addition, the number of needle passes was significantly higher when coaxial technique was used. This increased aggressiveness resulted in a significantly higher diagnostic yield for coaxial technique. In extrathoracic biopsies, the diagnostic yield was increased by 15%. However, there was no appreciable difference in the low number of complications between conventional and coaxial methods in extrathoracic biopsies. These results are similar to those from previous studies, which showed low complication rates in abdominal biopsies.[1,2,3,4,5,6] Although not addressed by our study, it has been our experience that coaxial technique decreases patient discomfort and the amount of time to complete a biopsy because repeated needle positioning is not necessary. We have also noticed that coaxial guides are easier to visualize than conventional needles by both CT and ultrasound because of their larger gauges. On the basis of the increased diagnostic yield without detectable loss of safety, we recommend the use of coaxial technique for all image-guided extrathoracic biopsies, with possible rare exceptions. Because of the small number of thoracic biopsies done with coaxial technique in our study, we cannot assess its relative safety and effectiveness in the thorax. Use of coaxial technique was recommended for almost all thoracic biopsies in a recent article.[7]

In our study, no difference was found in the diagnostic yield between CT-guided and ultrasound-guided biopsies when a coaxial guide was used. (No ultrasound-guided procedures were done without a coaxial guide [Fig 1]). This contrasts with the results of a previous study that showed a higher diagnostic yield for ultrasound-guided procedures.[8]

Ultrasound guidance was used to place 17 gauge coaxial guide into exophytic mass in left lobe of liver. No complications occurred. Core biopsies and needle aspirations revealed metastatic squamous cell carcinoma.

Placement of a coaxial guide allows both core biopsy and fine-needle aspiration specimens to be obtained. Cytologic specimens not only provide a method for immediate confirmation of needle placement within a lesion, but also provide cytologic detail that is sometimes superior to that seen in core biopsies. Hence, cytologic specimens provide information complementary to that provided by core biopsy and frequently are diagnostic alone. Fine-needle aspiration is also useful when flow cytometric studies are needed because aspiration helps to separate and disengage the cells from surrounding stroma. Core biopsies show portions of the architecture, matrix, and border of a lesion and may provide a more definitive pathologic diagnosis when cytology is inconclusive.

In all series comparing core needle biopsy and fine-needle aspiration, cases were reported in which cytologic diagnosis was correct when histologic diagnosis was incorrect and vice versa.[5] Therefore, we chose to routinely obtain both types of specimen. However, if immediate cytologic analysis is done and the attending cytopathologist can make a definitive diagnosis from an aspirate, a core biopsy may be unnecessary. One may chose to do core biopsies first, since cytologic preparations may be prepared by touch, crush, or scrape preparations of core biopsy tissue, thus saving the expense of an aspiration needle (Figs 2 and 3) Touch preparations have previously been shown to adequately evaluate needle placement.[9] Crush and scrape preparations frequently yield more cells per slide than touch preparations but may destroy a core biopsy. Fortunately, this is usually acceptable when using a coaxial guide, since additional cores can be easily obtained in most cases. Frozen sections of core biopsies are also possible but are particularly difficult on core biopsies obtained with 18 or 20 gauge guns. Some institutions obtain multiple core biopsies and/or perform fine-needle aspiration without cytologic review of adequacy, which decreases the time and manpower necessary for the procedure (N. Evans, MD, oral communication, July 1999; M. Gavant, MD, oral communication, November 1999).

Touch preparation.

Crush preparation.

Bone Biopsy. All four coaxial and three of four conventional biopsies of bone tumors were successful (Fig 4). The cortex was eroded in all of these cases. Thus, bone biopsy can be done without bone biopsy needles in selected cases. If a coaxial guide is used and attempts at bone biopsy with standard needles fail, a trephine needle biopsy can be done without additional passes through overlying tissue. Passage of a trephine needle through a coaxial guide to perform bone biopsy has been described previously.[10]

Large lytic lesion of left iliac wing was discovered on computed tomography of abdomen done because of unexplained weight loss. A 17 gauge coaxial guide was placed through thinned cortex without difficulty. Multiple myeloma was diagnosed.

Biopsy of Suspected Lymphoma. Coaxial technique is particularly useful in the diagnosis of lymphoma because multiple specimens are essential for histologic, immunophenotypic, molecular, and cytogenetic studies. However, the use of percutaneous biopsy in the diagnosis of lymphoma is controversial and may not be adequate in every case. Subclassification of lymphomas depends, in part, on architectural arrangement of neoplastic cells, which may be more difficult to assess on core biopsy than on a surgically resected specimen and is impossible to assess on aspirates. Also, more than one cell type may be present (eg, T-cell-rich B-cell lymphoma), which could go undetected or be misinterpreted because of less extensive sampling. Despite these concerns, the diagnostic accuracy ranges from 68% to 94% for percutaneous biopsy of suspected lymphoma.[11] In addition, some patients can be treated without exact subtyping because of a definite previous diagnosis or poor prognostic indicators.[11] In two large series of lymphoma diagnoses by core biopsy, 72%[12] and 86%[11] of patients were treated on the basis of core biopsy results alone. In our series, 3 of 4 coaxial-guided biopsies of lymphoma were used to determine treatment.

Nonspecific and normal pathologic diagnoses are difficult problems in clinical practice and for this study. A normal pathologic diagnosis may represent the benign histology of a lesion seen on an imaging study (eg, adrenal adenoma) or may represent sampling error (eg, normal adrenal adjacent to a metastasis). Likewise, a nonspecific histologic diagnosis may represent the true histology of a lesion (eg, chronic inflammation and fibrosis may be the only findings in a chronic abscess) or may represent sampling error (chronic inflammation and fibrosis may be seen at the edge of a malignancy). We divided nonspecific and normal findings into adequate and inadequate categories according to whether the pathologic diagnoses were used to determine management. Since consultation between clinician, radiologist, and pathologist usually occurred when the biopsy was reported as nonspecific or normal and the various explanations were discussed, this is a reasonable way to categorize these cases as adequate or inadequate. Although we recognize that this method is subject to error, it is more accurate than placing all these cases into one category.

This study was done retrospectively and is subject to some of the usual limitations of this method. There were problems with incomplete data collection. Information on needle gauge and number of needle passes was available in 97 and 90 cases, respectively, of a total of 144. When a coaxial guide was used, the records rarely specified the number of passes made with a coaxial guide versus the number made through the guide. Although we believe that it is safe to assume that the increased number of needle passes found in coaxial biopsies resulted from an increased number of passes through the guide, we do not have data to support this. Fortunately, this is a peripheral issue in our study. Since individual attending physicians chose the biopsy technique that was used, selection bias could have been introduced. Almost all chest biopsies were done with conventional technique. We addressed this problem by calculating success rates with and without including the chest biopsies. The difference was minimal. Attending physicians may have chosen coaxial technique for more difficult cases. This would decrease the apparent diagnostic yield of coaxial technique. If such a bias existed in our study, an increase in diagnostic yield was shown nonetheless.


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