Cardlovasc Inter"ventRadiol (1992) 15251-253

CardioVascular andInterventional Radiology 9 Springer-Verlag New York lnc 1992

Technical Notes

Modified Tru-Cut Needle with Exchangeable Blunt Styler for Safe Puncture: Technical Note Klaus-Christian Klose Department of Diagnostic Radtology, RWTH Aachen, Aachen, Federal Republic of Germany

Abstract. A modified Tru-Cut needle has been developed to safely bypass interposed vital structures during large-bore biopsies of solid lesions in various regions of the body. The needle allows blunt advancement in critical locations and facilitates accurate pin-point advancement when needed. The needle performed as designed in computed tomography (CT)-guided biopsies of 31 solid lesions. Key words: Biopsy--Large-bore needle--Tru-Cut --Complications--CT guidance

Histology has a higher diagnostic yield than cytology in diagnosing and classifying noncarcinomatous tumors [ 1]. However, use of large-bore biopsy needles that provide histologic specimens is restricted to lesions that can be approached by safe access routes. For this reason, histologic specimens may not be obtained from regions bearing a high risk of access such as mesenteric, pelvic, intertoop, and mediastihal locations. The use of a modified, large-bore TruCut needle overcomes this problem.

Material and Methods The system comprises a commercially avadable (Angiomed, Kartsruhe, Germany) modified 14-gauge Tru-Cut needle equipped with an additional stopper on the handle, an ordinary sharp stytet, and an addittonal blunt styler (Fig. IA-D). The stylets may be exchanged for each other. The blunt stylet differs from the ordinary sharp stylet only by the configuration of the tip (Fig tA.B). The additional stopper on the handle 5 mm behind the first stopper allows fixation of the blunt stylet halfway through the bevel (Fig. IC).

Address reprint requests to: Klaus-Christian Klose, M.D., Department of Diagnostic Radiology, RWTH Aachen, Pauwelsstr. 30, D-5100 Aachen. Federal Republic of Germany

Technique Our technique of computed tomography (CTJ needle gmdance has been previously described in detail [2]. Briefly. the precise position and depth of the target relative to a specific entry point on the skin Js determined on CT. For access to the peritoneal cavity only, such skin entry sites are selected and subsequentl.,, used that do not show underlying bowel abutting the transverse fascia on the way to the target After local anesthesia (lidocaine 15;), the structure that a biopsy is to be done on is approached imhally with the Tru-Cut needle eqmpped with the sharp inner st vlet to penetrate the thoracic or abdominal wall tFlg. IA). After penetratton of the abdominal or thoracic wall, the sharp styler is e~,changed for the blunt styler I FJg. I B), and ~s further advanced on the predetermmed route to the target until resistance is felt. When control CT demonstrates that the resistance is due to a vital organ such as bowel or a large vessel, the needle positzon ~,, corrected. When the resistance zs due to fasclal planes, the blunt stylet ~s retracted to the additional stopper {Fig. IC). Further gentle advancement of the needle towards the fascia cuts a "'halt: moon" into the fascial plane because in the posterior stopper position the blunt ttp of the stytet restricts the cutting edge of the cannula to a half-circle cut and creates a notable resistance to further cutting that prevents inadvertent further advancement of the needle. The residual fascmt resistance may be readily penetrated with the needle in ItS completely blunted condition (F~g. 1B). When the target is reached by the blunt needle, three modalihes are available for obtaining biopsy specimens, depending on the rigidity of the lesion to be blop~led. In ill-defined, nonencapsulated soft-tissue lesions, the blunt styler may be fully advanced into the lesion (Fig. tD) and the biopsy may be completed by further advancement of the sharp cannula over the blunt styler In well-defined, capsulated soft-tissue lesmns, however, the blunt stylet is retracted to the additional stopper and the biopsy system in its "semi-blunt'" condition is fully advanced into the lesion. Then, the biopsy specimen ~s obtained by moving the cannula back and forth over the styler left in place. Only in hard lesions, the blunt stylet is exchanged for the ordinary sharp stylet and the biopsy procedure is completed in the usual manner.

Results Over the past 3 years use of the modified Tru-Cut needle has been highly successful in gaining percutaneous access to a wide variety of locations. These include an interloop access to the peritoneal cavity in 14 patients and to the pelvis in 9 (Fig. 2), an

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K.-C. Klose: Modified Tru-Cut Needle with E x c h a n g e a b l e Blunt Styler

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Fig. 2. Interloop a c c e s s to an all-defined pelvic m a s s (asterisk) which c a u s e s m a r k e d s t e n o s i s of the sigmoid colon. A The posterior wall of the urinary bladder (B~ is separated from the anterior b o r d e r o f t h e tumor~arrows). B The needle tip in place Histology: metastatic gastric c a r c i n o m a .

interaortocaval acces~ to the middle mediastinum in 2 (Fig. 3), and a supraaortal access to the paratracheal part of the supraaortic mediastinum in 6. All target lesions were sohd and included malignancies in 23 cases and benign lesions in 8. Access to the desired structure ~ a s obtained in all cases, in no case were interposed hollow viscera or major blood vessels penetrated, as shown by CT scans. There were no complicationb related to this specific technique. No pert'oration o f hollow viscera such as the bowel or urinary bladder occurred. No major hemorrhage in the access route was evident.

Discussion

The system is designed to take advantage of the high diagnostic yield of large-bore biopsy while avoiding the possibly severe procedural trauma associated with previous ordinary large-bore biopsy systems. So, it permits histologic evaluation even of lesions

K.-C. Klose: Modified Tru-Cut Needle with Exchangeable Blunt Stylet

considered inaccessible for large-bore biopsy cannulas because of the high risk of access. The risk of large-bore biopsies with use of the blunt cannula appears minimal. A risk still remains when the sharp Tru-Cut cannula penetrates the abdominal wall with the bowel adjacent as considerable pressure must be brought up to overcome the muscular resistance. To minimize this risk, it is recommended to use a "'fat window," where the bowel does not abut the abdominal wall for access to ~he peritoneal cavity. Of the large-bore biopsy cannulas, the Tru-Cut cannula has been shown to provide the highest specimen weight [3]. Another advantage of any Tru-Cut needle with exchangeable styler is the possibility for

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repeating the biopsy while the cannula is left in place, thereby avoiding the risk and the time of repeated needle placement.

References I. Bocking A (t990) Histology or cytology in percutaneou~ biop,ms. Cardiovasc Intervent Radiol 14:7-ll 2. Klose K-C, Mertens R, Alzen G, LOer F, Bockmg A (1990) CT-guided percutaneous ta,ge-bore biopsies in bemgn and malignant pediatric lesions. Cardiovasc lntervent Radlol t4:78-83 3. Haaga JR. LiPuma JP, Bryan PJ, Balsara V J, Cohen AM 11983) Clinical compari.~on of a .~mall caliber cutting needle with large caliber cutting needle~. Radiology 146665-667

Modified Tru-Cut needle with exchangeable blunt stylet for safe puncture: technical note.

A modified Tru-Cut needle has been developed to safely bypass interposed vital structures during large-bore biopsies of solid lesions in various regio...
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