Tissue Biopsies

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Tissue Biopsies

Is the lesion to be biopsied a true abnormality, adequately documented (CT, ultrasound, MRI)? Is the lesion large enough to reasonably expect success targeting it? Is it accessible from the outside? Are there crucial organs in the way of the trajectory that you cannot cross (discuss with interventionalist)? Is the blood clotting function adequate? Can the patient tolerate a pneumothorax (in chest lesions)?

We Need Histology—Now!

Ann Hightower (62) has been sent to the oncology department by her general practitioner. She has not felt well for quite a while and has lost weight substantially. The initial tests already showed lesions suspicious of metastases in a number of different body locations, but the primary tumor has not yet been found. The oncologists urgently need the histological identification of the malignancy before they can decide which chemotherapy protocol best to choose. They also want to get more information about possible primary tumors to be able to gauge her prognosis. Percutaneous tissue biopsies are a special passion of senior consultant Chaban. There is no place in the body his needles have not been, says a popular department rumor. Together with Hannah he scrutinizes all the imaging studies performed so far to find the most secure and most promising biopsy target area. He then sits down with Mrs. Hightower. He tells her all about complications (hemorrhage; infection; trauma to the nerves, vessels, and organs) as well as about the alternative procedures (surgery) and the potential emergency surgery. Mrs. Hightower gets just a little nervous after all this information. Chaban puts her hands into his and gives her a warm smile: "I can't remember the last complication of that sort—it is so long ago. And I will be at your side for the whole time. The two of us will do the job!" he beams at her. Mrs. Hightower relaxes a little and returns his smile. Chaban explains to Hannah the essential technique of tissue biopsy. The main objective is, of course, to get enough tissue for the histological and microbiological analysis and to hand it to the pathologists and micro-biologists in an optimal condition for further processing and diagnosis:

• Tissue cores for the histopathological analysis are stored in little containers containing 5% formaldehyde solution.

* Fluids for cytological analysis are deposited as small drops at the end of a microscopy glass slide, drawn out over it very carefully with a second glass, and then left to dry.

• Material for bacteriological analysis is deposited in sterile, dry or agar medium-filled plastic containers.

• Material for mycological analysis is deposited in sterile, dry plastic containers (if transport is anticipated to take time add a few drops of saline solution).

• Material for virological analysis is deposited in sterile plastic containers filled with saline solution.

• Procedures

Lung biopsy: When performing a percutaneous lung biopsy, pneumothorax is the most frequent complication and measures should be taken to minimize this risk. Lesions close to the pleura are often associated with adhesions in the pleural space, which reduces the risk of pneumothorax. To harvest several tissue cores without subsequent increased pleural injury, a coaxial outer needle is advanced through the pleural cleft into the lung parenchyma and the immediate vicinity of the lesion (Fig. 7.6a). The inner biopsy needle is then advanced through the coaxial outer needle and redirected until it touches the lesion (Fig. 7.6b). This needle consists of a hollow cutting needle surrounding an inner trocar with a specimen notch or chamber. The trocar is then slowly advanced through the lesion, where some tissue settles in the specimen notch (Fig. 7.6c). This tissue is then separated from the rest by the rapidly advancing cutting needle (Fig. 7.6d) and withdrawn with the biopsy needle (Fig. 7.6e). This procedure is repeated until a sufficient amount of material has been collected.

If a pneumothorax develops despite the precautionary measures, the pleural air can be sucked out of the pleural space via the coaxial needle toward the end of the intervention (Fig. 7.7). If that is not successful, a little drain can be inserted to prevent further complications from a clinically significant (symptomatic or enlarging) pneumothorax.

Mediastinal biopsy: When attempting a mediastinal biopsy, the interventionalist must face the following obstacles:

• Frequently the lesion is located retrosternally, always close to large vessels or the heart and often close to the pleura.

• The needle caliber must match the respective anticipated risk. The danger of an erroneous puncture of arteries is low with a biopsy needle that is advanced slowly because the pulsation of the vascular wall is— as in femoral artery puncture (see p. 100)—palpable and visible.

• Vulnerable relevant structures can be pushed out of the way: here's how it works. The coaxial needle is advanced into the immediate vicinity of the pleura or the vessel that is to be avoided (Fig. 7.8). Then the stylet is removed and a pocket of saline fluid is deposited that shifts the vulnerable structure out of the way. The needle is then advanced with caution in this so-called "saline tunnel" technique.

I Lung Biopsy

Rapidly advancing hollow needle

Chest wall Pleural space Pulmonary nodule

Coaxial needle Coaxial needle

Stiletto I C°re

Hollow cutting I neej|g needle

Stiletto (with lateral groove for tissue)

Rapidly advancing hollow needle

Stiletto

Fig. 7.6a To prevent tearing injury to the pleura when gathering several tissue samples, a coaxial needle is used to pass the pleural space. It is positioned in the immediate neighborhood of the lesion. b An inner cutting needle with a trocar (see text) inside is advanced into the margin of the lesion. c The trocar with a tissue chamber/notch is pushed into the lesion and some tissue comes to rest in its notch. d This tissue is separated from the rest by a swift forward motion of the outer needle, which has a cutting edge at its end. e Trocar and cutting needle are withdrawn together with the tissue sample and can be reused for subsequent runs.

Abdominal, pelvic, and retroperitoneal biopsies: Any needle inserted into the abdomen must avoid transgressing the colon and vessels to avoid infection and hemorrhage. Under CT guidance—preferably on a scanner with optional CT fluoroscopy mode—vulnerable structures can be evaded more easily (Fig. 7.9). Biopsy of parenchy-mal organs in the upper abdomen is undemanding if the lesion is not too small and the patient is cooperative.

But beware: if you are trying to biopsy a lesion that is small and only visible on the arterial phase of a multi-phasic CT, you'd better find some adjacent anatomical landmarks that you can recognize during the noncontrast guidance CT situation. Tissue biopsy of a solid renal tumor is generally contraindicated because the dissemination of malignant cells along the needle path is a rare but real risk in this entity.

Bone biopsy: Percutaneous biopsy of bone requires a different technique and can be much more painful than many other tissue biopsies. After subcutaneous and periosteal local anesthesia (Fig. 7.10a) and a little incision of the skin, an outer cannula with an inner trocar is advanced to the bone cortex and screwed through the cortex in a forceful turning motion. The tip of the cannula is threaded to facilitate the penetration of the bone. The cannula should hit the cortex at a 90° angle to prevent skidding of the cannula tip (Fig. 7.10b). Once in the marrow space, the trocar is then withdrawn and the cannula is screwed further into the bone (Fig. 7.10c). The bone core is retrieved under vacuum by retracting the cannula out of the bone. The specimen is removed from the lumen of the cannula with a blunt pusher and transferred into a formaldehyde solution.

Chaban selects a larger paravertebral mass for Mrs. High-tower's biopsy. He retrieves a sizable number of samples through his coaxial needle to give the pathologists enough tissue for their histological tests. Hannah and Chaban talk with their patient about all kinds of things during the intervention to keep her distracted and cheerful. And Chaban works rapidly. As he removes the coaxial needle and throws it into the bin, the patient asks just when Chaban is going to start that awful biopsy. "Why, it's all done with, Mrs. Hightower. You'll go back to the ward now and have a smashin' good cup of tea. You want to see the little worms we pulled out?" Mrs. Hightower gazes with interest at the fine stripes of tissue as they swim in the container with the formaldehyde. She expresses her gratitude and is brought back to the ward. During the intervention Hannah has pondered some thoughts that she now confides to Chaban: "What if you had really hit the aorta? Or another important vessel?" "You don't do anything as long as the patient doesn't crash; scan them a little later to assess the damage and then sit tight if you can. The blood clotting must be OK, that's for sure. If that's borderline, you'd better monitor the patient. But in the early days of angiography our forefathers thrust gigantic—in comparison to today—needles directly into the aorta via a paravertebral route—routinely and for angiographies of the lower extremities. Complications then were hardly reported. But—come to think of it—before the advent of CT and ultrasound they didn't have the means to see the complications," chuckles Chaban.

Tissue cores, patients, and clinicians must be treated right and have no time to spare.

I Pneumothorax after Lung Biopsy

I Pneumothorax after Lung Biopsy

Aorta Paravertebral

Fig. 7.7 a A needle inserted for application of local anesthetic marks the approximate puncture site for the coaxial needle. b During the procedure, a pneumothorax develops owing to the peripheral location of the nodule. c After sucking out residual air with the coaxial needle after the biopsy, the pneumothorax is gone. A follow-up chest radiograph four hours later was normal.

Fig. 7.7 a A needle inserted for application of local anesthetic marks the approximate puncture site for the coaxial needle. b During the procedure, a pneumothorax develops owing to the peripheral location of the nodule. c After sucking out residual air with the coaxial needle after the biopsy, the pneumothorax is gone. A follow-up chest radiograph four hours later was normal.

I "Saline Tunnel" Technique

I Pelvic Biopsy

Pneumothorax Pathway
Fig. 7.8a The coaxial needle touches both the sternum and the pleura. The retrosternal mass must be reached. b After the creation of a saline pocket, the pleura moves away from the sternum, opening up a path to the target region. The needle is advanced cautiously.

I Pelvic Biopsy

Intestinal Biopsy
Fig. 7.9 a An intestinal loop lies in the path of the coaxial needle targeted for a presacral infiltration. b By tilting the needle just a little during the advance, the loop is dodged. c Now the needle can enter the tumor. This was a recurring rectal carcinoma.

I Bone Biopsy

Radiology, We Have a Problem!

Niles Strongarm (54) has had trouble with his pancreas for a while. He treasures a beer now and then and a brandy after a good meal. Now he has developed his second bout of pancreatitis. The doctors on the ward are nervous because he has developed large areas of necrosis reaching down into the pelvis to the iliac vessels. And now Mr. Strongarm has become febrile. They fear superinfection and abscess formation of the necrotic areas. The situation does not tolerate any delay. Chaban has the patient sent straight down from the ward after having looked at yesterday's CT of the patient (Fig. 7.11a) together with Hannah. He has made sure that Mr. Strongarm's blood clotting is within normal limits. Because the intervention is urgent, he briefs the patient directly before the procedure in the waiting room.

Fig. 7.10a In a first step, a long needle is advanced to the periosteum and local anesthesia is applied. b Then the bone biopsy needle is directed to the same spot and screwed into the bone. c The position of the bone biopsy needle in the target area is verified.

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