Equipment and Biopsy

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56 D.J. Grand and W.W. Mayo-Smith

cephalad from that point of the skin entry site. The needle trajectory distance is the

length of the hypotenuse of the right triangle.

Gantry angulation involves a slight tilt of the gantry to create an oblique axial image

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allowing the needle to course caudal to cephalad in the oblique axial plane of the image

and making imaging of the entire needle possible if it stays in this plane.

If this is not possible, a direct prone, trans-hepatic, or even an anterior approach may be

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utilized.

Equipment and Biopsy

A coaxial needle biopsy device is preferred as it allows the operator to obtain multiple

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samples without repositioning the outer needle (Fig. 2).

Generally, 16–19G outer needles are used.

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Placement of the coaxial introducer allows both passage of an aspirating needle (19–

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22G) for FNA and a core needle (17–20G) for cores.

Scout CT images are obtained and the skin entry site is marked. Anesthetize the skin

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and deeper soft tissues with local anesthetic.

Advance the outer 19G needle of the coaxial system to the adrenal margin.

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Place the20G biopsy needle coaxially through the 19G needle so it extends through the

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adrenal mass.

Fig. 1 Pre-procedural CT image in patient with indeterminate right adrenal mass. The patient is in the

right lateral decubitus position and the procedure is planned using measurements on the CT console

57 Adrenal Biopsy

Obtain at least two passes through the adrenal mass for surgical pathology.

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We observe patients in a holding area for 1 h post procedure.

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Patients do not typically require post-procedural analgesia.

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Discharge instructions are provided and patients are discharged in the care of a guard-

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ian. Patients are advised to contact their referring doctor for results of the biopsy in 3

days.

Results and Complications

Adrenal biopsy has a greater than 90% accuracy, a sensitivity of 81%, and a specicity

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of 99%.

The positive predictive value of 99% makes adrenal mass biopsy very useful in staging

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established extra-adrenal malignancy such as lung cancer.

The negative predictive value of 80% makes adrenal biopsy less useful to separate

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benign from malignant conditions.

Complication rate is under 3%.

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The most common complication is hemorrhage.

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Other potential complications are rare and include pneumothorax, adjacent organ injury

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(kidney, pancreas, bowel), infection, or hypertensive crisis if an unsuspected pheochro-

mocytoma undergoes biopsy.

Fig. 2 CT uoroscopic image during adrenal biopsy in same patient. The inner needle extends to

the adrenal mass and the “trough” is deployed through the lesion (arrow)

D.J. Grand and W.W. Mayo-Smith

Renal Biopsy

Onofrio A. Catalano and Anthony E. Samir

Clinical Features

47–61% of renal cancers are discovered incidentally.

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20% of solid renal masses of 3–4 cm are benign, 46% of solid renal masses of <1 cm

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are benign.

Small renal masses (<3 cm) are very slow growing (1–2 mm/year).

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Renal cell cancer constitutes the most common kidney cancer and accounts for 12,000

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deaths/year in the USA.

Indications

Indications for solid renal mass biopsy continue to evolve. The following are generally

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accepted:

In the settings of known primary extrarenal malignancy, to differentiate meta-

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static from concurrent primary renal tumor.

To establish a diagnosis when infection is thought to be a potential etiology

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of a focal renal lesion.

Prior to tumor ablation, where a specimen will not be available for pathologic

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evaluation.

Borderline surgical candidates, where biopsy may obviate the need for surgery

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by diagnosing a fat poor angiomyolipoma. The evidence for this approach is

strongest for small masses, which have a higher pretest probability of benignity.

O.A. Catalano ()

Abdominal and Interventional Radiology Department, Massachusetts General Hospital,

Boston, MA, USA and SDN Istituto di Ricerca Diagnostica e Nucleare, Napoli, Italy

O.A. Catalano and A.E. Samir

Contraindications

No absolute contraindications.

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Relative contraindications: coagulopathy, relevant anatomy.

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General Principles

Patient Preparation

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Diet: Nil by mouth 4–6 h prior to the procedure

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Consent: Bleeding, infection, organ, nerve or vascular injury, pseudoaneurysm, and

non-diagnostic biopsy (~5%). Bleeding requiring admission or transfusion was reported

in 2% of 400 focal renal lesion biopsies at our institution, with no case requiring surgi-

cal or endovascular intervention.

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Coagulation: It is recommended that INR, PTT, platelets be routinely checked pre-

procedure.

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Antibiotics: Not routinely administered.

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Imaging: A recent intravenous contrast-enhanced CT or MR study of the upper abdo-

men is preferred, as it facilitates accurate pre-procedural planning. Hypertrophy of a

column of Bertin may simulate a focal mass lesion. Dedicated renal imaging by CT or

MR is able to distinguish between a mass and this anatomic variant.

Access

Depending on tumor location and relationship with surrounding structures, renal

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biopsies may be performed in the prone, supine, lateral decubitus, and oblique

positions.

A posterior approach with the patient in the lateral decubitus position with the side

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of the lesion dependent is preferred. This approach stabilizes the kidney within the

retroperitoneal fat, reduces renal respiratory motion, and reduces bowel and pulmo-

nary interposition. The renal vessels and collecting system are largest in the renal

sinus. Consequently, a biopsy trajectory that does not traverse the renal sinus is

preferred.

Image Guidance

Computed tomography (Fig.

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1) or real-time ultrasound guidance.

Contrast medium can be administered if better localization of the tumor is needed.

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Magnetic resonance guidance provides better soft tissue contrast, and may be useful when

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intravenous contrast cannot be given but is only available in a few centers and is costly

owing to the need for MR compatible materials and increased procedure room expense.

Renal Biopsy

Sedation-Analgesia

Conscious sedation can be administered. One percent lidocaine is injected to anesthe-

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tize sensitive structures along the planned biopsy path.

Technique

Multiple ne-needle aspirates and/or core biopsies are obtained.

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In the case of partially cystic lesions, sampling of the solid portion is recommended.

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The author usually aspirates the cyst uid and then biopsies the remaining solid portion

of the lesion. Water-soluble contrast material may be injected into the cyst to demon-

strate mural irregularity and guide biopsy.

Fig. 1 Left kidney biopsy. A less than 3 cm exophytic lesion (curved arrow, (a)), arising from the

left kidney, was demonstrated on a CT performed for an unrelated indication. The patient was a

poor surgical candidate and biopsy was requested. The patient was placed in the left lateral oblique

decubitus position and the needle was advanced into the lesion (arrow, (b)). The post-procedure

scan revealed a small amount of expected perirenal hemorrhage and air (arrowhead, (c)). The

biopsy diagnosis was fat poor angiomyolipoma

62 O.A. Catalano and A.E. Samir

General Complications and Management

In ~2% of the cases, complications, most commonly hemorrhage, may require over-

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night hospital admission.

Post-procedure pain may be a manifestation of retroperitoneal bleeding; therefore, a

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pre-discharge CT scan is obtained in the few patients with more than usual puncture site

discomfort.

Pneumothorax, injury to adjacent organs, and renal colic secondary to obstruction of

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the collecting system by blood clots may all occur, but are very uncommon.

It is recommended that all patients be advised to seek medical care if they experience

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gross hematuria or symptoms of hypotension after discharge. This is exceedingly

uncommon.

Historically there has been concern regarding potential needle track seeding, but the

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risk is thought to be extremely low (<0.01%).

Tools for Biopsy

Needle Types

Fine-needle aspiration (FNA): 20–25G needles

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Core biopsy: 15–18G core biopsy needles, placed via a introducer system

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Specimen Handling

FNA specimens are placed in a cytological xing agent – either on slides or directly

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into a liquid preservative solution.

Core biopsies may be placed in saline or formalin depending on local pathology labora-

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tory preference.

If lymphoma is thought likely, it is recommended that a dedicated aspirate be sent for

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ow cytometry.

FNA Versus Core

The diagnostic yield of core biopsy is better than the diagnostic yield of FNA.

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FNA has the theoretical advantage of fewer complications, although this has not been

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proven in a prospective randomized trial.

In our experience performing both FNA and core via a coaxial needle system has a

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higher diagnostic yield than either technique alone and has a low complication

rate.

63 Renal Biopsy

Alternatives

Imaging surveillance is an alternative for small (

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£3 cm) renal masses in older patients,

as these lesions grow slowly and have low metastatic potential.

Post-Procedure Care and Follow Up

Observation for 2 h after biopsy and inspection of the patient’s urine prior to discharge

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is recommended. Bloodstained urine is normal after renal biopsy and generally resolves

after several days. Frank hematuria is uncommon. If present, a CT scan is recommended

to assess for a hemorrhagic complication.

Follow up imaging is performed for the majority of tumors which are benign on

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biopsy.