2.2.2 Techniques of PCNB
All biopsies were performed by pediatric surgical oncologists. Before PCNB, their cross-sectional imaging (CT/MRI) and ultrasonography were reviewed. Lesions were evaluated for adequacy of PCNB. If the tumor could be accessed directly under ultrasound without perceived high risks of injuries to adjacent important structures such as major vessels and bowels, then it would be considered appropriate for PCNB.
Informed consent for anesthesia (if general anesthesia would be applied) and biopsy was obtained from all the parents. Before biopsy, a full clotting screen and a routine blood test were mandatory as they are especially important in evaluating tumors suspicious of being related to angiogenesis. A large needle was chosen whenever it was deemed safe to obtain tissues, and the largest we applied was 14-gauge, although in recent 2 years we used 16-gauge needles.
All patients received CT or MRI scanning before biopsy to aid in evaluating the risk for biopsy and to preliminarily determine the possible entry. In our center, ultrasonography was the only imaging modality used in all biopsies. We do not perform CT-guided biopsies.
An experienced ultrasound radiologist scanned the tumor again and used Color Doppler to assess its blood supply and approximate major vessels. The radiologist then marked an ideal insertion site on the skin. With the aid of the transducer, a biopsy needle was guided into the tumor. Under real-time ultrasound monitoring, the needle was placed in and fired multiple times, taking pieces of tumor tissues. In our practice, 14G- (Precisa, tru-cut semiautomatic device for histological biopsy, H.S.Hospital Service S.p.A) ,16G- and18G-needles (BARD MAX-CORE Disposable Core Biopsy Instrument, Bard Biopsy) were used.