CardioVascular and Interventional Radiology | 2021
Image-Guided Percutaneous Calvarial Biopsy with Low-Dose CT-Fluoroscopy: Technique, Safety, and Utility in 12 Patients
Abstract
To the Editor, We would like to take this opportunity to share our institutions’ retrospective review of cases referred for percutaneous calvarial biopsy performed with lowdose CT-fluoroscopy to delineate its feasibility and clinical utility despite reductions in conventional acquisition dose parameters. Calvarial lesions can be benign or malignant, and distinguishing between these entities may be difficult on preoperative imaging as many calvarial lesions are nondescript on imaging. In the absence of prior studies, tissue sampling may be the best option for definitive classification of a lesion. A single-head CT’s absorbed and equivalent dose is roughly 50 mGy [1]. While this translates to an effective dose of 1–2 mSv, cumulative dose to the lens has been recorded as high as 8 mSv [1, 2]. The United States’ National Academies BEIR VII report published in 2005 extrapolated biological effects of ionizing radiation from exposure to B 100 mSv [3]. In a lifetime, approximately 42 in 100 patients (42%) will be diagnosed with cancer from causes unrelated to radiation. Approximately 1 in 100 patients (1%) is expected to develop solid cancer or leukemia from a single exposure of 100 mSv. Lower doses produce proportionally lower risks, noting that it is predicted that 1 individual in 1000 could develop cancer from a single exposure to 10 mSv [3]. The accuracy of linearly extrapolating biological effects from exposure of B 100 mSv remains controversial. Nevertheless, as repetitive scanning during CT-guided calvarial biopsy may result in significant dose accumulations over a procedural course, employment of low-dose strategies is ideal. All biopsies were performed using a CT-fluoroscopy compatible unit (Siemens SOMATOM Definition DS 128). The kilovoltage peak (kVp) was reduced from 120 to a range of 80–100. The milliampere-seconds (mAS) was reduced from 200 to a range of 8–15. Scout images were acquired, from which the appropriate trajectory was planned. All patients were prepped and draped in a sterile fashion. Local anesthetic was administered via 25-gauge needle for superficial and deep local anesthesia. Utilizing CT-fluoroscopic guidance, an 18 or 20-gauge needle was advanced into the superficial soft tissue component of the lesion. For sclerotic or mixed bony lesions without a soft tissue component, a biopsy needle with a diamond-tipped drill was used to enter the superficial edge/outer table of the skull. The inner stylet of the drill needle was removed, and the hollow cannula was advanced into the bone to obtain a core sample. In some cases, fine needle aspirations (FNA) were performed by & Sri Hari Sundararajan [email protected]; [email protected]