New needle for MR-guided aspiration cytology of the head and neck

Abstract

CT-guided aspiration cytology is valuable in the work-up of many deep head and neck lesions (1). Since MR imaging is rapidly replacing CT as the imaging study of choice for evaluating many areas of head and neck pathology, the ability to perform MR-guided aspiration cytology is becoming increasingly important. Attempts at MR-guided biopsy with conventional stainless steel CT needles result in images with unacceptably large image artifacts that obscure underlying anatomy. A needle for MR-guided biopsies of the liver first developed by Mueller et al. (2) has decreased the number of artifacts and is ideal for relatively thick MR sections of the liver. The decreased artifact of the liver needle necessary for thick-section liver studies is still too large to locate small lesions in areas of complex head and neck anatomy where higher resolution and thinner MR sections are necessary. Other investigators are studying nonferrous plastic sheaths with larger diameters for MR-guided percutaneous drainage procedures (3). Finally, new field-echo imaging techniques with narrow flip angles, which probably will be the most practical pulse sequences for MR-guided biopsy because of their speed, tend to accentuate magnetic susceptibility artifacts of all needle types because of the increased 12 sensitivity of gradient refocusing techniques (4). We describe a new MR needle with fewer artifacts on both spin-echo and gradient-echo sequences that is ideal for MR-guided aspiration cytology of head and neck lesions using high-resolution, thin-section MR imaging.