COMPUTED TOMOGRAPHY-GUIDED PERCUTANEOUS BIOPSY - CRITERIA FOR ACCURATE NEEDLE TIP IDENTIFICATION

Precise localization of the needle tip during CT-guided percutaneous b iopsy is considered to be a key element of a successful procedure. To ensure accuracy, the true needle tip must be differentiated from a fal se or simulated tip which appears when the CT slice encompasses only t he shaft of an angled needle. By obtaining images of an aspiration bio psy needle inserted vertically into a phantom and then incrementally t ilting the gantry, the authors werw able to compare the characteristic features of the true tip to the simulated tip. The true tip was abrup t and distinct and had an adjacent flame-like low density artifact. Th e simulated tip was indistinct and tapered, yet still produced the adj acent artifact. We concluded that the shape and distinctness of the en d portion of the needle itself, rather than the attendant artifact, we re the most reliable criteria for accurate needle tip identification.