Echogenic Needle Research Articles

Ultrasound-guided stereotaxic biopsy using a new apparatus.

A skull-mounted apparatus is described for use with ultrasound probes 16 mm in diameter (5.0-MHz probes for near-field and 7.5-MHz probes for far-field lesions). The system permits ultrasound-guided stereotaxic biopsy of intracranial lesions through a burr hole in awake or anesthetized patients. This apparatus has been used in 19 patients for biopsy of central nervous system lesions 1.5 to cm in diameter and for drainage of abscess cavities and cysts. The time required to obtain a tissue sample after incision of the skin ranged from 25 to 40 minutes. The only complication was a delayed hemorrhage in a patient with acquired immunodeficiency syndrome. The advantages of this method over those guided by computerized tomography (CT) include less time required for the entire procedure, immediate confirmation of the biopsied target by imaging the echogenic needle track, assessment of cyst or abscess drainage, and detection of hemorrhage within minutes after biopsy. The apparatus may be especially useful in pediatric patients because it obviates the need for general anesthesia during transport to and from the CT scanner. This ultrasound-guided system does not require a craniotomy, craniectomy, or two separate burr holes.

Biochemical changes after spontaneous subarachnoid haemorrhage. I. The biochemical problem.

With the growth of ultrasound-guided regional anesthesia, so has the requirement for training tools to practice needle guidance skills and evaluate echogenic needles. Ethically, skills in ultrasound-guided needle placement should be gained in a phantom before performance of nerve blocks on patients in clinical practice. However, phantom technology is varied, and critical evaluation of the images is needed to understand their application to clinical use. Needle visibility depends on the echogenicity of the needle relative to the echogenicity of the tissue adjacent the needle. We demonstrate this point using images of echogenic and nonechogenic needles in 5 different phantoms at both shallow angles (20 degrees) and steep angles (45 degrees). The echogenicity of phantoms varies enormously, and this impacts on how needles are visualized. Water is anechoic, making all needles highly visible, but does not fix the needle to allow practice placement. Gelatin phantoms and Blue Phantoms provide tactile feedback but have very low background echogenicity, which greatly exaggerates needle visibility. This makes skill acquisition easier but can lead to false confidence in regard to clinical ability. Fresh-frozen cadavers retain much of the textural feel of live human tissue and are nearly as echogenic. Similar to clinical practice, this makes needles inserted at steep angles practically invisible, unless they are highly echogenic. This review describes the uses and pitfalls of phantoms that have been described or commercially produced.