Clinical validation of true frameless stereotactic biopsy: Analysis of thefirst 125 consecutive cases

OBJECTIVE: A lockable guide device, adjustable for positioning, was used to obtain samples for tissue analysis during brain biopsy procedures performe d using an interactive image guidance system. Clinical validation of this t echnique, which was developed for true frameless stereotactic biopsies, and analyses of the histological yield, complication rate, and patient demogra phic characteristics for a large series of frameless stereotactic biopsies were the purposes of this study. METHODS: Demographic, radiological, surgical, and clinical data were prospe ctively collected for a series of 125 frameless stereotactic biopsies perfo rmed using the technique described in detail previously. RESULTS: Eighty-six procedures were magnetic resonance imaging-directed and 39 were computed tomography-directed. The mean diameter of the biopsied le sions was 36 mm, and the mean distance from the skin was 35.8 mm. Sixteen p ercent of the patients harbored multiple lesions, and 5.6% of the biopsied lesions were infratentorial. The mean operative time (including the entire anesthetic time) was 1.5 hours. The smear examination findings were corrobo rated by conclusive histological results in 96% of the cases, and definitiv e positive diagnoses were obtained in 122 cases (97.6%). Ten patients exper ienced surgical complications, but the sustained morbidity rate was 2.4% (i ncluding the death of a patient who was in critical clinical condition preo peratively and who died 2 mo later as a result of a chest infection; mortal ity rate, 0.8%). CONCLUSION: This true frameless stereotactic biopsy technique was associate d with low morbidity and mortality rates and an excellent diagnostic yield, with overall results at least as good as those observed for frame-based st ereotaxy. The excellent accuracy results demonstrated previously and statis tically significant reductions in operative time, as well as improved image presentation, target selection, and simplicity, support the use of this fr ameless stereotactic technique in preference to frame-based biopsy techniqu es.