Diagnostic accuracy and era for improvement for frameless stereotactic brain biopsy: a focus on non-diagnostic cases

Objective
To evaluate the diagnostic accuracy of frameless stereotactic brain biopsy, compare it with the current international standard, and review the era for improvement.

Background
The diagnostic accuracy of frameless stereotactic brain biopsy has been reported but there is limited literature focusing on the reasons for non-diagnostic cases.

Methods:
This is a retrospective analysis of consecutive, prospectively collected frameless stereotactic brain biopsy procedures from 2007 to 2020. We evaluated the diagnostic accuracy of the frameless stereotactic brain biopsy procedures using structurally-defined criteria. The biopsy result was classified as conclusive, inconclusive, or negative, based on the pathological, radiological, and clinical diagnosis concordance. For inconclusive or negative results, we further evaluated the preoperative planning and postoperative imaging to review the errors. A literature review for the diagnostic accuracy of frameless stereotactic biopsy was performed for the validity of our results. The objective of the study is to identify the causes of non-diagnostic results for future improvement.

Results:
There were 106 patients with 109 biopsy procedures performed from 2007 to 2020. The conclusive diagnosis was reached in 103 (94.5%) procedures. The inconclusive diagnosis was noted in four (3.7%) procedures and the negative biopsy was yielded in two (1.9%) procedures. Symptomatic hemorrhage was noted in one patient (0.9%). There was no mortality case (0.0%) in our series. The registration error and inaccurate targeting occurred in three trigonal lesions (2.8%), sampling of the non-representative part of the lesion occurred in two cases (1.8%), and one biopsy (0.9%) for lymphoma was negative due to the commencement of steroids. The literature review suggested that our diagnostic accuracy under the structurally-defined diagnosis criteria was comparable with the published literature, while the causes for non-diagnostic cases were uniquely performed and summarized.

Conclusion:
The stereotactic biopsy is a safe procedure with high diagnostic accuracy only if meticulous preoperative planning and careful intraoperative registration is performed. The common pitfalls precluding a conclusive diagnosis are registration errors and biopsies at non-representative sites.
