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Biomedical subjects

B I Hall

Publications and source records attributed to B I Hall.

4 recordsLinked to original sources
PubMed1999

Cerebrovascular biomodelling: a technical note.

BACKGROUND: Recently computed tomographic angiography (CTA) and MR angiography (MRA) have been used to image cerebrovascular structures. Although CTA and MRA are accurate and sensitive imaging modalities, limitations have been identified in relation to image interpretation. Stereolithographic (SL) biomodelling is a new technology that allows three-dimensional (3D) CT and MR data to be used to accurately manufacture solid plastic replicas of anatomical structures. A prospective trial of SL biomodelling in cerebrovascular surgery has been performed to investigate the feasibility and clinical utility of this new display medium. METHODS: Fifteen patients with cerebral aneurysms and 1 patient with a cerebral arteriovenous malformation (AVM) were selected. 3D CT and/or MR angiograms were acquired and 19 solid anatomical biomodels manufactured using the rapid prototyping technology of stereolithography. The biomodels were used for patient education, diagnosis, operative planning and surgical navigation. RESULTS: The biomodels replicated the CTA and MRA source data. The accuracy of one biomodel was verified by comparison with a post mortem specimen, which corresponded exactly in the x and y planes but differed by 2 mm in the z plane. The ability to closely study an overview of complex cerebrovascular anatomy from any perspective on a solid biomodel was reported to enhance the surgeon's understanding, particularly when conventional images were equivocal. Cerebrovascular biomodels were found to be useful when positioning the patient's head for surgery, for selecting the best aneurysm clip and for the simulation of clipping. Patient informed consent was anecdotally improved. Disadvantages of the technology were the cost and manufacturing time. CONCLUSIONS: Cerebrovascular biomodelling may have utility in complex cases or when the standard imaging is felt to be equivocal.

Adult↗
PubMed1999

Biomodel-guided stereotaxy.

OBJECTIVES: To simplify the practice of stereotactic surgery by using an original method, apparatus, and solid anatomic replica for trajectory planning and to validate the method and apparatus in a laboratory and clinical trial. METHODS: The patient is marked with fiducials and scanned by using computed tomography or magnetic resonance imaging. The three-dimensional data are converted to a format acceptable to stereolithography. Stereolithography uses a laser to polymerize photosensitive resin into a solid plastic model (biomodel). Stereolithography can replicate blood vessels, soft tissue, tumor, and bone accurately (<0.8 mm). A stereotactic apparatus is referenced to fiducials replicated in the biomodel. The trajectory for the intervention is determined and saved. The apparatus is attached to the patient fiducials, and the intervention is replicated. RESULTS: Three types of apparatus (template, Brown-Roberts-Wells frame, and D'Urso frame) were tested on phantoms and patients requiring the excision/biopsy of tumors. The localization errors determined from the phantom studies were template, 0.82 mm; Brown-Roberts-Wells frame, 1.17 mm; and D'Urso frame, 0.89 mm. The surgeons reported that clinical use of the template and D'Urso frame was accurate and ergonomic. The Brown-Roberts-Wells frame was more difficult to use and somewhat inaccurate. CONCLUSION: Biomodel-guided stereotaxy has significant advantages. It is performed quickly; it is based on simple, intuitive methodology; it enhances visualization of anatomy and trajectory planning; it enhances patient understanding; it uses inexpensive equipment; it does not require rigid head fixation; and it has greater versatility than known techniques. Disadvantages are biomodel cost and a manufacturing time of 12 to 24 hours.

Biopsy↗
PubMed1998

A 10-year follow-up of the outcome of lumbar microdiscectomy.

STUDY DESIGN: A retrospective analysis of the outcome of lumbar microdiscectomy, with independent assessment of outcome. OBJECTIVES: To explore whether the initial positive outcome after microdiscectomy is maintained at long-term follow-up. SUMMARY OF BACKGROUND DATA: Previous reports on long-term outcome after lumbar disc surgery give conflicting messages about whether an initially positive surgical outcome is maintained throughout a 10-year period. This is partly due to differing methods and the failure to include initial outcome, thereby permitting assessment of possible deterioration in the quality of outcome. METHODS: This study presents the initial and long-term outcome after lumbar microdiscectomy, with an independent assessment of outcome. Eighty-eight consecutive patients undergoing lumbar microdiscectomy were identified. Assessment at 10 years after surgery was obtained in 79 (90%) of the cases. The initial outcome was assessed retrospectively by an independent observer at 6 months after surgery using the Macnab classification. The final outcome Macnab classification was completed by postal questionnaire by the patients themselves, who also completed a modified Roland-Morris disability questionnaire. RESULTS: A successful outcome at 6 months was achieved in 91% of the cases. At 10-year follow-up, this result declined slightly to an 83% success rate. However, there was no statistically significant difference between these outcome results. The long-term Macnab classification results correlated well with disability, as measured by the Roland-Morris score. Patient satisfaction with the results of microdiscectomy 10 years later was high. CONCLUSIONS: Lumbar microdiscectomy achieves a high level of initial success, and this positive outcome is maintained at a 10-year follow-up.

Adolescent↗