Biomedical subjects

S Hariri

Publications and source records attributed to S Hariri.

6 recordsLinked to original sources

PubMed2001

Clinical fluoroscopic fiducial-based registration of the vertebral body in spinal neuronavigation.

We present a system involving a computer-instrumented fluoroscope for the purpose of 3D navigation and guidance using pre-operative diagnostic scans as a reference. The goal of the project is to devise a computer-assisted tool that will improve the accuracy, reduce risk, minimize the invasiveness, and shorten the time it takes to perform a variety of neurosurgical and orthopedic procedures of the spine. For this purpose we propose an apparatus that will track surgical tools and localize them with respect to the patient's 3D anatomy and pre-operative 3D diagnostic scans using intraoperative fluoroscopy for in situ registration and embedded fiducials. Preliminary studies have found a fiducial registration error (FRE) of 1.41 mm and a Target Localization Error (TLE) of 0.48 mm. The resulting system leverages equipment already commonly available in the operating room (OR), providing an important new functionality that is free of many current limitations, while keeping costs contained.

Artificial Intelligence↗

PubMed2001

A comparative statistical analysis of neuronavigation systems in a clinical setting.

The use of neuronavigation (NN) in neurosurgery has become ubiquitous. A growing number of neurosurgeons are utilizing NN for a wide variety of purposes, including optimizing the surgical approach (macrosurgery) and locating small areas of interest (microsurgery). The goal of our team is to apply rapid advances in hardware and software technology to the field of NN, challenging and ultimately updating current NN assumptions. To identify possible areas in which new technology may improve the surgical applications of NN, we have assessed the accuracy of neuronavigational measurements in the Radionics and BrainLab systems. Using a phantom skull, we measured how accurate the visualization of a navigational probe's tip was in these systems, taking a total of 2180 measurements. We found that, despite current NN tenets, error is maximal at the six marker count and minimal in the spreaded marker setting; that is, placing less markers around the area of interest maximizes accuracy and active tracking does not necessarily increase accuracy. Comparing the two systems, we also found that accuracy of NN machines differs both overall and in different axes. As researchers continue to apply technological advances to the NN field, an increasing number of currently held tenets will be revised, making NN an even more useful tool in neurosurgery.

Factor Analysis, Statistical↗

PubMed2001

Quantification of the gravity-dependent change in the C-arm image center for image compensation in fluoroscopic spinal neuronavigation.

In the quest to develop a viable, frameless spinal navigation system, many researchers are utilizing the C-arm fluoroscope. However, there is a significant problem with the C-arm that must be quantified: the gravity-dependent sag effect resulting from the geometry of the C-arm and aggravated by the inequity of weight at each end of the C-arm. This study quantified the C-arm sag effect, giving researchers the protocol and data needed to develop a program that accounts for this distortion. The development of spinal navigation algorithms that account for the C-arm sag effect should produce a more accurate spinal navigation system.

Artifacts↗

PubMed2001

Neuronavigational epilepsy focus mapping.

The localization of a seizure focus for resective surgery often requires invasive monitoring for precise localization of the target as well as structures to avoid. We report on the use of intra-operative surgical navigation to precisely localize and co-register subdural electrodes to regions of know radiographic pathology. Additionally, the navigation system was used to develop intra-operative electrode maps. These maps were subsequently used in the sub-acute recording phase to assign electrographic pathology and function (e.g. speech) to a specific cortical surface anatomy. This permitted for more precise planning of surgery and better assessment of potential risk, based on functional as well as anatomical criterion.

Artificial Intelligence↗

PubMedDate not supplied

Aesthetic results of treatment of large alopecia with total scalp expansion.

In the last 7 years, 18 patients with large alopecia (approximately one-third of hair-bearing scalp) were treated with 31 tissue expansion procedures. In the previous 44 patients, with various degrees of alopecia treated with conventional tissue expansion technique, the major complication rates were as high as reported in the relevant literature. The clinical experience gained with these cases led us to make some modifications in the surgical technique. We applied some simple surgical maneuvers and Z-plasties to the last 18 cases with large alopecia. The major complication rate of 3.2% observed in this study is comparable to the lower complication rates of 6-12% reported in the literature for different degrees of alopecia. We believe that these simple modifications and meticulous approach improve the results of conventional treatment of alopecia with tissue expansion and flap. In this paper, details of the insertion technique and reconstructive procedures and their relevance to the success rate of the aesthetic treatment of the large alopecia are discussed.

Adolescent↗

PubMedDate not supplied

Preoperative sagittal CT evaluation of the frontal recess.

Endoscopic surgical approaches for chronic frontal sinusitis require the reestablishment of adequate frontal sinus ventilation and drainage for relief of symptoms. After the resection of anterior ethmoid mucosal disease and cellular structure, the anterior to posterior depth of the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla (frontal sinus ostium) often represents a critical margin for functional success. However, little information concerning this dimension is available. Depending on intraoperative surgical judgment of this distance, extended endoscopic surgical procedures involving additional bone resection may be indicated. These approaches may be hazardous due to the proximity of the cranial cavity and orbit. In addition, secondary stenosis can result from the subsequent inflammatory response. Improved CT imaging, high resolution sagittal reformatting, and computer workstations provide the ability to obtain direct preoperative measurements of the frontal recess. We used a paramedian sagittal section and recorded the maximal anterior to posterior depth from the nasofrontal beak to the base of skull at the insertion of the ethmoidal bulla in 20 patients, 31 sides, undergoing primary endoscopic frontoethmoidectomy. In addition, we found a positive correlation between this distance and agger nasi air cell size measured in the same 31 sides.

Chronic Disease↗