Franklin Earnest

Magnetic resonance imaging in a routine clinical setting.

The results of magnetic resonance imaging (MRI) examinations in the first 1,000 consecutive patients who were studied by this technique at our institution were reviewed to determine the disease states encountered, the sensitivity and accuracy of results, and the value of the examination as compared with computed tomography and other imaging procedures. The MRI device was a 0.15-tesla resistive magnet that used a variety of saturation recovery, spin echo, and inversion recovery pulse sequences to produce images. MRI was found equal to or superior to other imaging techniques in most cases. Exceptions included organs or body regions that are prone to excessive respiratory or vascular motion, lesions that necessitate exquisite spatial resolution for diagnosis, and lesions in which angulation of the viewing plane is necessary for optimal depiction. Fresh blood and calcification within a lesion were also difficult to detect with use of MRI.

Simultanagnosia as the Initial Sign of Degenerative Dementia

In a study of 10 patients with degenerative brain disease that manifested as simultanagnosia, our aims were (1) to elucidate their clinical, neuropsychologic, and radiologic findings to determine whether these patients might represent a group distinguishable from those with typical Alzheimers disease and (2) to help clinicians recognize this entity. All patients were initially examined by ophthalmologists because of visual difficulties, and the simultanagnosia remained undiagnosed until nonophthalmologic complaints developed. Optic ataxia developed in six patients, and all patients had mildly impaired eye movements. All 10 patients could identify colors appropriately. Nine patients had language deficits (anomia, decreased auditory comprehension, alexia, and agraphia) but were fluent and had relative preservation of sentence repetition, and four performed in the normal range on a test of associative fluency. Two patients scored in the normal range on memory tests, all had preserved insight, and nine had no family history of degenerative dementia. The mean age at onset of the disorder was 60 years (range, 50 to 69). Neuroimaging disclosed prominent bilateral occipitoparietal atrophy in nine patients and generalized atrophy in one. With this unusual but consistent clinical, neuropsychologic, and anatomic profile, these patients are clinically distinguishable from those with typical Alzheimers disease, but until a specific cause has been found, we cannot be certain that they constitute a specific biologic entity. Clinicians should consider this diagnosis in relatively young patients who have slowly progressive nonocular visual complaints.

Surgical Options for Patients With Deep-Seated Brain Tumors: Computer-Assisted Stereotactic Biopsy

The histologic nature of deep-seated intracranial lesions can be determined by using a computer-assisted stereotactic biopsy technique. The procedures are performed with use of local anesthesia. A data base consisting of stereotactic computed tomographic scans and stereotactic cerebral angiography is acquired. Target coordinates and trajectory approach angles are calculated by using a computer system in the operating room. Since July 1984, 36 patients with a variety of pathologic lesions in various intracranial sites have undergone this procedure at our institution. Of the 36 patients thought to have neoplastic lesions preoperatively, 6 were found to have nonneoplastic lesions, information that was of importance in the therapeutic management of these patients. Of the 30 patients with tumors, 24 had astrocytomas of various grades, 3 had metastatic lesions, and an additional 3 had lymphomas. Computer-assisted stereotactic biopsy with arteriographic control is an accurate and relatively safe method of determining the histologic nature of any suspicious intracranial lesion.

Therapeutic Embolization Angiography for Extra-Axial Lesions in the Head

Percutaneous transcatheter arterial embolization has played an increasingly important role in the management of vascular lesions in the head. Embolization can promote thrombosis within vascular tumors and malformations, reduce bleeding and decrease the need for transfusion intraoperatively, and facilitate surgical approaches to otherwise unresectable lesions. It is important for the clinician to be aware of this interventional technique because many of the patients who are considered for embolization are triaged through several different clinical areas, and much can be gained from the collaboration of the clinician, the surgeon, and the angiographer. We performed 31 therapeutic particulate embolization procedures for extra-axial head lesions in 23 patients by using flow-directed techniques. Of these procedures, 11 resulted in vascular occlusion and 15 resulted in 80 to 95% obstruction, as demonstrated by angiography. In 14 patients, embolization was performed preoperatively both to decrease blood loss and to occlude inaccessible or unresectable portions of a lesion. In nine patients, embolization was the sole means of treatment for occluding an abnormal vascular shunt. Two patients (9%) experienced a minor transient neurologic change after the procedure.

Present and future developments of stereotactic technology.

Incorporation of a surgical computer system into stereotactic methodology provides the facility for efficient utilization of the multiple data bases at the disposal of the modern stereotactician. Computed tomography, magnetic resonance imaging, and digital fluoroscopy data gathered in stereotactic conditions are digitized into a stereotactic surgical matrix for surgical planning and interactive surgical procedures. The advantages of this system are illustrated in stereotactic biopsy, interstitial irradiation, and laser resections of intracranial tumors.

The Computer as a Stereotactic Surgical Instrument

We have developed methodology and stereotactic software for an operating room computer and imaging system. Patients undergo preoperative CT, MR and DSA imaging with their heads fixed in a stereotactic headholder. Localization systems attach to the headholder during the studies to create reference marks for computer transformation of points and volumes into three-dimensional stereotactic space. At the operating room computer console, the surgeon selects target points, avascular trajectories and tumour boundaries for volume reconstruction. Surgical approaches are simulated and target coordinates calculated. During surgery, the computer interactively monitors the position of stereotactically directed surgical instruments in relationship to the resident database along any viewing angle and conveniently superimposes the multiple data sources. We have found this system useful to provide rapid data acquisition and retrieval, accurate target point calculations, lesion volume reconstructions, and a convenient ability to reformat data from multiple sources in a manner useful to the surgeon and beneficial to the patient.