Biomedical subjects
Publications and source records attributed to A N Hasso.
The author believes that multiplanar CT imaging serves to distinguish the articular disc from other tissues of similar density and is necessary for a detailed temporomandibular joint survey.
Because of the controversy over applying adult clinical and laboratory criteria to children suspected of brain death, xenon computed tomographic cerebral blood flow (XeCTCBF) and near simultaneous scintigraphy were studied in 10 children. Six met the clinical criteria, one of whom had three indeterminate scintigrams with only central flow on XeCTCBF. Another had considerable flow with scintigraphy and XeCTCBF. One with clinical and autopsy brainstem death but preserved cortical function also had flow on both. This preliminary study establishes that brain scintigraphy is occasionally hypersensitive to insufficient cerebral flow and promises more accurate early assessment with XeCTCBF. The expectation is that XeCTCBF can refine the criteria for the earlier establishment of brain death.
We attempted to establish a computed tomographic value representing the normal volume ratio of gray matter to white matter (G/W) in children in order to have a baseline for studying various developmental disorders such as white matter hypoplasia. The records of 150 children 16 years of age or younger who had normal cranial computed tomography were reviewed. From these a group of 119 were excluded for various reasons. The remaining 31 were presumed to have normal brains. Using the region of interest function for tracing gray and white matter boundaries, superior and ventral to the foramen of Munro area, measurements were determined for consecutive adjacent frontal slices. Volumes were then calculated for both gray and white matter. A volume ratio of 2.010 (sigma = 0.349), G/W, was then derived from each of 31 children. The clinical value of this ratio will be determined by future investigation.
We reviewed 103 normal gas CT cisternograms to delineate the appearance of normal neurovascular structures in the cerebellopontine angle (CPA) and internal auditory canal (IAC). Cranial nerves VII and VIII were identified in the CPA in 97% of cases, either separately (53%) or as a bundle (44%). Intracanalicular branches of the VIIIth cranial nerve were identified in 20% of cases, and cranial nerve V was visualized in the CPA in 14%. The characteristic vascular loop, usually the anterior inferior cerebellar artery, was visible in 35% of cases, and, in 22% of visualized cases, was in an intracanalicular location. The internal auditory artery was questionably visualized in one case. In 10% of cases, greater than 66% of the IAC was occupied by the neurovascular bundle. Familiarity with the normal anatomy and variants seen on gas CT cisternograms is necessary to prevent false-positive interpretations.
Operative treatment of critical stenoses of the internal carotid artery secondary to fibromuscular dysplasia has been performed for nearly 2 decades using graduated metal dilators. While percutaneous transluminal balloon angioplasty of the internal carotid via the femoral artery has several advantages over the operative metal dilator method, cerebral embolization is a matter for concern. The authors have performed operative transluminal balloon angioplasty in such cases, permitting backbleeding with removal of any thrombi or debris. This technique combines the advantages of dilatation by a Grüntzig balloon with post-dilatation carotid backbleeding. Five patients have been successfully treated thus far using this technique.
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A prospective study to determine the accuracy of computed tomography (CT) for the diagnosis of dislocation of the temporomandibular joint (TMJ) meniscus was made by performing both CT and contrast arthrography on 18 joints suspected of meniscus dislocation. Arthrography rather than surgery was chosen as the quality standard for comparing CT findings, as not all patients undergoing the studies underwent surgery. The CT protocol included scanning with both closed- and open-mouth series, 1.5-mm-thick slices, soft-tissue and bone-detail settings, and coronal and sagittal reformations. Arthrography was done with linear tomography, after both lower and upper compartmental injections under fluoroscopic control. The results of each test were reported independently by the radiologist who obtained either all of the arthrograms or all of the CT scans. For dislocation of the meniscus, there was excellent agreement between the two methods. Nine menisci were dislocated according to both arthrography and CT. One meniscus was thought to be dislocated by CT, but this was not confirmed with arthrography. CT seems to be nearly as accurate as arthrography for showing meniscus dislocation, is performed with lower x-ray exposure, and is noninvasive. Arthrography discloses more detailed information about the joint meniscus, such as perforation and maceration, and should continue to be used when this kind of information is clinically important.
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Eight volunteer post partum female patients were examined with high resolution computed tomography during the week immediately after delivery. All patients received high dose (40-70 gm) intravenous iodine contrast administration. The scans were examined for pituitary gland height, shape and homogeneity. All of the patients had enlarged glands by the traditional standards (i.e. gland height of 8 mm or greater). The diaphragma sellae in every case bulged upward with a convex domed appearance. The glands were generally inhomogeneous. One gland had a 4 mm focal well defined area of decreased attenuation. Two patients who were studied again months later had glands which had returned to "normal" size. The enlarged, upwardly convex pituitary gland appears to be typical and normal for the recently post partum period.
High-resolution computed tomography of the temporomandibular joint (TMJ) was performed in 43 patients. Exquisite detail of the face, skull base, and TMJs was obtained with CT using soft tissue and bone algorithms, narrow collimation, and multiplanar images. In 10 patients clinically suspected of joint derangement, CT results were in close agreement with surgical findings and arthrography in 13/15 joints. CT showed indirect signs of disc dislocation, and the dislocated disc itself in 81% of affected joints. In two patients, arthrography with CT proved to be more helpful than conventional arthrography alone. CT without intra-articular contrast material provided information not appreciated on conventional radiographs in 28 patients (65%) and was particularly helpful in evaluating patients with disc pathosis and trauma. Early experience with CT of the TMJ shows that it is an excellent method of evaluation at acceptable radiation exposure levels that adds essential information not seen on standard radiographs.
High-resolution computed tomography (CT) was used to examine 12 patients with temporal bone trauma. The CT findings were correlated with the clinical signs and symptoms (hearing loss, facial nerve dysfunction) and with the operative findings in the 5 patients who underwent surgery. CT was able to demonstrate ossicular chain disruption or fractures causing the clinical findings in the majority of cases. The CT findings affected patient care by alerting the otologist to the abnormalities likely to be encountered during surgery.
Computed tomography of the spine using intrathecal metrizamide was performed on six patients with spinal trauma. Dural tears with contrast material escaping outside the subarachnoid space were documented in five cases. In one case, the thecal laceration had healed and the contrast material was confined in a post-traumatic meningocele. The characteristics of dural tears are demonstrable by metrizamide computed tomography, either in conjunction with myelography or as a separate procedure. Neurological deficits following spinal trauma may be aggravated by dural tears with entrapment of the spinal nerve roots.
High-resolution CT is an ideal technique for evaluating tumors of the paranasal sinuses. It offers excellent detail of both bony and soft tissue structures. CT can demonstrate a tumor in its early stage and can reveal the exact extent of a lesion for optimal staging prior to treatment. It is important in follow-up and can be used to document residual or recurrent tumor with a high degree of accuracy.
The neuroradiological findings in four cases of primitive neuroectodermal tumor of the cerebrum are described. These highly malignant neoplasms of childhood present as large, enhancing cerebral masses with extensive neovascularity. Cerebrospinal fluid seeding is common and distant extraneural metastases may occur.
Ten patients with malignant primary neoplasms of the ear and temporal bone were examined with high-resolution computed tomography (CT) and the results correlated with the operative findings. CT was found to be highly accurate in establishing the presence and extent of tumor and is recommended as the procedure of choice for preoperative treatment planning.
Sixteen patients with intracranial air under tension and severe neurological symptoms following trauma and neurosurgical procedures were reviewed. Computed tomography (CT) was performed in cadavers following selective air injections into the epidural, subdural, and subarachnoid spaces. The characteristic CT appearance of air in the various intracranial compartments is illustrated. The typical "peaking" of the frontal lobes in subdural tension pneumocephalus is explained by bridging veins entering the superior sagittal sinus. Stretching and rupturing of these veins may be implicated as a cause for a concomitant subdural hematoma. The various mechanisms causing tension pneumocephalus and its appropriate therapy are discussed.
A prospective study of 582 pediatric cranial computed tomographic (CT) examinations was made in order to determine the efficacy and safety of two sedation regimens and general anesthesia. Two hundred seventy-nine outpatients were randomly given oral chloral hydrate (80 mg/kg) or an intramuscular preparation composed of atropine, meperidine, promethazine, and secobarbital (AMPS). Three hundred three inpatients were randomly administered chloral hydrate, the AMPS, or endotracheal anesthesia. Intravenous supplementation of the sedation was limited by the protocol to a maximum secobarbital dosage of 2 mg/kg. An additional retrospective analysis was made of 316 scan attempts obtained outside the study during the same period. A failed CT examination was defined as one that could not be completed or one that showed motion artifacts on two or more scan pairs after two scan pair repeats. The failure rate was 15% for the chloral hydrate group and 12% for the AMPS group. No motion artifacts were present on 94% of the completed studies. There was no mortality, but major and minor complications occurred in 3.5% of the randomized group. It was concluded that each of the methods had proved acceptably safe and effective and that measures can be taken to decrease complications and sedation failures further.