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Biomedical subjects

A Valavanis

Publications and source records attributed to A Valavanis.

At least 127 records · Page 7Linked to original sources
PubMed1982

CT differentiation between recurrent disc herniation and postoperative scar formation: the value of contrast enhancement.

A study for the evaluation of the reliability of contrast enhanced CT in the differentiation between recurrent disc herniation and hypertrophic scar formation was undertaken. From the retrospective analysis of 36 surgically verified cases it became evident that hypertrophic scar tissue shows definite contrast enhancement, whereas recurrent disc herniation remains unenhanced. A possible explanation for this phenomenon is given. It is concluded that contrast enhancement should be performed in cases being studied by CT for recurrent symptoms after operation for disc herniation.

Cicatrix↗
PubMed1982

The current state of the radiological diagnosis of acoustic neuroma.

Thin, overlapping section, contrast-enhanced, axial and coronal CT, with additional high-resolution (HR) treatment of the sections through the internal auditory canal, was performed on 31 patients clinically suspected of acoustic neuroma. With this technique 13 acoustic neuromas protruding more than 10 mm and eight acoustic neuromas protruding between 2 and 10 mm outside the internal auditory canal were unequivocally diagnosed. O2CT cisternography was performed on ten patients. An intracanalicular neuroma was diagnosed in three cases with this technique, also a small extracanalicular neuroma in one case, and an acoustic neuroma was definitely excluded in six cases. It is concluded that O2CT cisternograhy is the diagnostic procedure of choice for the detection of purely intracanalicular neuromas and the definite exclusion of acoustic neuroma. HR CT proved superior to polytomography for the evaluation of the internal auditory canal and should be performed in every case suspected of acoustic neuroma. A protocol for the radiological investigation of patients suspected of acoustic neuroma is given.

Contrast Media↗
PubMed1982

[High resolution computerized tomography for the determination of fractures of the base of the skull, particularly the petrous bone].

Using high resolution CT, the high spatial resolution is comparable to conventional pluridirectional tomography. The small pixel size allows visualization of minute fractures of the skull base or the petrous bone. High resolution CT clearly demonstrated 32 fractures of the skull base, 14 of them passing through the petrous pyramids. The CT examination with the high resolution mode can be performed at the same time as the regular CT examination of the brain. This procedure is less time consuming and safer for the traumatized patient than the separate examination of the brain and the skull base with regular CT and conventional tomography respectively. As with conventional radiologic methods, the fractures are best demonstrated if they are oriented at right angles to the scanning plane. Fractures parallel to the scanning plane be missed. Therefore, additional direct coronal scans may be necessary for the accurate demonstration of fractures of the skull base.

Adult↗
PubMed1982

Cerebrovascular Doppler-ultrasound examination in children: principle, indication and findings.

The cerebrovascular Doppler examination (cv-Doppler) is a reliable noninvasive method for the diagnosis of obstructions in the extracranial cerebral arteries, and of major arteriovenous shunts in adult patients. The method was applied in 38 children aged 4 months to 17 years. 25 patients with symptoms of cerebrovascular disease underwent cerebral angiography. Six patients had extracranial arterial obstruction, all correctly diagnosed by Doppler. Six children had obstruction of the middle cerebral artery, four were indirectly predicted by Doppler. Four of these twelve patients had extra-intracranial bypass surgery. The patency of the anastomosis could be documented in all cases by Doppler. Ten children had arterio-venous shunts. Of these, 7 patients with an av-angioma and one patient with a carotid-cavernous-sinus fistula were diagnosed correctly by Doppler, as was the cessation of pathologically increased blood flow in the feeding and draining vessels in the 5 patients who had surgical intervention. cv-Doppler results were normal in 3 cases with normal angiography. These results demonstrate that cv-Doppler examination can be useful also in children for the diagnosis of cerebrovascular disease and noninvasive documentation of the hemodynamic effect of neurovascular surgery.

Adolescent↗
PubMed1982

Persistent cervical intersegmental artery as a cause of recurrence of a traumatic carotid-cavernous fistula: case report, with emphasis on Doppler ultrasound diagnosis.

In a 16-year-old boy, minor symptoms of an arteriovenous shunt into the cavernous sinus recurred 3 months after the performance of a trapping operation of the internal carotid artery on the side of a traumatic carotid-cavernous sinus fistula. An arterial and venous cerebrovascular Doppler examination demonstrated increased blood flow in the periorbital veins of both sides, with a pathological flow direction, i.e., from intra- to extracranial. Furthermore, an internal-like artery was found at the level of the carotid bifurcation on the side of the trapped internal carotid artery, and increased blood flow was registered in the homolateral vertebral artery. Angiography confirmed occlusion of the internal carotid artery 0.5 cm distal to the carotid bifurcation, but showed blood flow from the homolateral vertebral artery through a persistent 3rd cervical intersegmental artery into the trapped portion of the internal carotid artery. The latter fed blood into the cavernous sinus through the still-existing arteriovenous fistula. Insufficient involution of the 3rd cervical intersegmental artery was assumed. Obviously, this collateral artery dilated in the presence of a major blood pressure gradient between the vertebral artery and the trapped segment of the internal carotid artery. Thus, a persistent cervical intersegmental artery can be a cause for a recurrent carotid-cavernous sinus fistula.

Adolescent↗
PubMed1981

CT of meningiomas on the Posterior surface of the petrous bone.

A detailed analysis of the CT findings in 16 surgically verified cases of meningioma of the posterior surface of the petrous bone is presented. The results indicate that a correct preoperative diagnosis is possible in almost every case. Frequently occurring specific CT criteria for meningioma of the posterior surface of the petrous bone include: hyperdense, homogeneously enhancing, extra-axial, CPA mass; inverse relationship between precontrast attenuation value and degree of contrast enhancement of the tumor; oval shape; obtuse angle between lateral tumor border and posterior surface of petrous bone, and evidence of transcisternal supratentorial tumor extension. Infrequently occurring specific CT criteria include: tumor calcification; hyperostosis or exostosis of the posterior surface of the petrous bone; a comma-shaped tumor configuration in cases with transcisternal tumor extension and evidence of transtentorial tumor extension. Oxygen CT cisternography is the most sensitive and reliable technique for detecting small tumors. The CT differential diagnosis of meningioma of the posterior surface of the petrous bone is discussed.

Bone Neoplasms↗
PubMed1981

The diagnosis of solitary primary reticulum cell sarcoma of the posterior fossa with computed tomography.

The CT findings in two surgically and histologically verified cases of primary reticulum cell sarcoma of the cerebellar hemisphere with secondary involvement of the cerebellopontine angle are presented. It is suggested that a correct diagnosis is possible by CT if the following criteria are present: 1. slightly increased attenuation of the mass on the precontrast scan; 2. mottled appearance of the definitely enhancing mass; 3. ill-defined borders on both the pre- and postcontrast scans; 4. degree of mass effect less than that expected from the size of the lesion; 5. involvement of the cerebellopontine angle without signs indicating an extra-axial origin of the tumor. These criteria reflect the gross and microscopic neuropathological features of the tumor.

Aged↗
PubMed1980

Computed tomography in neuronal ceroid lipofuscinosis.

The computed tomography (CT) findings in a verified case of neuronal ceroid lipofuscinosis (NCL) are presented. CT revealed diffuse and severe cerebral atrophy, reflected by generalized subarachnoid space enlargement and symmetric ventricular dilatation. There was no evidence of abnormalities of the white matter. The CT features in our case of NCL correspond perfectly with the neuropathologic changes of the disease mentioned in the literature. Furthermore, CT is of considerable help in differentiating between those inherited metabolic brain diseases characterized primarily by white matter involvement and those presenting predominantly with changes of grey matter.

Ceroid↗
PubMed1980

Computed tomography in cerebral aneurysms with special emphasis on giant intracranial aneurysms.

The computed tomography (CT) findings of 105 patients with a total of 139 intracranial aneurysms are analyzed. The rate of detection of subarachnoid and intracerebral hemorrhage in relation to time since bleeding episode agreed well with previously reported results. Direct visualization of small intracranial aneurysms using 5 mm sections in the postcontrast scan was possible in 58% of the cases. Ten cases of giant intracranial aneurysms (GIA) more than 25 mm in diameter are analyzed in depth. Diagnostic criteria for differentiation of GIA from tumors are discussed. Ring shaped postcontrast enhancement of the outer margin of the aneurysm or curvilinear interrupted calcifications were found in totally or partially thrombosed GIA; central or peripheral homogeneous enhancement of the aneurysm's lumen (target sign) was typical of partially thrombosed GIA; and nonthrombosed GIA usually presented as homogeneously enhancing lesions. Differential diagnostic criteria are discussed.

Adolescent↗
PubMed1980

Neuroma of the cavernous sinus.

A case of a surgically verified parasellar neuroma is presented. Despite clinical and radiological evidence for the origin of the tumor to be the trochlear or oculomotor nerves, an operation revealed a neuroma originating from the cavernous sinus, but exact identification of the origin of the tumor was not possible. The radiologic findings including polytomography, angiography and computed tomography are presented. The clinical and radiological differentiation between this case and typical neuromas of the gasserian ganglion are discussed.

Adult↗
PubMed1979

Cerebral toxoplasmosis in the adult.

We report a case of cerebral toxoplasmosis in an adult patient. The diagnosis was established by demonstration of Toxoplasma gondii in the cerebrospinal fluid, and the patient was evaluated by computed tomography.

Adult↗
PubMed1979

Cerebral granulomatous angiitis simulating brain tumor.

A case of surgically verified cerebral granulomatous angiitis, which was mistaken for a brain tumor on computed tomography, is reported. The focal, enhancing lesion was due to multiple confluent infarction caused by the angiitic process.

Adult↗
PubMed1979

Subdural interhemispheric empyema in a 7-year-old boy.

Subdural interhemispheric empyema was diagnosed by angiography and computerized tomography (CT) in a 7-year-old boy suffering from acute left hemiparesis. After neurosurgical intervention his condition improved. Peptostreptococcus intermedius was cultured from the empyema. One year after hospitalisation the boy is in good condition. The importance of the CT-scanning for diagnosis and management of brain abscess or empyema is stressed.

Brain Abscess↗