Computerized x-ray scanning of the brain

Prognosis of pituitary adenomas in the early 1970s and today-Is there a benefit of modern surgical techniques and treatment modalities?

OBJECTIVE

Neurosurgical techniques for the treatment of sellar pathologies have been evolving continuously over the last decades. Additionally to the innovation of approaches and surgical techniques, this progress yielded to the application of modern intraoperative surgical tools as well as peri- and intraoperative imaging. Until now, no long-term analysis of the impact of new therapy concepts on the patient's outcome exists. Aim of this study was to analyse the impact of new operative approaches on perioperative mortality and morbidity as well as the long-term outcome after pituitary surgery.

PATIENTS AND METHODS

Three groups of patients were compared in this retrospective analysis of surgically treated pituitary adenomas between the years of 1963 and 2014. Group A contains 93 patients, treated between 1963-1980 with a mean follow-up of 12.1 years (±14.3years), group B comprises 89 patients treated between 1990 and 2000 with a mean follow-up of 10.1 years (±8.1years) and group C consists of 95 patients treated between 2011-2014 with a mean follow-up of 3.4 years (±1.9years).

RESULTS

The surgical treatment was performed significantly earlier today on smaller tumors with less preoperative complaints (p<0.01). Panhypopituitarism was detected only in 9.5% of the cases in group C compared to 50.8% in group A (p<0.01). Also, the incidence of revision surgery (5.6 vs. 2% vs 0%), postoperative hemorrhage (10.8% vs. 3.4% vs. 1%) and diabetes insipidus (34.4% vs. 11.2% vs. 5.2%) was decreased (p<0.01). Moreover, a significant postoperative improvement of ophthalmological complaints was detected (p<0.001). The long-term follow-up showed 40% of the entire recurrence rate occurring after the ninth postoperative year. The progression-free survival time increased significantly from group A to group B (p<0.05).

CONCLUSIONS

The results demonstrate a benefit of the recent developments of pituitary surgery in the short-term results as well as in the long-term outcome. The prognosis of pituitary adenoma patients could be improved by the introduction of new surgical approaches and techniques in the last decades. Also the perioperative morbidity and mortality rate has been reduced clearly since the 1970s. Furthermore our results emphasise the necessity of lifelong follow-up of all patients with successfully treated pituitary adenomas.

Prognosis of gliomas in the 1970s and today

The benefit of the current strategy for diagnosis (magnetic resonance, [MR] imaging) and treatment (surgery, chemotherapy, radiotherapy) of gliomas, in contrast to the standard treatment in use before MR imaging and the microsurgical era, has not yet been determined. A retrospective statistical analysis was performed for all patients with glioma who underwent surgery at a single institution between 1965 and 1974 (Group I, 88 patients) or 1986 and 1995 (Group II, 249 patients). There were no major differences in symptomatology, tumor localization, and number of surgical procedures. The mean time until tumor diagnosis was significantly shorter in Group II (Group I, 48 weeks; Group II, 19.5 weeks). Also, the mean time from initial symptoms to surgery was significantly shorter for high-grade gliomas in Group II (Group I, 16.3 weeks; Group II, 11.7 weeks). For high- as well as low-grade gliomas, there was a clear reduction of the perioperative morbidity and mortality rates in Group II. Nevertheless, for the postoperative duration of survival, no significant differences were demonstrated for high- or low-grade gliomas. Based on the results of this study, the perioperative morbidity and mortality rate as well as the time from diagnosis to treatment have been remarkably reduced within the last 30 years. Nevertheless, the overall prognosis for patients with gliomas has not changed from the 1970s until today. Thus, the introduction of modern diagnostic modalities and surgical procedures has not improved the outcome in patients with glioma. Further research to improve the treatment of this disease is urgently needed.

Chronic subdural haematoma, an unusual injury from playing basketball

Although the literature records instances of acute epidural haematoma and acute subdural haematoma related to playing basketball, there has not been a report of chronic subdural haematoma as a basketball injury. With the burgeoning interest in this sport in the United Kingdom and Europe, the possibility of this particular neurotrauma increases. Such an injury, along with the diagnosis and management of this often insidious lesion, is documented in this case report.

Computed tomography number correlations for metrizamide computed tomographic ventriculography

The authors describe a method that permits the determination of the precise intraventricular iodine concentration after metrizamide computed tomographic ventriculography. There is an observed linear relationship between computed tomography number (Hounsfield units) and iodine concentration. This relationship may be used to provide the basis for a method of evaluating ventricular fluid dynamics. This, in turn, is useful for the determination of the indications for a shunting procedure and for the evaluation of shunt function in a patient with an existing shunt.

Acute direct and indirect lesions of the brain stem--CT findings and their clinical evaluation

Since the introduction of computer tomography (CT) (Ambrose 1973, Hounsfield 1973) it has become an essential instrument in the diagnosis of acute intracranial lesions. The precise analysis of the CT and in particular the evaluation of the basal cisterns, yields results which are already wellknown, basically, from post-mortem investigations and clinical findings. However, while these were retrospective analyses and results, serial CT examinations which are free of risk for the patient and can be used in correlation with the clinical neurological findings, allow important assertions intra vitam, as well as a definitely better assessment of the prognosis. In addition to acute supratentorial lesions, acute and subacute infratentorial lesions are analysed and their clinical significance described. In this way, for the first time, the dynamics of the mechanical factors in raised intracranial pressure can be analysed. Important conclusions are drawn for the clinical management of the patients, and even some new indications for operation. Analysis of the acute hyperdense brain stem lesions--pathognomonic for haemorrhages--allows for the first time the diagnosis and continuous observation of traumatic and secondary haemorrhages caused by raised pressure, as well as spontaneous ones. As regards the mortality and morbidity, the results in this large series of traumatic and secondary haemorrhages are in striking contrast to previous analyses based on post mortem findings. Acute hypodense brain stem lesions are not amenable to any definite pathogenetic classification--softening, inflammatory lesions, tumours and oedema must all be considered. With acute lesions we are only dealing with infarcts, which are only incompletely assessable in the computer tomogram, and their diagnosis must still depend on the clinical findings. Secondary ischaemic lesions in acute raised intracranial pressure are identifiable in over 18% as infarcts which involve the entire territory of an artery. These additional space-occupying lesions are only survived by 11% of the patients. Hence the correlation which has been established between the basal cisterns and intracranial pressure is of great clinical significance. From our own research group several reports on different aspects of raised intracranial pressure and lesions of the brain stem have appeared since 1979. Similar analyses of partial aspects of the basal cisterns, have been published only recently, and came essentially to the same conclusions.

The pathogenetic and prognostic significance of blood-brain barrier damage at the acute stage of aneurysmal subarachnoid haemorrhage. Clinical and experimental studies

In a retrospective study, pathological tissue enhancement was found in nearly two fifths of patients with acute SAH on contrast-enhanced cranial computed tomography. By means of absorption measurements with the region of interest technique over the basal ganglia, it was proved indirectly that pathological tissue enhancement should be brought about not only by hyperaemia, i.e., a blood volume increase, but also by extravasation of the contrast material, i.e., blood-brain barrier (BBB) disruption. A similar conclusion was drawn from the retrospective isotope brain scintigraphy study. It was further established that, although the pathological contrast enhancement was most obvious in the cortex, and particularly in the neighbourhood of the subarachnoid spaces, the phenomenon is probably widespread throughout the brain. Patients with abnormal enhancement are likely to be in less favourable clinical grades, have a high incidence of marked or diffuse spasm, have a poorer outcome independent of surgical or conservative treatment, and develop cerebral infarction more frequently. Systemic arterial hypertension was associated with an increased incidence of abnormal enhancement. Pathological tissue contrast enhancement or isotope accumulation in the first few days of SAH may serve as prognostic signs indicative of the late development of vasospasm and ischaemia. As ischaemic disruption of the capillary system is not prominent in the initial days following any stroke, vasoactive substances arising from the breakdown of the blood clot should play important part in the BBB damage in the acute stage of SAH. The "cortical SAH" model developed in the animal experiments ensured a constant subarachnoid blood volume with minimal local brain damage. The intracranial pressure and mean arterial blood pressure did not change significantly, and perfusion defects did not arise. Thus, this model proved suitable for studying the influence on the BBB of vasoactive blood breakdown products (responsible for arterial spasm) without the accompanying effects of pathological conditions such as raised intracranial pressure, systemic hypertension, non-reflow phenomena, which also disrupt the BBB. Measurements on the water, electrolyte, albumin contents of brain tissue, as well as the immunohistochemical localization of albumin, clearly indicated that the brain oedema developing at the acute stage of experimental SAH could be classified as having a primary vasogenic component in addition to the cytotoxic component. This increased capillary permeability was found to be brought about by opening of tight junctions and pinocytosis in the endothelial cells. The pathological capillary permeabilit

Temporal evolution of hypoxic-ischaemic brain lesions in asphyxiated full-term newborns as assessed by computerized tomography

Hypoxic-ischaemic brain lesions may be detected as low density (LD) areas by means of computerized tomography (CT), but the clinical significance of such LD areas has been controversial. Since timing might be a critical factor, we studied the temporal evolution of LD areas in 9 asphyxiated term babies who had had two or more CT, and compared the changes to the neurodevelopmental outcome. Scans were classified according to the elapsed time after asphyxia as early (day 1-7, n = 6), intermediate (week 2-4, n = 7; week 4-7, n = 3) and late CT (3 months or more, n = 7). In early scans, no, or only ill defined, LD areas were seen in the periventricular region. In intermediate CT's, LD-zones were further diminished in those babies who later were normal. Sharply accentuated LD areas, however, appeared in those who later suffered from neurodevelopmental disorders. These LD areas, probably representing hypoxic-ischaemic lesions, were located periventricularly, extending into the subcortical white matter and the cortex, and usually involved both hemispheres symmetrically. They began to disappear at 4 to 7 weeks in some regions, possibly because of glial proliferation. LD persisting more than 4-7 weeks tended to transform into cyst-like lesions, or marked atrophy. We conclude (1) that hypoxic-ischaemic lesions appear as zones of low density on CT scans performed after the first week and (2) that the extent of such lesions can best be assessed between 9 to 23 days after asphyxia.

Significance of contrast enhancement in cranial computerized tomography after subarachnoid hemorrhage

Eighty patients with subarachnoid hemorrhage underwent computerized tomography (CT) scanning before and after administration of Conray contrast medium. Abnormal enhancement was seen in visual evaluation of the CT scans in 26 cases, in the regions bordering the subarachnoid spaces. Abnormal enhancement was associated with a poor clinical condition, angiographic spasm, and a poor outcome. Measurements of absorption values in the thalamus revealed significant increases in density after contrast enhancement in those patients whose scans showed abnormal enhancement in the regions bordering the subarachnoid spaces on visual evaluation. The authors suggest that the abnormal enhancement is parenchymal, in the gyri, and is not "subarachnoid." They suggest that it is due to gyral hyperemia or extravasation of contrast material into the cortex resulting from breakdown of the blood-brain barrier, or a combination of both factors.

Sedimentation level in chronic subdural hematoma visible on computerized tomography

A clear interface dividing subdural hematoma into an upper hypodense and a lower hyperdense part was seen on computerized tomography (CT) scan in seven of 140 patients with chronic subdural hematoma. All except one of the seven patients had a definite history of head trauma more than 1 month before they developed acute disturbances of consciousness and pronounced hemiparesis. Consequently, they remained bed-ridden until they underwent drainage of the subdural hematoma. This group was compared to seven chronic subdural hematoma patients with mild clinical manifestations who were selected and intentionally confined to bed for a period before CT examination and craniotomy. The CT scans in this latter group did not show the clear interface in the subdural hematoma seen in the first group. Based on this study, it is hypothesized that this sedimentation level occurred as a result of rebleeding into a chronic hematoma that was sufficiently old to result in its contents being homogenous prior to the rebleed. In cases of rebleeding, a sufficient period of bed confinement in the brow-up position before CT examination allows development of a gravitational sedimentation in the hematoma. This clear level of sedimentation is seen in only a small portion of patients, but this finding may be specific for a significant amount of rebleeding and may herald acute deterioration.

Evaluation of cross-sectional geometry and mass density distributions of humans and laboratory animals using computerized tomography

The purpose of this study was to determine the cross-sectional geometry and mass density distribution of a young porcine subject using the X-ray computerized tomographic (CT) method and to perform a comparative study of anatomical features of this subject and a 3 yr old female child specimen. The cross-sectional CT scans of the porcine subject were obtained at 1 cm intervals. The outlines of each cross section and of selected anatomical components within each section were obtained by standard picture processing techniques. The mass and inertia tensor for each cross section and for each anatomical structure in a section were computed based on the CT numbers. The porcine subject was then sacrificed, frozen, sectioned and photographed. These sectional photographs were then compared with those obtained from the CT method. Tabulated cross-sectional mass and inertia tensor obtained from CT scans of the porcine subject were also used to compare with similar results derived from previously completed CT scans of the 3 yr old female child specimen. In particular, the comparisons were made on the location of the center of gravity and the inertia tensor in the head, neck, head and neck and cervical spine regions. Some immediate applications of this data are inputs to finite element models, lumped parameter biodynamic models, computer simulation of vehicle crash victims, and dummy design.

Emergency presentation of subdural hematoma: a review of 85 cases diagnosed by computerized tomography

The emergency presentations of 85 patients diagnosed by computerized axial tomography (CT) as having subdural hematomas (SDH) were retrospectively reviewed to identify factors contributing to an early or delayed diagnosis. Sixty-one of 85 patients (72%) were diagnosed within 24 hours of presentation. Forty-five of 57 (79%) with definite history or signs of cranial trauma were diagnosed within 24 hours, while only 16 of 28 (57%) without historical or physical evidence of trauma were diagnosed promptly. Focal neurologic signs were present in 32 of 57 patients (56%) with head trauma and 24 of these patients (75%) had an early CT scan. Twenty-two of 50 patients (44%) with head trauma had skull fractures, but the presence or absence of skull fracture alone did not serve to hasten the diagnosis in this group. In patients without head trauma, 14 of 28 (50%) had focal neurologic signs, with eight of 14 (57%) undergoing CT scan within 24 hours. No patient in this group had an abnormal skull series. Thus despite the immediate availability of CT scanning, a significant number of patients, especially those without history or evidence of head trauma, had a delay in diagnosis exceeding 24 hours. The presence of a focal neurologic sign is a more sensitive indicator of the presence of SDH than is a positive skull series.

Brain abscess and its surgical management

A series of 56 patients with brain abscesses who were treated over a period of 23 years is reviewed. Patients with posttraumatic infections were not included. The operative mortality was 11%. Aspiration of purulent material, radical excision of the abscess, drainage of pus, or a combination of these procedures was used according to the patient's condition and the location of the abscess. The relatively low mortality may be related to the preoperative condition of these patients, who were operated upon in the subacute or chronic stage of their disease. Conservative surgery, especially when functionally important parts of the brain are involved, helps to keep the postoperative neurological deficit as low as possible. Computerized tomography is of primary importance in localizing, diagnosing, and following the evolution of a brain abscess.

Cerebral abscess. Aetiology and pathogenesis, symptoms, diagnosis and treatment. A review of 200 cases from 1935-1976

From 1935-1976 a total of 200 patients with cerebral abscesses were referred to the University Clinic of Neurosurgery, Rigshospitalet, Copenhagen. The primary source of infection could be established in 169 cases (85%). Bacteria could be cultured in 58% of the cases. From 1935-1957 nearly all patients were subjected to ventriculography (107/129). Cerebral angiography was the dominating diagnostic method from 1958-1974. Since then, 30 patients with a suspected intracranial abscess have been examined by computed tomography. The overall mortality has been 40%, but for the period 1958-1976 17%.

A contribution to the rapid diagnosis of subdural empyema

The authors report their experience with CT scanning ina series of 4 cases of subdural empyema, over a period of 10 months; all the patients were male, aged 16 to 25 years. A review of the literature shows that this disease, in spite of the large variety and efficacy of the available antibiotics, is marked by a significant mortality and morbidity rate if the diagnosis is delayed. Study of the cases reported here, as well as those in the literature, attests that CT scanning of the brain is nowadays the method of choice for early diagnosis of these lesions, and for timing of appropriate intervention according to variations in the development stage of the suppuration. From the study of this series of cases, it is clear that in the future, CT scanning of the brain will certainly allow the hope of a greater survival rate and an appreciable decrease in morbidity in cases of subdural empyema.

The value of computerized tomography in oral surgery

Computerized tomography is known to be of value in the assessment of malignant tumors of the head and neck. In addition, it can be helpful in the diagnosis of maxillofacial injuries, especially of the midface, and blowout fractures of the orbital walls. The present article reviews its possible role in the management of patients with expanding and infiltrating lesions of the jaws. An important feature of the technique is that soft tissues can be clearly demarcated from the surrounding structures. In addition, views are possible in both axial and coronal planes. Since 1977, CT has been employed in more than twenty patients with benign or locally invasive jaw lesions and has demonstrated a high degree of accuracy. However, a much larger series is necessary to assess the reliability of the technique and to define its role in the preoperative investigation of patients with this type of problem.

[Contribution of computerized tomography to the diagnosis and postoperative study of sellar tumors]

The computerized tomography (C.T.) of 18 patients with sellar tumours were analysed. The C.T. made before surgery in 6 cases was positive in 3 and the type of tumour suggested by C.T. was confirmed in 3. Twelve patients had a C.T. investigation after surgery and the examination suggest recurrent tumour in 5. Two of these were re-operated. One patients with cholesteatoma had the recurrent tumour verified by surgery and the other, with a pituitary adenoma during re-operation was noted only cicatricial tissue at sellar region.

The role of computed tomography in acute head injury

Computed tomography (CT) of the head provides the ability to rapidly evaluate patients with acute head injuries. Moreover, CT aids in surgical planning, prognosticating outcome and recovery time, and monitoring nonsurgical injuries. The authors review the ways in which CT is employed in a multiple trauma center.

Delayed sequelae of head injury

The evaluation of delayed sequelae of head injury is greatly facilitated by CT. This non-invasive technique provides us with the opportunity to evaluate the head trauma patients sequentially to detect the development and clinical significance of post-traumatic sequelae like delayed intracerebral hemorrhage, hydrocephalus, and post-traumatic atrophy.

An analysis of 113 intracranial infections

The location, source of infection, and CT characteristics of 90 intracerebral abscesses and 23 subdural empyemas are reported with special regard to capsule enhancement and surrounding cerebral edema.

Enlargement of intracerebral haematomas following surgical removal of epidural haematomas

Postoperative follow-up computerized tomographic (CT) scans were performed in 16 cases of acute epidural haematomas to assess the efficacy of surgical treatment. Particular attention was paid to postoperative intracerebral haematomas that were detected in four cases on the preoperative CT scans. The intracerebral haematomas were found to have enlarged in all four cases on CT scans performed immediately after removal of the epidural haematomas. In the other 12 patients in whom no apparent abnormalities other than epidural haematomas were detected on preoperative CT scans, postoperative CT scans did not show development of intracerebral bleeding. The results indicate that bleeding may be encouraged in areas of intracerebral haemorrhage when coexisting epidural haematomas are evacuated. The possible pathophysiology of enlargement of intracerebral haematomas after decompression is discussed.

Contrast enhancement of cranial lesions in computed tomography

The time course of enhancement in apparently normal brain tissue, edema and focal lesions during 30 to 60 min after intravenous injection of vascular contrast medium was evaluated in a series of 41 patients with different intracranial lesions. The attenuation of apparently normal unenhanced brain tissue varied with the level of the scan, mainly an effect of beam hardening. Different types of enhancement response are discussed in terms of a 3-compartment model. The differential diagnostic potential of contrast enhancement in the early phase needs further evaluation using instruments with short scanning time, while the late phase of enhancement must be recorded with the use of a reliable head fixation to provide reproducibility of repeat measurements.

The overshoot artifact as an aid in differentiating low densities on the computed tomographic scan

This brief report describes an artifact that is seen as a thin, white rim outlining an air collection on the EMI 80 X 80 and 160 X 160 matrix CT scanners. This artifact is not associated with fat density and, therefore, its recognition allows presumptive differentiation between air and fat densities. The attenuation numbers of the lesion should then be obtained for confirmation.

Cerebellar hemorrhage in adults. Diagnosis by computerized tomography

A series of 10 adult patients with cerebellar hemorrhage diagnosed by computerized tomography (CT) is described. Hypertension was the most common etiological factor, accounting for 70% of the cases. The clinical presentation appeared to fall into two basic groups. The first group (60% of the cases) ran a progressive course with early brain-stem compression. The second group had a benign course with findings of focal cerebellar dysfunction. The CT findings reflected the two clinical categories. The scans of Group 1 patients revealed a lorge hematoma (greater to or equal to 3cm) and substantial ventricular dilatation. In contrast, scans of Group 2 patients demonstrated a small hematoma (less than 3 cm) without ventricular dilatation. Use of CT scanning allowed the accurate diffferentiation of cerebellar hemorrhage from primary brain-stem and intraventricular hemorrhage. The findings of the CT investigations proved very helpful in defining appropriate therapy.

Treatment of tumours of the posterior part of the third ventricle and the pineal region: a long term follow-up

This paper represents a further investigation into the origninal series, with additional cases from N.I.N.U. This follow-up has been immeasureably enhanced by the availability of the EMI Scanner. It seems clear that there continues to be adequate evidence that the use of shunting procedures, followed by radiotherapy, is a rational approach to tumours of the pineal and posterior third ventricular region. Short of more extensive evidence to the contrary, we feel that it remains the method of choice in the initial treatment of these difficult lesions.

CT and arteriography in cerebral ischemia. A preliminary note

Sixty patients with cerebral ischemia were studied by both CT and angiography. The results are: 1. Thrombosis of the internal carotid artery: CT shows a hypodensity lateral to the frontal horn. 2. Thrombosis of the middle cerebral artery: the hypodensity occupies the convexity of the frontal, parietal, and temporal lobes. 3. In thrombosis of the posterior cerebral artery there is an occipital hypodensity, while in thrombosis of the vertebral artery the hypodensity occupies a cerebellar hemisphere. 4. Circulatory disturbances without occlusion of the major cerebral vessels: there is a disproportion between the serious CT lesion and paucity of the angiographic findings.

Heart imaging from computerized tomography

In vitro and in vivo animal experiments have demonstrated the potential for using computerized tomography in heart imaging. This paper summarizes some of the work done in our laboratory related to heart imaging of dogs, of cadavers, and of live subjects using the CT approach. We have also provided examples demonstrating a method for computing the heart volume from serial CT images.

The contrast-enhanced CT scan and the radionuclide brain scan: parallel mechanisms of action in the detection of supratentorial astrocytomas

The preoperative contrast-enhanced CT scan and the radionuclide brain scan of 70 patients with surgically verified supratentorial astrocytomas were evaluated and compared. The results indicate parallel mechanisms of action of contrast enhancement and radionuclide uptake. These diagnostic modalities apparently mirror the integrity of the blood-brain barrier (BBB) and therefore are useful in assessing the degree of malignancy of supratentorial gliomas. However, lesions with an intact BBB will be missed with RN imaging. These lesions and/or the associated mass effect will be detected with contrast-enhanced computed tomography. Our findings firmly establish contrast-enhanced CT as the primary investigate tool in the suspected brain tumor.

Computerized tomography and surgical treatment in intracranial suppuration. Report of 30 consecutive unselected cases of brain abscess and subdural empyema

The authors report their experience with 30 cases of intracranial suppuration: 23 with brain abscess and seven with subdural empyema. All of the cases were diagnosed by means of computerized tomography and enhancement with intravenous contrast material. Most of the patients were treated by single or repeated aspiration through burr holes.

Two cases of giant intracerebral aneurysm simulating neoplasm on ct scan; one with coexistent chronic subdural hematoma

Two cases of giant intracerebral aneurysm are presented. Both exhibit increased absorption values in a circumferential configuration peripherally after the administration of contrast material. In addition, one case demonstrates a coexistent contralateral chronic subdural hematoma. No previous example of intracranial aneurysm exhibiting this configuration on computed tomography has been described in the literature. The operative, computed tomographic, radionuclide and angiographic findings are described and the differential diagnosis discussed.

Giant craniopharyngioma evaluated by computerized axial tomography

The advent of computerized axial tomography (CAT scan) has augmented the neurologic diagnostic armamentarium dramatically. The ability of the CAT scan to differentiate and accurately locate various intracranial densities in a noninvasive manner makes it a very valuable method of investigating craniopharyngiomas. Because they are often composed of cystic, solid, and calcified portions, craniopharyngiomas are very well demonstrated, with the same CAT scan revealing ventricular size as well. A recent and representative case is reported demonstrating the correlation between the CAT scan and the operative findings.

Nuclide imaging and computed tomography in cerebral vascular disease

This report presents our experience with computed tomographic and radionuclide scans in 224 patients with ischemic or hemorrhagic infarcts or intracerebral hematomas secondary to cerebral occlusive vascular diseases. The results vary according to the site of vascular occlusion. The radionuclide angiograms and static scintigrams show four distinct patterns in cases of occlusion of the middle cerebral artery. Computed tomographic scans exhibit less variation in appearance and have a higher sensitivity in cases of recent ischemic infarction. The "tentorial confluence sign" is an important finding on static scintigrams in patients with occipital infarction; if this sign is not present, this diagnosis should be suspect. Earlier reports have established the value of computed tomography and radionuclide scans in the evaluation of cerebral infarction. In individual cases, however, each of these modalities may render nondiagnostic or false negative findings; combining both both types of examinations and comparing results yield a greater likelihood of an accurate diagnosis of cerebrovascular disease. Computed tomography is clearly more valuable than radionuclide scans in the diagnosis and follow-up of hemorrhagic infarcts or parenchymal hematomas.

Computerized tomography of in vitro abdominal organs--effect of preservation methods on attenuation coefficient

The effect of formalin, freezing, and refigeration on the attenuation coefficient of fresh abdominal tissue of rhesus monkeys and dogs was investigated over a 1-week period. These techniques were used individually and in combinations designed to simulate circumstances involved in future in vitro investigations of human specimens. Statistically significant alterations of attenuation coefficients were found to occur at all scanning times within the first week except for the first 48 hr of formalin storage. Refrigeration resulted in the largest alteration. The results indicate the attenuation coefficients of tissues preserved by these three methods may be altered and that the magnitude of the change will vary according to the preservation techniques, tissue, and duration between tissue death and scanning.

Computed tomography in the diagnosis of cerebral abscess

Computed tomography (CT) was performed 64 times on 22 patients with cerebral abcesses, using the 160 X 160 matrix EMI scanner. The diagnosis was based upon the demonstration of a localized low-attenuation area appearing, after the administration of contrast medium, as a high-attenuation annular rim ascribed to displaced and/or newly formed vessels, the so-called abscess membrane. CT is compared with the conventional diagnostic methods of neuroradiology. The differential diagnostic accuracy of CT is clearly superior to that of previous methods, including angiography, which, until now, we have considered the most accurate method.

Computer tomography of traumatic extracerebral lesions

Twenty-one traumatic intracranial extracerebral lesions in 15 patients were examined with the EMI scanner using the 160x160 matrix. The results were compared with operation and angiographic findings. Although angiography seems to be a more reliable diagnostic aid, computer tomography has important advantages as it provides information on the nature and extent of the extracerebral lesion as well as on concomitant brain damage.

Computer tomography in disseminated sclerosis

A case is reported where the appearance of acute, diffuse, disseminated sclerosis on computer tomography (Ct scan) is described and the literature is reviewed. This disease may give rise to multiple, small areas of diminished X-ray absorption which may decrease in size during the course of the disease. The histological features of one of the lesions was correlated with the radiological findings. It is suggested that, perhaps, only during the active stage of demyelination can the lesions be detected on the Ct scan.