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Biomedical subjects

R G Quisling

Publications and source records attributed to R G Quisling.

At least 19 recordsLinked to original sources
PubMed2001

Managing predefined templates and macros for a departmental speech recognition system using common software.

The authors have developed a networked database system to create, store, and manage predefined radiology report definitions. This was prompted by complete departmental conversion to a computer speech recognition system (SRS) for clinical reporting. The software complements and extends the capabilities of the SRS, and 2 systems are integrated by means of a simple text file format and import/export functions within each program. This report describes the functional requirements, design considerations, and implementation details of the structured report management software. The database and its interface are designed to allow all radiologists and division managers to define and update template structures relevant to their practice areas. Two key conceptual extensions supported by the template management system are the addition of a template type construct and allowing individual radiologists to dynamically share common organ system or modality-specific templates. In addition, the template manager software enables specifying predefined report structures that can be triggered at the time of dictation from printed lists of barcodes. Initial experience using the program in a regional, multisite, academic radiology practice has been positive.

Computer Peripherals↗
PubMed2001

A neuropsychological outcome study of a child's left pericallosal arteriovenous malformation with occult fornix lesion.

Pericallosal arteriovenous malformations are rarely reported, particularly in children. Moreover, few arteriovenous malformation studies report thorough neuropsychological outcome data for assessing post-surgical functioning. This case report provides a longitudinal study of a boy who initially presented for neuropsychological testing at the age of 8 years and 1 month, following polyvinyl alcohol embolization, two craniotomies and resections and stereotactic radiosurgery for a pericallosal arteriovenous malformation involving nearly all of the corpus callosum. Follow-up magnetic resonance imaging also indicated absence of the left fornix. Functioning has been assessed over 7 years. Neuropsychological measures identified a consistent pattern of verbally mediated cognitive and memory deficits, with relatively spared visual perceptual and visual motor functioning. No evidence of a split-brain syndrome was found. The findings are consistent with insult to dominant hemisphere language and memory systems, provide an interesting example of neurodevelopmental compensation for significant early brain insult, and may provide insight into functions subserved by the fornix.

Brain Damage, Chronic↗
PubMed2001

Quantitative assessment of brainstem development in Joubert syndrome and Dandy-Walker syndrome.

Key features of Joubert syndrome include developmental delay, hypotonia, hyperpnea and apnea, oculomotor apraxia, and the presence of the molar tooth sign on axial imaging through the brainstem isthmus--the junction of the pons and mesencephalon. Interestingly, 1 in 10 patients with Joubert syndrome has abnormal cerebrospinal fluid collections misdiagnosed as Dandy-Walker variants. Because of important differences in patient management, genetic counseling, and prognosis between these conditions, we undertook a study to determine if the brainstem isthmus is normal in Dandy-Walker syndrome. Using standard landmarks, we evaluated development of the isthmus in normal subjects and in subjects with Joubert syndrome and Dandy-Walker syndrome. Four of five brainstem measures increased with age in normal subjects. In subjects with Joubert syndrome, the depth and length of the interpeduncular fossa were increased, and the width of the isthmus was decreased. In subjects with Dandy-Walker syndrome, the width of the brainstem isthmus was normal, and the molar tooth sign was absent. Although the pons can be hypoplastic in Dandy-Walker syndrome, we conclude that the pontomesencephalic junction is normal. Thus, the molar tooth sign can effectively distinguish between Joubert and Dandy-Walker syndromes. Genetic heterogeneity or epigenetic factors may account for abnormal cerebrospinal fluid collections in some cases of Joubert syndrome.

Adolescent↗
PubMed1999

Molar tooth sign in Joubert syndrome: clinical, radiologic, and pathologic significance.

Joubert syndrome is a rare autosomal-recessive condition characterized by early hyperpnea and apnea, developmental delay, and truncal ataxia. We previously described key ocular motor signs in Joubert syndrome and the molar tooth sign resulting from dysplasia of the isthmic segment of the brain stem, superior cerebellar peduncles, and vermis. In this study, we obtained clinical and developmental data in 61 cases, and radiologic data in 46 of these, to determine the prevalence of the molar tooth sign in a large sample, and to ensure that magnetic resonance images obtained for study were representative of the Joubert syndrome population at large. We studied the morphology of the isthmic segment of the pontomesencephalic junction, the segment of the brain stem derived from the primitive isthmus. Portions of the cerebellum analyzed included the superior cerebellar peduncles, the anterior and posterior lobes of the vermis, and the flocculonodular lobe. In one case, autopsy of the brain was performed. The average age at diagnosis was 33 months. All patients were hypotonic and developmentally delayed. The molar tooth sign was present in 85% of cases with 13% of these showing additional malformations. All patients without the molar tooth sign had other mimicking conditions such as neocerebellar dysgenesis, isolated vermian atrophy, cerebellar aplasia, and cystic dilation of the cisterna magna. Autopsy showed aplasia of the cerebellar vermis with dysplasia of the dentate nucleus, elongated locus coeruleus, and marked dysplasia of the caudal medulla. A better understanding of the clinical, radiologic, and pathologic features of Joubert syndrome should help uncover the genetic basis for the syndrome.

Abnormalities, Multiple↗
PubMed1999

Magnetic resonance imaging features and classification of central nervous system malformations in Joubert syndrome.

This article examines the magnetic resonance imaging features that typify the Joubert malformation. Specific morphologic features include: (1) dysgenesis of the isthmic portion of the brain stem at the pontomesencephalic junction, (2) abnormally thick superior cerebellar peduncles perpendicular to the brain stem, (3) hypoplasia of the cerebellar vermis with consequent enlargement of the 4th ventricle and rostral shift of the fastigium, and (4) sagittal vermic clefting. At least two of these features were present in every patient and all were present in some. The only cerebral anomaly identified was mild prominence of the ventricles and subarachnoid spaces. The "Joubert-plus anomaly" has been defined as the Joubert malformation plus additional anomalies of either the mesencephalon or the caudal 4th ventricle; this likely represents a similar but more extensive embryologic defect. By placing a relative numeric value on each morphologic feature, a classification scheme has been created that can quantitate the extent of the Joubert malformation in any individual case.

Adolescent↗
PubMed1998

Calcified cystic lesions in a patient with epilepsy and progressive dementia.

A 67-year-old woman had intractable epilepsy and developed a progressive dementia with upper motor neuron signs over the last 6 years. Magnetic resonance imaging (MRI) revealed multiple areas of large calcified cysts, which increased in number and size over the last 3 years. Discussion includes the appearance of these lesions radiologically and pathologically, as well as their differential diagnosis and clinical significance, focusing on the increasing detection of these lesions with current imaging techniques.

Aged↗
PubMed1998

High prevalence of bihemispheric structural and functional defects in Sturge-Weber syndrome.

Abnormal cerebral venous drainage is associated with hypoxia and glucose deprivation, which can account for progressive neurologic deterioration in Sturge-Weber syndrome. Although developmental delay is common in Sturge-Weber syndrome, bihemispheric calcification is uncommon. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to study the neuroanatomy, while single photon emission computed tomography (SPECT) was used concurrently to evaluate perfusion and glucose metabolism using 99mTc hexamethylpropyleneamine oxime (HMPAO) and [18F] fluorodeoxyglucose (FDG), respectively. Ten patients (10 to 22 years of age) with previously diagnosed Sturge-Weber syndrome, port-wine nevi, and clinical evidence of seizures or stroke-like episodes were studied. Five children with onset of seizures in the first year of life had overall clinical severity comparable to that of children with later-onset seizures. Calcification was present in both hemispheres in one patient; six additional patients had other radiologic evidence of bihemispheric disease; SPECT studies detected bihemispheric disease in four cases. Our study is the first to concurrently evaluate structure, perfusion, and glucose metabolism in Sturge-Weber syndrome and to show a mismatch between functional and structural brain imaging in both cerebral hemispheres. Widespread abnormalities of cerebral perfusion and glucose metabolism might explain the high prevalence of developmental delay associated with Sturge-Weber syndrome. Longitudinal studies are needed to define better the natural history of neurologic deterioration and radiologic progression that relates to central nervous system circulatory dysfunction in Sturge-Weber syndrome.

Adolescent↗
PubMed1998

Central nervous system structure and function in Sturge-Weber syndrome: evidence of neurologic and radiologic progression.

Sturge-Weber syndrome is characterized by the presence of a port-wine nevus, epilepsy, stroke-like episodes, headache, and developmental delay. We studied 20 cases to test the hypothesis that decreased cerebral blood flow alters neurologic function by affecting cellular glucose metabolism. Group A consisted of 10 patients with a mean age of 1.75 years and early seizure onset (6.8 months), whereas group B was composed of older patients (mean age, 15.3 years) with later onset of seizures (3.7 years). Neurologic disease was more severe in group A, but group B had more widespread structural brain defects - shown on computed tomographic scans and magnetic resonance imaging - and metabolic brain defects shown on hexamethylpropyleneamine oxime and [18F] fluorodeoxyglucose single photon emission computed tomographic scans. Six group A cases had hypoperfusion at baseline and five of nine had worsening of perfusion and glucose metabolism 1 year later. A total of 119 stroke-like episodes occurred in six group A cases and eight group B cases; there were 65% fewer strokes in children treated with aspirin. The data suggest that progressive hypoperfusion and glucose hypometabolism are associated with neurologic deterioration in Sturge-Weber syndrome. Longitudinal studies are needed to better define the natural history of disease and to evaluate the safety and efficacy of aspirin therapy.

Adolescent↗
PubMed1997

Imaging for pediatric brain tumors.

Radiological imaging plays an important role in the care of pediatric and adolescent patients undergoing evaluation and treatment of brain tumors. The primary objective for any diagnostic magnetic resonance or computed tomography study is to distinguish between normality and abnormality. Establishing normality is typically more difficult than recognizing obvious pathology. To declare that an imaging procedure reveals either no apparent or no significant disease requires the examination to have been performed appropriately with the most sensitive imaging modality, scanned in the right location, using parameters capable of providing the optimum spatial and contrast resolution. Once tumor is observed, the role of imaging then shifts toward more specialized tasks including predicting the type of tumor, establishing the spatial relationship between the mass and eloquent areas, and staging the furthest extent of disease. These tasks require sophisticated imaging and experienced interpretation to adequately plan treatment.

Brain Neoplasms↗
PubMed1997

"Joubert syndrome" revisited: key ocular motor signs with magnetic resonance imaging correlation.

Joubert syndrome is characterized by episodic hyperpnea and apnea, developmental delay, hypotonia, truncal ataxia, ophthalmologic abnormalities, and vermian dysgenesis. We studied 15 patients with the diagnosis of Joubert syndrome to (1) more fully define the syndrome's clinical features, and (2) correlate the clinical features with magnetic resonance imaging (MRI) findings. Eight of 15 patients had a history of episodic hyperpnea and apnea. All patients had developmental delay and hypotonia. Of the 13 patients receiving detailed neuro-ophthalmologic evaluations, three had optic nerve dysplasia, pendular nystagmus, and gaze-holding nystagmus. All 13 patients had a normal vestibulo-ocular reflex based on head thrust, but had absent to poor ability to cancel the vestibulo-ocular reflex horizontally and vertically. Twelve of 13 patients had impaired smooth pursuit. Twelve of 13 patients had defects in initiation of saccades and quick phases. Two of the most consistent radiologic features were absent or hypoplastic posterior cerebellar vermis, and deformed midbrain and pontomesencephalic junction, which based on ocular motor physiology correlate with the vestibulo-ocular reflex cancellation/ pursuit defect and saccade initiation defect, respectively. As a result of midbrain, vermian, and superior cerebellar peduncle abnormalities, axial neuroimaging showed a unique "molar tooth" appearance of these structures. These results indicate that Joubert syndrome results from maldevelopment of the midbrain and cerebellar vermis, producing a pathognomonic sign on MRI.

Adolescent↗
PubMed1996

Prospective localization of epileptogenic foci: comparison of PET and SPECT with site of surgery and clinical outcome.

PURPOSE: To correlate prospective imaging findings in patients with intractable partial epilepsy with site of surgery and clinical outcome. MATERIALS AND METHODS: Thirty-five patients (25 male, 10 female) underwent positron emission tomography (PET; n=25), interictal single photon emission computed tomography (SPECT; n=33), or postictal SPECT (n=23) for localization of epileptogenic foci. The standard of reference was site of surgery. RESULTS: Sensitivity was 60%, 61%, and 52%; positive predictive value was 83%, 71%, and 55%; and localization was incorrect in 12% (three of 25 cases), 24% (eight of 33 cases), and 43% (10 of 23 cases) in PET, interictal SPECT, and postictal SPECT, respectively. There was no statistically significant difference in localization capabilities in a comparison of interictal SPECT and PET (correct localization, P=.999; incorrect localization, P=.625). There was a trend toward higher incorrect localization with interictal SPECT. CONCLUSION: Postictal SPECT has low sensitivity and a high incorrect localization rate and should not be performed in these patients. Interictal SPECT with 6-8-mm full-width at half-maximum is an alternative to PET. However, the trend toward higher false-localization rates must be taken into consideration.

Adult↗
PubMed1995

Intracranial arteriovenous malformations: quantitative analysis of magnitude contrast MR angiography versus gradient-echo MR imaging versus conventional angiography.

PURPOSE: To quantitatively analyze magnitude contrast (MC) magnetic resonance (MR) angiography and gradient-echo (GRE) MR imaging for evaluation of persistent transnidal blood flow in intracranial arteriovenous malformations (AVMs) of various sizes before or after stereotaxic radiosurgery. MATERIALS AND METHODS: Thirty-three patients with AVMs underwent 42 MC MR angiographic (maximum intensity projection [MIP] and source imaging), GRE imaging with and without flow compensation, and conventional angiographic studies within 90 days of each other. RESULTS: For MIP, source, and GRE images, the sensitivities for detection of large AVMs (> 1 cm) were 95%, 100%, and 100%, respectively, and for small AVMs (< or = 1 cm) were 27%, 50%, and 67%, respectively. MC MR angiography and GRE imaging depicted all eight nidi that were completely thrombosed on conventional angiograms. CONCLUSION: GRE imaging and MC MR angiography reliably depict AVMs larger than 1 cm. GRE is more sensitive for detection of small residual nidi (< 1 cm). Source images must be evaluated to accurately assess low-flow lesions. Neither GRE nor MR angiography is reliable for detection of mean nidus diameters less than 0.36 cm.

Cerebral Angiography↗
PubMed1994

High-dose chemotherapy with marrow reinfusion and hyperfractionated irradiation for children with high-risk brain tumors.

Between November 1990 and March 1993, nine pediatric patients with newly diagnosed brain tumors having a high risk of failure with standard treatment received high-dose thiotepa/cyclophosphamide chemotherapy followed by autologous bone marrow infusion and involved-field hyperfractionated radiation therapy. The presenting diagnoses were brainstem glioma (BSG) [6], parietal mixed high-grade oligodendroglioma-astrocytoma [1], thalamic anaplastic astrocytoma [1], and high-grade parietal glioma [1]. Following chemotherapy there were two partial responses, one minor response, three with stable disease, and one with progressive disease. Responses were not evaluated in two patients who had toxic deaths. Following radiation two patients, one with brainstem glioma and one with anaplastic mixed glioma, achieved complete remission. The overall survival is no better than conventional therapy.

Adolescent↗
PubMed1994

Value of thallium-201 SPECT imaging in childhood brain tumors.

Thallium-201 chloride single photon emission computed tomography (201Tl SPECT) has been proposed as a diagnostic tool in the assessment of patients with brain tumors. We performed SPECT scans coupled with magnetic resonance imaging (MRI) in children with brain tumors to determine the sensitivity and potential value of SPECT in neuro-oncology. Each patient was injected with 2.5-3.0 mCi of thallium chloride, followed by technetium-99m HMPAO (5-15 mCi) to assess cerebral perfusion. 201Tl uptake was imaged with triple-headed SPECT in 20/24 (83%) histologically and anatomically diverse neoplasms with MRI-measurable residual disease, including 13/16 (80%) posterior fossa tumors. 201Tl SPECT demonstrated uptake in tumors with MRI volumes ranging from 0.03 to 60 cm3. 201Tl SPECT imaging was not correlated with the following MRI features: gadolinium enhancement, necrosis, exophytic, unicentric and multicentric. 201Tl uptake was not detectable in patients with tumors of maldevelopmental origin or radionecrosis. It is suggested that 201Tl SPECT is an important imaging adjunct in the assessment of children with brain tumors.

Adolescent↗
PubMed1994

Vein of Galen aneurysms: a review and current perspective.

Our approach to treating a patient with a vein of Galen aneurysm is, of course, influenced greatly by the age of the patient, the clinical symptoms, and the angiographic architecture of the malformation. Therapeutic options are primarily based on whether a true AVM is present or if the malformation represents an arteriovenous fistula involving the vein of Galen. Arterial endovascular approaches, microneurosurgery, and/or radiosurgery are preferred for management of the former; the transvenous endovascular approach has become the cornerstone of treatment in the latter. The most critical group, however, is the neonates in extreme cardiovascular distress. In this case our therapeutic intervention is initially endovascular from the venous side, either transfemoral or transtorcular. The immediate goal is to increase resistance to right ventricular output. Advantages of this approach over a transarterial approach include a shorter anesthesia time, minimal fluid and/or contrast administration, and creation of a wire "basket" or "bird's nest" on the venous side that helps prevent emboli that may be deposited on the arterial side in subsequent embolizations from passing through the malformation. The transvenous approach can be easily repeated multiple times and may be supplemented by transarterial embolizations. Endovascular coils have been the mainstay for such venous embolizations. The end point of treatment is not complete occlusion of the fistula but improvement in cardiac function. Often, more than one stage is required to reach our goal. The results in recent years have been encouraging and are to a large degree attributable to the advances in endovascular approaches. With future improved tools for diagnosis and treatment, perhaps the prognosis for this difficult malady also will continue to improve.

Arteriovenous Fistula↗
PubMed1994

Vein of Galen fistulas.

The vein of Galen malformations continue to be challenging lesions for the neurosurgeon. Evolving therapies, including transvenous and transarterial embolotherapies, have dramatically changed our approach to these lesions over the past 5 years. The neurosurgeon remains the physician in charge of the care of these individuals. In neonates suffering from severe progressive cardiac failure, about a 50% survival rate can be expected. Those patients demonstrating significant injury to the central nervous system prior to therapy should probably be excluded from the aggressive treatment category. Low morbidity and mortality can be expected in the infant and older childhood group of patients harboring vein of Galen malformations treated interventionally. The tendency today is toward a combined transvenous transarterial approach to these lesions, no matter which clinical category is treated. Aggressive therapy is indicated in the control of hydrocephalus and seizures before, during, and after treatment. The overall philosophy, especially in the transvenous approach to these lesions, remains the careful and repeated embolization of these lesions in a staged fashion to encourage a graded thrombosis in an attempt to minimize the risk of hemorrhage and injury to the central nervous system. The overall prognosis is difficult to predict at this time, but it would appear to be better than with standard surgical treatment of these lesions. These therapies are evolving, and further improvements in the techniques and outcome are anticipated.

Cerebral Veins↗