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Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

At least 253 records · Page 14Linked to original sources

Computed tomography in detecting calvarial metastases: a comparison with skull radiography and radionuclide scanning.

A clinical study comparing the relative sensitivities of computed tomography, skull radiography, and radionuclide scanning in the detection of skull metastases indicated that CT was the least sensitive of these three modalities. CT could however detect a majority of lesions if scans were viewed at appropriate window settings. Phantom studies showed that the limitations of CT can be related to limited spatial resolution, the density of the lesions, partial volume averaging, and plane of section.

Humans↗

Relative detectability of intracranial calcifications on computed tomography and skull radiography.

Phantom studies comparing skull radiography and cranial computed tomography (CT) show that CT is 5 to 15 times more sensitive than skull radiography in the detection of intracranial calcifications. The difference in detectability varies with object size. The relative sensitivity of CT increases with increased object size within the constraints of the section thickness. The relationship of these findings to the detectability of pineal and choroid calcifications is discussed.

Brain↗

Malignant melanoma metastatic to the central nervous system.

The CT appearance of metastatic malignant melanoma is varied, but it can show features suggesting the correct diagnosis. Intracerebral hemorrhage alone, associated with an adjacent tumor nodule or mixed diffusely with a tumor, occurred in 10 of 33 patients. Identification of a tumor nodule is important, since it may be the site of recurrent hemorrhage if not removed completely at surgery. Unusual presentations such as meningeal carcinomatosis and lesions simulating primary gliomas also occurred.

Adult↗

Computed tomography in the follow-up of medulloblastomas and ependymomas.

The course of 36 patients with medulloblastoma and ependymoma was evaluated prospectively by clinical examination, radionuclide (RN) studies and computed tomography (CT). Seventeen of the 36 patients (47%) had tumor recurrence. Twelve (41%) of the 29 patients with medulloblastoma had recurrent tumors of which 7 of 12 (58%) were at the primary site and 2 of 12 (17%) were within the ventricles while 10 of 12 (83%) were in the subarachnoid space. Five of the 7 patients with ependymoma had recurrent tumors. In 4 of the 5 patients tumor recurred at the primary site while subarachnoid seeding occurred in 2 of 5 patients (40%) and intraventricular metastases were found in 4 of 5 patients (80%). Progressive ventricular enlargement often accompanied subarachnoid seeding, presumably secondary to obstruction of cerebrospinal fluid (CSF) flow in the subarachnoid pathways. CT and RN scans were frequently complementary in detecting tumor recurrence.

Brain Neoplasms↗

Computed tomography of herpes simplex encephalitis.

On the initial computed tomographic (CT) scan in 10 of 13 patients with herpes simplex encephalitis (HSE), the most characteristic finding was a unilateral, low-density lesion in the medial temporal lobe and/or insular cortex. This lesion was seen in all patients as the disease progressed. When associated with hemorrhage and streaked contrast enhancement this lesion added specificity to the CT scan, but this situation occurred in only 3 patients. Early in the course of HSE, focal CT findings localized the temporal lobe of greatest involvement in 12 patients; 1 had a normal initial CT scan.

Adolescent↗

Quantitative aspects of contrast enhancement in cranial computed tomography.

The temporal relationship of blood iodine levels to tumor enhancement in cranial computed tomography was studied in a series of patients. Both the bolus and biphasic techniques were evaluated. Peak tumor intensity may not develop immediately, but may be more pronounced on a 20-minute scan. The low-density centers seen in malignant gliomas show delayed enhancement. These low-density centers represent a second compartment which equilibrates with the intravascular and interstitial contrast material at a much slower rate. Patients with malignant gliomas can be scanned up to one hour following contrast injection without significant loss of information.

Blood-Brain Barrier↗

Interval computed tomography in multiple sclerosis.

Computed tomography demonstrated areas of abnormal attenuation in the white matter in 14 patients with multiple sclerosis (MS). Nine were studied two or more times. Acute MS lesions exhibit decreased or normal attenuation without contrast enhancement and increased attenuation with it. On later scans these lesions show decreased attenuation with or without contrast material. Some lesions remain decreased in attenuation and some become normal both with and without contrast material.

Adolescent↗

Computed tomographic brain scanning in intraparenchymal pyogenic abscesses.

Retrospective analysis of 25 pyogenic brain abcesses diagnosed by computed tomography (CT) revealed relatively specific morphologic characteristics of these infections. The ability to obtain an early accurate diagnosis resulted in a dramatic decrease in patient morbidity and mortality. Repeated examinations by CT permitted close monitoring of the response of the abscess to antibiotic therapy. In some instances the need for surgical intervention was eliminated or the surgical approach was modified as a result of these studies.

Actinomycosis↗

Optimal contrast dosage in cranial computed tomography.

Comparison of different contrast dosages in adult patients with malignant gliomas studied by computed tomography indicates that 28-42 g of iodine is required for clinically diagnostic results. This can be translated into a 10 min iodine blood level of 100 mg/100 ml. Contrast doses in the range of 14 g of iodine are not satisfactory.

Brain Neoplasms↗

Coronal computed tomography: indications and accuracy.

The application of wide aperture scanners to neuroradiology permits improved anatomic definition and localization of intracranial and intraorbital lesions. Coronal scans are most useful in demonstrating lesions of the skull base and apex, distinguishing between infra- and supratentorial lesions, and in determining if a lesion is intra- or extraaxial. Limitations of coronal scans include discomfort in positioning, high spatial frequency artifacts, and additional radiation exposure.

Adult↗

Decreased mortality from brain abscesses since advent of computerized tomography.

No deaths have occurred among 20 consecutive patients with intraparenchyma brain abscesses treated at the University of California, San Francisco, since computerized tomographic (CT) brain scanning became a routine diagnostic procedure (study period: July, 1974, to June, 1977). These patients have been compared to 18 consecutive cases treated without benefit of CT analysis (January, 1970, to June, 1974) in order to determine the factors responsible for the recently improved prognosis. The mortality rate was 44% for all cases and 36% for all operated patients treated before the availability of CT. Similar morbidity (about 33%) was seen in survivors from both series. No significant differences in the two groups were noted with respect to patient population and antibiotic or corticosteroid therapy. Among the factors that may have contributed to the improved results for patients diagnosed with CT are: less frequent occurrence of multiple abscesses, fewer patients with poor preoperative clinical status, and a greater incidence of total abscess removal. In addition, CT scanning provided more accurate diagnosis and localization of abscesses and aided in the rapid detection of postoperative complications that probably accounted for six out of eight deaths in the earlier series. Serial CT studies provide a means to optimize the timing for surgical intervention and plan appropriate medical therapy. It is noteworthy that two patients have been followed by serial CT scans to non-surgical cures.

Adult↗

Diagnosis of progressive multifocal leukoencephalopathy by computed tomography.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system which predominantly affects immunologically compromised hosts. The distinctive CT appearance in three documented cases includes low-density lesions of central and convolutional white matter with scalloped lateral borders. Lesions demonstrate no mass effect or contrast material enhancement. Findings are discussed with reference to other entities which may produce a similar CT appearance.

Adult↗

Cranial computed tomographic scan appearance of Sturge-Weber disease: unusual presentation.

The CT findings in both the typical and atypical presentations of the Sturge-Weber syndrome are characteristic if not pathognomonic in most cases. The typical gyriform cortical calcification and cortical atrophy are well demonstrated whether associated with a small or enlarged hemicranium. Contrast enhancement was demonstrated in both cases where contrast medium infusion was performed.

Adolescent↗

Quantitative aspects of computed tomography of the blood and cerebrospinal fluid.

Computed tomographic (CT) scans of fresh and coagulated blood in vitro as well as calcium and iron solutions demonstrate that the increased absorption seen in hematomas is primarily a reflection of hemoconcentration: calcium plays essentially no role in this increased absorption, while iron makes a minimal contribution. In vitro studies of cerebrospinal fluid (CSF) indicate that CT scanning is insensitive to pathological elevations of CSF protein.

Blood↗

Computer tomography in cisternography with metrizamide.

The preliminary results with computer tomography in cisternography with metrizamide (Amipaque) indicates that both normal and abnormal cerebrospinal fluid dynamics can be accurately displayed with the advantage of spatial and quantitative detail. The pharmacokinetics of metrizamide clearance from cerebrospinal fluid to blood are similar to those of nuclides. Hence, similar problems in predicting response to ventricular shunting may arise. However, the quantitative features of this method have yet to be fully exploited.

Humans↗

Transient hydrocephalus in premature infants: Treatment by lumbar punctures.

Three premature infants with post-haemorrhagic hydrocephalus were treated by removing large volumes of cerebrospinal fluid with repeated lumbar punctures. After this treatment, a computerised tomographic brain scan showed that ventricle size had decreased, and subsequent head growth was normal in all three patients. The results suggest that acquired hydrocephalus in premature infants may be transient and that ventricular shunts may not be necessary in all cases.

Cephalometry↗

Computed tomography of granulomatous basal arachnoiditis.

Clinical findings are often insufficient to diagnose basal arachnoiditis and conventional neuroradiological techniques often fail to demonstrate the inflammatory process. Computed tomographic (CT) scans, however, usually can demonstrate the circle of Willis, and the basilar, sylvian quadrigeminal, and vermian cisterns. Cisternal anatomy can also be delineated on the CT scans by metrizamide cisternography. CT scanning may prove to be the most accurate and sensitive radiographic test for basal arachnoiditis. Findings in three patients are reported.

Adult↗