David O. Davis

Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects: a prospective investigation

We performed magnetic resonance imaging on sixty-seven individuals who had never had low-back pain, sciatica, or neurogenic claudication. The scans were interpreted independently by three neuro-radiologists who had no knowledge about the presence or absence of clinical symptoms in the subjects. About one-third of the subjects were found to have a substantial abnormality. Of those who were less than sixty years old, 20 per cent had a herniated nucleus pulposus and one had spinal stenosis. In the group that was sixty years old or older, the findings were abnormal on about 57 per cent of the scans: 36 per cent of the subjects had a herniated nucleus pulposus and 21 per cent had spinal stenosis. There was degeneration or bulging of a disc at at least one lumbar level in 35 per cent of the subjects between twenty and thirty-nine years old and in all but one of the sixty to eighty-year-old subjects. In view of these findings in asymptomatic subjects, we concluded that abnormalities on magnetic resonance images must be strictly correlated with age and any clinical signs and symptoms before operative treatment is contemplated.

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.

Clinical-Radiological Correlation in Cerebral Venous Occlusive Disease

Abstract The clinical and radiological findings in 10 patients with cerebral venous occlusive disease are reported. Headache, confusion, and signs of increased intracranial pressure were the primary findings. Angiographic observations included nonvisualization of the dural sinuses, prolonged arteriovenous circulation time, dilated dural and venous collateral channels, and reversal of collateral flow. In such cases, retrograde jugular venography may show obstruction of the sinuses and intraluminal thrombus formation, confirming the diagnosis. The demonstration of angiographically nonvisualized unusual venous collaterals is also possible by this technique.

Angiography in Cerebral Infarction

The diagnosis of cerebral infarction by angiography is based on a variety of findings, involving both anatomical and pathophysiological considerations. These findings at the time of angiography are dependent upon the type of infarction that we are dealing with (hemorrhagic versus nonhemorrhagic), its location, and the time interval between the onset of symptoms and the performance of the angiographic procedure. Rapid serial angiography is indispensable in the study of cerebral infarction. Most patients are never referred to the Department of Radiology for cerebral angiography, but the number seen has increased of late because of the importance given to possible correctible lesions in the extracranial vessels. Other cases are referred because a hemorrhagic infarction requiring surgical intervention is suspected or because the diagnosis of cerebral infarction cannot be made with certainty on clinical grounds. Because of our desire to arrive at an accurate diagnosis and because the morbidity of the procedure...

Radiological evaluation of temporal artery--middle cerebral artery anastomosis.

Nineteen patients were studied angiographically following transcranial temporal artery—middle cerebral artery anastomosis surgery. All anastomoses remained patent up to 27 months. Flow patterns varied from filling of the entire middle cerebral triangle via the anastomosis to filling of one or two branches. Clinical improvement varied inversely with the degree of middle cerebral artery filling via the shunt. Best results occurred in patients having repeated transient ischemic attacks without a fixed neurologic deficit. On a second postoperative study 2 of 5 patients showed increased flow via the anastomosis. This procedure may be prophylactic in preventing massive cerebral infarction in progressive arterial disease.

Potential artifacts associated with the scanning pattern of the EMI scanner.

Physical and geometrical considerations of the EMI scanner are used to predict that regions of the head can be missed by adopting a scanner procedure based on the nominal EMI slice thickness. Using a nominal slice thickness of 1.3 cm and effective focal spot length of 12 mm, one can predict that in the central portion of the head, up to 8% of the region scanned may not be imaged. Moreover, it is shown that simultaneous monitoring of a single focal spot by two adjacent detectors, as in the EMI system, would lead to significant overlap between the two adjacent EMI slices resulting in dual imaging. Experimental examples are shown to illustrate these two artifacts in the EMI scanner.

Development of a Phantom for Evaluation and Assurance Of Image Quality in CT Scanning

The development and use of a phantom for evaluation, comparison, and quality assurance of CT scanners will be discussed. Examples of measurements on seven CT scanners using early prototypes of the phantom will be presented along with measurements on several scanners using the final phantom configuration. The phantom contains four modular sections which are removable to allow for future fabrication and replacement of individual sections for specialized applications. Section I is used to measure contrast sensitivity and scan slice geometry of the system. Section II is used to measure the sensitometric response of the system. Section III is used to determine the spatial resolution of the system at various contrast levels. Section IV is used to determine the noise, spatial uniformity, alignment, and MTF of the system. In addition, it contains a part with fittings where items may be placed such as in vitro samples, dosimeters, or a motion phantom.

Ct Appearance of Candida Diskitis

Two cases of a rare entity, Candida diskitis. are reported with presentation of plain film and CT findings. Guidelines for diagnosis and treatment are reviewed.

Computerized tomography in the evaluation of pituitary adenomas.

Computerized tomography during the past few years has been unequivocally been proven to be of extreme value in the evaluation of intracranial disease. Despite earlier reports, accuracy of diagnosis in the area of the sella turcica is found to be high despite the close proximity of both bony and air-containing structures. Correlation between computed tomographic images, angiography and pneumoencephalography has been performed and demonstrates that CT scans with a low margin of erro depict the relationships of pituitary adenomas to the surrounding brain parenchyma. The continued importance of angiography, and to some degree pneumoencephalography, in the diagnosis of pituitary tumors is discussed.

Digital subtraction angiography and dynamic computed tomography in the evaluation of arteriovenous malformations and hemangioblastomas of the spinal cord.

Digital subtraction angiography (DSA) and dynamic computed tomography (DCT) were used in the evaluation of five patients with surgically approachable vascular lesions of the spinal cord, including three arteriovenous malformations (AVM), one hemangioblastoma, and one lesion with a questionable radiographic-surgical diagnosis (AVM? hemangioblastoma?). Digital subtraction angiography was positive in three of the five cases and was particularly informative in the patient with hemangioblastoma, even vis a vis arteriography, which is considered the definitive diagnostic test for these lesions. Dynamic computed tomography was positive in four of the five cases. From this preliminary study, DSA and DCT appear to be useful screening and follow-up procedures which, in a number of aspects, complement each other.