Cervical carotid MR angiography with multiple overlapping thin-slab acquisition: comparison with conventional angiography.

OBJECTIVE: Multiple overlapping thin-slab acquisition (MOTSA) is a hybrid time-of-flight MR angiography technique that combines the advantages of two- and three-dimensional methods. A venetian blind-like artifact, resulting from variations in signal intensity at slab boundaries, is a potentially significant disadvantage. The objective of this study was to determine the accuracy of MOTSA MR angiography for the measurement of stenosis and to evaluate the effectiveness of modifications to reduce the venetian blind artifact. SUBJECTS AND METHODS: Fifty-one consecutive patients undergoing conventional and MR angiography of the carotid arteries for suspected atherosclerotic disease were studied. Methods established in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) were used to measure stenosis. Measurements from the conventional angiograms were compared with those from the MR angiograms. Modifications of the MR angiographic technique that were instituted after the initial 26 patients to reduce the venetian blind artifact included new acquisition parameters and the use of a postprocessing algorithm. RESULTS: After modification, highly significant improvements in Spearman ranked correlation coefficients were observed for MR angiography interobserver comparison (.573 to .974, p < .001) and comparison of conventional and MR angiography (.774 to .949, p < .001). A corresponding reduction was observed in the standard deviation of the difference measurement for percent stenosis for both interobserver (34.5% to 11.7%, p < .001) and intertechnique (22.6% to 12.6%, p < .001) comparisons. In the postmodification group, the interobserver correlation coefficients for conventional and MR angiography were not significantly different (.969 vs .974). The areas under the receiver-operating-characteristic curves used to predict surgically significant disease for the premodification and postmodification groups were 0.79 and 0.98, respectively, for observer A and 0.85 and 0.95, respectively, for observer B. CONCLUSION: Improved acquisition parameters and postprocessing significantly reduce the severity of the venetian blind artifact and increase the accuracy of MOTSA MR angiography in the measurement of percent stenosis. With these improvements, MOTSA MR angiography shows promise for noninvasive evaluation of stenosis of the carotid arteries.

Cerebral MR angiography with multiple overlapping thin slab acquisition. Part II. Early clinical experience.

In a prospective, multicenter study of 164 patients, cerebral magnetic resonance (MR) angiography with multiple overlapping thin slab acquisition was evaluated for image quality and diagnostic accuracy. Of the 164 patients, 87 (53%) underwent either correlative cut-film angiography or surgery. The overall image quality was excellent in 90% of patient studies. Eighteen of 19 aneurysms were detected with MR angiography. The parent artery, the anatomy of the neck and dome, and the size were correctly shown in 17 of the 19 aneurysms. All 19 vascular malformations were seen with MR angiography. Venous malformations and single pedicle arteriovenous malformations were completely defined with MR angiography, while complete definition of complex arteriovenous malformations was frequently difficult. In cerebral tumors, the arteries and veins important in surgical planning were accurately shown in all cases. In ischemic cerebrovascular disease, MR angiography depicted all stenoses and occlusions of first- and second-order cerebral arteries. The inability to depict intraluminal filling defects in any but the large central arteries limited the ability of MR angiography to enable the specific diagnosis of embolic stroke.

Coaxial needles for repeated biopsy sampling.

A set of coaxial biopsy needles permits repeated tissue samples through an outer, larger needle that remains in place. The tract can be dilated from 23 to 16 gauge with the use of transfer rods, without loss of the initial position. The technique has been used successfully in six patients.

A light-guidance system to be used for CT-guided biopsy.

We describe a light-guidance system that uses intersecting helium-neon laser beams to provide precise guidance for biopsy approaches from any direction (including compound angles) during CT-guided biopsy of the chest and abdomen. Interactive software provides visualization of the proposed path, indicates the segment of that path that will pass through each section, and displays the settings for the apparatus.

CT detection of occult pneumothorax in head trauma.

A prospective evaluation for occult pneumothorax was performed in 25 consecutive patients with serious head trauma by combining a limited chest CT examination with the emergency head CT examination. Of 21 pneumothoraces present in 15 patients, 11 (52%) were found only by chest CT and were not identified clinically or by supine chest radiograph. Because of pending therapeutic measures, chest tubes were placed in nine of the 11 occult pneumothoraces, regardless of the volume. Chest CT proved itself as the most sensitive method for detection of occult pneumothorax, permitting early chest tube placement to prevent transition to a tension pneumothorax during subsequent mechanical ventilation or emergency surgery under general anesthesia.

Lumbar spine: pretest predictability of CT findings.

Demographic and symptomatic data gathered from 460 patients referred for lumbosacral CT examinations were analyzed to determine if the prescan probability of normal or abnormal findings could be predicted accurately. We were unable to predict the presence of herniated disk on the basis of patient-supplied data alone. Age was the single most significant predictor of an abnormality and was sharply related to degenerative disease and spinal stenosis.

Percutaneous catheter drainage in intraabdominal fluid collections including infected biliary ducts and gallbladders.

Sixty-five abscesses, including 6 infected biliary systems and 15 sterile fluid collections, were treated by percutaneous catheter drainage in 77 febrile patients who were evaluated by computerized tomography or ultrasonography of intraabdominal infection. Percutaneous catheter drainage and systemic antibiotic administration without surgery provided satisfactory control of infection in 52 of 65 abscesses (80 percent). Catheter drainage followed by surgical exploration for abscess control was performed in an additional 5 of 65 abscesses (7 percent). Nine death (14 percent) occurred in the abscess group of 64 patients. In 15 patients, aspirations, Gram stain, and culture of the abnormal fluid collection revealed sterile fluid. Drainage with a single catheter allowed complete resolution in 14 of 15 sterile collections. Surgery was performed electively in one patient with a fistula from a pancreatic pseudocyst in the small bowel. No deaths occurred in the noninfected group of 15 patients, 2 of whom underwent drainage of coexisting abscesses.

Cerebral arterial spasm: part 10. Reversal of acute and chronic spasm in dogs with orally administered nifedipine.

In vivo experiments in dogs demonstrated angiographically that the subarachnoid injection of blood produced cerebral arterial apasm both immediately after the injection of blood and 2 days later. The sublingual adminstration of nifedipine reversed both the acute and the delayed cerebral arterial spasm. In addition, sublingual administration of nifedipine 20 minutes before the subarachnoid injection of blood prevented the acute spasm.

Efficacy of computed tomography of the head in changing patient care and health costs: a retrospective study.

Detailed analysis of all neurologic and neurosurgical admissions at Johns Hopkins Hospital for 6 months prior to the second 6 months after installation of a CT head scanner was undertaken in an attempt to identify the effect CT had on health care decisions, costs, and morbidity. Data showed decreased cost of more than $2,000 per patient and shorter length of stay by 7 days in patients with extracerebral collections, and more than $2,500 and 8 days reduction in patients with tumors after CT was in use. A group matched by computer for age, diagnosis, and physician showed decreased costs of more than $2,000 and shortened stay by more than 3 days per hospitalization. Increased costs were shown in patients with cerebrovascular disease after CT. Change in method of workup with fewer invasive studies for all patients (P less than .001) and significant increases in cost of diagnostic workup were demonstrated (P less than .001). There was no change in morbidity and mortality between the two groups. These data suggest that CT of the head may reduce cost and length of hospitalization in certain patient groups and frequently alters patient workup.

Neuroradiological manifestations of intracranial sarcoidosis.

Six cases of sarcoidosis involving the central nervous system are reported with the neuroradiological findings and appearance on computed tomography. Communicating hydrocephalus with sarcoid arachnoiditis is the most common finding, but arteritis and masses have also been reported. Two rare cases of intracerebral masses are included. The radiological findings and clinical histories are reviewed with emphasis on the use of CT and complete neuroradiological studies for patients with possible central nervous system sarcoidosis.

Cranial chondrosarcomas. Report of four cases and review of the literature.

Four cases of chondrosarcoma of the skull are presented. The clinical and radiographic features and differential diagnosis are discussed. The previous literature is reviewed and all cases tabulated. Computed tomography and angiography are important radiologic tools in suggesting the correct diagnosis prior to operation. Stippled, finely speckled, or amorphous calcification or bony erosion on radiographic studies and an avascular mass angiographically may suggest the diagnosis.

The production of cerebrospinal fluid in experimental communicating hydrocephalus.

Utilizing an atraumatic model to produce chronic hydrocephalus, CSF production was measured during and after development of communicatin hydrocephalus. CSF volume production was significantly lower in animals with increased pressure. Animals with chronic hydrocephalus and normal pressures had abnormal CSF production. Diminished CSF production appears to offer a potential compensatory mechanism when CSF absorption is altered.