Disk-caused nerve compression in patients with acute low-back pain: diagnosis with MR, CT myelography, and plain CT.

Ninety-five patients with acute low-back and radicular pain underwent magnetic resonance (MR) imaging and either plain computed tomography (CT) (n = 32) or CT myelography (n = 63) for diagnosis of herniated nucleus pulposus-caused nerve compression (HNPNC). Patients were followed up for at least 6-12 months. Fifty-six patients underwent surgery, and 39 received conservative treatment. Receiver operating characteristic (ROC) analysis was performed on correlation of results of blinded image reading with "true" diagnoses determined by an expert panel [corrected]. Results in subgroup analysis for ROC curve areas were MR, 0.84, versus plain CT, 0.86; MR, 0.81, versus CT myelography, 0.83; and MR, 0.82, versus findings with both CT techniques, 0.85. Results indicate no statistically significant difference in diagnostic accuracy of HNPNC among the three modalities. Thus, factors of cost, radiation dose, and invasiveness influence selection of modality. On the basis of accuracy findings, the authors suggest that MR should replace CT myelography because of the invasiveness of myelography but that MR should not replace plain CT because plain CT is equally accurate and much less costly.

Experimental and human brain neoplasms: detection with in vivo sodium MR imaging.

Elevations of intracellular sodium concentration have been observed in rapidly proliferating cells and malignant neoplasms. Sodium magnetic resonance (MR) imaging (with repetition times of 133 msec and echo times of 13, 26, 39, and 42 msec) was performed in ten patients and three dogs with central nervous system neoplasms. In all instances the neoplasms were associated with an increased sodium signal compared with that of normal brain. Unfortunately, the available echo times did not enable discrimination of intracellular sodium from extracellular sodium, which was present in high concentrations in adjacent vasogenic edema fluid. Further study is necessary to establish the utility of sodium MR imaging for the investigation of malignant neoplasms.

Cerebellopontine angle-petromastoid mass lesions: comparative study of diagnosis with MR imaging and CT.

Capabilities of computed tomography (CT) and magnetic resonance (MR) imaging in the diagnosis of cerebellopontine angle-petromastoid (CPA-PM) lesions were compared in 75 patients. CT and MR demonstrated 95.8% and 98.7% of the lesions, respectively. MR was often more helpful for characterization of neuromas, epidermoid cysts, exophytic gliomas, and vascular lesions, while CT was usually more informative for meningiomas, metastases, and tympanomastoid cholesteatomas. A specific diagnosis could be made with MR for most types of lesions through use of relaxation parameters and characteristic morphologic changes. Size, shape, location, and contour of the lesions, however, were generally more helpful for differential diagnosis than relaxation times. With the exception of metastatic lesions, cholesteatomas, and some meningiomas, MR was usually more helpful than CT in defining the full extent of the lesions and their relationships to contiguous structures. MR, because of its high accuracy in lesion detection, characterization, and localization, is a suitable primary diagnostic modality for evaluating patients with suspected CPA-PM lesions.

Clinical and experimental vasogenic edema: in vivo sodium MR imaging. Work in progress.

To investigate the sodium magnetic resonance (MR) imaging characteristics of acute vasogenic edema, an experimental canine model was developed. Vasogenic edema was produced in the hemisphere of the dogs by the intraarterial infusion of hypertonic mannitol (25%). This solution opens the blood-brain barrier, allowing the influx of water, electrolytes, and proteins into the brain. The main advantage of this model over the established "cold injury" model is the lack of associated brain necrosis. Two patients with chronic vasogenic edema secondary to well-circumscribed meningiomas also underwent MR imaging. The sodium signal was markedly elevated in both clinical and experimental studies of vasogenic edema fluid compared with signal in healthy brain tissue. Extracellular sodium associated with vasogenic edema displayed MR imaging characteristics similar to that of sodium in serum. There was a trend toward a shortened T2 in edema fluid secondary to the presence of serum macromolecules.

Iotrol versus metrizamide in lumbar myelography: a double-blind study.

In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.

Clivus epidural hematoma: a case report.

An acute traumatic epidural hematoma extending from the odontoid process to the dorsum sella is described. The mechanism for the formation of an extradural hematoma in this unusual location seems to be related to age and a severe hyperflexion injury.

The spectrum of multiple sclerosis lesions using a multiple spin echo pulse sequence and a high field strength.

Seventy-one patients having clinical laboratory findings consistent with multiple sclerosis (MS) were imaged with a 1.5 tesla MR instrument using multiple spin echo sequences (TR = 2,000 ms and TE = 30, 60, 90, 120 ms). Multiple spin echo is a sensitive method for detecting MS lesions. Sixty-seven patients (94%) demonstrated lesions consistent with MS. With the exception of those located in the cortex, optic nerve and chiasm the lesions detected correlated with pathologic data. Lesions of the cerebral hemispheres, corpus callosum and cerebellum were generally multiple while lesions of the brain stem and optic tracts were generally singular. The majority of the lesions were associated with the white matter tracts of the cerebral hemispheres and brain stem.

Iohexol for cervical myelography via C1-C2 puncture: study of efficacy and adverse reactions.

Cervical myelography with iohexol via C1-C2 puncture was performed in 30 patients in two medical centers using a concentration of 240 mg l/ml. The study demonstrated iohexol to be a safe contrast medium without significant changes in neurologic and physical examination, vital signs, electrocardiogram, or hematologic or blood chemistry parameters. Fifteen patients had electroencephalograms (EEGs); two were abnormal. In one patient the baseline EEG demonstrated nonspecific slow waves in the temporal regions bilaterally that remained unchanged after myelography. In the second patient, transient changes in the left hemisphere during either hyperventilation or photic stimulation on postmyelographic EEG had not been present on the baseline recording. The relation of these changes to the drug remains unclear. Iohexol was found to be an efficacious myelographic contrast agent, with good to excellent myelograms in 93% of cases. Headache occurred in 13% and nausea in 3%.

Chymopapain chemonucleolysis: correlation of diagnostic radiographic factors and clinical outcome.

The therapeutic response to treatment of lumbar disk herniation with chymopapain chemonucleolysis is significantly influenced by the criteria used for patient selection. Although careful clinical selection of patients reduces the frequency of treatment failure, some patients do not achieve satisfactory relief of pain with chemonucleolysis. In an attempt to identify objective pretreatment radiographic findings that might refine selection criteria and further reduce the failure rate of chemonucleolysis, a retrospective correlation of pretreatment radiographs and clinical responses was made of 200 consecutive chemonucleolysis patients. Marked improvement in sciatica occurred in 79.9% and 79.3% of patients at early and late follow-up, respectively. There was a significantly higher response rate, however, in patients who had definite radiographic evidence of focal disk herniation and in those patients with definite radiographic evidence of nerve-root compression (marked nerve-root deviation, nerve-root flattening or edema, root-sleeve amputation) by disk material. Those patients with a preinjection disk height greater than the mean had a slightly better response rate (91.1%) than those whose disk height was smaller than the mean (80.0%). Most cases of treatment failure could be attributed to an incorrect radiographic diagnosis, treatment of patients with equivocal diagnostic studies, the presence of "free" disk fragments, and causes of nerve-root compression unresponsive to chymopapain.

Chymopapain chemonucleolysis: CT changes after treatment.

Chymopapain chemonucleolysis is now used extensively in this country to treat lumbar disk herniation. Despite increasing experience in patient selection, there continue to be patients who do not respond to treatment and require diagnostic reevaluation. Interpretation of postchemonucleolysis computed tomographic (CT) scans in these patients requires a knowledge of the CT changes that normally occur after treatment with chemonucleolysis. To define these temporal changes, a prospective CT evaluation was performed of 29 treated interspaces in 26 patients who returned for routine postchemonucleolysis follow-up. Despite a successful clinical response in 17 of 21 patients, changes in the size, location, shape, homogeneity, and density of the disk herniation were uncommon at the 6 week follow-up. In 24 treated interspaces, the most common changes at 6 week CT follow-up were the development of vacuum phenomenon in three (12.5%) and a slight decrease in the size of two (8.3%) disk herniations. A successful response was noted in 17 of 21 patients scanned at 6 month follow-up, with five (22.7%) of 22 injected interspaces exhibiting vacuum phenomenon and 13 (59.1%) interspaces showing an observable decrease in the size of the disk herniation. Early improvement of sciatica after chemonucleolysis often occurs without a change in the size of the disk herniation and may be mediated by chymopapain-induced disk-space narrowing. Continued improvement may be accompanied by both a decrease in the disk height and a reduction in the size of the disk protrusion.

Comparison of ultrasound and IV-DSA for carotid evaluation.

Sixty carotid bifurcations in 34 symptomatic patients were examined prospectively with ultrasound (continuous wave Doppler and high resolution, B-mode imaging) and intravenous digital subtraction angiography (IV-DSA). The overall quality of examination was better with DSA than with ultrasound. Imaging of the external carotid artery was particularly difficult with sonography. For evaluation of the common and internal carotid arteries, eight percent of IV-DSA studies were poor or inadequate as compared with 12% for B-mode imaging. Overall for detection of atherosclerotic plaque, high resolution B-mode sonography was 84% sensitive and DSA 81% sensitive. When only the common and internal carotid arteries were considered, the sensitivity of high resolution sonography improved to 93% and the sensitivity of IV-DSA increased to 86%. Ultrasound (combined high resolution, B-mode sonography and CW Doppler) correctly identified all six internal carotid occlusions in the series. While IV-DSA correctly identified five of the six occlusions, the sensitivity for detection of lesions causing 70% or more stenosis was 95% for both ultrasound and IV-DSA. Sensitivity for 50% or greater obstruction was 79% for ultrasound and 85% for IV-DSA. Ultrasound sensitivity for greater than 50.9% stenoses rose to 87% when only the common and internal carotid were considered while IV-DSA sensitivity remained at 85%. Specificity was good at all levels of obstruction. It may be concluded from this study that the accuracy of ultrasound and IV-DSA are quite similar for evaluation of the carotid bifurcation and that either test is a satisfactory screening method for carotid bifurcation atheromatous disease.

Digital subtraction angiography. Comparison of meglumine-Na diatrizoate with iohexol.

A slight improvement in image quality occurred with the use of iohexol when compared with meglumine-Na diatrizoate. There is less swallowing with iohexol, which gives better image registration when looking at the extracranial carotid arteries. A single significant tachycardia occurred with the ionic medium, but not with iohexol. Overall discomfort and minor adverse reactions were less with iohexol than with diatrizoate.

Correlation of high-resolution, B-mode and continuous-wave Doppler sonography with arteriography in the diagnosis of carotid stenosis.

One hundred thirty-one carotid bifurcations in 73 symptomatic patients were prospectively studied with high-resolution, B-mode sonography (HRS) and continuous-wave Doppler ultrasound (CWD). Twenty-three bifurcations were studied because of asymptomatic bruits, 30 for transient ischemic attacks, and 36 for focal or nonfocal symptoms or signs suggesting occlusive disease. The remaining 42 bifurcations were asymptomatic, with symptoms or signs confined to the contralateral bifurcation. Findings in the common, external, and internal carotid arteries (total, 393 vessels) were tabulated separately for plaque severity (HRS), ulceration (HRS), and degree of occlusion (HRS and CWD). HRS correctly estimated plaque severity in 67% of vessels, with 13% overestimated and 20% underestimated. HRS was only 44% sensitive for detection of 81 angiographically demonstrated ulcers. Among 187 occlusive lesions (ranges, less than 50%, greater than or equal to 50%, less than 70%, greater than or equal to 70% decrease in diameter or complete occlusion) HRS correctly estimated luminal narrowing in 62%, CWD in 30%, and HRS plus CWD in 70%. Among greater than 50% occlusive lesions, HRS was correct in 48%, CWD in 59%, and HRS plus CWD in 69%. These results suggest that (a) HRS is not accurate for diagnosis of ulceration, (b) Doppler and B-mode combined are more accurate than separate use of either procedure for evaluation of occlusive lesions, and (c) the level of accuracy in evaluating plaque and stenosis provides a general estimation of severity of disease but does not allow for precise diagnosis.

Work in progress: hybrid temporal-energy subtraction in digital fluoroscopy.

Initial clinical results using a digital fluoroscopic implementation of the combined time-energy ("hybrid") subtraction technique are described, with emphasis on carotid and renal imaging. Where patient motion artifacts are due to soft-tissue motion alone, hybrid subtraction can remove them. Due to the need for a finite separation time between high- and low-energy pairs, however, the present implementation of the hybrid technique is not completely immune to soft-tissue motion. The intrinsic signal-to-noise ratio of hybrid imaging is less than that of conventional temporal subtraction. However, since the low-energy temporal subtraction images are included in the hybrid data set, the diagnostic quality of the examination is not compromised.