Biomedical subjects
S A Kieffer
Publications and source records attributed to S A Kieffer.
Gadopentetate dimeglumine: observations on the clinical research process.
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Recurrent postdiskectomy low back pain: MR-surgical correlation.
The preoperative MR findings in 11 patients, all of whom had developed recurrent low back pain after surgery for herniated lumbar intervertebral disk, were correlated with the surgical findings to determine possible criteria for distinguishing recurrent disk herniation from postoperative scar (extradural fibrosis). The preoperative MR findings agreed with the surgical findings in seven of eight patients with recurrent disk herniation and in six of nine individuals with extradural fibrosis. The most important parameters in differentiating recurrent herniated disk from extradural scar were the configuration and margination of the extradural mass rather than its signal characteristics. The most reliable MR sign for recurrent herniated disk was the presence of a sharply marginated focal polypoid disk protrusion beyond the posterior margins of the adjacent vertebral bodies shown to best advantage on sagittal T1- and T2-weighted and axial T1-weighted spin-echo MR images. Disk herniations usually maintained isointensity with the intervertebral disk of origin, while extradural fibrosis exhibited variable signal intensity. The preoperative diagnosis of extradural fibrosis on MR was based primarily on its irregular configuration and extension. This study suggests that preoperative differentiation between scar and recurrent herniated disk is possible with MR when morphology and topography are considered in addition to signal intensity.
Spontaneous dissection of the cervical internal carotid artery: correlation of arteriography, CT, and pathology.
Spontaneous dissection of the internal carotid artery is being recognized as a more frequent cause of acute neurologic deficit, particularly in young persons. Saccular pseudoaneurysm formation may be an associated finding, especially in the presence of tortuosity (coiling) of the cervical internal carotid artery. Of eight patients with nine vessels demonstrating internal carotid artery dissection on arteriography, pseudoaneurysms were found in five arteries. Four of the five pseudoaneurysms occurred in tortuous (coiled) arterial segments. Thin-section contrast-enhanced dynamic incremental CT showed close agreement with the findings on selective arteriography and provided additional information on the presence and configuration of arterial wall thickening as well as the extent of the pseudoaneurysm. Our experience indicates that CT may play an important role in the diagnosis, management, and follow-up of this lesion.
Recurrent post-discectomy pain. CT--surgical correlation.
Diagnostic evaluation of the patient with recurrent lumbosacral radiculopathy following lumbar laminectomy and discectomy represents a difficult task for the radiologist. Neither non-enhanced CT nor myelography have permitted reliable differentiation between postoperative extradural fibrosis (scarring) and recurrent disc herniation. However, CT following intravenous contrast infusion has been reported by several investigators to allow differentiation of these two entities. A series of 13 patients is reported with correlation between the findings on postcontrast CT and at reoperation. In 5 patients who exhibited variable contrast enhancement of an extradural soft tissue mass without a discreet lucent component on postcontrast CT, operative reexploration revealed only scar tissue. In 8 patients in whom postcontrast CT demonstrated a discreet non-enhancing extradural mass (partially surrounded by a thin enhancing rim of soft tissue in all but one), recurrent disc herniation together with an overlying band of scar was found and resected at reoperation. The strong positive correlation between CT and operative findings in this series suggests that postcontrast CT may well prove to be a reliable method for preoperative differentiation of recurrent disc herniation from extradural scarring.
Atheromatous extracranial carotid arteries: CT evaluation correlated with arteriography and pathologic examination.
Dynamic, rapid sequence, axial computed tomography (CT) was employed to evaluate the extracranial common and internal carotid arteries in 17 patients with clinical histories suggesting recent or remote ischemia in the territory supplied by the internal carotid artery. The CT findings were correlated with arteriographic observations and with gross and histologic evaluations of endarterectomy specimens. Areas of arterial wall thickening were evaluated on CT scans with regard to both degree of thickening and radiographic density (attenuation). The degree of vessel wall thickening secondary to atheromatous plaque demonstrated on CT scans corresponded closely to the severity of luminal compromise seen on arteriograms. Isodense or mildly hypodense focal mural thickening noted on CT scans of seven endarterectomy specimens proved to be primarily fibrotic (simple) atheromatous plaque on gross and histologic examination. Areas of markedly lucent focal mural thickening on CT scans of 11 specimens all demonstrated varying amounts of subintimal hemorrhage within loosely arranged and rather acellular (complex) atheromatous plaques on pathologic examination. While arteriography provides information regarding the status of the arterial lumen, CT offers the potential of accurate characterization of pathologic changes in the wall of the extracranial carotid arteries in patients with symptoms of cerebral ischemia.
Radiologic-pathologic correlation conference: SUNY Upstate Medical Center. Late deterioration after treatment of brain neoplasm.
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The radiological diagnosis of herniated lumbar intervertebral disk. A current controversy.
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Lumbar myelography with iohexol and metrizamide: a comparative multicenter prospective study.
Diagnostic quality of radiographs and adverse reactions associated with the use of metrizamide and iohexol as contrast agents in lumbar myelography were compared in a prospective randomized double blind study in 350 patients at seven centers. The contrast media were administered in comparable volumes at a concentration of 180 mg I per ml. Overall quality of radiographic visualization was graded good or excellent in 95% of 175 metrizamide studies and in 98% of 175 iohexol studies. Ninety-three patients examined using metrizamide (53%) and 130 patients examined using iohexol (74%) experienced no discomfort during or after myelography. Postmyelographic headache was associated with 38% of metrizamide examinations and 21% of iohexol examinations. Nausea and vomiting were also more common with metrizamide. Five patients examined using metrizamide (3%) experienced transient confusion and disorientation following lumbar myelography. No such reactions were observed following iohexol myelography.
Iopamidol and metrizamide for myelography: prospective double-blind clinical trial.
In a comparative randomized double-blind study, 73 patients underwent myelography using iopamidol (36 patients) or metrizamide (37 patients) as contrast medium. The overall diagnostic adequacy of iopamidol myelography was found to be comparable to that of metrizamide myelography. The incidence of examinations graded as superior (64%) or adequate (36%) with iopamidol was equivalent to that with metrizamide (57% superior, 43% adequate). Adverse reactions after iopamidol myelography were fewer, less severe, and generally of shorter duration than those associated with metrizamide. In the iopamidol group, adverse reactions occurred in nine (25%) patients, all of whom experienced mild or moderate headache, one with nausea, vomiting, and fatigue. In the metrizamide group, adverse reactions occurred in 17 (46%) patients, all of whom experienced mild or moderate headache, six with nausea and vomiting and four with back and leg pain. Of nine individuals who underwent myelography using 300 mg 1/ml metrizamide injected via lateral C1-C2 puncture, three experienced a toxic encephalopathy with confusion, dysphasia, headache, nausea, and vomiting, and a fourth individual suffered severe nausea, vomiting, fever, and irregular pulse. Encephalopathy was not observed in any of the 11 patients in whom myelography was performed via lateral C1-C2 puncture with a similar concentration of iopamidol. No seizures were encountered, and no clinically significant changes in laboratory studies were observed with either contrast medium.
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.
Multifocal glioblastoma: diagnostic implications.
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Bulging lumbar intervertebral disk: myelographic differentiation from herniated disk with nerve root compression.
Deformities of the margins of the contrast material-filled lumbar thecal sac are common findings at myelography in patients with low back pain, but not all such deformities are due to herniated disks. Differentiation at Amipaque myelography between a diffusely bulging disk (unlikely to cause nerve root compression) and a herniated disk (which typically causes nerve root compression) is based on the curvature and extent of the extradural deformity of the anterolateral margin of the contrast-filled sac and on the presence of fusiform widening of the most distal part of the affected nerve root. The deformity caused by a bulging disk is rounded, usually symmetrical (although occasionally more prominent on one side), and does not extend above or below the disk space; the nerve root is uniform in caliber and normal in size. The deformity caused by a herniated disk is angular and extends cephalad and/or caudal to the level of the disk space; the affected nerve root is usually widened in its most distal visible part. A consecutive series of 33 patients with clinically suspected lumbar disk herniation and no previous history of back surgery underwent laminectomy. Using the criteria listed above for differentiation of bulging from herniated disk on Amipaque myelography, the myelographic diagnosis was correct in all six operatively confirmed bulging disks and in 26 (96%) of 27 operatively verified disk herniations.
Applications and limitations of computed tomography of the spine.
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Quantitative assessment of the lumbar spinal canal by computed tomography.
An experimentally validated simple standardized method for making precise measurements of the spinal canal directly from the video display of a CT scanner is described. Using this method, normal values for anteroposterior diameter, interpediculate distance, and cross-sectional area of the lumbar spinal canal have been determined in a series of 60 adults. A careful study of canal configuration combined with the prudent use of the normal values should allow the CT diagnosis of lumbar spinal stenosis to be made with a high level of confidence.
CT of facet distraction in flexion injuries of the thoracolumbar spine: the "naked" facet.
Vertical distraction of the articular processes is an important sign of ligamentous disruption due to flexion injuries of the thoracolumbar spine. In addition to illustrating this finding in cross section (the "naked" facet), computed tomography in the transaxial plane allows assessment of the presence and position of fracture fragments that may encroach on the spinal canal. Image reconstruction in sagittal and coronal planes provides a clear demonstration of the degree of bony compression, facet distraction, and kyphosis associated with flexion injuries without additional patient manipulation or radiation exposure.
Computed tomography in genitourinary pathology.
Computed tomography (CT) provides accurate localization of pathologic processes within the abdomen and also frequently contributes information regarding the nature of the process. A review of 50 patients with suspected genitourinary pathology studied with CT suggests that this new noninvasive diagnostic modality can provide increased diagnostic accuracy but that it will not replace conventional abdominal radiography and intravenous urography as the primary screening examination for such patients. Situations in which CT has proved valuable include: (1) evaluation of areas which are relatively "blind" on conventional radiography: anterior and posterior margins of kidneys, paravertebral and midline portions of retroperitoneum, and base of bladder; (2) evaluation of patients with severely compromised function of one or both kidneys, including assessment of amount of functioning renal parenchyma and possible demonstration of cause of obstructive hydronephrosis; (3) evaluation of patients in whom intravenous urography is contraindicated; (4) differentiation of solid from cystic masses of kidney; (5) evaluation of spread of tumor outside boundaries of kidney; and (6) staging of bladder tumors.
Intradural herniation of lumbar intervertebral discs.
A case of intradural rupture of a lumbar intervertebral disc is reported, and the literature is reviewed. The majority of intradural disc herniations occur at the L4--5 level. These patients usually have neurologic deficits more severe than those found in the much more common extradural disc herniations. The myelographic picture varies from an irregularly marginated intradural lesion overlying the disc space to a complete block. The common factor allowing intradural disc herniation is probably dense adhesions between the dura and the posterior longitudinal ligament, preventing the more common lateral extradural disc herniation. Intradural disc herniation should be included in the differential diagnosis of lumbar intradural lesions causing nerve root or cauda equina compression.