Emerging impact of CTA/perfusion CT on acute stroke thrombolysis in a community hospital.

Our objective was to retrospectively review the emerging role of CT, CTA, and perfusion CT (pCT) in the hyperacute stroke population of a community hospital. We reviewed 50 consecutive patients' records and imaging studies, who were treated with thrombolytic therapy within 6 h of symptom onset. Multidetector CT, CTA, and pCT studies were evaluated. Subsequent CT, magnetic resonance, or angiographic studies when available were correlated. Patients' clinical data at admission and outcomes at discharge were evaluated. Complications were tabulated. Of the 50 patients treated with thrombolytics, 37 had CT/CTA/pCT, the others non-contrast CT only. CT blood volume defect was present in a total of 14 patients, presaging permanent infarct in all. Arterial clot was seen in 28/37 CTAs (carotid "T" 6, MCA 16, vertebrobasilar 6). Viable penumbra was shown in 20/37; rescued penumbra was depicted after treatment in 14. 39 patients were treated with intravenous, nine with intra-arterial, two with both forms of thrombolysis. Modified Rankin score showed clinical improvement in 58%, three patients had complete recovery. Subsequent bleed was shown in two (4%), symptomatic in one (2%). Two patients died. Our experience suggests advanced CT is more sensitive to ischemia than routine CT, that salvageable penumbra can be identified, and that triage of patients with acute stroke for thrombolysis with CT/CTA/pCT is more robust than routine CT alone, and may improve outcomes in the community hospital setting.

Effects of diagnostic information, per se, on patient outcomes in acute radiculopathy and low back pain.

BACKGROUND AND PURPOSE: We conducted a prospective randomized study of patients with acute low back pain and/or radiculopathy to assess the effect of knowledge of diagnostic findings on clinical outcome. The practice of ordering spinal imaging, perhaps unintentionally, includes a large number of patients for whom the imaging test is performed for purposes of reassurance or because of patient expectations. If this rationale is valid, one would expect to see a measurable effect from diagnostic information, per se. MATERIALS AND METHODS: A total of 246 patients with acute (<3 weeks) low back pain (LBP) and/or radiculopathy (150 LBP and 96 radiculopathy patients) were recruited. Patients were randomized using a stratified block design with equal allocation to either the unblinded group (MR imaging results provided within 48 hours) or the blinded group (both patient and physician blinded to MR imaging results.) After the initial MR imaging, patients followed 6 weeks of conservative management. Roland function, visual pain analog, absenteeism, Short Form (SF)-36 Health Status Survey, self-efficacy scores, and Fear Avoidance Questionnaire were completed at presentation; 2, 4, 6, and 8 weeks; and 6, 12, and 24 months. Improvement of Roland score by 50% or more and patient satisfaction assessed by Cherkin symptom satisfaction measure were considered a positive outcome. RESULTS: Clinical outcome at 6 weeks was similar for unblinded and blinded patients. Self-efficacy, fear avoidance beliefs, and the SF-36 subscales were similar over time for blinded and unblinded patients, except for the general health subscale on the SF-36. General health of the blinded group improved more than for the unblinded group (P = .008). CONCLUSIONS: Patient knowledge of imaging findings do not alter outcome and are associated with a lesser sense of well-being.

Low back pain.

The communication between radiologists and their surgical colleagues is particularly important in the setting of back pain. This common disorder often does not have a definable cause, even when the imaging findings are abnormal. A shared understanding of the various causes of back pain, the appropriate terminology, and the needs of the surgeon is vital to proper patient treatment. Unfortunately, little standardization in the terminology for and management of back pain syndromes exists. This article elucidates the approaches to problems of back pain used in one clinical setting.

Interobserver and intraobserver variability in interpretation of lumbar disc abnormalities. A comparison of two nomenclatures.

STUDY DESIGN: A double-blind prospective study was used to measure interobserver and intraobserver variability when interpreting lumbar spine magnetic resonance imaging studies of disc abnormalities. OBJECTIVES: To evaluate reader consistency when interpreting disc extension beyond the interspace, and assess the effect of two distinct nomenclatures on reader consistency. SUMMARY OF BACKGROUND DATA: Interobserver and intraobserver variability in interpretation of lumbar disc abnormalities is an important consideration in analyzing the technical efficacy of an imaging modality. However, this has not been well measured (particularly for standardized nomenclature). METHODS: Magnetic resonance imaging studies of the lumbar spine performed prospectively in 98 asymptomatic volunteers, and an additional 27 selected studies from symptomatic patients, were read blindly by two experienced neuroradiologists, using two separate nomenclatures. Only the discs were evaluated (625 interspaces). Nomenclature I was normal, bulge, herniation. Nomenclature II was normal, bulge, protrusion, extrusion. Intraobserver and interobserver variation were measured with Kappa statistic analysis. RESULTS: Interobserver agreement was 80% for both nomenclatures with a Kappa statistic of 0.58. Intraobserver agreement was 86% for each reader, with a Kappa statistic of 0.71 and 0.69, respectively. The most common disagreement was for normal versus bulge. The next most common disagreement (5-6%) was for bulge versus herniation (or protrusion in Nomenclature II). Herniation was read in 23% of the asymptomatic subjects. Using Nomenclature II, protrusion was seen in 27% of these subjects. Extrusion was read in only two asymptomatic subjects. CONCLUSIONS: Experienced readers using standardized nomenclature showed moderate to substantial agreement with interpreting disc extension beyond the interspace on magnetic resonance imaging.

MRI of degenerative disease of the lumbar spine.

Low back pain (LBP) is one of the most common reasons that patients seek medical attention. Although acute LBP is generally a self-limiting condition, the estimated cost for this health care problem exceeds $8 billion annually. MR accurately depicts both the morphologic as well as biochemical sequelae of disc degeneration. Additionally, MR is superior in its ability to depict disease processes that can present in an indistinguishable fashion. Although multiple mechanisms have been proposed for the possible etiology of disc degeneration, it remains incompletely understood at this time. In addition to the unknown etiology of disc degeneration, the relationship between degenerative disc disease and LBP has not been firmly established. Substantial percentages of people without a history of LBP or sciatica have been shown to have abnormal imaging examinations. Mechanical compression of neural elements by disc herniation, as well as direct biochemical and inflammatory effects of the contents of the nucleus pulposus upon neural structures, have been proposed as possible sources of LBP. Due to the above, caution is urged before attributing a particular anatomic finding as the patient's source of low back pain.

Magnetic resonance imaging of the lumbar spine in people without back pain.

BACKGROUND: The relation between abnormalities in the lumbar spine and low back pain is controversial. We examined the prevalence of abnormal findings on magnetic resonance imaging (MRI) scans of the lumbar spine in people without back pain. METHODS: We performed MRI examinations on 98 asymptomatic people. The scans were read independently by two neuroradiologists who did not know the clinical status of the subjects. To reduce the possibility of bias in interpreting the studies, abnormal MRI scans from 27 people with back pain were mixed randomly with the scans from the asymptomatic people. We used the following standardized terms to classify the five intervertebral disks in the lumbosacral spine: normal, bulge (circumferential symmetric extension of the disk beyond the interspace), protrusion (focal or asymmetric extension of the disk beyond the interspace), and extrusion (more extreme extension of the disk beyond the interspace). Nonintervertebral disk abnormalities, such as facet arthropathy, were also documented. RESULTS: Thirty-six percent of the 98 asymptomatic subjects had normal disks at all levels. With the results of the two readings averaged, 52 percent of the subjects had a bulge at at least one level, 27 percent had a protrusion, and 1 percent had an extrusion. Thirty-eight percent had an abnormality of more than one intervertebral disk. The prevalence of bulges, but not of protrusions, increased with age. The most common nonintervertebral disk abnormalities were Schmorl's nodes (herniation of the disk into the vertebral-body end plate), found in 19 percent of the subjects; annular defects (disruption of the outer fibrous ring of the disk), in 14 percent; and facet arthropathy (degenerative disease of the posterior articular processes of the vertebrae), in 8 percent. The findings were similar in men and women. CONCLUSIONS: On MRI examination of the lumbar spine, many people without back pain have disk bulges or protrusions but not extrusions. Given the high prevalence of these findings and of back pain, the discovery by MRI of bulges or protrusions in people with low back pain may frequently be coincidental.

Three-dimensional MR imaging and display of intracranial disease: improvements with the MP-RAGE sequence and gadolinium.

Three-dimensional (3D) image rendering was performed in 14 patients who had undergone magnetic resonance (MR) imaging for focal brain lesions. The MR study included the magnetization-prepared rapid gradient-echo (MP-RAGE) sequence with 64 or 128 partitions. Resultant contiguous sections 2.5 or 1.25 mm thick, respectively, were obtained. Images were acquired before and after administration of gadopentetate dimeglumine. Resultant 3D data sets were processed on a commercially available workstation. Correlative surgical observation was performed in four cases. All data sets were successfully processed into 3D images. The precontrast images proved superior to gadolinium-enhanced images for brain surface rendering. Postcontrast images proved superior for reconstruction of tumors and vascular structures. The 64-partition data set proved sufficient for all postprocessing. Coronal orientation was preferred to sagittal orientation for surface rendering because it provided optimal orthogonal orientation of sulcal and gyral brain surface features. Three-dimensional rendition allowed easy superposition of lesion, brain, vessels, and scalp features--all useful for surgical planning. The central sulcus was easily recognized in the midline partitions and traced mediolaterally for projection on the cortical surface. MP-RAGE provides a 3D data set that can be obtained in just over 3 minutes, from which clinically useful 3D renderings are possible. The rapidity of acquisition and capability for 3D rendering provides additional clinical utility.

Dissection of cranial arteries in the neck: correlation of MRI and arteriography.

Retrospective correlation of MRI and angiographic findings in nine patients with suspected cervical vascular dissections revealed MRI evidence of vessel abnormalities in eight patients, seven of whom proved to have arterial dissections. One patient whose MRI showed no abnormalities also proved to have a dissection, shown by angiography. Two patients had associated pseudoaneurysms not demonstrated by MRI. Five dissections involved the carotid arteries and three the vertebral arteries. Seven of the nine patients had associated transient neurologic deficits, while two had permanent deficits. Frank infarction of the brain was demonstrated by MRI in five cases. MRI findings suggestive of dissection included: (1) increased signal from the entire vessel; (2) a border of increased signal surrounding the lumen, with luminal narrowing; (3) poor or absent visualization of the vessel; and (4) significant compromise of the vessel lumen by adjacent abnormal increased signal tissue.

Clinical safety and efficacy of gadoteridol: a study in 411 patients with suspected intracranial and spinal disease.

In this phase III study, 411 adult patients with suspected intracranial or spinal disease underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol (gadolinium 1,4,7-tris [carboxymethyl]-10-[2'-hydroxypropyl]-1,4,7,10-tetraazacyclododecane+ ++). MR images were evaluated by a single unblinded reader at each of 27 sites; the diagnosis was confirmed with one of nine imaging or surgical procedures within 8 weeks before or after MR imaging. After injection, no clinically significant changes were noted in laboratory values, physical examination, or vital signs. Adverse clinical events possibly or probably associated with injection of gadoteridol were seen in 18 of 411 patients (4.4%); the most common were dysgeusia and mild nausea, and all abated without residual effects. MR images enhanced with gadoteridol in patients with confirmed disease provided more diagnostic information than unenhanced images in 128 of 175 brain examinations (73.1%) and 93 of 137 spinal examinations (67.9%). A change in diagnosis because of additional information from contrast-enhanced images was considered likely in 63 of 214 cranial and 54 of 161 spinal studies.

Acoustic analysis of gradient-coil noise in MR imaging.

A survey was conducted of acoustic noise levels in magnetic resonance (MR) imaging systems. Static magnetic flux and radio-frequency pulses did not affect the function of shielded sound-pressure detection equipment. Noise levels were measured at bore isocenter during a variety of imaging sequences in six MR imaging systems with magnetic fields of 0.35-1.5 T. Measured noise ranged from 82 to 93 dB on the A-weighted scale and from 84 to 103 dB on the linear scale. Noise levels increased during sequences employing thinner section thickness and shorter repetition and echo times and were independent of field strength. Gradient-coil noise in MR imaging is an annoyance but is well within safety guidelines.

MR imaging in seminal vesiculitis.

Seminal vesicle disorders may be clinically vague owing to the nonspecific nature of the associated signs and symptoms. Thus, the diagnosis of seminal vesicle disease is frequently difficult. Two cases of seminal vesiculitis are presented to illustrate the usefulness of pelvic magnetic resonance imaging in making this difficult diagnosis.

Chordomas: MR imaging.

Twenty histologically verified intracranial and upper cervical chordomas were retrospectively studied with both magnetic resonance (MR) imaging and computed tomography (CT), and the advantages of each modality were compared with regard to three criteria: detection of tumor, delineation of extent of tumor, and characterization of tumor. MR imaging and CT were equivalent in permitting the detection of chordomas. MR imaging was considerably better in delineating the full extent of the tumor, which would influence establishment of treatment. MR imaging also provided a degree of histologic specificity that would be useful in prognosis.

Changes in size and magnetic resonance signal intensity of the cerebral CSF spaces during the cardiac cycle as studied by gated, high-resolution magnetic resonance imaging.

In 1966, du Boulay demonstrated the pulsatile nature of CSF flow in the cerebral aqueduct by using air cineventriculography, which disturbs normal CSF dynamics by replacing part of the incompressible CSF with air. To investigate this phenomenon noninvasively, 35 normal volunteers were studied using high-resolution, cardiac-gated MR imaging. Specifically, we wished to document changes in size and configuration of the CSF spaces and the incidence and magnitude of signal loss (an indication of CSF motion) in these spaces as they related to time in the cardiac cycle. Changes in size and configuration were measurable in the third ventricle only (size increased during systole in seven of the 35 volunteers). Except for the lateral ventricles, some loss in signal intensity was seen in all CSF spaces at least during systole in all 35 volunteers--findings consistent with those of du Boulay. However, contrary to du Boulay's observations, asymmetric loss of signal, consistent with pulsatile CSF flow, was demonstrated at the level of the foramen of Monro in 15 of the 35 volunteers. Based on the pattern of flow void at the level of the foramen of Monro and on the expansion of the third ventricle during systole, we propose a theory of synchronous CSF flow at the foramen of Monro and aqueduct, which unifies our MR findings with du Boulay's cineventriculographic observations.

Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies.

Masses at the craniovertebral junction generally have serious prognostic implications. However, the authors studied three patients who had chronic atlantoaxial subluxation from either degenerative disease or congenital dysplasia of the dens and who also had benign fibrous masses in this region, confirmed at surgery. The association of masses of the craniovertebral junction with chronic atlantoaxial subluxation raises the possibility that the underlying cause of the masses is chronic mechanical irritation. All patients were imaged with metrizamide myelography and adjunctive computed tomography (CT), then by magnetic resonance (MR) imaging. MR images were not only superior to myelograms and CT scans in delineating the exact extent of the lesions, they also indicated the benign, fibrous nature of the masses.

Gated magnetic resonance imaging of the intracranial cerebrospinal fluid spaces.

The pulsatile nature CSF flow in the cerebral aqueduct has been demonstrated by du Boulay using air cineventriculography, a technique which disturbs normal CSF dynamics. To investigate this phenomenon non-invasively, we studied 35 normal volunteers using high-resolution, cardiac-gated magnetic resonance imaging (MRI). Specifically, we wished to document changes in size, configuration and signal intensity of the CSF spaces as they related to time in the cardiac cycle. Results show that changes in size and configuration were measurable in the third ventricle only (size increased during systole in 7 of the 35 volunteers). Except for the lateral ventricles, some loss in signal intensity was seen in all CSF spaces at least during systole, in all 35 volunteers-findings consistent with du Boulay's. However, contrary to du Boulay's observations, asymmetric loss of signal, consistent with pulsatile CSF flow, was demonstrated in the foramen of Monro in 15 of the 35 volunteers. Based on the pattern of signal void at the level of the foramen of Monro and on the expansion of the third ventricle during systole we propose a theory of synchronous CSF flow at the foramen of Monro and aqueduct, which unifies our MRI findings with du Boulay's cineventriculographic observations.

Obstetrical magnetic resonance imaging: fetal anatomy.

Nine patients who were 34-36 weeks pregnant underwent magnetic resonance (MR) imaging. Sagittal images using spin echo technique (TR 2.0 sec, TE 28 msec) were optimal for delineating fetal anatomy. The fetal cardiovascular, pulmonary, and central nervous systems were depicted in all cases. The heart and major vessels were readily seen due to the natural contrast of flowing blood. The intensity of the fluid-filled lungs greatly increased with a longer TR or TE, delimiting thorax from liver. The brain was relatively featureless due to the lack of gray-white matter differentiation. The umbilical cord within the amniotic fluid and its insertion into the placenta and fetus was identified in all cases. MR is a new modality for fetal imaging that offers tissue-characterization information that complements the superior anatomic detail of ultrasound scanning.

Nuclear magnetic resonance imaging of the brain in children.

Nuclear magnetic resonance imaging of the hydrogen nucleus provides a unique noninvasive display of proton dynamics in biologic tissues and fluids as well as internal anatomy in a sectional imaging format. No ionizing radiation is utilized. Our experience with NMR imaging of the brain in 14 pediatric patients is presented and compared with computed tomography. The major advantages of NMR over CT include its greater sensitivity to blood flow, edema, hemorrhage, and myelinization and its lack of beam-hardening artifacts. In addition, the potential for tissue characterization exists by determination of T1 and T2 relaxation times and of mobile proton density. Disadvantages of NMR over CT include its failure to demonstrate calcification and bone detail and longer data acquisition times.

Pelvimetry by digital radiography: a low-dose examination.

Digital radiographs obtained with a CT scanner were evaluated as an alternative to conventional pelvimetry. Dosimetry studies demonstrated an absorbed radiation dose of 22 mrad for each digital radiograph, approximately 3% of the dose for comparable standard radiographs. Distance measurements were accurately made on digital radiographs and axial CT sections by cursor placement and a computer program with no needs to correct for magnification. Clinical studies of 10 patients confirmed that pelvimetry using digital radiographs is an accurate, simple, and extremely low-dose procedure which could replace the conventional method.