Steven P. Meyers

Associations between patient report of symptoms and anatomic impairment visible on lumbar magnetic resonance imaging

STUDY DESIGNnA cross-sectional study comparing the relationship of symptoms with anatomic impairment visible on lumbar magnetic resonance imaging in 408 symptomatic subjects.nnnOBJECTIVEnTo determine how various anatomic impairments, including the magnitude and location of nerve compression visible on lumbar magnetic resonance imaging, are associated with patient reports of pain, weakness, and dysesthesia.nnnSUMMARY AND BACKGROUND DATAnAnatomic impairments of the intervertebral disc, radicular canal, and associated soft tissues are prevalent in people with and those without low back pain or lower extremity radiculopathy. This has led to confusion in differentiating between symptom generators and benign variation visible on lumbar magnetic resonance imaging. Recent literature has suggested that the presence of nerve compression is an important finding in the prediction of symptoms. However, the threshold for meaningful nerve compression has not been described.nnnMETHODSnIn this study, 408 participants undergoing a diagnostic workup for low back pain, radiculopathy, and/ or completed a survey and pain drawing. Participants underwent standardized lumbar magnetic resonance imaging using a 1.5-T scanner. Two classification systems describing the spatial distribution of symptoms were developed. An additional system to quantify the magnitude of nerve and thecal sac compression was created. All systems were assessed for reliability, after which comparisons among variables were performed using Chi2 as well as simple and multiple logistic regression analysis.nnnRESULTSnThe reliability coefficients for categorizing patients on the basis of pain drawing ranged from 0. 75 to 0.88. The S1-S2 segmental distribution was the most commonly reported location of symptoms, followed by L4-L5. The most common magnetic resonance imaging diagnosis was unremarkable, followed by disc impairment without nerve compression. Disc extrusion was present in 10.8% of participants. The reliability of classifying nerve compression visible on magnetic resonance imaging ranged from 0.27 to 1. Nerve compression was present in 37% of participants, and 18% had severe nerve compression. There were no significant associations between segmental distribution of symptoms and the presence of anatomic impairment. However, according to a collapsed classification scale, severe nerve compression and disc extrusion were predictive of pain distal to the knee (odds ratios, 2.72 and 3. 34). The self-report of weakness was associated mildly with severe nerve compression and disc extrusion, but not with other findings. Magnetic resonance imaging findings did not predict self-reports of dysesthesia.nnnCONCLUSIONSnThe presence of disc extrusion and/or ipsilateral, severe nerve compression at one or multiple sites is strongly associated with distal leg pain. Mild to moderate nerve compression, disc degeneration or bulging, and central spinal stenosis are not significantly associated with specific pain patterns. Although segmental distributions of pain can be determined reliably from pain drawings, this finding alone is of little use in predicting lumbar impairment. The self-report of lower extremity weakness or dysesthesia is not significantly related to any specific lumbar impairments. [Key words: back pain, diagnosis, magnetic resonance imaging, nerve compression, pain drawing, pathology]

Stress reactions of the lumbar pars interarticularis: the development of a new MRI classification system.

Study Design. In a retrospective study, multiple examiners reviewed lumbar magnetic resonance imaging scans to develop a new grading system for lumbar pars interarticularis stress reaction and spondylolysis. The resulting system can be used as a mechanism for classifying patients, and as a measurement tool for future studies assessing the outcome efficacy of lumbar magnetic resonance imaging in patients with abnormalities of the pars interarticularis. Objective. To determine the reliability of patient assignment to five different grades of bone stress reaction involving the lumbar pars interarticularis. Summary of Background Data. Injury to the lumbar pars interarticularis (spondylolysis) is reported to be a common cause of low back pain in young patients. High-field-strength magnetic resonance imaging using fat saturation techniques and dedicated coil technology is sensitive in detecting bone stress injuries of the lumbar pars interarticularis, and thus is an excellent method for diagnosis. It also may be useful in prognostic decision making for these patients. A reliable classification system is a fundamental requirement for performing the research assessing the relationship between lumbar MRI findings and prognosis. Methods. For this study, 55 young athletic patients undergoing evaluation for low back pain with suspected stress injury to the lumbar pars interarticularis underwent standardized lumbar magnetic resonance imaging using a 1.5-T scanner. Magnetic resonance images were reviewed by three readers using a new magnetic resonance classification system developed for lumbar spondylolysis. The findings were assessed for both interobserver and intraobserver reliability for five possible combinations in a 5-grade classification system. Results. On magnetic resonance imaging, 42% of the patients demonstrated signal abnormalities of the lumbar pars interarticularis. The intraobserver and interobserver reliability coefficients for assigning the grade of pars interarticularis abnormality ranged, respectively, from 0.766 (95% confidence interval [CI], 0.62–0.91) to 0.906 (95% CI, 0.80–1), and from 0.706 (95% CI, 0.55–0.86) to 1. Conclusions. Magnetic resonance findings of stress reactions and spondylolysis of the lumbar pars interarticularis can be reliably classified into five grades by experienced readers. Further study is needed to determine the role of these findings in the management of young athletic patients with low back pain.

Intracranial Lesions with High Signal Intensity on T1-weighted MR Images: Differential Diagnosis

Various substances, including methemoglobin, melanin, lipid, protein, calcium, iron, copper, and manganese, are responsible for the intrinsically high signal intensity observed in intracranial lesions at T1-weighted magnetic resonance (MR) imaging. Many of these substances have physical properties that lead to other specific imaging features as well. For example, lipid-containing lesions frequently produce chemical shift artifact, and some melanin-containing lesions exhibit a combination of high signal intensity on T1-weighted images and low signal intensity on T2-weighted images. The location and extent of a region of abnormal signal hyperintensity may be helpful for identifying rare diseases such as an ectopic posterior pituitary gland near the floor of the third ventricle, bilateral involvement of the dentate and lentiform nuclei in Cockayne syndrome, and involvement of the anterior temporal lobe and cerebellum in neurocutaneous melanosis. In cases in which diagnostically specific T1-weighted imaging features are lacking, findings obtained with other MR pulse sequences and other modalities can help narrow the differential diagnosis: An elevated glutamine or glutamate level at MR spectroscopy is suggestive of hepatic encephalopathy; a popcorn ball-like appearance at T2-weighted imaging, of cavernous malformations; and hyperattenuation at computed tomography, of mineral deposition disease. In many cases, a comparison of imaging features with clinical measures enables a specific diagnosis.

Magnetic resonance imaging features of fractures using the short tau inversion recovery (STIR) sequence: correlation with radiographic findings.

The MRI characteristics of fractures have been described on the basis of spin echo (SE) images emphasizing T1 and T2 contrast. These previous studies were carried out for injuries in which radiographic proof was often lacking. In comparison with SE images, short tau inversion recovery (STIR) images have been shown to provide superior contrast between normal and abnormal marrow. To determine the MRI characteristics of fracture using STIR pulse sequences, we reviewed 28 patients who had radiographic evidence of fracture and were examined with T1-weighted SE and STIR sequences. MRI marrow signal abnormalities were demonstrated at all fracture sites ranging in age from less than 24 h to 8 weeks. The extent of marrow signal abnormalities exceeded the size of corresponding radiographic findings of fracture in all cases. The MRI features of fractures on T1-weighted SE images consisted of irregular intramedullary zones of hypointensity. On STIR images a corresponding zone of hyperintensity extended to the outer cortical margin. Intramedullary lines of hypointensity extending to the inner cortical margin were identified within the hyperintense marrow abnormality on STIR images in 64% of the fractures. The results of this study show that MRI using T1-weighted SE and STIR sequences can consistently demonstrate prominent signal abnormalities at fracture sites including those in which radiographic signs are subtle.

Primary lymphoma of bone : correlation of magnetic resonance imaging features with cytokine production by tumor cells

Background. Primary lymphoma of bone is a rare, aggressive neoplasm that can present with a large, soft‐tissue mass despite minimal evidence of cortical destruction on plain radiographs.

Magnetic resonance imaging : a cost-effective alternative to bone scintigraphy in the evaluation of patients with suspected hip fractures

Abstractu2002Objective. To evaluate the cost-effectiveness of magnetic resonance imaging (MRI) compared with radionuclide bone scan in the evaluation of patients with clinically suspected hip fractures.nDesign. The medical records of all patients who had been seen in the emergency room over a 4-year period with a clinically suspected hip fracture, negative or equivocal plain films, and either a subsequent bone scan or MRI examination were retrospectively reviewed. The time to diagnosis, admission rate, and time to surgery were determined. A two-sample t-test was used to assess the statistical significance of the results. A theoretical cost analysis was performed using current charges to estimate all expenses.nPatients. Forty patients (11 male, 29 female; age 28–99 years) satisfied our inclusion criteria.nResults and conclusions. Twenty-one patients had bone scans (six with fractures), and 19 had MRI (four with fractures). The time to diagnosis was 2.24±1.30 days for bone scanning and 0.368±0.597 days for MRI (P<0.0001). Twenty patients in the bone scan group were admitted compared with 13 in the MRI group. The time to surgery was at least 1 day longer in patients undergoing bone scanning. Bone scanning resulted in higher patient costs compared with MRI because of the delay in diagnosis. In the evaluation of patients with suspected hip fractures, early MRI is more cost-effective than delayed bone scanning. Further prospective studies comparing the cost-effectiveness of early MRI with early bone scanning are needed.

Choroid plexus carcinomas in children: MRI features and patient outcomes

Choroid plexus carcinomas (CPC) are rare malignant intracranial neoplasms usually occurring in young children. The objectives of this study were to characterize the preoperative MRI features of CPC, determine the frequency of disseminated disease in the CNS at diagnosis, and assess patient outcomes. The preoperative cranial MR images of 11 patients with CPC were retrospectively reviewed for lesion location, lesion size, un-enhanced and enhanced MRI signal characteristics, and presence of disseminated intracranial tumor. Postoperative cranial and spinal MRI images were reviewed for residual, recurrent, and/or disseminated tumor. The study group included six male and five female patients ranging in age from 5xa0months to 5.3xa0years (median=1.8xa0years). CPC were located in the lateral (n=8), fourth (n=1), and third (n=1) ventricles, and foramen of Luschka (n=1). Mean tumor size was 5.2cm×4.9cm×5.0xa0cm. On short-TR images, CPC had heterogeneous, predominantly intermediate signal with foci of high signal in 45% of lesions from areas of hemorrhage. On long-TR/long-TE images, solid portions of CPC typically had heterogeneous, intermediate-to-slightly-high signal. Small zones of low signal on long-TR/long-TE images were seen in 55% of the lesions secondary to areas of hemorrhage and/or calcifications. Tubular flow voids representing blood vessels were seen in 55% of the lesions. Zones of high signal comparable to CSF were seen in 64% of CPC secondary to cystic/necrotic zones. All CPC showed prominent contrast enhancement. Irregular enhancing margins suggesting subependymal invasion were seen in 73% of the lesions. Findings consistent with edema in the brain adjacent to the enhancing lesions were seen in 73% of CPC. CPC caused hydrocephalus in 82% of patients at diagnosis. Two patients died from hemorrhagic complications from surgical biopsies. Disseminated tumor in the leptomeninges was present in 45% of patients at diagnosis and was associated with a poor prognosis. The 1-year and 5-year survival probabilities were 55% and 45%, respectively. In conclusion, MRI features commonly associated with CPC include large intraventricular lesions with irregular enhancing margins; heterogeneous signal on long TR/long TE images and short-TR images; edema in adjacent brain; hydrocephalus; and presence of disseminated tumor. MRI evidence of disseminated tumor at diagnosis is associated with a poor prognosis.

Parallel processing streams in human visual cortex

THIS study shows the existence in humans of independent neural processing streams in early visual cortex, which had previously been demonstrated in macaque monkeys. This evidence was obtained by controlled fixation testing of a subject who had suffered a small stroke in the right fusiform gyrus. The patient showed a severe disruption of color perception, shape discrimination and contrast sensitivity for stationary gratings in the upper left quadrant of his visual field. However, motion perception and contrast sensitivity for drifting gratings were relatively preserved. These results support the view that there are independent visual processing streams early in human visual cortex, and that these streams may subserve such functions as motion and color/form perception.

Hemangioblastoma of the optic nerve

A 43-year-old woman presented with progressive loss of vision in the right eye. Magnetic resonance imaging (MRI) showed a prominently enhancing lesion of the optic nerve, thought preoperatively to represent an optic nerve meningioma or optic neuritis. Histological examination of the excised tumor showed this lesion to be hemangioblastoma. Her family history was unremarkable. However, subsequent review of the preoperative MRIs and postoperative imaging studies showed two small cerebellar lesions, probably hemangioblastomas, and renal, pancreatic, and adnexal cysts, establishing the diagnosis of von Hippel-Lindau disease.

Magnetic resonance imaging of muscle injury

To further evaluate the role of magnetic resonance (MR) imaging in diagnosing and managing muscle injuries, eight patients with muscle pain or palpable masses were imaged. MR findings were correlated with clinical follow-up data. Increased signal was noted on T2-weighted images in torn and overused muscles. One extensively scarred muscle required surgical biopsy to exclude a fibrous tumor. Three partial muscle tears were treated conservatively. One complete musculotendinous junction tear required tendon transfer. MR studies noninvasively identified and staged various muscle injuries, thereby influencing management.