A L Williams

The Computed Tomographic Appearance of the Normal Pituitary Gland and Pituitary Microadenomas

With the use of axial and coronal computed tomography (CT), the authors compared the density, contrast enhancement, and dimensions of normal pituitary glands and pituitary microadenomas. The normal gland appears homogeneous, nearly isodense with brain tissue, and it enhances uniformly. Its upper surface is concave downward or flat and its height 2-7 mm. The cavernous sinuses, the third, fourth, and sixth cranial nerves, the infundibulum, and the adjacent carotid arteries are well demonstrated by CT. Abnormal height and upward convexity of the gland are reliable signs of prolactinoma; abnormal density and enhancement are suggestive signs. CT findings in prolactin- and ACTH-secreting tumors may differ. CT is more sensitive and more specific than polytomography in the diagnosis of pituitary adenoma.

Can We Distinguish Between Benign Versus Malignant Compression Fractures of the Spine by Magnetic Resonance Imaging

Study Design The authors investigate the usefulness of magnetic resonance imaging in differentiating benign versus malignan compression fractures by reviewing patients and a fracture model in a canine model. Objectives To determine the sensitivity and specificity of magnetic resonance imaging in differentiating benign versus malignant compression fractures of the spine and to obtain distinguishing features in magnetic resonance imaging. Summary of Background Data The differentiation between benign and abnormal compression fractures of the thoracolumbar spine has important implications regarding patient treatment and prognosis. Plain radiographs, bone scans, and computed tomography are not accurate imaging modalities for this purpose. Methods Magnetic resonance imaging scans of 22 patients with confirmed lesions of the thoracolumbar spine were studied. There were 11 malignant and 11 benign lesions. Two experienced neuroadiologists blindly reviewed the magnetic resonance imaging scans and determined benign or malignant lesions. A canine study was performed to simulate a compression fracture model with a vertebral osteotomy in two dogs, and serial contrast-enhanced magnetic resonance imaging scans were performed 15, 30, 60 and 90 days after surgery. Results The correct interpretation between two neuroradiologists was 77% and 95%. The combined sensitivity rate was 88.5%, and the specificity rate was 89.5%. Magnetic resonance imaging reliably distinguished beningn versus malignant lesions based on the anatomic distribution and intensity of signal changes of bone and adjacent tissues, contrast enhancement characteristics, and changes over time. Only one malignant lesion was misinterpreted by both neuroradiologists as benign, whereas there was one additional missed malignant lesion and three misinterpreted benign lesions by one radiologist. In the canine study, signal changes and enhancement were found 60 days after surgery, but no signal changes or enhancement were noted on the scan 90 days after surgery. Conclusions Magnetic resonance imaging scans can detect malignant vertebral lesions early, but acute healing compression fractures may mimic the findings of metastatic lesions. The use of contrast-enhanced magnetic resonance imaging scans and serial magnetic resonance imagings are helpful for additional differentiation between benign and malignant compression fractures. In addition to magnetic resonance imaging scans, other diagnostic tests and clinical findings should be correlated before biopsy or surgery of the suspected lesion.

Computed tomography of the spine

The book describes the computed tomographic (CT) techniques for imaging the different elements comprising the spinal column and canal. The use of intravenous and intrathecal contrast enhancement and of xenon enhancement is briefly mentioned. Reconstruction techniques and special problems regarding CT of the spine are presented. CT of the spinal cord, meninges and subarachnoid space, epidural space, intervertebral discs, facet joints, and vertebrae present normal anatomy, and several common pathologic conditions. (KRM)

Quantification of contrast in clinical MR brain imaging at high magnetic field.

The relative contrast between two tissues in a magnetic resonance (MR) image is shown to be quantifiable for any combination of pulse timing parameters, provided the intrinsic parameters are known. Based on multiple inversion-recovery and spin echo images, a region-of-interest T1, T2 and density analysis was conducted at 1.4T in selected patients with diagnosed neuropathology for various brain tissues. The resulting tissue parameters subsequently served to calculate the contrast-to-noise (C/N) ratio for typical tissue interfaces as a function of the operator-variable pulse timing parameters and the data were compared with the images. Although such calculations may be useful as a protocol selection aid, it is obvious that an optimized pulse protocol can only be established for a single tissue interface. The data also reveal that a T2-discriminating pulse sequence like Carr-Purcell-Meiboom-Gill with long repetition time, generally advocated as clinically most effective, may not always be ideal.

Diagnosis of herniated lumbar disk with computed tomography.

THE indications for computed tomography (CT) in patients with low back and leg pain are expanding as the resolution of the scanners improves. CT is already the procedure of choice for diagnosing lu...

Lumbar disc nomenclature: version 2.0: recommendations of the combined task forces of the North American Spine Society, the American Society of Spine Radiology, and the American Society of Neuroradiology.

Study Design. This article comprises a review of the literature pertaining to the normal and pathological lumbar disc and the compilation of a standardized nomenclature. Objective. To provide a resource that promotes a clear understanding of lumbar disc terminology among clinicians, radiologists, and researchers. Summary of Background Data. The article “Nomenclature and Classification of Lumbar Disc Pathology. Recommendations of the Combined Task Forces of the North American Spine Society, American Society of Spine Radiology and American Society of Neuroradiology” was published in 2001 in Spine

Gradient recalled echo MR imaging of superior sagittal sinus occlusion

SummaryWith T1-weighted gradient recalled echo (GRE) MR images and flow compensation, we studied the superior sagittal sinus in 3 normal volunteers and 3 patients with sinus occlusion. In these images, sites of patency of the superior sagittal sinus were identified due to the high signal intensity of the normal sinus. Tumor invading the sinus was nearly isointense with cerebral gray matter. T1-weighted GRE imaging proves to be an effective technique to evaluate sinus blood flow.

A clinical evaluation of xenon enhancement for computed tomography.

Xenon increases the attenuation coefficients of tissues in which it dissolves and, therefore, enhances lipid-rich material. The authors evaluated xenon enhancement for computed tomography. Patients and normal subjects were given xenon in subanesthetic concentrations and were scanned in a large aperture CT scanner. Patients tolerated 30-50% inhaled xenon well. Cerebral tissues and lung were enhanced by this concentration of xenon. Xenon inhalation in subanesthetic concentrations will be a useful technique for characterizing abnormal lipid tissues and for estimating cerebral blood flow.

Arteriovenous Malformation Simulating a Cyst on Computed Tomography

Three cases are described in which an intracerebral arteriovenous malformation (AVM) was accompanied by a cystic component probably resulting from hemorrhage. The 3 patients gave a history of headaches. In cases of low-attenuating nonenhancing CT processes, an AVM must be considered.

Computed tomography in Behçet disease.

In Behçet disease, CT may demonstrate low attenuation mass lesions with or without contrast enhancement. Since neurologic involvement may precede the typical dermatologic manifestations, Behçet disease should be included in the differential diagnosis of intracranial mass lesions. A case is presented with central nervous system involvement.