Objective: This study aimed to determine whether magnetic resonance imagine with Eigen image filtering can segment acoustic neuromas as a preliminary requirement to the development and validation of a volumetric method of measuring tumor size and growth using Eigen image filtering.Study Design: This was an observational study.Setting: The study was performed in an academic, comprehensive multi-specialty group practice.Patients: Patients were a convenience sample of adults of both sexes who had acoustic neuromas identified by magnetic resonance imaging. Tumors ranged widely in size.Intervention: Magnetic resonance imaging with digital image analysis using Eigen image filtering was the intervention.Main Outcome Measure: Observation and analysis of magnetic resonance images was the main outcome measure.Results: The ability of magnetic resonance imaging with Eigen image filtering to segment acoustic neuromas of various sizes and shapes is illustrated.Conclusions: Magnetic resonance imaging with digital image analysis using Eigen image filtering is a promising method for volumetric measurement of acoustic neuroma size and growth. The potential for acoustic neuromas to grow may be underestimated by linear methods because of their relative lack of precision and of the geometric error that occurs in rep resenting the volumetric growth of a three-dimensional tumor as a linear diameter.

The magnetic resonance (MR) appearance of hemorrhagic acoustic neuromas has not previously been reported. Four patients with surgically proven acoustic neuromas containing spontaneous hemorrhage were preoperatively evaluated with MR imaging. All patients presented with new onset of symptoms and three had subarachnoid hemorrhage. Signal changes on T1- and T2-weighted spin echo sequences were characteristic for acute, subacute and chronic intraparenchymal hemorrhage. Recognition of hemorrhagic changes on MR is important since more rapid surgical intervention is required in this patient subgroup.

The MR appearance of acute subarachnoid hemorrhage experimentally produced in Macaca monkeys and observed in patients with clinically documented acute subarachnoid hemorrhage is presented. Subarachnoid hemorrhages were produced in two Macaca Nemestrema monkeys using the technique of Frazee. CT and MR imaging were performed immediately after the procedure and at frequent intervals up to two week post hemorrhage. MR including T1 and T2 weighted multiplanar spin echo images were obtained. The imaging studies were compared with clinical evaluations and pathological specimens of all animals. Findings in the experimental animals are correlated with those observed in patients with clinically documented subarachnoid hemorrhage. The results show that acute subarachnoid hemorrhage (SAH) can be detected with MRI as isointense signal replacing normally black CSF spaces on T1 weighted images. Signal changes most likely relate to protein water binding associated with the clotting mechanism rather than oxidative denaturation of hemoglobin. Imaging performed experimentally and clinically beyond four days, however, showed a marked increase in signal intensity on T1 weighted images which probably does result from methemoglobin formation within the clot matrix. Although CT remains the gold standard in detecting acute SAH, MR does provide some sensitivity to its presence.

Aspiration biopsy guided with computed tomography (CT) has long been a valuable tool in the evaluation of head and neck disease. The ability to obtain diagnoses without the need for surgery has had a significant effect on patient treatment. Magnetic resonance (MR) imaging is now rapidly replacing CT as the primary imaging study for many head and neck diseases. The standard stainless steel needles used for CT-guided biopsy are unsuitable for MR-guided biopsy because significant ferromagnetic artifacts obscure the underlying anatomy. A new needle has recently been designed specifically for use with MR imaging. This needle has far less magnetic susceptibility and therefore does not cause significant image distortion. The authors describe the use of this needle in MR-guided aspiration biopsy of a variety of lesions in the head and neck.

One of the most revolutionary recent imaging advances is the use of magnetic resonance to study and produce morphologic representations of flowing blood vessels known as MR angiography. The ability to produce an image of even moderate spatial resolution of the three dimensional course of blood vessels with MR could have significant advantages over conventional invasive angiography which requires ionizing radiation and contrast material injection. By definition, MR angiography does not require the addition of any intravascular contrast agents and the images are produced entirely by the effect of the radio frequency pulses and magnetic field gradients on the spinning protons. Several researchers are already producing relatively high resolution MR angiograms using a variety of techniques. Essentially all techniques of MR angiography use variations of three steps to produce the image: (1) a projection image, (2) suppression of background static material, and (3) production of a flow sensitive image. This report will survey some of the more commonly used approaches to MR angiography that are currently under investigation.

The use of a new body stereotactic system to facilitate magnetic resonance (MR) guided biopsies is described. A skin entry point is first found using a localizer MR scan. The articulating arm of the stereotactic unit is then used to aim the MR needle at the entry point and accurately maintain the needle at the correct angle to intersect the target area. Complex angles may be used to allow needle passes outside the scan plane. This is accomplished by angling the arm out of the plane of the section.

Five patients presented with dysphagia but did not have abnormal esophageal motility or morphology on the esophagram. Each was found to have a malignant gastric tumor which did not appear to involve the gastroesophageal junction, and this was confirmed surgically in 2 cases. In 2 patients, diagnosis was delayed as a result of failure to examine the stomach following a normal esophagram. In the absence of abnormal esophageal motility, changes involving the gastroesophageal junction, or cerebral metastases, it is postulated that the dysphagia represented a nonspecific regional response to functional obstruction of the upper gastrointestinal tract secondary to an infiltrating neoplasm of the stomach. The fact that the esophagram was normal emphasizes the possibility that gastric lesions in patients with dysphagia may be missed when only a routine esophagram is employed. The authors recommend that the stomach be examined when no apparent cause for dysphagia can be discerned above the gastroesophageal junction.