Diffusion-weighted imaging of brain metastases: their potential to be misinterpreted as focal ischaemic lesions.

Small focal ischaemic brain lesions are said to be easy to identify in the acute stage and to differentiate from older lesions using diffusion-weighted imaging (DWI). Brain metastases are common and the aim of this study was to evaluate the risk of misinterpretation as ischaemic lesions in a standard MRI protocol for clinical stroke. Of 26 patients investigated with MRI for possible metastases, 12 did have metastatic brain lesions, including most of the common tumours. On a 1.5 tesla imager, we obtained DWI, plus T2- and T1-weighted images, the latter before and after triple-dose contrast medium. Well-circumscribed brain lesions with a decreased apparent diffusion coefficient and a slightly or moderately increased signal on T2-weighted images were found in patients with metastases from a small-cell bronchial carcinoma and a pulmonary adenocarcinoma. The same features were also found in metastases from a breast carcinoma but the lesions were surrounded by oedema. With a standard DWI protocol, the features of common brain metastases may overlap with those of small acute and subacute ischaemic lesions

Psychologic Tests in the Evaluation of Psychic Changes after Myelography with Metrizamide

The possibility of using psychologic tests to demonstrate psychic changes following myelography with metrizamide was investigated in 15 patients. The tests were made before and after the examination. The results revealed psychic changes of cognitive nature to occur both at 6 and at 24 hours after myelography. Of the tests used determination of the reaction time gave most significant results. Subjectively the patients considered themselves better 24 hours after the examination than after 6 hours. This was not confirmed from the test results—an observation indicating the sensitivity of the test instruments used. Thus, these appear to be well suited to study cognitive changes caused by the contrast media used in this particular type of examination. Since the tests are repeatedly performed, the effect of habituation and of learning cannot be avoided. However, when applied in groups of patients, in whom the effects of different contrast media are compared, the disadvantages of these specific effects can be neglected

Isthmic lumbar spondylolisthesis with sciatica. MR imaging vs myelography

Seventeen patients with sciatica and isthmic lumbar spondylolisthesis were studied with magnetic resonance (MR) imaging. In 13, myelography was also performed: 5 had dural sac deformation and root sleeve shortening, 2 had deformation with unilateral root sleeve shortening, one had bilateral root sleeve shortening only, and one had sac deformation only. In 4, myelography was normal. On sagittal MR examinations the neural foramen had an altered shape bilaterally with the long axis horizontal in all cases. In addition to altered shape the following was found in the 33 foramina evaluated. I: normal nerve (n = 8); II: compressed nerve (n = 16); III: disappearance of fat, nerve not possible to identify (n = 9). In patients with unilateral sciatica, the degree of foraminal stenosis correlated well with the side of symptoms. Coronal views showed the course of the nerve and pedicular kinking. Eight patients underwent decompressive surgery which revealed nerve compression by hypertrophic fibrous tissue and pedicular kinking, which correlated well with the findings on MR. Since the site of nerve compression often was peripheral to the root sleeves, myelography did not give complete information

Cerebral Perfusion Imaging in Hemodynamic Stroke: Be Aware of the Pattern

Reduction of the cerebral perfusion pressure caused by vessel occlusion or stenosis is a cause of neurological symptoms and border-zone infarctions. The aim of this article is to describe perfusion patterns in hemodynamic stroke, to give a practical approach for the assessment of colour encoded CT- and MR-perfusion maps and to demonstrate the clinical use of comprehensive imaging in the workup of patients with hemodynamic stroke