MRI in the classical MM1 and the atypical MV2 subtypes of sporadic CJD: an inter-observer agreement study.

BACKGROUND AND PURPOSE: To establish radiological features in the atypical MV2 subtype of sCJD compared with the classical MM1 subtype, as well as region- and sequence-dependent inter-observer correlation. METHODS: MRI hyperintensity of basal ganglia (BG), cortex and thalamus was evaluated in 31 MM1 and 32 MV2 patients. Each MR scan was analyzed independently by two neuroradiologists blinded to PRNP genotype/prion protein type. RESULTS: Cumulative T2-sensitivity for BG hyperintensity was higher in the MV2 subtype (84% for both observers versus 61% in observer 1/42% in observer 2 in MM1 patients). Significant inter-observer agreement was found for BG and thalamus on T2, FLAIR, PD and DWI, but for cortex only on DWI. Thalamic changes were significantly more frequent in MV2 than in MM1 patients (cumulative sensitivity 86% vs. 12.5% on DWI). DISCUSSION: The high frequency of thalamic hyperintensity in the MV2 subtype allowed differentiation from MM1 patients. Good inter-observer agreement was found for BG and thalamus in all sequences. DWI showed the highest inter-observer correlation independent of the investigated brain region and was therefore not only highly sensitive but also relatively independent of investigator bias. Since inter-observer correlation for cortical hyperintensity in T2, FLAIR and PD is relatively low, the cortical changes should not be over-interpreted with these sequences.

Outcome, observer reliability, and patient preferences if CTA, MRA, or Doppler ultrasound were used, individually or together, instead of digital subtraction angiography before carotid endarterectomy.

OBJECTIVES: To evaluate the accuracy of routinely available non-invasive tests (spiral computed tomographic angiography (CTA), time of flight magnetic resonance angiography (MRA), and colour Doppler ultrasound (DUS)), individually and together, compared with intra-arterial digital subtraction angiography (DSA) in patients with symptomatic tight carotid stenosis; and to assess the effect of substituting non-invasive tests for DSA on outcome, interobserver variability, and patient preference. METHODS: Patients referred from a neurovascular clinic were subjected prospectively to DUS imaging. The operator was blind to symptoms. Patients with a tight carotid stenosis on the symptomatic side were admitted for DSA. CTA and MRA were performed during the admission. The CTA, MRA, and DSA films were each read independently by two of six experienced radiologists, blind to all other data. RESULTS: 67 patients were included (34 had all four imaging procedures). DUS, CTA, and MRA all agreed with DSA in the diagnosis of operable v non-operable disease in about 80% of patients. CTA tended to underestimate (sensitivity 0.65, specificity 1.0), MRA to overestimate (sensitivity 1.0, specificity 0.57), and DUS to agree most closely with (sensitivity 0.85, specificity 0.71) the degree of stenosis as shown by DSA. When using any two of the three non-invasive tests in combination, adding the third if the first two disagreed would result in very few misdiagnoses (about 6%). MRA had similar interobserver variability to CTA (both worse than DSA). Patients preferred CTA over MRA and DSA. CONCLUSIONS: DUS, CTA, and MRA all show similar accuracy in the diagnosis of symptomatic carotid stenosis. No technique on its own is accurate enough to replace DSA. Two non-invasive techniques in combination, and adding a third if the first two disagree, appears more accurate, but may still result in diagnostic errors.

Interobserver variability of magnetic resonance angiography in the diagnosis of carotid stenosis--effect of observer experience.

Magnetic resonance angiography (MRA) for determining the degree of carotid stenosis prior to carotid endarterectomy is attractive because it does not have the high morbidity associated with conventional intra-arterial angiography. We assessed the interobserver variability in the estimation of the degree of stenosis amongst observers of different experience. In a prospective study, consecutive patients with transient ischaemic attacks and symptomatic tight carotid stenosis shown by Doppler ultrasound underwent conventional intra-arterial angiography and 2-D and 3-D time-of-flight MRA of the carotid bifurcations. The films of the processed MRA images were reviewed blind to other clinical and imaging data by eight observers of different levels of experience and coded for the presence and degree of stenosis. The stenosis on intra-arterial angiography was used as the reference standard. There was considerable variability between observers for estimation of the degree of stenosis on MRA. The observers' accuracy ranged from 41% (student) to 79% (experienced). From these estimations, excluding those of the student, it could be seen that up to 23% of patients who would have had an endarterectomy based on MRA should not have done so according to angiography, and up to 33% of patients who should have had an endarterectomy according to angiography would have inappropriately missed having an endarterectomy based on MRA results. Observer reliability of MRA processed images is not good, even in experienced hands. Using the source images and views of the circle of Willis might improve the accuracy, but a further study is required to assess this.

The role of MRI in the diagnosis of sporadic and variant Creutzfeldt-Jakob disease.

Creutzfeldt-Jakob disease (CJD) is a rare but important fatal, dementing illness. A number of types of CJD are identified, each with distinct clinical features. Characteristic MRI changes have been described recently. Sporadic CJD, the commonest type, is found worldwide, and causes hyperintensity of the putamen and caudate nuclei. In the recently described variant CJD, which affects younger patients and has been linked to Bovine Spongiform Encephalopathy (BSE) in cattle, a highly characteristic finding of bilateral hyperintensity of the pulvinar nuclei is seen. The MRI features of CJD are reviewed in this article.

MRI of Creutzfeldt-Jakob disease: imaging features and recommended MRI protocol.

Creutzfeldt-Jakob Disease (CJD) is a rare, progressive and invariably fatal neurodegenerative disease characterized by specific histopathological features. Of the four subtypes of CJD described, the commonest is sporadic CJD (sCJD). More recently, a new clinically distinct form of the disease affecting younger patients, known as variant CJD (vCJD), has been identified, and this has been causally linked to the bovine spongiform encephalopathy (BSE) agent in cattle. Characteristic appearances on magnetic resonance imaging (MRI) have been identified in several forms of CJD; sCJD may be associated with high signal changes in the putamen and caudate head and vCJD is usually associated with hyperintensity of the pulvinar (posterior nuclei) of the thalamus. These appearances and other imaging features are described in this article. Using appropriate clinical and radiological criteria and tailored imaging protocols, MRI plays an important part in the in vivodiagnosis of this disease.

Gliosarcoma with areas of primitive neuroepithelial differentiation and extracranial metastasis.

We report a case of gliosarcoma with areas of primitive neuroepithelial differentiation arising in the temporal lobe of a 53-year-old man. The sarcomatous component of this tumor was perivascular in its distribution and showed expression of factor VIII-related antigen, smooth muscle actin and CD34. The primitive neuroepithelial component possessed a small cell morphology and showed expression of neuronal antigens. Strong expression of p53 was demonstrated throughout the tumor with only focal weak expression of epidermal growth factor receptor. The tumor developed widespread extraneural metastases 5 months after surgical resection of the primary tumor. Histological examination of the liver metastases showed them to consist predominantly of the primitive neuroepithelial component. We believe this to be a novel pattern of differentiation in a gliosarcoma which in this case was associated with an aggressive metastatic potential.

The significance of intratumoural neurones and neuronal differentiation in diffuse gliomas: a case series.

We describe four patients, ranging from 26-40 years of age, who presented with seizures and large, poorly circumscribed cerebral tumours on magnetic resonance imaging. The resected tumours demonstrated a histopathology similar to low-grade glioma, but with admixed mature neurones. Immunohistochemistry demonstrated expression of putative neuronal antigens in the neuronal component as well as in tumour cells which did not show neuronal morphology. These tumours did not have the usual radiological and pathological features typical of gangliogliomas, but demonstrated an infiltrative pattern of growth and subsequent progressive behaviour. The term ganglioglioma, with its implication of good prognosis, is therefore inappropriate for tumours of this type. The expression of "neuronal" antigens by astrocytomas requires further investigation.

CNS involvement of virus-associated hemophagocytic syndrome: MR imaging appearance.

The MR imaging appearance of a case of virus-associated hemophagocytic syndrome complicated by diffuse CNS infiltration is presented. Virus-associated hemophagocytic syndrome is a rare condition, precipitated by viral infection and characterized by proliferation of benign histiocytes with phagocytosis. In severe cases, the CNS may be involved.

The pulvinar sign on magnetic resonance imaging in variant Creutzfeldt-Jakob disease.

BACKGROUND: There is a need for an accurate non-invasive diagnostic test for variant Creutzfeldt-Jakob disease (vCJD). We investigated the sensitivity and specificity of bilateral pulvinar high signal on magnetic resonance imaging (MRI) for the diagnosis of vCJD. METHODS: MRI from patients with vCJD and controls (patients with suspected CJD) were analysed. Scans were reviewed on two separate occasions by two neuroradiologists and scored for the distribution of changes, and likely final diagnosis. Scans from vCJD cases were reassessed to reach a consensus on all abnormalities. FINDINGS: We analysed 36 patients and 57 controls. vCJD patients were correctly identified based on bilateral pulvinar high signal in 29 of 36 and 32 of 36 cases on the first assessment by the two radiologists, and 32 of 36 and 31 of 36 on their second assessment. Bilateral increased pulvinar signal was identified in one of 57 and one of 57 controls on the first assessment and two of 57 and three of 57 controls on the second assessment. These reported changes in controls were graded as minimal/equivocal in six of seven patients and moderate in one (<0.5% of all control assessments). 80% of the assessments in vCJD cases were graded as moderate or substantial. On consensus review, 28 of 36 cases and none of 57 controls had prominent bilateral pulvinar signal-sensitivity 78% (95% CI 60-90%) and specificity 100% (95% CI 94-100%). Other common MRI features of vCJD were medial thalamic and periaqueductal grey matter high signal, and the notable absence of cerebral atrophy. Pulvinar high signal correlated with histological gliosis. INTERPRETATION: In the appropriate clinical context the MRI identification of bilaterally increased pulvinar signal is a useful non-invasive test for the diagnosis of vCJD.

Imaging features of leptomeningeal metastases.

AIMS: To assess the range of appearances, and accuracy of various methods of diagnosing leptomeningeal metastases. MATERIALS AND METHODS: In a retrospective study, the notes and imaging of all patients with a radiological and/or CSF cytological diagnosis of leptomeningeal metastasis (LM) were identified, and assessed for the following: age and sex, primary tumour type, presenting symptoms, initial radiological and cytological diagnosis, radiological appearances and length of survival following diagnosis. Discordance between the CSF cytology and radiological diagnosis of LM was also noted. RESULTS: 41 positive cases (36 female) of LM were identified over a 2.7 year period (diagnosis based on: imaging only--19 cases, cytology only--6, both--16 cases). The average age was 48 years, and the most frequent primary tumour was breast carcinoma (27/41). Two thirds of patients presented with at least one cranial or spinal nerve palsy. Where performed, contrast-enhanced CT was normal in 40% (10/25), with LM mistaken for parenchymal disease in a further 24% (6/25). CSF cytology was positive in 85% (22/26). Gadolinium-enhanced MRI was positive in all cases where it was performed (25/25). Pial enhancement and nodularity was the commonest finding (67%), but other manifestations included nodular disease, neural enhancement and white matter changes. Prognosis was uniformly poor. CONCLUSION: Leptomeningeal metastatic disease has a poor prognosis, and treatment regimen may differ from those of parenchymal CNS metastases. CT is normal or misleading in two thirds of patients, and CSF cytology may also be negative. Gadolinium-enhanced T1-weighted MRI complements CSF cytology, and is the investigation of choice in patients with a non-haematological primary tumour and suspected LM.

Atherosclerotic plaque at the carotid bifurcation: CT angiographic appearance with histopathologic correlation.

BACKGROUND AND PURPOSE: The likelihood that carotid plaque will give rise to cerebral ischemia probably relates to the degree of arterial stenosis and to plaque morphology. The aim of this study was to assess whether features seen at CT angiography might be used to predict carotid plaque stability by comparing CT angiograms with histopathologic examinations of the carotid artery bifurcation. METHODS: Nine patients with symptomatic severe carotid stenosis at intraarterial angiography had CT angiography of the carotid bifurcation before carotid endarterectomy. After endarterectomy, multiple sections of the specimens through the carotid bifurcation were examined histologically. Plaque characteristics recorded included the proportion of necrotic/lipid core, presence of hemorrhage, extent of fibrosis, ulceration, calcification, inflammatory cell infiltrate, and fibrous cap thickness. Corresponding CT angiograms were assessed for plaque size, distribution, and radiodensity as well as presence of calcific density and ulceration. Histologic findings and CT angiograms were compared. RESULTS: Plaque with a large necrotic/lipid core, which was often hemorrhagic, was found in 16 of 23 sections, and in 15 of these this histologic appearance corresponded with patchy or homogeneous low density on CT angiograms. Six of seven predominantly fibrous plaques were of soft-tissue density on CT angiograms. High density consistent with calcification was seen more frequently on CT angiograms than it was detected histologically, but CT angiography depicted plaque ulceration poorly (four ulcers at histology; two false-positive and two false-negative findings at CT angiography). CONCLUSION: CT angiography is a promising method for assessing the lumen and wall of the carotid artery. The apparent correlation between histologic appearance and plaque density on CT angiograms has important implications for the prediction of plaque stability, even though ulceration is shown inconsistently.

The diagnostic yield of magnetic resonance imaging (MRI) of the brain and spine requested by general practitioners: comparison with hospital clinicians.

The rate of diagnosis of radiologically significant abnormalities in outpatients following requests of magnetic resonance imaging (MRI) of the brain and spine by general practitioners was compared with the rate following MRI scan requests by hospital clinicians. A similar rate of significant pathology was diagnosed in both groups in both the brain and the spine. Under carefully controlled conditions, open-access MRI scanning of the brain and spine can contribute to effective patient management.

Limitations of using a cancer registry to identify incident primary intracranial tumours.

The completeness and accuracy of registration of primary intracranial tumours in the Scottish Cancer Registry was compared with a detailed incidence study performed over a two year period (1989-90). Of 228 patients with any primary intracranial tumour in the incidence study, 124 (54%) were identified as intracranial tumours in the cancer registry. The registry excluded benign tumours (although this was not consistent) and so the sensitivity of the registry varied with tumour type (84% for neuroepithelial tumours, 22% meningeal, 29% sellar, 0% cranial nerve). Of the 31 malignant tumours not found in the registry on our initial search, nine were found to have been included between 1989-90 but using different International Classification of Diseases-9th revision (ICD-9) codes or postcodes, and seven were found registered after 1990. Eleven per cent of cases (18/170) identified in the cancer registry were excluded from the incidence study: 11 had evidence of an intracranial tumour before 1989 whereas four definitely did not have an intracranial tumour. The cancer registry therefore significantly underestimated the incidence of all primary intracranial tumours, and of malignant intracranial tumours. Incidence studies must use additional methods to identify all primary tumours. Cancer registries should consider registering all primary intracranial tumours and may improve case ascertainment by screening neuroradiology data.

Incidence of intracranial tumours in the Lothian region of Scotland, 1989-90.

OBJECTIVE: To determine the incidence of primary and secondary intracranial tumours in the Lothian region of south east Scotland. METHODS: A population based study was performed. Patients from Lothian with incident intracranial tumours diagnosed in 1989 and 1990 (by CT or histology) were identified retrospectively using multiple sources. Differences in incidence by tumour type, age, sex, and socioeconomic status were examined. RESULTS: Four hundred and forty two patients with incident intracranial tumours were identified (228 primary tumours and 214 secondary tumours). The crude yearly incidences of primary and secondary tumours were 15.3 and 14.3 per 100,000 respectively. The commonest primary tumours were neuroepithelial tumours (53.5%), meningeal tumours (19.5%), and sellar tumours (16.5%). About 50% of patients with secondary tumours had an underlying lung cancer. The incidence of primary and secondary tumours increased markedly with age. Meningeal tumours were more common in women, and neuroepithelial tumours were more common in those who lived in more affluent areas. CONCLUSIONS: The incidence rates of primary and secondary intracranial tumours in Lothian were more than twice those previously reported in the United Kingdom. Intracranial tumours are a significant cause of morbidity and mortality in the United Kingdom, and further research into their aetiology and treatment is urgently required.

Pulmonary nodules: effect on detection of spiral CT pitch.

PURPOSE: To compare spiral computed tomography (CT) performed at increased pitch with spiral CT performed at standard pitch in the detection of pulmonary nodules. MATERIALS AND METHODS: Spiral CT scanning of the thorax was performed with a pitch of 1.0 in 109 patients with pulmonary nodules due to metastases. The patients were also randomly assigned to undergo further scanning with a pitch of 1.2 (n = 34), 1.5 (n = 37), 2.0 (n = 38) at the same scanning session. The scan pairs were analysed for number, size, and distribution of nodules. RESULTS: A bias toward undercounting was noted on scans with a pitch of 1.5 and 2.0; however, this was not statistically significant. Correlation coefficients were r = .982, r = .977, and r = .989 for scans of pitch 1.2, 1.5, and 2.0, respectively. Disease in one patient would have been prospectively understaged from findings on a scan of pitch 2.0 because of poor conspicuity of a small solitary nodule. CONCLUSION: Findings from scans with increased pitch generally agree well with those from scans with standard pitch; however, there is a greater risk of understaging of disease in patients with solitary nodules as pitch increases. Pitch should be limited to no greater than 1.5 for initial staging of pulmonary metastatic disease.