Can MRI Visual Assessment Differentiate the Variants of Primary-Progressive Aphasia?

BACKGROUND AND PURPOSE: Primary-progressive aphasia is a clinically and pathologically heterogeneous condition. Nonfluent, semantic, and logopenic are the currently recognized clinical variants. The recommendations for the classification of primary-progressive aphasia have advocated variant-specific patterns of atrophy. The aims of the present study were to evaluate the sensitivity and specificity of the proposed imaging criteria and to assess the intra- and interrater reporting agreements. MATERIALS AND METHODS: The cohort comprised 51 patients with a root diagnosis of primary-progressive aphasia, 25 patients with typical Alzheimer disease, and 26 matched control participants. Group-level analysis (voxel-based morphometry) confirmed the proposed atrophy patterns for the 3 syndromes. The individual T1-weighted anatomic images were reported by 3 senior neuroradiologists. RESULTS: We observed a dichotomized pattern of high sensitivity (92%) and specificity (93%) for the proposed atrophy pattern of semantic-variant primary-progressive aphasia and low sensitivity (21% for nonfluent-variant primary-progressive aphasia and 43% for logopenic-variant primary-progressive aphasia) but high specificity (91% for nonfluent-variant primary-progressive aphasia and 95% for logopenic-variant primary-progressive aphasia) in other primary-progressive aphasia variants and Alzheimer disease (sensitivity 43%, specificity 92%). MR imaging was least sensitive for the diagnosis of nonfluent-variant primary-progressive aphasia. Intrarater agreement analysis showed mean κ values above the widely accepted threshold of 0.6 (mean, 0.63 ± 0.16). Pair-wise interobserver agreement outcomes, however, were well below this threshold in 5 of the 6 possible interrater contrasts (mean, 0.41 ± 0.09). CONCLUSIONS: While the group-level results were in precise agreement with the recommendations, semantic-variant primary-progressive aphasia was the only subtype for which the proposed recommendations were both sensitive and specific at an individual level.

Utility of an ultrafast magnetic resonance imaging protocol in recent and semi-recent strokes.

OBJECTIVE: To evaluate the technical feasibility of an integrated ultrafast head magnetic resonance (MR) protocol using a sensitivity encoding (SENSE) technique for depicting parenchymal ischaemia and vascular compromise in patients with suspected recent stroke. METHODS: 23 patients were evaluated with the ultrafast MR protocol using T2, T1, fluid attenuated inversion recovery (FLAIR), 3D time of flight magnetic resonance angiography (MRA), and diffusion weighted imaging (DWI) sequences. These were compared with routine conventional MR sequences. RESULTS: One patient could not tolerate conventional imaging, although imaging using the three minute head SENSE protocol was diagnostic. Both conventional and ultrafast protocols were of similar diagnostic yield in the remaining patients. There were no significant differences in clinical diagnostic quality for the T1, T2, FLAIR, and DWI sequences. One MRA examination was of better quality when SENSE was used, owing to reduced motion artefacts and shorter imaging time. CONCLUSIONS: It is possible to undertake a comprehensive MR examination in stroke patients in approximately three to five minutes. Ultrafast imaging may become a useful triage tool before thrombolytic therapy. It may be of particular benefit in patients unable to tolerate longer sequences. Further work is necessary to confirm these findings in hyperacute stroke.

Assessment of quantitative computed tomographic cerebral perfusion imaging with H2(15)O positron emission tomography.

Assessment of quantitative cerebral blood flow on a conventional fast CT machine without the use of specialized equipment may be valuable in the investigation of acute stroke and head injury. We aimed to compare a single slice CT perfusion sequence with H2(15)O positron emission tomography using the sagittal sinus as an input function, a method that avoids unnecessary orbital irradiation. Eight patients were studied, two patients with gliomas, and six with arteriovenous malformations. The dynamic CT perfusion sequence was performed by acquiring the same 10 mm slice 10 times over 30 sec during a 50 ml bolus of intravenous contrast medium given at a rate of 7.5 ml sec-1 using a power injector. The CT perfusion studies were completed without complication. Co-registration was sub-optimal in one patient. Overall the correlation between the two methodologies was encouraging with an average r2 value of 0.524 for individual analyses. When two patients with high flow arteriovenous malformations were excluded the average r2 value increased to 0.640. The results of this CT perfusion methodology are encouraging. Having shown its feasibility, further studies in conditions with lower rates of cerebral blood flow are warranted.

Digital radiology in skeletal trauma: assessment of casualty officers' performance.

Radiographic images can now be produced without the requirement of film processing and development, and can be displayed rapidly on a computer monitor. We assessed junior doctors' performance in interpreting images from 25 patients being investigated for possible fracture and also compared the diagnostic abilities of casualty officers with those of radiology specialist registrars. For interpretation of images viewed at a workstation or as filmed laser images, respectively, sensitivities were 75% and 78%, and specificities were 65% and 76%. These differences were not significant. There was a tendency for radiology specialist registrars to be less specific when reviewing images at a workstation. The demonstration that there is no loss in diagnostic quality when casualty officers interpret fracture images in a purely digitally acquired and viewed format forms a robust basis for economic evaluation of the technology.

Intracranial assessment of incontinentia pigmenti using magnetic resonance imaging, angiography, and spectroscopic imaging.

OBJECTIVE: To evaluate patients with incontinentia pigmenti for evidence of cerebrovascular disease using magnetic resonance imaging techniques. DESIGN: A prospective case series of seven patients (four of whom were related) with incontinentia pigmenti using magnetic resonance imaging, magnetic resonance angiography, and multislice proton (1H) magnetic resonance spectroscopic imaging. SETTING: The Johns Hopkins Medical Institutions, Baltimore, Md, a tertiary, referred care center. PATIENTS: Seven patients with a diagnosis of incontinentia pigmenti. RESULTS: Five of the seven patients had abnormal magnetic resonance imaging consistent with small-vessel occlusions. Of these five patients, four had normal magnetic resonance angiography and spectroscopic imaging, and one patient had reduced middle cerebral artery flow on magnetic resonance angiography and increased lactate level in the cerebrospinal fluid on spectroscopic imaging. The remaining two patients had normal magnetic resonance imaging and spectroscopic imaging. Of these two patients, one had normal magnetic resonance angiography and the other had a right supraclinoid internal carotid aneurysm. There was substantial concordance between clinical (ophthalmic/neurologic) and imaging abnormalities. CONCLUSIONS: The central nervous system changes in patients with incontinentia pigmenti may represent the result of small-vessel occlusive phenomena in the brain. These central nervous system findings may share a common pathophysiologic state with the vascular occlusive disease seen in the retinas of these patients. The changes in the retinal vasculature may serve as a potential marker for central nervous system disease. Physicians should be aware of the systemic and debilitating nature of incontinentia pigmenti.