Differences in microstructural alterations of the hippocampus in Alzheimer disease and idiopathic normal pressure hydrocephalus: a diffusion tensor imaging study.

BACKGROUND AND PURPOSE: DTI can be used to assess the degradation of WM tracts by measuring the FA and MD. Decreased FA/increased MD values in the AD hippocampus have been reported by many studies. In contrast, only a few studies reported on hydrocephalus by using the DTI technique. In elderly patients with dementia and with dilated ventricles, it is often difficult to differentiate iNPH from AD with visual measurements on MR imaging. The aim of this study was to investigate the changes of microstructural integrity of the hippocampus in iNPH by using DTI and determining whether this method could be a new diagnostic tool to differentiate iNPH from AD. MATERIALS AND METHODS: We recruited 43 participants (15 healthy controls, 15 patients with AD, and 13 patients with iNPH). The FA and MD values were measured by using the region-of-interest method in the hippocampal head, body, and tail on both sides. Clinical history, neurologic examination, and neuropsychological assessment were included. RESULTS: The FA values were the lowest in the patients with AD, the patients with iNPH, and the healthy controls in this order. The MD values were the highest in the same order. These findings were consistent in the 3 subdivisions of the bilateral hippocampal regions. Hippocampal volume was not different between patients with iNPH and AD. CONCLUSIONS: The microstructural alterations of the hippocampus were more sensitive than the volumetric changes in AD and iNPH. DTI analysis might be a useful tool for discriminating AD from iNPH.

Impaired kidney function and cerebral microbleeds in patients with acute ischemic stroke.

BACKGROUND: We investigated the association between the presence of cerebral microbleeds and poor kidney function in patients with acute ischemic stroke. METHODS: We retrospectively examined consecutive acute ischemic stroke patients who underwent gradient echo MRI. The presence of cerebral microbleeds on gradient echo MRI was independently interpreted. The number and location of microbleeds were assessed. Demographics including age, sex, risk factors, and stroke subtype were obtained. Kidney function was estimated by measuring glomerular filtration rate (GFR) with the modification of diet in renal disease method. RESULTS: Of the 152 patients included, 45 (29.6%) patients had cerebral microbleeds on gradient echo MRI. The cerebral microbleeds were most commonly located in deep or infratentorial location (27/45 [60%]). Hypertension, presence of leukoaraiosis, old age, and low GFR were associated with the presence of cerebral microbleeds (p = 0.064, <0.001, 0.014, and <0.001). The mean GFR levels were lower in patients with cerebral microbleeds (65.15 +/- 22.54 vs 78.82 +/- 19.11 mL/min/1.73 m(2)). After the adjustment of risk factors, age, and sex, low GFR levels were associated with the presence of cerebral microbleeds (odds ratio, 3.85; 95% confidence interval, 1.52 to 9.76, p = 0.004). CONCLUSION: Impaired kidney function is associated with the presence of cerebral microbleeds in acute ischemic stroke.

Rapid appearance of new cerebral microbleeds after acute ischemic stroke.

BACKGROUND: It is unknown whether the development of cerebral microbleeds (MBs), small areas of signal loss on T2*-weighted gradient-echo imaging (GRE), follows a slow or a rapid process. We hypothesized that MBs may develop rapidly after certain critical events, such as strokes, and investigated the frequency, location, and factors associated with the formation of new MBs after acute ischemic stroke. METHODS: We retrospectively examined 237 consecutive acute ischemic stroke patients who underwent MRI within 24 hours and follow-up MRI during the week after symptom onset. We defined new MBs as MBs that newly appeared on follow-up GRE outside the infarcted area. We examined the association of new MBs with demographics, risk factors, laboratory data, baseline MBs, and small vessel disease (SVD; leukoaraiosis and lacunar infarctions). RESULTS: Seventy-five patients (31.6%) had baseline MBs, and 30 (12.7%) developed new MBs. Multiple logistic regression analysis indicated that the presence of baseline MBs (odds ratio [OR] 5.72, 95% confidence interval [CI] 2.12-15.42, p = 0.001) and severe SVD (OR 2.94, 95% CI 1.12-7.77, p = 0.03) independently predicted the development of new MBs. Of the 56 new MBs, 29 (51.8%) appeared in the lobar location, 17 (30.4%) appeared in the deep location, and 10 (17.9%) appeared in the infratentorial location. CONCLUSIONS: This study suggests that new microbleeds (MBs) can develop rapidly after acute ischemic stroke. Baseline MBs and severe small vessel disease are predictors for the development of new MBs. Further studies will be needed to investigate the clinical implications and mechanisms of these findings.

MRI evidence of reperfusion injury associated with neurological deficits after carotid revascularization procedures.

BACKGROUND AND PURPOSE: Some patients develop major neurological complications after carotid revascularization procedures, despite the lack of new infarcts or classical hyperperfusion syndrome. METHODS: In four patients who developed major neurological deficits after carotid revascularization procedures, but without evidence of new ischemic infarcts or hyperperfusion, we performed post-procedural MRI [diffusion-weighted image (DWI), perfusion-weighted image (PWI), pre-and post-contrast fluid-attenuated inversion recovery (FLAIR) image] immediately after and 1 day after the procedure. RESULTS: Post-gadolinium FLAIR images on 1 day after the procedures showed prominent leptomeningeal enhancements in the revascularized hemispheres. These radiological findings disappeared on follow-up FLAIR images accompanied by the clinical improvement over the following several days after the procedures. CONCLUSION: Reperfusion syndrome may be associated with transient severe neurological deficits after carotid revascularization in patients without new ischemic events or classical hyperperfusion syndrome.

High prevalence of unrecognized cerebral infarcts in first-ever stroke patients with cardioembolic sources.

BACKGROUND: With magnetic resonance imaging (MRI) analysis, we investigated the prevalence, clinical significance, and factors related to the presence of unrecognized cerebral infarcts in patients with first-ever ischaemic stroke. METHODS: We consecutively included patients who were admitted with first-ever stroke. Unrecognized cerebral infarct was defined as an ischaemic infarction or primary intracerebral hemorrhage on MRI irrelevant to the index stroke, without acute lesions on diffusion-weighted image. RESULTS: Of the total 203 patients, 78 (39.4%) patients were observed as having unrecognized cerebral infarct. Patients with high-risk cardioembolic sources (e.g., atrial fibrillation) more frequently had unrecognized stroke than those without (P = 0.008, 21/36 [58.3%] vs. 57/167 [34.1%]). On univariate analysis, male sex (P = 0.027) and cardioembolic source (P = 0.008) were associated with the presence of unrecognized cerebral infarcts. After adjustment for gender, age and risk factors, the presence of cardioembolic sources independently increased the risk of unrecognized cerebral infarct (P = 0.002, odds ratio 3.56, 95% confidence interval 1.58-8.02). Regarding clinical outcome at 3 months, the presence of unrecognized cerebral infarct was not associated with the poor clinical outcome. CONCLUSION: In our study, the presence of cardioembolic sources was an independent risk factor for the unrecognized cerebral infarct in patients with first-ever stroke.