PubMed Health⌕ Search

Biomedical subjects

Ritva L Vanninen

Publications and source records attributed to Ritva L Vanninen.

8 recordsLinked to original sources
PubMed2006

Subarachnoid hemorrhage in the subacute stage: elevated apparent diffusion coefficient in normal-appearing brain tissue after treatment.

PURPOSE: To prospectively evaluate whether subarachnoid hemorrhage (SAH) is associated with a change in the apparent diffusion coefficient (ADC) in normal-appearing brain parenchyma. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for all patient and volunteer studies. One hundred patients (48 men, 52 women; mean age, 52 years +/- 12 [standard deviation]) with aneurysmal SAH underwent conventional and diffusion-weighted magnetic resonance (MR) imaging at a mean of 9 days +/- 3 after SAH to evaluate possible lesions caused by SAH, treatment of SAH, and vasospasm. Aneurysms were treated surgically (n = 70) or endovascularly (n = 30) before MR imaging. Diffusion-weighted MR imaging was performed at 1-year follow-up in 30 patients (10 men, 20 women; mean age, 51 years +/- 11). Thirty healthy age-matched volunteers (11 men, 19 women; mean age, 54 years +/- 16) underwent MR imaging with an identical protocol. ADC values were measured bilaterally in the gray and white matter (parietal, frontal, temporal, occipital lobes; cerebellum; caudate nucleus; lentiform nucleus; thalamus; and pons) that appeared normal on T2-weighted and diffusion-weighted MR images. Linear mixed model was used for comparison of ADC values of supratentorial gray matter and white matter; general linear regression analysis was used for comparison of ADC values of cerebellum and pons. RESULTS: In patients with SAH, the ADC values in normal-appearing white matter, with a single exception in the frontal lobe (P = .091), were significantly higher than they were in healthy volunteers (P </= .011). The differences disappeared by 1 year, except in parietal white matter (P = .045). The ADC values of cortical gray matter did not significantly differ between patients and volunteers (P >/= .121). CONCLUSION: SAH and its treatment may cause global mild vasogenic edema in white matter and deep gray matter that is undetectable on T2-weighted and diffusion-weighted MR images but is detectable by measuring the ADC value in the subacute stage of SAH.

Adult↗
PubMed2006

Increased fMRI responses during encoding in mild cognitive impairment.

Structural and functional magnetic resonance imaging (fMRI) was performed on 21 healthy elderly controls, 14 subjects with mild cognitive impairment (MCI) and 15 patients with mild Alzheimer's disease (AD) to investigate changes in fMRI activation in relation to underlying structural atrophy. The fMRI paradigm consisted of associative encoding of novel picture-word pairs. Structural analysis of the brain was performed using voxel-based morphometry (VBM) and hippocampal volumetry. Compared to controls, the MCI subjects exhibited increased fMRI responses in the posterior hippocampal, parahippocampal and fusiform regions, while VBM revealed more atrophy in MCI in the anterior parts of the left hippocampus. Furthermore, the hippocampal volume and parahippocampal activation were negatively correlated in MCI, but not in controls or in AD. We suggest that the increased fMRI activation in MCI in the posterior medial temporal and closely connected fusiform regions is compensatory due to the incipient atrophy in the anterior medial temporal lobe.

Aged↗
PubMed2004

Acute ischemic stroke: predictive value of 2D phase-contrast MR angiography--serial study with combined diffusion and perfusion MR imaging.

PURPOSE: To evaluate phase-contrast magnetic resonance (MR) angiography and diffusion- and perfusion-weighted imaging in predicting evolution of infarction and clinical outcome. MATERIALS AND METHODS: Phase-contrast angiographic and diffusion-weighted images obtained 1 and 2 days after acute middle cerebral artery (MCA) stroke were assessed in 43 patients; 39 underwent perfusion-weighted imaging on day 1. Follow-up phase-contrast angiographic and T2-weighted images (n = 38) were obtained on day 8. Clinical outcome was assessed at 3 months. Patients were assigned to three groups according to angiographic findings on day 1: group 1, absence of flow in proximal MCA (M1 segment); group 2, internal carotid artery (ICA) occlusion with collateral M1 flow; group 3, flow in ICA and M1. Differences in lesion volumes on diffusion- and perfusion-weighted maps among groups were compared with one-way analysis of variance with Tukey post hoc multiple comparisons. RESULTS: Patients in group 1 had significantly larger infarct growth, volumes of hypoperfusion on relative cerebral blood volume (rCBV) and relative cerebral blood flow maps, and initial and final infarct volumes than did other patients (P <.05). Initial perfusion deficits on mean transit time maps were significantly (P =.002) larger in group 2 than in group 3, but there were no significant differences in infarct growth (P =.977), final infarct volume on day 8 (P =.947), and clinical outcome (P =.969). Absence of M1 flow on day 1 was significantly associated with unfavorable clinical outcome (modified Rankin score > or = 3) at 3 months (P =.010, chi(2) test). Discriminant analysis revealed that rCBV maps alone and combination of diffusion-weighted imaging and MR angiography yielded the highest accuracy in predicting an unfavorable clinical outcome. CONCLUSION: Phase-contrast MR angiography can provide complementary information to that with diffusion- and perfusion- weighted imaging in predicting the outcome of patients with acute stroke.

Aged↗
PubMed2003

Carotid artery stenosis: reproducibility of automated 3D CT angiography analysis method.

The aim of this study was to assess the reproducibility and anatomical accuracy of automated 3D CT angiography analysis software in the evaluation of carotid artery stenosis with reference to rotational DSA (rDSA). Seventy-two vessels in 36 patients with symptomatic carotid stenosis were evaluated by 3D CT angiography and conventional DSA (cDSA). Thirty-one patients also underwent rotational 3D DSA (rDSA). Multislice CT was performed with bolus tracking and slice thickness of 1.5 mm (1-mm collimation, table feed 5 mm/s) and reconstruction interval of 1.0 mm. Two observers independently performed the stenosis measurements on 3D CTA and on MPR rDSA according to the NASCET criteria. The first measurements on CTA utilized an analysis program with automatic stenosis recognition and quantitation. In the subsequent measurements, manual corrections were applied when necessary. Interfering factors for stenosis quantitation, such as calcifications, ulcerations, and adjacent vessels, were registered. Intraobserver and interobserver correlation for CTA were 0.89 and 0.90, respectively (p<0.001). The interobserver correlation between two observers for MPR rDSA was 0.90 (p<0.001). The intertechnique correlation between CTA and rDSA was 0.69 (p<0.001) using automated measurements but increased to 0.81 (p<0.001) with the manually corrected measurements. Automated stenosis recognition achieved a markedly poorer correlation with MPR rDSA in carotids with interfering factors than those in cases where there were no such factors. Automated 3D CT angiography analysis methods are highly reproducible. Manually corrected measurements facilitated avoidance of the interfering factors, such as ulcerations, calcifications, and adjacent vessels, and thus increased anatomical accuracy of arterial delineation by automated CT angiography with reference to MPR rDSA.

Aged↗
PubMed2002

Apolipoprotein E polymorphism and acute ischemic stroke: a diffusion- and perfusion-weighted magnetic resonance imaging study.

Diffusion- and perfusion-weighted magnetic resonance imaging (MRI) was used to study the putative effects of apolipoprotein E (ApoE) polymorphism in stroke. Thirty-one patients with acute stroke, comparative for age and gender were scanned, nine of whom were ApoE allele epsilon 4 carriers. Initially, less than 24 hours from the onset of stroke, the epsilon 4 carriers had significantly smaller volumes of hypoperfusion on relative cerebral blood volume map (P = 0.001), and smaller infarct volumes (P = 0.008) compared with the noncarriers. By day 8, this difference in the infarct volumes had disappeared, suggesting relatively enhanced infarct growth. On average, the total infarct volume increased 145% of the initial infarct volume in the epsilon 4 carriers, and 84% in the noncarriers. There were strong correlations between the imaging findings and clinical status initially and with the outcome 3 months after the stroke in the epsilon 4 noncarriers, but, with a single exception at acute phase, a lack thereof in the epsilon 4 carriers. These patterns were virtually similar in a subgroup of patients with middle cerebral artery stroke. These data support the hypothesis of increased general vulnerability of the brain in the epsilon 4 carriers. Thus, the effects of ApoE polymorphism should be accounted for when interpreting diffusion- and perfusion-weighted MRI studies, particularly if predicting lesion growth.

Acute Disease↗
PubMed2002

Patients with acute flank pain: comparison of MR urography with unenhanced helical CT.

PURPOSE: To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis. MATERIALS AND METHODS: Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results. RESULTS: At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004). CONCLUSION: In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.

Acute Disease↗
PubMedDate not supplied

Onyx, a new liquid embolic material for peripheral interventions: preliminary experience in aneurysm, pseudoaneurysm, and pulmonary arteriovenous malformation embolization.

PURPOSE: To describe our preliminary experience with a new liquid embolization agent, Onyx, in peripheral interventions. METHODS AND RESULTS: We successfully treated two peripheral aneurysms (one in an internal iliac artery, one in a thoracic collateral artery of an aortic coarctation), two peripheral pseudoaneurysms (one in a lumbar artery, one in a renal artery), and one pulmonary arteriovenous malformation. CONCLUSION: Onyx is a promising alternative embolic material for peripheral interventions. It can be combined with coils in selected cases, and balloon catheters can be effectively used during slow injection of embolic material to control flow and protect the aneurysm neck.

Aged↗