Hironori Kamano

Simultaneous measurement of arterial transit time, arterial blood volume, and cerebral blood flow using arterial spin-labeling in patients with Alzheimer disease

BACKGROUND AND PURPOSE: Cerebral hemodynamics abnormality in Alzheimer disease (AD) is not fully understood. Our aim was to determine whether regional hypoperfusion due to AD is associated with abnormalities in regional arterial blood volume (rABV) and regional arterial transit time (rATT) as measured by quantitative arterial spin-labeling (ASL) with multiple-delay time sampling. MATERIALS AND METHODS: Nineteen patients with AD (9 men and 10 women; mean age, 74.5 ± 8.6 years) and 22 cognitively healthy control subjects (11 men and 11 women; mean age, 72.8 ± 6.8 years) were studied by using a quantitative ASL method with multiple-delay time sampling. From the ASL data, maps of regional cerebral blood flow (rCBF), rABV, and rATT were generated. A region of hypoperfusion due to AD was determined by statistical parametric mapping (SPM) analysis. Mean rCBF, rABV, and rATT values within the hypoperfused region were compared between the AD and control groups. RESULTS: Despite the significantly lower rCBF (P = .0004) in patients with AD (27.8 ± 7.1 mL/100 g/min) in comparison with control subjects (36.7 ± 6.3 mL/100 g/min), no significant difference in rATT was observed between the control (0.48 ± 0.09 seconds) and AD (0.47 ± 0.10 seconds) groups. Mean rABV was lower in the AD group (0.22 ± 0.10%) than in the control group (0.27 ± 0.12%), though the difference did not reach the level of statistical significance. CONCLUSIONS: Our results revealed that regional hypoperfusion in AD is not associated with rATT prolongation, suggesting that the mechanism of hypoperfusion is distinct from that in cerebrovascular diseases.

Arterial spin labelling at 3-T MR imaging for detection of individuals with Alzheimer’s disease

The purpose of this study was to determine whether arterial spin labelling (ASL) at 3-T MR imaging can be used to discriminate individuals with Alzheimer’s disease (AD) from cognitively normal subjects. Twenty AD patients and 23 cognitively normal control subjects were studied using ASL on a 3-T MR imager. Absolute regional cerebral blood flow (rCBF) maps were calculated. In addition, normalized rCBF maps were obtained using CBF in the sensorimotor cortex for normalization. A voxel-wise comparison of these rCBF maps between the AD and control groups was performed using the two-sample t test. Individuals with AD were discriminated from control subjects based on mean rCBF values within a region-of-interest defined by the t test, and the discriminating performance was evaluated by the receiver operating characteristic (ROC) analysis. Comparisons of both absolute and normalized rCBF maps revealed areas of significant hypoperfusion caused by the effects of AD in the bilateral precunei and posterior cingulate gyri. ROC analyses resulted in area under the curve (AUC) values of 0.861 to 0.877 for absolute and 0.910 to 0.932 for normalized rCBF. Our results suggest that ASL at 3-T MR imaging can be used to help discriminate individuals with AD from normal subjects.

Kyphoplasty and Vertebroplasty Produce the Same Degree of Height Restoration

BACKGROUND AND PURPOSE: There are few comparative studies regarding morphologic changes after kyphoplasty and vertebroplasty. The purpose of this study was to compare restoration of vertebral body height and wedge angle and cement leakage with kyphoplasty and vertebroplasty in osteoporotic compression fractures. MATERIALS AND METHODS: Forty patients (57 vertebrae) were treated with kyphoplasty, and 66 patients (124 vertebrae) were treated with vertebroplasty. Cement leakage into the disk space and paravertebral soft tissues or veins was analyzed on immediate postoperative CT scans. The height and wedge angle were measured before and after treatment and analyzed with the Mann-Whitney U test and χ2 test. RESULTS: Kyphoplasty and vertebroplasty both improved vertebral body height and the wedge angles (P < .05). However, these differences were not statistically significant when the 2 techniques were compared (P > .05). There were 18% of the kyphoplasty group and 49% of the vertebroplasty group that showed cement leakage into the paravertebral soft tissues or veins (P < .01). Cement leakage into the disk space occurred in 12% of the kyphoplasty group and in 25% of the vertebroplasty group (P < .01). However, no complications related to cement leakage were noted. CONCLUSIONS: Both kyphoplasty and vertebroplasty achieved the same degree of height restoration and improvement of the wedge angle. Kyphoplasty resulted in less cement leakage into the disk space and paravertebral soft tissues or veins than vertebroplasty.

Detection of middle ear cholesteatoma by diffusion-weighted MR imaging: multishot echo-planar imaging compared with single-shot echo-planar imaging.

BACKGROUND AND PURPOSE: Previous reports have shown that DWI is useful in detecting cholesteatoma. SS-EPI is the most widely used DWI technique. However, SS-EPI may have susceptibility artifacts due to field inhomogeneity in the imaging of the temporal bone region. Our purpose was to prospectively evaluate the advantage of MS-EPI for the diagnosis of middle ear cholesteatoma by comparing it with SS-EPI. MATERIALS AND METHODS: We studied 29 patients with preoperatively suspected acquired cholesteatoma. Each patient underwent an MR imaging examination including both SS-EPI and MS-EPI by using a 1.5T MR imaging scanner. Images of the 29 patients (58 temporal bones including 30 with and 28 without cholesteatoma) were reviewed by 2 independent neuroradiologists. The confidence level for the presence of cholesteatoma was graded on a scale of 0–2 (0 = none, 1 = equivocal, 2 = definite). Interobserver agreement as well as sensitivity, specificity, and accuracy were assessed for the 2 readers. RESULTS: Excellent interobserver agreement was shown for both MS-EPI (κ = 0.856) and SS-EPI (κ = 0.820). MS-EPI was associated with higher sensitivity (76.7%) and accuracy (87.9%) than SS-EPI (sensitivity = 50.0%, accuracy = 74.1%) (P < .05), while both methods showed 100% specificity. CONCLUSIONS: Compared with SS-EPI, MS-EPI improves the accuracy of the diagnosis of acquired middle ear cholesteatomas.

Volumetric Asymmetry and Differential Aging Effect of the Human Caudate Nucleus in Normal Individuals: A Prospective MR Imaging Study

The purpose of this study was to examine interhemispheric asymmetry in volume of the caudate nucleus and its age dependency.

Usefulness of Cone-Beam CT Before and After Percutaneous Vertebroplasty

OBJECTIVE The usefulness of cone-beam C-arm CT for percutaneous vertebroplasty has not been fully evaluated. The purpose of this study was to assess the feasibility of cone-beam CT for evaluation before and after vertebroplasty. SUBJECTS AND METHODS This prospective study included 22 consecutive patients (15 women and seven men) with osteoporotic compression fractures (51 vertebrae). Cone-beam CT and 64-MDCT were performed before and after percutaneous vertebroplasty. Multiplanar reformations of the axial, sagittal, and coronal planes were obtained. We evaluated the presence of cortical defects, vacuum phenomena in adjacent disks, and cement leakage, and we calculated the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of cone-beam CT compared with MDCT. RESULTS All 75 cortical defects in 51 vertebrae seen on MDCT were also observed on cone-beam CT (100% sensitivity and specificity). Vacuum phenomena were detected in 33 of 86 (38.4%) adjacent disk spaces on MDCT and in 29 on cone-beam CT (84.8% sensitivity, 98.1% specificity, and 93.0% accuracy). Cement leakage was noted at 17 disk spaces, 15 paravertebral soft tissues, and 12 veins on MDCT. All cement leakages were correctly identified on cone-beam CT. CONCLUSION Cone-beam CT is able to correctly evaluate for vertebral fractures and vacuum phenomena in adjacent disks before vertebroplasty and for cement leakage after vertebroplasty.

Arterial spin labeling in patients with chronic cerebral artery steno-occlusive disease: correlation with 15O-PET

Background Heterogeneity of arterial transit time due to cerebral artery steno-occlusive lesions hampers accurate regional cerebral blood flow measurement by arterial spin labeling (ASL). Purpose To assess the feasibility of regional cerebral blood flow measurement by ASL with multiple-delay time sampling in patients with steno-occlusive diseases by comparing with positron emission tomography (PET), and to determine whether regional arterial transit time measured by this ASL technique is correlated with regional mean transit time, a PET index of perfusion pressure. Material and Methods Sixteen patients with steno-occlusive diseases received both ASL and 15O-PET. The mean regional cerebral blood flow measured by ASL and PET, regional arterial transit time by ASL, and regional mean transit time by PET were obtained by a region-of-interest analysis. Correlation between regional cerebral blood flow by ASL and that by PET, and correlation between regional arterial transit time by ASL and regional mean transit time by PET were tested using Pearsons correlation coefficient for both absolute and relative values. A multivariate regression analysis was performed to test whether regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling the effect of regional cerebral blood flow by ASL. Results A significant positive correlation was found between regional cerebral blood flow by ASL and that by PET for both absolute (r = 0.520, P < 0.0001) and relative (r = 0.691, P < 0.0001) values. A significant positive correlation was found between regional arterial transit time by ASL and regional mean transit time by PET both for absolute (r = 0.369, P = 0.0002) and relative (r = 0.443, P < 0.0001) values. The regression analysis revealed that regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling regional cerebral blood flow by ASL (P = 0.0011). Conclusion The feasibility of regional cerebral blood flow measurement using ASL with multiple-delay time sampling was confirmed in patients with cerebral artery steno-occlusive diseases. Moreover, it was suggested that mapping of regional arterial transit time has the potential to detect hemodynamic impairment.

Simultaneous Arterial Spin Labeling Cerebral Blood Flow and Morphological Assessments for Detection of Alzheimer's Disease

RATIONALE AND OBJECTIVES The relative roles of arterial spin-labeling (ASL) perfusion imaging and magnetic resonance morphological assessment in diagnosing Alzheimers disease (AD) have not been established. Our purposes were to directly compare the diagnostic performance of ASL regional cerebral blood flow (rCBF) measurement and that of morphological assessment, and to determine whether or not the combination of the two methods improves diagnostic performance. MATERIALS AND METHODS We analyzed 23 consecutive, retrospectively identified AD patients and 23 healthy control subjects. For each subject, both high-resolution T1-weighted images and ASL perfusion images were obtained. A linear discriminant analysis was performed to distinguish the AD patients from the control subjects based on the three imaging parameters: 1) globally normalized gray matter (GM) density determined by voxel-based morphometry (VBM) procedures, 2) normalized rCBF calculated from ASL data, and 3) the combination of the two. The discriminative abilities of these methods were evaluated by the area under the curve (AUC) derived from receiver-operating characteristics analysis. RESULTS The morphological assessment based on the globally normalized GM density resulted in an AUC of 0.779, whereas ASL-normalized rCBF analysis achieved better performance (AUC = 0.893). The combination of the two methods performed better (AUC = 0.919) than either method alone. CONCLUSION Normalized rCBF measurement by ASL may perform better than morphological analysis based on the VBM procedure in discriminating AD patients from healthy control subjects. The combination of the two approaches was more effective than either method alone.

Contributing factors in the pathogenesis of acquired cholesteatoma: Size analysis based on MDCT

OBJECTIVE The purpose of this article is to explore the factors that contribute to the occurrence of cholesteatoma. We studied the size of the mastoid air cells and the tympanic cavity using high-resolution CT. MATERIALS AND METHODS Temporal bone CT scans of consecutive patients with unilateral cholesteatoma and healthy control subjects were retrospectively analyzed. We compared the total volume and the greatest cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity between the affected and unaffected sides in patients with cholesteatoma and in the control subjects. We also compared separately the measured volumes of the cavities of the mastoid air cells and tympanic cavity between the unaffected side of the patients with cholesteatoma and the control subjects. RESULTS One hundred temporal bones of 50 patients with cholesteatoma and 50 control subjects were included. Both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in the affected side of the patients with cholesteatoma were significantly smaller than those in the unaffected side (p < 0.001). Moreover, both the volume and the cross-sectional area of the cavities of the combined mastoid air cells and tympanic cavity in both affected and unaffected sides of patients with cholesteatoma were significantly smaller than those in control subjects (p < 0.001). The volume of the cavities of the mastoid air cells in the unaffected side of patients with cholesteatoma was smaller than that of the control subjects (p < 0.001). In contrast, no significant difference was found in the tympanic cavity volume between the unaffected side and the control subjects. CONCLUSION Our results were consistent with the hypothesized contribution of mastoid air cell underdevelopment to the occurrence of cholesteatoma. A small tympanic cavity is less likely to contribute to the occurrence of cholesteatoma.

New vertebral compression fractures after prophylactic vertebroplasty in osteoporotic patients.

OBJECTIVE Previous studies have shown the possible efficacy of prophylactic cement injection for nonfractured vertebrae during percutaneous vertebroplasty for compression fractures. The purpose of this study was to investigate risk factors for subsequent fractures after prophylactic percutaneous vertebroplasty. MATERIALS AND METHODS This retrospective study included 116 patients with osteoporotic compression fractures who underwent prophylactic percutaneous vertebroplasty. The patients were monitored with physical examinations and radiographs at 1 day and at 3 and 12 months after percutaneous vertebroplasty, and if back pain recurred. We analyzed the following multiple covariates to determine whether they were associated with recurrence: age, sex, steroid use, and the preoperative number of unhealed or chronic compression fractures. RESULTS Subsequent fractures in any vertebra occurred within 3 months after the procedure at 26 vertebrae in 21 patients (18.1%), and 36 occurred in 28 patients (24.1%) within 12 months. The occurrence of subsequent fractures within 12 months depended on the preoperative number of unhealed vertebrae: the occurrence rate was 16.9% (11/65) for one vertebra, 27.0% (10/37) for two vertebrae, and 50.0% (7/14) for three or more vertebrae. The incidence of subsequent fractures was significantly higher in patients with three or more fractures than in those with one fracture (p < 0.05). There were no statistically significant differences for the other factors. CONCLUSION Patients with three or more fractures tended to have subsequent fractures, despite undergoing prophylactic percutaneous vertebroplasty. However, there was no increased risk of subsequent fractures related to prophylactic percutaneous vertebroplasty.