Akio Hiwatashi

Perfusion Imaging of Brain Tumors Using Arterial Spin-Labeling : Correlation with Histopathologic Vascular Density

BACKGROUND AND PURPOSE: We investigated the relationship between tumor blood-flow measurement based on perfusion imaging by arterial spin-labeling (ASL-PI) and histopathologic findings in brain tumors. MATERIALS AND METHODS: We used ASL-PI to examine 35 patients with brain tumors, including 11 gliomas, 9 meningiomas, 9 schwannomas, 1 diffuse large B-cell lymphoma, 4 hemangioblastomas, and 1 metastatic brain tumor. As an index of tumor perfusion, the relative signal intensity (SI) of each tumor (%Signal intensity) was determined as a percentage of the maximal SI within the tumor per averaged SI within normal cerebral gray matter on ASL-PI. Relative vascular attenuation (%Vessel) was determined as the total microvessel area per the entire tissue area on CD-34–immunostained histopathologic specimens. MIB1 indices of gliomas were also calculated. The differences in %Signal intensity among different histopathologic types and between high- and low-grade gliomas were compared. In addition, the correlations between %Signal intensity and %Vessel or MIB1 index were evaluated in gliomas. RESULTS: Statistically significant differences in %Signal intensity were observed between hemangioblastomas versus gliomas (P < .005), meningiomas (P < .05), and schwannomas (P < .005). Among gliomas, %Signal intensity was significantly higher for high-grade than for low-grade tumors (P < .05). Correlation analyses revealed significant positive correlations between %Signal intensity and %Vessel in 35 patients, including all 6 histopathologic types (rs = 0.782, P < .00005) and in gliomas (rs = 0.773, P < .05). In addition, in gliomas, %Signal intensity and MIB1 index were significantly positively correlated (rs = 0.700, P < .05). CONCLUSION: ASL-PI may predict histopathologic vascular densities of brain tumors and may be useful in distinguishing between high- and low-grade gliomas and in differentiating hemangioblastomas from other brain tumors.

Amide proton transfer imaging of adult diffuse gliomas: correlation with histopathological grades.

BACKGROUND Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas. METHODS Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1 ± 14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets ω = -6 to +6 ppm (step 0.5 ppm). δB0 maps were acquired separately for a point-by-point δB0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR)asym = (S[-3.5 ppm] - S[+3.5 ppm])/S0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density. RESULTS The mean APT SI values were 2.1 ± 0.4% in grade II gliomas (n = 8), 3.2 ± 0.9% in grade III gliomas (n = 10), and 4.1 ± 1.0% in grade IV gliomas (n = 18). Significant differences in APT intensity were observed between grades II and III (P < .05) and grades III and IV (P < .05), as well as between grades II and IV (P < .001). There were positive correlations between APT SI and Ki-67 LI (P = .01, R = 0.43) and between APT SI and cell density (P < .05, R = 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P < .001). CONCLUSIONS APT imaging can predict the histopathological grades of adult diffuse gliomas.

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.

Regional gray and white matter volume abnormalities in obsessive-compulsive disorder: A voxel-based morphometry study

Previous studies have demonstrated both functional and structural abnormalities in the frontal-striatal-thalamic circuits in obsessive-compulsive disorder (OCD). The purpose of this study was to assess volume abnormalities not only of gray matter (GM), but also of white matter (WM) in patients with OCD using voxel-based morphometry (VBM). Subjects consisted of 23 patients with OCD and 26 normal control subjects. All patients were drug-free for at least 2 weeks before the study. Three-dimensional T1-weighed MR images were obtained in all subjects. Optimized voxel-based morphometry was performed to detect structural difference between the two groups. The patients with OCD demonstrated a significant reduction of GM volume in the bilateral medial prefrontal cortex, right premotor area, right orbitofrontal cortex (OFC), right dorsolateral prefrontal cortex, and bilateral temporal and occipital regions. The OCD patients also showed a significant WM volume increase in the right anterior limb of the internal capsule, right orbitofrontal region, and a significant WM volume reduction in the left anterior cingulate gyrus. Our findings are consistent with previous studies implicating dysfunction of the frontal cortex including the OFC. The results suggested that WM volume abnormalities in the orbitofrontal region, anterior limb of the internal capsule, and anterior cingulate gyrus would imply abnormalities in the pathways of frontal-striatal circuits.

CT and MRI findings of human herpesvirus 6-associated encephalopathy: comparison with findings of herpes simplex virus encephalitis.

OBJECTIVE It is important to differentiate human herpesvirus 6 (HHV-6)-associated encephalopathy from herpes simplex encephalitis (HSE). Although these conditions are similar with regard to involvement of the mesial temporal lobe, HSE is sensitive to acyclovir but HHV-6 encephalopathy is not. We compared the imaging findings of the two conditions. MATERIALS AND METHODS We encountered eight cases of HHV-6 encephalopathy and nine cases of HSE. We divided an observation time into early, middle, and late periods defined as 0-2, 3-30, and more than 30 days from the onset of neurologic symptoms. Differences between HHV-6 encephalopathy and HSE on CT scans in the early period and in distribution and temporal changes in the affected regions on MR images in the three periods were analyzed. RESULTS At MRI in the early and middle periods, all eight patients with HHV-6 encephalopathy had exclusive involvement of the mesial temporal lobes, and all nine patients with HSE had involvement of both the mesial temporal lobes and the extratemporal regions (p < 0.01). Among patients who underwent head MRI, six of six with HHV-6 encephalopathy but none of six with HSE had resolution of high signal intensity on T2-weighted and FLAIR images (p < 0.01). Among patients who underwent head CT in the early period, none of the four with HHV-6 encephalopathy and six of the seven with HSE had abnormal findings, including parenchymal swelling, decreased attenuation of affected regions, and abnormal gyral enhancement (p < 0.05). CONCLUSION Serial MRI showed transient abnormal signal intensity in the mesial temporal lobes in patients with HHV-6 encephalopathy but persistent abnormal signal intensity in both the mesial temporal lobes and the extratemporal regions in patients with HSE. CT in the early period showed no abnormality in patients with HHV-6 encephalopathy but definite abnormal findings in patients with HSE. These differences may be useful in the differential diagnosis of the two conditions.

Characterization of IgG4 anti-neurofascin 155 antibody-positive polyneuropathy.

To investigate anti‐neurofascin 155 (NF155) antibody‐positive chronic inflammatory demyelinating polyneuropathy (CIDP).

Cement Leakage During Vertebroplasty Can Be Predicted on Preoperative MRI

OBJECTIVE Previous studies have shown that cement leakage into an adjacent disk space is a risk factor for new fracture after vertebroplasty. The purpose of this study was to investigate the use of preoperative MRI for predicting such cement leakage. MATERIALS AND METHODS Our institutional review board approved this retrospective study and waived the requirement of informed consent. We studied preoperative MRI of 46 vertebroplasty patients (107 vertebral bodies). Endplate cortical defect, abnormal T2 hyperintensity in adjacent disk space, intravertebral cleft, degree of compression, and wedge angle were correlated to the incidence of cement leakage into the adjacent disk. Patient age, sex, and location of treated vertebral body were also evaluated. We used logistic regression analysis and Fishers exact probability test to analyze the association between cement leakage and these observations. RESULTS Cortical defect in the endplate of the treated vertebral body, abnormal T2 hyperintensity in the adjacent intervertebral disk, and absence of intravertebral cleft were associated with cement leakage into the disk space (p < 0.05). There was no statistically significant association between cement leakage into the disk and degree of compression, wedge angle, location of treated vertebral body, patient age, or sex (p > 0.05). CONCLUSION Cement leakage into an adjacent disk is more common when there is a cortical defect in the endplate and increased T2 signal in the adjacent disk and is less common if there is an intravertebral cleft.

MRI of Glossopharyngeal Neuralgia Caused by Neurovascular Compression

OBJECTIVE Glossopharyngeal neuralgia is rare but causes severe pain. We retrospectively evaluated preoperative MR images of patients with glossopharyngeal neuralgia caused by neurovascular compression. CONCLUSION MRI may be beneficial in patients with glossopharyngeal neuralgia and an offending compressing artery. If the offending vessel was the posterior inferior cerebellar artery (PICA), a loop formation at the supraolivary fossette was always seen, whereas if it was the anterior inferior cerebellar artery (AICA), glossopharyngeal neuralgia was difficult to diagnose before surgery.