Miyuki Takasu

Diffusion tensor imaging of peripheral nerve in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a feasibility study

IntroductionThe purpose of this study was to assess the clinical feasibility of diffusion tensor imaging (DTI) for the evaluation of peripheral nerves in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).MethodsUsing a 3-T magnetic resonance imaging scanner, we obtained DTI scans of the tibial nerves of 10 CIDP patients and 10 sex- and age-matched healthy volunteers. We prepared fractional anisotropy (FA) maps, measured the FA values of tibial nerves, and compared these values in the two study groups. In nine patients, we also performed tibial nerve conduction studies and analyzed the correlation between the FA values and parameters of the nerve conduction study.ResultsThe tibial nerve FA values in CIDP patients (median 0.401, range 0.312–0.510) were significantly lower than those in healthy volunteers (median 0.530, range 0.469–0.647) (Mann–Whitney test, p < 0.01). They were significantly correlated with the amplitude of action potential (Spearman correlation coefficient, p = 0.04, r = 0.86) but not with nerve conduction velocity (p = 0.79, r = 0.11).ConclusionOur preliminary data suggest that the noninvasive DTI assessment of peripheral nerves may provide useful information in patients with CIDP.

Effect of age on the fractional anisotropy (FA) value of peripheral nerves and clinical significance of the age-corrected FA value for evaluating polyneuropathies

IntroductionWe investigated the correlation between age and the fractional anisotropy (FA) values of peripheral nerves in healthy adults and compared the age-corrected FA values of peripheral nerves in healthy subjects and patients with polyneuropathy.MethodsThe institutional review board approved this study and informed consent was obtained from all participants before entry into the study. We optimized diffusion tensor imaging using a 3-T magnetic resonance scanner and an extremity coil for scanning tibial nerves. The effect of age and sex on the FA values of tibial nerves in healthy volunteers was investigated and the age-corrected FA values of tibial nerves in healthy volunteers and patients with polyneuropathy were compared.ResultsThe maximum FA values of the tibial nerves remained constant until age 45 (approximately 0.516); they subsequently decreased by 0.004/year in healthy volunteers. After removing the effect of age with an age-adjusted equation, the median maximum FA values in the volunteers and patients were 0.518 (range, 0.406–0.616) and 0.442 (range, 0.376–0.530), respectively. The age-corrected FA values were significantly lower in the patients than the healthy volunteers (p < 0.001). There was no significant gender-related difference in the maximum FA values of the tibial nerves (p = 0.416).ConclusionThe age-corrected FA value of the peripheral nerves helps to differentiate between age-related peripheral nerve degeneration and polyneuropathies.

Multiple Myeloma: Microstructural Analysis of Lumbar Trabecular Bones in Patients without Visible Bone Lesions—Preliminary Results

PURPOSE To evaluate the accuracy of trabecular analysis of the lumbar spine by using multidetector computed tomography (CT) in differentiating multiple myeloma patients without spinal fractures from control subjects. MATERIALS AND METHODS This retrospective single-institution study was approved by the institutional review board, with a waiver of informed consent. Spinal microarchitecture was examined by using 64-detector row CT in 29 patients with multiple myeloma and 51 control subjects. The patients were 13 men and 16 women (mean ages, 71.1 and 69.2 years, respectively). By using multidetector CT data, eight parameters were calculated for the L3 vertebral trabeculae with a three-dimensional image analysis system. The χ(2) test was used to select a preliminary set of predictors for multiple myeloma. A multivariable generalized linear model was constructed to identify parameters that could be used to differentiate between patients and controls. Parameters with findings of P < .05 were included in the multivariable model. RESULTS Generalized linear models showed that mean trabecular thickness (TbTh) (patients, 703.7 μm ± 46.7 [standard deviation]; controls, 661.1 μm ± 35.7) and fractal dimension (FD) (patients, 2.23 ± 0.24; controls, 2.41 ± 0.15) in men (P = .05 and .03, respectively) and degree of anisotropy (DA) (patients, 1.63 ± 0.23; controls, 1.38 ± 0.10) in women (P = .02) had significant effects in differentiation between patients and controls. CONCLUSION Significant differences were observed in spinal microarchitecture between control subjects and multiple myeloma patients without pathologic fractures. Independent predictors of multiple myeloma included TbTh and FD in male patients and DA in female patients.

Evaluation of lumber nerve root compression using thin-slice thickness coronal magnetic resonance imaging: three-dimensional fat-suppressed multi-shot balanced non-steady-state free precession versus threedimensional T1-weighted spoiled gradient-recalled echo

PurposeThe aim of this study was to compare the three-dimensional fat-suppressed balanced non-steady-state free precession (3D FS-nSSFP) sequence and the 3D T1-weighted spoiled gradient-recalled echo (3D T1-GRE) sequence for evaluating lumbar nerve root compression with continuous thin-slice coronal magnetic resonance (MR) images.Materials and methodsThe institutional review board approved this study, and written informed consent was obtained from all 35 patients. We optimized continuous 2.5-mm thick lumbar coronal images with 3D FS-nSSFP and 3D T1-GRE. We calculated the contrast-to-noise ratio (CNR) for nerve roots and other structures on images with the two sequences. With knowledge of the final diagnosis, we assessed the visibility of nerve root compression on these images.ResultsThe CNR values of nerve roots were significantly higher on images with 3D FS-nSSFP than on those with 3D T1-GRE. These continuous thin-slice coronal images facilitated visualization of nerve root compression in >91% of patients. There was no statistically significant difference between the two sequences in the detection of nerve root compression.ConclusionContinuous thin-slice coronal MR images using 3D FS-nSSFP and 3D T1-GRE sequences are sufficient to evaluate lumbar nerve root compression, and 3D FS-nSSFP is superior to 3D T1-GRE for depiction of lumbar nerve roots.

Magnetic Resonance Evaluation of Multiple Myeloma at 3.0 Tesla: How Do Bone Marrow Plasma Cell Percentage and Selection of Protocols Affect Lesion Conspicuity?

Purpose To compare various pulse sequences in terms of percent contrast and contrast-to-noise ratio (CNR) for detection of focal multiple myeloma lesions and to assess the dependence of lesion conspicuity on the bone marrow plasma cell percent (BMPC%). Materials and Methods Sagittal T1-weighted FSE, fat-suppressed T2-weighted FSE (FS- T2 FSE), fast STIR and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging of the lumbar spine were performed (n = 45). Bone marrow (BM)-focal myeloma lesion percent contrast and CNR were calculated. Spearman rank correlation coefficients were obtained between percent contrast, CNR and BMPC%. Percent contrasts and CNRs were compared among the three imaging sequences. Results BM-focal lesion percent contrasts, CNRs and BMPC% showed significant negative correlations in the three fat-suppression techniques. Percent contrast and CNRs were significantly higher for FS- T2 FSE than for STIR (P<0.01, P<0.05, respectively), but no significant differences were found among the three fat-suppression methods in the low tumor load BM group. Conclusion The higher BMPC% was within BM, the less conspicuous the focal lesion was on fat-suppressed MRI. The most effective protocol for detecting focal lesions was FS- T2 FSE. In the high tumor load BM group, no significant differences in lesion conspicuity were identified among the three fat-suppression techniques.

Ocular Volumetry Using Fast High-Resolution MRI during Visual Fixation

BACKGROUND AND PURPOSE: Volumetry may be useful for evaluating treatment response and prognosis of intraocular lesions. Phantom, volunteer, and patient studies were performed to determine whether ocular MR volumetry is reproducible. MATERIALS AND METHODS: Half-Fourier single-shot RARE and FSPGR sequences at 1.5T with a 76-mm-diameter surface coil were optimized to obtain still ocular images. Volumetry accuracies of each sequence were compared with simulated subretinal phantom volumes. Ocular volumetry was performed in 15 volunteers twice in 1 week by using contiguous axial images of the globes while the subjects stared at a target, and images were acquired in 2 seconds before the subjects were instructed to blink, with this process repeated as necessary. Imaging, intraobserver, and interobserver reproducibility for volumes of the whole eyeball and anterior chamber were assessed. Ocular volumetry was also performed in 6 patients with intraocular tumors before and after treatment. RESULTS: The phantom study demonstrated that measurement error rates with RARE were significantly lower than with FSPGR (P < .01). The volunteer study demonstrated excellent imaging and intraobserver reproducibility of RARE volumetry for whole eyeballs and anterior chambers (P < .01). Although no interobserver differences were observed in anterior chamber volume measurement (P = .33), there was a significant difference between the 2 observers in eyeball volume measurement (P < .01). Follow-up volumetric data were useful for treatment decisions in all patients. CONCLUSIONS: Ocular volumetry from contiguous ultrafast RARE images obtained during visual fixation is feasible in volunteer and patient studies and is superior to FSPGR images.

How to Improve the Conspicuity of Breast Tumors on Computed High b-value Diffusion-weighted Imaging

Purpose: The aim of this study was to compare the tumor conspicuity on actual measured diffusion-weighted images (aDWIs) and computed DWI (cDWI) of human breast tumors and to examine, by use of a phantom, whether cDWI improves their conspicuity. Materials and Methods: We acquired DWIs (b-value 0, 700, 1400, 2100, 2800, and 3500 s/mm2) of 148 women with breast tumors. cDWIs with b-values of 1400, 2100, 2800, and 3500 s/mm2 were calculated from aDWI scans where b = 0 and 700 s/mm2; the tumor signal-to-noise ratio (SNR) was compared at each b-value. We also subjected a phantom harboring a breast tumor and mammary glands to DWI. For reference we used two models. The model with b = 0, 1000, 1500, 2000, 2500, and 3000 s/mm2 was our multiple b-value model. In the single b-value model, we applied b = 0 and 1000 s/mm2 and changed the number of excitations (NEX). cDWIs were generated at b = 0 and 1000 and used to compare the SNR, the contrast ratio (CR), and the contrast-to-noise ratio (CNR). Results: In the phantom study, the CNR of cDWI generated from high SNR images obtained at lower b-values and a high NEX was outperformed aDWI. However, the CR and CNR on cDWI obtained using the same scanning parameters were inferior to aDWI scans. Similarly, in the clinical study, breast tumor conspicuity was worse on high b-value cDWIs than aDWIs. Conclusion: To improve tumor conspicuity on cDWI, the quality of the source images must be improved. It may easily cause inferior conspicuity to aDWIs if high b-value cDWIs were generated from insufficient SNR images.

Pituitary Volumes and Functions in Children with Growth Hormone Deficiency: Volumetric Magnetic Resonance Findings

Purpose : The purpose of the study was to compare pituitary volumes calculated from magnetic resonance imaging (MRI) in patients with idiopathic growth hormone deficiency (GHD) without structural abnormalities in the pituitary gland with clinical and biochemical features. Methods : This study was designed as a retrospective review and the need for informed consent was waived. MRI of the head was performed for 39 male and 17 female patients ranging in age from 10 to 14 years. Pituitary volumes were calculated from sectional area and ellipsoid formula. Pituitary volumes were compared between boys and girls. Pituitary volumes were also compared with measurements of pituitary function, age, and standard deviation scores (SDS) for height. Results : Whole pituitary volumes in patients were 405.1 ± 150.6 mm3 for the male group and 348.6 ± 161.1 mm3 for the female group. No significant difference was identified between mean pituitary volumes of the female and male groups. A weak correlation was found between pituitary volume and height SDS for boys (ρ = 0.34, p = .03). For girls, a moderate correlation was identified between pituitary volume and FSH level (ρ = 0.67, p < .01). Conclusion : Pituitary volumes of GHD patients correlated with height SDS in boys and FSH levels in girls. Brain MRI can be used not only to rule out anatomical abnormalities of the pituitary gland in GHD patients, but also to assess pituitary functions in clinical settings.

Vertebral Fracture Risk of Multiple Myeloma Assessed by a CT-based Finite Element and Trabecular Structure Analysis

Miyuki Takasu, Yoko Kaichi, Kazuo Awai Department of Diagnostic Radiology, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan Hideki Asaoku Department of Hematology, Hiroshima Red Cross Hospital and Atomic-bomb Survivors Hospital, Hiroshima, Japan Yoshiaki Kuroda Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan Akira Sakai Department of Radiation Life Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan