Clinical Evaluation of Non-invasive Perfusion-weighted MRI

脳灌流の画像化は現在主にsingle-photon emission computed tomography(SPECT)でなされているが, positron emission tomography(PET)や造影剤を用いたMRIの手法も用いられている。更に近年, MRIの新しいパルス系列として, arterial spin labeling法(ASL法)を用いたMR脳灌流強調画像が報告されてきている。今回我々は脳疾患患者に対して, 臨床用の1.5T超伝導MRI装置を使用し, ASL法を応用したパルス系列であるFAIR(flow-sensitive alternating inversion recovery)と, 造影剤を用いた灌流強調画像(perfusion-weighted image, 以下PWI)を比較検討した。結果は以下の通りである。1.PWIで高灌流を示した8病変のうち7病変がFAIR画像でも高信号を示し, 高灌流病変に対するFAIRの検出率は88%であった。2.PWIで低灌流を示した41病変のうち13病変がFAIR画像でも低信号を示し, 低灌流病変に対するFAIRの検出率は32%であった。3.PWIで低灌流を示した病変で, FAIRで検出されたものはそうでないものに比較して相対的脳血液量と相対的脳血流量が有意に低かった。4.FAIRで灌流異常が検出された病変については, 相対的脳血流量あるいは相対的脳血液量とFAIRの信号強度の間に正の相関が見られた。5.PWIで無信号を示した7病変のうち, 5病変はFAIR画像で明瞭な高信号として検出された。FAIRはbackgroundに対する脳実質の信号が低く, 低灌流病変に対する検出能に問題があるが, 半定量的に脳血流の評価が可能であり, 臨床上有用と考えられた。A spin labeling method to measure cerebral blood flow without a contrast medium was developed and applied clinically to obtain a non-invasive perfusion-weighted image. The purpose of this study is to compare the non-invasive perfusion-weighted image using FAIR with the well-established PWI using a bolus injection of Gd-DTPA. Of 41 lesions which revealed decreased perfusion, 13 were shown to be low signal intensity areas on FAIR. Therefore, detection rate of FAIR for hypoperfusion was 32%.0 Of 8 lesions which revealed increased perfusion, 7 demonstrated high intensity on FAIR. Therefore, detection rate of FAIR for hyperperfusion was 88%.0 7 lesions were found to have a mean pixel value of zero on PWI. Of these lesions, 5 lesions could be detected as high signal intensity area on FAIR. The rCBV- and rCBF index ratios of hypoperfused lesions detected on FAIR were significantly lower than those of lesions which were not detected on FAIR (p=0.007,p=0.01). As concerns the lesions detected of FAIR, there were positive correlation between rCBV- or rCBF index ratio and FAIR signal ratio (rCBV ratio : ρ=0.873,p=0.0002,rCBF index ratio : ρ=0.858,p=0.0003). FAIR is valuable clinical tool to detect perfusion abnormality semi-quantitatively without contrast medium, although it showed relatively low detection rate for hypoperfused lesions

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 (Ï = 0.34, p = .03). For girls, a moderate correlation was identified between pituitary volume and FSH level (Ï = 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

Assessment of early treatment response on MRI in multiple myeloma: Comparative study of whole-body diffusion-weighted and lumbar spinal MRI.

OBJECTIVES:To compare remission status at completion of chemotherapy for multiple myeloma (MM) with changes in total diffusion volume (tDV) calculated from whole-body diffusion-weighted imaging (WB-DWI) and fat fraction (FF) of lumbar bone marrow (BM) by modified Dixon Quant (mDixon Quant) soon after induction of chemotherapy, and to assess the predictive value of MRI. METHODS:Fifty patients (mean age, 66.9 ± 10.5 years) with symptomatic myeloma were examined before and after two cycles of chemotherapy. From WB-DWI data, tDV was obtained with the threshold for positive BM involvement. Mean FF was calculated from lumbar BM using the mDixon Quant sequence. At the completion of chemotherapy, patients were categorized into a CR/very good PR (VGPR) group (n = 15; mean age, 67.6 ± 10.3 years) and a PR, SD or PD group (n = 35; mean age, 69.1 ± 8.6 years). ROC curves were plotted to assess performance in predicting achievement of CR/VGPR. RESULTS:At second examination, serum M protein, β2-microglobulin, and tDV were significantly decreased and hemoglobin, mean ADC, and FF were significantly increased in the CR/VGPR group and serum M protein was significantly increased in the PR/SD/PD group. The general linear model demonstrated that percentage changes in FF and M protein contributed significantly to achieving CR/VGPR (P = 0.02, P = 0.04, respectively). AUCs of ROC curves were 0.964 for FF and 0.847 for M protein. CONCLUSIONS:Early change in FF of lumbar BM and serum M protein soon after induction of chemotherapy contributed significantly to prediction of CR/VGPR

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

Prediction of mobilized hematopoietic stem cell yield in patients with multiple myeloma: Usefulness of whole-body MRI-derived indices.

IntroductionHigh-dose chemotherapy followed by autologous stem cell transplant is the mainstay of treatment for multiple myeloma (MM). The purpose of this study was to evaluate the ability of MRI-derived indices to predict mobilized hematopoietic stem cell yield.Materials and methodsIn this exploratory pilot work, we retrospectively analyzed 38 mobilization procedures for MM. Successful mobilization procedure was defined as a total yield of >4.0×106 CD34+ cells/kg. Univariate and multivariate analyses were performed to identify factors with a significant effect on successful mobilization from among clinical characteristics including number of prior lines of therapy, period from diagnosis to harvest, type of monoclonal protein (M protein); and radiological characteristics including total diffusion volume (tDV), median apparent diffusion coefficient (ADC) of tDV, and mean fat fraction of bone marrow calculated by MRI.ResultsUnivariate analyses showed that relatively poor mobilization was significantly associated with M protein of Bence-Jones type and with median ADC of tDV (P = 0.02 and P = 0.004, respectively). Multivariate analyses using these two indices showed that median ADC of tDV was a significant predictive factor for adequate mobilization (P = 0.01), with an area under the curve of 0.784 (cutoff value, 1.18×10-3 mm2/s; sensitivity, 72.7%; specificity, 87.5%).ConclusionThe present data indicate that median ADC of tDV is a predictive factor for relatively poor mobilization of hematopoietic stem cells in MM patients undergoing autologous stem cell transplant

Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-Squares Estimation (IDEAL) Magnetic Resonance Imaging as a Biomarker for Symptomatic Multiple Myeloma

<div><p>Introduction</p><p>To evaluate the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) magnetic resonance imaging (MRI) to discriminate between symptomatic and asymptomatic myeloma in lumbar bone marrow without visible focal lesions.</p><p>Materials and Methods</p><p>The lumbar spine was examined with 3-T MRI in 11 patients with asymptomatic myeloma and 24 patients with symptomatic myeloma. The fat-signal fraction was calculated from the ratio of the signal intensity in the fat image divided by the signal intensity of the corresponding ROI in the in-phase IDEAL image. The <i>t</i> test was used to compare the asymptomatic and symptomatic groups. ROC curves were constructed to determine the ability of variables to discriminate between symptomatic and asymptomatic myeloma.</p><p>Results</p><p>Univariate analysis showed that β2-microglobulin and bone marrow plasma cell percent (BMPC%) were significantly higher and fat-signal fraction was significantly lower with symptomatic myeloma than with asymptomatic myeloma. Areas under the curve were 0.847 for β₂;-microglobulin, 0.834 for fat-signal fraction, and 0.759 for BMPC%.</p><p>Conclusion</p><p>The fat-signal fraction as a biomarker for multiple myeloma enables discrimination of symptomatic myeloma from asymptomatic myeloma. The fat-signal fraction offers superior sensitivity and specificity to BMPC% of biopsy specimens.</p></div