MR积分法与灌注成像在脑胶质瘤中的对照研究

目的比较MR积分法与灌注成像在脑胶质瘤术前分级诊断中的价值。方法对30例脑胶质瘤(低级8例,高级22例,世界卫生组织分级)术前行MR常规及灌注成像检查。MR积分法使用9个指标进行评价,灌注指标相对脑血容量(rCBV)由肿瘤及对侧正常脑白质的脑血容量(CBV)相比后得出。分别对低级、Ⅲ级和Ⅳ级胶质瘤的积分及rCBV值进行分析。结果低级胶质瘤的积分值(067±029)显著低于Ⅲ级(132±047)(t=-348,P=0003)和Ⅳ级(156±020)(t=-736,P=0000)。Ⅲ级和Ⅳ级之间差异无统计学意义(t=-139,P=0182)。低级胶质瘤的rCBV值(238±066)显著低于Ⅲ级(581±320)(t=-357,P=0003)和Ⅳ级(699±247)(t=-509,P=0001)。Ⅲ级和Ⅳ级之间差异无统计学意义(t=-093,P=0365)。结论在脑胶质瘤术前分级诊断中,常规MR和灌注成像均有重要价值,可相互补充,提高诊断准确率。     

3-[123I]Iodo-alpha-methyl-L-tyrosine uptake in cerebral gliomas: relationship to histological grading and prognosis

3-[123I]Iodo-alpha-methyl-L-tyrosine (IMT) is employed clinically as a tracer of amino acid transport in brain tumours using single-photon emission tomography (SPET). This study investigates the role of IMT SPET in the non-invasive histological grading and prognostic evaluation of cerebral gliomas. The files of patients investigated by IMT SPET in our clinic between 1988 and 1996 were evaluated retrospectively. Complete follow-up was available for 58 patients with cerebral gliomas investigated by IMT SPET shortly after tumour diagnosis. Seventeen patients had low-grade gliomas (WHO grade II), 14 had anaplastic gliomas (WHO grade III) and 27 had glioblastomas (WHO grade IV). Thirty-six cases were primary tumours and 22 cases, recurrences. Maximal and mean tumour-to-brain (T/B) ratios of IMT uptake at the first IMT SPET investigation were related to histological grading and survival time. Patients with low-grade gliomas showed significantly longer survival than patients with high-grade (grade III or IV) tumours. Gliomas without contrast enhancement on computed tomography or magnetic resonance imaging scans were associated with longer patient survival than tumours with contrast enhancement. The T/B ratios of IMT SPET showed no differences in relation to histological grading [WHO grade II: 1.73+/-0.59; WHO grade III: 1.74+/-0.38; WHO grade IV: 1.59+/-0.35, (mean+/-SD, T/B ratios of mean tumour uptake)]. The median survival time of patients with a high T/B ratio on IMT SPET was not significantly different from that of patients with a low T/B ratio (T/B ratio <1.6, 14.8 months; T/B ratio > or =1.6, 13.0 months). Thus, no evidence could be found for a relationship between IMT uptake in cerebral gliomas and either histological grading or survival time. Nevertheless, IMT SPET constitutes a useful method for the detection of primary and recurrent gliomas, determination of tumour extent and individual follow-up.     

^201TlSPECT和MRI评估胶质瘤恶性度的比较

目的评估２０１ＴｌＳＰＥＣＴ与增强ＭＲＩ在脑胶质瘤恶性度判断中的价值。方法３７例经组织学证实的幕上胶质瘤病人，按ＷＨＯ分级，１３例为低级别损害，８例为间变性损害，１６例为胶质母细胞瘤。采用半定量法，比较２０１Ｔｌ摄取、ＭＲＩ增强与胶质瘤组织学级别的关系。结果在低级别损害组２０１Ｔｌ平均摄取值为１２３±０７６，明显低于间变组２６０±１２４（Ｐ＜００１）和胶质母细胞瘤组４４５±１６８（Ｐ＜００１），后两组差异也有显著性（Ｐ＜００５）。若用２０１Ｔｌ摄取值２０作为阈值，鉴别高与低级别胶质瘤，则８３８％（３１／３７）病例可被正确预测。研究显示，按肿瘤在ＭＲＩ上的增强度来判定其恶性程度，其主要缺陷在于中等度增强缺乏特异性，而２０１ＴｌＳＰＥＣＴ可弥补其不足。结论对于胶质瘤恶性度的判定，２０１ＴｌＳＰＥＣＴ比ＭＲＩ更有价值     

颅内胶质瘤柔脑膜扩散的MR影像学研究

目的 探讨颅内胶质瘤柔脑膜扩散的ＭＲ影像学特征。为临床治疗及估计预后提供参考。方法 共集颅人胶质瘤９４５例,其中星形细胞瘤６２０例,多形成胶质细胞溜３２５例,对其中具有柔脑扩散的７２例胶质瘤的临床及ＭＲＩ资料进行回顾性分析。结果 ７２例具有柔脑膜扩散的胶质瘤中,星形细胞瘤２９例,多形成胶质细胞瘤４３例,柔脑膜发生率分别为４．７％和１３．２％。颅内胶瘤中,星形细胞瘤２９例,多形成胶质细胞瘤４３例,柔     

Preoperative grading of gliomas by using metabolite quantification with high-spatial-resolution proton MR spectroscopic imaging

PURPOSE: To evaluate proton magnetic resonance (MR) spectroscopic imaging with high spatial resolution for preoperative grading of suspected World Health Organization grades II and III gliomas. MATERIALS AND METHODS: Institutional ethics committee approval and informed consent were obtained for control subjects but were not required for the retrospective component involving patients. Twenty-six patients (10 women, 16 men; mean age, 37.5 years) suspected of having gliomas and 26 age- and sex-matched control subjects underwent proton MR spectroscopy. Absolute metabolite concentrations for choline-containing compounds (Cho), creatine (Cr), and N-acetylaspartate (NAA)-N-acetylaspartylglutamate (total NAA [tNAA]) were calculated by using a user-independent spectral fit program. Metabolic maps of Cho/tNAA ratios were calculated, segmented, and used for MR spectroszpcopy-guided stereotactic brain biopsy. Two-sided paired Student t tests were used to test for statistical significance. RESULTS: Significantly lower Cho levels (P = .002) and higher tNAA levels (P = .010) were found in grade II tumors (n = 9) compared with grade III tumors (n = 17). The average Cho/tNAA ratio over the voxels in the tumor center showed a distinct difference (P < .001) between grade II and III gliomas at a threshold of 0.8 (with ratios <0.8 for grade II). The maximum Cr concentration in the tumor showed a clear-cut threshold between grade III oligodendrogliomas and oligoastrocytomas (Cr level, <7 mmol/L) and grade III astrocytomas (Cr level, >7 mmol/L; P = .020). Comparison between the histopathologic findings from the MR spectroscopy-guided biopsy samples (76 biopsies from 26 patients) and molar metabolite values in corresponding voxels located at the biopsy sampling points showed a negative linear correlation for tNAA (r = -0.905) and a positive exponential correlation for Cho (r = 0.769) and Cho/tNAA (r = 0.885). CONCLUSION: Proton MR spectroscopic imaging with high spatial resolution allows preoperative grading of gliomas.     

MR imaging of brain contusions: a comparative study with CT

Ninety-eight brain contusions in 17 patients served as a data base for a comparative study of MR and CT for defining brain contusions. MR was the more sensitive technique, detecting 98% of the brain contusions compared with only 56% by CT. CT was slightly better for showing hemorrhagic components, documenting 77% of hemorrhages compared with 71% for MR. The appearance of the contusions on MR was variable, depending on the T1- and T2-weighting of the images and the constituents of the contusions, such as edema, hemorrhage, and encephalomalacia. On MR, hemorrhagic components appeared as high signal on T1-weighted images and as either low or high signal on T2-weighted images, depending on the age of the hemorrhage. The approximate ages of hemorrhagic contusions were often suggested by their appearance on T1- and T2-weighted images. CT is very effective for evaluating acute head trauma, but MR is recommended for documenting brain contusions during the subacute and chronic stages of head injuries.     

Quantitative accuracy of dopaminergic neurotransmission imaging with (123)I SPECT.

123I-Labeled radiotracers are suitable for in vivo imaging of the dopaminergic system by SPECT. However, precise measurement of striatal uptake is limited by scatter, attenuation, and the finite spatial resolution of the camera. We studied the quantitative accuracy that can be achieved with (123)I SPECT of the dopaminergic neurotransmission system. METHODS: Using a Monte Carlo simulation and brain phantom experiments, we studied the biases in brain and striatal absolute uptake estimates and in binding potential (BP) values for different processing schemes with corrections for attenuation, scatter, and the partial-volume effect. RESULTS: Without any correction, brain activity was underestimated by at least 65%, and absolute striatal activity measured in regions corresponding to the anatomic contours of the striata was underestimated by about 90%. With scatter and attenuation corrections only, estimated brain activity was accurate within 10%; however, striatal activity remained underestimated by about 50%, and BP values were underestimated by more than 50%. When combined with attenuation and scatter corrections, anatomically guided partial-volume effect correction (PVC) reduced the biases in striatal activity estimates and in BP values to about 10%. PVC reliability was affected by errors in registering SPECT with anatomic images, in segmenting anatomic images, and in estimating the spatial resolution. With registration errors of 1 voxel (2.1 x 2.1 x 3.6 mm(3)) in all directions and of 15 degrees around the axial direction, PVC still improved the accuracy of striatal activity and BP estimates compared with scatter and attenuation corrections alone, the errors being within 25%. A 50% overestimation of the striatal volume yielded an approximate 30% change in striatal activity estimates with respect to no overestimation but still provided striatal activity estimates that were more accurate than those obtained without PVC (average errors +/- 1 SD were -22.5% +/- 1.0% with PVC and -49.0% +/- 5.5% without PVC). A 2-mm error in the spatial resolution estimate changed the striatal activity and BP estimates by no more than 10%. CONCLUSION: Accurate estimates of striatal uptake and BP in (123)I brain SPECT are feasible with PVC, even with small errors in registering SPECT with anatomic data or in segmenting the striata.     

Noninvasive identification of anthracycline cardiotoxicity: Comparison of123I-MIBG and123I-BMIPP imaging

To test the feasibility of myocardial¹²³I-MIBG and¹²³I-BMIPP imaging for the early detection of anthracycline cardiotoxicity, 13 patients who had received anthracycline anticancer chemotherapeutic agents were studied. Two-dimensional echocardiography and myocardial imaging with both¹²³I-MIBG and¹²³I-BMIPP were performed in 13 patients treated with anthracycline (group A) and 10 normal control subjects (group C). Anterior myocardial images were obtained 15 minutes and 3 hours after the injection of isotopes. The heart-to-mediastinum ratio (H/M ratio) was used to quantify cardiac¹²³I-MIBG and¹²³I-BMIPP uptake. The left ventricular shortening fraction (%SF) and the ratio of peak mitral flow velocity in early diastole to that at the time of atrial systole (E/A ratio) were measured by echocardiography. The H/M ratio of¹²³I-MIBG was lower in group A than in group C (1.5 ± 0.2 vs. 1.9 ± 0.2, p < 0.01). The patients in group A had faster clearance of¹²³I-MIBG from the myocardium than those in group C (27 ± 10% vs. 22 ± 4%, p < 0.05). However, the H/M ratio and clearance of¹²³I-BMIPP were similar between the two groups (H/M ratio: 2.1 ± 0.2 vs. 2.0 ± 0.2, clearance: 24 ± 6% vs. 26 ± 6%). The %SF (37 ± 8% vs. 36 ± 7%) and E/A ratio (1.4 ± 0.4 vs. 1.6 ± 0.3) were comparable in groups A and C. The present findings indicated that myocardial imaging with¹²³I-MIBG could detect myocardial damage in patients treated with anthracycline in the early stage when cardiac systolic and diastolic function was still preserved. Early detection of anthracycline cardiotoxicity by¹²³I-MIBG would reduce the incidence and severity of heart failure.     

N-isopropyl-p-[123I]iodoamphetamine SPECT in MELAS syndrome: comparison with CT and MR imaging

Regional cerebral perfusion was studied in three patients with the mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, using single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP). Accumulation of the tracer was relatively decreased in the parietooccipital regions and also in the frontotemporal regions after stroke-like episodes. However, quantitative regional cerebral blood flow (rCBF) measurement showed that rCBF was relatively well preserved even at these sites, and a hyperemic state was observed at the sites of normal accumulation. IMP SPECT may be useful in the diagnosis and assessment of the progress of the MELAS syndrome.     

肥厚性心肌病患者201Tl和123I-MIBG心肌SPECT显像

目的：探讨肥厚性心肌病的肥厚心肌与非肥厚心肌交感神经活性。方法选择１８例肥厚性心肌病（ＨＣＭ）患和６例对照（Ｎ组）。根据超声心动图将ＨＣＭ组分为心尖部肥厚性心肌病（ＡＰＭ）５例，非对称性心室间隔肥厚性心肌病（ＡＳＨ）７例，弥漫性肥厚性心肌病（ＤＰＭ）６列。所有患均进行超声心动图（Ｍ型和Ｂ型）检查＾２０１Ｔｌ和＾１２３Ｉ－间碘苄胍（ＭＩＢＧ）显像。结果ＨＣＭ组＾１２３Ｉ－ＭＩＢＧ显像与Ｎ组相     

123I-IMT SPECT for evaluation of the response to radiation therapy in high grade gliomas: a feasibility study

Assessing response to radiation therapy in patients with high grade gliomas is needed upon making decisions toward further therapy strategies. Currently used standard imaging tools such as CT and MRI are not sensitive enough to detect early therapy effects. We prospectively investigated if single photon emission computed tomography (SPECT) using radiolabelled amino acid derivate (123)I-methyltyrosine (IMT) would be useful for this aim. 10 patients with histologically proven high grade gliomas, who were candidates for radiation therapy, were enrolled in this investigation. All patients were examined by IMT SPECT before radiation therapy and 4 weeks after the initiation of the hypofractionated application of 40 Gy. Patients were followed up for 39 months; the tumours to background ratios (T/B) for IMT under/before radiation therapy were correlated to survival times. Initially, SPECT depicted an abnormal intratumoural IMT uptake in all patients (mean T/B ratios 1.37-1.87). In four out of 10 patients, the mean T/B ratios decreased by more than 10% under radiation therapy. In six other patients, the BQ decreased by less than 10% or increased. There were no significant correlations between the degree of changes in T/B and survival (r = -0.1, p = 0.973). Serial IMT SPECT measurements allow detection of changes in amino acid accumulation in high-grade gliomas under radiation therapy. However, these changes seem to possess no prognostic value in respect to survival prediction.     

L-3-123I-alpha-methyltyrosine for melanoma detection: a comparative evaluation

L-3-123I-alpha-methyltyrosine (IMT) was compared to [67Ga]citrate, [203Pb]Tris and [131I]iodochloroquine (ICQ) with respect to their potential as melanoma seeking radiopharmaceuticals in two tumor lines, a malignant melanotic melanoma of the Sofia type and a malignant amelanotic melanoma of the Greene-Harvey type, transplanted onto Syrian Golden hamsters. [203Pb]Tris and ICQ showed significant accumulation only in melanotic melanoma. In contrast, [67Ga]citrate and IMT accumulated in both tumor lines. [67Ga]citrate has very high tumor-to-skin, tumor-to-eye, and tumor-to-blood ratios at 48 h after injection, but has low selectivity for melanoma and unfavorable physical (high gamma-energy) and biological (half-time) characteristics. IMT has a convenient gamma-energy at 159 keV and a short biological half-time. Maximum of melanoma accumulation is reached at 1-2h after application; tumor-to-tissue ratios are suitable for scintigraphy.     

Brain phantom: high-resolution imaging with SPECT and I-123

Inverse Monte Carlo (IMOC) is a unified reconstruction algorithm for single photon emission computed tomography (SPECT) that provides simultaneous compensation for attenuation and collimator divergence. IMOC was applied to the reconstruction of SPECT images of a brain phantom with iodine-123 and high-resolution collimation. Projection sets containing 80,000, 540,000, and 5.2 million counts were reconstructed. Comparison with filtered back-projection reconstructions showed that the IMOC reconstructions provided superior noise and resolution characteristics at all three photon densities. Results of this study indicate that IMOC may allow the use of high-resolution, low-sensitivity collimation for SPECT studies, which have traditionally provided photon yields too low for useful imaging.     

3T MR肾脏灌注成像:动脉自旋标记和动态增强技术的对比研究

目的评价3T MR动脉自旋标记和动态增强技术测量肾脏血流量的可行性和两者的相关性。材料与方法研究获机构审查委员会批准,19名健康志愿者(7名女性,12名男性;年龄25～68岁)入组,均签署知情同意书。采用3T     

Comparison of O-(2-18F-fluoroethyl)-L-tyrosine PET and 3-123I-iodo-alpha-methyl-L-tyrosine SPECT in brain tumors.

The aim of this study was to compare PET with O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) and SPECT with 3-(123)I-iodo-alpha-methyl- L-tyrosine ((123)I-IMT) in patients with brain tumors. METHODS: Twenty patients with a suspected brain tumor were investigated by (18)F-FET PET, (123)I-IMT SPECT, and MRI within 3 wk. Region-of-interest analyses were performed on coregistered PET/SPECT/MRI images and the tumor-to-brain ratio (TBR), muscle-to-brain ratio (MBR), cerebellum-to-brain ratio (CerBR), and sinus-to-brain ratio (SBR) were calculated. In addition, the presence of tumor and the discrimination of anatomic structures on (18)F-FET PET and (123)I-IMT SPECT images were visually determined by 3 observers who were unaware of clinical data. RESULTS: The TBR of (18)F-FET and (123)I-IMT uptake in cerebral tumors showed a highly significant correlation (r = 0.96; P < 0.001). In the visual analysis for the presence or absence of tumors, no differences for (123)I-IMT SPECT and (18)F-FET PET were found in 19 of 20 patients; in one patient a low-grade glioma was only identified on (18)F-FET PET images but not on (123)I-IMT SPECT images. The contrast between tumor and normal brain was significantly higher in (18)F-FET PET (TBR, 2.0 +/- 0.9) than in (123)I-IMT SPECT (TBR, 1.5 +/- 0.5). The discrimination of anatomic structures yielded a significantly better score on (18)F-FET PET images (rating score, 2.6 +/- 0.9) compared with (123)I-IMT SPECT images (rating score, 1.7 +/- 0.9). The uptake of (18)F-FET in the muscles was significantly higher compared with (123)I-IMT (MBR (18)F-FET, 1.4 +/- 0.3; MBR (123)I-IMT, 0.6 +/- 0.2; P < 0.001) and (18)F-FET demonstrated a significantly higher blood-pool radioactivity than (123)I-IMT (SBR (18)F-FET, 1.3 +/- 0.2; SBR (123)I-IMT, 0.8 +/- 0.2; P < 0.001). CONCLUSION: The significant correlation of the TBRs of (18)F-FET and (123)I-IMT indicates that clinical experiences of brain tumor diagnostics with (123)I-IMT SPECT might be valid for (18)F-FET PET although substantial differences of the physiologic behavior were identified in extracerebral tissue. As (18)F-FET PET allows improved discrimination of anatomic structures and the tumor-to-brain contrast was significantly superior compared with (123)I-IMT SPECT scans, the results are encouraging for further evaluation of (18)F-FET for imaging brain tumors.     

Ocular melanoma: detection using iodine-123-iodoamphetamine and SPECT imaging

Uptake of iodine-123-iodoamphetamine has been demonstrated in malignant melanoma using planar imaging techniques and has been used to detect an ocular melanoma at 12 hr postinjection. Using SPECT technique, an ocular melanoma is identified in a 64-yr-old male at 1 hr postinjection.     

Synthesis, radiolabeling and baboon SPECT imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl)tropane ([(123)I]YP256) as a serotonin transporter radiotracer

To develop a potential SPECT probe to evaluate the integrity of the serotoninergic system (5-HTT) whose dysfunction is linked to several disease conditions such as Parkinson's disease, Alzheimer's disease and depression, we report the synthesis, radiolabeling and in vivo baboon imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl) tropane (YP256, 6). The radiolabeling was performed by iododestannylation using sodium [(123)I]iodide and peracetic acid. Although the ligand displayed high selectivity for 5-HTT over dopamine transporter in vitro, SPECT imaging in baboons did not reveal selective 5-HTT accumulation in brain in vivo.     

Osteoid osteoma: MR imaging of two untreated lesions

Nonoperative management is currently the preferred method of treatment for osteoid osteoma by some orthopedic surgeons. The follow-up imaging appearance of osteoid osteoma in patients who are managed conservatively has not previously been described in radiology literature, and it is unclear what the natural evolution of the imaging findings is. Such patients may present to the radiologist either for follow-up assessment of the lesion or as an incidental finding during imaging for an unrelated complaint. The magnetic resonance imaging (MRI) findings in two patients with osteoid osteoma who underwent conservative treatment are presented.