全身18F-FDGPET-CT在脑转移瘤诊断中的应用

目的评价全身18F-氟脱氧葡萄糖（18F-fluorodeoxyglucose,18 F-FDG）正电子发射断层扫描（posi—tronemissiontomography,PET）-CT显像在脑转移瘤的诊断及寻找原发灶中的应用价值。方法对全身脑转移瘤及可疑脑转移瘤的212例行PET—CT检查,并回顾性分析其临床资料。结果212例中,肺原发恶性病变158例（74．5％）,其他部位原发恶性肿瘤40例（18．9％）,可疑脑原发病变11例（5．2％）,未发现原发灶的脑转移瘤3例（1．4％）。未明确原发灶的48例中,全身PET-CT显像发现原发灶34例（70．8％）,其中肺恶性病变来源26例（54．2％）、其他部位来源恶性肿瘤8例（16．7％）。单纯胸部薄层CT扫描诊断为肺恶性病变来源者22例（45．8％）;CT性质不明确的孤立性肺结节4例,结合临床及全身PET—CT显像特征均诊断为肺恶性病变。结论全身18F—FDGPET—CT显像有利于发现脑转移瘤的原发灶。脑转移瘤来源于肺恶性病变较多。胸部薄层CT扫描有利于对原发灶的初步诊断。     

CT findings in fungal opportunistic pneumonias: body and brain involvement

A population of 28 immunocompromised hosts with proved pulmonary infections by Candida species (n = 18) or angioinvasive fungal pneumonias (Aspergillus species, n = 7, Mucor species n = 2, Trichosporon capitatum n = 1) were retrospectively examined for any characteristic computed tomographic (CT) pattern. Chest CT examination in angioinvasive fungal pneumonias (AFP) showed in all cases nodules or mass-like infiltrates. The mass/nodules were surrounded by a halo of low attenuation in early scans (n = 3/10) and showed often a peripheral enhancement in 6/8 contrast-enhanced scans. CT abnormalities in AFP were confined to the chest. Of the 18 patients with Candida pneumonias, 6 showed a mixed air space-interstitial pattern, 4 a granular pattern, 6 some type of mass-like consolidation, without neither perifocal halo nor postcontrast enhancement. In two autoptically proved cases, both chest plain film and CT scans were normal (false negatives). In CT body examinations, were found in 6 cases, other sites of organ involvement by Candida species (of brain in 1/6).     

多层螺旋CT灌注成像在全身肿瘤性病变中的初步应用

目的：初步评价多层螺旋CT(MSCT)肿瘤灌注成像方法及其临床应用价值。方法：对l0例肿瘤患者行MSCT灌注成像，先用常规CT平扫确定肿瘤中心部位，然后进行肿瘤灌注扫描，采用电影扫描技术(1r／s)，层厚l0mm／2i;药流率3．5—4．0ml／s，剂量45—50m1，延迟时间5s，扫描总时间45s。扫描图像经ADW3．1工作站处理，计算并分析灌注图像和灌注参数，包括血流量(BF)、血容量(BV)、平均通过时间(MTT)和表面通造性(PS)。结果：所有肿瘤的灌注图像均可以清晰直观的显示出肿瘤大小和轮廓，并可定量检测肿瘤内部的组织灌注状态，在脑肿瘤中清晰区分肿瘤区与水肿区。所有肿瘤灌注参数均明显增高。体部肿瘤灌注成像受呼吸运动影响较大。结论：MSCT灌注成像提供了一种准确且相对简捷的定量评估全身肿瘤血流灌注状态的方法。     

全身18F FDG PET CT在脑转移瘤诊断中的应用

目的评价全身18F 氟脱氧葡萄糖（18F fluorodeoxyglucose,18F FDG）正电子发射断层扫描(positron emission tomography,PET) CT显像在脑转移瘤的诊断及寻找原发灶中的应用价值。方法对全身脑转移瘤及可疑脑转移瘤的212例行PET CT检查,并回顾性分析其临床资料。结果212例中,肺原发恶性病变158例（745%）,其他部位原发恶性肿瘤40例（189%）,可疑脑原发病变11例（52%）,未发现原发灶的脑转移瘤3例（14%）。未明确原发灶的48例中,全身PET CT显像发现原发灶34例（708%）,其中肺恶性病变来源26例（542%）、其他部位来源恶性肿瘤8例（167%）。单纯胸部薄层CT扫描诊断为肺恶性病变来源者22例（458%）;CT性质不明确的孤立性肺结节4例,结合临床及全身PET CT显像特征均诊断为肺恶性病变。结论全身18F FDG PET CT显像有利于发现脑转移瘤的原发灶。脑转移瘤来源于肺恶性病变较多。胸部薄层CT扫描有利于对原发灶的初步诊断。     

Changing body temperature affects the T2* signal in the rat brain and reveals hypothalamic activity.

This study was designed to determine brain activity in the hypothalamus-in particular the thermoregulatory function of the hypothalamic preoptic area (PO). We experimentally changed the body temperature in rats within the physiological range (37-39 degrees C) and monitored changes in blood oxygenation level-dependent (BOLD) MR signal. To explore PO activity we had to deal with general signal changes caused by temperature-dependent alterations in the affinity of oxygen for hemoglobin, which contributes to BOLD contrast because it is partly sensitive to the amount of paramagnetic deoxyhemoglobin in the voxel. To reduce these overall temperature-induced effects, we corrected the BOLD data using brain-specific correction algorithms. The results showed activity of the PO during body warming from 38 degrees C to 39 degrees C, supported by an increased BOLD signal after correction. This is the first fMRI study on the autonomous nervous system in which hypothalamic activity elicited by changes in the internal environment (body temperature) was monitored. In this study we also demonstrate 1) that any fMRI study of anesthetized small animals should guard against background BOLD signal drift, since animals are vulnerable to body temperature fluctuations; and 2) the existence of a link between PO activity and the sympathetically-mediated opening of the arteriovenous anastomoses in a parallel study on the rat tail, a peripheral thermoregulatory organ.     

Spectral analysis of body movement during deep brain stimulation in Parkinson’s disease

BackgroundThe characteristics of Parkinson’s disease (PD) include postural instability and resting tremor. However, reductions of tremor amplitude do not always improve postural stability.Research questionWhat is the effect of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on spectral analysis of body movement in patients with PD when tested without anti-PD medication? The effect of visual cues was also studied.MethodsTen patients with PD (mean age 64.3 years, range 59−69 years) and 17 control participants (mean age 71.2 years, range 65–79 years) were recruited. Spectral power following a period of quiet stance (35 s) was analysed in three different spectral power bands (0−4 Hz, 4−7 Hz and 7−25 Hz). Motion markers were secured to the head, shoulder, hip, and knee, which recorded movements in two directions, the anteroposterior and lateral.ResultsDBS STN significantly changed the spectral distribution pattern across the body in the anteroposterior (p = 0.029) and lateral directions (p ≤ 0.003). DBS predominantly reduced spectral power at the head (p ≤ 0.037) and shoulder (p ≤ 0.031) in the lateral direction. The spectral power of the lower and upper body in patients with PD, with DBS ON, were more similar to the control group, than to DBS OFF. Visual cues mainly reduced spectral power in the anteroposterior direction at the shoulder (p ≤ 0.041) in controls and in patients with PD with DBS ON.SignificanceThere is an altered postural strategy in patients with PD with DBS ON as shown by an altered spectral power distribution pattern across body segments and a reduction of spectral power in the lateral direction at the head and shoulder. A reduction of spectral power in controls and in patients with PD with DBS ON suggests that visual cues are able to reduce spectral power to some extent, but not with DBS OFF where postural sway and power are larger.     

坐位下体负压对人体脑功能影响的实验研究

 目的探讨坐位下体负压(Lower body negative pressure,LBNP)暴露时对人体脑功能的影响。方法 15例健康青年男性被试者在坐位LBNP-4.00 kPa(-30 mmHg)、-6.67 kPa(-50 mmHg)的条件下,分别测试暴露前、暴露时和卸压后的脑事件相关电位(Event related potential,ERP)P300、反应时(Reaction tinle,RT)及跟踪误差(Trackng error,TrE)等工效学指标,并记录主观症状。结果在-4.00 kPa LBNP作用时,P300波幅、潜时、反应时、跟踪误差与负压前对照差异无显著性意义(P＞0.05)。在-6.67 kPa LBNP作用时,P300波幅降低(P＜0.01),P300潜时延长(P＜0.01),反应时延长(P＜0.05),跟踪误差增大(P＜0.05)。主观症状随着负压值的增大,症状数量增多,程度加重。结论 坐位下体负压造成血液在下肢积聚,引起大脑供血量减少,从而引起大脑对外界的反应减慢,脑认知工效下降。     

立体定向放疗计划验证模体在脑转移瘤HyperArc技术中的应用研究

目的 探究StereoPhan(SP)模体与SRS MapCHECK(SMC)半导体矩阵用于脑转移瘤患者HyperArc(HA)计划剂量验证的可行性。方法 选取16例在北京协和医院接受HA放射治疗的脑转移瘤患者为研究对象,分别将电离室和SMC半导体矩阵插入SP模体,测量患者的HA验证计划的点剂量与平面剂量,并与治疗计划系统(TPS)计算数据对比,平面剂量的γ分析标准取2 mm/3%、2 mm/2%、1 mm/3%和1 mm/2%。结果 16例患者的点剂量平均偏差是1.33%±0.84%,平面剂量γ通过率在2 mm/3%、2 mm/2%的标准下依次为99.72%±0.46%、98.93%±1.32%,在 1 mm/3% 、1 mm/2%的标准下依次为98.85%±1.79%、97.13%±3.19%。结论 SP模体与SMC半导体矩阵适合用于开展脑转移瘤患者HA计划的剂量验证工作,在进行点剂量和平面剂量验证时,可以分别采用3%和1mm/2%的分析标准。     

The "mini brain": plasmacytoma in a vertebral body on MR imaging

OBJECTIVE: Patients with solitary plasmacytoma in the spine frequently require a biopsy for diagnosis of their condition. We report an appearance of plasmacytoma in the spine, which is sufficiently pathognomonic to obviate biopsy. CONCLUSION: Identification of a "mini brain" in an expansile lesion in the spine is characteristic of plasmacytoma. It is important that radiologists note this characteristic because biopsy can be avoided in patients with this appearance. Although biopsy might still be required at many institutions, at our institution, surgeons find this appearance sufficiently pathognomonic to bypass biopsy and start treatment.     

Multidetector SPECT scanner for brain and body: system performance and applications

A multidetector whole-body single photon emission computed tomography (SPECT) scanner has been developed for high-resolution dynamic SPECT imaging. The scanner consists of three detector rings with 128 NaI crystals (14 x 26 x 30 mm) in each ring, providing three tomographic images at 30 mm intervals. This system uses a rotation of collimator around the patient combined with the detector rotation for fine data sampling. The in-plane spatial resolution is 14.2 mm (full width of half maximum) with high-resolution (HR) collimator, 22.0 mm with high-sensitivity (HS) collimator, and 10.6 mm with high-resolution brain (HRB) collimator. The axial resolution is 24.0, 34.0, and 23.5 mm with HR, HS, and HRB collimator, respectively. The sensitivity measured with a 20% energy window for 99mTc in a 20 cm diameter phantom is 5.7, 17.0 and 6.6 kcps/muCi/ml with HR, HS, and HRB collimator, respectively. This scanner allows dynamic SPECT imaging both for brain and body organs with good spatial resolution.     

The radiation dose to patients from EMI brain and body scanners.

Absorbed doses throughout the head of a Rando standard man phantom have been measured during simulated neurological examination with the EMI Mk I brain scanner and the second generation CT 1010 brain scanner. Similar measurements have been made with the CT 5005 whole-body scanner which have also included scans through thoracic and abdominal sections of the phantom. Lithium borate thermoluminescent dosimeters placed at regular intervals throughout, and on either side of the scanned volume, have enabled estimates to be made of the total energy imparted to the phantom by each scanner as well as the absorbed dose at various locations including organs of interest in health physics such as the lens of the eye, thyroid and gonads. Isodose curves have been plotted for the central transverse section of each simulated examination. Results are reported for both the standard and high accuracy scan speed options on the two scanners where this choice is available. It would appear that all three machines when operated at their standard scan speeds impart no more energy to the phantom than that associated with a few conventional radiographs of the same part of the body. Maximum skin doses vary from 30 to 56 mGy (3.0 to 5.6 rad) being highest for the CT 1010 scanner. Use of the high accuracy scan option increases the energy imparted and the maximum skin doses by a factor of about five, while providing much enhanced tissue density discrimination. In the case of the body scanner this higher value of energy imparted becomes comparable to that associated with lengthy fluoroscopic examinations like barium enemas. Recent work by EMI involving further refinements to the collimation system has reduced the dose levels by typically 50%. Some preliminary results with this new system are included to indicate the likely degree of improvement, but a detailed account will be the subject of a separate paper.     

Labeled choline and phosphorylcholine: body distribution and brain autoradiography: concise communication

Following intravenous injection of labeled choline or phosphorylcholine in rats and mice, the brain uptake as percent injected dose was less than 0.2% with 6-12% going to kidney and 3-6% to liver. A study of [14C]choline autoradiography in a stump-tailed macaque demonstrated a five- to sixfold greater uptake in gray matter than in white matter. Dynamic positron imaging of [11C]choline in a rhesus monkey demonstrated rapid brain uptake followed by rapid washout, with heavy late uptake in muscle. The use of labeled choline and choline analogs as imaging agents in human studies is constrained by the low brain uptake relative to extracerebral tissues.     

Effects of repeated brain ischemia induced by rapid lower body negative pressure on brain water and Na+,K+-ATPase activity in rats

BACKGROUND: It has been demonstrated that during +Gz exposure cerebral blood flow is significantly reduced resulting in brain ischemia. Animal centrifuge models are commonly used to investigate the mechanisms of +Gz-induced loss of consciousness (G-LOC) and their pathophysiological effects on the brain. These dynamic models are limited because we currently are unable to obtain accurate measures of membrane ion flux or single cell electrophysiological responses from animals under centrifugation. HYPOTHESIS: The aim of the present study was to develop a non-centrifuge animal model of short-term, repeatable and complete brain ischemia using a rodent lower body negative pressure (LBNP), and to investigate the effects of repeated complete brain ischemia induced by LBNP on brain Na+,K+-ATPase activity, Na+, K+ and water contents in rats. METHODS: Eight anesthetized rats were exposed randomly to LBNP of -2.67 kPa, -4.00 kPa, and -5.33 kPa, respectively, at the rate of -0.67 kPa x s(-1). The pressure rapidly returned to control level when EEG became isoelectric (flat). The mean arterial BP (MAP), EEG and ECG were recorded. Twenty-one rats were divided randomly into control, single LBNP exposure, and three LBNP exposures groups (n = 7 in each group). Brain samples were analyzed for Na+,K+-ATPase activity, Na+, K+ and water contents 1 h after single and three 2-min LBNP exposures (-4.00 kPa at a rate of 0.67 kPa x s(-1)), respectively. RESULTS: MAP decreased rapidly during LBNP exposure. The mean time to isoelectric EEG was 41.33 +/- 11.48, 30.67 +/- 3.88 and 25.67 +/- 3.45 s during -2.67, -4.00 and -5.33 kPa LBNP, respectively. Heart rate (HR) significantly decreased when EEG became isoelectric. MAP, HR and EEG rapidly returned after releasing LBNP. The brain Na+,K-ATPase activity decreased significantly after single LBNP exposure and decreased further after three LBNP exposures. The brain K+, Na+ and water contents increased significantly after three LBNP exposures. CONCLUSIONS: A rat model of short-term, repeatable brain ischemia was developed using rapid LBNP. Three -4.00 kPa LBNP exposures (2 min each) cause a significant reduction in brain Na+,K+-ATPase activity and brain edema in rats.