Primary Spinal Intradural Extramedullary Hydatid Cyst in a Child

Abstract

Background/Objective: Spinal hydatid cyst is a serious form of hydatid disease affecting less than 1% of the total cases of hydatid disease. We present a case of pathologically confirmed primary intradural spinal cyst hydatid in an otherwise healthy patient who showed no other evidence of systemic hydatid cyst disease.

Case Report: An 8-year-old boy presented with back pain, left leg pain, and difficulty in walking. The patient had no other signs of systemic hydatid cyst disease. An intradural extramedullary cystic lesion was identified with magnetic resonance imaging and was shown to be a hydatid cyst by histopathologic examination after the surgical removal.

Conclusion: Although extremely rare, primary intradural extramedullary hydatid cyst pathology might be the cause of leg pain and gait disturbance in children living in endemic areas.     

Pharmacokinetics and dosimetry of an alpha-particle emitter labeled antibody: 213Bi-HuM195 (anti-CD33) in patients with leukemia.

Data from nine patients with leukemia participating in a phase I activity-escalation study of HuM195, labeled with the alpha-particle emitter 213Bi (half-life = 45.6 min), were used to estimate pharmacokinetics and dosimetry. This is the first trial using an alpha-particle emitter in humans. The linear energy transfer of alpha particles is several hundredfold greater than that of beta emissions. The range in tissue is approximately 60-90 microm. METHODS: The activity administered to patients ranged from 0.6 to 1.6 GBq. Patient imaging was initiated at the start of each injection. Thirty 1-min images followed by ten 3-min images were collected in dynamic mode; a 20% photopeak window centered at 440 keV was used. Blood samples were collected until 3 h postinjection and counted in a gamma counter. Contours around the liver and spleen were drawn on the anterior and posterior views and around a portion of the spine on the posterior views. No other organs were visualized. RESULTS: The percentage injected dose in the liver and spleen volumes increased rapidly over the first 10-15 min to a constant value for the remaining hour of imaging, yielding a very rapid uptake followed by a plateau in the antibody uptake curves. The kinetic curves were integrated to yield cumulated activity. The mean energy emitted per nuclear transition for 213Bi and its daughters, adjusted by a relative biologic effectiveness of 5 for alpha emissions, was multiplied by the cumulated activity to yield the absorbed dose equivalent. Photon dose to the total body was determined by calculating a photon-absorbed fraction. The absorbed dose equivalent to liver and spleen volumes ranged from 2.4 to 11.2 and 2.9 to 21.9 Sv, respectively. Marrow (or leukemia) mean dose ranged from 6.6 to 12.2 Sv. The total-body dose (photons only) ranged from 2.2 x 10(-4) to 5.8 x 10(-4) Gy. CONCLUSION: This study shows that patient imaging of 213Bi, an alpha-particle emitter, labeled to HuM195 is possible and may be used to derive pharmacokinetics and dosimetry. The absorbed dose ratio between marrow, liver and spleen volumes and the whole body for 213Bi-HuM195 is 1000-fold greater than that commonly observed with beta-emitting radionuclides used for radioimmunotherapy.     

PET-based radiation dosimetry in man of 18F-fluorodihydrotestosterone, a new radiotracer for imaging prostate cancer.

16 beta-fluoro-5 alpha-dihydrotestosterone (FDHT) is a promising new PET radiopharmaceutical for the imaging of prostate cancer. A recent clinical trial provided the opportunity for refinement of normal-tissue radiation-absorbed dose estimates based on quantitative PET. The objective of the current study was to derive estimates of normal-tissue absorbed doses for (18)F-FDHT administered to patients with advanced prostate cancer. METHODS: Absorbed dose estimates were derived from 10 (18)F-FDHT PET studies (administered activity, 111-407 MBq) of 7 prostate cancer patients. Activity concentrations in plasma and red marrow (assuming a plasmacrit of 0.58, an extracellular fluid fraction of 0.40, and equilibration of activity between plasma and marrow extracellular fluid) were measured ex vivo from a peripheral blood sample. Liver, spleen, urinary bladder contents, and total-body activities were measured by region-of-interest analysis of quantitative whole-body studies acquired with a dedicated PET scanner. Total organ activities and residence times were calculated from the respective PET scan-derived activity concentrations assuming standard (70 kg) man organ masses. Urinary excretion was corrected for hepatobiliary excretion (liver activity), and a first-order adjustment was made for the bladder-wall mass based on the patient's total-body mass. Mean organ absorbed doses were calculated with the MIRD formalism and the standard man model using the MIRDOSE3 software program. RESULTS: The absorbed doses (mean +/- SD) ranged from 0.00057 +/- 0.000281 cGy/MBq (to skin) to 0.00868 +/- 0.00481 cGy/MBq (to bladder wall) (voiding intervals, 1-2 h), and the effective dose equivalent was 0.00177 +/- 0.000152 cSv/MBq. CONCLUSION: The maximum absorbed dose among all tissues in all 10 studies, 0.0151 cGy/MBq, occurred for the urinary bladder wall (with hydration and 1- to 2-h voiding intervals). To ensure that the maximum normal-tissue absorbed dose is kept below the recommended maximum permissible dose of 5 cGy per single administration, a maximum administered activity of 331 MBq (5 cGy/[0.0151 cGy/MBq]) is recommended for (18)F-FDHT.     

Primary spinal intradural extramedullary hydatid cyst in a child

BACKGROUND/OBJECTIVE: Spinal hydatid cyst is a serious form of hydatid disease affecting less than 1% of the total cases of hydatid disease. We present a case of pathologically confirmed primary intradural spinal cyst hydatid in an otherwise healthy patient who showed no other evidence of systemic hydatid cyst disease. CASE REPORT: An 8-year-old boy presented with back pain, left leg pain, and difficulty in walking. The patient had no other signs of systemic hydatid cyst disease. An intradural extramedullary cystic lesion was identified with magnetic resonance imaging and was shown to be a hydatid cyst by histopathologic examination after the surgical removal. CONCLUSION: Although extremely rare, primary intradural extramedullary hydatid cyst pathology might be the cause of leg pain and gait disturbance in children living in endemic areas.     

Validation of GATE Monte Carlo simulations of the GE Advance/Discovery LS PET scanners

The recently developed GATE (GEANT4 application for tomographic emission) Monte Carlo package, designed to simulate positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanners, provides the ability to model and account for the effects of photon noncollinearity, off-axis detector penetration, detector size and response, positron range, photon scatter, and patient motion on the resolution and quality of PET images. The objective of this study is to validate a model within GATE of the General Electric (GE) Advance/Discovery Light Speed (LS) PET scanner. Our three-dimensional PET simulation model of the scanner consists of 12 096 detectors grouped into blocks, which are grouped into modules as per the vendor's specifications. The GATE results are compared to experimental data obtained in accordance with the National Electrical Manufactures Association/Society of Nuclear Medicine (NEMA/SNM), NEMA NU 2-1994, and NEMA NU 2-2001 protocols. The respective phantoms are also accurately modeled thus allowing us to simulate the sensitivity, scatter fraction, count rate performance, and spatial resolution. In-house software was developed to produce and analyze sinograms from the simulated data. With our model of the GE Advance/Discovery LS PET scanner, the ratio of the sensitivities with sources radially offset 0 and 10 cm from the scanner's main axis are reproduced to within 1% of measurements. Similarly, the simulated scatter fraction for the NEMA NU 2-2001 phantom agrees to within less than 3% of measured values (the measured scatter fractions are 44.8% and 40.9 +/- 1.4% and the simulated scatter fraction is 43.5 +/- 0.3%). The simulated count rate curves were made to match the experimental curves by using deadtimes as fit parameters. This resulted in deadtime values of 625 and 332 ns at the Block and Coincidence levels, respectively. The experimental peak true count rate of 139.0 kcps and the peak activity concentration of 21.5 kBq/cc were matched by the simulated results to within 0.5% and 0.1% respectively. The simulated count rate curves also resulted in a peak NECR of 35.2 kcps at 10.8 kBq/cc compared to 37.6 kcps at 10.0 kBq/cc from averaged experimental values. The spatial resolution of the simulated scanner matched the experimental results to within 0.2 mm.     

Intrinsic and synaptic mechanisms determining the timing of neuron population activity during hippocampal theta oscillation

Hippocampal theta (3-8 Hz) is a major electrophysiological activity in rodents, which can be found in primates and humans as well. During theta activity, pyramidal cells and different classes of interneurons were shown to discharge at different phases of the extracellular theta. A recent in vitro study has shown that theta-frequency oscillation can be elicited in a hippocampal CA1 slice by the activation of metabotropic glutamate receptors with similar pharmacological and physiological profile that was found in vivo. We constructed a conductance based three-population network model of the hippocampal CA1 region to study the specific roles of neuron types in the generation of the in vitro theta oscillation and the emergent network properties. Interactions between pairs of neuron populations were studied systematically to assess synchronization and delay properties. We showed that the circuitry consisting of pyramidal cells and two types of hippocampal interneurons [basket and oriens lacunosum-moleculare (O-LM) neurons] was able to generate coherent theta-frequency population oscillation. Furthermore, we found that hyperpolarization-activated nonspecific cation current in pyramidal cells, but not in O-LM neurons, plays an important role in the timing of spike generation, and thus synchronization of pyramidal cells. The model was shown to exhibit the same phase differences between neuron population activities found in vivo, supporting the idea that these patterns of activity are determined internal to the hippocampus.     

梅干腹综合征一例

患儿男。4岁。出生后发现腹部膨隆。系二胎二产出生,母孕期正常,足月顺产。第一胎系双胎,因早产33周而夭折。家族史无异常。体检：一般情况可,发育营养尚可,生长发育同正常同龄儿;查体合作;无特殊面容;呈漏斗胸,肋缘外翻,心肺检查未见异常。腹膨隆．立位时成梨形;腹壁松软 皮肤粗糙,多处皱褶,可见明显肠型．触诊全腹柔软无张力．无肌肉收缩感(图1)。可触及肝、脾、肾脏及肠管。脊柱四肢无畸形．运动自如。阴茎短小,双侧睾丸未触及。     

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目的探讨合并癫疒间的脑性瘫痪患儿的临床特点及癫疒间治疗效果。方法总结1999年10月至2004年5月在西安交通大学第二医院住院的合并癫疒间的脑性瘫痪患儿的癫疒间发生率、临床类型、头颅计算机体层成像(CT)和(或)磁共振成像(MRI)、脑电图等方面的特点以及抗癫疒间治疗效果。结果139例脑性瘫痪患儿中有32例合并癫疒间,占23.0%(32/139);常见的癫疒间类型为强直阵挛发作12例(37.5%)和部分性发作6例(18.8%);25例(78.1%)癫疒间首发于1岁前;合并癫疒间脑性瘫痪儿童的头颅影像异常及脑电图异常分别占30例(93.8%)和27例(84.4%);常见的头颅影像异常为脑发育不良11例(36.7%)、脑积水6例(20.0%),余为脑萎缩、缺氧缺血性脑病样改变等13例(43.3%);脑电图异常中局灶性和弥漫性所占比例分别为48.2%(13/27)和51.8%(14/27);癫疒间多发生于痉挛性脑性瘫痪中(68.8%);81.3%(26/32)的癫疒间需要2种及2种以上的抗癫疒间药物治疗。结论脑性瘫痪患儿中癫疒间的发生率较高,其头颅影像学和脑电图分别以脑发育不良和弥漫性背景活动异常伴疒样波发放为主;脑性瘫痪儿童的癫疒大多为难治性,需要联合用药治疗。