体外实验中宝石CT能谱成像技术血管成像最佳单能量图像的选择

目的 通过体外实验探讨宝石CT能谱成像(GSI)技术血管成像的最佳单能量图像。方法 将非离子型对比剂(碘海醇,300 mgI/ml)用生理盐水稀释成10种不同浓度的溶液置于2 ml硬塑料试管中,浓度依次为1.04、1.17、1.56、2.08、2.34、3.13、4.17、4.69、6.25及9.38 mgI/ml。用猪肉包裹试管后置入水槽中,并加以固定。使用能谱CT进行GSI模式扫描,利用GSI处理/重建平台获得40~70 keV间距为5 keV的7种单能量图像及140 kVp混合能量图像,比较各单能量图像及混合能量图像的CNR、SNR和噪声;并根据管壁边缘锐利度、肌肉及脂肪组织的显示情况及噪声3个方面对图像质量进行主观评价,得出图像质量评分,并进行统计学分析。结果 50 keV(13.28±3.06)及55 keV图像的CNR(14.68±3.75)高于其他单能量图像和混合能量图像(P<0.001),50 keV及55 keV图像间差异无统计学意义(P=0.139)。55 keV图像的SNR(22.18±3.95)高于其他单能量图像和混合能量图像(P<0.001)。与混合能量图像比较,65 keV图像的噪声降低程度(23.08%)优于其他单能量图像(P=0.002)。55 keV的图像质量评分(11.76±0.33)高于其他单能量图像和混合能量图像(χ²=73.05,P<0.001)。结论 本实验中,55 keV图像是能谱CT GSI血管成像的最佳单能量图像,图像质量优于140 kVp混合能量图像。     

能谱CT显示胰腺血管网：与混合能量CT对照

目的 探讨能谱CT单能图像改善胰腺血管网显示的能力。方法 将47例非胰腺病变患者随机分为能谱CT组（27例）和VCT扫描组（20例）。由1名观察者测量11组能谱CT单能图像（40~140 keV,间隔10 keV）及1组VCT混合能量图像的噪声、CNR、信号强度比（SIR）、SNR值,并行VR、MIP重建;2名观察者独立盲法观察,以5分法评价显示胰腺血管网的能力。结果 能谱CT 50~70 keV图像胰腺血管网评分明显高于40 keV、80~140 keV（P均<0.05）;2名观察者对各组单能图像评分的一致性为一般或良（0.403~0.843）。70 keV组图像噪声明显低于40~60 keV组（P<0.05）。能谱CT 70 keV图像胰腺血管网评分明显优于120 kVp图像（P<0.05）;在噪声、扫描剂量无显著差异的情况下,与120 kVp图像比较,CT 70keV胃十二指肠动脉CT值、CNR、SIR、SNR分别提高了29.06%、58.07%、22.22%、31.28%。结论 与混合能量CT相比,能谱CT单能图像能更好地显示胰腺血管网。     

探讨宝石CT能谱成像技术减除脊柱金属植入物伪影的最佳单能量

目的 评价宝石CT能谱成像技术(GSI)单能量成像在减除脊柱金属植入物伪影方面的应用价值,寻求图像质量最佳的单能量成像点。 方法 对19例带有脊柱金属植入物的患者行宝石能谱CT GSI扫描。获得能谱扫描数据后,利用能谱技术,每隔10 keV重建40~140 keV共11组单能量图像,于每组图像中分别选取伪影最重层面(A)和无或少伪影层面(B)的两幅图像行ROICT值和SD值测定,分别记录为CT1、CT2和SD1、SD2,计算伪影指数(AI)。采用配对t检验比较CT值,LSD-t检验比较AI值。 结果 40~140 keV 11组单能量图像中,120 keV单能量图像组,A、B两层面CT值分别为(41.41±9.48)HU和(41.91±7.97)HU(t=－0.21,P>0.05);其他10组两两比较差异均有统计学意义(P均<0.05)。70~140 keV时,两两比较,AI值差异均无统计学意义(P均>0.05);40~60 keV时,与其他能量组两两比较,AI值差异均有统计学意义(P均<0.05)。 结论 能谱CT利用能谱成像技术可有效减除金属植入物的伪影,120 keV为图像质量最佳的单能量成像点,70 keV为伪影减除的分界点。     

能谱成像技术减除125I粒子植入术后体内伪影

目的 探讨宝石CT能谱成像(GSI)和金属伪影去除序列(MARs)在减少金属粒子伪影的价值。方法 选择19例腹部植入¹²⁵I粒子的患者,在相同CT剂量指数(CTDI)条件下进行GSI扫描。获得140 kVp混合能量图像;GSI在60~110 keV(间距10 keV)重建6种单能量图像及对应的MARs能谱图像。由3名放射医师主观评价3种成像方式的图像质量差异,并计算¹²⁵I粒子邻近病变组织的对比噪声比(CNR)、噪声值及伪影指数(AI)。结果 ①70 keV图像质量明显高于混合能量的图像,主观评分差异具有统计学意义(t=11.95,P<0.001);②不同keV单能量图像中,70 keV图像的¹²⁵I粒子邻近组织CNR最佳(0.81±0.20),且主观评分最高(2.79±0.21);80 keV图像的AI最低71.78±20.70;110 keV图像中伪影长度最小 ;③MARs能谱图像中高密度金属伪影减少,¹²⁵I粒子不同程度被消除并产生低密度伪影。110 keV图像中金属伪影的长度小于混合能量图像及MARs能谱图像(t=3.42、3.97,P均<0.05);MARs能谱图像与混合能量及70 keV图像的CNR差异有统计学意义(t=3.63、4.05,P均<0.01)。结论 GSI技术能有效减少CT图像中¹²⁵I粒子的金属伪影,提高图像质量,改善¹²⁵I粒子植入术后邻近组织的显示情况。MARs技术不能有效消除放射性粒子产生的伪影。     

低浓度对比剂结合能谱CT最佳单能量成像对胆囊动脉的显示能力

目的 评价低浓度对比剂结合能谱CT最佳keV成像技术对胆囊动脉的显示能力。方法 前瞻性选取体质量指数为25.15~34.91 kg/m²的90例患者,按照扫描方式和对比剂浓度分为能谱扫描低浓度对比剂组（A组）和常规扫描高浓度对比剂组（B组）。对两组分别测量胆囊动脉、相同层面竖脊肌的CT值及竖脊肌CT值的标准差,计算胆囊动脉与竖脊肌间的CNR和SNR。对胆囊动脉行VR、MIP及CPR。由2名观察者分别独立评价两组重建后的图像质量。对以上指标进行统计学分析,并进行观察者间一致性检验。结果 能谱CT单能量成像显示胆囊动脉的平均最佳keV值为（60.62±5.85）keV。A组胆囊动脉CT值、竖脊肌CT值均高于B组（P均<0.05）,但两组CNR及SNR差异均无统计学意义（P均>0.05）。两名观察者主观评分一致性良好（Kappa=0.804、0.773）,主观评分差异无统计学意义（t=-0.243,P=0.808）。结论 低浓度对比剂结合能谱CT最佳单能量成像技术可提供良好的胆囊动脉的图像质量,并可显著降低对比剂用量。     

光谱CT虚拟单能量图像优化胸部增强CT显示肺动脉北大核心CSCD

目的评价光谱CT虚拟单能量图像(VMI)优化胸部增强CT显示肺动脉的价值,观察可否以碘密度预测其最佳单能级水平。方法分析40例胸部增强CT显示肺动脉强化不佳(肺动脉干CT值<200 HU)患者资料,分别以常规120 kVp混合能量图像(常规图像)和40~70 keV VMI(间隔10 keV)测量并计算肺动脉干、左肺动脉、右肺动脉、左上肺动脉、左下肺动脉、右上肺动脉及右下肺动脉的CT值、噪声(SD)、信噪比(SNR)及对比噪声比(CNR),并以5分法评价图像质量。以肺动脉CT值>200 HU且主观评分≥3分选择最佳优化VMI,将该能级下VMI的主观、客观指标与常规图像进行比较;以线性回归模型评估平均碘密度与最佳单能级的相关性。结果于40~70 keV VMI所测肺动脉CT值、SNR、CNR及主观评分均随能级降低而递增,SD值则递减,与常规图像相比差异多有统计学意义(P<0.05)。40例中,36例(36/40,90.00%)图像经优化达到诊断要求;最佳单能级水平下,优化图像的CT值、SNR和CNR分别较常规图像提高59.61%、76.51%和124.03%而SD值降低12.77%,主观评分提高148.15%。线性回归模型显示,平均碘密度与最佳单能级呈正相关(R 2=0.80)。结论光谱CT VMI可优化胸部增强CT显示肺动脉质量;根据碘密度可预测最佳单能级水平。     

能谱CT最佳单能量成像去除体模对比剂硬化伪影及图像噪声

目的 选择CT能谱成像的最佳单能量水平,以最小化对比剂所致的线束硬化伪影(BHA)和图像噪声。方法 9支含有不同浓度碘溶液(浓度分别为100.0、50.0、30.0、20.0、10.0、5.0、2.0、0.7、0.4 mg/ml)的硬塑料试管,将浓度最高者置于塑料体模的中心,将其余8支按浓度梯度依次等距环形排列于体模周边。分别采用常规120 kVp混合能量模式和能谱(GSI)模式进行扫描,共获得1组120 kVp混合能量和21组单能量图像。由2名放射科医师采用4分量表对图像质量进行主观目测评分,测量并比较图像内指定区域(硬化伪影最明显处)的噪声值(以SD值表示)及BHA。选取噪声及BHA最低、图像主观评分最高的单能量图像,与常规120 kVp混合能量图像进行比较。采用单因素方差分析比较选定组间数据差异。结果 21组单能量图像中,85 keV和90 keV图像的主观评分最高,图像噪声及BHA最低。与120 kVp混合能量图像比较,上述两组单能量图像噪声分别降低了约82.5%和82.0%(P均<0.001),BHA分别降低了约96.1%和95.7%(P均<0.001),主观评分提高了1倍。但85 keV及90 keV两组单能量图像间噪声和BHA差异无统计学意义(P=0.232、0.817)。结论 与传统120 kVp混合能量图像相比,CT能谱成像能够提供一系列单能量图像,其中85 keV和90 keV最佳单能量图像能够显著降低图像噪声和对比剂产生的线束BHA,提高图像质量。     

双能量CT联合金属伪影削减算法显示微弹簧圈定位肺结节

目的 评价双能量能谱CT（DESCT）扫描获得的虚拟单色谱（VMS）图像联合金属伪影削减（MAR）算法在CT引导微弹簧圈定位肺结节中的应用价值。方法 选取80例CT引导微弹簧圈定位的肺结节患者,微弹簧圈置入后,对其行DESCT扫描。选择最佳光子能量水平,在最佳能量水平重建VMS图像及经MAR算法处理的VMS图像（VMS+MAR）,比较VMS、VMS+MAR图像质量主观评分的差异。结果 选择74 keV为最佳能量水平。74、90、110、140 keV VMS+MAR图像质量优于50 keV图像（P均<0.05）;74、90、110、140 keV水平VMS+MAR图像质量评分差异均无统计学意义（P均>0.05）。74 keV VMS+MAR图像质量优于VMS图像（P<0.05）。2名观察者主观评分一致性较好（Kappa值=0.78）。结论 74 keV VMS图像联合MAR算法可有效抑制微弹簧圈金属伪影,清晰显示肺结节。     

双能CT在增强检查中的应用:体模研究

目的 探讨双能CT(DECT)成像技术在增强检查中的应用价值.方法 将浓度不同的碘乙醇溶液和碘水溶液封装于塑料试管中,按顺序固定后浸浴在装满水的截面近似椭圆、周长为86 cm的尼龙复合膜中制成体模原型.于Siemens Somatom Definition Flash扫描仪分别采用常规上腹部条件进行单能和DECT扫描.于专用图像工作站采用Liver VNC软件测量各溶液的碘浓度,并回顾性重建权重为0.5的线性混合图像、最优非线性混合图像(OCM)和CNR最大的单能量图像.结果 两种溶液碘浓度测量值与理论值均呈强相关(r=0.998、0.999,P均 <0.001),但相对误差较大(最大值25.00%).OCM图像和65 keV单能量图像的CNR碘浓度比均显著高于120 kVp图像(P <0.001).结论 DECT可准确区分不同碘溶液的浓度,应用于增强检查可提高图像质量.     

双能CT非线性融合技术提高头颅CTA图像质量的临床应用

目的 探讨双源双能量CT非线性融合（NLB）技术提高头颅CTA图像质量的应用价值。方法 对线性融合（LB）图像不佳或不能满足诊断要求（主观评分≤3分）的53例双能头颅CTA图像行NLB处理,图像分为80 kV组、140 kV组、LB组及NLB组。测量并计算4组图像颈内动脉床突段、大脑中动脉、基底动脉及脑干的CT值、标准差（SD）、SNR和CNR;并对图像质量进行主观评分。分别比较4组间CT值、SD值、SNR和CNR及图像质量评分的差异。结果 LB组与NLB组图像主观评分差异有统计学意义[（2.68±0.47）分 vs （3.19±0.59）分, P<0.01]。LB组与NLB组可诊断率分别为69.81%（37/53）、83.02%（44/53）,图像优良率分别为0（0/53）、37.74%（20/53）,差异有统计学意义（P均<0.01）。4组间各部位CT值、SD、SNR及CNR各组间比较差异均有统计学意义（P均<0.05）,80 kV组CT值最高,NLB组高于LB组（P<0.05）;NLB组SNR、CNR均优于其他3组（P均<0.05）。结论 NLB技术可改善和提高头颅CTA图像质量,提高图像的可诊断率和优良率。     

Prospective Comparison of Temperature Guided Microwave and Radiofrequency Catheter Ablation in the Swine Heart

Microwave energy has been proposed as an alternative to radiofrequency energy for use during catheter ablation procedures. The purpose of this study was to prospectively compare, in an animal model, the lesion size associated with temperature guided catheter ablation using either microwave or radiofrequency energy. Eleven swine underwent catheter ablation with either radiofrequency (N = 4) or microwave energy (N = 7). In each animal catheter ablation was performed at 7–15 sites. At each site energy was delivered for 60 seconds using closed loop feedback temperature control to achieve a target temperature of 70°C. Cardiac catheterization was performed before and after ablation. Animals were sacrificed approximately one month following the ablation procedure. Analysis of lesion size demonstrated that overall lesions created using radiofrequency energy were larger than those created using microwave energy. In the ventricle, lesions created using microwave energy were longer, but had a similar width and depth as those created using radiofrequency energy. An important relation was observed between tbe depth of lesions created using microwave energy and catheter stability, as evidenced by the temperature profile. Overall, lesions created using microwave energy are smaller than those created using radiofrequency energy. Catheter stability has an important impact on lesion size.     

Indirect calorimetry during treadmill walking — a study of two methods

Walking is a complex process and the physiotherapist must focus on physical signs as well as functional and practical tests to evaluate treatment. Measurement of energy expenditure during level walking is a useful objective parameter for assessing walking as being a valuable supplement to evaluate the outcome of physiotherapy. This study had two purposes. The first purpose was to investigate whether sampling and measurement of oxygen consumption were reproducible when using two different devices during walking on a treadmill. A second purpose was to find out whether the measurements were sensitive enough to reveal differences in energy expenditure and respiratory quotient (RQ) during different walking speeds. Ten healthy students (mean age 22 years; range 20–25 years) volunteered in the test-retest of a slightly adjusted Deltatrac metabolic monitor. Thirteen volunteers (mean age 45 years; range 31–57 years) participated in the test-retest of Sensormedics 2900. In the first test, the subjects walked for 10 min in order to get a steady state both at an individual comfortable speed and at a preset speed. The retest was done with the same design and within 2 weeks. Nobody experienced any discomfort during the tests. The repeatability of measuring energy expenditure and RQ was acceptable for both methods and the methods were sensitive in revealing differences in energy expenditure during different walking speeds. The RQ were, however, too low when using the Deltatrac monitor, probably as a result of low air flow. We therefore conclude that only the method using Sensormedics 2900 may be used for the evaluation of energy expenditure during walking on a treadmill.     

Physical and Dynamic Characteristics of DC Ablation in Relation to the Type of Energy Delivery and Catheter Design

We evaluated and compared the in vitro characteristics of direct current ablation using high energy ablation (Hewlett-Packard defibrillator) and a new form of low energy ablation (low energy ablation power supply, Cardiac Recorders, UK). Two new catheters with a large distal electrode have been recently introduced for catheter ablation: a low energy 7F bipolar catheter (Bard) with a contoured distal electrode, and a 7F deflectable catheter with a 4-mm tip (Mansfield). In vitro studies were carried out in a large tank filled with physiological saline while recording voltage, current, and pressure. High speed cinematography at 32,000 frames per second (Cordin, Utah) was done to assess the dynamic behavior of the vapor globe with both systems of energy delivery. We evaluated shocks of 50, 100, 150, 200, and 300 joules with the conventional system, and shocks of 10, 15, 20, 30, and 40 joules with the new system, and also compared the effects of varying catheter design with both systems of energy delivery. The conventional system using high energy showed significant arcing and increases in pressure. Low energy direct current ablation produces nonarcing shocks with 20 joules or less, and significantly less vapor globe and gas formation during arcing shocks, with a shorter duration of increase in pressure. This new system using low energy direct current may reduce the risk and complications reported with high energy ablations.     

Feasibility of Radiofrequency Powered, Thermal Balloon Ablation of Atrioventricular Bypass Tracts Via the Coronary Sinus: In Vivo Canine Studies

Radiofeequency catheter ablation of left sided accessory pathways is technically demanding and usually requires left heart catheterization. The feasibility of creating lesions from within the coronary sinus of sufficient size to ablate accessory pathways in humans using a thermal balloon catheter was studied in 20 dogs. In group 1 (n == 14), 17 thermal inflations were performed in 12 dogs at either 70°, 80°, or 90°C each for 30 or 60 seconds (in 2 dogs two non-thermal control inflations were performed). Animals were sacrificed 6.3 ± 1.6 days later. In group 2 (n = 6), seven thermal inflations were performed at 90°C each for 180, 300, or 360 seconds. Group 2 animals received antiplatelet and anticoagulant therapy for 1 week and were sacrificed at 13 ± 10.7 days. In both groups, hemodynamic, angiographic, and electrocardiographic studies were performed at baseline, 1 hour after inflation, and prior to sacrifice. All dogs remained clinically stable throughout the procedure and no complications were attributed to the effect of thermal inflation. Thermal lesions measured 14.4 ± 4.4 mm in length and extended from the coronary sinus intima to a mean depth of 2.9 ± 1.2 mm (range 1.4-6.5 mm). Group 2 lesions were significantly deeper than group 1 lesions (P = 0.03). Of the 24 thermal lesions created, atrial necrosis was present in 23 and ventricular necrosis in 11. In all lesions there was some degree of either atrial necrosis, ventricular necrosis, or both. A variable degree of coronary sinus thrombus was present in 18 dogs without clinical sequelae. It is concluded that radiofrequency balloon heating via the coronary sinus can create thermal lesions in the atrioventricular sulcus of dogs that may be of sufficient size to ablate accessory left-sided pathways in humans. (PACE 1995; 18: 1518-1530)     

Catheter Ablation of Canine Myocardium with Radiofrequency Energy

High energy direct-current shocks delivered via an electrode catheter have been used to ablate the atrioventricular junction since 1981.¹ This technique has also been adapted for ablation of other cardiac tissues including the atrium, posterior interatrial septum and ventricular myocardium. The limitations of this technique include inadequate control of the energy source, poor understanding of the mechanisms of myocardial injury, and untoward complications possibly related to barotraumatic injury. Radiofrequency energy has been shown to create ablative injury when delivered lo the myocardium via standard electrode catheters. This report will review our experience with radiofrequency catheter ablation of the canine myocardium with specific emphasis on the biophysical aspects of lesion formation.     

彩色多普勒能量图在膀胱占位性病变中诊断价值

膀胱良性肿瘤、恶性肿瘤以及非肿瘤性增生在影像学检查中均显示占位征象，定性诊断存在一定困难，尤其是后者误诊率很高。本文通过回顾５５例经膀胱镜活检和手术病理诊断的膀胱占位病变的Ｂ超、彩色多普勒能量图（ＣＤＥ）及病理资料对照分析研究。结果发现不同性质的占位，其ＣＤＥ的血管形态学及血流动力学参数具有显著差异，定性诊断率可达９３．３％，明显弥补了其它影像学检查的不足，提高诊断符合率。作者认为：ＣＤＥ血流参数中的阻力指数（ＲＩ）值可以作为判断膀胱占位良恶性的重要依据。即ＲＩ＜０．５５考虑为恶性，ＲＩ＞０．７０则诊断为良性     

彩色多普勒能量图在诊治腹膜后肿块中的应用价值

目的探讨彩色多普勒能量图（ＣＤＥ）在诊治腹膜后肿块（ＲＰＭ）中的应用价值。方法对３４例ＲＰＭ进行二维超声（２Ｄ）和ＣＤＥ检查,采用Ａｄｌｅｒ半定量法对肿块血流信号进行分级。结果①ＣＤＥ对ＲＰＭ的定位准确性为９１％。②根据ＣＤＥ血流信号分级,０、１级提示良性肿块,２、３级提示恶性肿块,则其判断ＲＰＭ良恶性的敏感性为８５％、特异性为８９％、准确性为８８％。③ＣＤＥ能够良好显示肿块与周围大血管的位置关系,其显示率为６２％。结论ＣＤＥ结合２Ｄ能够明显提高对ＲＰＭ定位和良恶性判断的准确性,为临床制定治疗方案提供重要依据,并可作为非手术治疗ＲＰＭ疗效判断的有效客观指标之一。     

Effects of radiation exposure and storage on the energy metabolome of platelets in whole blood

Background

Exposure to radiation through battlefield use of nuclear weapons, terrorist attacks or accidents at nuclear power plants is a current concern for the military. Beyond the risk of exposure to personnel is the intentional or accidental irradiation of our blood banking supply system. It is unknown how large doses of ionizing radiation affect storage of blood and blood products, including platelets. The major function of platelets is clot formation which includes aggregation, shape change, vesicle release, and fibrinogen attachment; these tasks require a significant amount of energy. Here, we determine whether the ionizing radiation effects the energy metabolome of platelets in storage.

Study Design and Methods

Fresh whole blood from healthy volunteers was subjected to 0, 25, or 75Gy of X-irradiation, and stored at 4°C. Platelets were isolated from stored WB at 0, 1, 7, 14, and 21 days of storage. Krebs cycle intermediates, nicotinamide adenine dinucleotides, and the tri-, di, and mono- phosphorylated versions of adenosine and guanosine were extracted and measured by tandem mass spectroscopy.

Results

Irradiation at either 25Gy or 75Gy had no significant effect on the amount of any metabolite measured compared to control (0Gy). However, there was a significant fall over time in storage for most of the metabolites measured.

Discussion

These data show that irradiation at high doses has no effect on the concentration of the energy metabolome of platelets derived from whole blood stored in 4°C for up to 21 days and suggests that platelets can maintain their metabolome even after radiation exposure.     

能谱CT单能量模式与传统单电压扫描模式的相同CT值:体模研究

目的寻找能谱CT(GSI)显示不同碘浓度体模CT值与传统的单电压扫描(TPXI)相同时的单能量值(MEI)。方法应用聚丙烯材料容器型体模装载5、10、15和20 mg I/ml的碘对比剂,分别在空气背景及软组织背景下应用相同放射剂量的GSI扫描及TPXI扫描,TPXI扫描时分别采用80、100、120和140 kVp各采集一遍数据,两种扫描方式使用相同的转速(0.8 s)及Pitch值(0.984)对比剂对应TPXI扫描相同CT值的MEI。结果在TPXI不同的能量80、100、120和140kV下,MEI对应相同碘浓度CT值在空气背景下为52±1.0、58±1.3、62±1.4和66±1.3 keV;在软组织背景下为53±0.8、59±1.0、64±1.0和68±1.0 keV。结论 MEI在不同碘浓度时不同背景下均与TPXI各自kVp有良好的对应关系。     

Metabolic aspects of HIV: associated wasting

Despite recent progress in the treatment of human immunodeficiency virus (HIV) infection, wasting syndrome (WS) is now one of the major aspects of acquired immunodeficiency syndrome (AIDS). Malnutrition in HIV infected patients is characterised by a predominant loss of body cell mass (BCM), the amount of functional protoplasm in non-adipose tissue. This loss of BCM is correlated with a higher risk of AIDS events and a greater risk of mortality. If anorexia plays a major role in the development of the WS, some abnormalities in the metabolism drive the predominant loss of BCM. In the stable state, the resting energy expenditure (REE) is increased by about 10%. The REE is significantly correlated with the whole body protein turn over as measured by C¹³ leucine. This particular and only metabolic situation is associated with an increased insulin sensitivity and a high level in de novo hepatic lipogenesis. During periods of secondary infections, patients had a striking average weight loss, resulting from the combination of anorexia and dramatic elevated REE.