通量平滑度在胸中上段食管癌容积弧形调强中的剂量学比较

目的对比Monaco计划系统中3种通量平滑度参数在胸中上段食管癌容积弧形调强(VMAT)中的剂量学差异。方法选取15例胸中上段食管癌病例,相同优化条件下分别使用高、中和低3种通量平滑度(高组、中组、低组)进行VMAT计划设计和评估。比较3组计划靶区的D95、Dmean、适形度指数(CI)、均匀性指数(HI)、危及器官的受量和机器跳数。结果3组计划相比靶区的D95、Dmean、CI和HI等参数差异均无统计学意义(P>0.05)。高组与中和低组相比,心脏的V40、Dmean、双肺的V10、V20、Dmean和子野数差异无统计学意义(P>0.05);与中组和低组相比,高组心脏的V30和脊髓危及器官的计划体积(PRV)Dmax均降低(t=-2.167、-0.999,P<0.05);高组双肺的V5高于中和低组(t=1.306、-2.027、P<0.05);与中组和低组相比,高组的机器跳数降低(t=-3.148、-6.692、P<0.05)。与中组相比,低组的心脏V30和Dmean,脊髓PRV Dmax均增加(t=0.411、0.589、0.013,P<0.05),而肺的V5降低(t=0.423,P<0.05)。结论3组计划均能满足临床要求。综合考虑计划质量和执行效率,建议采用高通量平滑度用于中上段食管癌容积弧形调强放疗。     

Standardization of F using the 4π(β+γ) integral counting technique

Α 4π(β+γ) integral counting technique using a 4πβ−4πγ detector configuration was adopted for the standardization of ¹⁸F. In this technique, the β-detector is composed of two thin plastic scintillators sandwiching the source, coupled with a slender photomultiplier tube. The β-detector part with the source was inserted into a large well-type NaI(Tl) scintillation detector for γ-ray detection, making a 4πβ−4πγ coincidence counting system. In this work, positron particles were detected with high efficiency in the β-channel and annihilation quanta were also detected with high efficiency in the 4πγ channel. The very small inefficiency of the 4π(β+γ) integral counter for the β-plus branch has been confirmed by EGS5 Monte Carlo simulation. The result using this technique agreed within the uncertainties with the result obtained by the conventional 4πβ−γ coincidence counting with the efficiency extrapolation technique using the same detector configuration and a conventional 4πβ−γ coincidence counter.     

Experimental hypoxemic hypoxia: Changes in R2* of brain parenchyma accurately reflect the combined effects of changes in arterial and cerebral venous oxygen saturation

A two-dimensional T₂*-weighted gradient-echo sequence was used to image the rat brain before and during graded hypoxemia. Changes in R₂* (δR₂*) with respect to the control state were calculated for brain parenchyma and were compared with changes in hemoglobin saturation measured from both arterial and jugular venous blood samples. δR₂* was first correlated with the changes in arterial (δYa) and venous (δYv) hemoglobin saturations individually. Although a general trend toward a linear relationship with δR₂* was observed for both δYa and δYv, neither alone was strong (correlation coefficients r = 0.71 and 0.75 for δYa and δYv, respectively, and standard errors of the regression (SER) = 0.52 and 0.48 for δYa and δYv, respectively). However, when an “effective” cerebral blood hemoglobin saturation change (δYb) was constructed that takes into account the approximate weighting of the contributions from the arterial and venous phases of the circulation (δYb = 0.75 × δYv + 0.25 × δYa), a stronger correlation with δR₂* was obtained and there was less variance (r = 0.87 and SER = 0.35). It is concluded that an appropriate weighting of the contributions of arterial and venous phases of the circulation must be taken into account in modeling the volume susceptibility effects of deoxyhemoglobin on R₂* of brain parenchyma. In this way, a more accurate relationship between δR₂* and δYb can be obtained.     

T1ρ relaxation and its application to MR histology

The application of T_1P as an alternative contrast parameter in high-field magnetic resonance histology (MRH) has been investigated. Spectroscopic measurements of T_1P were performed on 5.75% agar and 1.0 mM MnCl₂ phantoms at 9.4 T to validate the accuracy of the imaging measurements. Image studies were performed at 2.0 and 9.4 T on perfusion-fixed 17.5-day-old mouse embryos. T_1′ T_2′ and T_1P relaxation times were calculated for the phantoms and muscle, diencephalon, and liver tissues. The 5.75% agar phantom and all tissues showed T_1P dispersion with B_1L, whereas the 1.0 mM MnCl₂ phantom showed no significant B_1L dependence. T_1P dispersion with B⁰ was observed arising from the effects of diffusion through susceptibility-induced gradients. T_1P shows promise as a contrast parameter in high-field MRH because it is capable of producing T₂-like contrast without the susceptibility artifacts associated with T₂-weighted images.     

Delayed gadolinium‐enhanced magnetic resonance imaging (dGEMRIC) of hip joint cartilage in femoroacetabular impingement (FAI): Are pre‐ and postcontrast imaging both necessary?

The purpose of this study was to assess if delayed gadolinium MRI of cartilage using postcontrast T₁ (T_1Gd) is sufficient for evaluating cartilage damage in femoroacetabular impingement without using noncontrast values (T₁₀). T_1Gd and ΔR₁ (1/T_1Gd ? 1/T₁₀) that include noncontrast T₁ measurements were studied in two grades of osteoarthritis and in a control group of asymptomatic young‐adult volunteers. Differences between T_1Gd and ΔR₁ values for femoroacetabular impingement patients and volunteers were compared. There was a very high correlation between T_1Gd and ΔR₁ in all study groups. In the study cohort with Tonnis grade 0, correlation (r) was ?0.95 and ?0.89 with Tonnis grade 1 and ?0.88 in asymptomatic volunteers, being statistically significant (P < 0.001) for all groups. For both T_1Gd and ΔR₁, a statistically significant difference was noted between patients and control group. Significant difference was also noted for both T_1Gd and ΔR₁ between the patients with Tonnis grade 0 osteoarthritis and those with grade 1 changes. Our results prove a linear correlation between T_1Gd and ΔR₁, suggesting that T_1Gd assessment is sufficient for the clinical utility of delayed gadolinium MRI of cartilage in this setting and additional time‐consuming T₁₀ evaluation may not be needed. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

上胸段食管癌调强放射治疗中淋巴结意外照射的剂量学研究

目的比较上胸段食管癌容积旋转调强放射治疗(VMAT)与5野的静态调强放射治疗(5F-IMRT)在淋巴结意外照射中的剂量学差异,评估两种方式在上胸段食管癌放射治疗中的剂量学特点。方法选取20例典型的上胸段食管癌患者,在进行靶区勾画时,肿瘤区(GTV)、临床靶区(CTV)不包含所有淋巴结,而将淋巴结单独勾画作为正常组织。对这20例患者分别制定两套计划,即VMAT与5F-IMRT,主要的计划评估参数为靶区的适形指数(CI)、均匀指数(HI),以及接受相应处方剂量水平照射体积百分比V95、V110;危及器官(OAR)评估包括肺的Dmean、V5、V20、V30,心脏的Dmean、V25,脊髓的Dmax,机器调数(MU)。同时评估各个淋巴结的等效均衡剂量(EUD)与接受40 Gy照射剂量的体积百分比V40。结果5F-IMRT计划在V95%上具有较高的计划靶区(PTV)剂量覆盖率(t=-9.4,P<0.05),VMAT计划的适形指数(CI)优于5F-IMRT(t=-5.3,P<0.05);5F-IMRT计划较VMAT计划降低平均肺V510.9%(t=-7.8,P<0.05),降低平均脊髓Dmax 9%(t=-10.2,P<0.05);VMAT计划较5F-IMRT计划降低平均MU 18.6%(t=-6.2,P<0.05);5F-IMRT计划在所有上胸段淋巴结区域的平均EUD值为32.3~61.5 Gy,较VMAT计划(32.5~61.1 Gy)提高4.7%,平均V40提高2.4%。各个上胸段淋巴结区域除左气管支气管淋巴结(106tbL)外的意外照射剂量,与PTV的体积大小充分相关(R=0.716~0.933,P<0.05)。结论5F-IMRT的放射治疗计划在上胸段食管癌淋巴结意外照射中更具剂量学优势,且肿瘤靶区较大的患者淋巴结区域具有更高的辐射剂量。     

BodyTom移动CT的辐射剂量和图像质量评估

目的 通过对新一代全身移动CT（BodyTom CT）与常用固定CT机的比较,对其辐射剂量和图像质量评估。方法 用CATPHAN 500性能测试体模评价图像质量,用常规的100 mm笔形电离室、CT聚甲基丙烯酸甲酯（PMMA）体部体模及头部体模测量辐射剂量（头模直径为160 mm,体部体模直径为320 mm,它们宽度均为140 mm）。结果 BodyTom CT的空间分辨率、密度分辨率与两类固定CT接近,差异无统计学意义（P>0.05）。对比度噪声比（CNR）降低20%左右：头部扫描模式下,明显低于飞利浦64排CT和东芝320排CT（重建函数soft时,t=-4.82、-6.98,P<0.05;重建函数standard时t=-20.60、-20.09,P<0.05）;体部扫描模式下,也明显低于飞利浦64排CT和东芝320排CT（重建函数soft时,t=-5.67、-12.82,P<0.05;重建函数standard时,t=-3.39、-9.18,P<0.05;重建函数sharp时,t=-3.88、-3.21,P<0.05）。BodyTom CT的辐射剂量高于固定CT,相同参数下体部体模比飞利浦64排CT机剂量高22.97%（t=9.48,P<0.05）,比东芝320排CT机高29.60%（t=11.66,P<0.05）;头模比飞利浦64排CT机高29.76%（t=23.44,P<0.05）,比东芝320排CT机高33.22%（t=23.11,P<0.05）。结论 移动CT的图像与常规CT图像质量相当时,辐射剂量增高20%以上。     

Mechanical thrombectomy in patients with deep venous thrombosis

Purpose: To report our experience with mechanical thrombectomy in proximal deep vein thrombosis (DVT). Methods: Eighteen patients with a mean (± SD) age of 37.6 ± 16.1 years who presented with DVT in the iliac and femoral vein (n = 3), inferior vena cava (n = 5), or inferior vena cava and iliac vein (n = 10), were treated with the Amplatz Thrombectomy Device after insertion of a temporary caval filter. Results: Successful recanalization was achieved in 15 of 18 patients (83%). Overall, the percentage of thrombus removed was 66 ± 29%: 73 ± 30% at caval level and 55 ± 36% at iliofemoral level. Complementary interventions (seven patients) were balloon angioplasty (n = 2), angioplasty and stenting (n = 2), thrombo-aspiration alone (n = 1), thrombo-aspiration, balloon angioplasty, and permanent filter (n = 1), and permanent filter alone (n = 1). There was one in-hospital death. Follow-up was obtained at a mean of 29.6 months; three patients had died (two cancers, one myocardial infarction); 10 had no or minimal sequelae; one had post-phlebitic limb. Conclusion: Mechanical thrombectomy is a potential therapeutic option in patients presenting with proximal DVT.     

Effect of combination of essential oils and bacteriocins on the efficacy of gamma radiation against Salmonella Typhimurium and Listeria monocytogenes

Abstract

Purpose: Using essential oils (EO) alone or combined EO with nisin to enhance the lethality of Salmonella Typhimurium and Listeria monocytogenes to γ-irradiation treatment.

Materials and methods: Cell suspension or inoculated carrots (10⁶ colony forming unit (CFU)/ml) of L. monocytogenes or Salmonella Typhimurium were treated with carvacrol and mountain savory EO alone or treated by the combined EO plus nisin and were irradiated at different doses. The radiation dose required to reduce bacterial population by 90% (D₁₀ value) and the relative sensitivity (RS) of treated bacteria to irradiation were calculated.

Results: The RS of L. monocytogenes cell suspension to irradiation was increased by 4.19 and 6.31 times when treated by carvacrol plus nisin and mountain savory plus nisin, respectively, as compared to the control. The RS of Salmonella Typhimurium cell suspension to irradiation was increased by 1.84-fold when treated with carvacrol plus nisin. Coated carrots by nisin plus carvacrol increased the RS of L. monocytogenes to irradiation by 2.74 times while coated carrots by nisin and nisin plus carvacrol increased the RS of Salmonella Typhimurium to irradiation by 2.46 and 2.52, respectively.

Conclusions: The combined EO with nisin and irradiation could increase the RS of L. monocytogenes and Salmonella Typhimurium.     

模拟退火逆向优化算法在宫腔管联合插植针的宫颈癌三维后装腔内放疗中的应用

目的 探讨模拟退火逆向优化算法（IPSA）在以插植针为施源器的宫颈癌三维后装腔内放疗中的应用效果。方法 以2016年10月至2018年7月接受根治性外照射及腔内联合组织间插植的局部晚期宫颈癌患者60例为研究对象,其中宫腔管联合1~4根插植针的患者各15例。在每例患者的同一套CT图像上,分别用正向的图形优化（GRO）方式和IPSA完成两种放疗计划,采用配对t检验分析两种计划方式的剂量学差异。结果 IPSA计划的D₉₀、V₁₀₀均高于GRO计划（t=-4.742、-4.823,P<0.05）,但靶区一致性指数（CI）和靶区适形指数（COIN）略低于GRO计划（t=9.642、8.783,P<0.05）。两组计划的靶区高量（V₁₅₀、V₂₀₀、V₃₀₀）比较,差异无统计学意义（P>0.05）。两组计划的膀胱、直肠D_{2 cm³}相近（P>0.05）。宫腔管联合1根插植针时,IPSA较GRO的平均D₉₀只提高了4 cGy （P>0.05）;但随着插植针管数的增加,IPSA相比于GRO,D₉₀提高的幅度也逐渐增加;当增加到4根插植针时,IPSA较GRO的平均D₉₀增加了14 cGy （t=-3.180,P<0.05）。与GRO相比,IPSA的V₁₀₀提高的幅度同样随着插植针管数的增加而逐渐增加。结论 在以宫腔管联合插植针为施源器的宫颈癌三维后装治疗中,相比于GRO计划,IPSA计划在未增加靶区高量和危及器官剂量的情况下,可以提高靶区的覆盖度（D₉₀、V₁₀₀）,且随着插植针管数的增多,IPSA较GRO在提高靶区覆盖度方面的优势也更为明显。     

The clinical application of bone mineral analysis

Photon absorptiometry provides an accurate measurement of bone mineral content. In acromegaly, the bone mineral content is normal, whereas the bone mineral content is reduced by acidosis. Decreased bone mineral content occurs in alcoholics due to osteomalacia and also in anticonvulsant therapy for the same reason. In hyperparathyroidism, there is decreased bone mineral content. Corticosteroids reduce bone mineral content especially in the central skeleton similar to Cushing's disease. Glutethimide causes osteomalacia with decreased bone mineral content. Long-term heparin therapy causes bone resorption. Immobilization causes decreased bone mineral content. Bedrest and space flight reduce lower limb bone mineral content with recovery on ambulation. Conversely, activity increases bone mineral content even in the elderly and bone mineral content is greater in athletes than non-athletes. Osteoporosis is a normal process occurring from age 45 years in females and 65 in males. Bone loss is related to menopause and lactation in females and may be arrested by estrogens, fluoride (with calcium and vitamin D), and possibly calcium carbonate. Decreased bone mineral content occurs at all stages of renal failure with rapid bone mineral content loss in azotemia and during dialysis and slower loss after transplant. Parathyroidectomy does not affect bone mineral content in renal osteodystrophy.The bone mineral content is normal in compact bone but decreased in trabecular bone in patients with spinal cord injury, as well as in leprosy and diabetes. In hemiplegia, there is decreased bone mineral content on the paralyzed side. In thyrotoxicosis, there is increased formation and resorption of bone.     

乳腺癌根治术后调强放疗的一体化射野设计

目的 比较一种一体化调强射野设计方式与常规射野设计方法在乳腺癌根治术后调强放疗中的剂量学差异。方法 选取41例左侧乳腺癌根治术后患者的CT图像,进行胸壁、部分腋窝、锁骨上、内乳等靶区及危及器官（OAR）勾画。对每一套CT图像分别制作一体化射野设计的调强计划和常规调强计划。评估两种计划靶区和OAR剂量学分布。结果 两种计划靶区剂量分布和OAR受照剂量均满足临床要求,靶区剂量学参数差异无统计学意义（P>0.05）。一体化调强计划相比于常规计划：患侧肺V₅降低9.7%（t=2.407,P<0.05）、V₁₀降低11.2%（t=2.160,P<0.05）、V₂₀降低17.3%（t=2.465,P<0.05）、V₃₀降低13.4%（t=2.119,P<0.05）、D_mean降低13.8%（t=2.258,P<0.05）;心脏V₃₀下降28.4%（t=2.589,P<0.05）、D_mean下降23.2%（t=2.409,P<0.05）;其他OAR剂量学差异不具有统计学意义（P>0.05）。结论 一体化调强射野设计技术显著降低了患侧肺和心脏的受照体积与受照剂量,有望减轻乳腺癌根治术后放疗的不良反应。新型设计方案选取了较多的样本,包含不同分期的左乳癌根治术患者,对乳腺癌根治术后调强放疗临床应用具有普遍性,可以作为一种新的照射方式推广。     

Quantification of hepatic arterial and portal perfusion with dynamic computed tomography: comparison of maximum-slope and dual-input one-compartment model methods

Purpose  The aim of this study was to compare the maximum-slope (MS) and dual-input one-compartment model (DOCM) methods in hepatic perfusion computed tomography (CT). Materials and methods  A total of 37 patients with known or suspected liver disease underwent single-location dynamic CT after arterial or venous bolus injection of contrast material. Perfusion CT images were created by the MS (dividing the peak gradient of the time-attenuation curve by the peak vessel CT number) and DOCM—calculating from the equation dC _L (t)/dt = k _a C _a (t − τ _a ) + k _p C _p (t − τ _p ) − k _v C _L (t)—methods. The perfusion parameters hepatic arterial perfusion (HAP), portal venous perfusion (PVP), and hepatic perfusion index (HPI) were determined. Results  The PVP of the tumor-free hepatic parenchyma determined by the MS method was lower than that obtained by the DOCM method (P < 0.001) with both injections. HAP determined by the MS method was lower than that obtained by the DOCM method with venous injection (P = 0.001), although there was no difference between the methods for HAP with arterial injection (P = 0.154). Most of the perfusion parameters showed linear correlations between the two analytical methods. Conclusion  Except for HAP with arterial injection, the perfusion parameters obtained with the MS method were lower than those obtained with the DOCM method.     

Model-based, semiquantitative and time intensity curve shape analysis of dynamic contrast-enhanced MRI: a comparison in patients undergoing antiangiogenic treatment for recurrent glioma

Purpose:

To compare time intensity curve (TIC)‐shape analysis of dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) data with model‐based analysis and semiquantitative analysis in patients with high‐grade glioma treated with the antiangiogenic drug bevacizumab.

Materials and Methods:

Fifteen patients had a pretreatment and at least one posttreatment DCE‐MRI. We applied a pixel‐by‐pixel TIC shape analysis, where TICs are classified into five different types according to their shape, and calculated the occurrence of each TIC type in the region of interest (ROI). The results were compared to the pharmacokinetic model (PKM) parameters K^trans, K_ep, V_e, and V_i, and with the semiquantitative parameters maximum enhancement (ME) and initial slope of increase (ISI).

Results:

The relative amount of type 2 and 4 TIC shape significantly correlated with the parameter K_ep but not with K^trans or V_e. The PKM parameter V_e and the semiquantitative parameters ME and ISI showed significant changes after treatment. None of the TIC shapes individually showed significant changes.

Conclusion:

The semiquantitative parameters ME and ISI are more sensitive to the effect of the bevacizumab than K^trans and V_e. The pixel‐by‐pixel TIC shape analysis parameters are not sensitive to the effect of bevacizumab, although they can be seen as surrogates for the PKM parameter K_ep. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Diagnostic value of kinetic analysis using dynamic FDG PET in immunocompetent patients with primary CNS lymphoma

Purpose The purpose of this study was to investigate the accumulation of FDG in immunocompetent patients with primary central nervous system (CNS) lymphoma using qualitative and quantitative PET images and to compare baseline with follow-up PET after therapy. Methods Twelve immunocompetent patients with CNS lymphoma were examined. Dynamic emission data were acquired for 60 min immediately following injection of FDG. In seven patients, repeated PET studies were performed after treatment. Applying a three-compartment five-parameter model, K ₁, k ₂, k ₃, k ₄, vascular fraction (V _B ) and cerebral metabolic rate of glucose (CMR_Glc) were obtained. We evaluated the FDG uptake visually using qualitative and parametric images and quantitatively using parametric images. Results A total of 12 lesions were identified in ten patients with newly diagnosed CNS lymphoma. On visual analysis, ten lesions showed an increase on qualitative images, eight showed an increase on K ₁ images, 12 showed an increase on k ₃ images and ten showed an increase on CMR_Glc images. On quantitative analysis, k ₂, k ₃ and CMR_Glc values of the lesion were significantly different from those of the normal grey matter (p<0.02–0.0005). A total of three lesions were identified in two patients with recurrent tumour. All three lesions showed an increase on qualitative, k ₃ and CMR_Glc images. The K ₁, k ₂, k ₃ and CMR_Glc values after treatment were significantly different from those obtained before treatment (p<0.04–0.008). Conclusion Kinetic analysis, especially with respect to k ₃, using dynamic FDG PET might be helpful for diagnosis of CNS lymphoma and for monitoring therapeutic assessment.     

The individual and combined influence of ACE and ACTN3 genotypes on muscle phenotypes before and after strength training

Alternative measures of muscle size, strength, and power to those used in previous studies could help resolve the controversy surrounding associations between polymorphisms of the angiotensin‐I converting enzyme (ACE) and α‐actinin‐3 (ACTN3) genes and skeletal muscle phenotypes, and the responses to resistance training (RT). To this end, we measured quadriceps femoris muscle volume (V_m), physiological cross‐sectional area (PCSA), maximum isometric force (F_t), specific force (F_t per unit PCSA), maximum isoinertial strength (1‐RM), and maximum power (W_max; n = 40) before and after 9‐week knee extension RT in 51 previously untrained young men, who were genotyped for the ACE I/D and ACTN3 R577X polymorphisms. ACTN3 R‐allele carriers had greater V_m, 1‐RM, and W_max than XX homozygotes at baseline (all P < 0.05), but responses to RT were independent of ACTN3 genotype (all P > 0.05). Muscle phenotypes were independent of ACE genotype before (all P > 0.05) and after RT (all P > 0.01). However, people with the “optimal” ACE+ACTN3 genotype combination had greater baseline 1‐RM and W_max compared to those with the “suboptimal” profile (both P < 0.0125). We show for the first time that the ACTN3 R577X polymorphism is associated with human V_m and (independently and in combination with the ACE I/D polymorphism) influences 1‐RM and W_max.     

Effect of oxygen pressure during incubation with a 10B-carrier on 10B uptake capacity of cultured p53 wild-type and mutated tumor cells: dependency on p53 status of tumor cells and types of 10B-carriers

Purpose To evaluate the effect of oxygen pressure during incubation with a ¹⁰B-carrier on ¹⁰B uptake capacity of cultured p53 wild-type and mutated tumor cells.

Materials and methods Cultured human head and neck squamous cell carcinoma cell line transfected with mutant TP53 (SAS/mp53), or with a neo vector as a control (SAS/neo) was incubated with L-para-boronophenylalanine-¹⁰B (BPA) or sodium mercaptoundecahydrododecaborate-¹⁰B (BSH) as a ¹⁰B-carrier at the ¹⁰B concentration of 60 ppm for 24?h under aerobic (20.7% of oxygen) or hypoxic (0.28% of oxygen) conditions. Immediately after incubation, cultured tumor cells received reactor thermal neutron beams, and a cell survival assay was performed. ¹⁰B concentration of cultured SAS/neo or SAS/mp53 cells incubated under aerobic or hypoxic conditions was determined with a thermal neutron guide tube.

Results Hypoxic incubation significantly decreased ¹⁰B concentration of cultured cells with a clearer tendency observed following BPA than BSH treatment in both SAS/neo and SAS/mp53 cells. Following neutron beam irradiation, SAS/mp53 cells showed significantly higher relative biological effectiveness values than SAS/neo cells because of the significantly lower radiosensitivity of SAS/mp53 to γ-rays than SAS/neo cells.

Conclusion Oxygen pressure during incubation with a ¹⁰B-carrier had a critical impact on ¹⁰B uptake of cultured tumor cells.     

Nuclear medical determination of the left ventricular normalized velocity of contraction

The normalized velocity of contraction (v _n) and its maximal value (v _n ^max ) are related to the normalized flow acceleration within the ventricle, to the subendocardial fiber shortening rate, strain rate, and stress. This paper presents the method of the nuclear medical determination of v _n and analyzes a typical volume-velocity-time curve. In 60 patients with different stages of coronary artery disease, global v _n ^max showed good correlation with the minimal ventricular transit time (y=6.18-1.36 x, P<0.001) and global ejection fraction (y=-(2.5+356/(x-104)), P<0.001). The segmental v _n ^max showed a highly significant correlation with the regional ejection fraction (y=-(2.5+371/(x-104)), P<0.001). The mathematical relationships of v _n with the mechanical properties of the ventricular wall are described in the appendix.     

13C-NMR relaxation in glycogen

This study is the first report on the multiexponential T₂ relaxation of the ¹³C-1 carbon of glycogen. In contrast to T₁ relaxation, which does not display observable multiexponential decay behavior, T₂ relaxation is described by a continuous distribution of T₂ times. Changes in molecular weight and sample viscosity, which affect the overall mobility of the glycogen particle have little influence on T₁ and T₂ relaxation times. This is in contradiction with earlier results that T₂ is dominated by the overall motion of the glycogen particles [L.-H. Zang Biochemistry 29, 6815–6820 (1990)]. T₁ depends strongly on the external field B_o and is almost temperature independent in the range 23–37°C whereas T₂ is field independent and varies appreciably with temperature. The experimental T₁ and T₂ relaxation data are shown to be consistent with existing theoretical models for relaxation, suitably modified to include a distribution of correlation times for the internal motions. The presence of fast decaying components (short T₂) in the FID implies broad line components in the frequency spectrum and the corresponding need to appropriately set the integration limits for the quantification of the glycogen peak.     

Pre-operative estimation of esophageal tumor metabolic length in FDG-PET images with surgical pathology confirmation

Objective The aim of this study was to evaluate a 3D tumor segmentation method for fluorodeoxyglucose positron emission tomography (FDG-PET) in the context of noninvasive estimation of tumor metabolic length (L _m), as it correlates with surgical pathology and phantom results. Methods Thirty-four patients (7 women, 27 men) with esophageal cancer were retrospectively evaluated. All patients underwent FDG-PET-computed tomography (CT) imaging following endoscopic ultrasound (EUS). Seventeen patients had esophagectomy after PET/CT, without prior neoadjuvant therapy. Tumor length was assessed by EUS (L _e, n = 31) and histopathology (L _p, n = 17). Images were evaluated quantitatively with a 3D threshold-based region-growing program (Medical Image Processing Analysis and Visualization). L _m, total metabolic volume (V _m), maximum standardized uptake value (SUV_max), and average SUV (SUV_a) over the entire tumor were obtained for several threshold values (mean activity in the liver plus 0-, 1-, 2-, 3-, and 4-SD of the activity in the liver). Results L _m showed a good correlation with L _p for all thresholds (best correlation for L _m(2-SD), r = 0.74, P < 0.001). A positive nonsignificant correlation was observed between L _p and L _e (r = 0.30, P = 0.29). L _m(2-SD) correlated well with L _e (r = 0.71, P < 0.001). Good correlations were also observed between L _m(2-SD) and V _m(2-SD) (r = 0.89, P < 0.001) and SUV_a(2-SD) (r = 0.38, P < 0.05). V _m(2-SD) also had a significant correlation with L _p (r = 0.61, P < 0.05) and L _e (r = 0.57, P < 0.001). Conclusions FDG-PET-derived tumor metabolic length of untreated esophageal carcinomas correlates well with surgical pathology results, and provides preliminary evidence that noninvasive delineation of the superior and inferior extent of viable tumor involvement might be feasible using computer-generated metabolic length measurements.