低管电压联合迭代模型重建技术在肝脏CT增强扫描中的可行性研究

目的 探讨低管电压联合迭代模型重建(IMR)技术在肝脏CT增强扫描中的可行性。方法 60例患者按随机数字表法分为A组和B组,每组30例。扫描方案A组动脉期100 kV,门静脉期120 kV,B组动脉期120 kV,门静脉期100 kV。各组管电流均固定为250 mAs。A组动脉期和B组门静脉期采用IMR,A组门静脉期和B组动脉期采用滤波反投影(FBP)重建,得到4组图像,包括A1组(动脉期,100 kV,IMR),B1组(动脉期,120 kV,FBP),A2组(门静脉期,120 kV,FBP)以及B2组(门静脉期,100 kV,IMR)。分别比较A1组和B1组,A2组和B2组的图像质量客观评价指标 [图像噪声、图像信噪比(SNR)、对比噪声比(CNR)] 和主观评价指标(低对比分辨力、病灶边缘锐利度、图像失真及诊断信心度),并计算有效剂量。结果 有效剂量A1组较B1组、B2组较A2组明显下降(t=11.05、11.64, P<0.01)。低对比分辨力、病灶边缘锐利度A1优于B1组、 B2优于A2组(Z=6.391、3.200、6.559、3.409, P<0.01),图像失真和诊断信心差异无统计学意义(P>0.05)。图像噪声A1组低于B1组,B2组低于A2组(t=12.889、15.163, P<0.01),SNR和CNR A1组高于B1组,B2组高于A2组(t=15.458、1.325、15.308、3.136, P<0.01)。结论 与常规管电压FBP重建相比,低管电压联合IMR重建可显著降低肝脏增强CT的辐射剂量,并提高其图像质量。     

Physiologic Characteristics and Clinical Outcomes of Patients With Discordance Between FFR and iFR

ObjectivesThis study evaluated the physiologic characteristics of discordant lesions between instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) and the prognosis at 5 years.BackgroundFFR or iFR have been standard methods for assessing the functional significance of coronary artery stenosis. However, limited data exist about the physiologic characteristics of discordant lesions and the prognostic implications resulting from these lesions.MethodsA total of 840 vessels from 596 patients were classified according to iFR and FFR; high iFR–high FFR (n = 580), low iFR–high FFR (n = 40), high iFR–low FFR (n = 69), and low iFR–low FFR (n = 128) groups, which were compared with a control group (n = 23). The differences in coronary circulatory indices including the coronary flow reserve (CFR), index of microcirculatory resistance (IMR), and resistance reserve ratio (RRR) (resting distal arterial pressure × mean transit time / hyperemic distal arterial pressure × hyperemic mean transit time), which reflect the vasodilatory capacity of coronary microcirculation, were compared. Patient-oriented composite outcomes (POCO) at 5 years including all-cause death, any myocardial infarction, and any revascularization were compared among patients with deferred lesions.ResultsIn the low iFR–high FFR group, CFR, RRR, and IMR measurements were similar to the low iFR–low FFR group: CFR 2.71 versus 2.43 (p = 0.144), RRR 3.36 versus 3.68 (p = 0.241), and IMR 18.51 versus 17.38 (p = 0.476). In the high iFR–low FFR group, the CFR, RRR, and IMR measurements were similar to the control group: CFR 2.95 versus 3.29 (p = 0.160), RRR 4.28 versus 4.00 (p = 0.414), and IMR 17.44 versus 17.06 (p = 0.818). Among the 4 groups, classified by iFR and FFR, CFR and RRR were all significantly different, except for IMR. However, there were no significant differences in the rates of POCO, regardless of discordance between the iFR and FFR. Only the low iFR–low FFR group had a higher POCO rate compared with the high iFR–high FFR group (adjusted hazard ratio: 2.46; 95% confidence interval: 1.17 to 5.16; p = 0.018).ConclusionsDifferences in coronary circulatory function were found, especially in the vasodilatory capacity between the low iFR–high FFR and high iFR–low FFR groups. FFR–iFR discordance was not related to an increased risk of POCO among patients with deferred lesions at 5 years. (Clinical, Physiological and Prognostic Implication of Microvascular Status; NCT02186093; Physiologic Assessment of Microvascular Function in Heart Transplant Patients; NCT02798731)     

A 4-methyl-substituted <Emphasis Type="Italic">meta</Emphasis>-iodobenzylguanidine analogue with prolonged retention in human neuroblastoma cells

Purpose As a part of our efforts to develop a meta-iodobenzylguanidine (MIBG) analogue with improved characteristics for the diagnosis and treatment of neuroendocrine tumours, 3-[¹³¹I]iodo-4-methyl-benzylguanidine ([¹³¹I]MeIBG) has been developed. The purpose of this study was to evaluate [¹³¹I]MeIBG in vitro using the uptake-1 positive SK-N-SH neuroblastoma cell line and in vivo in normal mice and mice bearing human neuroblastoma xenografts.Methods The ability of SK-N-SH human neuroblastoma cells to retain [¹³¹I]MeIBG in vitro over a period of 4 days, in comparison to [¹²⁵I]MIBG, was determined by a paired-label assay. Paired-label biodistributions of [¹³¹I]MeIBG and [¹²⁵I]MIBG were performed in normal mice as well as in athymic mice bearing SK-N-SH and IMR-32 human neuroblastoma xenografts.Results Retention of [¹³¹I]MeIBG by SK-N-SH cells in vitro was increased by factors of 1.2, 1.5, 2.0, 2.5 and 3.1 compared with [¹²⁵I]MIBG at 8, 24, 48, 72 and 96 h, respectively. In normal mice, the uptake of [¹³¹I]MeIBG in the heart was similar to that of [¹²⁵I]MIBG at 1 and 4 h; in contrast, myocardial uptake of [¹³¹I]MeIBG was 1.6-fold higher than that of [¹²⁵I]MIBG (p<0.05) at 24 h. When mice were pre-treated with the uptake-1 inhibitor desipramine (DMI), the heart uptake of both tracers was reduced to about half that in untreated controls at 1 h post injection (p<0.05). The hepatic uptake of [¹³¹I]MeIBG was two- to threefold lower than that of [¹²⁵I]MIBG. On the other hand, blood levels of [¹³¹I]MeIBG were substantially higher (up to sixfold), especially at early time points. Uptake of [¹³¹I]MeIBG in heart and tumour at 1 h in the murine SK-N-SH model was specific and comparable to that of [¹²⁵I]MIBG. However, [¹³¹I]MeIBG uptake was 1.6- to 1.7-fold lower than that of [¹²⁵I]MIBG over 4–48 h. While the uptake of both tracers in IMR32 xenografts was similar, it was not uptake-1 mediated.Conclusion Introduction of a methyl group at the 4-position of MIBG seems to be advantageous in terms of higher tumour retention in vitro and lower hepatic uptake in vivo. However, the slower blood clearance of MeIBG may be problematic for some applications.     

Application of polymer-mesh device to remodel left ventricular–mitral valve apparatus in ischemic mitral regurgitation

Objectives

Ischemic mitral regurgitation (IMR) results from ischemic left ventricular (LV) distortion and remodeling, which displaces the papillary muscles and tethers the mitral valve leaflets apically. The aim of this experimental study was to examine efficacy of an adjustable novel polymer filled mesh (poly-mesh) device to reverse LV remodeling and reduce IMR.

Intraocular Injection of Muscimol Induces Illusory Motion Reversal in Goldfish

Induced activation of the gamma-aminobutyric acid_A (GABA_A) receptor in the retina of goldfish caused the fish to rotate in the opposite direction to that of the spinning pattern during an optomotor response (OMR) measurement. Muscimol, a GABA_A receptor agonist, modified OMR in a concentration-dependent manner. The GABA_B receptor agonist baclofen and GABA_C receptor agonist CACA did not affect OMR. The observed modifications in OMR included decreased anterograde rotation (0.01~0.03 µM), coexistence of retrograde rotation and decreased anterograde rotation (0.1~30 µM) and only retrograde rotation (100 µM~1 mM). In contrast, the GABA_A receptor antagonist bicuculline blocked muscimolinduced retrograde rotation. Based on these results, we inferred that the coding inducing retrograde movement of the goldfish retina is essentially associated with the GABA_A receptor-related visual pathway. Furthermore, from our novel approach using observations of goldfish behavior the induced discrete snapshot duration was approximately 573 ms when the fish were under the influence of muscimol.