Brain mechanism of acupuncture for children with anisometropic amblyopia: a resting functional magnetic resonance imaging study based on voxel-mirrored homotopic connectivity

AIM:To explore the brain mechanism of acupuncture for children with anisometropic amblyopia using the voxelmirror homotopic connectivity(VMHC)analysis method of resting functional magnetic resonance imaging(rs-fMRI)technology based on clinical effectiveness.METHODS:Eighty children with anisometropic monocular amblyopia were randomly divided into two groups:control(40 cases,1 case of shedding)and acupuncture(40 cases,1 case of shedding)groups.The control group was treated with glasses,red flash,grating,and visual stimulations,with each procedure conducted for 5min per time.Based on routine treatment,the acupuncture group underwent acupuncture of“regulating qi and unblocking meridians to bright eyes”,Jingming(BL1),Cuanzhu(BL2),Guangming(GB37),Fengchi(GB20)acupoints were taken on both sides,with the needle kept for 30min each time.Both groups were treated once every other day,three times per week,for a total of 4wk.After the treatment,the overall curative effect of the two groups and the latency and amplitude changes of P100 wave of pattern visual-evoked potential were counted.At the same time,nine children with left eye amblyopia were randomly selected from the two groups and were scanned with rsfMRI before and after treatment.The differences in the brain regions between the two groups were compared and analyzed with VMHC.RESULTS:Chi-square test showed a notable difference in the total efficiency rate between the acupuncture(94.87%)and control groups(79.49%).Regarding the P100 wave latency and amplitude,the acupuncture group had significantly shorter latency and higher amplitude of P100 wave than the control group.Moreover,the VMHC values of the bilateral temporal lobe,superior temporal gyrus,and middle temporal gyrus were notably increased in the acupuncture group after treatment.CONCLUSION:Acupuncture combined with conventional treatment can significantly improve the corrected visual acuity and optic nerve conduction in children with anisometropic amblyopia.Compared with the conventional treatment,the regulation of acupuncture on the functional activities of the relevant brain areas in the anterior cerebellum may be an effective acupuncture mechanism for anisometropic amblyopia.

Structural and functional alterations in the brains of patients with anisometropic and strabismic amblyopia:a systematic review of magnetic resonance imaging studies

Amblyopia is the most common cause of vision loss in children and can persist into adulthood in the absence of effective intervention.Previous clinical and neuroimaging studies have suggested that the neural mechanisms underlying strabismic amblyopia and anisometropic amblyopia may be different.Therefore,we performed a systematic review of magnetic resonance imaging studies investigating brain alterations in patients with these two subtypes of amblyopia;this study is registered with PROSPERO(registration ID:CRD42022349191).We searched three online databases(PubMed,EMBASE,and Web of Science) from inception to April 1,2022;39 studies with 633 patients(324patients with anisometropic amblyo pia and 309 patients with strabismic amblyopia) and 580 healthy controls met the inclusion criteria(e.g.,case-control designed,pee r-reviewed articles) and were included in this review.These studies highlighted that both strabismic amblyopia and anisometropic amblyopia patients showed reduced activation and distorted topological cortical activated maps in the striate and extrastriate co rtices during tas k-based functional magnetic resonance imaging with spatial-frequency stimulus and retinotopic representations,respectively;these may have arisen from abnormal visual experiences.Compensations for amblyopia that are reflected in enhanced spontaneous brain function have been reported in the early visual cortices in the resting state,as well as reduced functional connectivity in the dorsal pathway and structural connections in the ventral pathway in both anisometro pic amblyopia and strabismic amblyopia patients.The shared dysfunction of anisometro pic amblyopia and strabismic amblyopia patients,relative to controls,is also chara cterized by reduced spontaneous brain activity in the oculomotor co rtex,mainly involving the frontal and parietal eye fields and the cerebellu m;this may underlie the neural mechanisms of fixation instability and anomalous saccades in amblyopia.With regards to specific alterations of the two forms of amblyo pia,anisometropic amblyo pia patients suffer more microstructural impairments in the precortical pathway than strabismic amblyopia patients,as reflected by diffusion tensor imaging,and more significant dysfunction and structural loss in the ventral pathway.Strabismic amblyopia patients experience more attenuation of activation in the extrastriate co rtex than in the striate cortex when compared to anisometropic amblyopia patients.Finally,brain structural magnetic resonance imaging alterations tend to be lateralized in the adult anisometropic amblyopia patients,and the patterns of brain alterations are more limited in amblyopic adults than in childre n.In conclusion,magnetic resonance imaging studies provide important insights into the brain alterations underlying the pathophysiology of amblyopia and demonstrate common and specific alte rations in anisometropic amblyo pia and strabismic amblyopia patients;these alterations may improve our understanding of the neural mechanisms underlying amblyopia.

Artificial intelligence-aided diagnosis and treatment in the field of optometry

With the rapid development of computer technology,the application of artificial intelligence(AI)to ophthalmology has gained prominence in modern medicine.As modern optometry is closely related to ophthalmology,AI research on optometry has also increased.This review summarizes current AI research and technologies used for diagnosis in optometry,related to myopia,strabismus,amblyopia,optical glasses,contact lenses,and other aspects.The aim is to identify mature AI models that are suitable for research on optometry and potential algorithms that may be used in future clinical practice.

Defects and asymmetries in the visual pathway of non-human primates with natural strabismus and amblyopia

Strabismus and amblyopia are common ophthalmologic developmental diseases caused by abnormal visual experiences. However, the underlying pathogenesis and visual defects are still not fully understood. Most studies have used experimental interference to establish diseaseassociated animal models, while ignoring the natural pathophysiological mechanisms. This study was designed to investigate whether natural strabismus and amblyopia are associated with abnormal neurological defects. We screened one natural strabismic monkey(Macaca fascicularis) and one natural amblyopic monkey from hundreds of monkeys, and retrospectively analyzed one human strabismus case. Neuroimaging, behavioral,neurophysiological, neurostructural, and genovariation features were systematically evaluated using magnetic resonance imaging(MRI), behavioral tasks, flash visual evoked potentials(FVEP),electroretinogram(ERG), optical coherence tomography(OCT), and whole-genome sequencing(WGS), respectively. Results showed that the strabismic patient and natural strabismic and amblyopic monkeys exhibited similar abnormal asymmetries in brain structure, i.e., ipsilateral impaired right hemisphere. Visual behavior, visual function, retinal structure, and fundus of the monkeys were impaired. Aberrant asymmetry in binocular visual function and structure between the strabismic and amblyopic monkeys was closely related, with greater impairment of the left visual pathway.Several similar known mutant genes for strabismus and amblyopia were also identified. In conclusion,natural strabismus and amblyopia are accompanied by abnormal asymmetries of the visual system,especially visual neurophysiological and neurostructural defects. Our results suggest that future therapeutic and mechanistic studies should consider defects and asymmetries throughout the entire visual system.

网络教学联合眼科临床指南在斜视弱视学教学中的应用

网络教学打破了教育资源的时空限制。以眼视光技术专业斜视弱视学课程的网络教学联合眼科临床指南的教学模式为例,构建教学新模式,实现教学方式的转变。

应用R软件meta4diag程序包实现诊断准确性试验的Meta分析

meta4diag程序包是R软件中专用于实现诊断准确性试验(diagnostic test accuracy,DTA)Meta分析的程序包,该程序包基于贝叶斯理论采用INLA(integrated nested Laplace approximation)法来对单个研究效应值进行合并,同时,该程序包还提供了SROC(Summary Receiving Operation Characteristic)曲线图的分析与绘制,然而其缺陷在于无法给出异质性检验及风险偏倚评估。本文以实例形式就meta4diag程序包实现诊断准确性试验DTA Meta分析的数据准备与分析、结果汇总及图形绘制等功能作相关简述。

国医大师唐由之运用参明汤治疗弱视的组方思路探讨

弱视为常见的儿童眼病,归属于中医学“视瞻昏渺”“目暗不明”等范畴。国医大师唐由之认为,弱视的病因病机为先天禀赋不足、后天摄养失宜,在治疗上以补养先、后天为主,在其经验方参明汤的基础上进行临证加减。参明汤的组方特色为:虚为病由,肾为虚本,重视补肾,填精益髓;幼科之要,调理脾胃,培土化源,健脾益胃;斡旋脾肾,脾肾互赞,相互资生,相得益彰;治法多变,不拘于补,补而不滞,静中有动;用药权衡,变通为要,四诊合参,中西并举。本文对唐由之诊治儿童弱视的学术思想进行深入分析,探讨其诊治依据和组方思路。

鼻腔递送血管活性肠肽对弱视大鼠视皮层脑源性神经营养因子的影响

目的探索血管活性肠肽(VIP)对形觉剥夺性弱视大鼠视皮层脑源性神经营养因子(BDNF)的影响,探讨弱视治疗的神经保护作用机制。方法选取3周龄健康SD大鼠36只,随机分为对照组、模型组、治疗组,各12只。采用前爪触地实验测定大鼠视敏度,图形视觉诱发电位(PVEP)测定客观视觉功能;采用Western blotting检测各组大鼠视皮层BDNF表达水平,采用免疫荧光染色观察胶质纤维酸性蛋白(GFAP)和VIP在视皮层中的表达水平和GFAP表达部位,苏木精-伊红(HE)染色观察大鼠视皮层病理学改变。结果与模型组比较,治疗组视敏度和客观视觉功能均提高(P<0.05),BDNF蛋白表达水平增加(P<0.05),但仍低于对照组(P<0.05)。免疫荧光检测结果显示:GFAP阳性细胞在正常组与弱视组中主要表达在视皮层Ⅰ层和Ⅵ层,且弱视组大鼠视皮层GFAP荧光强度明显低于对照组(P<0.05),治疗组视皮层VIP和GFAP的荧光强度均明显增加(P<0.05)。结论VIP对弱视大鼠有治疗作用,可能与活化视皮层星形胶质细胞释放BDNF有关。这为弱视的治疗提供了新思路。

弱视治疗——国内外最新指南和专家共识对比

弱视是指视觉发育期由于形觉剥夺和(或)双眼异常的相互作用导致最佳矫正视力低于相应年龄视力或低于对侧眼视力2行及以上。2022年美国眼科学会更新了弱视临床指南(PPP)中的治疗建议,2021年我国中华医学会眼科学分会斜视与小儿眼科学组也发表了《中国儿童弱视防治专家共识(2021年)》。本文将2022年版PPP与2017年版《Amblyopia Preferred Practice Pattern》以及我国2021年专家共识进行对比分析,重点解读新版PPP在治疗方面的更新内容,以及国内外在治疗方式及随访评估上的差异,以期与国内眼科同道分享弱视的最新治疗进展。

优势眼的特征及转换在眼部疾病治疗中的意义

优势眼是指两眼在视物时起主导作用的眼,在双眼视功能和融合功能中发挥重要作用,其形成机制较为复杂。根据优势眼检查方法的原理不同,可分为注视性、运动性和知觉性优势眼3种类型,每一类优势眼的检查方法有所不同。由于双眼疾病进展不平衡引起的视力或视功能的改变,可能会导致优势眼的转换,进而影响双眼视觉平衡及治疗效果。因此,忽视优势眼的定位或错误判断会改变双眼间长期建立的视觉平衡,对视觉质量和生活质量带来不同程度影响。这种现象主要体现在屈光不正配镜矫正、屈光手术、斜视矫正手术、弱视训练方法和白内障人工晶状体度数的测定等过程中。基于优势眼的眼别进行医疗方案的制定,对患者良好双眼视觉的重建和生活质量的改善尤其重要。然而,优势眼在双眼视功能中的作用目前尚未完全明确,临床医生也缺乏对其重要性的足够认知。本文就优势眼的形成机制、检查方法和优势眼转换的临床意义等相关的最新研究进展进行综述。

视觉发育关键期单眼形觉剥夺弱视大鼠视皮层的差异表达基因及其功能分析

目的筛选视觉发育关键期单眼形觉剥夺弱视大鼠视皮层的差异表达基因,并分析其功能。方法选取出生13 d尚未睁眼SD大鼠24只,按随机数字表法均分为空白对照组、模型组。模型组进行右侧眼睑缝合建立单眼形觉剥夺弱视模型。出生60 d,麻醉处死大鼠,取其脑组织。用基因芯片实验筛选差异表达基因,用基因本体论(GO)和京都基因与基因组百科全书(KEGG)对差异表达基因进行富集分析。结果与空白对照组比较,模型组左侧视皮层差异表达基因共163个,右侧视皮层差异表达基因数共38个,共有差异表达基因16个。GO富集分析显示,左侧视皮层差异表达基因富集程度大于2的涉及22个条目,右侧视皮层差异表达基因富集程度大于2的涉及19个条目。KEGG富集分析显示,模型组差异表达基因主要功能集中于胚胎背腹轴线形成、光信号传导通路、丝裂原活化蛋白激酶(MAPK)信号通路、核苷酸结合寡聚化结构域(NOD)样受体信号通路、神经营养蛋白信号通路、神经递质配体-受体相互作用信号通路等。其中MAPK1、鸟氨酸结合蛋白Gα2(GNAT2)基因异常表达可能与视功能异常改变有关,MAPK1基因主要功能集中在胚胎背腹轴线形成、MAPK信号通路、NOD样受体信号通路、神经营养蛋白信号通路、神经配体-受体相互作用信号通路,GNAT2基因主要功能为光信号传导通路。结论视觉发育关键期进行单眼形觉剥夺可造成大鼠大脑视皮层基因异常表达,并引起其调控的信号通路相关基因表达改变,造成视觉信号传导功能异常;MAPK1、GNAT2基因异常表达可能是弱视发病的生物学机制之一。

虚拟现实技术在眼部疾病中的应用与展望

目的虚拟现实(VR)技术与眼视觉密切关联,随着软硬件设备的发展与进步,VR广泛应用于眼科领域。本文详述了VR技术在眼科临床研究和科普培训领域中的研究与运用过程;总结目前应用VR技术的研究成果及其优势,包括在弱视、斜视、近视、青光眼等方面的新疗效,以及在白内障等手术培训及科普教育中的应用研究;探讨了应用VR的危险和困境,并预测未来的应用趋势;根据VR在目前研究应用中的不足,展望其在弱视、近视等疾病中的应用前景,为以后的临床研究提供参考。

屈光参差性弱视一阶光栅锐度和二阶纹理敏感度的感知能力

目的:研究单眼屈光参差性弱视患者对一阶光栅锐度和二阶纹理敏感度的感知能力。方法:收集2018-01/2022-12于我院确诊的单眼屈光参差性弱视儿童715例715眼作为弱视组,另选取矫正视力正常儿童745例745眼作为正常对照组。分别检测最佳矫正视力(BCVA)、一阶光栅锐度和(或)二阶纹理敏感度,并分析不同程度弱视患者对一阶光栅锐度和二阶纹理敏感度的感知能力。结果:弱视组与正常对照组一阶光栅锐度(11.58±6.10 vs 20.27±3.47,P<0.001)、二阶纹理敏感度(0.33±0.16 vs 0.12±0.04,P<0.001)均有明显差异,且轻中度弱视患者与重度弱视患者一阶光栅锐度(12.10±6.23 vs 8.13±3.70,P<0.001)和二阶纹理敏感度(0.32±0.16 vs 0.37±0.17,P<0.05)均有明显差异。结论:单眼屈光参差性弱视患者大脑皮层一阶视觉通路和二阶视觉通路均存在不同程度的损伤,重度弱视患者较轻中度弱视患者损伤更为严重。

小鼠上丘Rap1B表达的发育性变化及关键期单眼形觉剥夺对其的影响

目的探讨小鼠上丘Rap1B表达的发育性变化以及视觉发育关键期单眼形觉剥夺(MD)对其表达的影响。方法SPF级健康雄性C57BL/6J小鼠45只为实验对象。实验一:小鼠上丘Rap1B表达的发育性变化。该实验小鼠分为3组,即关键期前组[生后18 d(P18)小鼠]、关键期组(P32小鼠)和成年组(P60小鼠),采用qPCR和Western blot检测各组小鼠左右两侧上丘中Rap1B基因及蛋白的表达量。实验二:MD对上丘Rap1B基因及蛋白表达的影响。该实验小鼠分为2组:右眼MD组(小鼠P28时右眼建立MD模型,至P32时行检测)与NC组(正常对照组,P32小鼠),采用qPCR和Western blot检测各组小鼠左右两侧上丘中Rap1B基因及蛋白的表达。结果关键期前组小鼠左右两侧上丘中Rap1B基因和蛋白表达量均较低;与关键期前组相比,关键期组小鼠Rap1B基因及蛋白表达量均显著增高(均为P<0.05);与关键期组相比,成年组小鼠Rap1B基因和蛋白表达量均显著降低(均为P<0.05)。与NC组相比,右眼MD组小鼠左侧上丘Rap1B基因和蛋白表达量均显著增高(均为P<0.05),而右侧上丘Rap1B基因和蛋白表达量均显著降低(均为P<0.05)。结论小鼠上丘中Rap1B基因表达的发育性变化趋势与视觉发育关键期相一致,Rap1B可能参与了关键期MD对上丘发育的调控。

Prevalence of visual impairment and estimation of refractive errors among school children in Kakamega,Kenya

AIM:To investigate the prevalence of visual impairment(VI)and provide an estimation of uncorrected refractive errors in school-aged children,conducted by optometry students as a community service.METHODS:The study was cross-sectional.Totally 3343 participants were included in the study.The initial examination involved assessing the uncorrected distance visual acuity(UDVA)and visual acuity(VA)while using a+2.00 D lens.The inclusion criteria for a subsequent comprehensive cycloplegic eye examination,performed by an optometrist,were as follows:a UDVA<0.6 decimal(0.20 logMAR)and/or a VA with+2.00 D≥0.8 decimal(0.96 logMAR).RESULTS:The sample had a mean age of 10.92±2.13y(range 4 to 17y),and 51.3%of the children were female(n=1715).The majority of the children(89.7%)fell within the age range of 8 to 14y.Among the ethnic groups,the highest representation was from the Luhya group(60.6%)followed by Luo(20.4%).Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17(range 1.70 to 0.22).Out of the total,246 participants(7.4%)had a full eye examination.The estimated prevalence of myopia(defined as spherical equivalent≤-0.5 D)was found to be 1.45%of the total sample.While around 0.18%of the total sample had hyperopia value exceeding+1.75 D.Refractive astigmatism(cil<-0.75 D)was found in 0.21%(7/3343)of the children.The VI prevalence was 1.26%of the total sample.Among our cases of VI,76.2%could be attributed to uncorrected refractive error.Amblyopia was detected in 0.66%(22/3343)of the screened children.There was no statistically significant correlation observed between age or gender and refractive values.CONCLUSION:The primary cause of VI is determined to be uncorrected refractive errors,with myopia being the most prevalent refractive error observed.These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.

A Rare Cause of Leukocoria in Children: Persistent Hyperplastic Primary Vitreous

Introduction: Leukocoria, a whitish pupillary reflection, is a common warning sign of various pediatric ocular pathologies, including Persistent hyperplastic primary vitreous (PHVP). This case report describes the observation of a 3-year-old child with melanoderma, presenting with a white spot in the left eye since birth. Observation: Uncorrected distance visual acuity was 2/10 in the right eye and hand movements were perceived at 2 meters in the left eye. Examination of the anterior segment in the left eye revealed leukocoria and microphthalmia. The fundus examination was normal in the right eye but revealed a white mass extending from the center of the optic disc towards the temporal region in the left eye. Ocular imaging, including ocular ultrasound and optical coherence tomography, confirmed the diagnosis of PHVP, illustrated by a residual white mass at the center of the optic disc in the left eye. Conclusion: PHVP should be considered in the presence of leukocoria in a child, with urgent exclusion of retinoblastoma. This observation underscores the importance of early diagnosis for appropriate management. .

清代医家梁廉夫辨治小儿痘证经验探析

清代医家梁廉夫在辨治小儿痘证方面有其独到之处。梁氏认为小儿痘证乃体内胎毒受时邪侵入触动而发;辨治时强调需辨痘与伤寒之别,辨气病血病,辨表里寒热。在治疗痘证方面,提出了三宜三忌:宜细察虚实,忌妄投医药;宜益气补血,忌克伐气血;宜健脾益肾,忌清热败毒。本文通过研究其著作《不知医必要》,浅析梁氏辨治小儿痘证的学术经验,以期为现代临床诊疗提供参考。

学龄期儿童远视性弱视脉络膜及视网膜厚度的研究

目的研究不同严重程度弱视儿童的脉络膜厚度及视网膜厚度分布情况及变化规律。方法回顾性病例对照研究。选取2021年12月至2022年12月我院就诊的学龄期远视性弱视儿童共48例(96只眼),根据弱视严重程度分为轻度(34只眼)、中度(34只眼)、重度(28只眼)三个亚组;选取同期视力正常儿童17例(34只眼)为正视组。利用相干光层析成像增强技术(EDI‐OCT)行黄斑中心凹下脉络膜厚度(SFCT)以及距中心凹1.0 mm、3.0 mm鼻侧(N1、N3)和颞侧(T1、T3)脉络膜厚度(CT)及黄斑中心凹视网膜厚度(FRT)检测,记录年龄、性别、视力、眼轴长度(AL)、等效球镜(SE),分析脉络膜厚度与视网膜厚度、眼轴、等效球镜、年龄的相关性以及视网膜厚度与眼轴、年龄的相关性。结果各组五个位置CT随着弱视程度加重而增厚,各组间差异均有统计学意义(均P<0.05)。中度远视性弱视组与正视组比较在各位置中CT均增厚、与轻度弱视组相比仅SFCT及N3处CT增厚;重度远视性弱视组CT与其余三组相比在各位置中均明显更厚,差异均有统计学意义(均P<0.05)。远视性弱视组中SFCT较其余四个部位更厚;T1、T3分别厚于N1、N3;T1、N1分别厚于T3、N3,差异均有统计学意义(均P<0.05)。四组中FRT有随着弱视程度的加重而变厚的趋势,但差异无统计学意义(P>0.05)。远视性弱视组中SFCT与AL负相关、与FRT、SE均呈正相关(均P<0.05);FRT与AL负相关(P<0.05);SFCT、FRT与年龄均无相关性(均P>0.05)。结论远视性弱视儿童中弱视眼可影响黄斑区的脉络膜组织结构。

中西医治疗弱视的研究进展

弱视是一种与视觉发育相关的眼病,通常在视觉发育的敏感期及时干预可获较好的疗效,但治疗不当或不及时,将对患者的视力和生活质量造成严重影响。弱视治疗旨在消除弱视的危险因素,并通过遮盖或者压抑优势眼促进弱视眼的使用。中、西医在弱视治疗中各有其独特的方法和理论,近年来,中西医结合治疗弱视的研究备受关注。本文对中、西医治疗弱视的方法和疗效的研究进展进行综述,西医包括脑神经调节、神经可塑性和认知训练等;中医包括中药治疗、耳穴贴压和针灸等。结合中、西医优势制定个性化治疗方案,使二者相辅相成,能更好地促进弱视患者的视觉恢复和功能改善。

超声造影联合中国甲状腺影像报告和数据系统在甲状腺结节诊断和活检效能中的研究

目的探讨中国甲状腺影像报告和数据系统(C-TIRADS)联合超声造影在诊断甲状腺结节的价值。方法选取2022年1月至6月在广西医科大学第一附属医院超声科接受超声检查的413例甲状腺结节患者(413个结节)作为研究对象,以病理学检查结果为“金标准”,所有患者均进行C-TIRADS分类及其联合超声造影检查。比较C-TIRADS分类、C-TIRADS分类联合超声造影检查的灵敏度、特异度及准确度;并分别根据C-TIRADS指南和C-TIRADS指南联合超声造影进行推荐甲状腺活检,分别计算并比较两种方法的恶性肿瘤的活检产量、恶性肿瘤的活检率以及不必要的活检率。结果C-TIRADS检查结果诊断良性结节363例,恶性结节50例;C-TIRADS联合超声造影检查结果诊断良性结节267例,恶性结节146例。C-TIRADS联合超声造影检查的诊断甲状腺癌的灵敏度、特异度、准确度均高于应用C-TIRADS检查,差异有统计学意义(P<0.05)。所有结节、1.0~1.5cm结节中,C-TIRADS联合超声造影的恶性肿瘤活检率低于C-TIRADS单独分类,>1.5cm结节中,C-TIRADS联合超声造影的恶性肿瘤活检率、不必要活检率均低于C-TIRADS单独分类,差异有统计学意义(P<0.05)。结论C-TIRADS与超声造影相联合可提高甲状腺结节的超声诊断效能,并且将超声造影联合C-TIRADS去推荐甲状腺活检也能提高推荐甲状腺结节活检的可靠性,在增加恶性结节的活检产率的同时还能减少甲状腺良性结节的不必要活检率。