彩色多普勒超声在血管性阴茎勃起功能障碍诊断中的应用

目的评估阴茎海绵体注射后彩色多普勒超声对男性血管性阴茎勃起功能障碍（ED）患者诊断作用。方法47例ED患者经阴茎海绵体注射PGE1 30μg诱导勃起后行彩色超声多普勒检查左、右海绵体动脉血流指标,包括收缩期最大流速（PSV）,动脉舒张末期血流速度（EDV）,阻力指数（RI）。结果非血管性ED组41例（87.2%）,其中左、右海绵体动脉PSV分别〉25 cm/s者33例,左右海绵体动脉PSV相加〉50 cm/s者8例。动脉性ED组2例（4.25%）,左右海绵体动脉PSV均〈25 cm/s,背深静脉未见血流。静脉性ED组4例（8.51%）。结论阴茎海绵体注射血管活性药物后多普勒彩色超声对男性血管性ED检查是一种微创而准确的方法。     

彩色多普勒超声检查在血管性勃起功能障碍诊断中的应用

目的 :探讨多普勒超声检查在诊断血管性勃起功能障碍 (ED)的临床价值。　方法 :应用多普勒超声检查阴茎药物诱导勃起前后的血液动力学改变 ,将非血管性ED病人与明确诊断血管性ED病人的多普勒超声变化进行对比 ,寻找血管性ED的特征。　结果 :动脉性ED病人深动脉的最大血流速度 (PSV)明显小于正常组 (P <0 .0 1) ;静脉性ED病人在阴茎完全勃起后背深静脉血流 (VV)仍大于对照组 (P <0 .0 5 )。　结论 :配合药物诱导阴茎勃起 ,多普勒超声检查是临床上筛选血管性ED的有效手段     

糖尿病性勃起功能障碍的超声研究

目的 应用彩色多普勒超声血流显像(CDFI)技术探讨动脉在糖尿病性勃起功能障碍(ED)中的作用.方法 23例糖尿病性ED患者和30例非糖尿病ED患者经阴茎海绵体注射前列地尔注射液(主要成分为PGE1)10 μg诱导勃起后,行CDFI检查双侧海绵体动脉血流动力学指标,包括收缩期最大流速(PSV)、舒张末期流速(EDV)、阻力指数(RI)及内径(R).结果 PSV和R这两项指标在糖尿病性ED和非糖尿病ED患者中存在差异具有统计学意义,EDV和RI在两组患者中的差异没有统计学意义.糖尿病性ED患者中的动脉性ED明显多于非糖尿病性ED.结论 动脉供血不足在糖尿病性勃起功能障碍发病机制中起着重要作用.阴茎海绵体注射血管活性药物后CDFI对血管性ED检查是一种微创而准确的方法.     

Cavernous artery intima-media thickness predicts the response to sildenafil in erectile dysfunction patients as a morphological parameter

While the intima-media thickness (IMT) of the cavernous artery was used for diagnosis for vascular erectile dysfunction (ED) with more accuracy than the peak systolic velocity, the role of the IMT in predicting treatment responses remained unexamined. A total of 136 patients with ED were enrolled. The baseline clinical and laboratory characteristics were collected. Penile Doppler ultrasonography (PDU) was performed on all patients by a blinded sonographer. Sildenafil was administrated to all patients with an adjusted dose of 50 or 100 mg on demand over a period of 3 months. A follow-up was conducted on all patients using the Erectile Hardness Score (EHS) questionnaire along with the visual and tactile version of the standardised EHS tool. The peak systolic velocity (PSV) and IMT were compared between sildenafil responders and sildenafil nonresponders, while receiver operator characteristic (ROC) curves were used to calculate the cut-off values and compare the test power respectively. There was no statistical difference from the baseline characteristics. The IMT of cavernous artery was more accurate than PSV to predict the sildenafil response (AUC = 0.809, 0.626 respectively). IMT could predict sildenafil responders more accurately than PSV, and the cut-off value of the IMT of the cavernous artery was less than 0.22 mm.     

Assessment of erectile dysfunction in diabetic patients

Erectile dysfunction (ED) aetiology is multifactorial, including endocrine, neurological, vascular, systemic disease, local penile disorders, nutrition, psychogenic factors, and drug-related. This study was performed to compare the relevant comprehensive biochemical parameters as well as the clinical characteristics in diabetic ED and healthy control subjects and to assess the occurrence of penile neuropathy in diabetic patients and thus the relationship between ED and diabetes. A total of 56 patients accepted to undergo assessment for penile vasculature using intracavernosal injection and colour Doppler ultrasonography. Of the 56 diabetic patients, 38 patients were found with normal blood flow and thus they were considered as the diabetic-ED group, whereas, ED diabetic patients with an arteriogenic component were excluded. These patients with an age range between 17 and 58 years, complaining of ED, with duration of diabetic illness ranging from 2 to 15 years. The Control group comprised of 30 healthy subject aged between 19 and 55 years. Peripheral venous levels of testosterone, prolactin, follicle stimulating hormone (FSH), luteinizing hormone (LH), thyroid stimulating hormone (TSH), malondialdehyde and glycosylated haemoglobin (HbA(1)c) were obtained in all subjects. Valsalva manoeuvre and neurophysiological tests were also determined. Testosterone, prolactine, FSH, LH, and TSH hormones of the diabetic patients were not significantly different from those of the control group. Diabetic patients with ED have higher HbA(1)c and oxidative stress levels while the R-R ratio was significantly decreased. Bulbocavernosus reflex latency was significantly prolonged, whereas its amplitude, the conduction velocity and amplitude of dorsal nerve of penis were significantly reduced in the diabetic patients. We concluded that although ED is a multifactorial disorder, yet, the present study revealed that in ED patients without arteriogenic ED a neurogenic component is present. Furthermore, the complex effect of the Valsalva manoeuvre on cardiovascular function is the basis of its usefulness as a measure of autonomic function. Thus, it can be of value in the diagnosis of ED although these hypotheses require follow-up in a large study cohort.     

Doppler evaluation of erectile dysfunction - part 2

Doppler evaluation in erectile dysfunction (ED) has a significant role in determining the cause of ED. The advantages of penile Doppler and pharmacologic duplex ultrasonography include objective, minimally invasive evaluation of penile hemodynamics at a relatively low cost. Arteriogenic ED may be secondary to peripheral vascular disease and diabetes, or may be seen in association with coronary artery disease. Various parameters, such as diameter of the cavernosal artery, peak systolic flow velocity, degree of arterial dilatation and acceleration time, have been suggested for the diagnosis of arteriogenic ED, but peak systolic flow velocity is the most accurate indicator of arterial disease. This second part of the review article describes the various causes of ED and the interpretation and evaluation of color flow Doppler examination in ED.     

Diagnosis and treatment of trauma-associated arteriogenic erectile dysfunction

Objective: To study the diagnosis and treatment of the trauma-associated arteriogenic erectile dysfunction. Methods: Four patients suffers from arteriogenic erectile dysfunction caused by pelvic fractures trauma. Before operation they were examined using pharmacopenile duplex ultrasonography(PPDU) and internal pudendal arteriogram(IPA). Dorsal artery inferior epigastric artery anastomosis were performed in 3 cases. Results: PPDU and IPA suggested that both cavernous arteries and blood flow were not seen in 1 case in 2 cases both PSV of cavernous artery were less than normal level, and in 1 case the PSV of right cavernous artery was normal, the PSV of left cavernous artery was less than normal level. Injury of left common penile artery was comfirmed. After operation one recovers normal erection spontaneously and two have rigid erection induced by intracavernous injection. Conclusions: Trauma-associated arteriogenic erectile dysfunction may result from common penile artery and internal pudendal artery inj     

Non-invasive assessment of arteriogenic impotence: a comparative study

This study was undertaken to determine the relative accuracy of computerised Doppler waveform analysis and colour coded duplex ultrasonography in the diagnosis of arteriogenic impotence. Twenty men with ostensibly normal penile haemodynamics were compared with 50 men whose impotence was considered due to compromised penile haemodynamics. In each patient the penile arterial inflow was assessed by both methods of investigation, which were performed at an interval of 2 weeks. The results demonstrated both techniques to be sensitive in detecting penile artery insufficiency but colour coded duplex ultrasonography was significantly more accurate.     

动脉外伤性勃起功能障碍的诊断和治疗 (附4例报告)

目的　探讨动脉外伤性勃起功能障碍的诊断和治疗。方法　 4例骨盆骨折外伤引起阴茎动脉供血受损所致ED ,阴茎海绵体血管活性药物注射后仅见阴茎轻度胀大 ,球海绵体肌反射试验正常。并行药物性阴茎多谱勒超声检查 (PPDU)和药物性阴部内动脉造影检查 (IPA) ,其中 3例行腹壁下动脉和阴茎背浅动脉吻合术。结果　术前PPDU和IPA显示 ,1例双侧海绵体动脉及血流均未显示 ,左侧阴部内动脉和右侧阴茎动脉主干断裂 ,2例双侧海绵体动脉血管均低于正常 ,双侧阴部内动脉及阴茎动脉主干未显示明显异常。 1例右侧海绵体动脉血流正常 ,左侧海绵体动脉血流明显低于正常 ,左右海绵体动脉近端有交通枝 ,左侧阴茎动脉主干断裂。 3例手术后随访 ,1例完全恢复正常自然勃起 ,2例阴茎海绵体血管活性药物注射后阴茎达正常勃起。结论　骨盆骨折可造成阴茎勃起血供受损 ,阴茎动脉旁路手术为一有可能达到永久治愈单纯动脉外伤性勃起障碍的方法     

多普勒超声技术动态观察血管性勃起功能障碍患者阴茎血流动力学的变化

目的动态观察多普勒超声技术配合阴茎海绵体注射在血管性勃起功能障碍患者诊断中的价值。方法120例疑血管性ED患者在阴茎注射PGE1后5min、10min和20min应用多普勒超声技术测量阴茎血流动力学变化,指标包括:收缩期峰值流速(PSV)、舒张末期峰值流速(EDV)、血流阻力指数(RI)。另100例心因性ED设为对照组。第一次注射后勃起不佳的患者3d后增加PGE1剂量重新检测。结果120例患者可以观察到明显的血流动力学变化,其中有动脉性ED者34例,静脉性ED 55例,混合血管性31例。ICI后不同时间的多普勒测量其血流动力学变化有一定差异。结论多普勒超声技术诊断血管性勃起功能障碍有一定意义。阴茎海绵体注射药物后须动态观察阴茎血流动力学的变化。     

双功能超声和阴部内动脉造影检查在外伤动脉性勃起功能障碍诊断中的应用(附7例报告)

目的探讨双功能超声(DU)、阴部内动脉造影(IPA)在外伤动脉性勃起功能障碍诊断中的应用。方法7例骨盆骨折外伤引起阴茎动脉供血受损致勃起功能障碍患者进行DU和IPA检查。结果DU检查提示7例患者阴茎勃起动脉血液灌注血流动力学受到损害。IPA检查显示7例患者有阴茎动脉血供受损解剖形态学上的变化,包括阴部内动脉断裂、阴茎动脉主干断裂、阴茎动脉主干狭窄和髂总动脉假性动脉瘤病变。结论DU和IPA为阴茎动脉功能和解剖形态学“金标准”试验,DU提供了阴茎勃起动脉血供受损血流动力学改变的客观数据,而IPA显示了阴茎动脉受损解剖形态学上的变化,对损伤病变部位进行定位。对于外伤所致动脉性勃起功能障碍的患者首选DU检查。     

Predictive value of patient history and correlation of nocturnal penile tumescence, colour duplex Doppler ultrasonography and dynamic cavernosometry and cavernosography in the evaluation of erectile dysfunction

AIMS: The results of history and physical examination, nocturnal penile tumescence testing (NPT), colour flow duplex Doppler ultrasonography and dynamic infusion cavernosometry and cavernosography (DICC) were retrospectively correlated in 207 patients with erectile dysfunction. METHODS AND MATERIALS: The predictive value of the patient's own subjective assessment of early morning and nocturnal erections, history of cigarette smoking, the presence of vascular risk factors was correlated to the outcome of investigations. The result of Rigiscan NPT was correlated to the peak systolic velocity (PSV) and the resistance index (RI) determined at colour flow duplex Doppler ultrasonography, and the maintenance flow rate (Qm) determined at DICC. RESULTS: Eighty-five out of two hundred and seven patients (41%) had normal NPT comprising 48 out of 85 patients (56%) who described rigid early morning and nocturnal erections, 15 out of 85 patients (18%) who smoked cigarettes and 9 out of 85 patients (11%) with other positive vascular risk factors. 72 out of 85 patients (85%) had a normal PSV (>30 cm/s), 80 out of 85 patients (94%) had a normal RI (>0.85) and 82 out of 85 patients (96%) had a normal Qm), (<10 ml/min). Vascular investigations in this group identified 71 out of 85 patients (84%) with no penile vascular disease, 11 out of 85 patients (13%) with arteriogenic impotence, 2 out of 85 patients (2%) with mixed vasculogenic impotence and 1 out of 85 patients (1%) with cavernosal venous leakage (CVL). One hundred and twenty-two out of two hundred and seven patients (59%) had an abnormal NPT comprising 18 out of 122 patients (15%) who continued to experience rigid early morning erections, 65 out of 122 patients (53%) who smoked cigarettes, 59 out of 112 patients (48%) with other positive vascular risk factors, 36 out of 112 patients (29%) had an abnormal PSV (<30 cm/s), 49 out of 122 patients (40%) had an abnormal RI (<0.85) and 55 out of 122 patients (45%) had an abnormal Qm (>10 ml/min). Vascular investigations in this group identified five patients with no penile vascular disease, 51 out of 122 patients (41%) with arteriogenic impotence, 31 out of 122 patients (25%) with cavernosal venous leakage (CVL) and 35 out of 122 patients (29%) with mixed vasculogenic impotence. CONCLUSIONS: (1) a history of cigarette smoking and positive vascular risk factors are good predictors of organic impotence whereas the patient's subjective assessment of his own early morning erections is unreliable; (2) normal NPT correlates well with normal PSV, RI and Qm but does not exclude organic impotence; (3) abnormal NPT correlates well with abnormal PSV, RI and Qm.     

IIEF-5在血管性勃起功能障碍诊断中的应用

目的:评价国际勃起功能简化量表(IIEF-5)对血管性勃起功能障碍(ED)病因区分的意义,以指导血管性ED诊断及治疗。方法:将103例ED患者分为4组,非血管性ED组37例(37/103,35.9%)、动脉性ED组18例(18/103,17.5%)、静脉性ED组35例(35/103,34.0%)、混合性ED组13例(13/103,12.6%),其IIEF-5得分与海绵体血管活性药物注射试验结果、多普勒超声检查结果及双核素检测结果进行比较,以非参数检验的多个独立样本检验(Kruskal-WallisTEST)比较各组之间IIEF-5得分差异的显著性。结果:上述4组之间的IIEF-5得分没有统计学差异(P=0.253)。结论:IIEF-5不能作为一种诊断工具用于鉴别血管性ED的病因以及判断血管病变严重程度。     

Diagnostic Performance of Duplex Ultrasonography in the Detection of High Grade Internal Carotid Artery Stenosis

OBJECTIVES: to establish on a national basis whether the diagnostic accuracy of carotid duplex justifies carotid surgery without preoperative angiography. DESIGN: prospective national multicentre study with 10 participating university and county hospitals. MATERIAL AND METHODS: one hundred and thirty-four patients, aged 69+/-9 years, were subjected to routine carotid duplex ultrasonography and angiography. The influence of relevant factors on the relation between ultrasonographic and angiographic variables was evaluated using multiple regression analysis. The capacity of carotid ultrasonography to detect internal carotid artery (ICA) stenosis > or =80% was assessed by receiver operating characteristic analysis. RESULTS: the correlation between peak systolic velocity in ICA (PSV(ICA)) and the angiographic degree of stenosis was strong and significantly influenced only by the applied Doppler angle. Accordingly, the optimal PSV(ICA) cutpoint values for the diagnosis of ICA stenosis > or =80% (ECST method) differed substantially (2.1 and 3.2 m/s) between the two considered angle ranges (0-49 degrees and 50-62 degrees ), the ability to identify high grade ICA stenosis being significantly better at small Doppler angles (0-49 degrees ). CONCLUSION: ultrasonographic duplex technique identifies high grade ICA stenosis with a high degree of accuracy, which can be further improved by the application of small Doppler angles and the use of angle range specific PSV(ICA) cut-off points.     

彩色多普勒超声检查在血管性勃起功能障碍诊断中的应用

目的:评估彩色多普勒超声在诊断血管性勃起功能障碍中的临床价值。方法:应用彩色多普勒超声技术,检测527例疑似血管性勃起功能障碍患者,海绵体注射血管活性药物前、后阴茎海绵体动脉血流动力学。结果:动脉性勃起功能障碍207例(49.88%),静脉性勃起功能障碍144例(34.70%),动静脉性勃起功能障碍64例(15.42%),非血管性勃起功障碍112例(26.99%)。结论:彩色多普勒超声技术是目前诊断血管性勃起功能障碍的一种微创而可靠的检查方法,其能够定量反映阴茎的血流动力学状态,为合理的治疗勃起功能障碍提供有价值的依据。     

Duplex Ultrasound Remains a Reliable Test Even After Carotid Stenting

Transluminal arterial stenting reduces vessel compliance and may alter accurate interpretation of flow velocities. We reviewed duplex ultrasonography (DUS) following carotid stenting to identify criteria indicative of severe recurrent stenosis. This is a single-center retrospective review of 158 carotid stenoses treated with carotid angioplasty and stenting (CAS) from April 2001 to December 2004. DUS was obtained preoperatively, postoperatively, and at 3-month intervals thereafter. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were analyzed. Mean follow-up was 12 months (range 1-40). Mean age was 71 ± 9 years (range 51-91; 74% men, 26% women). Three patients (1.9%) developed restenosis and one (0.6%) developed an asymptomatic occlusion during follow-up. Average preoperative PSV was 373 ± 123 cm/sec (mean ± SD) and EDV was 148 ± 63 cm/sec. Immediate postoperative PSV and EDV decreased by an average of 70% (average 118 ± 45 cm/sec) and 72% (average 32 ± 15 cm/sec), respectively. In patients free from restenosis or occlusion, these reductions (range 65-80%) were maintained throughout follow-up and remained within 1-25% of immediate postoperative values. In patients suffering restenosis or occlusion, follow-up PSV and EDV increased 34% and 28%, respectively, compared to preoperative values. PSV and EDV increased by an average of 287% and 500%, respectively, compared to immediate postoperative values. Using criteria of PSV >170 cm/sec and a 50% increase of PSV over immediate postoperative values, restenosis or occlusion was detected with 100% sensitivity and specificity in our patients. Additionally, EDV >120 cm/sec and a 50% increase in EDV over immediate postoperative values detected restenosis and occlusion with 100% sensitivity and specificity. Presumed restenosis and occlusion detected by DUS were confirmed in all cases with angiography. Restenosis or occlusion after CAS at our institution can reliably be detected by carotid duplex using cut-off values of 170 cm/sec PSV, 120 cm/sec EDV, and >50% increase over immediate postoperative values. While these criteria are applied to patients undergoing CAS at our institution, they serve only as suggested guidelines for patient populations at other centers and must be customized to each Intersocietal Commission for the Accreditation of Vascular Laboratories-accredited vascular laboratory. Presented at the Fifteenth Annual Winter Meeting of the Peripheral Vascular Surgery Society, Steamboat Springs, CO, January 28-30, 2005.     

Multiphasic diagnostic evaluation of arteriogenic, venogenic, and sinusoidogenic impotency. Value of noninvasive tests compared with penile duplex ultrasonography

Fifty patients with a mean age of fifty-five years (range 25 to 75 years) in whom vasculogenic impotency was suspected clinically were evaluated to determine the type of vascular lesion involved: arterial insufficiency, venous leak, or sinusoidal dysfunction. All patients underwent first, noninvasive diagnostic tests including penile brachial index, penile brachial subtraction index, and penile plethysmogram, followed by penile duplex ultrasonography with papaverine and phentolamine injection. Patients with abnormal ultrasonography were divided into two groups: One group with suspected sinusoidal dysfunction and those with either arteriogenic or venogenic insufficiency but not considered candidates for surgery; they were not subjected to further studies. Another group with suspected proximal arteriogenic lesions and those with suspected venous leakage considered candidates for surgical correction were subjected to angiography and cavernosometry-cavernosography, respectively. The findings of the noninvasive tests were compared with those provided by the invasive tests. The results indicated that noninvasive tests can predict whether or not impotency is arteriogenic in approximately 90 percent of cases. The noninvasive tests, however, were less accurate in predicting venogenic and sinusoidogenic impotency, for which penile duplex ultrasonography seems to be the choice.     

Imagerie diagnostique du rein transplanté et des complications de la greffe rénale

Imaging is indicated prior to transplantation in order to evaluate the graft and assess its vascular anatomy in potential living donors. After the transplantation, the main role of imaging is to detect vascular and urological complications, which do not require biopsy and can lead to reconstructive surgery or percutaneous management. In most cases, the first line imaging modality is the colour doppler ultrasonography. Compared to iodinated contrast-enhanced CT, contrast-enhanced MRI provides accurate, noninvasive and nonnephrotoxic evaluation of the arterial pedicle and perfusion disorders.     

B-mode ultrasound measurement of carotid bifurcation stenoses: is it reliable?

In the majority of cases, duplex ultrasonography (DU) is the sole imaging study necessary before carotid interventions. Duplex-derived internal carotid artery (ICA) peak systolic velocity (PSV), ICA end-diastolic velocity (EDV) and ICA/common carotid artery (CCA) PSV ratio are the most commonly utilized parameters for predicting critical carotid stenoses. However, the role of direct B-mode image measurement of maximal ICA narrowing is ill defined. The images and records of 192 patients who underwent both arteriography and duplex ultrasonography (DU) of 375 carotid arteries from January 1995 to November 2000 were reviewed. All DUs were performed by registered vascular technologists (n=6). Maximum arteriographic stenosis was determined according to the NASCET study design. With arteriography as the "gold standard," B-mode image (BMI) measurement of the maximal ICA luminal narrowing relative to the carotid bulb (n=162)as well as the peak systolic velocity in the internal carotid artery (PSVICA) (n=330), end-diastolic velocity in the internal carotid artery (EDV(ICA)) (n=198), and the ratio of the PSVs in both the ICA and the CCA (PSVICA/CCA) ratio (n=319) were subjected to receiver operator characteristics (ROC) curves for 3 clinically relevant stenoses thresholds: 50-99%, 60-99%, and 70-99%. A strong correlation was found between B-mode image (BMI)and the NASCET arteriographic measures of carotid stenosis (r =0.80;p<0.001) and was similar among the 6 technologists (r =0.74-0.89;p>0.2). The overall accuracy of BMI measurement to diagnose 50%, 60%,and 70% arteriographic carotid stenosis was 85.3%, 82.2%, and 87%, respectively. BMI measurement was similar to the most accurate PSV(ICA), EDV(ICA), and PSV(ICA/CCA) ratio at all 3 threshold stenoses levels (p>0.3). When combined with the velocity criteria, BMI measurement improved the positive predictive value (PPV) for all arteriographic stenoses thresholds by an average of 12.6% for PSV(ICA), 21.2% for EDV(ICA), and 14.2% for PSV(ICA/CCA) ratio. BMI measurement of carotid bifurcation narrowing is as reliable as duplex-derived velocity criteria in evaluating clinically relevant threshold ICA stenoses. The routine use of B-mode ultrasound in conjunction with the velocity parameters enhances the PPV of carotid DU. Our experience suggests that with current refinements in B-mode resolution, BMI stenosis measurements are accurate among experienced technologists and are a useful adjunct to duplex-derived velocity parameters.     

Peak systolic velocity in patients with arterial erectile dysfunction and peripheral arterial disease

The aim of this study is to evaluate whether penile peak systolic velocity (PSV) varies in patients with erectile dysfunction (ED) due to artery insufficiency associated with abnormalities in other arterial districts or not. To accomplish this, cavernous artery PSV was determined 10, 20 and 30 min after intracavernously administering alprostadil by means of echo-color Doppler to a total of 65 consecutive patients (age range 52-78 years). In all, 18 patients had ED alone (group A) and served as controls, 15 had ED plus atheroma plaques and/or marked intima-media thickness of the common carotid artery (group B); 17 had ED plus lower limb artery abnormalities; 17 had ED plus carotid and lower limb artery abnormalities (group D). Group B and C patients had a similar PSV, which turned out to be significantly lower than that in group A. Group D patients had the lowest PSV, which proved to be significantly lower than that in groups A, B and C. This study shows that a more generalized peripheral atherosclerotic process is associated with a severer penile artery insufficiency. Therefore, ED patients with a severe arterial insufficiency should undergo an extensive echo-duplex examination.