A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography:

Summary We replaced Dopplerderived stroke volume in the continuity equation (method A) by either right heart catheterizationderived stroke volume (method B) or cardiovascular magnetic resonance–derived stroke volume (method C) to calculate aortic valve area in 20 consecutive patients with moderate or severe aortic stenosis. Comparison of both hybrid methods (methods B and C) by Bland–Altman analysis showed a mean difference near zero, a spread within two standard deviations and very similar limits of agreement. More importantly, all patients were classified into the same category of severity by both methods.     

Evaluation of aortic valve stenosis using cardiovascular magnetic resonance: comparison of an original semiautomated analysis of phase-contrast cardiovascular magnetic resonance with Doppler echocardiography

Background- Accurate quantification of aortic valve stenosis (AVS) is needed for relevant management decisions. However, transthoracic Doppler echocardiography (TTE) remains inconclusive in a significant number of patients. Previous studies demonstrated the usefulness of phase-contrast cardiovascular magnetic resonance (PC-CMR) in noninvasive AVS evaluation. We hypothesized that semiautomated analysis of aortic hemodynamics from PC-CMR might provide reproducible and accurate evaluation of aortic valve area (AVA), aortic velocities, and gradients in agreement with TTE. Methods and Results- We studied 53 AVS patients (AVA(TTE)=0.87±0.44 cm(2)) and 21 controls (AVA(TTE)=2.96±0.59 cm(2)) who had TTE and PC-CMR of aortic valve and left ventricular outflow tract on the same day. PC-CMR data analysis included left ventricular outflow tract and aortic valve segmentation, and extraction of velocities, gradients, and flow rates. Three AVA measures were performed: AVA(CMR1) based on Hakki formula, AVA(CMR2) based on continuity equation, AVA(CMR3) simplified continuity equation=left ventricular outflow tract peak flow rate/aortic peak velocity. Our analysis was reproducible, as reflected by low interoperator variability (<4.56±4.40%). Comparison of PC-CMR and TTE aortic peak velocities and mean gradients resulted in good agreement (r=0.92 with mean bias=-29±62 cm/s and r=0.86 with mean bias=-12±15 mm Hg, respectively). Although good agreement was found between TTE and continuity equation-based CMR-AVA (r>0.94 and mean bias=-0.01±0.38 cm(2) for AVA(CMR2), -0.09±0.28 cm(2) for AVA(CMR3)), AVA(CMR1) values were lower than AVA(TTE) especially for higher AVA (mean bias=-0.45±0.52 cm(2)). Besides, ability of PC-CMR to detect severe AVS, defined by TTE, provided the best results for continuity equation-based methods (accuracy >94%). Conclusions- Our PC-CMR semiautomated AVS evaluation provided reproducible measurements that accurately detected severe AVS and were in good agreement with TTE.     

A simplified continuity equation approach to the quantification of stenotic bicuspid aortic valves using velocity-encoded cardiovascular magnetic resonance.

OBJECTIVE: We aimed to compare velocity-encoded cine cardiac magnetic resonance (CMR) with an established echocardiographic method for noninvasive measurement of aortic valve area (AVA) using the continuity equation. METHODS AND RESULTS: Twenty consecutive young adults with stenotic bicuspid aortic valves were examined with CMR and transthoracic echocardiography (TTE). CMR AVA was calculated by the continuity equation, dividing stroke volume by the aortic velocity-time integral (VTIAorta), the stroke volume measured both by ventricular volume analysis and by phase contrast velocity mapping at 4 levels (1 subvalvar and 3 supravalvar). Stroke volumes measured at all levels correlated well with those from volumetric analysis. The CMR AVAs calculated using volumetric analysis and VTIAorta from jet velocity mapping correlated and agreed well with TTE AVA measurements (R2 = 0.83). When CMR AVA was calculated more rapidly using volume flow and VTIAorta both measured from the same trans-jet velocity acquisition, R2 was 0.74, with a bias and limits of agreement of 0.02 (-0.44, 0.47) cm2. CONCLUSIONS: Continuity equation calculation of the AVA using CMR velocity mapping, with or without ventricular volumetric measurement, correlated and agreed well with the comparable and widely accepted TTE approach.     

Impact of intraoperative transesophageal echocardiography among patients undergoing aortic valve replacement for aortic stenosis.

In this study, we sought to define the impact of intraoperative transesophageal echocardiography (IOTEE) among patients undergoing aortic valve replacement for severe aortic stenosis. We reviewed the clinical data and preoperative, intraoperative, and postoperative echocardiograms of all adults who underwent aortic valve replacement for aortic stenosis and had IOTEE between January 1993 and December 1996. There were 383 patients (223 men, 160 women; mean age, 69 years). Fifty-four (14%) of the 383 patients had mitral valve surgery at the time of aortic valve replacement. In 6 patients, mitral valve surgery was not planned but was added because of findings on IOTEE. In 25 patients, mitral valve surgery was canceled on the basis of the IOTEE. Additional information was found by IOTEE in 25 patients before and after bypass, altering the surgical plan in 18 of these 25 patients. Overall, IOTEE altered the planned operation in 49 (13%) of the 383 patients. These data support the routine use of IOTEE among patients undergoing aortic valve replacement for aortic stenosis.     

Safety of adenosine stress magnetic resonance imaging using a mobile cardiac magnetic resonance system.

BACKGROUND: Contrast-enhanced magnetic resonance imaging (ceMRI) allows for the detection of ischemic heart disease. Aim of this prospective study was to show feasibility, practicability and safety of adenosine stress ceMRI in routine outpatients with a mobile scanner. METHODS: Consecutive patients were scanned in six different cardiac outpatient centers with a 1.5 T mobile ceMRI scanner. First-pass wash-in patterns of gadolinium chelate were evaluated after three minutes of adenosine infusion. After a second bolus of gadolinium chelate myocardial late enhancement (MLE) images of the left ventricle were acquired to visualize myocardial necrosis. RESULTS: Five hundred seventy-four patients were enrolled to the study. No major complications during examination and adenosine infusion were observed. One hundred seventy-three minor complications as temporary atrio-ventriculare blockade, mild chest pain or dyspnea and nausea were noticed. None of the complications led to further special treatment CONCLUSION: This ceMRI protocol is suitable for application in outpatient settings. CeMRI stress testing using a mobile scanner in an outpatient setting is feasible and safe.     

Metastatic cardiac liposarcoma: diagnosis by transesophageal echocardiography and magnetic resonance imaging

The most superior portion of the right atrium is not well visualized by transthoracic echocardiography. This limits the ability of the technique to detect intracardiac disease in this area. We describe a 41-year-old man with a history of liposarcoma in whom transthoracic echocardiography was unable to elucidate a right atrial metastasis. Transesophageal echocardiography demonstrated the morphology and extent of the large right atrial mass. These findings were well correlated with both magnetic resonance imaging and surgery.     

Early detection of subclinical ventricular deterioration in aortic stenosis with cardiovascular magnetic resonance and echocardiography

Background

Severe aortic stenosis (AS) patients with late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) or left ventricular (LV) systolic dysfunction are known to have worse outcome. We aimed to investigate whether LGE on CMR would be useful in early detection of subclinical LV structural and functional derangements in AS patients.

Methods

118 patients with moderate to severe AS were prospectively enrolled. Echocardiography and CMR images were taken and the patients were divided into groups according to the presence/absence of LGE and of LV systolic dysfunction (LV ejection fraction (EF) <50%). The stiffness of LV was calculated based on Doppler and CMR measurements.

Results

Patients were grouped into either group 1, no LGE and normal LVEF, group 2, LGE but normal LVEF and group 3, LGE with depressed LVEF. There was a significant trend towards increasing LV volumes, worsening of LV diastolic function (E/e’, diastolic elastance), systolic function (end-systolic elastance) and LV hypertrophy between the three groups, which coincided with worsening functional capacity (all p-value < 0.001 for trend). Also, significant differences in the above parameters were noted between group 1 and 2 (E/e’, 14.6 ± 4.3 (mean ± standard deviation) in group 1 vs. 18.2 ± 9.4 in group 2; end-systolic elastance, 3.24 ± 2.31 in group 1 vs. 2.38 ± 1.16 in group 2, all p-value < 0.05). The amount of myocardial fibrosis on CMR correlated with parameters of diastolic (diastolic elastance, Spearman’s ρ = 0.256, p-value = 0.005) and systolic function (end-systolic elastance, Spearman’s ρ = -0.359, p-value < 0.001).

Conclusions

These findings demonstrate the usefulness of CMR for early detection of subclinical LV structural and functional deterioration in AS patients.     

冠状动脉血流显像评价主动脉瓣狭窄瓣膜置换术后的冠状动脉血流储备

目的　应用冠状动脉血流显像技术结合双嘧达莫负荷试验探讨主动脉瓣狭窄患者主动脉瓣置换术 (AVR)前后的冠脉血流储备 (CFR)的变化。方法　分别在AVR前和AVR后 6个月两种情况下检测 3 1例单纯主动脉瓣狭窄患者的冠状动脉左前降支 (LAD)远端的舒张期血流速度峰值 (CPV)和速度时间积分 (VTI) ;然后经静脉注射双嘧达莫 ,测量达到最大充血状态的CPV和VTI ;CFR由用药后与用药前冠脉血流的CPV比和VTI比来计算 ;测量受试者的室间隔厚度 (IVST )、左室后壁厚度 (PWT)、左室内径 (LVID)、冠状动脉左前降支远端直径 (LADD) ;计算CPV和VTI与IVST的比值。结果　 2 4例患者得到了手术前后成对的完整资料 ,IVST和PWT在主动脉瓣置换术后较术前明显减小 ,LVID却无明显变化 ;LADD也从术前的 (2 .2 72± 0 .0 15 )mm下降到 (2 .2 3 1± 0 .0 47)mm (P >0 .0 5 )。在静息状态 ,CPV和VTI在手术后稍降低 ,差别无显著性意义 (P >0 .0 5 ) ;CPV和VTI与IVST的比值均轻度增加 (P >0 .0 5 ) ;在充血状态 ,CPV和VTI在手术前后均明显增加 ,但术后的增加程度高于术前 ;术后的CPV和VTI与IVST的比值均显著增加 (P <0 .0 0 1) ;术后的冠脉血流储备也显著增加。结论　主动脉瓣狭窄患者在主动脉瓣置换术后冠脉血流储备明显增加 ,这个增加出     

MRI相位编码速度标识技术定量检测儿童二尖瓣反流:与超声心动图对比

目的 利用MR相位编码速度标识技术对儿童二尖瓣反流进行定量分析,并与超声心动图半定量结果进行比较. 方法 病例组为二尖瓣反流患儿61例,其中轻度反流16例,轻中度反流16例,中度反流20例,中重度反流4例,重度反流5例.对照组20例,其中8例无心肺疾病,12例为先天性心脏病但室间隔完整无二尖瓣反流及主动脉瓣反流.利用MR相位编码速度标识技术分别测定对照组和病例组的左心室流入量和主动脉流量. 结果 对照组中,左心室流入量与主动脉流量之间相关性良好.除轻度二尖瓣反流外,对照组与病变组其余各组间反流量与反流指数差异均有统计学意义;病变组各组间二尖瓣反流差异有统计学意义;二尖瓣反流指数与超声的二尖瓣反流程度的总体相关性良好. 结论 MRI相位编码速度标识技术是一种非创伤性的定量分析儿童二尖瓣反流的较好方法,并为外科手术以及术后随访提供更为精确的信息.     

Comparison of conventional and transesophageal echocardiography with magnetic resonance imaging for anatomical mapping of thoracic aortic dissection

Thirty-five consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol using comprehensive echocardiography and ECG-triggered MRI with multi-slice spin echo and cine sequences in random order. The purpose of this dual imaging study was to compare the diagnostic accuracy of two-dimensional and color-coded Doppler echocardiography using the conventional transthoracic (TTE) and the transesophageal approach (TEE) with magnetic resonance imaging (MRI) for the exact morphologic evaluation and anatomical mapping of the thoracic aorta. The results of each diagnostic method were validated independently against the ‘gold standard’ of intraoperative findings (n=17), necropsy (n=4) or contrast angiography (n=22). Compared to conventional transthoracic echocardiography both TEE and MRI were more reliable in detecting aortic dissections (TTE vs TEE: p<0.02; TTE vs MRI: p<0.01) and associated epiphenomena. Moreover, the reliability of TTE decreased significantly from proximal to distal segments of the aorta, e.g. from the ascending segment to the arch (p<0.05) and to the descending aorta (p<0.005), whereas the sensitivities of both TEE and MRI were excellent irrespective of the site of dissection. With regard to epiphenomena such as thrombus formation and entry location, MRI emerged as the optimal method for detailed morphologic information in all segments of the aorta. No serious side effects were encountered with either method. Thus, in patients with suspected acute or subacute aortic dissections the echocardiographic assessment should include the transesophageal approach for significant improvement of the moderate sensitivity and specificity of TTE. Both TEE and MRI are non-traumatic, safe and diagnostically accurate to identify and classify acute and subacute dissections of the thoracic aorta irrespective of their location. MRI provides superb anatomical mapping of all type A and B dissections and more detailed information on the site of entry and thrombus formation than TEE. These features of TEE and MRI may render retrograde contrast angiography obsolete in the setting of thoracic aortic dissection and may encourage surgical interventions exclusively on the basis of noninvasive imaging.     

Evaluation of the aortic and mitral valves with cardiac computed tomography and cardiac magnetic resonance imaging

Cardiac computed tomography (CT) produces high-quality anatomical images of the cardiac valves and associated structures. Cardiac magnetic resonance imaging (MRI) provides images of valve morphology, and allows quantitative evaluation of valvular dysfunction and determination of the impact of valvular lesions on cardiovascular structures. Recent studies have demonstrated that cardiac CT and MRI are important adjuncts to echocardiography for the evaluation of aortic and mitral valvular heart diseases (VHDs). Radiologists should be aware of the technical aspects of cardiac CT and MRI that allow comprehensive assessment of aortic and mitral VHDs, as well as the typical imaging features of common and important aortic and mitral VHDs on cardiac CT and MRI.     

Impact of asymmetry on measurements of the aortic root using cardiovascular magnetic resonance imaging in patients with a bicuspid aortic valve

To assess the impact of aortic root asymmetry on the relationship between aortic dimensions derived from two-dimensional transthoracic echocardiography (TTE) as compared with cross-sectional cardiovascular magnetic resonance (CMR) imaging in adults with a bicuspid aortic valve (BAV). Maximal CMR cross-sectional aortic measurements at the level of the sinuses of Valsalva, including cusp–commissure, cusp–cusp diameters and aortic root areas, from 68 consecutive patients (65 % male) were retrospectively analyzed. The degree of aortic root asymmetry on CMR was expressed using the coefficient of variance of the root diameters in each dimension for an individual (CoeffVi) as compared with the median of the entire population (CoeffVp) and asymmetry was defined as CoeffVi > CoeffVp. Values obtained from CMR were compared with standard root measurements using TTE from contemporary studies (48 patients, 71 %). Reproducibility of CMR measurements was assessed using the intra-class correlation coefficient (ICC). Echocardiography systematically underestimated aortic root dimensions in comparison with CMR, particularly in asymmetric roots with cusp–cusp measurements in systole (bias: ?4.9 mm). Best agreement between modalities existed in symmetric roots with cusp–commissure measurements in diastole (bias: ?0.01 mm). CMR measurements showed excellent intra-reader (ICC ≥ 0.98) and moderate inter-reader (ICC range 0.37–0.95) reproducibility, particularly aortic root area (inter/intra-reader ICC ≥ 0.94). In comparison to cross-sectional CMR diameters, standard TTE measurements consistently underestimates maximum aortic root diameter in adults with a BAV and aortic root asymmetry further decreases the agreement between CMR and TTE. CMR-derived aortic root measurements are reproducible and aortic root area showed the best reproducibility.     

Comparison between cardiovascular magnetic resonance and transthoracic doppler echocardiography for the estimation of effective orifice area in aortic stenosis

Background

The effective orifice area (EOA) estimated by transthoracic Doppler echocardiography (TTE) via the continuity equation is commonly used to determine the severity of aortic stenosis (AS). However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance (CMR) has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA.

Methods and results

31 patients with mild to severe AS (EOA range: 0.72 to 1.73 cm²) and seven (7) healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract (LVOT) cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area (A_LVOT, 3.84 ± 0.80 cm²) compared to CMR (4.78 ± 1.05 cm²). On the other hand, TTE overestimated the LVOT velocity-time integral (VTI_LVOT: 21 ± 4 vs. 15 ± 4 cm). Good concordance was observed between TTE and CMR for estimation of aortic jet VTI (61 ± 22 vs. 57 ± 20 cm). Overall, there was a good correlation and concordance between TTE-derived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm², r = 0.92, bias = 0.06 ± 0.29 cm²). The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.

Conclusion

Underestimation of A_LVOT by TTE is compensated by overestimation of VTI_LVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.     

Tricuspid valve magnetic resonance imaging phase contrast velocity-encoded flow quantification for follow up of tetralogy of Fallot

Our purpose was to identify E- and A-wave flow patterns across the tricuspid valve in tetralogy of Fallot (TOF) patients following repair using magnetic resonance imaging phase contrast velocity-encoded flow quantification and to correlate them with measurements of right ventricle enlargement. The study included 33 children following TOF repair who had MRI examinations that included cine imaging to quantify ventricle size and function and flow analysis across the atria-ventricular valves to evaluate ventricle in-flow patterns. The E:A ratio was calculated for each patient and the population separated into α (E:A ratio ≥ 1.4) and β (E:A ratio < 1.4) groups. Significant association was present between the β group and right ventricle end diastolic volume index ≥140 ml/m² (P = 0.046), right ventricle end systolic volume index ≥70 ml/m² (P = 0.02), and end diastolic volume right ventricle to left ventricle ≥ 2.0 (P = 0.003). A reduction in the E:A wave ratio across the tricuspid valve is associated with right ventricle diastolic dysfunction and correlated well in our study with right ventricle enlargement. This may be a useful criterion for determining the timing of valved pulmonary conduit surgery in children following TOF repair.     

Prospective comparison of echocardiography versus cardiac magnetic resonance imaging in patients with Ebstein's anomaly

Ebstein's anomaly (EA) is primarily diagnosed by echocardiography. The purpose of this study was to compare echocardiography and magnetic resonance imaging (MRI) in EA. Data from cardiac MRI and echocardiography were prospectively collected from 16 patients with EA. Imaging data also were compared with intraoperative findings. Information provided by MRI and echocardiography were comparable for left ventricular size and function, tricuspid valve repairability, qualitative assessment of right-sided cavities, and visibility of septal and anterior tricuspid valve leaflets. The posterior tricuspid valve leaflet and tricuspid valve fenestrations were better visualized with MRI; associated heart defects were equally recognized, apart from small shunts that tended to be more readily diagnosed with echocardiography. Quantification of right-cavity size and right ventricular ejection fraction was possible only with cardiac MRI. The degree of tricuspid valve regurgitation was underestimated by echocardiography (2 patients) and by MRI (4 patients) when compared with intraoperative assessment. When evaluating EA, echocardiography and MRI provide complementary data. For visualization of the posterior tricuspid valve leaflet and quantitative assessment of right ventricular size and function, MRI is preferable. For appropriate risk stratification in EA, both MRI and echocardiography should be performed before cardiac surgery.     

高分辨率磁共振扫描在颅内动脉狭窄中的应用

目的：探索高分辨率磁共振扫描技术在颅内动脉狭窄处管壁成像中的应用价值。方法采用3.0T 磁共振扫描仪,应用3D-TOF,TIRM,T2WI,T1WI(平扫+增强)序列对37例颅内动脉造影证实的颅内动脉狭窄患者进行扫描。结果3例患者因躁动及幽闭恐惧等原因无法完成扫描,其余34例患者正常完成扫描,可以有效的显示颅内动脉狭窄的程度及原因。结论应用3.0T 磁共振高分辨率扫描技术,可以明确显示颅内动脉狭窄的程度及原因,提供更有意义的诊断信息。     

Cardiovascular magnetic resonance as a reliable alternative to cardiovascular computed tomography and transesophageal echocardiography for aortic annulus valve sizing

To assess the accuracy and reproducibly of cardiovascular magnetic resonance (CMR) in the measurement of the aortic annulus and in process of valve sizing as compared to intra-operative sizing, cardiovascular computed tomography (CCT) and transesophageal echocardiography (TEE). Retrospective study on 42 patients who underwent aortic valve replacement from September 2010 to September 2015, with available records of pre surgery annulus assessment by CMR, CCT and TEE and of peri-operative assessment. In CCT and CMR, the annular plane was considered a virtual ring formed by the lowest hinge points of the valvular attachments to the aorta. In TEE the annulus was measured at the base of leaflet insertion in the mid-esophageal long-axis view using the X-plane technique. Two double-blinded operators performed the assessments for each imaging technique. Intra-operative evaluation was performed using Hegar dilators. Continuous variables were studied with within-subject ANOVA, Bland–Altman (BA) plots, Wilcoxon’s and Friedman’s tests; trends were explored with scatter plots. Categorical variables were studied with Fisher’s exact test. The intra- and inter-operator reliability was satisfying. There were no significant differences between the annulus dimensions measured by CMR and either one of the three references. Valve sizing for CoreValve by CMR had the same good agreement with CCT and TEE, with a 78?% match rate; for SAPIEN XT the agreement was slightly better (82?%) for CCT than for TEE (66?%). MR performs well when compared to the surgical reference of intra-operative sizing and stands up to the level of the most used imaging references (CCT and TEE).     

Lumbar stenosis rates in symptomatic patients using weight-bearing and recumbent magnetic resonance imaging

Objective

The purpose of this study was to determine the rate of lumbar stenosis detected via magnetic resonance imaging (MRI) in patients with symptomatic foraminal stenosis, lateral recess stenosis, or central stenosis.

Methods

A retrospective review was performed on 1983 MRI scans from a 2-year period on 1486 symptomatic patients. Of these patients, 761 were scanned in the recumbent position using low-field (0.3 T, Airis II; Hitachi, Twinsburg, Ohio) MRI, and 725 were scanned in an upright sitting position using midfield (0.6 T) open Upright MRI (Fonar Corp, Melville, NY). In total, 986 serial scans (recumbent) and 997 serial scans (weight-bearing) were performed.

Results

Of scans performed in the recumbent position, stenoses were identified in 382 scans (38.8%), central stenosis in 119 scans (12%), lateral recess stenosis in 91 scans (9.2%), and foraminal stenosis in 327 scans (33.2%). Of scans performed in a weight-bearing position, stenoses were identified in 565 scans (56.7%), central stenosis in 136 scans (13.6%), lateral recess stenosis in 206 scans (20.7%), and foraminal stenosis in 524 scans (52.6%).

Conclusions

The stenosis rates as indicated by MRI interpretation ranged between 38.5% (recumbent) and 56.7% (weight-bearing). These rates are higher than those reported in the medical literature for asymptomatic patients. Further study is needed to determine whether weight-bearing, compared with recumbent, MRI better informs the clinician in the diagnosis of spinal stenosis.     

Digital fourier techniques in the diagnosis and quantification of aortic stenosis with pulsed-Doppler echocardiography

Pulsed Doppler echocardiography and digital Fourier analysis were utilized to examine flow distal to the aortic valve and to quantify aortic stenosis. A graphic index of parameters derived from velocity spectrum patterns generated by Fourier analysis was regressed against mean systolic pressure gradients in 21 adults with clinical evidence of aortic stenosis who underwent catheterization studies and five normal adults (r = .82). Correlation improved in the absence of regurgitation (r = .92). Sensitivity for detecting gradients > 30 mmHg was 86%; specificity was 90%. Doppler spectral analysis shows promise in alleviating the need for many invasive studies.