Prognostic importance of the transmitral pressure gradient in mitral annular calcification with associated mitral valve dysfunction.

AIMS: The aim of this study was to define the natural history of patients with mitral annular calcification (MAC)-related mitral valve dysfunction and to assess the prognostic importance of mean transmitral pressure gradient (MG) and impact of concomitant mitral regurgitation (MR). METHODS AND RESULTS: The institutional echocardiography database was examined from 2001 to 2019 for all patients with MAC and MG ≥3 mmHg. A total of 5754 patients were stratified by MG in low (3-5 mmHg, n = 3927), mid (5-10 mmHg, n = 1476), and high (≥10 mmHg, n = 351) gradient. The mean age was 78 ± 11 years, and 67% were female. MR was none/trace in 32%, mild in 42%, moderate in 23%, and severe in 3%. Primary outcome was all-cause mortality, and outcome models were adjusted for age, sex, and MAC-related risk factors (hypertension, diabetes, coronary artery disease, chronic kidney disease). Survival at 1, 5, and 10 years was 77%, 42%, and 18% in the low-gradient group; 73%, 38%, and 17% in the mid-gradient group; and 67%, 25%, and 11% in the high-gradient group, respectively (log-rank P < 0.001 between groups). MG was independently associated with mortality (adjusted HR 1.064 per 1 mmHg increase, 95% CI 1.049-1.080). MR severity was associated with mortality at low gradients (P < 0.001) but not at higher gradients (P = 0.166 and 0.372 in the mid- and high-gradient groups, respectively). CONCLUSION: In MAC-related mitral valve dysfunction, mean transmitral gradient is associated with increased mortality after adjustment for age, sex, and MAC-related risk factors. Concomitant MR is associated with excess mortality in low-gradient ranges (3-5 mmHg) but gradually loses prognostic importance at higher gradients, indicating prognostic utility of transmitral gradient in MAC regardless of MR severity.

Contrast-Enhanced Ultrasound: A Novel Noninvasive, Nonionizing Method for the Detection of Brown Adipose Tissue in Humans.

BACKGROUND: Brown adipose tissue (BAT) consumes glucose when it is activated by cold exposure, allowing its detection in humans by (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT). The investigators recently described a novel noninvasive and nonionizing imaging method to assess BAT in mice using contrast-enhanced ultrasound (CEUS). Here, they report the application of this method in healthy humans. METHODS: Thirteen healthy volunteers were recruited. CEUS was performed before and after cold exposure in all subjects using a continuous intravenous infusion of perflutren gas-filled lipid microbubbles and triggered imaging of the supraclavicular space. The first five subjects received microbubbles at a lower infusion rate than the subsequent eight subjects and were analyzed as a separate group. Blood flow was estimated as the product of the plateau (A) and the slope (ß) of microbubble replenishment curves. All underwent (18)F-FDG PET/CT after cold exposure. RESULTS: An increase in the acoustic signal was noted in the supraclavicular adipose tissue area with increasing triggering intervals in all subjects, demonstrating the presence of blood flow. The area imaged by CEUS colocalized with BAT, as detected by ¹8F-FDG PET/CT. In a cohort of eight subjects with an optimized CEUS protocol, CEUS-derived BAT blood flow increased with cold exposure compared with basal BAT blood flow in warm conditions (median Aß = 3.3 AU/s [interquartile range, 0.5-5.7 AU/s] vs 1.25 AU/s [interquartile range, 0.5-2.6 AU/s]; P = .02). Of these eight subjects, five had greater than twofold increases in blood flow after cold exposure; these responders had higher BAT activity measured by (18)F-FDG PET/CT (median maximal standardized uptake value, 2.25 [interquartile range, 1.53-4.57] vs 0.51 [interquartile range, 0.47-0.73]; P = .02). CONCLUSIONS: The present study demonstrates the feasibility of using CEUS as a noninvasive, nonionizing imaging modality in estimating BAT blood flow in young, healthy humans. CEUS may be a useful and scalable tool in the assessment of BAT and BAT-targeted therapies.

Major Cardiac Events and the Value of Echocardiographic Evaluation in Patients Receiving Anthracycline-Based Chemotherapy.

Anthracyclines are an important component of cancer treatments; however, their use is limited by the occurrence of cardiotoxicity. There are limited data on the occurrence of heart failure and the value of baseline and follow-up measurements of left ventricular (LV) ejection fraction (EF) in the current era. Therefore, the objectives of the present study were twofold: (1) to characterize the occurrence of and risk factors for major adverse cardiac events (MACEs: symptomatic heart failure and cardiac death) in a large contemporaneous population of adult patients treated with anthracyclines and (2) to test the value of LVEF and LV dimensions obtained using echocardiography in the prediction of MACE. Five thousand fifty-seven patients were studied, of whom 124 (2.4%) developed MACE. Of the total cohort, 2,285 patients had an available echocardiogram pre-chemotherapy. Patients with MACE were older (p <0.0001), predominantly men (p = 0.03), and with a higher incidence of cardiovascular risk factors and cardiac treatments. Patients with hematologic cancers had a higher incidence of cardiac events than patients with breast cancer (4.2% vs 0.7%, p <0.0001). Baseline LVEF, LVEF ≤5 points above the lower limits of normal, and LV internal diameter were predictive of the rate of occurrence of MACE. In conclusion, older patients with hematologic cancers and patients with a baseline LVEF ≤5 points above the lower limit of normal have higher incidence of MACE and should be closely monitored.

The echo score revisited: Impact of incorporating commissural morphology and leaflet displacement to the prediction of outcome for patients undergoing percutaneous mitral valvuloplasty.

BACKGROUND: Current echocardiographic scoring systems for percutaneous mitral valvuloplasty (PMV) have limitations. This study examined new, more quantitative methods for assessing valvular involvement and the combination of parameters that best predicts immediate and long-term outcome after PMV. METHODS AND RESULTS: Two cohorts (derivation n=204 and validation n=121) of patients with symptomatic mitral stenosis undergoing PMV were studied. Mitral valve morphology was assessed by using both the conventional Wilkins qualitative parameters and novel quantitative parameters, including the ratio between the commissural areas and the maximal excursion of the leaflets from the annulus in diastole. Independent predictors of outcome were assigned a points value proportional to their regression coefficients: mitral valve area ≤1 cm(2) (2), maximum leaflets displacement ≤12 mm (3), commissural area ratio ≥1.25 (3), and subvalvular involvement (3). Three risk groups were defined: low (score of 0-3), intermediate (score of 5), and high (score of 6-11) with observed suboptimal PMV results of 16.9%, 56.3%, and 73.8%, respectively. The use of the same scoring system in the validation cohort yielded suboptimal PMV results of 11.8%, 72.7%, and 87.5% in the low-, intermediate-, and high-risk groups, respectively. The model improved risk classification in comparison with the Wilkins score (net reclassification improvement 45.2%; P<0.0001). Long-term outcome was predicted by age and postprocedural variables, including mitral regurgitation, mean gradient, and pulmonary pressure. CONCLUSIONS: A scoring system incorporating new quantitative echocardiographic parameters more accurately predicts outcome following PMV than existing models. Long-term post-PMV event-free survival was predicted by age, degree of mitral regurgitation, and postprocedural hemodynamic data.

The Björk-Shiley convexo-concave heart valve experience from the perspective of the supervisory panel.

The 20-year activities of a medical supervisory panel appointed under the terms of a settlement agreement of the Bowling v. Pfizer class action suit involving the Björk-Shiley convexo-concave (BSCC) heart valve are detailed. Of approximately 86,000 valves implanted, catastrophic failure of the valve was reported in 663 patients from 1978 to 2012. In 1994, a 7-member medical panel consisting of cardiologists, cardiovascular surgeons, epidemiologists, and a nontechnical chairman was appointed by the federal court. The panel collected clinical and manufacturing data, supported epidemiologic studies assessing risk factors for valve fracture, and developed guidelines for payment for explanting potentially defective valves in patients. Three sets of guidelines, based on comparisons of estimated risks of valve fracture versus risks of valve replacement surgery, were issued by the panel to help guide patients and their physicians in decisions about explanting valves. In addition, the panel supported research directed at identifying valves at risk for outlet strut fracture. The primary techniques evaluated included analyzing acoustic signals from the valves, imaging valves for potential cracks in the struts, and structural analyses of Björk-Shiley convexo-concave valves, but none proved applicable for large-scale surveillance of the patient population. The panel also became a patient advocate and acted as an intermediary between the manufacturer and the attorneys initiating the legal settlement. The panel's experiences may help inform future strategies for guideline development for other medical devices or procedures involving risk-benefit comparisons.

The impact of isometric handgrip testing on left ventricular twist mechanics.

Left ventricular (LV) rotation occurs due to contraction of obliquely oriented myocardial fibres. Left ventricular twist (LVT) results from rotation of the apex and base in opposite directions. Although LVT is altered in various cardiac diseases, physiological factors that affect LVT remain incompletely understood. Isometric handgrip testing (IHGT), a well-established laboratory-based technique to increase LV afterload, was performed for 3 min at 40% maximum force generation in healthy human subjects (n = 18, mean age 29.7 ± 2.7 years). Speckle-tracking echocardiography was used to measure LV volumes, LV apical and basal rotation, peak systolic LVT and peak early diastolic untwisting rate (UTR) at rest and at peak IHGT. IHGT led to significant increase in systemic blood pressure (systolic, 120.6 ± 9.7 vs. 155.6 ± 14.5 mmHg, P < 0.001; diastolic, 67.5 ± 6.4 vs. 94.1 ± 21.1 mmHg, P < 0.001) and LV end-systolic volume (44.2 ± 7.8 vs. 50.5 ± 10.8 ml, P = 0.005), as well as a significant increase in heart rate (62.8 ± 11.7 vs. 84.7 ± 13.8 beats min−1; P < 0.001). IHGT produced a significant acute reduction in LV stroke volume (63.9 ± 12.0 vs. 49.4 ± 7.8 ml, P < 0.001). In this setting, there was a significant decrease in peak systolic apical rotation (11.9 ± 3.0 vs. 8.6 ± 2.2 deg, P < 0.001) and a resultant 25% decrease in peak systolic LVT (16.6 ± 2.8 vs. 12.5 ± 2.8 deg, P < 0.001). The magnitude of peak early diastolic UTR did not change (−114.5 ± 26.4 vs. −110.6 ± 39.8 deg s−1, P = 0.71). Peak systolic apical rotation and LVT decrease during IHGT in healthy humans. This impairment of LV twist mechanics may in part underlie the LV dysfunction that can occur in the clinical context of acute increase in afterload.

Absence of left ventricular apical rocking and atrial-ventricular dyssynchrony predicts non-response to cardiac resynchronization therapy.

AIMS: Current imaging techniques attempt to identify responders to cardiac resynchronization therapy (CRT). However, because CRT response may depend upon several factors, it may be clinically more useful to identify patients for whom CRT would not be beneficial even under optimal conditions. We aimed to determine the negative predictive value of a composite echocardiographic index evaluating atrial-ventricular dyssynchrony (AV-DYS) and intraventricular dyssynchrony. METHODS AND RESULTS: Subjects with standard indications for CRT underwent echo before and during the month following device implantation. AV-DYS was defined as a percentage of left ventricular (LV) filling time over the cardiac cycle. AV-DYS, which produces a characteristic rocking of the LV apex, was quantified as the percentage of the cardiac cycle over which tissue Doppler-derived displacement curves of the septal and lateral walls showed discordance. CRT responder status was determined based on the early haemodynamic response to CRT (intra-individual improvement >25% in the Doppler-derived LV dP/dt). Among 40 patients, optimal cut-points predicting CRT response were 31% for LV apical rocking and 39% for AV-DYS. The presence of either apical rocking >31% or AV-DYS ≤ 39% had a sensitivity of 95%, specificity of 80%, positive predictive value of 83%, and a negative predictive value of 94% for CRT response. CONCLUSION: After pre-selection of candidates for CRT by QRS duration, application of a simple composite echocardiographic index may exclude patients who would be non-responders to CRT and thus improve the global rate of therapy success.

Pulmonary artery acceleration time provides an accurate estimate of systolic pulmonary arterial pressure during transthoracic echocardiography.

BACKGROUND: Transthoracic echocardiographic estimates of peak systolic pulmonary artery pressure are conventionally calculated from the maximal velocity of the tricuspid regurgitation (TR) jet. Unfortunately, there is insufficient TR to determine estimated peak systolic pulmonary artery pressure (EPSPAP) in a significant number of patients. To date, in the absence of TR, no noninvasive method of deriving EPSPAP has been developed. METHODS: Five hundred clinically indicated transthoracic echocardiograms were reviewed over a period of 6 months. Patients with pulmonic stenosis were excluded. Pulsed-wave Doppler was used to measure pulmonary artery acceleration time (PAAT) and right ventricular ejection time. Continuous-wave Doppler was used to measure the peak velocity of TR (TR(Vmax)), and EPSPAP was calculated as 4 × TR(Vmax)(2) + 10 mm Hg (to account for right atrial pressure). The relationship between PAAT and EPSPAP was then assessed. RESULTS: Adequate imaging to measure PAAT was available in 99.6% of patients (498 of 500), but 25.3% (126 of 498) had insufficient TR to determine EPSPAP, and 1 patient had significant pulmonic stenosis. Therefore, 371 were included in the final analysis. Interobserver variability for PAAT was 0.97. There were strong inverse correlations between PAAT and TR(Vmax) (r = -0.96), the right atrial/right ventricular pressure gradient (r = -0.95), and EPSPAP (r = -0.95). The regression equation describing the relationship between PAAT and EPSPAP was log(10)(EPSPAP) = -0.004 (PAAT) + 2.1 (P < .001). CONCLUSIONS: PAAT is routinely obtainable and correlates strongly with both TR(Vmax) and EPSPAP in a large population of randomly selected patients undergoing transthoracic echocardiography. Characterization of the relationship between PAAT and EPSPAP permits PAAT to be used to estimate peak systolic pulmonary artery pressure independent of TR, thereby increasing the percentage of patients in whom transthoracic echocardiography can be used to quantify pulmonary artery pressure.

The impact of endurance exercise training on left ventricular torsion.

OBJECTIVES: We sought to examine the effect of endurance exercise training (EET) on peak systolic left ventricular torsion (LVT) and peak early diastolic untwisting rate (UTR). BACKGROUND: Left ventricular (LV) structural adaptations to EET have been well characterized. LVT, a recognized marker of LV function in numerous cardiac diseases, has recently been investigated in the setting of exercise. However, longitudinal data characterizing the impact of sustained exercise training on LVT have not been reported. METHODS: A prospective, longitudinal study design examined the impact of a 90-day period of training on LV twist mechanics in university male rowers (n = 15, mean age 18.6 ± 0.5 years). Conventional LV structural measurements, LV apical and basal rotation, peak systolic LVT, and peak early diastolic UTR were measured by 2-dimensional and speckle tracking echocardiography before and after the EET study period. RESULTS: Participants experienced LV eccentric hypertrophy, characterized by increased LV end-diastolic volume (80.8 ± 8.7 ml/m(2) vs. 91.3 ± 8.0 ml/m(2), p < 0.001) and LV mass (101.3 ± 11.4 g/m(2) vs. 115.7 ± 12.6 g/m(2), p = 0.001). There was a significant increase in peak systolic apical rotation (8.9 ± 4.2° vs. 12.7 ± 3.9°, p = 0.002) but no change in basal rotation. This translated into a highly significant increase in peak systolic LVT after EET (14.1 ± 5.0° vs. 18.0 ± 3.6°, p = 0.002). The impact of EET on LV twist mechanics was not confined to ventricular systole, as peak early diastolic UTR (-110.6 ± 41.8°/s vs. -148.0 ± 29.8°/s, p = 0.003) and the percentage of untwisting that occurred by the end of isovolumic relaxation (31.2 ± 12.0% vs. 39.9 ± 14.9%, p = 0.04) increased. CONCLUSIONS: Participation in EET was associated with significant changes in LV twist mechanics characterized by increased apical rotation, LVT, and UTR. These findings suggest that LVT and UTR augmentation may be an important and previously unrecognized component of exercise-induced cardiac remodeling.

Preload dependency of left ventricular torsion: the impact of normal saline infusion.

BACKGROUND: left ventricular (LV) rotation results from contraction of obliquely oriented myocardial fibers. The net difference between systolic apical counterclockwise rotation and basal clockwise rotation is left ventricular torsion (LVT). Although LVT is altered in various cardiac diseases, determinants of LVT are incompletely understood. METHODS AND RESULTS: LV end-diastolic volume, LV apical and basal rotation, peak systolic LVT, and peak early diastolic untwisting rate were measured by speckle-tracking echocardiography in healthy subjects (n=8) before and after infusion of a weight-based normal saline bolus (2.1±0.3 L). Saline infusion led to a significant increase in end-diastolic LV internal diameter (45.9±3.7 versus 47.6±4.2 mm; P=0.002) and LV end-diastolic volume (90.0±21.6 versus 98.3±19.6 mL; P=0.01). Stroke volume (51.3±10.9 versus 63.0±15.5 mL; P=0.003) and cardiac output (3.4±0.8 versus 4.4±1.5 L/min; P=0.007) increased, whereas there was no change in heart rate and blood pressure. There was a significant increase in the magnitude of peak systolic apical rotation (7.5±2.4° versus 10.5±2.8°; P<0.001) but no change in basal rotation (-4.1±2.3° versus -4.8±3.1°; P=0.44). Accordingly, peak systolic LVT increased by 33% after saline infusion (11.2±1.3° versus 14.9±1.7°; P<0.001). This saline-induced increase in LVT was associated with a marked increase in peak early diastolic untwisting rate (72.3±21.4 versus 136.8±30.0 degrees/s; P<0.001). CONCLUSIONS: peak systolic LVT and peak early diastolic untwisting rate are preload-dependent. Changes in LV preload should be considered when interpreting results of future LVT studies.

The impact of moderate-altitude staging on pulmonary arterial hemodynamics after ascent to high altitude.

Staged ascent (SA), temporary residence at moderate altitude en route to high altitude, reduces the incidence and severity of noncardiopulmonary altitude illness such as acute mountain sickness. To date, the impact of SA on pulmonary arterial pressure (PAP) is unknown. We tested the hypothesis that SA would attenuate the PAP increase that occurs during rapid, direct ascent (DA). Transthoracic echocardiography was used to estimate mean PAP in 10 healthy males at sea level (SL, P(B) approximately 760 torr), after DA to simulated high altitude (hypobaric chamber, P(B) approximately 460 torr), and at 2 times points (90 min and 4 days) during exposure to terrestrial high altitude (P(B) approximately 460 torr) after SA (7 days, moderate altitude, P(B) approximately 548 torr). Alveolar oxygen pressure (Pao(2)) and arterial oxygenation saturation (Sao(2)) were measured at each time point. Compared to mean PAP at SL (mean +/- SD, 14 +/- 3 mmHg), mean PAP increased after DA to 37 +/- 8 mmHg (Delta = 24 +/- 10 mmHg, p < 0.001) and was negatively correlated with both Pao(2) (r(2) = 0.57, p = 0.011) and Sao(2) (r(2) = 0.64, p = 0.005). In comparison, estimated mean PAP after SA increased to only 25 +/- 4 mmHg (Delta = 11 +/- 6 mmHg, p < 0.001), remained unchanged after 4 days of high altitude residence (24 +/- 5 mmHg, p = not significant, or NS), and did not correlate with either parameter of oxygenation. SA significantly attenuated the PAP increase associated with continuous direct ascent to high altitude and appeared to uncouple PAP from both alveolar hypoxia and arterial hypoxemia.

Future directions in echocardiography.

Future developments in echocardiography will likely focus on the continued evolution of existing techniques, such as real-time 3-dimensional (RT3D) imaging and contrast-enhanced imaging; higher resolution imaging; and greater flexibility in imaging systems due to miniaturization, enhanced connectivity, and integration with other techniques. Improvements in RT3D image quality may include expanded parallel processing and use of transesophageal matrix arrays. Two areas of future clinical potential for contrast-enhanced echocardiography/ultrasound are the use of targeted microbubbles for diagnostic and therapeutic applications and expanded vascular imaging. Although molecular imaging holds great promise for the future, in the short-term, it is likely that contrast will be used more extensively for vascular imaging to assess both the effects of interventions on local perfusion and the activity of atherosclerotic plaque based on the size/density of the vasa vasorum. The widespread use of ultrasound will be facilitated by the development of a convenient portable or readily available ultrasonic equivalent of the stethoscope.

Mitral valve prolapse in Marfan syndrome: an old topic revisited.

BACKGROUND: The echocardiographic features of mitral valve prolapse (MVP) in Marfan syndrome have been well described, and the incidence of MVP in Marfan syndrome is reported to be 40-80%. However, most of the original research was performed in the late 1980s and early 1990s, when the diagnostic criteria for MVP were less specific. Our goal was to investigate the characteristics of MVP associated with Marfan syndrome using currently accepted diagnostic criteria for MVP. METHODS: Between January 1990 and March 2004, 90 patients with definitive diagnosis of Marfan syndrome (based on standardized criteria with or without genetic testing) were referred to Massachusetts General Hospital for transthoracic echocardiography. Patients' gender, age, weight, height, and body surface area at initial examination were recorded. Mitral valve thickness and motion, the degree of mitral regurgitation and aortic regurgitation, and aortic dimensions were quantified blinded to patients' clinical information. RESULTS: There were 25 patients (28%) with MVP, among whom 80% had symmetrical bileaflet MVP. Patients with MVP had thicker mitral leaflets (5.0 +/- 1.0 mm vs. 1.8 +/- 0.5 mm, P < 0.001), more mitral regurgitation (using a scale of 1-4, 2.2 +/- 1.0 vs. 0.90 +/- 0.60, P < 0.0001), larger LVEDD, and larger dimensions of sinus of Valsalva, sinotubular junction, aortic arch, and descending aorta indexed to square root body surface area, when compared with those without MVP. When echocardiographic features of patients younger than 18 years of age and those of patients older than 18 were compared, adult Marfan patients had larger LA dimension (indexed to square root body surface area), larger sinotubular junction (indexed to square root body surface area), and more mitral regurgitation and aortic regurgitation. CONCLUSIONS: The prevalence of MVP in Marfan syndrome is lower than previously reported. The large majority of patients with MVP have bileaflet involvement, and those with MVP have significantly larger aortic root diameters, suggesting a diffuse disease process.

Derivation of a size-independent variable for scaling of cardiac dimensions in a normal paediatric population.

AIMS: It is general practice to correct cardiac chamber size for body size by the process of scaling or normalization. Normalization is most commonly performed using simple linear or isometric correction; however, there is increasing evidence that this approach may be flawed. Likewise, there is little agreement concerning the appropriate scaling variable (measure of body size) for normalization. Therefore, we aimed to establish the optimal method for correcting the differences in body size in a large population of echocardiographically normal paediatric subjects. METHODS AND RESULTS: We compared the relative ability of standard size variables including height (HT), body weight (BW), body mass index (BMI), and body surface area (BSA), in both isometric and allometric models, to remove the effect of body size in 4109 consecutive echocardiographically normal subjects<18 years of age, using the left atrial dimension (LAD) as a reference standard. Simple linear normalization resulted in significant residual correlations (r=-0.57 to -0.92) of the indexed value with the body size variable, the correlations with weight (WT) and BSA actually increasing. In contrast, correction by the optimal allometric exponent (AE) removed the effects of the indexed variable (residual correlations -0.01 to 0.01), with BW and BSA best removing the effects of all the measures of body size. CONCLUSION: Conventional linear correction for body size is inaccurate in children and paradoxically increases the relationship of the indexed parameter with WT and BSA. Conversely, correction using the optimal AE removes the effect of that variable, with WT best correction for all measures of body size.

Estimation of radial strain and rotation using a new algorithm based on speckle tracking.

BACKGROUND: The aim of this study was to test the ability of a new algorithm to accurately measure point-to-point Lagrangian strain (LS) and local rotation (ROT). Change in distance between 2 separate regions of interest (ROIs) can theoretically be computed with speckle tracking (SpT) and used to calculate LS in any tissue location with angle independence and high spatial resolution. Similarly, tracking an ROI relative to a fixed point should provide an estimate of ROT. METHODS: Two dynamic phantoms (60 beats/min) were scanned in short axis at frame rates of 30, 60, and 90 Hz. To estimate LS, 2 ROIs were positioned immediately beneath the inner and outer borders of the superior wall of the first phantom and tracked using SpT. LS derived from SpT (SpT-LS) was compared with LS measured by sonomicrometers placed on the inner and outer walls of the phantom (SN-LS). To estimate ROT, the rotational vectors around the centroid of a second phantom were calculated for 3 epicardial bead targets imaged with gated computed tomography (CT) and compared with measurements derived from SpT. RESULTS: There was a significant correlation between SpT-LS and SN-LS at 30 Hz (R(2) = 0.99; P < .0001), 60 Hz (R(2) = 0.98; P < .0001), and 90 Hz (R(2) = 0.99; P < .0001). There was also a significant correlation between ROT derived from SpT and ROT derived from CT: R(2) = 0.97 (P < .0001) at 30 Hz, R(2) = 0.95 (P < .0001) at 60 Hz, and R(2) = 0.98 (P < .0001) at 90 Hz. CONCLUSIONS: Point-to-point SpT permits the determination of LS between 2 distinct tissue regions as well as ROT measurement of specific tissue regions without the need for border detection.