Can we evaluate the levator ani after Kegel exercise in women with pelvic organ prolapse by transperineal elastography? A preliminary study

Objectives

The aim of this study was to evaluate the stiffness variation of the levator ani in patients with stage I/II pelvic organ prolapse (POP) before and after Kegel exercises by transperineal elastography.

Methods

A total of 20 patients who were diagnosed with staged I/II POP underwent conventional transperineal ultrasound and elastography. For each patient, the levator ani was located and evaluated in the state of Valsalva. After Kegel exercises for 12 weeks, transperineal ultrasound and elastography were repeated. The elasticity images were assessed using a four-point scale scoring system.

Results

Of the 20 cases, four had an elastography score of 1, 14 had a score of 2, two had a score of 3, and no cases had a score of 4 in the levator ani before Kegel exercises. After Kegel exercises, one had an elastography score of 1, two had a score of 2, 15 had a score of 3, and two cases had a score of 4. The mean elastography score was statistically significantly higher for the levator ani after Kegel exercises (2.90 ± 0.48) than for the baseline score (1.90 ± 0.29) (p = 0.025).

Conclusions

Transperineal elastography was an effective and useful tool in the evaluation of the levator ani in patients with POP-Q stage I/II before and after Kegel exercises.

     

Synthetic aperture ultrasound imaging with a ring transducer array: preliminary ex vivo results

Purpose

The conventional medical ultrasound imaging has a low lateral spatial resolution, and the image quality depends on the depth of the imaging location. To overcome these problems, this study presents a synthetic aperture (SA) ultrasound imaging method using a ring transducer array.

Methods

An experimental ring transducer array imaging system was constructed. The array was composed of 2048 transducer elements, and had a diameter of 200 mm and an inter-element pitch of 0.325 mm. The imaging object was placed in the center of the ring transducer array, which was immersed in water. SA ultrasound imaging was then employed to scan the object and reconstruct the reflection image.

Results

Both wire phantom and ex vivo experiments were conducted. The proposed method was found to be capable of producing isotropic high-resolution images of the wire phantom. In addition, preliminary ex vivo experiments using porcine organs demonstrated the ability of the method to reconstruct high-quality images without any depth dependence.

Conclusion

The proposed ring transducer array and SA ultrasound imaging method were shown to be capable of producing isotropic high-resolution images whose quality was independent of depth.

     

Shear wave elastography of the spleen: evaluation of spleen stiffness in healthy volunteers

Purpose

The aim of this study was to assess the mean value of spleen stiffness measured by Shear wave elastography in healthy patients and its dependence on age, sex, and spleen dimensions, and to evaluate the repeatability of this method.

Methods

The final study group included 59 healthy volunteers without any clinical evidence of liver disease, portal hypertension, hematological disorders, and without any pathological ultrasonographic spleen findings. Each patient underwent abdominal ultrasound examination and elastography of the liver and the spleen.

Results

The mean value of spleen stiffness was 16.6 ± 2.5 kPa. In the group of men (N = 25), it was 17.3 ± 2.7 kPa, and in the group of women (N = 34), it was 16.1 ± 2.2 kPa. The study confirmed no correlation between spleen stiffness and sex, age of patients, and spleen size. Coefficient of repeatability and correlation coefficient between the results of the first and the second measurement showed good but not ideal repeatability of the measurement results.

Conclusion

Our outcomes may be a reference point for evaluating spleen stiffness in research on patients with various illnesses.

     

Basic study of less invasive high-intensity focused ultrasound (HIFU) in fetal therapy for twin reversed arterial perfusion (TRAP) sequence

Purpose

The objective of the present study was to develop a high-intensity focused ultrasound (HIFU) transducer more suitable for clinical use in fetal therapy for twin reversed arterial perfusion (TRAP) sequence.

Materials and methods

We created a cooling and degassed water-circulating-type HIFU treatment device. HIFU was applied to renal branch vessels in three rabbits. Sequential HIFU irradiation contains a trigger wave, heating wave, and rest time. The duration of HIFU application was 10 s/course. Targeting could be achieved by setting the imaging probe in the center and placing the HIFU beam and imaging ultrasonic wave on the same axis.

Result

We confirmed under sequential HIFU irradiation with a total intensity of 1.94 kW/cm² (spatial average temporal average intensity) that the vein and artery were occluded in all three rabbits.

Conclusion

Simultaneous occluding of the veins and arteries was confirmed with trigger waves and a resting phase using the HIFU transducer treatment device created for this study. Clinical application appears possible and may represent a promising option for fetal therapy involving TRAP sequence.

     

Shear wave elastography evaluation in pediatric testicular microlithiasis: a comparative study

Purpose

The aim of this study was to evaluate the testicular parenchyma in pediatric patients with testicular microlithiasis by shear wave elastography (SWE) and compare the values with normal control subjects.

Methods

Twenty-three patients previously diagnosed with testicular microlithiasis under follow-up for 20 ± 11 months were included in the study group. In the control group, 31 patients with no medical history that could affect testicular tissue were prospectively included. Forty-six testes in the study group and 62 testes in the control group were evaluated with gray-scale ultrasound and SWE.

Results

There were no differences in age and testes volume between the study and control groups. The mean SWE values of all testes based on elasticity and speed parameters in the study group were 8.84 ± 2.86 kPa and 1.66 ± 0.26 m/s, respectively. In the control group, mean SWE values were 5.26 ± 1.17 kPa and 1.31 ± 0.14 m/s, respectively. Elasticity values were significantly higher in testes with microlithiasis as compared with the control group (p < 0.001).

Conclusions

SWE evaluation demonstrates the effects of ultrastructural changes in elasticity that are not detected on gray-scale ultrasound. SWE is a more reliable method in follow-up examinations for pediatric testicular microlithiasis.

     

Measurement of sound pressure and temperature in tissue-mimicking material using an optical fiber Bragg grating sensor

Purpose

The experimental investigation of an optical fiber Bragg grating (FBG) sensor for biomedical application is described. The FBG sensor can be used to measure sound pressure and temperature rise simultaneously in biological tissues exposed to ultrasound. The theoretical maximum values that can be measured with the FBG sensor are 73.0 MPa and 30 °C.

Methods

In this study, measurement of sound pressure up to 5 MPa was performed at an ultrasound frequency of 2 MHz. A maximum temperature change of 6 °C was measured in a tissue-mimicking material.

Results

Values yielded by the FBG sensor agreed with those measured using a thermocouple and a hydrophone.

Conclusion

Since this sensor is used to monitor the sound pressure and temperature simultaneously, it can also be used for industrial applications, such as ultrasonic cleaning of semiconductors under controlled temperatures.

     

Changing use of noninvasive ventilation in critically ill patients: trends over 15 years in francophone countries

Purpose

Over the last two decades, noninvasive ventilation (NIV) has been proposed in various causes of acute respiratory failure (ARF) but some indications are debated. Current trends in NIV use are unknown.

Methods

Comparison of three multicenter prospective audits including all patients receiving mechanical ventilation and conducted in 1997, 2002, and 2011 in francophone countries.

Results

Among the 4132 patients enrolled, 2094 (51 %) required ventilatory support for ARF and 2038 (49 %) for non-respiratory conditions. Overall NIV use was markedly increased in 2010/11 compared to 1997 and 2002 (37 % of mechanically ventilated patients vs. 16 % and 28 %, P < 0.05). In 2010/11, the use of first-line NIV for ARF had reached a plateau (24 % vs. 16 % and 23 %, P < 0.05) whereas pre-ICU and post-extubation NIV had substantially increased (11 % vs. 4 % and 11 % vs. 7 %, respectively, P < 0.05). First-line NIV remained stable in acute-on-chronic RF, continued to increase in cardiogenic pulmonary edema, but decreased in de novo ARF (16 % in 2010/11 vs. 23 % in 2002, P < 0.05). The NIV success rate increased from 56 % in 2002 to 70 % in 2010/11 and remained the lowest in de novo ARF. NIV failure in de novo ARF was associated with increased mortality in 2002 but not in 2010/11. Mortality decreased over time, and overall, NIV use was associated with a lower mortality.

Conclusion

Increases in NIV use and success rate, an overall decrease in mortality, and a decrease of the adverse impact NIV failure has in de novo ARF suggest better patient selection and greater proficiency of staff in administering NIV.

Trial registration

Clinicaltrials.gov Identifier NCT01449331.

     

Diagnostic value of strain elastography for differentiation between renal cell carcinoma and transitional cell carcinoma of kidney

Purpose

The objective of our study was to prospectively evaluate the diagnostic performance of strain elastography for differentiation between renal cell carcinomas (RCCs) and transitional cell carcinomas (TCCs) of kidney.

Methods

A total of 99 consecutive patients who were referred to our hospital because of a newly diagnosed solid renal mass suspicious for malignancy on radiological screenings were evaluated with sonography, including strain elastography. Strain elastography was used to compare the stiffness of the renal masses and renal cortex. The ratio of strain in a renal mass and nearby renal cortex was defined as the strain index value. Mean strain index values for RCCs and TCCs were compared, and mean strain index values between histological subtypes of RCC were also compared.

Results

Although TCCs were smaller than RCCs (p < 0.001), there were no significant differences in gender distribution and mean age of the patients, and mean probe-tumor distance between RCC and TCC. The mean strain index value ±SD for TCC (5.18 ± 1.12) was significantly higher than the value for RCC (4.04 ± 0.72; p < 0.001). Mean strain index value for papillary cell carcinomas (4.09 ± 0.45) was slightly higher than that for clear cell carcinomas (3.85 ± 0.78): however, the difference was not statistically significant (p = 0.51).

Conclusions

Strain elastography can be used as a valuable imaging technique for preoperative differentiation between RCC and TCC of kidney.

     

Efficiency of quantitative echogenicity for investigating supraspinatus tendinopathy by the gray-level histogram of two ultrasound devices

Purpose

The gray-level histogram of ultrasound is a promising tool for scanning the hypoechogenic appearance of supraspinatus tendinopathy, and the aim of this study was to test the hypothesis that the gray-level value of the supraspinatus tendon in the painful shoulder has a lower value on B-mode images even though in different ultrasound devices.

Methods

Sixty-seven patients who had unilateral shoulder pain with rotator cuff tendinopathy underwent bilateral shoulder ultrasonography, and we compared the mean gray-level values of painful shoulders and contralateral shoulders without any pain in each patient using two ultrasound devices. The echogenicity ratio (symptomatic/asymptomatic side) of two ultrasound devices was compared.

Results

A significant difference existed between the symptomatic shoulder and contralateral asymptomatic shoulder (p < 0.001) on the mean gray-level value measurements of each device. The symptomatic-to-asymptomatic tendon echogenicity ratio of device A was 0.919 ± 0.090 in the transverse plane and 0.937 ± 0.081 in the longitudinal plane, and the echogenicity ratio of device B was 0.899 ± 0.113 in the transverse plane and 0.940 ± 0.113 in the longitudinal plane.

Conclusions

The decline of the mean gray-level value and the echogenicity ratio of the supraspinatus tendon in the painful shoulder may be utilized as a useful sonographic reference of unilateral rotator cuff lesions.

Level of evidence

Diagnostic level III.

     

Real-time ultrasound elastography of the Achilles tendon in patients with cerebral palsy: is there a correlation between strain ratio and biomechanical indicators?

Purpose

Our aim was to comparatively investigate the strain ratio and thickness of the Achilles tendon in children with cerebral palsy (CP), and to elucidate whether there is a correlation between biomechanical features of the Achilles tendon and strain ratio.

Methods

A total of 155 participants (72 CP patients and 83 healthy controls) who underwent real-time elastography of both Achilles tendons were studied. A linear transducer (4.8–11.0 MHz) was used to obtain the images. Correlation analysis between age, length, and thickness of the Achilles tendon, and strain ratio (SR) was performed by means of Pearson correlation and Spearman’s rho tests.

Results

Comparison of results obtained from CP patients and controls showed that the length of the Achilles tendon was shorter (p < 0.001) and SR was higher (p < 0.001) in CP patients. In CP patients, there was a positive correlation between SR and age and between SR and the thickness and length of the Achilles tendon (p < 0.001 for all). Furthermore, the length of the tendon and age were positively associated (p < 0.001). ROC analysis revealed that the cut-off value for SR was 1.89.

Conclusion

The results of the present study demonstrated that real-time elastography can constitute a simple, practical, and noninvasive method for evaluation of the elasticity of the Achilles tendon in children with CP.

     

Apoptotic and genotoxic effects of low-intensity ultrasound on healthy and leukemic human peripheral mononuclear blood cells

Purpose

To scrutinize the apoptotic and genotoxic effects of low-intensity ultrasound and an ultrasound contrast agent (SonoVue; Bracco Diagnostics Inc., EU) on human peripheral mononuclear blood cells (PMBCs).

Methods

PMBCs were subjected to a low-intensity ultrasound field (1-MHz frequency; spatial peak temporal average intensity 0.18 W/cm2) followed by analysis for apoptosis and DNA damage (single-strand breaks + double-strand breaks). The comet assay was then repeated after 2 h to examine the ability of cells to repair DNA breaks.

Results

The results demonstrated that low-intensity ultrasound was capable of selectively inducing apoptosis in leukemic PMBCs, but not in healthy cells. The introduction of ultrasound contrast agent SonoVue resulted in an increase in apoptosis in both groups. DNA analysis after ultrasound exposure indicated that ultrasound triggered DNA damage in leukemic PMBCs (66.05 ± 13.36%), while the damage was minimal (7.01 ± 0.89%) in control PMBCs. However, both cell lines demonstrated an ability to repair DNA single- and double-strand breaks 2 h after sonication.

Conclusions

The study demonstrated that low-intensity ultrasound selectively induced apoptosis in cancer PMBCs. Ultrasound-induced DNA damage was observed primarily in leukemic PMBCs. Nevertheless, both cell lines were able to repair ultrasound-mediated DNA strand breaks.

     

Lung ultrasonography for assessment of oxygenation response to prone position ventilation in ARDS

Purpose

Prone position (PP) improves oxygenation and outcome of acute respiratory distress syndrome (ARDS) patients with a PaO₂/FiO₂ ratio <150 mmHg. Regional changes in lung aeration can be assessed by lung ultrasound (LUS). Our aim was to predict the magnitude of oxygenation response after PP using bedside LUS.

Methods

We conducted a prospective multicenter study that included adult patients with severe and moderate ARDS. LUS data were collected at four time points: 1 h before (baseline) and 1 h after turning the patient to PP, 1 h before and 1 h after turning the patient back to the supine position. Regional lung aeration changes and ultrasound reaeration scores were assessed at each time. Overdistension was not assessed.

Results

Fifty-one patients were included. Oxygenation response after PP was not correlated with a specific LUS pattern. The patients with focal and non-focal ARDS showed no difference in global reaeration score. With regard to the entire PP session, the patients with non-focal ARDS had an improved aeration gain in the anterior areas. Oxygenation response was not associated with aeration changes. No difference in PaCO₂ change was found according to oxygenation response or lung morphology.

Conclusions

In ARDS patients with a PaO₂/FiO₂ ratio ≤150 mmHg, bedside LUS cannot predict oxygenation response after the first PP session. At the bedside, LUS enables monitoring of aeration changes during PP.

     

Distribution of lung ventilation in spontaneously breathing neonates lying in different body positions

Objective

The aim of our study was to determine the effect of the irregular spontaneous breathing pattern and posture on the spatial distribution of ventilation in neonates free from respiratory disease by the non-invasive imaging method of electrical impedance tomography (EIT). Scanning of spontaneously breathing neonates is the prerequisite for later routine application of EIT in babies with lung pathology undergoing ventilator therapy.

Design

Prospective study.

Setting

Neonatal intensive care unit at a university hospital.

Patients

Twelve pre-term and term neonates (mean age: 23 days; mean body weight: 2,465 g; mean gestational age: 34 weeks; mean birth weight: 2,040 g).

Interventions

Change in body position in the sequence: supine, right lateral, prone, supine.

Measurements and results

EIT measurements were performed using the Göttingen GoeMF I system. EIT scans of regional lung ventilation showing the distribution of respired air in the chest cross-section were generated during phases of rapid tidal breathing and deep breaths. During tidal breathing, 54.5±8.3%, 55.2±10.5%, 59.9±8.4% and 54.2±8.5% of inspired air (mean values ± SD) were directed into the right lung in the supine, right lateral, prone and repeated supine postures respectively. During deep inspirations, the right lung ventilation accounted for 52.6±7.9%, 68.5±8.5%, 55.4±8.2% and 50.5±6.6% of total ventilation respectively.

Conclusion

The study identified the significant effect of breathing pattern and posture on the spatial distribution of lung ventilation in spontaneously breathing neonates. The results demonstrate that changes in regional ventilation can easily be determined by EIT and bode well for the future use of this method in paediatric intensive care.

     

Quantitative assessment of thyroid gland elasticity with shear-wave elastography in pediatric patients with Hashimoto’s thyroiditis

Objective

Hashimoto’s thyroiditis is the most common autoimmune thyroid disorder in the pediatric age range. Measurement of thyroid gland size is an essential component in evaluation and follow-up of thyroid pathologies. Along with size, tissue elasticity is becoming a more commonly used parameter in evaluation of parenchyma in inflammatory diseases. The aim of the current study was to assess thyroid parenchyma elasticity by shear-wave elastography in pediatric patients with Hashimoto’s thyroiditis; and compare the elasticity values to a normal control group.

Materials and methods

In this study; thyroid glands of 59 patients with a diagnosis of Hashimoto’s thyroiditis based on ultrasonographic and biochemical features, and 26 healthy volunteers without autoimmune thyroid disease and thyroid function disorders, were evaluated with shear-wave elastography. Patients with Hashimoto thyroiditis were further subdivided into three categories based on gray-scale ultrasonography findings as focal thyroiditis (grade 1), diffuse thyroiditis (grade 2), and fibrotic thyroid gland (grade 3).

Results

Patients with Hashimoto’s thyroiditis (n = 59) had significantly higher elasticity values (14. 9 kPa; IQR 12.9–17.8 kPa) than control subjects (10.6 kPa; IQR 9.0–11.3 kPa) (p < 0.001). Of the 59 patients with Hashimoto’s thyroiditis, 23 patients had focal thyroiditis involving less than 50% of the gland categorized as grade 1, 24 patients had diffuse involvement of the thyroid gland categorized as grade 2, and 12 patients had marked hyperechoic septations and pseudonodular appearance categorized as grade 3 on gray-scale ultrasound. Based on elastography, grade 3 patients had significantly higher elasticity values (19.7 kPa; IQR 17.8–21.5 kPa) than patients with grade 2 (15.5 kPa; IQR 14.5–17.8 kPa) and grade 1 thyroiditis (12.8 kPa; IQR 11.9–13.1 kPa) (p < 0.05). Patients with grade 2 thyroiditis had significantly higher elasticity values than those with grade 1 thyroiditis (p < 0.05).

Conclusion

Gray-scale ultrasound findings of heterogeneous echotexture and hypoechoic echogenicity reflect a longer duration of inflammation and may not be found in the initial stages of thyroiditis. Our results indicate that shear-wave elastography could be used to evaluate the degree of fibrosis in Hashimoto’s thyroiditis.

     

Effects of mannitol alone and mannitol plus furosemide on renal oxygen consumption,blood flow and glomerular filtration after cardiac surgery

Objective

Imbalance of the renal medullary oxygen supply/demand relationship can cause hypoxic medullary damage and ischaemic acute renal failure (ARF). The use of mannitol for prophylaxis/treatment of clinical ischaemic ARF is controversial and the effect of mannitol on renal oxygenation in man has not yet been investigated. We evaluated the effects of mannitol on renal oxygen consumption (RVO₂)_, renal blood flow (RBF) and glomerular filtration rate (GFR) in postoperative patients.

Design

Prospective interventional study.

Setting

University hospital cardiothoracic ICU.

Patients

Ten uncomplicated mechanically ventilated and sedated postcardiac surgery patients with preoperatively normal renal function.

Interventions

Mannitol infusion (225 mg/kg + 75 mg/kg/h) and combined mannitol and furosemide infusion (0.25 mg/kg + 0.25 mg/kg/h).

Measurements and results

Systemic haemodynamics were evaluated by a pulmonary artery catheter. RBF and GFR were measured by the renal vein thermodilution technique and by renal extraction of ⁵¹Cr–EDTA, respectively. Mannitol increased urine flow (60%), GFR (20%) and filtration fraction (FF) (20%) with no change in RBF. This was accompanied by an increase in renal sodium reabsorption (18%), RVO₂ (19%) and renal oxygen extraction (21%). When combined with mannitol, furosemide normalised sodium reabsorption, RVO₂, renal oxygen extraction with no change in RBF, while GFR and FF were still elevated compared to control.

Conclusions

In patients with normal renal function, mannitol increases GFR, which increases tubular sodium load, sodium reabsorption and RVO₂ after cardiac surgery. The lack of effect on RBF, indicates that mannitol impairs the renal oxygen supply/demand relationship. Furosemide normalised renal oxygenation when combined with mannitol.

     

Value of in vitro acoustic radiation force impulse application on uterine adenomyosis

Purpose

Adenomyosis is the presence of endometrial glandular and stromal tissue in the myometrium. This phenomenon can be the cause of excessive bleeding and menstrual pain in premenopausal women. Diagnosis of adenomyosis may present difficulty with conventional methods such as ultrasound and magnetic resonance imaging. Frequently, diagnosis is accomplished retrospectively based on the hysterectomy specimen.

Materials and methods

This is a prospective case control study done in vitro on 90 patients’ hysterectomy specimens. Acoustic radiation force impulse (ARFI) and color elastography were used to determine the elasticity of hysterectomy specimens of patients undergoing indicated surgeries. Based on histopathological examinations, two groups were formed: a study group (n = 28—with adenomyosis) and a control group (n = 62—without adenomyosis).

Results

Elasticity measurements of tissue with adenomyosis were observed to be significantly higher than measurements of normal myometrial tissue (p < 0.01). Uterine fibroids were found to have higher values on ARFI study compared to normal myometrial tissues (p < 0.01).

Conclusion

The findings lead to the conclusion that adenomyosis tissue is significantly softer than the normal myometrium. ARFI was found to be beneficial in differentiating myometrial tissue with adenomyosis from normal myometrial tissue. It was found to be feasible and beneficial to implement ARFI in daily gynecology practice for diagnosis of adenomyosis.

     

Intraoperative Molecular Imaging of Lung Adenocarcinoma Can Identify Residual Tumor Cells at the Surgical Margins

Purpose

During lung surgery, identification of surgical margins is challenging. We hypothesized that molecular imaging with a fluorescent probe to pulmonary adenocarcinomas could enhance residual tumor during resection.

Procedures

Mice with flank tumors received a contrast agent targeting folate receptor alpha. Optimal dose and time of injection was established. Margin detection was compared using traditional methods versus molecular imaging. A pilot study was then performed in three humans with lung adenocarcinoma.

Results

The peak tumor-to-background ratio (TBR) of murine tumors was 3.9. Fluorescence peaked at 2 h and was not improved beyond 0.1 mg/kg. Traditional inspection identified 30 % of mice with positive margins. Molecular imaging identified an additional 50 % of residual tumor deposits (p?<?0.05). The fluorescent probe visually enhanced all human tumors with a mean TBR of 3.5.

Conclusions

Molecular imaging is an important adjunct to traditional inspection to identify surgical margins after tumor resection.

     

Robotic ultrasound-guided SBRT of the prostate: feasibility with respect to plan quality

Purpose

Advances in radiation therapy delivery systems have enabled motion compensated SBRT of the prostate. A remaining challenge is the integration of fast, non-ionizing volumetric imaging. Recently, robotic ultrasound has been proposed as an intra-fraction image modality. We study the impact of integrating a light-weight robotic arm carrying an ultrasound probe with the CyberKnife system. Particularly, we analyze the effect of different robot poses on the plan quality.

Methods

A method to detect the collision of beams with the robot or the transducer was developed and integrated into our treatment planning system. A safety margin accounts for beam motion and uncertainties. Using strict dose bounds and the objective to maximize target coverage, we generated a total of 7650 treatment plans for five different prostate cases. For each case, ten different poses of the ultrasound robot and transducer were considered. The effect of different sets of beam source positions and different motion margins ranging from 5 to 50 mm was analyzed.

Results

Compared to reference plans without the ultrasound robot, the coverage typically drops for all poses. Depending on the patient, the robot pose, and the motion margin, the reduction in coverage may be up to 50 % points. However, for all patient cases, there exist poses for which the loss in coverage was below 1 % point for motion margins of up to 20 mm. In general, there is a positive correlation between the number of treatment beams and the coverage.

Conclusion

While the blocking of beam directions has a negative effect on the plan quality, the results indicate that a careful choice of the ultrasound robot’s pose and a large solid angle covered by beam starting positions can offset this effect. Identifying robot poses that yield acceptable plan quality and allow for intra-fraction ultrasound image guidance, therefore, appears feasible.

     

Auto strain ratio system for the quality control of breast strain elastography

Purpose

To determine the reproducibility, accuracy, and quantitative values of the auto strain ratio system (ASRS)—a newly developed strain elastography-based program.

Materials and methods

First, the accuracy of ASRS was verified using a breast phantom. A prospective clinical study was then performed in patients. Two hundred and one women (mean age 52.4 years ± SD 14.5) with 232 breast lesions (177 benign and 55 malignant) were enrolled in this study. We assessed the correlation between ASRS and manual strain ratio (MSR), calculating the diagnostic performance to determine the cut-off. The area under the receiver operating characteristic curve (AUC) was calculated.

Results

ASRS was strongly correlated with the subtle differences in phantom stiffness (R = 0.87). In the clinical study, there was a significant correlation between MSR and ASRS with R = 0.79 (P < 0.001). ASRS (cut-off = 3.9) had a sensitivity of 81.8%, specificity of 88.7%, accuracy of 87.1%, positive predictive value of 69.2%, and negative predictive value of 94%. The AUC of ASRS was 0.89.

Conclusion

The findings from this study have demonstrated that it is possible to quantify strain elastography and control its accuracy. ASRS is expected to contribute to the standardization of breast elastography.

     

Laboratory test of Single Landmark registration method for ultrasound-based navigation in laparoscopy using an open-source platform

Purpose

Test the feasibility of the novel Single Landmark image-to-patient registration method for use in the operating room for future clinical trials. The algorithm is implemented in the open-source platform CustusX, a computer-aided intervention research platform dedicated to intraoperative navigation and ultrasound, with an interface for laparoscopic ultrasound probes.

Methods

The Single Landmark method is compared to fiducial landmark on an IOUSFAN (Kyoto Kagaku Co., Ltd., Japan) soft tissue abdominal phantom and T2 magnetic resonance scans of it.

Results

The experiments show that the accuracy of the Single Landmark registration is good close to the registered point, increasing with the distance from this point (12.4 mm error at 60 mm away from the registered point). In this point, the registration accuracy is mainly dominated by the accuracy of the user when clicking on the ultrasound image. In the presented set-up, the time required to perform the Single Landmark registration is 40% less than for the FLRM.

Conclusion

The Single Landmark registration is suitable for being integrated in a laparoscopic workflow. The statistical analysis shows robustness against translational displacements of the patient and improvements in terms of time. The proposed method allows the clinician to accurately register lesions intraoperatively by clicking on these in the ultrasound image provided by the ultrasound transducer. The Single Landmark registration method can be further combined with other more accurate registration approaches improving the registration at relevant points defined by the clinicians.