Streaming detection for evaluation of indeterminate sonographic breast masses: a pilot study.

OBJECTIVE: Streaming detection is a novel sonography technique that uses ultrasonic energy to induce movement in cyst fluid that is detected on Doppler sonography. This pilot study evaluates the utility of streaming detection for differentiating cysts from solid masses in breast lesions that are indeterminate on sonography. SUBJECTS AND METHODS: Thirty-nine lesions-11 simple cysts and seven solid masses (control group) and 21 masses with indeterminate findings for the diagnosis of a cyst versus a solid lesion (study group)-in 34 patients were evaluated using streaming detection. All lesions underwent cyst aspiration or biopsy (n = 35) or were diagnosed simple cysts (n = 4) on sonography. Lesion size and depth were recorded. Streaming detection software was placed on conventional sonography units. Acoustic pulses were focused on the lesion, and if fluid movement was generated, it was seen on the spectral Doppler display as velocity away from the transducer. Lesions were then aspirated or underwent biopsy, and the viscosity of the aspirated fluid was recorded. The sensitivity and specificity of the technique and the effect of cyst size, cyst depth, and fluid viscosity in diagnosing fluid-filled cysts were assessed. RESULTS: Overall, 31 cysts and eight solid masses (seven benign, one carcinoma) were diagnosed in the study and control groups. Aspiration of indeterminate lesions resulted in 20 cysts and one solid mass. Lesions ranged in size from 4 to 47 mm and in depth from 4 to 29 mm. In the control group, streaming detection correctly showed nine of the 11 simple cysts (sensitivity, 82%; positive predictive value, 100%), and acoustic streaming was absent in all seven solid masses (specificity, 100%; negative predictive value, 78%). Of the indeterminate lesions, streaming detection allowed correct identification of 10 of 20 cysts (sensitivity, 50%; positive predictive value, 100%). Acoustic streaming was not detected in the one solid study group lesion. Neither cyst size or depth nor fluid viscosity had a significant effect on the ability to detect fluid. CONCLUSION: The streaming detection technique improved differentiation of cysts from solid masses in indeterminate lesions and has potential for reducing the number of recommended cyst aspirations for the diagnosis of indeterminate breast masses.

Deep bleeder acoustic coagulation (DBAC)-Part I: development and in vitro testing of a research prototype cuff system.

BACKGROUND: Bleeding from limb injuries is a leading cause of death on the battlefield, with deep wounds being least accessible. High-intensity focused ultrasound (HIFU) has been shown capable of coagulation of bleeding (cautery). This paper describes the development and refereed in vitro evaluation of an ultrasound (US) research prototype deep bleeder acoustic coagulation (DBAC) cuff system for evaluating the potential of DBAC in the battlefield. The device had to meet quantitative performance metrics on automated operation, therapeutic heating, bleeder detection, targeting accuracy, operational time limits, and cuff weight over a range of limb sizes and bleeder depths. These metrics drove innovative approaches in image segmentation, bleeder detection, therapy transducers, beam targeting, and dose monitoring. A companion (Part II) paper discusses the in vivo performance testing of an animal-specific DBAC system. MATERIALS AND METHODS: The cuff system employed 3D US imaging probes ("Ix") for detection and localization (D&L) and targeting, with the bleeders being identified by automated spectral Doppler analysis of flow waveforms. Unique high-element-count therapeutic arrays ("Tx") were developed, with the final cuff prototype having 21 Tx's and 6 Ix's. Spatial registration of Ix's and Tx's was done with a combination of image-registration, acoustic time-of-flight measurement, and tracking of the cuff shape via a fiber optic sensor. Acoustic radiation force impulse (ARFI) imaging or thermal strain imaging (TSI) at low-power doses were used to track the HIFU foci in closed-loop targeting. Recurrent neural network (RNN) acoustic thermometry guided closed-loop dosing. The cuff was tested on three phantom "limb" sizes: diameters = 25, 15, and 7.5 cm, with bleeder depths from 3.75 to 12.5 cm. "Integrated Phantoms" (IntP) were used for assessing D&L, closed-loop targeting, and closed-loop dosing. IntPs had surrogate arteries and bleeders, with blood-mimicking fluids moved by a pulsatile pump, and thermocouples (TCs) on the bleeders. Acoustic dosing was developed and tested using "HIFU Phantoms" having precisely located TCs, with end-of-dose target ∆T = 33-58 °C, and skin temperature ∆T ≤ 20 °C, being required. RESULTS: Most DBAC cuff performance requirements were met, including cuff weight, power delivery, targeting accuracy, skin temperature limit, and autonomous operation. The automated D&L completed in 9 of 15 tests (65 %), detecting the smallest (0.6 mm) bleeders, but it had difficulty with the lowest flow (3 cm/sec) bleeders, and in localizing bleeders in the smallest (7.5 cm) phantoms. D&L did not complete within the 9-min limit (results ranged 10-21 min). Closed-loop targeting converged in 20 of 31 tests (71 %), and closed-loop dosing power shut-off at preset ∆Ts was operational. SUMMARY AND CONCLUSION: The main performance objectives of the prototype DBAC cuff were met, however the designs required a number of challenging new technology developments. The novel Tx arrays exhibited high power with significant beam steering and focusing flexibility, while their integrated electronics enabled the required compact, lightweight configurability and simplified driving controls and cable/connector architecture. The compounded 3D imaging, combined with sophisticated software algorithms, enabled automated D&L and initial targeting and closed-loop targeting feedback via TSI. The development of RNN acoustic thermometry made possible feedback-controlled dosing. The lightweight architecture required significant design and fabrication effort to meet mechanical functionalities. Although not all target specifications were met, future engineering solutions addressing these performance deficiencies are proposed. Lastly, the program required very complex limb test phantoms and, while very challenging to develop, they performed well.