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US-12622679-B2 - Tactile ultrasound method and probe for predicting spontaneous preterm birth

US12622679B2US 12622679 B2US12622679 B2US 12622679B2US-12622679-B2

Abstract

A cervical probe, equipped with both a tactile sensor array and an ultrasound transducer array, is engineered for the simultaneous acquisition of stress and ultrasound strain data from cervical sectors, as well as for the measurement of cervical length. The collected stress and strain data from various cervical sectors are transmitted to a data processor. This processor calculates cervical elasticity using a strain-to-stress ratio. Subsequently, the arithmetic mean of the stress-to-strain ratios is compared with a predetermined cutoff value, and the measured cervical length is evaluated against another predetermined value, to predict preterm birth during gestational weeks 24-28.

Inventors

  • Vladimir Egorov

Assignees

  • Vladimir Egorov

Dates

Publication Date
20260512
Application Date
20230920

Claims (14)

  1. 1 . A method for predicting spontaneous preterm birth, the method comprising the steps of: a) providing a cervix probe with a head equipped with a plurality of tactile sensors and an array of ultrasound transducers having a curved anterior contact surface, said head positioned at an angle to a probe shaft, thereby said probe is configured for a side contact with a cervical anterior surface of a subject such that, when the probe shaft is inserted into a vagina beside a cervix, the curved anterior contact surface is substantially parallel to a longitudinal axis of a cervical canal and configured for side contact with the cervical anterior surface from one lateral side thereof across the cervical canal, b) inserting said cervix probe into the vagina to contact said cervix anterior surface from one side thereof across the cervical canal, c) using said cervix probe to deform said cervix surface from one side thereof and across the cervical canal while simultaneously acquiring cervix surface stress data via said tactile sensors and strain data from B-mode ultrasound images of said cervix, d) calculating cervix elasticity as a stress-to-strain ratio and cervix length using said cervix stress data and said ultrasound images of said cervix, and e) comparing said stress-to-strain ratio and said cervical length with a respective predetermined stress-to-strain ratio cutoff value and a predetermined cervical length cutoff value to predict spontaneous preterm birth.
  2. 2 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein in step (a) said head positioned at said angle of 130 degrees to the probe shaft.
  3. 3 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein in step (e) said predetermined stress-to-strain ratio cutoff value is at least 1.1 kPa/mm.
  4. 4 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein in step (e) said predetermined cervical length cutoff value is at least 22 mm.
  5. 5 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein said step (d) further comprising a step of calculating cervix length from the B-mode ultrasound cervical image.
  6. 6 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein said steps (c) and (d) are conducted for more than one cervical sector and an arithmetic mean stress-to-strain ratio is calculated for all applied cervical sectors.
  7. 7 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein said steps (b) through (e) are performed on a pregnant woman at 24-28 weeks of pregnancy.
  8. 8 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein the step (d) of calculating cervix elasticity further comprising calculating Young's modulus based on a semi-infinitive linear elastic model of the cervix.
  9. 9 . The method for predicting spontaneous preterm birth, as in claim 1 , wherein the step (d) of calculating cervix elasticity further comprising calculating Young's modulus based on a finite element modeling of cervix deformation.
  10. 10 . The method for predicting spontaneous preterm birth, as in claim 6 , wherein said applied cervical sectors are an anterior cervical sector and a posterior cervical sector.
  11. 11 . A probe for predicting spontaneous preterm birth, said probe comprising: a head equipped with a plurality of front-facing tactile sensors and a front-facing array of ultrasound transducers having a curved anterior contact surface, said head is positioned at an angle to a probe shaft, thereby said probe is configured for contact of the curved anterior contact surface carrying the front-facing plurality of tactile sensors and the front-facing array of ultrasound transducers with a cervical anterior surface to facilitate deformation of said cervical anterior surface from one lateral side thereof and across a cervical canal with the curved anterior contact surface being substantially parallel to a longitudinal axis of the cervical canal, said plurality of tactile sensors forming together a pressure sensor array configured to acquire cervix surface stress data and located over at least a portion of said head, said ultrasound transducers of the array of ultrasound transducers are positioned adjacent to said plurality of tactile sensors on said head, the ultrasound transducers are configured to emit an ultrasound pulse and to acquire a scattered ultrasound waveforms from said cervix anterior surface for a B-mode ultrasound imaging during cervix deformation by said probe, a control unit operably connected to said tactile sensor array for acquiring said stress data and said ultrasound transducers for acquiring said scattered ultrasound waveforms, and a data processor operably connected to said control unit and configured for calculating cervix elastic as a stress-to-strain ratio and cervix length using said stress data and said ultrasound waveforms which are used to create the B-mode ultrasound image, and said data processor is further configured to compare the stress-to-strain ratio and cervical length with a respective predetermined stress-to-strain ratio cutoff value and a predetermined cervical length cutoff value to predict spontaneous preterm birth.
  12. 12 . The probe, as in claim 11 , wherein said head further comprises an elastic layer covering said tactile sensor array and said ultrasound transducers to allow reversible stress transmission therethrough and multiple disinfections of said probe.
  13. 13 . The probe, as in claim 11 , wherein said ultrasound transducers are made using a piezoceramic composite material with a mylar film with a predetermined thickness as an acoustic matching layer.
  14. 14 . The probe, as in claim 11 , wherein said ultrasound transducers have an elastic backing layer to allow attenuation of acoustic backscattering from a support base housing thereof.

Description

CROSS-REFERENCE DATA This US patent application is a continuation-in-part of a U.S. patent application Ser. No. 18/144,752 filed 8 May 2023 by the same inventor and entitled TACTILE ULTRASOUND METHOD AND PROBE FOR PREDICTING PRETERM BIRTH, which in turn is a continuation in part of a U.S. patent application Ser. No. 16/574,270 filed 18 Sep. 2019 by the same inventor and entitled METHOD AND PROBE FOR PREDICTING SPONTANEOUS PRETERM DELIVERY, which is a continuation-in-part of the U.S. patent application Ser. No. 15/249,672 filed Aug. 29, 2016, by the same inventor with the title “METHODS AND PROBES FOR VAGINAL TACTILE AND ULTRASOUND IMAGING,” which in turn claims a priority benefit from a U.S. Provisional Patent Application No. 62/215,227 filed 8 Sep. 2015 with the same title. All cited patent documents are incorporated herein in their respective entireties by reference. GOVERNMENT-SUPPORTED RESEARCH This invention was made with US Government support under grant No. HD109075 awarded by the National Institutes of Health. The government has certain rights in this invention. FIELD OF THE INVENTION The present invention generally relates to cervix imaging and characterization of pregnant women. Specifically, the invention describes methods and devices for detecting conditions leading to spontaneous preterm birth. BACKGROUND Preterm birth is a leading global cause of neonatal mortality despite intensive research and numerous advances in perinatal medicine. Almost 1 million children die each year due to complications of preterm birth. In almost all countries that have reliable data, preterm birth rates are increasing. Of the 14 million survivors per year, many face a lifetime of disability, including learning disabilities, visual and hearing impairments. The morbidities include respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, sepsis, and retinopathy of prematurity. Long-term complications include cognitive disorders, behavioral problems, and cerebral palsy. These consequences imply devastating financial, social, and emotional effects on the parents or the affected children. In 2021, preterm birth affected about 1 of every 10 infants born in the United States. The preterm birth rate rose 4% in 2021, from 10.1% in 2020 to 10.5% in 2021, according to the data collected by the Centers for Disease Control and Prevention. A preterm birth is defined by the World Health Organization as a birth before 37 completed weeks of gestation or fewer than 259 days since the first day of a woman's last menstrual period. Preterm births occur for a variety of reasons. Most preterm births happen spontaneously. Common causes of a spontaneous preterm birth (sPTB) include multiple pregnancies, infections, chronic conditions, lifestyle, family history, and cervical incompetence. However, often no single cause is identified. Although sPTB is often a multifactorial event, precocious cervical softening, shortening, and dilatation are a common denominator. Clinical risk factors for sPTB include obstetric history (familial genetic predisposition, uterine malformation, previous preterm labor, previous cervical surgery) and other aspects of the current pregnancy (multifetal gestation, genital tract bleeding and/or infection, fetal malformation, preterm rupture of membranes, shortened cervix, and other pregnancy complications including preeclampsia and gestational diabetes mellitus). A previous preterm birth before 34 weeks gestation is one of the strongest risk factors for subsequent preterm birth. However, insofar as nulliparous women have no past obstetric history to call upon, any such previous history risk factor-based assessment is not applicable in their situation. The sPTB risk factors assessment alone is unreliable. Extensive cervical remodeling is needed for the cervix to dilate and pass a fetus fully. While human parturition is not completely understood, it is a complex system that involves interactions between placental, fetal, and maternal mechanisms. The extracellular matrix of the cervix is primarily made up of tightly packed collagen bundles. Gradually, throughout the pregnancy, the composition of the cervix changes as the collagen density decreases, in addition to realignment and degradation of collagen cross-linking due to proteolytic enzymes, and an increase in the hyaluronic acid and water content. Further, through a cascade of events, inflammatory mediators increase the production of prostaglandins. Prostaglandins invading the cervix mediate the release of metalloproteases that further break down collagen and change the cervical structure. Cervical softening and distention result from these extracellular matrix compositional changes, specifically, increased vascularity and stromal and glandular hypertrophy, and are due, in part, to an increase in collagen solubility closer to birth. The cervical elasticity assessment currently used i