Surgery: kinesitherapy – Kinesitherapy – Ultrasonic
Reexamination Certificate
2000-11-22
2003-09-30
Lateef, Marvin M. (Department: 3737)
Surgery: kinesitherapy
Kinesitherapy
Ultrasonic
C600S439000, C600S442000, C601S002000
Reexamination Certificate
active
06626855
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to methods and apparatus for efficiently heating biological tissues with high intensity ultrasound for therapeutic purposes, and in particular, to endoscopic devices for applying ultrasound energy to uterine fibroids and other pathologic tissues that are inside body or organ cavities, to destroy the tumor or the diseased tissue.
BACKGROUND OF THE INVENTION
Fibroids are benign tumors in women's uteri. There are different types of fibroids, including submucosal, which are inside the uterine cavity; intramural, which are in the uterine wall; and subserosal, which are outside the uterus. Fibroids may cause excessive bleeding and pain. For symptomatic fibroids, surgery is the predominate treatment. Every year in the U.S., there are more than 200,000 cases of fibroid-caused hysterectomies. To preserve the uterus, the patient may choose myomectomy, which removes the fibroids only. There are more than 80,000 abdominal myomectomies each year in the U.S. These surgical procedures cause significant trauma to the patients and result in significant costs. Consequently, patients need several days of hospital stay and suffer from the prolonged recovery.
Minimally invasive surgical (MIS) procedures have been explored to treat uterine fibroid trans-abdominally or trans-cervically under laparoscopic or hysteroscopic guidance. Many MIS apparatus have been developed to make the procedure less difficult. Several prior art devices are described in U.S. Pat. No. 5,304,124; U.S. Pat. No. 5,662,680; and U.S. Pat. No. 5,709,679. Besides surgically resecting and removing the tumor tissue, alternative treatments include using different energy forms, such as laser, radio frequency (RF), and cryo-therapy, to thermally ablate or necrose the fibroid tissue. Most of these techniques require the insertion of needles or other types of devices into the body of the fibroid. The mechanical damage to the fibroid and the uterus can cause bleeding during the treatment and adhesions after the treatment. Suturing the damage in the uterus is very difficult in the laparoscopic MIS procedure. Also, most of these alternative treatments are time consuming and technically challenging.
Uterine arterial embolization (UAE) has been investigated as an alternative treatment for uterine fibroids. In UAE, a catheter is inserted into the patient's femoral artery. The catheter is then advanced until its tip reaches the uterine artery. Many small particles are then injected into the uterine artery to block the blood flow. Both left and right uterine arteries are treated. Blood vessels supplying uterine fibroids are typically larger than the vessels in the normal uterine tissue. With properly sized particles, the blood vessels feeding the uterine fibroids are embolized, but not those in the normal uterine tissue. The fibroids then starve and die due to lack of a blood supply. The uterus survives, however, on the blood supplied from the ovarian artery and other collateral circulation. The embolization procedure may cause severe pain in the first few days after the treatment. Other disadvantages of UAE may include long X-ray radiation exposure during the procedure and other long-term potential adverse effects. The procedure is not recommended if the patient seeks a future pregnancy.
Ultrasound is a term that refers to acoustic waves having a frequency above the high limit of the human audible range (i.e., above 20 KHz). Ultrasound waves have the capability of penetrating into the human body. Based on this property, ultrasound in the frequency range of 2-20 MHz has been widely used to image internal human organs for diagnostic purposes. Ultrasound imaging has also been suggested as a tool for guidance during a resectoscopic surgery (U.S. Pat. No. 5,957,849).
When ultrasound energy is absorbed by tissue, it becomes thermal energy, raising the temperature of the tissue. To avoid thermal damage to tissue, the power level in diagnostic ultrasound imaging is kept very low. The typical ultrasound intensity (power per unit area) used in imaging is less than 0.1 watt per square centimeter. High intensity focused ultrasound, which can have an intensity above 1000 watts per square centimeter, can raise the tissue temperature at the region of the spatial focus to above 60-80 degrees Celsius in a few seconds and can cause tissue necrosis almost instantaneously.
High intensity ultrasound has been proposed to treat and destroy tissues in the liver (G. ter Haar, “Ultrasound Focal Beam Surgery,” Ultrasound in Medicine and Biology, Vol. 21, No. 9, pp.1089-1100, 1995); in the prostate (N. T. Sanghvi and R. H. Hawes, “High-intensity Focused Ultrasound,” Experimental and Investigational Endoscopy, Vol. 4, No. 2, pp.383-395, 1994); and in other organs. In U.S. Pat. Nos. 5,080,101, 5,080,102, 5,735,796, 5,769,790, and 5,788,636, for example, ultrasound imaging is combined with a high intensity ultrasound treatment to target the treatment region and to monitor the treatment process. In U.S. Pat. Nos. 5,471,988, 5,492,126, 5,666,954, 5,697,897, and 5,873,828, endoscopic ultrasound devices with both imaging and therapeutic capabilities are disclosed. These devices all have an elongated tube or shaft, so that they can be inserted in organ cavities (e.g., into the rectum) or into the abdominal cavity through a puncture hole in the abdominal wall to bring the ultrasound imaging and treatment sources closer to the disease sites. Some of them have flexible ends, which can be bent to fit the anatomy of a specific patient.
The therapeutic ultrasound beam is focused inside tissue to a small spot of a few millimeters in size. At the focus, tissue temperature rapidly exceeds a level sufficient to cause tissue necrosis, thus achieving the desired therapeutic effect. Outside of the focus, ultrasound energy is less concentrated, tissue temperature rise remains below the necrosis level during the typically short exposure times employed. To treat a tissue volume larger than the focal spot, in the prior art, the ultrasound focus is deflected mechanically or electronically to scan, or incrementally expose, the target tissue volume. One disadvantage of the current high intensity ultrasound therapy is its inefficiency when treating large tumors or heating a large volume of tissue. Even though a three-second ultrasound pulse can increase the temperature of tissue at its focus dramatically, the ultrasound treatment must typically pause 40-60 seconds between two subsequent pulses to allow the intermediate tissue between the focus and the ultrasound transducer to cool sufficiently to avoid thermally damaging the tissue. The volume of tissue necrosis for each treatment pulse is very small (~0.05 cm
3
). For example, to treat a volume of tissue within a 3 cm diameter sphere, it will take more than 4 hours, too long to be practical in most clinical situations. Many symptomatic uterine fibroids are larger than 2-3 cm in diameter, and multiple fibroids are also common. To be acceptable for clinicians and patients, the ultrasound treatment time must be significantly reduced.
Large device size is the second disadvantage of the therapeutic ultrasound apparatus in much of the prior art. Most of these devices have two separated ultrasound transducers, including one for imaging and the other for therapy. For effective treatment, the diameter of the treatment transducer is approximately equal to the maximum depth, where the f-number (transducer diameter divided by its focal length) of the transducer is about one (f/1). The transducer surface area must also be sufficiently large to generate high ultrasound power. In some prior art endoscopic devices (for example, in U.S. Pat. Nos. 5,471,988 and 5,873,828), there is a large orifice in the center of the therapy transducer for positioning an imaging transducer. This orifice reduces the area of the treatment transducer and increases its effective f-number. In this case, the size of the treatment transducer must be increased to maintain its effectiveness, so that the overall dimensions o
Perozek David M.
Weng Lee
Zhang Jimin
Lateef Marvin M.
Qaderi Runa Shoh
Therus Corpoation
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