CT Scan MRI and LASER in GYNECOLOGY: CT Scan MRI and LASER in GYNECOLOGY Dr Geeta J.Doppa Assoc prof KVG Medical College Sullia D.K. CT SCAN : CT SCAN CT scan discovered independently by a British engineer named Sir Godfrey Hounsfield and Dr. Alan Cormack.nobel prize in 1979 Computerised axial tomography scan (CAT SACN) Difference in x-ray beam attentuation that results from different densities in adjacent tissues can visualize abnormal massess but definitive pathologic diagnosis is only with surgical biopsy. CT scan is more expensive than ultrasound. Types of CT scan: Types of CT scan Conventional Contrast CT scan Spiral CT scan A narrow slice width is used (usually 1–2 mm) A high spatial resolution image reconstruction algorithm is used Field of view is minimized, so as to minimize the size of each pixel Principle: Principle Takes x-ray images at many different angles around the body Processed by a computer to produce cross-sectional pictures of the body In each of these pictures the body is as an x-ray "slice" of the body-TOMOGRAM. Slice of bread added" together, a 3D picture of an organ or abnormal body structure can be obtained. Reading films: Reading films Dark (black) areas will generally refer to fluid Bright (white) masses suggest foreign tissue or other implant. PowerPoint Presentation: Attenuation coefficient Windowing PowerPoint Presentation: Artifact motion and metal artifact (self-explanatory), beam hardening volume averaging. Indications: Indications To detect pituitary tumor. To detect ovarian tumor. To determine the cancer of genital tract. To detect the staging of cancer cervix. To determine myometrial involvement in endometrial cancer. To detect para -aortic nodes and obtain needle biopsy to determine retroperitoneal spread of cancer. To determine the spread of ovarian cancer. To detect intraabdominal abscess and hematoma. To diagnose pelivc vein thrombophlebitis. Both adenomas and metastases are hyperdense compared to brain, often with a mottled appearance, which is thought to represent areas of cystic degeneration or necrosis. Both lesions usually enhance homogeneously with the administration of intravenous contrast material (10,27).: Both adenomas and metastases are hyperdense compared to brain, often with a mottled appearance, which is thought to represent areas of cystic degeneration or necrosis. Both lesions usually enhance homogeneously with the administration of intravenous contrast material (10,27). Complications : Complications Radiation Reaction to the contrast severe allergic reaction high risk asthma emphysema, severe heart disease Contrast leaks rash/necrosis MRI SCAN : MRI SCAN Basic principle: Basic principle powerful magnetic field to align the magnetization of some atoms in the body, and radio frequency fields to systematically alter the alignment of this magnetization Physics of Magnetic Resonance Imaging: Physics of Magnetic Resonance Imaging Strong electromagnetic field: Strong electromagnetic field PowerPoint Presentation: When a person is inside the powerful magnetic field of the scanner, themagnetic moments of some of these molecules become aligned with the direction of the field. A radio frequency transmitter is briefly turned on, producing a further varyingelectromagnetic field PowerPoint Presentation: The photons of this field have just the right energy, known as the resonance frequency, to be absorbed and flip the spin of the aligned protons in the body. The frequency at which the protons resonate depends on the strength of the applied magnetic field. After the field is turned off, those protons which absorbed energy revert to the original lower-energy spin-down state PowerPoint Presentation: Now a hydrogen dipole has two spins, 1 high spin and 1 low. In low spin both dipole and field are in parallel direction In high spin case it is antiparallel. They release the difference in energy as a photon, and the released photons are detected by the scanner as an electromagnetic signal, similar to radio waves. PowerPoint Presentation: It is this relationship between field-strength and frequency that allows the use of nuclear magnetic resonance for imaging An image can be constructed because the protons in different tissues return to their equilibrium state at different rates, which is a difference that can be detected. Five different tissue variables — spin density, T 1 and T 2 relaxation times and flow and spectral shifts can be used to construct images PowerPoint Presentation: Contrast agents may be injected i.v. to enhance the appearance of bloodvessels, tumors or inflammation. Adv/dis : Adv/dis MRI uses no ionizing radiation – safe strong magnetic fields and radio pulses can affect metal implants, including cochlear implants and cardiac pacemakers Gradient coils are within the bore of the scanner, there are large forces between them and the main field coils, producing most of the noise that is heard during operation. PowerPoint Presentation: MRI is particularly useful for tissues with many hydrogen nuclei and little density contrast, such as the brain, muscle, connectiv tissue and most tumors Claustrophobia Time cosuming PowerPoint Presentation: T 1 -weighted scans are a standard basic scan, in particular differentiating fat from water - with water darker and fat brighter T 2 -weighted scans are another basic type. Like the T 1 -weighted scan, fat is differentiated from water - but in this case fat shows darker, and water lighter Uses : Uses Used extensively for prenatal diagnosis valuable diagnostic results in gynecology diseases such as ovarian, uterus, and breast tumors . Endometriosis/ adenomyosis Congenital uterine malformation LASER : LASER Laser is an acronym that stands for light amplification by the stimulated emission of radiation PowerPoint Presentation: The first modality to be introduced was the carbondioxide, CO2-laser, used together with the colposcope for the treatment of cervical intraepithelial dysplasia and condylomata. The same laser has also been employed through laparoscopic technique The Neodymium-Yttrium-Aluminium-Garnet, (the Nd-YAG-laser), has been introduced for treating intrauterine conditions PowerPoint Presentation: Potassium-titanyl-phosphate (KTP), Argon. Lasers are named according to the medium that is activated Each medium produces light waves of specific wavelength giving it a characteristic color (monochromatic). BASIC PHYSICS: BASIC PHYSICS Different colors are produced by different lasers: Different colors are produced by different lasers The argon laser wavelength of 510 nm, blue-green light. The KTP wavelength of 532 nm, green color. The CO 2 laser, wavelength of 10,800 nm, which is in the nonvisible part of the electromagnetic spectrum Helium –neon laser red light to identify the location of the CO 2 beam. Focus: Focus LASER–TISSUE INTERACTION: LASER–TISSUE INTERACTION Three basic parameters wattage. For most gynecologic procedures using the CO 2 laser, 20–30 W, Time - The longer the laser remains focused on one spot, the more energy is applied to that area. Spot size of the beam. As one gets closer to the target area, the spot size is made smaller, producing a more intense effect. PowerPoint Presentation: the CO 2 laser remains the most versatile and is relatively safe because of limited depth penetration. The CO 2 beam is readily absorbed by tissue because of its high water content. The instantaneous boiling of intracellular water causes cells to explode, forming steam PowerPoint Presentation: Bleeding is reduced with the use of the CO 2 laser because of its coagulating properties; it seals small vessels as it cuts. Type Wavelength (nm) Color Fiber Depth of penetration Argon 488–512 Blue-green Yes 0.5 mm KTP/532 532 Green Yes 1–2 mm Nd:YAG 1,064 Infrared Yes 3–4 mm CO 2 10,600 Infrared No 0.1 mm Types of lasers used in gynecology As a result of a laser beam impacting on tissue, a spot or crater is created. The diameter of Disadvantages of the CO2 laser: Disadvantages of the CO 2 laser Focusing of the helium–neon beam Production of smoke referred to as “plume,” which needs frequent evacuation to allow adequate visualization of the target CO2 LASER: CO2 LASER the CO 2 laser is the most versatile and is extremely safe because of its limited depth of penetration (0.1–0.5 mm) and lateral thermal damage (0.5 mm). This allows use of the CO 2 laser in delicate areas , such as the bladder, lateral side wall near the ureter, and bowel serosa. Besides vaporization, the CO 2 laser can be used for excision or incision by increasing the power density. . KTP–ARGON LASERS: KTP–ARGON LASERS The advantages of these lasers over the CO 2 laser include : a selective absorption by hemoglobin , less plume production, an easy delivery system that uses lower power settings in the range of 5–10 W. The main disadvantage is the need to wear special glasses that distort the view LASER SAFETY: LASER SAFETY Gynecologists requesting laser privileges should be certified for the specific type of laser used. Certification implies attendance of didactic instruction and practical use of the laser in the laboratory prior to its application in patients. Warning sign, such as “Laser in Use, Protective safety glasses PowerPoint Presentation: If not being fired , it should always be on stand-by mode. Surgical drapes near the operating field should be fire retardant and kept wet if possible. Adequate suction should be available to collect all plume produced by laser use, because intact viral DNA and papilloma-virus have been detected in the plume. PowerPoint Presentation: fibers used for transmission of laser energy are delicate and can break. understand their specific tissue interaction to avoid undesired trauma.