1) A we know the image that we can see using ultrasound imaging systems is created by the reflection of the high frequency waves or echoes from the organs. Different organs have different velocities, so the reflection of the waves from these organs will be different, also the time between emission of the pulse and receiving the echo determines the distance between the organ which produced the echo and the transducer. Based on these datas the image is formed. As the velocity of the soft tissues and their place is different, different images will be created.
2) a: It is the situation when the pulse is not attenuated. For example when the beams pass through a fluid-filled structure. In such cases the organ which is behind this structure in comparison with the organ beside it, seems to produce more echo.
b: Is the situation when the sound beam fails to pass through an object. For example sound can not pass through bones, and in images there is only shadowing behind it.
Image on the left side: It shows a large renal cyst. The liquid are anechoic and as you can see the walls are sharply defined and thin.
Image on the right side: It shows a gallstone. Inside the gallbladder, it produces a strong echo and causes a dark acoustic shadow.
3) The upper image is the short (transverse) axis, and second image is long (longitudinal) axis.
4) Probes can have different frequencies. For example an 8- 13 MHz probe allows us to choose frequencies, from 8 MHz to maximum 13 MHz. The lower frequencies are used for deeper organs and the higher frequencies for superficial structures, so frequency balances penetration and resolution. As we said as the frequency is higher, the depth penetration is less, but high frequency gives a higher resolution
the better resolution, means better clarity of an image. But to have the best details, the most important thing is to place the object of interest in focused area. It can be done by moving the probe closer or farther away from the organ or the object or by using less or more gell.
5) Basically M-mode or motion mode is when moving structures are displayed along a single line the ultrasound beam, so the produced images are 2-dimensional. M-mode echocardiography is very simple but in this imaging method the image is not similar to actual structure of the heart, it is almost similar to tracing. The views might be, right long-exis, right long-axis view optimised for left ventricle and atrium reference view, right long-axis view optimised for left ventricular outflow and aortic valve, right long/oblique-axis view optimised for pulmonary valve, and right short-axis views. By this method you measure heart structures, such as the pumping chambers, heart walls thickness and also the size of the heart or in other words helps us to determine the velocity of an organ. These images provide us with information regarding to reflecting borders displacement.
6) For abdominal ultrasound test, patient should not eat or drink from six hours before the procedure.
If any medications are necessary, it should be taken with a small amount of water. Kidney’s ultrasound doesn’t need six hour fasting. Ultrasound can be used in a wide range of diagnostic procedures such as biopsies from different organs, almost it is used to determine the location of the tissue which is needed to be tested. It is also used in image-guided biopsy when it is needed to view internal organs to locate the sample tissue which should be removed for analysis. In most cases after finding an abnormal tissue such as cancerogenous tissues by imaging systems, biopsies will be taken. A blood test should be done to check how well blood clots, it’s called clotting profile.
7) The very basic structure of a CT machine consists of, X-ray tube and X-ray detectors plus a movable section which patient can lie on it, it’s also called cradle . These are the parts that help to create an image. Basically in this technology by using computer-processed x-rays, tomographic images of an specific area of a scanned object are produced. So large series of two-dimensional radiographic images which are taken around a single axis of rotation, are used to produce a three-dimensional image.
8) In old CT machines images could be generated only in transverse or axial plane or perpendicular to the long axis of the body, but using modern CT machines allows us to reformat the data in various planes such as dorsal, transversal, sagital, and oblique planes or generally in 3D.
9) Skull: CT scan is indicated for detection of tumors, haemorrhage, trauma, infarction, and calcifications.
Extremity: Fractures, dislocations and ligamentous injuries.
Thoracic and abdominal: Diagnosis of abdominal disease, acute abdominal pain investigations, it is also used to determine stage of cancer, it is also used to differentiate adrenal tumors (to see if the tumor is benign or not) . CTPA, and also cardiac CT angiography
10) The main parts of the MRI machine consist of RF coils, gradient coils and magnet plus a very powerful computer system and the table, so patient can lay on it during imaging. Basically this machine forms a strong magnetic field around the area that needs to be scanned. The radio frequency signal produced by excited hydrogen atoms is detected and formatted into images. Any H atom in H2O molecules is excited by the strong magnetic field arounf the body. As we know if protons get exposed to short radio pulses at their resonance frequency, they can absorb energy. So the energy absorbed, and then released by nuclei, and the energy returnes to it’s primary state of equilibrium, the whole trasnsmition is called MRI signal. Different tissues and organs, produce different MRI signals. By using these signals and complex mathematical formulas on modern computers, the MRI images are produced.
11) Brain and spinal cord and also ligaments.
12) The most important issue regarding MRI safety is presence of any metal in the body, so using MRI for those who have any metallic implants is not allowed. Any type of biohazard has not been proved yet, though the usage of anesthetics affects the physiological situation of the animal so, the dose of anesthetic should be chosen according to the age, weight and specie. Most time isoflurane gas is used as anesthetic.
Works cited:
"MRI Overview." MRI Overview. N.p., n.d. Web. 11 Nov. 2013. <http://www.iit.edu/arc/workshops/pdfs/ARNOLD_MRI_Overview.pdf>.
"CT scanning ." CT scanning. N.p., n.d. Web. 11 Nov. 2013. <http://www.aapm.org/meetings/02AM/pdf/8372-23331.pdf>.
"Ultrasound." Ultrasound. N.p., n.d. Web. 11 Nov. 2013. <http://eeweb.poly.edu/~yao/EL5823/Ultrasound_imaging_ch11.pdf>.
Lavin, Lisa M.. Radiography in Veterinary Technology, 4th edition. Missouri: Elsevier Saunders, 2007. Print.
