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Introduction to Radiology - imaging
modalities
What are the imaging modalities that use ionizing radiation? - correct answer ✔✔1. Radiographs (x-rays, conventional films, plain films)
- Computed tomography (CT)
- Nuclear medicine (NM) What are the imaging modalities that do not use ionizing radiation? - correct answer ✔✔1. Magnetic resonance imaging (uses magnet and radio waves)
- ultrasound (uses sound waves) The birth of radiology started with which imaging modality? - correct answer ✔✔The x-ray On November 8th 1895, WilhelmConrad Roentgen discover the _____________. Why did he call it this? - correct answer ✔✔x-ray He termed this new invisible ray, X-ray (X = unknown) Receive 1st Nobel prize in physics in 1901 The X-ray hit widespread use for medical imaging by the year _________ - correct answer ✔✔ 1913 T or F: conventions radiographs/ plain films use an added contract material - correct answer ✔✔False: images produced through the use of ionizing radiation but without added contrast material i.e. Barium or iodine Conventional radiographs The X-rays pass through the patient and are detected on the other side by ___________ or __________ - correct answer ✔✔Films or digital detector
The images from conventional radiographs are named with consideration of what? - correct answer ✔✔The direction of x-ray beams What are some common radiographic projections? - correct answer ✔✔The radiographs are named with consideration of the direction of X-ray beams, common radiographic projections are
- Anterior-posterior (AP) - the x-rays go in the front and come out the back
- Posterior-anterior (PA) - Come through back first, then anterior, then hit the detector (often the orientation in the thorax)
- Lateral X-rays are absorbed based on what as they pass through the body? - correct answer ✔✔Based upon density of the tissue. (This difference in absorption produces an image) A totally _________ or _________ material will absorb all the X-rays, how does this show up on the image on the detector and what is it termed on that image? - correct answer ✔✔Opaque (= not able to be seen through) or dense material will absorb all the X-rays, allowing none to pass through, thus creating a WHITE image. This is referred to as radiopaque or radiodense *there will be a question on the exam concerning radiopaque or radiodense along with all the other similar terminologies from all the different modialities, she hinted hard core on this one When a less dense tissue is between the source and the film in a conventional radiograph, what happens to the x-rays and how does this correspond to the image detected? - correct answer ✔✔When a less dense tissue is between the source and the film, more X-rays strike the film, leading to a BLACK image. This is referred to as radiolucent Intermediate degrees of density give rise to shade of ________ in a conventional radiograph image - correct answer ✔✔Gray Radiopaque (or radiodense) = ____________ tissue; _________ image
________-absorbs the least x-ray and appears "blackest" on conventional radiographs - correct answer ✔✔Air _______-gray somewhat darker (blacker) than soft tissue - correct answer ✔✔Fat T or F: both fluid (ex: blood) and soft tissue (ex: muscle) have the same densities on conventional radiographs - correct answer ✔✔True: they have a medium gray level _________-the most dense naturally occurring material (ex: bones) absorbs most x-rays - correct answer ✔✔Calcium (because absorbs most x-rays, it generates a more radiopaque image of the bone on a conventional radiograph) ___________-usually absorbs all X-rays and appears the "whitest" (most radiopaque) - correct answer ✔✔Metal (ex: bullets, barium) T or F: you can get a complete view with just one view (one plane) of image taken with conventional radiograph. - correct answer ✔✔FALSE!! She emphasized this several times that one view = NO view Why does one view = no view in radiography? - correct answer ✔✔Radiographs are 2D projections of a 3D patient Radiographs flatten everything (everything is superimposed on one another) Multiple views are needed What are the advantages and disadvantages to plain films? - correct answer ✔✔Advantages
- Fast
- These images are relatively inexpensive to produce
- Can be obtained almost anywhere using portable or mobile machines
- Are still the most widely obtained imaging studies Disadvantages
- Utilizes ionizing radiation
- Soft tissue is hard to visualize or can't be visualized at all
- Not usually recommended for pregnant women except in an emergency What is fluoroscopy? - correct answer ✔✔Continuous beam of x-rays passes through the patient to give a moving, real-time image T or F: fluoroscopy is used in conjunction with contrast - correct answer ✔✔True: it is used in conjunction with contrast (ex: barium, iodine) What are the uses of fluoroscopy imaging? - correct answer ✔✔1. Can be helpful to evaluate motion in the intestinal tract or angiographic studies
- Also used for catheter and tube placement
- Fracture repair
- Apparatus placement in surgery CT was introduced in 1972, by British engineer _________ ________, as a more sensitive x-ray detection system, which creates slice images through the body - correct answer ✔✔Godfrey Hounsfield What was the advancement that became possible in imaging with the creating of the CT? - correct answer ✔✔The slice images through the body and Allowed the capability to see through the skull into the brain What is the scale used to measure CT density? - correct answer ✔✔Hounsfield units What does CT stand for? - correct answer ✔✔Computed Tomography (CT) The CT is similar to radiography in that it uses __________ from a source to produce an image - correct answer ✔✔Ionizing radiation
Increased attenuation White densities __________ substances that absorb fewer x-rays have low CT number, are said to demonstrate ____________, and are displayed as _____________ on CT scans - correct answer ✔✔Less dense substances Decreased attenuation Blacker densities Different window setting on the CT on the computer optimize the visibility of different types of pathology, when are these settings made (before or after the imaging)? - correct answer ✔✔The windows can be applied after the images are obtained. This is called post-processing *this keeps the patient from having to take several CTs, we can do post-processing based upon Hounsfield units What are two types of CT windows? - correct answer ✔✔Bone window Brain window The brain window allow evaluation of brain parenchyma, hemorrhage, CSF spaces, and soft tissue at the expense of _________ - correct answer ✔✔Bony detail Bone windows allow detailed examination for fractures but obscure all __________ detail - correct answer ✔✔Soft tissue T or F: CT scans have to be performed with contrast - correct answer ✔✔False CT scans can be performed with or without the intravenous administration of iodinated contrast material, but, in general, they yield more diagnostic information that is more easily recognizable when intravenous contrast can be used Why are radiographic contrast agents administered? - correct answer ✔✔To increase the differences in density between two tissues
CT scans done with intravenous contrast are called ____________ or simply _________ - correct answer ✔✔Contrast-enhanced Or simply enhanced While the contrast may yield more diagnostic information that is more easily recognizable in an enhanced CT scan, what is a disadvantage to contrast material? - correct answer ✔✔The iodinated contrast material can have adverse effects and produce serious reaction in susceptible individuals Intravenous contrast containing a high concentration of ___________ that circulate through the bloodstream, _________ those tissues and organs with high blood flow, are absorbed by x-rays, and then excreted in the ___________ by the _______ - correct answer ✔✔Iodine Opacify (they appear whiter on images because they absorb more x-rays) Excreted in urine by kidneys What happens in patients with compromised renal function when they are given iodinated contrast for CT scan? - correct answer ✔✔In some patients (ex: those with diabetes, dehydration, multiple myelomas) who have compromised renal function, iodinated contrast can produce a nephrotoxic effect resulting in a true tubular necrosis. Though usually reversible, in a small number of patients with underlying renal insufficiency, renal dysfunction may permanently worsen Mild side effects of the iodinated contrast material used in CT includ what? - correct answer ✔✔1. Nausea
- Vomiting
- Local irritation at the site of injection
- Itching
- Hives What are the advantages of CT? - correct answer ✔✔1. Resolution excellent for many areas (can see fractures otherwise missed)
- Can scan in multiple planes
- Widely available
- Cheaper than MRI
- Fast (a few seconds for the whole body)
(She was also talking about how the open MRI with the lower field strength would be advantageous for claustrophobic patients and could allow patients to be able to move the parts of the body not behind. Scanned while its happening-more comfortable and cheaper but not as detailed) MRI images can be weighted to enhance different characteristics of the ___________ tissue. What are these weights called? - correct answer ✔✔Soft tissue T1 weighted T2 weighted __________ weighted - usually best anatomical detail ___________ weighted - usually most sensitive for pathological lesions - correct answer ✔✔T1 weighted
- usually best anatomical detail T2 weighted - usually most sensitive for pathological lesions (she said through things like fluid and blood) A key point is that water will be dark on _______ weighted MRI images and bright on _______ weighted images. - correct answer ✔✔T1 weighted images - water is dark T2 weighted images - water is bright Note: memory tool H"2"O is bright in T"2" weighted images What is the term for a white or bright area in an MRI image? - correct answer ✔✔Increased (high) signal intensity What is the term for a black or dark area on an MRI image? - correct answer ✔✔Decreased (low) signal intensity What is an easy way to distinguish quickly between a T1 weighted and T2 weighted MRI image of the trunk? - correct answer ✔✔Because cerebrospinal fluid is similar to water in density, it appears dark on the T1-weighted image and bright on the T2 weighted image
T or F: subcutaneous fat and intra-abdominal fat would be bright only on T2-weighted image. - correct answer ✔✔False! Subcutaneous fate and intra-abdominal fat are bright on both T1-weighted and T2- weighted images What are the advantages and disadvantages of MRI? - correct answer ✔✔Advantages
- No ionizing radiation
- Can scan in multiple planes (axial, coronal, sagittal)
- Better soft tissue detail than CT Disadvantages
- Images can't be manipulated on the viewing screen like CT
- Narrower than in CT, worse for claustrophobic or larger patients
- Noisy
- Can't be scanned if you have certain kinds of metal/implants
- No movements allowed
- Adverse reaction to contrast
- MRI scans are long
- MRIs are expensive MRI scans are long, they can take ________ minutes - correct answer ✔✔30 - 60 minutes *this means you can fit less patients in in a day Patients that are ill and can't stop coughing or sneezing the day of the MRI scan should be rescheduled, why? - correct answer ✔✔Because patients need to lie still for the entire time, that is, for 30-60 minutes. Which would be the top choice for an image of the lungs or abdomen, MRI or CT? And why? - correct answer ✔✔CT would be your preferred choice because there are poor quality images of the abdomen and chest due to motion with breathing and peristalsis
In patients with renal insufficiency, gadolinium-based contrast agent have been associated with a rare, painful, debilitating and sometimes fatal disease called _______ _______ _______ - correct answer ✔✔Nephrogenic systemic fibrosis (NSF) Nephrogenic systemic fibrosis causes fibrosis of what body parts? - correct answer ✔✔1. Skin
- Eyes
- Joints
- Internal organs Resembling scleroderma What patients are at the greatest risk of developing nephrogenic systemic fibrosis? - correct answer ✔✔Patients with preexisting renal dysfunction, especially those on dialysis, are at the greater risk Caution is exercised when administering ________-base contrast agents to patient who have moderate renal disease and typically avoided in patients with severe renal disease. - correct answer ✔✔Gadolinium T or F: there is currently no evidence to suggest that patients with normal renal function are at risk of developing NSF, and contrast-enhanced MRI imaging remains extermely safe in the vast majority of patients - correct answer ✔✔True Ultrasound (US) employs a transducer that produces high frequency ______ ______ - correct answer ✔✔Sound waves In ultrasound, the __________ reflected by body structure and is recorded by the transducer and converted to grey image. - correct answer ✔✔Sound Tissue that reflects many echoes is referred to as what? And how does it appear in the image? - correct answer ✔✔Increased echogenicity or sonodense and appears bright white (Bones, stones, fat for example)
Tissue that has few or no echoes is referred to as what? And what does it appear as in the US image? - correct answer ✔✔Decreased echogenisity or sonolucent and appears dark or black (lymph nodes and tumors, things like that) Radiodense is a term used to describe what imaging modality? Sonodense is a term used to describe what imaging modality? - correct answer ✔✔Radiodense - radiographs/plain films Sonodense - ultrasound Both appear white in their respective imaging modalities What are the indications for ultrasound imaging? - correct answer ✔✔1. Usually the study of first choice in imaging the female pelvis and in pediatric patients
- Differentiating cystic versus solid lesions in all patients
- Noninvasive vascular imaging
- Imaging of the fetus and placenta during pregnancy
- Real-time image guided fluid aspiration and biopsies What are the advantages and disadvantages of ultrasound? - correct answer ✔✔Advantages
- No ionizing radiation
- Real-time images
- Produces little to no patient discomfort
- Easy to use and noninvasive
- Inexpensive
- Portable Disadvantages
- Bone and air-filled structures interfere with image
- Difficulty penetrating obese patients Radionuclide imaging is also known as ___________ imaging - correct answer ✔✔Nuclear
- Provides early detection Disadvantages
- Expensive
- Availability of service
- Radiation
- Poor spatial resolution ________ _________ in large doses, substantially higher than any medical radiographic procedure, is know to produce cell mutations that can lead to many forms of cancer and anomalies - correct answer ✔✔Ionizing radiation In considering the radiation exposure of imaging techniques, diagnostic examinations should be performed only when ________ ________ - correct answer ✔✔Medically necessary. When doing a medical radiographic procedure that uses ionizing radiation, you should shield the most radiation sensitive areas such as? - correct answer ✔✔Gonads Eye lens thyroid Studies using X-rays should be avoiding during potentially damaging times such as _____________ - correct answer ✔✔Pregnancy ______ ________ is the ionizing radiation present in the environment - correct answer ✔✔Background radiation What is the average background radiation dose? - correct answer ✔✔2.4 mSv/year (For comparison a chest radiograph is approximately 0.06 mSv which is about 1 week of background radiation and a chest CT is approximately 7.0 mSv which is about 3 years of background radiation
"Risks of medical imaging at effective doses below _________ for single procedure or __________ for multiple procedures over short time periods are too low to be detectable and may be nonexistent" - AAPM - correct answer ✔✔50 mSv 100 mSv The American college of radiology appropriateness criteria (www.acr.org) gives
- Evidence-based guidelines to choose imaging
- Relative radiation risk each study
- Modality guideline
- Practice guidelines: when (in what order) to perform - correct answer ✔✔ A 65 year old veteran presents to the emergency department with sever abdominal pain. His history states he had a recent place to of a pacemaker for an irregular heart rhythm. The physician wants to order a radiologic test to evaluate the patients pain. Which of the following test modalities is inappropriate to order for the patient based on his history?
- CT
- MRI
- US
- Plain films - correct answer ✔✔MRI - because of the pacemaker
