MS-1 FUND 1: 8:10-9:10
Thursday, September 17, 2017
Dr. Sushil Sonavane M.D.
Intro to Imaging – lecture 1
Transcriber: Sarah Hashimi
Editor: Sushma Boppana
Page 1 of 4
Abbreviations: AP – Anterior posterior plane
Introductory Comments: This is the first hour of Dr. Sonavane’s Imaging lecture. Audio times are from ECHO recording
and slide numbers are given whenever applicable. Dr. Sonavane is a assistant professor in radiology who works in
cardiopulmonary specialty. This is an image heavy presentation; please refer to powerpoint for images.
I.
X-rays (slide 2) 2:31
i. X-ray discovery in 1896 by Wilhelm Rotgen - described x-rays and allowed for the specialty of radiology
ii. Radiation is energy emitted from any source – encompasses the entire electromagnetic radiation spectrum
iii. Spectrum with visible light in the middle – frequency increases and wavelength decreases as you increase
from left to right on the spectrum (slide 4)
1. Longest to shortest – radio waves, visible light, ultraviolet, x-rays, gamma rays
iv. X-rays and gamma rays are the ionizing radiation which is used in medicine
1. Ionizing - the molecule has energy enough to eject an electron from an atom to form an ion
a. High frequency means that it has penetrability. It has the capability to form ionizing radiation
b. The high penetrability of these molecules is what causes cellular damage/ cell mutation
v. Concept: x-rays pass through the object and refract with different wavelengths depending on varying
densities of structures in body and create different shadows on the radiograph (slide 5) 4:06
1. Image: x-ray unit
a. X-ray tube houses the machine which creates x-rays and directs them at the patient
b. The x-rays are directed toward the patient and focused on a specific part of the body
2. Type of radiograph describes how the radiation is going through the patient
a. Posterior to anterior (PA) radiograph – patient is standing, imaged from behind
b. Anterior to posterior (AP) radiograph – lay patient down to examine the abdomen – the
receptor cassette is below the patient
II. Various methods for x-rays
a. Chest PA & Lateral (slide 6) 5:45
i. Radiograph of chest
1. Taken with laying down at two different angles to obtain a mental 3D image of body
a. Radio dense marker at shoulder used to identify the side of the patient (left, in this image)
2. 4-5 different densities shown as shades of gray. If you are going from darkest to lightest:
a. air  subcutaneous fat  muscles/tissue (soft tissues)  bone  man-made structures
(markers, surgical implants)
i. air is dark because it causes no diffraction of the x-rays
ii. mostly soft tissue shown, hard to determine soft tissue abnormalities
b. Will always see fluid bubbles, throughout, the small ones are normal
3. 2D representation of a 3D structure, this is why you get the lateral dimension too, so that you can
see all the angles
a. Heart anatomy - On the PA view you can see the heart outline with the superior and inferior
vena cava, right atrium, right ventricle (sitting above diaphragm), and aortic knob. On the
lateral view you can see the aortic arch and the left atrium (behind the sternum).
b. Dual energy radiographs (slide 7) 9: 41
i. Modify the x-ray spectra to be more or less penetrating
ii. Image: Compare/contrast – normal x-ray with higher energy x-ray/ lower energy x- ray
iii. Concept: More energy will be more penetrating, creates a clearer picture
1. The x-ray penetrates the soft tissues creating shadows of various resolution
a. High energy, you see just bone
b. Low energy, you see just soft tissue
iv. Ex: 65 year old man, smoker for 25 years, chronic cough (slide 8) 10:58
1. Asymmetrical soft tissue opacity around the heart – clinical applications: indication of lung cancer
2. If seen in a young patient, opacity could indicate something different, like pneumonia, pulmonary
nodule, fluid collection
v. X-ray imaging of the chest is probably the most common radiological x-ray test done because there are
many different diagnoses which can be indicated by these images.
1. Evaluation for: lung cancer, pneumonia, air in the pleural space, fluid in the chest, pneumothorax
c. Abdomen Anterior – Posterior (AP) radiograph (slide 9) 11:45
i. Taken with patient in the prone position
ii. Abdomen – to see bowel structures and assess function
1. Example of a normal radiograph- can see some fundic “air bubbles” and air-containing structures.
MS-1 FUND 1: 8:10-9:10
Thursday, September 17, 2017
Dr. Sushil Sonavane M.D.
Intro to Imaging – lecture 1
Transcriber: Sarah Hashimi
Editor: Sushma Boppana
Page 2 of 4
Abbreviations: AP – Anterior posterior plane
a. Normal to have some air filled bowel loops but can indicate a problem if enlarged past a
certain point
2. Example of an abnormal radiograph: clearly enlarged (dilation) of small bowels (slide 9) 12:32
a. Loops at periphery (the colonic loops) are not overly dilated. The central loops (the small
bowel) are markedly dilated – indicates a small bowel obstruction.
b. Loops are considered dilated if their width exceeds the width of a vertebral body in the x-ray.
d. Mammogram (slides 11-13) 13:40
1. X ray study of breast tissue
2. Breast tissue is glandular and fatty –you don’t need high energy radiation to image the tissue
a. Clinically important for breast cancer screening
b. Example image: Red arrow – opacity might be breast cancer (slide 13) 14:20
III. Contrast agents used in imaging (slide 14) 14:43
a. What is it? A substance that imparts the greatest difference in density into adjacent pixels– NOT a dye!
i. Can choose based on color – extreme black or white spectrum
b. Barium sulfate (fluoroscopy) – commonly used in GI tract studies (slide 16)
i. BaSO4
ii. Inert
iii. Not water soluble
iv. Chalky appearance and thick consistency
v. Other uses: vacuum tubes, fireworks, florescent lamps, paint, rat poison
c. Other contrasting agents include: Iodine (fluoroscopy and CT) and gadolinium (MR) (SN: did not go over these in class
but written on the slide)
d. Use in upper GI studies (contrast fluoroscopy scan) – Administer the contrast agent orally and allow to pass
through the digestive tract, allows differentiation of the GI tract on the x-ray
1. Use of low energy x-ray used to see progress of the contrast dye over time while the signal is
amplified by the x-ray machine and shown on the monitor
2. Example images from GI study (slides 19-21)
a. White opacity is from the barium sulfate passage through the GI tract
3. Analyze the images to make sure no obstruction, mucosal abnormality, or obvious mass as the
contrast passes through the digestive tract
a. Note that one image is not in real time so have bowel movement artifacts
b. You monitor in real time (serial of images) so that you can see differences
e. Special contrast study of the colon (slide 21) 19:10
i. Uses both positive contrast of the barium and negative contrast of the air
ii. Helps delineate the mucosal details
iii. Arrow points to irregular mucosal layers (and magnified view) indicating colon cancer
IV. Computed Tomography Scanner (CT scanner) (slide 22) 20:27
a. from tomos = “slice” and graphien = “ to write”
b. Most performed medical scan – the workhorse of radiography
c. Components: x-ray source and a 360 degree scanner
i. Normal x-ray principal, but the x-ray and detectors moves all the way around the patient in coordinated
movements to get a circular “slice” of the body
ii. This is done in order to gain large information on the “slice” – allows 3D information on the patient’s body
1. Example images: (slide 24) 21:50
a. Trans-axial image of the patient’s chest (as if staring down foot of patient) – image has
markers for anterior, right, left, and table
b. Compare/contrast pictures: left – without contrast, doesn’t show much detail; and right – with
contrast can see outlines of the organ structures (heart, aorta, ventricles, and atria)
d. Dye: uses an IV contrast dye (iodine based) injected through a peripheral vein – which is used to differentiate
structures. Iodine based water soluble contrast agent can also be given orally after dilution
i. Do not use barium (like that was used in fluoroscopy) because it is too dense and will create a lot of
artifacts on the CT (SN: Mentions later (slide 36) 34:00)
e. Uses various body planes – sagittal, coronal, transverse (slide 25 – 27) 24:07
i. Looking from foot of patient – (transverse) slices
ii. Coronal plane – like the AP plane from the x-ray
iii. Sagittal plane – like the lateral view x-ray, taken from left/right side point of view; can see anterior and
posterior structures
f. Looking at another chest image (slide 28) 25:00
i. PA and lateral radiograph of chest, big abnormality of left side of mediastinum, follows the path of the aorta
MS-1 FUND 1: 8:10-9:10
Thursday, September 17, 2017
Dr. Sushil Sonavane M.D.
Intro to Imaging – lecture 1
Transcriber: Sarah Hashimi
Editor: Sushma Boppana
Page 3 of 4
Abbreviations: AP – Anterior posterior plane
ii. Patient presented with chest pain and hypertension
iii. The CT scan clearly shows the enlargement of the aorta (3 times larger) (slide 29) 26:00
<ARS Question 28:00>
g. Characteristics (slide 35) 31:45
i. >70 million CTs performed in US each year and has doubled in 5 years
ii. > 100,000 performed at UAB last year – probably more than that
iii. 2/3 medical radiation exposure is from CT – large radiation is the big downside, but quick - with the scanner
used now can scan entire chest in approximately 3 seconds of breath hold, and entire chest/abdomen/
pelvis in 9-10 seconds
1. Gives a lot of anatomic information about the soft tissues and the vascular structures but increases
radiation exposure since you are doing imaging at 360 degrees over multiple passes
h. Case examples/images: (SN: Dr. Sonayane jumped around a lot when describing the characteristics and images, these are compiled
as a summary for organizational purposes )
i. Ex: Radiograph (slide 28) 25:12- Abnormal chest x-ray and comparison with CT scan (slide 29) 26:04
1. Can see how the abnormality correlates with what we are seeing on the x-ray
2. X- ray - can see the enlargement of the aorta and is clearly an abnormal structure
3. CT angiography – Can see the extent of the abnormality, and can use this data to construct image
with 3D programs – without unwanted structures (lungs, etc.) to only look at structures of interest
a. May not be helpful for a diagnostic but important for surgery purposes – how the surgeon is
used to seeing the anatomy
4. Diagnosis – dissection of aorta with thrombosis formation. In dissections, the intima layer separates
from the media layer (due to trauma or atherosclerosis).
ii. Example: Coronal 3D vascular reconstruction (slide 32) 29:03
1. Shows skull, throat with trachea, lungs and aorta. This study is looking at common carotid and
subclavian arteries. The subclavian can sometimes get pinched between the first rib and clavicle.
This study looks to make sure that this vessel is totally patent and not obstructed.
iii. Example: Abdominal image with contrast (slide 33) 30:06
1. Shows the lower abdomen at the level of the inferior aspect of liver. Anterior to vertebral body, the
aorta has additional pools of contrast and additional soft tissue formation, indicating a leaking aortic
aneurysm (hematoma).
iv. Example: Three images with different CT scan settings (slide 34) 31:00
1. Can change display settings of the CT to look at different structures
2. Comparison of soft tissue, bone, and lung
v. Example: abdominal transverse slice (slide 36) 33:18
1. Oral ingested and IV injected contrast, trans-axial section
2. Patient with symptoms of dysphagia, hematemesis, and loss of weight; worrisome for malignancy in
esophagus or stomach
3. Shows mass with contrast enhancement and non-enhancing central area; the non-enhancing area
indicates necrosis of center of tumor
4. Tumor touching stomach, probably reason for onset of symptoms
a. Since the abdomen has a lot of fat, abdominal tumors can grow large before being detected.
This patient was not diagnosed until tumor began toughing stomach and causing symptoms.
i. Clinical advantage (slide 39-41) 35:43
i. Can do CT guidance for many procedures – take pictures at certain points to guide the surgeon
ii. Picture not in slide show 36:29 – example of procedural guidance - images of the chest
1. Procedures with CT guidance to avoid a more invasive procedure
2. The scan shows abnormality in the tissue, find path to go in with a needle and obtain the biopsy
sample without surgery
j. Summary of Advantages of CT – time, good resolution of tissues with contrast, allows 3D reconstruction, can
change the settings to look at one organ at a time, good resolution of both soft tissue and vasculature
abnormalities, can be done during a procedure to guide the physician (Slides 31-47)
V. Subtraction angiography – Use of X-ray to study of vascular structures using x-rays (slide 42 - 43) 37:20
a. What is typically done: access the aorta through the femoral or axillary artery with a catheter to inject contrast
i. Image of upper abdomen (slide 42 ) 38:00 (SN: several stacked images on ppt)
b. Then, digitally subtract all other structures (bones, etc.) so you just see the contrast
i. Image of aorta with branching
1. Can see the vascular anatomy at different levels with or without the organs
ii. Sometimes need vascular information before further procedures can be done – ex: kidney donor
1. This example shows that the patient has an additional renal artery (unique anatomy)
MS-1 FUND 1: 8:10-9:10
Thursday, September 17, 2017
Dr. Sushil Sonavane M.D.
Intro to Imaging – lecture 1
Transcriber: Sarah Hashimi
Editor: Sushma Boppana
Page 4 of 4
Abbreviations: AP – Anterior posterior plane
iii. Can get similar information with a CT scan or with reconstruction
c. Pros/Cons: more invasive than CT, but can have therapeutic applications
i. Difference is in the timing of the contrast injection
d. Example – therapeutic intervention (slide 43) 42:00
i. Patient has internal bleeding after traumatic liver injuries
ii. Catheter placed in descending aorta and injects contrast to identify source of bleeding. Material placed to
clot the artery and stop bleeding before surgery
iii. This intervention is more immediate than surgery
<ARS question 43:00>
e. Example: (slide 45) 43:37 Vascular information from a CT angiography
i. Can see the vasculature when you make a 3D reconstruction
ii. Depending on the information that you need, you can pick the best imaging, especially if you don’t
anticipate needing any intervention
f. Example: CT angiography in trauma patient (slide 46) 44:26
i. Patient with a comminuted, crush fracture of femur; worrisome for arterial injury
ii. Can use a CT angiography to assess; this patient does not have arterial injury
VI. Gamma Rays (Nuclear Medicine) (slide 47) 45:33
a. Other main ionizing radiation used in the medical field
i. Main difference: X-rays are emitted energy from electrons, gamma rays are emitted energy from atomic
nucleus
1. More penetrable (so more radiation)
b. Used in the field of Nuclear Medicine. Referred to as functional imaging or physiological imaging.
c. Used for more physiologic imaging than x-rays or CT scans – highlights the physiology of an organ
d. Works by giving a patient a radio tracer (usually orally) that we know will concentrate in a target organ. Once
tracer concentrates, it will emit gamma rays that we can detect to assess functionality of that organ.
i. Example: thyroid imaging. 95% of iodine will normally concentrate in thyroid. To image the thyroid, use a
radio tracer isotope of iodine
e. Radiopharmaceuticals, containing radionuclides usually:
1. Thallium
2. Technetium
ii. Photon emission – detected with a camera
iii. Crystal detectors – detect the signals
iv. Photomultiplier tubes – amplify the signals because they are very small – then these signals are transferred
to a monitor (SN: Dr. Sonavane says we do not need to know the technical terms )
f. Machine image (slide 48) 48:25
i. Similar looking machine and process as CT scans but image with the gamma camera and crystal detectors
g. Another machine can fuse anatomic and physiologic data if used with CT scan (slide 49) 49:14
i. Allows you to see abnormalities well
h. Example of image (slide 50) 49:26: Low anatomical resolution image (blurry)
i. Breast lymphoscintigraphy - Not done very frequently anymore, tracer injected into affected breast and see
what lymphatic region that it drains to, because that area may also be affected by cancer
1. Scintigraphy – refers to the gamma radiation study
ii. Ex: breast cancer- tracer seen in lymph node
1. Silhouette remains against the background – shows location of the tracer in the body, delineated
lymph node which should be removed. Allows the surgeon to know which lymph node to take out
VII. Pet scanner – Positive emission tomography - nuclear medicine study (slide 51) 51:18
a. Tracer: Glucose analog used as tracer (florodeoxyglucose (FDG)). Glucose is concentrated by body tissues
where there is rapid turnover, good for detecting primary tumors and site of metastasis
b. Important for cancer screening – functional screen, lacks clear anatomical data
c. Emission is a positron from the glucose analog – where the name is derived
d. Combining PET and CT scan to get better idea of disease process – fuses functional and anatomical scanning
i. Get CT scan then a functional scan and fuse images
ii. Example image (slide 52) 52:56
1. Can see low resolution organ activity from PET and high resolution anatomical data from the CT
2. Shows which anatomic structures are physiologically active, have increased glucose metabolism
(brain, myocardium, kidneys, bladder). This patient does not show diseased structures.
Student Questions: None
<END OF LECTURE 54:29>