CLINICAL APPLICATIONS OF CT SCAN.pptx

CLINICALAPPLICATIONS OF CT SCAN
Presenter: Dr. Dheeraj Kumar
MRIT, Ph.D. (Radiology and Imaging)
Assistant Professor
Medical Radiology and Imaging Technology
School of Health Sciences, CSJM University, Kanpur
September 26, 2023 Assist. Prof. Dheeraj Kumar 1

CONTENTS
• INTRODUCTION
• HISTORY
• CLINICAL APPLICATIONS
• SUMMARY
• REFERENCES

INTRODUCTION
• Computed tomography (CT) is an essential tool in diagnostic imaging for evaluating many
clinical conditions.
• A computerized tomography (CT) scan combines a series of X-ray images taken from
different angles around your body and uses computer processing to create cross-sectional
images (slices) of the bones, blood vessels and soft tissues inside your body.
• In recent years, there have been several notable advances in CT technology that already have
had or are expected to have a significant clinical impact, including extreme multidetector
CT, iterative reconstruction algorithms, dual-energy CT, cone-beam CT, portable CT, and
phase-contrast CT.

HISTORY
• The first commercially available CT scanner was created
by British engineer Sir Godfrey Hounsfield of EMI
(Electronic Musical Instruments) Laboratories in 1972.
• He co-invented the technology with physicist Dr. Allan
Cormack. Both researchers were later on jointly awarded
the 1979 Nobel Prize in Physiology and Medicine. By
1981, Hounsfield was knighted and became Sir Godfrey
Hounsfield.

• However, it was the mathematical theory of Johann
Radon way back in 1917, called “Radon
transform,” that brought the technology to life.
Another mathematical advancement that Hounsfield
built on is the “Algebraic Reconstruction
Technique,” which was formulated by Polish
mathematician Stefan Kaczmarz in 1937.
• Both theories were adopted by Hounsfield to create
one of the greatest advancements in medical history.

ADVANTEGES OF CT
MULTI SLICE SCANNING ADVANTAGE OF OVER SINGLE SLICE

ADVANTAGES CT SCANNER
• This has improved the diagnostic capabilities of CT scanners. Recently new scanners capable of
producing 32, 40 and even 64 images have been announced. These scanners will increase the diagnostic
capabilities of CT scanners even further, resulting in clearer images and lower doses of radiation
• Multi-slice scanners mean that it takes less time to complete a CT scan. Additionally, the amount of
radiation is reduced. The amount of radiation experienced depends on two factors. First, the design of the
scanner impacts the amount of radiation required. Secondly, how the scanner is used determines the
amount of radiation used.
• One of the key differences between single slice scanners and multi-slice scanners is the geometric
efficiency of the scan. Additionally, the amount of radiation used depends on the scan’s parameters- kV,
rotation time, mA, scan field of view, focal spot size, pitch and slice width.

ADVANTAGES WITH MULTI SLICE CT
SCANNERS
• With each rotation, it produces higher simultaneous 0.5 mm slices and gives
isotropic volumetric data with a better resolution
• Thin slice volume data reconstructed
• Post processing advanced visualization algorithms allow the extraction of
specific body parts
• Allow to understand complex anatomy and diseases
• Open new clinical possibilities
• Uncompromised image quality at a level never seen before

APPLICATIONS WITH MULTISLICE
CT SCANNER
• CT Head, Abdomen and Extremities
• CT Angiography (CTA)
• Coronary CT Angiography (CCTA)
• Visualization of Cardiac and Other Structure
• Cardiac Calcium Scoring
• Routine CT Scanning with Better Resolution
• Virtual Bronchoscopy
• Virtual Colonoscopy

CT HEAD
Indications
• Bone abnormalities.
• Brain mass/tumor.
• Fluid collection, such as an abscess.
• Haemorrhage.
• Hydrocephalus.
• Ischemic process, such as a stroke.
• Trauma or fracture of the skull.

BONE ABNORMALITIES
CT HEAD CONGENITAL
CALVARIAL DEFECTS
CT HEAD CONGENITAL
CALVARIAL SPECTRUM
CT HEAD SKULL FRACTURE

BRAIN MASS/TUMOR
NCCT BRAINTUMOR

FLUID COLLECTION, SUCH AS AN
ABCESS

HAEMORRHAGE

HYDROCEPHALUS

ISCHEMIC PROCESS, SUCH AS A
STROKE

TRAUMA OR FRACTURE OF THE
SKULL

CT ABDOMEN
Indications
• Abdominal pain.
• Difficulties in breathing
• Abdominal sepsis.
• Bowel obstruction.
• Postoperative complications.
• Trauma.
• Vascular compromise, e.g. aortic aneurysm.

DIFFICULTIES IN BREATHING
Consolidation

ABDOMINAL SEPSIS
Abscess
sepsis

BOWEL OBSTRUCTION

POSTOPERATIVE COMPLICATIONS

ABDOMINAL TRAUMA

VASCULAR COMPROMISE, E.G.
AORTIC ANEURYSM

CT EXTREMITY
Reasons for an Extremity CT Scan
• Evaluate pain, swelling, or trauma.
• Identify and localize a known mass.
• Examine complex fractures.
• Diagnose arthritis.
• Scan for a collection of pus (abscess)
• Monitor scar tissue and healing after surgery.

CT ANGIOGRAPHY (CTA)
With ultra fast scanning, arteries serving the brain, lungs, kidneys, arms and legs can
be evaluated non-invasively.
 Cerebral aneurysm
 Carotid stenosis
 Pulmonary embolism
 Renal artery stenosis
 Aortic aneurysm / dissection
 Mesenteric ischemia
 Hepatic artery anatomy (For Surgery)

CT Angiography- Technique
• Bolus tracking
• Amount and rate of contrast media
• Exposure factors
• Pitch/ Collimation

CT PERFUSION
• Computed tomography (CT) perfusion
imaging shows which areas of the specific
organ are adequately supplied or perfused with
blood and provides detailed information on
delivery of blood or blood flow to the brain
• CT perfusion scanning is a non-invasive
medical test that helps physicians diagnose and
treat medical conditions

• Xenon gas previously used
Patients not very tolerant
Scans taken over 5-10 minutes at 1
minute intervals
• Faster scanning means ionic
contrast can now be used
Continuous scanning of the brain
during contrast injection
Scan time < 1 Minute

CORONARYANGIOGRAPHY
•Only 30% conventional angiographies intervention for
therapeutic purpose
•Rest 65-70% - Only for diagnostic purpose
(AHA- Heart and stroke statistics update, 2001)

CT CORONARYANGIOGRAPHY
CLINICALAPPLICATIONS
• ASYMPTOMATIC PATIENT
• High risk
• High calcium score
• SYMPATOMATIC PATIENT
• No history of CAD
• Atypical chest pain
• Inconclusive stress test
• FOLOOW UP OF POST BTPASS AND POST STENT PATIENTS
• TO RULE OUT CONGENITAL ANOMALIES

CALCIUM SCORE
• Cardiac computed tomography (CT) for Calcium Scoring uses special x-ray
equipment to produce pictures of the coronary arteries to determine if they
are blocked or narrowed by the build-up of plaque – an indicator for
atherosclerosis or coronary artery disease (CAD).
• The information obtained can help evaluate whether you are at increased risk
for heart attack.

RISK FACTORS OF CAD
The major risk factors for CAD are:
• high blood cholesterol levels
• family history of heart attacks
• diabetes
• high blood pressure
• cigarette smoking
• overweight or obese
• physical inactivity

CALCIUM SCORE- INTERPRETATION
The result of the test is usually given as a number called an Agatston score. The
score reflects the total area of calcium deposits and the density of the calcium.
• A score of zero means no calcium is seen in the heart. It suggests a low
chance of developing a heart attack in the future.
• When calcium is present, the higher the score, the higher your risk of heart
disease.
• A score of 100 to 300 means moderate plaque deposits. It's associated with a
relatively high risk of a heart attack or other heart disease over the next three
to five years.
• A score greater than 300 is a sign of very high to severe disease and heart
attack risk.

PLAQUE CHARACTERIZATION
(Schroder, JACC 2001)
PLAQUES CT DENSITY
Soft < 50 HU
Fibrotic 50-130 HU
Calcified > 130 HU

CT SOFTWARES AVAILABLE
Curved MPR
Dynamic CT MPI

VIRTUAL COLONOSCOPY
• Emerging noninvasive imaging technology for detecting colon polyps and
cancer
• Trends towards using this as screening gold standards as it permits complete
visualization of the entire colon, hence proving the opportunity to identify
precancerous polyps and cancer
• Accepted application include incomplete colonoscopy

ADVANTAGES OF CT COLONOSCOPY
• more comfortable
• No sedation is required
• Evidence that CTC is better able to
detect polyps than fecal occult blood
testing, Ba enema and sigmoidoscopy
• Take less time than either conventional
colonoscopy or lower GI Series
• Secondary benefits of the revealing
diseases or abnormalities outside the
colon

VIRTUAL BRONCHOSCOPY
• Virtual bronchoscopy (VB) is a novel
computed tomography (CT)-based
imaging technique that allows a non-
invasive intraluminal evaluation of the
tracheobronchial tree.
• Several studies have shown that VB can
accurately show the lumen and the
diameter of the trachea, the left and
right main stem bronchi, and the
bronchial tree down to the fourth order
of bronchial orifices and branches

Applications
Normal Anatomic Features And Variants
Tracheobronchial Stenosis
Bronchogenic Carcinoma
Endoluminal Lesion
Foreign Body Aspiration
Trauma
Stent Planning And Follow-up
Burn Injury
Tracheoesophageal Fistula

NORMAL ANATOMIC FEATURES and
TRACHEOBRONCHIAL STENOSIS
• 3D CT can depict the airway down to the 6th and 7th order of
subdivision
• The 3d map can be used to guide bronchoscopy or to direct
transbronchail needle biopsy
• The stenosis to lumen ratios determined with VB and Conventional
bronchoscopy were found to be within 10 % of each other
• Especially valuable for evaluation of suspected tracheobronchial
stenosis in children
• Less invasive and safer than fiberoptic bronchoscopy
• The advantage of depicting the adjustment structures such as
vascular rings, which can be a cause of stridor in children.

BRONCHOGENIC CARCINOMA
CT is the primary imaging technique for the detection, staging and follow-up of the
primary malignant tumors of the lung
CT with VB
Sensitivity- 100% for Obstructive lesions
16% for Mucosal lesions
90% for Endoluminal lesions
• Specificity for malignant tumors -100%
• Advantage of VB over fiberoptic bronchoscopy, can image beyond the site of
obstruction
• Visualization of the smaller airways, which are not accessible with fiberoptic
bronchoscopy

CT Scan Procedure May Be More Comfortable For The Patient
Carry Fewer Risks Of Complications
Sometimes Replace More Invasive Procedure
New Technology Providing Its Worth In Routine Scanning
It More Specialized Of Medical Image
CT Doses-
Higher For Some Exams But Could Be Lower For Other
Thin Slice Doses Lower Than On 4 Slice
Are Being Addressed By Dose Reduction Features

REFERENCES
• De wever W, vandecaveye V, lanciotti S, verschakelen JA. Multidetector ct-generated
virtual bronchoscopy: an illustrated review of the potential clinical indications. European
respiratory journal. 2004 may 1;23(5):776-82.
• Himi t, kataura a, sakata m, odawara y, satoh ji, sawaishi m. Three-dimensional imaging
of the temporal bone using a helical CT scan and its application in patients with cochlear
implantation. Orl. 1996;58(6):298-300.
• Ganz sd. Computer-aided design/computer-aided manufacturing applications using CT
and cone beam CT scanning technology. Dental clinics of north america. 2008 oct
1;52(4):777-808.
• De chiffre l, carmignato s, kruth jp, schmitt r, weckenmann a. Industrial applications of
computed tomography. CIRP annals. 2014 jan 1;63(2):655-77.

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