• discovery of x-rays by Roentgen.
• The bones appear white on the developed
plate, in contrast to the surrounding darker
• degree of transparency is based on the
density of the material.
classification of radiologic
a) Organ based include musculoskeletal, breast,
neurologic, abdominal, gastrointestinal,
thoracic, and genitourinary imaging.
(Chest/Bones & Joints / Abdomen / Head
b) Modality based include Ultrasound, PET, and
c) Subspecialty fields include pediatric imaging
and women's imaging.
• Conventional radiography remains a
fundamental tool in the detection and
diagnosis of disease presenting in the chest ,
abdomen, pelvis, breasts, and bones.
Standard posteroanterior chest X-ray.
A tumor (T) is seen at the left hilum.
• Procedure—after administration of the dye
continuous beam of x-rays to evaluate dynamic
processes, such as bowel peristalsis and diaphragmatic
a. evaluation of the upper and lower gastrointestinal
tract (e.g., barium enema)
b. spinal cord in the case of a lumbar puncture or
d. feeding tube or drainage catheter placement.
• Used for optimal detection of breast lesions,
particularly early breast carcinoma.
• Breast lesions +ve
US-guided core biopsy or fine-needle
• Decreased natural contrast between adjacent
structures of roughly similar radiographic density
mandates the use of contrast material.
• Contrast media are commonly utilized for the
a. GIT , Urinary tract, vascular system;
b. biliary tree for carcinoma or obstruction,
c. spinal canal, fistulous tracts arising from abscesses,
d. uterine cavity and fallopian tubes for uterine
anomalies and tubal patency, respectively
Iodinated contrast agents
• are water soluble
• classified in several ways, ionic/nonionic, monomeric/dimeric, or
• Side effects, while uncommon, encompass a spectrum, ranging
from mild reactions (flushing, tachycardia, and metallic taste in the
mouth) to life-threatening effects (hypotension, severe
bronchospasm, cardiac arrest).
• use of low-osmolality contrast agents is advocated, because these
agents have a significantly lower incidence of drug reactions.
• Uses of Water-soluble contrast agents—
a. gastrointestinal tract for suspected perforation,
b. prior to surgical procedures,
c. for contraindications to barium suspensions.
• Used for the standard upper gastrointestinal (UGI)
series and for evaluation of the small bowel and colon.
• Both single- and double-contrast techniques can be
performed in an UGI series after oral administration of
a barium suspension or during a barium enema,
following rectally administered barium .
• In the single-contrast study, only a barium suspension
is used, whereas double-contrast studies use both
barium and air to delineate mucosal irregularities and
superficially located lesions.
A single-contrast retrograde colonic enema
demonstrates an annular lesion
representing a cecal carcinoma (arrows)
Intravenous urography (IVU)
• most common contrast study of the urinary tract.
• After injection of contrast material into a peripheral vein,
sequential filming of the kidneys is performed , typically 1–3
minutes postinjection, as well as during contrast excretion into the
renal collecting system and ureters (pyelographic phase, typically
• Primary indications for this study include hematuria, urinary tract
calculi, ureteral obstruction, and evaluation of a suspected
• Nonenhanced helical CT is rapidly superceding the standard IVU
examination in cases of stone disease and ureteral obstruction.
• However, IVU remains the procedure of choice for evaluation of
suspected uroepithelial neoplasms, such as transitional cell
carcinoma, because it more sensitively detects subtle mucosal
• Retrograde studies of the renal collecting system
(retrograde pyelography), ureter (retrograde
ureterography), and bladder (cystography)
• performed by direct instillation of water-soluble
contrast material into the urinary bladder.
• These studies are typically performed for
evaluation of vesicoureteral reflux, calculi, or
An AP film from an intravenous urogram taken at 10 minutes in
a pt. with a proximal Lt ureteral calculus (arrow) and associated
left collecting system dilatation. The right collecting system is
normal, and the right ureter (arrowheads),bladder are seen.
• radiographic method for evaluation of the
endometrial cavity and the fallopian tubes.
• Procedure-- direct instillation of water-soluble
contrast material into the cervical canal.
a. primary or secondary infertility work-up,
b.detection of suspected uterine anomalies,
c. assessment of tubal patency
d.determination of the location of a uterine
leiomyoma within the endometrial cavity.
• the study of the vascular system
• Procedure --injection of water-soluble contrast media intra-
arterially (or intravenously, for venous studies) through a
percutaneously placed catheter under fluoroscopic guidance.
• Types: peripheral angiography, coronary angiography,
thoracic/abdominal aortography, pulmonary angiography, cerebral
angiography, and superior/inferior venocavography.
• Common applications include
i. assessment of vascular disease (atherosclerosis, aneurysm,
ii. prior to therapeutic interventions (stent placement),
iii. evaluation for pulmonary embolus.
• is typically performed for the evaluation of
suspected traumatic injury, dissection,
aneurysm, vasculitis, thromboembolic
disease, tumors, arteriovenous malformations
• CT angiography and MR angiography replaced
conventional angiographic studies .
• Coronary angiographic studies identify areas
of stenosis or occlusion involving the coronary
An aortogram demonstrates transection
(arrow) of the aortic arch at the aortic
isthmus extending about 4 cm below.
• In patients suspected of having a pulmonary
embolus, pulmonary angiography may be
• This procedure is generally used
i. when the results of a ventilation-perfusion (V/Q)
scan or pulmonary CT angiography are equivocal
ii. when a low-probability V/Q scan is obtained in
the presence of continued high clinical suspicion.
• myelography for evaluation of spinal cord compression.
• fistulography for detection of epithelialized tracts
arising from an inflammatory, infectious, or neoplastic
• sialography for the assessment of ductal obstruction or
tumor involving the salivary glands.
• galactography for detection of masses within large
breast ducts .
• cholangiography for detection of biliary ductal masses
• high-resolution CT
• commonly used for evaluation of diffuse
interstitial lung disease or detection of
• contrast resolution of vascular structures,
organs, or hypervascular neoplasms can be
enhanced following intravenous infusion of
water-soluble contrast media.
Contrast-enhanced CT image of the upper
abdomen demonstrates two low-attenuation
areas (M) confirmed as multiple hepatic
metastases from gastrointestinal stromal tumor.
• Procedure-- intravenous administration of iodinated
contrast material. Using a MDCT scanner, images are
• CT angiography has become an important tool for
i. assessment of the abdominal and iliac arteries,
ii. the thoracic aorta, the pulmonary arteries,
iii.and the extra- and intracranial carotid circulation.
• Exquisite anatomic detail of both intra- and
extraluminal structures is revealed using this
technique, including detection of intimal calcification
and mural thrombosis.
• CT colonography (virtual colonoscopy)
• used primarily in the detection and
characterization of colonic polyps
• These images display the mucosal surface of
the colon and internal density of the detected
• They also directly demonstrate the bowel wall
and extracolonic abdominal and pelvic
• noninvasive imaging technique that uses high-
frequency sound waves.
b.variable visualization of midline abdominal
organs (pancreas) or vasculature when
obscured by overlying bowel gas
c. inability of sound waves to penetrate gas or
• abdomen [liver, gallbladder, pancreas, kidneys],
• pelvis (female reproductive organs),
• fetus (routine fetal surveys for detection of anomalies),
• vascular system (aneurysms, arteriovenous
communications, deep-venous thrombosis),
• testicles (tumor, torsion, infection),
• pediatric brain (hemorrhage, congenital
• breast, and
• chest (size and location of pleural fluid collections).
• ultrasound-guided interventions –used for
b.abscess drainage, and
c. radiofrequency ablation.
A transverse ultrasound image of the
gallbladder demonstrates a gallstone (arrow)
with the characteristic distal acoustic shadowing
(S) because sound waves cannot penetrate the
• It is used to calculate the corresponding flow
velocities, which reflects the flow pattern
within the vessel.
• Color flow Doppler assigns colors (blue and
red) to structures according to their motion
toward or away from transducers.
• This information can be superimposed on a
• Endoluminal sonography is used to image structures beyond the
lumen of the hollow viscus.
• It is accurate in local staging of cancer and in detecting small lesions
that may not be visualized with other imaging modalities.
a. GI applications include quantification of the size and wall thickness
of esophageal carcinoma or varices. Eg. Upper GI
endoscopy and colonoscopy.
b. Transrectal USG is performed for evaluation of the prostate.
c. Genitourinary (GU) applications include examination of the severity
and length of ureteral strictures, diagnosis of upper tract neoplasms
and urethral diverticula, identification of submucosal calculi.
d. The uterus, adnexa, and routine fetal examinations by using a
transvaginal probe in the presence of an empty bladder.
e. Sonohysterography, an ultrasound-guided procedure, requires
instillation of a sterile saline solution into the uterine cavity following
cannulation for evaluation of endometrial masses or other
f. Transesophageal echocardiography is used for evaluating cardiovascular
abnormalities after placement of a probe into the esophagus.
g. Three-dimensional ultrasound (3D-US) is widely used in obstetrics and
i. 3D-US is used to quantify the volume of organs and pathology.
ii. It has been used predominantly in obstetrics for studying normal
embryonic and/or fetal development and
iii. for detecting specific congenital anomalies in a fetus at risk given a
known family history.
• In MR imaging, a pulsed radio-frequency (rf) beam is
used in the presence of a strong main magnetic field to
generate high-quality images of the body.
• Images can be acquired in virtually any plane, although
sagittal, coronal, and axial images are commonly
• The most commonly used, clinically approved contrast
for MR imaging is a paramagnetic agent (atoms with
unpaired electrons in their outer shells) containing
gadolinium, termed gadolinium dimeglumine.
• neurologic indications, including brain tumors , acute
ischemia, infection, and congenital abnormalities.
• non-neurologic indications, namely, spine,
musculoskeletal, cardiac, hepatic, biliary, pancreatic,
adrenal, renal, breast, and female pelvis applications.
• Spine MR studies are useful for evaluating
degenerative changes, disk herniation, infection,
metastatic disease, or congenital abnormalities.
• Cardiac studies are performed to identify congenital
anomalies and complex malformations (malpositioning
of great vessels and/or cardiac chambers).
• Common musculoskeletal applications involve
the knee, shoulder, and hip.
• The primary indication for the knee is the
assessment of the menisci and ligaments
following internal derangement.
• Rotator cuff tear is the most typical shoulder
• Abdomen -- hepatic MR imaging studies are often used to
diagnose atypical presentations of liver lesions, metastatic
diseases, or hepatocellular carcinoma.
• Adrenal studies are performed primarily to distinguish
adrenal adenomas from metastatic disease.
• Atypical renal masses, found incidentally on USG or CT, can
often be better characterized on MR imaging.
• Breast MR imaging is predominantly utilized for detection
and evaluation of ruptured implants, and to detect the
• Female pelvis --diagnosis and characterization of cervical
and endometrial carcinomas, as well as adnexal lesions.
A midline sagittal T1-weighted contrast-
enhanced MR image depicts a large tumor
(T) in the region of the pineal gland.
• patients with metal implants or
eg. intracranial aneurysm clips, intraorbital
metallic foci, cardiac pacemakers, or specific
types of cardiac valves.
• MR imaging may also be contraindicated for
claustrophobic or uncooperative patients who
may not respond to conscious sedation
• It is exquisitely sensitive to the microscopic
molecular motion of water, demonstrating areas
of limited (restricted) intracellular diffusion
following an acute ischemic event.
• This sequence is routinely utilized in clinical
neuroimaging protocols, but is nonspecific for
• diffusion changes similar to that seen with acute
ischemia can be observed with infection and
3D contrast-enhanced magnetic resonance
angiography (MR angiography)
• It is used for noninvasive assessment of many
vascular abnormalities, including aneurysms,
dissection, vessel anomalies, and coarctation.
• It is used to evaluate choledocholithiasis,
retained gallstones, pancreatobiliary
neoplasms, strictures, primary sclerosing
cholangitis, and chronic pancreatitis.
• ERCP is generally reserved for therapeutic
purposes, such as stent placement, stone
extraction, or stricture dilatation.
• Nuclear medicine studies are performed by
administering a radiopharmaceutical to the patient
and subsequently recording its distribution in the body
over a defined period of time.
• In general, these studies are very sensitive, but
relatively nonspecific, in the detection of
• Correlation with pertinent clinical history, physical
findings, laboratory data, and other diagnostic imaging
procedures is, therefore, essential to render an
accurate interpretation and for maximizing clinical
benefits to both the patient and ordering physician.
• radiopharmaceuticals typically consist of two
(1)the main component, which is the compound
distributed to various organs by a number of
physiologic mechanisms, and
(2)the radionuclide tagged to this component,
which emits gamma rays, permitting detection
of the compound in the body.
Types of Nuclear studies
• Single photon emission computed
• Positron emission tomography
• new developments in PET technology include
the use of combined PET/CT imaging devices
• Advantages of both SPECT and PET include
i. ability to map the distribution of the
radiopharmaceutical in three dimensions,
iii.ability to generate cinematic displays of the
Common nuclear medicine procedures
A. cardiac studies for evaluation of myocardial perfusion
and/or ventricular function;
B. skeletal studies for detection of early bone metastases
and primary bone neoplasms;
C. renograms and renal scans for assessment of renal
function and morphologic defects (e.g., pyelonephritis);
D. ventilation–perfusion studies for identification of
suspected pulmonary emboli; and
E. PET studies for tumor diagnosis and staging (e.g., lung,
colorectal, breast, lymphoma, melanoma), as well as for
evaluation of neurodegenerative disorders (dementia),
brain tumor recurrence, and myocardial viability.
• less commonly performed nuclear medicine
a. diagnostic thyroid studies for evaluation of
nodules and following iodine-131 therapy for
hyperthyroidism and thyroid cancer,
b.hepatobiliary studies for determination of acute
cholecystitis and bile duct patency,
c. brain imaging for assessment of brain death and
d.white blood cell studies for detection of
infectious or inflammatory processes,
e.gastrointestinal bleeding studies for detection
and localization of small bleeds,
f. lymphoscintigraphy to identify sentinel lymph
nodes for surgery, and
g.parathyroid scans to identify adenomas and
Tc-MDP bone scan in the anterior and posterior projections
demonstrates multiple foci of increased radiopharmaceutical
accumulation (spine, ribs, pelvis, and left clavicle) with the
typical appearance of bone metastases.