Radiological procedures

Plain x-ray

Examples

• Chest x-ray
• KUB
• Bones

How it is done

Example Indications

Limitation

Principle

CT scanning combines X-rays and computer to produce precisely detailed cross-sectional images of the organs. 

Examples

• Chest CT
• Head CT
• Abdomen CT
• Joint CT
• Bone CT

How it is done

• A computerized axial tomography scan is performed by obtaining axial x-rays images using computerized reconstruction. 
• CAT scans can be enhanced by using intravenous iodinated contrast material. 
  • This allows one to detect perfusion and concentration of the contrast by the kidney.
  • Evaluates increased enhancement of tumor with contrast separating it from normal enhancement of parenchyma.

• CT scan is helpful in delineating the characteristics of anatomy and function of organs
• Three-dimensional reconstructions studies and blood supply provide "road maps" for planning surgeries.

Limitation

Principle

The use of high-frequency sound waves to produce real-time images, provides a simple and painless way to examine structures.

Examples

• Abdomen
• Pelvis
• Scrotum

How it is done

• A hand held transducer sends high frequency sound waves into the body.
• The waves are reflected back by various tissues they go through.
• The reflected waves , with a help of a computer, form an image on the screen.
• Color coding of the various reflected echoes gives color images.
• Doppler examination is done using US waves aimed at a moving object - arteries or veins. The reflected waves with computer aid, give us the velocity of blood in various vessels.

Example Indications

Advantages

• Non-invasive test
• Requires no preparation
• No pain
• Provides accurate anatomic information, including dimensions
• No radiation risk
• Avoiding the potential allergic and toxic complications of contrast media.  
• Can be used on individuals with poor kidney function in whom contrast cannot be given
• No complications 
• Can be done at bedside
• Relatively economical exam

Limitation

MRI (Magnetic Resonance Imaging)

• MRI uses a strong magnet, radio waves and computers to create detailed images of the body. 

Examples

• Head  MR
• Abdomen MR
• Joint MR
• Bone  MR

How it is done

• Lying inside a massive hollow magnet, a patient is exposed to short bursts of powerful non-ionizing radio  wave energy, directed at protons, the nuclei of hydrogen or water atoms, in the body. 
• Radio signals generated by first "exciting" and then "relaxing" those protons, are computer-processed to form digital images, reflecting different types of tissue.
• It does not use ionizing radiation.

MRI is as good as CT or better in characterizing lesions of organs

• Because of its ability to show soft tissues in exquisite detail, MRI can detect disease and evaluate vasculature 
• MRI can delineate a cyst from a solid mass.
• In can identify the spread of cancer into the  vessels and soft tissue (Staging).

• When contrast CT cannot be done, MRI is useful to evaluate vascular lesions 

Example Indications

Limitation

• Expensive
• Limited availability
• MRI has limited applicability for the urinary tract since the non-specificity of its signals makes it ineffective in detecting calcifications and bladder abnormalities.

CT and MRI have replaced the need for renal angiogram. It is rarely done nowadays for diagnostic purposes..

However the therapeutic applications of angiography have expanded considerably.

Principle

Angiography provides a complete examination of the arterial supply to organs, including a view of the aorta and branches.

Examples

• Aortogram
• Cerebral angiogram
• Renal angiogram
• Pulmonary angiogram

How it is done

• A catheter is inserted into abdominal Aorta and contrast dye is injected into desired arteries. 
• X-ray images are taken at a rapid rate because the high pressure of the arterial blood flow will cause the dye to disappear quickly.

Past indications

• For evaluation of renal artery stenosis
• For delineation of vascular renal tumors
• For evaluation of tumor invasion of renal veins and inferior vena cava

Limitation

• Invasive procedure
• Bleeding and injury to the artery.
• Contrast complications

Radionuclide  study

Examples

• Lung scan
• Renal scan
• Bone scan

How it is done

• A nuclear renogram is performed by injecting a radioisotope into a vein. 
• Scanning begins with injection and is carried out up to 30 minutes. 
• Delayed views may be necessary. 
• The isotope flows through the blood vessels of the kidney and is filtered by the glomerulus and secreted by the renal tubules. 
• As the isotope flows into the kidney, it is detected by a nuclear medicine gamma camera usually placed posterior to the kidneys. 
• The amount of isotope filtered and drained by the kidneys is analyzed by a computer. 
• Perfusion, secretion and excretion of the kidney are determined with this test.

• It shows the anatomy and the function of Kidney 

• Very sensitive in detecting renal function. 

Example Indications

Advantages

• Radionuclide imaging is considered safe since it does not carry the risk of allergic reaction encountered with contrast 
• Radiation exposure is minimal.

Limitation

Nuclear medicine Testicular scan

• This study is usually ordered on an emergency basis
• 20 mCi of 99mTcO4 pertechnetate is given I.V. (adult dose).

• Scan for approximately 30 minutes.

• Useful to differentiate acute testicular torsion from other causes of testicular pain/swelling.
• This study demonstrates the presence or absence of perfusion to the testes. 
  • Flow is decreased or absent with torsion
  • Epididymitis and orchitis have normal or increased perfusion.

Contrast filling lumens

Examples

• GI studies
• Bronchogram
• Cystogram
• Retrograde pyelogram
• Fistulogram

How it is done

Example Indications

Advantages

Limitation

How it is done

Example Indications

Advantages

Limitation

Contrast in blood stream

Examples

• IVP
• CT angiogram

How it is done

Useful for

Example Indications

Advantages

Limitation

Voiding Cystourethrogram

A VCUG uses X-rays and iodinized contrast to study the bladder and urethra.

• A voiding cystourethrogram is performed by inserting a catheter into the urethra. 
• Contrast material is then instilled into the bladder through the catheter. 
• X-rays are taken before, during and after filling of the bladder. 
• When the bladder is full, the catheter is removed. 
• While the patient voids, additional x-rays are taken.

• Children with urinary tract infections. 
  • Reflux  is detected if contrast is seen to flow in retrograde fashion up the ureters from the bladder. 
• Pelvic trauma where rupture of the bladder or urethra is suspected.
  • If the bladder is ruptured, extravasation of contrast will be seen outside the bladder in the pelvis or abdomen. 
  • If urethra is ruptured, there is extravasation into the perineum.
• Patients with suspected bladder outlet obstruction 
  • Obstructions or strictures or injury of the urethra can be seen on the x-rays taken during voiding.

Limitations: 

• Insertion of the catheter is painful. 
• While conventional voiding cystograms are still necessary to evaluate the male urethra for posterior valves and bladder trauma, the majority of reflux studies today are done effectively with radionuclide cystography.

• Preliminary film of the urethra and bladder is obtained prior to injection of a contrast agent 
• A catheter is inserted about two centimeters into the penis. 
• The balloon on the catheter is slightly inflated and contrast is injected.
• Several X-rays are obtained during the injection of the contrast. 
• The bladder is then filled and the catheter is usually removed. 

Limitation

• Minor discomfort during and following the procedure
• Risk of contrast allergy
• Risk of urinary tract infection

• Defines ureters and collecting systems
• While newer diagnostic techniques have replaced this test for many functions, retrograde pyelography may still yield better definition of the upper urinary tract, particularly the ureter and kidney collecting system. 

How is retrograde pyelogram done?

• Urologist performs cystoscopy first
• A catheter is inserted inot ureteral orifice and contrast dye is injected. 
• This technique produces definitive images of calcifications and tumors thus allowing easy diagnosis of obstructions in the urinary system.

• Commonly performed when IVP produces an inadequate picture. Useful to study urinary tract obstruction when further clarification of nature of ureteral obstruction is required
• It also complements cystoscopy while investigating a patient with hematuria or recurrent or suspected cancer.
• Detects small lesions in the collecting system E.g. Transitional cell carcinoma

Limitations

• Contrast complications 
• May aggravate an existing urinary tract infection or triggering one from the catheterization.

Scrotal Ultrasound

Scrotal ultrasound is used to evaluate almost all abnormalities in the scrotum. 

• It can determine if the mass is intratesticular or extratesticular

• It can determine whether  the mass is cystic or solid. 

  • Cyst is benign.

  • Soild is usually malignant.

Principle

• IVP is a radiological test that uses contrast to outline the kidneys, ureters and bladder.  

• Also known as intravenous urogram (IVU) 

How it is done

• Preliminary KUB 

• Intravenous contrast is administered, and timed films are taken as contrast is excreted .

  • Routine IVP

  • Timed IVP for reno-vascular disease

• Useful for evaluating the anatomy of the kidneys, ureters and bladder
• One can detect function when no contrast is excreted
  • absence of renal function .
  • absence of perfusion to a kidney 
• Useful to identify urinary tract obstruction 
• Useful  to evaluate reno-vascular disease

• Labor and time intensive – it may take up to 6 hours to complete in the severe obstruction
• It requires placement of an intravenous line. 
• Requires a bowel preparation for optimal results
• Involves intravenous injection of potentially allergic and mildly nephrotoxic contrast
  • Nonionic contrast agents have lowered the incidence of adverse reactions.
• IVP's are not useful in patients with renal dysfunction.
• Newborns rarely have sufficient renal concentrating ability to allow the kidneys to be seen on an x-ray. 
• Hydration is important
• May aggravate renal failure