Category Archives: Radiology

Sinogram.

What is sinogram?

It is a special X-ray procedure that is done with contrast dye to visualize any abnormal opening (sinus) in the body. The contrast is injected via a rubber catheter. Serial x-ray pictures are taken to show the extension of the fistula.

Other name for sinogram is fistulogram.

What kind of contrast medium used in this procedure?

A low osmolar contrast medium, LOCM 150.

How is it done?

Technique :

  1. A prelim film is taken to exclude the presence of radio-opaque foreign body.
  2. A fine catheter is then inserted into the orifice of the sinus.
  3. After a gauze pad has been firmly placed over the orifice to discourage reflux, the contrast medium is injected under fluoroscopic control.
  4. Spot films are taken as required including tangential views.

Below are sequence of films taken to investigate a sinus at right mid thigh.

1. Prelim :  shows intramedullary fixation of right femur fracture. Site of fistula is located at mid thigh.


2. Right thigh AP : Dye is injected. There is a focal collection of contrast seen.

3. Lateral view : shows focal collection of contrast.

4. Right lower thigh AP : shows  seepage of contrast seen into the intramuscular layers of the lateral aspect of the right thigh.

5. Right upper thigh AP : shows seepage of contrast seen into the intramuscular layers of the lateral aspect of the right thigh up to the level of hip joint and distally to the level of distal femur (just above the femoral condyles).

How is it reported?

This is a sample report of a sinogram case.

NAME : ?

I/C : ?

SINOGRAM (01.04.2010)

Procedures:

Patient wound is cleaned. Sinus identified.

25 ml undiluted omipaque injected using 8F nasogastric tube.

Serial x-rays are taken.

Findings:

There is flow of contrast from the sinus into a focal collection measuring 3.5×4.5cm.

Seepage of contrast seen into the intramuscular layers of the lateral aspect of the right thigh.

Superiorly the contrast extends to the level of hip joint and distally to the level of distal femur (just above the femoral condyles).

There is no connection to the knee or hip joint.

CONCLUSION

No evidence of intra-articular extension of the right thigh abscess.

Radiologist 01.04.2010

Qs.

1.Why do I need a sinogram?

It is needed when your doctor has decided that you need this test to show passage of a cavity in the body that opens out onto the skin surface.

2.Where will the procedure take place ?

In a special room ( Fluoroscopy  room ) within the x-ray department.

3.How do I prepare for sonogram?

No special prep is required.

4.Who will be doing the sinogram?

Medical officer observed by radiologist /Radiologist.

5.What is actually happen during sinogram ?

a)      You may be asked to wear gown.

b)      Medical officer/ Radiologist will once again explain the procedure to you.

c)      Your skin will be washed with antiseptic solution and a small catheter is inserted into the opening of the sinus on the skin surface.

d)     A small amount of contrast is injected through the catheter into the sinus and serial x-rays are taken to show where the sinus goes.

e)      When all the x-rays have been taken, the catheter will be removed and your skin will be covered with a sterile dressing.

*If you normally use a stoma bag please bring a spare with you.This order only applies to abdomen related fistula or sinus.

6.Will it hurt?

You may experience a little discomfort during the procedure but there is usually no pain. If there is pain during the procedure, please tell someone.

7.How long will it take?

Around 30 minutes.

8.Are they any risks or complications ?

There may be a small amount of bleeding from the sinus for a short time.

Reference :

  1. A Guide to Radiological Procedures Stephen Chapman.

Don’t just simply order x-rays unless indicated!!

Risk from radiation is a slope, there is no one “cut-off” point below which it is “perfectly safe” – even small radiation doses may have some risk. Therefore, statutory regulations require the dose to be “as low as reasonably achievable”.
Having said that, there is no absolute “legal” limit to the dose a patient can receive – go ahead and order the scan if you think the investigation is medically indicated, and the benefits outweigh the risk.
What then, is the risk, and how do you explain it to patients in layman terms?

Contrast in CT and MR Imaging: Applications and Contraindications.

WHAT IS CONTRAST AGENT?

A substance placed in the body to increase image differentiation of anatomical structures.
It increases the differentiation between the areas containing contrast media and the areas not containing contrast media.

WHY NEED TO USE CONTRAST AGENT?

1.To better differentiate between anatomical structures.
2.To increase detection of pathology.

CT CONTRAST AGENTS

POSITIVE CONTRAST AGENT:
Iodinated Contrast Media

IODINATED CONTRAST MEDIA – Ionic

High Osmolar Contrast Media (HOCM)
-Composed of salts which dissociate in water into anions (radiopaque) and cations (osmotically active).
-Osmolality up to 5x serum ? toxicity.
-Non-intravascular route – oral / rectal.
-Not for use in subarachnoid space.
E.g. Gastrografin, Urografin, Isteropac

IODINATED CONTRAST MEDIA – Non-ionic

Low Osmolar Contrast Media (LOCM)
-Non-dissociating.
-Only about 2x serum osmolality.
-Less side effects, less nephrotoxic.
E.g. Ultravist, Omnipaque
Iso-osmolar Contrast Media
-Osmolality approximately serum osmolality.
-Preferred in renal impaired patients.
E.g. Visipaque
Oily Contrast Media
-Currently not widely used
-Used for – chemoembolisation
E.g. Lipiodol Ultra Fluid

METHODS OF ADMINISTRATION:

A)Intravenous injection
1.     Highlight blood vessels.

2.    Enhance structure of organs.

3.    Rapidly eliminated by kidneys.

B) Oral administration

C)Rectal administration

For Oral and rectal–>

1.  Highlight gastrointestinal tract in the abdomen and pelvis.

2.  Positive contrast – iodinated CM(Gastrografin)

3.  Negative contrast
– water
– air (CT colonoscopy)

D)Intrathecal injection

E)Intra-articular injection

CONTRAINDICATIONS

Recognizing patients at risk of contrast media reaction

1.Proven/suspected hypersensitivity to iodine

2.Previous severe reaction to contrast media

3.Asthma/significant allergy history

4.Heart disease

5.Infants/children/elderly

6.Liver failure

7.Renal impairment (moderate-severe) – NIDDM on Metformin

8.Myelomatosis

9.Poor hydration

10.Sickle cell anaemia

11.Thyrotoxicosis

12.Pregnancy

13.Phaeochromocytoma

IN THESE GROUPS OF PATIENTS, LOCM SHOULD ALWAYS BE THE CHOICE OVER HOCM!!

Overall incidence of contrast media reactions

HOCM: 5-12%

LOCM: 1-3%

Mortality rates of contrast media reactions

HOCM: approx 1:40,000

LOCM: approx 1: 200,000

Types of Contrast Media Reactions

1. Anaphylactoid (idiosyncratic)

Urticaria, facial & laryngeal oedema, bronchspasm, hypotension – life threatening

2. Non-idiosyncratic

Direct effect on organs (nephrotoxicity, vasovagal attacks, arrythmias, MI)

3. Local reaction

Extravasation, phlebitis

Severity of Contrast Media Reactions

Mild: Hives, flushed feeling, metallic taste, nausea, vomiting

Moderate: Bronchospasm, laryngospasm, hypotension

Severe: Life threatening anaphylaxis

!! REACTION MAY BE DELAYED UP TO 1 WEEK !!

PATIENT PREPARATION

  1. Fasting 4-6 hrs
  2. Steroid cover  – allergy, asthma
  • T. prednisolone 50 mg 13, 7, 1 hr before examination
  • IV hydrocortisone 200mg stat

3. Renal impairment

  • N-acetyl cysteine 600mg the day before and 1 day after examination

MR CONTRAST AGENTS

Paramagnetic / Superparamagnetic
-Causes changes in the local magnetic field
–>shortened T1 relaxation time – increases signal intensity on T1-weighted images
–>shortened T2 relaxation time – decreases signal intensity on T2-weighted images
e.g.Gadolinium-DTPA (Magnevist)


Newer MRI contrast media
1.Liver-specific MRI agents
-Accumulates in the liver
e.g. Resovist, Primovist, MultiHance
2.USPIO (ultrasmall paramagnetic iron peroxide particles)
-Accumulate in macrophages in lymph nodes
-Currently undergoing clinical trials, no FDA approval as yet

COMPLICATIONS

1.Hypersensitivity reaction
2.Nephrogenic systemic fibrosis
-Recently reported serious late adverse reaction of gadolinium-based contrast.
-Seen in patients with renal failure and on dialysis.
-Fibrosis of skin and organs.
-Clinical symptoms developed 2-8 weeks after exposure to gadodiamide.
-Avoid in patient with creatinine clearance <15mL/min.

Source :
Dept of Biomedical Imaging UMMC

CT and MRI for non-radiologist Course

Deep Vein Thrombosis ( DVT )

Definition

Deep venous thrombosis is a condition in which a blood clot forms in a vein that is deep inside the body.

Causes

Deep venous thrombosis (DVT) mainly affects the large veins in the lower leg and thigh. The clot can block blood flow. If the clot breaks off and moves through the bloodstream, it can get stuck in the brain, lungs, heart, or other area, leading to severe damage.

Risks for DVT include:

  • Immobility which causes blood flow in the veins to be slow. Slow flowing blood is more likely to clot than normal flowing blood.
    • A surgical operation which lasts more than 30 minutes is the most common cause of a DVT. The legs become still when you are under anaesthetic. Blood flow in the leg veins can become very slow.
    • Any illness or injury that causes immobility increases the risk of a DVT.
    • Long journeys by plane, train, etc are thought to cause a slightly increased risk of DVT. This is probably due to sitting cramped for long periods.
  • Faulty blood clotting is an uncommon cause. One example is an inherited condition that causes the blood to clot more easily than normal (factor V leiden).
  • The contraceptive pill and hormone replacement therapy (HRT) which contain oestrogen can cause the blood to clot slightly more easily. Women taking ‘the pill’ or ‘HRT’ have a small increased risk of DVT.
  • Damage to the inside lining of the vein increases the risk of a blood clot forming. For example, a DVT may damage the lining of the vein. So, if you have already had a DVT, then you have a higher than average risk of having another one sometime in the future.
  • Older people are more likely to have a DVT, particularly if you have poor mobility or have a serious illness such as cancer.
  • Pregnancy increases the risk. About 1 in 1000 pregnant women have a DVT.
  • Obesity also increases the risk of having a DVT.
  • Bedrest
  • Cigarette smoking
  • Fractures
  • Giving birth within the last 6 months Read more »

Skeletal survey…what x-rays should you order.

Many of us do not know what is necessary for a skeletal survey and what the indications are….

Well…to cut it short…Here’s some knowledge about Skeletal survey.

Definition

A skeletal survey is a systematically performed series of radiographic images that encompasses the entire skeleton or those anatomic regions appropriate for the
clinical indications.

Indications and parts to be x-rayed as below:

1. NAI ( NON ACCIDENTAL INJURY )

CHEST
AP / PA view, erect if possible
SKULL
AP/LATERAL
LUMBAR SPINE
LATERAL
PELVIS WITH LL
(In 1 film where possible,if not then 2 films.)
AP to include the toes
BOTH UL
AP, done separately to include finger tips.
2) FOR GENETIC ABNORMALITIES

CHEST
AP/PA, erect whenever possible
SKULL
LATERAL
LUMBAR SPINE
LATERAL
PELVIS
AP
L SIDE UL
AP
L SIDE LL
AP
3) RENAL OSTEODYSTROPHIES

CHEST
PA/AP
SKULL
LATERAL
LUMBAR SPINE
LATERAL
PELVIS
AP
BOTH HANDS
PA
That’s all for today…..Enjoy!