DIAGNOSTIC IMAGING

Diagnostic Imaging: A Clinical Perspective

Medical imaging is an essential part of the diagnosis of many diseases.

A diagnostic imaging procedure is indicated when the management of a patient depends on the findings of the procedure. Therefore, before any diagnostic imaging procedure is requested, the question of how the results will influence patient management and care should always be asked.

  • Prior to requesting a procedure, it is useful to determine if the required information is already available from
    recent procedures, and if the relevant clinical, laboratory, diagnostic imaging, and treatment information is provided.
  • When indicated and available, alternative diagnostic imaging procedures which do not use ionising radiation,
    e.g. ultrasound, should be chosen first, especially in children.

Questions to be answered to prevent unnecessary use of procedure and radiation

  • Has this procedure been done already?
  • Does the patient need it?
  • Does the patient need it NOW?
  • Is this the best procedure?
  • Are all the investigations I am requesting necessary?
  • Have you provided appropriate clinical information and questions that the procedure should answer?

No procedure should ever be requested in lieu of a thorough clinical assessment or as a means of satisfying a difficult patient.

Basic Diagnostic Imaging Modalities

  • Plain Radiography (Hospital)
  • Ultrasound scan (HC4 and Hospital)
    • Ultrasound is non-invasive and does not use ionising radiation. Therefore, when indicated, it is the most
      appropriate imaging modality for children and pregnant women.

Other imaging modalities (at RR and NR)

  • Computed tomography
  • Fluoroscopy
  • Magnetic Resonance Imaging
  • Nuclear Medicine
  • Mammography

In the following table, a summary of the clinical indication, the suggested investigation modality and the possible
findings are presented, as a guide to request the correct investigation based on the clinical suspicion.

Note

  • CT scan is the investigation of choice for intracranial pathological processes (severe head trauma, stroke, etc.)
    but it is only available at referral facilities.
SYSTEM/
BODY AREA
INDICATIONS MODALITY INFORMATION PROVIDED
Musculoskeletal
  • Suspected lesion of
    bony skull, spine and
    extremities
  • Monitoring progress of
    pathologic conditions
    (osteomyelitis etc.)
Plain X-rays
2 views taken
at right angles,
include the
joint above and
below in case of
a fracture
  • Fractures
  • Dislocations
  • Foreign bodies (metallic)
  • Bone lesions/destruction
  • Osteomyelitis
Chest/
pulmonary
  • Cough for >2 weeks
    not responding to
    treatment
  • Haemoptysis
  • Blunt chest trauma
  • Acute respiratory
    insufficiency/
    problems, asthma
  • Foreign bodies
    (metallic, coins)
Chest X-ray
  • Chest infections e.g.
    bronchopneumonia, lobar
    pneumonia, interstitial
    pneumonia
  • Pleurisy (pleural effusion)
  • TB (Lung infiltrates especially
    in upper lobe, pleural effusion,
    cavities, mediastinal /hilar
    lymph nodes)
  • Trauma complications
    (pneumothorax, fractured ribs,
    lung contusion, haemothorax)
  • Lung masses
  • Other lung/bronchial disorders
    (COPD)
Cardiovascular
  • Palpitation
  • Exertion dyspnoea
  • Difficulty in breathing
  • Peripheral oedema
Chest X-ray
  • Heart enlargement
    (cardiomegaly or pericardial
    effusion), poorly defined cardiac
    borders
  • Pulmonary oedema (Kerley B
    lines)
  • Pleural effusion
Paranasal
sinuses
  • Acute uncomplicated
    sinusitis
  • Chronic headache
  • Nasal congestion
  • Nasal discharge
X-rays of the
Paranasal
sinuses
  • Air-fluid levels, opacification,
    polyps, mucosal thickening
    indicating sinusitis
Postnasal
space
  • Snoring and difficulty
    in breathing in small
    children
X-ray of the
postnasal space
  • Hypertrophied adenoids
  • Compromised airways
Obstetric 1st trimester
  • First-Trimester
  • PV bleeding
  • Low abdominal pain
  • Not sure of date
  • Embryo viability
  • Suspected ectopic
    pregnancy
Obstetric
ultrasound scan
  • Intrauterine or extra-uterine
    pregnancy, ectopic pregnancy,
    cardiac activity, number of
    embryo/foetus, gestation age
Obstetric
2nd and 3rd
trimesters
  • 2nd and 3rd trimester
  • Fundo-height greater
    or less than WOA
  • PV bleeding
  • Loss of foetal
    movements
  • Foetal anomalies
Obstetric
ultrasound scan
  • Foetal presentation, amniotic
    fluid volume, cardiac activity,
    placental position, foetal
    biometry, and foetal number,
    plus an anatomic survey.
  • Umbilical cord around the neck
Gynaecology
  • Low abdominal pain
  • Abnormal PV bleeding
    or discharges
  • Amenorrhoea and
    irregular periods
  • Pelvic mass(es)
  • Infertility
Pelvic
ultrasound

Transvaginal
ultrasound

  • Uterine Masses (fibroids,
    polyps)
  • Ovarian masses/cysts
  • Pelvic inflammatory disease
    (fluid in the pouch of Douglas)
  • Polycystic ovaries
Abdomen
  • Suspected small bowel
    obstruction (SBO)
Plain
abdominal
X-ray (supine
and nondependent
(either upright
or left lateral
decubitus)

Ultrasound

X-Ray

  • Dilated small bowel, presence
    of > two air-fluid levels, air-fluid
    levels wider than 2.5 cm, and
    air-fluid levels differing >2 cm in
    height from one another within
    the same small bowel loop
  • Lumen of the fluid-filled small
    bowel loops dilated to >3 cm,
    length of the segment is >10
    cm, peristalsis of the dilated
    segment is increased, as shown
    by the to-and-fro or whirling
    motion of the bowel contents
  • Examining the area of transition
    from the dilated to normal
    bowel may identify causes
    of conditions e.g. bezoars,
    intussusception, Crohn’s
    disease, hernias and tumours
  • Or suspected large
    bowel obstruction
    Ultrasound
  • Colon dilated >6 cm and the
    cecum is not >9 cm in diameter.
    (Normal colonic caliber 3-8 cm,
    with the largest diameter in the
    cecum).

    • The colon is dilated proximal
      to the site of obstruction with a
      paucity or absence of gas distal
      to the obstruction.
    • Air-fluid levels are often seen in
      the dilated colon on the upright
      or decubitus radiographs.
      This suggests that the cause
      of obstruction is more acute
      since the colonic fluid has not
      been present long enough to be
      absorbed
  • Suspected perforation Abdominal
X-Ray (erect or
or left lateral
decubitus)
  • Gut perforation: Free air below
    the hemidiaphgram on the CXR
    indicate pneumoperitoneum
  • Liver or gall bladder
    disease
Ultrasound
  • Gallstones, cholecystitis
  • Hepatomegaly or cirrhosis
    (fibrotic liver)
  • Liver masses (tumours)
  • Intra-abdominal
    bleeding
  • Abdominal trauma
Ultrasound
  • Fluids (blood) in peritoneum
  • Liver/spleen rupture/
    haematoma
  • Aortic aneurysm
  • Renal trauma/haematoma
Urology
  • Urological diseases
Ultrasound
  • Kidney stones
  • Kidney diseases (cancer, chronic
    pyelonephritis, hydronephrosis)
  • Prostate enlargement