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HO / MO guide to radiological investigations Ver 60430 CONTENTS

Organisational chart of imaging departments - Important people in the department Pre-investigation preparation - Contraindications - Preparation - Consent Taking and Risks of procedure Radiological investigations - FAQ - Head And Neck / Neurology / Neurosurgery / ENT - Respiratory / Cardiology / Cardiothoracic Surgery (CTS) - Abdomen / Pelvis / Gastroenterology / HBS / Urology / Obstetrics / Gynaecology / Breast - Orthopaedics / Spine / Extermities / Trauma Disclaimer

Organisational chart of imaging departments (aka Which department do I arrange this scan with?)

However, most of the hospitals don’t have all three departments. For some scans, they will be done by the radiology department; for others, the patient will have to travel to another hospital. In addition, the radiology departments in larger hospitals separate their inpatient and outpatient locations (E.g. SGH Inpatient is Blk 6, but outpatient is Blk 2) Back to top

Important people in the department (aka Who do I look for?) Who is he? Radiologist

Medical doctor specialising in imaging

His role Approve xray requests “Protocols” (gives technical instructions) on how to do the scan. Doesn’t actually do most scans! (except fluoro, U/S and angio)

Radiographer Technologist who runs the xray machines(Diploma holder after ‘A’-level)

When you need to look for him! Urgent requests

Not sure which investigation (e.g. CT vs MRI), special circumstances (pregnancy, implants in MRI, post-op anastomotic leak)

Covers medical emergencies.

Allergic reaction, collapse, resus

Interprets scans and issues report.

Urgent report, second opinion

X-ray conferences

Submit list of cases for round

Person who actually performs the xray, CT or MRI Prints the xray films

Sonographer

Specialised radiographer that does ultrasound

Specialises in ultrasound

Clerk

Runs the front desk!

Receives your request form

If you’ve brought the patient down and can’t find anyone! Need hardcopy film or CD Check if form has been received

Schedules appointments

Check appointment date and ask for an earlier one (sometimes works!)

Issues instruction phamplets, oral contrast, etc.

Collect contrast/prep after urgent request is approved

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Pre-investigation preparation Contraindications(By modality)

Modality

Absolute C/I

Plain Xrays

Relative C/I

-

i/v contrast: -CT -IVU

Allergy: CT Contrast, Iodine, Fish

Ultrasound

-

Pregnancy Renal disease (Raised Cr) Asthma DM on metformin Allergy: Multiple(> 3) -

MRI

Cochlear implant Pacemaker Intraocular foreign body Other mobile ferrous objects

Depending on model/operation date Vascular clips Artificial heart valve

Barium swallow / meal / enema

Suspected perforation / leak (use water-soluble contrast)

Acute Intestinal obstruction Patient unable to stand/weight bear Patient unable to turn over

Preparation (By modality)

Modality

Fasting (8 hours)*

Others

Plain Xrays

No

Mammogram

No

Ultrasound

For HBS and renal arteries

Barium swallow / meal

Yes

Barium enema

Yes, overnight

Bowel preparation 1-2 days before

IVU

Yes

Bowel preparation 1-2 days before

CT abdomen &/or pelvis

Yes

May require oral contrast 1-2 hours before

MRI

For liver, MRCP

Ideally in first 14 days of menses (will be arranged by the appt desk)

*- Implication: Keep the patient nil-by-mouth if you think you need the scan urgently! Back to top

Consent Taking and Risks of procedure When is written consent required? Varies between hospitals, but in general: 1. 2. 3. 4.

Age < 21 Pregnant women Women who have missed their period, or are in 2nd half of cycle (for high dose Ix) All interventional procedures (including biopsy)

Radiation dose 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?

Modality / Procedure

Equivalent of “normal” Risk of fatal cancer / death daily background radiation

Xray – Limbs

1 day

* Eating 2 bananas a week for 1 year

1 day

Xray – CXR

3 days

0.0003%

Xray – Skull

9 days

0.001% (1 in 100,000)

* Smoking 1 pack of cigarettes

-

0.001%

* Flight from Singapore to New York

1 month

Mammogram

2 months

0.005%

Xray - Abdomen, Pelvis, Spine

4 months

0.01% (1 in 10,000)

Tc-99m thyroid scan

6 months

IVU

1 year

0.03%

Barium swallow, meal, follow-through

1 – 1.5 years

0.03%

CT Head

10 months

0.03%

Tc-99m dynamic cardiac scan

2 years

0.05%

CT Chest, abdomen or pelvis

3.5 years

0.1% (1 in 1,000)

* Dying in a home accident each year

-

0.1% (1 in 1,000)

* Smoking 1 pack of cigarettes a day x 1 year -

0.0001% (1 in a million)

0.35%

i/v contrast (IVU and CT scan) (1) Allergic reaction / anaphylaxis - Idiosyncratic, just like all other drugs - Increased risk if (1)Multiple drug allergies (2)Recent asthma (<1 year ago) - Prevention: Prednisolone 10mg x 3 days before the scan (2) Extravasation - Definition: When the contrast is forced outside the vein - Background: About 50mls of contrast (which is as viscous as D50%) is injected as fast as 5mls/second under great pressure (If you don’t believe, get a 20ml syringe, some D50%, a blue plug, and see if you can inject everything out in 5 seconds!!). - Problem: Vein bursts (damn, got to reset the plug ;-) --> Contrast leaks out into tissue --> Draws water from surrounding tissues --> (1)Dehydration (& cell death)of surrounding tissues and (2)Compartment syndrome - Prevention: - i. Make sure plug works(They check, and you’ll just have to walk down to the

department to re-set it if it doesn’t work) - ii. Large bore (Pink/Green) plug for procedures requiring high-injection rates (generally anything vascular/arterial). - iii. If all else fails, blue plugs (but not in tiny finger veins!) may be acceptable for slowinjection rates (e.g. brain) - iv. PICCs are NEVER acceptable. (1) The tiny tip can blast off into the pulmonary arteries and (2) SVC rupture is not a pretty sight. - Treatment: - i. RICE (Rest, Ice-pack, Compress, Elevate extremity) - ii. Watch for compartment syndrome, especially if large volume (3) Contrast induced nephrotoxicity - Defined as a 25% increase in serum creatinine (does not always require dialysis though). - 1% in low risk patients - 10% in high risk patients (Diabetes, CCF, renal impairment, nephrotoxic drugs, age > 70yrs) - Prevention: - i. Any high risk factors: Pre-hydrate patient - ii. Renal impairment: Consider N-acetylcysteine (600mg bd x 2 day before and on day of scan) - iii. Space out contrast studies 72h apart, if possible (e.g. cancer staging) - iv. Consider non-contrast CT or alternate studies (e.g. US, MRI) - Paradoxically, patients whose kidneys have already failed and are on dialysis can ignore all the above. (4) Metformin-induced lactic acidosis - Metformin: Stop on the day, and 2 days after the scan. - Once again, do this proactively, if you think patient might be going for a contrast-CT soon! (Just don’t forget to convert to insulin/another OHGA, and to re-start it later!) (5) Breast feeding - Can scan as per normal, but no breast feeding x 24h after the scan Back to top

Radiological investigations FAQ Q: How do I know which scan to order? A: Specifying the modality(i.e. CT, MRI), organ of interest and including an adequate history is usually enough. For example, “CT lung” for “Lung cancer” vs “PE” vs “Interstitial lung disease” will get you three different scans, but as long as you include the diagnosis/history, there is no need to specify the exact technical details. Even suspected clinical diagnosis or the clinical indication, no matter how silly (e.g. “Hemoptysis for Ix”, “right sided rib pain”, “TB x 40 years ago”).

Q: What do I write in the “History” column? A: The keyword is “relevant”. Include whatever you think might be relevant to the scan, such as Presenting complaint, Duration, Possible causes (e.g. TB, prostate cancer), Physical findings/relevant investigations (e.g. axillary LN, pyloric ulcer on OGD, Hep B carrier), Treatment so far (e.g. Subtotal gastrectomy on 21/4/06), and any previous scans (e.g. U/S Feb 06: 4cm liver mass). Also, include any questions your consultant had (e.g. ?increase in size since 2004, ?anastomotic leak) so that they can be specifically answered in the report (Which may well save you a trip down to bug an irritated, overworked radiologist!).

Q: That’s a lot to write! What can I leave out? A: More is better than less, especially if you’re unsure! (It’ll save you an angry phone call from the radiologist, or even worse, having to explain to the patient why he needs another $350 CT scan of the same organ when he just had one yesterday, and to the consultant why the scan didn’t include the pelvic anastomosis…). But you can safely leave out irrelevant comorbidities (e.g. schizophrenia in a liver scan), and a summary of the history/physical exam is enough (e.g. “R breast lump x 2/12” vs “Admitted for # NOF. Incidental finding of R breast lump, 4.5cm, hard. L breast NAD. etc. etc.)

Q: Does the scan require i/v contrast (a.k.a Do I need to set a plug)? A: This is a tricky one. The full list is given below, but in general, the following require contrast: Most CT scans, including those looking at/for: - Tumour - Inflammation - Blood vessels Some MRI scans, especially those looking at - Tumour All interventional studies (except PermCath and Hickman lines, but including PICC lines) Common scans that do NOT require i/v contrast include: CT head for stroke, trauma CT spine and extremities for trauma CT KUB for renal/ureteric stones

Q: How do I arrange for an “urgent” scan? A: This varies by hospital, but here is a suggested approach:

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HEAD AND NECK /NEUROLOGY / NEUROSURGERY / ENT Xray: Skull Indication

Investigation

Vault #

Skull (AP,Lateral, Towne’s)

Maxilla #

Skull (AP, Lateral, OM)

Mandible #

Mandible X-xray

Orbit #

Orbit X-ray

Orbital foreign body Orbit X-ray + Look up/down views Sinusitis (chronic)

X-ray Paransal sinuses

Xray: Non-Skull Indication

Investigation

FB Throat

Neck xray,lateral (not C-spine)

Cervical spine trauma

C-spine xray (not Neck) +/- Swimmer / Lat pull-down for C7/T1

Parotid stone

Parotid xray (occlusal view)

Dental

Occlusal / OPG

Fluoroscopy Indication

Investigation

Swallowing assessment / ?Aspiration

(1)VFS if high % aspiration (2)Barium swallow (not gastrograffin)

FB throat / perforation / post-esophagect

(1)Gastrograffin swallow (2)NB: CT neck better for FB

Nasolacrimal duct stenosis

Dacrocystogram*

Salivary/Parotid duct stenosis

Sialogram*

* - Specialised, rarely performed investigation

Ultrasound Indication

Investigation

Thyroid lump / goitre U/S thyroid Young CVA

U/S carotids

CT Indication

Investigation

Contrast?

Stroke, hemorrhagic Head injury (see NICE criteria) CT brain

No

Meningitis

CT brain

Maybe

Fits, brain tumour, mets

CT brain

Yes

Chronic sinusitis

CT paranasal sinuses No

Hearing loss, conductive

CT temporal bone

No

Foreign body throat

CT neck

Maybe

MRI Indication

Investigation

Contrast?

Stroke, hyperacute (< 12 hours)

MRI brain (stroke protocol) NB: CT is better to exclude bleed

No

Stroke, brainstem Posterior fossa lesions MRI brain (more sensitive than CT) Maybe

Hearing loss, sensorineural

MRI IAM / MRI IAM screening

Yes

Retrobulbar mass, orbital tumor

MRI orbits

Yes

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RESPIRATORY / CARDIOLOGY / CARDIOTHORACIC SURGERY (CTS) Chest X-ray Indication

Investigation

Which side?

Basic CXR view

CXR (Erect)

Rib #

CXR (Oblique)

Same side as suspected # i.e. R oblique for R #

Localise lung lesion

CXR (Lateral)

Same side as lesion

Loculated effusion, or patient cannot sit CXR (Lateral up decubitus)

Same side as effusion i.e. R LD for R effusion

Small pneumothorax, sit up

Opposite side of pneumothorax i.e. R LD for L pneumothorax

Sternal #

or patient cannot

CXR (Lateral decubitus) Sternal Xray

General notes on CXR: The ‘standard’ CXR view is PA erect, but patient must be able to stand, and it cannot be done portable. AP Sitting is second best, followed by Supine. Lateral views are not routinely required. Ask yourself – “how will it affect management?”

Fluoroscopy Indication Investigation Diaphragmatic paralysis Fluoroscopic sniff test*

* - Specialised, rarely performed investigation

CT Indication Most lung conditions

Investigation

Contrast

CT Thorax / CT Chest

Interstitial lung disease

High resolution CT (HRCT) (NB: Slices are “skipped” – do not use for tumour No detection)

Aortic aneurysm / dissection

CT Aortogram / CT Thoracic aorta

Yes (High rate)

Pulmonary embolism (PE) CT PE / CT Chest (PE protocol) Coronary arteries CT Coronary Arteries / Cardiac CT

Yes (High rate) Yes (High rate)

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ABDOMEN / PELVIS / GASTROENTEROLOGY / HBS / UROLOGY / OBSTETRICS / GYNAECOLOGY / BREAST Abdomen X-ray Indication

Investigation

Standard AXR view

AXR (Supine)

Air-fluid levels

AXR (Erect) or (Lateral decubitus)

Free air under diaphragm CXR (Erect) or (AP Sit) Ureteric/bladder calculi

KUB

General notes on AXR: The ‘standard’ AXR does not always cover the pelvis. Order a KUB for pelvic pathology. Erect or decubitus views are not routinely required, even in IO. The supine view shows bowel distribution better, and free gas is better detected on the CXR.

Ultrasound Indication

Investigation

Preparation

Liver, gallbladder U/S liver / HBS

Fast x 8 hours

Kidneys

-

U/S kidneys

Notes Includes a quick look at kidneys

Kidneys & bladder U/S kidneys + bladder Needs to have a full bladder Not routinely ordered Renal arteries

U/S renal artery

Fast x 8 hours

Specialised investigation

Aorta

U/S abdominal aorta

Fast x 8 hours

CT preferred, if possible

Uterus/ovaries

U/S pelvis

Needs to have a full bladder May include endovaginal scan

Testes

U/S testes

-

General notes on ultrasound: Do NOT order "ultrasound abdomen" – only solid organs can be scanned, and the vast majority of the “abdomen” (including the bowel) is un-scannable. You will either get a rejected request, a call from an irate radiologist, or a vague scan of the region based on the clinical history in your form. They will never scan the entire “abdomen”, so you might as well be more specific.

Intravenous urogram (IVU) Indication

Investigation

Hydronephrosis, ?stones IVU

Preparation Fast overnight, bowel prep

General notes on IVU: IVU as an inpatient is usually suboptimal due to (1)poor bowel preparation or (2)infeasible to keep patient in hospital just for bowel prep. Alternatives include CT KUB (if looking for hydro and stones, or if renal function is poor) or CT urogram (if looking for renal function or pyelonephritis). Disadvantages of CT are higher cost and radiation dose.

Fluoroscopy Indication Esophagus / swallowing problem

Investigation Barium swallow

Requirements Be able to stand

Notes

Stomach / PUD / Be able to stand and Barium meal reflux / hiatus roll over. Barium follow-through Small bowel pathology Enteroclysis Large bowel

More invasive than followthrough, but better results

Be able to stand and roll over. No fecal incontinence.

Barium enema

Water-soluble / As for similar barium ?anastomotic leak gastrograffin swallow/ study. meal/ enema. Urethral stricture Ascending urethrogram Vesico-ureteric reflux

MCU

Post PCN

Check nephrostogram

Include op details (incl anastomosis type), and exact date study is required on form. Include op details if any Include op details if any

CT Indication Upper abdominal pathology Pelvic / gynae pathology

Investigation CT abdomen CT pelvis

Contrast Yes Yes

Entire abdominal cavity required CT abdomen + pelvis (abdo/pelvis) Yes Liver (Routine e.g. abscess) CT liver Yes Liver lesion ?HCC Liver HCC post-TACE

CT liver (triphasic) CT liver (plain + triphasic)

Yes (High rate) Yes

Pancreas Renal /ureteric stone

CT pancreas (fine cuts) CT KUB (may differ by hospital)

Yes No

Kidneys Kidneys, ureter, bladder

CT kidneys Yes (High rate) CT urogram(may differ by hospital) Yes (High rate) and Lasix

Abdominal aorta CT abdominal aorta Yes (High rate) Colon< td> CT colongraphy Yes and rectal gas General notes on CT: There are many, many different CT protocols for the abdomen (e.g. see CT liver above!). If unsure, it is best to state the organ of interest, and provide sufficient history, rather than guess blindly. Abdomen and Pelvis (in radiological protocol terminology) are completely different!! Your consultant may casually order a “CT abdomen” for “?sigmoid CA” or “abd pain for ix”, when what he really means is “CT Abdomen + Pelvis”. The radiographers protocoling the scan are not medically qualified, and may or may not catch your meaning, so make sure you fill the form in correctly! (As an aside, the main reason why the pelvis is not automatically included in a “CT abdomen” is due to the high radiation dose to the gonads and bowel.) Almost all abdo scans require fasting. If you’re clerking a patient and think he might need an urgent scan, keep him NBM!

MRI Indication Liver

Investigation Contrast MRI liver Yes

Bile duct stones MRCP Maybe Pancreas MRI pancreas Yes Kidneys

MRI kidneys Yes

General notes on MRI: There are many, many, many MRI protocols for the abdomen, even more than for CT. MRI liver for HCC alone has 12 sequences. Don’t bother trying to specify them, just state the organ of interest, and provide sufficient history.

Breast Indication Screening Evaluation of breast lump

Investigation Mammogram Ultrasound + Mammogram

Note

Biopsy of lump Ultrasound guided bx Specialised investigation Biopsy of lesion on mammogram Mammotome / Stereotactic biopsy Specialised investigation Implant rupture

MRI breast

Specialised investigation

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ORTHOPAEDICS / SPINE / EXTERMITIES / TRAUMA General notes on orthopaedic xrays: Othopaedic xrays are really easy to order – if you can name the bone that is likely to be fractured, then that's the xray you ask for! So go ahead, and order xrays according to where you think the problem is. Using radio-opaque markers, especially for foreign bodies, is highly recommended. If you can’t personally accompany the patient and put the marker – just write a “with marker” on the xray form, and make sure the patient can point out the site of the problem!

Plain x-rays Skull

See head and neck

Spine Cervical spine Cervical spine (Swimmers view) or (Lateral pulldown) Open-mouth / Odontoid views Thoracic spine Lumbar spine Oblique views of above Coccyx

Upper limb Clavicle Scapula Shoulder Humerus Elbow Forearm or radius/ulna Wrist Scaphoid Hand x finger

Pelvis

Pelvis (AP) Pelvis (Inlet / Outlet) Judet views (for acetabulum)

Lower limb Hip Femur Knee Skyline (Patella) Tib/Fib Ankle Calcaneum Foot

CT / MRI for tumour or trauma Specify region as above. 3D-reconstructions are not performed by default at most hospitals, so specify if your consultant needs them.

Ultrasound Indication Rotator cuff pathology

Investigation U/S shoulder

Carpal tunnel, cysts, neuroma U/S wrist DDH / CDH (< 4-6 mths)

U/S hip

MRI Spine (specify region, level, and side of symptoms) Shoulder* Wrist* Hip Knee Ankle General notes on MRI: While MRI is highly detailed, it is not cheap, and before ordering one, ask yourself if it will affect subsequent management. * - These procedures may involve use of intra-articular contrast injection (arthrogram), which depends on indication for the scan, and varies between hospitals. Once again, include all relevant details on the request form (esp. suspicion of tears and any previous operation) and advise patient he may require an injection. Back to top

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