Computed Tomography (CT) Prioritization
Scope
This guideline summarizes suggested wait times for common indications where Computed Tomography (CT) is the recommended first imaging test. The purpose is to inform primary care practitioners of how referrals are prioritized by Radiologists and Radiology departments across the province. This guideline is an adaptation of the British Columbia Radiological Society (BCRS) CT Prioritization Guidelines (2013).1 Management of the listed clinical problems is beyond the scope of thisguideline. However, in some cases, notes and alternative tests are provided for additional clinical context. Primary care practitioners are encouraged to consult a Radiologist if they have any concerns or questions regarding which appropriate imaging test to choose for a problem. If in doubt consult with a Radiologist and review provincial guidance materials.2
Background
The 2013 BCRS CT Prioritization Guidelines were developed to provide imaging departments with a consistent, provincial approach to prioritizing commonly ordered CT tests according to suggested maximum wait times. The BCRS guidelines were developed by consensus and are based on BC expert opinion with representation of Radiologists from across the province.
Several considerations apply:
- These are guidelines, and as such, are designed to apply in general terms. They are not intended to replace clinical judgement or practitioner-to-practitioner discussion.
- Prioritization levels were selected to match other similar guidelines for Magnetic Resonance Imaging (MRI) and Ultrasound (US) and are typically assigned by Radiologists rather than referring practitioners.
- These guidelines should not be applied rigidly to each case, as varying clinical factors may shift an indication from one priority level to another.
- Access to CT and the ability to respond to CT requests will depend on resources and local availability.
- Providing detailed patient information is essential to aid with the prioritization process.
- The clinical topics included in this guideline represent broad examples, and do not encompass all possible scenarios or all requirements for CT examinations.
Priority Level Definitions
The priority levels defined below (Table 1) are in alignment with the Canadian Association of Radiologists national designation Five Point Classification System.3
Table 1: Priority Level Definitions
Priority Level | Clinical Example | Maximum Suggested Wait Time |
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P1 | An examination immediately necessary to diagnose and/or treat life-threatening disease. Such an examination will need to be done either stat or not later than the day of the request. | Immediately to 24 hours |
P2 | An examination indicated within one week of a request to resolve a clinical management imperative. | Maximum 7 calendar days |
P3 | An examination indicated to investigate symptoms of potential importance. | Maximum 30 calendar days |
P4 | An examination indicated for long-range management or for prevention. | Maximum 60 calendar days |
P5 | Timed follow-up exam or specified procedure date recommended by Radiologist and/or clinician. |
Source: Adapted from the Canadian Association of Radiologists National Maximum Wait Time Access Targets for Medical Imaging.
Prioritization of Potential Diagnoses
CT is widely indicated for and includes but is not limited to the following4 (see separate sections for specific clinical indications):
- Cerebrovascular accidents
- Imaging in trauma
- Staging and monitoring of malignancies
- Imaging of the chest and abdominal conditions
- Providing pre-operative assessment of complex masses
- Assessing post-operative complications
- Imaging guided intervention: injections, fine needle aspiration, core biopsy and fluid drainage
The following potential diagnoses, where CT is the recommended first test, are grouped according to body system and then further subdivided into priority levels. For each system, an overview table is presented followed by a more detailed table outlining additional notes and alternative tests where CT may be less appropriate due to ionizing radiation exposure.
For CT also consider the patient risk of radiation exposure, refer to Appendix A: Radiation Exposure.
Referring practitioners should include clear, pertinent clinical history on radiology requisitions to assist the triaging/prioritizing of examinations and interpretation of images and may consider noting the priority directly on the requisition where possible.
Head and Neck
Head and Neck: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Head and Neck: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Stroke / Transient Ischemic Attack (TIA) |
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Acute thunderclap headache acute: suspected acute subarachnoid hemorrhage |
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P2 | Postoperative neurosurgical patients |
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Headaches (recently worsening or neurological findings), red flags |
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P3 | Pulsatile tinnitus |
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Acute Psychosis – 1st episode |
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P4 | Postoperative follow-up (i.e. meningioma resection, pituitary adenoma Rx) |
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Appropriate Imaging for Common Situations in Primary and Emergency Care5
Headaches Imaging is not recommended unless red flags are present |
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Consider imaging in the following red flag situations:
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Think twice before requesting head CT for:
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Spine
Spine Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Spine: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Acute myelopathy (cord compression, cauda equina syndrome) |
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Discitis / osteomyelitis, suspected |
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P2 | Back pain with red flags |
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P3 | Persistent back pain of more than six weeks, with or without objective neurological findings (radiculopathy) |
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Appropriate Imaging for Common Situations in Primary and Emergency Care5
Back Pain Imaging is not recommended unless red flags are present |
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Consider imaging in the following red flag situations:
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Note: Back pain may be due to conditions other than spinal and may warrant imaging of the abdomen or pelvis.
Musculoskeletal/Extremity
Musculoskeletal/Extremity: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Musculoskeletal/Extremity: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Acute vascular insufficiency to extremity |
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P2 | Tumor musculoskeletal - biopsy |
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P3 | Assess progress of fracture healing |
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P4 | Characterization of arthritis, gout |
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Evaluation of chronic vascular insufficiency |
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Chest
Chest: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Chest: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Acute pulmonary embolism (in pregnancy, see notes) |
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P2 | Acute interstitial lung disease |
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Evaluating atypical lung or pleural infection and symptomatic patients with a cough |
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High clinical suspicion for pneumonia/infection with a normal chest radiograph |
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Clinical deterioration if lung Transplant or immunocompromised |
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P4 | Evaluation for lung cancer in high risk individuals |
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P5 | Follow-up of small pulmonary nodule |
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Stable aneurysm/dissection follow-up |
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Cardiac
Cardiac: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Cardiac: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
---|---|---|
P1 | Acute/ unstable infective endocarditis |
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P2 | Chest pain (typical / atypical in high risk patient) |
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Stable suspected infective endocarditis |
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Myo-/pericarditis (if MRI is contraindicated) |
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Ventricular assist device evaluation |
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P3 | Atypical chest pain in low risk patient (CCTA) |
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CT myocardial perfusion for ischemia (MRI contraindicated) |
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Valve replacement workup (TAVR / TMVR) |
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Abdomen and Pelvis
Abdomen and Pelvis: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Abdomen and Pelvis: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Abdominal trauma |
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Abdominal aortic aneurysm rupture |
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Appendicitis |
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Suspected bowel perforation |
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Cholecystitis or biliary obstruction |
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Pelvic inflammatory disease |
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P2 | Solid organ masses (intra-abdominal or pelvic for characterization) |
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Renal or liver transplant complications |
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P3 | Adrenal mass, work-up of incidental finding |
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P4 | Colonic polyps |
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Hernia without acute symptoms |
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Renal stone burden |
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Renal artery stenosis |
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P5 |
Follow-up of treated malignancy |
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Pediatric
Consider alternatives to CT, if appropriate, to reduce radiation exposure for pediatric patients. See Appendix A: Radiation Exposure, for more information.
Pediatric: Overview
P1 | P2 | P3 | P4 | P5 |
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Immediately to 24 hours | Max 7 calendar days | Max 30 calendar days | Max 60 calendar days | |
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Pediatric: Notes and Alternative Tests
Potential Diagnosis | Notes and Alternative Tests | |
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P1 | Non-accidental trauma suspected, with acute neurological syndrome |
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Stroke |
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Anterior Mediastinal Mass |
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P2 | Chest, Abdominal mass evaluation and staging |
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Congenital Heart Disease |
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P3 | Headache with red flags |
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P4 | Craniosynostosis |
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Congenital Lung Anomaly |
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Resources
- American College of Radiology Appropriateness Criteria
https://www.acr.org/Quality-Safety/Appropriateness-Criteria - BC Cancer, Family Practice Oncology Network Guidelines and Protocols
http://www.bccancer.bc.ca/health-professionals/networks/family-practice-oncology-network/guidelines-protocols - BC Guidelines Appropriate Imaging for Common Situations in Primary and Emergency Care
https://www2.gov.bc.ca/gov/content/health/practitioner-professional-resources/bc-guidelines/appropriate-imaging - Canadian Association of Radiology, Diagnostic Imaging Referral Guidelines (2012)
http://www.car.ca/en/standards-guidelines/guidelines.aspx - Canadian Association of Radiologists Radiology Resumption of Clinical Services (2020)
https://car.ca/wp-content/uploads/2020/05/CAR-Radiology-Resumption-of-Clinical-Services-Report_FINAL-2.pdf - CAR Standard for Magnetic Resonance Imaging (2011)
https://car.ca/wp-content/uploads/Magnetic-Resonance-Imaging-2011.pdf - Choosing Wisely Radiology Recommendations for Radiology:
http://www.choosingwiselycanada.org/wp-content/uploads/2014/04/Radiology.pdf - Essential Imaging, BC Patient Safety and Quality Council
https://bcpsqc.ca/improve-care/medical-imaging/ - HealthlinkBC, Radiation Exposure: Risk and Health Effects
https://www.healthlinkbc.ca/health-topics/abl0600 - Image Gently: Pediatric Radiology & Imaging
https://www.imagegently.org/ - Image Wisely
https://www.imagewisely.org/ - Medical Imaging Advisory Committee. Provincial Guidance for Medical Imaging Services within British Columbia During the Pandemic Phases (June 2020).
http://www.bccdc.ca/Health-Professionals-Site/Documents/COVID19_MedicalImagingGuidePractitioners.pdf - National Cancer Institute
https://www.cancer.gov/about-cancer/causes-prevention/risk/radiation/pediatric-ct-scans - RACE line – Rapid Access to Consultative Services, includes Radiology consultation services:
http://www.raceconnect.ca/ - Radiology Info for Patients
https://www.radiologyinfo.org/ - The Fleischner Society Publications
https://fleischner.memberclicks.net/white-papers
Appendices
References
- BC Radiological Society. CT Prioritization Guideline (2013)
- Medical Imaging Advisory Committee. Provincial Guidance for Medical Imaging Services within British Columbia During the Pandemic Phases (June 2020).
http://www.bccdc.ca/Health-Professionals-Site/Documents/COVID19_MedicalImagingGuidePractitioners.pdf - Canadian Association of Radiologists National Maximum Wait Time Access Targets for Medical Imaging (MRI and CT).
https://car.ca/wp-content/uploads/car-national-maximum-waittime-targets-mri-and-ct.pdf - International Radiology Quality Network. Referral Guidelines for Diagnostic Imaging: A Supporting Tool for Healthcare Professionals in the Selection of Appropriate Procedures. 2017.
http://www.isradiology.org/quality-guidelines - BC Guidelines. Appropriate Imaging for Common Situations in Primary and Emergency Care
https://www2.gov.bc.ca/gov/content/health/practitioner-professional-resources/bc-guidelines/appropriate-imaging
This guideline is based on expert BC clinical practice current as of the effective date. This guideline was developed by the Guidelines and Protocols Advisory Committee based on the British Columbia Radiological Society Computed Tomography Prioritization Guidelines (2013), and approved by the Medical Services Commission.
THE GUIDELINES AND PROTOCOLS ADVISORY COMMITTEE
The principles of the Guidelines and Protocols Advisory Committee are to:
Contact Information: Guidelines and Protocols Advisory Committee PO Box 9642 STN PROV GOVT Victoria BC V8W 9P1 Email: hlth.guidelines@gov.bc.ca Website: www.BCguidelines.ca Disclaimer The Clinical Practice Guidelines (the guidelines) have been developed by the BC Cancer Primary Care Program, Family Practice Oncology Network and the Guidelines and Protocols Advisory Committee, on behalf of the Medical Services Commission. The guidelines are intended to give an understanding of a clinical problem, and outline one or more preferred approaches to the investigation and management of the problem. The guidelines are not intended as a substitute for the advice or professional judgment of a health care professional, nor are they intended to be the only approach to the management of clinical problem. We cannot respond to patients or patient advocates requesting advice on issues related to medical conditions. If you need medical advice, please contact a health care professional. |