General Principles & Governance
Imaging Protocols for CT and MRI · v2.1 · March 2026
Authorisation
All imaging requests must be justified by an IR(ME)R practitioner (radiologist or radiographer)
IR(ME)R 2017 (as amended 2024) Justification Requirement
Every CT must be individually justified under IR(ME)R 2017 (as amended 2024) — benefit must outweigh risk. Clinical indication and relevant clinical information must be documented on the request.
MRI Safety & Governance
MRI is governed by MHRA Safety Guidelines v4.3 (2021), not IR(ME)R. Each scanner requires a designated MR Responsible Person (MRRP) and access to an MR Safety Expert (MRSE).
Gadolinium-based contrast agents (GBCAs): All MRI contrast requires eGFR assessment. Macrocyclic agents preferred per MHRA guidance. Patients with eGFR <30 require senior radiology review. Risk of nephrogenic systemic fibrosis (NSF) with linear agents in renal impairment.
MRI in pregnancy: MRI may be used at any stage of pregnancy when clinically indicated (no ionising radiation). Gadolinium should be avoided unless the benefit clearly outweighs the risk — macrocyclic agents only, with senior radiology approval.
Implant safety: All patients must be screened for MRI-incompatible implants, devices, and foreign bodies prior to scanning. Refer to local MRI safety questionnaire and implant database.
Cross-Cutting Guidance
Governing Guidelines
| Reference | Guideline Title | Year | Link |
|---|---|---|---|
| NICE NG232 | Head Injury(Replaces CG176) | May 2023 | View ↗ |
| NICE NG128 | Stroke and TIA(Replaces CG68) | 2019, updated 2022 | View ↗ |
| NICE TA990 | Tenecteplase for Acute Ischaemic Stroke | July 2024 | View ↗ |
| NICE NG228 | Subarachnoid Haemorrhage | 2022 | View ↗ |
| NICE NG41 | Spinal Injury | 2016 | View ↗ |
| NICE NG234 | Spinal Metastases and MSCC(Replaces CG75) | 2023 | View ↗ |
| NICE NG59 | Low Back Pain and Sciatica | 2016, updated 2020 | View ↗ |
| NICE NG158 | Venous Thromboembolic Diseases including PE | 2020 | View ↗ |
| NICE CG95 | Chest Pain of Recent Onset | 2010, updated November 2016 | View ↗ |
| NICE NG122 | Lung Cancer | 2019, updated 2024 | View ↗ |
| NICE CG163 | Idiopathic Pulmonary Fibrosis | 2013 | View ↗ |
| NICE NG39 | Major Trauma | 2016 | View ↗ |
| NICE NG208 | Heart Valve Disease | 2021 | View ↗ |
| NICE NG156 | Abdominal Aortic Aneurysm | 2020 | View ↗ |
| NICE CG147 | Lower Limb PAD | 2012, updated 2020 | View ↗ |
| NICE NG147 | Diverticular Disease | 2019 | View ↗ |
| NICE NG104 | Pancreatitis | 2018, updated 2020 | View ↗ |
| NICE CG188 | Gallstone Disease | 2014 | View ↗ |
| NICE NG85 | Pancreatic Cancer | 2018 | View ↗ |
| NICE NG118 | Renal and Ureteric Stones | 2019 | View ↗ |
| NICE NG151 | Colorectal Cancer | 2020 | View ↗ |
| NICE CG122 | Ovarian Cancer | 2011 | View ↗ |
| NICE NG131 | Prostate Cancer | 2019 | View ↗ |
| NICE NG73 | Endometriosis | 2017, updated 2024 | View ↗ |
| NICE NG236 | Cervical Cancer | 2023 | View ↗ |
| NICE NG129 | Crohn's Disease | 2019 | View ↗ |
| NICE NG12 | Suspected Cancer: Recognition and Referral | 2015, updated 2026 | View ↗ |
| NICE NG101 | Early and Locally Advanced Breast Cancer | 2018 | View ↗ |
| NICE CG164 | Familial Breast Cancer | 2013 | View ↗ |
| NICE CG124 | Hip Fracture Management | 2011, updated 2023 | View ↗ |
| NICE NG38 | Fractures (Non-complex) | 2016 | View ↗ |
| NICE NG97 | Dementia | 2018 | View ↗ |
| NICE NG217 | Epilepsies | 2022 | View ↗ |
| NICE NG220 | Multiple Sclerosis | 2022 | View ↗ |
| NICE NG99 | Brain Tumours (Primary) and Brain Metastases | 2018 | View ↗ |
| NICE CG150 | Headaches in Over 12s | 2012 | View ↗ |
| NICE NG98 | Hearing Loss in Adults | 2018 | View ↗ |
| NICE NG36 | Cancer of the Upper Aerodigestive Tract | 2016 | View ↗ |
| NICE NG145 | Thyroid Disease | 2019 | View ↗ |
| NICE NG100 | Rheumatoid Arthritis | 2018 | View ↗ |
| NICE CG102 | Bacterial Meningitis in Children | 2010, updated 2015 | View ↗ |
| RCR iRefer | Making the Best Use of Clinical Radiology, 8th edition | 2017, continuously updated | View ↗ |
| RCR/RCEM | Acute Aortic Syndrome Imaging Pathway | January 2024, revised March 2025 | — |
| RCR BFCR(19)4 | Guidance on Gadolinium-based Contrast Agents | 2019 | — |
| RCR CIB | MRI Provision for Cauda Equina Syndrome | February 2023 | — |
| RCR/RCOG | Ionising Radiation and Pregnancy | 2021 | — |
| RCR/SCoR/RCPCH | Radiological Investigation of Suspected Physical Abuse in Children | 2017, revised 2018 | — |
| RCR/RCEM | Emergency CT and IV Contrast(Joint Advisory Statement) | Current | — |
| NHS TLHC | Targeted Lung Health Check Programme | Current | — |
| NHS TDP | Timed Diagnostic Pathway — Head and Neck Cancer | 2024 | — |
| NHS AAA Screening | AAA Screening Programme | Current | — |
| IR(ME)R 2017 | Ionising Radiation (Medical Exposure) Regulations 2017 | SI 2017/1322 | View ↗ |
| IR(ME)R 2024 Amendment | IR(ME)R Amendment Regulations 2024 | SI 2024/896 | View ↗ |
| MHRA MRI Safety | Safety Guidelines for MRI Equipment in Clinical Use, v4.3 | 2021 | — |
| BASS | Standards of Care for Cauda Equina Syndrome | 2018 | — |
| GIRFT | National Cauda Equina Syndrome Pathway | 2023 | — |
| BSG | Guidelines for Management of IBD in Adults | 2019 | — |
| BAHNO/ENT-UK | National MDT Guidelines: Salivary Gland Tumours | 2016 | — |
| BOA BOAST | ACL Injuries Management | 2020 | — |
| ECCO/ESGAR | Cross-sectional Imaging in IBD | Updated | — |
| ESC | Guidelines on Cardiomyopathies | 2023 | — |
| ESC | Guidelines on Myocarditis | 2025 | — |
| ESC | Guidelines on Congenital Heart Disease in Adults | 2020 | — |
| ESO | Cerebral Venous Thrombosis Diagnosis and Treatment | 2017 | — |
| EASL | Clinical Practice Guidelines: Hepatocellular Carcinoma | 2018 | — |
| RCP | National Clinical Guideline for Stroke, 5th edition | 2023 | — |
| IAP-APA | Evidence-based Guidelines for Acute Pancreatitis | 2013 | — |
| WSES | Guidelines for Acute Mesenteric Ischaemia | 2017 | — |
| ATS/ERS/JRS/ALAT | IPF Evidence-based Guidelines | Updated 2022 | — |
Applicability
These protocols are applicable to all clinical settings (ED, Inpatient, Outpatient). Age-specific criteria are noted where applicable.
Contrast Administration
No blood tests required for IV iodinated contrast authorisation in emergency CT — per joint RCEM/RCR advisory statement. eGFR thresholds apply for gadolinium-based MRI contrast agents.
Disclaimers
Not clinical advice. ProtocolPulse is a reference tool only. It does not constitute clinical advice and does not replace the professional judgement of a qualified clinician, radiographer, or radiologist. All imaging decisions remain the responsibility of the authorising IR(ME)R practitioner.
Guidelines may have been updated. All guidelines referenced are current at the stated version date (March 2026). Guidelines are subject to revision by NICE, RCR, and other issuing bodies at any time. Users must verify all criteria against the latest published source before relying on them clinically.
Use common sense. The criteria presented are summaries of source guidelines. They do not capture every clinical nuance. Users must apply professional judgement and common sense, and refer directly to the full cited guideline text if any content appears inconsistent with their clinical knowledge or local practice.
Individual patient factors. This tool does not account for individual patient contraindications, allergies, implant status, renal function, pregnancy, or any clinical circumstance not captured in the published guideline criteria.
IR(ME)R responsibility. ProtocolPulse does not fulfil, replace, or substitute for any employer obligation under IR(ME)R 2017, including the requirement to provide referral guidelines to referrers under Regulation 6(5)(a). It is a supplementary reference aid only.
Medical device status. ProtocolPulse has not been assessed or registered as a medical device under the UK Medical Devices Regulations 2002 or the MHRA's Software and AI as a Medical Device framework. Before deployment in a clinical NHS setting, the responsible organisation must conduct an MHRA classification assessment.
Created with the assistance of AI. The clinical content, protocol criteria, and guideline summaries in ProtocolPulse v2.1 were developed with the assistance of Claude (Anthropic). All clinical criteria have been cross-referenced against the cited source guidelines. AI-assisted content may contain errors or omissions — users should apply common sense and verify against the original cited sources.
All Protocols (29)
- CTCT Head — Head Injury (adults ≥16)
- CTCT Head — Head Injury (children <16)
- CTCT Head — Stroke Thrombolysis
- CTCT Head — Stroke: Non-Thrombolysis / Thrombectomy
- CTCT Head — Other Acute Indications
- MRIMRI Brain — Outpatient
- CTCT Cervical Spine [ED]
- MRIMRI Cervical Spine [ED/INPATIENT/OUTPATIENT]
- MRIMRI Lumbar Spine — Low Back Pain [OUTPATIENT]
- MRIMRI Lumbar Spine — Cauda Equina Syndrome [ED/INPATIENT]
- CT/MRICT/MRI Whole Spine — MSCC [INPATIENT]
- CT/MRICT/MRI Orbits & Sinuses
- CT/MRICT/MRI Neck
- CTCT Thorax
- CTCTPA — Pulmonary Embolism
- CTCT Coronary Angiography
- CTCT Aorta — Acute Aortic Syndrome
- MRICMR — Cardiac MRI
- CTCT Abdomen and Pelvis
- MRIMRI Pelvis & Abdomen
- CT/MRICT/MRI Hepatobiliary & Pancreas
- CTCT KUB — Renal Calculus
- CTCT Urogram — Haematuria
- CTCT Vascular
- CTCT MSK
- MRIMRI MSK
- CTCT Breast Staging
- MRIMRI Breast
- CTCT Trauma Series (Head to mid-thigh)