Table 1.
Examples of imaging stratified by necessity for ICM
| Tier 1 | Tier 2 | Tier 3 | Tier 4 |
|---|---|---|---|
| Multimodal code stroke CT1 | Diverticulitis | Occult Infection | Asymptomatic annual staging |
| Subarachnoid Haemorrhage1 | Appendicitis | Pulmonary Embolism | Pulmonary nodules <8 mm |
| Suspected aortic dissection | Bowel Obstruction/perforation | Oncology Staging | Low‐risk incidental findings workup |
| Level 1 Trauma | Fluid collections | Focal Liver lesions | Claudication |
| Oncology initial staging2 | Chest Imaging | Cerebral venous sinus thrombosis | |
| Oncology restaging3 | Selected oncology/haematology studies5 | Biliary/renal obstruction | |
| Active lower GI bleed4 | Trauma—clinically stable | TIA workup | |
| Acute Mesenteric Ischaemia | |||
| Clinical Trial Patients (where CT is mandated by the trial) |
Modified from Cavallo et al, practice management strategies for imaging facilities facing an acute iodinated contrast media shortage, AJR 2022 preprint https://doi.org/10.2214/AJR.22.27969. Tier 1 – CT with contrast necessary. Tier 2 – unenhanced CT is feasible. Tier 3 – alternative modalities can be used, for example, NM, PET, US, CEUS and MRI. Tier 4 – study can be delayed. 1 – Contrast is necessary during phase 1 and 2. Once contrast supplies are critical, these can be replaced with MRI (with DWI and perfusion‐weighted images for ischaemic stroke). 2 – where the patient is potentially curable, could be enrolled in a trial or to guide biopsy. 3 – following neoadjuvant therapy where the patient is a potential resection candidate. 4 – Upper GI bleed should have an endoscopy, and if that fails discussion with an IR consultant. 5 – patients with measurable disease without needing contrast, based upon prior studies and no clinical suspicion of recurrence/disease progression.