This article provides examples and guidance on how diagnostic certainty should be set rather than an exhaustive list of every condition. When available, diagnostic certainty must be set according to published diagnostic criteria (often found in the Diagnosis section of the relevant Radiopaedia article) or based on pathology results. The editor-in-chief retains responsibility for setting diagnostic certainty when there is debate about the appropriate level.

Tumours and tumour-like lesions

Histopathology is routinely required for publication. Cases with the diagnostic certainty set at “Probable” or “Possible” are unlikely to be accepted, particularly if they involve a common condition (e.g., meningioma).

Cytology results that are "suspicious for" a condition will have a diagnostic certainty set at "Probable" or "Possible" depending on the clinical history and imaging findings.

Cases labelled ‘mass’ or ‘tumour’ in the title, e.g., "gastric mass" or "soft tissue tumour," need careful review as they are often unsuitable for publication due to limited educational value.

Exceptions occur where histopathology is feasible but not routinely obtained; in these cases, “Almost certain” is appropriate (or very occasionally "Certain") where very typical imaging findings are observed with typical demographics and clinical presentation, for example:

• “Do not touch” bone lesions, e.g. fibrous cortical defect (case)

• mucinous neoplasms, e.g. IPMN (case)

• some soft tissue tumours, e.g. lipoma (case)

• congenital cysts, e.g. Rathke cleft cyst (case)

• vascular malformations, e.g. cerebral AVM (case)

Infection

Proof of the infective pathogen is required for less common infections or where the infection could mimic a different disease process to meet the "Certain" or "Almost certain" criteria for publication. For example:

• mucormycosis (case)

• peritoneal tuberculosis (case)

• congenital syphilis (case)

Inflammatory conditions

Some conditions with pathognomonic imaging findings can be set to “Certain”, e.g. epiploic appendagitis (case).

Supportive data (e.g. inflammatory markers, antibodies) and/or histopathology in selected cases is required to meet the “Certain” or “Almost certain” criteria for publication, e.g. psoriatic arthritis (case).

Neurological conditions

Neurological conditions (e.g. dementias, metabolic/toxic conditions) require typical imaging findings supported by in-depth clinical information, clinical exam results (e.g. MMSE), laboratory results, genetic testing, and/or follow-up imaging to meet the "Certain" or "Almost certain" criteria for publication. For example:

• frontotemporal dementia (case)

• herion-induced leukoencephalopathy (case)

Congenital conditions

Typical imaging findings usually will need to be supported by additional data, e.g. additional clinical information, results of genetic testing, biochemical results, to meet the "Certain" or "Almost certain" criteria for publication. For example:

• congenital hypothyroidism (case)

• callosal dysgenesis (case)

• achondroplasia (case)

• schizencephaly (case)

Practical points

• the less common a particular clinical picture is, the more evidence often needed to substantiate the diagnosis ¹

  • "It isn't about how certain you are, but how certain the reader is going to be after reading the case." - Frank Gaillard, Founder, Radiopaedia

• additional clinical information, such as specific management of a condition or follow-up, might be helpful to increase the diagnostic certainty, e.g. adrenal haemorrhage with a follow-up CT showing resolution will increase the diagnostic certainty from “Probable” to “Certain”

• pathognomonic and unequivocal imaging appearance require a very high specificity, positive predictive value, and a very low false positive rate - appropriate references should support this