Multimodal MRI recommended to prevent brain mass misdiagnosis

By Lucy Piper, Senior medwireNews Reporter

T2*-weighted gradient recalled echo (T2*GRE) or susceptibility-weighted imaging (SWI) sequences should be performed during the diagnosis of brain masses to rule out pseudotumoural presentation of cerebral amyloid angiopathy-related inflammation (CAA-I), say researchers.

They found that such sequences showed multiple cortical and subcortical microbleeds in all of the 28 cases they studied. And it should be considered particularly in elderly patients with cognitive impairment who have one or several nonenhancing space-occupying infiltrative white matter lesions on magnetic resonance imaging (MRI).

These features, although not specifically associated with CAA-I, were commonly seen in affected patients, with 85% over the age of 60 years, 65% cognitively impaired and 93% showing patchy or confluent hyperintense T2/FLAIR lesions without contrast enhancement on MRI.

The findings are important given that CAA-I is often incorrectly diagnosed as brain neoplasms in the pre-operative setting, resulting in futile resections and biopsies, say Jérôme Honnorat (Université de Lyon–Université Claude Bernard Lyon, France) and co-researchers.

They reviewed the medical records of five newly diagnosed patients, aged a median of 70 years who were initially suspected of having brain cancer (lymphoma, low-grade glioma and gliomatosis cerbri) based on having cognitive impairment and MRI evidence of unilateral or bilateral asymmetric T2/FLAIR hyperintensities in the supratentorial white matter with loco-regional mass effect and no parenchymal enhancement.

Following subsequent multimodal MRI, however, T2*-GRE sequences showed extensive cortical and subcortical microbleeds in all patients, primarily supratentorial, and marginal siderosis in four patients.

“[T]he primary reason for the misinterpretation of CAA-I imaging findings as CNS [central nervous system] neoplasm was the absence of T2*-GRE/SWI sequences on initial imaging”, says the team.

In centres that already include T2*-GRE/SWI sequences in their standard MRI protocols, the researchers urge clinicians evaluating patients with suspected brain tumours to actively review them.

“Centers that do not include those sequences should strongly consider adding them”, they add in Neurology.

The team corroborated their initial findings by reviewing 23 previously published cases of patients with CAA-I that was histologically confirmed in 21. Standard MRI images gave similar findings to those of the five case series patients and were initially interpreted as CNS neoplasm, leading to biopsy in 74% of patients, which was nondiagnostic in 14%, and surgical resection in 26%.

Again, the researchers believe the main reason for the misinterpretation of the imaging findings was the absence of T2*-GRE sequences.

Six of the patients underwent T2*-GRE or SWI sequences – two before surgery and four during follow-up – and all showed evidence of multiple microbleeds.

Of the 11 patients in total who underwent T2*-GRE sequences, five met the criteria for definite CAA-I and six for probable CAA-I.

After diagnosis, 15 patients received steroids with or without cyclophosphamide and a favourable outcome was more likely with than without treatment, at rates of 78% versus 58%.

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