Contribution of arterial spin-labelling MRI in a case with immune reconstitution inflammatory syndrome

Abstract

Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS), which occurs most often in HIV-infected patients, is an exacerbation of inflammatory reactions related to opportunistic infections as well as primary CNS malignancies both of which mostly occur in HIV-infected patients. However, differential diagnoses are challenging both clinically and radiologically. We describe a patient with CNS-IRIS due to toxoplasmosis whose ¹¹C-methionine uptake suggested lymphoma but whose arterial spin-labelling MRI led to the correct diagnosis.

Keywords: Neuroimaging; Radiology.

Figure 1

T2WI shows a hyperintense nodular lesion with mild surrounding oedema at the right frontoparietal lobe (a, arrowhead). Postcontrast T1WI shows a solid enhanced area (b, arrowhead) with an increased signal intensity on DWI (c, arrowhead) in conjunction with an ADC decrease (d, arrowhead). A low-CBF lesion is observed on ASL-MRI (e, arrowhead), but MET-PET 60 min after the injection shows a high uptake (f, arrowhead). ADC, apparent diffusion coefficient; ASL, arterial spin-labelling; CBF, cerebral blood flow; DWI, diffusion-weighted image; MET, ¹¹C-methionine; T1WI, T1-weighted image; T2WI, T2-weighted image.