Response to: 'Neuropsychiatric lupus or not? Cerebral hypoperfusion by perfusion-weighted MRI in normal-appearing white matter in primary neuropsychiatric lupus erythematosus' by Papadaki et al' by Wallace. Issue 1 (23rd January 2018) - Papadaki, Efrosini; Fanouriakis, Antonis; Kavroulakis, Eleftherios; Karageorgou, Dimitra; Sidiropoulos, Prodromos; Bertsias, George; Simos, Panagiotis; Boumpas, Dimitrios T