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Abstract High-signal cortical lesions are observed on T1-weighted images in cases of brain infarct. Histological examination has demonstrated these to be "cortical laminar necrosis", without haemorrhage or calcification. We report serial MRI in this condition in 12 patients with brain infarcts. We looked at high-signal lesions on T1-weighted images, chronological changes in signal intensity and contrast enhancement. High-signal cortical lesions began to appear about 2 weeks after the ictus, were prominent at 1-2 months, then became less evident, but occasionally remained for up to 1.5 years. They gave high signal or were isointense on T2-weighted images and did not give low signal at any stage. Contrast enhancement of these lesions was prominent at 1-2 months, and less apparent from 3 months, but was seen up to 5 months.
Keywords Brain infarcts * Cortical laminar necrosis * Magnetic resonance imaging
Introduction
High intensity cortical lesions are observed on Tlweighted MRI in brain infarcts [1, 2, 3]. These can be cortical laminar necrosis, haemorrhagic infarcts or a combination of the two. Cortical laminar necrosis represents to neuronal ischaemia accompanied by gliosis and layered deposition of fat-laden macrophages [4, 5]. We investigated patients with cortical laminar necrosis with special reference to chronological changes in signal intensity and contrast enhancement. We used a variety of MRI techniques to analyse the nature of and characteristic chronological changes in such lesions.
Patients and methods
From March 1998 to February 2001, reviewing 60 patients diagnosed as having brain infarcts on clinical features and CT, we found 12 (four women, eight men), aged 23-83 years, with laminar high-signal lesions on Tl-weighted images. The inclusion criterion was the presence of high-signal laminar cortical lesions on Tl weighted images at any time during the clinical course. Patients with calcification or haemorrhagic infarcts on CT were excluded.
All patients underwent CT within 24 h of admission and on the day of their first MRI. Each underwent serial MRI from day 6 to 1.5 years after the ictus, at 1.5 tesla. The basic protocol included T1-weighted and T2-weighted axial spin-echo images, and contrast enhancement with gadolinium diethylenetriamine-pentaacetic acid (Gd-DTPA) 0.1-0.2 mmol/kg. Fluid-attenuated inversion-recovery (FLAIR) and T2*-weighted gradient-echo images were performed in some cases, the former on seven occasions for five patients, latter on three occasions for...