Secondary central nervous system lymphoma: spectrum of morphological MRI appearances.

BACKGROUND: Secondary central nervous system lymphoma (SCNSL) is a rare and aggressive disease, which is defined as secondary central nervous system (CNS) involvement in patients with systemic lymphoma. According to previous reports, SCNSL presents mostly with leptomeningeal spread; however, our experience differs. In the present study, we demonstrate the diversity of magnetic resonance imaging (MRI) patterns in SCNSL. PATIENTS AND METHODS: Initial morphological MRI findings in 21 patients (10 women and 11 men with mean age 62.3±16.2 years) with SCNSL were retrospectively evaluated. All patients suffered from neurological symptoms and underwent MRI, and all cases were histologically verified. Twelve patients were treated by corticosteroids at the time of the initial MRI. RESULTS: Parenchymal lesions were present in 18 of 21 cases (85.7%), solitary meningeal infiltration was present in 1 patient (4.8%), leptomeningeal infiltration in combination with hypophyseal involvement in 1 patient (4.8%), and solitary involvement of the sixth cranial nerve (CN) was found in 1 patient (4.8%). Multiple lesions were present in 11 of 21 cases (52.4%). Diffusion restriction in all or part of the lesion was detected in 14 of 18 cases (77.8%). All parenchymal lesions had an infiltrative appearance and most enhanced homogenously (11 of 17 cases; 64.7%). A combination of parenchymal and meningeal involvement was found in 10 of 21 cases (47.6%). Infiltration of the CNs, basal ganglia, corpus callosum, and ependyma was present in 8 of 21 cases (38.1%) for each of the abovementioned structures; hypothalamic-hypophyseal axis was affected in 7 of 21 cases (33.3%). CONCLUSION: In contrast to previous reports, SCNSL presented as parenchymal disease. MRI is not sufficient for differentiation between primary and secondary CNS lymphoma.

Central nervous system lymphoma: a morphological MRI study.

OBJECTIVES: The aim of the present study was to evaluate morphological MRI findings in histologically-proven central nervous system lymphoma (CNSL) at time of their first appearance, and to describe dynamic changes on repeat MRI before the diagnosis was histologically proven. METHODS: We retrospectively evaluated the MRI examinations of 74 patients with histologically-proven CNSL (10 secondary CNSL, 64 primary PCNSL; 10 immunocompromised, 54 immunocompetent). In 43 patients, we evaluated the evolution of CNSL on MRI before the diagnosis was proven. RESULTS: Primary CNSL was typically localized supratentorially (63%), with multiple (59%) or infiltrative (36%) lesions showing diffusion restriction (98%), often (87%) reaching the brain surface. In approximately 50% of patients, meningeal, ependymal or cranial nerve involvement was found. We detected significant differences in enhancement patterns between immunocompromised and immunocompetent patients; non-homogenous enhancement present in 50% of immunocompromised patients. We did not find any significant differences in MRI appearance between primary and secondary CNSL. Regression was evident after corticosteroid treatment in 52% of patients; however, in 16% of cases overall progression was observed. CONCLUSION: CNSL generally presents as an infiltrative lesion or multiple homogenously-enhancing lesions of the brain in contact with the brain surface. Involvement of the corpus callosum, cranial nerves, ependyma or meninges is common. No significant differences between primary and secondary CNSL were detected, however differences in enhancement type between immunocompromised and immunocompetent primary CNSL patients were found. We stress the variability of MRI findings in the course of the disease and also the variable response to corticotherapy.

Late morphological changes after radiosurgery of brain arteriovenous malformations: an MRI study.

BACKGROUND: Radiosurgery by Gamma Knife (GK) is an effective treatment for brain arteriovenous malformations (AVM). The aim of the present study was to evaluate late, radiation-induced changes detectable by MRI after AVM radiosurgery in patients treated minimally 10 years prior, with AVM obliteration proven by angiography. METHODS: Thirty-five patients with 37 AVMs were included. AVMs were irradiated 16.6 ± 3.5 years prior with AVM obliteration proven 13 ± 4 years prior. All patients underwent recent MRI examinations, including application of gadolinium-based contrast. RESULTS: In one case, post-irradiative cystic formation with mass effect and signs of hemorrhage requiring surgery was found. Post-gadolinium enhancement at the site of obliterated nidi was apparent in 28 of 37 cases (76 %). In all cases except one, the mean volume of enhancement at the time of review was clearly lower than the volume of the originally irradiated AVM (88 ± 20 %; median 92 %); in one case the extent was 142 % greater than the irradiated AVM. When we compared enhancing and non-enhancing nidi, we found that enhancing nidi were significantly larger than non-enhancing nidi at the time of radiosurgery (4.39 ± 3.35 cc vs. 0.89 ± 0.79 cc, p = 0.004). Enhancement was not influenced by total radiation dose, patient age at the time of irradiation, duration since radiosurgery, or the number of irradiations. Wallerian degeneration was found in nine of 37 cases (24 %); in six cases the optical tracts were affected and visual field defects were proven. In five of nine cases (55.6 %) with Wallerian degeneration previous hemorrhage was present. Dual vascular pathology was found in eight of 35 patients (23 %). CONCLUSIONS: GK radiosurgery for AVM is a safe treatment method although delayed complications may occur. Post-gadolinium enhancement of obliterated nidi may indicate an active post-irradiative process.