In malignant tumours, ferumoxtran may show areas of enhancement, even with a 0.15 T intraoperative MR, that do not enhance with gadolinium. Ferumoxtran-enhancing lesions have persistent increased T1 signal intensity for 2-5 days, which may provide advantages over gadolinium for postoperative imaging. Histochemistry for iron shows uptake of ferumoxtran in reactive cells (astrocytes and macrophages) rather than tumour cells.

Central nervous system (CNS) drainage may occur via connections to the vasculature, but in animal models up to 50% occurs via perivascular, perineural and primitive lymphatic drainage to cervical lymph nodes. We evaluated efflux of particles from the brain to cervical lymph nodes in normal rats, using Combidex iron oxide-based magnetic resonance imaging (MRI) agent. After intracerebral, intraventricular, intracarotid or intravenous injection of Combidex in normal Long Evans rats, particle localization was assessed by MRI and histochemistry for iron and the dextran coat (n = 27). Intraventricular or intracerebral injection, but not intracarotid administration of Combidex (100 micro g), resulted in MRI signal changes in the deep cervical lymph nodes around the carotid artery, and, less strongly, in the superficial cervical nodes. Within 2 h of Combidex administration, iron was histologically localized in cervical lymph nodes, with patched staining of capsule and peripheral sinus consistent with delivery via multiple afferent lymphatic vessels. Lymph node staining in groups receiving CNS Combidex was significantly different from controls (P < 0.0001) and was significantly localized in the deep vs. superficial cervical lymph nodes (P = 0.0003). The trafficking of the superparamagnetic iron particles from the CNS in the rat could be visualized by MRI and histology. Combidex provides a powerful tool to rapidly assess drainage of virus-sized particles from the CNS.

Background: Brain metastasis of lung cancer adversely affects overall survival (OS) and quality of life, while peritumoral brain edema is responsible for life-threatening complications. Methods: We retrospectively analyzed the clinicopathological and cerebral radiological data of 575 consecutive lung cancer patients with brain metastases. Results: In adenocarcinoma and squamous cell carcinoma, peritumoral brain edema was more pronounced than in small-cell lung cancer (p < 0.001 and p < 0.001, respectively). There was a positive correlation between the size of metastasis and the thickness of peritumoral brain edema (p < 0.001). It was thicker in supratentorial tumors (p = 0.019), in younger patients (≤50 years) (p = 0.042), and in females (p = 0.016). The time to development of brain metastasis was shorter in central than in peripheral lung cancer (5.3 vs. 9.0 months, p = 0.035). Early brain metastasis was characteristic for adenocarcinomas. A total of 135 patients had brain only metastases (N0 disease) characterized by peripheral lung cancer predominance (p < 0.001) and a longer time to development of brain metastasis (9.2 vs. 4.4 months, p < 0.001). OS was longer in the brain only subgroup than in patients with N1-3 diseases (p < 0.001). Conclusions: The clinicopathological characteristics of lung cancer are related to the development and radiographic features of brain metastases. Our results might be helpful in selecting patients who might benefit from prophylactic cranial irradiation.

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3 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2018;48:441-448.