Diffusion-Weighted Imaging of Brain Metastasis: Correlation of MRI Parameters with Histologic Type.

AIM: To compare the diffusion properties of brain metastases as imaging biomarkers in various types of tumours, to determine their histology and origin. MATERIAL AND METHODS: Magnetic Resonance Imaging (MRI) and diffusion-weighted imaging (DWI) were used to retrospectively study the data of 143 patients suffering from brain metastases. Four categories of primary tumours with metastases to the brain were included: lung carcinoma (n=102, 71.3%); breast carcinoma (n=27, 18.8%); colon carcinoma (n=8, 5.6%); and others (n=6, 4.2%). The Apparent Diffusion Coefficient (ADCmin ) values, as well as the normalised ADC ratio (nADC), were determined. The lesions on the DWI were categorised as follows: type 1, with negative findings on DWI; type 2, which were isointense with the normal cortical grey matter; type 3, which were hyperintense compared to the normal cortical grey matter. RESULTS: The diffusion type, mean ADCmin, and mean nADC showed statistically significant differences in different types of metastases. In the subgroup analysis, it was found that type 3 was the diffusion type found most extensively in the brain metastases of small cell carcinoma (SCLC) (n=52, 65.8%, p < 0.000). Furthermore, the mean ADCmin and nADC values were the least for the brain metastases of the SCLC (552.0 ± 134.2 and nADC = 0.8 ± 0.1, p < 0.000, respectively). The value of the mean ADCmin was low in the human epidermal growth factor receptor 2 (HER-2) negative groups than in the HER-2 positive groups at 786.8 ± 299.1 vs 844.8 ± 141.3 (p < 0.006). CONCLUSION: Our findings indicated that there is a correlation between diffusion parameters as imaging biomarkers of the solid component of brain metastases of primary tumours and the tumour histology.

The effectiveness of magnetization transfer technique in the evaluation of acute plaques in the central nervous system of multiple sclerosis patients and its correlation with the clinical findings.

PURPOSE: To determine the value of magnetization transfer (MT) imaging in the evaluation of acute plaques, which cause clinical findings in the brain magnetic resonance (MR) images of patients with relapsing-remitting multiple sclerosis, and its correlation with the clinical findings. MATERIALS AND METHODS: Forty patients with relapsing-remitting multiple sclerosis were included in the study. They were being followed-up for the diagnosis of relapsing-remitting multiple sclerosis based on McDonald's criteria. To evaluate the acute plaques of the patients, their T1- weighted spin echo sequences were divided into 3 groups: precontrast and postcontrast MT images (group 1), postcontrast MT images only (group 2), and precontrast and postcontrast non-MT images (group 3). The sensitivity and positive predictive values were calculated to determine the correlation between the patients considered to have had attacks and the acute plaques detected during MR imaging examinations with T1-weighted spin echo. RESULTS: After clinical examinations, in 25 of 40 patients (62.5%), there were neurological findings suggesting acute attacks. Among the 3 imaging groups, there was a significant difference in the number of acute plaques. In group 1 there were a total 30 findings suggesting acute plaques; in group 2 33; and in group 3 there were 20. When the correlation between the patients who were considered to have had attacks after their clinical examinations and the acute plaques detected with T1- weighted spin echo examinations were evaluated, the sensitivity and positive predictive values were 97% and 100% in group 1, 87% and 78% in group 2, and 65% and 100% in group 3, respectively. CONCLUSION: In MS, T1-weighted MT examinations yield more reliable results for following up the treatment and changes in the development of the disease. They also offer a more effective evaluation of the acute plaques that cause clinical findings.