Growth speed of large brain metastases between diagnostic and radiosurgical planning MRI and predictors of rapid tumor growth.

PURPOSE: We aimed to assess volumetric changes of large brain metastases (≥ 2 cm) between their diagnosis and planning for treatment with fractionated stereotactic radiation surgery (fSRS). Predictors of rapid tumor growth were also analyzed. MATERIALS AND METHODS: One hundred nine patients harboring 126 large brain metastases were retrospectively evaluated. Tumor characteristics were evaluated on diagnostic magnetic resonance imaging (dMRI) and MRI performed when planning fSRS (pMRI). Average tumor growth rate and percentage growth rate were calculated. Predictors of rapid growth (percentage growth rate > 5%) were determined using multivariate logistic regression. RESULTS: Both tumor diameter and volume were significantly larger on pMRI than on dMRI (P < 0.001). Median tumor percentage growth rate was 2.6% (range, - 10.8-43.3%). Eighty-eight tumors (70%) were slow-growing (percentage growth rate < 5%) and 38 (30%) grew rapidly (percentage growth rate ≥ 5%). Major peritumoral edema and no steroids were predictors of rapid tumor growth. CONCLUSION: Large brain metastases can grow considerably between the time of diagnosis and the time of fSRS treatment planning. We recommend the time between dMRI and fSRS treatment initiation be as short as possible.

Comparison of high-resolution computed tomography findings between Pseudomonas aeruginosa pneumonia and Cytomegalovirus pneumonia.

OBJECTIVE: To compare pulmonary high-resolution CT (HRCT) findings in patients with Pseudomonas aeruginosa pneumonia to HRCT findings in patients with Cytomegalovirus (CMV) pneumonia. METHODS: We studied 124 patients (77 men, 47 women; age range, 20-89 years; mean age, 65.4 years) with P. aeruginosa pneumonia and 44 patients (22 men, 22 women; age range, 36-86 years; mean age, 63.2 years) with CMV pneumonia. RESULTS: CT findings of consolidation (p < 0.005), bronchial wall thickening (p < 0.001), cavity (p < 0.05), and pleural effusion (p < 0.001) were significantly more frequent in patients with P. aeruginosa pneumonia than in those with CMV pneumonia. Centrilobular nodules, a crazy-paving appearance, and nodules were significantly more frequent in patients with CMV pneumonia than in those with P. aeruginosa pneumonia (all p < 0.001). CONCLUSION: Pulmonary HRCT findings, such as bronchial wall thickening, crazy-paving appearance, and nodules may be useful in distinguishing between P. aeruginosa pneumonia and CMV pneumonia. KEY POINTS: Distinguishing Pseudomonas aeruginosa pneumonia from Cytomegalovirus pneumonia is important. Characteristic features of underlying conditions are present in each pneumonia species. Bronchial wall thickening and cavities are more frequent in Pseudomonas aeruginosa pneumonia. Nodules and a crazy-paving appearance are more frequent in Cytomegalovirus pneumonia.