Apparent diffusion coefficient and pituitary macroadenomas: pre-operative assessment of tumor atypia.

RATIONALE AND OBJECTIVES: Pituitary macroadenomas are predominantly benign intracranial neoplasms that can be locally aggressive with invasion of adjacent structures. Biomarkers of aggressive behavior have been identified in the pathology literature, including the proliferative marker MIB-1. In the radiology literature, diffusion weighted imaging and low ADC values provide similar markers of aggressive behavior in brain tumors. The purpose of this study was to determine if there is a correlation between ADC and MIB-1 in pituitary macroadenomas. MATERIALS AND METHODS: A retrospective review of diffusion imaging and immunohistochemical characteristics of pituitary macroadenomas was performed. The ADC ratio and specimen Ki-67 (MIB-1) indices were measured. Linear regression analysis of normalized ADC values and MIB-1 indices was used to compare these parameters. RESULTS: There were 17 patients with available ADC maps and MIB-1 indices. Local invasion was confirmed by imaging and intraoperative visualization in 11 patients. The mean ADC ratio for the invasive group was 0.68, with a mean MIB-1 index of 2.21 %. In the noninvasive group, the mean ADC ratio was 1.05, with a mean MIB-1 index of 0.9 %. Linear regression analysis of normalized ADC values versus MIB-1 demonstrates a negative correlation, with a linear slope significantly different from zero (p = 0.003, correlation coefficient of 0.77, and r squared = 0.59). CONCLUSION: We determine a strong correlation of low ADC values and MIB-1, demonstrating the potential of diffusion imaging as a possible biomarker for atypical, proliferative adenomas, which may ultimately affect the surgical approach and postoperative management.

Comparison of different modes in optical coherence tomography and ultrasound biomicroscopy in anterior chamber angle assessment.

PURPOSE: To compare anterior chamber angle width measurements by low and high-resolution anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). PATIENTS AND METHODS: Thirty-six eyes of 32 patients with gonioscopically narrow angles from a university-based glaucoma clinic were recruited in the study. All subjects received AS-OCT {in "Anterior Segment Single" mode [low-resolution optical coherence tomography (LOCT)] and "High-resolution Cornea" mode [high-resolution optical coherence tomography (HOCT)]} and UBM examination in 1 or both eyes. Angle opening distance (AOD) and angle recess area of temporal (t) and nasal (n) quadrants were assessed using the customized software on each type of image. Angle measurements from UBM, LOCT, and HOCT images were compared; intraobserver and interobserver measurement reproducibility for each type of image was also evaluated. RESULTS: Thirty-three eyes of 29 patients were available for analysis. No significant differences were found between LOCT and UBM in the measurement of t-AOD (P=0.350), n-AOD (P=0.106), and n-angle recess area (P=0.360). HOCT measurements were significantly larger than both LOCT and UBM for all parameters (all, P<0.05). HOCT images had better interobserver and intraobserver measurement reproducibility than UBM images. CONCLUSIONS: LOCT is similar to UBM for most of the studied angle measurements. HOCT tends to give larger measurements than both LOCT and UBM. AS-OCT measurements were more reproducible than those from UBM.

Anterior segment optical coherence tomography as a screening tool for the assessment of the anterior segment angle.

BACKGROUND AND OBJECTIVE: Anterior segment optical coherence tomography (AS-OCT) is an alternative method for the assessment of angle width. The purpose of this study is to assess the accuracy of AS-OCT for detecting occludable angles and compare the results of high- and low-resolution images with gonioscopy. PATIENTS AND METHODS: Visante AS-OCT (Carl Zeiss Meditec, Dublin, CA) images of 303 eyes (155 patients) presenting between February 1 and July 15, 2007, were retrospectively analyzed. Angle recess area (ARA) and angle opening distances (AOD) at 250, 500, and 750 microm were measured and correlated with the corresponding gonioscopic measurements. RESULTS: AS-OCT parameters showed a nonlinear relationship with gonioscopy, ARA having the highest correlation. Correlations between high- and low-resolution images were modest. Cut-off values were 0.180 mm2 (70.3% sensitivity, 87.4% specificity) for ARA and 0.264 mm (71.8% sensitivity, 84.8% specificity) for AOD at 500 microm. CONCLUSION: AS-OCT appears to be a promising screening tool for narrow angles.