[The heterogeneity of blood flow on magnetic resonance imaging: a biomarker for grading cerebral astrocytomas]

OBJECTIVES

To study whether the histograms of quantitative parameters of perfusion in MRI obtained from tumor volume and peritumor volume make it possible to grade astrocytomas in vivo.

MATERIAL AND METHODS

We included 61 patients with histological diagnoses of grade II, III, or IV astrocytomas who underwent T2*-weighted perfusion MRI after intravenous contrast agent injection. We manually selected the tumor volume and peritumor volume and quantified the following perfusion parameters on a voxel-by-voxel basis: blood volume (BV), blood flow (BF), mean transit time (TTM), transfer constant (K(trans)), washout coefficient, interstitial volume, and vascular volume. For each volume, we obtained the corresponding histogram with its mean, standard deviation, and kurtosis (using the standard deviation and kurtosis as measures of heterogeneity) and we compared the differences in each parameter between different grades of tumor. We also calculated the mean and standard deviation of the highest 10% of values. Finally, we performed a multiparametric discriminant analysis to improve the classification.

RESULTS

For tumor volume, we found statistically significant differences among the three grades of tumor for the means and standard deviations of BV, BF, and K(trans), both for the entire distribution and for the highest 10% of values. For the peritumor volume, we found no significant differences for any parameters. The discriminant analysis improved the classification slightly.

CONCLUSIONS

The quantification of the volume parameters of the entire region of the tumor with BV, BF, and K(trans) is useful for grading astrocytomas. The heterogeneity represented by the standard deviation of BF is the most reliable diagnostic parameter for distinguishing between low grade and high grade lesions.

[Association of cavernous and venous angiomas]

INTRODUCTION

Isolated cavernous and venous angiomas are common vascular cerebral malformations. The routine use of magnetic resonance imaging (MRI) in cerebral studies has shown their frequent association.

OBJECTIVE

An analysis of the association characteristics of both lesions (cavernous and venous angiomas), and the relationships with localization, size, patient sex and the use of intravenous contrast material in the diagnosis with MR.

METHODS

A retrospective analysis of the cerebral MRI studies of 37 patients with cavernous angiomas. Statistical relations were established with contingency tables and statistical methods of Pearson c2 and t of Student for independent samples. Results. 52 cavernous angiomas were identified in the 37 patients. No significant statistical differences were found that related the cavernous angioma size, localization or patient sex with the existence of an associated venous angioma. Only the administration of contrast material has shown a statistical significance for the diagnosis.

CONCLUSIONS

The association of cavernous and venous angioma is frequent (30%). This association has prognostic implications, due to bleeding risk, and surgical as it is not recommended the resection of the venous anomaly due to the possible venous infarction. To detect venous angiomas is necessary the administration of contrast material.

[Update on lung cancer staging]

Clinical staging is fundamental in lung cancer, as this descriptive system facilitates the transmission of the extension of the disease, provides prognostic information, helps in choosing the most appropriate treatment program, and provides a standardized system that enables the treatment outcomes of different series of patients to be compared. The most important technique for defining local, regional, and remote extension of the disease continues to be chest and abdominal CT. Functional imaging techniques play a complementary role that is becoming increasingly important in the noninvasive characterization of mediastinal lymph-node involvement.