Purpose:To investigate the contribution of perfusionweighted MR imaging (PWI) by using the relative cerebral blood volume (rCBV) ratio in the differential diagnosis of various intracranial space-occupying lesions. Materials and Methods:This study involved 105 patients with lesions (high-grade glioma (N ϭ 26), low-grade glioma (Nϭ 11), meningioma (N ϭ 23), metastasis (N ϭ 25), hemangioblastoma (N ϭ 6), pyogenic abscess (N ϭ 4), schwannoma (N ϭ 5), and lymphoma (N ϭ 5)). The patients were examined with a T2*-weighted (T2*W) gradient-echo singleshot EPI sequence. The rCBV ratios of the lesions were obtained by dividing the values obtained from the normal white matter. Statistical analysis was performed with the Mann-Whitney U-test. A P-value less than 0.05 was considered statistically significant. Results:The rCBV ratio was 5.76 Ϯ 3.35 in high-grade gliomas, 1.69 Ϯ 0.51 in low-grade gliomas, 8.02 Ϯ 3.89 in meningiomas, 5.27 Ϯ 3.22 in metastases, 11.36 Ϯ 4.41 in hemangioblastomas, 0.76 Ϯ 0.12 in abscesses, 1.10 Ϯ 0.32 in lymphomas, and 3.23 Ϯ 0.81 in schwannomas. The rCBV ratios were used to discriminate between 1) high-and low-grade gliomas (P Ͻ 0.001), 2) hemangioblastomas and metastases (PϽ 0.05), 3) abscesses from high-grade gliomas and metastases (P Ͻ 0.001), 4) schwannomas and meningiomas (P Ͻ 0.001), 5) lymphomas from high-grade gliomas and metastases (P Ͻ 0.001), and 6) typical meningiomas and atypical meningiomas (P Ͻ 0.01).Conclusion: rCBV ratios can help discriminate intracranial space-occupying lesions by demonstrating lesion vascularity. It is possible to discriminate between 1) high-and low-grade gliomas, 2) hemangioblastomas and other intracranial posterior fossa masses, 3) abscesses from highgrade gliomas and metastases, 4) schwannomas and meningiomas, 5) lymphomas and high-grade gliomas and metastases, and 6) typical and atypical meningiomas.

ABSTRACT. The aim of this prospective study was to evaluate the value of unenhanced (three-dimensional constructive interference in steady state (3D-CISS)) and contrastenhanced MR cisternography (CE-MRC) in detecting the localisation of cerebrospinal fluid (CSF) leak in patients with rhinorrhoea. 17 patients with active or suspected CSF rhinorrhoea were included in the study. 3D-CISS sequences in coronal and sagittal planes and fat-suppressed T 1 -weighted spin-echo sequences in three planes before and after intrathecal contrast media adminstration were obtained. Images were obtained of the cribriform plate and sphenoid sinus. In addition, high-resolution CT (HRCT) was performed in order to evaluate the bony elements. The leak was present in 9/17 patients with 3D-CISS and 10/17 patients with CE-MRC. The leak from the cribriform plate to the nasal cavity in six patients and from the sphenoid sinus in four patients was nicely shown by CE-MRC. Eight of those patients were surgically treated, but spontaneous regression of the symptoms in two precluded any intervention. The leak localisations shown with CE-MRC were fully compatible with surgical results. The sensitivities of HRCT, 3D-CISS and CE-MRC for showing CSF leakage were 88%, 76% and 100%, respectively. In conclusion, 3D-CISS is a non-invasive and reliable technique, and should be the first-choice method to localise CSF leak. CE-MRC is helpful in conditions when there is no leak or in complicated cases with a positive b2-transferrin measurement.

Diffusion-weighted MR imaging findings of atypical/malignant meningiomas and typical meningiomas differ. Atypical/malignant meningiomas have lower intratumoral ADC values than typical meningiomas. Mean ADC values for peritumoral edema do not differ between typical and atypical meningiomas.

No abstract

ObjectiveTo evaluate the usage of duplex power Doppler ultrasound (PDUS) for the differentiation of benign and malignant thyroid nodules.Materials and MethodsWe prospectively examined 77 thyroid nodules in 60 patients undergoing ultrasound-guided fine needle aspiration biopsy (FNAB). Each nodule was described according to size, inner structure, borders, parenchymal echogenicity, peripheral halo formation, and the presence of calcification (B-mode ultrasound findings). Vascularity as determined by PDUS imaging was defined as non-vascular, peripheral, central, or of mixed type. For each nodule, the pulsatility index (PI) and resistive index (RI) values were obtained. Results of FNAB and surgical pathological examination (if available) were used as a proof of final diagnosis to categorize all nodules as benign or malignant. A receiver operating characteristic (ROC) curve analysis was performed to establish cut-off, sensitivity, and specificity values associated with RI-PI values.ResultsA significant relationship was observed between malignancy and irregular margins, microcalcifications, and hypoechogenicity on ultrasound examination (p < 0.05). The pattern of vascularity as determined by PDUS analysis was not a statistically significant criterion to suggest benign or malignant disease in this study (p > 0.05). The central, peripheral, and mean RI-PI values were higher in malignant nodules when compared to the other cytologies (p < 0.05).ConclusionVascularity is not a useful parameter for distinguishing malignant from benign thyroid nodules. However, RI and PI values are useful in distinguishing malignant from benign thyroid nodules.