Resonancia magnética de perfusión en astrocitomas de alto grado: el volumen sanguíneo cerebral,la altura del pico y el porcentaje de recuperación de intensidad de señal ¿pueden discriminar entre progresión y seudoprogresión?

Objectives

To study the usefulness of common MRI perfusion parameters for identifying pseudoprogression in high grade astrocytomas.

Material and methods

This retrospective case-control study compared the relative cerebral blood volume (rCBV), the relative percentage of signal intensity recovery (rPSR), and the relative peak height (rPH) recorded in a sample of 17 cases of anaplastic astrocytomas and gliomas considered to be undergoing pseudoprogression by biopsy or follow-up with those recorded in a sample of histologically similar tumors that were treated and considered to be undergoing progression by histologic study or follow-up. We evaluated the accuracy of these parameters and the correlations among them. Statistical significance was set at P<.05.

Results

The rCBV, rPSR, and rPH were significantly different between the two groups (P=.001). The cutoff values rPH=1.37, rCBV=0.9, and rPSR=99% yielded sensitivity (S)=88% and specificity (Sp)=82.2% for rPH, S=100% and Sp=100% for rCBV, and S=100% and Sp=70.6% for rPSR, respectively. We found negative correlations between rPRS and rPH (−0.76) and between rPRS and rCBV (−0.81) and a high positive correlation between rPH and rCBV (0.87).

Conclusion

The variables rPH and rCBV were useful for differentiating between pseudoprogression and true progression in our sample. The variable rPRS was also very sensitive, although the overlap in the values between samples make it less useful a priori.     

Role of PROPELLER diffusion weighted imaging and apparent diffusion coefficient in the diagnosis of sellar and parasellar lesions

Objective

To evaluate the role of the apparent diffusion coefficient (ADC) using periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion weighted imaging (DWI) in the differentiation between sellar and parasellar mass lesions.

Materials and methods

The study protocol was approved by our institutional review board. We retrospectively studied 60 patients with sellar and parasellar lesions who had undergone PROPELLER DWI on a 3-T MR imager. Conventional MRI findings were expressed as the ratio of signal intensity (SI) in the lesions to the normal white matter and the degree of contrast enhancement. ADC values were calculated as the minimum (ADC-MIN), mean (ADC-MEAN), and maximum (ADC-MAX). All patients underwent surgery and all specimens were examined histologically. Logistic discriminant analysis was performed by using the SI ratios on T1- and T2-weighted images (T1-WI, T2-WI), the degree of enhancement, and absolute ADC values as independent variables.

Results

ADC-MIN of hemorrhagic pituitary adenomas was lower than of the other lesions with similar appearance on conventional MRI (non-hemorrhagic pituitary adenomas, craniopharyngiomas, Rathke's cleft cysts; accuracy 100%); the useful cut-off value was 0.700 × 10⁻³ mm²/s. ADC-MAX of meningiomas was lower than of non-hemorrhagic pituitary adenomas (accuracy 90.3%; p < 0.01). ADC-MIN of craniopharyngiomas was lower than of Rathke's cleft cysts (accuracy 100%; p < 0.05).

Conclusion

As PROPELLER DWI is less sensitive to susceptibility artifacts than single-shot echoplanar DWI, it is more useful in the examination of sellar and parasellar lesions. Calculation of the ADC values helps to differentiate between various sellar and parasellar lesions.     

Assesment of perfusion in glial tumors with arterial spin labeling; comparison with dynamic susceptibility contrast method

Purpose

Arterial spin labeling perfusion imaging (ASL-PI) is a non-invasive perfusion imaging method that can be used for evaluation and quantification of cerebral blood flow (CBF). Aim of our study was to evaluating the efficiency of ASL in histopathological grade estimation of glial tumors and comparing findings with dynamic susceptibility contrast perfusion imaging (DSC-PI) method.

Methods

This study involved 33 patients (20 high-grade and 13 low-grade gliomas). Multiphase multislice pulsed ASL MRI sequence and a first-passage gadopentetate dimeglumine T2*-weighted gradient-echo single-shot echo-planar sequence were acquired for all the patients. For each patient, perfusion relative signal intensity (rSI), CBF and relative CBF (rCBF) on ASL-PI and relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) values on DSC-PI were determined. The relative signal intensity of each tumor was determined as the maximal SI within the tumor divided by SI within symetric region in the contralateral hemisphere on ASL-PI. rCBV and rCBF were calculated by deconvolution of an arterial input function. Relative values of the lesions were obtained by dividing the values to the normal appearing symmetric region on the contralateral hemisphere. For statistical analysis, Mann–Whitney ranksum test was carried out. Receiver operating characteristic curve (ROC) analysis was performed to assess the relationship between the rCBF-ASL, rSI-ASL, rCBV and rCBF ratios and grade of gliomas. Their cut-off values permitting best discrimination was calculated. The correlation between rCBV, rCBF, rSI-ASL and rCBF-ASL and glioma grade was assessed using Spearman correlation analysis.

Results

There was a statistically significant difference between low and high-grade tumors for all parameters. Correlation analyses revealed significant positive correlations between rCBV and rCBF-ASL (r = 0.81, p < 0.001). However correlation between rCBF and rCBF-ASL was weaker (r = 0.64, p < 0.001).

Conclusion

Arterial spin labeling is an employable imaging technique for evaluating tumor perfusion non-invasively and may be useful in differentiating high and low grade gliomas.     

Role of perfusion-weighted imaging at 3T in the histopathological differentiation between astrocytic and oligodendroglial tumors

Objective

The differentiation of oligodendroglial tumors from astrocytic tumors is important clinically, because oligodendroglial tumors are more chemosensitive than astrocytic tumors. This study was designed to clarify the usefulness of 3 T MR perfusion imaging (PWI) in the histopathological differentiation between astrocytic and oligodendroglial tumors. This is because there is a growing interest in the diagnostic performance of 3 T MR imaging, which has the advantages of a higher signal-to-noise ratio (SNR) and greater spatial and temporal resolution.

Materials and methods

This study retrospectively included 24 consecutive patients with supratentorial, WHO grade II and III astrocytic and oligodendroglial tumors (7 astrocytic, 10 oligoastrocytic, and 7 oligodendroglial tumors) that were newly diagnosed and resected between November 2006 and December 2009 at Hiroshima University Hospital. These patients underwent dynamic susceptibility contrast-enhanced (DSC) PWI relative cerebral blood volume (rCBV) measurements before treatment. Astrocytic tumors were designated as the astrocytic group, and oligoastrocytic and oligodendroglial tumors as the oligodendroglial group. The regions of interest with the maximum rCBV values within the tumors were normalized relative to the contra-lateral white matter (rCBVmax).

Results

The average rCBVmax of astrocytic tumors (2.01 ± 0.68) was significantly lower than that of the oligoastrocytic (4.60 ± 1.05) and oligodendroglial tumors (6.17 ± 0.867) (P < 0.0001). A cut-off value of 3.0 allowed to differentiate the oligodendroglial group from the astrocytic group at 100% sensitivity and 87.5% specificity.

Conclusion

The rCBVmax values obtained from 3 T MR PWI may be useful as an adjunct to the postoperative histopathological diagnosis of glioma patients.     

Low field MR imaging of sellar and parasellar lesions: experience in a developing country hospital

Background

Magnetic resonance imaging (MRI), an advancement which followed computed tomography (CT) is expensive and inaccessible in most developing countries. However it is the procedure of choice in evaluating sellar and parasellar lesions. Its major advantages are its superior soft tissue contrast differentiation, its capacity for multiplanar imaging and nonexistence of ionising radiation. Its use is relatively new in Nigeria, a developing economy in Africa. Since its introduction in 2005, it has been utilised extensively for neuroimaging at the University College Hospital (UCH), Ibadan; a large hospital in south-western Nigeria.

Objective

To review the role and pattern of low field MR Imaging in sellar and parasellar lesions presenting to a tertiary care centre in Nigeria.

Methods

All 62 patients with clinically suspected sellar and parasellar masses, referred to the Department of Radiology, UCH Ibadan for MRI between December 2006 and January 2010 were retrospectively analysed. The examinations were performed using an open 0.2 T permanent magnet MR unit. T1W, T2W, T2/FLAIR, TOF and T1W post gadolinium DTPA sequences of the sellar region were obtained.

Results

Of the 62 patients, there were 27 males and 35 females. The modal age group was 40–49 years with a mean age of 39.94 years (±16.65 years). Twenty-four cases (38.7%) had histological diagnosis, of which 20 (83.3%) were consistent with initial MRI diagnosis. Pituitary adenomas were the commonest (58.06%) lesions of the sellar and parasellar regions. Others include parasellar meningiomas, cranipharyngiomas, and giant aneurysms. Headache and visual impairment were the major presenting features and showed no significant correlation with tumour size.

Conclusion

The use of low field MRI in the diagnostic evaluation of patients with suspected sellar or parasellar lesions in developing countries of low economic resource is commendable as it provides beneficial outcomes in management.     

Role of diffusion weighted MRI in differentiating typical from atypical meningiomas at 1.5 and 3T MRI

Purpose

Atypical and malignant meningiomas are considered to have a higher rate of recurrence and show aggressive behavior compared to benign variety. The purpose of our study was to study the role of diffusion weighted imaging and determination of apparent diffusion coefficient (ADC) values and ADC ratios to differentiate typical meningiomas from atypical/malignant variety at 1.5 and 3T MRI.

Materials and methods

A total of 94 adult patients (48 patients at 3T and 46 patients at 1.5T) with pathologically proven meningiomas were retrospectively evaluated on conventional and diffusion weighted MRI. The signal intensity of the lesions on DW imaging was evaluated. ADC values and ADC ratios were calculated from lesion and contralateral normal white matter.

Results

94 lesions comprising of 66 benign and 28 atypical meningiomas were evaluated. The mean ADC values at 3T MRI were 0.82 ± 0.12 × 10⁻³ in benign (typical) meningiomas and 0.68 ± 0.10 × 10⁻³ in atypical meningiomas. At 1.5T, the mean ADC values of benign meningiomas were 0.83 ± 0.11 × 10⁻³ and 0.70 ± 0.09 × 10⁻³ in atypical meningiomas. The mean ADC ratios were 1.08 ± 0.17 and 0.85 ± 0.15 for benign and atypical meningiomas respectively. There was a statistically significant difference between the mean ADC ratios and the mean ADC values of typical and atypical meningiomas (P < 0.001) at both 1.5T and 3T MRI.

Conclusion

DWI with calculation of apparent diffusion coefficient (ADC) values and ADC ratios has a potential role in differentiating benign from atypical meningiomas at both 1.5 and 3T MRI. The differences in mean ADC values between benign and atypical meningiomas were similar at both 1.5 and 3T MRI.     

鞍区肿瘤的MRI表现与鉴别诊断

目的：明确不同类型鞍区肿瘤的MRI特征。材料与方法：回顾性分析44例经手术病理证实的鞍区肿瘤MRI表现。结果：19例垂体大腺瘤、12例颅咽管瘤、9例鞍区脑膜瘤及4例鞍上池表皮样囊肿均有其一定的特征性MRI表现。垂体大腺瘤起源于垂体，大多数向上生长呈“雪人”形，个别向下生长突破鞍底，瘤体内可发生囊变（47％）或出血（32％）而致信号强度不均；颅咽管瘤多发生于鞍上，少数累及鞍内，囊实性或囊性者居多，其中于T1加权像上囊液可呈低、等、高不同信号强度为其特点；脑膜瘤多位于鞍上池前部，信号均匀与脑灰质相似，增强扫描有时可见脑膜尾征；发生于鞍上池的表皮样囊肿沿脑池生长，边缘不规则，信号强度与脑脊液相似。结论：MRI对鞍区肿瘤有重要的鉴别诊断价值。     

Relative percentage signal intensity recovery of perfusion metrics—an efficient tool for differentiating grades of glioma

Objective:

Glioma classification and characterization may be facilitated by a multiparametric approach of perfusion metrics, which could not be achieved by conventional MRI alone. Our aim is to explore the potential of relative percentage signal intensity recovery (rPSR) values, in addition to relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) of first-pass T₂* dynamic susceptibility contrast (DSC) perfusion MRI, in differentiating high- and low-grade glioma.

Methods:

This prospective study included 39 patients with low-grade and 25 patients with high-grade glioma. rPSR, rCBV and rCBF were calculated from the first-pass T₂* DSC perfusion MRI. rPSR was calculated using standard software and validated with dedicated perfusion metrics analysis software. The statistical analysis was performed using analysis of variance and receiver operating characteristic (ROC) curves.

Results:

Variation in rPSR, rCBV and rCBF values between low- and high-grade gliomas were statistically significant (p < 0.005). The ROC curve analysis for each of them yielded 96% sensitivity and 71.8% specificity; 88% sensitivity and 69.2% specificity; and 72% sensitivity and 66.7% specificity. The area under the curve (AUC) from the ROC curve analysis yielded 0.893, 0.852 and 0.702 for rPSR, rCBV and rCBF, respectively. The rPSR calculation with the validation software yielded 92.3% sensitivity and 72% specificity with an AUC of 0.864.

Conclusion:

rPSR inversely correlates while rCBV and rCBF values directly correlate with the tumour grade. Furthermore, the overall diagnostic performance of rPSR is better than rCBV and rCBF values.

Advances in knowledge:

rPSR of T₂* DSC perfusion is an indicator of blood–brain barrier status and lesion leakiness, which has not been explored yet compared with the usual haemodynamic parameters, rCBV and rCBF.Gliomas, the most common primary brain tumour of the brain, are heterogeneous, showing highly varied histopathological features during malignant transformation of the tumour reflecting alterations in the tumour vasculature.¹ The broad category of glioma represents approximately 30% of all the tumours. Low-grade astrocytomas (60–70%) and oligodendrogliomas (10–30%) are two common subtypes of low-grade gliomas. Among them, glioblastoma and astrocytoma account for 75% of gliomas.² With the advent of advanced imaging technologies, heterogeneity in gliomas such as neovascularization, angiogenesis, loss of blood–brain barrier (BBB) integrity, tortuousness, disorganized and highly permeable vessels may be non-invasively measured with the help of perfusion imaging.^3–5 Dynamic susceptibility contrast (DSC) perfusion MRI is a widely accepted tool for evaluating the haemodynamic characteristics of the brain, which are of great interest since it helps in assessing the malignancy of the tumour. The common haemodynamic parameters assessed using perfusion MRI are relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF).^6–8 In this study, we use a comparatively newer parameter, relative percentage signal intensity recovery (rPSR), whose potential has not been exploited to its best for haemodynamic calculations, even though this parameter has shown promise in the differentiation of brain tumours.^9–11 PSR is the percentage of the signal intensity recovered at the end of the first pass of the contrast agent with respect to the pre-contrast baseline signal intensity. After the administration of the contrast agent, there is a sudden decrease in the signal intensity owing to the variation in the local magnetic field leading to T₂* decay, which is seen as a dip in the mean signal intensity–time curve, and then the signal returns towards the baseline.^9–11The tumour rCBV provides information about the tumour blood levels and degree of angiogenesis but fails to provide information regarding capillary permeability. This drawback of DSC-MR perfusion imaging can be addressed by evaluating the rPSR obtained from the signal intensity–time curve formed at the end of the first pass of contrast agent in DSC-MR perfusion imaging.^9,10 Previous studies have observed that the contrast agent leakage, size of the extravascular space and the rate of blood flow that reflects the alterations in capillary permeability are related to rPSR.^10,11 There are reports which state that information regarding capillary permeability and lesion leakiness can be gathered from the signal intensity–time curve obtained from the first-pass T₂* DSC perfusion. Usually, this is performed using dynamic contrast-enhanced perfusion MRI, which involves additional scan time and also post-processing assumptions and extrapolations.^9–11Lupo et al⁴ was the first to report the characterization of high-grade gliomas using the PSR and peak height. rPSR is the only parameter among the different perfusion metrics which takes into account the leakage factor for the characterization of heterogeneity of brain tissues, compared with the other two parameters rCBV and rCBF where the leakage is neglected during the evaluation. The rPSR values of lower grade gliomas have not been explored, and hence an effort to differentiate between high- and low-grade gliomas using this new parameter will be advantageous. Hence, in the present study, we have evaluated all the parameters rPSR, rCBV and rCBF of low- and high-grade gliomas to find the potential of rPSR to differentiate different grades of glioma over the other two conventionally used parameters rCBV and rCBF. rPSR values were evaluated using two different standard software programs. Furthermore, we have performed a test for correlation between these parameters.     

Magnetic resonance spectroscopy and perfusion weighted imaging as predictors for tumor response to gamma knife radiosurgery: A single center experience

Objective

To test the hypothesis that hemodynamic and metabolic characteristics of intracranial neoplasms detected with magnetic resonance spectroscopy and perfusion weighted imaging are efficient predictors of tumor response to radiosurgery.

Methods

Fifty-four patients with 59 intracranial neoplasms, who underwent evaluation with echoplanar PW and MRS imaging prior to gamma knife radiosurgery were selected for this retrospective analysis. The mean irradiation dose was 13.76 Gy. The mean follow up after GNR constituted 24 months. Predictive diagnostic accuracy was calculated with standard formulas. The association of tumor response to radiosurgery with pretherapeutic MRI parameters was estimated using the Mann–Whitney U test.

Results

Significant association was found between the perfusion and hemodynamic parameters of intracranial neoplasms and the outcome of GKR. Diagnostic accuracy of multimodel MRI was 89% among low grade and 65% among high grade neoplasms. The overall accuracy was 81%. Normalized rCBV, choline, NAA and lipid contents and Chol/cr and NAA/cr were statistically different between low and high grade neoplasms (p < 0.001).

Conclusion

MR perfusion and spectroscopic results provided information that were predictive of the outcome of radiosurgery in this patient pool, increased the diagnostic accuracy of conventional MRI in defining tumor type and grade and may play an important role in pre-therapeutic planning for radiosurgery.     

What’s the clinical significance of adding diffusion and perfusion MRI in the differentiation of glioblastoma multiforme and solitary brain metastasis?

Objective

To evaluate the additional diagnostic value of diffusion and perfusion MRI in the differentiation of glioblastoma multiforme (GBM) and solitary brain metastasis.

Perfusion CT: A biomarker for soft tissue tumors of extremities

The aim of the work

To assess the perfusion CT characteristics of soft tissue tumors of extremities and evaluate its feasibility as a functional imaging technique in detecting, characterization, surgical planning and therapy monitoring of soft tissue tumors.

Patients & methods

31 cases with soft tissue tumor of extremities underwent PCT. Patients were 20 males and 11 females; age ranged from 17 to 74 years, mean age was 47.3 years. The final pathological results revealed three benign and 28 malignant soft tissue tumors, included 25 primary malignant tumors and three secondary tumors (metastasis). All cases underwent first-pass perfusion imaging with a 64-detector row CT scanner. Perfusion (BF), peak enhancement intensity (PEI), time to peak (TTP) and blood volume (BV) were measured in both tumor area and surrounding normal muscles then statistically compared.

Results

Qualitative analysis of color-coded PCT maps efficiently differentiated areas of active tumor/tumor residue from normal tissue. Quantitative analysis demonstrated that mean BF, PEI and BV were significantly higher in malignant tumors compared with surrounding healthy muscles (p < 0.05), but mean value of TTP was not found to be statistically significantly different. Receiver operating characteristic (ROC) curve analysis showed that malignant tissue can be differentiated well from normal muscle with BF greater than 12.9 ml/min/100 gm tissue, PEI higher than 22.8 HU or BV larger than 19.75 ml per 100 g tissue.

Conclusion

Preliminary results suggest a good value of PCT in detecting, characterization and therapy monitoring of soft tissue tumors of extremities.     

Assessment of tumor blood flow and its correlation with histopathologic features in skull base meningiomas and schwannomas by using pseudo-continuous arterial spin labeling images

Objective

We aimed to investigate whether pseudo-continuous arterial spin labeling (pcASL)-MRI can adequately evaluate tumor perfusion even if the tumors are located in the skull base region and evaluate the correlation between tumor blood flow (TBF) and the histopathologic features of skull base meningiomas and schwannomas.

Materials and methods

We enrolled 31 patients with skull base meningioma (n = 14) and schwannoma (n = 17) who underwent surgical resection. TBF was calculated from pcASL. Tissue sections were stained with CD34 to evaluate microvessel area (MVA). TBF and MVA ratio were compared between meningiomas and schwannomas using Mann–Whitney U-test. The correlations between MVA ratio and TBF were evaluated in each tumor by using single linear regression analysis and Spearman's rank correlation coefficients (r_s).

Results

MVA ratio and TBF were significantly higher in meningioma than in schwannoma (both p < 0.01). Correlation analyses revealed significant positive correlations between MVA ratio and both mean and max TBF for meningiomas (r_s = 0.89, 0.81, both p < 0.01). There was a weak positive correlation between MVA ratio and mean TBF for schwannomas (r_s = 0.43, p = 0.04). However, no significant correlation was found between MVA ratio and max TBF for schwannoma.

Conclusions

pcASL-MRI is useful for evaluating tumor perfusion even if the tumors are located in the skull base region. Moreover, pcASL-TBF was significantly higher in most meningiomas compared to schwannomas, which can help in the differential diagnosis of the 2 tumor types even without the use of contrast material.     

Changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery

Purpose

To evaluate changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery in the patients who underwent ischemic stroke caused by carotid artery stenosis.

Methods

Twenty patients with unilateral symptomatic carotid artery stenosis received brain computer tomography perfusion (CTP) scan a week before and a week after carotid artery stenting. Three absolute values including mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were acquired and analyzed by use of the post-processing software. Six vascular territories such as ACA territory, MCA territory, PCA territory, basal ganglia, watershed between ACA and MCA territory (frontal watershed), watershed between MCA and PCA territory (posterior watershed) were chosen for comparison. Relative parameter values were defined as rCBF (relative CBF), rCBV (relative CBV), rMTT (relative MTT) through comparing absolute values in symptomatic hemispheres to absolute values in asymptomatic hemispheres. The relative perfusion parameter values before treatment were compared with post-treatment values. These analyses were performed by using the paired t test.

Results

The mean rMTT decreased significantly in ACA territory, MCA territory and two watershed after treatment, while the mean rCBF increased significantly in those areas after treatment. But the mean rCBV had no significant changes in all six vascular territories. In PCA territory, all the parameters had no significant changes.

Conclusion

Carotid artery stenting yields satisfactory cerebral perfusion in ACA territory, MCA territory, basal ganglia and two watersheds.     

Application of CT perfusion imaging to the histological differentiation of adrenal gland tumors

Background

CT perfusion imaging has been used in diagnosis and classification of tumors widely and in assess tumor angiogenesis in some organs. However, there are few reports describing CT perfusion imaging of adrenal gland tumors.

Objective

This study aimed to evaluate the application of CT perfusion imaging in analysis of angiogenesis in adrenal tumors and in diagnosis of adrenal tumors.

Patients and methods

Forty four patients with adrenal gland tumors (26 with adenomas and 18 with nonadenomas) were enrolled in this study. CT scan of adrenal glands was performed with the perfusion of non-ionic contrast medium Ultravist. The obtained images were processed with deconvolution algorithms-based perfusion software and then perfusion parameter maps and values (blood flow, blood volume, mean transit time, and permeability surface-area production) were generated and analyzed respectively.

Results

Univariate multivariate logistic regression indicated that blood volume (OR: 1.261, 95% CI: 1.056, 1.505, P = 0.010) was associated with the likelihood of adrenal adenoma. Receiver operating characteristic analysis showed that the blood volume value of ≥9.325 ml min⁻¹ 100 g⁻¹ predicted adrenal adenoma with sensitivity of 76.9% and specificity of 73.2%. In addition, permeability surface-area production in adenoma was higher than in non-adenoma (27.11 ± 15.45 vs. 16.76 ± 14.44 ml min⁻¹ 100 g⁻¹, P < 0.05). The other parameters had no clear prognostic significance.

Conclusions

CT perfusion imaging can quantitatively distinguish adrenal gland tumors with different histological characteristics. Especially, blood volume can be used in differentiating adrenal adenomas from nonadenomas.     

The diagnostic value of diffusion weighted imaging in patients with meningioma

Purpose

This study aims to determine the use of diffusion-weighted (DW) magnetic resonance imaging (MRI) in differentiating typical and atypical meningiomas.

Patients and methods

In total, 31 patients aged 37–77 years with meningiomas were included in this study. Using routine MRI sequences, the meningiomas were diagnosed and DW images were performed using factor of b-0 and b-1000. Apparent diffusion coefficient (ADC) values were measured in the lesion, in the normal area of brain parenchyma. Student t-test was used for statistical analysis. P < 0.05 was considered significant.

Results

Showed that the mean ADC of atypical/malignant meningiomas (0.42–0.69 × 10⁻³ mm²/s; P < .0001) was significantly lower compared with benign meningiomas (0.72–1.5 × 10⁻³ mm²/s). Mean NADC ratio in the atypical/malignant group (0.61) was also significantly lower than the benign group (1.21; P < .0001), without overlap between groups. The difference between the ADC values of the subtypes of typical meningiomas was insignificant.

In conclusion

Typical meningiomas have higher ADC values than atypical cases. DW MRI may be of help in differentiating typical and atypical meningiomas.     

The role of advanced MRI techniques in differentiating typical,from atypical and malignant meningiomas

Background

Meningiomas are the commonest primary, non-glial intracranial tumors. The diagnosis is often correctly predicted from characteristic imaging appearances. Some meningiomas have atypical imaging appearance that may cause diagnostic confusion.

Aim

Is to evaluate the role of advanced MR imaging techniques in differentiating typical from atypical and malignant meningiomas before surgery.

Patient

Thirty patients were retrospectively included in this study. They were referred from Neurosurgery Department and all of them suspected to have intracranial meningioma according to the contrast enhanced CT.

Methods

All patients were subjected to conventional magnetic resonance imaging followed by advanced magnetic resonance imaging in the form of diffusion weighted imaging, perfusion weighted imaging and MR spectroscopy by single-voxel techniques.

Results

The overall results based on differentiation of typical from atypical and malignant meningiomas by advanced MRI techniques. Twenty four patients had typical meningioma and 6 patients had atypical and malignant Meningiomas by advanced MRI techniques.

Conclusion

Appearance of meningiomas on DWIs and the calculation of ADC values could be correlated with their histopathological grading. On MRS, alanine was not found to be increased in all meningiomas, so MRS cannot reliably differentiate typical intracranial meningomas from atypical meningiomas.     

3D dynamic pituitary MR imaging with CAIPIRINHA: Initial experience and comparison with 2D dynamic MR imaging

Objectives

To evaluate the validity of 3D dynamic pituitary MR imaging with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA), with special emphasis on demarcation of pituitary posterior lobe and stalk.

Methods

Participants comprised 32 patients who underwent dynamic pituitary MR imaging due to pituitary or parasellar lesions. 3D dynamic MR with CAIPIRINHA was performed at 3 T with 20-s-interval, precontrast, 1st to 5th dynamic images. Normalized values and enhanced ratios (dynamic postcontrast image values divided by precontrast ones) were compared between 3D and 2D dynamic MR imaging for patients with visual identification of posterior lobe and stalk.

Results

In 3D, stalk was identified in 29 patients and unidentified in 3, and posterior lobe was identified in 28 and unidentified in 4. In 2D, stalk was identified in 26 patients and unidentified in 6 patients, and posterior lobe was identified in 15 and unidentified in 17. Normalized values of pituitary posterior lobe and stalk were higher in 3D than 2D (P < 0.001). No significant difference in enhancement ratio was seen between 3D and 2D.

Conclusions

3D dynamic pituitary MR provided better identification and higher normalized values of pituitary posterior lobe and stalk than 2D.     

Prognostic indices for cerebral venous thrombosis on CT perfusion: A prospective study

Purpose

We determined the prognostic significance of CT perfusion characteristics of patients with cerebral venous sinus thrombosis (CVST) and assessed the change in perfusion parameters following anticoagulation therapy.

Materials and methods

20 patients with CVST diagnosed on non-contrast computed tomography (NCCT), magnetic resonance imaging (MRI), and magnetic resonance venography (MRV) were included in this study. The initial CT perfusion study was performed at the time of admission. The following perfusion parameters: relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative mean transit time (rMTT) were calculated in the core and periphery of the affected area of the brain. Follow-up CT perfusion studies were performed at 1 month following anticoagulation therapy and the perfusion parameters thus obtained were compared with pre-treatment results. Receiver operating characteristic (ROC) curve analysis was performed to determine the prognostic significance of perfusion parameters.

Results

All patients in this study showed areas of hypoperfusion on CT perfusion. To determine the favorable clinical outcome on basis of perfusion parameters, ROC curve analysis was performed which showed that the optimal threshold for rCBF > 60.5%, rCBV > 75.5%, and rMTT < 148.5% correlated with better clinical outcomes. Post treatment perfusion parameters showed significant correlation in core of the lesion (p < 0.05) than in the periphery.

Conclusion

CT perfusion studies in CVST are a good prognostic tool and yield valuable information regarding clinical outcome.     

MR spectroscopy and diffusion MR imaging in characterization of common sellar and supra-sellar neoplastic lesions

Background

MR spectroscopy and diffusion-weighted imaging are useful non invasive imaging modalities used for characterization of different sellar and suprasellar lesions.

Patient and methods

We studied 30 cases of suprasellar SOLs (as proved by conventional MRI), MRS and DWI. Our findings were correlated with histopathological analysis after surgical resection.

Results

Three false positive cases in which cMRI give diagnosis mismatched with that obtained after adding the MRS findings and ADC values. MR spectrum type IIC is found in macroadenoma, craniopharyngioma, meningioma and germinoma with characteristic broad lipid peak in the second and forth types and elevated alanine peak in meningioma. Glioma had MRS appearance of type IIB. Simple differentiation between tumor types were achieved by the mean ADC values which were statistically significant (p < 0.001) when correlated to the histological diagnosis. When the ADC value of 0.6 × 10⁻³ mm²/s this strongly points to macroadenoma, ADC value of 1.05 × 10⁻³ mm²/s in meningiomas, ADC value 1.88 8 × 10⁻³ mm²/s strongly points to craniopharyngioma, while gliomas and germinoma had ADC values 1.6 × 10⁻³ mm²/s and 1.0 × 10⁻³ mm²/s respectively.

Conclusion

MR spectroscopy and DWMRI are considered important diagnostic tools complementary to cMRI in pre-surgical evaluation and discrimination between different sellar and suprasellar lesions.