Gokhan Gokalp

The contribution of diffusion-weighted MR imaging to distinguishing typical from atypical meningiomas

IntroductionAtypical/malignant meningiomas recur more frequently then typical meningiomas. In this study, the contribution of diffusion-weighted MR imaging to the differentiation of atypical/malignant and typical meningiomas and to the determination of histological subtypes of typical meningiomas was investigated.MethodsThe study was performed prospectively on 39 patients. The signal intensity of the lesions was evaluated on trace and apparent diffusion coefficient (ADC) images. ADC values were measured in the lesions and peritumoral edema. Student’s t-test was used for statistical analysis. P<0.05 was considered statistically significant.ResultsMean ADC values in atypical/malignant and typical meningiomas were 0.75±0.21 and 1.17±0.21, respectively. Mean ADC values for subtypes of typical meningiomas were as follows: meningothelial, 1.09±0.20; transitional, 1.19±0.07; fibroblastic, 1.29±0.28; and angiomatous, 1.48±0.10. Normal white matter was 0.91±0.10. ADC values of typical meningiomas and atypical/malignant meningiomas significantly differed (P<0.001). However, the difference between peritumoral edema ADC values was not significant (P>0.05). Furthermore, the difference between the subtypes of typical meningiomas and atypical/malignant meningiomas was significant (P<0.001).ConclusionDiffusion-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.

The contribution of 3D-CISS and contrast-enhanced MR cisternography in detecting cerebrospinal fluid leak in patients with rhinorrhoea

The aim of this prospective study was to evaluate the value of unenhanced (three-dimensional constructive interference in steady state (3D-CISS)) and contrast-enhanced 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 T1-weighted spin-echo sequences in three planes before and after intrathecal contrast media administration 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 beta2-transferrin measurement.

Solitary metastases and high-grade gliomas: radiological differentiation by morphometric analysis and perfusion-weighted MRI

AIM To evaluate the value of morphometric analysis and perfusion-weighted magnetic resonance imaging (MRI) in differentiating solitary metastases from high-grade gliomas. MATERIALS AND METHODS Forty-eight tumours (22 high-grade gliomas and 26 solitary hemispheric metastases) were evaluated using conventional and perfusion-weighted MRI. T2-weighted, gradient-echo, echo-planar sequences were used for perfusion-weighted MRI. Relative cerebral blood volume (rCBV) ratios were calculated by dividing the rCBV of the intratumoural and peritumoural areas with the average CBV value of the normal white matter areas. Morphometric analysis was carried out by proportioning the area of peritumoural oedema to the mass area. Mann-Whitney U test and ROC curve analysis were applied for statistical analysis. P<0.05 was accepted as statistically significant. RESULTS Mean rCBV ratios of intratumoural areas of high-grade gliomas and metastases were 5.02+/-2.47 and 4.62+/-2.46, respectively. No statistically significant difference was found (p=0.515). rCBV ratios of peritumoural oedema were 0.89+/-0.51 in high-grade gliomas and 0.31+/-0.12 in metastases. The difference was statistically significant (p<0.001). According to the results of morphometric analysis, a statistically significant difference was present between the two tumour types (p<0.001). CONCLUSION Measuring the oedema: mass and rCBV ratios of the oedema surrounding the tumour prior to operation in solitary masses proved to be useful for differentiating metastases from high-grade gliomas.

Role of Duplex Power Doppler Ultrasound in Differentiation between Malignant and Benign Thyroid Nodules

Objective To evaluate the usage of duplex power Doppler ultrasound (PDUS) for the differentiation of benign and malignant thyroid nodules. Materials and Methods We 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. Results A 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). Conclusion Vascularity 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.

Power Doppler sonography: Anything to add to BI-RADS US in solid breast masses?

OBJECTIVE To evaluate the contribution of power Doppler ultrasonography (PDUS) to breast imaging reporting and data system ultrasonography (BI-RADS US) categorization of solid breast masses. MATERIALS AND METHODS Totally 94 solid lesions with histopathological results in 49 patients were included in the study. US features of the lesions were classified according to American College of Radiologists (ACR) BI-RADS US lexicon. Lesions were evaluated qualitatively according to their PDUS properties and quantitatively with spectral analysis. Hypervascularity, penetration of vessels into the mass or branching-disordered course and resistivity index values higher than 0.85 were accepted as probable malignant criteria. RESULTS Fifty-five of 94 lesions were benign (58.5%), while 39 (41.5%) were malignant histopathologically. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of US and PDUS in the diagnosis of malignant lesions were 100%, 58.2%, 62.9%, 100% and 71.8%, 81.8%, 73.7%, 80.4%, respectively. Criteria used for the distinction of malignant and benign lesions like number of vessels (p<0.05), distribution of tumoral vessels, morphology of vessels and resistivity index values higher than 0.85 showed statistically significant difference (p<0.001). When sonographic findings were combined with PDUS and spectral analysis findings, sensitivity, specificity, PPV and NPV were 100%, 52.7%, 60% and 100%, respectively. CONCLUSION PDUS and spectral analysis have no contribution to BI-RADS US. For the spectral analysis, when RI value is one or greater, malignancy risk significantly increases.

Neurochemical–structural changes evaluation of brain in patients with obstructive sleep apnea syndrome

PURPOSE To evaluate neurochemical and structural changes in the patients with newly diagnosed obstructive sleep apnea syndrome (OSAS) by MR spectroscopy (MRS), T2 relaxometry, and diffusion weighted imaging (DWI). MATERIAL AND METHODS Following the acquisition of routine cranial MR, MRS, T2 relaxometry, and DWI images; spectroscopic metabolite ratios and DWI-T2 relaxometry findings of the thalami, hippocampi, frontal white matter (FWM) and frontal cortex of 24 OSAS patients and 9 controls were statistically compared. The relationship between two groups was evaluated with Mann-Whitney test. RESULTS Spectroscopic measurements in the frontal cortex and frontal white matter of the OSAS patients revealed significantly lower NAA/Cr ratios than those of the control group (P=0.004 and P=0.006, respectively). The measurements in the frontal white matter of the OSAS patients exhibited significantly lower NAA/Cho ratios compared with those of the control group (P=0.005). Thalamic Cho/Cr ratios of the patient group were significantly higher than those of the control group (P=0.002). In terms of the ADC-T2 relaxometry values, there was no significant relationship between the patient and the control groups (P>0.05). CONCLUSION MRS is a useful and non-invasive modality in showing neurochemical changes in various regions of the brain but our data does not show any change on diffusion weighting or T2 quantification in the OSAS group. DWI and T2 relaxometry appear to be not effective techniques to evaluate the brain structural changes of the patients with newly diagnosed OSAS.

Adhesive capsulitis: Contrast-enhanced shoulder MRI findings

Purpose: Evaluation of contrast‐enhanced magnetic resonance imaging (CE‐MRI) findings in cases clinically diagnosed as adhesive capsulitis (AC).

Using chemical-shift MR imaging to quantify fatty degeneration within supraspinatus muscle due to supraspinatus tendon injuries

The objective of this study was to prospectively quantify the fatty degeneration of supraspinatus (SSP) muscle due to SSP tendon injuries by using chemical-shift magnetic resonance imaging (CS-MRI). Forty-one patients with suspected rotator cuff tear or impingement examined with MR arthrography were included in the study. The following images were obtained after injection of diluted gadolinium chelate into glenohumeral joint: fat-saturated T1-weighted spin echo in the coronal, axial, and sagittal-oblique plane; fat-saturated T2-weighted and intermediate-weighted fast spin-echo in the coronal-oblique plane; and T1-weighted spin echo in the sagittal-oblique plane. CS-MRI was performed in the coronal plane using a double-echo fast low-angle shot (FLASH) sequence. SSP tendon changes were classified as normal, tendinosis, and partial and complete tear according to MR arthrography findings. Fatty degeneration was quantified after measurement of signal intensity values within the region of interest (ROI) placed over SSP muscle. Signal intensity (SI) suppression ratio and SI index were calculated with the values obtained. Degrees of fatty degeneration depicted in normal subjects and subjects with rotator cuff injuries were compared. Median (min:max) was used as descriptive values. SI suppression ratio was −3.5% (−15.5:3.03) in normal subjects, whereas it was −13.5% (−28.55:−6.60), −30.7% (−41.5:−20.35), and −43.75% (−62:−24.90) in tendinosis, partial and complete tears, respectively. SI index was 0.75% (−6:11.5) in normal subjects. It was 10% (4.50:27), 26.5% (19.15:35.5), and 41% (23.9:57) in tendinosis, partial and complete tears, respectively. The increase in degree of fatty degeneration parallels the seriousness of tendon pathology. CS-MRI is a useful method for grading fat accumulation within SSP muscle.

Ideal combination of MRI sequences for perianal fistula classification and the evaluation of additional findings for readers with varying levels of experience.

PURPOSE The aim of our study was to assess the contribution of various magnetic resonance imaging (MRI) sequences in determining the type of perianal fistula and in obtaining critical information for surgical decisions, as well as to define the optimal combination of sequences for readers with varying levels of experience. MATERIALS AND METHODS The study included 33 MRI examinations in 26 patients with suspected perianal fistula. The following sequences were obtained in both the coronal and axial planes: thin slice, high resolution T1-weighted (W) spin echo; T2-weighted turbo spin echo; short tau inversion recovery (STIR); and native and contrast enhanced T1-weighted gradient echo fast low-angle shot (FLASH) images with fat suppression (FS-CE-T1W-GRE). The examinations were interpreted by three radiologists with varying degrees of experience in two different sessions, and the inter-reader agreement was assessed. Seventeen of the patients underwent surgery. The agreement between the surgical findings and the MRI results were evaluated. RESULTS A statistically significant concordance between the fistula classification and surgery was achieved with the FS-CE-T1W-GRE sequence for Reader 1 (Cramers V=0.701, P = 0,022) and Reader 3 (Cramers V=0.716, P = 0,043). For Reader 2, statistically significant concordance between fistula classification and surgery was achieved with the FS-CE-T1W-GRE (Cramers V=0.703, P = 0,011) and the T2W images (Cramers V=0.648, P = 0,027). For all sequences, there was statistically significant agreement between readers for fistula classification, internal opening location, and the presence of sinus tracts, abscess, a horseshoe component, and inflammation. CONCLUSION For experienced readers, combining FS-CE-T1W-GRE images with either T2W or STIR images collected in both the coronal and axial planes was sufficient to make an assessment before deciding the surgical extent of the procedure.

Transient splenial lesion of corpus callosum associated with antiepileptic drug: conventional and diffusion-weighted magnetic resonance images

Transient focal lesions of splenium of corpus callosum can be seen as a component of many central nervous system diseases, including antiepileptic drug toxicity. The conventional magnetic resonance (MR) findings of the disease are characteristic and include ovoid lesions with high signal intensity at T2-weighted MRI. Limited information exists about the diffusion-weighted MRI characteristics of these lesions vanishing completely after a period of time. We examined the conventional, FLAIR, and diffusion-weighted MR images of a patient complaining of depressive mood and anxiety disorder after 1 year receiving antiepileptic medication.