Cem Tayfun

The added value of the apparent diffusion coefficient calculation to magnetic resonance imaging in the differentiation and grading of malignant brain tumors.

Objective: ADC calculation can improve the diagnostic efficacy of MR imaging in brain tumor grading and differentiation. Methods: Apparent diffusion coefficient (ADC) values and ratios of 33 low-grade (23 astrocytomas, 10 oligodendrogliomas) and 40 high-grade (25 metastases and 15 high-grade astrocytomas) malignant tumors were prospectively evaluated. Results: Tumoral ADC values (r = −0.738, P < 0.000) and ratios (r = −0.746, P < 0.000) were well correlated with higher degree of malignancy and quite effective in grading of malignant brain tumors (P < 0.000). By using cutoff values of 0.99 for tumoral ADC value and 1.22 for normalized ADC ratio, the sensitivity of MR imaging could be increased from 72.22% to 93.75% and 90.63%, the specificity from 81.08% to 92.68% and 90.24%, PPV from 78.79% to 90.91% and 87.88%, and NPV from 75.00% to 95.00% and 92.50%, respectively. Conclusion: ADC calculation was quite effective in grading of malignant brain tumors but not in differentiation of them and added more information to conventional contrast-enhanced MR imaging.

Cerebrospinal fluid flow imaging by using phase-contrast MR technique.

Cerebrospinal fluid (CSF) spaces include ventricles and cerebral and spinal subarachnoid spaces. CSF motion is a combined effect of CSF production rate and superimposed cardiac pulsations. Knowledge of CSF dynamics has benefited considerably from the development of phase-contrast (PC) MRI. There are several disorders such as communicating and non-communicating hydrocephalus, Chiari malformation, syringomyelic cyst and arachnoid cyst that can change the CSF dynamics. The aims of this pictorial review are to outline the PC MRI technique, CSF physiology and cerebrospinal space anatomy, to describe a group of congenital and acquired disorders that can alter the CSF dynamics, and to assess the use of PC MRI in the assessment of various central nervous system abnormalities.

Imaging findings in idiopathic granulomatous mastitis: A review with emphasis on magnetic resonance imaging

Objective To describe magnetic resonance (MR) imaging features of patients with a histologic diagnosis of idiopathic granulomatous mastitis (IGM). Methods Dynamic contrast-enhanced MR imaging was performed with a 1.5-T MR unit. Postprocessing of images included subtraction and calculation of time-intensity curves of the enhancing regions at several points in all patients. Results In addition to granulomatous inflammation, biopsy slides of 5 patients demonstrated abscess formation without a specific organism (aseptic abscess). One patient had a fibrotic tissue component. Magnetic resonance imaging findings were heterogeneously enhancing areas with (n = 5) and without (n = 1) multiple ring-like enhanced abscesses and a circumscribed lesion with heterogeneous contrast enhancement (n = 1). Time-intensity curves showed a benign pattern in all but 1 patient. Conclusion Idiopathic granulomatous mastitis has a number of appearances on MR imaging. Magnetic resonance imaging with measurement of time-signal intensity curves may support the findings of ultrasonography and mammography in distinguishing benign inflammatory breast disorders from malignant ones; however, biopsy still remains the only method of definite diagnosis.

High-resolution CT findings in patients with pulmonary tuberculosis: correlation with the degree of smear positivity.

Background There are data about the relationship between morphologic findings on high-resolution computed tomography (HRCT) and the number of acid-fast bacilli (AFB) on sputum smears in patients with pulmonary tuberculosis (PTB). It was also shown that existence of cavities and airspace consolidation might be related to smear positivity in PTB patients. However, there is no study suggesting a relationship between AFB on sputum smears and radiologic extent of disease based on HRCT findings. Aim In this study, we investigated a relationship between the degree of smear positivity and radiologic extent of disease based on HRCT findings and, the degree of smear positivity and different pulmonary parenchymal changes on HRCTs of the PTB patients. Methods Sixty-one male patients with PTB (mean age: 22±3.2) were included into the study. HRCT images were assessed for patterns, distribution, and profusion of pulmonary abnormalities. Dividing the lungs into 3 zones, profusion of abnormalities was assessed. A profusion score was given. Patients were divided as smear positive and smear negative and compared for the scores of HRCT findings. Smear-positive patients were divided into 4 groups as per grading of the sputum AFB smear: group I (sputum 1+), group II (sputum 2+), group III (sputum 3+), and group IV (sputum 4+). Correlations were investigated between the degree of smear positivity and the scores of HRCT findings. Results A significant correlation between radiologic extent of the disease based on HRCT and the degree of smear positivity was found (r=0.63, P=0.0001). There were also significant correlations between the degree of smear positivity and the scores of different HRCT findings. Nodule, cavity, and bronchial lesions are the most important contributors of the predictive properties of the total score. There was significant differences for the scores of HRCT findings between smear-positive and smear-negative patients. Conclusions Our study suggests that radiologic extent of disease based on HRCT findings in patients with PTB correlated with the degree of smear positivity. Different HRCT findings such as nodule, cavitation, ground-glass opacity, consolidation, and bronchial lesion are significantly associated with smear-positive PTB. Particularly, nodules, cavities, and bronchial lesions might be predictors of smear positivity in patients with PTB. This study also suggests that the thickness of cavity wall and the distance of cavity from central airways might be related to the degree of smear positivity.

Pediatric abdominal masses: diagnostic accuracy of diffusion weighted MRI.

PURPOSE To retrospectively identify apparent diffusion coefficient (ADC) values of pediatric abdominal mass lesions, to determine whether measured ADC of the lesions and signal intensity on diffusion-weighted (DW) images allow discrimination between benign and malignant mass lesions. MATERIALS AND METHODS Approval for this retrospective study was obtained from the institutional review board. Children with abdominal mass lesions, who were examined by DW magnetic resonance imaging (MRI) were included in this study. DW MR images were obtained in the axial plane by using a non breath-hold single-shot spin-echo sequence on a 1.5-T MR scanner. ADCs were calculated for each lesion. ADC values were compared with Mann-Whitney U test. Receiver operating characteristic curve analysis was performed to determine cut-off values for ADC. The results of visual assessment on b800 images and ADC map images were compared with chi-square test. RESULTS Thirty-one abdominal mass lesions (16 benign, 15 malignant) in 26 patients (15 girls, 11 boys, ranging from 2 days to 17 years with 6.9 years mean) underwent MRI. Benign lesions had significantly higher ADC values than malignant ones (P < .001). The mean ADCs of malignant lesions were 0.84 +/- 1.7x10(-3) mm2/s, while the mean ADCs of the benign ones were 2.28 +/- 1.00x10(-3) mm2/s. With respect to cutoff values of ADC: 1.11x10(-3) mm2/s, sensitivity and negative predictive values were 100%, specificity was 78.6% and positive predictive value was 83.3%. For b800 and ADC map images, there were statistically significant differences on visual assessment. All malignant lesions had variable degrees of high signal intensity whereas eight of the 16 benign ones had low signal intensities on b800 images (P < .001). On ADC map images, all malignant lesions were hypointense and most of the benign ones (n=11, 68.7%) were hyperintense (P < .001). CONCLUSION DW imaging can be used for reliable discrimination of benign and malignant pediatric abdominal mass lesions based on considerable differences in the ADC values and signal intensity changes.

Thin-section axial multidetector computed tomography and multiplanar reformatted imaging of children with suspected foreign-body aspiration: is virtual bronchoscopy overemphasized?

Purpose: To determine the added value of multidetector computed tomography (MDCT)-assisted virtual bronchoscopy (VB) to axial MDCT and multiplanar reformatted (MPR) imaging with respect to conventional bronchoscopy in the evaluation of children with suspected foreign-body aspiration (FBA). Material and Methods: Twenty-one consecutive children (14 male, seven female, age 8 months–7 years, mean age 3.5 years) presenting with the suspicion of FBA were examined with 16-slice MDCT using 100–120 kV, 30–50 mA, 1-mm section thickness, 1.2 pitch ratio, and 0.6–1.0-mm reconstruction interval. Before CT examinations, chest radiographies were also obtained in all cases. VB and MPR imaging were carried out after MDCT examinations. Results: Nine foreign bodies were identified by gold-standard conventional bronchoscopy. VB, thin-section axial MDCT, and MPR images identified eight of nine foreign bodies. CT scans with MPR images and VB did not reveal a chronic foreign body; and, in one patient, endobronchial mucous was diagnosed as the foreign body. The sensitivity, specificity, and accuracy of thin-section axial MDCT and MPR images alone in the diagnosis of FBA were 88.9%, 91.7%, and 90.5%, respectively. Results were the same as those obtained when VB was also included. Conclusion: MDCT with VB and axial/MPR images provide equally valuable information in children with suspected foreign-body aspiration and prevent unnecessary conventional bronchoscopic examinations. However, VB increases total examination time and cost, and it does not provide additional information over MPR images in the evaluation of foreign-body aspiration.

Value of magnetic resonance imaging in the depiction of intravenous leiomyomatosis extending to the heart.

Intravenous leiomyomatosis is a seldom neoplasia characterized by invasion of venous channels by a benign smooth muscle tumor originating either from a uterine myoma or from vessel wall. Extension to the heart may cause mechanical obstruction and is frequently misdiagnosed as a right-atrial myxoma. We present a case of recurrent intravenous leiomyomatosis with previous hysterectomy because of uterine leiomyoma which have different magnetic resonance characteristics than that of the former reports.

TRUS, CT and MRI findings of hydatid disease of seminal vesicles

Abstract. Hydatid disease of the urogenital system, especially seminal vesicles and prostate, or retroperitoneum is a very rare condition. Secondary dissemination of seminal vesicles has not been described before. We describe the transrectal ultrasonography (TRUS), CT and MRI findings of a secondary solitary hydatid cyst of the left seminal vesicle, in a patient with disseminated hydatid disease involving all abdominal organs except for right kidney. We obtained typical findings of hydatid cyst at all modalities.

Diagnostic value of MRI in tuberculous meningitis

In this study 15 patients with clinical findings and positive cerebrospinal fluid analyses for tuberculous meningitis were evaluated with magnetic resonance imaging (MRI). Tuberculous meningitis was diagnosed in 11 cases when thick meningeal enhancement was present after intravenous injection of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) in T1-weighted images. Intra-axial tuberculomas were present in 8 patients, 2 of whom had intra-axial tuberculomas without MRI evidence of meningitis. Tuberculomas showed ring or nodular enhancement in postcontrast T1-weighted images, but the most significant MR feature of intraparenchymal tuberculomas was the hypointense appearance of the lesions on T2-weighted images.

Corpus callosum: Normal imaging appearance, variants and pathologic conditions

Various types of lesions can occur within the corpus callosum (CC) which is a white matter tract communicating corresponding regions of the cerebral hemispheres. Magnetic resonance imaging is the modality of choice for the evaluation of the CC. In addition, diffusion weighted imaging and diffusion tensor imaging can provide additional information about the CC. The aim of this study is to illustrate the imaging features of the corpus callosum and its pathologies.