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Air embolism is known to be a complicating factor in several clinical settings, including thoracic, cardiovascular, and neurosurgical operations; central line placement; and penetrating thoracic and cranial trauma. There are, however, only few case descriptions for cardiopulmonary resuscitation massive cerebral air embolism, and the frequency of this supposedly rare complication is unknown. Computed tomography is useful for showing cerebral air embolism. In this report, we present a 16-year-old adolescent girl with cerebrovascular air embolism on computed tomographic examination after a posttraumatic cardiopulmonary resuscitation and discuss the reasonable mechanisms of cerebrovascular air embolism.

Purpose: The aim of this study was to evaluate the efficiency of MR cisternography (MRC) in the diagnosis of idiopathic normal-pressure hydrocephalus (INPH) and in the prediction of the response to shunt treatment., Materials and Methods: Thirty-six patients with the diagnosis of "probable INPH" were included in the study group and 15 asymptomatic age-matched individuals were included in the control group. Pre-contrast T1-weighted (T1W) imaging was followed by intrathecal administration of 1 ml gadopentetate dimeglumine. Post-contrast T1W images were taken at the 12th, 24th and 48th hours. The presence of contrast material in the lateral ventricles for more than 24 hours was accepted as a positive diagnosis of INPH. Data from both groups were compared statistically. Statistical significance was accepted for P < 0.05., Results: All of the INPH patients had remaining contrast material in their lateral ventricles at the 12th and 24th hours, while only 28 (78%) patients had contrast material remaining at the 48th hour after MRC. Only 3 (20%) of the control cases had remaining contrast material in their lateral ventricles at the 24th hour. No contrast material was present in the control cases at the 48th hour. The contrast material was found to be significantly more prevalent in the INPH patients at the 24th and the 48th hours compared with the control cases (P < 0.001). Shunt placement was performed in 14 INPH patients, and eight improved after shunt placement. All patients (100%) who improved after shunt placement had remaining contrast material in their lateral ventricles at the 24th and at the 48th hours. The sensitivity and specificity of MRC in the prediction of the response to shunt treatment were 100% and 17%, respectively., Conclusion: MRC does not use ionizing radiation and is generally a useful procedure to diagnose NPH and to predict a positive response to shunt treatment; thus, we recommend MRC after routine MRI in patients with the presumed diagnosis of NPH.

Purpose: T1-weighted (T1W) magnetic resonance images with magnetization transfer (MT) are widely used in the evaluation of multiple sclerosis (MS) plaques. We aimed to evaluate the contribution of the subtraction technique with MT in the detection of acute MS plaques., Materials and Methods: Sixty-four patients during an MS attack were enrolled in the study. Axial T1W spin echo (SE) with MT, axial-sagittal T2W fast SE, axial FLAIR and postcontrast axial T1W SE magnetic resonance imaging sequence with MT were acquired from all patients. The subtraction (postcontrast-precontrast) images were obtained on the workstation. FLAIR and T2W images were used as reference for plaque imaging. Contrast material enhanced plaques were considered as acute plaques. Qualitatively, both subtracted and contrast-enhanced with MT images were evaluated visually. Quantitatively, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated., Results: A total of 464 plaques were detected on T2W and FLAIR images. Thirty-five acute plaques were detected on both postcontrast MT and subtracted images. Additionally, 66 acute plaques were only detected on subtracted images visually. CNR and SNR values of acute MS plaques were significantly higher on subtracted MT images than on postcontrast MT images (P < 0.001)., Conclusion: The subtraction technique seems to facilitate the detection of acute MS plaques by intensifying the visibility of poorly enhanced plaques without use of high dose contrast medium. We suggest the use of subtraction technique in routine imaging work-up of MS patients with acute attacks.

Purpose: To investigate neuronal dysfunction in the thalami of juvenile myoclonic epilepsy (JME) by using proton magnetic resonance spectroscopy (MRS)., Methods: We performed single-voxel proton MRS over the right and the left thalami of 15 consecutive patients (10 women, 5 men) with JME (mean age 20.3 years) and 16 healthy volunteers (10 women, 6 men) (mean age 24.5 years). All patients had seizure onset in late childhood-teenage, normal neurologic examination, typical electroencephalogram (EEG) of JME and normal magnetic resonance imaging (MRI). We determined N-acetylaspartate (NAA) values and NAA over creatine-phosphocreatine (Cr) values. Mann-Whitney U-test was used to evaluate group differences., Results: Group analysis showed that echo time (TE) 270 integral value of NAA over left thalamus were significantly decreased in JME patients as compared with controls (34.6033+/-15.8386; 48.0362+/-22.2407, respectively, P=0.019). Also group analysis showed that thalami NAA/Cr ratios were significantly decreased in JME patients (right side, 2.21+/-1.07; left side 2.00+/-0.72) as compared with controls (right side, 3.45+/-1.50; left side, 3.08+/-1.60; P=0.011 and P=0.030, respectively)., Conclusion: In the previous studies, NAA values in patients with JME found that they were not statistically lower in thalami than control group. But, in our study, NAA value was found low as well. It has been known that NAA is a neuronal marker and hence it is a valuable metabolite in the neuron physiopathology. As a result, in the patients with JME we tried to support the theory that the underlying mechanism of the generalized seizures was the abnormal thalamocortical circuity, determining the thalamic neuronal dysfunction in MRS statistically.

Purpose: To explore the use of fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted echo planar imaging sequences in imaging of the intracranial epidermoid and arachnoid cysts and assess the efficiency of those sequences in differentiation of epidermoid cysts from arachnoid cysts., Materials and Methods: This study was performed prospectively by using two different MR devices in 24 patients (12 epidermoid cysts, 12 arachnoid cysts). T1-weighted spin echo, T2-weighted fast spin echo, FLAIR and diffusion-weighted echo planar imaging sequences were used. Lesions were evaluated qualitatively and quantitatively. In qualitative evaluation, the signal intensity of the lesions were compared with cerebral spinal flow. Quantitative evaluation was made from the diffusion-weighted images by measuring values of apparent diffusion coefficient (ADC) from the cystic spaces and cerebral white matters. In statistic analyses, Mann-Whitney U test was used., Results: Arachnoid cysts had the same intensity with cerebral spinal flow in all sequences. Mean ADC value was 3.41 +/- 0.17 x 10(-3) mm2/sn. All epidermoid cysts on diffusion-weighted trace images were more hyperintense than brain parenchyma. The mean ADC value of the epidermoid cysts was 1.15 +/- 10(-3) mm2/sn. The ADC values of the epidermoid cysts were lower than the arachnoid cysts (p < 0.001), but were higher than the cerebral white matter (p < 0.01)., Conclusion: FLAIR sequences were superior to conventional sequences in imaging of epidermoid cysts and in differentiation of epidermoid cysts from arachnoid cysts. It was also shown that diffusion-weighted trace imaging and measurement of ADC values might be used as problem solving tools. Furthermore, those sequences may be a guide to demonstrate postoperative residual lesions.

Purpose: To evaluate the potential role of ECG-gated flow sensitive phase contrast cine magnetic resonance (MR) imaging in detecting the communication between cystic intracranial lesions and neighboring cerebrospinal fluid (CFS) spaces., Materials and Methods: Twenty one patients with intracranial cystic lesions (arachnoid cyst, 15; epidermoid cyst, 2; glioma, 1; dermoid cyst, 1; and mega cisterna magna, 2) underwent CSF flow studies in addition to the conventional MR sequences. MR imaging was performed with ECG gated two dimensional fast imaging steady-state precession sequence (2D-FISP). Using the cine images obtained per cardiac cycle, we tried to identify the communication between cysts or cyst-like structures and neighboring CSF spaces. Results were compared with intraoperative findings, computed tomography (CT) cisternography and scintigraphy., Results: In 14 cystic lesions, no communication was identified. In five arachnoid cysts, a pulsatile CSF flow was seen in the cysts. In the two enlarged cisterna magnas there was a pulsatile flow coming from the central CSF spaces. All intraoperative, CT cisternography and scintigraphy findings were compatible with the results of the MR flow studies., Conclusion: Cine-mode MR imaging with ECG gated 2D phase contrast MR sequence technique is a reliable noninvasive alternative to CT cisternography for functional evaluation of the cystic lesions, because it enables visualization of the flow communication between cysts or cyst-like structures and neighboring CSF spaces.

Purpose: Mesial temporal sclerosis is the most common pathological finding in temporal lobe epilepsy (TLE). Accurate identification and localization of this pathology before surgery is obligatory for a good prognosis after the operation. In this study we compared the results of qualitative and quantitative MR findings of the hippocampus in TLE., Materials and Methods: The study group consisted of 42 patients with the definitive diagnosis of temporal lobe complex partial seizure and 42 control subjects. Extrahippocampal lesions had been detected in 10 patients. Qualitative evaluation was performed by T2-weighted FSE, fast FLAIR, T1-weighted fast IR sequences on coronal plane. We also performed volumetric measurements of the hippocampus in 32 patients with TLE and compared the results with those of the control group. The mesial temporal lobes were investigated with SVS-proton MR spectroscopy using a PRESS sequence with an echo time of 135 milliseconds and T2 relaxation values., Results: Hippocampal pathology was detected on paracoronal plane at T1-weighted fast IR (84%), T2-weighted FSE (60%) and fast FLAIR (88%) images. On comparing the hippocampal volumes of the patient and control groups, the hippocampal of the control group were found to be significantly larger (p < 0.05). Considering the right-left volume differences, 28 patients (88%) were found to have unilateral hippocampal atrophy. The most consistent MR spectroscopic parameter for definite lateralization was the NAA/Cho + Cr ratio (100%). Accurate epileptic focus lateralizations were made in 27 subjects (84%) by using hippocampal T2 relaxation time, and in 12 subjects (33%) by using temporal white matter T2 relaxation time., Conclusion: MR imaging is highly sensitive in detecting and locating abnormalities in the temporal lobe and hippocampus in patients with TLE. Implementation of FLAIR and T1 IR sequences in the routine MR examination of patients with TLE is recommended. With adequate asymmetry index, NAA/Cho + Cr ratio is sensitive in predicting the side of involvement in patients with TLE. For medically intractable TLE patients MRS is a very important guiding tool prior to surgery.

Purpose: Our purpose was to assess the value of diffusion-weighted steady-state free precession (SSFP) sequence for differentiating between benign and pathologic compression fractures., Materials and Methods: Forty-nine patients with 63 acute vertebral compression fractures caused by osteoporosis (n = 23), trauma (n = 7), malignancy (n = 30), infection (n = 3) were examined with a diffusion-weighted SSFP sequence (diffusion gradient strength; 23 mT/m, diffusion pulse length 5 ms), T1-weighted turbo spin-echo sequence, and short-inversion-time (TI 150 ms) T2-weighted turbo inversion recovery sequence. The signal intensity characteristics were analyzed qualitatively and quantitatively for all sequences. Statistical analysis was performed with the Student's t test., Results: In diffusion-weighted MR imaging, benign osteoporotic and traumatic fractures were hypo- to isointense to adjacent normal vertebral bodies. Pathologic and infectious compression fractures were hyperintense to normal vertebral bodies. Pathologic vertebral fractures had positive bone marrow contrast ratios at diffusion-weighted imaging, whereas non infectious benign vertebral fractures had negative values (p < 0.001). The difference in bone marrow contrast ratios for benign and pathologic compression fractures at T1-weighted TSE and T2-weighted turbo IR was not significant (p > 0.01)., Conclusion: Diffusion-weighted SSFP sequence provides unique information that significantly impacts the accuracy of radiologic diagnosis. Diffusion-weighted SSFP sequence may allow the differentiation of acute benign osteoporotic fractures from malignant compression fractures. Acute benign osteoporotic or traumatic fractures show hypointense or isointense signal on diffusion-weighted sequences that reflects persistent free water proton mobility. Malignant compression fractures show hyperintensity compared with normal surrounding bone marrow probably due to altered water proton mobility within the neoplasm.

Objective: The purpose of this study was to evaluate the long-term efficacy of polyurethane stent placement in adults with nasolacrimal duct obstruction., Subjects and Methods: Polyurethane stents were placed under fluoroscopic guidance in 52 eyes of 49 patients (mean age, 43 years) with severe epiphora due to idiopathic nasolacrimal duct obstruction. The obstruction was complete in 44 eyes and partial in eight. Clinical success was defined as complete resolution of or great improvement in the symptoms of epiphora and the patency of the lacrimal system to irrigation. Mean follow-up was 23 months (range, 14-44 months)., Results: Stent placement was technically successful in 50 eyes (96%). The mean fluoroscopy screening time was 2.2 min (range, 0.2-5.8 min). Two patients were lost to follow-up. Clinical success was obtained in 33 (69%) of 48 eyes. Lacrimal symptoms developed in 23 (70%) of these 33 eyes at least once during the follow-up, but these patients responded well to topical drug treatment and lacrimal irrigation. External dacryocystorhinostomy was performed in 13 eyes after failure of the stents. At surgery, lacrimal sacs were shrunken, hyperemic, and fragile in all eyes, making it difficult to anastomose with nasal mucosa. Histologic examination showed granulation tissue and chronic inflammation of the sac epithelium., Conclusion: The success rate of the nasolacrimal stent decreases as follow-up lengthens. After stent treatment, lacrimal symptoms frequently develop, even if the stent remains patent, and require multiple office visits and therapy. The polyurethane stent may induce a chronic inflammatory response in the lacrimal sac, which can interfere with subsequent dacryocystorhinostomy.