Hail detection with a differential reflectivity radar

A major objective in the remote sensing of convective storms by radar is the clear and reliable differentiation between regions of hail and regions of rainfall. This report describes the application of the differential reflectivity (Z(DR)) radar technique to the problem of hail detection. The procedure is based on the markedly different polarization-dependent backscatter characteristics of rain and hail. Field experiments conducted in Colorado during the spring of 1983 provide significant evidence of hail detection with this new radar technique.

Smaller gray matter volumes in frontal and parietal cortices of solvent abusers correlate with cognitive deficits

BACKGROUND AND PURPOSE

Abuse of toluene-containing organic solvents by inhalation is a prevalent practice among adolescents. Long-term abuse of toluene causes cognitive deficits. The mechanism of cognitive deficits induced by long-term toluene abuse has not yet been defined. In the current study, we assessed the effects of chronic toluene abuse on cortical gray matter volume and the association between cognitive impairment and cortical gray matter volume distribution in chronic toluene abusers.

MATERIALS AND METHODS

Fifteen toluene abusers and 20 healthy control subjects matched in sex, age, education level, and handedness were investigated by structural MR imaging. The cognitive states of the subjects were assessed by using the third edition of the Wechsler Intelligence Scale for Children (WISC-III). The voxel-based comparison and correlation analyses of MR images were performed by using SPM5 software.

RESULTS

The voxel-based morphometric analysis revealed that toluene abusers had significantly lower gray matter volumes in the bilateral frontotemporal and right parietal cortices. In addition, the lower gray matter volumes in the frontal and parietal regions correlated with the duration of toluene abuse. There was a positive correlation between the WISC performance scale scores and gray matter volumes in the frontal and parietal cortices of the abusers.

CONCLUSIONS

The results of the current study demonstrate that chronic toluene abusers have smaller gray matter volumes than nonabusers in various regions of the brain. Moreover, the cognitive deficits are associated with the lower gray matter volumes in the frontal and parietal cortices of chronic toluene abusers.

Macular Retinitis as a First Sign of Subacute Sclerosing Panencephalitis: The Importance of Early Diagnosis

PURPOSE

Subacute sclerosing panencephalitis (SSPE) is a subacute inflammatory and neurodegenerative encephalitis related to the measles (rubeola) virus and usually affecting children and young adults. The overwhelming majority of cases follow a progressive downhill course leading to death, although there have been a few case reports of patients who have apparently gone into remission. Ocular changes occur in up to 50% of SSPE cases. Visual complaints, if present, generally antedate the onset of neurological symptoms by a few weeks or months. Here, we report two cases of SSPE presenting with ocular findings and their prognoses.

METHODS

Case reports. In the first case, a 17-year-old male presenting with macular retinitis, the macular findings were mistaken for a heredodegenerative disorder and diagnosis was postponed until neurological findings took place. He died six months after the appearance of his first ophthalmic symptoms despite intravenous immune globulin and isoprinosine therapy. The second case was a 14-year-old male, who presented with only ophthalmological complaints. His diagnosis was based on both ophthalmological findings and high doses of measles IgG in the cerebrospinal fluid (CSF); isoprinosine and intramuscular beta-interferon therapy was started before the onset of neurological findings and in the follow-up time of about 18 months, neurological findings consistent with SSPE did not develop.

RESULTS

The characteristic finding of macular retinitis in SSPE patients is rapid recovery in about one month without therapy. After improvement, neurological findings take place. Once suspected, the diagnosis of SSPE is easily established by the demonstration of high levels of measles antibody in the serum and CSF. Early diagnosis can be made with typical ocular findings and high IgG titers for rubeola in CSF.

CONCLUSION

We suppose that ophthalmic manifestations, especially macular retinitis, may be useful in the diagnosis and management of SSPE cases with elevated IgG titers for rubeola in CSF. The typical clinical findings must be familiar to every ophthalmologist so that diagnostic pitfalls can be prevented and early therapy started. It may be discussed if early diagnosis and therapy will be possible before neurological signs appear, the prognosis of this relentless disease may show a more favorable course.

Multi-gap individual and coupled split-ring resonator structures

We present a systematic numerical study, validated by accompanied experimental data, of individual and coupled split ring resonators (SRRs) of a single rectangular ring with one, two and four gaps. We discuss the behavior of the magnetic resonance frequency, the magnetic field and the currents in the SRRs, as one goes from a single SRR to strongly interacting SRR pairs in the SRR plane. We show that coupling of the SRRs along the E direction results to shift of the magnetic resonance frequency to lower or higher values, depending on the capacitive or inductive nature of the coupling. Strong SRR coupling along propagation direction usually results to splitting of the single SRR resonance into two distinct resonances, associated with peculiar field and current distributions.

Reduced gray matter volume in the frontotemporal cortex of patients with early subacute sclerosing panencephalitis

BACKGROUND AND PURPOSE

Subacute sclerosing panencephalitis (SSPE) is a persistent infection of the central nervous system by the measles virus. Patients in the initial stages of SSPE show behavioral symptoms and usually normal cranial MR imaging findings. We aimed to investigate the gray matter volume changes in patients with early SSPE.

MATERIALS AND METHODS

Seventeen patients with SSPE with normal cranial MR imaging findings and 30 sex- and age-matched control subjects were included in the study. Clinical parameters of the patients were quantified by using a neurologic disability index (NDI) as defined previously. We obtained T1-weighted magnetization-prepared rapid acquisition gradient echo images from the patients and control subjects, and we applied an optimized method of voxel-based morphometry. We performed a cross-sectional analysis to search the gray matter volume differences between the patients and control subjects. The correlation between the gray matter distribution and the duration of symptoms, immunoglobulin G index, and NDI scores was tested.

RESULTS

We found that the cortical gray matter volume of patients was reduced in the frontotemporal regions including the bilateral cingulate cortex and amygdala. There was no correlation between the gray matter distribution of patients and the duration of symptoms or the NDI scores.

CONCLUSIONS

The current study demonstrated gray matter volume reduction in the frontotemporal cortex of patients with SSPE without any apparent lesions on conventional MR imaging. Because the cingulate cortex and amygdala are involved in emotion processing, gray matter loss in these regions may contribute to the development of early behavioral symptoms of SSPE.

Localization of cerebrospinal fluid leaks by gadolinium-enhanced magnetic resonance cisternography: a 5-year single-center experience

OBJECTIVE

Intrathecal gadolinium (Gd)-enhanced magnetic resonance (MR) cisternography is a newly introduced imaging method. Two main objectives of this study were to investigate the sensitivity of Gd-enhanced MR cisternography for presurgical localization of cerebrospinal fluid (CSF) leaks in patients with CSF rhinorrhea and to study the potential long-term adverse effects of intrathecal Gd application.

METHODS

Fifty-one patients (19 women; mean age, 36.2 yr) with CSF rhinorrhea were included in the study. A total of 0.5 ml of Gd was injected into the lumbar subarachnoid space. T1-weighted MR cisternographic images were obtained to detect CSF leakage. The patient's neurological states and vital signs were recorded for the first 24 hours after the procedure. Neurological evaluations were repeated 1, 3, and 12 months after the procedure. The patients were followed for at least 3 years with annual neurological examinations.

RESULTS

Gd-enhanced MR cisternography demonstrated CSF leaks in 43 of the 51 patients. The sensitivity of Gd-enhanced MR cisternography for localization of CSF leaks was 84%. Forty-four patients underwent surgery to repair dural tears. Surgical findings confirmed the results of Gd-enhanced cisternography in 43 of the 44 patients who underwent surgery (98%). Eight patients with negative Gd-enhanced MR cisternography had no active rhinorrhea at the time of procedure, and seven of them did not need surgery. None of the patients developed an acute adverse reaction that could be attributed to the procedure. None of the patients developed any neurological symptoms or signs caused by intrathecal Gd injection during a mean follow-up period of 4.12 years.

CONCLUSION

Gd-enhanced MR cisternography is a sensitive and safe imaging method for detection of CSF leaks in patients with rhinorrhea.

Maintaining microneurosurgical ability via staying active in microneurosurgery

The aim of this study was to evaluate the effect of staying inactive for well-trained microneurosurgical hand and to determine the critical time period in the decreasing of this special ability (microneurosurgery). For this purpose we planned a case-based and time-dependent study. This study was done on a microneurosurgeon who previously worked very actively in a department of neurosurgery (at least one operation in a day). He received a new appointment which included staying inactive in another department for a certain period of time, like a medical doctor. He did hand practice everyday and scored his ability in the aspect of total beauty and harmony of the work. The total performance of work was graded as bad, good and excellent. A bad grade was scored as 1 point, a good grade as 2 points, and an excellent grade as 3 points. The inactive time period was divided into three equal periods of 30 days. The total numerical values were calculated and a mean score was estimated for each 30-day period. The differences among the first, second, and third periods were enumerated based on the mean scores. The mean score in the first 30 days was estimated as 2.56+/-0.49, in the second 30 days as 2.16+/-0.37, and in the third 30 days 1.66+/-0.47. The differences between these values were statistically significant. The result of this study revealed that neurosurgeons may gradually lose their well trained microneurosurgical ability through staying inactive from daily practice. The maintenance of trained microneurosurgical ability should be preserved by staying active in neurosurgical operative practice.

Elimination of RF inhomogeneity effects in segmentation

There are various methods proposed for the segmentation and analysis of MR images. However the efficiency of these techniques is effected by various artifacts that occur in the imaging system. One of the most encountered problems is the intensity variation across an image. To overcome this problem different methods are used. In this paper we propose a method for the elimination of intensity artifacts in segmentation of MRI images. Inter imager variations are also minimized to produce the same tissue segmentation for the same patient. A well-known multivariate classification algorithm, maximum likelihood is employed to illustrate the enhancement in segmentation.

Use of 3DFT-CISS sequences and virtual MR endoscopy for the neuroendoscopic treatment of unilateral hydrocephalus: case illustration

OBJECTIVE

Intraventricular virtual MR endoscopic imaging of the foramen of Monro region by using three-dimensional Fourier transformation constructive interference in steady state (3DFT-CISS) magnetic resonance imaging in a patient with a unilateral congenital obstruction of the foramen of Monro by a transparent membranous septum was performed to enhance the orientation, achieve a better understanding of the pathology, and plan the surgical intervention in an endoscopic approach to the lateral ventricles.

METHODS

3DFT-CISS sequences and virtual MR endoscopic imaging were performed in a patient before and after endoscopic fenestration procedures, to communicate the lateral ventricle to the third ventricle for the treatment of unilateral ventricular enlargement.

RESULTS

Preoperative 3DFT-CISS imaging demonstrated unilateral membranous septa in the localization of the left foramen of Monro which were not observed with routine T2-weighted imaging. 3DFT-CISS imaging and T2-weighted imaging were equally useful for monitoring postoperative changes in the size of the ventricles or cysts and the presence of flow voids after fenestration procedures, but only 3DFT-CISS imaging clearly demonstrated the area of fenestration.

CONCLUSION

Virtual MR endoscopy by using 3DFT-CISS sequences is a feasible method in the planning of intraventricular real-time endoscopic surgery, for the enhancement of orientation in a surgical field, and to achieve a better understanding of the pathology.

Increased gray matter density in the parietal cortex of mathematicians: a voxel-based morphometry study

BACKGROUND AND PURPOSE

The training to acquire or practicing to perform a skill, which may lead to structural changes in the brain, is called experience-dependent structural plasticity. The main purpose of this cross-sectional study was to investigate the presence of experience-dependent structural plasticity in mathematicians' brains, which may develop after long-term practice of mathematic thinking.

MATERIALS AND METHODS

Twenty-six volunteer mathematicians, who have been working as academicians, were enrolled in the study. We applied an optimized method of voxel-based morphometry in the mathematicians and the age- and sex-matched control subjects. We assessed the gray and white matter density differences in mathematicians and the control subjects. Moreover, the correlation between the cortical density and the time spent as an academician was investigated.

RESULTS

We found that cortical gray matter density in the left inferior frontal and bilateral inferior parietal lobules of the mathematicians were significantly increased compared with the control subjects. Furthermore, increase in gray matter density in the right inferior parietal lobule of the mathematicians was strongly correlated with the time spent as an academician (r = 0.84; P < .01). Left-inferior frontal and bilateral parietal regions are involved in arithmetic processing. Inferior parietal regions are also involved in high-level mathematic thinking, which requires visuospatial imagery, such as mental creation and manipulation of 3D objects.

CONCLUSION

The voxel-based morphometric analysis of mathematicians' brains revealed increased gray matter density in the cortical regions related to mathematic thinking. The correlation between cortical density increase and the time spent as an academician suggests experience-dependent structural plasticity in mathematicians' brains.

Quantitative proton MR spectroscopy findings in the corpus callosum of patients with schizophrenia suggest callosal disconnection

BACKGROUND AND PURPOSE

The callosal disconnectivity theory was previously proposed to explain the pathophysiology of schizophrenia. The goal of this study was to investigate the metabolic integrity of the corpus callosum in patients with schizophrenia by proton MR spectroscopy.

MATERIALS AND METHODS

Twelve first-episode and 16 chronic patients meeting the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for schizophrenia and 28 age- and sex-matched control subjects were enrolled in the study. We measured the absolute concentrations of neurometabolites and T2 relaxation times of tissue water (T2B) in the genu of the corpus callosum by using the internal water-reference method. The severity of symptoms in patients was rated by means of psychopathology scales. Differences in neurometabolite concentrations and T2B values between the patients and control subjects were assessed. We also investigated the correlation of metabolite concentrations with the severity of symptoms.

RESULTS

N-acetylaspartate (NAA) concentrations were significantly lower in the first-episode as well as in chronic patients, compared with respective control subjects (P < .001). NAA concentrations in the first-episode and chronic patient groups were negatively correlated with both the Brief Psychiatry Rating Scale and the Scale for Assessment of Negative Symptoms scores (P < .001). There was a significant negative correlation between the NAA concentrations and the Scale for Assessment of Positive Symptoms scores in all patients (P = .028). T2B values were significantly higher in the patients, compared with the control subjects (P < .001).

CONCLUSION

Decreased NAA concentration in the corpus callosum correlates with psychopathology in schizophrenia. This finding, together with prolonged T2B values of the corpus callosum, supports the previously proposed callosal disconnection theory concerning the pathophysiology of schizophrenia.

Breakthrough Trichosporon asahii fungemia in neutropenic patient with acute leukemia while receiving caspofungin

A 47-year-old man with newly diagnosed acute myeloblastic leukemia and non-insulin-dependent diabetes mellitus developed Trichosporon asahii fungemia while receiving caspofungin as empirical antifungal therapy. The diagnosis was based on repeated isolation of T. asahii in culture of blood for three times. Despite treatment with amphotericin B and voriconazole, the patient died. The in vitro antifungal susceptibilities of the T. asahii isolates were only available after the patient died. In vitro antifungal susceptibility tests showed high caspofungin and amphotericin B minimal inhibitory concentrations (MICs) value for this Trichosporon strain (MICs, 16 microg/ml, and>32 microg/ml, respectively). Fluconazole, itraconazole, and voriconazole exhibited low MICs in vitro (MICs, 4 microg/ml, 0.5 microg/ml, and<or=0.015 microg/ml, respectively). Our experience strongly suggest that identification and antifungal susceptibility testing for T. asahii in neutropenic patients who may develop signs of infection in the presence of caspofungin as well as broadspectrum antibiotics treatment should not be overlooked.

A New Minimally Invasive Experimental Spinal Cord Injury Model in Rabbits

The aim of this experimental study was to evaluate the effectivity of epidural microballoon inflation into the unroofed spinal column for the creation of a new experimental spinal cord injury model in rabbits. 10 New Zealand white rabbits were used for this study. Before operation and after anasthesia with 50 mg/kg ketamine and 8 mg/kg xylazine, spinal evoked potentials (SEP) were recorded in all rabbits. A midline skin incision was done on the lomber skin at the level of L1-L4. Paravertebral muscles were dissected bilaterally. A microhemilaminotomy was done in the right L3 lamina close to the midline by using Midas-rex micro-diamond drill instruments. The ligamentum flavum was opened and removed with microscissors. A microballoon was inserted into the spinal column between the bone and dura mater to the level of T12. The microballoon was inflated by using a pressure- and volume-controlled microballoon inflation device. Pre-injury and post-injury SEPs were recorded. The microballoon was deflated 15 minutes later and removed completely from the epidural space. 24 hours later the SEP study was repeated. Following microballoon inflation the SEP waves dropped to the basal level. All rabbits were paraplegic after the operation. In conclusion, this experimental study demonstrated that the microballoon inflation technique is a very successful method for the evaluation of spinal cord injury in rabbits. Unroofing of the spinal column is extremely important because decompression may be an effective treatment in spinal cord injury. Also the traumatic effect of aneurysm clips represents a different type of injury to the spinal cord. This new model may be used in experimental studies of spinal cord injury in rabbits.

Soft micro-balloon paddy for brain retraction in the protection of neuronal tissue

Brain protection is extremely important during arachnoidal dissection and brain separation with a metallic retractor to create a surgical corridor. We have designed a new type of paddy containing air-filled micro-balloons and cotton for use between the metallic retractor and the brain surface for maximal protection of the neuronal tissues from the pressure of the retractor. In neurosurgical operations, cotton paddies are commonly and generally used during the retraction of brain tissue. We hypothesized that air-filled micro-balloon paddies covered with cotton could be helpful in the gentle separation of brain tissue with metallic retractors for minimizing cerebral damage, and for separating sulcal and cisternal walls during brain operations. These paddies are 2 cm in width and 4 cm in length. Multiple air-filled silicon micro-balloons are located in a sheet with 1-2 mm separation from each other. These silicon micro-balloonoid sheets are covered with a cotton sheath. The thickness of this type of paddy is 2-3 mm from the anterior surface to the posterior surface. We used paddies in 86 brain operations where brain retraction was necessary to create a surgical corridor. There was no complication or unwanted events related with the use of these paddies.

IN CONCLUSION

air-filled silicon micro-balloon paddies are useful materials for the gentle separation of brain tissue with a metallic retractor in order to minimize cerebral damage, and for the separation of sulcal and cisternal walls during the surgical intervention.