Changes in stroke volume variation and cardiac index during open major bowel surgery.

BACKGROUND: Stroke volume variation (SVV) is a dynamic indicator of preload, which is a determinant of cardiac output. Aims: Aim of this study was to evaluate the relationship between changes in SVV and cardiac index (CI) in patients with normal left ventricular function undergoing major open abdominal surgery. PATIENTS AND METHODS: Patients undergoing major open abdominal surgery were monitored continuously with FloTrac® to measure SVV and CI along with standard monitoring. Both SVV and CI were noted at baseline and every 10 min thereafter till the end of surgery and were observed for concurrence between the measurements. RESULTS: 1800 pairs of measurement of SVV and CI were obtained from 60 patients. Mean SVV and CI (of all patients) measured at different time points of measurement showed that as SVV increased with time, the CI dropped correspondingly. When individual readings of CI and SVV were plotted against each other, the scatter was found to be wide, reiterating the lack of agreement between the two parameters (R2 = 0.035). SVV >13% suggesting hypovolemia was found at 207 time points. Of these, 175 had a CI >2.5 L/min/m2 and only 32 patients had a CI <2.5 L/min/m2. CONCLUSION: SVV, a dynamic index of fluid responsiveness can be used to monitor patients expected to have large fluid shifts during major abdominal surgery. It is very specific and has a high negative predictive value. When SVV increases, CI is usually maintained. Since many factors affect SVV and CI, any increase in SVV >13%, must be correlated with other parameters before administration of the fluid challenge.

Cryopreserved human umbilical cord patch for in-utero spina bifida repair.

OBJECTIVE: To identify a patch system to repair surgically created spina bifida in a sheep model for its efficacy in healing the skin defect, protecting the underlying spinal cord and reducing the Chiari II malformation. METHODS: Spina bifida was created surgically in 16 fetuses from eight timed-pregnant sheep at gestational age of 75 days. Two fetuses did not survive the procedure. Repeat hysterotomy was performed at 95 days' gestation to cover the defect with either biocellulose film with underwater adhesive (BCF-adhesive) (n = 7) or human umbilical cord with suture (HUC-suture) (n = 7). Three fetuses without formation of the defect served as reference controls. The skin healing was examined by direct visualization after a planned Cesarean section at term, followed by histological analysis using hematoxylin and eosin and Masson's trichrome stains. Mid-sagittal sections of the fetal cranium and upper cervical spine were analyzed by a pediatric neuroradiologist who was blinded to the type of patch received. RESULTS: Three fetuses that received the BCF-adhesive and six fetuses that received the HUC-suture survived to term for final analysis. As a result of dislodgment of the BCF-adhesive, all spina bifida defects repaired using BCF-adhesive were not healed and showed exposed spinal cord with leakage of cerebrospinal fluid. In contrast, all spinal defects repaired by HUC-suture were healed with complete regrowth of epidermal, dermal and subdermal tissue components, with no exposed spinal cord. The maximal skin wound width was 21 ± 3.6 mm in the BCF-adhesive group but 3 ± 0.8 mm in the HUC-suture group (P < 0.001). The spinal cord area (P = 0.001) and the number of anterior horn cells (P = 0.03) was preserved to a greater degree in the HUC-suture group than in the BCF-adhesive group, whilst psammoma bodies, signifying neuronal degeneration, were only observed in the BCF-adhesive group. Anatomic changes, indicative of Chiari II malformation, were seen in all three fetuses of the BCF-adhesive group but in none of the HUC-suture group (P < 0.01). CONCLUSION: Cryopreserved umbilical cord graft is a promising regenerative patch for intrauterine repair of spina bifida.

Dandy-Walker Phenotype with Brainstem Involvement: 2 Distinct Subgroups with Different Prognosis.

BACKGROUND AND PURPOSE: Although cardinal imaging features for the diagnostic criteria of the Dandy-Walker phenotype have been recently defined, there is a large range of unreported malformations among these patients. The brainstem, in particular, deserves careful attention because malformations in this region have potentially important implications for clinical outcomes. In this article, we offer detailed information on the association of brainstem dysgenesis in a large, multicentric cohort of patients with the Dandy-Walker phenotype, defining different subtypes of involvement and their potential clinical impact. MATERIALS AND METHODS: In this established multicenter cohort of 329 patients with the Dandy-Walker phenotype, we include and retrospectively review the MR imaging studies and clinical records of 73 subjects with additional brainstem malformations. Detailed evaluation of the different patterns of brainstem involvement and their potential clinical implications, along with comparisons between posterior fossa measurements for the diagnosis of the Dandy-Walker phenotype, was performed among the different subgroups of patients with brainstem involvement. RESULTS: There were 2 major forms of brainstem involvement in patients with Dandy-Walker phenotype including the following: 1) the mild form with anteroposterior disproportions of the brainstem structures "only" (57/73; 78%), most frequently with pontine hypoplasia (44/57; 77%), and 2) the severe form with patients with tegmental dysplasia with folding, bumps, and/or clefts (16/73; 22%). Patients with severe forms of brainstem malformation had significantly increased rates of massive ventriculomegaly, additional malformations involving the corpus callosum and gray matter, and interhemispheric cysts. Clinically, patients with the severe form had significantly increased rates of bulbar dysfunction, seizures, and mortality. CONCLUSIONS: Additional brainstem malformations in patients with the Dandy-Walker phenotype can be divided into 2 major subgroups: mild and severe. The severe form, though less prevalent, has characteristic imaging features, including tegmental folding, bumps, and clefts, and is directly associated with a more severe clinical presentation and increased mortality.

Refining the Neuroimaging Definition of the Dandy-Walker Phenotype.

BACKGROUND AND PURPOSE: The traditionally described Dandy-Walker malformation comprises a range of cerebellar and posterior fossa abnormalities with variable clinical severity. We aimed to establish updated imaging criteria for Dandy-Walker malformation on the basis of cerebellar development. MATERIALS AND METHODS: In this multicenter study, retrospective MR imaging examinations from fetuses and children previously diagnosed with Dandy-Walker malformation or vermian hypoplasia were re-evaluated, using the choroid plexus/tela choroidea location and the fastigial recess shape to differentiate Dandy-Walker malformation from vermian hypoplasia. Multiple additional measures of the posterior fossa and cerebellum were also obtained and compared between Dandy-Walker malformation and other diagnoses. RESULTS: Four hundred forty-six examinations were analyzed (174 fetal and 272 postnatal). The most common diagnoses were Dandy-Walker malformation (78%), vermian hypoplasia (14%), vermian hypoplasia with Blake pouch cyst (9%), and Blake pouch cyst (4%). Most measures were significant differentiators of Dandy-Walker malformation from non-Dandy-Walker malformation both pre- and postnatally (P < .01); the tegmentovermian and fastigial recess angles were the most significant quantitative measures. Posterior fossa perimeter and vascular injury evidence were not significant differentiators pre- or postnatally (P > .3). The superior posterior fossa angle, torcular location, and vermian height differentiated groups postnatally (P < .01), but not prenatally (P > .07). CONCLUSIONS: As confirmed by objective measures, the modern Dandy-Walker malformation phenotype is best defined by inferior predominant vermian hypoplasia, an enlarged tegmentovermian angle, inferolateral displacement of the tela choroidea/choroid plexus, an obtuse fastigial recess, and an unpaired caudal lobule. Posterior fossa size and torcular location should be eliminated from the diagnostic criteria. This refined phenotype may help guide future study of the numerous etiologies and varied clinical outcomes.

Ergonomics of digital imaging.

There has been an increase in the use of digital imaging in recent years and radiologists have almost universally accepted the use of computers in their day-to-day work. Completely filmless radiology departments, with all reporting being done on visual display terminals and picture archiving and communications systems (PACS) around the department, are already a reality in many places in the UK and other parts of the world. There is a constant need of computers for literature searches on the web, e-mails, communication and preparing lectures and presentations. With this explosive increase in the use of computers in the hospital, it is imperative that the use of computer monitor screens for medical use is optimized in order to avoid eyestrain and fatigue. This is especially important as tired eyes and brains may be more likely to commit errors. We have reviewed the current literature to elaborate a few useful measures that can be taken to minimize the effect of excessive computer use in a soft-copy radiology reporting area on the eyes and the musculoskeletal system. We recommend that optimal placement of computer monitors with user-friendly PACS terminal interfaces will ensure greater acceptability and improve reporting efficiency and accuracy. Good work practices to ensure reduction of reporting errors are highlighted.

Pediatric first time non-febrile seizure with focal manifestations: is emergent imaging indicated?

PURPOSE: To assess the prevalence of clinically urgent intra-cranial pathology among children who had imaging for a first episode of non-febrile seizure with focal manifestations. METHODS: We performed a cross sectional study of all children age 1 month to 18 years evaluated for first episode of non-febrile seizure with focal manifestations and having neuroimaging performed within 24h of presentation at a single pediatric ED between 1995 and 2012. We excluded intubated patients, those with known structural brain abnormality and trauma. A single neuro-radiologist reviewed all cranial computed tomography and/or magnetic resonance imaging performed. We defined clinically urgent intracranial pathology as any finding resulting in a change of initial patient management. We performed univariate analysis using χ(2) analysis for categorical data and Mann-Whitney U test for continuous data. RESULTS: We identified 319 patients having a median age of 4.6 years [IQR 1.8-9.4] of which 45% were female. Two hundred sixty-two children had a CT scan, 15 had an MR and 42 had both. Clinically urgent intra-cranial pathology was identified on imaging of 13 patients (4.1%; 95% CI: 2.2, 7.0). Infarction, hemorrhage and thrombosis were most common (9/13). Twelve of 13 were evident on CT scan. Persistent Todd's paresis and age ≤ 18 months were predictors of clinically urgent intracranial pathology. Absence of secondary generalization and multiple seizures on presentation were not predictive. CONCLUSIONS: Four percent of children imaged with first time, afebrile focal seizures have findings important to initial management. Children younger than ≤ 18 months are at increased risk.

Metabolic imaging of mild traumatic brain injury.

Traumatic brain injury results in a metabolic cascade of changes that occur at the molecular level, invisible to conventional imaging methods such as computed tomography or magnetic resonance imaging. Non-invasive metabolic imaging tools such as single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance spectroscopy (MRS) are the ideal methods for providing insight to these changes by measuring regional cerebral blood flow, glucose metabolism, and brain metabolite concentrations, respectively, after mild traumatic brain injury (mTBI). The purpose of this review is to provide an overview of the different methodologies and provide an up-to-date summary of recent findings with SPECT, PET, and MRS technologies, specifically after mTBI, as defined by standardized criteria. Given that the different physiological and pathological responses are heterogeneous, efforts will be made to separate studies at different time points after injury (acute, subacute, and chronic stages) as well as to the different types of mTBI such sports-related head injury where repetitive head injuries are much more common and may present a unique signature.

Early thalamic lesions in patients with sleep-potentiated epileptiform activity.

OBJECTIVE: To compare the prevalence and type of early developmental lesions in patients with a clinical presentation consistent with electrical status epilepticus in sleep either with or without prominent sleep-potentiated epileptiform activity (PSPEA). METHODS: We performed a case-control study and enrolled patients with 1) clinical features consistent with electrical status epilepticus in sleep, 2) ≥1 brain MRI scan, and 3) ≥1 overnight EEG recording. We quantified epileptiform activity using spike percentage, the percentage of 1-second bins in the EEG tracing containing at least 1 spike. PSPEA was present when spike percentage during non-REM sleep was ≥50% than spike percentage during wakefulness. RESULTS: One hundred patients with PSPEA (cases) and 47 patients without PSPEA (controls) met the inclusion criteria during a 14-year period. Both groups were comparable in terms of clinical and epidemiologic features. Early developmental lesions were more frequent in cases (48% vs 19.2%, p = 0.002). Thalamic lesions were more frequent in cases (14% vs 2.1%, p = 0.037). The main types of early developmental lesions found in cases were vascular lesions (14%), periventricular leukomalacia (9%), and malformation of cortical development (5%). Vascular lesions were the only type of early developmental lesions that were more frequent in cases (14% vs 0%, p = 0.005). CONCLUSIONS: Patients with PSPEA have a higher frequency of early developmental lesions and thalamic lesions than a comparable population of patients without PSPEA. Vascular lesions were the type of early developmental lesions most related to PSPEA.

Application of alpha track registration technique for plutonium estimation in bioassay samples.

Bioassay monitoring is carried out for occupational workers handling plutonium (Pu) in nuclear facilities. In India, presently Pu estimation in bioassay samples is done by alpha spectrometry. The minimum detectable activity (MDA) of alpha spectrometry is 0.5mBq for a counting period of 1 day. To reduce the load of sample counting on alpha spectrometry, an alternative method based on alpha track registration in solid state nuclear track detectors (SSNTDs) is developed in the present paper. For this purpose, few urine samples of normal subjects spiked with known amounts of Pu in the range of 0.5-5.5mBq were exposed to CR-39 SSNTDs. The total number of alpha tracks seen in the CR-39 films of the sample and the standard were used to calculate the amount of Pu in the sample. The results of alpha track registration technique were also compared with that obtained by the well-established alpha spectrometry and were found to agree well within +/-30%. The minimum amount of Pu that can be analyzed by this method is 0.18mBq for an exposure period of 45 days.

Fibrochondrogenesis.

Fibrochondrogenesis is a rare lethal short-limb skeletal dysplasia. Till now only fifteen cases have been reported since Lazzaroni-Fossati first described it in 1978. Hence reported a case of fibrochondrogenesis in a child born to a consanguineously married couple with characteristic physical and radiological features and discuss the incidence, inheritence, ultrasonographic, clinical, radiological and pathological characteristics of this disorder.

Fibrochondrogenesis.

Fibrochondrogenesis is a rare lethal short-limb skeletal dysplasia. Till now only fifteen cases have been reported since Lazzaroni-Fossati first described it in 1978. Hence reported a case of fibrochondrogenesis in a child born to a consanguineously married couple with characteristic physical and radiological features and discuss the incidence, inheritance, ultrasonographic, clinical, radiological and pathological characteristics of this disorder.