Braın abscess due to Streptococcus intermedius secondary to mastoiditis in a child

Background: Brain abscess is a rare but serious, life-threatening infection in children. It may arise from parameningeal infections such as otitis media, sinusitis and mastoiditis.Case descriptionA ten-year-old boy with the diagnosis of glycogen-storage disease and obesity was admitted to the emergency room with complaints of vomiting, decreased level of consciousness, imbalance on walking. On neurological examination, the patient was ataxic. His cranial magnetic resonance imaging (MRI) examination showed mastoiditis on the right side and 39 × 34 mm abscess formation with surrounding edema on the right cerebellar hemisphere. The patient underwent surgery to drain the abscess, microbiological samples were obtained and empirical antibiotic treatment with vancomycin and piperacillin–tazobactam were started. Postoperative cranial MRI examination showed that the lesion regressed 10 × 10 mm with a reduction in the edema. On the second week of the treatment, the antibiotics were switched to vancomycin and meropenem because of the relapsing fever. The therapy was continued for 6 weeks. A final MRI (after completing antibiotherapy) showed resolution of the cerebellar abscess. The child's clinical condition improved and he was discharged without any sequelae.Discussion and evaluationChildren with congenital heart disease and an immonocompromised state are particularly at risk. Streptococcus intermedius is usually a commensal microorganism in the normal flora of the mouth which can cause brain abscess rarely in children. Brain abscess induced mortality rates are still relatively high, even with the advancement of imaging technologies, the combination of surgical drainage and antimicrobial therapy. Conclusion: This case is one of the few reported cases of cerebellar abscess caused by S. intermedius in an immunocompetent child, due to its low virulence, a rare occurence and timely management resulting in fully healed.

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Terlipressin and albumin for type 1 hepatorenal syndrome: does bacterial infection affect the response?

Vasoconstrictor therapy with terlipressin and concomitant albumin can improve renal function in patients with hepatorenal syndrome (HRS) type 1, but the efficacy of therapy in patients with active infection is controversial. The aim of this study was to investigate the efficacy, adverse effects, and predictors of terlipressin therapy and to find out whether there was a difference in response rates between the patients with or without active infections. Data of 58 patients with type 1 HRS treated with terlipressin and albumin were retrospectively evaluated. Twenty-six patients (44.8 %) showed complete response to treatment. Response rates of patients with or without active bacterial infection were 47 and 43.9 %, respectively (p > 0.05). Only baseline serum creatinine level was significantly related to response in univariate/multivariate analyses (p < 0.05). Twenty-three patients (39.6 %) developed adverse effects probably related to treatment. In 8.6 % of patients, treatment was discontinued because of adverse effects of therapy. Four patients (6.9 %) developed ischemic adverse events, including nonfatal myocardial infarction, intestinal ischemia, and cutaneous necrosis. Terlipressin plus albumin therapy improved renal function in nearly half of patients with type 1 HRS. Thus, it seems a reasonable treatment for patients with active bacterial infections. Baseline serum creatinine level is a potential predictor of terlipressin response.

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CT-guided biopsy of lung lesions using two needles in difficult and poorly cooperative patients

The purpose of our study was to evaluate the feasibility and safety of CT-guided percutaneous lung biopsy using two needles in difficult and poorly cooperative patients; and to examine the usefulness of the malpositioned first needle in tissue sampling with a second needle. This study included 17 consecutive patients with unsuccessful first insertion of the biopsy needle in the normal lung parenchyma and re-attempted tissue sampling through another puncture site using a second needle with the first needle retained in position until completion of the biopsy. We examined the difficult factors in biopsy that led to a failed first attempt, success rate of tissue sampling, procedure-related complications, and usefulness of the malpositioned needle. There were 1 or multiple difficult factors in all patients. In all 17 patients, core samples were successfully obtained using a second needle. Post-procedure pneumothorax and parenchymal hemorrhage occurred in 4 and 3 patients, respectively. The first needle was used as a navigational reference point for lesion localization in all patients and as an anchor restricting the mobility of the lung in patients with pneumothorax or poor breath holding capacity. CT-guided needle biopsy of the lung using a second needle without removing the first malpositioned needle is feasible and safe. During biopsy procedures in difficult or poorly cooperative patients, the malpositioned needle provides a navigational reference point or serves as an anchor to hold the movable lung.

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Evaluation of a systematic approach to weaning of tracheotomized neurological patients: an early interrupted randomized controlled trial

Background: While a systematic approach to weaning reduces the rate of extubation failure in intubated brain-injured patients, no data are available on the weaning outcome of these patients after tracheotomy. We aimed to assess whether a systematic approach to disconnect tracheotomized neurological and neurosurgical patients off the ventilator (intervention) is superior to the sole physician's judgment (control). Based on previous work in intubated patients, we hypothesized a reduction of the rate of failure within 48 h from 15 to 5 %. Secondary endpoints were duration of mechanical ventilation, ICU length of stay and mortality. Methods: We designed a single center randomized controlled study. Since no data are available on tracheotomized patients, we based our a priori power analysis on results derived from intubated patients and calculated an overall sample size of 280 patients. Results: After inclusion of 168 consecutive patients, the trial was interrupted because the attending physicians judged the observed rate of reconnection to be much greater than expected. The overall rate of failure was 29 %, confirming the physicians' judgment. Twenty-one patients (24 %) in the intervention group and 27 (33 %) controls were reconnected to the ventilator within 48 h (p = 0.222). The main reasons for failure were respiratory distress (80 and 88 % in the treatment and control group, respectively), hemodynamic impairment (15 and 4 % in the treatment and control group, respectively), neurological deterioration (4 % in the control group only). The duration of mechanical ventilation was of 412 ± 202 h and 402 ± 189 h, in the control and intervention group, respectively. ICU length of stay was on average of 23 days for both groups. ICU mortality was 6 % in the control and 2 % in the intervention group without significant differences. Conclusion: We found no difference between the two groups under evaluation, with a rate of failure much higher than expected. Consequent to the early interruption, our study results to be underpowered. Based on the results of the present study, a further trial should overall enroll 790 patients.Trial registration: ACTRN12612000372886

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The impact of system matrix dimension on small FOV SPECT reconstruction with truncated projections

Purpose:

A dedicated cardiac hybrid single photon emission computed tomography (SPECT)/CT scanner that uses cadmium zinc telluride detectors and multiple pinhole collimators for stationary acquisition offers many advantages. However, the impact of the reconstruction system matrix (SM) dimension on the reconstructed image quality from truncated projections and 19 angular samples acquired on this scanner has not been extensively investigated. In this study, the authors aimed to investigate the impact of the dimensions of SM and the use of body contour derived from adjunctive CTimaging as an object support in reconstruction on this scanner, in relation to background extracardiac activity.

Methods:

The authors first simulated a generic SPECT/CT system to image four NCAT phantoms with various levels of extracardiac activity and compared the reconstructions using SM in different dimensions and with/without body contour as a support for quantitative evaluations. The authors then compared the reconstructions of 18 patient studies, which were acquired on a GE Discovery NM570c scanner following injection of different radiotracers, including ^99mTc-Tetrofosmin and ¹²³I-mIBG, comparing the scanner's default SM that incompletely covers the body with a large SM that incorporates a patient specific full body contour.

Results:

The simulation studies showed that the reconstructions using a SM that only partially covers the body yielded artifacts on the edge of the field of view (FOV), overestimation of activity and increased nonuniformity in the blood pool for the phantoms with higher relative levels of extracardiac activity. However, the impact on the quantitative accuracy in the high activity region, such as the myocardium, was subtle. On the other hand, an excessively large SM that enclosed the entire body alleviated the artifacts and reduced overestimation in the blood pool, but yielded slight underestimation in myocardium and defect regions. The reconstruction using the larger SM with body contour yielded the most quantitatively accurate results in all the regions of interest for a range of uptake levels in the extracardiac regions. In patient studies, the SM incorporating patient specific body contour minimized extracardiac artifacts, yielded similar myocardial activity, lower blood pool activity, and subsequently improved myocardium-to-blood pool contrast (p reconstructions using the scanner's default SM.

Conclusions:

Their results demonstrate that using a large SM that incorporates a CT derived body contour in the reconstruction could improve quantitative accuracy within the FOV for clinical studies with high extracardiac activity.

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Effect of deformable registration uncertainty on lung SBRT dose accumulation

Purpose:

Deformable image registration (DIR) plays an important role in dose accumulation, such as incorporating breathing motion into the accumulation of the delivered dose based on daily 4DCBCT images. However, it is not yet well understood how the uncertainties associated with DIR methods affect the dose calculations and resulting clinical metrics. The purpose of this study is to evaluate the impact of DIR uncertainty on the clinical metrics derived from its use in dose accumulation.

Methods:

A biomechanical model based DIR method and a biomechanical-intensity-based hybrid method, which reduced the average registration error by 1.6 mm, were applied to ten lungcancer patients. A clinically relevant dose parameter [minimum dose to 0.5 cm³ (Dmin)] was calculated for three dose scenarios using both algorithms. Dose scenarios included static (no breathing motion), predicted (breathing motion at the time of planning), and total accumulated (interfraction breathing motion). The relationship between the dose parameter and a combination of DIR uncertainty metrics, tumor volume, and dose heterogeneity of the plan was investigated.

Results:

Depending on the dose heterogeneity, tumor volume, and DIR uncertainty, in over 50% of the patients, differences greater than 1.0 Gy were observed in the Dmin of the tumor in the static dose calculation on exhale phase of the 4DCT. Such differences were due to the errors in propagating the tumor contours from the reference planning 4DCT phase onto a subsequent 4DCT phase using each DIR algorithm and calculating the dose on that phase. The differences in predicted dose were more subtle when breathing motion was modeled explicitly at the time of planning with only one patient exhibiting a greater than 1.0 Gy difference in Dmin. Dmin differences of up to 2.5 Gy were found in the total accumulated delivered dose due to difference in quantifying the interfraction variations. Such dose uncertainties could potentially be clinically significant.

Conclusions:

Reductions in average uncertainty in DIR algorithms by 1.6 mm may have a clinically significant impact on the decision-making metrics used in dose planning and dose accumulation assessment.

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Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

Purpose:

To demonstrate that the authors' new "aqueous solution vs pure water" equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures.

Methods:

The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of "free" water molecules per unit volume of solution, "Nf," and (c) the "t" factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate Nf was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors' equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures.

Results:

The provisional equations formulated to calculate Nf, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of Nf using recorded relative density data at 20 °C. They were subsequently used to estimate Nf values at temperatures up to and excess of body temperatures. Those values, together with t values at temperatures up to and in excess of body temperatures recorded in the literature, were substituted in the authors' equation for the provisional calculation of osmotic potentials. The calculations indicated that solutiontemperatures and solute concentrations have a marked effect on osmotic potentials.

Conclusions:

Following work to measure the relative densities of aqueous solutions for the calculation of Nf values and the determination of definitive t values up to and beyond bodily temperatures, the authors' equation would enable the accurate estimations of the osmotic potentials of wide concentrations of aqueous solutions of inorganic and organic solutes over the temperature range. The study illustrates that not only solute concentrations but also temperatures have a marked effect on osmotic potentials, an observation of medical and biological significance.

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