Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy

Objective The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion.Materials and methodsThis prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements.ResultsNo significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm.ConclusionsA better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met. (AU)

Dosimetric impact of rectum and bladder anatomy and intrafractional prostate motion on hypofractionated prostate radiation therapy.

OBJECTIVE: The objective of this study was to evaluate the dosimetric impact on hypofractionated prostate radiation therapy of two geometric uncertainty sources: rectum and bladder filling and intrafractional prostate motion. MATERIALS AND METHODS: This prospective study included 544 images (375 pre-treatment cone-beam CT [CBCT] and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients. We recalculated the dose on each pre-treatment CBCT once the positioning errors were corrected. We also recalculated two dose distributions on each post-treatment CBCT, either using or not intrafractional motion correction. A correlation analysis was performed between CBCT-based dose and rectum and bladder filling as well as intrafraction prostate displacements. RESULTS: No significant differences were found between administered and planned rectal doses. However, we observed an increase in bladder dose due to a lower bladder filling in 66% of treatment fractions. These differences were reduced at the end of the fraction since the lower bladder volume was compensated by the filling during the treatment session. A statistically significant reduction in target volume coverage was observed in 27% of treatment sessions and was correlated with intrafractional prostate motion in sagittal plane > 4 mm. CONCLUSIONS: A better control of bladder filling is recommended to minimize the number of fractions in which the bladder volume is lower than planned. Fiducial mark tracking with a displacement threshold of 5 mm in any direction is recommended to ensure that the prescribed dose criteria are met.

Iatrogenic mediastinitis in bronchiolitis: Importance of avoiding pharyngeal aspiration.

An 11-month-old infant was hospitalized for his first episode of severe bronchiolitis, with pneumomediastinum on the chest x-ray performed in the emergency room before hospitalization. After a few days, the occurrence of a feverish torticollis motivated a CT scan, revealing mediastinitis. An iatrogenic perforation was objectified in the posterior wall of the esophagus, probably caused by nasopharyngeal aspiration. This exceptional case has never been reported before, except in premature infants. This encouraged us to report this case to change systematic aspiration practices and prefer nasal suctioning in healthy infants with bronchiolitis presenting to the emergency department.

Impact of rectum and bladder anatomy in intrafractional prostate motion during hypofractionated radiation therapy.

BACKGROUND: The objective was to determine the magnitude of the prostate intrafractional motion relative to bony pelvis anatomy, and to evaluate the relationship between this displacement and some clinical and anatomical variables. MATERIALS AND METHODS: The prospective study consisted of 544 images (375 pre-treatment CBCT and 169 post-treatment CBCT) from 15 prostate adenocarcinoma patients that were used for intrafractional prostate motion determination. In addition, two radiation oncologists re-contoured the bladder and rectum on each CBCT according to the patient's anatomy of the day. ANOVA and correlation analysis followed by linear regression analysis were performed to identify clinical or anatomical variables that predict large prostate intrafractional motion. RESULTS: Prostate shift increased in patients with hormone therapy (p ≤ 0.02). The regression analysis showed that patients with large bladder intrafractional filling (p < 0.01) and a large bladder volume difference from planning CT were more likely to experience bigger longitudinal prostate motion (> 3 mm). Recommended bladder size values: anterior-posterior size ≤ 10 cm and anterior-posterior/cranio-caudal ratio ≤ 1.7, both parameters measured in the midsagittal prostate plane, were defined. CONCLUSIONS: The treatment margin should not be reduced for those patients who were treated with hormone therapy and/or whose rectum or bladder was far from complying the preparation protocol conditions.

Caracterización y simulación de ruido en las imágenes de PET reconstruidas con OSEM: desarrollo de un método para la generación de imágenes sintéticas / Characterization and simulation of noise in PET images reconstructed with OSEM: Development of a method for the generation of synthetic images

Introducción: Los objetivos del trabajo son caracterizar las propiedades de la imagen 2D PET reconstruida mediante el algoritmo ordered-subset expectation maximization (OSEM) y proponer un nuevo método de generación de imágenes sintéticas. Material y métodos: El ruido se analiza en términos de magnitud, correlación espacial y distribución espectral a través de la desviación estándar, la función de autocorrelación y el espectro de potencias de ruido (NPS, por noise power spectrum), respectivamente. También se estudian sus variaciones con la posición y la cantidad de actividad. Este análisis del ruido se realiza sobre imágenes de maniquí a partir de distribuciones de actividad de 18F homogéneas. Para estudiar la resolución espacial del sistema a través de la point spread function (PSF) se emplean los coeficientes de recuperación medidos en esferas calientes en diferentes entornos radiactivos. Las funciones PSF y NPS proporcionan la base del método de simulación propuesto: convolución con la PSF como núcleo y adición de ruido a partir del NPS. Resultados: El análisis del ruido espectral muestra que la principal contribución es de naturaleza aleatoria. También se observa que la corrección de atenuación no altera la textura del ruido pero sí modifica su magnitud. Finalmente, las imágenes sintéticas de 2 maniquíes, uno de ellos un cerebro anatómico, son comparadas cuantitativamente con las imágenes experimentales, encontrando un buen acuerdo en términos de valores de píxel y correlaciones entre píxeles. Así, la razón contraste-ruido para la esfera más grande del maniquí NEMA IEC es 10,7 en la imagen sintética y 8,8 en la imagen experimental. Conclusiones: Las propiedades de las imágenes PET-OSEM pueden ser descritas por las funciones NPS y PSF. Las imágenes simuladas, incluyendo regiones anatómicas, son generadas satisfactoriamente mediante el método propuesto basado en las funciones NPS y PSF

Introduction: The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. Material and methods: The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. Results: The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. Conclusions: The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF

Characterization and simulation of noise in PET images reconstructed with OSEM: Development of a method for the generation of synthetic images. / Caracterización y simulación de ruido en las imágenes de PET reconstruidas con OSEM: desarrollo de un método para la generación de imágenes sintéticas.

INTRODUCTION: The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. MATERIAL AND METHODS: The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. RESULTS: The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. CONCLUSIONS: The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF.

Reduced late urinary toxicity with high-dose intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer

Background/purpose. To evaluate the impact of intensity-modulated radiotherapy (IMRT) with intra-prostate fiducial markers image-guided radiotherapy (IGRT) on the incidence of late urinary toxicity compared to 3D conformal radiotherapy (3DCRT) for patients with prostate cancer (PC). Methods and materials. We selected 733 consecutive patients with localized PC treated with dose-escalation radiotherapy between 2001 and 2014. Eligibility criteria were radiation dose >72.0 Gy, no pelvic RT and minimum follow-up 24 months. 438 patients were treated with 3DCRT and 295 with IMRT. Acute and late urinary complications were assessed using the EORTC/RTOG and CTCAEs v3.0 definition. The Cox regression model was used to compare grade ≥2 urinary toxicity between both techniques. The median follow-up was 75 months (range 24-204). Results. The median isocenter radiation dose was 78.7 Gy for 3DCRT and 80.7 Gy for IMRT/IGRT (p < 0.001). The 5-year incidence of late grade ≥2 urinary toxicity was 6.4% for IMRT and 10.8% for 3DCRT [hazard ratio (HR) 0.575, p = 0.056]. The corresponding 5-year estimates of late grade ≥2 hematuria were 2% for IMRT and 5.3% for 3DCRT (HR 0.296, p = 0.024). On multivariate analysis, the antecedent of prior transurethral resection of the prostate was also a strong predictor of a higher risk of urinary complications (HR 2.464, p = 0.002) and of hematuria (HR 5.196, p < 0.001). Conclusion. Compared with 3DCRT, high-dose IMRT/IGRT is associated with a lower rate of late urinary complications in spite of higher radiation dose (AU)

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Reduced late urinary toxicity with high-dose intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer.

BACKGROUND/PURPOSE: To evaluate the impact of intensity-modulated radiotherapy (IMRT) with intra-prostate fiducial markers image-guided radiotherapy (IGRT) on the incidence of late urinary toxicity compared to 3D conformal radiotherapy (3DCRT) for patients with prostate cancer (PC). METHODS AND MATERIALS: We selected 733 consecutive patients with localized PC treated with dose-escalation radiotherapy between 2001 and 2014. Eligibility criteria were radiation dose >72.0 Gy, no pelvic RT and minimum follow-up 24 months. 438 patients were treated with 3DCRT and 295 with IMRT. Acute and late urinary complications were assessed using the EORTC/RTOG and CTCAEs v3.0 definition. The Cox regression model was used to compare grade ≥2 urinary toxicity between both techniques. The median follow-up was 75 months (range 24-204). RESULTS: The median isocenter radiation dose was 78.7 Gy for 3DCRT and 80.7 Gy for IMRT/IGRT (p < 0.001). The 5-year incidence of late grade ≥2 urinary toxicity was 6.4% for IMRT and 10.8% for 3DCRT [hazard ratio (HR) 0.575, p = 0.056]. The corresponding 5-year estimates of late grade ≥2 hematuria were 2% for IMRT and 5.3% for 3DCRT (HR 0.296, p = 0.024). On multivariate analysis, the antecedent of prior transurethral resection of the prostate was also a strong predictor of a higher risk of urinary complications (HR 2.464, p = 0.002) and of hematuria (HR 5.196, p < 0.001). CONCLUSION: Compared with 3DCRT, high-dose IMRT/IGRT is associated with a lower rate of late urinary complications in spite of higher radiation dose.

[Purple drank: A dangerous cocktail]. / Purple drank : un dangereux cocktail à connaître.

"Purple drank" is a dangerous hallucinogenic cocktail commonly used by teenagers, made popular by American rappers and social networks. It combines codeine-based cough syrup, antihistamines such as promethazine, and soda. Unknown by caregivers, it may be responsible for serious neuropsychological complications. We report the effects of this new risky behavior in three patients: a 14-year-old girl and her boyfriend, both found in an initial state of drowsiness, followed by hallucinations and anticholinergic toxidrome; and another teenager whose chronic use led to addiction with increasing doses. It is important to identify signs of such intoxication and to inform patients about the risks of respiratory depression, drowsiness, and delirium linked to acute medication misuse.

Low serum 25-hydroxyvitamin D is associated with increased risk of stress fracture during Royal Marine recruit training.

UNLABELLED: The aim of this study was to investigate vitamin D status and stress fracture risk during Royal Marine military training. Poor vitamin D status was associated with an increased risk of stress fracture. Vitamin D supplementation may help to reduce stress fracture risk in male military recruits with low vitamin D status. INTRODUCTION: Stress fracture is a common overuse injury in military recruits, including Royal Marine (RM) training in the UK. RM training is recognised as one of the most arduous basic training programmes in the world. Associations have been reported between serum 25-hydroxyvitamin D (25(OH)D) and risk of stress fracture, but the threshold of 25(OH)D for this effect remains unclear. We aimed to determine if serum 25(OH)D concentrations were associated with stress fracture risk during RM training. METHODS: We prospectively followed 1082 RM recruits (males aged 16-32 years) through the 32-week RM training programme. Troops started training between September and July. Height, body weight and aerobic fitness were assessed at week 1. Venous blood samples were drawn at weeks 1, 15 and 32. Serum samples were analysed for 25(OH)D and parathyroid hormone (PTH). RESULTS: Seventy-eight recruits (7.2 %) suffered a total of 92 stress fractures. Recruits with a baseline serum 25(OH)D concentration below 50 nmol L(-1) had a higher incidence of stress fracture than recruits with 25(OH)D concentration above this threshold (χ(2) (1) = 3.564, p = 0.042; odds ratio 1.6 (95 % confidence interval (CI) 1.0-2.6)). Baseline serum 25(OH)D varied from 47.0 ± 23.7 nmol L(-1) in February, to 97.3 ± 24.6 nmol L(-1) in July (overall mean 69.2 ± 29.2 nmol L(-1), n = 1016). There were weak inverse correlations between serum 25(OH)D and PTH concentrations at week 15 (r = -0.209, p < 0.001) and week 32 (r = -0.214, p < 0.001), but not at baseline. CONCLUSION: Baseline serum 25(OH)D concentration below 50 nmol L(-1) was associated with an increased risk of stress fracture. Further studies into the effects of vitamin D supplementation on stress fracture risk are certainly warranted.

Brain acetylcholine and choline concentrations and dynamics in a murine model of the Fragile X syndrome: age, sex and region-specific changes.

Fragile X syndrome is a learning disability caused by excess of CGG repeats in the 5' untranslated region of the Fragile X gene (FMR1) silencing its transcription and translation. We used a murine model of this condition, Fmr1 knock-out mice (KO) to study acetylcholine (ACh) metabolism and compared it to that of wild-type control mice (WT). Brain endogenous ACh (D0ACh), free choline (D0Ch), their deuterated variants D4ACh and D4Ch and mole ratios (AChMR and ChMR) were measured by gas chromatography-mass spectrometry in the cerebral hemisphere, cerebral cortex, hippocampus and cerebellum, following D4Ch administration. Regression analysis indicated a significant decrease with age (negative slope) of D4ACh, AChMR, D4Ch and ChMR in WT mice. Age dependence was only present for D4ACh and AChMR in KO mice. Analysis of variance with age as covariate indicated a significant greater D4Ch in the cerebral cortex of KO females when compared to WT females. Contrasts between sexes within genotypes indicated lower D0Ch in cortex and cerebellum of female KO mice but not in WT and lower D4Ch in hippocampus of female KO and WT mice. In conclusion, after adjusting for age, D0ACh concentrations and synthesis from deuterium-labeled Ch were similar in KO and control WT mice in all brain regions. In contrast, significant changes in Ch dynamics were found in hippocampus and cerebral cortex of KO mice that might contribute to the pathogenesis of FXS.

Value of the preservation of an osseous mandibular rim with a fibula free flap reconstruction.

BACKGROUND: Reconstruction of the mandible with microvascularized fibula transplants is actually a well-established procedure, yet the major component is the limited diameter of the diaphysis that can induce oral rehabilitation's failure, especially in dentate patients. In this paper, we report our surgical procedure allowing preservation of the mandibular height. The primary objective was to assess aesthetic and functional improvements of preservation of an osseous mandibular rim with a fibula free flap reconstruction. PATIENTS AND METHODS: Five patients (all males, mean age of 60 years) were treated with this method. Aetiologies were tumour in 3 cases, and osteoradionecrosis in the two others cases. We described all step of our surgical procedure and the functional, aesthetic and carcinologic results were evaluated. The follow up varies from 6 to 30 months. RESULTS: One patient died at 12 days from unrelated affection. For the other patients, both the aesthetics and functional outcomes were better than in case of mandibular interruption surgery. In fact, the mandibular contour of the mandibule was preserved and the height of mandible was restored. One patient is in progress of dental rehabilitation with osseous implants. Carcinologically, no local recurrence was observed. CONCLUSION: This technique is reliable and enables to optimize oral rehabilitation with endosteal implants. Nevertheless, we consider that the 3D scanner is essential before the intervention to evaluate the osseous reach. Moreover, if necessarily the procedure can be modified intraoperatively.

Description and validation of a magnetic resonance imaging-guided stereotactic brain biopsy device in the dog.

A stereotactic brain biopsy system that is magnetic resonance (MR) imaging-guided has not been validated in dogs. Our purpose was to determine the mean needle placement error in the caudate nucleus, thalamus, and midbrain of a canine cadaver brain using the modified Brainsight stereotactic system. Relocatable reference markers (fiducial markers) were attached to the cadaver head using a dental bite block. A T1-weighted gradient echo three-dimensional (3D) sequence was acquired using set parameters. Fiducial markers were used to register the head to the acquired MR images in reference to a 3D position sensor. This allowed the planning of trajectory path to brain targets in real time. Coordinates (X, Y, Z) were established for each target and 0.5 microl of diluted gadolinium was injected at each target using a 26-gauge needle to create a lesion. The center of the gadolinium deposition was identified on the postoperative MR images and coordinates (X', Y', Z') were established. The precision of this system in bringing the needle to target (needle placement error) was calculated. Seventeen sites were targeted in the brain. The mean needle placement error for all target sites was 1.79 +/- 0.87 mm. The upper bound of error for this stereotactic system was 3.31 mm. There was no statistically significant relationship between needle placement error and target depth (P = 0.23). The ease of use and precision of this stereotactic system support its development for clinical use in dogs with brain lesions > 3.31 mm.

[A 23-year-old patient with sore throat and cervical lymph node enlargement: a rare presentation of tularemia]. / 23-jähriger Patient mit Halsschmerzen und progredienter Lymphknotenschwellung: Eine seltene Form der Hasenpest.

We report a case of oropharyngeal tularemia--an uncommon manifestation of this disease. There is a low prevalence of tularemia in Germany. Therefore the diagnosis can be confirmed only by well directed laboratory diagnostics. Without correct antibiotic therapy mortality can reach 33%--depending on the subspecies of Francisella tularensis. For this reason tularemia should be included into the differential-diagnostic considerations in patients with unclear lymph node enlargement.

Ongoing activity in trigeminal wide-dynamic range neurons is driven from the periphery.

Ongoing activity of spinal trigeminal neurons is observed under various conditions and suggested to be responsible for ongoing headache. It can be spontaneous, i.e. arising intrinsically from the neuron, or the product of descending influences from other central neurons, or maintained by ongoing afferent input. The aim of the present study was to examine if ongoing activity of neurons in different subnuclei of the spinal trigeminal nucleus is driven from peripheral afferent input. Experiments were performed in Wistar rats anesthetized with isoflurane or Nembutal/urethane. Ongoing activity of single wide-dynamic range (WDR) neurons was recorded with carbon fiber glass microelectrodes in two subnuclei of the spinal trigeminal nucleus: oral (Sp5O) and caudal (Sp5C). Peripheral receptive fields were evaluated using von Frey filaments. Sp5O neurons received peripheral input from facial areas innervated by the mandibular branch of the trigeminal nerve. Units in Sp5C had receptive fields in the surgically exposed dura mater and in facial areas innervated by the ophthalmic and maxillary branch of the trigeminal nerve. Saline or the local anesthetic lidocaine was locally applied onto the exposed dura mater or microinjected into V3 (for Sp5O units) or V1/V2 (for Sp5C units) divisions of the trigeminal ganglion via the infraorbital channel. Local application of lidocaine onto the exposed dura caused mechanical insensitivity of dural receptive fields but not significant decrease in ongoing activity. Microinjection of lidocaine but not saline into the trigeminal ganglion was followed by a substantial decrease in both the receptive field size and the activity of the recorded WDR units. Mechanical insensitivity of receptive fields after trigeminal ganglion blockade was accompanied by the disappearance of ongoing activity. We conclude that the ongoing activity of WDR neurons in the spinal trigeminal nucleus, which may be indicative for processes of sensitization, is driven remotely by ongoing afferent input.

Synthesis of highly functionalized bicyclo[m.n.1]alkanones via a cationic reaction cascade.

[reaction: see text] The acid-mediated Prins/pinacol and the triple domino reactions Diels-Alder/Prins/pinacol were used to construct highly functionalized bicyclo[m.n.1]alkanones 19-29 and 33a-c possessing various ring sizes from ketals 8-18 and 31a-c in 44-96% yields. This approach proves to be highly efficient and reliable to generate high molecular complexity in a single step.

Rapid assembly of the bicyclo[5.3.1]undecenone core of penostatin F: a successive Diels-Alder/Claisen reaction strategy with an efficient stereochemical relay.

The first synthesis of the tricyclic core of Penostatin F (1) using a stereocontrolled Diels-Alder reaction and a Claisen rearrangement in succession has been achieved in nine steps from commercially available methyl acetoacetate and (E)-2-decenal. Penostatin F is a metabolite isolated from a fungal strain of Penicillium sp., OUPS-79, separated from the marine alga Enteromorphia intestinalis and exhibits significant cytotoxicity against cultured P388 Leukemia cells (ED(50) = 1.4 micromol/mL). [reaction: see text]

Automatic non-linear MRI-ultrasound registration for the correction of intra-operative brain deformations.

OBJECTIVE: Movements of brain tissue during neurosurgical procedures reduce the effectiveness of using pre-operative images for intra-operative surgical guidance. In this paper, we explore the use of acquiring intra-operative ultrasound (US) images for the quantification of and correction for non-linear brain deformations. MATERIALS AND METHODS: We will present a multi-modal registration strategy that automatically matches pre-operative images (e.g., MRI) to intra-operative US to correct for these deformations. The strategy involves using the predicted appearance of neuroanatomical structures in US images to build "pseudo ultrasound" images based on pre-operative segmented MRI. These images can then be non-linearly registered to intra-operative US using cross-correlation measurements within the ANIMAL package. The feasibility of the theory is demonstrated through its application to clinical patient data acquired during 12 neurosurgical procedures. RESULTS: Results of applying the method to 12 surgical cases, including those with brain tumors and selective amygdalo-hippocampectomies, indicate that our strategy significantly recovers from non-linear brain deformations occurring during surgery. Quantitative results at tumor boundaries indicate up to 87% correction for brain shift. CONCLUSIONS: Qualitative and quantitative examination of the results indicate that the system is able to correct for non-linear brain deformations in clinical patient data.

Measurement of serum 'free' or 'easily dissociable' insulin-like growth factor-1.

BACKGROUND: Serum insulin-like growth factor-1 (IGF-1) exists as ternary and binary complexes, and as the free hormone. An immunometric assay for 'free IGF-1' or 'easily dissociable IGF-1' has been described, although its use has not been widely assessed. METHODS: The assay was assessed using the serum concentration/dilution test and by determining the relationship of the measured free hormone to the total hormone/binding protein ratio. RESULTS: In six serum pools the measured free IGF-1 did not remain constant on concentration/dilution of the sample. However there was a significant correlation between the measured free IGF-1 and total IGF-1 (P < 0.001) and between total IGF-1/IGF binding protein-3 ratio (P < 0.001). DISCUSSION: Although the assay failed the serum concentration/dilution test, there was still a significant relationship to the total hormone/binding protein ratio. It is possible that the serum dilution test is inappropriate to such a complex system or that the assay does not measure the free fraction. It is suggested that, though more cumbersome, it should be referred to as 'easily dissociable' IGF-1 as suggested by the manufacturers.

Visualization of subdural strip and grid electrodes using curvilinear reformatting of 3D MR imaging data sets.

Curvilinear reformatting of 3D MR imaging data sets was used to visualize the position of subdural strip and grid electrodes relative to the underlying cerebral cortex in patients with epilepsy who were undergoing invasive electroencephalographic recordings. The contour of the cortical surface was delineated interactively, and topographical relationships among surface gyration, cortical lesions, and subdural electrodes were investigated by using serial convex planes parallel to the cortical surface. Electrode contacts could be marked and their positions projected to underlying areas at different depths. This method is apt for routine purposes and allows electrode positions to be displayed with respect to cortical and subcortical regions of interest.