Cardiac dual-source CT for the preoperative assessment of patients undergoing bariatric surgery.

AIM: To assess the diagnostic value of coronary dual-source computed tomography (DSCT) as a comprehensive, non-invasive tool in the preoperative cardiac evaluation of patients undergoing bariatric surgery. MATERIALS AND METHODS: Thirty consecutive obese [average body mass index (BMI): 45 ± 7.6, range: 35-59] patients (24 women; six men; median age: 52 ± 15 years) were enrolled in this institutional review board (IRB)-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant prospective study. Calcium scoring (CaS) and electrocardiography (ECG)-gated images of the coronary arteries were obtained with a large body habitus protocol (120 kV; 430 mAs; 100 ml iodinated contrast medium at 7 ml/s injection rate) on a DSCT machine. Qualitative (four-point: 1 = excellent to 4 = not delineable) coronary segmental analysis, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) measurements were performed. The presence and degree of vascular disease (four-grade scale: mild to severe) was correlated with CaS and cardiovascular (CV) risk stratification blood tests. In patients with severe stenosis (>70%), findings were compared with cardiac nuclear medicine imaging (single photon-emission computed tomography; SPECT) imaging. RESULTS: The average HR, enhancement, and quality score were 64 ± 7 beats/min, 288 ± 66 HU and 1.8 ± .5, respectively. Ninety-three percent (417/450) of the coronary segments were rated diagnostic. The SNRs and CNRs were 17 ± 9 and 12 ± 7 for the right coronary artery; 17 ± 8 and 12 ± 7 for the left main coronary artery; 16 ± 9 and 11 ± 7 for the left anterior descending coronary artery; and 15 ± 7 and 10 ± 6 for the left circumflex coronary artery. Ten of the 30 patients (33%) demonstrated coronary artery disease (CAD) of which two (6%) showed three-vessel disease. Four (13%) patients showed severe disease: in three of which the presence of significant stenosis was confirmed by SPECT and by catheter angiography in the fourth patient. Neither the CaS, nor the CV risk stratification tests showed significant correlation with presence or degree of CAD (p > 0.05). CONCLUSIONS: Coronary DSCT is a robust alternative imaging tool in the preoperative assessment of patients undergoing bariatric surgery.

Bronchoscopic lung-volume reduction with Exhale airway stents for emphysema (EASE trial): randomised, sham-controlled, multicentre trial.

BACKGROUND: Airway bypass is a bronchoscopic lung-volume reduction procedure for emphysema whereby transbronchial passages into the lung are created to release trapped air, supported with paclitaxel-coated stents to ease the mechanics of breathing. The aim of the EASE (Exhale airway stents for emphysema) trial was to evaluate safety and efficacy of airway bypass in people with severe homogeneous emphysema. METHODS: We undertook a randomised, double-blind, sham-controlled study in 38 specialist respiratory centres worldwide. We recruited 315 patients who had severe hyperinflation (ratio of residual volume [RV] to total lung capacity of ≥0·65). By computer using a random number generator, we randomly allocated participants (in a 2:1 ratio) to either airway bypass (n=208) or sham control (107). We divided investigators into team A (masked), who completed pre-procedure and post-procedure assessments, and team B (unmasked), who only did bronchoscopies without further interaction with patients. Participants were followed up for 12 months. The 6-month co-primary efficacy endpoint required 12% or greater improvement in forced vital capacity (FVC) and 1 point or greater decrease in the modified Medical Research Council dyspnoea score from baseline. The composite primary safety endpoint incorporated five severe adverse events. We did Bayesian analysis to show the posterior probability that airway bypass was superior to sham control (success threshold, 0·965). Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00391612. FINDINGS: All recruited patients were included in the analysis. At 6 months, no difference between treatment arms was noted with respect to the co-primary efficacy endpoint (30 of 208 for airway bypass vs 12 of 107 for sham control; posterior probability 0·749, below the Bayesian success threshold of 0·965). The 6-month composite primary safety endpoint was 14·4% (30 of 208) for airway bypass versus 11·2% (12 of 107) for sham control (judged non-inferior, with a posterior probability of 1·00 [Bayesian success threshold >0·95]). INTERPRETATION: Although our findings showed safety and transient improvements, no sustainable benefit was recorded with airway bypass in patients with severe homogeneous emphysema. FUNDING: Broncus Technologies.

Sleep disturbance in menopause.

Sleep disturbance during menopause is a common and important complaint faced by many women. There are many factors that may play a role in this problem, including vasomotor symptoms and changing hormone levels, circadian rhythm abnormalities, exacerbation of primary insomnia, mood disorders, coexistent medical conditions as well as lifestyle factors. Sleep can be measured both objectively and subjectively; however, correlation between the two measures is not high. Most of the menopause-related sleep disturbances have been reported as qualitative in nature; however, there have also been studies showing changes in objective measures. This discrepancy has implications with regard to evaluation of research in sleep and menopause, as well as application in the clinical setting. Investigations of inadequate sleep and sleep problems during the menopausal period and obtaining a thorough understanding of the factors contributing to these problems are essential in formulating treatment strategies. Such strategies can vary from hormonal treatment and medications to lifestyle and behavioural modification.

Cloned mouse cells with natural killer function and cloned suppressor T cells express ultrastructural and biochemical features not shared by cloned inducer T cells.

We have examined the morphology, cytochemistry, and biochemistry of mouse leukocyte subsets by analyzing cloned leukocyte populations specialized to perform different immunologic functions. Cloned cells expressing high-affinity plasma membrane receptors for IgE and mediating natural killer (NK) lysis and cloned antigen-specific suppressor T cells contained prominent osmiophilic cytoplasmic granules similar by ultrastructure to those of mouse basophils. Both clones also incorporated 35SO4 into granule-associated sulfated glycosaminoglycans, expressed a characteristic ultrastructural pattern of nonspecific esterase activity, incorporated exogenous [3H]5-hydroxytryptamine, and contained cytoplasmic deposits of particulate glycogen. By contrast, cloned inducer T cells lacked cytoplasmic granules and glycogen, incorporated neither 35SO4 nor [3H]5-hydroxytryptamine, and differed from the other clones in pattern of nonspecific esterase activity. These findings establish that certain cloned cells with NK activity and cloned suppressor T cells express morphologic and biochemical characteristics heretofore associated with basophilic granulocytes. However, these clones differ in surface glycoprotein expression and immunologic function, and the full extent of the similarities and differences among these populations and basophils remains to be determined.

A computer-aided diagnosis system for quantitative scoring of extent of lung fibrosis in scleroderma patients.

OBJECTIVES: To evaluate an improved quantitative lung fibrosis score based on a computer-aided diagnosis (CAD) system that classifies CT pixels with the visual semi-quantitative pulmonary fibrosis score in patients with scleroderma-related interstitial lung disease (SSc-ILD). METHODS: High-resolution, thin-section CT images were obtained and analysed on 129 subjects with SSc-ILD (36 men, 93 women; mean age 48.8±12.1 years) who underwent baseline CT in the prone position at full inspiration. The CAD system segmented each lung of each patient into 3 zones. A quantitative lung fibrosis (QLF) score was established via 5 steps: 1) images were denoised; 2) images were grid sampled; 3) the characteristics of grid intensities were converted into texture features; 4) texture features classified pixels as fibrotic or non-fibrotic, with fibrosis defined by a reticular pattern with architectural distortion; and 5) fibrotic pixels were reported as percentages. Quantitative scores were obtained from 709 zones with complete data and then compared with ordinal scores from two independent expert radiologists. ROC curve analyses were used to measure performance. RESULTS: When the two radiologists agreed that fibrosis affected more than 1% or 25% of a zone or zones, the areas under the ROC curves for QLF score were 0.86 and 0.96, respectively. CONCLUSIONS: Our technique exhibited good accuracy for detecting fibrosis at a threshold of both 1% (i.e. presence or absence of pulmonary fibrosis) and a clinically meaningful threshold of 25% extent of fibrosis in patients with SSc-ILD.

Mast cell clones: a model for the analysis of cellular maturation.

Cloned mouse mast cells resemble, by ultrastructure, immature mast cells observed in vivo. These mast cell clones can be grown in the absence of any other cells, facilitating direct investigations of their biochemistry and function. We find that cloned mast cells express plasma membrane receptors (Fc epsilon R) that bind mouse IgE with an equilibrium constant (KA) similar to that of normal mouse peritoneal mast cells. In addition, cloned mast cells do not display detectable la antigens and cannot enhance lg secretion when added to lymphocyte cultures or mediate natural killer lysis. In the presence of 1 mM sodium butyrate, cloned mast cells stop dividing and acquire abundant electron-dense cytoplasmic granules similar to those of mature mast cells. Their histamine content increases concomitant with cytoplasmic granule maturation and may exceed that of untreated mast cells by 50-fold. Unlike peritoneal mast cells, cloned mast cells incorporate 35SO4 into chondroitin sulfates rather than heparin. These findings demonstrate that, unlike fully differentiated mouse peritoneal mast cells, cloned immature mouse mast cells contain no heparin and low levels of histamine. In addition, they establish that high-affinity Fc epsilon R are expressed early in mast cell maturation, well before completion of cytoplasmic granule synthesis and mediator storage.

Intravenous stem cell dose and changes in quantitative lung fibrosis and DLCO in the AETHER trial: a pilot study.

OBJECTIVE: Our purpose was to compare quantitative CT-derived changes in lung fibrosis with pulmonary function, including DLCO, in human subjects with idiopathic pulmonary fibrosis who received an injection of one of two different intravenous doses of human bone-marrow-derived mesenchymal stem cells. PATIENTS AND METHODS: Two three-subject cohorts from the AETHER trial (Allogeneic Human Cells in subjects with Idiopathic Pulmonary Fibrosis via Intravenous Delivery) underwent high-resolution CT and clinical testing at baseline, 24 weeks, and 48 weeks after injection. Cohort 1 received 2x107 stem cells, and cohort 2 received 1x108 stem cells. CT scans were quantitatively analyzed for lung fibrosis using 510K cleared validated software. The percent predicted DLCO and other pulmonary function studies were obtained. RESULTS: The cohorts were well matched in lung fibrosis at baseline as assessed by CT scan and lung function. The mean QLF in cohort 1 increased from 13.1% at baseline to 17.1% at 48 weeks, while mean QLF in cohort 2 increased from 15.4% at baseline to 16.5% at 48 weeks. The subjects in cohort 2 progressed more slowly in whole lung fibrosis by a mean of 2.87% compared with cohort 1 (p=0.001 with adjustment of baseline covariates) during the baseline to the 48-week interval. The baseline DLCO was lower in cohort 2 than in cohort 1 (p<0.0001). Over 48 weeks of the study, cohort 2 subjects demonstrated a mean DLCO decline of only 2% compared with a decline of 17% in cohort 1 subjects (p=0.02). CONCLUSIONS: In this pilot study, the subjects receiving 1x108 stem cells demonstrated slower progression in quantitative lung fibrosis and a smaller decrease in DLCO than subjects receiving 2x107 stem cells.

A prospective cohort study of thoracic ultrasound in acute respiratory failure: the C3PO protocol.

OBJECTIVES: This study was performed to assess the clinical utility of a standardised thoracic ultrasound examination when added to standard care in patients with acute respiratory failure admitted to an intermediate care unit. This study aimed to assess the impact on clinical diagnosis, clinician confidence and management. Ultrasound has been shown to have utility in patients admitted to intensive care and emergency; however, utility in a ward setting is unknown. DESIGN: Prospective cohort study. SETTING: Tertiary hospital in Melbourne, Australia. PARTICIPANTS: 50 patients with acute respiratory failure requiring admission to an intermediate care unit. MAIN OUTCOME MEASURES: (1) Change in clinical diagnosis or additional clinical diagnosis following thoracic ultrasound. (2) Change in diagnostic confidence following thoracic ultrasound. (3) Change to management following thoracic ultrasound. RESULTS: In 34% of patients, ultrasound detected unexpected findings that changed or added to the clinical diagnosis. Diagnostic confidence was increased in 44%, and the treating clinician altered the management plan in 30% as a result of the ultrasound. Ultrasound was particularly useful in clarifying the diagnosis in patients with multiple initial diagnoses, reducing to a single diagnosis in 69%. CONCLUSIONS: Thoracic ultrasound has clinical utility in non-intubated adults with acute respiratory failure managed outside intensive care settings. It changed aetiological diagnosis, increases diagnostic confidence and altered clinical management in one out of three patients scanned. Our results suggest extended utility of thoracic ultrasound in acute respiratory failure to a broader context outside the intensive care unit population.

Between-Scanner and Between-Visit Variation in Normal White Matter Apparent Diffusion Coefficient Values in the Setting of a Multi-Center Clinical Trial.

PURPOSE: To study the between-scanner variation and the between-visit reproducibility of brain apparent diffusion coefficient (ADC) measurements in the setting of a multi-center chemotherapy clinical trial for glioblastoma multiforme. METHODS AND MATERIALS: ADC maps of 52 patients at six sites were calculated in-house from diffusion-weighted images obtained by seven individual scanner models of two vendors. The median and coefficient of variation (CV) of normal brain white matter ADC values from a defined region of interest were used to evaluate the differences among scanner models, vendors, magnetic fields, as well as successive visits. All patients participating in this study signed institutional review board approved informed consent. Data acquisition was performed in compliance with all applicable Health Insurance Portability and Accountability Act regulations. The study spanned from August 1, 2006, to January 29, 2008. RESULTS: For baseline median ADC, no difference was observed between the different scanner models, different vendors, and different magnetic field strength. For baseline ADC CV, a significant difference was found between different scanner models (p = 0.0002). No between-scanner difference was observed in ADC changes between two visits. For between-visit reproducibility, significant difference was seen between the ADC values measured at two successive visits for the whole patient group. CONCLUSION: The CVs varied significantly between scanners, presumably due to image noise. Consistent scanner parameter setup can improve reproducibility of the ADC measurements between visits.

Cyst-based measurements for assessing lymphangioleiomyomatosis in computed tomography.

PURPOSE: To investigate the efficacy of a new family of measurements made on individual pulmonary cysts extracted from computed tomography (CT) for assessing the severity of lymphangioleiomyomatosis (LAM). METHODS: CT images were analyzed using thresholding to identify a cystic region of interest from chest CT of LAM patients. Individual cysts were then extracted from the cystic region by the watershed algorithm, which separates individual cysts based on subtle edges within the cystic regions. A family of measurements were then computed, which quantify the amount, distribution, and boundary appearance of the cysts. Sequential floating feature selection was used to select a small subset of features for quantification of the severity of LAM. Adjusted R(2) from multiple linear regression and R(2) from linear regression against measurements from spirometry were used to compare the performance of our proposed measurements with currently used density based CT measurements in the literature, namely, the relative area measure and the D measure. RESULTS: Volumetric CT data, performed at total lung capacity and residual volume, from a total of 49 subjects enrolled in the MILES trial were used in our study. Our proposed measures had adjusted R(2) ranging from 0.42 to 0.59 when regressing against the spirometry measures, with p < 0.05. For previously used density based CT measurements in the literature, the best R(2) was 0.46 (for only one instance), with the majority being lower than 0.3 or p > 0.05. CONCLUSIONS: The proposed family of CT-based cyst measurements have better correlation with spirometric measures than previously used density based CT measurements. They show potential as a sensitive tool for quantitatively assessing the severity of LAM.

Assessment of previous tuberculosis status using questionnaires, chest X-rays and computed tomography scans.

SETTING: Accurate diagnosis of previous pulmonary tuberculosis disease (PPTB) status is important clinically and in research. Reliable records of bacteriologically confirmed tuberculosis (TB) are frequently unavailable. OBJECTIVES: To evaluate the use of questionnaires and chest imaging to determine PPTB status in a high TB prevalence population. DESIGN: PPTB status was assessed using two questionnaires, chest X-ray (CXR) and high-resolution chest computed tomography (CT) scans reported by experienced readers. The study population comprised adults aged >40 years diagnosed with obstructive lung disease in a community-based prevalence survey. RESULTS: The Burden of Obstructive Lung Disease (BOLD) questionnaire and a second comprehensive questionnaire (PTbQ) provided a history of PPTB in respectively 38% (n = 41) and 36.4% (n = 39) of 107 participants. On CXR, 43.3% (45/104) had evidence of PPTB, with good inter-reader agreement (κ = 0.73). Changes compatible with PPTB were identified on chest CT in 68.3% (71/104) of the subjects. Questionnaire and CXR had negative predictive values for PPTB of 48% and 47%, respectively, compared to a composite definition. CONCLUSION: Both questionnaire and CXR markedly underestimate the prevalence of previous TB in patients with chronic obstructive pulmonary disease. The combination of a structured questionnaire and CT scan is more useful when a diagnosis of PPTB needs to be ruled out.

Genetic loci determining bone density in mice with diet-induced atherosclerosis.

This study investigates the phenotypic and genetic relationships among bone-density-related traits and those of adipose tissue and plasma lipids in mice with diet-induced atherosclerosis. Sixteen-month-old female F2 progeny of a C57BL/6J and DBA/2J intercross, which had received an atherogenic diet for 4 mo, were examined for multiple measures of femoral bone mass, density, and biomechanical properties using both computerized tomographic and radiographic methods. In addition, body weight and length, adipose tissue mass, plasma lipids and insulin, and aortic fatty lesions were assessed. Bone mass was inversely correlated with extent of atherosclerosis and with a prooxidant lipid profile and directly correlated with body weight, length, and, most strongly, adipose tissue mass. Quantitative trait locus (QTL) analysis, using composite interval mapping (CIM) and multi-trait analysis, identified six loci with multi-trait CIM LOD scores > 5. Three of these coincided with loci linked with adipose tissue and plasma high-density lipoprotein. Application of statistical tests for distinguishing close linkage vs. pleiotropy supported the presence of a potential pleiotropic effect of two of the loci on these traits. This study shows that bone mass in older female mice with atherosclerosis has multiple genetic determinants and provides phenotypic and genetic evidence linking the regulation of bone density with adipose tissue and plasma lipids.

Relative value of computed tomography scanning and venous sampling in establishing the cause of primary hyperaldosteronism.

The purpose of this study was to evaluate the relative merits of the postural stimulation test, adrenal computed tomography (CT) and venous sampling in the differential diagnosis of patients presenting with primary hyperaldosteronism. The records of 20 patients presenting with primary hyperaldosteronism were reviewed retrospectively. There were 15 patients with a unilateral aldosterone-producing adenoma (APA), four patients with idiopathic hyperaldosteronism (IHA) and one patient with primary adrenal hyperplasia (PAH). The postural stimulation test was based on measurements of plasma aldosterone and renin activity at 08.00 h and at noon after 4 h of ambulation. The CT scans of the adrenals were reviewed by a single radiologist. Bilateral venous sampling of adrenal veins was attempted in all patients and blood collected for aldosterone and cortisol assay. Plasma aldosterone concentration increased after 4 h of standing in all cases of hyperplasia but was also demonstrated in 10/15 patients with a surgically-proven APA. If one defines a significant postural rise as being greater than 30%, then 8/15 patients with APA can be considered as being posturally responsive. Computed tomography scanning correctly identified all 15 cases of APA and also classified correctly the remaining five cases of hyperplasia (four cases of IHA and one case of PAH). Venous sampling failed technically in 4/15 cases of APA and in one case of IHA: a total of 5/20 (25%,). A correct diagnosis of APA or IHA was established in all the remaining cases. However, the one case of PAH was treated successfully by adrenalectomy following venous sampling, which suggested a unilateral adrenal lesion: this one result was the only instance where venous sampling altered clinical decision-making. Computed tomography scanning may be used alone to confirm the cause of hyperaldosteronism where postural studies suggest an adrenal adenoma, and such patients may be considered for early surgery. Venous catheterization studies are not necessary routinely. but may still be useful in selected patients, particularly when CT scanning shows no clear lesion.

Problem-oriented prefetching for an integrated clinical imaging workstation.

Prefetching methods have traditionally been used to restore archived images from picture archiving and communication systems to diagnostic imaging workstations prior to anticipated need, facilitating timely comparison of historical studies and patient management. The authors describe a problem-oriented prefetching scheme, detailing 1) a mechanism supporting selection of patients for prefetching via characterizations of clinical problems, using multiple data sources (picture archiving and communication systems, hospital information systems, and radiology information systems), classifying patients into cohorts on the basis of their medical conditions (e.g., lung cancer); and 2) prefetching of multimedia data (imaging, laboratory, and medical reports) from clinical databases to enable the viewing of an integrated patient record. Preliminary evaluation of the prefetching algorithm using classic information retrieval measures showed that the system had high recall (100 percent), correctly identifying and retrieving data for all patients belonging to a target cohort, but low precision (50 percent). A key finding during testing was that the recall of the system was increased through the use of multiple data sources (compared with one data source), because of better patient descriptors. Medical problems and patient cohorts were more specifically defined by combining information from heterogeneous databases.

A pattern classification approach to characterizing solitary pulmonary nodules imaged on high resolution CT: preliminary results.

The purpose of this research is to characterize solitary pulmonary nodules as benign or malignant based on quantitative measures extracted from high resolution CT (HRCT) images. High resolution CT images of 31 patients with solitary pulmonary nodules and definitive diagnoses were obtained. The diagnoses of these 31 cases (14 benign and 17 malignant) were determined from either radiologic follow-up or pathological specimens. Software tools were developed to perform the classification task. On the HRCT images, solitary nodules were identified using semiautomated contouring techniques. From the resulting contours, several quantitative measures were extracted related to each nodule's size, shape, attenuation, distribution of attenuation, and texture. A stepwise discriminant analysis was performed to determine which combination of measures were best able to discriminate between the benign and malignant nodules. A linear discriminant analysis was then performed using selected features to evaluate the ability of these features to predict the classification for each nodule. A jackknifed procedure was performed to provide a less biased estimate of the linear discriminator's performance. The preliminary discriminant analysis identified two different texture measures--correlation and difference entropy--as the top features in discriminating between benign and malignant nodules. The linear discriminant analysis using these features correctly classified 28/31 cases (90.3%) of the training set. A less biased estimate, using jackknifed training and testing, yielded the same results (90.3% correct). The preliminary results of this approach are very promising in characterizing solitary nodules using quantitative measures extracted from HRCT images. Future work involves including contrast enhancement and three-dimensional measures extracted from volumetric CT scans, as well as the use of several pattern classifiers.

Knowledge-based segmentation of thoracic computed tomography images for assessment of split lung function.

The assessment of differential left and right lung function is important for patients under consideration for lung resection procedures such as single lung transplantation. We developed an automated, knowledge-based segmentation algorithm for purposes of deriving functional information from dynamic computed tomography (CT) image data. Median lung attenuation (HU) and area measurements were automatically calculated for each lung from thoracic CT images acquired during a forced expiratory maneuver as indicators of the amount and rate of airflow. The accuracy of these derived measures from fully automated segmentation was validated against those from segmentation using manual editing by an expert observer. A total of 1313 axial images were analyzed from 49 patients. The images were segmented using our knowledge-based system that identifies the chest wall, mediastinum, trachea, large airways and lung parenchyma on CT images. The key components of the system are an anatomical model, an inference engine and image processing routines, and segmentation involves matching objects extracted from the image to anatomical objects described in the model. The segmentation results from all images were inspected by the expert observer. Manual editing was required to correct 183 (13.94%) of the images, and the sensitivity, specificity, and accuracy of the knowledge-based segmentation were greater than 98.55% in classifying pixels as lung or nonlung. There was no significant difference between median lung attenuation or area values from automated and edited segmentations (p > 0.70). Using the knowledge-based segmentation method we can automatically derive indirect quantitative measures of single lung function that cannot be obtained using conventional pulmonary function tests.

Intracranial volume change in childhood.

OBJECT: The goal of this study was to construct a model of normal changes in intracranial volume occurring throughout childhood from age 7 days to 15 years. METHODS: Using the technique of segmentation on magnetic resonance images obtained in healthy children, intracranial volume was measured and plotted against age. CONCLUSIONS: Intracranial volume in the first few months of life is on average 900 cm3 in males and 600 cm3 in females. By the age of 15 years, it increases up to 1500 cm3 in males and 1300 cm3 in females, increased by factors of 1.6 and 2.1, respectively. By the time the child reaches 2 years of age, intracranial volume has reached 77% (1150 cm3 in males and 1000 cm3 in females) and, by 5 years, 90% (1350 cm3 in males and 1200 cm3 in females) of the volume observed at age 15 years. The change in intracranial volume that occurs with age is not linear, but there seems to be a segmental pattern. Three main periods can be distinguished, each lasting approximately 5 years (0-5, 5-10, and 10-15 years), during which the growth of intracranial volume is linear. Throughout childhood, males have higher intracranial volumes than females, with a similar growth pattern.

Intracranial volume change in craniosynostosis.

OBJECT: There is still controversy regarding the optimum time to perform surgery for craniosynostosis. Some recommend surgery soon after birth and others delay until the age of 12 months. Intracranial pressure has been measured in an attempt to provide a scientific rationale, but many questions remain unanswered. To date, little attention has been given to intracranial volume and its changes during the first few years of life in children with craniosynostosis. The authors' goal was to focus on intracranial volume during this period and to compare measurements obtained in patients with craniosynostosis with measurements obtained in healthy individuals. METHODS: Using the technique of segmentation, the intracranial volume of 84 children with various forms of craniosynostosis was measured on preoperative computerized tomography scans. The change in average volume that occurs with increasing age was calculated and compared with a model of normal intracranial volume growth. The age at presentation for children with craniosynostosis was 1 to 39 months; 76% of the patients were younger than 12 months. In eight patients in whom only one cranial expansion procedure was performed, postoperative intracranial volumes were measured as well. Several interesting observations emerged. 1) There was little difference in head growth between boys and girls with craniosynostosis during the first few months of life. After the age of 12 months, however, the difference in intracranial volume normally seen between the two genders was observed in the craniosynostosis group as well. 2) Excluding children with complex pansynostosis, who have smaller heads, children with all other types of craniosynostosis have similar head growth after the 1st year of life, with no difference between the number of and type of suture affected. Children with Apert's syndrome develop greater than normal intracranial volumes after the 1st year of life. 3) Although children with craniosynostosis are born with a smaller intracranial volume, by the age of 6 months volume has reached normal levels, and from that point on volume follows the pattern of normal head growth. 4) Children who presented after the age of 6 months and later developed recurrent craniosynostosis after initial successful treatment had a small intracranial volume at their initial presentation. 5) Of the patients whose postoperative intracranial volumes were measured, all but one had preoperative volumes at or above normal values, and their postoperative volumes were considerably higher than normal for their age. These children all followed a growth curve parallel to that of healthy children but at higher volume value. One patient with a smaller-than-normal initial intracranial volume was surgically treated at a very young age and, despite cranial expansion surgery, postoperative volume did not reach normal levels. It is postulated that this was due to the fact that the operation was performed at a time when craniosynostosis was still active. CONCLUSIONS: The results of this study indicate that the underlying mechanism leading to craniosynostosis and constriction of head volume "exhausts" its effect during the first few months of life. Measurement of intracranial volume in clinical practice could be used to "fine tune" the optimum time for surgery. In late-presenting children, this may be useful in predicting possible recurrence.

Patient-specific models for lung nodule detection and surveillance in CT images.

The purpose of this work is to develop patient-specific models for automatically detecting lung nodules in computed tomography (CT) images. It is motivated by significant developments in CT scanner technology and the burden that lung cancer screening and surveillance imposes on radiologists. We propose a new method that uses a patient's baseline image data to assist in the segmentation of subsequent images so that changes in size and/or shape of nodules can be measured automatically. The system uses a generic, a priori model to detect candidate nodules on the baseline scan of a previously unseen patient. A user then confirms or rejects nodule candidates to establish baseline results. For analysis of follow-up scans of that particular patient, a patient-specific model is derived from these baseline results. This model describes expected features (location, volume and shape) of previously segmented nodules so that the system can relocalize them automatically on follow-up. On the baseline scans of 17 subjects, a radiologist identified a total of 36 nodules, of which 31 (86%) were detected automatically by the system with an average of 11 false positives (FPs) per case. In follow-up scans 27 of the 31 nodules were still present and, using patient-specific models, 22 (81%) were correctly relocalized by the system. The system automatically detected 16 out of a possible 20 (80%) of new nodules on follow-up scans with ten FPs per case.

Method for segmenting chest CT image data using an anatomical model: preliminary results.

We present an automated, knowledge-based method for segmenting chest computed tomography (CT) datasets. Anatomical knowledge including expected volume, shape, relative position, and X-ray attenuation of organs provides feature constraints that guide the segmentation process. Knowledge is represented at a high level using an explicit anatomical model. The model is stored in a frame-based semantic network and anatomical variability is incorporated using fuzzy sets. A blackboard architecture permits the data representation and processing algorithms in the model domain to be independent of those in the image domain. Knowledge-constrained segmentation routines extract contiguous three-dimensional (3-D) sets of voxels, and their feature-space representations are posted on the blackboard. An inference engine uses fuzzy logic to match image to model objects based on the feature constraints. Strict separation of model and image domains allows for systematic extension of the knowledge base. In preliminary experiments, the method has been applied to a small number of thoracic CT datasets. Based on subjective visual assessment by experienced thoracic radiologists, basic anatomic structures such as the lungs, central tracheobronchial tree, chest wall, and mediastinum were successfully segmented. To demonstrate the extensibility of the system, knowledge was added to represent the more complex anatomy of lung lesions in contact with vessels or the chest wall. Visual inspection of these segmented lesions was also favorable. These preliminary results suggest that use of expert knowledge provides an increased level of automation compared with low-level segmentation techniques. Moreover, the knowledge-based approach may better discriminate between structures of similar attenuation and anatomic contiguity. Further validation is required.