Development of body knowledge as measured by arm differentiation in infants: From global to local?

The ability to sense and use the body parts in an organized and differentiated manner is a precursor of body knowledge in infancy. To acquire this ability, the infant's brain might explore the perceptual consequences of its bodily actions. Undifferentiated body movements would gradually be replaced by more precise actions. Only a very few studies have tested this ‘global‐to‐local’ hypothesis, and none of them have so far been replicated. In this study, we assessed arm differentiation in 4‐, 6‐, and 8‐month‐old infants using a new contingency detection task in which infants have to detect a contingency between one of their arms’ activity and an audiovisual stimulus on a screen. We found that 4‐ to 8‐month‐old infants seem to be able to use their arms in a differentiated manner. However, surprisingly, we were not able to show a developmental trend in arm differentiation between 4 and 8 months of age.

Combining structural and textural assessments of volumetric FDG-PET uptake in NSCLC

Numerous studies have reported the prognostic utility of texture analyses and the effectiveness of radiomics in PET and PET/CT assessment of non-small cell lung cancer (NSCLC). Here we explore the potential, relative to this methodology, of an alternative model-based approach to tumour characterization, which was successfully applied to sarcoma in previous works. The spatial distribution of 3D FDG-PET uptake is evaluated in the spatial referential determined by the best-fitting ellipsoidal pattern, which provides a univariate uptake profile function of the radial position of intratumoral voxels. A group of structural features is extracted from this fit that include two heterogeneity variables and statistical summaries of local metabolic gradients. We demonstrate that these variables capture aspects of tumour metabolism that are separate to those described by conventional texture features. Prognostic model selection is performed in terms of a number of classifiers, including stepwise selection of logistic models, LASSO, random forests and neural networks with respect to two-year survival status. Our results for a cohort of 93 NSCLC patients show that structural variables have significant prognostic potential, and that they may be used in conjunction with texture features in a traditional radiomics sense, towards improved baseline multivariate models of patient overall survival. The statistical significance of these models also demonstrates the relevance of these machine learning classifiers for prognostic variable selection.

Tissue and Bronchoalveolar Lavage Biomarkers in Idiopathic Pulmonary Fibrosis Patients on Pirfenidone

BACKGROUND

Pirfenidone is a novel anti-fibrotic agent in idiopathic pulmonary fibrosis with proven clinical benefit. Better human tissue models to demonstrate the immunomodulatory and anti-fibrotic effect of pirfenidone are required.

OBJECTIVES

The purpose of the study was to use transbronchial lung cryobiopsy (TBLC), a novel technique which provides substantial tissue samples, and a large panel of biomarkers to temporally assess disease activity and response to pirfenidone therapy.

METHODS

Thirteen patients with confirmed idiopathic pulmonary fibrosis (IPF) underwent full physiological and radiological assessment at diagnosis and after 6-month pirfenidone therapy. They underwent assessment for a wide range of potential serum and bronchoalveolar lavage biomarkers of disease activity. Finally, they underwent TBLC before and after treatment. Tissue samples were assessed for numbers of fibroblast foci, for Ki-67, a marker of tissue proliferation and caspase-3, a marker of tissue apoptosis.

RESULTS

All patients completed treatment and investigations without significant incident. There was no significant fall in number of fibroblast foci per unit tissue volume after treatment (pre-treatment: 0.14/mm² vs. post-treatment 0.08/mm², p = 0.1). Likewise, there was no significant change in other markers of tissue proliferation, Ki-67 or Caspase-3 with pirfenidone treatment. We found an increase in three bronchoalveolar lavage angiogenesis cytokines, Placental Growth Factor, Vascular Endothelial Growth Factor-A, and basic Fibroblast Growth Factor, two anti-inflammatory cytokines Interleukin-10 and Interleukin-4 and Surfactant Protein-D.

CONCLUSIONS

TBLC offers a unique opportunity to potentially assess the course of disease activity and response to novel anti-fibrotic activity in IPF.

Fetal Origin of Sensorimotor Behavior

The aim of this article is to track the fetal origin of infants' sensorimotor behavior. We consider development as the self-organizing emergence of complex forms from spontaneously generated activity, governed by the innate capacity to detect and memorize the consequences of spontaneous activity (contingencies), and constrained by the sensory and motor maturation of the body. In support of this view, we show how observations on fetuses and also several fetal experiments suggest that the fetus's first motor activity allows it to feel the space around it and to feel its body and the consequences of its movements on its body. This primitive motor babbling gives way progressively to sensorimotor behavior which already possesses most of the characteristics of infants' later behavior: repetition of actions leading to sensations, intentionality, some motor control and oriented reactions to sensory stimulation. In this way the fetus can start developing a body map and acquiring knowledge of its limited physical and social environment.

Anomalous right upper lobe venous drainage

Lung resections are usually not associated with significant bleeding, but can be fatal, especially in cases of video-assisted thoracoscopic surgery (VATS). Anomalous vascular structures could be a major reason for unexpected bleeding in such surgeries. We present a case of an aberrant upper lobe pulmonary vein that was encountered posterior to the right upper lobe bronchus during a right upper lobectomy via thoracotomy. The anomalous pulmonary vein was identified preoperatively on a computed tomography (CT) scan and hence was looked for before dividing the bronchus. Many centres are adopting the VATS approach for performing lung resections. If an anomalous vein is present posterior to the bronchus, it might be in a blind spot and could be damaged inadvertently, leading to profuse and potentially fatal bleeding. We conclude that the identification of anomalous vascular structures prior to surgery with the help of CT helps in avoiding adverse outcomes.

Biomarkers to identify ILD and predict lung function decline in scleroderma lung disease or idiopathic pulmonary fibrosis

BACKGROUND

SSc-ILD and IPF demonstrate significant morbidity and mortality. Predicting disease progression is challenging in both diseases.

OBJECTIVES

We sought a serum biomarker that could identify patients with SSc-ILD or IPF and prospectively predict short-term decline in lung function in these patients.

METHODS

10 healthy controls, 5 SSc w/o ILD, 6 SSc-ILD and 13 IPF patients underwent venesection. An array of cytokines including KL-6, SP-D and MMP7 were measured. PFTs were obtained at baseline and six months. Cytokine measurements were correlated with PFTs.

RESULTS

KL-6 in IPF patients (633 ng/ml, IQR 492-1675) was significantly elevated compared to controls (198 ng/ml, IQR 52-360, p<0.01) and SSc w/o ILD patients (192 ng/ml, IQR 0-524, p<0.05); KL-6 in SSc-ILD patients (836 ng/ml, IQR 431-1303) was significantly higher than in controls (p<0.05). SP-D was significantly higher in IPF patients (542 ng/ml, IQR 305-577) compared to controls (137 ng/ml, IQR 97-284, p<0.01) or to SSc w/o ILD patients (169 ng/ml, IQR 137-219, p<0.05). In comparison with controls (0.0 ng/ml, IQR 0.0-0.6), MMP7 was significantly higher in both IPF patients (2.85 ng/ml, IQR 1.5-3.6, p<0.05) and SSc-ILD patients (5.41 ng/ml, IQR 2.6-7.2, p<0.001). Using a cut-off level of 459ng/ml for KL-6 and of 1.28 ng/ml for MMP7, 18 out of 19 patients with ILD had a serum value of either KL-6 or MMP7 above these thresholds. For all ILD patients, baseline serum SP-D correlated with ΔFVC %pred over six months (r=-0.63, p=0.005, 95% CI -0.85 to -0.24).

CONCLUSIONS

Combining KL-6 with MMP7 may be a useful screening tool for patients at risk of ILD. SP-D may predict short-term decline in lung function.

Increasing the accuracy of 18F-FDG PET/CT interpretation of "mildly positive" mediastinal nodes in the staging of non-small cell lung cancer

INTRODUCTION

The aim of this study was to identify radiological factors that may reduce false-positive results and increase diagnostic accuracy when staging the mediastinum of patients with non-small cell lung carcinoma (NSCLC).

METHODS

This was a retrospective, interdisciplinary, per-node analysis study. We included patients with NSCLC and mediastinal nodes with an SUV max in the range of 2.5-4.0 on PET-CT. We hypothesized that the greatest number of false positive cases would occur in this cohort of patients.

RESULTS

A total of 92 mediastinal lymph nodes were analyzed in 44 patients. Mediastinal disease (N2/N3) was histologically confirmed in 15 of 44 patients and in 34 of 92 lymph nodes; positive predictive value of 37% and false positive rate of 63%. Lymph node SUV max, tumor size, ratio of node SUV max to tumor SUV max (SUVn/SUVp), and ratio of node SUV max to node size (SUV n/SADn) were significantly higher in true positive cases. Using a threshold of 0.3 for SUV node/tumor and 3 for SUV node/size yielded sensitivities of 91% and 71% and specificities of 71% and 69% respectively for the detection of mediastinal disease. Using both ratios in combination resulted in a sensitivity of 65% and a specificity of 88%. Concurrent benign lung disease was observed significantly more frequently in false-positive cases.

CONCLUSION

SUVn/SUVpt and SUVn/SADn may be complimentary to conventional visual interpretation and SUV max measurement in the assessment of mediastinal disease in patients with NSCLC.

Metastatic mucosal melanoma: imaging patterns of metastasis and recurrence

PURPOSE

Mucosal melanoma is a rare but aggressive subtype of melanoma with unique clinicopathologic features. We hypothesize that mucosal melanoma shows predilection for separate and unique metastatic pathways.

MATERIALS AND METHODS

This was a retrospective analysis of 19 patients (5 men and 14 women; median age 60 years, range 38-76 years) with metastatic mucosal melanoma presenting to a tertiary oncology center between 2005 and 2010. We performed a review of medical records and histologic and imaging studies to evaluate the natural history, metastatic patterns and the role of imaging in the management of patients with advanced mucosal melanoma.

RESULTS

At presentation, disease was confined to the primary site (58%, n = 11) or to the regional lymph nodes (32%, n = 6) in most patients. The most common site of metastasis was the lungs (89%, n = 16), followed by the liver (67%, n = 12) and peritoneum (44%, n = 8). Sinonasal melanoma preferentially spread to the liver (100%, n = 4), vaginal melanoma to the lungs (100%, n = 7) and anal melanoma to the inguinal lymph nodes (100%, n = 4).

CONCLUSION

Pathways of metastatic spread in mucosal melanoma may differ from other forms of melanoma and between different primary sites of mucosal origin.

Molecular targeted therapies in non-GIST soft tissue sarcomas: what the radiologist needs to know

Non-gastrointestinal stromal soft tissue sarcomas are uncommon neoplasms that have a dismal prognosis due to a high incidence of metastases and a poor response to conventional chemotherapy. The identification of characteristic genetic alterations in several of these tumors has opened the window for molecular targeted therapies in patients who have failed conventional chemotherapy. Imaging plays a critical role in assessing the response to these novel therapeutic agents. Just like the response of gastrointestinal stromal tumors to imatinib, the response of non-gastrointestinal stromal soft tissue sarcomas to molecular targeted drugs is better evaluated on imaging by alternate tumor response criteria such as the Choi criteria. In addition, these drugs are associated with distinct class-specific drug toxicities that can come to attention for the first time on imaging. The purpose of this article is to provide a primer for the radiologist on the various molecular targeted therapies in advanced/metastatic non-gastrointestinal stromal soft tissue sarcomas with emphasis on the role of imaging in assessing treatment response and complications.

Plain abdominal radiographs in patients with Crohn's disease: radiological findings and diagnostic value

AIM

To determine the diagnostic yield and clinical value of plain film of the abdomen (PFA) in Crohn's disease (CD) patients and to determine whether performance of PFA yields definitive diagnostic information or whether additional imaging examinations are required.

MATERIALS AND METHODS

One hundred and seventy-seven CD patients underwent 643 PFAs during the period September 1992 to August 2008. Two radiologists blinded to the clinical details independently evaluated individual PFAs and/or their reports for abnormal findings using the following criteria: normal, small bowel (SB) findings; colonic findings, acute CD complications, extra-colonic findings; global assessment/impression. The results of additional imaging studies performed within 5 days of PFA were recorded and findings were analysed.

RESULTS

A mean of 3.6 (range 1-22) PFAs was performed per patient during the study period. Almost 70% of films were normal (n = 449). SB abnormalities were detected in 21.8% (n = 140) PFAs; most commonly dilated loops (18.8%, n = 121) and mucosal oedema (5%, n = 32). Colonic abnormalities were present in 11.4% (n = 73); most commonly mucosal oedema (7.5%, n = 48) and dilated loops (5%, n = 32). Four cases of pneumoperitoneum were detected. There was no case of toxic megacolon. There was one case in which intra-abdominal abscess/collection was suspected and two cases of obstruction/ileus. Extracolonic findings (renal calculi, sacro-iliitis, etc.) were identified in 7.5% (n = 48). PFAs were followed by additional abdominal imaging within 5 days of PFA in 273/643 (42.5%) of cases.

CONCLUSION

Despite the high rates of utilization of PFA in CD patients, there is a low incidence of abnormal findings (32.5%). Many of the findings are non-specific and clinically irrelevant and PFA is frequently followed by additional abdominal imaging examinations.

Malignant primary chest wall neoplasms: a pictorial review of imaging findings

Malignant primary chest wall neoplasms (MCWN) are uncommon. Although benign chest wall neoplasms are most commonly asymptomatic, MCWN typically manifest as painful, fast growing masses. While the imaging features of malignant masses can be nonspecific, knowledge of the typical radiologic manifestations of MCWN may suggest a specific diagnosis. We review imaging features of the most common MCWN with images collected at an outpatient academic oncologic center.

OBJECTIVE

While the imaging features of patients with malignant masses can be nonspecific, knowledge of the typical radiologic manifestations of MCWN may suggest a specific diagnosis. We review distinguishing imaging features of the most common MCWN, including epithelial and mesenchymal malignancies, with images collected at an outpatient oncologic center.

CONCLUSION

Chest wall neoplasms encompass 5% of all thoracic tumors, with nearly half of chest wall neoplasms being malignant. Out of these malignant neoplasms, 50% are primary and the commonest one is chondrosarcoma. Although distinguishing imaging features may suggest a specific diagnosis in the majority of MCWN, most affected patients undergo biopsy for a definitive diagnosis.

Imaging features of bowel toxicities in the setting of molecular targeted therapies in cancer patients

Molecular targeted therapies are becoming ubiquitous in cancer treatment. These drugs may cause gastrointestinal toxicities including perforation, pneumatosis, enteritis, colitis and fistula formation. Knowledge of these complications and their management enables early radiological identification and appropriate intervention, reducing patient morbidity and mortality.

Image quality associated with the use of an MR-compatible incubator in neonatal neuroimaging

OBJECTIVES

MRI in the neonate poses significant challenges associated with patient transport and monitoring, and the potential for diminished image quality owing to patient motion. The objective of this study was to evaluate the usefulness of a dedicated MR-compatible incubator with integrated radiofrequency coils in improving image quality of MRI studies of the brain acquired in term and preterm neonates using standard MRI equipment.

METHODS

Subjective and objective analyses of image quality of neonatal brain MR examinations were performed before and after the introduction of an MR-compatible incubator. For all studies, the signal-to-noise ratio (SNR) was calculated, image quality was graded (1-3) and each was assessed for image artefact (e.g. motion). Student's t-test and the Mann-Whitney U-test were used to compare mean SNR values.

RESULTS

39 patients were included [mean gestational age 39 weeks (range 30-42 weeks); mean postnatal age 13 days (range 1-56 days); mean weight 3.5 kg (range 1.4-4.5 kg)]. Following the introduction of the MR-compatible incubator, diagnostic quality scans increased from 50 to 89% and motion artefact decreased from 73 to 44% of studies. SNR did not increase initially, but, when using MR sequences and parameters specifically tailored for neonatal brain imaging, SNR increased from 70 to 213 (p=0.001).

CONCLUSION

Use of an MR-compatible incubator in neonatal neuroimaging provides a safe environment for MRI of the neonate and also facilitates patient monitoring and transport. When specifically tailored MR protocols are used, this results in improved image quality.

Case report: atypical lipomatous tumor with unusual extensive metaplastic ossification

The presence of metaplastic ossification within atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLPS) is a rare occurrence. When present, bone formation is most often found in association with a dedifferentiated component arising within the primary tumor. It is important for the radiologist not only to recognize the differential diagnosis of a calcified or ossified soft tissue mass but also be aware of the various soft tissue neoplasms, both aggressive and non-aggressive, that may show such features. We report a case of ALT/WDLPS with unusual extensive metaplastic bone formation without an element of dedifferentiated liposarcoma.

Pheochromocytoma and paraganglioma: imaging characteristics

The accurate diagnosis of adult pheochromocytoma and paraganglioma necessitates a multidisciplinary approach that includes clinical history, biochemical testing, and multimodality imaging such as computed tomography, magnetic resonance imaging, and nuclear medicine studies. This review illustrates the different imaging characteristics of primary adult pheochromocytomas as well as both sympathetic and parasympathetic paragangliomas. The review also describes known genetic associations and shows common metastatic patterns. Knowledge of the diverse appearance of pheochromocytomas and paragangliomas can result in early initial diagnosis or detection of disease recurrence thereby affecting patient management and prognosis.

Multimodality imaging in amyloidosis

Amyloidosis comprises a rare spectrum of protein deposition diseases that diffusely or focally affect any organ. Amyloid's variable clinical presentation and nonspecific disease course often cause it to evade early diagnosis. This pictorial essay aims to familiarize radiologists with the pathophysiology of amyloidosis, to describe the basic classifications of amyloidosis, and to use multimodality imaging to illustrate its varied appearance throughout the body. This review highlights the diagnostic challenge of interpreting radiographic studies in patients with hematologic malignancies and concurrent amyloidosis. Radiologists should consider amyloid in chronically ill patients or patients with hematologic malignancies who have unusual/unexpected imaging findings.

Selection of symptomatic patients with Crohn's disease for abdominopelvic computed tomography: role of serum C-reactive protein

BACKGROUND

Results of previous studies have shown that repeated abdominopelvic computed tomography (CT) examinations can lead to substantial cumulative diagnostic radiation exposure in patients with Crohn's disease (CD). Improved selection of patients referred for CT will reduce unnecessary radiation exposure. This study examines if serum C-reactive protein (CRP) concentration predicts which symptomatic patients with CD are likely to have significant disease activity or disease complications (such as abscess) detected on abdominopelvic CT.

METHODS

All abdominopelvic CTs performed on patients with CD at a tertiary referral centre during the period June 2003 to June 2008 were identified. CT findings were coded by a pair of independent blinded senior radiologists for (i) small bowel luminal disease, (ii) large bowel luminal disease, (iii) mesenteric inflammatory changes, (iv) penetrating disease (fistulas, abscess, or phlegmon), (v) acute disease complications (obstruction or perforation), and (vi) acute non-CD findings. Imaging findings were correlated with serum CRP checked within 14 days before imaging. The reference range for CRP was defined as 0-5 mg/L.

RESULTS

A total of 147 patients with symptomatic CD had a CRP assay performed within 14 days before undergoing abdominopelvic CT. The median time from CRP assay to imaging was 2 days (interquartile range, 0-6 days). Median CRP before imaging was 24 mg/L (interquartile range, 6-88 mg/L). CT was normal in 34 of 147 case (23.1%). Patients with normal CRP (n = 36) were significantly less likely to have penetrating disease (odds ratio [OR], 0.04 [95% confidence interval {CI}, 0.01-0.7]; P < .001) or large bowel luminal disease (OR, 0.3 [95% CI, 0.1-0.8]; P < .05). Normal CRP excluded penetrating disease with a sensitivity of 1.0 (95% CI, 0.87-1.0). CRP levels did not correlate with the presence of small bowel luminal disease (n = 82), mesenteric inflammatory changes (n = 68), or acute disease complications (n = 10).

CONCLUSION

Symptomatic patients with CD and normal serum CRP are unlikely to have evidence of abscess, fistulating disease, or large bowel luminal disease detected on abdominopelvic CT. However, abdominopelvic CT may demonstrate evidence of clinically significant non-penetrating CD or complications, including perforation and acute obstruction, regardless of serum CRP concentration.

Demonstration of the course of the posterior intercostal artery on CT angiography: relevance to interventional radiology procedures in the chest

PURPOSE

To document the course of the posterior intercostal artery (PIA) within the intercostal space (IS) in vivo using computed tomography angiography (CTA).

MATERIALS AND METHODS

A review of 428 IS from CTA of the chest was performed. Using multiplanar reconstruction (MPR) algorithms, the course of the PIA within the IS and the maximum distance of the PIA from the undersurface of the rib were determined in the 4th to 8th IS at three clinically relevant points: the posterior paravertebral area (PPV), angle of the rib (AR), and 25 mm lateral to the angle of the rib (LAR). Tortuosity of the vessels was graded from coronal three-dimensional images.

RESULTS

The mean maximum distances of the PIA within the IS from the undersurface of the rib were as follows: PPV, 7.2±0.512 mm (P = 0.0027); AR, 5.5±0.535 mm (P = 0.0487); and LAR, 2.3±0.366 mm (P = 0.0052). At the PPV, the PIA lies halfway between the two ribs within the IS and lies one third of the way from the undersurface of the rib at the AR and comes to lie within the subcostal groove toward the mid-axillary line. The tortuosity of the vessel was highly variable and was independent of both age and gender.

CONCLUSION

Considerable variability in vessel position was noted within the IS, with the PIA lying furthest from the undersurface of the rib in the PPV. To avoid injury, our data support the dictum "choose a site above the rib below," and additional caution should be taken to avoid the posterior paravertebral area.

The role of 18F-FDG PET/CT imaging in Waldenstrom macroglobulinemia

Disease assessment in WM is dependent on the quantification of the IgM monoclonal protein and percent involvement of the bone marrow. There is a need for imaging studies that objectively measure tumor load in these patients. In this study, we sought to examine the role of combined FDG-PET/CT imaging in the detection of tumor load and in the assessment of response to therapy. Thirty-five patients were enrolled on a prospective study using bortezomib and rituximab therapy and were included in this study because they completed a pre- and post-treatment FDG-PET/CT imaging at one facility (12 newly diagnosed and 23 relapsed/refractory). The use of combined FDG-PET/CT imaging showed positive findings in 83% of patients with WM, unlike prior studies using conventional imaging that indicate that only 20% of patients have lymphadenopathy or hepatosplenomegaly. Moreover, 43% of patients had abnormal bone marrow uptake on FDG-PET imaging that can potentially help in the assessment of their tumor load, especially with heterogenous sampling of the bone marrow. There was no statistical correlation between EORTC response criteria for FDG-PET/CT and response by monoclonal protein. This is the first study to examine the role of FDG-PET/CT imaging in WM. Future studies should examine the role of FDG-PET/CT in conjunction with monoclonal protein response in the assessment of progression-free survival in patients with WM.

Ovarian squamous cell carcinoma arising from mature cystic teratoma

Preoperative diagnosis of malignant transformation of an ovarian mature cystic teratoma to squamous cell carcinoma is difficult due to nonspecific tumor markers and imaging findings. This is an interesting case presentation that has prior imaging that demonstrates imaging characteristics of the transformation of a mature cystic teratoma to squamous cell carcinoma.

Fulminant limb and retroperitoneal necrotizing fasciitis in a 15-year-old girl with Fanconi anaemia

Necrotizing fasciitis (NF) is an uncommon soft-tissue infection in children that carries a high mortality rate. We present a 15-year-old girl with chronic pancytopenia secondary to Fanconi anaemia who developed extensive NF of the lower limb, which unfortunately resulted in a fatal outcome. Immunodeficiency is a known risk factor for the development of this condition. The findings in this case demonstrate that patients with Fanconi anaemia may be susceptible to NF and that the clinical course may be more aggressive due to underlying immunosuppression. Prompt diagnosis of NF is vital in order to initiate appropriate treatment and to optimize patient outcome. Radiological investigation demonstrated extensive soft-tissue gas and destruction affecting the entire lower limb, abdominal wall and retroperitoneum, which led to timely definitive diagnosis and management.

Crohn's disease: factors associated with exposure to high levels of diagnostic radiation

AIMS

Exposure to diagnostic radiation may be associated with increased risk of malignancy. The aims of this study were to (1) examine patterns of use of imaging in Crohn's disease; (2) quantify the cumulative effective dose (CED) of diagnostic radiation received by patients; and (3) identify patients at greatest risk of exposure to high levels of diagnostic radiation.

METHODS

409 patients with Crohn's disease were identified at a tertiary centre. CED was calculated retrospectively from imaging performed between July 1992 and June 2007. High exposure was defined as CED>75 mSv, an exposure level which has been reported to increase cancer mortality by 7.3%. Complete data were available for 399 patients. 45 were excluded (20 attended outside the study period, 25 were primarily managed at other centres).

RESULTS

Use of computed tomography increased significantly and accounted for 77.2% of diagnostic radiation. Mean CED was 36.1 mSv and exceeded 75 mSv in 15.5% of patients. Factors associated with high cumulative exposure were: age <17 years at diagnosis (hazard ratio 2.1, confidence interval (CI) 1.1 to 4.1), upper gastrointestinal tract disease (odds ratio (OR) 2.4, CI 1.2 to 4.9), penetrating disease (OR 2.0, CI 1.0 to 3.9) and requirement for intravenous steroids (OR 3.7, CI 2.0 to 6.6); infliximab (OR 2.3, CI 1.2 to 4.4); or multiple (>1) surgeries (OR 2.7, CI 1.4 to 5.4).

CONCLUSIONS

Identifiable subsets of patients with Crohn's disease are at risk of exposure to significant amounts of diagnostic radiation. Given the background risk of neoplasia and exposure to potentially synergistic agents such as purine analogues and other immune modulators, specialist centres should develop low-radiation imaging protocols.

THERE IS SOMETHING OUT THERE: DISTAL ATTRIBUTION IN SENSORY SUBSTITUTION, TWENTY YEARS LATER

Sensory substitution constitutes an interesting domain of study to consider the philosopher's classical question of distal attribution: how we can distinguish between a sensation and the perception of an object that causes this sensation. We tested the hypothesis that distal attribution consists of three distinct components: an object, a perceptual space, and a coupling between subjects' movements and stimulation. We equipped sixty participants with a visual-to-auditory substitution device, without any information about it. The device converts the video stream produced by a head-mounted camera into a sound stream. We investigated several experimental conditions: the existence or not of a correlation between movements and resulting stimulation, the direct or indirect manipulation of an object, and the presence of a background environment. Participants were asked to describe their impressions by rating their experiences in terms of seven possible "scenarios". These scenarios were carefully chosen to distinguish the degree to which the participants attributed their sensations to a distal cause. Participants rated the scenarios both before and after they were given the possibility to interrupt the stimulation with an obstacle. We were interested in several questions. Did participants extract laws of co-variation between their movements and resulting stimulation? Did they deduce the existence of a perceptual space originating from this coupling? Did they individuate objects that caused the sensations? Whatever the experimental conditions, participants were able to establish that there was a link between their movements and the resulting auditory stimulation. Detection of the existence of a coupling was more frequent than the inferences of distal space and object.

Thromboprophylaxis using a low molecular weight heparin delays fracture repair

Low molecular weight heparins are significantly superior to unfractionated heparin or warfarin in the prevention of thromboembolic episodes associated with orthopaedic surgery. Therapeutic doses of heparin and warfarin have been shown to delay bone repair in a rabbit model. The current study investigated the effect of prophylactic administration of a low molecular weight heparin, enoxaparin, on the healing of a closed rabbit rib fracture. Fracture healing was assessed using histomorphometric, histologic, and immunohistochemical methods at 3, 7, and 14 days, and biomechanical testing with torsional loading was assessed after 21 days. Bone repair was significantly attenuated at all times in animals receiving subcutaneous enoxaparin compared with that of the control animals. Numerous putative mechanisms for this phenomenon are discussed, and additional studies are proposed to elucidate the effects of this pharmacologically diverse group of compounds on all aspects of bone physiology and repair.