Supervised representation learning based on various levels of pediatric radiographic views for transfer learning

Transfer learning plays a pivotal role in addressing the paucity of data, expediting training processes, and enhancing model performance. Nonetheless, the prevailing practice of transfer learning predominantly relies on pre-trained models designed for the natural image domain, which may not be well-suited for the medical image domain in grayscale. Recognizing the significance of leveraging transfer learning in medical research, we undertook the construction of class-balanced pediatric radiograph datasets collectively referred to as PedXnets, grounded in radiographic views using the pediatric radiographs collected over 24 years at Asan Medical Center. For PedXnets pre-training, approximately 70,000 X-ray images were utilized. Three different pre-training weights of PedXnet were constructed using Inception V3 for various radiation perspective classifications: Model-PedXnet-7C, Model-PedXnet-30C, and Model-PedXnet-68C. We validated the transferability and positive effects of transfer learning of PedXnets through pediatric downstream tasks including fracture classification and bone age assessment (BAA). The evaluation of transfer learning effects through classification and regression metrics showed superior performance of Model-PedXnets in quantitative assessments. Additionally, visual analyses confirmed that the Model-PedXnets were more focused on meaningful regions of interest.

Updated Primer on Generative Artificial Intelligence and Large Language Models in Medical Imaging for Medical Professionals

The emergence of Chat Generative Pre-trained Transformer (ChatGPT), a chatbot developed by OpenAI, has garnered interest in the application of generative artificial intelligence (AI) models in the medical field. This review summarizes different generative AI models and their potential applications in the field of medicine and explores the evolving landscape of Generative Adversarial Networks and diffusion models since the introduction of generative AI models. These models have made valuable contributions to the field of radiology. Furthermore, this review also explores the significance of synthetic data in addressing privacy concerns and augmenting data diversity and quality within the medical domain, in addition to emphasizing the role of inversion in the investigation of generative models and outlining an approach to replicate this process. We provide an overview of Large Language Models, such as GPTs and bidirectional encoder representations (BERTs), that focus on prominent representatives and discuss recent initiatives involving language-vision models in radiology, including innovative large language and vision assistant for biomedicine (LLaVa-Med), to illustrate their practical application. This comprehensive review offers insights into the wide-ranging applications of generative AI models in clinical research and emphasizes their transformative potential.

Utility of cranial MRI in non-traumatic headache patients with prior negative head CT within 1 month

AIM

To investigate the importance of additional cranial magnetic resonance imaging (cMRI) in non-traumatic headache patients with a prior negative head computed tomography (CT) examination within 1 month.

MATERIALS AND METHODS

This retrospective study analysed 162 adult patients with non-traumatic headache who underwent cMRI within 1 month of a negative initial head CT at the emergency department (ED). The diagnostic yield and false-referral rate were analysed according to the revisit duration (early [≤1 week] versus late [>1-4 weeks] revisits), patient care settings (ED versus outpatient clinics [OPC]), and clinical variables. Subsequent patient management change (PMC), such as admission and treatment (AT) or outpatient clinic treatment (OT), were also investigated.

RESULTS

The overall diagnostic yield of cMRI was 17.3% (28/162) and the false-referral rate was 1.2% (2/162). The diagnostic yield of cMRI was significantly different according to the patient care settings (ED, 24.7% [21/85] versus OPC, 9.1% [7/77]; p=0.02). The diagnostic yield was highest in the ED-early-revisit group (25.4% [18/71]), 45% (9/20) in those with systemic signs, and 46.7% (14/30) in those with symptom change. Among patients with positive cMRI findings, 90% (27/30) received AT and 3.3% (1/30) received OT. Among OPC-revisit-negative cMRI patients, PMC occurred in 0% (0/50).

CONCLUSION

The diagnostic yield of cMRI was relatively high for headache patients who revisited the ED earlier, especially in those with systemic signs or symptom change. Most positive cMRI cases experienced PMC. Negative cMRI in OPC-revisit patients might help clarify the benign nature of a condition.

Approximating Intermediate Feature Maps of Self-Supervised Convolution Neural Network to Learn Hard Positive Representations in Chest Radiography

Recent advances in contrastive learning have significantly improved the performance of deep learning models. In contrastive learning of medical images, dealing with positive representation is sometimes difficult because some strong augmentation techniques can disrupt contrastive learning owing to the subtle differences between other standardized CXRs compared to augmented positive pairs; therefore, additional efforts are required. In this study, we propose intermediate feature approximation (IFA) loss, which improves the performance of contrastive convolutional neural networks by focusing more on positive representations of CXRs without additional augmentations. The IFA loss encourages the feature maps of a query image and its positive pair to resemble each other by maximizing the cosine similarity between the intermediate feature outputs of the original data and the positive pairs. Therefore, we used the InfoNCE loss, which is commonly used loss to address negative representations, and the IFA loss, which addresses positive representations, together to improve the contrastive network. We evaluated the performance of the network using various downstream tasks, including classification, object detection, and a generative adversarial network (GAN) inversion task. The downstream task results demonstrated that IFA loss can improve the performance of effectively overcoming data imbalance and data scarcity; furthermore, it can serve as a perceptual loss encoder for GAN inversion. In addition, we have made our model publicly available to facilitate access and encourage further research and collaboration in the field.

Overcoming the Challenges in the Development and Implementation of Artificial Intelligence in Radiology: A Comprehensive Review of Solutions Beyond Supervised Learning

Artificial intelligence (AI) in radiology is a rapidly developing field with several prospective clinical studies demonstrating its benefits in clinical practice. In 2022, the Korean Society of Radiology held a forum to discuss the challenges and drawbacks in AI development and implementation. Various barriers hinder the successful application and widespread adoption of AI in radiology, such as limited annotated data, data privacy and security, data heterogeneity, imbalanced data, model interpretability, overfitting, and integration with clinical workflows. In this review, some of the various possible solutions to these challenges are presented and discussed; these include training with longitudinal and multimodal datasets, dense training with multitask learning and multimodal learning, self-supervised contrastive learning, various image modifications and syntheses using generative models, explainable AI, causal learning, federated learning with large data models, and digital twins.

CheSS: Chest X-Ray Pre-trained Model via Self-supervised Contrastive Learning

Training deep learning models on medical images heavily depends on experts' expensive and laborious manual labels. In addition, these images, labels, and even models themselves are not widely publicly accessible and suffer from various kinds of bias and imbalances. In this paper, chest X-ray pre-trained model via self-supervised contrastive learning (CheSS) was proposed to learn models with various representations in chest radiographs (CXRs). Our contribution is a publicly accessible pretrained model trained with a 4.8-M CXR dataset using self-supervised learning with a contrastive learning and its validation with various kinds of downstream tasks including classification on the 6-class diseases in internal dataset, diseases classification in CheXpert, bone suppression, and nodule generation. When compared to a scratch model, on the 6-class classification test dataset, we achieved 28.5% increase in accuracy. On the CheXpert dataset, we achieved 1.3% increase in mean area under the receiver operating characteristic curve on the full dataset and 11.4% increase only using 1% data in stress test manner. On bone suppression with perceptual loss, we achieved improvement in peak signal to noise ratio from 34.99 to 37.77, structural similarity index measure from 0.976 to 0.977, and root-square-mean error from 4.410 to 3.301 when compared to ImageNet pretrained model. Finally, on nodule generation, we achieved improvement in Fréchet inception distance from 24.06 to 17.07. Our study showed the decent transferability of CheSS weights. CheSS weights can help researchers overcome data imbalance, data shortage, and inaccessibility of medical image datasets. CheSS weight is available at https://github.com/mi2rl/CheSS .

Screening of adolescent idiopathic scoliosis using generative adversarial network (GAN) inversion method in chest radiographs

OBJECTIVE

Conventional computer-aided diagnosis using convolutional neural networks (CNN) has limitations in detecting sensitive changes and determining accurate decision boundaries in spectral and structural diseases such as scoliosis. We devised a new method to detect and diagnose adolescent idiopathic scoliosis in chest X-rays (CXRs) employing the latent space's discriminative ability in the generative adversarial network (GAN) and a simple multi-layer perceptron (MLP) to screen adolescent idiopathic scoliosis CXRs.

MATERIALS AND METHODS

Our model was trained and validated in a two-step manner. First, we trained a GAN using CXRs with various scoliosis severities and utilized the trained network as a feature extractor using the GAN inversion method. Second, we classified each vector from the latent space using a simple MLP.

RESULTS

The 2-layer MLP exhibited the best classification in the ablation study. With this model, the area under the receiver operating characteristic (AUROC) curves were 0.850 in the internal and 0.847 in the external datasets. Furthermore, when the sensitivity was fixed at 0.9, the model's specificity was 0.697 in the internal and 0.646 in the external datasets.

CONCLUSION

We developed a classifier for Adolescent idiopathic scoliosis (AIS) through generative representation learning. Our model shows good AUROC under screening chest radiographs in both the internal and external datasets. Our model has learned the spectral severity of AIS, enabling it to generate normal images even when trained solely on scoliosis radiographs.

Emergency triage of brain computed tomography via anomaly detection with a deep generative model

Triage is essential for the early diagnosis and reporting of neurologic emergencies. Herein, we report the development of an anomaly detection algorithm (ADA) with a deep generative model trained on brain computed tomography (CT) images of healthy individuals that reprioritizes radiology worklists and provides lesion attention maps for brain CT images with critical findings. In the internal and external validation datasets, the ADA achieved area under the curve values (95% confidence interval) of 0.85 (0.81–0.89) and 0.87 (0.85–0.89), respectively, for detecting emergency cases. In a clinical simulation test of an emergency cohort, the median wait time was significantly shorter post-ADA triage than pre-ADA triage by 294 s (422.5 s [interquartile range, IQR 299] to 70.5 s [IQR 168]), and the median radiology report turnaround time was significantly faster post-ADA triage than pre-ADA triage by 297.5 s (445.0 s [IQR 298] to 88.5 s [IQR 179]) (all p < 0.001).

Diagnosis of Scoliosis Using Chest Radiographs with a Semi-Supervised Generative Adversarial Network

Purpose

To develop and validate a deep learning-based screening tool for the early diagnosis of scoliosis using chest radiographs with a semi-supervised generative adversarial network (GAN).

Materials and Methods

Using a semi-supervised learning framework with a GAN, a screening tool for diagnosing scoliosis was developed and validated through the chest PA radiographs of patients at two different tertiary hospitals. Our proposed method used training GAN with mild to severe scoliosis only in a semi-supervised manner, as an upstream task to learn scoliosis representations and a downstream task to perform simple classification for differentiating between normal and scoliosis states sensitively.

Results

The area under the receiver operating characteristic curve, negative predictive value (NPV), positive predictive value, sensitivity, and specificity were 0.856, 0.950, 0.579, 0.985, and 0.285, respectively.

Conclusion

Our deep learning-based artificial intelligence software in a semi-supervised manner achieved excellent performance in diagnosing scoliosis using the chest PA radiographs of young individuals; thus, it could be used as a screening tool with high NPV and sensitivity and reduce the burden on radiologists for diagnosing scoliosis through health screening chest radiographs.

Clinical Impact of a Quality Improvement Program Including Dedicated Emergency Radiology Personnel on Emergency Surgical Management: A Propensity Score-Matching Study

Objective

To investigate the clinical impact of a quality improvement program including dedicated emergency radiology personnel (QIP-DERP) on the management of emergency surgical patients in the emergency department (ED).

Materials and Methods

This retrospective study identified all adult patients (n = 3667) who underwent preoperative body CT, for which written radiology reports were generated, and who subsequently underwent non-elective surgery between 2007 and 2018 in the ED of a single urban academic tertiary medical institution. The study cohort was divided into periods before and after the initiation of QIP-DERP. We matched the control group patients (i.e., before QIP-DERP) to the QIP-DERP group patients using propensity score (PS), with a 1:2 matching ratio for the main analysis and a 1:1 ratio for sub-analyses separately for daytime (8:00 AM to 5:00 PM on weekdays) and after-hours. The primary outcome was timing of emergency surgery (TES), which was defined as the time from ED arrival to surgical intervention. The secondary outcomes included ED length of stay (LOS) and intensive care unit (ICU) admission rate.

Results

According to the PS-matched analysis, compared with the control group, QIP-DERP significantly decreased the median TES from 16.7 hours (interquartile range, 9.4–27.5 hours) to 11.6 hours (6.6–21.9 hours) (p < 0.001) and the ICU admission rate from 33.3% (205/616) to 23.9% (295/1232) (p < 0.001). During after-hours, the QIP-DERP significantly reduced median TES from 19.9 hours (12.5–30.1 hours) to 9.6 hours (5.7–19.1 hours) (p < 0.001), median ED LOS from 9.1 hours (5.6–16.5 hours) to 6.7 hours (4.9–11.3 hours) (p < 0.001), and ICU admission rate from 35.5% (108/304) to 22.0% (67/304) (p < 0.001).

Conclusion

QIP-DERP implementation improved the quality of emergency surgical management in the ED by reducing TES, ED LOS, and ICU admission rate, particularly during after-hours.

Patient recalls associated with resident-to-attending radiology report discrepancies: predictive factors for risky discrepancies

BACKGROUND

This study aimed to identify predictive factors for risky discrepancies in the emergency department (ED) by analyzing patient recalls associated with resident-to-attending radiology report discrepancies (RRDs).

RESULTS

This retrospective study analyzed 759 RRDs in computed tomography (CT) and magnetic resonance imaging and their outcomes from 2013 to 2021. After excluding 73 patients lost to follow-up, we included 686 records in the final analysis. Risky discrepancies were defined as RRDs resulting in (1) inpatient management (hospitalization) and (2) adverse outcomes (delayed operations, 30-day in-hospital mortality, or intensive care unit admission). Predictors of risky discrepancies were assessed using multivariable logistic regression analysis. The overall RRD rate was 0.4% (759 of 171,419). Of 686 eligible patients, 21.4% (147 of 686) received inpatient management, and 6.0% (41 of 686) experienced adverse outcomes. RRDs with neurological diseases were associated with the highest ED revisit rate (79.4%, 81 of 102) but not with risky RRDs. Predictive factors of inpatient management were critical finding (odds ratio [OR], 5.60; p < 0.001), CT examination (OR, 3.93; p = 0.01), digestive diseases (OR, 2.54; p < 0.001), and late finalized report (OR, 1.65; p = 0.02). Digestive diseases (OR, 6.14; p = 0.006) were identified as the only significant predictor of adverse outcomes.

CONCLUSIONS

Risky RRDs were associated with several factors, including CT examination, digestive diseases, and late finalized reports, as well as critical image findings. This knowledge could aid in determining the priority of discrepancies for the appropriate management of RRDs.

Bone suppression on pediatric chest radiographs via a deep learning-based cascade model

BACKGROUND AND OBJECTIVE

Bone suppression images (BSIs) of chest radiographs (CXRs) have been proven to improve diagnosis of pulmonary diseases. To acquire BSIs, dual-energy subtraction (DES) or a deep-learning-based model trained with DES-based BSIs have been used. However, neither technique could be applied to pediatric patients owing to the harmful effects of DES. In this study, we developed a novel method for bone suppression in pediatric CXRs.

METHODS

First, a model using digitally reconstructed radiographs (DRRs) of adults, which were used to generate pseudo-CXRs from computed tomography images, was developed by training a 2-channel contrastive-unpaired-image-translation network. Second, this model was applied to 129 pediatric DRRs to generate the paired training data of pseudo-pediatric CXRs. Finally, by training a U-Net with these paired data, a bone suppression model for pediatric CXRs was developed.

RESULTS

The evaluation metrics were peak signal to noise ratio, root mean absolute error and structural similarity index measure at soft-tissue and bone region of the lung. In addition, an expert radiologist scored the effectiveness of BSIs on a scale of 1-5. The obtained result of 3.31 ± 0.48 indicates that the BSIs show homogeneous bone removal despite subtle residual bone shadow.

CONCLUSION

Our method shows that the pixel intensity at soft-tissue regions was preserved, and bones were well subtracted; this can be useful for detecting early pulmonary disease in pediatric CXRs.

Impact of diagnostic errors on adverse outcomes: learning from emergency department revisits with repeat CT or MRI

Background

To investigate diagnostic errors and their association with adverse outcomes (AOs) during patient revisits with repeat imaging (RVRIs) in the emergency department (ED).

Results

Diagnostic errors stemming from index imaging studies and AOs within 30 days in 1054 RVRIs (≤ 7 days) from 2005 to 2015 were retrospectively analyzed according to revisit timing (early [≤ 72 h] or late [> 72 h to 7 days] RVRIs). Risk factors for AOs were assessed using multivariable logistic analysis. The AO rate in the diagnostic error group was significantly higher than that in the non-error group (33.3% [77 of 231] vs. 14.8% [122 of 823], p < .001). The AO rate was the highest in early revisits within 72 h if diagnostic errors occurred (36.2%, 54 of 149). The most common diseases associated with diagnostic errors were digestive diseases in the radiologic misdiagnosis category (47.5%, 28 of 59) and neurologic diseases in the delayed radiology reporting time (46.8%, 29 of 62) and clinician error (27.3%, 30 of 110) categories. In the matched set of the AO and non-AO groups, multivariable logistic regression analysis revealed that the following diagnostic errors contributed to AO occurrence: radiologic error (odds ratio [OR] 3.56; p < .001) in total RVRIs, radiologic error (OR 3.70; p = .001) and clinician error (OR 4.82; p = .03) in early RVRIs, and radiologic error (OR 3.36; p = .02) in late RVRIs.

Conclusion

Diagnostic errors in index imaging studies are strongly associated with high AO rates in RVRIs in the ED.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-021-01108-0.

Realistic High-Resolution Body Computed Tomography Image Synthesis by Using Progressive Growing Generative Adversarial Network: Visual Turing Test

BACKGROUND

Generative adversarial network (GAN)-based synthetic images can be viable solutions to current supervised deep learning challenges. However, generating highly realistic images is a prerequisite for these approaches.

OBJECTIVE

The aim of this study was to investigate and validate the unsupervised synthesis of highly realistic body computed tomography (CT) images by using a progressive growing GAN (PGGAN) trained to learn the probability distribution of normal data.

METHODS

We trained the PGGAN by using 11,755 body CT scans. Ten radiologists (4 radiologists with <5 years of experience [Group I], 4 radiologists with 5-10 years of experience [Group II], and 2 radiologists with >10 years of experience [Group III]) evaluated the results in a binary approach by using an independent validation set of 300 images (150 real and 150 synthetic) to judge the authenticity of each image.

RESULTS

The mean accuracy of the 10 readers in the entire image set was higher than random guessing (1781/3000, 59.4% vs 1500/3000, 50.0%, respectively; P<.001). However, in terms of identifying synthetic images as fake, there was no significant difference in the specificity between the visual Turing test and random guessing (779/1500, 51.9% vs 750/1500, 50.0%, respectively; P=.29). The accuracy between the 3 reader groups with different experience levels was not significantly different (Group I, 696/1200, 58.0%; Group II, 726/1200, 60.5%; and Group III, 359/600, 59.8%; P=.36). Interreader agreements were poor (κ=0.11) for the entire image set. In subgroup analysis, the discrepancies between real and synthetic CT images occurred mainly in the thoracoabdominal junction and in the anatomical details.

CONCLUSIONS

The GAN can synthesize highly realistic high-resolution body CT images that are indistinguishable from real images; however, it has limitations in generating body images of the thoracoabdominal junction and lacks accuracy in the anatomical details.

Value of bone suppression software in chest radiographs for improving image quality and reducing radiation dose

OBJECTIVES

To compare image quality and radiation dose between dual-energy subtraction (DES)-based bone suppression images (D-BSIs) and software-based bone suppression images (S-BSIs).

METHODS

Chest radiographs (CXRs) of forty adult patients were obtained with the two X-ray devices, one with DES and one with bone suppression software. Three image quality metrics (relative mean absolute error (RMAE), peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM)) between original CXR and BSI for each of D-BSI and S-SBI groups were calculated for each bone and soft tissue areas. Two readers rated the visual image quality for original CXR and BSI for each of D-BSI and S-SBI groups. The dose area product (DAP) values were recorded. Paired t test was used to compare the image quality and DAP values between D-BSI and S-BSI groups.

RESULTS

In bone areas, S-BSIs had better SSIM values than D-BSI (94.57 vs. 87.77) but worse RMAE and PSNR values (0.50 vs. 0.20; 20.93 vs. 34.37) (all p < 0.001). In soft tissue areas, S-BSIs had better SSIM values than D-BSI (97.56 vs. 91.42) but similar RMAE and PSNR values (0.29 vs. 0.27; 31.35 vs. 29.87) (all p < 0.001). Both readers gave S-BSIs significantly higher image quality scores than D-BSI (p < 0.001). The mean DAP in software-related images (0.98 dGy·cm²) was significantly lower than that in the DES-related images (1.48 dGy·cm²) (p < 0.001).

CONCLUSION

Bone suppression software significantly improved the image quality of bone suppression images with a relatively lower radiation dose, compared with dual-energy subtraction technique.

KEY POINTS

• Bone suppression software preserves structure similarity of soft tissues better than dual-energy subtraction technique in bone suppression images. • Bone suppression software achieves superior image quality for lung lesions than dual-energy subtraction technique in bone suppression images. • Bone suppression software can decrease the radiation dose over the hardware-based image processing technique.

Assessment of naive indolent lymphoma using whole-body diffusion-weighted imaging and T2-weighted MRI: results of a prospective study in 30 patients

Background

We prospectively evaluated the diagnostic utility of whole-body diffusion-weighted imaging with background body signal suppression and T2-weighted short-tau inversion recovery MRI (WB-DWIBS/STIR) for the pretherapeutic staging of indolent lymphoma in 30 patients.

Methods

This prospective study included 30 treatment-naive patients with indolent lymphomas who underwent WB-DWIBS/STIR and conventional imaging workup plus biopsy. The pretherapeutic staging agreement, sensitivity, and specificity of WB-DWIBS/STIR were investigated with reference to the multimodality and multidisciplinary consensus review for nodal and extranodal lesions excluding bone marrow.

Results

In the pretherapeutic staging, WB-DWIBS/STIR showed very good agreement (κ = 0.96; confidence interval [CI], 0.88–1.00), high sensitivity (93.4–95.1%), and high specificity (99.0–99.4%) for the whole-body regions. These results were similar to those of ¹⁸F-FDG-PET/CT, except for the sensitivity for extranodal lesions. For extranodal lesions, WB-DWIBS/STIR showed higher sensitivity compared to ¹⁸F-FDG-PET/CT for the whole-body regions (94.9–96.8% vs. 79.6–86.3%, P = 0.058).

Conclusion

WB-DWIBS/STIR is an effective modality for the pretherapeutic staging of indolent lymphoma, and it has benefits when evaluating extranodal lesions, compared with ¹⁸F-FDG-PET/CT.

Ischemic colitis after enema administration: Incidence, timing, and clinical features

BACKGROUND

Enema administration is a common procedure in the emergency department (ED). However, several published case reports on enema-related ischemic colitis (IC) have raised the concerns regarding the safety of enema agents. Nevertheless, information on its true incidence and characteristics are still lacking.

AIM

To investigate the incidence, timing, and risk factors of IC in patients receiving enema.

METHODS

We consecutively collected the data of all adult patients receiving various enema administrations in the ED from January 2010 to December 2018 and identified patients confirmed with IC following enema. Of 8320 patients receiving glycerin enema, 19 diagnosed of IC were compared with an age-matched control group without IC.

RESULTS

The incidence of IC was 0.23% among 8320 patients receiving glycerin enema; however, there was no occurrence of IC among those who used other enema agents. The mean age ± standard deviation (SD) of patients with glycerin enema-related IC was 70.2 ± 11.7. The mean time interval ± SD from glycerin enema administration to IC occurrence was 5.5 h ± 3.9 h (range 1-15 h). Of the 19 glycerin enema-related IC cases, 15 (79.0%) were diagnosed within 8 h. The independent risk factors for glycerin-related IC were the constipation score [Odds ratio (OR), 2.0; 95% confidence interval (CI): 1.1-3.5, P = 0.017] and leukocytosis (OR, 4.5; 95%CI: 1.4-14.7, P = 0.012).

CONCLUSION

The incidence of glycerin enema-related IC was 0.23% and occurred mostly in the elderly in the early period following enema administration. Glycerin enema-related IC was associated with the constipation score and leukocytosis.

Assessment of pulmonary arterial enhancement on CT pulmonary angiography using a leg vein for contrast media administration

The purpose of our study was to compare pulmonary artery (PA) enhancement according to venous routes of contrast media (CM) administration in patients who underwent CT pulmonary angiography (CTPA) in the emergency department (ED).This retrospective study reviewed the CTPAs of 24 patients who administered CM via leg veins (group A) and 72 patients via arm veins (group B) with age and gender matching at a ratio of 1:3. Clinical data, aorta attenuation (Aoatten), and PA attenuation (PAatten) were compared between group A and B. Each group was subcategorized into diagnostic and nondiagnostic CTPA subgroups, with a threshold of 250 HU at the PA. Then, clinical data, rates of pulmonary embolism (PE), and right ventricle (RV) strain were compared. In group A, the relationship between the narrowest suprahepatic IVC area (IVCarea) and the attenuation ratio of the RV to the intrahepatic IVC (RV/IVCatten) was evaluated.Aoatten (236.6 HU vs 293.1 HU, P < .001) and PAatten (266.7 HU vs 321.4 HU, P = .026) were significantly lower in group A than in group B. The proportion of nondiagnostic CTPA was significantly higher in group A than in group B (58.3% vs 19.4%, P = .001). In the subgroup analysis in of group A, patients with a nondiagnostic CTPA were significantly younger (55.3 years vs 68.6 years, P = .026) and showed a significantly lower incidence rate of PE (14% vs 70%, P = .01) than patients with a diagnostic CTPA. However, the radiological diagnostic rate of RV strain was comparable between patients with nondiagnostic and diagnostic CTPA. In group A, IVCarea and RV/IVCatten were positively correlated, with a correlation coefficient of 0.430 (P < .036).In conclusion, administration of CM through the leg veins increases the nondiagnostic CTPA rate, reducing the detection rate of PE. When CM is injected via the leg veins, the degree of PA enhancement is related with to the diameter of the suprahepatic IVC; therefore, adjustment of respiratory maneuvers may be needed to promote IVC flow into the right cardiac chamber, and to improve PA enhancement.

Appendiceal location analysis and review of the misdiagnosis rate of appendicitis associated with deep pelvic cecum on multidetector computed tomography

OBJECTIVE

To investigate appendiceal location and misdiagnosis rate of appendicitis associated with deep pelvic cecum on multidetector computed tomography (MDCT).

MATERIALS AND METHODS

Among 1107 appendicitis cases, 25 patients with deep pelvic cecum and 75 patients with conventional cecum on MDCT were retrospectively selected for analysis of appendiceal locations and preoperative misdiagnosis rate.

RESULTS

The major appendiceal direction in deep pelvic cecum group was ascending (84.0%). The misdiagnosis rates of appendicitis in deep pelvic and conventional cecum groups were 16% and 5.3%.

CONCLUSION

A deep pelvic cecum may cause misdiagnosis of appendicitis. The appendix associated with deep pelvic cecum mainly demonstrates right ascending direction.

Differentiation of small (≤2 cm) hepatocellular carcinomas from small benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted magnetic resonance images

OBJECTIVE

To identify imaging characteristics that differentiate small (≤2 cm) HCCs from small (≤2 cm) benign nodules in cirrhotic liver on gadoxetic acid-enhanced and diffusion-weighted (DW) magnetic resonance (MR) images.

MATERIALS AND METHODS

On gadoxetic acid-enhanced and DW MR images, we analysed signal intensity of 222 small HCCs and 61 benign nodules (diameter, 0.5-2 cm) at each sequence and rim enhancement during portal or equilibrium phases. Univariate and multivariate logistic regression analyses identified predictors of HCC. Combinations of significant MR findings in multivariate analysis were compared with American Association for the Study of Liver Disease (AASLD) practice guidelines.

RESULTS

In multivariate analysis, arterial enhancement (adjusted odds ratio [aOR], 8.6), T2 hyperintensity (aOR, 5.8), and hyperintensity on DW images (aOR, 3.8) were significant for differentiating small HCCs from benign nodules (p ≤ 0.004). When two or all three findings were applied as diagnostic criteria for differentiating small HCCs from benign nodules, sensitivity and accuracy were significantly higher compared with AASLD practice guidelines (91% vs. 78% and 89% vs. 81%, respectively; each p < 0.0001).

CONCLUSION

On gadoxetic acid-enhanced MR imaging, arterial enhancement and hyperintensity on T2-weighted and DW MR images are helpful for differentiating small HCCs from benign nodules in liver cirrhosis.

Iohexol versus diatrizoate for fecal/fluid tagging during CT colonography performed with cathartic preparation: comparison of examination quality

OBJECTIVE

We aimed to compare iohexol vs. diatrizoate as fecal/fluid tagging agents for computed tomography colonography (CTC) regarding examination quality.

METHODS

Forty prospective patients (M:F = 23:17; 63 ± 11.6 years) received CTC using 50 mL (350 mgI/mL) oral iohexol for tagging. Forty other indication-matched, age-matched, and sex-matched patients who underwent CTC using 100 mL diatrizoate for tagging and otherwise the same technique, were retrospectively identified. Two groups were compared regarding overall examination quality, per-patient and per-segment scores of colonic bubbles (0 [no bubbles] to 5 [the largest amount]), and the volume, attenuation, and homogeneity (untagged, layered, and homogeneous) of the residual colonic fluid.

RESULTS

The iohexol group demonstrated a greater amount of colonic bubbles than the diatrizoate group: mean per-patient scores ± SD of 1.2 ± 0.8 vs. 0.7 ± 0.6, respectively (p = 0.003); and rates of segments showing ≥ grade 3 bubbles of 12.9 % (85/659) vs. 1.6 % (11/695), respectively (p = 0.001). Residual colonic fluid amount standardized to the colonic volume did not significantly differ: 7.2 % ± 4.2 vs. 7.8 % ± 3.7, respectively (p = 0.544). Tagged fluid attenuation was mostly comparable between groups and the fluid was homogeneously tagged in 98.7 % (224/227) vs. 99.5 % (218/219) segments, respectively (p = 0.344). Iohexol caused more colonic bubbles when used during cathartic CTC. Otherwise, examination quality was similarly adequate with both iohexol and diatrizoate.

KEY POINTS

• When used for tagging, iohexol caused significantly more colonic bubbles than diatrizoate. • The residual colonic fluid amount did not significantly differ between iohexol and diatrizoate. • The quality of fluid tagging was similarly adequate in both iohexol and diatrizoate.

Primary perivascular epitheloid cell tumour (PEComa) of the liver: case report and review of the literature

PURPOSE

Perivascular epitheloid cell tumour [PEComa] is a rare neoplasm entity, characterized by perivascular epitheloid cells with a coexpression of smooth muscle and melanocytic markers. PEComas are found in a variety of localizations, though lesions within the liver are still scarcely found. Although the majority of these tumours are recognized as benign, there are some reports about advanced and aggressive tumours even with fatal outcome. By means of this case report and literary review including other 21 published cases, potential treatment modalities concerning clinical diagnostics, therapy and the follow-up care should be discussed.

METHODS

The following report presents the case of a 53-year old woman with a known liver lesion, since four years under regularly sonographic controls. Finally, after a haemorrhage episode, the lesion was resected and the diagnosis found. For the literary review a systematic search for case reports published between January 1, 1999 and May 1, 2012 was performed on Pubmed.

RESULTS

The only way, till now, of confirming the diagnosis is through immunohistochemical examinations. The already published Malignancy criteria by Folpe et al. must be taken carefully in question, as there are cases of malignant behaviour, that do not exactly coincide with these.

CONCLUSION

Primary PEComa of the liver must be treated as potential malignant and therefore a close follow-up is demanded.

LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast and colorectal cancer

Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, using both loss of heterozygosity analysis and customized microarray comparative genomic hybridization. LARG (leukemia-associated Rho guanine-nucleotide exchange factor) (also called ARHGEF12), identified from the analysed region, is frequently underexpressed in breast and colorectal carcinomas with a reduced expression observed in all breast cancer cell lines (n=11), in 12 of 38 (32%) primary breast cancers, 5 of 10 (50%) colorectal cell lines and in 20 of 37 (54%) primary colorectal cancers. Underexpression of the LARG transcript was significantly associated with genomic loss (P=0.00334). Hypermethylation of the LARG promoter was not detected in either breast or colorectal cancer, and treatment of four breast and four colorectal cancer cell lines with 5-aza-2'-deoxycytidine and/or trichostatin A did not result in a reactivation of LARG. Enforced expression of LARG in breast and colorectal cancer cells by stable transfection resulted in reduced cell proliferation and colony formation, as well as in a markedly slower cell migration rate in colorectal cancer cells, providing functional evidence for LARG as a candidate tumor suppressor gene.

MRSA breast abscesses in postpartum women

BACKGROUND

Infections caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) are being increasingly observed in patients who lack traditional risk factors. While mastitis and breast abscesses are commonly encountered in post-natal women, CA-MRSA breast infections have rarely been reported.

MATERIALS AND METHODS

We reviewed 15 postpartum women with methicillin-resistant Staphylococcus aureus (MRSA) breast abscesses observed in our unit from June 2005 to April 2007. Ultrasonographic examination was performed in all cases. MRSA infection was diagnosed on microbiological analysis cultured from the abscesses of these patients.

RESULTS

The median age of the patients was 31.5 years. The majority of the patients were primiparae (80%). Only one patient was immunocompromised. None of the patients had history of previous breast infection and none developed recurrence. Eleven patients (73.3%) underwent aspiration of pus and four patients (26.7%) underwent incision and drainage. All the cultures were sensitive to co-trimoxazole and vancomycin. Eight (53.3%) of the cultures were also sensitive to erythromycin.

CONCLUSION

CA-MRSA is an emerging problem in our obstetric population. CA-MRSA breast infections are clinically responsive to common oral antibiotics such as co-trimoxazole and erythromycin. A high index of suspicion is essential to avoid delay in the clinical response to empirical beta-lactams as these patients may benefit from an early change of antibiotics.

Acoustic diagnosis of aortic stenosis

BACKGROUND AND AIM OF THE STUDY

Phonocardiography is a promising non-invasive diagnostic tool for the assessment of aortic stenosis (AS), and time-frequency representation is a potential tool to extract information from the phonocardiogram (PCG) signal. The study aim was to develop an acoustical method to predict the severity of AS.

METHODS

Normalized continuous wavelet transform (NCWT) and fast Fourier Transform (FFT) were used to perform a spectral analysis of the PCG signal. A multi-peak detection algorithm was developed to determine the dominant frequency (DF) of systolic murmurs (SM). The spectral ratio of the SM, integration of the NCWT of SM (SI), and combined information of SM and second heart sound, were also calculated.

RESULTS

The DF correlated best with the hemodynamic data: r = -0.72 with aortic valve (AV) area; r = 0.63 with maximal blood velocity through the AV; and r = 0.57 with mean pressure gradient across the AV. Based on DF and SI data, the study subjects (n = 59) were classified into three categories: severe AS; moderate AS; and other cases. The acoustical and echo classifications were in agreement in 50 subjects (85%).

CONCLUSION

The acoustical method developed cannot predict accurately the severity of AS, but is valuable when conducting a screening classification before an invasive method is used.

Inhibition of Bcl10-mediated activation of NF-kappa B by BinCARD, a Bcl10-interacting CARD protein

We have identified a novel CARD-containing protein from EST database. BinCARD (Bcl10-interacting protein with CARD). BinCARD was ubiquitously expressed. Co-immunoprecipitation, In vitro binding, mammalian two-hybrid, and immunostaining assays revealed that BinCARD interacted with Bcl10 through CARD. BinCARD potently suppressed NF-kappa B activation induced by Bcl10 and decreased the amounts of phosphorylated Bcl10. Mutations at the residue Leu17 or Leu65, which is highly conserved in CARD, abolished the inhibitory effects of BinCARD on both Bcl10-induced activation of NF-kappa B and phosphorylation of Bcl10. Further, expression of BinCARD inhibited Bcl10 phosphorylation induced by T cell activation signal. These results suggest that BinCARD interacts with Bcl10 to inhibit Bcl10-mediated activation of NF-kappa B and to suppress Bcl10 phosphorylation.

Founder mutation in the BRCA1 gene in Malay breast cancer patients from Singapore

The mutation spectrum of the BRCA1 gene among ethnic groups from Asia has not been well studied. We investigated the frequency of mutations in the BRCA1 gene among Malay breast cancer patients from Singapore, independent of family history. By using the protein truncation test (PTT) and direct sequencing, BRCA1 mutations were detected in 6 of 49 (12.2%) unrelated patients. Four novel missense mutations in exon 11, T557A (1788A>G), T582A (1863A>G), N656S (2086A>G) and P684S (2169C>T) were identified in one patient. Two patients had missense mutations in exon 23, V1809A (5545T>C), which has been previously detected in individuals from Central and Eastern Europe. Three unrelated patients had the deleterious 2846insA frameshift mutation in exon 11. Methylation specific PCR (MSP) of the promoter region of the BRCA1 gene detected hypermethylation of tumor DNA in an additional 2 patients. Haplotype analysis using the microsatellite markers D17S855, D17S1323 and D17S1325 revealed a common haplotype for the three unrelated patients and their three relatives with the 2846insA mutation. These findings strongly suggest that the 2846insA mutation, the most common deleterious mutation in this study, may possibly be a founder mutation in breast cancer patients of Malay ethnic background.

Well-differentiated thyroid carcinoma: factors predicting recurrence and survival

AIMS

1) Determine the patient and tumour characteristics for well-differentiated thyroid carcinoma--towards developing a unique risk classification for our largely Chinese population. 2) Assess extent of thyroid surgery required. 3) Document prognostic value of UICC and AMES classification.

METHODS

Retrospective review of 175 patients treated for primary thyroid epithelial malignancy by the Department of General Surgery at the Singapore General Hospital.

RESULTS

There were 78% papillary carcinomas (PC) and 19% follicular carcinomas (FC). Female: male ratio was 3:1. Patient distribution in the UICC stages I, II, III, IV is respectively 56, 11, 31 and 2%. Twenty-six percent had hemithyroidectomy, and 74% total thyroidectomy. Neck dissections were required in 6% of FC compared to 34% of PC. Mean follow-up was 40 months. Extent of surgery did not affect PC/FC survival nor recurrence rates (p=0.53 and 0.06 respectively). Recurrences occurred in 15% FC and 9% PC. Death occurred in one FC and two PC. Survival correlated with UICC stage I/II and stage III/IV groups (p=0.04), and recurrence correlated with AMES High and Low Risk groups (p=0.004). No statistically significant difference was shown for survival between PC and FC or AMES groups and recurrence between PC and FC or UICC groups.

CONCLUSIONS

Extent of thyroid surgery does not significantly affect local recurrences of PC/FC. The characterisation of thyroid carcinoma here is an important step towards developing a risk classification unique to our largely Chinese population.

Calpain-dependent cleavage of cain/cabin1 activates calcineurin to mediate calcium-triggered cell death

Cain/cabin1 is an endogenous inhibitor of calcineurin (Cn), a calcium-dependent serine/threonine phosphatase involved in various cellular functions including apoptosis. We show here that during apoptosis cain/cabin1 is cleaved by calpain at the carboxyl terminus to generate a cleavage product with a molecular mass of 32 kDa as a necessary step leading to Cn-mediated cell death. Mouse cain/cabin1 was identified from a thymus cDNA library by an in vitro substrate-screening assay with calpain. Exposure of Jurkat cells to the calcium ionophore, induced cain/cabin1 cleavage and cell death, accompanied by activation of calpain and Cn. The calpain inhibitors, calpeptin and zLLY, suppressed both -induced cain/cabin1 cleavage and Cn activation, indicating that Cn activation and cain/cabin1 cleavage are calpain-dependent. Expression of cain/cabin1 or a catalytically inactive Cn mutant [CnA beta(2)(1-401/H160N)] and treatment with FK506 reduced -induced cell death. In vitro calpain cleavage and immunoprecipitation assays with deletion mutants of cain/cabin1 showed that cleavage occurred in the Cn-binding domain of cain/cabin1, indicating that the cleavage at its C terminus by calpain prevented cain/cabin1 from binding to Cn. In addition, in vitro binding assays showed that cain/cabin1 bound to the Cn B-binding domain of Cn A. Taken together, these results indicate that calpain cleaves the calcineurin-binding domain of cain/cabin1 to activate Cn and elicit calcium-triggered cell death.

Genotoxicity of human breast milk from different countries

Dietary and/or environmental factors appear to play a key role in the international variations that exist in breast cancer incidence. The genotoxicity of breast milk extracts is being examined as a possible indicator of in vivo exposure of mammary epithelial cells to DNA-damaging agents. Breast milk samples were obtained from the UK (n = 32), a high risk country, and from Hong Kong (n = 10), India (n = 20) and Singapore (n = 20), countries of lower breast cancer incidence. The abilities of breast milk extracts to induce DNA damage detected as single-strand breaks (SSBs) in the alkaline Comet assay and to induce micronuclei in MCL-5 cells and mutations in Salmonella typhimurium YG1019 were investigated. In the Comet assay 18 of 32 (56%) UK samples induced significant increases in DNA SSBs compared with 2 of 10 (20%), 5 of 20 (25%) and 8 of 20 (40%) of the samples from Hong Kong, India and Singapore, respectively. The proportion of positive samples was significantly higher in the UK group than in the combined low breast cancer incidence group and significantly higher than in the Indian group (P < 0.05, Fisher's exact test). In the micronucleus assay 9 of 32 (28%) UK samples showed significant activity compared with 0 of 10 (0%), 2 of 20 (10%) and 3 of 20 (15%) of the samples from Hong Kong, India and Singapore, respectively. Extracts of all the aforementioned milk samples were also tested for bacterial mutagenicity. Nine of 32 (28%) UK samples induced significant activity with a dose-response effect. Although activity was detected in samples from the other countries, comparable dose-response data could not be obtained because of a lack of material. This pilot study suggests that genotoxic components occur more frequently in UK breast milk than in milk from some other countries with a lower incidence of cancer. More work is required to confirm these initial findings and to examine their relevance to variations in breast cancer incidence.

FLASH coordinates NF-kappa B activity via TRAF2

FLASH is a protein recently shown to interact with the death effector domain of caspase-8 and is likely to be a component of the death-inducing signaling complex in receptor-mediated apoptosis. Here we show that antisense oligonucleotide-induced inhibition of FLASH expression abolished TNF-alpha-induced activation of NF-kappaB in HEK293 cells, as determined by luciferase reporter gene expression driven by a NF-kappaB responsive promoter. Conversely, overexpression of FLASH dose-dependently activated NF-kappaB, an effect suppressed by dominant negative mutants of TRAF2, NIK, and IKKalpha, and partially by those of TRAF5 and TRAF6. TRAF2 was co-immunoprecipitated with FLASH from the cell extracts of HEK293 cells or HeLa cells stably expressing exogenous FLASH (HeLa/HA-FLASH). Furthermore, serial deletion mapping demonstrated that a domain spanning the residues 856-1191 of FLASH activated NF-kappaB as efficiently as the full-length and could directly bind to TRAF2 in vitro and in the transfected cells. Taken together, these results suggest that FLASH coordinates downstream NF-kappaB activity via a TRAF2-dependent pathway in the TNF-alpha signaling.

A case of alpha-fetoprotein-producing gastric cancer

INTRODUCTION

A case of alpha-fetoprotein (AFP)-producing gastric cancer is described in a 57-year-old Chinese woman.

CLINICAL PICTURE

She presented with bleeding tendency and bone pain, and was found to have haematological evidence of disseminated intravascular coagulation and spinal metastasis. Her tumour markers, including AFP, Ca 19-9 and carcinoembryonic antigen (CEA) were elevated. In view of the elevated tumour markers, there was an exhaustive search for a primary lesion in the gastrointestinal tract, liver and ovaries. There was no radiological evidence to suggest any lesion in the chest, liver or pelvis. Lectin affinity electrophoresis of the AFP showed AFP-L2 and AFP-L3 bands, which are suggestive of a non-hepatoma malignancy.

MANAGEMENT

Gastroscopy showed a gastric ulcer and she developed bleeding after the gastric biopsy which required urgent surgery. Intraoperatively she was found to have carcinomatous peritone and a malignant ulcer in the greater curve of the stomach. Histology confirmed a linitis plastica like adenocarcinoma which stains for AFP.

OUTCOME

She died from multi-organ failure 3 days after surgery.

CONCLUSION

AFP-producing adenocarcinoma of the stomach is not uncommon. Lectin affinity electrophoresis of AFP is helpful in the differentiation between hepatoma and non-hepatoma malignancies.

Reconstitution of caspase-8 sensitizes JB6 cells to TRAIL

TRAIL induces apoptosis in various tumor cells. We report here that caspase-8 is required in TRAIL-induced cell death. Western blot analyses and enzyme assays showed that exposing Jurkat cells to TRAIL resulted in activation of caspases-8 followed by caspase-3 and -9. Acetyl-IETD-fluoromethylketone, a caspase-8 inhibitor, potently suppressed TRAIL-induced cell death compared to acetyl-DEVD-fluoromethylketone and acetyl-LEHD-fluoromethylketone, inhibitors of caspase-3 and caspase-9, respectively. JB6 cells, a caspase-8-deficient Jurkat variant, were completely resistant to TRAIL. However, reconstitution with a caspase-8, but not with caspase-2 or -3, sensitized JB6 cells to subsequent exposure to TRAIL. These results are indicative of the crucial function of caspase-8 in TRAIL-induced apoptosis in Jurkat cells.

Management of intraparotid facial nerve schwannomas

BACKGROUND

The purpose of the present paper was to review the management of intraparotid facial nerve schwannoma so as to discuss its clinical presentation, evaluate the various possible diagnostic investigations, and compare the various surgical options and outcome.

METHODS

Case series was undertaken of five (1.3%) patients with facial nerve schwannoma out of 400 consecutive parotidectomies at Singapore General Hospital.

RESULTS

There were three men and two women with an age range of 29-65 years. Three patients presented with painless parotid lumps while two had painful parotid swellings. None had facial nerve paresis. Only one patient had preoperative diagnosis suspicious of schwannoma by fine-needle aspiration cytology (FNAC). Diagnoses were made intraoperatively. Four patients had excision with cable grafting of the nerve defect. achieving facial nerve grade II-IV (House-Brackmann scale). One patient who underwent enucleation of tumour with nerve preservation achieved grade II.

CONCLUSIONS

Preoperative diagnosis is difficult but it is important for discussion of the extent and options of surgery. Fine-needle aspiration cytology holds promise in making a preoperative diagnosis. Enucleation with nerve preservation where possible seems to offer better facial function whereas nerve excision with cable graft can give satisfactory results.

Epidemiology of Warthin's tumour of the parotid gland in an Asian population

BACKGROUND

Recent studies have documented a number of changing demographic features in the occurrence of Warthin's tumour (adenolymphoma) of the parotid gland. In order to analyse its epidemiology in an Asian population, a retrospective study was performed on all parotid neoplasms (n = 289) operated on between 1988 and 1998.

PATIENTS AND METHODS

A total of 209 consecutive patients were selected for study, 136 with pleomorphic adenomas (one bilateral) and 73 with Warthin's tumours (seven bilateral). Patients were analysed with regard to tumour incidence, age, sex and race. Smoking as an aetiological factor in the development of Warthin's tumour was also studied.

RESULTS

Warthin's tumour formed 25 per cent of parotid tumours and its ratio to pleomorphic adenomas was 1 : 1.9. Multicentricity was found in 14 patients (19 per cent). The male : female ratio for Warthin's tumours was 4.6 : 1. The proportion of Warthin's tumours did not show any increasing trend relative to pleomorphic adenomas. The racial distribution of Warthin's tumours showed an increased incidence among Chinese and a reduced incidence among Malays and Indians. The adjusted odds ratio for sex and age favouring an association between smoking and Warthin's tumour was 39.5 (95 per cent confidence interval 10.5-149. 0; P < 0.0001).

CONCLUSION

The incidence of Warthin's tumour is considerable among Asians although there is still male predominance. There is no rising incidence of Warthin's tumour; the trend parallels the declining smoking rate in the population. The lower incidence among ethnic groups with dark skin seems to suggest concomitant genetic factors other than environmental factors alone in histogenesis. Smokers have a 40-fold greater risk than non-smokers of developing a Warthin's tumour.

Splenic angiosarcoma--an unusual cause of bleeding gastrointestinal tract

Splenic angiosarcoma is a rare malignant vascular tumour with about 100 reported cases to date. The presentation of splenic angiosarcoma is highly variable, frequently causing diagnostic difficulty. It usually presents with splenomegaly, abdominal pain and occasionally with a microangiopathic type of anaemia. Here we report an additional case of primary angiosarcoma of the spleen presenting as a problem of bleeding from the gastrointestinal tract.

Primary reconstruction after extensive chest wall resection

BACKGROUND

Chest wall resection and reconstruction has been proven to be a safe surgical procedure. This is particularly useful for breast cancer patients with chest wall recurrences or for those who first present with locally advanced cancer in the chest wall where there is both a large soft tissue and bony defect that need repair. In addition, many of these patients have had irradiation or chemotherapy, which can significantly impair wound healing.

METHODS

Thirty-four patients underwent chest wall resection and primary reconstruction over an 8-year period.

RESULTS

Twenty-three patients had breast carcinomas and six had breast and chest wall sarcomas. Of the breast carcinoma patients, 12 had local recurrences and 11 presented with locally advanced primary disease. Bony resection of the chest wall was required in 16 (47%) cases. Thirty myocutaneous flaps (18 rectus abdominis, four pectoralis major, eight latissimus dorsi) and three omental flaps were used for reconstruction. One required a deltovertebral skin flap. Skeletal reconstruction was necessary in four cases. All except one (97%) achieved primary wound healing. There was one mortality (3%) and three patients required further surgery for complications that were related to the reconstruction. Post-resection metastases occurred in 13 (42%) patients and only 2 (6%) had local recurrences. The 2-year survival rate was 78% with a mean survival time of 25.5 months.

CONCLUSIONS

Primary reconstruction for curative or palliative purposes is a useful and safe surgical procedure for patients with recurrent or locally advanced chest malignancies after extensive chest wall resection. Pedicled myocutaneous flap is the preferred option for skeletal and soft-tissue coverage.

Flexible endoscopic tracheo-oesophageal puncture under local anaesthetic

Blom-Singer valve prosthesis is an increasingly popular technique for voice rehabilitation in alaryngeal patients. Although primary voice puncture is being practised, the creation of the tracheo-oesophageal fistula is performed in the majority of patients as a secondary procedure. We describe a technique of secondary tracheo-oesophageal puncture using the flexible endoscope which can be performed under local anaesthetic and sedation. The technique overcomes the difficulty of passing a rigid oesophagoscope or forceps to the level of the tracheostome in a scarred and irradiated neck. The new technique also obviates the need for general anaesthesia. We have successfully used the technique in three patients.

Primary reconstruction after chest wall resection in breast cancer

Breast cancer patients with chest wall recurrence or patients with advanced breast cancer pose a difficult challenge to surgeons. Surgical ablation results in not only a large soft tissue defect that needs cover but often, in addition, a significant bony chest wall defect. The majority of these patients would have already received irradiation or chemotherapy or both. Thus, wound healing is significantly impaired. For these reasons, surgery was previously not attractive as an alternative in the palliation of these patients. Over a one-year period, seven breast cancer patients had chest wall resection. Six patients had recurrent tumours and one had advanced primary breast cancer. Two of these patients required only extensive resection of soft tissue of the anterior chest wall. The other five patients required, in addition, resection of the bony chest wall. Myocutaneous flaps were used to repair the surgical defects in six of these patients. Five were rectus abdominis myocutaneous flaps and one a pectoralis major myocutaneous flap. In one patient, a deltovertebral skin flap, which is an axial pattern skin flap was used. Primary wound healing was achieved in five of six patients (83%). One patient died immediately post-operatively, the cause of which is unknown. One of the rectus abdominis flap needed an exploration but was ultimately salvaged. This paper demonstrates the usefulness of the myocutaneous flap in enabling surgery to become a modality for palliation of patients with recurrent and advanced breast cancer.

Dieulafoy's disease: cause of massive upper gastrointestinal haemorrhage in two Asian women

Dieulafoy's disease is a submucous arterial malformation of the stomach, and is a known cause of massive upper gastrointestinal bleeding. To date, 125 cases have been reported in the literature. Fatality is high if the condition remains undiagnosed. Endoscopy is difficult but important in the diagnosis of Dieulafoy's disease. Dieulafoy's disease in two Asian women are reported here. Both required large amount of blood transfusions as the diagnosis was not recognised early. Greater awareness of the condition will enable earlier diagnosis and reduced mortality from this condition.

Oestrogen receptors in well differentiated thyroid cancers

Oestrogen receptor (ER) monoclonal antibody, H222 was used to study ER expression in forty-seven paraffin embedded blocks of well differentiated thyroid cancers. Trypsinisation, DNase I digestion, together with the use of labelled streptavidin biotin immuno-histochemical staining kit were adopted to increase the sensitivity of the immunoreaction. One out of twenty-seven papillary carcinomas and one out of twenty follicular carcinomas were immunoreactive. Thus, 4.3% of the well differentiated thyroid cancers were noted to express ER. The increased incidence and the better prognosis in females with well differentiated thyroid cancers is unlikely to be explained on the presence or absence of ER.

Protective effect of aprotinin on ischemic hepatocellular damage

During hepatic resection, occlusion of the hepatoduodenal ligament has been frequently applied to prevent intraoperative bleeding. To reduce hepatocellular ischemic damage in this procedure, we pretreated animals with Aprotinin. Three hours after an intravenous injection of 40,000 KIU Aprotinin in SD rats, we occluded the afferent hepatic vessels for 50-min and 60-min periods. 92% of occluded animals could sustain life after 60 min. Without premedication only 17 of 25 animals (68%) survived the 50-min occlusion, and 18 of 32 (56%) the 60-min occlusion. Biochemical analysis of sera was carried out 12 hr after a 40- and 60-min occlusion of the hepatoduodenal ligament with Aprotinin pretreatment. Furthermore we induced compensatory cirrhosis by application of CCL4 and biochemical analysis of sera was carried out after a 30-min occlusion. The elevation of SGOT and SGPT values was drastically reduced in the animals with Aprotinin medication in comparison with those without treatment. These observations suggest the highly protective effect of Aprotinin in the case of warm ischemic hepatic damage, especially in the cirrhotic liver. After pretreatment of LEW rats with Aprotinin (40,000 KIU i.v.), we perfused the livers with chilled Ringer solution containing 40,000 KIU Aprotinin/20 ml. We transplanted the livers orthotopically into LEW rats. With the application of Aprotinin liver preservation time increased to 10-15 hr. However, without Aprotinin the livers could be successfully preserved for only 4-6 hr. Our results indicated that premedication with high doses of Aprotinin provided highly protective effects against warm and cold ischemic damage of the liver.

Bacterial and mycotic otological infections in Singapore

This paper describes a microbiological study of 84 young adult men with clinical otitic infections. Gram-negative aerobic bacilli were frequently isolated from these patients diagnosed as having otitis externa or chronic suppurative otitis media, of which Pseudomonas species predominated. Staphylococcus aureus, S. epidermidis and aerobic Corynebacterium species (diphtheroids) were also found. About 40% of ear infections were attributed to otomycoses, chiefly from Aspergillus species and Candida parapsilosis. Antimicrobial susceptibility testing of the bacterial isolates revealed that Pseudomonas species were generally resistant to antibiotics commonly employed in general practice: ampicillin, erythromycin, co-trimoxazole, tetracycline and cephaloridine. However, polymyxin B, gentamicin and neomycin were active against some Pseudomonas isolates. Other Gram-negative bacilli were also mainly sensitive to gentamicin, neomycin as well as co-trimoxazole. Disc diffusion and minimum inhibitory concentration studies demonstrated good activity of ceftazidime, cefoperazone, tobramycin and carbenicillin against strains of Pseudomonas species and other Gram-negative rods. Cefotaxime and cefoxitin were active against Gram-negative bacilli other than Pseudomonas species. Beta-lactamase production did not appear to be the main mechanism of resistance in these community-acquired Gram-negative bacillary isolates. The antimicrobial therapy of otological infections is reviewed.