The role of PET/CT in cervical cancer.

In locally advanced cervical cancer, (18)F-fluorodeoxyglucose (FDG) positron emission tomography - computed tomography (PET/CT) has become important in the initial evaluation of disease extent. It is superior to other imaging modalities for lymph node status and distant metastasis. PET-defined cervical tumor volume predicts progression-free and overall survival. Higher FDG uptake in both primary and regional lymph nodes is strongly predictive of worse outcome. FDG-PET is useful for assessing treatment response 3 months after completing concurrent chemo-radiotherapy (CRT) and predicting long-term survival, and in suspected disease recurrence. In the era of image-guided adaptive radiotherapy, accurately defining disease areas is critical to avoid irradiating normal tissue. Based on additional information provided by FDG-PET, radiation treatment volumes can be modified and higher doses to FDG-positive lymph nodes safely delivered. FDG-PET/CT has been used for image-guided brachytherapy of FDG-avid tumor volume, while respecting low doses to bladder and rectum. Despite survival improvements due to CRT in cervical cancer, disease recurrences continue to be a major problem. Biological rationale exists for combining novel non-cytotoxic agents with CRT, and drugs targeting specific molecular pathways are under clinical development. The integration of these targeted therapies in clinical trials, and the need for accurate predictors of radio-curability is essential. New molecular imaging tracers may help identifying more aggressive tumors. (64)Cu-labeled diacetyl-di(N(4)-methylthiosemicarbazone) is taken up by hypoxic tissues, which may be valuable for prognostication and radiation treatment planning. PET/CT imaging with novel radiopharmaceuticals could further impact cervical cancer treatment as surrogate markers of drug activity at the tumor microenvironment level. The present article reviews the current and emerging role of PET/CT in the management of cervical cancer.

A multi-center study: intra-scan and inter-scan variability of diffusion spectrum imaging.

The objective of this study was to investigate whether it is possible to pool together diffusion spectrum imaging data from four different scanners, located at three different sites. Two of the scanners had identical configuration whereas two did not. To measure the variability, we extracted three scalar maps (ADC, FA and GFA) from the DSI and utilized a region and a tract-based analysis. Additionally, a phantom study was performed to rule out some potential factors arising from the scanner performance in case some systematic bias occurred in the subject study. This work was split into three experiments: intra-scanner reproducibility, reproducibility with twin-scanner settings and reproducibility with other configurations. Overall for the intra-scanner and twin-scanner experiments, the region-based analysis coefficient of variation (CV) was in a range of 1%-4.2% and below 3% for almost every bundle for the tract-based analysis. The uncinate fasciculus showed the worst reproducibility, especially for FA and GFA values (CV 3.7-6%). For the GFA and FA maps, an ICC value of 0.7 and above is observed in almost all the regions/tracts. Looking at the last experiment, it was found that there is a very high similarity of the outcomes from the two scanners with identical setting. However, this was not the case for the two other imagers. Given the fact that the overall variation in our study is low for the imagers with identical settings, our findings support the feasibility of cross-site pooling of DSI data from identical scanners.

Fréquence des incidentalomes lors d'un examen PET/CT effectué pour une pathologie oncologique

Contexte¦Le PET/CT au 18Fluor (FDG) fait aujourd'hui partie intégrante des moyens diagnostiques¦à disposition pour la stadification des cancers suspectés ou connus. Il n'est pas rare de¦découvrir des lésions fortuites.¦Objectifs¦Notre but était de déterminer la fréquence des lésions tumorales ou non, cliniquement¦silencieuses (incidentalomes), chez des patients consécutifs non sélectionnés examinés¦par PET/CT au FDG pour un cancer connu ou supposé au sein du bassin populationnel¦du CHUV.¦Méthode¦Nous avons rétrospectivement lu les 1226 des rapports d'examens faits d'août 2009 à¦juillet 2010 pour toute indication oncologique et relevé les lésions de découverte¦fortuite et leur localisation, avant de rechercher leur investigation et leur prise en¦charge.¦Résultats¦Nous avons retenu 309 lésions fortuites chez 260 patients (25,2% des rapports lus),¦dont 141 chez 127 patients investiguées. Ont été relevés 31 patients présentant 32¦incidentalomes (2,6%), dont 6 étaient malins, 6 pré-malins et 20 bénins, soit un taux de¦1% pour les malins et pré-malins. Les sites les plus fréquents étaient les mêmes que¦dans la littérature, à savoir la thyroïde, le poumon, la sphère colorectale (lésions prémalignes¦uniquement) et les lymphomes. Pour ces trois derniers, les lésions étaient¦moins fréquentes que ce qui est rapporté. Tous ces foyers sont à investiguer¦soigneusement, afin de différencier une nouvelle atteinte d'une métastase.¦Conclusion¦En tant que première étude suisse sur le sujet, nous obtenons 1% d'incidentalomes¦(pré)malins, soit l'équivalent de la limite inférieure de la littérature, dans des sites¦similaires. Une amélioration serait possible en augmentant l'attention portée aux lésions¦jugées peu significatives. A l'instar de nombreuses autres études, nous sommes aussi¦confrontés au problème lié à l'interprétation des foyers de captation et à la nonspécificité¦du FDG.

Multi-Atlas based Segmentation of Head and Neck CT Images using Active Contour

This paper presents the segmentation of bilateral parotid glands in the Head and Neck (H&N) CT images using an active contour based atlas registration. We compare segmentation results from three atlas selection strategies: (i) selection of "single-most-similar" atlas for each image to be segmented, (ii) fusion of segmentation results from multiple atlases using STAPLE, and (iii) fusion of segmentation results using majority voting. Among these three approaches, fusion using majority voting provided the best results. Finally, we present a detailed evaluation on a dataset of eight images (provided as a part of H&N auto segmentation challenge conducted in conjunction with MICCAI-2010 conference) using majority voting strategy.

Pratique du scanner en Suisse: fréquence et évolution temporelle [CT utilisation in Switzerland: frequency and secular trends]

PURPOSE: This study analyzes CT examinations in Switzerland. MATERIALS AND METHODS: Using different sources (administrative data on the equipment, a 1998 nationwide inquiry into practices, and data provided by the Swiss University Hospitals of Basel, Zurich, and Lausanne), we determined the frequency of CT examinations (hospitals and private radiologists) in 1998 according to different descriptive variables and studied the progression in CT use over time. RESULTS: CT scanners increased by 7% between 1998 and 2004. The average annual number of CT examinations in 1998 was 46.3/1000 population, 3.4% of all radiological examinations in Switzerland in 1997-1998. The most frequent examination was CT of the skull (24%), while private radiology institutes perform more CTs of the spine. More CT examinations were performed for men than for women (sex ratio M/F=1.17). The average annual increase in CT in Swiss hospitals varied from 8% for Basel to 18% for Lausanne. Finally, the proportion of pediatric examinations was 5%; their numbers appear to be stabilizing. CONCLUSION: There is a significant increase in CT examinations. It is hoped that our study will heighten awareness among doctors of CT examinations in order to optimize their use.

Pediatric CT: how to compare the Present DRL Values? : 12.10

Purpose: To determine dose thresholds, in term of CTDIvol, where subtle anatomical structures of pediatric CT images becomes no more detectable and compare them to the most recent Reference Dose Levels (DRL) proposed in the UK, Germany and Switzerland. Materials and methods: A GE LightSpeed-Ultra scanner (MSCT 8 slices) was used to perform chest and abdomen acquisitions on 8 patients (age range 2 to 16 years old) to provide a set of gold standard images. Dose reductions were then simulated by introducing image noise on raw data to provide simulated CT images with CTDIvol ranging from 2 to 22 mGy. All images were reviewed and scored independently by four experienced radiologists using the VGA methodology (Visual Grading Analysis) to determine the dose threshold where a significant loss of normal anatomy conspicuity appeared. Data were analyzed with ANOVA and Tukey HSD tests, a p >0.05 was considered to be significant. Results: No significant difference in VGA scoring appeared for CTDIvol leading to image noise levels lower than 10 and 25 HU for respectively abdominal and chest acquisitions. These data can thus be used to set the AEC (automatic exposure control) system of units having similar noise properties than the GE LightSpeed-Ultra used in this study. The present DRLs proposed for pediatric CT acquisitions are compatible with an excellent image quality level. Conclusion: The differences of DRL values proposed in Europe for pediatric acquisitions are marginal and assure a very good image quality level. The results of this study allow to further optimize the acquisition protocol by giving Noise Index value to set the AEC device.

Postmortem dynamic CT-angiography : P30

Purpose: Forensic imaging and especially forensic radiology is a new trend in forensic medicine. More and more forensic institutes set up their own CT-scanner in order to perform postmortem cross-sectional imaging. Due to this trend, a new subspecialty was born: the forensic radiology. To image the vascular system after death, a postmortem CT- angiography can be performed. Methods and materials: In the Institute of Forensic Medicine in Lausanne, a science group has been created with specialists of different medical fields that has set up a new technique of forensic CT-angiography. The method consists in the creation of a postmortem circulation by the use of a modified heart lung machine. As circulating liquid Angiofil, an oily contrast agent, is injected. Results: With the aid of this technique, the whole vascular system of a deceased person can be imaged in detail without autopsy. The circulating contrast allows demonstrating the vascular system when it is under pressure, similarly to living patients. First experiences showed, that vascular pathologies such as cardiac tamponade and aortic dissection can be well demonstrated. Since the oily Angiofil strictly remains in the intravascular space, no artifacts had been observed during the CT-examination and the later performed autopsy. Conclusion: Post-mortem dynamic CT angiography is of great advantage in forensic pathology, because the detailed mapping of the entire vascular system is almost impossible with conventional autopsy tools.

Screening of illegal intracorporeal containers ("body packing"): is abdominal radiography sufficiently accurate? A comparative study with low-dose CT.

PURPOSE: To evaluate the diagnostic performance of abdominal radiography in the detection of illegal intracorporeal containers (hereafter, packets), with low-dose computed tomography (CT) as the reference standard. MATERIALS AND METHODS: This study was approved by the institutional ethical review board, with written informed consent. From July 2007 to July 2010, 330 people (296 men, 34 women; mean age, 32 years [range, 18-55 years]) suspected of having ingested drug packets underwent supine abdominal radiography and low-dose CT. The presence or absence of packets at abdominal radiography was reported, with low-dose CT as the reference standard. The density and number of packets (≤ 12 or >12) at low-dose CT were recorded and analyzed to determine whether those variables influence interpretation of results at abdominal radiography. RESULTS: Packets were detected at low-dose CT in 53 (16%) suspects. Sensitivity of abdominal radiography for depiction of packets was 0.77 (41 of 53), and specificity was 0.96 (267 of 277). The packets appeared isoattenuated to the bowel contents at low-dose CT in 16 (30%) of the 53 suspects with positive results. Nineteen (36%) of the 53 suspects with positive low-dose CT results had fewer than 12 packets. Packets that were isoattenuated at low-dose CT and a low number of packets (≤12) were both significantly associated with false-negative results at abdominal radiography (P = .004 and P = .016, respectively). CONCLUSION: Abdominal radiography is mainly limited by low sensitivity when compared with low-dose CT in the screening of people suspected of carrying drug packets. Low-dose CT is an effective imaging alternative to abdominal radiography.

Pouchography, CT, and MRI features of ileal J pouch-anal anastomosis

OBJECTIVE: Our objective is to describe pouchography, CT, and MRI features of the J-shaped pouch, both normal and with pouch-related complications. CONCLUSION: Pouchography is performed before closure of the loop ileostomy to assess the integrity of the ileal pouch and anastomosis. CT and MRI can be performed when postoperative complications, such as small-bowel obstruction, pouchitis, leakage, abscess, intramural hematoma, desmoid tumor, or recurrent Crohn's disease, are suspected.

CT dose optimization when changing to CT multi-detector row technology

The purpose of this article was to review the strategies to control patient dose in adult and pediatric computed tomography (CT), taking into account the change of technology from single-detector row CT to multi-detector row CT. First the relationships between computed tomography dose index, dose length product, and effective dose in adult and pediatric CT are revised, along with the diagnostic reference level concept. Then the effect of image noise as a function of volume computed tomography dose index, reconstructed slice thickness, and the size of the patient are described. Finally, the potential of tube current modulation CT is discussed.