Denis Tack

MDCT for suspected acute appendicitis in adults: Impact of oral and IV contrast media at standard-dose and simulated low-dose techniques

OBJECTIVE The objective of this study was to prospectively investigate the influence of oral, IV, and oral and IV contrast media on the information provided by MDCT at standard and simulated low radiation doses in adults suspected of having acute appendicitis. SUBJECTS AND METHODS One hundred thirty-one consecutive patients (80 women, 51 men; age range, 18-87 years; mean age, 37 years) suspected of having appendicitis were randomly assigned to either ingest or not ingest iodinated contrast material. Thereafter, all patients underwent IV unenhanced and enhanced abdominopelvic MDCT with a 4 x 2.5 mm collimation at 120 kVp and 100 mAs(eff). Dose reduction corresponding to 30 mAs(eff) was simulated. Two radiologists independently read scans during separate sessions, assessed appendix visualization, and proposed a diagnosis (i.e., appendicitis or an alternative diagnosis). The final diagnosis was based on either surgical findings or clinical follow-up. Data were analyzed by factorial analysis of multiple correspondences followed by an ascending hierarchic classification method. RESULTS Factorial analysis and ascending hierarchic classification revealed that, in terms of diagnostic correctness, reader influence predominated over the influence of IV and oral contrast media use and radiation dose but that correctness was also influenced by the patients sex (p = 0.048) and was lower in cases of alternative diseases (p < 0.001). Visualization of the appendix depended predominantly on the reader rather than on the use of IV, oral, or oral and IV contrast agents or on radiation dose. CONCLUSION Diagnostic correctness is much more influenced by the reader than by the use of contrast medium (oral, IV, or both) or of simulated low-radiation-dose technique.

Radiation dose from adult and pediatric multidetector computed tomography

Introduction: Clincical Expansion of CT and Radiation Dose Part I: Radiation Risks in Multidetector CT: Risks from Ionizing Radiations The Linear-No-Threshold Theory: Background and Limitations CT Parameters that Influence the Radiation Dose Collective Radiation Dose from MDCT: Critial Review and Survey Studies Methods for Reducing the Radiation Dose from MDCT Including Image Quality Automatic Exposure Control in Multidetector-Row CT Patient Centering and CT Radiation Dose Part II: Clinical Approaches of Dose Optimization, and Reduction: Dose Optimization and Reduction in CT of Head and Neck Including Brain Dose Optimization and Reduction in CT of the Chest Dose Optimization and Reduction in CT of the Abdomen Dose Optimization and Reduction in CT Angiography and Cardiac CT Dose Optimization and Reduction in CT of the Musculoskeletal System Including the Spine Dose Reduction in CT Fluoroscopy Dose Optimization and Reduction in CT of Children Radiation Risk Management in Low Dose MDCT Screening Programs Subject Index List of Contributors.

Dose Reduction Strategies for Thoracic Multidetector Computed Tomography: Background, Current Issues, and Recommendations

This review will summarize the current background knowledge about radiation exposure related to thoracic computed tomography (CT). It will also review the historical development in this area. This will be followed by a summary of current efforts to reduce dose with respect to predefined clinical indications. Finally, the review will indicate future strategies for further dose reduction in thoracic CT imaging and give practical recommendations for everyday use.

Spontaneous lung herniation after a single cough

Abstract. Herniation of the lung is commonly caused by congenital rib abnormalities, blunt trauma, or thoracic surgery. Spontaneous hernias are rarely described in the literature. We report a case of a spontaneous intercostal pulmonary hernia following a single cough. In addition, a review of the literature is presented which outlines the classification, causes, and incidence of lung hernias. Some reference is made to possible methods of treatment.

Differentiating between Subsolid and Solid Pulmonary Nodules at CT: Inter- and Intraobserver Agreement between Experienced Thoracic Radiologists

PURPOSE To quantify the reproducibility and accuracy of experienced thoracic radiologists in differentiating between subsolid and solid pulmonary nodules at CT. MATERIALS AND METHODS The institutional review board of Beth Israel Deaconess Medical Center approved this multicenter study. Six thoracic radiologists, with a mean of 21 years of experience in thoracic radiology (range, 17-22 years), selected images of 10 solid and 10 subsolid nodules to create a database of 120 nodules; this selection served as the reference standard. Each radiologist then interpreted 120 randomly ordered nodules in two different sessions that were separated by a minimum of 3 weeks. The radiologists classified whether or not each nodule was subsolid. Inter- and intraobserver agreement was assessed with a κ statistic. The number of correct classifications was calculated and correlated with nodule size by using Bland-Altman plots. The relationship between disagreement and nodule morphologic characteristics was analyzed by calculating the intraclass correlation coefficient. RESULTS Interobserver agreement (κ) was 0.619 (range, 0.469-0.745; 95% confidence interval (CI): 0.576, 0.663) and 0.670 (range, 0.440-0.839; 95% CI: 0.608, 0.733) for interpretation sessions 1 and 2, respectively. Intraobserver agreement (κ) was 0.792 (95% CI: 0.750, 0.833). Averaged for interpretation sessions, correct classification was achieved by all radiologists for 58% (70 of 120) of nodules. Radiologists agreed with their initial determination (the reference standard) in 77% of cases (range, 45%-100%). Nodule size weakly correlated with correct classification (long axis: Spearman rank correlation coefficient, rs = 0.161 and P = .049; short axis: rs = 0.128 and P = .163). CONCLUSION The reproducibility and accuracy of thoracic radiologists in classifying whether or not a nodule is subsolid varied in the retrospective study. This inconsistency may affect surveillance recommendations and prognostic determinations.

Radiation dose from multidetector CT

Part I: General Aspects of CT Radiation.- Part II: Clinical Approaches of Dose Optimization and Reduction.- Part III: Initiatives for Dose Reduction.- Part IV: Practical Approaches Depending on Vendors.- Part V: Low Dose Images.

The CT fallen-lung sign.

Abstract. On chest radiograph, the diagnosis of tracheobronchial tear is usually suspected because of the persistence of a pneumothorax after chest tube insertion. Since this radiographic pattern is nonspecific, the diagnosis is usually made by bronchoscopy and delayed. The fallen-lung sign consists in the fall of the collapsed lung away from the mediastinum occurring when the normal central bronchial anchoring attachment of the lung is disrupted. In contrast to the persistent pneumothorax, this sign is specific but rarely observed. Our purpose is to present the corresponding CT patterns observed in two cases of right stem bronchus tear, consisting in a caudal-dependent displacement of the right upper lobe bronchus which becomes obliquely oriented.

Female Breast, Lung, and Pelvic Organ Radiation From Dose-Reduced 64-MDCT Thoracic Examination Protocols: A Phantom Study

OBJECTIVE We compared phantom organ doses delivered to breast, lung, and pelvis by five protocols using current dose reduction methods for routine chest CT and pulmonary CT angiography. MATERIALS AND METHODS We measured the radiation dose to an anthropomorphic phantom using 64-MDCT with metal oxide semiconductor field effect transistor (MOSFET) detectors in the breast (skin and parenchyma), the lungs, and the pelvis (upper and lower). We compared the following five protocols: protocol 1, 120 kVp, automatic dose modulation, 120-320 mA; protocol 2, 120 kVp, automatic dose modulation, 60-200 mA; protocol 3, 100 kVp and fixed dose of 200 mA; protocol 4, 120 kVp, automatic dose modulation, 200-394 mA; and protocol 5, 80 kVp and fixed dose of 120 mA. Organ doses in milligrays and as a percentage of the volume CT dose index (CTDI(vol)) were compared using the analysis of variance for repeated measurements. RESULTS Protocol 1 delivered the highest breast dose (mean ± SD, 15.8 ± 1.8 mGy; 110.5% of CTDI(vol)). A decrease in breast radiation of more than 50% was achieved with protocol 3 (4.8 ± 1.8 mGy; 91.7% of CTDI(vol)) compared with protocol 4 (13.1 ± 5.5 mGy; 87.0% of CTDI(vol)) (p = 0.003). The lung received the highest organ dose regardless of the protocol (protocol 4: 21.5 ± 1.7 mGy; 142.5% of CTDI(vol)). Pelvic radiation was low regardless of protocol and did not exceed 0.2 mGy (up to 3.7% of CTDI(vol); p = 0.118-0.999). CONCLUSION The results of this anthropomorphic phantom study showed substantial and significant variation in radiation doses to the breast and lungs depending on the scanning protocol used with the potential for over threefold dose reduction.

Cholecystoduodenal fistula in a porcelain gallbladder

Abstract. Calcification of the gallbladder wall (porcelain gallbladder) is rare. Its appearance is quite characteristic on plain films, ultrasonography and computed tomography. Sporadic cases of cholecystitis have been described in porcelain gallbladders. Enterobiliary fistula may complicate acute or chronic cholecystitis in non-calcified gallbladder. We report a unusual case of acute cholecystitis with cholecystoduodenal fistula in a porcelain gallbladder.

Optimised z-axis coverage at multidetector-row CT in adults suspected of acute appendicitis

OBJECTIVE To compare diagnostic performances of two reduced z-axis coverages to full coverage of the abdomen and pelvis for the diagnosis of acute appendicitis and alternative diseases at unenhanced CT. METHODS This study included 152 adults suspected of appendicitis who were enrolled in two ethical committee-approved previous prospective trials. Based on scans covering the entire abdomen and pelvis (set L), two additional sets of images were generated, each with reduced z-axis coverages: (1) from the top of the iliac crests to the pubis (set S) and (2) from the diaphragmatic crus to the pubis (set M). Two readers independently coded the visualisation of the appendix, measured its diameter and proposed a diagnosis (appendicitis or alternative). Final diagnosis was based on surgical findings or clinical follow-up. Fisher exact and McNemar tests and logistic regression were used. RESULTS 46 patients had a definite diagnosis of appendicitis and 53 of alternative diseases. The frequency of appendix visualisation was lower for set S than set L for both readers (89% and 84% vs 95% and 91% by Readers A and B, respectively; p=0.021 and 0.022). The probability of giving a correct diagnosis was lower for set S (68%) than set L (78%; odds ratio, 0.611; p=0.008) for both readers, without significant difference between sets L and M (77%, p=0.771); z-axis coverage being reduced by 25% for set M. CONCLUSION Coverage from diaphragmatic crus to pubis, but not focused on pelvis only, can be recommended in adults suspected of appendicitis. ADVANCES IN KNOWLEDGE In suspected appendicitis, CT-coverage can be reduced from diaphragmatic crus to pubis.