Overview of two years of clinical experience of chest tomosynthesis at Sahlgrenska University Hospital.

Since December 2006, approximately 3800 clinical chest tomosynthesis examinations have been performed at our department at Sahlgrenska University Hospital. A subset of the examinations has been included in studies of the detectability of pulmonary nodules, using computed tomography (CT) as the gold standard. Visibility studies, in which chest tomosynthesis and CT have been compared side-by side, have been used to determine the depiction potential of chest tomosynthesis. Comparisons with conventional chest radiography have been made. In the clinical setting, chest tomosynthesis has mostly been used as an additional examination. The most frequent indication for chest tomosynthesis has been suspicion of a nodule or tumour. In visibility studies, tomosynthesis has depicted over 90 % of the nodules seen on the CT scan. The corresponding figure for chest radiography has been <30 %. In the detection studies, the lesion-level sensitivity has been approximately 60 % for tomosynthesis and 20 % for chest radiography. In one of the detection studies, an analysis of all false-positive nodules was performed. This analysis showed that all findings had morphological correlates on the CT examinations. The majority of the false-positive nodules were localised in the immediate subpleural region. In conclusion, chest tomosynthesis is an improved chest radiography method, which can be used to optimise the use of CT resources, thereby reducing the radiation dose to the patient population. However, there are some limitations with chest tomosynthesis. For example, patients undergoing tomosynthesis have to be able to stand still and hold their breath firmly for 10 s. Also, chest tomosynthesis has a limited depth resolution, which may explain why pathology in the subpleural region is more difficult to interpret and artefacts from medical devices may occur.

A phantom study of nodule size evaluation with chest tomosynthesis and computed tomography.

The aim of the present study was to investigate nodule size measurements with chest tomosynthesis (TS) and computed tomography (CT). A 26-mm thick phantom, composed of a Polylite block with embedded spheres of different materials and sizes (4-20 mm), was scanned by both CT and TS. Six observers without prior knowledge of the true diameters of the spheres independently measured the diameter of the spheres on the CT and TS images. Four observers were allowed to change the window settings and two of the observers used predetermined fixed viewing conditions. The mean relative errors for all observers and all measured spheres compared with the known diameter of the spheres were 1.4 % (standard deviation, SD: 5.4 %) on CT images and -1.1 % (SD: 5.0 %) on TS images. With regard to the four observers where the window settings were at the discretion of the observer, the mean relative errors were 1.4 % (SD: 6.4 %) on CT images and -1.7 % (SD: 5.7 %) on TS images. Regarding the two observers using identical viewing conditions the mean relative error was 1.5 % (SD: 2.8 %) on CT images and 0.2 % (SD: 2.6 %) on TS images. In conclusion, the study suggests that nodule size measurements on chest TS might be an alternative to measurements on CT.

Effect of clinical experience of chest tomosynthesis on detection of pulmonary nodules.

BACKGROUND: The new technique chest tomosynthesis refers to the principle of collecting low-dose projections of the chest at different angles and using these projections to reconstruct section images of the chest at a radiation dose comparable to that of chest radiography. PURPOSE: To investigate if, for experienced thoracic radiologists, the detectability of pulmonary nodules obtained after only a short initial learning period of chest tomosynthesis improves with additional clinical experience of the new technique. MATERIAL AND METHODS: Two readings of the same clinical chest tomosynthesis cases, the first performed after 6 months of clinical experience and the second after an additional period of 1 year, were conducted. Three senior thoracic radiologists, with more than 20 years of experience of chest radiography, acted as observers, with the task of detecting pulmonary nodules in a jackknife free-response receiver operating characteristics (JAFROC1) study. The image material consisted of 42 patients with and 47 patients without pulmonary nodules examined with chest tomosynthesis. Multidetector computed tomography (MDCT) was used as a reference. The total number of nodules was 131. The JAFROC1 figure of merit (FOM) was used as the principal measure of detectability. RESULTS: The difference in the observer-averaged JAFROC1 FOM of the two readings was 0.004 (95% confidence interval: -0.11, 0.12; F-statistic: 0.01 on 1 and 2.65 df; P=0.91). Thus, no significant improvement in detectability was found after the additional clinical experience of tomosynthesis. CONCLUSION: The study indicates that experienced thoracic radiologists already within the first months of clinical use of chest tomosynthesis are able to take advantage of the new technique in the task of detecting pulmonary nodules.

Detection of mild emphysema by computed tomography density measurements.

PURPOSE: To assess the ability of a conventional density mask method to detect mild emphysema by high-resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema. MATERIAL AND METHODS: Fifty-five healthy male smokers and 34 never-smokers, 61-62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated. RESULTS: Forty-nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65-100% in the apical levels, but low in the rest of the lung. CONCLUSION: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect.

High-resolution computed tomography in healthy smokers and never-smokers: a 6-year follow-up study of men born in 1933.

PURPOSE: To elucidate whether emphysematous lesions and other high-resolution computed tomography (HRCT) findings considered associated with smoking are part of a progressive process, and to measure the extent to which similar changes are found in never-smokers. MATERIAL AND METHODS: Healthy smokers and never-smokers were recruited from a randomized epidemiological study and investigated with a 6-year interval. Emphysema, parenchymal and subpleural nodules, ground-glass opacities, bronchial alterations, and septal lines were evaluated in 66 subjects (40 smokers, 11 of whom had stopped smoking in the interval, and 26 never-smokers). Lung function was tested. RESULTS: All except emphysematous lesions were present to some extent in never-smokers. Emphysema, parenchymal nodules, and septal lines occurred significantly more in current smokers, and a progression in extent of emphysema, ground-glass opacities, bronchial alterations and septal lines was seen. There was no significant change among those who stopped and never-smokers except for bronchial alterations, which progressed in never-smokers. CONCLUSION: In healthy, elderly never-smokers a low extent of various HRCT findings has to be considered normal. Emphysema, parenchymal nodules, and ground-glass opacities are indicative of smoking-induced disease. Further progress may cease if smoking is stopped.

Neutrophil-associated activation markers in healthy smokers relates to a fall in DL(CO) and to emphysematous changes on high resolution CT.

Smoking is a risk factor for developing chronic obstructive pulmonary disease (COPD), but there are no good indicators for early identification of subjects who will develop symptomatic COPD. The aim of this study was to investigate inflammatory mechanisms related to changes in lung function and emphysematous changes on high resolution computed tomography (HRCT) in 'healthy' smokers. Subjects were 60-year-old men from a population study. Bronchoscopy was performed in 30 smokers and 18 who had never smoked. Blood tests, lung function measurements and HRCT were carried out in 58 and 34 subjects, respectively. In comparison with never-smokers, smokers had higher levels of myeloperoxidase (MPO), human neutrophil lipocalin (HNL), eosinophil cationic protein (ECP) and lysozyme in blood, higher levels of MPO, interleukin-8 (IL-8) and HNL in bronchial lavage (BL), and of IL-8, HNL and interleukin-lbeta (IL-1beta) in bronchoalveolar lavage (BAL). Smokers also had lower levels of Clara cell protein 16 (CC-16) in blood. HNL in BL and BAL showed strong correlations to other inflammatory markers (MPO, IL-8, IL-1beta). The variations in MPO in BL were explained by variations in HNL (R2 =0.69), while these variations in BAL were explained by variations in HNL and IL-1beta (R2 = 0.76). DL(CO) was the lung function variable most closely related to MPO and IL-8 in BL and BAL and to IL-1beta in BAL. In a multiple regression analysis, MPO, IL-1beta, IL-8 and CC-16 in BL and MPO in BAL contributed to the explanation of variations in DL(CO) to 41% and 22%. respectively, independent of smoking habits. In smokers with emphysematous lesions on HRCT, HNL in BAL correlated to emphysema score (r(s) = 0.71). We conclude that 'healthy' smoking men with a near normal FEV1 show signs of inflammation in the lower airways that are related to a decrease in DL(CO) and to emphysematous lesions on HRCT. This inflammation seems to be the result of both monocyte/macrophage and neutrophil activation.

[Acute abdomen calls for considerable care resources. Analysis of 3727 in-patients in the county of Stockholm during the first quarter of 1995]. / Akut buksjukdom kräver stora vårdresurser. Analys av 3,727 inlagda patienter första kvartalet 1995 i Stockholms län.

A total of 3,727 in-patients with acute abdominal symptoms were identified during the first quarter of 1995 at the surgical clinics of the nine hospitals with emergency departments in the county of Stockholm. The diagnoses were: non-specific abdominal pain 24%; cholecystitis 9%; appendicitis 8%; bowel obstruction 7%; intra-abdominal malignancy, diseases of the urinary tract and peptic ulcer 6% each; gastrointestinal hemorrhage, diverticulitis of the colon and pancreatitis 5% each; other diseases as a cause of abdominal symptoms, 19%. 1,601 operations were performed of which 47% were endoscopic procedures. The mean duration of hospital stay was 4.8 days. The length of stay increased significantly with age. The age-related relative frequency of hospitalization due to acute abdominal pain was also dramatically higher in the elderly cohorts. These facts and the prognosis of an 18% increase of inhabitants 50 years of age or older until 2010 in Greater Stockholm signal an increased need of hospital resources for this large group of patients in the coming years.

Emphysematous lesions and lung function in healthy smokers 60 years of age.

We aimed to study the occurrence of emphysematous lesions in symptom free smoking men of about 60 years of age and in a matching group of never-smoking men and the relationship between pulmonary changes at high resolution computed tomography (HRCT) and lung function tests. Our investigation included 57 smoking and 32 never-smoking healthy men from a randomized epidemiological study. HRCT was performed at full inspiration with a 1.5 mm slice thickness and a 3 cm inter-slice distance. Evaluation was made by two radiologists unaware of smoking history. Emphysematous lesions were scored visually. Pulmonary function tests were performed including spirometry and diffusion capacity test (DLCO). Emphysematous changes were demonstrated in 25 of 57 smokers but in only one never-smoker. DLCO/VA was the most sensitive test for early emphysematous lesions. It also correlated with radiographical scoring. Emphysematous lesions were evident in 44% of the healthy symptom free smokers. HRCT may reveal early emphysematous lesions in smokers before clinical symptoms have developed.

[Computed tomography as an alternative to observation in brain concussion]. / Datortomografi alternativ till observation vid hjärnskakning.

In Sweden, patients with minor head injury (i.e., history of loss of consciousness or posttraumatic amnesia) are routinely admitted for neurological observation. The article reports the results of a small study of current clinical practices at St Göran's Hospital in Stockholm, and briefly reviews published reports of different management strategies. The findings suggest that computed tomography scanning might constitute better management than routine hospitalisation, both medically and economically. However, further investigation from a Swedish perspective is needed before any evidence-based recommendations can be made.

[Increased number of knife assaults inspite of the legislation. Record of injuries among 399 patients]. / Fler knivöverfall trots knivlagen. Skadepanorama hos 399 knivhuggna patienter.

From January 1985 to September 1993, 399 patients (368 men and 31 women), median age 28 years (mean 31.1, range 16-71 years), were admitted with stab wounds due to assault. The number of stab wounds per patient was one (N = 268 patients), two (N = 63), three (N = 31), four (N = 15), five (N = 7), or more than five (N = 15). The series as whole (N = 399) accounted for 543 sites of injury. Upper extremity wounds were the most frequent (35 per cent); of 188 arm injuries, 60 per cent were in the left arm. The next most frequent site was the head and neck region (N = 105; 12 per cent), followed by the chest (N = 75; 14 per cent), abdomen (N = 66;12 per cent), lower extremities (N = 59;11 per cent), back (N = 48;9 per cent), and the male genitalia (N = 2;0.4 per cent). Ninety-five major operations were performed in 74 patients. Seven patients died, and 40 had somatic or cosmetic life-time sequelae.

Computed tomography with intravenous cholangiography contrast: a method for visualizing choledochal cysts.

Our patient presented with a typical case history and typical symptoms. She also belongs to a group with a high incidence of the disorder. The diagnosis was suspected at ultrasonography, which accurately detected the presence and location of a cyst, but could not establish its origin. Computed tomography is a better diagnostic tool, as it will detect small differences in attenuation and thus identify contrast accumulation in the bile ducts, even when the function of the lever parenchyma is decreased. As scanning is performed in the transverse plane with the patient supine, the layering of contrast medium in the dilated duct is also displayed. In the analysis of our case, the accumulation of biliary contrast medium in the lesion at CT established its origin. The fusiform nature of the dilatation (the type I form of the disorder), was demonstrated at ERCP, after which the operation was performed.

Glomerular filtration rate estimated after multiple injections of contrast medium during angiography.

In twenty-six patients referred for angiography, clearance of contrast medium was determined with x-ray fluorescence analysis after multiple injections of contrast medium. A formula for correction of the injected amount, which takes into consideration the different times of contrast medium injections, approximating the total injected amount into one injection, was used. A single injection clearance of 51Cr-EDTA was determined at the same time. The results showed a good correlation between the clearance of contrast medium after multiple injections and the 51Cr-EDTA clearance after a single injection (r = 0.945). The correlation between contrast medium clearance calculated without correction for the different injection times, and 51Cr-EDTA clearance was the same (r = 0.946), due to short angiography time and rather low clearance values in our patients. It is concluded that total plasma clearance of contrast medium can easily be estimated after multiple injections. In this way patients with a risk of developing post-angiographic renal failure can be found.

Cardiac output determination during intravenous cardioangiography using x-ray fluorescence analysis.

Cardiac output was determined with an indicator dilution technique during digital venous angiography of the left ventricle in 11 patients. The contrast medium injected into the right atrium was used as indicator. During and after the injection of contrast medium one blood sample per second was obtained through a catheter placed in the descending aorta. The samples were analyzed for iodine content with x-ray fluorescence analysis and cardiac output determined ad modum Stewart-Hamilton. Thermodilution was used as a reference method. The results indicate that the indicator dilution method with the use of contrast medium might be used for calibration of videodensitometric methods for blood flow measurements.

Glomerular filtration rate estimated from a single plasma sample after contrast-enhanced radiological examinations.

In twenty-six patients examined with radiographic procedures, including a single injection of meglumine metrizoate, blood samples were drawn 180, 200, 220 and 240 min after injection. Plasma was analysed for iodine concentration with X-ray fluorescence analysis and the total plasma clearance of metrizoate was calculated with the single sample method from each sample. The results were compared with the total plasma clearance of 51Cr-EDTA, calculated from multiple samples and determined no more than a few days apart from the X-ray examination. A good correlation, ranging from 0.91 and 0.94, was found. We therefore conclude that kidney function can be estimated from a single plasma sample after contrast-enhanced radiological examinations.

Renal function measured by x-ray fluorescence analysis. A comparison between contrast medium clearance and non-simultaneous 51Cr-EDTA clearance.

In twenty-six patients injected with metrizoate during urography, plasma was analyzed for iodine concentration using x-ray fluorescence analysis, and total plasma clearance of contrast medium was calculated. Total plasma clearance of 51Cr-EDTA was also determined, but not simultaneously, in order to find out if the urographic procedure would influence the kidneys to such an extent that the contrast medium clearance value would differ much from the 51Cr-EDTA clearance value. The errors in the method were assessed and the total error of the contrast medium clearance determination was calculated. When comparing 51Cr-EDTA and metrizoate clearance a correlation of 0.94 and a mean ratio of 1.046 (SD 0.138) was found. The assessable errors cannot fully explain the standard deviation, which might indicate a transient change in kidney function related to elements of the urographic procedure such as laxation with possible dehydration and/or the contrast medium dose.

Perception errors with double-contrast enema after a positive guaiac test.

Between 3 and 6 of 12 colorectal neoplasms larger than 1 cm in diameter were overlooked by each of 4 radiologists in 117 individuals investigated with double-contrast enema (DCE) after a positive guaiac test. Even when the individual results of 2, 3, or 4 experienced radiologists were combined, 2 small carcinomas were overlooked due to perception errors. One of these carcinomas was diagnosed by rectosigmoidoscopy, which is an important and necessary complement to DCE. Although small carcinomas may be missed even with this combination, meticulous exploitation of the 2 methods is absolutely necessary to minimize the risk of missing a colorectal neoplasm. A drawback when 2 or more radiologists read the radiographs is the increased number of false-positive findings.

Repeated computed tomography during treatment of small cell carcinoma of the lung.

Twenty-three patients with small cell carcinoma of the lung were examined with CT and conventional chest radiography before treatment, 19 after 3 courses of chemotherapy, before radiation therapy, and 8 after cessation of chemotherapy and radiation therapy. In most patients high abdominal CT was also employed. CT provided more information about the thoracic involvement than did conventional radiography in more than half of the cases. In 3 cases CT before irradiation demonstrated progression in the thorax, not visible at conventional radiography, and in 4 cases progression of extrathoracic metastases in spite of intrathoracic regression. After therapy, one case of progression in the thorax not seen at conventional radiography was demonstrated. With repeated CT examinations of the thorax and abdomen, progression/regression both intra- and extrathoracically is well demonstrated.