Routine Chest CT Examinations Research Articles

Breast glandular dose and effectiveness of in-plane bismuth breast shield in routine pediatric female chest CT examination

Breast glandular dose and effectiveness of in-plane bismuth breast shield in routine pediatric female chest CT examination

Potential of the Non-Contrast-Enhanced Chest CT Radiomics to Distinguish Molecular Subtypes of Breast Cancer: A Retrospective Study.

ObjectivesThe molecular subtype plays an important role in breast cancer, which is the main reference to guide treatment and is closely related to prognosis. The objective of this study was to explore the potential of the non-contrast-enhanced chest CT-based radiomics to predict breast cancer molecular subtypes non-invasively.MethodsA total of 300 breast cancer patients (153 luminal types and 147 non-luminal types) who underwent routine chest CT examination were included in the study, of which 220 cases belonged to the training set and 80 cases to the time-independent test set. Identification of the molecular subtypes is based on immunohistochemical staining of postoperative tissue samples. The region of interest (ROI) of breast masses was delineated on the continuous slices of CT images. Forty-two models to predict the luminal type of breast cancer were established by the combination of six feature screening methods and seven machine learning classifiers; 5-fold cross-validation (cv) was used for internal validation. Finally, the optimal model was selected for external validation on the independent test set. In addition, we also took advantage of SHapley Additive exPlanations (SHAP) values to make explanations of the machine learning model.ResultsDuring internal validation, the area under the curve (AUC) values for different models ranged from 0.599 to 0.842, and the accuracy ranged from 0.540 to 0.775. Eventually, the LASSO_SVM combination was selected as the final model, which included 9 radiomics features. The AUC, accuracy, sensitivity, and specificity of the model to distinguish luminal from the non-luminal type were 0.842 [95% CI: 0.728−0.957], 0.773, 0.818, and 0.773 in the training set and 0.757 [95% CI: 0.640–0.866], 0.713, 0.767, and 0.676 in the test set.ConclusionThe radiomics based on chest CT may provide a new idea for the identification of breast cancer molecular subtypes.

Biphasic split-bolus injection protocol for routine contrast-enhanced chest CT: comparison with conventional early-phase single bolus technique.

To present a routine contrast-enhanced chest CT protocol with a split-bolus injection technique achieving combined early- and delayed phase images with a single aquisition, and to compare this technique with a conventional early-phase single-bolus chest CT protocol we formerly used at our institution, in terms of attenuation of great thoracic vessels, pleura, included hepatic and portal venous enhancement, contrast-related artifacts, and image quality. A total of 202 patients, who underwent routine contrast-enhanced chest CT examination aquired with either conventional early-phase single-bolus technique (group A,n = 102) or biphasic split-bolus protocol (group B,n = 100), were retrospectively included. Attenuation measurements were made by two radiologists independently on mediastinal window settings using a circular ROI at the following sites: main pulmonary artery (PA) at its bifurcation level, thoracal aorta (TA) at the level of MPA bifurcation,portal vein (PV) at porta hepatis, left and right hepatic lobe, and if present, thickened pleura (>2 mm) at the level with the most intense enhancement. Respective normalized enhancement values were also calculated. Contrast-related artifacts were graded and qualitative evaluation of mediastinal lymph nodes was performed by both reviewers independently. Background noise was measured and contrast-to-noise ratios (CNRs) of the liver and TA were calculated. While enhancement of thoracic vessels and normalised MPA enhancement did not differ significantly between both groups (p > 0.05), enhancement and normalised enhancement of pleura, liver parenchyma and PV was significantly greater in group B (p < 0.001). Perivenous artifacts limiting evaluation were less frequent in group B than in A and mediastinal lymph nodes were judged to be evaluated worse in group A than in group B with an excellent agreement between both observers. No significant difference was detected in CNRTA (p = 0.633), whereas CNR liver was higher in group B (p < 0.001). Our split-bolus chest CT injection protocol enables simultaneous enhancement for both vascular structures and soft tissues, and thus, might raise diagnostic confidence without the need of multiple acquisitions. We think that this CT protocol might also be a promising alternative in lung cancer staging, where combined contrast-enhanced CT of the chest and abdomen is indicated. We therefore suggest to further evaluate its diagnostic utility in this setting, in particular in comparison with a late delayed chest-upper abdominal CT imaging protocol.

Quantitative Analysis of Adipose Depots by Using Chest CT and Associations with All-Cause Mortality in Chronic Obstructive Pulmonary Disease: Longitudinal Analysis from MESArthritis Ancillary Study.

Background Obesity and sarcopenia are associated with mortality in chronic obstructive pulmonary disease (COPD). Routine chest CT examinations may allow assessment of obesity and sarcopenia by soft-tissue markers for predicting risks of mortality. Purpose To investigate associations between soft-tissue markers subcutaneous adipose tissue (SAT), intermuscular adipose tissue (IMAT), and pectoralis muscle (PM) index from chest CT with mortality in participants with COPD. Materials and Methods In this secondary analysis of a prospectively enrolled cohort from the Multi-Ethnic Study of Atherosclerosis, participants with available chest CT in 2010-2012 were included. CT examinations were analyzed to determine SAT, IMAT (within PM), and PM areas. The spirometry evaluations were used to establish COPD diagnosis. Mortality data were extracted from the National Death Index (April 2010 to December 2017). The correlations of the soft-tissue markers with fat mass index were studied. The associations of these markers and risks of mortality in participants with COPD were assessed by using Cox proportional-hazard models adjusted for confounders. Results Among 2994 participants who were included (mean age, 69 years ± 9 [standard deviation]; 1551 women), 265 had COPD (9%; mean age, 72 years ± 9; 162 men) and 49 participants with COPD (18%) died during follow-up. The SAT, IMAT, and PM areas had moderate-to-excellent reliabilities (intraclass correlation coefficient, 0.88-0.99). In the 2994 participants, the SAT (ρ = 0.80; 95% CI: 0.78, 0.81; P < .001) and IMAT indexes (ρ = 0.37; 95% CI: 0.34, 0.41; P < .001) were correlated with fat mass index. Those with COPD and higher SAT index had lower risks of mortality (hazard ratio, 0.2; 95% CI: 0.1, 0.4; P < .001, per doubling), whereas a higher IMAT index was associated with a higher risk of mortality (hazard ratio, 1.4; 95% CI: 1.0, 1.9; P = .04, per doubling). Conclusion Soft-tissue markers were reliably obtained by using chest CT performed for lung assessment. In participants with chronic obstructive pulmonary disease, a high intermuscular adipose tissue index was associated with a higher risk of mortality than was a high subcutaneous adipose tissue index. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Sverzellati and Cademartiri in this issue.

Clinical study of 34 patients with cytomegalovirus pneumonia after allogeneic hematopoietic stem cell transplantation

目的分析异基因造血干细胞移植（allo-HSCT）后巨细胞病毒（CMV）肺炎的临床特点及预后。方法对2016年3月1日至2019年6月30日在上海市第一人民医院血液科接受allo-HSCT后并发CMV肺炎的患者进行回顾性分析。结果①全部411例allo-HSCT患者中，34例（8.3％）移植后发生CMV肺炎，其中男18例，女16例，中位年龄32（8～62）岁；急性髓系白血病14例，急性淋巴细胞白血病10例，骨髓增生异常综合征5例，非霍奇金淋巴瘤3例，再生障碍性贫血2例。②CMV肺炎中位发病时间为移植后53（36～506）d，主要症状为咳嗽（26例，76.5％）、发热（23例，67.6％）及气促（14例，41.2％），仅17.6％（6/34）的患者有咯痰，2例（5.9％）患者早期无明显症状而在常规胸部CT检查时发现。28例（82.4％）患者的影像学表现为小叶中心结节、弥漫毛玻璃影等典型间质性肺炎改变，6例（17.6％）表现为斑片、结节以及实变样不典型影像学改变。③26例（76.5％）患者血浆CMV-DNA阳性，拷贝数低于同期BALF检测结果［1.70×107（5.44×105～4.45×109）拷贝/L对1.45×108（1.10×107～1.10×1011）拷贝/L，P＝0.004］。④13例（38.2％）CMV肺炎患者合并其他下呼吸道病原体感染（真菌10株，细菌6株，腺病毒1株）。⑤所有患者中位随访时间12.8（0.4～46.5）个月，总生存率为58.82％，年龄≥40岁、接受高流量通气是CMV肺炎患者独立预后不良因素（P＝0.049，P＝0.009）。结论气管镜肺泡灌洗液检测有助于提升allo-HSCT后CMV肺炎病原学诊断的准确性。年龄≥40岁及接受高流量通气是CMV肺炎患者独立预后不良因素。

Predicting Atrial Fibrillation from Automated Measurements of Left Atrial Volume Using Routine Chest CT Examination: Overlooked and Underrecognized Risk Factors.

Predicting Atrial Fibrillation from Automated Measurements of Left Atrial Volume Using Routine Chest CT Examination: Overlooked and Underrecognized Risk Factors.

CT radiation dose optimization and reduction for routine head, chest and abdominal CT examination

CT radiation dose optimization and reduction for routine head, chest and abdominal CT examination

An efficacy analysis of whole-body magnetic resonance imaging in the diagnosis and follow-up of polymyositis and dermatomyositis.

ObjectivesTo evaluate the value of whole-body magnetic resonance imaging (WBMRI) in diagnosing muscular and extra muscular lesions in patients with polymyositis (PM) and dermatomyositis (DM).MethodsA retrospective analysis of WBMRI data from PM/DM patients who met the Bohan and Peter diagnostic criteria was performed. X2 test was used to compare the rate of positive diagnosis of newly diagnosed patients using WBMRI, serum creatine kinase test, and EMG. McNemar test was used to compare the performance of WBMRI and chest CT in detecting interstitial lung disease (ILD).ResultsThe study included 129 patients (30 PM cases and 99 DM cases). Of them, 81.4% (105/129) showed a visible inflammatory muscular edema on their WBMRI; 29.5% (38/129) had varying degrees of fatty infiltration (9 cases with clear muscular atrophy). Of the 66 newly diagnosed patients, the positive rates of WBMRI, muscle biopsy, serum creatine kinase test and EMG were 86.4% (57/66), 92.4% (61/66), 71.2% (47/66) and 71.1% (32/45), respectively. There was no significant difference in the positive rates between WBMRI and muscle biopsy (X2 = 1.28, P = 0.258). The WBMRI had a higher positive rate than both serum creatine kinase test (X2 = 4.53, P = 0.033) and EMG (X2 = 3.92, P = 0.047). In addition to muscular changes, WBMRI also detected interstitial lung disease (ILD) in 38 cases (29.5%), osteonecrosis in 15 cases (11.6%), and neoplastic lesions (5 malignant; 7 benign) in 12 cases (9.3%). Of the 61 patients who underwent routine chest CT examinations, the WBMRI and CT revealed ILD in 29 cases and 35 cases respectively. There was no significant difference in the sensitivity between WBMRI and CT (p = 0.146).ConclusionsWBMRI is a sensitive, non-invasive and efficient imaging method. It comprehensively displays the extent of muscular involvement in PM/DM patients, and it has the ability to diagnose other associated extra muscular diseases, such as ILD and systemic malignancy. WBMRI can also help screen steroid-induced osteonecrosis.

Coronary calcium screening with dual-source CT: reliability of ungated, high-pitch chest CT in comparison with dedicated calcium-scoring CT.

To investigate the reliability of ungated, high-pitch dual-source CT for coronary artery calcium (CAC) screening. One hundred and eighty-five smokers underwent a dual-source CT examination with acquisition of two sets of images during the same session: (a) ungated, high-pitch and high-temporal resolution acquisition over the entire thorax (i.e., chest CT); (b) prospectively ECG-triggered acquisition over the cardiac cavities (i.e., cardiac CT). Sensitivity and specificity of chest CT for detecting positive CAC scores were 96.4% and 100%, respectively. There was excellent inter-technique agreement for determining the quantitative CAC score (ICC = 0.986). The mean difference between the two techniques was 11.27, representing 1.81% of the average of the two techniques. The inter-technique agreement for categorizing patients into the four ranks of severity was excellent (weighted kappa = 0.95; 95% CI 0.93-0.98). The inter-technique differences for quantitative CAC scores did not correlate with BMI (r = 0.05, p = 0.575) or heart rate (r = -0.06, p = 0.95); 87.2% of them were explained by differences at the level of the right coronary artery (RCA: 0.8718; LAD: 0.1008; LCx: 0.0139; LM: 0.0136). Ungated, high-pitch dual-source CT is a reliable imaging mode for CAC screening in the conditions of routine chest CT examinations. • CAC is an independent risk factor for major cardiac events. • ECG-gated techniques are the reference standard for calcium scoring. • Great interest is directed toward calcium scoring on non-gated chest CT examinations. • Reliable calcium scoring can be obtained with dual-source CT in a high-pitch mode.

Distribution of the radiation dose in multislice computer tomography of the chest – phantom study

SummaryBackgroundThe most commonly used form of reporting doses in multislice computed tomography involves a CT dose index per slice and dose-length product for the whole series. The purpose of this study was to analyze the actual dose distribution in routine chest CT examination protocols using an antropomorphic phantom.Material/MethodsWe included in the analysis readings from a phantom filled with thermoluminescent detectors (Art Phantom Canberra) during routine chest CT examinations (64 MDCT TK LIGHT SPEED GE Medical System) performed using three protocols: low-dose, helical and angio-CT.ResultsMean dose values (mSv) reported from anterior parts of the phantom sections in low-dose/helical/angio-CT protocols were as follows: 3.74; 16.95; 30.17; from central parts: 3.18; 14.15; 26.71; from posterior parts: 3.01; 12.47; 24.98 respectively. Correlation coefficients for mean doses registered in anterior parts of the phantom between low-dose/helical, low-dose/angio-CT and helical/angio-CT protocols were 0.49; 0.63; 0.36; from central parts: 0.73; 0.66; 0.83, while in posterior parts values were as follows: 0.06; 0.21; 0.57.ConclusionsThe greatest doses were recorded in anterior parts of all phantom sections in all protocols in reference to largest doses absorbed in the anterior part of the chest during CT examination. The doses were decreasing from anterior to posterior parts of all sections. In the long axis of the phantom, in all protocols, lower doses were measured in the upper part of the phantom and at the very lowest part.

Correlation between Measured and Visual Scoring of Coronary Artery Calcification

Coronary artery calcification (CAC) is a well-known marker of subclinical coronary atherosclerosis, which is always detectable in non ECG-gated routine chest CT examinations, and its visual estimation is correlated to clinical outcomes. Agatston scoring is not routinely performed on these examinations. We sought to validate a visual scoring scheme we derived against ECG-gated CT’s and compare our system with another previously published visual scoring scheme in a different cohort of lung cancer screening participants. 50 COPDGene participants received, regular dose full inspiration (non-gated high mA), and low dose expiration CT (non-gated low mA) and ECG-gated CT’s at the same time. CAC was visually scored by 3 readers using our total visual scoring (TVS) method and compared to the Agatston score. The second portion of the study involved visual and Agatston scoring of a larger sample of 198 lung cancer screening patients, comparing visual scoring described by Shemesh et. al. and our TVS method. For the COPDGene participants, scores were highly correlated among readers (all ICC≥0.92), between the ECG-gated CT, non-gated high mA CT, and the non-gated low dose CT (all p<0.001), and with the Agatston score (all ICC≥0.90). For the cancer screening cohort there was very good agreement of our system and Shemesh scores. Correlations between reader scores, our system, Shemesh scores, and Agatston scores were also very good, ranging from 0.81-0.96. We derived cutoff values corresponding to Agatston risk quartiles for our system and Shemesh. There was excellent correlation of visual scoring with Agatston scoring on ECG-gated and non-gated CT. In lung cancer screening CT’s both ours and Shemesh visual scoring correlated well with Agatston scores and with each other. Visual scoring may predict clinically significant CAC in major Agatston categories.

Pertinent reportable incidental cardiac findings on chest CT without electrocardiography gating: review of 268 consecutive cases

Pertinent reportable cardiac findings on non-electrocardiography (ECG)-gated chest CT examinations have become easier to detect given recent advancements in multidetector CT technology. However, those findings are easily overlooked on routine chest CT without ECG gating given residual inherent cardiac motion artifact and non-cardiac indications. To describe and quantify the types of pertinent reportable cardiac findings that can be detected on chest CT examinations without ECG gating and evaluate how often they were reported. Two radiologists retrospectively reviewed (blinded to the original interpretation) 268 consecutive routine adult chest CT examinations without ECG gating for the presence of pertinent reportable cardiac findings. Retrospective interpretations were then compared with the original radiological reports. One hundred and sixty-three patients (61%) had pertinent reportable cardiac findings. The findings encountered included: coronary artery disease (n = 131; 80.0%), coronary artery bypass grafts (n = 10; 6.1%), left ventricular aneurysm (n = 1; 0.6%), valve calcification (n = 131; 80.0%), valve repair/replacement (n = 5; 3.1%), pericardial effusion (n = 33; 20.2%), left atrial appendage thrombus (n = 1; 0.6%), cardiac mass (n = 1; 0.6%), and cardiac chamber enlargement (n = 29; 17.8%). On the original radiological reports 22.3% of the pertinent reportable cardiac findings, detected by the two radiologists retrospectively, were not reported. Detection of pertinent reportable cardiac findings on routine chest CT examinations without ECG gating is possible. The high volume of chest CT examinations without ECG gating represents an opportunity for radiologists to comment on the presence or absence of cardiac disease which may influence future clinical decisions.

Dose to Radiosensitive Organs During Routine Chest CT: Effects of Tube Current Modulation

The aims of this study were to estimate the dose to radiosensitive organs (glandular breast and lung) in patients of various sizes undergoing routine chest CT examinations with and without tube current modulation; to quantify the effect of tube current modulation on organ dose; and to investigate the relation between patient size and organ dose to breast and lung resulting from chest CT examinations. Thirty voxelized models generated from images of patients were extended to include lung contours and were used to represent a cohort of women of various sizes. Monte Carlo simulation-based virtual MDCT scanners had been used in a previous study to estimate breast dose from simulations of a fixed-tube-current and a tube current-modulated chest CT examinations of each patient model. In this study, lung doses were estimated for each simulated examination, and the percentage organ dose reduction attributed to tube current modulation was correlated with patient size for both glandular breast and lung tissues. The average radiation dose to lung tissue from a chest CT scan obtained with fixed tube current was 23 mGy. The use of tube current modulation reduced the lung dose an average of 16%. Reductions in organ dose (up to 56% for lung) due to tube current modulation were more substantial among smaller patients than larger. For some larger patients, use of tube current modulation for chest CT resulted in an increase in organ dose to the lung as high as 33%. For chest CT, lung dose and breast dose estimates had similar correlations with patient size. On average the two organs receive approximately the same dose effects from tube current modulation. The dose to radiosensitive organs during fixed-tube-current and tube current-modulated chest CT can be estimated on the basis of patient size. Organ dose generally decreases with the use of tube current-modulated acquisition, but patient size can directly affect the dose reduction achieved.

Voluminous post-traumatic mediastinal haematoma: late presentation in DEA

Mediastinal haematoma in the settings of blunt chest trauma can produce potentially serious problems. Nonaortic sources include disruption of arch vessels, rupture of small mediastinal veins, fractures of ribs/sternum and injury to the intercostal and internal thoracic vessels. Rupture of the aorta and great vessels is less frequent. Mediastinal haematoma presents a dual threat to haemodynamic stability, both as source of blood loss and because of compression of vascular structures such as the heart and pulmonary arteries. The case presented here tells about a patient who was initially in good conditions and haemodynamically stable, with no radiologic abnormalities. Some hours later he developed chest pain with hypotension due to sudden growth of large mediastinal haematoma. Multiphase multi-detector CT (MDCT) in our case allowed prompt detection of active bleeding in the arterial phase, a specific sign of arterial injury, with cardiac tamponade, which required immediate surgical treatment. MDCT is commonly considered the gold standard in severe thoracic trauma. Improvements in CT scanner technology have markedly shortened scanning times and now provide cardiac and vessels images of high quality during routine chest CT examinations.

Diagnóstico casual de tromboembolismo pulmonar: descripción de las características clínicas y radiológicas y su evolución

To evaluate the cases of pulmonary embolism (PE) detected incidentally in our hospital, the associated risk factors, clinical and radiological characteristics, and evolution. We retrospectively reviewed the reports of routine contrast-enhanced chest CT examinations performed during a 19-month period to detect cases in which PE was diagnosed incidentally. We found 18 cases of incidentally diagnosed PE and we reviewed the clinical histories and CT images of these patients to analyze the risk factors, clinical presentation, radiological characteristics, treatment, and evolution of PE in these cases. We found 18 patients (9 men and 9 women; mean age: 61 years) with incidentally detected PE. The main risk factor for developing PE was the presence of a neoplasm (n = 16). No PE-related symptoms were present in 12 patients. A multidetector CT scanner was used for the examination in most cases (n = 16). PE was centrally located in 16 patients. Five patients were not treated with anticoagulation and no embolic events occurred in these patients. Two of the remaining patients died because of PE. The incidental finding of PE can be common in oncological patients. Multidetector CT probably has a greater capacity for the incidental detection of PE in these patients. The outcome of incidentally detected PE can vary from death to remaining stable to spontaneous resolution.

TU‐C‐L100J‐09: CT Doses: Changes in the Last Twenty‐Five Years

Purpose. To quantify how CT patient doses, and the corresponding scan times, have changed over the last 25 years. Method. We analyzed data for five generations of CT scanners from one vendor (GE), ranging from the 9800 single slice scanner without slip ring technology used in the early 1980s to a 64 slice VCT, the current state of the art. We determined values of CTDIair and CTDIw at a constant kV/mAs. Effective doses were performed for a standard 32 cm chest CT examination performed at 120 kV using contiguous axial scanning on the 9800, and a pitch of 1 on the VCT. Scan times were computed assuming (contiguous) axial images with a 5 mm thickness.Results. CTDIair of a VCT scanner (30 mGy/100 mAs) is 12% higher than that of a 9800 scanner, whereas the corresponding body VCT CTDIw (9.5 mGy/100 mAs) is 53% higher. The increased doses on modern scanners are a result of reduced focus‐isocenter distances to accommodate faster rotation speeds, changes in beam shaping filters, and overbeaming used on MSCT scanners. Patient effective doses for a routine chest CT examination are 5 mSv/100 mAs on a VCT and 3.2 mSv/100 mAs on a 9800. Acquisition of 64 axial images for a routine chest CT in the early 1980's took ∼5 minutes, whereas modern scanners cover the same volume in only 8 x‐ray tube rotations taking ∼3 seconds.Conclusion. Over the last 25 years, normalized CT patient doses (i.e., per unit mAs) have increased by ∼50%, whereas image acquisition times have been reduced by two orders of magnitude.

Malignant Right Coronary Artery Anomaly Simulated by Motion Artifacts on MDCT

The aim of our study was to determine the prevalence of anomalous right coronary artery imitation due to motion artifacts in MDCT. Routine chest MDCT for reasons other than cardiac or vascular imaging is usually performed using breath-hold technique but without retrospective ECG gating and consequently yields pulsating motion artifacts. A possible artifact in front of the aortic root imitates an anomalous right coronary artery originating from the left posterior sinus. This course of the right coronary artery is considered a malignant variant and raises the question of far-reaching consequences such as a bypass operation. We performed a prospective study involving 355 patients undergoing routine chest CT examinations. To determine the prevalence of anomalous right coronary artery imitation caused by this motion artifact, all images were evaluated prospectively by an experienced radiologist. Twenty-one patients (5.9%) were suspected of having a malignant variant of the right coronary artery. However, in all patients prior chest CT or additional coronary MR angiography showed a normal origin of the right coronary artery. Routine chest MDCT without retrospective ECG gating may produce artifacts around the aorta simulating a malignant variant of the right coronary artery. Considering the low incidence of this malignant interarterial variant, the need for routine chest CT examinations combined with ECG gating and further workup can be disputed from an economic point of view. This artifact should be known to avoid unnecessary further examinations.

Desmoplastic small round cell tumour of the pleura: a case report with unusual follow-up

In 1994 a 19-year-old woman presented with a few weeks history of back ache. Routine chest X-ray and CT examination revealed a lesion originating from the parietal pleura and destroying the ribs. The tumour was resected during thoracotomy. The histological examination raised the possibility of atypical carcinoid tumour. One year later the tumour recurred. After its re-resection, the patient received radiotherapy. Three years after the initial presentation multiple pulmonary metastases developed. The patient was treated with chemotherapy, receiving vincristine, epi-adriamycin and cyclophosphamide in 8 cycles, which resulted in complete remission. Between 1998 and 1999 progressions and partial remissions were observed, while the patient received further cycles of chemotherapy. Histological revision was performed in 1999 and a final diagnosis of desmoplastic small round cell tumour of the pleura was made. Immunohistochemically co-expression of cytokeratin, vimentin, desmin, and NSE was observed. The patient died in June 2000. The whole follow-up period was 76 months. We thought this case to be worth for presentation because this unusual long survival, which was probably due to the aggressive complex anticancer treatment.

Individually adapted examination protocols for reduction of radiation exposure in chest CT.

To develop a simple directive for the reduction of radiation exposure without loss of diagnostic information in routine chest CT examinations. Two hundred fifty adult patients (164 male, 86 female) were entered into a prospective trial. All examinations were performed with a multislice CT technique (Somatom Volume Zoom, Siemens). Four groups of 50 patients each were scanned with patient-related specific parameters: individual mA-s values were derived from the estimated body weight: kilograms + 10, +/- 0, - 10, and - 20 mAs. The results were compared with those of 50 patients who were examined by a standard chest protocol by using the parameters 120 mAs and 140 kV. All other parameters including the tube voltage were kept constant. Subjective image quality was rated on a three-point scale: 1 = excellent, 2 = fair, 3 = nondiagnostic. In addition, objective criteria based on signal-to-noise measurements were assessed by using a region-of-interest methodology. Image quality was sufficient in all cases. Mean subjective gradings of image quality, based on soft-tissue window settings, were 1.1 for the 120-mAs protocol, 1.1 for the (body weight [kg] + 10) mAs protocol, 1.1 for the (body weight [kg] +/- 0) mAs protocol, 1.3 for the (body weight [kg] - 10) mAs protocol, and 1.2 for the (body weight [kg] - 20) mAs protocol. Objective criteria based on noise measurements showed mean +/- standard deviation values of 5.7 +/- 0.8 Hounsfield units (HU) for the 120-mAs protocol. For the reduced-dose protocols, values were calculated as 7.6 +/- 1.2 HU (group + 10), 7.9 +/- 1.3 HU (group +/- 0), 8.7 +/- 1.2 HU (group - 10), and finally 9.1 +/- 1.3 HU (group - 20). The best correlation for an entire subgroup was achieved with the - 10 protocol (body weight [kg] - 10) mAs, with nearly constant noise related to body weight in all patients. By deriving mAs values from body weight estimation, an individually adapted protocol for chest CT can be recommended and easily employed in a clinical setting. With an adaptation of the tube current-time product based on the estimated body weight of the patient - 10 (body weight [kg] - 10 mAs), a well-balanced examination without significant loss of information, even in soft-tissue window settings, can be performed with this particular scanner. For this adapted mAs protocol, a mean reduction of radiation exposure of 45% was achievable, compared with the standard protocol. A maximum decrease per case down to 31 mAs was obtained, without relevant loss of image quality. Therefore, for other types of CT scanners, analogous protocols may be adapted.

Effective doses to patients undergoing thoracic computed tomography examinations.

The purpose of this study was to investigate how x-ray technique factors and effective doses vary with patient size in chest CT examinations. Technique factors (kVp, mAs, section thickness, and number of sections) were recorded for 44 patients who underwent a routine chest CT examination. Patient weights were recorded together with dimensions and mean Hounsfield unit values obtained from representative axial CT images. The total mass of directly irradiated patient was modeled as a cylinder of water to permit the computation of the mean patient dose and total energy imparted for each chest CT examination. Computed values of energy imparted during the chest CT examination were converted into effective doses taking into account the patient weight. Patient weights ranged from 4.5 to 127 kg, and half the patients in this study were children under 18 years of age. All scans were performed at 120 kVp with a 1 s scan time. The selected tube current showed no correlation with patient weight (r2=0.06), indicating that chest CT examination protocols do not take into account for the size of the patient. Energy imparted increased with increasing patient weight, with values of energy imparted for 10 and 70 kg patients being 85 and 310 mJ, respectively. The effective dose showed an inverse correlation with increasing patient weight, however, with values of effective dose for 10 and 70 kg patients being 9.6 and 5.4 mSv, respectively. Current CT technique factors (kVp/mAs) used to perform chest CT examinations result in relatively high patient doses, which could be reduced by adjusting technique factors based on patient size.