Interobserver agreement between on-call radiology residents and radiology specialists in the diagnosis of pulmonary embolism using computed tomography pulmonary angiography.

OBJECTIVE: The objective of this study was to assess the interobserver agreement between on-call radiology residents and radiology specialists in the evaluation of pulmonary embolism (PE) using computed tomographic pulmonary angiography (CTPA). MATERIALS AND METHODS: Single center, prospective cohort study of 119 consecutive inpatients and outpatients with clinically suspected PE in whom CTPA was performed during out-of-office hours and weekends. The on-call radiology resident interpreted the CTPA for the presence of PE. An experienced radiology specialist, without knowledge of earlier reading, reviewed the CTPA the following morning. In discordant cases, a consensus reading was conducted. The radiology specialists' assessment and the consensus reading in case of discordance were considered as the gold standard. RESULTS: Five CTPA studies were excluded from the analysis. In the remaining cases, radiology residents and radiology specialists agreed on the interpretations of CTPAs (no PE vs PE present) in 106 (93%) of the 114 cases, with a kappa value of 0.84 (95% confidence interval, 0.74-0.95). The consensus reading equally disagreed with both radiology resident and radiology specialist in 8 (7%) of the 114 discordant cases. Seven out of 8 discordant cases had suboptimal scan quality. CONCLUSIONS: The assessment of CTPA in patients with suspected PE by radiology residents seems reliable during out-of-office hours.

Screening for distant metastases in head and neck cancer patients by chest CT or whole body FDG-PET: a prospective multicenter trial.

BACKGROUND AND PURPOSE: The aim of the study was to define the added value of whole body FDG-PET in screening for distant metastases in patients with head and neck squamous cell carcinoma and risk factors. MATERIALS AND METHODS: In a multi-center prospective study between 1998 and 2003, 145 consecutive HNSCC patients with risk factors for distant metastases underwent chest CT and whole body FDG-PET for screening of distant metastases. The data of 92 evaluable patients who developed distant metastases or who had a follow-up of at least 12 months were analyzed. Besides their performance in clinical practice, the operational characteristics of PET and CT using ROC analyses were investigated. RESULTS: Pretreatment screening identified distant metastases in 19 patients (21%). FDG-PET had a higher sensitivity (53% vs. 37%) and positive predictive value (80% vs. 75%) than CT. The combination of CT and FDG-PET had the highest sensitivity (63%). The ROC analyses of the five point ordinal scales revealed that the "area under the curve" (AUC) of FDG-PET was significantly higher as compared to CT. CONCLUSION: In HNSCC patients with risk factors, pretreatment screening for distant metastases by chest CT is improved by FDG-PET.

CT detected indeterminate pulmonary nodules in a chemoprevention trial of fluticasone.

INTRODUCTION: In animal models of lung carcinogenesis, inhaled corticosteroids appear to reduce the number of new lung tumors. In a trial of budesonide in smokers with bronchial dysplasia, the proportion of indeterminate CT detected pulmonary nodules that resolved was larger in the treatment group. We performed a secondary analysis of CT data of subjects at risk of lung cancer enrolled in a chemoprevention trial of fluticasone. METHODS: Subjects with bronchial squamous metaplasia or dysplasia had a baseline chest CT scan. They were randomized to fluticasone or a placebo. After 6 months a repeat CT was performed and the change in number and size of nodules was evaluated. RESULTS: Two hundred and one subjects were screened. Of the 108 volunteers included in the study, 74 were male, mean age was 53 years and mean number of pack years 48. Baseline: 35 subjects had 91 nodules in total, 62% <4mm. In the fluticasone arm more subjects had a decrease and fewer had an increase in number of nodules, however this trend did not reach statistical significance. CONCLUSION: In this preliminary study there was a tendency of nodules to resolve, however, studies with CT detected nodules as inclusion criterion are needed.

Prognostic relevance of response evaluation using [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography in patients with locally advanced non-small-cell lung cancer.

PURPOSE: The objective of this study was to determine the accuracy of (early) response measurements using [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG PET) with respect to survival of patients with stage IIIA-N2 non-small-cell lung cancer (NSCLC) undergoing induction chemotherapy (IC), with a comparative analysis of PET methods. PATIENTS AND METHODS: In a prospective multicenter study, PET was performed in patients before IC and after one and three cycles. Computed tomography (CT) was performed before and after IC. Glucose consumption (metabolic rate of glucose [MRglu]) was measured using Patlak graphical analysis and correlated with simplified methods. Mediastinal lymph node (MLN) status was assessed visually. Cox proportional hazards analysis was used to determine the prognostic relevance of CT and PET measures of response with respect to survival. RESULTS: Complete PET data sets were available in 47 patients. Median survival was 21 months. MLN status after IC by PET predicted survival (hazard ratio [HR], 2.33; 95% CI, 1.04 to 5.22; P = .04) in contrast with CT (HR, 1.87; 95% CI, 0.81 to 4.30; P = .14). Residual MRglu after IC proved to be the best prognostic factor (HR, 1.95; 95% CI, 1.28 to 2.97; P = .002). Multivariate stepwise analysis showed that PET identified prognostically different strata in patients considered responsive according to CT. Residual MRglu after one cycle selected patients with different outcomes (HR, 2.04; 95% CI, 1.18 to 3.52; P = .01). Simplified quantitative 18FDG PET methods were correlated with Patlak graphical analysis during and after therapy (r > or = 0.90). CONCLUSION: 18FDG PET has additional value over CT in monitoring response to IC in patients with stage IIIA-N2 NSCLC, and it seems feasible to predict survival early during IC. Simple semiquantitative and complex PET methods perform equally well.

Screening for distant metastases in patients with head and neck cancer: is there a role for (18)FDG-PET?

The detection of distant metastases and second primary tumours at the time of initial evaluation changes the prognosis and influences the selection of treatment modality in patients with HNSCC. Until recently chest CT was the single most effective test to screen for distant metastases in HNSCC patients. In this observational cohort study we prospectively compared the yield of whole body (18)FDG-PET and chest CT to detect distant metastases and synchronous primary tumours. The results of whole body (18)FDG-PET and chest CT were analysed in 34 consecutive HNSCC patients with previously established risk factors for the presence of distant metastases. Four patients were diagnosed with distant metastases or second primary tumours: CT as well as (18)FDG-PET identified one patient with lung metastases and another with primary lung cancer. In addition, (18)FDG-PET detected second primary tumours in two patients (hepatocellular carcinoma and abdominal adenocarcinoma). However increased uptake sites at (18)FDG-PET in lung, liver and pelvis in five patients were not confirmed by other imaging modalities. The added value of whole body (18)FDG-PET versus chest CT was to identify unknown malignancy in 6% of the patients. Confirmation of positive (18)FDG-PET findings is feasible and necessary.

Clinical prediction model to characterize pulmonary nodules: validation and added value of 18F-fluorodeoxyglucose positron emission tomography.

BACKGROUND: The added value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning as a function of pretest risk assessment in indeterminate pulmonary nodules is still unclear. OBJECTIVE: To obtain an external validation of the prediction model according to Swensen and colleagues, and to quantify the potential added value of FDG-PET scanning as a function of its operating characteristics in relation to this prediction model, in a population of patients with radiologically indeterminate pulmonary nodules. DESIGN, SETTING, AND PATIENTS: Between August 1997 and March 2001, all patients with an indeterminate solitary pulmonary nodule who had been referred for FDG-PET scanning were retrospectively identified from the database of the PET center at the VU University Medical Center. RESULTS: One hundred six patients were eligible for the study, and 61 patients (57%) proved to have malignant nodules. The goodness-of-fit statistic for the model (according to Swensen) indicated that the observed proportion of malignancies did not differ from the predicted proportion (p = 0.46). PET scan results, which were classified using the 4-point intensity scale reading, yielded an area under the evaluated receiver operating characteristic curve of 0.88 (95% confidence interval [CI], 0.77 to 0.91). The estimated difference of 0.095 (95% CI, -0.003 to 0.193) between the PET scan results classified using the 4-point intensity scale reading and the area under the curve (AUC) from the Swensen prediction was not significant (p = 0.058). The PET scan results, when added to the predicted probability calculated by the Swensen model, improves the AUC by 13.6% (95% CI, 6 to 21; p = 0.0003). CONCLUSION: The clinical prediction model of Swensen et al was proven to have external validity. However, especially in the lower range of its estimates, the model may underestimate the actual probability of malignancy. The combination of visually read FDG-PET scans and pretest factors appears to yield the best accuracy.

Screening for distant metastases in patients with head and neck cancer: is chest computed tomography sufficient?

OBJECTIVES/HYPOTHESIS: The detection of distant metastases during screening influences the choice of treatment in patients with head and neck squamous cell carcinoma. A previous study in the authors' institution showed that chest computed tomography (CT) scan was the most important screening technique. Different clinical risk factors in patients with head and neck squamous cell carcinoma for the development of distant metastases were identified. STUDY DESIGN: Retrospective cohort study. METHODS: To evaluate the authors' diagnostic strategy, the accuracy of screening for distant metastases with chest CT in 109 consecutive patients with head and neck squamous cell carcinoma with risk factors between 1997 and 2000 was retrospectively analyzed. RESULTS: Preoperative screening with CT revealed 20 patients (18%) with lung metastases and 1 liver metastasis. Despite negative screening with chest CT, 9 (11%) patients developed distant metastases within 12 months during follow-up. Sensitivity of the chest CT was 73%; the specificity was 80%. CONCLUSION: Although chest CT frequently detects distant metastases, there seems to be a need for a more sensitive and whole-body screening technique.

Positron emission tomography using 2-deoxy-2-[18F]-fluoro-D-glucose for response monitoring in locally advanced gastroesophageal cancer; a comparison of different analytical methods.

PURPOSE: To determine the ability of 2-deoxy-2-[18F]-fluoro-D-glucose (FDG) positron emission tomography (PET) to monitor response in locally advanced gastroesophageal cancer (LAGEC). Additionally, optimal FDG-PET methods for response monitoring were selected. PROCEDURES: Sequential dynamic FDG-PET scans were performed in 13 patients with LAGEC (T2-3N0-1M0-1a) treated with neoadjuvant cisplatin and gemcitabine plus granulocyte macrophage colony stimulating growth factor at a three weekly schedule. The standard FDG-PET method, nonlinear regression (NLR), was compared with computed tomography (CT), endoscopic-ultrasound (EUS), and histopathology as well as with 21 simplified analytical FDG-PET methods. RESULTS: Five out of 12 operated tumors responded histopathologically with less than 10% residual tumorcells (42%). These had a higher decrease in FDG uptake compared with nonresponders (P=0.008). Early (after two cycles) and late (after completed induction therapy) response evaluation showed a specificity of 86% and 100%, respectively, and a sensitivity of 100%. Both FDG-PET and EUS were superior to CT. From 21 methods analyzing FDG uptake, the quantitative Patlak analysis, the simplified kinetic method (SKM), and the semiquantitative standardized uptake value corrected for bodyweight (SUV-BW) seemed to correlate best with NLR. CONCLUSIONS: FDG-PET reliably predicted response in LAGEC. FDG-PET measurements using Patlak analysis or the more clinical applicable SKM and SUV-BW were acceptable alternatives to NLR.

Lung density measurements in spontaneous pneumothorax demonstrate airtrapping.

PURPOSE: Idiopathic spontaneous pneumothorax (SP) is the result of leakage of air from the lung parenchyma through a ruptured visceral pleura into the pleural cavity. This rupture is thought to be caused by an increased pressure difference between parenchymal airspace and pleural cavity. We hypothesize that rather peripheral airway inflammation leads to obstruction with check valve phenomena and by that to airtrapping in the lung parenchyma, which precedes spontaneous pneumothorax. SETTING: University hospital. MATERIALS AND METHODS: Forty-one matched healthy volunteers (21 smokers and 20 nonsmokers), and 41 patients with SP (21 patients with and 20 patients without bullae) underwent spirometrically controlled high-resolution CT density measurements with automatic contour tracing at 10% and at 90% of vital capacity. RESULTS: Patients with SP showed lower mean lung density (MLD) values and higher percentages of Hounsfield units (HU) below - 900 HU (pixel index [PI]) compared to the healthy volunteers on expiratory scans. This enhanced airtrapping phenomenon is seen in both the SP lung (MLD, p = 002; PI, p = 0.01) and the contralateral lung (MLD, p = 0.009; PI, p = 0.05) compared to the control subjects. The difference with control subjects is independent of smoking behavior and bullae. CONCLUSIONS: Peripheral airway obstruction with airtrapping was found, and it is supposed to play an important role in the pathogenesis of spontaneous pneumothorax.

Bronchogenic cysts in adults: frequently mistaken for a solid mass on computed tomography.

BACKGROUND: Bronchogenic cysts are congenital malformations and are often detected in asymptomatic patients as an incidental finding. Growth can cause compression of airways and vessels, resulting in clinical symptoms and possible complications. On computed tomography (CT) scans, bronchogenic cysts frequently have the appearance of a solid tumor. We describe diagnostic strategy and management for patients with bronchogenic cysts. METHODS: Retrospective case study of 11 adults diagnosed with a bronchogenic cyst. The CT scan of all patients was revised and localization, size, Hounsfield Units (HU), and appearance (cystic or solid) of the lesions were reported. Lesions were arbitrarily considered cystic or solid when the radiographic density was below or above 20 HU, respectively. RESULTS: Eleven adults with a bronchogenic cyst were followed for at least 2 years after diagnosis. Eight of 11 detected lesions were judged as a solid lesion, based on the radiographic density (in HU) on CT images. Nine of 11 patients were treated by surgical resection. Two asymptomatic patients were not operated and remained asymptomatic without enlargement of the cysts during 2 years follow-up. Complications of resection were post-operative bleeding (n = 1), recurrent pneumothorax (n = 1), and recurrence of the cyst (n = 1). No mortality was observed. CONCLUSION: Bronchogenic cysts are frequently mistaken for a solid mass on CT scans. Further differentiation can be made by MRI or EUS when CT is inconclusive.

Interobserver variability in chest CT and whole body FDG-PET screening for distant metastases in head and neck cancer patients.

PURPOSE: The aim of the study was to assess the interobserver variability in chest computed tomography (CT) and whole body 2-deoxy-2-[(18)F]fluoro-D-glucose positron emission tomography (FDG-PET) screening for distant metastases in head and neck squamous cell carcinoma (HNSCC) patients. PROCEDURE: Chest CT and whole body FDG-PET of 69 HNSCC patients with high-risk factors who underwent screening for distant metastases were analyzed. All scans were independently read by two experienced radiologists or nuclear physicians who were blinded to the other examinations and follow-up results. RESULTS: A kappa of 0.516 was found for assessment of size on CT. Kappa values for origin and susceptibility of 0.406 and 0.512 for CT and 0.834 and 0.939 for PET were found, respectively. The overall conclusions had a kappa of 0.517-0.634 for CT and 0.820-1.000 for PET. CONCLUSIONS: In screening for distant metastases in HNSCC patients with high-risk factors, chest CT readings had a reasonable to substantial agreement, while PET readings showed an almost perfect agreement. These findings suggest that for optimal assessment in clinical practice, PET most often can be scored by one observer, but CT should probably more often be scored by different observers in consensus or combined with PET.

Subtraction-multiphase-CT unbeneficial for early detection of colorectal liver metastases.

PURPOSE: To assess the value of multiphase-subtraction-CT for early detection of colorectal-liver-metastases (CRLM). METHODS AND MATERIALS: In 50 patients suspected of CRLM a routine pre-operative 4-phase-CT-scan of the upper abdomen was obtained. All 12 possible image subtractions between two different phases were constructed applying 3D-image-registration to decrease distortion artefacts induced by differences in inspiration volume. Two experienced radiologists initially reviewed the conventional 4-phase-CT for malignant and/or benign appearing lesions and at least 1-month hereafter the same 4-phase-CT now including the subtracted images. The results were compared to histology reports or to a combination of surgical exploration and intraoperative ultrasound together with results from pre-operative PET and follow-up examinations. RESULTS: Although an additional number of 31 malignant appearing lesions were detected on the subtraction images, none proved to represent a true CRLM. Interobserver agreement (kappa) decreased from 0.627 (good) to 0.418 (fair). CONCLUSION: Adding linearly co-registered subtraction-CT images to a conventional 4-phase-CT protocol does not improve detection of CRLM.

Early detection of local RFA site recurrence using total liver volume perfusion CT initial experience.

RATIONALE AND OBJECTIVES: The aim of this study was to prospectively evaluate the feasibility of a novel total liver volume perfusion computed tomographic technique in demonstrating treatment-site recurrence of liver metastases after radiofrequency ablation (RFA). MATERIALS AND METHODS: Eleven patients considered to be at increased risk for local RFA-site tumor recurrence underwent both positron emission tomography (PET) and perfusion computed tomography (CTP): a 12-phase scan of the entire liver acquired before and 11 times after contrast injection. After coregistration, blood flow maps were created using the maximum slope method. RESULTS: In all cases, the CTP-derived blood flow maps fully paralleled the PET images in showing either the absence (nine of 13 lesions) or presence (four of 13 lesions) of local RFA-site recurrence. Marginal lesions with high hepatic arterial perfusion (>50 mL/min/100 g) and low portal venous perfusion (<10 mL/min/100 g) represented recurring vital tumor tissue (P < .05). CONCLUSION: Total liver volume CTP seems feasible for the detection and localization of treatment-site recurrence after RFA.

Initial bronchoscopic treatment for patients with intraluminal bronchial carcinoids.

OBJECTIVE: Carcinoid of the lung is considered low-grade malignancy, and less invasive treatment may therefore be considered. We analyzed the long-term outcome of initial bronchoscopic treatment in patients with intraluminal bronchial carcinoids. METHODS: Initial bronchoscopic treatment was applied to improve presurgical condition, to obtain tissue samples for proper histologic classification, and to enable less extensive parenchymal resection. For intraluminal bronchial carcinoid, complete tumor eradication with initial bronchoscopic treatment was attempted. High-resolution computed tomography in addition to bronchoscopy was used to determine intraluminal versus extraluminal tumor growth. Surgery followed in cases of atypical carcinoid, residue, or recurrence. RESULTS: Seventy-two patients, 43 of them female, have been treated (median age 47 years, range 16-80 years). Median follow-up has been 65 months (range 2-180 months). Fifty-seven (79%) had typical carcinoids and 15 (21%) had atypical carcinoids. Initial bronchoscopic treatment resulted in complete tumor eradication in 33 of 72 cases (46%), 30 typical and 3 atypical. Thirty-seven of 72 cases (51%), 11 atypical, required surgery (2 for late detected recurrences). Two patients had metastatic atypical carcinoid, 1 already at referral. Of the 6 deaths, 1 was tumor related. CONCLUSIONS: Initial bronchoscopic treatment is a potentially more tissue-sparing alternative than immediate surgical resection in patients with intraluminal bronchial carcinoids. For successful tumor eradication with initial bronchoscopic treatment in central carcinoids, assessment of intraluminal versus extraluminal growth may be of much more importance than histologic division between typical and atypical carcinoid. Disease-specific mortality is low, and long-term outcome has been excellent. Implementation of initial bronchoscopic treatment had no negative impact on surgical treatment outcome.

The performance of( 18)F-fluorodeoxyglucose positron emission tomography in small solitary pulmonary nodules.

Solitary pulmonary nodule (SPN, intraparenchymal lung mass <3 cm) is often a diagnostic challenge. This study was performed to evaluate the diagnostic accuracy of( 18)F-fluorodeoxyglucose positron emission tomography (FDG PET) in radiologically indeterminate SPN < or =10 mm on spiral CT. Between August 1997 and March 2001, we identified all patients with radiologically indeterminate SPNs < or =10 mm who were referred for FDG PET imaging at the VU University Medical Centre. All PET scans were retrospectively reviewed by an experienced nuclear medicine physician. PET was considered positive in cases with at least moderately enhanced focal uptake, and otherwise as negative. Lesions were considered benign on the basis of histology, no growth during 1.5 years or disappearance within at least 6 months. Thirty-five patients with 36 SPNs < or =10 mm in diameter at clinical presentation were identified (one patient had two metachronous lesions). In 13 of 14 malignant nodules and in two of 22 benign nodules, diagnosis was confirmed by histology. Prevalence of malignancy was 39%. PET imaging correctly identified 30 of 36 small lesions. One lesion proved to be false negative on PET (CT: 10 mm), and in five lesions, PET scans proved to be false positive. Specificity was 77% (17/22; 95% CI: 0.55-0.92), sensitivity 93% (13/14; 95% CI: 0.66-1.0), positive predictive value 72% (13/18; 95% CI: 0.46-0.90) and negative predictive value 94% (17/18; 95% CI: 0.73-1.0). This retrospective study suggests that FDG PET imaging could be a useful tool in differentiating benign from malignant SPNs < or =10 mm in diameter at clinical presentation. Such results may help in the design of larger prospective trials with structured clinical work-up.

Lung attenuation measurements in healthy young adults.

BACKGROUND: High-resolution computed tomography (HRCT) attenuation measurements may be more sensitive in finding early emphysematous changes in relatively young subjects than lung function measurements. OBJECTIVES: To define lung attenuation parameters in smokers and never-smokers. METHODS: A prospective comparative study in a university hospital setting was designed with 20 healthy smoking and 20 nonsmoking volunteers. Attenuation measurements on spirometrically controlled HRCT at three levels in the upper half of the lungs at 10% and 90% of vital capacity (VC10% and VD90%) were done, and lung function measurements were performed. RESULTS: Mean lung attenuation (MLD) and pixel index (PI) were correlated with lung function and smoking history. Small attenuation differences in the left and right lung were found but no sex-related differences. At main carina (MC) level, the PI was higher at VC90% (p < 0.0001) but lower at VC10% (p < 0.01) compared to the apex. Age correlated with attenuation parameters at VC10%, whereas for pack-years no correlation was found. There were attenuation correlations with VC (PI: R = 0.31, p < 0.05 at VC10%/90%), residual volume (MLD: R = -0.31, p < 0.05 at VC10%), and total lung capacity (PI: R = 0.31, p < 0.05 at VC10%/VC90%). CONCLUSIONS: Lung attenuation during inspiration was lower at the MC level than at the top, but higher on expiratory scans. No sex-related differences were found. Lung attenuation decreases with age on expiratory scans. This seemed to be of more importance than the amount of pack-years of smoking. A relationship with lung function parameters is not uniformly proven.