Ghosting of pulmonary nodules with respiratory motion: comparison of helical and conventional CT using an in vitro pediatric model

OBJECTIVE: The study was designed to compare helical CT with varying pitch and reconstruction intervals and conventional CT for revealing pulmonary nodules in a model that simulates respiratory motion in children. MATERIALS AND METHODS: CT scans were obtained in an experimental model with one nodule (3 or 10 mm) in each scan. One-second scans were obtained at rates of 10, 20, and 30 respirations per minute using conventional CT with 4-mm collimation and table incrementation and helical CT with 4-mm collimation and either 4-mm/sec (pitch, 1:1) or 8-mm/sec (pitch, 2:1) table speed. Reconstructions were at 1-, 2-, and 4-mm intervals for scans obtained using 4-mm/sec table speed and at 1- and 4-mm intervals for scans obtained using 8-mm/sec table speed. Images were independently reviewed by three radiologists who estimated the number of nodules on each image. RESULTS: Ghosting (depiction of more than one nodule in a study) was seen in 79%, 80%, and 75% of helical CT scans obtained with a 1:1 pitch using 1-, 2-, and 4-mm reconstruction intervals, respectively. By comparison, ghosting was seen in only 54% and 58% of helical CT scans with a 2:1 pitch using 1-mm reconstruction intervals and 4-mm reconstruction intervals, respectively, and in 56% of conventional CT scans (p < .0001). A single nodule was detected on all other scans, and at least one nodule was seen on all scans. CONCLUSION: Ghosting of nodules is common in this model. Ghosting was seen less often on conventional scans and helical scans with 2:1 pitch than it was on helical scans with 1:1 pitch. Nonetheless, ghosting was seen on more than 50% of all scans with each technique.     

Pulmonary nodules: effect of increased data sampling on detection with spiral CT and confidence in diagnosis

PURPOSE: To compare spiral computed tomography (CT) with interscan spacing of 4-5 mm versus 8-10 mm for detection rate and level of confidence in diagnosis of pulmonary nodules. MATERIALS AND METHODS: Four radiologists (two junior and two senior faculty members) retrospectively reviewed 67 spiral CT studies with one to six nodules per study. Every second image was masked, which resulted in 8-mm sections every 8 or 10 mm; then all images reconstructed every 4 or 5 mm were reviewed. Lesions were classified as definite, probable, or possible. RESULTS: Narrow interscan spacing yielded more lesions overall (583 vs 566, P < .025) and more definite lesions and fewer equivocal lesions (482 vs 431 and 101 vs 135, respectively; P < .055). The greatest effects were in the reduction of possible lesions (50 vs 88, P < .001) and in the reduction of false-positive diagnoses made by less experienced radiologists. CONCLUSION: Increased reconstruction frequency of spiral CT volume data sets improves detection of pulmonary nodules and enhances confidence in the diagnosis.     

Cardiorespiratory responses to acute hypoxemia in the chronically catheterized fetal llama at 0.7-0.9 of gestation

PURPOSE: To compare hard-copy digital chest radiographs obtained with a selenium-based system with wide-latitude asymmetric screen-film radiographs for detection of pulmonary nodules. MATERIALS AND METHODS: Fifty patients undergoing thoracic computed tomography (CT) for suspected pulmonary nodules were recruited to undergo both digital and screen-film posteroanterior (PA) and lateral chest radiography. Three chest radiologists blinded to the CT results independently reviewed each digital and screen-film radiograph, identified each nodule, and graded their confidence for its presence. RESULTS: Seventy-eight pulmonary nodules (mean diameter, 1.5 cm; range, 0.5-3.5 cm; 62 soft tissue, 16 calcified) were identified with CT in 34 patients, while 16 patients had clear lungs. The mean sensitivity for the detection of all nodules by all readers (PA and lateral) was 66% (95% Cl, 54%, 76%) for digital radiographs and 64% (95% Cl, 52%, 74%) for screen-film radiographs. Differences between the two techniques were not statistically significant (P > .05, Student t test). There was no difference in mean false-positive-true-positive ratios (PA, 0.35; lateral, 0.53) or positive predictive values (PA, 74%; lateral, 65%), and no significant difference (P > .05) was seen in mean reader confidence rating. CONCLUSION: In detecting pulmonary nodules, radiologists perform comparably with selenium-based digital and wide-latitude asymmetric screen-film radiographs.     

Variables affecting pulmonary nodule detection with computed tomography: evaluation with three-dimensional computer simulation

To meaningfully evaluate factors determining the overall accuracy of computed tomography (CT) for identifying pulmonary nodules, computer-generated nodules were superimposed on normal CT scans and interpreted independently by three experienced chest radiologists. Variables evaluated included nodule size, shape, number, density, location, edge characteristics, and relationship to adjacent vessels, as well as technical factors, including slice thickness and electronic windowing. The overall sensitivity in identifying nodules was 62% and the specificity was 80%. On average, the observers identified 56, 67, and 63% of nodules on 1.5-, 5-, and 10-mm-thick sections, respectively (p = 0.037). Nodules were more difficult to identify on 1.5-mm-thick sections. On average, observers identified 1, 48, 82, and 91% of nodules < 1.5, < 3, < 4.5, and < 7 mm in diameter, respectively (p < 0.001). Other factors that made a significant contribution (p < 0.01) in identifying nodules, as determined by linear discriminant function analysis, included nodule location, angiocentricity, and density. We concluded that computer-generated nodules can be used to assess a large number of imaging variables. We anticipate that this approach will be of considerable utility in assessing the accuracy of interpretation of a wide range of pathologic entities as well as in optimizing three-dimensional scan protocols within the thorax.     

Neural networks for the analysis of small pulmonary nodules

PURPOSE: Small pulmonary nodules can be readily detected by computed tomography (CT). The goal of this detection is to diagnose early lung cancer as the five year survival at this early stage is over 70% in contradistinction to the overall 5-year survival of around 10%. Critical to the efficacy of CT for early lung cancer detection is the ability to distinguish between benign and malignant nodules. We explored the usefulness of neural networks (NNs) to help in this differentiation. METHODS: CT images of 28 pulmonary nodules, 14 benign and 14 malignant, each having a diameter less than 3 cm were selected. All were sufficiently malignant in appearance to require needle biopsy and surgery. The statistical-multiple object detection and location system (S-MODALS) NN technique developed for automatic target recognition (ATR) was used to differentiate between these benign and malignant nodules. RESULTS: S-MODALS was able to correctly identify all but three benign nodules. S-MODALS classified a nodule as malignant because it looked similar to other malignant nodules. It identified the most similar nodules to display them to the radiologist. The specific features of the nodule that determined its classification were also shown, so that S-MODALS is not simply a "black box" technique but gives insight into the NN diagnostics. CONCLUSION: This initial evaluation of S-MODALS NNs using pulmonary nodules whose CT features were very suspicious for lung cancer demonstrated the potential to reduce the number of biopsies without missing malignant nodules. S-MODALS performed well, but additional optimization of the techniques specifically for CT images would further enhance its performance.     

Optimization of parameters for the detection of cerebral aneurysms: CT angiography of a model

PURPOSE: To optimize parameters with computed tomographic angiography for the detection of cerebral aneurysms. MATERIALS AND METHODS: Model aneurysms were placed randomly at various branch points and scanned multiple times with spiral technique. The final analysis included 63 branch points and 22 aneurysms. Each spiral scan used a different parameter combination. Collimation ranged from 1.5 to 4.0 mm and pitch ranged from 1:1 to 1.5:1. Images were constructed with shaded surface display (SSD) and maximum intensity projection (MIP) algorithms and were interpreted by three readers for the presence or absence of aneurysm. RESULTS: The receiver operating characteristic (ROC) curve area for 1.5-mm collimation was greater than those of 3- or 4-mm collimation (P < .01 and P < .001, respectively). There was no statistically significant difference in the ROC curve areas between 3- and 4-mm collimation (P = .37). There was no statistically significant decrease in ROC curve area when increasing pitch from 1:1 to 1.5:1 for any value of collimation (P = .96). For all parameter combinations the ROC curve areas for SSD images was greater than that of MIP images (P < .0001). CONCLUSION: For cerebral aneurysm detection, narrow collimation is superior to wider collimation. Mild increases in pitch do not substantially degrade diagnostic accuracy. SSD offers improved diagnostic accuracy over MIP display in this model.     

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INTRODUCTION: High-resolution computed tomography (HRCT) with iodinated contrast material has been used by many authors to study solitary pulmonary nodules (SPNs). The degree of enhancement was correlated with the nodule malignancy. MATERIAL AND METHODS: Forty adult patients were examined, before and after contrast agent administration, with incremental dynamic CT. We selected 22 patients with SPNs (3-30 mm phi, except one with 40 mm phi). The CT numbers of the inner nodule were calculated before and 1, 2 and 3 minutes after the i.v. administration of a weight-related dose (1.5 mL/kg/min) of nonionic iodinated contrast agent. A dose of 100 mL contrast agent was used in the first 6 patients. The difference in CT numbers between unenhanced images and the images with maximum enhancement (max. attenuation) was also calculated. RESULTS: Histologic diagnoses included 4 tuberculomas, 3 hamartomas and 15 malignant tumors (9 adenocarcinomas, 5 squamous cell carcinomas and 1 non-Hodgkin lymphoma). The CT numbers (in Hounsfield units, HU) of malignant nodules ranged 12-31 HU (mean: 21.5 HU) before contrast agent administration; the "long-standing" tuberculomas ranged 11-22 HU (mean: 16.5 HU) and the hamartomas had a mean density of 10.5 HU. We excluded for the study two "fresh" tuberculomas, one of which was surrounded by a low-attenuation infiltrate (the halo sign). We selected a threshold value of 20 HU on enhanced CT images to distinguish malignant (> or = 20 HU) from benign (< or = 20 HU) nodules. All lung cancers had complete enhancement (mean density: 35.5 HU). With 20 HU as the threshold value for a positive test, sensitivity was 100%, specificity 85.7%, positive predictive value 93.8% and negative predictive value 100%; test bias was 1.067. CONCLUSION: Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-D glucose is reported to be as accurate as enhanced HRCT, but it does not provide accurate morphological information, is not widely available and it is quite expensive: therefore, in our opinion, CT should be preferred. After examining over 100 patients, we may use our results in the decision analysis comparing surgical risk with cancer risk.     

Depot medroxyprogesterone acetate or oral contraception in postpartum adolescents

The purpose of the study was the evaluation of low-dose spiral CT in the detection and assessment of contours of pulmonary nodules. In a prospective investigation 71 consecutive chest CT examinations were acquired both at 30 and 200 mA. Films were interpreted independently by two radiologists. According to the size, nodules were divided into four categories: 10 mm; nodule shape was registered. With both protocols, 240 nodules were detected. The correlation coefficient for both methods was 0.89. Discrepancies were found most frequently in nodules near to pulmonary vessels. Nodule size estimation did not differ more than one size category. Eight spiculated nodules were identified by both techniques. Low-dose spiral CT of the chest has a high sensitivity in the detection of pulmonary nodules. If clinical circumstances require dose minimization, low-dose spiral CT may be advocated as an alternative screening method to conventional dose spiral CT.     

Computer-aided diagnoses: automatic detection of lung nodules

This work describes a computational scheme for automatic detection of suspected lung nodules in a chest radiograph. A knowledge-based system extracts the lung masks over which we will apply the nodule detection process. First we obtain the normalized cross-correlation image. Next we detect suspicious regions by assuming a threshold. We examine the suspicious regions using a variable threshold which results in the growth of the suspicious areas and an increase in false positives. We reduce the large number of false positives by applying the facet model to the suspicious regions of the image. An algorithmic classification process gives a confidence factor that a suspicious region is a nodule. Five chest images containing 30 known nodules were used as a training set. We evaluated the system by analyzing 30 chest images with 40 confirmed nodules of varying contrast and size located in various parts of the lungs. The system detected 100% of the nodules with a mean of six false positives per image. The accuracy and specificity were 96%.     

Grid versus non-grid techniques for the detection of pulmonary nodules in a chest phantom

A partial chest phantom was constructed to compare two commonly employed radiographic techniques, 70 kVp without a grid and 120 kVp with a grid, for the detection of pulmonary nodules. The phantom consisted of human ribs embedded in paraffin, the lungs of a dog injected with silicone rubber, a tissue equivalent wax heart and beeswax nodules. The nodules ranged in size from 3-7 mm. A series of 120 films was exposed, half with each technique, and the films were interpreted by three senior residents and seven staff radiologists. More nodules of all sizes except 3 mm were detected with the 120 kVp technique. The 3 mm nodules were rarely detected with either technique. The disadvantages of the 120 kVp technique were an approximate 50 percent increase in patient exposures and almost twice as many false-positive nodule detections.     

Likelihood of malignancy in a solitary pulmonary nodule: comparison of Bayesian analysis and results of FDG-PET scan

OBJECTIVE: To compare the probability of cancer in a solitary pulmonary nodule using standard criteria with Bayesian analysis and result of 2-[F-18] fluoro-2-deoxy-D-glucose-positron emission tomographic (FDG-PET) scan. SETTING: A university hospital and a teaching Veteran Affairs Medical Center. METHODS: Retrospective analysis of 52 patients who had undergone both CT scan of the chest and a FDG-PET scan for evaluation of a solitary pulmonary nodule. FDG-PET scan was classified as abnormal or normal. Utilizing Bayesian analysis, the probability of cancer using "standard criteria" available in the literature, based on patient's age, history of previous malignancy, smoking history, size and edge of nodule, and presence or absence of calcification were calculated and compared to the probability of cancer based on an abnormal or normal FDG-PET scan. Histologic study of the nodules was the gold standard. RESULTS: The likelihood ratios for malignancy in a solitary pulmonary nodule with an abnormal FDG-PET scan was 7.11 (95% confidence interval [CI], 6.36 to 7.96), suggesting a high probability for malignancy, and 0.06 (95% CI, 0.05 to 0.07) when the PET scan was normal, suggesting a high probability for benign nodule. FDG-PET scan as a single test alone was more accurate than the standard criteria and standard criteria plus PET scan in correctly classifying nodules as malignant or benign. CONCLUSION: FDG-PET scan as a single test was a better predictor of malignancy in solitary pulmonary nodules than the standard criteria using Bayesian analysis. FDG-PET scan can be a useful adjunct test in the evaluation of solitary pulmonary nodules.     

Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.     

Seizures in cerebral malaria

The authors proposed a new application of helical CT, namely, CT-ventriculography that can obtain 2D and 3D images of different cardiac phases. CT-ventriculography could assess wall motion, systolic thickening and chamber volume. From a single breath hold helical CT 50-rotation), about 500 transaxial slices were obtained by applying overlapping reconstruction (0.1 pitch, 0.08 sec = 0.2 mm interval). All transaxial slices were recordered to separate different cardiac phases. Then, long and short axial 2D tomograms and 3D images in different cardiac phases were reformatted. CT-ventriculography is a promising new application for the assessment of heart function.     

Suppressive therapy with levothyroxine for solitary thyroid nodules: a double-blind controlled clinical study and cumulative meta-analyses

Levothyroxine suppressive treatment of solitary thyroid nodules is controversial. A 1-yr prospective randomized placebo-controlled trial was conducted to evaluate the effect of T4 on nodule volume and bone mineral density, and meta-analyses were performed to examine the quantitative synthesis of data from similar designed controlled trials. Forty-five euthyroid patients (42 females, age range: 19-73 yr) with single, colloid nodules were randomized to T4 (21 patients, 2.7 +/- 0.3 microg/kg, TSH < 0.3 microIU/mL) and placebo. Ultrasonography and densitometry were performed at baseline and repeated after treatment. Mean nodule volume or bone mineral density did not change. Nodule reduction more than 50% was observed in 6 of 21 treated patients and 2 of 24 placebo patients (P = 0.12). This study and another 6 prospective controlled trials (minimum 6 months, ultrasonographic nodule evaluation) were included in cumulative meta-analyses (risk-difference method). Nodule volume decreased more than 50% in a significantly higher percentage of patients in the T4 groups (risk difference, 16.7%; 95% confidence intervals, 5.8-27.6%). Four trials evaluated nodule growth with homogeneous results (Q = 0.42). Nodule volume increased more than 50% in a significantly smaller percentage of patients treated with T4 (risk difference, 9.7%; 95% confidence intervals, 2.0-17.4%). In conclusion, T4 treatment is associated with decreased nodule volume in 17% of patients and may inhibit growth in another 10%.     

Computerized detection of pulmonary nodules in computed tomography images

RATIONALE AND OBJECTIVES: Interpretation of computed tomographic (CT) scans of the lungs is a time-consuming task that involves visual correlation of possible nodules in one section with those in contiguous sections to distinguish actual nodules from blood vessels. Thus, the authors are developing automated methods to detect nodules on CT images of the thorax. METHODS: The computerized technique uses various computer-vision techniques and a priori information of the morphologic characteristics of pulmonary nodules. In each section, the external thoracic wall and lung boundaries are detected, and the features within the lung boundaries are subjected to gray-level thresholding operations. By analyzing the relationships between features arising at different threshold levels with respect to their shape, size, and location, each feature is assigned a likelihood of being a nodule or a vessel. Features in adjacent sections are compared to resolve ambiguous features. Detected nodule candidates are displayed in three dimensions within the lung. RESULTS: The system provided a sensitivity of 94% for nodule detection and an average of 1.25 false-positive results per case. CONCLUSIONS: Continued development of an automated method for detecting pulmonary nodules in CT scans is expected to aid radiologists in the task of locating nodules in three dimensions.     

Transfectable and transplantable postmitotic human neurons: a potential "platform" for gene therapy of nervous system diseases

OBJECTIVE: To evaluate F-18 fluorodeoxyglucose positron emission tomography (PET) in terms of its sensitivity and specificity in diagnosing malignant pulmonary nodules and staging bronchogenic carcinoma. METHODS: A retrospective review of any patient that presented to the VA Palo Alto Health Care System with a pulmonary nodule between 9/94 and 3/96 revealed 49 patients (four female, 45 male) age 37-85 (mean 63) with 54 pulmonary nodules who had: chest CT scan, PET scan; and tissue characterization of the nodule. Characterization of each nodule was achieved by histopathologic (N = 44) or cytopathologic (N = 10) analysis. Of the 49 patients, 18 had bronchogenic carcinoma which was adequately staged. Mediastinal PET and CT findings in these 18 patients were compared with the surgical pathology results. N2 disease was defined as mediastinal lymph node involvement by the American Thoracic Society's classification system. Mediastinal lymph nodes were interpreted as positive by CT if they were larger that 1.0 cm in the short-axis diameter. RESULTS: Sensitivity and specificity for the diagnosis of malignant pulmonary nodules using PET was 93 and 70%, respectively. All nodules (N = 3) that were falsely positive by PET scan were infectious in origin. All nodules (N = 4) that were falsely negative by PET were technically limited studies (outdated scanner, no attenuation correction, hyperglycemia) except for one case of metastatic adenocarcinoma. The sensitivity and specificity of PET in diagnosing N2 disease was 67 and 100%, compared with 56% and 100% for CT scan (not statistically significant). However, one more patient with N2 disease was correctly diagnosed by PET than by CT scan. CONCLUSION: PET is a valuable tool in the diagnosis and management of pulmonary nodules and may more accurately stage patients with bronchogenic carcinoma than CT scanning alone.     

Role of ultrasound-guided fine-needle aspiration biopsy in evaluation of nonpalpable thyroid nodules

To determine the role of ultrasound-guided fine-needle aspiration biopsy (US-FNAB) in the evaluation of incidentally diagnosed nonpalpable thyroid nodules (NP-TN), we compared the diagnostic yield of US-FNAB in NP-TN larger than 10 mm in diameter, with palpation-guided (P-FNAB) in palpable thyroid nodules (P-TN) in the same hospital setting. Of 108 consecutive patients with NP-TN (female/male: 97/11, age: 55.2 +/- 14.3, mean +/- SD), malignancy was identified in 8 patients (7 with thyroid papillary carcinoma, 4 of which had extrathyroidal spread, and 1 patient had metastasis of pulmonary adenocarcinoma). Male gender was associated with higher prevalence of malignancy (p = 0.09) while calcification and/or cystic degeneration of the nodule did not predict the cytological findings. Malignancy was identified in 16 of 151 consecutive patients with P-TN (female/male: 139/12, age: 44.1 +/- 9.5, mean +/- SD) indicating a similar rate of malignancy in both NP-TN and P-TN. In the P-TN group thyroid cancer was more common in males (p = 0.007), and the US properties of the nodule did not predict its cytological diagnosis. In conclusion, because similar rates of cancer are detected by FNAB in both NP-TN and P-TN, an FNAB is recommended for NP-TN larger than 10 mm.     

Helical CT of pulmonary nodules in patients with extrathoracic malignancy: CT-surgical correlation

OBJECTIVE: Our aim was to assess the sensitivity of helical CT for revealing pulmonary nodules. Thoracotomy with palpation of the deflated lung, resection, and histologic examination of palpable nodules was used as the gold standard. SUBJECTS AND METHODS: Thirteen patients underwent helical CT (slice thickness, 5 mm; reconstruction intervals, 3 mm and 5 mm; interpreted by two independent observers). Subsequently, patients underwent unilateral (n = 6) or bilateral (n = 7) surgical exploration, and CT-surgical correlation of 20 lungs was performed. RESULTS: Ninety nodules were resected (61 were smaller than 6 mm; 13 were 6-10 mm; 11 were larger than 10 mm; in five nodules, the size was not recorded at surgery). Sixty-nine nodules were located in the pulmonary parenchyma and 21 in the visceral pleura. Of the 90 lesions, 43 (48%) were found on histology to represent metastases. For lesions detected by at least one observer, the sensitivity of helical CT was 69% for intrapulmonary nodules smaller than 6 mm, 95% for intrapulmonary nodules larger than or equal to 6 mm, and 100% for histologically proven intrapulmonary metastases larger than or equal to 6 mm. For lesions smaller than or equal to 10 mm, sensitivity was better using a reconstruction interval of 3 mm rather than of 5 mm. CONCLUSION: In this study, the sensitivity of helical CT exceeded the sensitivity of conventional CT in previous reports. However, because of limitations in the detection of intrapulmonary nodules smaller than 6 mm and of pleural lesions, complete surgical exploration should remain the procedure of choice in patients undergoing pulmonary metastasectomy. Preoperative helical CT should be used to guide the surgeon to lesions that are difficult to palpate.     

Genetic characterization of an oral treponeme isolated from human subgingival plaque

INTRODUCTION: Since many benign and malignant pathologic conditions can appear as solitary pulmonary nodules, to establish nodule nature is always necessary for correct patient management. Recently, some authors have demonstrated the effectiveness of incremental dynamic CT in distinguishing cancerous from noncancerous lesions. The purpose of this work is to report our personal experience in this field. MATERIAL AND METHODS: We reviewed the incremental dynamic CT scans of 21 patients with a solitary pulmonary nodule < 3.5 cm phi without any calcifications, cavities and fat--namely, 15 carcinomas, 3 granulomas, 2 hamartomas, 1 abscess. Lesion density was evaluated before and 30 s, 1, 2, 3 and 5 min after contrast agent administration; we used a circular region of interest consisting of the central portion of the nodule in all cases and of 60-70% of its area in most cases. We subdivided the nodules into two groups, according to their enhancement: the nodules with > 20 HU and those with < 20 HU. All the lesions were submitted to surgery and histologic studies. RESULTS: Fourteen of 15 carcinomas and one hamartoma had contrast enhancement > 20 HU; an abscess exhibited marked ring-shaped contrast enhancement (positive predictive value: 87%). One carcinoma, three granulomas and one hamartoma had no contrast enhancement, or else it was < 20 HU (negative predictive value: 80%). DISCUSSION: Recently, some authors have demonstrated that malignant nodules, studied with incremental dynamic CT, have higher contrast enhancement than benign nodules. A value > 20 HU is a good predictor of malignancy (positive predictive value: 90%) and, conversely, a value < 20 HU is an unquestionable sign of benignity (negative predictive value: 100%). Our findings confirm the positive predictive value of enhancement > 20 HU, but not its negative predictive value because we found a malignant nodule without contrast enhancement. CONCLUSIONS: Incremental dynamic CT is an effective indicator of solitary pulmonary nodule nature, but its predictive value is not absolute and therefore this technique should be integrated with biopsy in the cases which are clinically or radiologically suspicious.     

Endogenous benzodiazepine-like compounds and diazepam binding inhibitor in serum of patients with liver cirrhosis with and without overt encephalopathy

PURPOSE: The purpose of our work was to determine the usefulness of double-phase helical CT during arterial portography (CTAP) for the detection of hypervascular hepatocellular carcinoma (HCC). METHOD: Eighty-four patients with 176 hypervascular HCC nodules underwent double-phase CTAP. Hypervascular HCCs were diagnosed by iodized oil CT after transcatheter arterial chemoembolization (TACE). The first-phase images were obtained 30 s after the initiation of injection of a nonionic iodinated contrast medium into the superior mesenteric artery or splenic artery, and the second-phase images were obtained after 70 s. These images were interpreted separately for detection of HCC. RESULTS: The double-phase CTAP detected two nodules and six nodules that were missed by the first- and second-phase images, respectively. The sensitivity for hypervascular HCC nodules was 89% for the first phase, 91% for the second phase, and 93% for the first phase and second phase combined. The double-phase CTAP showed significantly superior sensitivity to the first-phase CTAP for detecting HCC nodules (p < 0.05). However, there was no statistically significant difference between the sensitivities of the double-phase CTAP and the second-phase CTAP. The positive predictive values of the double-phase images were inferior to those of either the first-phase or the second-phase images alone. CONCLUSION: Double-phase helical CTAP was found to be no better than second-phase CTAP alone for the detection of hypervascular HCC nodules.