Pre- and postoperative study of the bile ducts with spiral computerized tomography

PURPOSE: To investigate the capabilities of Helical CT in imaging the biliary tract after administration of an oral cholecystographic contrast agent. MATERIAL AND METHODS: Forty-five adult patients and one 8-year-old child were examined with Helical CT 12 hours after the oral administration of hyopanoic acid (3 g). All the examinations were performed with the following parameters: thickness 5 mm, pitch factor 1.5, standard reconstruction algorithm, acquisition time 20-30 s, image index 2.5 mm, 130 kV, 125 mA. In 37 cases CT was performed in patients candidate to laparoscopic cholecystectomy, in 8 cases to assess the positioning of surgical clips in patients with postcholecystectomy syndrome and in 1 case (the 8-year-old child) to confirm the US diagnosis of choledochal cystic dilatation. Helical CT images were reconstructed with a Volume Rendering (VR) software. RESULTS: The extrahepatic biliary tract was visualized in all the cases with CT and VR. II grade biliary ducts were visualized in 87% (CT) and 91% (VR), III grade ducts in 76% (CT) and 78% (VR), IV grade ducts in 28% and 35%, respectively. No statistically significant difference was found between CT and VR in the visualization of the biliary structures (p > 0.05), while three-dimensional VR reconstructions improved the evaluation of the anatomical relations in the biliary tract in comparison with CT both in normal cases and in patients with congenital abnormalities of the biliary tract. Also, three-dimensional VR reconstructions were superior in assessing the correct positioning of surgical clips in patients with postcholecystectomy syndrome (p < 0.05). DISCUSSION AND CONCLUSIONS: Cholecysto-cholangio-CT with VR reconstructions is a reliable imaging technique for the biliary tract in patients candidate to laparoscopic cholecystectomy, to diagnose choledochal cystic dilatation and to assess the positioning of surgical clips.     

Angiography with spiral computerized tomography in the study of aneurysms of the visceral arteries. Techniques and results]

INTRODUCTION: The aneurysms of visceral vessels are characterized by few or no symptoms and the diagnosis is often occasional. We investigated the usefulness of CT angiography in the diagnosis and preoperative assessment of this condition. MATERIALS AND METHODS: From January 1993 to March 1998, twenty-five patients (aged 32-69 years) with 28 aneurysms underwent CT angiography before and after contrast agent injection to study lesion number, site, size, neck, intraluminal thrombosis and wall calcifications. Data from axial images were postprocessed on an external work-station to obtain CT angiograms. CT angiography findings were analyzed with a double blinded method by 2 radiologists comparing CT angiography with digital subtraction angiography images and evaluating the information obtained from Multiplanar (MPR), Maximum Intensity Projection (MIP) and Shaded Surface Display (SSD) reconstructions. Surgical findings were available for 10 patients. RESULTS: There was complete agreement between CT angiography and digital subtraction angiography in the identification of all lesions; the correlation rate was 94.42% for lesion location, 89.28% for lesion size, 85.71% for detection of endoluminal thrombosis and 82.14% for identification of wall calcifications. Axial and MPR images were useful in the assessment of ali parameters, while MIP images accurately demonstrated wall calcifications and the lesion relationships with adjacent structures. No additional information was obtained from SSD reconstructions. CONCLUSIONS: In our experience CT angiography can replace digital subtraction angiography in the diagnosis and preoperative work-up of visceral vessels aneurysms. CT angiography was superior to digital angiography in the evaluation of the lesion exact dimensions in cases with large thrombotic component and diffuse wall calcifications.     

Automatic evaluation of total lung capacity and of emphysema involvement with spiral computerized tomography (CT) in obstructive pneumonia

OBJECTIVE: To evaluate, in patients with chronic obstructive lung disease or chronic bronchitis, inspiratory helical CT with 3D postprocessing, to measure lung volumes and the amount of emphysema and to compare these measurements with lung function tests. MATERIAL AND METHODS: Seventeen patients with chronic obstructive lung disease disease or chronic bronchitis underwent pulmonary function tests and helical CT after a full inspiration with 3D postprocessing (lower threshold -1024 HU, upper thresholds -200, -300 and -400 HU). Lung inspiratory volumes (TLC-CT) were determined for each model; the amount of emphysema was evaluated by means of an automatic score and a visual score with HRCT. RESULTS: There is a good correlation between automatic and visual scores (p < 0.001); the automatic score had a good correlation with lung function tests, above all with total lung capacity (r = -0.56; p = 0.01) but the visual score had a much closer correlation with DLCO (r = -0.70; p < 0.001). TLC-CT had a significant correlation with pletismographic TLC (TLC-P); the upper threshold -200 HU was more correct (TLC-P = 8011 cc.; TLC-CT 200 = 7138 cc.; r = 0.83; p < 0.001). The volume change of 3D model was about 230 cc. per 100 HU (p < 0.001) modifying upper thresholds, but no change was observed in the volume occupied by emphysema and the percentage of emphysema presented minimal, clinically non significant modifications. DISCUSSION AND CONCLUSIONS: In emphysematous patients, the helical CT with 3D model construction is a good technique to evaluate lung volumes and to quantify emphysema with automatic score; this one, however, probably underscores the extent of pathology; therefore, the addition of a visual score with HRCT is probably worthwhile.     

Dosimetry in dental radiology: comparison of spiral computerized tomography and orthopantomography]

INTRODUCTION: Dental diagnosis still depends largely on diagnostic imaging for correct anatomical and radiological assessment. Many studies confirm the risk of ionizing radiations, especially if used in pediatric populations and with suboptimal control. We compared the doses absorbed by the dentomaxillary area in Spiral CT and panoramic radiography examinations. MATERIAL AND METHODS: Doses were measured at critical organs in neck, ocular and intracranial regions with lithium fluoride dosimeters calibrated on the national standard and then positioned on an anthropomorphic Rando phantom made of tissue-equivalent material covering a skeleton. Multiple measurements were made during Spiral CT with the Dentascan software and panoramic radiography, to calculate mean absorbed doses for both examinations. Acquisition technical parameters were similar to those used in vivo. RESULTS: The parotid, cerebellum and thyroid gland were the most irradiated organs with panoramic radiography, with the addition of the mandible with Spiral CT. The gonads did not receive major doses. CONCLUSIONS: Our dose measurements demonstrate that patients receive smaller doses with panoramic radiography than with Spiral CT with Dentascan. After allowing for some variations from instrumental differences, they are in substantial agreement with literature data. Further investigations are needed considering the radiobiological risk related to the growing spread of Dentascan examinations.     

Non-invasive lymphatic staging of lung neoplasms: comparative study with computerized tomography and endoscopic ultrasonography]

INTRODUCTION: A prospective comparative study with pathology was performed at the National Cancer Institute, Milan, to assess the clinical value of Computed Tomography (CT) and endoscopic ultrasound (EUS) for nodal staging in lung cancer. MATERIAL AND METHODS: In three years, 71 patients with histological diagnosis of non-small-cell lung cancer were operated on. They underwent CT and EUS examinations to identify mediastinal lymphadenopathies after major nodal involvement had been excluded by chest X-ray. Diagnostic staging was completed in two weeks prior to treatment. Patients received complete tumor removal and radical lymphadenectomy (55 patients), invasive staging with node resection and sampling (11 patients), or mediastinoscopy (5 patients). Blinded interpretation of CT alone, EUS alone, and CT and EUS together were performed, with systematic correlation of imaging findings and pathological results. RESULTS: The frequency of mediastinal involvement was 42.2%. A total of 329 nodal stations were dissected or sampled and 755 lymph nodes were examined at histology. On a per-station basis, CT had greater sensitivity (74%) than EUS (56%), but EUS was more specific (83.4% vs 92.7%). The accuracy rates of the two techniques were similar (CT 81%, EUS 83%). A site by site analysis showed highest sensitivity (100%) in the lower right paratracheal nodes for CT, and in the superior left paratracheal and subcarinal nodes for EUS. When the EUS and CT images were studied together by specialists on a per-station basis, sensitivity, specificity, and accuracy increased to 85%. CONCLUSIONS: Endoscopic ultrasound should be part of the routine preoperative diagnostic approach to non-small-cell lung cancer, because of its high specificity. Results can be improved when EUS and CT are combined, which suggests that these imaging modalities should be used together in selected patients for the noninvasive staging of non-small-cell lung cancer to identify local lymphatic spread.     

Possibility of false negative results in the diagnosis of lung neoplasms with computerized tomography]

PURPOSE: To describe the radiological appearance of overlooked malignant pulmonary lesions at CT and to analyze the reasons of misdiagnosis. MATERIAL AND METHODS: Ten patients with pulmonary malignant lesions (PML) overlooked at first CT examination were selected among patients with lung cancer who were referred to our institution between 1994 and 1997. CT scans were evaluated by consensus of two chest radiologists with different experience in chest radiology, who were blinded to the final diagnosis. RESULTS: The overlooked pulmonary lesions were 5 endobronchial cancers and 5 central solitary nodules. The mean diameter of the lesions ranged 1 to 2 cm. Furthermore, 7 patients had associated pleural and/or parenchymal abnormalities. The technical quality of CT examinations was considered good in 2 cases, acceptable in 6 cases, poor in 2 cases. PML were correctly identified in 6/10 cases by the first (more experienced) radiologist and in 4/10 by the second radiologist. Four cases were considered suspect for the presence of PML by the first radiologist, 2 by the second. CONCLUSIONS: Endobronchial location of the tumors and their small size were the most frequent causes of misdiagnosis of PML at chest CT in our series. However, a systematic evaluation of CT scans can reduce the percentage of missed lesions.     

Application of spiral computerized tomography in the study of traumatic lesions of the thoracic aorta

PURPOSE: Acute thoracic aortic injuries account for up to 10-20% of fatalities in high-speed deceleration road accidents and have an estimated immediate fatality rate of 80-90%. Untreated survivors to acute trauma (10-20%) have a dismal prognosis: 30% of them die within 6 hours, 40-50% die within 24 hours, and 90% within 4 months. We investigated the diagnostic accuracy of Helical Computed Tomography (Helical CT) in acute traumatic injuries of the thoracic aorta, and the role of this technique in the diagnostic management of trauma patients with a strong suspicion of aortic rupture. MATERIAL AND METHODS: We compared retrospectively the chest Helical CT findings of 256 trauma patients examined June 1995 through August 1999. All patients underwent a plain chest radiograph in supine recumbency when admitted to the Emergency Room. Chest Helical CT examinations were performed according to trauma score, to associated traumatic lesions and to plain chest radiographic findings. All the examinations were performed with no intravenous contrast agent administration and the pitch 2 technique. After a previous baseline study, contrast-enhanced scans were acquired with pitch 1 in 87 patients. All examinations were assessed for the presence of mediastinal hematoma, periaortic hematoma, traumatic pseudodiverticulum, irregular aortic wall or contour and intimal flap as signs of aortic rupture. RESULTS: Helical CT showed thoracic aortic lesions in 9 of 256 patients examined. In all the 9 cases we found a mediastinal hematoma and all of them had positive plain chest radiographic findings of mediastinal enlargement. Moreover, in 6 cases aortic knob blurring was also evident on plain chest film and in 5 cases depressed left mainstem bronchus and trachea deviation rightwards were observed. All aortic lesions were identified on axial scans and located at the isthmus of level. Aortic rupture was always depicted as pseudodiverticulum of the proximal descending tract and intimal flap. We also found periaortic hematoma in 6 cases and intramural hematoma in 1 case. There were no false positive results in our series: 7 patients with Helical CT diagnosis of aortic rupture were submitted to conventional aortography that confirmed both type and extension of the lesions as detected by Helical CT, and all findings were confirmed by gross inspection at surgery. No false negative results have been recorded so far: untreated aortic ruptures are fatal within 4 months in 90% of patients, or they may evolve into chronic pseudoaneurysm in about 5% of survivors. CONCLUSIONS: In our experience Helical CT had much higher diagnostic sensitivity and specificity than plain chest radiography. In agreement with larger published series, in our small one the diagnostic accuracy of Helical CT was 100% in the evaluation of traumatic aortic ruptures. Moreover, Helical CT is faster and less invasive than conventional aortography, which makes this diagnostic modality increasingly used and markedly improves the management of the serious trauma patient. The more widespread use of this diagnostic tool has permitted to standardize the technique and now Helical CT can be used not only as a screening modality for patients that undergo digital aortography, but also as a reliable diagnostic method for surgical planning.     

Characterization of non-secreting adrenal nodules (incidentalomas): role of multiphasic spiral computerized tomography

PURPOSE: To evaluate the diagnostic yield of multiphasic helical CT in the characterization of single non functioning adrenal nodules (incidentalomas) less than 50 mm in diameter. Emphasis was given to the possible replacement of unenhanced with delayed scans in cancer patients undergoing staging procedures. MATERIAL AND METHODS: Sixty patients with single adrenal nodules (30 of them neoplastic and 30 non-neoplastic) were examined with thin unenhanced scans (5 mm), early scans after administration of a contrast agent (120 mL at 2.5 mL/s with 60 s delay) and late scans (30 min delay). RESULTS: On both unenhanced and late scans a threshold could be selected on the Hounsfield unit scale which guaranteed absolute specificity in the characterization of adenomas (100% specificity) with very high sensitivity (93% at both scans): this threshold was 19 HU on unenhanced and of 41 HU on late scans. In contrast, at early delayed scanning the threshold which guaranteed 100% specificity was associated with negligible sensitivity (30%). The evaluation of lesion size had no diagnostic value, since the mean diameter of both benign and malignant nodules was of 25 mm. CONCLUSIONS: Late scans have diagnostic yield comparable to unenhanced scans: at the selected delay (30 min), benign lesions nearly always have lower attenuation values than malignant nodules and can be diagnosed with confidence when they exhibit mean attenuation values lower than 41.     

The role of computerized tomography in the study of duodenal carcinoma]

Seven patients suffering from carcinoma of the lower portion of duodenum were examined by means of CT. Water was used as oral contrast medium. In all patients CT showed parietal thickening in the lesion site, with hyperdense (4 cases) or isodense (3 cases) patterns with respect to adjacent normal walls; irregularities on the inner surface were also demonstrated. CT correctly staged the tumor in 5/7 patients (70%), showing pancreatic infiltration in 5 cases--in 1 case associated with hepatic metastases--, vena caval infiltration in 1 patient, and right anterior pararenal fascia involvement in 1 case. In 2 patients the relationship between duodenal carcinoma and pancreas could not be evaluated. CT is suggested for the patients with suspected neoplastic pathologic conditions of the duodenum thanks to its capabilities of showing extraparietal lesion spread, as well as adjacent organs infiltration, adjacent vessels involvement, and distant metastases.     

Comparison between low (3:1) and high (6:1) pitch for routine abdominal/pelvic imaging with multislice computed tomography

PURPOSE: The purpose of this study was to compare the performance of low helical pitch acquisition (3:1) and high helical pitch acquisition (6:1) for routine abdominal/pelvic imaging with multislice computed tomography (CT). METHOD: Three hundred eighty-four patients referred for abdominal/pelvic CT were examined in a breath-hold on a multislice CT scanner (LightSpeed QX/I; General Electric Medical Systems, Milwaukee, WI). Patients were randomized and scanned with pitch of 3:1 or 6:1 using a constant 140 peak kV and 280-300 mA. Images were reconstructed at a 3.75-mm slice thickness. Direct comparison between the two pitches was possible in a subset of 40 patients who had a follow-up scan performed with the second pitch used in each patient. A comparison was also performed between standard dose CT using a pitch of 6:1 and 20% reduced radiation dose CT using a pitch of 3:1. Two readers performed a blind evaluation using a three-point scale for image quality, anatomic details, and motion artifacts. Statistical analysis was performed using a rank sum test and the Wilcoxon signed rank test. RESULTS: Overall image quality mean scores were 2.5 and 2.3 for a pitch of 3:1 and a pitch of 6:1, respectively (P = 0.134). Likewise, mean anatomic detail and motion artifact scores were 2.5 and 2.6 for a 3:1 pitch and 2.3 and 2.5 for a 6:1 pitch, respectively (P > 0.05). In patients with a direct comparison of the two pitches (with the standard radiation dose as well as with a 20% reduction in milliamperes), no statistically significant difference in the performance of the two pitches was observed (P > 0.05). CONCLUSION: Image quality with a high pitch (6:1) is acceptable for routine abdominal/pelvic CT.     

Unusual application of computerized tomography: the study of musical instruments]

INTRODUCTION: We report on the use of CT in the study of bowed stringed instruments to assess structural defects and/or damage before proceeding to any repair. MATERIAL AND METHODS: Two antique masterpieces from the Castello Sforzesco Museum of Antique Musical Instruments were analyzed with CT. They were an exquisite wood and ivory guitar from Naples (Italy) and a very rare Giuseppe Guarneri "del Gesù" violin from Cremona (Italy), both crafted in the early years of the 18th century. We evaluated the wood thickness, the neck and its heel. In the wood structure we studied the course and thickness of hypo- and hyperdense lines. RESULTS: The examination showed three types of signs: normal wood structure: hypodense, thin, parallel lines; wormholes: hypodense lines with irregular course and variable thickness; previous repair signs: thin or thick more or less parallel hyperdense lines. CONCLUSIONS: The study confirmed that CT is a valuable tool to investigate normal structure, defects and damage, providing accurate information for the evaluation and repair of antique stringed instruments.     

Pre- and post-interventional follow-up of stent graphs with single and multi-slice spiral computerized tomography

PURPOSE: Could contrast enhanced computed tomography replace conventional catheter angiography in the preoperative evaluation of aortic aneurysms before stentgraft implantation? Does multi slice computed tomography have advantages comparing to single slice computed tomography? METHODS: We compared 15 single slice with 13 multi slice computed tomography studies and reconstructions according to there ability to replace conventional catheter angiography in the preoperative evaluation. In the postoperative follow-up 60 single slice computed tomography studies were compared to 60 multi slice studies. RESULTS: By using appropriate reconstructions the spiral computed tomography studies could deliver all information necessary for implantation. In our study no advantage of multi slice computed tomography could be detected. In the postoperative evaluation of stentgrafts our computed tomography scan protocol could detect all relevant complications in single and multi slice computed tomography. No significant advantage of multi slice computed tomography could be detected. CONCLUSION: Contrast enhanced computed tomography is equal to conventional catheter angiography in the pre- and postoperative evaluation of stengrafts. No significant advantage of multi slice versus single slice could be detected.     

Reconsideration of conventional tomography versus computerized tomography in the evaluation of lung metastases

Several published reports compare linear chest tomography to computerized chest tomography regarding the detection of lung metastases in adults. As linear tomography does not result in a sectional image, a study comparing multidirectional tomography to computed tomography in the chest was carried out. Equal sensitivity and specificity of these two modalities is shown by reviewing 28 cases who had known extrathoracic malignancies prospectively. The currently prevailing impression that computerized tomography is superior in the detection of lung metastases is thus not justified.     

3D computerized segmentation of lung volume with computed tomography

Three-dimensional (3D)-based detection and diagnosis has an important role for significantly improving the detection and diagnosis of lung cancer upon computed tomography (CT). This report presents a 3D-based method for segmenting and visualizing lung volume by using CT images. An anisotropic filtering method was developed on CT slices to enhance the signal-to-noise ratio, and a wavelet transform-based interpolation method was used combined with volume rendering to construct the 3D volumetric data based on entire CT slices. Then an adaptive 3D region-growing algorithm was designed to segment lung volume, incorporated by automatic seed-locating methods through fuzzy logic algorithms and 3D morphological closing approaches. In addition, a 3D visualization tool was designed to view volumetric data, projections, or intersections of the lung volume at any view angle. This segmentation method was tested on single-detector CT images by percentage of volume overlap and percentage of volume difference. The experiment results show that the developed 3D-based segmentation method is effective and robust. This study lays the groundwork for 3D-based computerized detection and diagnosis of lung cancer with CT imaging. In addition, this approach can be integrated into a picture archiving and communication system serving as a visualization tool for radiologists' reading and interpretation.     

3D spiral computerized tomography in the reconstructive treatment of malignant maxillofacial tumors

PURPOSE: To investigate the role of Helical CT and the usefulness of three-dimensional (3D) imaging for preoperative planning and follow-up of reconstructive maxillofacial surgery with alloplastic material in neoplastic disease involving this region. MATERIAL AND METHODS: From 1996 to 1999 eleven patients were examined with Helical CT and 3D images for planning of maxillofacial plastic and reconstructive surgery for advanced cancer of this anatomically complex region. A 3D-modulated titanium mesh (100%) or micronets was used to rebuild the anterior surface of maxillary bone and the orbital floor. The mesh was cut to the appropriate size and shape and curved where necessary. Within the residual sinusal cavity a siliconed filling was used surmounting an acrylic prosthesis with dental arch to rebuild the palate. A rehydrated bovine pericardium was affixed and moduled on the borders in two cases only. Three-dimensionally reconstructed CT images were obtained preoperatively and at least 6 months postoperatively in all patients. The images were generated on a computer workstation using the shaded surface display (SSD) software with threshold values ranging 425 to 630 HU, and a more closed window for the imaging of titanium mesh/bone interface in the postsurgical follow-up. RESULTS: We always obtained an excellent complete spatial depiction of maxillofacial region both before and after surgery, with no artefacts so important as to affect the 3D reconstruction process and the image quality. Together with the head-neck surgical team we could work for preoperative planning through CT scans by different 3D points of view. The 3D reconstructed follow-up scans showed good filling of the defect in the area where the titanium mesh had been used. Then efficacious bone modelling and good biocompatibility of the alloplastic material were seen in all patients, with no inflammatory reactions. CONCLUSIONS: Titanium is a well-known material, which is widely used for cranioplasty. It is a radiolucent, nonferrous metal of low atomic number that allows very clear CT and MR images to be obtained. Further Ti features are strength, biocompatibility and easy handling. 3D Helical CT scan has proved to be the most complete and accurate imaging technique for reconstructive plastic surgery with alloplastic material in advanced maxillofacial cancer, also considering the anatomic and functional complexity of this area. The prospect is provided to identify virtual 3D presurgical ablation planes. These may allow the surgeon to improve plastic reconstruction and shorten intervention time.