P Vagli

Time efficiency of CT colonography: 2D vs 3D visualization.

We aimed to compare the time efficiency of three visualization methods in CT colonography and to identify the colonic factors influencing the time for interpretation. Twenty CT colonographic examinations were prospectively analysed. Three reading methods were adopted: method 1, primary 2D analysis with the use of virtual endoscopy as problem solver, method 2, primary standard virtual endoscopy with semiautomatic navigation through the colon and use of 2D images as problem solver; method 3, primary virtual endoscopy with automatic navigation and the use of 2D images as problem solver. In method 1, time for 2D analysis ranged between 6 and 18min (mean 12) for evaluation of both supine and prone decubitus with a synchronization method. In method 2, time for 3D manual navigation in supine plus prone ranged between 9 and 24min (mean 17). In method 3, time for automated navigation ranged between 6 and 20min (mean 12) for evaluation of both supine and prone decubitus. A statistically significant difference was found between time efficiency of methods 1 and 2 (p=0.009, t-test, unequal variances). Methods 2 and 3 showed a tendency to significant differences (p=0.054, t-test, unequal variances). Faecal or fluid residuals were reported as major drawbacks in 3D navigations, requiring constant correlation with 2D images; tortuous folds influenced mostly the 2D analysis; diverticula were reported as influencing factor in all three methods. No differences in sensitivity and specificity were observed between the three viewing methods. The 3D semiautomatic navigation method* tended to increase the time for interpretation in almost all cases. There is, in particular, greatest time efficiency for 2D analysis as compared with 3D manual analysis. Two-dimensional and automated 3D navigation reading have comparable time efficiencies in a routine clinical setting.

Renal Artery Stenting in Patients with a Solitary Functioning Kidney

AbstractPurpose: To retrospectively evaluate the results of renal artery stenting in patients with renovascular disease and a solitary functioning kidney. Methods: Palmaz stents were placed in 16 patients with a solitary functioning kidney, renal artery stenosis, hypertension and renal failure. Stenoses were evaluated with color Doppler ultrasound, MR angiography and digital subtraction angiography (DSA). Indications for stenting were: recoil after percutaneous transluminal renal angioplasty (PTRA) (63%), arterial dissection after PTRA (13%) and primary stenting (25%). Immediate results were evaluated by DSA. On follow-up (6-36 months), patients underwent periodical evaluation of clinical conditions (blood pressure and serum creatinine level) and stent patency, by means of color Doppler ultrasound. Results: Stent placement was successful in all patients (100%). Cumulative primary patency rate was: 100% at 1 day, 93.75% at 6 months, 81.25% at 12 months and 75% at 24 months. A significant reduction in diastolic blood pressure occurred (mean ± SD 104 ± 6 vs 92 ± 3; p < 0.05); renal function improved or stabilized in over 80% of patients. However, there was no significant difference in the creatinine values before and after treatment (mean ± SD 200 ± 142 mmol/l vs 197 ± 182 mmol/l; p > 0.05). Conclusion: Renal artery stenting, both after PTRA and as primary stenting, represents a safe procedure, able to preserve renal function in patients with a solitary functioning kidney.

CT colonography : contrast enhancement of benign and malignant colorectal lesions versus fecal residuals

We retrospectively reviewed the computed tomographic colonographic datasets of 22 patients. Mean attenuation values of benign polyps before and after contrast administration were 30 ± 15 HU and 90 ± 18 HU, respectively. Mean attenuation values of colorectal cancer before and after contrast administration were 43 ± 15 HU and 124 ± 18 HU, respectively. The mean attenuation value of solid fecal residuals was 43 ± 15 HU. The difference in attenuation value between precontrast and postcontrast studies of polyps was statistically significant (mean 60 HU, p < 0.01); the same was true for colorectal cancer (mean 81 HU, p < 0.01). The difference between postcontrast density of polyps and cancer with respect to density of solid fecal residuals was statistically significant (p < 0.01). The use of contrast medium could be of help in computed tomographic colonography for discriminating polypoid benign lesions and colorectal cancer from fecal residuals.

CT Colonography: Role of a second reader CAD paradigm in the initial training of radiologists

PURPOSE To evaluate the influence of CAD for the evaluation of CT colonography (CTC) datasets by inexperienced readers during the attendance of a dedicated hands-on training course. METHOD AND MATERIALS Twenty-seven radiologists inexperienced in CTC (11 with no CTC training at all, 16 having previously reviewed no more than 10 CTC cases overall) attended a hands-on training course based on direct teaching on fifteen workstations (four Advantage Windows 4.4 with Colon VCAR software, GE; six CADCOLON, Im3D; five ColonScreen (Toshiba/Voxar) with ColonCAD™ API, Medicsight). During the course, readers were instructed to analyze 26 CTC cases including 38 colonic lesions obtained through low-dose MDCT acquisitions, consisting of 12 polyps sized less than 6 mm, 9 polyps sized between 6 and 10 mm, 12 polyps sized between 11 mm and 30 mm, and 5 colonic masses sized>3 cm. CTC images were reviewed by each reader both in 2D and 3D mode, respectively by direct evaluation of native axial images and MPR reconstructions, and virtual endoscopy or dissected views. Each reader had 15 min time for assessing each dataset without CAD, after which results were compared with those provided by CAD software. Global rater sensitivity for each lesion size before and after CAD usage was compared by means of two-tailed Students t test, while sensitivity of each single reader before and after CAD usage was assessed with the McNemar test. RESULTS For lesions sized<6 mm, global rater sensitivity was 0.1852±0.1656 (mean±SD) before CAD-assisted reading and 0.2345±0.1761 after CAD (p=0.0018). For lesions sized 6-9 mm, sensitivity was 0.2870±0.1016 before CAD-assisted reading and 0.3117±0.1099 after CAD (p=0.0027). For lesions sized 10-30 mm, sensitivity was 0.5308±0.2120 before CAD-assisted reading and 0.5637±0.2133 after CAD (p=0.0086), while for lesions sized>30 mm, sensitivity before CAD-assisted reading was 0.3556±0.3105 and did not change after CAD usage (p=1). Sensitivity of each single rater did not significantly differ before and after CAD for any lesion size category (McNemar test, p>0.05). Specificity was not significantly different before and after CAD for any lesion size (>96% for all size categories). CONCLUSION CAD usage led to increased overall sensitivity of inexperienced readers for all polyps sizes, except for lesions>30 mm, but sensitivity of individual raters was not significantly higher compared with CAD-unassisted reading.

Ileocecal valve imaging on computed tomographic colonography

BackgroundThe aim of our study was to describe the visualization, normal anatomy, and variations of the ileocecal valve with computed tomographic (CT) colonography to provide information about its optimal imaging.MethodsWe analyzed data in two- and three-dimensional rendering mode in 71 consecutive patients who underwent routine CT colonoscopy followed by conventional colonoscopy for confirmation of the radiologic findings.ResultsComplete visualization of the ileocecal valve was better achieved in the supine than in the prone position (82% vs. 62%, respectively); the ileocecal valve appeared in 64% of cases in the supine position when it was invisible in prone position (p < 0.0001). Partial visualization of the ileocecal valve was possible in 94% of cases. The ileocecal valve was of labial type in 76%, papillary type in 21%, and lipomatous in 3% of cases. The orifice was identified in 53% of ileocecal valves; in two cases of cecal carcinoma, the normal ileocecal valve morphology was grossly disrupted.ConciusionThe ileocecal valve was at least partly visualized by CT colonoscopy in 94% of cases, more frequently in the supine position. Its most common normal morphology is the labial type. The absence of orifice visualization alone is not a specific sign for neoplasia, but its presence helps distinguish physiologic bulging from neoplasia.

Diagnostic accuracy of CT colonography in patients with positive faecal occult blood test: results of the Italian project Legatumori 2003–2006

PurposeIn the framework of the 3-year project of the Italian Legatumori (2003–2006), we evaluated the diagnostic accuracy of computed tomography (CT) colonography in detecting colorectal lesions in a screening population with positive faecal occult blood test (FOBT).Materials and methodsTwo hundred and thirty asymptomatic subjects (age range 45–80 years) were enrolled in the study. CT colonography was performed with standard patient preparation (no faecal tagging) and a 4-detector-row CT scanner. Image analysis was carried out with primary 2D analysis and the use of 3D endoluminal views to solve difficult cases. Patients were referred for conventional colonoscopy in the following situations: detection of three or more suspected lesions with maximum diameter ≤6 mm; evidence of one or more lesions with maximum diameter >6 mm; presence of colonic masses (maximum diameter >3 cm).ResultsCT colonography detected colonic masses in 12 out of 135 subjects (8%). It generated 93 false positives and 19 false negatives in the identification of diminutive lesions (≤6 mm), and 70 false positives and six false negatives in lesions >6 mm. Sensitivity was 83% in smaller lesions and 93% in lesions >6 mm; specificity was 45% and 59%, respectively.ConclusionsIn a screening population with positive FOBT, CT colonography without faecal tagging and no definite size threshold for the reporting of polyps showed very low specificity but high sensitivity in the detection of all colorectal lesions.RiassuntoObiettiviNell’ambito di un progetto triennale finanziato dalla Legatumori (2003–2006) è stata valutata l’accuratezza diagnostica della CV nel rilievo di lesioni colorettali in una popolazione di screening risultata positiva al test per il SOF.Materiali e metodiSono stati inclusi nello studio 230 soggetti asintomatici. La CV era eseguita con preparazione standard (senza fecal tagging) e apparecchiatura TC a 4 strati. L’analisi delle immagini era effettuata con valutazione primaria 2D e uso delle ricostruzioni 3D nei casi dubbi. L’esame di CC veniva indicato in presenza di: almeno 3 lesioni sospette per polipi con diametro inferiore o uguale a 6 mm, almeno 1 lesione con diametro superiore a 6 mm, o masse coliche (diametro massimo >3 cm).RisultatiLa CV ha consentito la diagnosi di masse coliche in 12/135 (8%) pazienti; ha generato 93 falsi positivi e 19 falsi negativi per polipi di dimensioni minori o uguali a 6 mm, e 70 falsi positivi e 6 falsi negativi per polipi di dimensioni maggiori. La sensibilità era quindi 83% per polipi clinicamente non significativi e 93% per quelli con diametro superiore a 6mm; la specificità rispettivamente di 45% e 59%.ConclusioniIn una popolazione di screening con SOF+, la CV senza fecal tagging e senza l’adozione di un cut off dimensionale nella indicazione alla colonscopia tradizionale, ha evidenziato una bassa specificità, a fronte Pickdi una elevata sensibilità nel rilievo di tutte le lesioni.

Giant fibrovascular polyp of the esophagus-imaging techniques for proper treatment planning: report of two cases.

Giant fibrovascular polyps of the esophagus are rare, benign mesenchymal intraluminal lesions that arise from the cervical esophagus and can reach a very large size. Surgical excision is the treatment of choice, since endoscopic removal alone is not always feasible due to the presence of a very much vascularized stalk in most cases. We present two archetypal cases emphasizing the fact that these lesions can grow to huge masses with various and bizarre clinical presentation and they can arise (although rarely) at the level of the hypopharynx. We also aim to point out the role of imaging in defining the exact origin and characteristics of the stalk (width, vascularization) and the polyp structure (tissue components), thus providing useful information for planning the most appropriate surgical approach.

Diagnostic accuracy of CT colonography in patients with positive faecal occult blood test: results of the Italian project

PurposeIn the framework of the 3-year project of the Italian Legatumori (2003–2006), we evaluated the diagnostic accuracy of computed tomography (CT) colonography in detecting colorectal lesions in a screening population with positive faecal occult blood test (FOBT).Materials and methodsTwo hundred and thirty asymptomatic subjects (age range 45–80 years) were enrolled in the study. CT colonography was performed with standard patient preparation (no faecal tagging) and a 4-detector-row CT scanner. Image analysis was carried out with primary 2D analysis and the use of 3D endoluminal views to solve difficult cases. Patients were referred for conventional colonoscopy in the following situations: detection of three or more suspected lesions with maximum diameter ≤6 mm; evidence of one or more lesions with maximum diameter >6 mm; presence of colonic masses (maximum diameter >3 cm).ResultsCT colonography detected colonic masses in 12 out of 135 subjects (8%). It generated 93 false positives and 19 false negatives in the identification of diminutive lesions (≤6 mm), and 70 false positives and six false negatives in lesions >6 mm. Sensitivity was 83% in smaller lesions and 93% in lesions >6 mm; specificity was 45% and 59%, respectively.ConclusionsIn a screening population with positive FOBT, CT colonography without faecal tagging and no definite size threshold for the reporting of polyps showed very low specificity but high sensitivity in the detection of all colorectal lesions.RiassuntoObiettiviNell’ambito di un progetto triennale finanziato dalla Legatumori (2003–2006) è stata valutata l’accuratezza diagnostica della CV nel rilievo di lesioni colorettali in una popolazione di screening risultata positiva al test per il SOF.Materiali e metodiSono stati inclusi nello studio 230 soggetti asintomatici. La CV era eseguita con preparazione standard (senza fecal tagging) e apparecchiatura TC a 4 strati. L’analisi delle immagini era effettuata con valutazione primaria 2D e uso delle ricostruzioni 3D nei casi dubbi. L’esame di CC veniva indicato in presenza di: almeno 3 lesioni sospette per polipi con diametro inferiore o uguale a 6 mm, almeno 1 lesione con diametro superiore a 6 mm, o masse coliche (diametro massimo >3 cm).RisultatiLa CV ha consentito la diagnosi di masse coliche in 12/135 (8%) pazienti; ha generato 93 falsi positivi e 19 falsi negativi per polipi di dimensioni minori o uguali a 6 mm, e 70 falsi positivi e 6 falsi negativi per polipi di dimensioni maggiori. La sensibilità era quindi 83% per polipi clinicamente non significativi e 93% per quelli con diametro superiore a 6mm; la specificità rispettivamente di 45% e 59%.ConclusioniIn una popolazione di screening con SOF+, la CV senza fecal tagging e senza l’adozione di un cut off dimensionale nella indicazione alla colonscopia tradizionale, ha evidenziato una bassa specificità, a fronte Pickdi una elevata sensibilità nel rilievo di tutte le lesioni.

Pitfalls and Artefacts in Virtual Endoscopy

Artefacts can be defined as false features in the image that significantly alter the interpretation of the patient anatomy and pathology. For the radiologist, the recognition of artefacts is important to avoid incorrect diagnoses, and therefore precise knowledge of them is mandatory. Artefacts as well as other 3D (three-dimensional) representation methods affect virtual endoscopy. The appearance of artefacts in endoluminal views may add further difficulties to the interpretation of virtual endoscopy images (Bode et al. 2001). Artefacts can be grouped into two types, in relation to the phases of virtual endoscopy generation: image acquisition and image processing.

Multidetector-Row CT: Image-Processing Techniques and Clinical Applications

Image processing and three-dimensional (3D) reconstruction of diagnostic images represents a necessary tool for depicting complex anatomical structures and understanding pathological changes in terms of both morphology and function. The importance of 3D reconstructions is evident if we consider that the quantity of native images produced with new-generation cross-sectional techniques has become increasingly large. Volumetric data such as those acquired with multidetector row computed tomography (CT) are particularly well suited to postprocessing. On the other hand the analysis and processing of such data through additional planes over the axial and 3D views is becoming mandatory. Image processing involves operations such as reformatting original CT images and surface and volume rendering. These types of operations are also included in a wide classification which divides the techniques of display of 3D models into projectional and perspective methods. Projectional methods are those in which a 3D volume is projected into a bidimensional plane; in the perspective methods a 3D virtual world is displayed by means of techniques that aim to reproduce the perspective of the human eye looking at the physical world. Projectional methods include CT image-reformatting approaches such as multiplanar reformations (MPR) in the sagittal, coronal, oblique, and curved planes. More specific projection techniques include maximum-intensity projection (MIP) and minimum-intensity projection (MinIP). The reformatting process does not modify the CT data but uses them in off-axis views and displays the images in an orientation different from native acquisition. Surface and volume rendering use algorithms that generate 3D views of sectional two-dimensional data. Surface rendering is based on the extraction of an intermediate surface description of the relevant objects from the volume data, while volume rendering displays the entire volume preserving the whole dynamic range of the image. A more advanced application of surface and volume rendering is represented by virtual endoscopy, which is a simulation of the endoscopic perspective by processing volumetric data sets. The CT acquisition parameters that have a direct effect on the quality of the image processing are section thickness, reconstruction spacing, and pitch. Thin sections and reconstruction spacing allow better postprocessing results by reducing partial volume averaging effects on the longitudinal plane or z-axis (Fig. 3.1). The effect of pitch on 3D imaging of CT data sets is particularly relevant for single-row systems, where the use of high pitch values introduces an increased slice-sensitive profile and consequently determines artifacts on projectional and perspective CONTENTS