F Cerri

Integrating image processing in PACS

Integration of RIS and PACS services into a single solution has become a widespread reality in daily radiological practice, allowing substantial acceleration of workflow with greater ease of work compared with older generation film-based radiological activity. In particular, the fast and spectacular recent evolution of digital radiology (with special reference to cross-sectional imaging modalities, such as CT and MRI) has been paralleled by the development of integrated RIS--PACS systems with advanced image processing tools (either two- and/or three-dimensional) that were an exclusive task of costly dedicated workstations until a few years ago. This new scenario is likely to further improve productivity in the radiology department with reduction of the time needed for image interpretation and reporting, as well as to cut costs for the purchase of dedicated standalone image processing workstations. In this paper, a general description of typical integrated RIS--PACS architecture with image processing capabilities will be provided, and the main available image processing tools will be illustrated.

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.

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.

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.

Cardio-TC e TC dual source

La disponibilita di apparecchi TC multistrato (TCMS) con risoluzione spaziale longitudinale submillimetrica e tempi di scansione sempre piu ridotti ha aperto la strada alla valutazione del cuore con scanner TC per impieghi universali. Quest’ultima ha tradizionalmente conosciuto serie limitazioni, dovute all’ovvia impossibilita di fermare il movimento cardiaco o, quanto meno, di rallentarlo fino a consentire l’acquisizione di immagini prive di artefatti da movimento, compatibile con la risoluzione temporale degli scanner TC convenzionali e spirali a singolo strato.

Analisi delle immagini: 2D vs 3D

Le immagini acquisite durante l’esame di colonscopia virtuale (CV) possono essere elaborate con software dedicati che consentono sostanzialmente la visualizzazione 2D e la ricostruzione 3D. Tali software, disponibili sul mercato con svariate caratteristiche e potenzialita, consentono la visualizzazione delle immagini native di tomografia computerizzata in modalita di confronto tra l’acquisizione in decubito prono e supino, la navigazione all’interno del lume colico con simulazione endoscopica, la refertazione strutturata dell’esame, marcando i reperti patologici che automaticamente sono inseriti nel referto finale. A queste caratteristiche di base si aggiungono varie modalita di visualizzazione 3D, oltre a quella endoscopica, che caratterizzano ciascun software.