CT staging in sigmoid diverticulitis

Transcription

1 CT staging in sigmoid diverticulitis Poster No.: C-1503 Congress: ECR 2012 Type: Scientific Paper Authors: M. Buchberger, B. von Rahden, J. Schmid, W. Kenn, C.-T. Germer, D. Hahn; Würzburg/DE Keywords: Abdomen, Gastrointestinal tract, CT DOI: /ecr2012/C-1503 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 12

2 Purpose CT is considered the diagnostic imaging method of choice in patients with sigmoid diverticulitis [1-3], especially because of its ability to show the extraluminal inflammatory process [4,5]. As diverticulitis is a disease that can present itself in different degrees of severity, it is necessary to know the exact extent of the inflammation for selecting the appropriate treatment. This study was designed to evaluate the accuracy of CT in the visualization of the extent of the inflammation in sigmoid diverticulitis. Methods and Materials This study included a total of 91 patients (48 women and 43 men; median age 60.4 years, ranging from 26 to 89 years) who underwent surgery for sigmoid diverticulitis at the University Hospital of Wuerzburg between August 2008 and May All patients underwent CT scans according to a standardized CT acquisition protocol using oral, rectal (Gastrolux, Sanochemia Diagnsostics, Germany) and intravenous (Imeron 300, Bracco Imaging, Germany; 110ml, flow rate: 3ml/s) contrast medium. A multislice CT scanner (Siemens Somatom Sensation 16, Erlangen, Germany) was used and all scans were conducted at 120kV with 220mAs, as well as applying a care dose. Subsequent CT scans were started with a delay of 70 seconds. The collimation was 0.6mm and the slice thickness was 5mm, including coronal and sagittal reformations. The radiological staging was performed using the Hansen and Stock (H&S) classification [6]. This classification distinguishes acute uncomplicated diverticulitis (type I) from acute complicated (type IIA, IIB, IIC) and chronic recurrent diverticulitis (type III, see Fig. 1 on page 2). The complicated type II is classified into phlegmonous diverticulitis (type IIA, see Fig. 2 on page 3), covered perforated diverticulitis (type IIB, see Fig. 3 on page 4) and free perforated diverticulitis (type IIC), see Table 1 on page 5. The histopathological workup of colon specimens was performed by the Institute of Pathology, University of Wuerzburg. We therefore used a score according to the Hansen and Stock classification for correlation with the CT morphological findings. The histopathological type was regarded as the correct type. To assess the level of interobserver agreement, all CT scans were reviewed by a second radiologist. Agreement was calculated using the kappa index [7]. Images for this section: Page 2 of 12

3 Fig. 1: Chronic recurrent diverticulitis (H&S type III) - axial CT image shows thickened colonic wall, narrowed intestinal lumen, and fistula. Page 3 of 12

4 Fig. 2: Acute complicated diverticulitis (H&S type IIA) - axial CT image shows colonic wall thickening and pericolic inflammatory changes. Page 4 of 12

5 Fig. 3: Acute complicated diverticulitis (H&S type IIB) - axial CT image showing intramural abscess, colonic wall thickening and pericolic inflammation as well as small amount of extraluminal air. Table 1: Classification according to Hansen and Stock and standardized CT criteria [6]. Page 5 of 12

6 Results 19 patients were preoperatively staged as having phlegmonous diverticulitis (type IIA). In ten cases the CT revealed the phlegmonous type while the pathologist classified the specimens as covered perforated type (type IIB). In two cases we found an overstaging (true type I), in another two cases the histopathological workup revealed the chronic recurrent type. Regarding the covered perforated type (IIB), we found conformity in 35 cases and an overstaging in four cases (true type I). In four cases the pathologist classified the findings as type III. In the free perforated type (IIC) we found conformity in all five patients. 16 patients were both histopathologically and radiologically classified as type III. In five cases the radiologist classified type III, however the histopathological evaluation revealed the presence of an acute complicated type (n=1 type IIA, n=4 type IIB). Results are also shown in Table 2 on page 6 and Fig. 4 on page 7. The sensitivity in detecting the phlegmonous type (H&S IIA; n=6) was 83.3%, for the covered perforation (H&S IIB; n=49) 71.4% and 72.7% for the chronic recurrent diverticulitis (H&S type III; n=22). The calculated specificity was 83.5% for type IIA, 81.0% for type IIB and 92.7% for type III. In the presence of free perforation (H&S type IIC; n=5) we found a sensitivity and specificity of 100% (see Table 3 on page 7). Although only five patients were histopathologically classified as type IIA, both radiologists were in agreement that the phlegmonous type was present in 16 cases. In three cases one radiologist classified the CT scans as type IIB. In the covered perforated type we found 32 cases to be in accordance, in ten cases one radiologist classified the CT scans as type IIA, in one case as type IIC. In the free-perforated type we found conformity in four cases, in one case one radiologist classified type IIB. In ten cases both radiologists classified the CT scans as the chronic recurrent type. In eleven cases one radiologist classified the findings as acute diverticulitis (n=6 type I; n=5 type IIA), the other radiologist classified the chronic recurrent type. Altogether the two radiologists only agreed moderately in their diagnosis (kappa=0.598) [8]. Results are also given in Table 4 on page 8 and Fig. 5 on page 8. Images for this section: Page 6 of 12

7 Table 2: Comparison of preoperative and histopathological staging results Fig. 4: Comparison of preoperative and histopathological staging results Page 7 of 12

8 Table 3: Sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) of preoperative staging results. Table 4: Interobserver correlation Page 8 of 12

9 Fig. 5: Interobserver correlation Page 9 of 12

10 Conclusion CT is an accurate tool for staging in sigmoid diverticulitis using the Hansen and Stock classification. Especially in diagnosing type IIB it shows a deficit in terms of an understaging: In ten cases the CT was not able to show a histopathologically verified covered perforation (exemplary image is shown in Fig. 6 on page 10). Thus, the two complicated types IIA and IIB are unable to be identified clearly by CT scans in some cases. In contrast, CT reflects the free perforated type of sigmoid diverticulitis very well. The moderate interobserver agreement also highlights potential difficulties in staging sigmoid diverticulitis by CT, which also results especially from identifying the complicated types IIA and IIB. In ten cases one radiologist classified the findings as type IIA, the second radiologist as type IIB. Regarding the results, one may also assume that CT shows potential deficits in the differentiation between acute and chronic recurrent diverticulitis. Images for this section: Page 10 of 12

11 Fig. 6: Axial CT image of a 59-year-old woman showing a thickened sigmoid wall and inflammatory changes in the pericolic fat (arrow). In this case, the radiologist classified H&S type IIA, however the pathologist classified the findings as type IIB. Page 11 of 12

12 References Werner A, Diehl SJ, Farag-Soliman M, Düber C (2003); Multi-slice spiral CT in routine diagnosis of suspected acute left-sided colonic diverticulitis: a prospective study of 120 patients. Eur Radiol 13: Baker M (2008); Imaging and Interventional Techniques in Acute Left-sided Diverticulitis. J Gastrointest Surg 12: Ambrosetti P; Acute Diverticulitis of the Left Colon (2008); Value of the Initial CT and Timing of Elective Colectomy. J Gastrointest Surg 12: Hachigan MP, Honickman S, Eisenstat TE, Rubin RJ, Salvati EP (1992); Computed tomography in the initial management of acute left-sided diverticulitis. Dis Colon Rectum 35 (12): Ambrosetti P, Jenny A, Becker C, Terrier TF, Morel P (2000); Acute left colonic diverticulitis - compared performance of computed tomography and water-soluble contrast enema: prospective evaluation of 420 patients. Dis Colon Rectum 43 (10): Hansen O, Stock W (1999); [Prophylactic resection in diverticular disease - treatment by precise staging]. Langenbecks Arch Chir Kongressband 116 (Suppl II): Cohen J (1960); A coefficient of agreement for nominal scales. Educational and Psychological Measurement 20: Altman DG (1991); Practical Statistics for Medical Research. Chapman & Hall/ CRC, Boca Raton Personal Information Page 12 of 12