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 Gastrointestinal Imaging

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Hei865
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Number of posts : 11
Country : HONG KONG
Grade (Ex:IET04 or guest) : CM04
Registration date : 2006-09-07

PostSubject: Gastrointestinal Imaging   Mon Oct 09, 2006 12:50 am

PURPOSE: To explore the possibility of a relationship between increased use of computed tomography (CT) for diagnosis of appendicitis and increased occurrence of minimal or subtle CT and surgical findings.

MATERIALS AND METHODS: Two groups, each with 50 consecutive patients who underwent CT before appendectomy in 1997 and 2000, were compared. CT scans and surgery-pathology reports were evaluated on a six-grade scale from normal to abscess or inflammatory mass. The demographics, surgical techniques, hospital stay, and grade distribution for the two groups were compared, and the CT results were correlated with surgical findings.

RESULTS: In 1997, CT was performed in 33% (50 of 152) of patients undergoing appendectomy, as compared with 59% (50 of 85) 3 years later (P < .001). There was excellent correlation between surgical-pathologic and CT grades (weighted , 0.75; P < .001; Spearman rank correlation, 0.83). There was no significant difference in demographics, rate of surgery, or surgical techniques used, but there was a significant decrease in the median surgical-pathologic grades, from 3.0 to 2.5 (P = .05) for all patients and from 3.5 to 2.6 (P = .003) for patients who underwent CT. Similarly, the median CT grade decreased from 4 to 3 (P < .001). Seven patients had subtle CT findings in 1997 compared with 16 in 2000 (P = .004), and there was a significant decrease in mean hospital stay, from 2.8 days ± 4 (SD) to 1.5 days ± 2 (P = .008).

CONCLUSION: With increased CT use, there were less severe imaging findings, including absence of periappendiceal stranding, and a significant decrease in surgical-pathologic severity of appendiceal disease and hospital stay.

The widespread use of computed tomography (CT) for the diagnosis of acute appendicitis is relatively new. Early on, the modality was reserved for evaluation of complications of appendicitis or for patients presenting with atypical symptoms (1–5). Currently, however, CT has become popular among emergency department physicians and surgeons because it has evolved into a quick and accurate examination that provides images that are easy to interpret (6–13). This popularity is due in part to improved scanning techniques, which have followed the evolving CT technology from dynamic incremental scanning (14) to helical scanning (15) and, most recently, to multi–detector row scanning (16). This evolution has led to increased patient comfort and increased accuracy in studies, while the increased availability of scanners has led to an increased use of CT in patients with acute abdominal pain (10,17).

The usefulness of CT has been further strengthened by excellent clinical results despite the variety of often controversial scanning techniques used. Some investigators (8,9,14,18) have observed advantages of using intravenously administered contrast material. Others (19–25) have found studies performed without intravenously administered contrast material to be highly accurate. Similarly, some investigators advocate the use of contrast materials administered gastrointestinally (8,9,14,18), orally (14), or rectally (15), while others do not recommend the use of any contrast material (22). Finally, there are those who advocate focused right lower quadrant scanning (15) and those who have observed value in scanning the entire abdomen and pelvis (8,9). Increasing evidence suggests that nonfocused CT performed with intravenously administered contrast material outweighs the advantages of the focused studies and improves accuracy (9).

Irrespective of technique, however, the CT signs of appendicitis have remained constant. These include enlargement of the appendix with or without contrast material enhancement of the appendiceal wall, periappendiceal stranding or fluid, and presence of an inflammatory mass or abscess in the right lower quadrant (8,14,15,26).

In our clinical practice, we saw an increase in the number of CT scans obtained for the evaluation of acute appendicitis in the late 1990s. During the same period, we also observed an increasing number of patients having appendicitis with subtle CT findings, in particular with borderline enlargement of the appendix and no or minimal periappendiceal stranding. We postulated that increased CT use resulted in earlier scanning that depicted less severe disease. The purpose of this study was to explore the possibility of a relationship between increased use of CT for diagnosis of appendicitis and increased occurrence of minimal or subtle CT and surgical findings.

Patients
We selected two groups, each with 50 consecutive patients who underwent CT before appendectomy: one group in 1997 and the other in 2000. These studies were selected from a computerized search of our institutional database to identify patients who underwent appendectomy from July 1, 1997, to October 1, 2000. Within this span, we selected two periods 3 years apart: one ranging from July 1, 1997, to April 10, 1998 (1997 group) and the other ranging from May 24, 2000, to October 1, 2000 (2000 group). Each period was extended until we identified 50 consecutive patients who underwent CT before appendectomy. The 50 patients in each group were selected from a cohort of 237 patients who underwent appendectomy in the two periods: 152 in 1997 and 85 in 2000.

Image and Report Review
Institutional review board approval for the retrospective review of the charts and images was obtained. We were not required by the board to obtain informed consent from the patients. Each patient received a research identification number, which was used for data analysis. The CT scans were reviewed by two radiologists (V.R. and B.S.) together, and a consensus was reached. Each patient’s surgery and pathology reports were reviewed at the same time by another pair of radiologists (V.R. and G.K.) together, and a consensus was reached. One of the reviewers was in both pairs (V.R.) and was blinded to the results of the other assessment as follows: The other member of the pair chose the patient sequence for review independently and also blocked patient identification. Patient identification did not appear on the images or in the reports at the time of the review.

Additional clinical data were collected by means of computerized search in our institutional data bank by another investigator (M.P.R.). The collected data included demographic information (ie, sex and age), number of appendectomies performed per month, proportion of patients who underwent CT before surgery, surgical technique (laparoscopic or open appendectomy), and length of hospital stay of the patients who underwent appendectomy in the two periods studied.

The hard-copy scans obtained in the 1997 group were reviewed. Because of a change in clinical practice, the scans obtained in the 2000 group were reviewed on a picture archiving and communication system. The surgery and pathology reports were reviewed together, and a combined assessment was made on the basis of a six-grade scale from 0 (normal) to 6 (abscess or inflammatory mass), as defined in the Table. Half grades were allowed. The CT scans were also assessed on the basis of a different six-grade scale from 0 (normal) to 6 (complicated appendicitis), as defined in the Table and shown in Figure 1. Half grades were allowed.
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