To Fill or Not to Fill? – Value of the Administration of Positive Rectal Contrast for CT Evaluation of Diverticular Disease of the Colon

Abstract

Purpose To assess the value of the administration of positive rectal contrast at CT in patients referred for suspected diverticular disease (DD) of the colon. Materials and Methods 460 patients (253 male, 207 female; median age 62 years; interquartile range 24) with clinical suspicion of DD of the colon were included in this retrospective IRB-approved study. CT was performed with i. v. contrast only (n = 328, group M1), i. v. + positive rectal contrast (n = 82, group M2), neither i. v. nor rectal contrast (n = 32, group S1), or positive rectal contrast only (n = 19, group S2). Two readers in consensus evaluated all CT datasets concerning diagnosis of DD (yes/no) and categorized findings (classification of diverticular disease (CDD)). Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values for the diagnosis of DD were calculated for all groups, using either clinical follow-up (n = 335) or intraoperative findings (n = 125) as the reference standard. In patients undergoing surgery, radiological staging of DD was correlated with the histopathology (weighted Cohen-k). Results 224 patients (48.7 %) were diagnosed with DD. The sensitivity, specificity, PPV, and NPV were as follows. Group M1 / M2: 92 %/92 %, 97 %/94 %, 96 %/96 %, 94 %/89 %, respectively; group S1 / S2: 94 %/86 %, 93 %/80 %, 94 %/92 %, 93 %/67 %, respectively. Radiological staging and histopathology correlated substantially in all groups (k = 0.748–0.861). Conclusion Abdominal CT had a high sensitivity and specificity for the diagnosis of DD. Disease staging correlated well with the findings at surgery. Additional positive rectal contrast administration did not have a significant advantage and may therefore be omitted in patients with suspected DD. Key Points: Citation Format

Classification of Diverticular Disease (CDD) – assessment of the intra- and interobserver agreement in abdominal CT scans

“…Although the redefined abscess size of 3 cm does not significantly improve the practical applicability of the CDD classification from the radiological point of view, it reflects the practical approach more accurately, e. g., therapeutic options like percutaneous drainage. Furthermore, when correlating imaging findings in patients with CDD type 2b with intraoperative findings, we found a slight tendency toward overstaging on CT, when the 1 cm threshold was applied [9]. Hence, increasing the size of abscess definition seems to be a reasonable recommendation.…”

“…First, CT image acquisition was not standardized and, depending on additional clinical indications, a wide range of scan protocols was used. However, despite being a frequent examination, until now there is no consensus regarding the scan protocol, and consistent recommendations on how to perform CT examinations in patients with suspected DD are still lacking [9]. Second, the observers had different levels of expertise.…”

“…This retrospective study was approved by the local institutional review board with a waiver of patient consent granted. In our study we used a pre-existing fully characterized patient population in whom imaging was performed for suspected DD from a previous study [9]. A composite endpoint of a consensus reading, intraop-erative findings, and clinical follow-up from that study served as the reference standard.…”

“…In addition, early radiologic imaging is recommended and used to establish the diagnosis [8]. Besides ultrasound, CT has become a mainstay in patients with suspected diverticulitis due to its excellent sensitivity and specificity [9,10]. By means of CT, not only confirmation of DD is feasible, but also assessment of disease stage including treatment stratification, and exclusion of important differential diagnoses.…”

“…The main purpose of this new CDD classification was to establish a more comprehensive and treatment-relevant categorization of separate stages of DD (▶ Table 1). Recent studies have shown that the CDD enables reliable staging of disease severity [9,18].…”